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Archive for the ‘Developmental biology’ Category


Reporter and Curator: Dr. Sudipta Saha, Ph.D.

 

Leigh syndrome is one of the hundreds of so-called mitochondrial diseases, which are caused by defects in the mitochondria that produce 90 percent of the body’s energy. These disorders are rare; about 1,000 to 4,000 babies in the United States are born with one every year. But they are devastating and can result in grave impairment of nearly any bodily system. They are largely untreatable, uniformly incurable and very difficult to screen.

 

Leigh syndrome is a terrible disease. It emerges shortly after birth and claims one major organ after another. Movement becomes difficult, and then impossible. A tracheotomy and feeding tube are often necessary by toddlerhood, and as the disease progresses, lungs frequently have to be suctioned manually. Most children with the condition die by the age of 5 or 6.

 

Scientists have devised a procedure called mitochondrial replacement therapy (M.R.T.) that involves transplanting the nucleus of an affected egg (mitochondrial diseases are passed down from the mother’s side) into an unaffected one whose nucleus has been removed. The procedure is sometimes called “three-parent in vitro fertilization”. Mitochondria contain a minuscule amount of DNA, any resulting embryo would have mitochondrial DNA from the donor egg and nuclear DNA from each of its parents.

 

After decades of careful study in cell and animal research M.R.T. is now finally being tested in human clinical trials by doctors in Britain (no births confirmed yet officially). In the United States, however, this procedure is effectively illegal. M.R.T. does not involve altering any genetic code. Defective mitochondria are swapped out for healthy ones.

 

Mitochondrial DNA governs only a handful of basic cellular functions. It is separate from nuclear DNA, which helps determine individual traits like physical appearance, intelligence and personality. That means M.R.T. cannot be used to produce the genetically enhanced “designer babies” and thus should be allowed in humans. But, there is no way to know how safe or effective M.R.T. is until doctors and scientists test it in humans.

 

References:

 

 

https://pharmaceuticalintelligence.com/2016/10/07/the-three-parent-technique-to-avoid-mitochondrial-disease-in-embryo/

 

 

 

 

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Lesson 8 Cell Signaling and Motility: Lesson and Supplemental Information on Cell Junctions and ECM: #TUBiol3373

Curator: Stephen J. Williams, Ph.D.

Please click on the following link for the PowerPoint Presentation for Lecture 8 on Cell Junctions and the  Extracellular Matrix: (this is same lesson from 2018 so don’t worry that file says 2018)

cell signaling 8 lesson 2018

 

Some other reading on this lesson on this Open Access Journal Include:

On Cell Junctions:

Translational Research on the Mechanism of Water and Electrolyte Movements into the Cell     

(pay particular attention to article by Fischbarg on importance of tight junctions for proper water and electrolyte movement)

The Role of Tight Junction Proteins in Water and Electrolyte Transport

(pay attention to article of role of tight junction in kidney in the Loop of Henle and the collecting tubule)

EpCAM [7.4]

(a tight junction protein)

Signaling and Signaling Pathways

(for this lesson pay attention to the part that shows how Receptor Tyrosine Kinase activation (RTK) can lead to signaling to an integrin and also how the thrombin receptor leads to cellular signals both to GPCR (G-protein coupled receptors like the thrombin receptor, the ADP receptor; but also the signaling cascades that lead to integrin activation of integrins leading to adhesion to insoluble fibrin mesh of the newly formed clot and subsequent adhesion of platelets, forming the platelet plug during thrombosis.)

On the Extracellular Matrix

Three-Dimensional Fibroblast Matrix Improves Left Ventricular Function Post MI

Arteriogenesis and Cardiac Repair: Two Biomaterials – Injectable Thymosin beta4 and Myocardial Matrix Hydrogel

 

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Reporter and Curator: Dr. Sudipta Saha, Ph.D.

 

Long interspersed nuclear elements 1 (LINE1) is repeated half a million times in the human genome, making up nearly a fifth of the DNA in every cell. But nobody cared to study it and may be the reason to call it junk DNA. LINE1, like other transposons (or “jumping genes”), has the unusual ability to copy and insert itself in random places in the genome. Many other research groups uncovered possible roles in early mouse embryos and in brain cells. But nobody quite established a proper report about the functions of LINE1.

 

Geneticists gave attention to LINE1 when it was found to cause cancer or genetic disorders like hemophilia. But researchers at University of California at San Francisco suspected there was more characteristics of LINE1. They suspected that if it can be most harmless then it can be worst harmful also.

 

Many reports showed that LINE1 is especially active inside developing embryos, which suggests that the segment actually plays a key role in coordinating the development of cells in an embryo. Researchers at University of California at San Francisco figured out how to turn LINE1 off in mouse embryos by blocking LINE1 RNA. As a result the embryos got stuck in the two-cell stage, right after a fertilized egg has first split. Without LINE1, embryos essentially stopped developing.

 

The researchers thought that LINE1 RNA particles act as molecular “glue,” bringing together a suite of molecules that switch off the two-cell stage and kick it into the next phase of development. In particular, it turns off a gene called Dux, which is active in the two-cell stage.

 

LINE1’s ability to copy itself, however, seems to have nothing to do with its role in embryonic development. When LINE1 was blocked from inserting itself into the genome, the embryonic stem cells remained unaffected. It’s possible that cells in embryos have a way of making LINE1 RNA while also preventing its potentially harmful “jumping” around in the genome. But it’s unlikely that every one of the thousands of copies of LINE1 is actually being used to regulate embryonic development.

 

LINE1 is abundant in the genomes of almost all mammals. Other transposons, also once considered junk DNA, have turned out to have critical roles in development in human cells too. There are differences between mice and humans, so, the next obvious step is to study LINE1 in human cells, where it makes up 17 percent of the genome.

 

References:

 

https://www-theatlantic-com.cdn.ampproject.org/c/s/www.theatlantic.com/amp/article/563354/

 

https://www.ncbi.nlm.nih.gov/pubmed/29937225

 

https://www.nature.com/scitable/topicpage/transposons-the-jumping-genes-518

 

https://www.sciencedaily.com/releases/2018/06/180621141038.htm

 

https://www.ncbi.nlm.nih.gov/pubmed/16015595

 

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Reporter and Curator: Dr. Sudipta Saha, Ph.D.

 

Hepatitis B virus can cause serious, long-term health problems, such as liver disease and cancer, and can spread from mother-to-child during delivery. According to the latest estimates from the World Health Organization (WHO), approximately 257 million people in 2015 were living with the virus. Countries in Asia have a high burden of hepatitis B. There is no cure, and antiviral drugs used to treat the infection usually need to be taken for life.

 

To prevent infection, WHO recommends that all newborns receive their first dose of hepatitis B vaccine within 24 hours of delivery. Infants born to hepatitis B-infected mothers are also given protective antibodies called hepatitis B immune globulin (HBIG). However, mother-to-child transmission can still occur in women with high levels of virus in their blood, as well as those with mutated versions of the virus.

 

Tenofovir disoproxil fumarate (TDF), an antiviral drug commonly prescribed to treat hepatitis B infection, does not significantly reduce mother-to-child transmission of hepatitis B virus when taken during pregnancy and after delivery, according to a phase III clinical trial in Thailand funded by the National Institutes of Health. The study tested TDF therapy in addition to the standard preventative regimen — administration of hepatitis B vaccine and protective antibodies at birth — to explore the drug’s potential effects on mother-to-child transmission rates. The results appear in the New England Journal of Medicine.

 

The present study was conducted at 17 hospitals of the Ministry of Public Health in Thailand. It screened more than 2,500 women for eligibility and enrolled 331 pregnant women with hepatitis B. The women received placebo (163) or TDF (168) at intervals from 28 weeks of pregnancy to two months after delivery. All infants received standard hepatitis B preventatives given in Thailand, which include HBIG at birth and five doses of the hepatitis B vaccine by age 6 months (which differs from the three doses given in the United States). A total of 294 infants (147 in each group) were followed through age 6 months.

 

Three infants in the placebo group had hepatitis B infection at age 6 months, compared to zero infants in the TDF treatment group. Given the unexpectedly low transmission rate in the placebo group, the researchers concluded that the addition of TDF to current recommendations did not significantly reduce mother-to-child transmission of the virus.

 

According to the study, the clinical trial had enough participants to detect statistical differences if the transmission rate in the placebo group reached at least 12 percent, a rate observed in previous studies. Though the reasons are unknown, the researchers speculate that the lower transmission rate seen in the study may relate to the number of doses of hepatitis B vaccine given to infants in Thailand, lower rates of amniocentesis and Cesarean section deliveries in this study, or the lower prevalence of mutated viruses that result in higher vaccine efficacy in Thailand compared to other countries.

 

References:

 

https://www.nih.gov/news-events/news-releases/antiviral-drug-not-beneficial-reducing-mother-child-transmission-hepatitis-b-when-added-existing-preventatives

 

https://www.ncbi.nlm.nih.gov/pubmed/29514030

 

https://www.ncbi.nlm.nih.gov/pubmed/29514035

 

https://www.ncbi.nlm.nih.gov/pubmed/25240752

 

https://www.ncbi.nlm.nih.gov/pubmed/28188612

 

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Reporter and Curator: Dr. Sudipta Saha, Ph.D.

 

Babies born at or before 25 weeks have quite low survival outcomes, and in the US it is the leading cause of infant mortality and morbidity. Just a few weeks of extra ‘growing time’ can be the difference between severe health problems and a relatively healthy baby.

 

Researchers from The Children’s Hospital of Philadelphia (USA) Research Institute have shown it’s possible to nurture and protect a mammal in late stages of gestation inside an artificial womb; technology which could become a lifesaver for many premature human babies in just a few years.

 

The researchers took eight lambs between 105 to 120 days gestation (the physiological equivalent of 23 to 24 weeks in humans) and placed them inside the artificial womb. The artificial womb is a sealed and sterile bag filled with an electrolyte solution which acts like amniotic fluid in the uterus. The lamb’s own heart pumps the blood through the umbilical cord into a gas exchange machine outside the bag.

 

The artificial womb worked in this study and after just four weeks the lambs’ brains and lungs had matured like normal. They had also grown wool and could wiggle, open their eyes, and swallow. Although this study is looking incredibly promising but getting the research up to scratch for human babies still requires a big leap.

 

Nevertheless, if all goes well, the researchers hope to test the device on premature humans within three to five years. Potential therapeutic applications of this invention may include treatment of fetal growth retardation related to placental insufficiency or the salvage of preterm infants threatening to deliver after fetal intervention or fetal surgery.

 

The technology may also provide the opportunity to deliver infants affected by congenital malformations of the heart, lung and diaphragm for early correction or therapy before the institution of gas ventilation. Numerous applications related to fetal pharmacologic, stem cell or gene therapy could be facilitated by removing the possibility for maternal exposure and enabling direct delivery of therapeutic agents to the isolated fetus.

 

References:

 

https://www.nature.com/articles/ncomms15112

 

 

https://www.sciencealert.com/researchers-have-successfully-grown-premature-lambs-in-an-artificial-womb

 

http://www.npr.org/sections/health-shots/2017/04/25/525044286/scientists-create-artificial-womb-that-could-help-prematurely-born-babies

 

http://www.telegraph.co.uk/science/2017/04/25/artificial-womb-promises-boost-survival-premature-babies/

 

https://www.theguardian.com/science/2017/apr/25/artificial-womb-for-premature-babies-successful-in-animal-trials-biobag

 

http://www.theblaze.com/news/2017/04/25/new-artificial-womb-technology-could-keep-babies-born-prematurely-alive-and-healthy/

 

http://www.theverge.com/2017/4/25/15421734/artificial-womb-fetus-biobag-uterus-lamb-sheep-birth-premie-preterm-infant

 

http://www.abc.net.au/news/2017-04-26/artificial-womb-could-one-day-keep-premature-babies-alive/8472960

 

https://www.theatlantic.com/health/archive/2017/04/preemies-floating-in-fluid-filled-bags/524181/

 

http://www.independent.co.uk/news/health/artificial-womb-save-premature-babies-lives-scientists-create-childrens-hospital-philadelphia-nature-a7701546.html

 

https://www.cnet.com/news/artificial-womb-births-premature-lambs-human-infants/

 

https://science.slashdot.org/story/17/04/25/2035243/an-artificial-womb-successfully-grew-baby-sheep—-and-humans-could-be-next

 

http://newatlas.com/artificial-womb-premature-babies/49207/

 

https://www.geneticliteracyproject.org/2015/06/12/artificial-wombs-the-coming-era-of-motherless-births/

 

http://news.nationalgeographic.com/2017/04/artificial-womb-lambs-premature-babies-health-science/

 

https://motherboard.vice.com/en_us/article/artificial-womb-free-births-just-got-a-lot-more-real-cambridge-embryo-reproduction

 

http://www.disclose.tv/news/The_Artificial_Womb_Is_Born_Welcome_To_The_WORLD_Of_The_MATRIX/114199

 

 

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Reporter and Curator: Dr. Sudipta Saha, Ph.D.

 

Scientists think excessive population growth is a cause of scarcity and environmental degradation. A male pill could reduce the number of unintended pregnancies, which accounts for 40 percent of all pregnancies worldwide.

 

But, big drug companies long ago dropped out of the search for a male contraceptive pill which is able to chemically intercept millions of sperm before they reach a woman’s egg. Right now the chemical burden for contraception relies solely on the female. There’s not much activity in the male contraception field because an effective solution is available on the female side.

 

Presently, male contraception means a condom or a vasectomy. But researchers from Center for Drug Discovery at Baylor College of Medicine, USA are renewing the search for a better option—an easy-to-take pill that’s safe, fast-acting, and reversible.

 

The scientists began with lists of genes active in the testes for sperm production and motility and then created knockout mice that lack those genes. Using the gene-editing technology called CRISPR, in collaboration with Japanese scientists, they have so far made more than 75 of these “knockout” mice.

 

They allowed these mice to mate with normal (wild type) female mice, and if their female partners don’t get pregnant after three to six months, it means the gene might be a target for a contraceptive. Out of 2300 genes that are particularly active in the testes of mice, the researchers have identified 30 genes whose deletion makes the male infertile. Next the scientists are planning a novel screening approach to test whether any of about two billion chemicals can disable these genes in a test tube. Promising chemicals could then be fed to male mice to see if they cause infertility.

 

Female birth control pills use hormones to inhibit a woman’s ovaries from releasing eggs. But hormones have side effects like weight gain, mood changes, and headaches. A trial of one male contraceptive hormone was stopped early in 2011 after one participant committed suicide and others reported depression. Moreover, some drug candidates have made animals permanently sterile which is not the goal of the research. The challenge is to prevent sperm being made without permanently sterilizing the individual.

 

As a better way to test drugs, Scientists at University of Georgia, USA are investigating yet another high-tech approach. They are turning human skin cells into stem cells that look and act like the spermatogonial cells in the testes. Testing drugs on such cells might provide more accurate leads than tests on mice.

 

The male pill would also have to start working quickly, a lot sooner than the female pill, which takes about a week to function. Scientists from University of Dundee, U.K. admitted that there are lots of challenges. Because, a women’s ovary usually release one mature egg each month, while a man makes millions of sperm every day. So, the male pill has to be made 100 percent effective and act instantaneously.

 

References:

 

https://www.technologyreview.com/s/603676/the-search-for-a-perfect-male-birth-control-pill/

 

https://futurism.com/videos/the-perfect-male-birth-control-pill-is-coming-soon/?utm_source=Digest&utm_campaign=c42fc7b9b6-EMAIL_CAMPAIGN_2017_03_20&utm_medium=email&utm_term=0_03cd0a26cd-c42fc7b9b6-246845533

 

http://www.telegraph.co.uk/women/sex/the-male-pill-is-coming—and-its-going-to-change-everything/

 

http://www.mensfitness.com/women/sex-tips/male-birth-control-pill-making

 

http://health.howstuffworks.com/sexual-health/contraception/male-bc-pill.htm

 

http://europe.newsweek.com/male-contraception-side-effects-study-pill-injection-518237?rm=eu

 

http://edition.cnn.com/2016/01/07/health/male-birth-control-pill/index.html

 

http://www.nhs.uk/Conditions/contraception-guide/Pages/male-pill.aspx

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Reporter and Curator: Dr. Sudipta Saha, Ph.D.

Researchers have classified a brand-new organ inside human body. Known as the mesentery, the new organ is found in our digestive systems, and was long thought to be made up of fragmented, separate structures. But recent research has shown that it’s actually one, continuous organ. The evidence for the organ’s reclassification is now published in The Lancet Gastroenterology & Hepatology. Although we now know about the structure of this new organ, its function is still poorly understood, and studying it could be the key to better understanding and treatment of abdominal and digestive disease.

mesentery

J Calvin Coffey, a researcher from the University Hospital Limerick in Ireland, who first discovered that the mesentery was an organ. In 2012, Coffey and his colleagues showed through detailed microscopic examinations that the mesentery is actually a continuous structure. Over the past four years, they’ve gathered further evidence that the mesentery should actually be classified as its own distinct organ, and the latest paper makes it official. Mesentery is a double fold of peritoneum – the lining of the abdominal cavity – that holds our intestine to the wall of our abdomen. It was described by the Italian polymath Leanardo da Vinci in 1508, but it has been ignored throughout the centuries, until now. Although there are generally considered to be five organs in the human body, there are in fact now 79, including the mesentery. The heart, brain, liver, lungs and kidneys are the vital organs, but there are another 74 that play a role in keeping us healthy. The distinctive anatomical and functional features of mesentery have been revealed that justify designation of the mesentery as an organ. Accordingly, the mesentery should be subjected to the same investigatory focus that is applied to other organs and systems. This provides a platform from which to direct future scientific investigation of the human mesentery in health and disease.

References:

http://www.thelancet.com/journals/langas/article/PIIS2468-1253(16)30026-7/abstract

http://www.sciencealert.com/it-s-official-a-brand-new-human-organ-has-been-classified

http://www.bbc.com/news/health-38506708

http://www.independent.co.uk/news/science/new-organ-mesentery-found-human-body-digestive-system-classified-abdominal-grays-anatomy-a7507396.html

https://in.news.yahoo.com/scientists-discover-human-organ-064207997.html

https://en.wikipedia.org/wiki/Mesentery

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