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Archive for the ‘Endocrine Diseases’ Category


Cellular switch molecule for sperm motility control: a novel target for male contraception and infertility treatments

Reporter and Curator: Sudipta Saha, Ph.D.

 

Researchers have discovered the cellular switch that boosts the activity of sperm cells so that they can travel to the egg.  The finding may lead to new options for male contraception as well as treatments for infertility resulting from problems with sperm mobility.

Inside the male reproductive tract, mature sperm are capable of limited movement. This limited movement, however, is not enough to propel them toward the egg when they enter the female reproductive tract. To begin their journey, they must first be activated by the hormone progesterone, which is released by the egg.

The researchers reported that the molecule to which progesterone must bind is the enzyme alpha/beta hydrolase domain containing protein 2 (ABHD2), found in the sperm cell’s outer membrane. Similarly, strategies to bypass or enhance the enzyme might provide therapies for treating infertility resulting from sperm that lack movement capability.

Before a sperm can transition to the hyper-active phase, calcium must pass through the cell’s outer membrane and enter the flagella, the tail-like appendage the cell uses to propel itself. The sperm protein known as CatSper joins with similar proteins in the flagella to allow the entry of calcium.

When the researchers undertook the current study, it was not known whether progesterone interacted directly with CatSper to trigger the calcium influx, or acted on some other molecule (which, in turn, acted on CatSper). Before treating sperm with progesterone, the researchers exposed them to a chemical that inhibits a particular class of enzymes that they believed could include the candidate molecule that acted on CatSper. The hunch proved correct: the treated cells remained inactive after progesterone exposure, indicating that CatSper was not directly involved.

Working with modified progesterone, the researchers eventually isolated ABHD2 from the sperm tails. When the researchers inactivated ABHD2, exposure to progesterone failed to activate the sperm cells, confirming that ABHD2 is the molecular target for progesterone.

All of the technical terminology aside, this means that the researchers have pinned down the cellular switch that boosts the sperm along to the egg, so by blocking the ABHD2 activity, new male birth control methods could be on the way. Conversely, enhancing the enzyme could lead to new treatments for male infertility.

It will be interesting to see how this discovery impacts future research concerning male birth control and infertility treatments. Perhaps it’s the missing piece of information that will quickly yield an effective new male contraception option.

 

SOURCES

http://www.nih.gov/news-events/news-releases/researchers-identify-molecule-needed-sperm-activation

http://www.ncbi.nlm.nih.gov/pubmed/26989199

http://thescienceexplorer.com/brain-and-body/nih-funded-study-made-breakthrough-discovery-could-lead-new-male-birth-control

http://www.jhunewsletter.com/2016/03/31/researchers-find-a-protein-fertilization-catalyst/

 

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Metformin and vitamin B12 deficiency?

Larry H. Bernstein, MD, FCAP, Curator

LPBI

 

Years of taking popular diabetes drug tied to risk of B12 deficiency

 

Long-term Metformin Use and Vitamin B12 Deficiency in the Diabetes Prevention Program Outcomes Study

 

Metformin linked to vitamin B12 deficiency

David Holmes   Nature Reviews Endocrinology(2016)    http://dx.doi.org:/10.1038/nrendo.2016.39

Secondary analysis of data from the Diabetes Prevention Program Outcomes Study (DPPOS), one of the largest and longest studies of metformin treatment in patients at high risk of developing type 2 diabetes mellitus, shows that long-term use of metformin is associated with vitamin B12deficiency.

Aroda, V. R. et al. Long-term metformin use and vitamin B12 deficiency in the Diabetes Prevention Program Outcomes Study. J. Clin. Endocrinol. Metab. http://dx.doi.org/10.1210/jc.2015-3754 (2016)

 

Long-term Follow-up of Diabetes Prevention Program Shows Continued Reduction in Diabetes Development

http://www.diabetes.org/newsroom/press-releases/2014/long-term-follow-up-of-diabetes-prevention-program-shows-reduction-in-diabetes-development.html

San Francisco, California
June 16, 2014

Treatments used to decrease the development of type 2 diabetes continue to be effective an average of 15 years later, according to the latest findings of the Diabetes Prevention Program Outcomes Study, a landmark study funded by the National Institutes of Health (NIH).

The results, presented at the American Diabetes Association’s 74th Scientific Sessions®, come more than a decade after the Diabetes Prevention Program, or DPP, reported its original findings. In 2001, after an average of three years of study, the DPP announced that the study’s two interventions, a lifestyle program designed to reduce weight and increase activity levels and the diabetes medicinemetformin, decreased the development of type 2 diabetes in a diverse group of people, all of whom were at high risk for the disease, by 58 and 31 percent, respectively, compared with a group taking placebo.

The Diabetes Prevention Program Outcomes Study, or DPPOS, was conducted as an extension of the DPP to determine the longer-term effects of the two interventions, including further reduction in diabetes development and whether delaying diabetes would reduce the development of the diabetes complications that can lead to blindness, kidney failure, amputations and heart disease. Funded largely by the NIH’s National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), the new findings show that the lifestyle intervention and metformin treatment have beneficial effects, even years later, but did not reduce microvascular complications.

Delaying Type 2 Diabetes

Participants in the study who were originally assigned to the lifestyle intervention and metformin during DPP continued to have lower rates of type 2 diabetes development than those assigned to placebo, with 27 percent and 17 percent reductions, respectively, after 15 years.

“What we’re finding is that we can prevent or delay the onset of type 2 diabetes, a chronic disease, through lifestyle intervention or with metformin, over a very long period of time,” said David M. Nathan, MD, Chairman of the DPP/DPPOS and Professor of Medicine at Harvard Medical School. “After the initial randomized treatment phase in DPP, all participants were offered lifestyle intervention and the rates of diabetes development fell in the metformin and former placebo groups, leading to a reduction in the treatment group differences over time.  However, the lifestyle intervention and metformin are still quite effective at delaying, if not preventing, type 2 diabetes,” Dr. Nathan said. Currently, an estimated 79 million American adults are at high-risk for developing type 2 diabetes.

Microvascular Complications
The DPPOS investigators followed participants for an additional 12 years after the end of the DPP to determine both the extent of diabetes prevention over time and whether the study treatments would also decrease the small vessel -or microvascular- complications, such as eye, nerve and kidney disease. These long-term results did not demonstrate significant differences among the lifestyle intervention, metformin or placebo groups on the microvascular complications, reported Kieren Mather, MD, Professor of Medicine at Indiana University School of Medicine and a study investigator.

“However, regardless of type of initial treatment, participants who didn’t develop diabetes had a 28 percent lower occurrence of the microvascular complications than those participants who did develop diabetes. These findings show that intervening in the prediabetes phase is important in reducing early stage complications,” Dr. Mather noted. The absence of differences in microvascular complications among the intervention groups may be explained by the small differences in average glucose levels among the groups at this stage of follow-up.

Risk for Cardiovascular Disease

The DPP population was relatively young and healthy at the beginning of the study, and few participants had experienced any severe cardiovascular events, such as heart attack or stroke, 15 years later. The relatively small number of events meant that the DPPOS researchers could not test the effects of interventions on cardiovascular disease. However, the research team did examine whether the study interventions, or a delay in the onset of type 2 diabetes, improved cardiovascular risk factors.

“We found that cardiovascular risk factors, such as hypertension, are generally improved by the lifestyle intervention and somewhat less by metformin,” said Ronald Goldberg, MD, Professor of Medicine at the University of Miami and one of the DPPOS investigators. “We know that people with type 2 diabetes are at much higher risk for heart disease and stroke than those who do not have diabetes, so a delay in risk factor development or improvement in risk factors may prove to be beneficial.”

Long-term Results with Metformin

The DPP/DPPOS is the largest and longest duration study to examine the effects of metformin, an inexpensive, well-known and generally safe diabetes medicine, in people who have not been diagnosed with diabetes. For DPPOS participants, metformin treatment was associated with a modest degree of long-term weight loss. “Other than a small increase in vitamin B-12 deficiency, which is a recognized consequence of metformin therapy, it has been extremely safe and well-tolerated over the 15 years of our study,” said Jill Crandall, MD, Professor of Medicine at Albert Einstein College of Medicine and a DPPOS investigator. “Further study will help show whether metformin has beneficial effects on heart disease and cancer, which are both increased in people with type 2 diabetes.”

Looking to the Future

In addition to the current findings, the DPPOS includes a uniquely valuable population that can help researchers understand the clinical course of type 2 diabetes.  Since the participants did not have diabetes at the beginning of the DPP, for those who have developed diabetes, the data show precisely when they developed the disease, which is rare in previous studies. “The DPP and DPPOS have given us an incredible wealth of information by following a very diverse group of people with regard to race and age as they have progressed from prediabetes to diabetes,” said Judith Fradkin, MD, Director of the NIDDK Division of Diabetes, Endocrinology and Metabolic Diseases. “The study provides us with an opportunity to make crucial discoveries about the clinical course of type 2 diabetes.”

Dr. Fradkin noted that the study population held promise for further analyses because researchers would now be able to examine how developing diabetes at different periods of life may cause the disease to progress differently. “We can look at whether diabetes behaves differently if you develop it before the age of 50 or after the age of 60,” she said. “Thanks to the large and diverse population of DPPOS that has remained very loyal to the study, we will be able to see how and when complications first develop and understand how to intervene most effectively.”

She added that NIDDK had invited the researchers to submit an application for a grant to follow the study population for an additional 10 years.

The Diabetes Prevention Program Outcomes Study was funded under NIH grant U01DK048489 by the NIDDK; National Institute on Aging; National Cancer Institute; National Heart, Lung, and Blood Institute; National Eye Institute; National Center on Minority Health and Health Disparities; and the Office of the NIH Director; Eunice Kennedy Shriver National Institute of Child Health and Human Development; Office of Research on Women’s Health; and Office of Dietary Supplements, all part of the NIH, as well as the Indian Health Service, Centers for Disease Control and Prevention and American Diabetes Association. Funding in the form of supplies was provided by Merck Sante, Merck KGaA and LifeScan.

The American Diabetes Association is leading the fight to Stop Diabetes® and its deadly consequences and fighting for those affected by diabetes. The Association funds research to prevent, cure and manage diabetes; delivers services to hundreds of communities; provides objective and credible information; and gives voice to those denied their rights because of diabetes. Founded in 1940, our mission is to prevent and cure diabetes and to improve the lives of all people affected by diabetes. For more information please call the American Diabetes Association at 1-800-DIABETES (1-800-342-2383) or visit http://www.diabetes.org. Information from both these sources is available in English and Spanish.

Association of Biochemical B12Deficiency With Metformin Therapy and Vitamin B12Supplements  

The National Health and Nutrition Examination Survey, 1999–2006

Lael ReinstatlerYan Ping QiRebecca S. WilliamsonJoshua V. Garn, and Godfrey P. Oakley Jr.
Diabetes Care February 2012 vol. 35 no. 2 327-333 
     http://dx.doi.org:/10.2337/dc11-1582

OBJECTIVE To describe the prevalence of biochemical B12deficiency in adults with type 2 diabetes taking metformin compared with those not taking metformin and those without diabetes, and explore whether this relationship is modified by vitamin B12supplements.

RESEARCH DESIGN AND METHODS Analysis of data on U.S. adults ≥50 years of age with (n = 1,621) or without type 2 diabetes (n = 6,867) from the National Health and Nutrition Examination Survey (NHANES), 1999–2006. Type 2 diabetes was defined as clinical diagnosis after age 30 without initiation of insulin therapy within 1 year. Those with diabetes were classified according to their current metformin use. Biochemical B12 deficiency was defined as serum B12concentrations ≤148 pmol/L and borderline deficiency was defined as >148 to ≤221 pmol/L.

RESULTS Biochemical B12 deficiency was present in 5.8% of those with diabetes using metformin compared with 2.4% of those not using metformin (P = 0.0026) and 3.3% of those without diabetes (P = 0.0002). Among those with diabetes, metformin use was associated with biochemical B12 deficiency (adjusted odds ratio 2.92; 95% CI 1.26–6.78). Consumption of any supplement containing B12 was not associated with a reduction in the prevalence of biochemical B12deficiency among those with diabetes, whereas consumption of any supplement containing B12 was associated with a two-thirds reduction among those without diabetes.

CONCLUSIONS Metformin therapy is associated with a higher prevalence of biochemical B12 deficiency. The amount of B12recommended by the Institute of Medicine (IOM) (2.4 μg/day) and the amount available in general multivitamins (6 μg) may not be enough to correct this deficiency among those with diabetes.

It is well known that the risks of both type 2 diabetes and B12deficiency increase with age (1,2). Recent national data estimate a 21.2% prevalence of diagnosed diabetes among adults ≥65 years of age and a 6 and 20% prevalence of biochemical B12 deficiency (serum B12<148 pmol/L) and borderline deficiency (serum B12 ≥148–221 pmol/L) among adults ≥60 years of age (3,4).

The diabetes drug metformin has been reported to cause a decrease in serum B12 concentrations. In the first efficacy trial, DeFronzo and Goodman (5) demonstrated that although metformin offers superior control of glycosylated hemoglobin levels and fasting plasma glucose levels compared with glyburide, serum B12 concentrations were lowered by 22% compared with placebo, and 29% compared with glyburide therapy after 29 weeks of treatment. A recent, randomized control trial designed to examine the temporal relationship between metformin and serum B12 found a 19% reduction in serum B12 levels compared with placebo after 4 years (6). Several other randomized control trials and cross-sectional surveys reported reductions in B12ranging from 9 to 52% (716). Although classical B12 deficiency presents with clinical symptoms such as anemia, peripheral neuropathy, depression, and cognitive impairment, these symptoms are usually absent in those with biochemical B12 deficiency (17).

Several researchers have made recommendations to screen those with type 2 diabetes on metformin for serum B12 levels (6,7,1416,1821). However, no formal recommendations have been provided by the medical community or the U.S. Prevention Services Task Force. High-dose B12 injection therapy has been successfully used to correct the metformin-induced decline in serum B12 (15,21,22). The use of B12supplements among those with type 2 diabetes on metformin in a nationally representative sample and their potentially protective effect against biochemical B12 deficiency has not been reported. It is therefore the aim of the current study to use the nationally representative National Health and Nutrition Examination Survey (NHANES) population to determine the prevalence of biochemical B12deficiency among those with type 2 diabetes ≥50 years of age taking metformin compared with those with type 2 diabetes not taking metformin and those without diabetes, and to explore how these relationships are modified by B12 supplement consumption.

Design overview

NHANES is a nationally representative sample of the noninstitutionalized U.S. population with targeted oversampling of U.S. adults ≥60 years of age, African Americans, and Hispanics. Details of these surveys have been described elsewhere (23). All participants gave written informed consent, and the survey protocol was approved by a human subjects review board.

Setting and participants

Our study included adults ≥50 years of age from NHANES 1999–2006. Participants with positive HIV antibody test results, high creatinine levels (>1.7 mg/dL for men and >1.5 mg/dL for women), and prescription B12 injections were excluded from the analysis. Participants who reported having prediabetes or borderline diabetes (n = 226) were removed because they could not be definitively grouped as having or not having type 2 diabetes. We also excluded pregnant women, those with type 1 diabetes, and those without diabetes taking metformin. Based on clinical aspects described by the American Diabetes Association and previous work in NHANES, those who were diagnosed before the age of 30 and began insulin therapy within 1 year of diagnosis were classified as having type 1 diabetes (24,25). Type 2 diabetes status in adults was dichotomized as yes/no. Participants who reported receiving a physician’s diagnosis after age 30 (excluding gestational diabetes) and did not initiate insulin therapy within 1 year of diagnosis were classified as having type 2 diabetes.

Outcomes and follow-up

The primary outcome was biochemical B12 deficiency determined by serum B12 concentrations. Serum B12 levels were quantified using the Quantaphase II folate/vitamin B12 radioassay kit from Bio-Rad Laboratories (Hercules, CA). We defined biochemical B12 deficiency as serum levels ≤148 pmol/L, borderline deficiency as serum B12 >148 to ≤221 pmol/L, and normal as >221 pmol/L (26).

The main exposure of interest was metformin use. Using data collected in the prescription medicine questionnaire, those with type 2 diabetes were classified as currently using metformin therapy (alone or in combination therapy) versus those not currently using metformin. Length of metformin therapy was used to assess the relationship between duration of metformin therapy and biochemical B12 deficiency. In the final analysis, two control groups were used to allow the comparison of those with type 2 diabetes taking metformin with those with type 2 diabetes not taking metformin and those without diabetes.

To determine whether the association between metformin and biochemical B12 deficiency is modified by supplemental B12 intake, data from the dietary supplement questionnaire were used. Information regarding the dose and frequency was used to calculate average daily supplemental B12 intake. We categorized supplemental B12 intake as 0 μg (no B12 containing supplement), >0–6 μg, >6–25 μg, and >25 μg. The lower intake group, >0–6 μg, includes 6 μg, the amount of vitamin B12 typically found in over-the-counter multivitamins, and 2.4 μg, the daily amount the IOM recommends for all adults ≥50 years of age to consume through supplements or fortified food (1). The next group, >6–25 μg, includes 25 μg, the amount available in many multivitamins marketed toward senior adults. The highest group contains the amount found in high-dose B-vitamin supplements.

 

In the final analysis, there were 575 U.S. adults ≥50 years of age with type 2 diabetes using metformin, 1,046 with type 2 diabetes not using metformin, and 6,867 without diabetes. The demographic and biological characteristics of the groups are shown in Table 1. Among metformin users, mean age was 63.4 ± 0.5 years, 50.3% were male, 66.7% were non-Hispanic white, and 40.7% used a supplement containing B12. The median duration of metformin use was 5 years. Compared with those with type 2 diabetes not taking metformin, metformin users were younger (P < 0.0001), reported a lower prevalence of insulin use (P < 0.001), and had a shorter duration of diabetes (P = 0.0207). Compared with those without diabetes, metformin users had a higher proportion of nonwhite racial groups (P< 0.0001), a higher proportion of obesity (P < 0.0001), a lower prevalence of macrocytosis (P = 0.0017), a lower prevalence of supplemental folic acid use (P = 0.0069), a lower prevalence of supplemental vitamin B12 use (P = 0.0180), and a lower prevalence of calcium supplement use (P = 0.0002). There was a twofold difference in the prevalence of anemia among those with type 2 diabetes versus those without, and no difference between the groups with diabetes.    

Association of Biochemical B12Deficiency With Metformin Therapy and Vitamin B12Supplements

Demographic and biological characteristics of U.S. adults ≥50 years of age: NHANES 1999–2006

Table 1
The geometric mean serum B12 concentration among those with type 2 diabetes taking metformin was 317.5 pmol/L. This was significantly lower than the geometric mean concentration in those with type 2 diabetes not taking metformin (386.7 pmol/L; P = 0.0116) and those without diabetes (350.8 pmol/L; P = 0.0011). As seen in Fig. 1, the weighted prevalence of biochemical B12 deficiency adjusted for age, race, and sex was 5.8% for those with type 2 diabetes taking metformin, 2.2% for those with type 2 diabetes not taking metformin (P = 0.0002), and 3.3% for those without diabetes (P = 0.0026). Among the three aforementioned groups, borderline deficiency was present in 16.2, 5.5, and 8.8%, respectively (P < 0.0001). Applying the Fleiss formula for calculating attributable risk from cross-sectional data (27), among all of the cases of biochemical B12 deficiency, 3.5% of the cases were attributable to metformin use; and among those with diabetes, 41% of the deficient cases were attributable to metformin use. When the prevalence of biochemical B12 deficiency among those with diabetes taking metformin was analyzed by duration of metformin therapy, there was no notable increase in the prevalence of biochemical B12 deficiency as the duration of metformin use increased. The prevalence of biochemical B12 deficiency was 4.1% among those taking metformin <1 year, 6.3% among those taking metformin ≥1–3 years, 4.1% among those taking metformin >3–10 years, and 8.1% among those taking metformin >10 years (P = 0.3219 for <1 year vs. >10 years). Similarly, there was no clear increase in the prevalence of borderline deficiency as the duration of metformin use increased (15.9% among those taking metformin >10 years vs. 11.4% among those taking metformin <1 year; P = 0.4365).
Figure 1
Weighted prevalence of biochemical B12 deficiency and borderline deficiency adjusted for age, race, and sex in U.S. adults ≥50 years of age: NHANES 1999–2006. Black bars are those with type 2 diabetes on metformin, gray bars are those with type 2 diabetes not on metformin, and the white bars are those without diabetes. *P = 0.0002 vs. type 2 diabetes on metformin. †P < 0.0001 vs. type 2 diabetes on metformin. ‡P = 0.0026 vs. type 2 diabetes on metformin.
Table 2 presents a stratified analysis of the weighted prevalence of biochemical B12 deficiency and borderline deficiency by B12supplement use. For those without diabetes, B12 supplement use was associated with an ∼66.7% lower prevalence of both biochemical B12deficiency (4.8 vs. 1.6%; P < 0.0001) and borderline deficiency (16.6 vs. 5.5%; P < 0.0001). A decrease in the prevalence of biochemical B12deficiency was seen at all levels of supplemental B12 intake compared with nonusers of supplements. Among those with type 2 diabetes taking metformin, supplement use was not associated with a decrease in the prevalence of either biochemical B12 deficiency (5.6 vs. 5.3%; P= 0.9137) or borderline deficiency (15.5 vs. 8.8%; P = 0.0826). Among the metformin users who also used supplements, those who consumed >0–6 μg of B12 had a prevalence of biochemical B12 deficiency of 14.1%. However, consumption of a supplement containing >6 μg of B12 was associated with a prevalence of biochemical B12 deficiency of 1.8% (P = 0.0273 for linear trend). Similar trends were seen in the association of supplemental B12 intake and the prevalence of borderline deficiency. For those with type 2 diabetes not taking metformin, supplement use was also not associated with a decrease in the prevalence of biochemical B12 deficiency (2.1 vs. 2.0%; P = 0.9568) but was associated with a 54% reduction in the prevalence of borderline deficiency (7.8 vs. 3.4%; P = 0.0057 for linear trend).
Table 2
Comparison of average daily B12 supplement intake by weighted prevalence of biochemical B12 deficiency (serum B12 ≤148 pmol/L) and borderline deficiency (serum B12 >148 to ≤221 pmol/L) among U.S. adults ≥50 years of age: NHANES 1999–2006.
Table 3 demonstrates the association of various risk factors with biochemical B12 deficiency. Metformin therapy was associated with biochemical B12 deficiency (odds ratio [OR] 2.89; 95% CI 1.33–6.28) and borderline deficiency (OR 2.32; 95% CI 1.31–4.12) in a crude model (results not shown). After adjusting for age, BMI, and insulin and supplement use, metformin maintained a significant association with biochemical B12 deficiency (OR 2.92; 95% CI 1.28–6.66) and borderline deficiency (OR 2.16; 95% CI 1.22–3.85). Similar to Table 2, B12 supplements were protective against borderline (OR 0.43; 95% CI 0.23–0.81), but not biochemical, B12 deficiency (OR 0.76; 95% CI 0.34–1.70) among those with type 2 diabetes. Among those without diabetes, B12 supplement use was ∼70% protective against biochemical B12 deficiency (OR 0.26; 95% CI 0.17–0.38) and borderline deficiency (OR 0.27; 95% CI 0.21–0.35).
Table 3
Polytomous logistic regression for potential risk factors of biochemical B12 deficiency and borderline deficiency among U.S. adults ≥50 years of age: NHANES 1999–2006, OR (95% CI)

The IOM has highlighted the detection and diagnosis of B12 deficiency as a high-priority topic for research (1). Our results suggest several findings that add to the complexity and importance of B12 research and its relation to diabetes, and offer new insight into the benefits of B12 supplements. Our data confirm the relationship between metformin and reduced serum B12 levels beyond the background prevalence of biochemical B12 deficiency. Our data demonstrate that an intake of >0–6 μg of B12, which includes the dose most commonly found in over-the-counter multivitamins, was associated with a two-thirds reduction of biochemical B12 deficiency and borderline deficiency among adults without diabetes. This relationship has been previously reported with NHANES and Framingham population data (4,29). In contrast, we did not find that >0–6 μg of B12 was associated with a decrease in the prevalence of biochemical B12 deficiency or borderline deficiency among adults with type 2 diabetes taking metformin. This observation suggests that metformin reduces serum B12 by a mechanism that is additive to or different from the mechanism in older adults. It is also possible that metformin may exacerbate the deficiency among older adults with low serum B12. Our sample size was too small to determine which amount >6 μg was associated with maximum protection, but we did find a dose-response trend.

We were surprised to find that those with type 2 diabetes not using metformin had the lowest prevalence of biochemical B12 deficiency. It is possible that these individuals may seek medical care more frequently than the general population and therefore are being treated for their biochemical B12 deficiency. Or perhaps, because this population had a longer duration of diabetes and a higher proportion of insulin users compared with metformin users, they have been switched from metformin to other diabetic treatments due to low serum B12 concentrations or uncontrolled glucose levels and these new treatments may increase serum B12 concentrations. Despite the observed effects of metformin on serum B12 levels, it remains unclear whether or not this reduction is a public health concern. With lifetime risks of diabetes estimated to be one in three and with metformin being a first-line intervention, it is important to increase our understanding of the effects of oral vitamin B12 on metformin-associated biochemical deficiency (20,21).

The strengths of this study include its nationally representative, population-based sample, its detailed information on supplement usage, and its relevant biochemical markers. This is the first study to use a nationally representative sample to examine the association between serum B12 concentration, diabetes status, and metformin use as well as examine how this relationship may be modified by vitamin B12 supplementation. The data available regarding supplement usage provided specific information regarding dose and frequency. This aspect of NHANES allowed us to observe the dose-response relationship in Table 2 and to compare it within our three study groups.

This study is also subject to limitations. First, NHANES is a cross-sectional survey and it cannot assess time as a factor, and therefore the results are associations and not causal relationships. A second limitation arises in our definition of biochemical B12 deficiency. There is no general consensus on how to define normal versus low serum B12levels. Some researchers include the functional biomarker methylmalonic acid (MMA) in the definition, but this has yet to be agreed upon (3034). Recently, an NHANES roundtable discussion suggested that definitions of biochemical B12 deficiency should incorporate one biomarker (serum B12 or holotranscobalamin) and one functional biomarker (MMA or total homocysteine) to address problems with sensitivity and specificity of the individual biomarkers. However, they also cited a need for more research on how the biomarkers are related in the general population to prevent misclassification (34). MMA was only measured for six of our survey years; one-third of participants in our final analysis were missing serum MMA levels. Moreover, it has recently been reported that MMA values are significantly greater among the elderly with diabetes as compared with the elderly without diabetes even when controlling for serum B12 concentrations and age, suggesting that having diabetes may independently increase the levels of MMA (35). This unique property of MMA in elderly adults with diabetes makes it unsuitable as part of a definition of biochemical B12 deficiency in our specific population groups. Our study may also be subject to misclassification bias. NHANES does not differentiate between diabetes types 1 and 2 in the surveys; our definition may not capture adults with type 2 diabetes exclusively. Additionally, we used responses to the question “Have you received a physician’s diagnosis of diabetes” to categorize participants as having or not having diabetes. Therefore, we failed to capture undiagnosed diabetes. Finally, we could only assess current metformin use. We cannot determine if nonmetformin users have ever used metformin or if they were not using it at the time of the survey.

Our data demonstrate several important conclusions. First, there is a clear association between metformin and biochemical B12 deficiency among adults with type 2 diabetes. This analysis shows that 6 μg of B12 offered in most multivitamins is associated with two-thirds reduction in biochemical B12 deficiency in the general population, and that this same dose is not associated with protection against biochemical B12 deficiency among those with type 2 diabetes taking metformin. Our results have public health and clinical implications by suggesting that neither 2.4 μg, the current IOM recommendation for daily B12 intake, nor 6 μg, the amount found in most multivitamins, is sufficient for those with type 2 diabetes taking metformin.

This analysis suggests a need for further research. One research design would be to identify those with biochemical B12 deficiency and randomize them to receive various doses of supplemental B12chronically and then evaluate any improvement in serum B12concentrations and/or clinical outcomes. Another design would use existing cohorts to determine clinical outcomes associated with biochemical B12 deficiency and how they are affected by B12supplements at various doses. Given that a significant proportion of the population ≥50 years of age have biochemical B12 deficiency and that those with diabetes taking metformin have an even higher proportion of biochemical B12 deficiency, we suggest that support for further research is a reasonable priority.

 

Discussion:
One research design would be to identify those with biochemical B12 deficiency and randomize them to receive various doses of supplemental B12chronically and then evaluate any improvement in serum B12concentrations and/or clinical outcomes. Another design would use existing cohorts to determine clinical outcomes associated with biochemical B12 deficiency and how they are affected by B12supplements at various doses.
This is of considerable interest.  As far as I can see, there is insufficient data presented to discern all of the variables entangled.  In a study of 8000 hemograms several years ago, it was of some interest that there were a large percentage of patients who were over age 75 years having a MCV of 94 – 100, not considered indicative of macrocytic anemia.  It would have been interesting to explore that set of the data further.

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Dopamine-β-Hydroxylase Functional Variants

Curator: Larry H. Bernstein, MD, FCAP

 

 

Deep sequencing identifies novel regulatory variants in the distal promoter region of the dopamine-β-hydroxylase gene.

OBJECTIVE:

Dopamine-β-hydroxylase (DBH), an enzyme that converts dopamine into norepinephrine, is a drug target in cardiovascular and neuropsychiatric disorders. We aimed to identify functional variants in this gene by deep sequencing and enzyme phenotyping in an Indian cohort.

MATERIALS AND METHODS:

Targeted resequencing of 12 exons and 10 kb upstream sequences of DBH in healthy volunteers (n=50) was performed using the Ion Personal Genome Machine System. Enzyme quantity and activity in their sera samples were determined by ELISA and ultra performance liquid chromatography, respectively. The association of markers with phenotypes was determined using Matrix eQTL. Global P-values for haplotypes generated using UNPHASED 3.1.5 were graphed using GrASP v.082 beta.

RESULTS:

Of the 49 variants identified, nine were novel (minor allele frequency≥0.01). Though individual markers associated with enzyme quantity did not withstand multiple corrections, a novel distal promoter block driven by rs113249250 (global P=1.5×10) was associated. Of the nine single nucleotide polymorphisms (SNPs) associated with enzyme activity, rs3025369, rs1076151 and rs1611115, all from the upstream region, withstood false discovery rate correction (false discovery rate=0.03, 0.03 and 2.9×10, respectively). Conditioning for rs1611115 identified rs1989787 also to affect activity. Importantly, we report an association of a novel haplotype block distal to rs1076151 driven by rs3025369 (global P=8.9×10) with enzyme activity. This regulatory SNP explained 4.9% of the total 46.1% of variance in DBH activity caused by associated SNPs.

CONCLUSION:

This first study combining deep sequencing and enzyme phenotyping identified yet another regulatory SNP suggesting that regulatory variants may be central in the physiological or metabolic role of this gene of therapeutic and pharmacological relevance.

 

 

Correlation of plasma dopamine beta-hydroxylase activity with polymorphisms in DBH gene: a study on Eastern Indian population.

Plasma dopamine beta-hydroxylase activity (plDbetaH) is tightly regulated by the DBH gene and several genetic polymorphisms have been found to independently exert their influence. In the present investigation, association of four DBH polymorphisms, DBH-STR, rs1611115, rs1108580, and rs2519152 with plDbetaH was examined in blood samples from 100 unrelated individuals belonging to the state of West Bengal, Eastern India. Genotypes obtained after PCR amplification and restriction digestion were used for statistical analyses. plDbetaH was measured using a photometric assay and its correlation with the genetic polymorphisms was analyzed using analysis of variance and linear regression. Moderate linkage disequilibrium (LD) was observed between DBH-STR and rs1611115, while rs1108580 and rs2519152 were in strong LD. ‘T’ allele of rs1611115 showed strong negative correlation with plDbetaH, whereas DBH-STR, rs1108580 and rs2519152 had no major effect. Four haplotypes showed significant influence on plDbetaH. This is the first report on the effect of genetic polymorphisms on plDbetaH from the Indian sub-continent. rs1611115 was the only polymorphism that showed substantial control over plDbetaH. Other polymorphisms which did not show individual effects could possibly be part of larger haplotype blocks that carry the functional polymorphisms controlling plDbetaH.
Polymorphisms and low plasma activity of dopamine-beta-hydroxylase in ADHD children.
Attention-deficit Hyperactivity disorder (ADHD) is a multifactorial disorder clinically characterized by inattentiveness, impulsivity and hyperactivity. The occurrence of this disorder is between 3 and 6% of the children population, with boys predominating over girls at a ratio of 3:1 or more. The research of some candidate genes (DRD4, DAT, DRD5, DBH, 5HTT, HTR1B and SNAP25) brought consistent results confirming the heredity of ADHD syndromes. Dopamine-beta-hydroxylase (DBH) is an enzyme responsible for the conversion of dopamine into noradrenaline. Alteration of the dopamine/noradrenaline levels can result in hyperactivity. The DBH protein is released in response to stimulation. DBH activity, derived largely from sympathetic nerves, can be measured in human plasma. Patients with ADHD showed decreased activities of DBH in serum and urine. Low DBH levels correlate indirectly with the seriousness of the hyperkinetic syndrome in children [19,20]. In the DBH gene, the G444A, G910T, C1603T, C1912T, C-1021T, 5 -ins/del and TaqI polymorphisms occur frequently and may affect the function of gene products or modify gene expression and thus influence the progression of ADHD. This article reviews the DBH itself and polymorphisms in the DBH gene that influence the DBH activity in the serum and the CSF level of DBH. All those are evaluated in connection with ADHD.
Candidate gene studies of attention-deficit/hyperactivity disorder.
A growing body of behavioral and molecular genetics literature has indicated that the development of attention-deficit/hyperactivity disorder (ADHD) may be attributed to both genetic and environmental factors. Family, twin, and adoption studies provide compelling evidence that genes play a strong role in mediating susceptibility to ADHD. Molecular genetic studies suggest that the genetic architecture of ADHD is complex, while the handful of genome-wide scans conducted thus far is not conclusive. In contrast, the many candidate gene studies of ADHD have produced substantial evidence implicating several genes in the etiology of the disorder. For the 8 genes for which the same variant has been studied in 3 or more case-control or family-based studies, 7 show statistically significant evidence of association with ADHD based on pooled odds ratios across studies: the dopamine D4 receptor gene (DRD4), the dopamine D5 receptor gene (DRD5), the dopamine transporter gene (DAT), the dopamine beta-hydroxylase gene (DBH), the serotonin transporter gene (5-HTT), the serotonin receptor 1B gene (HTR1B), and the synaptosomal-associated protein 25 gene (SNAP25). Recent pharmacogenetic studies have correlated treatment nonresponse with particular gene markers, while preclinical studies have increased our understanding of gene expression paradigms and potential analogs for human trials. This literature review discusses the relevance and implications of genetic associations with ADHD for clinical practice and future research
Lack of significant association between -1021C–>T polymorphism in the dopamine beta hydroxylase gene and attention deficit hyperactivity disorder.
Recent trends in medications for attention deficit hyperactivity disorder (ADHD) suggest that norepinephrine (NE) deficiency may contribute to the disease etiology. Dopamine beta hydroxylase (DBH) is the key enzyme which converts dopamine to NE and since DBH gene is considered a major quantitative trait locus for plasma DBH activity, genetic polymorphism may lead to altered NE neurotransmission. Several polymorphisms including a 5′ flanking -1021C–>T polymorphism, was reported to be associated with changed DBH activity and an association between -1021C–>T polymorphism with ADHD was observed in Han Chinese children. We have carried out family-based studies with three polymorphisms in the DBH gene, -1021C–>T polymorphism, exon 2*444g/a and intron 5 TaqI RFLP, to explore their association with Indian ADHD cases. Allele and genotype frequency of these polymorphisms in ADHD cases were compared with that of their parents and a control group. Haplotypes obtained were analyzed for linkage disequilibrium (LD). Haplotype-based haplotype relative risk analysis and transmission disequilibrium test showed lack of significant association between transmission of the polymorphisms and ADHD. A haplotype comprising of allele 1 of all polymorphisms showed a slight positive trend towards transmission from parents to ADHD probands. Strong LD was observed between *444g/a and TaqI RFLP in all the groups. However, low D’ values and corresponding log of odds scores in the control group as compared to the ADHD families indicated that, the incidence of the two polymorphisms being transmitted together could be higher in ADHD families.
Association of the dopamine beta hydroxylase gene with attention deficit hyperactivity disorder: genetic analysis of the Milwaukee longitudinal study.
Attention deficit hyperactivity disorder (ADHD) is a highly heritable and common disorder that partly reflects disturbed dopaminergic function in the brain. Recent genetic studies have shown that candidate genes involved in dopamine signaling and metabolism contribute to ADHD susceptibility. We have initiated genetic studies in a unique cohort of 158 ADHD and 81 control adult subjects who have been followed longitudinally since childhood in the Milwaukee study of ADHD. From this cohort, genetic analysis was performed in 105 Caucasian subjects with ADHD and 68 age and ethnicity-matched controls for the DRD4 exon 3 VNTR, the SLC6A3 (DAT1) 3′ UTR VNTR, dopamine beta hydroxylase (DBH) TaqI A polymorphism, and the DBH GT microsatellite repeat polymorphism that has been quantitatively associated with serum levels of DBH activity, but not previously studied in ADHD. Results indicate a significant association between the DBH TaqI A1 allele and ADHD (P = 0.018) with a relative risk of 1.33. The DBH GT repeat 4 allele, which is associated with high serum levels of DBH, occurred more frequently in the ADHD group than controls, but the difference did not reach statistical significance. Associations were not found with the SLC6A3 10 repeat or DRD4 7 repeat alleles. These results indicate that the DBH TaqI A allele, or another polymorphism in linkage disequilibrium with this allele, may confer increased susceptibility towards ADHD.
Polymorphisms of the dopamine transporter gene: influence on response to methylphenidate in attention deficit-hyperactivity disorder.
Attention deficit-hyperactivity disorder (ADHD) is a very common and heterogeneous childhood-onset psychiatric disorder, affecting between 3% and 5% of school age children worldwide. Although the neurobiology of ADHD is not completely understood, imbalances in both dopaminergic and noradrenergic systems have been implicated in the origin and persistence of core symptoms, which include inattention, hyperactivity, and impulsivity. The role of a genetic component in its etiology is strongly supported by genetic studies, and several investigations have suggested that the dopamine transporter gene (DAT1; SLC6A3 locus) may be a small-effect susceptibility gene for ADHD. Stimulant medication has a well-documented efficacy in reducing ADHD symptoms. Methylphenidate, the most prescribed stimulant, seems to act mainly by inhibiting the dopamine transporter protein and dopamine reuptake. In fact, its effect is probably related to an increase in extracellular levels of dopamine, especially in brain regions enriched in this protein (i.e. striatum). It is also important to note that dopamine transporter densities seem to be particularly elevated in the brain of ADHD patients, decreasing after treatment with methylphenidate. Altogether, these observations suggest that the dopamine transporter does play a major role in ADHD. Among the several polymorphisms already described in the SLC6A3 locus, a 40 bp variable number of tandem repeats (VNTR) polymorphism has been extensively investigated in association studies with ADHD. Although there are some negative results, the findings from these reports indicate the allele with ten copies of the 40 bp sequence (10-repeat allele) as the risk allele for ADHD. Some investigations have suggested that this polymorphism can be implicated in dopamine transporter gene expression in vitro and dopamine transporter density in vivo, even though it is located in a non-coding region of the SLC6A3 locus. Despite all these data, few studies have addressed the relationship between genetic markers (specifically the VNTR) at the SLC6A3 locus and response to methylphenidate in ADHD patients. A significant effect of the 40 bp VNTR on response to methylphenidate has been detected in most of these reports. However, the findings are inconsistent regarding both the allele (or genotype) involved and the direction of this influence (better or worse response). Thus, further investigations are required to determine if genetic variation due to the VNTR in the dopamine transporter gene is able to predict different levels of clinical response and palatability to methylphenidate in patients with ADHD, and how this information would be useful in clinical practice.
Pharmacogenomics in psychiatry: the relevance of receptor and transporter polymorphisms.
The treatment of severe mental illness, and of psychiatric disorders in general, is limited in its efficacy and tolerability. There appear to be substantial interindividual differences in response to psychiatric drug treatments that are generally far greater than the differences between individual drugs; likewise, the occurrence of adverse effects also varies profoundly between individuals. These differences are thought to reflect, at least in part, genetic variability. The action of psychiatric drugs primarily involves effects on synaptic neurotransmission; the genes for neurotransmitter receptors and transporters have provided strong candidates in pharmacogenetic research in psychiatry. This paper reviews some aspects of the pharmacogenetics of neurotransmitter receptors and transporters in the treatment of psychiatric disorders. A focus on serotonin, catecholamines and amino acid transmitter systems reflects the direction of research efforts, while relevant results from some genome-wide association studies are also presented. There are many inconsistencies, particularly between candidate gene and genome-wide association studies. However, some consistency is seen in candidate gene studies supporting established pharmacological mechanisms of antipsychotic and antidepressant response with associations of functional genetic polymorphisms in, respectively, the dopamine D2 receptor and serotonin transporter and receptors. More recently identified effects of genes related to amino acid neurotransmission on the outcome of treatment of schizophrenia, bipolar illness or depression reflect the growing understanding of the roles of glutamate and γ-aminobutyric acid dysfunction in severe mental illness. A complete understanding of psychiatric pharmacogenomics will also need to take into account epigenetic factors, such as DNA methylation, that influence individual responses to drugs.
Pharmacogenetics of psychotropic drug response.

OBJECTIVE:

Molecular genetic approaches provide a novel method of dissecting the heterogeneity of psychotropic drug response. These pharmacogenetic strategies offer the prospect of identifying biological predictors of psychotropic drug response and could provide the means of determining the molecular substrates of drug efficacy and drug-induced adverse events.

METHOD:

The authors discuss methods issues in executing pharmacogenetic studies, review the first generation of pharmacogenetic studies of psychotropic drug response, and consider future directions for this rapidly evolving field.

RESULTS:

Pharmacogenetics has been most commonly used in studies of antipsychotic drug efficacy, antidepressant drug response, and drug-induced adverse effects. Data from antipsychotic drug studies indicate that polymorphisms within the serotonin 2A and dopamine receptor 2 genes may influence drug efficacy in schizophrenia. Moreover, a growing body of data suggests a relationship between the serotonin transporter gene and clinical effects of the selective serotonin reuptake inhibitors used to treat depression. A significant relationship between genetic variation in the cytochrome P450 system and drug-induced adverse effects may exist for certain medications. Finally, a number of independent studies point to a significant effect of a dopamine D(3) receptor polymorphism on susceptibility to tardive dyskinesia.

CONCLUSIONS:

Initial research into the pharmacogenetics of psychotropic drug response suggests that specific genes may influence phenotypes associated with psychotropic drug administration. These results remain preliminary and will require further replication and validation. New developments in molecular biology, human genomic information, statistical methods, and bioinformatics are ongoing and could pave the way for the next generation of pharmacogenetic studies in psychiatry.

OBJECTIVE: Molecular genetic approaches provide a novel method of dissecting the heterogeneity of psychotropic drug response. These pharmacogenetic strategies offer the prospect of identifying biological predictors of psychotropic drug response and could provide the means of determining the molecular substrates of drug efficacy and drug-induced adverse events. METHOD: The authors discuss methods issues in executing pharmacogenetic studies, review the first generation of pharmacogenetic studies of psychotropic drug response, and consider future directions for this rapidly evolving field. RESULTS: Pharmacogenetics has been most commonly used in studies of antipsychotic drug efficacy, antidepressant drug response, and drug-induced adverse effects. Data from antipsychotic drug studies indicate that polymorphisms within the serotonin 2A and dopamine receptor 2 genes may influence drug efficacy in schizophrenia. Moreover, a growing body of data suggests a relationship between the serotonin transporter gene and clinical effects of the selective serotonin reuptake inhibitors used to treat depression. A significant relationship between genetic variation in the cytochrome P450 system and drug-induced adverse effects may exist for certain medications. Finally, a number of independent studies point to a significant effect of a dopamine D3 receptor polymorphism on susceptibility to tardive dyskinesia. CONCLUSIONS: Initial research into the pharmacogenetics of psychotropic drug response suggests that specific genes may influence phenotypes associated with psychotropic drug administration. These results remain preliminary and will require further replication and validation. New developments in molecular biology, human genomic information, statistical methods, and bioinformatics are ongoing and could pave the way for the next generation of pharmacogenetic studies in psychiatry.

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Christopher J. Lynch, MD, PhD, the New Office of Nutrition Research, Director

Curator: Larry H. Bernstein, MD, FCAP

 

Christopher J. Lynch to direct Office of Nutrition Research

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

http://www.nih.gov/news-events/news-releases/christopher-j-lynch-direct-office-nutrition-research

 

Christopher J. Lynch, Ph.D., has been named the new director of the Office of Nutrition Research (ONR) and chief of the Nutrition Research Branch within the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Lynch officially assumed his new roles on Feb. 21, 2016. NIDDK is part of the National Institutes of Health.

Lynch will facilitate nutrition research within NIDDK and — through ONR — across NIH, in part by forming and leading a trans-NIH strategic working group. He will also continue and extend ongoing efforts at NIDDK to collaborate widely to advance nutrition research.

“Dr. Lynch is a leader in the nutrition community and his expertise will be vital to guiding the NIH strategic plan for nutrition research,” said NIH Director Francis S. Collins, M.D., Ph.D.  “As NIH works to expand nutrition knowledge, Dr. Lynch’s understanding of the field will help identify information gaps and create a framework to support future discoveries to ultimately improve human health.”

NIH supports a broad range of nutrition research, including studies on the effects of nutrient and dietary intake on human growth and disease, genetic influences on human nutrition and metabolism and other scientific areas. ONR was established in August 2015 to help NIH develop a strategic plan to expand mission-specific nutrition research.

NARRATIVE:
Our laboratory is dedicated to developing cures for metabolic diseases like Obesity, Diabetes and MSUD. We have several projects:
Project 1: How Antipsychotic Drugs Exert Obesity and Metabolic Disease Side effects
Project 2: Impact of Branched Chain Amino Acid (BCAA) signaling and metabolism in obesity and diabetes.
Project 3: Adipose tissue transplant as a treatment for Maple Syrup Urine Disease.
Project 4: How Gastric Bypass Surgery Provides A Rapid Cure For Diabetes And Other Obesity Co-Morbidities Like Hypertension
Project 5: Novel Mechanism Of Action Of Cannabinoid Receptor 1 Blockers For Improvement Of Diabetes

Timeline

  1. Klingerman CM, Stipanovic ME, Hajnal A, Lynch CJ. Acute Metabolic Effects of Olanzapine Depend on Dose and Injection Site. Dose Response. 2015 Oct-Dec; 13(4):1559325815618915.

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  1. Lynch CJ, Kimball SR, Xu Y, Salzberg AC, Kawasawa YI. Global deletion of BCATm increases expression of skeletal muscle genes associated with protein turnover. Physiol Genomics. 2015 Nov; 47(11):569-80.

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  1. Lynch CJ, Xu Y, Hajnal A, Salzberg AC, Kawasawa YI. RNA sequencing reveals a slow to fast muscle fiber type transition after olanzapine infusion in rats. PLoS One. 2015; 10(4):e0123966.

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  1. Shin AC, Fasshauer M, Filatova N, Grundell LA, Zielinski E, Zhou JY, Scherer T, Lindtner C, White PJ, Lapworth AL, Ilkayeva O, Knippschild U, Wolf AM, Scheja L, Grove KL, Smith RD, Qian WJ, Lynch CJ, Newgard CB, Buettner C. Brain Insulin Lowers Circulating BCAA Levels by Inducing Hepatic BCAA Catabolism. Cell Metab. 2014 Nov 4; 20(5):898-909.

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  1. Lynch CJ, Adams SH. Branched-chain amino acids in metabolic signalling and insulin resistance. Nat Rev Endocrinol. 2014 Dec; 10(12):723-36.

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  1. Olson KC, Chen G, Xu Y, Hajnal A, Lynch CJ. Alloisoleucine differentiates the branched-chain aminoacidemia of Zucker and dietary obese rats. Obesity (Silver Spring). 2014 May; 22(5):1212-5.

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  1. Zimmerman HA, Olson KC, Chen G, Lynch CJ. Adipose transplant for inborn errors of branched chain amino acid metabolism in mice. Mol Genet Metab. 2013 Aug; 109(4):345-53.

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  1. Olson KC, Chen G, Lynch CJ. Quantification of branched-chain keto acids in tissue by ultra fast liquid chromatography-mass spectrometry. Anal Biochem. 2013 Aug 15; 439(2):116-22.

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  1. She P, Olson KC, Kadota Y, Inukai A, Shimomura Y, Hoppel CL, Adams SH, Kawamata Y, Matsumoto H, Sakai R, Lang CH, Lynch CJ. Leucine and protein metabolism in obese Zucker rats. PLoS One. 2013; 8(3):e59443.

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  1. Lackey DE, Lynch CJ, Olson KC, Mostaedi R, Ali M, Smith WH, Karpe F, Humphreys S, Bedinger DH, Dunn TN, Thomas AP, Oort PJ, Kieffer DA, Amin R, Bettaieb A, Haj FG, Permana P, Anthony TG, Adams SH. Regulation of adipose branched-chain amino acid catabolism enzyme expression and cross-adipose amino acid flux in human obesity. Am J Physiol Endocrinol Metab. 2013 Jun 1; 304(11):E1175-87.

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  1. Klingerman CM, Stipanovic ME, Bader M, Lynch CJ. Second-generation antipsychotics cause a rapid switch to fat oxidation that is required for survival in C57BL/6J mice. Schizophr Bull. 2014 Mar; 40(2):327-40.

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  1. Carr TD, DiGiovanni J, Lynch CJ, Shantz LM. Inhibition of mTOR suppresses UVB-induced keratinocyte proliferation and survival. Cancer Prev Res (Phila). 2012 Dec; 5(12):1394-404.

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  1. Lynch CJ, Zhou Q, Shyng SL, Heal DJ, Cheetham SC, Dickinson K, Gregory P, Firnges M, Nordheim U, Goshorn S, Reiche D, Turski L, Antel J. Some cannabinoid receptor ligands and their distomers are direct-acting openers of SUR1 K(ATP) channels. Am J Physiol Endocrinol Metab. 2012 Mar 1; 302(5):E540-51.

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  1. Albaugh VL, Singareddy R, Mauger D, Lynch CJ. A double blind, placebo-controlled, randomized crossover study of the acute metabolic effects of olanzapine in healthy volunteers. PLoS One. 2011; 6(8):e22662.

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  1. She P, Zhang Z, Marchionini D, Diaz WC, Jetton TJ, Kimball SR, Vary TC, Lang CH, Lynch CJ. Molecular characterization of skeletal muscle atrophy in the R6/2 mouse model of Huntington’s disease. Am J Physiol Endocrinol Metab. 2011 Jul; 301(1):E49-61.

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  1. Fogle RL, Hollenbeak CS, Stanley BA, Vary TC, Kimball SR, Lynch CJ. Functional proteomic analysis reveals sex-dependent differences in structural and energy-producing myocardial proteins in rat model of alcoholic cardiomyopathy. Physiol Genomics. 2011 Apr 12; 43(7):346-56.

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  1. Zhou Y, Jetton TL, Goshorn S, Lynch CJ, She P. Transamination is required for {alpha}-ketoisocaproate but not leucine to stimulate insulin secretion. J Biol Chem. 2010 Oct 29; 285(44):33718-26.

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  1. Agostino NM, Chinchilli VM, Lynch CJ, Koszyk-Szewczyk A, Gingrich R, Sivik J, Drabick JJ. Effect of the tyrosine kinase inhibitors (sunitinib, sorafenib, dasatinib, and imatinib) on blood glucose levels in diabetic and nondiabetic patients in general clinical practice. J Oncol Pharm Pract. 2011 Sep; 17(3):197-202.

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  1. Li J, Romestaing C, Han X, Li Y, Hao X, Wu Y, Sun C, Liu X, Jefferson LS, Xiong J, Lanoue KF, Chang Z, Lynch CJ, Wang H, Shi Y. Cardiolipin remodeling by ALCAT1 links oxidative stress and mitochondrial dysfunction to obesity. Cell Metab. 2010 Aug 4; 12(2):154-65.

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  1. Culnan DM, Albaugh V, Sun M, Lynch CJ, Lang CH, Cooney RN. Ileal interposition improves glucose tolerance and insulin sensitivity in the obese Zucker rat. Am J Physiol Gastrointest Liver Physiol. 2010 Sep; 299(3):G751-60.

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  1. Hajnal A, Kovacs P, Ahmed T, Meirelles K, Lynch CJ, Cooney RN. Gastric bypass surgery alters behavioral and neural taste functions for sweet taste in obese rats. Am J Physiol Gastrointest Liver Physiol. 2010 Oct; 299(4):G967-79.

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  1. Lang CH, Lynch CJ, Vary TC. BCATm deficiency ameliorates endotoxin-induced decrease in muscle protein synthesis and improves survival in septic mice. Am J Physiol Regul Integr Comp Physiol. 2010 Sep; 299(3):R935-44.

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  1. Albaugh VL, Vary TC, Ilkayeva O, Wenner BR, Maresca KP, Joyal JL, Breazeale S, Elich TD, Lang CH, Lynch CJ. Atypical antipsychotics rapidly and inappropriately switch peripheral fuel utilization to lipids, impairing metabolic flexibility in rodents. Schizophr Bull. 2012 Jan; 38(1):153-66.

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  1. Fogle RL, Lynch CJ, Palopoli M, Deiter G, Stanley BA, Vary TC. Impact of chronic alcohol ingestion on cardiac muscle protein expression. Alcohol Clin Exp Res. 2010 Jul; 34(7):1226-34.

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  1. Lang CH, Frost RA, Bronson SK, Lynch CJ, Vary TC. Skeletal muscle protein balance in mTOR heterozygous mice in response to inflammation and leucine. Am J Physiol Endocrinol Metab. 2010 Jun; 298(6):E1283-94.

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  1. Albaugh VL, Judson JG, She P, Lang CH, Maresca KP, Joyal JL, Lynch CJ. Olanzapine promotes fat accumulation in male rats by decreasing physical activity, repartitioning energy and increasing adipose tissue lipogenesis while impairing lipolysis. Mol Psychiatry. 2011 May; 16(5):569-81.

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  1. Lang CH, Lynch CJ, Vary TC. Alcohol-induced IGF-I resistance is ameliorated in mice deficient for mitochondrial branched-chain aminotransferase. J Nutr. 2010 May; 140(5):932-8.

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  1. She P, Zhou Y, Zhang Z, Griffin K, Gowda K, Lynch CJ. Disruption of BCAA metabolism in mice impairs exercise metabolism and endurance. J Appl Physiol (1985). 2010 Apr; 108(4):941-9.

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  1. Herman MA, She P, Peroni OD, Lynch CJ, Kahn BB. Adipose tissue branched chain amino acid (BCAA) metabolism modulates circulating BCAA levels. J Biol Chem. 2010 Apr 9; 285(15):11348-56.

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  1. Li P, Knabe DA, Kim SW, Lynch CJ, Hutson SM, Wu G. Lactating porcine mammary tissue catabolizes branched-chain amino acids for glutamine and aspartate synthesis. J Nutr. 2009 Aug; 139(8):1502-9.

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  1. Lu G, Sun H, She P, Youn JY, Warburton S, Ping P, Vondriska TM, Cai H, Lynch CJ, Wang Y. Protein phosphatase 2Cm is a critical regulator of branched-chain amino acid catabolism in mice and cultured cells. J Clin Invest. 2009 Jun; 119(6):1678-87.

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  1. Nairizi A, She P, Vary TC, Lynch CJ. Leucine supplementation of drinking water does not alter susceptibility to diet-induced obesity in mice. J Nutr. 2009 Apr; 139(4):715-9.

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  1. Meirelles K, Ahmed T, Culnan DM, Lynch CJ, Lang CH, Cooney RN. Mechanisms of glucose homeostasis after Roux-en-Y gastric bypass surgery in the obese, insulin-resistant Zucker rat. Ann Surg. 2009 Feb; 249(2):277-85.

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  1. Culnan DM, Cooney RN, Stanley B, Lynch CJ. Apolipoprotein A-IV, a putative satiety/antiatherogenic factor, rises after gastric bypass. Obesity (Silver Spring). 2009 Jan; 17(1):46-52.

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  1. She P, Van Horn C, Reid T, Hutson SM, Cooney RN, Lynch CJ. Obesity-related elevations in plasma leucine are associated with alterations in enzymes involved in branched-chain amino acid metabolism. Am J Physiol Endocrinol Metab. 2007 Dec; 293(6):E1552-63.

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  1. She P, Reid TM, Bronson SK, Vary TC, Hajnal A, Lynch CJ, Hutson SM. Disruption of BCATm in mice leads to increased energy expenditure associated with the activation of a futile protein turnover cycle. Cell Metab. 2007 Sep; 6(3):181-94.

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  1. Vary TC, Lynch CJ. Nutrient signaling components controlling protein synthesis in striated muscle. J Nutr. 2007 Aug; 137(8):1835-43.

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  1. Vary TC, Deiter G, Lynch CJ. Rapamycin limits formation of active eukaryotic initiation factor 4F complex following meal feeding in rat hearts. J Nutr. 2007 Aug; 137(8):1857-62.

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  1. Vary TC, Anthony JC, Jefferson LS, Kimball SR, Lynch CJ. Rapamycin blunts nutrient stimulation of eIF4G, but not PKCepsilon phosphorylation, in skeletal muscle. Am J Physiol Endocrinol Metab. 2007 Jul; 293(1):E188-96.

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  1. Vary TC, Lynch CJ. Meal feeding stimulates phosphorylation of multiple effector proteins regulating protein synthetic processes in rat hearts. J Nutr. 2006 Sep; 136(9):2284-90.

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  1. Lynch CJ, Gern B, Lloyd C, Hutson SM, Eicher R, Vary TC. Leucine in food mediates some of the postprandial rise in plasma leptin concentrations. Am J Physiol Endocrinol Metab. 2006 Sep; 291(3):E621-30.

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  1. Albaugh VL, Henry CR, Bello NT, Hajnal A, Lynch SL, Halle B, Lynch CJ. Hormonal and metabolic effects of olanzapine and clozapine related to body weight in rodents. Obesity (Silver Spring). 2006 Jan; 14(1):36-51.

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  1. Vary TC, Lynch CJ. Meal feeding enhances formation of eIF4F in skeletal muscle: role of increased eIF4E availability and eIF4G phosphorylation. Am J Physiol Endocrinol Metab. 2006 Apr; 290(4):E631-42.

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  1. Vary TC, Goodman S, Kilpatrick LE, Lynch CJ. Nutrient regulation of PKCepsilon is mediated by leucine, not insulin, in skeletal muscle. Am J Physiol Endocrinol Metab. 2005 Oct; 289(4):E684-94.

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  1. Vary TC, Lynch CJ. Biochemical approaches for nutritional support of skeletal muscle protein metabolism during sepsis. Nutr Res Rev. 2004 Jun; 17(1):77-88.

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  1. Lynch CJ, Halle B, Fujii H, Vary TC, Wallin R, Damuni Z, Hutson SM. Potential role of leucine metabolism in the leucine-signaling pathway involving mTOR. Am J Physiol Endocrinol Metab. 2003 Oct; 285(4):E854-63.

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  1. Lynch CJ, Hutson SM, Patson BJ, Vaval A, Vary TC. Tissue-specific effects of chronic dietary leucine and norleucine supplementation on protein synthesis in rats. Am J Physiol Endocrinol Metab. 2002 Oct; 283(4):E824-35.

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  1. Lynch CJ, Patson BJ, Anthony J, Vaval A, Jefferson LS, Vary TC. Leucine is a direct-acting nutrient signal that regulates protein synthesis in adipose tissue. Am J Physiol Endocrinol Metab. 2002 Sep; 283(3):E503-13.

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  1. Vary TC, Lynch CJ, Lang CH. Effects of chronic alcohol consumption on regulation of myocardial protein synthesis. Am J Physiol Heart Circ Physiol. 2001 Sep; 281(3):H1242-51.

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  1. Lynch CJ, Patson BJ, Goodman SA, Trapolsi D, Kimball SR. Zinc stimulates the activity of the insulin- and nutrient-regulated protein kinase mTOR. Am J Physiol Endocrinol Metab. 2001 Jul; 281(1):E25-34.

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Global deletion of BCATm increases expression of skeletal muscle genes associated with protein turnover.

Lynch CJ1Kimball SR2Xu Y2Salzberg AC3Kawasawa YI4.   Author information
Physiol Genomics. 2015 Nov;47(11):569-80.  http://dx.doi.org:/10.1152/physiolgenomics.00055.2015

Consumption of a protein-containing meal by a fasted animal promotes protein accretion in skeletal muscle, in part through leucine stimulation of protein synthesis and indirectly through repression of protein degradation mediated by its metabolite, α-ketoisocaproate. Mice lacking the mitochondrial branched-chain aminotransferase (BCATm/Bcat2), which interconverts leucine and α-ketoisocaproate, exhibit elevated protein turnover. Here, the transcriptomes of gastrocnemius muscle from BCATm knockout (KO) and wild-type mice were compared by next-generation RNA sequencing (RNA-Seq) to identify potential adaptations associated with their persistently altered nutrient signaling. Statistically significant changes in the abundance of 1,486/∼39,010 genes were identified. Bioinformatics analysis of the RNA-Seq data indicated that pathways involved in protein synthesis [eukaryotic initiation factor (eIF)-2, mammalian target of rapamycin, eIF4, and p70S6K pathways including 40S and 60S ribosomal proteins], protein breakdown (e.g., ubiquitin mediated), and muscle degeneration (apoptosis, atrophy, myopathy, and cell death) were upregulated. Also in agreement with our previous observations, the abundance of mRNAs associated with reduced body size, glycemia, plasma insulin, and lipid signaling pathways was altered in BCATm KO mice. Consistently, genes encoding anaerobic and/or oxidative metabolism of carbohydrate, fatty acids, and branched chain amino acids were modestly but systematically reduced. Although there was no indication that muscle fiber type was different between KO and wild-type mice, a difference in the abundance of mRNAs associated with a muscular dystrophy phenotype was observed, consistent with the published exercise intolerance of these mice. The results suggest transcriptional adaptations occur in BCATm KO mice that along with altered nutrient signaling may contribute to their previously reported protein turnover, metabolic and exercise phenotypes.

 

RNA sequencing reveals a slow to fast muscle fiber type transition after olanzapine infusion in rats.

Lynch CJ1Xu Y1Hajnal A2Salzberg AC3Kawasawa YI4. Author information
PLoS One. 2015 Apr 20;10(4):e0123966. http://dx.doi.org:/10.1371/journal.pone.0123966. eCollection 2015.

Second generation antipsychotics (SGAs), like olanzapine, exhibit acute metabolic side effects leading to metabolic inflexibility, hyperglycemia, adiposity and diabetes. Understanding how SGAs affect the skeletal muscle transcriptome could elucidate approaches for mitigating these side effects. Male Sprague-Dawley rats were infused intravenously with vehicle or olanzapine for 24h using a dose leading to a mild hyperglycemia. RNA-Seq was performed on gastrocnemius muscle, followed by alignment of the data with the Rat Genome Assembly 5.0. Olanzapine altered expression of 1347 out of 26407 genes. Genes encoding skeletal muscle fiber-type specific sarcomeric, ion channel, glycolytic, O2- and Ca2+-handling, TCA cycle, vascularization and lipid oxidation proteins and pathways, along with NADH shuttles and LDH isoforms were affected. Bioinformatics analyses indicate that olanzapine decreased the expression of slower and more oxidative fiber type genes (e.g., type 1), while up regulating those for the most glycolytic and least metabolically flexible, fast twitch fiber type, IIb. Protein turnover genes, necessary to bring about transition, were also up regulated. Potential upstream regulators were also identified. Olanzapine appears to be rapidly affecting the muscle transcriptome to bring about a change to a fast-glycolytic fiber type. Such fiber types are more susceptible than slow muscle to atrophy, and such transitions are observed in chronic metabolic diseases. Thus these effects could contribute to the altered body composition and metabolic disease olanzapine causes. A potential interventional strategy is implicated because aerobic exercise, in contrast to resistance exercise, can oppose such slow to fast fiber transitions.

 

Brain insulin lowers circulating BCAA levels by inducing hepatic BCAA catabolism.

Shin AC1Fasshauer M1Filatova N1Grundell LA1Zielinski E1Zhou JY2Scherer T1Lindtner C1White PJ3Lapworth AL3,Ilkayeva O3Knippschild U4Wolf AM4Scheja L5Grove KL6Smith RD2Qian WJ2Lynch CJ7Newgard CB3Buettner C8. Author information
Cell Metab. 2014 Nov 4;20(5):898-909. http://dx.doi.org:/10.1016/j.cmet.2014.09.003   Epub 2014 Oct 9

Circulating branched-chain amino acid (BCAA) levels are elevated in obesity/diabetes and are a sensitive predictor for type 2 diabetes. Here we show in rats that insulin dose-dependently lowers plasma BCAA levels through induction of hepatic protein expression and activity of branched-chain α-keto acid dehydrogenase (BCKDH), the rate-limiting enzyme in the BCAA degradation pathway. Selective induction of hypothalamic insulin signaling in rats and genetic modulation of brain insulin receptors in mice demonstrate that brain insulin signaling is a major regulator of BCAA metabolism by inducing hepatic BCKDH. Short-term overfeeding impairs the ability of brain insulin to lower BCAAs in rats. High-fat feeding in nonhuman primates and obesity and/or diabetes in humans is associated with reduced BCKDH protein in liver. These findings support the concept that decreased hepatic BCKDH is a major cause of increased plasma BCAAs and that hypothalamic insulin resistance may account for impaired BCAA metabolism in obesity and diabetes.

 

Branched-chain amino acids in metabolic signalling and insulin resistance.

Lynch CJ1Adams SH2Author information
Nat Rev Endocrinol. 2014 Dec; 10(12):723-36. http://dx.doi.org:/10.1038/nrendo.2014.171

Branched-chain amino acids (BCAAs) are important nutrient signals that have direct and indirect effects. Frequently, BCAAs have been reported to mediate antiobesity effects, especially in rodent models. However, circulating levels of BCAAs tend to be increased in individuals with obesity and are associated with worse metabolic health and future insulin resistance or type 2 diabetes mellitus (T2DM). A hypothesized mechanism linking increased levels of BCAAs and T2DM involves leucine-mediated activation of the mammalian target of rapamycin complex 1 (mTORC1), which results in uncoupling of insulin signalling at an early stage. A BCAA dysmetabolism model proposes that the accumulation of mitotoxic metabolites (and not BCAAs per se) promotes β-cell mitochondrial dysfunction, stress signalling and apoptosis associated with T2DM. Alternatively, insulin resistance might promote aminoacidaemia by increasing the protein degradation that insulin normally suppresses, and/or by eliciting an impairment of efficient BCAA oxidative metabolism in some tissues. Whether and how impaired BCAA metabolism might occur in obesity is discussed in this Review. Research on the role of individual and model-dependent differences in BCAA metabolism is needed, as several genes (BCKDHA, PPM1K, IVD and KLF15) have been designated as candidate genes for obesity and/or T2DM in humans, and distinct phenotypes of tissue-specific branched chain ketoacid dehydrogenase complex activity have been detected in animal models of obesity and T2DM.

 

Leucine and protein metabolism in obese Zucker rats.

She P1Olson KCKadota YInukai AShimomura YHoppel CLAdams SHKawamata YMatsumoto HSakai RLang CHLynch CJAuthor information
PLoS One. 2013;8(3):e59443. http://dx.doi.org:/10.1371/journal.pone.0059443   Epub 2013 Mar 20.

Branched-chain amino acids (BCAAs) are circulating nutrient signals for protein accretion, however, they increase in obesity and elevations appear to be prognostic of diabetes. To understand the mechanisms whereby obesity affects BCAAs and protein metabolism, we employed metabolomics and measured rates of [1-(14)C]-leucine metabolism, tissue-specific protein synthesis and branched-chain keto-acid (BCKA) dehydrogenase complex (BCKDC) activities. Male obese Zucker rats (11-weeks old) had increased body weight (BW, 53%), liver (107%) and fat (∼300%), but lower plantaris and gastrocnemius masses (-21-24%). Plasma BCAAs and BCKAs were elevated 45-69% and ∼100%, respectively, in obese rats. Processes facilitating these rises appeared to include increased dietary intake (23%), leucine (Leu) turnover and proteolysis [35% per g fat free mass (FFM), urinary markers of proteolysis: 3-methylhistidine (183%) and 4-hydroxyproline (766%)] and decreased BCKDC per g kidney, heart, gastrocnemius and liver (-47-66%). A process disposing of circulating BCAAs, protein synthesis, was increased 23-29% by obesity in whole-body (FFM corrected), gastrocnemius and liver. Despite the observed decreases in BCKDC activities per gm tissue, rates of whole-body Leu oxidation in obese rats were 22% and 59% higher normalized to BW and FFM, respectively. Consistently, urinary concentrations of eight BCAA catabolism-derived acylcarnitines were also elevated. The unexpected increase in BCAA oxidation may be due to a substrate effect in liver. Supporting this idea, BCKAs were elevated more in liver (193-418%) than plasma or muscle, and per g losses of hepatic BCKDC activities were completely offset by increased liver mass, in contrast to other tissues. In summary, our results indicate that plasma BCKAs may represent a more sensitive metabolic signature for obesity than BCAAs. Processes supporting elevated BCAA]BCKAs in the obese Zucker rat include increased dietary intake, Leu and protein turnover along with impaired BCKDC activity. Elevated BCAAs/BCKAs may contribute to observed elevations in protein synthesis and BCAA oxidation.

 

Regulation of adipose branched-chain amino acid catabolism enzyme expression and cross-adipose amino acid flux in human obesity.

Lackey DE1Lynch CJOlson KCMostaedi RAli MSmith WHKarpe FHumphreys SBedinger DHDunn TNThomas APOort PJKieffer DAAmin RBettaieb AHaj FGPermana PAnthony TGAdams SH.
Am J Physiol Endocrinol Metab. 2013 Jun 1; 304(11):E1175-87. http://dx.doi.org:/10.1152/ajpendo.00630.2012

Elevated blood branched-chain amino acids (BCAA) are often associated with insulin resistance and type 2 diabetes, which might result from a reduced cellular utilization and/or incomplete BCAA oxidation. White adipose tissue (WAT) has become appreciated as a potential player in whole body BCAA metabolism. We tested if expression of the mitochondrial BCAA oxidation checkpoint, branched-chain α-ketoacid dehydrogenase (BCKD) complex, is reduced in obese WAT and regulated by metabolic signals. WAT BCKD protein (E1α subunit) was significantly reduced by 35-50% in various obesity models (fa/fa rats, db/db mice, diet-induced obese mice), and BCKD component transcripts significantly lower in subcutaneous (SC) adipocytes from obese vs. lean Pima Indians. Treatment of 3T3-L1 adipocytes or mice with peroxisome proliferator-activated receptor-γ agonists increased WAT BCAA catabolism enzyme mRNAs, whereas the nonmetabolizable glucose analog 2-deoxy-d-glucose had the opposite effect. The results support the hypothesis that suboptimal insulin action and/or perturbed metabolic signals in WAT, as would be seen with insulin resistance/type 2 diabetes, could impair WAT BCAA utilization. However, cross-tissue flux studies comparing lean vs. insulin-sensitive or insulin-resistant obese subjects revealed an unexpected negligible uptake of BCAA from human abdominal SC WAT. This suggests that SC WAT may not be an important contributor to blood BCAA phenotypes associated with insulin resistance in the overnight-fasted state. mRNA abundances for BCAA catabolic enzymes were markedly reduced in omental (but not SC) WAT of obese persons with metabolic syndrome compared with weight-matched healthy obese subjects, raising the possibility that visceral WAT contributes to the BCAA metabolic phenotype of metabolically compromised individuals.

 

Some cannabinoid receptor ligands and their distomers are direct-acting openers of SUR1 K(ATP) channels.

Lynch CJ1Zhou QShyng SLHeal DJCheetham SCDickinson KGregory PFirnges MNordheim UGoshorn SReiche D,Turski LAntel J.   Author information
Am J Physiol Endocrinol Metab. 2012 Mar 1;302(5):E540-51.
http://dx.doi.org:/10.1152/ajpendo.00258.2011

Here, we examined the chronic effects of two cannabinoid receptor-1 (CB1) inverse agonists, rimonabant and ibipinabant, in hyperinsulinemic Zucker rats to determine their chronic effects on insulinemia. Rimonabant and ibipinabant (10 mg·kg⁻¹·day⁻¹) elicited body weight-independent improvements in insulinemia and glycemia during 10 wk of chronic treatment. To elucidate the mechanism of insulin lowering, acute in vivo and in vitro studies were then performed. Surprisingly, chronic treatment was not required for insulin lowering. In acute in vivo and in vitro studies, the CB1 inverse agonists exhibited acute K channel opener (KCO; e.g., diazoxide and NN414)-like effects on glucose tolerance and glucose-stimulated insulin secretion (GSIS) with approximately fivefold better potency than diazoxide. Followup studies implied that these effects were inconsistent with a CB1-mediated mechanism. Thus effects of several CB1 agonists, inverse agonists, and distomers during GTTs or GSIS studies using perifused rat islets were unpredictable from their known CB1 activities. In vivo rimonabant and ibipinabant caused glucose intolerance in CB1 but not SUR1-KO mice. Electrophysiological studies indicated that, compared with diazoxide, 3 μM rimonabant and ibipinabant are partial agonists for K channel opening. Partial agonism was consistent with data from radioligand binding assays designed to detect SUR1 K(ATP) KCOs where rimonabant and ibipinabant allosterically regulated ³H-glibenclamide-specific binding in the presence of MgATP, as did diazoxide and NN414. Our findings indicate that some CB1 ligands may directly bind and allosterically regulate Kir6.2/SUR1 K(ATP) channels like other KCOs. This mechanism appears to be compatible with and may contribute to their acute and chronic effects on GSIS and insulinemia.

 

Transamination is required for {alpha}-ketoisocaproate but not leucine to stimulate insulin secretion.

Zhou Y1Jetton TLGoshorn SLynch CJShe PAuthor information
J Biol Chem. 2010 Oct 29;285(44):33718-26. http://dx.doi.org:/10.1074/jbc.M110.136846

It remains unclear how α-ketoisocaproate (KIC) and leucine are metabolized to stimulate insulin secretion. Mitochondrial BCATm (branched-chain aminotransferase) catalyzes reversible transamination of leucine and α-ketoglutarate to KIC and glutamate, the first step of leucine catabolism. We investigated the biochemical mechanisms of KIC and leucine-stimulated insulin secretion (KICSIS and LSIS, respectively) using BCATm(-/-) mice. In static incubation, BCATm disruption abolished insulin secretion by KIC, D,L-α-keto-β-methylvalerate, and α-ketocaproate without altering stimulation by glucose, leucine, or α-ketoglutarate. Similarly, during pancreas perfusions in BCATm(-/-) mice, glucose and arginine stimulated insulin release, whereas KICSIS was largely abolished. During islet perifusions, KIC and 2 mM glutamine caused robust dose-dependent insulin secretion in BCATm(+/+) not BCATm(-/-) islets, whereas LSIS was unaffected. Consistently, in contrast to BCATm(+/+) islets, the increases of the ATP concentration and NADPH/NADP(+) ratio in response to KIC were largely blunted in BCATm(-/-) islets. Compared with nontreated islets, the combination of KIC/glutamine (10/2 mM) did not influence α-ketoglutarate concentrations but caused 120 and 33% increases in malate in BCATm(+/+) and BCATm(-/-) islets, respectively. Although leucine oxidation and KIC transamination were blocked in BCATm(-/-) islets, KIC oxidation was unaltered. These data indicate that KICSIS requires transamination of KIC and glutamate to leucine and α-ketoglutarate, respectively. LSIS does not require leucine catabolism and may be through leucine activation of glutamate dehydrogenase. Thus, KICSIS and LSIS occur by enhancing the metabolism of glutamine/glutamate to α-ketoglutarate, which, in turn, is metabolized to produce the intracellular signals such as ATP and NADPH for insulin secretion.

 

Effect of the tyrosine kinase inhibitors (sunitinib, sorafenib, dasatinib, and imatinib) on blood glucose levels in diabetic and nondiabetic patients in general clinical practice.

Agostino NM1Chinchilli VMLynch CJKoszyk-Szewczyk AGingrich RSivik JDrabick JJ.
J Oncol Pharm Pract. 2011 Sep; 17(3):197-202. http://dx.doi.org:/10.1177/1078155210378913

Tyrosine kinase is a key enzyme activity utilized in many intracellular messaging pathways. Understanding the role of particular tyrosine kinases in malignancies has allowed for the design of tyrosine kinase inhibitors (TKIs), which can target these enzymes and interfere with downstream signaling. TKIs have proven to be successful in the treatment of chronic myeloid leukemia, renal cell carcinoma and gastrointestinal stromal tumor, and other malignancies. Scattered reports have suggested that these agents appear to affect blood glucose (BG). We retrospectively studied the BG concentrations in diabetic (17) and nondiabetic (61) patients treated with dasatinib (8), imatinib (39), sorafenib (23), and sunitinib (30) in our clinical practice. Mean declines of BG were dasatinib (53 mg/dL), imatinib (9 mg/dL), sorafenib (12 mg/dL), and sunitinib (14 mg/dL). All these declines in BG were statistically significant. Of note, 47% (8/17) of the patients with diabetes were able to discontinue their medications, including insulin in some patients. Only one diabetic patient developed symptomatic hypoglycemia while on sunitinib. The mechanism for the hypoglycemic effect of these drugs is unclear, but of the four agents tested, c-kit and PDGFRβ are the common target kinases. Clinicians should keep the potential hypoglycemic effects of these agents in mind; modification of hypoglycemic agents may be required in diabetic patients. These results also suggest that inhibition of a tyrosine kinase, be it c-kit, PDGFRβ or some other undefined target, may improve diabetes mellitus BG control and it deserves further study as a potential novel therapeutic option.

 

Cardiolipin remodeling by ALCAT1 links oxidative stress and mitochondrial dysfunction to obesity.

Li J1Romestaing CHan XLi YHao XWu YSun CLiu XJefferson LSXiong JLanoue KFChang ZLynch CJWang HShi Y.    Author information
Cell Metab. 2010 Aug 4;12(2):154-65. http://dx.doi.org:/10.1016/j.cmet.2010.07.003

Oxidative stress causes mitochondrial dysfunction and metabolic complications through unknown mechanisms. Cardiolipin (CL) is a key mitochondrial phospholipid required for oxidative phosphorylation. Oxidative damage to CL from pathological remodeling is implicated in the etiology of mitochondrial dysfunction commonly associated with diabetes, obesity, and other metabolic diseases. Here, we show that ALCAT1, a lyso-CL acyltransferase upregulated by oxidative stress and diet-induced obesity (DIO), catalyzes the synthesis of CL species that are highly sensitive to oxidative damage, leading to mitochondrial dysfunction, ROS production, and insulin resistance. These metabolic disorders were reminiscent of those observed in type 2 diabetes and were reversed by rosiglitazone treatment. Consequently, ALCAT1 deficiency prevented the onset of DIO and significantly improved mitochondrial complex I activity, lipid oxidation, and insulin signaling in ALCAT1(-/-) mice. Collectively, these findings identify a key role of ALCAT1 in regulating CL remodeling, mitochondrial dysfunction, and susceptibility to DIO.

 

BCATm deficiency ameliorates endotoxin-induced decrease in muscle protein synthesis and improves survival in septic mice.

Lang CH1Lynch CJVary TC.   Author information
Am J Physiol Regul Integr Comp Physiol. 2010 Sep; 299(3):R935-44.
http://dx.doi.org:/10.1152/ajpregu.00297.2010

Endotoxin (LPS) and sepsis decrease mammalian target of rapamycin (mTOR) activity in skeletal muscle, thereby reducing protein synthesis. Our study tests the hypothesis that inhibition of branched-chain amino acid (BCAA) catabolism, which elevates circulating BCAA and stimulates mTOR, will blunt the LPS-induced decrease in muscle protein synthesis. Wild-type (WT) and mitochondrial branched-chain aminotransferase (BCATm) knockout mice were studied 4 h after Escherichia coli LPS or saline. Basal skeletal muscle protein synthesis was increased in knockout mice compared with WT, and this change was associated with increased eukaryotic initiation factor (eIF)-4E binding protein-1 (4E-BP1) phosphorylation, eIF4E.eIF4G binding, 4E-BP1.raptor binding, and eIF3.raptor binding without a change in the mTOR.raptor complex in muscle. LPS decreased muscle protein synthesis in WT mice, a change associated with decreased 4E-BP1 phosphorylation as well as decreased formation of eIF4E.eIF4G, 4E-BP1.raptor, and eIF3.raptor complexes. In BCATm knockout mice given LPS, muscle protein synthesis only decreased to values found in vehicle-treated WT control mice, and this ameliorated LPS effect was associated with a coordinate increase in 4E-BP1.raptor, eIF3.raptor, and 4E-BP1 phosphorylation. Additionally, the LPS-induced increase in muscle cytokines was blunted in BCATm knockout mice, compared with WT animals. In a separate study, 7-day survival and muscle mass were increased in BCATm knockout vs. WT mice after polymicrobial peritonitis. These data suggest that elevating blood BCAA is sufficient to ameliorate the catabolic effect of LPS on skeletal muscle protein synthesis via alterations in protein-protein interactions within mTOR complex-1, and this may provide a survival advantage in response to bacterial infection.

 

Alcohol-induced IGF-I resistance is ameliorated in mice deficient for mitochondrial branched-chain aminotransferase.

Lang CH1Lynch CJVary TCAuthor information
J Nutr. 2010 May;140(5):932-8. http://dx.doi.org:/10.3945/jn.109.120501

Acute alcohol intoxication decreases skeletal muscle protein synthesis by impairing mammalian target of rapamycin (mTOR). In 2 studies, we determined whether inhibition of branched-chain amino acid (BCAA) catabolism ameliorates the inhibitory effect of alcohol on muscle protein synthesis by raising the plasma BCAA concentrations and/or by improving the anabolic response to insulin-like growth factor (IGF)-I. In the first study, 4 groups of mice were used: wild-type (WT) and mitochondrial branched-chain aminotransferase (BCATm) knockout (KO) mice orally administered saline or alcohol (5 g/kg, 1 h). Protein synthesis was greater in KO mice compared with WT controls and was associated with greater phosphorylation of eukaryotic initiation factor (eIF)-4E binding protein-1 (4EBP1), eIF4E-eIF4G binding, and 4EBP1-regulatory associated protein of mTOR (raptor) binding, but not mTOR-raptor binding. Alcohol decreased protein synthesis in WT mice, a change associated with less 4EBP1 phosphorylation, eIF4E-eIF4G binding, and raptor-4EBP1 binding, but greater mTOR-raptor complex formation. Comparable alcohol effects on protein synthesis and signal transduction were detected in BCATm KO mice. The second study used the same 4 groups, but all mice were injected with IGF-I (25 microg/mouse, 30 min). Alcohol impaired the ability of IGF-I to increase muscle protein synthesis, 4EBP1 and 70-kilodalton ribosomal protein S6 kinase-1 phosphorylation, eIF4E-eIF4G binding, and 4EBP1-raptor binding in WT mice. However, in alcohol-treated BCATm KO mice, this IGF-I resistance was not manifested. These data suggest that whereas the sustained elevation in plasma BCAA is not sufficient to ameliorate the catabolic effect of acute alcohol intoxication on muscle protein synthesis, it does improve the anabolic effect of IGF-I.

 

Impact of chronic alcohol ingestion on cardiac muscle protein expression.

Fogle RL1Lynch CJPalopoli MDeiter GStanley BAVary TCAuthor information
Alcohol Clin Exp Res. 2010 Jul;34(7):1226-34. http://dx.doi.org:/10.1111/j.1530-0277.2010.01200.x

BACKGROUND:

Chronic alcohol abuse contributes not only to an increased risk of health-related complications, but also to a premature mortality in adults. Myocardial dysfunction, including the development of a syndrome referred to as alcoholic cardiomyopathy, appears to be a major contributing factor. One mechanism to account for the pathogenesis of alcoholic cardiomyopathy involves alterations in protein expression secondary to an inhibition of protein synthesis. However, the full extent to which myocardial proteins are affected by chronic alcohol consumption remains unresolved.

METHODS:

The purpose of this study was to examine the effect of chronic alcohol consumption on the expression of cardiac proteins. Male rats were maintained for 16 weeks on a 40% ethanol-containing diet in which alcohol was provided both in drinking water and agar blocks. Control animals were pair-fed to consume the same caloric intake. Heart homogenates from control- and ethanol-fed rats were labeled with the cleavable isotope coded affinity tags (ICAT). Following the reaction with the ICAT reagent, we applied one-dimensional gel electrophoresis with in-gel trypsin digestion of proteins and subsequent MALDI-TOF-TOF mass spectrometric techniques for identification of peptides. Differences in the expression of cardiac proteins from control- and ethanol-fed rats were determined by mass spectrometry approaches.

RESULTS:

Initial proteomic analysis identified and quantified hundreds of cardiac proteins. Major decreases in the expression of specific myocardial proteins were observed. Proteins were grouped depending on their contribution to multiple activities of cardiac function and metabolism, including mitochondrial-, glycolytic-, myofibrillar-, membrane-associated, and plasma proteins. Another group contained identified proteins that could not be properly categorized under the aforementioned classification system.

CONCLUSIONS:

Based on the changes in proteins, we speculate modulation of cardiac muscle protein expression represents a fundamental alteration induced by chronic alcohol consumption, consistent with changes in myocardial wall thickness measured under the same conditions.

 

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Experience with Thyroid Cancer

Author: Larry H. Bernstein, MD, FCAP

 

 

I retired from my position as pathologist in charge of clinical laboratories after five years at New York Methodist Hospital, with great satisfaction in mentoring students from the high schools and university undergraduate programs nearby interested in science.  I was fortunate to experience the Brooklyn “cityscape” and vibrance, and to work with other physician educators in surgery and cardiology and pulmonary medicine. Most of my students participated in presenting papers at professional meetings, and some coauthored published work.  But I was about to enter a new phase of life.  I returned to my home in Connecticut and immediately accepted a temporary position for less than a year as the Blood Bank – Transfusion Medicine Director at Norwalk Hospital, which also afforded the opportunity to help with the installation of an automated hematology system, and to help in the quality monitoring in Chemistry.  It was a good reprieve from the anxiety of having nothing to do after an intense professional  career.  When that ended I went to Yale University Department of Mathematics  and found a collaborative project with a brilliant postdoc and his mentor, Professor and Emeritus Chairman Ronald Coifman.  A colleague of mine many years ago had done a project with the automated hematology, but it was too early for a good interpretive hemogram.  I had sufficient data in 8,000 lines of data containing all of the important information.  We managed to develop an algorithm in over a year that would interpret the data and provide a list of probabilities for the physician, and we used part of the data set for creating the algorithm and another set for validation.   In the meantime I also became engaged in twice weekly sessions in Yoga, Pilates, and massage therapy, and did some swimming.  I also participated in discussions with a group of retired men up to 20 years senior to me. I also did two rounds of walking around the condonium that was home to my wife and I.

 

Then I noticed that I became weak and short of breath in walking around the condominium streets and had to stop and hold a tree or streetlamp.  I was long-term diabetic and was followed by a pulmonologist for sleep apnea for some five years.  This was an insidious health presentation, as I had had good pulmonary and cardiac status at that point in time.  Then an “aha!” moment occurred when my laboratory results showed a high level of thyroid stimulating hormone.  It was one of a rare instances of hyperparathyroidism occurring with a thyroid tumor.

I then had radiological testing of the head and neck, which led to a thyroid biopsy.  I then chose to referral to Yale University Health Sciences Center, where there was an excellent endocrinologist, and it was a leading center for head and neck surgery.  All of this took many trips, much testing, biopsies of thyroid and its removal.  There also were 3 proximate lymph nodes.  In undergoing the tests the technicians said that they had never had a patient like me because of my questions and comments.  It was a papillary thyroid cancer involving the center and right lobe, with a characteristic appearance and identified by a histologically stained biomarker that I reviewed with my longtime friend and colleague, Dr. Marguerite Pinto.  The surgery and followup went well.

 

However, I developed  double-vision (diplopia) and was referent to one of a handful of neuro-ophthalmologists in Connecticut.  Perhaps related to the hyperthyroid condition, I had developed an anti-thyroid antibody that disturbed the lower muscle that moves the right eye.  This required many test over months, and my wearing a special attachable lens gradient to equalize the vision in both eyes.  The next requirement was to watch and wait. It could be corrected by surgery if it remained after a year.  Nevertheless, it subsided over a period of perhaps 9 months and I removed the attachment with sufficient return of my previous sight.

In the meantime I was writing a lot over this period, and I also began to watch MSNBC and Turner Classic Movies on a regular basis and found relief.  I’m not a “laugher” and have had a long-term anxiety state.  I enjoyed watching the magic of Charlie Chaplin, Al Jolson, Lassie, and whatever caught my fancy.

My daughter was accepted for a tenure earning faculty position competing against a large field of candidates for an Assistant Professorship at Holyoke Community College in Western Massachusetts. Her husband had invested 15 years as a Navy physician and neurologist, having graduated from the Armed Services Medical School in Bethesda, and given this opportunity, decided to forgo further service  would pay for their child’s future college education.  He is very bright, knowledgable, and a blessing for a son-in-law.  We went through the sale of our house and the search for a living arrangement near our daughter, all while I was going through my therapy.  It was undoubtedly the best thing to moving near the daughter.

The move became an enormous challenge.  It took time to sell the condominium, which was  desirable in  a difficult market.  I became engaged in trashing what I need not save, but I had to review hundreds of published work, unpublished papers, saved publications, and hundreds of photographs large and small, that I had kept over many years.  I had to dispense of my darkroom equipment, and we managed to give much away.  It was very engaging.  It was impossible to be overwhelmed, but also tiring over the long haul.

Prior to moving, my wife had trouble swallowing, and she was subsequently found to have an esophageal carcinoma at 20 cm, and invading the submucosa.  We made arrangement for treatment by Massachusetts General Hospital, which could be done at its cancer affiliate in Northampton, MA.  The move was made, and we have temporary residence in a townhouse in Northampton, woon to move to an adult living facility.  My wife is lucky enough to have a squamous cell carcinoma, not adenocarcinoma.  Her treatment needed careful adjustments.  She decided to live it out whatever the outcome.  However, she has done well.  She maintained her weight, underwent radiation and chemotherapy, which is finished, and is returning to eating more than soft food and protein shakes. She has enjoyed being a grandmother to an incredible kid in kindergarten only a block away, and engaged in reading and all sorts of puzzles and games.

My own health has seen a decline in ease of motion. I am starting physical therapy and also pulmonary therapy for my asthma.  Having a grandson is both a pleasure and an education. Being a grandparent, one is relieved of the responsibility of being a parent.

In following my wife’s serious illness, which precluded surgery, we have had phone calls from her sister daily, weekend visits nonstop, and more to come.  She has been very satisfied with the quality of care.
My triplet sister calls often for both of us.  We also call my 95 year old aunt, who is my mother’s sister.  My mother’s younger brother enjoyed life, left Hungary as a medical student in 1941 and became an insurance salesman in Cleveland. He lived to 99 years old.  He outlived 3 wives, all friends of my mother.
His daughter has called me for a medical second opinion for a good fifteen years.  She was a very rare patient who had a pituitary growth hormone secreting adenocarcinoma (Addison’s Disease) for which she had two surgeries, and regularly visits the Cleveland Clinic and the Jewish Hospital of Los Angeles.

 

 

 

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Computer Aided Design

Larry H. Bernstein, MD, FCAP, Curator

LPBI

 

IBM’s Watson shown to enhance human-computer co-creativity, support biologically inspired design

Watson Engagement Advisor AI system was trained to “learn” about biologically inspired design from biology articles, then answer questions
November 13, 2015   http://www.kurzweilai.net/ibms-watson-shown-to-enhance-human-computer-co-creativity-support-biologically-inspired-design

http://www.kurzweilai.net/images/Enhancing-Human-Computer-Co-Creativity.jpg

Georgia Institute of Technology researchers, working with student teams, trained a cloud-based version of IBM’s Watson called the Watson Engagement Advisor to provide answers to questions about biologically inspired design (biomimetics), a design paradigm that uses biological systems as analogues for inventing technological systems.

 

Ashok Goel, a professor at Georgia Tech’s School of Interactive Computing who conducts research on computational creativity. In an experiment, he used this version of Watson as an “intelligent research assistant” to support teaching about biologically inspired design and computational creativity in the Georgia Tech CS4803/8803 class on Computational Creativity in Spring 2015. Goel found that Watson’s ability to retrieve natural language information could allow a novice to quickly “train up” about complex topics and better determine whether their idea or hypothesis is worth pursuing.

An intelligent research assistant

In the form of a class project, the students fed Watson several hundred biology articles from Biologue, an interactive biology repository, and 1,200 question-answer pairs. The teams then posed questions to Watson about the research it had “learned” regarding big design challenges in areas such as engineering, architecture, systems, and computing.

Examples of questions:

“How do you make a better desalination process for consuming sea water?” (Animals have a variety of answers for this, such as how seagulls filter out seawater salt through special glands.)

“How can manufacturers develop better solar cells for long-term space travel?” One answer: Replicate how plants in harsh climates use high-temperature fibrous insulation material to regulate temperature.

Watson effectively acted as an intelligent sounding board to steer students through what would otherwise be a daunting task of parsing a wide volume of research that may fall outside their expertise.

This version of Watson also prompts users with alternate ways to ask questions for better results. Those results are packaged as a “treetop” where each answer is a “leaf” that varies in size based on its weighted importance. This was intended to allow the average user to navigate results more easily on a given topic.

 

http://www.kurzweilai.net/images/GT-Watson-Plus-Concept-Results.png

Results from training the Watson AI system were packaged as a “treetop” where each answer is a “leaf” that varies in size based on its weighted importance. Each leaf is the starting point for a Q&A with Watson. (credit: Georgia Tech)

 

“Imagine if you could ask Google a complicated question and it immediately responded with your answer — not just a list of links to manually open, says Goel. “That’s what we did with Watson. Researchers are provided a quickly digestible visual map of the concepts relevant to the query and the degree to which they are relevant. We were able to add more semantic and contextual meaning to Watson to give some notion of a conversation with the AI.”

 

http://www.kurzweilai.net/images/Watson-Screenshot.png

Georgia Tech’s Watson Engagement Advisor (credit: Georgia Tech)

 

Goel believes this approach to using Watson could assist professionals in a variety of fields by allowing them to ask questions and receive answers as quickly as in a natural conversation. He plans to investigate other areas with Watson such as online learning and healthcare.

The work was presented at the Association for the Advancement of Artificial Intelligence (AAAI) 2015 Fall Symposium on Cognitive Assistance in Government, Nov. 12–14, in Arlington, Va. and was published in Procs. AAAI 2015 Fall Symposium on Cognitive Assistance (open access).

 

Abstract of Using Watson for Enhancing Human-Computer Co-Creativity

We describe an experiment in using IBM’s Watson cognitive system to teach about human-computer co-creativity in
a Georgia Tech Spring 2015 class on computational creativity. The project-based class used Watson to support biologically
inspired design, a design paradigm that uses biological systems as analogues for inventing technological
systems. The twenty-four students in the class self-organized into six teams of four students each, and developed semester-long projects that built on Watson to support biologically inspired design. In this paper, we describe this experiment in using Watson to teach about human-computer co-creativity, present one project in detail, and summarize the remaining five projects. We also draw lessons on building on Watson for (i) supporting biologically inspired design, and (ii) enhancing human-computer co-creativity.

sjwilliams

Interesting however Google had just announced a big AI venture of their own. Although it is curious why they needed such a defined training set. It seems, as was said in the EmTechMIT lectures that AI is still in its infancy and is nowhere near a true AI system. It is also interesting to note how rapidly China is expanding their supercomputing power (growth of supercomputers in China is dwarfing that in the US, in fact US has 20 less suipercomputers).

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Diabetic Retinopathy

Larry H. Bernstein, MD, FCAP, Curator

LPBI

 

Lucentis effective for proliferative diabetic retinopathy

NIH-funded clinical trial marks first major advance in therapy in 40 years.

http://www.nih.gov/news-events/news-releases/lucentis-effective-proliferative-diabetic-retinopathy

Illustration of ruptured blood vessels

http://www.nih.gov/sites/default/files/styles/featured_media_breakpoint-large-extra/public/news-events/news-releases/2015/20151116-eye-blood-vessels.jpg

Abnormal blood vessels bleeding into the center of the eye due to proliferative diabetic retinopathy.

https://youtu.be/jPoCIa0_1po

A clinical trial funded by the National Institutes of Health has found that the drug ranibizumab (Lucentis) is highly effective in treating proliferative diabetic retinopathy. The trial, conducted by the Diabetic Retinopathy Clinical Research Network (DRCR.net) compared Lucentis with a type of laser therapy called panretinal or scatter photocoagulation, which has remained the gold standard for proliferative diabetic retinopathy since the mid-1970s. The findings demonstrate the first major therapy advance in nearly 40 years.

“These latest results from the DRCR Network provide crucial evidence for a safe and effective alternative to laser therapy against proliferative diabetic retinopathy,” said Paul A. Sieving, M.D., Ph.D., director of NIH’s National Eye Institute (NEI), which funded the trial.  The results were published online today in the Journal of the American Medical Association.

Treating abnormal retinal blood vessels with laser therapy became the standard treatment for proliferative diabetic retinopathy after the NEI announced results of the Diabetic Retinopathy Study in 1976. Although laser therapy effectively preserves central vision, it can damage night and side vision; so, researchers have sought therapies that work as well or better than laser but without such side effects.

A complication of diabetes, diabetic retinopathy can damage blood vessels in the light-sensitive retina in the back of the eye. As the disease worsens, blood vessels may swell, become distorted and lose their ability to function properly. Diabetic retinopathy becomes proliferative when lack of blood flow in the retina increases production of a substance called vascular endothelial growth factor, which can stimulate the growth of new, abnormal blood vessels. These new vessels are prone to bleeding into the center of the eye, often requiring a surgical procedure called a vitrectomy to clear the blood. The abnormal blood vessels can also cause scarring and retinal detachment. Lucentis is among several drugs that block the effects of vascular endothelial growth factor.

About 7.7 million U.S. residents have diabetic retinopathy, a leading cause of blindness among working-age Americans. Among these, about 1.5 percent have PDR.

The DRCR.net enrolled 305 participants (394 eyes) with proliferative diabetic retinopathy in one or both eyes at 55 clinical sites across the country. Eyes were assigned randomly to treatment with Lucentis or laser. For participants who enrolled both eyes in the study, one eye was assigned to the laser group and the other was assigned to the Lucentis group. About half of the eyes assigned to the laser group required more than one round of laser treatment. In the other group, Lucentis (0.5 mg/0.05 ml) was given via injections into the eye once per month for three consecutive months, and then as needed until the disease resolved or stabilized.

Because Lucentis is commonly used to treat diabetic macular edema—the build-up of fluid in the central area of the retina—the study permitted the use of Lucentis for diabetic macular edema in the laser group, if necessary. Slightly more than half (53 percent) of eyes in the laser group received Lucentis injections to treat diabetic macular edema. About 6 percent of eyes in the Lucentis group received laser therapy, mostly to treat retinal detachment or bleeding.

At two years, vision in the Lucentis group improved by about half a line on an eye chart compared with virtually no change in the laser group. There was little change in side vision with injection (average worsening of 23 decibels) but a substantial loss of side vision with laser (average worsening of 422 decibels).   The vitrectomy rate was lower in the Lucentis group (8 of 191 eyes) than in the laser group (30 of 203 eyes).

Rates of serious systemic adverse events, including cardiac arrest and stroke, were similar between the two groups. One patient in the Lucentis group developed endophthalmitis, an infection in the eye. Other side effects were low, with little difference between treatment groups.

“Lucentis should be considered a viable treatment option for people with proliferative diabetic retinopathy, especially for individuals needing anti-vascular endothelial growth factor for diabetic macular edema,” said Jeffrey G. Gross, M.D., of the Carolina Retina Center in Columbia, South Carolina, who chaired the study. Dr. Gross presented results November 13, 2015, at the annual meeting of the American Academy of Ophthalmology in Las Vegas.

In addition to treating proliferative diabetic retinopathy, the report suggests Lucentis may even help prevent diabetic macular edema from occurring. Among people without diabetic macular edema at the start of the study, only 9 percent of Lucentis-treated eyes developed diabetic macular edema during the study, compared with 28 percent in the laser group. The DRCR.net will continue to follow patients in this study for a total of five years.

The DRCR.net is dedicated to facilitating multicenter clinical research of diabetic eye disease. The network formed in 2002 and comprises more than 350 physicians practicing at more than 140 clinical sites across the country. For more information, visit the DRCR.net website at http://drcrnet.jaeb.org/(link is external).

The study was funded by NEI grants EY14231, EY23207, EY18817.

Lucentis was provided by Genentech. Additional research funding for this study was provided by the National Institute of Diabetes and Digestive and Kidney Diseases, also a part of the NIH.

The study is registered as NCT01489189 at ClinicalTrials.gov(link is external).

The NEI provides information about diabetic eye disease at http://www.nei.nih.gov/health/diabetic/.

Information about diabetes is available through the National Diabetes Education Program, www.ndep.nih.gov/.

View an NEI video about the study at https://youtu.be/jPoCIa0_1po(link is external).

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