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Dr. Craig Venter: The future of biology – Designing life

December 6, 2013 by 2012pharmaceutical

Dr. Craig Venter: The future of biology – Designing life

Reporter: Aviva Lev-Ari, PhD, RN

 

See on Scoop.it – Cardiovascular and vascular imaging

See on www.youtube.com

Posted in 3D Printing for Medical Application | Leave a Comment »

FDA: Nuclear stress test agents carry fatal risks

December 6, 2013 by 2012pharmaceutical

See on Scoop.it – Cardiovascular and vascular imaging

The U.S. Food and Drug Administration has issued a warning that there is a rare but serious risk of heart attack or death associated with the use of cardiac nuclear stress test agents Lexiscan (regadenson) and Adenoscan (adenosine).

See on www.fiercemedicalimaging.com

Posted in Uncategorized | Leave a Comment »

Human Stem Cells Elucidate the Mechanisms of Beta-Cell Failure in Diabetes

December 5, 2013 by larryhbern

Lucid description of mutation changes and their effects on endoplasmic reticulum, mitochondria, with apoptosis, and resulting in diabetes and neuronal secondary damage.

Posted in Uncategorized | Leave a Comment »

Third Annual TCGC: The Clinical Genome Conference, San Francisco, June 10-12, 2014 by Bio-IT World and Cambridge Healthtech Institute

December 4, 2013 by 2012pharmaceutical

Third Annual TCGC: The Clinical Genome Conference, San Francisco, June 10-12, 2014 by Bio-IT World and Cambridge Healthtech Institute

Reporter: Aviva Lev-Ari, PhD, RN

 

UPDATED on 5/1/2014

Register by May 2 for

Hotel Kabuki, San Francisco, CA

June 10 – 12, 2014

FINAL AGENDA

CLINICAL GENOME

conference

THE 3rd ANNUAL

Mining the Genome for Medicine Clinical Genome Conference.com

TCGC

The unstoppable march of genomics into clinical practice continues. In an ideal world, the expanding use of genomic tools will identify disease before the onset of clinical symptoms and determine individualized drug treatment leading to precision medicine. However, many challenges remain or the successful translation of genomic knowledge and technologies into health advances and actionable patient care. Join vital discussions of the applications, questions and solutions surrounding clinical genome analysis.

KEYNOTE SPEAKERS

Atul Butte, M.D., Ph.D.

Division Chief and Associate Professor, Stanford University School of Medicine; Director, Center for Pediatric Bioinformatics, Lucile Packard Children’s Hospital

David Galas, Ph.D.

Principal Scientist, Pacific Northwest Diabetes Research Institute

Gail P. Jarvik, M.D., Ph.D.

Head, Division of Medical Genetics, Arno G. Motulsky Endowed Chair in Medicine and Professor, Medicine and Genome Sciences, University of Washington Medical Center

John Pfeifer, M.D., Ph.D.

Vice Chair, Clinical Affairs, Pathology and Immunology; Professor, Pathology and Immunology, Washington University

John Quackenbush, Ph.D.

Professor, Dana-Farber Cancer Institute and Harvard School of Public Health; Co-Founder and CEO, GenoSpace

Topics Include:

• Working with the Payer Process

• Genome Variation and Clinical Utility

• NGS Is Guiding Therapies

• NGS Is Redefining Genomics

• Interpretation and Translation to the Client

• Integrating Genomic Data into the Clinic

ClinicalGenomeConference.com

Cambridge Healthtech Institute

250 First Avenue, Suite 300

Needham, MA 02494

www.healthtech.com

 

TUESDAY, JUNE 10

7:30 am Conference Registration and Morning Coffee

Working with the Payer Process

8:30 Chairperson’s Opening Remarks

»»KEYNOTE PRESENTATION

8:45 Case Study on Working through the Payer Process

John Pfeifer, M.D., Ph.D., Vice Chair, Clinical Affairs, Pathology; Professor,

Pathology and Immunology; Professor, Obstetrics and Gynecology, Washington

University School of Medicine

If next-generation sequencing (NGS) is to become a part of patient care in routine clinical practice (whether in the setting of oncology or in the setting of inherited genetic disorders), labs that perform clinical NGS must be reimbursed for the testing they provide. Genomics and Pathology Services at Washington University in St. Louis (GPS@WUSTL) will be used as a case study of a national reference lab that has been successful in achieving high levels of reimbursement for the clinical NGS testing it performs, including from private payers. The reasons for GPS’s success will be discussed, including NGS test design, clinical focus of testing, use of different models for reimbursement and payer education.

9:30 Implementation of Clinical Cancer Genomics within an Integrated

Healthcare System

Lincoln D. Nadauld, M.D., Ph.D., Director, Cancer Genomics, Intermountain Healthcare

Precision cancer medicine involves the detection of tumor-specific DNA alterations followed by treatment with therapeutics that specifically target the actionable mutations. Significant advances in genomic technologies have now rendered extended genomic analyses of human malignancies technologically and financially feasible for clinical adoption. Intermountain Healthcare, an integrated healthcare delivery system, is taking advantage of these advances to programmatically implement genomics into the regular treatment of cancer patients to improve clinical outcomes and reduce treatment costs.

10:00 PANEL DISCUSSION:

Payer’s Dilemma: Evolution vs. Revolution

As falling genome sequencing costs help clinicians refine patient diagnoses and therapeutic approaches, new complexities arise over insurance coverage of such tests, classification by CPT codes and other reimbursement issues. Experts on this panel will discuss payer challenges and changes—both rapid and gradual—occurring alongside these advances in clinical genomics.

Moderator: Katherine Tynan, Ph.D., Business Development & Strategic Consulting for Diagnostics

Companies, Tynan Consulting LLC

Panelists:

Tonya Dowd, MPH, Director, Reimbursement Policy and Market Access, Quorum Consulting

Mike M. Moradian, Ph.D., Director of Operations and Molecular Genetics Scientist, Kaiser

Permanente Southern California Regional Genetics Laboratory

Rina Wolf, Vice President of Commercialization Strategies, Consulting and Industry Affairs, XIFIN

Additional Panelists to be Announced

10:45 Networking Coffee Break

11:15 Beyond Genomics: Preparing for the Avalanche of Post-Genomic

Clinical Findings

Jimmy Lin, M.D., Ph.D., President, Rare Genomics Institute

Whole genomic and exomics sequencing applied clinically is revealing newly discovered genes and syndromes at an astonishing rate. While clinical databases and variant annotation continue to grow, much of the effort needed is functional analysis and clinical correlation. At RGI, we are building a comprehensive functional genomics platform that includes electronic health records, biobanking, data management, scientific idea crowdsourcing and contract research sourcing.

11:45 The MMRF CoMMpass Clinical Trial: A Longitudinal Observational

Trial to Identify Genomic Predictors of Outcome in Multiple Myeloma

Jonathan J. Keats, Ph.D., Assistant Professor, Integrated Cancer Genomics Division, Translational

Genomics Research Institute

12:15 pm Luncheon Presentation: Sponsored by

Big Data & Little Data – From Patient Stratification

to Precision Medicine

Colin Williams, Ph.D., Director, Product Strategy, Thomson Reuters

Molecular data has the power, when unlocked, to transform our understanding of disease to support drug discovery and patient care. The key to unlocking this potential is ‘humanising’ the data, through tools and techniques, to a level that supports interpretation by Life Science professionals. This talk will focus on strategies for extracting insight from ‘big data’ by shrinking it to ‘little data’, with a focus on applications to support patient stratification in drug discovery and for practising precision medicine in a clinical setting.

Genome Variation and Clinical Utility

1:45 Chairperson’s Remarks

»»KEYNOTE PRESENTATION

1:50 Lessons from the Clinical Sequencing Exploratory

Research (CSER) Consortium: Genomic Medicine

Implementation

Gail P. Jarvik, M.D., Ph.D., Head, Division of Medical Genetics, Arno G. Motulsky Endowed Chair in Medicine and Professor, Medicine and Genome

Sciences, University of Washington Medical Center

Recent technologies have led to affordable genomic testing. However, implementation of genomic medicine faces many hurdles. The Clinical Sequencing Exploratory Research (CSER) Consortium, which includes nine genomic medicine projects, was formed to explore these challenges and opportunities. Dr. Jarvik is the PI of a CSER genomic medicine project and of the CSER coordinating center. She will focus on the frequency of exomic incidental findings, including those of the 56 genes recommended for incidental finding return by the ACMG. The CSER group has annotated the putatively pathogenic and novel variants of the Exome Variant Server (EVS) to estimate the rate of these in individuals of European and African ancestry. Experience with consenting and returning incidental findings will also be reviewed.

2:35 Decoding the Patient’s Genome: Clinical Use of Genome-Wide

Sequencing Data

Elizabeth Worthey, Ph.D., Assistant Professor, Pediatrics & Bioinformatics Program, Human & Molecular Genetics Center, Medical College of Wisconsin

Despite significant advances in our understanding of the genetic basis of disease, genomewide identification and subsequent interpretation of the molecular changes that lead to human disease represent the most significant challenges in modern human genetics.

Starting in 2009 at MCW, we have performed clinical WGS and WES to diagnose patients coming from across all clinical specialties. I will discuss findings, pros and cons in approach, challenges remaining and where we go next.

3:05 Analyzing Variants with a DTC Genetics Database

Brian Naughton, Ph.D., Founding Scientist, 23andMe, Inc.

Sequencing a genome results in dozens of potentially disease-causing variants (VUS). I describe some examples of using the 23andMe database, including quick recontact of participants, to determine if a variant is disease-causing.

3:35 Refreshment Break in the Exhibit Hall with Poster Viewing

 

Genome Interpretation Software Solutions: Software Spotlights

(Sponsorship Opportunities Available)

Obtaining clinical genome data is rapidly becoming a reality, but analyzing and interpreting the data remains a bottleneck. While there are many commercial software solutions and pipelines for managing raw genome sequence data, providing the medical interpretation and delivering a clinical diagnosis will be the critical step in fulfilling the promise of genomic medicine. This session will showcase how genome data analysis companies are streamlining the genomic diagnostic pipeline through:

• Transferring raw sequencing data

• Interpreting genetic variations

• Building new software and cloud-based analysis pipelines

• Investigating the genetic basis of disease or drug response

• Integrating with other clinical data systems

• Creating new medical-grade databases

• Reporting relevant clinical information in a physician-friendly manner

• Continuous learning feedback

4:15 Software Spotlight #1

4:30 Copy Number Variant Detection Using Sponsored by

Next-Generation Sequencing: State of the Art

Alexander Kaplun, Ph.D., Field Applications Scientist, BIOBASE

This talk will provide a short review about the current state of the art in detection of larger variants that have an important role in many diseases such as haplotypes, indels, repeats, copy number variants (CNVs), structural variants (SVs) and fusion genes using NGS methods, and an outlook to their use for pharmacogenomic genotyping.

4:45 Software Spotlight #3

5:00 Software Spotlight #4

5:15 Software Spotlight #5

5:30 Pertinence Metric Enables Hypothesis-Independent Sponsored by

Genome-Phenome Analysis in Seconds

Michael M. Segal, M.D., Ph.D., Chief Scientist, SimulConsult

Genome-phenome analysis combines processing of a genomic variant table and comparison of the patient’s findings to those of known diseases (“phenome”). In a study of 20 trios, accuracy was 100% when using trios with family-aware calling, and close to that if only probands were used. The gene pertinence metric calculated in the analysis was 99.9% for the causal genes. The analysis took seconds and was hypothesis-independent as to form of inheritance or number of causal genes. Similar benefits were found in gene discovery situations.

6:00 Welcome Reception in the Exhibit Hall with Poster Viewing

7:00 Close of Day

WEDNESDAY, JUNE 11

7:30 am Breakfast Presentation (Sponsorship Opportunity Available) or Morning Coffee

NGS Is Guiding Therapies

8:30 Chairperson’s Opening Remarks

8:35 Next-Generation Sequencing Approaches for Identifying Patients

Who May Benefit from PARP Inhibitor Therapy

Mitch Raponi, Ph.D., Senior Director and Head, Molecular Diagnostics, Clovis Oncology

The following questions will be addressed: What biomarkers should we be focusing on to identify appropriate patients who will likely benefit from PARP inhibitors? How can we apply next-generation sequencing technologies to identify all patients who will respond to the PARP inhibitor rucaparib? What regulatory challenges are we faced with for approval of NGS companion diagnostics?

9:05 Whole-Genome and Whole-Transcriptome Sequencing to Guide

Therapy for Patients with Advanced Cancer

Glen J. Weiss, M.D., MBA, Director, Clinical Research, Cancer Treatment Centers of America

Treating advanced cancer with agents that target a single-cell surface receptor, up-regulated or amplified gene product or mutated gene has met with some success; however, eventually the cancer progresses. We used next-generation sequencing technologies (NGS) including whole-genome sequencing (WGS), and where feasible, whole-transcriptome sequencing (WTS) to identify genomic events and associated expression changes in advanced cancer patients. While the initial effort was a slower process than anticipated due to a variety of issues, we demonstrated the feasibility of using NGS in advanced cancer patients so that treatments for patients with progressing tumors may be improved. This lecture will highlight some of these challenges and where we are today in bringing NGS to patients.

9:35 The SmartChip TE™ Target Enrichment System for Sponsored by

Clinical Next-Gen Sequencing

Gianluca Roma, MS MBA, Director, Product Management, WaferGen Biosystems

10:05 Coffee Break in the Exhibit Hall with Poster Viewing

Data Mining

»»KEYNOTE PRESENTATION

10:45 Translating a Trillion Points of Data into

Therapies, Diagnostics and New Insights into Disease

Atul Butte, M.D., Ph.D., Division Chief and Associate Professor, Stanford University School of Medicine; Director, Center for Pediatric Bioinformatics,

Lucile Packard Children’s Hospital; Co-Founder, Personalis and Numedii

There is an urgent need to translate genome-era discoveries into clinical utility, but the difficulties in making bench-to-bedside translations have been well described. The nascent field of translational bioinformatics may help. Dr. Butte’s lab at Stanford builds and applies tools that convert more than a trillion points of molecular, clinical and epidemiological data— measured by researchers and clinicians over the past decade—into diagnostics, therapeutics and new insights into disease. Dr. Butte, a bioinformatician and pediatric endocrinologist, will highlight his lab’s work on using publicly available molecular measurements to find new uses for drugs, including drug repositioning for inflammatory bowel disease, discovering new treatable inflammatory mechanisms of disease in type 2 diabetes and the evaluation of patients presenting with whole genomes sequenced.

11:30 DGIdb – Mining the Druggable Genome

Malachi Griffith, Ph.D., Research Faculty, Genetics, The Genome Institute, Washington University School of Medicine

In the era of high-throughput genomics, investigators are frequently presented with lists of mutated or otherwise altered genes implicated in human disease. Numerous resources exist to generate hypotheses about how such genomic events might be targeted therapeutically or prioritized for drug development. The Drug-Gene Interaction database (DGIdb) mines these resources and provides an interface for searching lists of genes against a compendium of drug-gene interactions and potentially druggable genes. DGIdb can be accessed at dgidb.org.

12:00 pm Sponsored Presentation (Opportunity Available)

12:30 Luncheon Presentation (Sponsorship Opportunity Available)

 

The unstoppable march of genomics into clinical practice continues. In an ideal world, the expanding use of genomic tools will identify disease before the onset of clinical symptoms and determine individualized drug treatment leading to precision medicine. However, many challenges remain for the successful translation of genomic knowledge and technologies into health advances and clinical practice.

Bio-IT World and Cambridge Healthtech Institute are again proud to host the Third Annual TCGC: The Clinical Genome Conference, inviting stakeholders from all arenas impacting clinical genomics to share new findings and solutions for advancing the application of clinical genome medicine.

TCGC brings together many constituencies for frank and vital discussion of the applications, questions and solutions surrounding clinical genome analysis, including scientists, physicians, diagnosticians, genetic counselors, bioinformaticists, ethicists, regulators, insurers, lawyers and administrators.

Topics addressing successful translation of genomic knowledge and technologies into advancement of clinical utility (medicines and diagnostics) include but are not limited to:

Scientific Investigation and Interpretation

  • Technologies/Platforms
  • WGS/Exome/Single-Cell Sequencing
  • Drug and Diagnostic Targets
  • Interpretation and Analysis Pipelines
  • Case Studies

Clinical Integration and Implementation

  • Mechanisms to Monitor Genomic Medicine
  • Determining Clinical Utility
  • Standardization/Regulation/Certification
  • Reimbursement
  • Data Management
  • Diagnostic Lab Infrastructure
  • HIT/Data Integration
  • Reporting Results to Patients/Physicians

Call for Speakers
For a limited time, we are inviting researchers and clinicians applying genome analysis tools in clinical settings, as well as regulators and administrators implementing genomics into the clinic, to submit proposals for platform presentations. Please note that due to limited speaking slots, preference is given to abstracts from those within pharmaceutical and biopharmaceutical companies, regulators and those from academic centers. Additionally, as per CHI policy, a select number of vendors/consultants who provide products and services to these genomic researchers are offered opportunities for podium presentation slots based on a variety of Corporate Sponsorships.

All proposals are subject to review by the organizers and Scientific Advisory Committee.

Please click here to submit a proposal.

Submission deadline for priority consideration: November 15, 2013

For more details on the conference, please contact:
Mary Ann Brown
Executive Director, Conferences
Cambridge Healthtech Institute
250 First Avenue, Suite 300
Needham, MA 02494
T:  781-972-5497
E:  mabrown@healthtech.com

For exhibit and sponsorship opportunities, please contact:
Jay Mulhern
Manager, Business Development, Conferences & Media
Cambridge Healthtech Institute
250 First Avenue, Suite 300
Needham, MA 02494
T: 781-972-1359
E: jmulhern@healthtech.com

SOURCE

http://www.clinicalgenomeconference.com/

 

Posted in Biological Networks, Gene Regulation and Evolution, CANCER BIOLOGY & Innovations in Cancer Therapy, Computational Biology/Systems and Bioinformatics, Genome Biology, Genomic Expression, Genomic Testing: Methodology for Diagnosis, Reproductive Andrology, Embryology, Genomic Endocrinology, Preimplantation Genetic Diagnosis and Reproductive Genomics | Tagged , , , | Leave a Comment »

Ischemic Stable CAD (FFR): In >5000 Patients – Medical Therapy and PCI no difference in End Point: Meta-Analysis of Contemporary Randomized Clinical Trials

December 3, 2013 by 2012pharmaceutical

Ischemic Stable CAD: Medical Therapy and PCI no difference in End Point: Meta-Analysis of Contemporary Randomized Clinical Trials

Reporter: Aviva Lev-Ari, PhD, RN

 

SOURCE

Stergiopoulos K, Boden WE, Hartigan P, et al. Percutaneous coronary intervention outcomes in patients with stable obstructive coronary artery disease and myocardial ischemia: A collaborative meta-analysis of contemporary randomized clinical trials. JAMA Intern Med 2013; DOI:10.1001/jamainternmed.2013.12855. Available at:http://www.jamainternalmedicine.com.

 

PCI No Benefit Over Medical Therapy in Ischemic Stable CAD

December 02, 2013

NEW YORK, NY — A new analysis is calling into question the de facto rationale for many of the revascularization procedures taking place today, at least in patients with stable coronary artery disease[1]. In a meta-analysis of more than 5000 patients, PCI was no better than medical therapy in patients with documented ischemia by stress testing or fractional flow reserve (FFR).

“Cardiology has a long history of finding a marker of a bad outcome and treating that marker of that bad outcome as if it were the cause of the bad outcome,” senior author on the study, Dr David Brown (State University of New York [SUNY]–Stony Brook School of Medicine), told heartwire . In the case of proceeding to PCI on the basis of documented ischemia, that stems from evidence that patients with ischemia have a worse prognosis than patients who don’t.”It has gotten to the point that a positive stress test [is the gateway] to doing an intervention, even if the ischemia is not in the same ischemic territory as the vessel being treated,” he said. “The medical/industrial complex in cardiology is now focused on finding and treating ischemia, and I think that’s not justified, and these data suggest that that’s not justified.”

Brown and colleagues, with first author Dr Kathleen Stergiopoulus (SUNY–Stony Brook School of Medicine), reviewed the literature for randomized clinical trials of PCI and medical therapy for stable CAD conducted over the past 40 years, ultimately including five trials of 5286 patients. These were a small German trial published in 2004, plus MASS II , COURAGE , BARI 2D , and FAME 2 . In all, 4064 patients had myocardial ischemia documented by exercise, nuclear or echo stress imaging, or FFR.

Over a median follow-up of five years, mortality, nonfatal MI, unplanned revascularization, and angina were no different between patients treated medically vs those treated with PCI.

Odds Ratio, PCI vs Medical Therapy

Outcome Odds ratio 95% CI
Death 0.90 0.71–1.16
Nonfatal MI 1.24 0.99–1.56
Unplanned revascularization 0.64 0.35–1.17
Angina 0.91 0.57–1.44

“These findings are unique in that this is the first meta-analysis to our knowledge limited to patients with documented, objective findings of myocardial ischemia, almost all of whom underwent treatment with intracoronary stents and disease-modifying secondary-prevention therapy,” Stergiopoulus et al write.

The findings, they continue, “strongly suggest that the relationship between ischemia and mortality is not altered or ameliorated by catheter-based revascularization of obstructive, flow-limiting coronary stenosis.”

To heartwire , Brown pointed out that their analysis could not separate out patients who had small amounts of ischemia from those with larger ischemic territories. “Maybe that’s where the differentiating factor will be,” he acknowledged, adding that the 8000-patient ISCHEMIA trial, still ongoing, will hopefully yield some insights.

Current practice, however, is to check for ischemia and to proceed with catheterization and, usually, revascularization when ischemia is confirmed by stress testing or during FFR. “But if that doesn’t improve outcomes, why are we doing it?” Brown asked. “We think that needs to be rethought.”

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Information from Industry

Commenting on the study for heartwire , Dr Peter Berger(Geisinger Health System, Danville, PA) pointed out: “There is no question that PCI is more effective than medical therapy for relief of symptoms: the more severe the angina and the more active the patient, the greater the superiority of PCI.” And, as Berger noted, most of the studies included in this analysis documented ischemia but did not report on the frequency or severity of angina at baseline.

That said, “Patients with minimal angina—and certainly those with silent ischemia but no angina—are unlikely to have a significantly greater reduction of symptoms with PCI, and PCI is rarely beneficial in such patients.”

Moreover, Berger continued, it has been clearly established that PCI does not reduce the risk of death or MI in most such patients.

“I very much agree with the authors, however, that just because more severe ischemia has been shown to be associated with a worse long-term prognosis, reducing the ischemic burden ought not be assumed to reduce the likelihood of death or MI. In most such patients, it does not.”

Stergiopoulos and Brown had no disclosures. Disclosures for the coauthors are listed in the paper.

SOURCE 

Posted in Atherogenic Processes & Pathology, Cardiac and Cardiovascular Surgical Procedures, Cardiovascular Research, Frontiers in Cardiology and Cardiovascular Disorders, Medical Devices R&D and Inventions, Myocardial metabolism, Myocardial ischemia, myocardial perfusion, Myocardial adenine nucleotide metabolism, Origins of Cardiovascular Disease, PCI, Pharmacotherapy of Cardiovascular Disease, Stents & Tools | Tagged , , , , , | Leave a Comment »

Hyperhomocysteinemia interaction with Protein C and Increased Thrombotic Risk

December 3, 2013 by larryhbern

Hyperhomocysteinemia interaction with Protein C and Increased Thrombotic Risk

Reporter and Curator: Larry H Bernstein, MD, FCAP

 

This document explores the relationship between thromboembolic risk related to hyperhomocysteinemia related to the HHcy interaction with and blocking the protective effect of APC.

Previous Venous Thromboembolism Relationships With Plasma Homocysteine Levels

Marco Cattaneo, Franca Franchi, Maddalena L. Zighetti, Ida Martinelli, Daniela Asti, P. Mannuccio Mannucci
Arterioscler Thromb Vasc Biol. 1998;18:1371-1375.
Received January 28, 1998; revision accepted March 16, 1998. From the Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Institute of Internal Medicine, IRCCS Ospedale Maggiore, University of Milano, Italy.
Correspondence to Marco Cattaneo, MD, Hemophilia and Thrombosis Center, Via Pace 9, 20122 Milano, Italy. E-mail marco.cattaneo@unimi.it © 1998 American Heart Association, Inc. 1371 Original Contributions

Abstract—

The proteolytic enzyme activated protein C (APC) is a normal plasma component, indicating that protein C (PC) is continuously activated in vivo. High concentrations of homocysteine (Hcy) inhibit the activation of PC in vitro;

  • this effect may account for the high risk for thrombosis in patients with hyperhomocysteinemia (HyperHcy).

We measured the plasma levels of APC in 128 patients with previous venous thromboembolism (VTE) and in 98 age- and sex-matched healthy controls and

  • correlated them with the plasma levels of total Hcy (tHcy) measured before and after an oral methionine loading (PML).

Forty- eight patients had HyperHcy and 80 had normal levels of tHcy. No subject was known to have any of the congenital or acquired thrombophilic states at the time of the study.  Because the plasma levels of APC and PC were correlated in healthy controls,  the APC/PC ratios were also analyzed.

Plasma APC levels and APC/PC ratios were significantly higher in VTE patients than in controls (P < 0.03 and 0.0004, respectively).

  • Most of the increase in APC levels and APC/PC ratios were attributable to patients with HyperHcy.

Patients with normal tHcy had intermediate values, which did not differ significantly from those of healthy controls.

  • There was no correlation between the plasma levels of tHcy or its PML increments and APC or APC/PC ratios in controls.
  • The fasting plasma levels of APC and APC/PC ratios of 10 controls did not increase 4 hours PML, despite a 2-fold increase in tHcy.

This study indicates that

  • APC plasma levels are sensitive markers of activation of the hemostatic system in vivo and
  • that Hcy does not interfere with the activation of PC in vivo.

Key Words: homocysteine, protein C, thromboembolism, activated protein C, hypercoagulability,  T mechanism.

The zymogen protein C is converted to the active protease, activated protein C (APC),

  • through proteolytic cleavage by thrombin bound to its endothelial membrane receptor thrombomodulin.1

The demonstration that APC is a normal plasma component,2,3whose enzymatic activity can be detected with specific and sensitive methods,4,5indicates that

  • the protein C anticoagulant pathway is continuously activated in vivo.

Measurement of APC plasma levels might therefore be helpful in determining the in vivo integrity of the protein C anticoagulant pathway. More generally,

  • APC levels might mirror the in vivo activation of the coagulation system and
  • serve as a marker of thrombin activity in the circulation.4

The mechanism(s) by which a moderate elevation of plasma levels of homocysteine (Hcy) increases the risk for arterial and venous thrombotic disease is still unclear.6,7 In vitro studies showed that

  • Hcy inhibits the thrombomodulin- dependent protein C activation to APC and
  • interferes with the expression of thrombomodulin on human umbilical vein endothelial cells.8–10

These findings may be relevant to unravel the thrombogenic mechanism of Hcy, because

the protein C anticoagulant system is of major physiological importance in the regulation of the hemostatic  congenital or acquired disorders

  • characterized by impaired production or function of APC are associated with a high risk for venous thromboembolism (VTE).11

It must be noted, how ever, that these in vitro findings have been obtained by using very high concentrations of Hcy,

  • at least 1 order of magnitude higher than the plasma concentrations found in patients with homozygous homocystinuria.12,13

Their clinical relevance is therefore uncertain and awaits confirmation from ex vivo and/or in vivo studies in humans. In this study, we compared the plasma levels of APC with those of the prothrombin fragment F1,2, a marker of thrombin generation,14in healthy subjects and patients with previous episodes of VTE and

  • tested whether the levels are affected by plasma Hcy concentrations.

Methods

Materials

L-Methionine, tri-n-butylphosphine, 7-fluoro-2,1,3-benzoxadiazole- 4-sulfonamide (ABDF), L-cystine, Tween 20, Tween 80, benzamidine, and HEPES were from Sigma. (4-Amidinophenyl)-methanesulfonylfluoride (APMSF) was from Boehringer, BSA from Calbiochem, and the chromogenic substrate L-homocystine, ovalbumin, S-2366 from Chromogenics. The monoclonal antibody directed against the light chain of protein C (C3-Mab) was a kind gift of Dr H.P. Schwarz (Immuno, Vienna, Austria). All other chemicals were of reagent grade. Subjects We studied 128 patients with previous VTE and 98 healthy controls. All diagnoses of thrombotic episodes, excluding those of superficial veins, had been confirmed by objective methods: compression ultrasonography or venography for deep vein thrombosis; and ventilation/perfusion scintigraphy for pulmonary embolism. The contemporary presence of deep vein thrombosis in patients with superficial vein thrombosis had not been excluded by objective methods. Table 1 shows the characteristics of the patients studied.

They belonged to a cohort of 315 patients who had been screened for thrombophilic states at our Center between December 1993 and July 1995 and were selected on the basis of the following characteristics:
(1) absence of congenital or acquired thrombophilic states except hyperhomocysteinemia (HyperHcy) (see below);
(2) oral anticoagu- lant therapy discontinued at least 1 month before screening;
(3) at least 4 months elapsed since the last thrombotic episode; and
(4) willingness to participate in the study.

The screening for thrombophilia included the following tests:

  • prothrombin time;
  • activated partial thromboplastin time;
  • thrombin time;
  • plasma levels of fibrinogen,
  • protein C,
  • protein S, and
  • antithrombin;
  • APC resistance; and
  • screening for antiphospholipid syndrome15 and
  • plasma levels of total homocysteine (tHcy)

before and 4 hours after an oral methionine load. Patients with abnormal APC resistance were also screened for factor V Leiden.16

The study was designed and completed before the demonstration that the mutation G20210A of the prothrombin gene is a risk factor for deep vein thrombosis.17 This mutation therefore was looked for retrospectively only in those subjects whose DNA was still available for analysis (all controls and 50 patients): 5 patients (10%) and 2 controls (2.1%) were heterozygous for the mutation. Of the 128 patients enrolled in the study,

  • 48 had hyperhomocysteinemia (VTE-HyperHcy) according to the diagnostic criteria outlined below, and
  • 80 had normal Hcy levels (VTE-NormoHcy).
    • The healthy controls, who were age and sex matched with the patients (male/female, 50/45; median age, 40 years [range, 20 to 73 years]), had been chosen from the same geographical area and with the same socioeconomic background as the patients.
  1. Previous episodes of thrombosis had been ruled out by a validated structured questionnaire.18
  2. No subject had abnormal liver or renal function, or overt autoimmune or neoplastic disease.
  3. Informed consent to participate in the study was obtained from all subjects.
  4. The study was approved by the ethics committee of the University of Milano.

Study Protocol

After an overnight fast, blood samples were drawn between 8:30 and 9:30 AM in K3-EDTA for measurement of total Hcy (tHcy), in 0.013 mol/L trisodium citrate for measurement of F1?2 and protein C, and in citrate plus 0.03 mol/L benzamidine (a reversible inhibitor of APC) for measurement of APC. L-Methionine (3.8 g/m2body surface area) was then administered orally in approximately 200 mL of orange juice. Four hours later, a second blood sample was collected in EDTA for tHcy measurement from all subjects and in citrate plus benzamidine for measurement of APC plasma levels from 10 controls. All subjects remained in the fasting state until the second blood sample had been taken. Plasma Hcy Assay Blood samples in K3-EDTA were immediately placed on ice and centrifuged at 2000xG, 4°C, for 15 minutes. The supernatant was stored in aliquots at < 70°C until assay.
The plasma levels of tHcy (free and protein bound) were determined by high-performance liquid chromatography (Waters Millipore 6000A pump, Millipore) and fluorescence detection (Waters 474) by the method of Ubbink et al,19with slight modifications.20 Briefly, 100 uL of plasma was incubated with 10 uL of 10% tri-n-butylphosphine in dimethylfor- mamide at 4°C for 30 minutes to reduce homocystine and mixed disulfide and deconjugate Hcy from plasma proteins. Then, 100 uL of 10% trichloroacetic acid was added, and the mixture was centrifuged in an Eppendorf microcentrifuge at 13 000 rpm for 10 minutes.
After centrifugation, the mixture was incubated with 1 mg/mL ABDF in borate buffer to derivatize the thiols. The mobile phase, pumped at 1 mL/min, consisted of 0.1 mol/L potassium dihydrogenophosphate, 0.06 mmol/L EDTA, and 12% acetonitrile (pH = 2.1).

Criteria for Diagnosis of HyperHcy  HyperHcy was diagnosed when
  1. fasting plasma levels of tHcy or its postmethionine load absolute increments above fasting levels exceeded the 95th percentiles of distribution of values obtained in 388 healthy controls.
Measurement of Plasma APC  Plasma APC levels were measured with < enzyme capture assay, essentially as described by Gruber and Griffin.4 Blood samples were

TABLE 1.
Patients With Previous VTE-NormoHcy

Demographic Characteristics of Patients With Previous VTE-HyperHcy
VTE-HyperHcyVTE-NormoHcy                                                                                                        4880
No. Males/females                                                                                                                                                23/25
Median age, y (range)                                                                                                                                     36 (19–69)
Median age at the first thrombotic episode, y (range)                                                                     32 (17–62)
Time elapsed since last episode, mo (range)                                                                                        14 (4–70)
Time elapsed since discontinuation of oral anticoagulant therapy, mo (range)                   11 (1–64)Type of first thrombotic episode
Deep vein thrombosis                                                                                                                                       31/49
Pulmonary embolism                                                                                                                                    36 (14–62)
Superficial vein thrombosis                                                                                                                       31 (13–60)
Venous thrombosis of other sites                                                                                                           14 (4–90)                                                                                                                                                                          
With 1 or more episodes                                                                                                                              11 (1–70)
2233                                                                                                                                                                    26 (54.2%)
With circumstantial risk factors* at first episode                                                                             44 (55%)
*The following circumstantial risk factors were considered: surgery (26), trauma (50), immobilization (47), pregnancy/puerperium (16,21), and oral contraceptives (22).

1372

Activated Protein C, Thrombosis, and Homocysteine

centrifuged within 60 minutes from collection at 1200xG, 4°C, for 30 minutes to obtain platelet-poor plasma, which was frozen in aliquots at < 70°C. A plasma pool from 30 healthy individuals (15 men, 15 women) was obtained in the same way and used to prepare the standards.
(removed)…  The chromogenic substrate for APC S-2366 (0.46 mmol/L in Tris-buffered saline, pH 7.4) was then added to the wells. After incubation of the sealed plates at 4°C in wet chambers for 3 weeks, hydrolysis of the substrate was monitored at a dual wavelength setting of 405/655 nm.
The concentration of APC in the unknown samples was calculated from the absorbance of each sample with the standard curve as a reference. Results were expressed as percentage of pooled normal plasma. Measurement of Plasma F1?2 F1?2 was assayed by a commercial ELISA (Behringwerke), as previously described.21

Statistical Analysis

The two-tailed t test was used to compare VTE patients and healthy controls. ANOVA was used to compare VTE-HyperHcy, VTE controls, and healthy controls, followed by the Dunnett’s test for internal contrasts. The Pearson r value was calculated for correla- tions between the variables studied.

Results

The results obtained in all VTE patients and controls are presented, including those with the heterozygous G20210A mutation of the prothrombin gene. A subanalysis of the results obtained in the 40 patients and 98 controls, in whom the mutation was looked for, revealed that

  • exclusion of the subjects heterozygous for the mutation did not significantly affect the results.

Plasma tHcy Levels

The mean (SD) fasting levels of plasma tHcy were significantly higher in VTE-HyperHcy (28.8?19.5 ?mol/L) than in VTE-NormoHcy (12.0+5.2, P<0.001) and healthy con- trols (11.0+5.3, P<0.001). The mean postmethionine load increments of tHcy above fasting levels were also higher in VTE-HyperHcy (32.9+13.5 umol/L) than in VTE- NormoHcy (19.8+7.5, P<0.001) and healthy controls (16.1+7.6, P<0.001). Differences between VTE-NormoHcy and healthy controls were not statistically significant. Six healthy controls (6.3%) had HyperHcy, according to the diagnostic criteria previously outlined. Plasma Levels of APC Healthy Controls The mean plasma level of APC in healthy controls was 116(20%). There was a statistically significant correlation between the plasma levels of APC and those of protein C (r?0.48, P?0.001) (Figure 1). Therefore, because APC levels are influenced by the concentration of their zymogen, both the absolute APC levels and the activated protein C/protein C (APC/PC) ratios were used for subsequent analysis. The mean value of the APC/PC ratio in healthy controls was 1.01?0.2.

There was no correlation between the plasma levels of APC (not shown) or the APC/PC ratios and the fasting plasma levels of tHcy (Figure 2) or its postmethionine load increments above fasting levels (not shown). The mean APC plasma levels and APC/PC ratios were similar in healthy controls whose tHcy plasma levels fell within the first (115 and 1.0), second (118 and 0.96), or third (115 and 1.01) tertiles of distribution. The mean fasting plasma levels of APC and the APC/PC ratios of 10 healthy controls

– did not significantly differ from those measured in the same subjects 4 hours after an oral methionine load,
– which increased the concentration of tHcy by more than 2-fold (Table 2).

VTE Patients

The mean plasma levels of APC and APC/PC ratios were higher in VTE patients than in healthy controls (124?32 versus 116?20, P?0.03 and 1.12?0.32 versus 0.99?0.19, P?0.0004). This difference was mostly due to VTE- HyperHcy patients whose plasma APC levels and APC/PC ratios were significantly higher than those of healthy controls (Table 3). In contrast, differences between VTE-NormoHcy and healthy controls and between VTE-HyperHcy and VTE- NormoHcy did not reach statistical significance (Table 3). Results did not change substantially when we excluded patients with thrombosis of the superficial veins (APC levels, 124+26 in VTE-HyperHcy and 121?31 in VTE-NormoHcy; APC/PC ratio, 1.17?0.25 in VTE-HyperHcy and 1.09?0.3 Figure 1. Correlation between the plasma levels of protein C and APC in 98 healthy volunteers. Values are expressed as per- centage of the concentrations measured in pooled normal plasma from 30 healthy blood donors. Figure 2. Correlation between the fasting plasma levels of tHcy and APC/PC ratios of 98 healthy volunteers. Cattaneo et al September 1998 1373 in VTE-NormoHcy) or women taking oral contraceptives (APC levels, 115?19 in controls, 130?29 in VTE- HyperHcy, and 121+33 in VTE-NormoHcy; APC/PC ratio, 0.98?0.23 in controls, 1.13?0.4 in VTE-HyperHcy, and 1.08?0.3 in VTE-NormoHcy). The prevalence of high APC/PC ratios was significantly higher in VTE patients than in controls, independent of the tHcy levels in their plasma (Table 4),

-whereas that of high plasma APC levels was significantly increased in VTE- HyperHcy patients only (Table 4).

Plasma Levels of F1?2

The mean plasma level of F1?2 in VTE patients (1.6?0.5 nmol/L) did not significantly differ from that measured in healthy controls (1.5?0.6 nmol/L). There was no statistically significant difference between plasma levels of F1?2 in VTE-HyperHcy (1.6?0.6 nmol/L), VTE-NormoHcy (1.6?0.6 nmol/L), and healthy controls. The mean F1?2 plasma levels were similar in healthy controls whose plasma levels of tHcy fell within the first, second, or third tertiles of distribution (not shown). F1?2 levels and APC/PC ratios were significantly correlated in controls (r?0.28, P?0.005) but not in VTE-HyperHcy (r? ?0.03, P?0.05) or VTE- NormoHcy (r?0.08, P?0.05).

Discussion

This study shows that

–  patients with previous episodes of VTE have higher circulating plasma levels of APC than healthy controls, particularly if they have HyperHcy.

The patients studied had none of the known congenital or acquired thrombophilic states, in which

–  the circulating levels of markers of activation of the coagulation system may be increased.21–24Even
– though the recently described G20210A mutation of the prothrombin gene17could be looked for retrospectively in only approximately one third of the pa- tients, also those patients in whom the prothrombin mutation was ruled out had high APC levels,
– excluding that they were mainly due to the presence of the mutation.

APC is generated from its plasma precursor, protein C, on activation by thrombin-thrombomodulin complex on the endothelial cell surface, probably acting in concert with the endothelial cell protein C receptor.1Subcoagulant amounts of thrombin in the circulation may increase the plasma levels of endogenous APC, which can therefore be considered markers of a hypercoagulable state.4Accordingly, the high APC plasma levels that we measured in patients with previous episodes of VTE may be interpreted as an index of ongoing thrombin formation,
despite the fact that at least 4 months (and a median of 14 months) elapsed since their last thrombotic episode. However,

–  the plasma concentrations of F1?2, a marker of thrombin generation, were not increased signifi cantly in the same VTE patients and were not correlated with APC levels or APC/PC ratios.

In contrast to VTE patients, a statistically significant correlation between APC and F1?2 plasma levels was found in healthy controls. On the basis of these data, we hypothesize that

–  the increased plasma levels of APC found in patients with previous episodes of VTE are not caused by heightened thrombin generation but by alternative mechanisms. Although we did not measure markers of activation of the fibrinolytic system,

– the possibility that high plasma levels of plasmin could be responsible for protein C activation25in these patients should be considered.

The greatest increase of APC plasma levels in VTE patients was observed in subjects with fasting and/or postmethionine-loading HyperHcy. VTE patients with nor mal plasma levels of tHcy had lower concentrations of APC than patients with HyperHcy, but this

–  difference could be due to chance alone, because it was not statistically significant. These results contrast with the alleged inhibitory effect of Hcy on protein C activation that was shown in in vitro studies.8–10

Our data obtained in healthy individuals

– support the view that Hcy does not affect protein C activation in vivo, because the
– mean plasma levels of APC of subjects in the highest tertile of distribution of tHcy levels were not different from those of subjects in the lowest tertile. Moreover,
– the rapid increase in plasma tHcy brought about by an oral methionine load did not affect the concentration of circulating APC

TABLE 2. Healthy Controls Before and 4 Hours After Methionine Loading (PML) Plasma Levels tHcy, APC, and APC/PC Ratios in 10 tHcy, ?mol/LAPC, %APC/PC Ratio Baseline 4 h PML* P† 10.5?3.8 29.5?7.6 0.0001 118?43 113?32 0.57 0.98?0.2 0.95?0.1 0.7 Data are mean?SD. *Methionine was given orally at a dose of 3.8 g/m2body surface area. †t test for paired samples. TABLE 4. APC/PC Ratios in Healthy Controls, Patients With Previous VTE-HyperHcy, and Patients With Previous VTE-NormoHcy Prevalences of High Plasma Levels of APC and Subjectsn With High APC LevelsWith High APC/PC Ratio n (%)OR (95% CI) n (%)OR (95% CI) Healthy controls 98 10 (10.2) 1.0 (reference) 10 (10.2) 1.0 (reference) VTE-HyperHcy48 12 (25.0) 2.9 (1.1–8.3) VTE-NormoHcy80 16 (20.0) 2.2 (0.9–5.7) 16 (33.3) 4.4 (1.7–11.4) 22 (27.5) 3.3 (1.4–8.1) CI indicates confidence interval. The cutoff points, which corresponded to the 90th percentiles of distribution among healthy controls, were 143.1% for APC levels and 1.22 for APC/PC ratios.

TABLE 3. Controls, Patients With Previous VTE-HyperHcy, and Patients With Previous VTE-NormoHcy

Plasma Levels of APC and APC/PC Ratios in Healthy Subjects nAPC,* %APC/PC Ratio† Healthy controls VTE-HyperHcy VTE-NormoHcy P (ANOVA) 98 48 80 116?20 128?29 121?33 0.03 0.99?0.19 1.15?0.33 1.10?0.31 0.002 Data are mean?SD. *VTE-HyperHcy versus VTE-NormoHcy (Dunnett’s test), P?NS; VTE- HyperHcy versus healthy controls, P?0.01; VTE-NormoHcy versus healthy controls, P?NS. †VTE-HyperHcy versus VTE-NormoHcy (Dunnett’s test), P?NS; VTE- yperHcy versus healthy controls, P?0.001; VTE-NormoHcy versus healthy controls, P?0.01. 1374

Activated Protein C, Thrombosis, and Homocysteine

Therefore, the results of our study suggest that Hcy does not negatively influence the plasma APC levels and argue against the hypothesis that

– it inhibits the activation of protein C in vivo by interfering with the activity of thrombomodulin.

Recently, Lentz et al,26in an experimental study of mon- keys with diet-induced moderate HyperHcy, showed that

– the thrombin-stimulated endothelium of aortas from hyperhomocysteinemic animals activated protein C in vitro less effectively than that of control animals.

This study, which supports the hypothesis that Hcy interferes with protein C activation, is in apparent contradiction with our results. At least two possible explanations for their different results can be proposed.

First, Hcy would not affect protein C activation that is ongoing in vivo under physiological conditions, whereas it would interfere with its activation at sites at which athero- genic or thrombogenic stimuli injured the endothelium and increased the local concentration of thrombin.
Second, due to the different relative densities of endothelial cell protein C receptor and thrombomodulin on the endothelium of large vessels and capillaries,1the regulation of protein C activation may differ in the two vascular districts. Although Lentz et al26 measured protein C activation by the endothelium of the aorta, we measured circulating APC, which mostly reflects protein C activation occurring in the microcirculation.

On the basis of the considerations above, we speculate that
– Hcy does not interfere with protein C activation ongoing in the micro- circulation under physiological conditions, whereas
– it could inhibit protein C activation on large, injured vessels.

In conclusion, our study shows that APC plasma levels are high in patients with previous episodes of VTE in whom the plasma levels of F1?2 are normal. Therefore, APC plasma levels represent a sensitive marker of activation of the hemostatic system. In addition, the study showed that high Hcy levels are not associated with heightened thrombin generation and do not interfere with the activation of protein C under physiological conditions in vivo. Further studies are needed to unravel the mechanism(s) by which HyperHcy increases the risks for atherosclerosis and thrombosis.

References

1. Esmon CT, Ding W, Yasuhiro K, Gu J-M, Ferrel G, Regan LM, Stearns- Kurosawa DJ, Kurosawa S, Mather T, Laszik Z, Esmon NL. The protein C pathway: new insights. Thromb Haemost. 1997;78:70–74.
2. Bauer KA, Kass BL, Beeler DL, Rosenberg RD. Detection of protein C activation in humans. J Clin Invest. 1984;74:2033–2041.
3. Heeb MJ, Mosher D, Griffin JH. Inhibition and complexation of activated protein C by two major inhibitors in plasma. Blood. 1989;73:446–454.
4. Gruber A, Griffin JH. Direct detection of activated protein C in blood from human subjects. Blood. 1992;79:2340–2348.
5. Espan ˜a F, Zuazu I, Vicente V, Estelle ´s A, Marco P, Aznar J. Quantifi- cation of circulating activated protein C in human plasma by immuno- assays: enzyme levels are proportional to total protein C levels. Thromb Haemost. 1996;75:56–61.
6. Cattaneo M. Hyperhomocysteinemia: a risk factor for arterial and venous thrombotic disease. Int J Clin Lab Res. 1997;27:139–144.
7. Harpel PC, Zhang X, Borth W. Homocysteine and hemostasis: patho- genetic mechanisms predisposing to thrombosis. J Nutr. 1996;126: 1285S–1289S.
8. Rodgers GM, Conn MT. Homocysteine, an atherogenic stimulus, reduces protein C activation by arterial and venous endothelial cells. Blood. 1990;75:895–901.
9. Lentz SR, Sadler JE. Inhibition of thrombomodulin surface expression and protein C activation by the thrombogenic agent homocysteine. J Clin Invest. 1991;88:1906–1914.
10. Hayashi T, Honda G, Suzuki K. An atherogenic stimulus homocysteine inhibits cofactor activity of thrombomodulin and enhances thrombo- modulin expression in human umbilical vein endothelial cells. Blood. 1992;79:2930–2936.
saee original manuscript for further referencesz  and for figures (not shown)

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Stabilizers that prevent Transthyretin-mediated Cardiomyocyte Amyloidotic Toxicity

December 2, 2013 by larryhbern

Stabilizers that prevent Transthyretin-mediated Cardiomyocyte Amyloidotic Toxicity

Reporter and curator: Larry H. Bernstein, MD, FCAP

http://pharmaceuticalintelligence.com/12-2-2013/larryhbern/Stabilizers that prevent transthyretin-mediated cardiomyocyte amyloidotic toxicity

Transthyretin is a small protein with a half-life of < 48 hours, synthesized by the liver, and a major transport protein for thyroxin.  There are 80 variants known, and some variants that occur in the Portuguese, a small section of Japan, Sweden, and Brazil, are associated will primary amyloidosis, the only cure for which is liver transplantation.  It causes fibrillary inclusions in the heart, but also affects the autonomic nervous system.  Some of the major work on this has been done for many years in the laboratory of   Jeffery W. Kelly, at the Skaggs Institute for Chemical Biology, the Scripps Research Institute.  A recent publication is of considerable interest.

Potent Kinetic Stabilizers that Prevent Transthyretin-mediated Cardiomyocyte Proteotoxicity

 Mamoun M. Alhamadsheh1,6,7, Stephen Connelly2,7, Ahryon Cho1, Natàlia Reixach3, Evan T. Powers3,4,5, Dorothy W. Pan1, Ian A. Wilson2,5, Jeffery W. Kelly3,4,5, and Isabella A. Graef1,*
Sci Transl Med. Author manuscript; available in PMC 2012 August 24.
1Department of Pathology, Stanford University Medical School, Stanford, California, USA
2Department of Molecular Biology, The Scripps Research Institute, La Jolla, California, USA
3Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California, USA
4Department of Chemistry, The Scripps Research Institute, La Jolla, California, USA
5The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California, USA
6Department of Pharmaceutics & Medicinal Chemistry, University of the Pacific, Stockton, California, USA

Abstract

The V122I mutation that alters the stability of transthyretin (TTR) affects 3–4% of African Americans and leads to amyloidogenesis and development of cardiomyopathy. In addition, 10–15% of individuals over the age of 65 develop senile systemic amyloidosis (SSA) and cardiac
TTR deposits due to wild-type TTR amyloidogenesis. As no approved therapies for TTR amyloid cardiomyopathy are available, the development of drugs that prevent amyloid-mediated cardiotoxicity is desired. To this aim, we developed a fluorescence polarization-based HTS screen,
which identified several new chemical scaffolds targeting TTR. These novel compounds were potent kinetic stabilizers of TTR and
  • prevented tetramer dissociation,
  • unfolding and aggregation of both wild type and the most common cardiomyopathy-associated TTR mutant, V122I-TTR.
High-resolution co-crystal structures and characterization of the binding energetics revealed how these diverse structures bound to tetrameric TTR. Our study also showed that these compounds effectively inhibited the proteotoxicity of V122I-TTR towards human cardiomyocytes.
Several of these ligands stabilized TTR in human serum more effectively than diflunisal, which is one of the best known inhibitors of TTR aggregation, and may be promising leads for the treatment and/or prevention of TTR-mediated cardiomyopathy.

Author Contributions:

M.M.A. designed and performed most experiments, S.C. performed crystallographic structure determination, A.C peformed the serum TTR stabilization. N.R. performed the cell-based assays.   E.T.P. analyzed the ITC data. D.W.P. helped with probe synthesis. I.A.W. supervised the crystallographic work. J.W.K. supervised the work, S.C., N.R., I.A.W. and J.W.K. edited the paper. I.A.G supervised the work, M.M.A. and I.A.G prepared the manuscript.

 INTRODUCTION

The misassembly of soluble proteins into toxic amyloid aggregates underlies a large number of human degenerative diseases (1–3). TTR is one of more than 30 human amyloidogenic proteins whose misassembly can cause
  • a variety of degenerative gain-of-toxic-function diseases.
TTR is a tetrameric protein (54 kDa), secreted from the liver into the blood where, using orthogonal sites,
  • it transports thyroxine (T4) and
  • holo-retinol binding protein (4).
However, 99% of the TTR T4 binding sites remain unoccupied in humans
  • owing to the presence of two other T4 transport proteins in blood (3).
Familial TTR amyloid diseases, which are associated with one of more than 80 mutations in the TTR gene, include
  • the systemic neuropathies (familial amyloid polyneuropathy [FAP]),
  • cardiomyopathies (familial amyloid cardiomyopathy [FAC]), and
  • central nervous system amyloidoses (CNSA) (5–8).
Cardiac amyloidosis is most commonly caused by
  • deposition of immunoglobulin light chains or
  • TTR in the cardiac interstitium and conducting system.
It is a chronic and progressive condition, which can lead to arrhythmias, biventricular heart failure, and death (8–10). Two types of TTR-associated amyloid cardiomyopathies are clinically important.
  1. Wild-type (WT) TTR aggregation underlies the development of senile systemic amyloidosis (SSA). Cardiac TTR deposits can be found in 10 to 15% of the population over the age of 65 at autopsy (10,11). Many of these patients are asymptomatic, but there is little doubt that SSA is an underdiagnosed disease.
  2. In addition, a number of TTR mutations, including V122I, lead to amyloidogenesis and familial amyloid cardiomyopathy (FAC) (12–15). Population studies show that the V122I mutation is found in 3–4% of African Americans (~1.3 million people) and contributes to the increased prevalence of heart failure among this population segment (14,15).

The mutant TTR allele behaves as an autosomal dominant allele with age-dependent penetrance and

  • the frequency of cardiac amyloidosis from TTR in African-American individuals above age 60 is four times that seen in Caucasian-Americans of comparable age.
All of the TTR mutations associated with familial amyloidosis decrease tetramer stability, and
  • some decrease the kinetic barrier for tetramer dissociation (3, 16).
  • The latter is important because tetramer dissociation is the rate-limiting step in the TTR amyloidogenesis cascade (3).

Kinetic stabilization of the native, tetrameric structure of TTR by

  • interallelic trans suppression (incorporation of mutant subunits that raise the dissociative transition state energy) prevents
    1. post-secretory dissociation and aggregation, as well as the related disease 
    2. familial amyloid polyneuropathy (FAP), by slowing TTR tetramer dissociation (17).
Occupancy of the TTR T4 binding sites with rationally designed small molecules is known to stabilize the native tetrameric state of TTR over the dissociative transition state,
  • raising the kinetic barrier,
  • imposing kinetic stabilization on the tetramer and
  • preventing amyloidogenesis (3, 16, 18).
Previous studies have focused on rational ligand design and as a result
  • most of the TTR stabilizers reported to date are halogenated biaryl analogues of T4,
  • many resembling non-steroidal anti-inflammatory drugs (NSAIDs).
Some of these compounds, such as the NSAID diflunisal, which is currently tested in clinical trials in FAP patients for its efficacy to ameliorate
  • peripheral neuropathy resulting from TTR deposition, (19) have anti-inflammatory activity (20, 21).
The pharmacological effects of NSAIDs are due to inhibition of cyclo-oxygenase (COX) enzymes (22). Inhibition of COX-1 can produce side effects such as
  • gastrointestinal irritation, leading to ulcers and bleeding (23).
Inhibition of COX-2 has been associated with an
  • increased risk of severe cardiovascular events, including heart failure,
  • particularly in patients with preexisting cardiorenal dysfunction (20, 21, 24, 25).
Therefore, heart and kidney impairment are exclusion criteria for participation of patients in the diflunisal clinical trials to treat TTR-mediated FAP (19). Genomic variations can
  • increase the sensitivity of individuals to adverse side effects of NSAIDs.
Serum concentrations of NSAIDs depend on CYP2C9 and/or CYP2C8 activity. CYP2C9 polymorphism might play a significant role in the profile of adverse side effects of NSAID and alleles that affect the activity of CYP2C9 are found at different frequency in subjects of Caucasian, African or Asian descent (26, 27). Hence, the long-term therapy with drugs that have inhibitory effect on COX activity to prevent TTR aggregation is especially problematic in patients who suffer from TTR-mediated cardiomyopathy. The design and development of drugs to treat/prevent FAC or SSA thus presents the challenge
  1. not only to find compounds with a greater variety of chemical scaffolds that accomplish stabilization, but
  2. do so without the adverse side effects due to inhibition of COX activity.
 For these reasons, the development of a rapid and robust screen for compounds that bind to and stabilize TTR could be useful. To date, no high-throughput screening (HTS) methodology is available for the discovery of TTR ligands (28,29). Therefore, we developed a versatile
  • fluorescence polarization (FP) based HTS assay that can detect
  • binding of small molecules to the T4 binding pocket of TTR under physiological conditions.

RESULTS

Design and synthesis of the TTR FP probe

FP is used to study molecular interactions by monitoring changes in the apparent size of a fluorescently labeled molecule. Binding is measured by an increase in the FP signal, which is proportional to the decrease in the rate of tumbling of a fluorescent ligand upon association with macromolecules such as proteins (Fig. 1A). To synthesize a fluorescent TTR ligand 1, we initially started with the NSAID diflunisal analogue 2 (Fig. 1B) (30). The product of attaching a linker to 2, compound 3, had very low binding affinity to TTR (Kd1 >3290 nM, fig. S1A and fig. S1B).
The crystal structure of the diclofenac analog 4 showed that
  • the phenolic hydroxyl flanked by the two chlorine atoms is oriented out of the binding pocket into the solvent (31).
  • We reasoned that attaching a PEG amine linker to the phenol group of 4 would generate compound 5 which would bind to TTR (Fig. 1B and fig. S1C)

5 was coupled to fluorescein isothiocyanate (FITC) to produce the FITC-coupled TTR FP probe (1, Fig. 1B). The binding characteristics of the probe (Kd1 = 13 nM and Kd2 = 100 nM) were assessed with ITC (Fig. 2A).

Evaluation of the FP assay

The binding of 1 to TTR was evaluated to test its suitability for the FP assay with a standard saturation binding experiment. A fixed concentration of probe 1 (0.1 μM) was incubated with increasing concentrations of TTR (0.005 μM to 10 μM) and the formation of 1•TTR complex was quantified by the increase in FP signal (excitation λ 485 nm, emission λ 525 nm) relative to the concentration of TTR (Fig. 2B). The fluorescence polarization increased with the concentration of TTR until saturation was reached. A large dynamic range (70 – 330 mP) was measured for the assay. To validate the FP assay, we tested known TTR binders in a displacement assay (for detailed information see Supplemental Material). Compound 2 (Kapp = 231 nM, R2 = 0.997), Thyroxine (T4) (Kapp = 186 nM, R2 = 0.998) and diclofenac (Kapp = 4660 nM, R2 = 0.999) decreased the FP signal in a dose- dependent  manner  (Fig. 2C,  fig. S2B and S2C). The FP assay is a competitive displacement assay and therefore it provides apparent binding constants (Kapp). However, these apparent binding constants correlate well with the data obtained by ITC which measures direct interactions in solution and gives an actual (Kd) value.

 Adaptation of the FP assay for HTS

Next, we optimized the FP assay for HTS and screened a ~130,000 small molecule library for compounds that displaced probe 1 from the T4 binding sites of TTR. The FP assay was performed in 384-well plates with low concentrations of probe 1 (1.5 nM) and TTR (50 nM) in a 10  μL assay volume.  Detergent (0.01% Triton X-100) was added to the assay buffer to avoid false positive hits from aggregation of the small molecules. The assay demonstrated robust performance, with a, large dynamic range (~70–230 mP) and a Z′ factor (32, 33) in the range of 0.57–0.78 (fig. S3A and S3B).

Hits were defined as compounds, which resulted in at least 50% decrease in FP and demonstrated relative fluorescence between 70 and 130%. Many fluorescence quenchers and enhancers, which have less than 70% and greater than 130% total fluorescence relative to a control (compound without TTR), were excluded from the hit list. The excluded compounds have native fluorescence that is similar to fluorescein, which would interfere with the FP measurements and result in false positive hits. Two hundred compounds were designated as positive hits (0.167% hit rate). The top 33 compounds (compounds with lowest FP IC50) were assayed in a 10-point duplicate dose-response FP assay and displayed an IC50 (concentration that resulted in 50% decrease in the FP signal) between 0.277 and 10.957 μM (table S2).

Validation of the HTS hits

The top 33 compounds were retested with the FP assay (table S2) and with surface plasmon resonance (SPR) as another independent biophysical method. Solutions of the 33 hits were passed over immobilized, biotinylated TTR on a streptavidin coated chip. The binding of a small molecule to TTR on the sensor chip produces a SPR response signal (RU). The RU signal after addition of the top 33 compounds was measured and compared to a negative, solvent only, control. All compounds identified by the screen as hits were confirmed as TTR binders using SPR (fig. S4). We also found known TTR binders, such as NSAIDs (diclofenac, meclofenamic acid, and niflumic acid) and isoflavones (apigenin) in our screen (3, 34) (table S2). Among the best ligands (Fig. 2D) were the NSAID, niflumic acid, two catechol-O-methyl-tranferase (COMT) inhibitors, 3,5-dintrocatechol and Ro 41-0960 (35) and a number  of compounds   not previously known to bind to TTR. The chemical structures of these ligands were confirmed by 1H NMR and high-resolution mass spectrometry(HRMS) and the chemical purity was determined to be >95% (fig. S5).

Inhibition of TTR amyloidogenesis by the HTS hits

To test whether the new TTR ligands (7.2 μM) could function as kinetic stabilizers, we measured their ability to inhibit TTR (3.6 μM) amyloidogenesis at 72 hrs at pH 4.4 (fig. S6) (29). All 33 compounds inhibited TTR aggregation (<50% fibril formation, table S2). Of these, 23 were very good (<20% fibril formation) and 11 were excellent (<2% fibril formation) TTR kinetic stabilizers (Fig. 3A). All of the potent TTR stabilizers, except niflumic acid, and the two COMT inhibitors 3,5-dintrocatechol and Ro 41-0960, were chemical entities with no previously reported biological activity. Since occupancy of only
one T4 binding site within TTR is sufficient for kinetic stabilization of the tetramer (3), we tested the most potent ligands at substoichiometric concentrations (2.4 fold molar excess of TTR relative to ligand) in a kinetic aggregation assay monitored over 5 days (Fig. 3B). Under these conditions ligands 7, 14, 15 and Ro 41-0960 dramatically slowed fibril formation and outperformed the known TTR stabilizer, diclofenac, which blocked only ~55% of TTR aggregation.

Evaluating the TTR ligands for COX-1 enzymatic inhibition and binding to thyroid hormone receptor

A successful clinical candidate against TTR amyloid cardiomyopathy should have minimal off-target toxicity due to the potential need for life-long use of these drugs. Specifically, the TTR ligands should exhibit minimal binding to COX and the nuclear thyroid hormone receptor (THR). Inhibition of COX is contraindicated for treating FAC patients, since COX inhibition can not only lead to renal dysfunction and blood pressure elevation, but may precipitate heart failure in vulnerable individuals (20, 21, 24, 25). Therefore, the most potent TTR ligands were evaluated for their ability to inhibit COX-1 activity, as well as, for binding to THR, in comparison with the NSAID niflumic acid. Although niflumic acid exhibited substantial (94%) COX-1 inhibition, three of the 12 new compounds evaluated (7, 6 and 10) displayed less than 1% inhibition of COX-1. Only one ligand (compound 8) showed significant (58%) and two compounds (6 and 10) minor (5%) binding to THR (Fig. 3C).

Characterization of the binding energetics to TTR

Many reported TTR ligands, including T4, bind TTR with negative cooperativity, which appears to arise from subtle conformational changes in TTR upon ligand binding to the first T4 site (3, 16, 36). We used ITC to determine the binding constants and to evaluate cooperativity between the two TTR T4 sites (Fig. 2A, Fig. 4A, Fig. 4B and fig. S1 and fig. S7). The ITC data for compounds 1, 7, 14, and Ro 41-0906 binding to TTR were fit to a two-site binding model and show that these potent ligands bind TTR with low nanomolar affinity. The dissociation constants for these ligands indicated that they bound TTR with negative cooperativity (table S3). Analysis of the free energies associated with ligand binding to TTR indicates that binding was driven both by burial of the hydrophobic ligand in the TTR binding site (which leads to the favorable binding entropies) and specific ligand-TTR interactions (which leads to the favorable binding enthalpies) (Fig. 2A, Fig. 4A, Fig.4B, and fig. S7B) (37). The binding of compounds 7 (Kd1 = 58 nM and Kd2 = 500 nM) and 14 (Kd1 = 26 nM and Kd2 = 1800 nM) to TTR did not cause major conformational changes to the TTR tetramer structure (Fig. 5).
Remainder of document is found at publication site, including Figures.
SOURCE

Posted in Cardiomyopathy, Cerebrovascular and Neurodegenerative Diseases, Chemical Biology and its relations to Metabolic Disease, Disease Biology, Small Molecules in Development of Therapeutic Drugs, Frontiers in Cardiology and Cardiovascular Disorders, Human Immune System in Health and in Disease, Liver & Digestive Diseases Research, Metabolomics, Personalized and Precision Medicine & Genomic Research, Population Health Management, Genetics & Pharmaceutical, Proteomics, Regulated Clinical Trials: Design, Methods, Components and IRB related issues, Technology Transfer: Biotech and Pharmaceutical, Translational Effectiveness, Translational Science | Tagged , , , , , , , , , | Leave a Comment »

“R145C” variant of the ApoE gene is found in People of African Descent, linked to Increased Levels of Triglycerides, Obesity, Diabetes, Stroke and Cardiovascular Diseases

December 2, 2013 by 2012pharmaceutical

“R145C” variant of the ApoE gene is found in People of African Descent, linked to Increased Levels of Triglycerides, Obesity, Diabetes, Stroke and Cardiovascular Diseases

Reporter: Aviva Lev-Ari, PhD, RN

Gene Mutation May Explain Heart Disease Risk Among African-Americans

December 2, 2013

 

MONDAY, Dec. 2, 2013 (HealthDay News) — A genetic mutation associated with an increased risk of heart disease, type 2 diabetes and other health problems is common in Africans and people of African descent worldwide, according to a new study.

The findings may help explain why Africans and people of African descent are more likely to develop heart disease and diabetes than many other racial groups, the Weill Cornell Medical College researchers said.

The mutation in the ApoE gene is linked to increased levels of triglycerides, which are fats in the blood associated with conditions such as obesity, diabetes, stroke and heart disease.

The researchers’ analysis of worldwide data revealed that the “R145C” variant of the ApoE gene is found in 5 percent to 12 percent of Africans and people of African descent, especially those from sub-Saharan Africa. The variant is rare in people who are not African or of African descent.

“Based on our findings, we estimate that there could be 1.7 million African-Americans in the United States and 36 million sub-Saharan Africans worldwide with the variant,” study senior author Dr. Ronald Crystal, chairman of genetic medicine at Weill Cornell, said in a college news release.

On average, African-Americans with the mutation had 52 percent higher triglyceride levels than those without the variant, according to the study, which was published online Nov. 18 in the American Journal of Cardiology.

“The prevalence of the ApoE mutation may put large numbers of Africans and African descendants worldwide at risk for a triglyceride-linked disorder,” Crystal said. “But we don’t yet know the extent of that risk or its health consequences.”

“Inheriting this genetic variant does not mean a person is going to get heart disease and other diseases,” he said. “It increases their risk, and screening for fats in the blood — both cholesterol and triglycerides — as well as maintaining a healthy lifestyle is important.”

“There are many factors at work in these diseases,” Crystal said. “This may be one player.”

More information

The American Heart Association has more about black Americans and heart disease and stroke.

SOURCE

http://news.health.com/2013/12/02/gene-mutation-may-explain-heart-disease-risk-among-african-americans/

Other related articles published on this Open Access Online Scientific Journal include the following:

Cardiology, Genomics and Individualized Heart Care: Framingham Heart Study (65 y-o study) & Jackson Heart Study (15 y-o study)

http://pharmaceuticalintelligence.com/2013/12/01/cardiology-genomics-and-individualized-heart-care-framingham-heart-study-65-y-o-study-jackson-heart-study-15-y-o-study/

Cholesteryl Ester Transfer Protein (CETP) Inhibitor: Potential of Anacetrapib to treat Atherosclerosis and CAD

http://pharmaceuticalintelligence.com/2013/04/07/cholesteryl-ester-transfer-protein-cetp-inhibitor-potential-of-anacetrapib-to-treat-atherosclerosis-and-cad/

Two Mutations, in the PCSK9 Gene: Eliminates a Protein involved in Controlling LDL Cholesterol

http://pharmaceuticalintelligence.com/2013/04/15/two-mutations-in-a-pcsk9-gene-eliminates-a-protein-involve-in-controlling-ldl-cholesterol/

Artherogenesis: Predictor of CVD – the Smaller and Denser LDL Particles

http://pharmaceuticalintelligence.com/2012/11/15/artherogenesis-predictor-of-cvd-the-smaller-and-denser-ldl-particles/

Synthetic Biology: On Advanced Genome Interpretation for Gene Variants and Pathways: What is the Genetic Base of Atherosclerosis and Loss of Arterial Elasticity with Aging

http://pharmaceuticalintelligence.com/2013/05/17/synthetic-biology-on-advanced-genome-interpretation-for-gene-variants-and-pathways-what-is-the-genetic-base-of-atherosclerosis-and-loss-of-arterial-elasticity-with-aging/

Posted in Atherogenic Processes & Pathology, Cardiovascular Research, Frontiers in Cardiology and Cardiovascular Disorders, HTN, Myocardial metabolism, Myocardial ischemia, myocardial perfusion, Myocardial adenine nucleotide metabolism, Origins of Cardiovascular Disease, Pharmacotherapy of Cardiovascular Disease | Tagged , , , , | Leave a Comment »

Brown Fat Stem Cells for Treating Diabetes and Obesity

December 2, 2013 by larryhbern

Posted in Uncategorized | Leave a Comment »

PAD and Resistance Hypertension: Renal Artery Intervention using Stenting

December 2, 2013 by 2012pharmaceutical

Resistance Hypertension: Renal Artery Intervention using Stenting

Reporter: Aviva Lev-Ari, PhD, RN

UPDATED 2/4/2014

Stenting and Medical Therapy for Atherosclerotic Renal-Artery Stenosis

Christopher J. Cooper, M.D., Timothy P. Murphy, M.D., Donald E. Cutlip, M.D., Kenneth Jamerson, M.D., William Henrich, M.D., Diane M. Reid, M.D., David J. Cohen, M.D., Alan H. Matsumoto, M.D., Michael Steffes, M.D., Michael R. Jaff, D.O., Martin R. Prince, M.D., Ph.D., Eldrin F. Lewis, M.D., Katherine R. Tuttle, M.D., Joseph I. Shapiro, M.D., M.P.H., John H. Rundback, M.D., Joseph M. Massaro, Ph.D., Ralph B. D’Agostino, Sr., Ph.D., and Lance D. Dworkin, M.D. for the CORAL Investigators

N Engl J Med 2014; 370:13-22 January 2, 2014DOI: 10.1056/NEJMoa1310753

BACKGROUND

Atherosclerotic renal-artery stenosis is a common problem in the elderly. Despite two randomized trials that did not show a benefit of renal-artery stenting with respect to kidney function, the usefulness of stenting for the prevention of major adverse renal and cardiovascular events is uncertain.

METHODS

We randomly assigned 947 participants who had atherosclerotic renal-artery stenosis and either systolic hypertension while taking two or more antihypertensive drugs or chronic kidney disease to medical therapy plus renal-artery stenting or medical therapy alone. Participants were followed for the occurrence of adverse cardiovascular and renal events (a composite end point of death from cardiovascular or renal causes, myocardial infarction, stroke, hospitalization for congestive heart failure, progressive renal insufficiency, or the need for renal-replacement therapy).

RESULTS

Over a median follow-up period of 43 months (interquartile range, 31 to 55), the rate of the primary composite end point did not differ significantly between participants who underwent stenting in addition to receiving medical therapy and those who received medical therapy alone (35.1% and 35.8%, respectively; hazard ratio with stenting, 0.94; 95% confidence interval [CI], 0.76 to 1.17; P=0.58). There were also no significant differences between the treatment groups in the rates of the individual components of the primary end point or in all-cause mortality. During follow-up, there was a consistent modest difference in systolic blood pressure favoring the stent group (−2.3 mm Hg; 95% CI, −4.4 to −0.2; P=0.03).

CONCLUSIONS

Renal-artery stenting did not confer a significant benefit with respect to the prevention of clinical events when added to comprehensive, multifactorial medical therapy in people with atherosclerotic renal-artery stenosis and hypertension or chronic kidney disease. (Funded by the National Heart, Lung and Blood Institute and others; ClinicalTrials.gov number, NCT00081731.)

SOURCE

http://www.nejm.org/doi/full/10.1056/NEJMoa1310753

based on

What Do CORAL and ERASE Mean for Peripheral Intervention?

Seth Bilazarian, MD, Mark A. Creager, MD

November 27, 2013

Seth Bilazarian, MD: Hi. I’m Seth Bilazarian from the heart.org on Medscape. I’m here at the American Heart Association Scientific Sessions in Dallas with Dr. Mark Creager, Director of Vascular Medicine at Brigham and Women’s Hospital in Boston. Dr. Creager was the moderator of a session enriched with peripheral vascular disease topics yesterday. And I’m fortunate to be with him to unpack 2 of those studies: the ERASE study,[1] a study of peripheral artery disease in the lower extremities and exercise; and the CORAL study,[2] a study of renal artery intervention using stenting.

As a practicing endovascular medicine physician, I’m excited to get Dr. Creager’s take on this. The CORAL study, to start with, was a study that was sponsored by the NHLBI (National Heart, Lung, and Blood Institute), -looking at patients who had greater than 60% stenosis who had resistant hypertension or renal insufficiency and were optimally treated with medical therapy. The patients were given free antihypertensive therapies and statin therapy. And that alone was compared with medical therapy plus renal artery intervention with stenting.

Dr. Creager, can you summarize the take-home message and the results for our audience?

Mark A. Creager, MD: Thank you, Seth. This was an important study. The CORAL study compared these 2 groups, and the primary endpoints were cardiovascular and renal death, hospitalization for congestive heart failure, stroke, myocardial infarction, progressive renal insufficiency, and renal replacement therapy. The trial found that there was no significant difference in this primary composite endpoint between the 2 groups.

That’s an important message: that if we treat our patients with hypertension and renal insufficiency who have concomitant renal artery stenosis with appropriate medical therapy, they will do as well — in terms of cardiovascular and renal endpoints — as those who undergo renal artery stenting.

Dr. Bilazarian: A very strong message that stenting adds nothing, if we take home the short answer that renal stenting adds nothing on top of optimal medical therapy. Previously, enthusiasts for renal stenting criticized studies such as ASTRAL[3] and STAR[4] that the patients may not have been optimally chosen and may not have had significant enough renal artery stenosis.

In the CORAL study, we saw yesterday that in a subgroup analysis looking at patients who had greater or less than 80% stenosis, the average was 72% in the whole trial. But those at greater than 80% did not seem to fare any better from this study. They were the same as those at less than 80%. So does this largely close the door to renal stenting for atherosclerotic disease?

Dr. Creager: As implied by your question, one might have anticipated that those individuals with the most severe renal artery stenosis would have been those most likely to benefit. But as you stated, there was no difference between the patients who had a greater than 80% stenosis and those who did not. That really continues to raise questions about the efficacy of renal artery stenting in this population in general.

But it doesn’t entirely close the door. I think it still is very important for all physicians to deal with their patients individually and inform their decisions by the evidence that’s available. But there will be patients who have hypertension and remain refractory despite aggressive and appropriate medical therapy. And in those individuals, one might consider looking for the presence of renal artery stenosis, and if found, treat them.

But keep in mind that in this trial, the group randomized to medical therapy did demonstrate benefit. In fact, they demonstrated a 15-mm Hg (on average) decrease in systolic blood pressure, indicating that before enrollment in the trial they probably were being treated as aggressively as they should be.

My take-home message is: If you have a patient with significant hypertension, make sure you’re implementing guideline-based therapies to bring their blood pressure into appropriate control. And if one is not successful in that case, then consider other options.

Dr. Bilazarian: One of the findings in the study was that at the end of the trial, there was a 2.5-mm Hg blood pressure difference between those with renal stenting and those without renal stenting (both on optimal medical therapy). Did that result surprise you?

Dr. Creager: It did surprise me for the very reason I just alluded to. I think that prior to enrollment in the trial, many of these patients who were treated with 2 or more antihypertensive drugs still might not have been treated aggressively enough with the right doses of these drugs or the right number of drugs to bring their blood pressure down.

In fact, I was pleased to see that an intensive medical regimen could be effective in these patients. And it sends another important message to our medical community that we can do more for these patients.

Dr. Bilazarian: You mentioned in this last answer that there may still be a role for identifying patients with renal artery stenosis. Can you help clarify that for me as a director of the vascular lab at Brigham and Women’s Hospital? As a teacher of postgraduate physicians, help me understand in what situation patients should be evaluated.

Currently, patients who may not have frank resistant hypertension get referrals to duplex ultrasound for assessment. Should that bar be moved up? Or is it only the most refractory patients who should be investigated? Or is it still valuable to know whether a patient has renal artery stenosis with noninvasive testing?

Dr. Creager: The bar does need to be moved without question. But there are several situations. I’ll give you 2 examples. One I mentioned: The patient who continues to have resistant hypertension despite aggressive medical therapy will be one such patient where I’ll be looking for secondary causes. And one of those secondary causes could be renal artery stenosis. So in that individual, duplex ultrasound would be appropriate, and if renal artery stenosis is found, continue the evaluation and treat that patient as the renal artery stenosis is confirmed.

Another example might be an individual who has recurrent acute pulmonary edema that cannot be explained by coronary artery disease or severe left ventricular dysfunction. That’s a patient I would consider working up for bilateral renal artery stenosis. And if found, I would treat. That patient population was really not the type that was included in the CORAL trial. So those are 2 examples.

Dr. Bilazarian: Our current guidelines say that there is a role for renal artery intervention for resistant hypertension, acute pulmonary edema, and declining renal function. It seems like the first of those has been taken off the table. Is there a role in the patient with declining renal function?

Dr. Creager: Well, that’s an important subset of patients, indeed. And I would be evaluating them for the potential causes of declining renal function. If they have renal artery stenosis, I would then initiate aggressive risk factor modification, antiplatelet therapy, and if they’re hypertensive, treat that as well.

But if in spite of that there still is evidence of declining renal function, then there’s a situation of someone who has failed medical therapy, and I would consider evaluating them for a renal artery stenosis. If one were to find, for example, bilateral renal artery stenosis in that patient or a severe stenosis to a single functioning kidney, then, yes, I would consider renal artery stenting in that individual.

Dr. Bilazarian: Great. Thank you for that summary on the trial called CORAL. Let’s move on to the second trial that you moderated. That trial is called ERASE, a study looking at supervised exercise therapy — an abbreviation I wasn’t familiar with: SET — supervised exercise therapy alone or supervised exercise therapy plus intervention of lower-extremity peripheral arterial disease. And that study was called ERASE. It built on an earlier study called CLEVER.[5] Please summarize the take-home message for the audience in that trial.

Dr. Creager: These were patients with peripheral artery disease and intermittent claudication, and the peripheral artery disease could have affected the aortoiliac system or the femoropopliteal system. The bottom line is that those patients who were randomized to both endovascular intervention and supervised exercise training had a much greater improvement in their walking time as assessed by treadmill testing, and also in quality of life as assessed by a number of instruments, compared with those patients who were just treated with supervised exercise training.

It adds incrementally to what we’ve previously understood. We know that supervised exercise training is extremely effective in improving walking time in patients with intermittent claudication. And as was shown with CLEVER, compared with medical therapy, endovascular intervention — at least in the aortoiliac area — is also associated with improvement in walking time.

So perhaps it’s no surprise that if you put the two together, they’re going to do better. And that’s what the ERASE trial showed.

Dr. Bilazarian: I agree with you. Many times, studies compare one or the other. And, of course, both is better than one or the other. I was happy to see that this trial looked at both.

There is one part of the trial that I had difficulty getting a take-home message from, and I’d love your input. As endovascular medicine physicians, we think in terms of the 3 zones of lower-extremity vascular disease: above the inguinal ligament, the fem-pop system, and then below the knee. Each becomes increasingly difficult, both for acute result as well as for durability. In this trial, half the patients had aortoiliac disease and half had fem-pop disease. Am I right to say that that might make it somewhat difficult to interpret whether the effects of supervised exercise therapy might be different for fem-pop disease or, say, aortoiliac disease, and that the bar for intervention might be lower for aortoiliac disease?

Dr. Creager: That’s a very important question. We don’t know yet what the subset analysis will be between those patients who had aortoiliac disease and underwent randomization and those who had femoropopliteal artery disease. And I’m sure we all await that analysis when it’s available.

Having said that, however, the studies show several things. It underscores the fact that no matter where the lesion is, patients still do better when exercise training is included in their therapeutic interventions. I think those of us who practice vascular medicine recognize the fact that endovascular intervention in the iliac arteries has been extremely successful and durable. And those patients really do benefit. d Our practice pattern and standard of care is to do endovascular intervention in patients with disabling claudication who have aortoiliac disease.

Superficial femoral artery disease, as you implied, is a little bit of a different situation. Those lesions are sometimes more difficult to treat and the durability is not as great. Within the context of this study, durability was pretty good in terms of restenosis. But I still think we need to see the subset analysis to make sure that those patients benefited as much as the entire group.

Dr. Bilazarian: Help us with a take-home message for US-based physicians. This was supervised exercise therapy in-home. We don’t have that available in the United States. Other than adding to our knowledge base, which is, of course, valuable, and being able to impart this knowledge to our patients and show them that this is of value, what other things can we do as a change in our practice to integrate this?

Dr. Creager: Currently we do need changes in healthcare policy, at least as it applies to supervised exercise training. We need reimbursement from CMS (Centers for Medicare & Medicaid Services). We need reimbursement from other third-party payers to provide additional incentive for physicians to recommend supervised exercise training for their patients. Unfortunately, that’s not available. And that’s one reason why patients in this country are not being referred for supervised exercise training. It’s an extremely effective intervention in patients with intermittent claudication.

Dr. Bilazarian: Great. Mark, thanks for joining me and for helping unpack these 2 trials for our audience: the ERASE trial of lower-extremity exercise in PAD patients, and the CORAL trial of renal artery stenting. I think they will add to our knowledge base and hopefully make practice changes in both areas. Thank you again for joining. And thank you for joining us for this program.

SOURCE

http://www.medscape.com/viewarticle/815029?src=emailthis#1

Posted in Cardiac and Cardiovascular Surgical Procedures, Frontiers in Cardiology and Cardiovascular Disorders, HTN, Nephrology, Origins of Cardiovascular Disease, Peripheral Arterial Disease & Peripheral Vascular Surgery, Pharmacotherapy of Cardiovascular Disease, Stents & Tools | Tagged , , , , , | Leave a Comment »

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