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Cholesterol-lowering drugs and the risk of hemorrhagic stroke

Contact: Angela Babb
ababb@aan.com
651-695-2789
American Academy of Neurology

ST. PAUL, Minn. – People taking cholesterol-lowering drugs such as atorvastatin after a stroke may be at an increased risk of hemorrhagic stroke, or bleeding in the brain, a risk not found in patients taking statins who have never had a stroke. But researchers caution the risk must be balanced against the much larger overall benefit of the statin in reducing the total risk of a second stroke and other cardiovascular events when making treatment decisions. The research is published in the December 12, 2007, online issue of Neurology®, the medical journal of the American Academy of Neurology.

For the study, researchers conducted a secondary analysis of the results of the Stroke Prevention with Aggressive Reduction in Cholesterol Levels (SPARCL) clinical trial. The trial enrolled 4,731 people who were within one to six months of having had a stroke or transient ischemic attack, or mini-stroke, and with no history of heart disease. Half of the participants received atorvastatin and half received a placebo. The participants were then followed for an average of four and a half years.

Overall, treatment was associated with a 16-percent reduction in total stroke, the study’s primary endpoint, as well as significant reductions in coronary heart events. However, secondary analysis found that the overall reduction in stroke included an increase in the risk of brain hemorrhage. Of those people randomized to atorvastatin, the study found 2.3 percent experienced a hemorrhagic stroke during the study compared to 1.4 percent of those taking placebo. The study also found there was a 21-percent reduction in ischemic stroke, a more common type of stroke involving a block in the blood supply to the brain, among people taking atorvastatin.

Other factors were also found to increase the risk of brain hemorrhage. For example, those who had experienced a hemorrhagic stroke prior to the study were more than five times as likely to suffer a second stroke of this kind. Men were also nearly twice as likely as women to suffer a hemorrhagic stroke. People with severe high blood pressure at their last doctor’s visit prior to the hemorrhagic stroke had over six times the risk of those with normal blood pressure.

“Although treatment of patients with a stroke or transient ischemic attack was clearly associated with an overall reduction in a second stroke, hemorrhagic stroke was more frequent in people treated with atorvastatin, in those with a prior hemorrhagic stroke, in men and in those with uncontrolled hypertension,” according to study author Larry B. Goldstein, MD, with Duke University Medical Center in Durham, North Carolina, and Fellow of the American Academy of Neurology. “This risk of hemorrhagic stroke also increased with age.”

“Treatment with atorvastatin did not disproportionately increase the frequency of brain hemorrhage associated with these other factors. The risk of hemorrhage in patients who have had a transient ischemic attack or stroke must be balanced against the benefits of cholesterol-lowering drugs in reducing the overall risk of a second stroke, as well as other cardiovascular events,” said Goldstein.

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The SPARCL trial was funded by Pfizer, the maker of atorvastatin.

The American Academy of Neurology, an association of more than 20,000 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as stroke, Alzheimer’s disease, epilepsy, Parkinson disease, and multiple sclerosis.

For more information about the American Academy of Neurology, visit http://www.aan.com.

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December 13, 2007 Posted by | American Academy of Neurology, Baltimore, Barcelona, Bethesda, Boston, Calgary, Canada, FMS Global News, France, Germany, Global, Global Health Vision, Global News, Hemorrhagic Stroke, Italy, London, London UK Feed, Medical Journals, Newfoundland, News, News Australia, News Canada, News France, News Germany, News Israel, News Italy, News Jerusalem, News Switzerland, News UK, News US, News USA, Nova Scotia, Ottawa, Ottawa City Feed, Quebec, Research, RSS Feed, Slovakia, Spain, Statin Drugs, Stroke, Toronto, Toronto City Feed, UK, US, Virginia, Washington DC, Washington DC City Feed, World News | , , | Leave a comment

A pioneering study opens roads for tailor-made antidepressants

In spite that the causes of depression have not still been fully identified, scientists acknowledge that genetic and environmental factors play a common role in the onset of this disorder. One of the environmental risk factors more often related to depression is exposure to threatening life events. On the other side, from a genetic point of view, the serotonin transporter gene, with a crucial role in communication between neurons, could predispose to depression.

An international group of scientists, headed by professors Jorge Cervilla Ballesteros and Blanca Gutiérrez Martínez, from the department of Legal Medicine, Toxicology and Psychiatry of the University of Granada, has recently published in the prestigious journal Molecular Psychiatry the pioneering study PREDICT-gene, confirming the relation between allele s in the serotonin transporter gene and exposure to threatening life events in the onset of depression. The study proves, for a population sample accounting for gender, age and family history of psychiatric disorders, that 24% of the Spanish population, comprising people with the s/s genotype, need minimal exposure to threatening life events, unlike individuals with s/l or l/l genotypes, thus confirming the relation between genetic and environmental factors in this mental disorder.

Tailor-made antidepressants

The most important consequence of research on interaction between genetic and environmental factors is that, in a foreseeable future, scientists will be able to produce measures to predict response to antidepressants taking into account each individual’s genotype, i. e. they will be able to design tailor-made drugs according to each person’s genetic configuration and their exposure to environmental factors.

The research group headed by professor Cervilla Ballesteros and Gutiérrez Martínez is currently working at the University of Granada to open roads for psycho-pharmaco-genetics, a field that will allow for individual treatments, tailor-made drugs, for each patient with depression, a disorder affecting one in every five Spaniards visiting the doctor’s.

This study is framed in the international project PREDICT and is funded by the European Union and the Spanish Ministry of Education and Science. One of its most important novelties is that it has been carried out through a very representative sample: a total of 737 people agreed to participate in the genetic tests, with ages ranging from 18 to 75, patients of nine primary care centres in the South of Spain. That is why this is the first representative population-based replication of earlier research, as until now research had been done into restricted population samples, comprising only women, adolescents, twins or people with affective disorders.

Contact: Professor Jorge Cervilla Ballesteros
jacb@ugr.es
34-663-075-835
Universidad de Granada

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August 6, 2007 Posted by | Alberta, Baltimore, Barcelona, Bethesda, Biological Sciences, Calgary, Canada, Depression, France, General Psychiatry, Germany, Global, Global Health Vision, Global News, Health Canada, Music Video Pick Of The Day, Newfoundland, News, News Australia, News Canada, News Israel, News Italy, News Jerusalem, News Switzerland, News UK, News US, News USA, Nova Scotia, Osaka, Ottawa, Prince Edward Island, Public Health, Quebec, RSS, RSS Feed, Spain, Toronto, UK, US, Virginia, Washington DC, Washington DC City Feed, World News | Leave a comment

European heat waves double in length since 1880

The most accurate measures of European daily temperatures ever indicate that the length of heat waves on the continent has doubled and the frequency of extremely hot days has nearly tripled in the past century. The new data shows that many previous assessments of daily summer temperature change underestimated heat wave events in western Europe by approximately 30 percent.

Paul Della-Marta and a team of researchers at the University of Bern in Switzerland compiled evidence from 54 high-quality recording locations from Sweden to Croatia and report that heat waves last an average of 3 days now—with some lasting up to 4.5 days—compared to an average of around 1.5 days in 1880. The results are published 3 August in the Journal of Geophysical Research-Atmospheres, a publication of the American Geophysical Union. The researchers suggest that their conclusions contribute to growing evidence that western Europe’s climate has become more extreme and confirm a previously hypothesized increase in the variance of daily summer temperatures since the 19th century.

The study adds evidence that heat waves, such as the devastating 2003 event in western Europe, are a likely sign of global warming; one that perhaps began as early as the 1950s, when their study showed some of the highest trends in summer mean temperature and summer temperature variance.

“These results add more evidence to the belief among climate scientists that western Europe will experience some of the highest environmental and social impacts of climate change and continue to experience devastating hot summers like the summer of 2003 more frequently in the future,” Della-Marta said.

The authors note that temperature records were likely overestimated in the past, when thermometers were not kept in modern Stevenson screens, which are instrument shelters used to protect temperature sensors from outside influences that could alter its readings. The researchers corrected for this warm bias and other biases in the variability of daily summer temperatures and show that nearly 40 percent of the changes in the frequency of hot days are likely to be caused by increases in summer temperatures’ variability. This finding demonstrates that even a small change in the variance of daily summer temperatures can radically enhance the number of extremely hot days.

“These findings provide observational support to climate modeling studies showing that European summer temperatures are particularly sensitive to global warming,” Della-Marta said. “Due to complex reactions between the summer atmosphere and the land, the variability of summer temperatures is expected to [continue to] increase substantially by 2100.”

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The research was supported by the European Environment and Sustainable Development Program, the Swiss National Science Foundation and the National Center for Excellence in Climate Research (NCCR Climate).

Contact: Jonathan Lifland
jlifland@agu.org
202-777-7535
American Geophysical Union

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August 3, 2007 Posted by | Alberta, Baltimore, Barcelona, Bethesda, Calgary, Canada, France, Germany, Global, Global Health Vision, Global News, Health Canada, Irvine, Italy, Japan, Medical Journals, Newfoundland, News, News Australia, News Canada, News Israel, News Italy, News Jerusalem, News Switzerland, News UK, News US, News USA, Nova Scotia, Osaka, Ottawa, Pennsylvania, Prince Edward Island, Quebec, RSS, RSS Feed, Slovakia, Spain, Toronto, UK, University of Bern, US, Virginia, Washington DC, Washington DC City Feed | Leave a comment

Identifying the mechanism behind a genetic susceptibility to type 2 diabetes

Type 2 diabetes is reaching epidemic proportions in the developed world. Determining if and how certain genes predispose individuals to type 2 diabetes is likely to lead to the development of new treatment strategies for individuals with the disease.

In a study appearing in the August issue of the Journal of Clinical Investigation Valeriya Lyssenko and colleagues from Lund University in Sweden show that certain variants of the gene TCF7L2 make individuals more susceptible to type 2 diabetes. The susceptibility variants were associated with increased expression of TCF7L2 in pancreatic islet cells and decreased islet cell secretion of insulin. Consistent with this, ectopic overexpression of TCF7L2 in human islet cells decreased insulin secretion in response to exposure to glucose. This study identifies TCF7L2 type 2 diabetes susceptibility variants and provides a mechanism by which these genetic variants might cause susceptibility to the disease. As discussed by the authors and in the accompanying commentary by Andrew Hattersley from Peninsula Medical School in the United Kingdom, future studies are likely to investigate the potential for manipulating the signaling pathways controlled by TCF7L2 for the development of new therapeutics for type 2 diabetes.

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TITLE: Mechanisms by which common variants in the TCF7L2 gene increase risk of type 2 diabetes

AUTHOR CONTACT:
Valeriya Lyssenko
Lund University, University Hospital Malma, Malma, Sweden.
Phone: 46-40-391214; Fax: 46-40-391222; E-mail: Valeri.Lyssenko@med.lu.se.

View the PDF of this article at: https://www.the-jci.org/article.php?id=30706

ACCOMPANYING COMMENTARY
TITLE: Prime suspect: the TCF7L2 gene and type 2 diabetes risk

AUTHOR CONTACT:
Andrew T. Hattersley
Institute of Biomedical and Clinical Sciences, Peninsula Medical School, Exeter, United Kingdom.
Phone: 44-1392-406806; Fax: 44-1392-406767; E-mail: Andrew.Hattersley@pms.ac.uk.

View the PDF of this article at: https://www.the-jci.org/article.php?id=33077

Contact: Karen Honey
press_releases@the-jci.org
215-573-1850
Journal of Clinical Investigation

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August 2, 2007 Posted by | Alberta, Baltimore, Barcelona, Bethesda, Biological Sciences, Calgary, Canada, Diabetes, France, Genes, Genetic, Genetic Link, Genetics, Genome, Genomic, Germany, Global, Global Health Vision, Global News, Health Canada, Human Genome, Irvine, Italy, Japan, Journal of Clinical Investigation, Medical Journals, Newfoundland, News, News Australia, News Canada, News Israel, News Italy, News Jerusalem, News Switzerland, News UK, News US, News USA, Nova Scotia, Nunavut, Osaka, Ottawa, Pennsylvania, Prince Edward Island, Public Health, Quebec, Research, RSS, RSS Feed, Slovakia, Spain, Toronto, Type 2 Diabetes, US, Virginia, Washington DC, Washington DC City Feed, World News | Leave a comment

U-M researchers find family of ‘on switches’ that cause prostate cancer

Gene fusions trigger cancer growth, could impact treatment choices

ANN ARBOR, Mich. — Researchers at the University of Michigan Comprehensive Cancer Center have discovered how genes turn on the switch that leads to prostate cancer.

The team discovered that pieces of two chromosomes can trade places with each other and cause two genes to fuse together. The fused genes then override the “off” switch that keeps cells from growing uncontrollably, causing prostate cancer to develop.

By testing these gene fusions in mice and in cell cultures, the researchers showed that the fusions are what cause prostate cancer to develop. But it’s not just one set of genes that fuse. The researchers found that any one of several in a family of genes can become scrambled and fuse. Results of the study appear in the Aug. 2 issue of Nature.

“Each of these switches, or gene fusions, represent different molecular subtypes. This tells us there’s not just one type of prostate cancer. It’s a more complex disease and potentially needs to be treated differently in each patient,” says lead study author Arul Chinnaiyan, M.D., Ph.D., director of the Michigan Center for Translational Pathology, a new U-M center whose goal is to translate research into real world practice.

The gene fusion research is the centerpiece project of the new center. In the current study, researchers found one of several abnormal gene fusions in the prostate cancer tissue samples they tested. In 2005, the researchers identified a prostate-specific gene called TMPRSS2, which fuses with either ERG or ETV1, two genes known to be involved in several types of cancer.

The Nature paper reports on five additional genes that fuse with ERG or ETV1 to cause prostate cancer. Gene fusions were involved in 60 percent to 70 percent of the prostate cancer cell lines the researchers looked at. The genes involved are all controlled by a different mechanism. For example, four of the genes are regulated by androgen, a male sex hormone known to fuel prostate cancer. Androgen deprivation is a common therapy for prostate cancer.

Knowing which gene fusion is involved in an individual patient’s tumor could impact treatment options. If an androgen-regulated gene is involved, androgen therapy would be appropriate. But if the gene fusion involves a gene that represses androgen, the anti-androgen therapy could encourage the cancer’s growth. This may also explain why androgen treatment is not effective for some prostate cancers.

“Typing someone’s prostate cancer by gene fusion can affect the treatment given. We would not want to give androgen to someone whose prostate cancer gene fusion is not regulated by androgen,” says Chinnaiyan, who is the S.P. Hicks Collegiate Professor of Pathology at the U-M Medical School.

Rearrangements in chromosomes and fused genes are known to play a role in blood cell cancers like leukemia and lymphoma, and in Ewing’s sarcoma. A fused gene combination that plays a role in chronic myelogenous leukemia led researchers to develop the drug Gleevec, which has dramatically improved survival rates for that disease.

Chinnaiyan believes the prostate gene fusions will eventually lead to similar treatments for prostate cancer.

“More immediately, we hope to develop tests for diagnosis or prognosis. But long-term, we hope this will lead to better therapies to treat prostate cancer. The key challenge is to find a drug that would go after this gene fusion,” Chinnaiyan says.

The gene fusion technology has been licensed to San Diego-based Gen-Probe Inc., which is working on a screening tool to detect gene fusions in urine. The tool could one day supplement or replace the prostate specific antigen, or PSA, test currently used to screen for prostate cancer.

The idea of translating laboratory research findings into a test or treatment that will impact patients is central to the new Michigan Center for Translational Pathology. The center brings together experts in genomics, proteomics and bioinformatics to look at common patterns and potential targets in cancer and other diseases. This is the first center of its kind in the nation in that it is associated with one of 39 National Cancer Institute-designated “comprehensive” cancer centers, a premier medical school and a large health system with both clinicians and patients.

The center’s goal is to study the genes, proteins and other markers on cells to develop new diagnostic tests or screening tools as well as targeted treatments for cancer and other diseases, with the key being to translate these laboratory discoveries into clinical applications.

Chinnaiyan and his team have received numerous awards and honors, including the American Association for Cancer Research Team Science Award for their previously published work on gene fusions, and the Specialized Program of Research Excellence Outstanding Investigator award. The new Center for Translational Pathology supported in part by the Prostate Cancer Foundation, which has offered to match up to $1 million dollars in donations to support work related to developing therapies against prostate cancer gene fusions at the university.

“Mapping of the human genome was only the beginning. Equipped with the comprehensive analysis of the human genome, we can now systematically examine the blueprint of disease at the molecular level. This essential knowledge may lead to better diagnostic tests and promising new treatments for cancer, cardiovascular disease, diabetes and other illnesses,” Chinnaiyan says.

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For information about the Michigan Center for Translational Pathology, go to http://www.med.umich.edu/mctp.

About 218,890 men will be diagnosed with prostate cancer this year, and 27,050 will die from the disease, according to the American Cancer Society. The gene fusion work is not currently available for treatment or diagnosis, and no clinical trials are currently recruiting. For information about prostate cancer and currently available treatments, go to http://www.mcancer.org or call the U-M Cancer AnswerLine at 800-865-1125.

In addition to Chinnaiyan, U-M study authors were Scott Tomlins; Saravana Dhanasekaran, Ph.D.; Bharathi Laxman; Qi Cao; Beth Helgeson; Xuhong Cao; David Morris, M.D.; Anjana Menon; Xiaojun Jing; Bo Han; James Montie, M.D.; Kenneth Pienta, M.D.; Diane Roulston; Rajal Shah, M.D.; Sooryanarayana Varambally, Ph.D.; and Rohit Mehra, M.D. Mark Rubin, M.D., from Brigham and Women’s Hospital, Dana-Farber Cancer Institute and Harvard Medical School is also a study author.

Funding for the study came from the U.S. Department of Defense, the National Institutes of Health, the Early Detection Research Network, the Prostate Cancer Foundation and Gen-Probe Inc.

The University of Michigan has filed for a patent on the detection of gene fusions in prostate cancer, on which Tomlins, Mehra, Rubin and Chinnaiyan are co-inventors. The diagnostic field of use has been licensed to Gen-Probe Inc. Chinnaiyan also has a sponsored research agreement with Gen-Probe; however, GenProbe has had no role in the design or experimentation of this study, nor has it participated in the writing of the manuscript.

Reference: Nature, Vol. 448, No. 7153, Aug. 2, 2007

Contact: Nicole Fawcett
nfawcett@umich.edu
734-764-2220
University of Michigan Health System

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August 1, 2007 Posted by | acute lymphoblastic leukemia, Alberta, Baltimore, Barcelona, Bethesda, Calgary, Canada, Cancer, Cancer Biology, Cancer Biology and Therapy, Chemotherapy, Childhood Lukemia, France, Genes, Genetic, Genetic Link, Genetics, Genome, Genomic, Germany, Global, Global Health Vision, Global News, Health Canada, Human Genome, Irvine, Italy, Japan, journal Nature Genetics, Leukemia, Lung Cancer, Medical Journals, Nature Genetics, Newfoundland, News, News Australia, News Canada, News Israel, News Italy, News Jerusalem, News Switzerland, News UK, News US, News USA, non-Hodgkin's lymphoma, Nova Scotia, Oncology, Osaka, Ottawa, Prince Edward Island, Public Health, Quebec, Research, RSS, RSS Feed, Slovakia, Spain, Toronto, UK, University of Michigan, US, Virginia, Washington DC, Washington DC City Feed, World News | 3 Comments

Huntington’s disease study shows animal models on target

This release is available in French.

An international team of researchers has published a benchmark study showing that gene expression in several animal models of Huntington’s Disease (HD) closely resembles that of human HD patients.

The results, published August 1, 2007, in the , validate the applicability of using animal models to study human disease and will have important consequences for the pertinence of these models in preclinical drug testing.

Huntington’s disease is an incurable and fatal hereditary neurodegenerative disorder caused by a mutation in the gene that encodes the huntingtin protein. Neurons in certain regions of the brain succumb to the effects of the altered protein, leading to severe motor, psychiatric, and cognitive decline. Several recent studies have shown that the mutant huntingtin protein modifies the transcriptional activity of genes in affected neurons. This disease mechanism is a promising new avenue for research into the causes of neuronal death and a novel potential approach for treatment.

Led by EPFL professor Ruth Luthi-Carter, and involving collaborators from six countries, the current study found a marked resemblance between the molecular etiology of neurons in animal models and neurons in patients with HD. This implies that animal models are relevant for studying human HD and testing potential treatments.

To come to this conclusion, the scientists measured the gene expression profile of seven different transgenic mouse models of HD, representing different conditions and disease stages. These profiles clarified the role of different forms and dosages of the protein hungtintin in the transcriptional activity of neurons. They then designed and implemented novel computational methods for quantifying similarities between RNA profiles that would allow for comparisons between the gene expression in mice and in human patients. “Interestingly, results of different testing strategies converged to show that several available models accurately recapitulate the molecular changes observed in human HD,” explains Luthi-Carter. “It underlines the suitability of these animal models for preclinical testing of drugs that affect gene transcription in Huntington’s Disease.”

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More Information:

EPFL Laboratory of functional neurogenomics, http://lngf.epfl.ch/

Alexandre Kuhn ; +41 21 693 1731
alexandre.kuhn@epfl.ch

Professor Ruth Luthi-Carter; +41 21 693 9533
ruth.luthi-carter@epfl.ch

Contact: Alexandre Kuhn
alexandre.kuhn@epfl.ch
41-216-931-731
Ecole Polytechnique Fédérale de Lausanne

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July 31, 2007 Posted by | Alberta, Baltimore, Barcelona, Bethesda, Calgary, Canada, DNA, France, Genes, Genetic, Genetic Link, Genetics, Genome, Genomic, Germany, Global, Global Health Vision, Global News, Health Canada, Human Genome, Huntington's disease, Italy, Japan, Neurodegenerative Diseases, Newfoundland, News, News Australia, News Canada, News Israel, News Italy, News Jerusalem, News Switzerland, News UK, News US, News USA, Nova Scotia, Nunavut, Ottawa, Prince Edward Island, Proteins, Quebec, Research, RSS, RSS Feed, Spain, Toronto, UK, US, Virginia, Washington DC, Washington DC City Feed, World News | Leave a comment

Flip of genetic switch causes cancers in mice to self-destruct, Stanford researchers find

STANFORD, Calif. – Killing cancerous tumors isn’t easy, as anyone who has suffered through chemotherapy can attest. But a new study in mice shows that switching off a single malfunctioning gene can halt the limitless division of tumor cells and turn them back to the path of their own planned obsolescence.

The surprising possibility that a cell’s own natural mechanism for ensuring its mortality could be used to vanquish tumors opens the door to a new approach to developing drugs to treat cancer patients, according to Dean Felsher, MD, PhD, associate professor of medicine (oncology) and of pathology at the Stanford University School of Medicine. Felsher is the senior author of the study to be published July 30 in the advance online version of the Proceedings of the National Academy of Sciences.

“Our research implies that by shutting off a critical cancer gene, tumor cells can realize that they are broken and restore this physiologic fail-safe program,” said Felsher.

Cancer can be notoriously resistant to medical treatment. Not only do cancer cells proliferate uncontrollably, they somehow circumvent the mechanism that causes normal cells to die when they get old or malfunction. That makes cancer cells effectively immortal unless doctors manage to squelch them.

The gene Felsher’s team studied produces a protein called Myc (pronounced “mick”), which promotes cell division. A mutation of the gene causes cells to overproduce the protein, prompting perpetual cell division and tumor growth. By turning off the mutated gene, the researchers found that not only did uncontrolled cell division cease, but the cells also reactivated a normal physiological mechanism, called senescence, which makes it possible for a cell to eventually die.

“What was unexpected was just the fact that cancer cells had retained the ability to undergo senescence at all,” said Felsher. Cancer researchers had long thought the senescence process had to be irreversibly disrupted for a tumor to develop.

The researchers worked with a series of mice engineered to have Myc-triggered cancers of either the liver, blood or bones, along with a specially constructed version of the Myc gene that they could switch off by feeding the mice antibiotics. When the mice dined on doses of the drugs, invariably, the tumors ceased growing and then diminished, with some disappearing over the course of just a few days.

Although Felsher’s lab had previously shown that mouse tumors diminished and disappeared when Myc was switched off, they hadn’t been sure how the process actually worked. Historically, most research involving genetic methods of battling cancer cells has focused on reactivating genes called tumor-suppressor genes, which are generally overcome by a proliferating cancer. No one had explored the idea that senescence might play a key role in diminishing tumors.

Felsher described senescence as acting like a fail-safe mechanism to stop cancer. When a cell detects a deleterious mutation, it launches the senescence process, resulting in the permanent loss of the cell’s ability to proliferate, thus halting any cancer.

“In order to become tumor cells, those cells have to overcome senescence,” said Chi-Hwa Wu, PhD, postdoctoral researcher in Felsher’s lab and first author of the study. Wu had the inspiration to explore whether the sudden diminishment they had observed in the tumors might be due to the reactivation of some latent remnant of the trigger for senescence.

Through a series of experiments looking at enzymes associated with the senescence process, as well as some molecular markers, Wu confirmed her suspicion. And not only was senescence occurring in cells that had been thought to be incapable of it, the process was reactivated in all the different tumors they studied.

Consider it a cell version of the Jekyll-and-Hyde transformation. “It’s sort of like Mr. Hyde realizing that there’s something wrong with him and then being able to put himself back into his normal state as Dr. Jekyll,” Felsher said.

In addition to the deepened understanding of how the process of senescence works, Felsher and Wu see a lot of potential for new approaches to treating cancer, beyond the traditional tactic of trying to kill cancer cells directly. “This work implies that maybe part of the strategy should involve figuring out how to get the cancer cells to just be allowed to do what they originally wanted to do anyway, which is to not be proliferating endlessly and growing uncontrolled,” said Felsher.

The next step for the team is to see how well the approach works in human cancer cells. “And we’re also trying to figure out what the mechanism is,” Felsher said. “What are the molecular mechanisms of this, so that we can figure out how to better treat cancer””

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Other authors on the research paper are Jan van Riggelen, PhD, postdoctoral researcher; Alper Yetil, graduate student in cancer biology; Alice Fan, MD, instructor in medicine (oncology), and medical student Pavan Bachireddy.

The study was funded by the National Cancer Institute, the National Institutes of Health, the Leukemia and Lymphoma Society, the Burroughs Wellcome Fund, the Damon Runyon Lilly Clinical Investigator Award, the Lymphoma Research Foundation and the Howard Hughes Medical Institute.

Stanford University Medical Center integrates research, medical education and patient care at its three institutions – Stanford University School of Medicine, Stanford Hospital & Clinics and Lucile Packard Children’s Hospital at Stanford. For more information, please visit the Web site of the medical center’s Office of Communication & Public Affairs at http://mednews.stanford.edu.

Contact: Lou Bergeron
louisb3@stanford.edu
650-723-3900
Stanford University Medical Center

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July 31, 2007 Posted by | acute lymphoblastic leukemia, Alberta, Baltimore, Barcelona, Bethesda, Biological Sciences, Calgary, Canada, Cancer, Cancer Biology, Cancer Biology and Therapy, Childhood Lukemia, France, Genes, Genetic, Genetic Link, Genetics, Genome, Genomic, Germany, Global, Global Health Vision, Global News, Health Canada, Howard Hughes Medical Institute, Human Genome, Italy, Japan, Leukemia, Medical Journals, Molecular Biology, National Cancer Institute, National Institutes of Health, Newfoundland, News, News Australia, News Canada, News Israel, News Italy, News Jerusalem, News Switzerland, News UK, News US, News USA, NIH, non-Hodgkin's lymphoma, Nova Scotia, Nunavut, Osaka, Ottawa, Prince Edward Island, Public Health, Quebec, Research, RSS, RSS Feed, Toronto, UK, US, Virginia, Washington DC, Washington DC City Feed, Wellcome Trust, World News | Leave a comment

New studies on goat milk show it is more beneficial to health than cow milk

-It helps to prevent diseases such as anaemia and bone demineralisation
-UGR researchers have carried out a comparative study on the properties of goat milk compared to those of cow milk. Rats with induced nutritional ferropenic anaemia have been used in the study
-Goat milk helps digestive and metabolic utilisation of minerals such as iron, calcium, phosphorus and magnesium
-Part of the results of this research have been published in the prestigious scientific journals International Dairy Journal and Journal Dairy Science

C@MPUS DIGITAL Research carried out at the Department of Physiology of the University of Granada has revealed that goat milk has more beneficial properties to health than cow milk. Among these properties it helps to prevent ferropenic anaemia (iron deficiency) and bone demineralisation (softening of the bones).

This project, conducted by Doctor Javier Díaz Castro and directed by professors Margarita Sánchez Campos, Mª Inmaculada López Aliaga and Mª José Muñoz Alférez, focuses on the comparison between the nutritional properties of goat milk and cow milk, both with normal calcium content and calcium enriched, against the bioavailability of iron, calcium, phosphorus and magnesium. To carry out this study, the metabolic balance technique has been used both in rats with experimentally induced nutritional ferropenic anaemia and in a control group of rats.

In order to know how the nutritive utilisation of these minerals may affect their metabolic distribution and destination, the UGR researcher has determined the concentration of these minerals in the different organs involved in their homeostatic regulation and different haematological parameters in relation to the metabolism of the minerals.

Better results with goat milk
Results obtained in the study reveal that ferropenic anaemia and bone demineralisation caused by this pathology have a better recovery with goat milk. Due to the higher bioavailability of iron, calcium, phosphorus and magnesium, the restoration of altered haematological parameters and the better levels of parathyroid hormone (PTH), a hormone that regulates the calcium balance in the organism was found in the rats that consumed this food.

Javier Díaz Castro points out that the inclusion of goat milk with normal or double calcium content in the diet “favours digestive and metabolic utilisation of iron, calcium and phosphorus and their deposit in target organs – parts of the organism to which these minerals are preferably sent – involved in their homeostatic regulation”.

According to this researcher, all these conclusions reveal that regular consumption of goat milk – a natural food with highly beneficial nutritional characteristics – “has positive effects on mineral metabolism, recovery from ferropenic anaemia and bone mineralisation in rats. In addition, and unlike observations in cow milk, its calcium enrichment does not interfere in the bioavailability of the minerals studied”.

Although there is no doubt that these findings may be a base for further in depth study of the multiple health benefits of goat milk, the UGR researcher warns that “studies in humans are still required in order to confirm the findings obtained in rats and to promote goat milk consumption both in the general population and in the population affected by nutritional ferropenic anaemia and pathologies related to bone demineralisation”. Part of the results of this research has been published in the prestigious scientific journals International Dairy Journal and Journal Dairy Science.

Reference: Dr Javier Díaz Castro. Department of Physiology of the University of Granada.
Tel.: +34 958248319. Mobile: +34 654574434. Email: javierdc@ugr.es

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July 30, 2007 Posted by | Alberta, Baltimore, Barcelona, Bethesda, Biological Sciences, Bone Demineralisation, Bone Diseases, Calgary, Canada, France, Germany, Global, Global Health Vision, Global News, Italy, Japan, Medical History, Medical Journals, Molecular Biology, Newfoundland, News, News Australia, News Canada, News Israel, News Italy, News Jerusalem, News Switzerland, News UK, News US, News USA, NIH, Nova Scotia, Nunavut, Nutritional Anthropology, Ottawa, Pennsylvania, Prince Edward Island, Quebec, Research, RSS, RSS Feed, Slovakia, Toronto, UK, University of Granada, US, Virginia, Vitamin D, Washington DC, Washington DC City Feed, World News | Leave a comment

Research links genetic mutations to lupus

WINSTON-SALEM, N.C. – A gene discovered by scientists at Wake Forest University School of Medicine has been linked to lupus and related autoimmune diseases. The finding, reported in the current issue of Nature Genetics, is the latest in a series of revelations that shed new light on what goes wrong in human cells to cause the diseases.

“This research is a huge leap toward understanding the cause of lupus and related autoimmune diseases,” said Fred Perrino, Ph.D., a co-author on the paper and a professor of biochemistry at Wake Forest. “There had been few clues before now.”

Perrino, who discovered the gene in 1998, said he suspected it was involved in human disease, but it took a group of researchers from around the world collaborating to put the puzzle together.

“We’ve known that lupus was a complex disease, but now we have a specific protein and a particular cellular process that appears to be one of the causes,” said Perrino. “We’re connecting the dots to understand the biology of what’s going on with the disease.”

In Nature Genetics, lead author Min Ae Lee-Kirsch, M.D., from the Technische Universität Dresden in Dresden, Germany, and colleagues report finding variations of the TREX1 gene discovered by Perrino in patients with systemic lupus erythematosus. The study involved 417 lupus patients from the United Kingdom and Germany. Mutations were found in nine patients with lupus and were absent in 1,712 people without lupus.

“Our data identify a stronger risk for developing lupus in patients that carry variants of the gene,” said Lee-Kirsch.

In recent years, the gene was also linked to Aicardi-Goutieres syndrome, a rare neurological disease that causes death in infants, and to chilblain lupus, an inherited disease associated with painful bluish-red skin lesions that occur during cold weather and usually improve in summer. The current research also links it to Sjogren’s syndrome, a form of lupus.

The diseases are all autoimmuine diseases, which means that the body makes antibodies against itself. In lupus, these antibodies cause pain and inflammation in various parts of the body, including the skin, joints, heart, lungs, blood, kidneys and brain. The disease is characterized by pain, heat, redness, swelling and loss of function.

Perrino began studying the protein made by the gene more than 14 years ago.

“We basically cracked open cells to locate the protein and find the gene,” said Perrino. “In the 14 years since, we’ve learned a lot about the protein and how it functions.”

The gene manufactures a protein, also known as TREX1, whose function is to “disassemble” or “unravel” DNA, the strand of genetic material that controls processes within cells. The “unraveling” occurs during the natural process of cells dying and being replaced by new cells. If a cell’s DNA isn’t degraded or unraveled during cell death, the body develops antibodies against it.

“If the TREX1 protein isn’t working to disassemble the DNA, you make antibodies to your own DNA and can end up with a disease like lupus,” said Perrino.

Perrino and colleagues at Wake Forest have been studying the gene and its protein since 1993. Thomas Hollis, Ph.D., an assistant professor of biochemistry at Wake Forest, is credited with solving the structure of both TREX1 and a similar protein, TREX2. Perrino has also developed a way to measure the function of the proteins.

In a study reported in April in the Journal of Biological Chemistry, Hollis and Perrino found that three variations of the gene reduced the activity of the protein by four- to 35,000-fold.

“Now that we have the structure, we can understand how it disassembles DNA and how mutations in the gene may affect that process,” said Hollis.

The researchers hope that understanding more about the gene’s mutations and the structure of the protein may lead to drug treatments to help ensure that mutant copies of the gene are inactive.

###
Media Contacts: Karen Richardson, krchrdsn@wfubmc.edu; Shannon Koontz, shkoontz@wfubmc.edu; at 336-716-4587.

Wake Forest University Baptist Medical Center is an academic health system comprised of North Carolina Baptist Hospital and Wake Forest University Health Sciences, which operates the university’s School of Medicine. U.S. News & World Report ranks Wake Forest University School of Medicine 18th in primary care and 44th in research among the nation’s medical schools. It ranks 35th in research funding by the National Institutes of Health. Almost 150 members of the medical school faculty are listed in Best Doctors in America.

Contact: Karen Richardson
krchrdsn@wfubmc.edu
336-716-4453
Wake Forest University Baptist Medical Center

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July 29, 2007 Posted by | Alberta, Baltimore, Barcelona, Bethesda, Biological Sciences, Calgary, Canada, Clinical Trials, France, Genes, Genetic, Genetic Link, Genetic Marker C allele of rs10505477, Genetics, Genome, Genomic, Global, Global Health Vision, Global News, Health Canada, Human Genome, Italy, Japan, Lupus, Nature Genetics, Newfoundland, News, News Australia, News Canada, News Israel, News Italy, News Jerusalem, News Switzerland, News UK, News US, News USA, NIH, Nova Scotia, Nunavut, Osaka, Ottawa, Prince Edward Island, Public Health, Quebec, Research, RSS, RSS Feed, Slovakia, Spain, Toronto, UK, US, Virginia, Wake Forest University Baptist Medical Center, WASHINGTON, Washington DC, Washington DC City Feed, World Health Organisation, World News | 1 Comment

A new century of Alzheimer’s disease research

Mayo Clinic scientists aim to improve risk prediction, diagnosis and treatment
JACKSONVILLE, Fla. — Imagine the day when a routine visit to the family doctor includes a simple blood test to predict the risk for developing Alzheimer’s disease (AD). If the test returns a worrisome result — too many sticky brain proteins that might begin to gum up memory and thought in 10 to 15 years — a person could be offered an aspirin-like pill to keep those proteins in check.

That is the future a visionary team of researchers at Mayo Clinic’s campus in Jacksonville aims to reach.

“It will be very straightforward, like today’s blood cholesterol test to gauge risk of developing heart disease,” says Steve Younkin, M.D., Ph.D., a Mayo Clinic neuroscientist. “If your cholesterol profile is out of whack, treatment with a simple statin drug can reduce that risk. Our goal is to develop a similar kind of testing and treatment to keep the brain in balance.”

Researchers and physicians at Mayo Clinic’s sites in Florida, Minnesota and Arizona are studying various aspects of Alzheimer’s. When combined, the elements provide a comprehensive approach to unraveling the mystery of the disease: from understanding why it develops, to how it can be diagnosed early, treated effectively and, ultimately, prevented.

Much of the basic lab, animal research and drug discovery occurs in Jacksonville. Mayo researchers in Jacksonville, Rochester, Minn., and Scottsdale, Ariz., are studying aging’s effects in thousands of elderly individuals. Researchers want to know how aging changes brain structure, thought processes and blood chemistry, so they can model and predict progression to Alzheimer’s disease.

“Whether it is working with people or doing lab science, we have really tried to focus our research on ways in which we can make a difference in the lives of our patients, both today and tomorrow,” says Todd Golde, M.D., an Alzheimer’s disease researcher who chairs the Department of Neurosciences at Mayo Clinic Jacksonville.

And, by all accounts, that focus will likely begin to pay off in this second century of Alzheimer’s research. Until 1986, some 80 years after German physician Alois Alzheimer discovered the brain abnormalities associated with the disease, physicians understood little about Alzheimer’s disease. But several decades ago, the pace of discovery began to accelerate, says Ronald Petersen, M.D., Ph.D., a Mayo physician in Rochester who directs the Mayo Clinic Alzheimer’s Disease Research Center (ADRC), encompassing the research programs in Jacksonville and Rochester.

“We have moved a great distance forward in understanding what might be the key, or, in the least, an important aspect of this disease,” Dr. Petersen says. “And we are at the threshold of developing therapies that we hope will eventually impact Alzheimer’s disease.”

“We are not slogging through a fog anymore,” says Dr. Younkin, who has helped define the direction that Alzheimer’s research has taken in many of the world’s research labs. “We can see the top of the hill for the first time, and while we probably won’t get where we want to be for many years, it is really exciting.” Dr. Younkin helped discover that a single brain protein, known as amyloid-beta 42 (AB42), appears to be the central player in the disorder. And much of Alzheimer’s drug research is focused on different ways to attack Aâ42, believed to be the most vulnerable target — the Achilles’ heel — of Alzheimer’s disease.

“We know AB42 is always on the scene and is clearly important,” says Richard Caselli, M.D., who heads Alzheimer’s disease research at Mayo Clinic in Arizona. “So the prevailing model is that AB42 is it, and if you can somehow control AB42, you can control Alzheimer’s disease.”

Protein provides initial “insult”

Today, an estimated 20 million people worldwide have Alzheimer’s disease. Within the higher-functioning portions of their brains (the areas responsible for thought and memory), twisting tangles of threads made up of chains of tiny “tau” proteins are being assembled inside billions of nerve cells (neurons). Outside the neurons, other amyloid-beta (AB) proteins are fusing together into sticky clumps (plaque) — akin to the substance that clogs heart arteries. Together, these tangles and plaques disrupt the normal functioning of the nerve cells, destroying the pathways along which packets of chemical “information” move. Memories cannot be stored or retrieved, and, eventually, the brain cannot control the body. Each year about 4.6 million more people develop Alzheimer’s worldwide, and that number is escalating rapidly. As many as 4.5 million people in the United States have Alzheimer’s, according to the National Institute on Aging, and experts predict that by 2050 that total will rise to approximately 15 million people.

To find out what causes Alzheimer’s — plaques, tangles or both — researchers first began studying people who developed the disease early, before age 65. A breakthrough came when the gene that produced the AB fragments (amyloid-beta precursor protein, or APP) was found on chromosome 21. This made sense, because patients with Down syndrome, all of whom inherit an extra chromosome 21, typically develop early brain plaques and tangles.

Then scientists linked mutations in two other genes to early-onset Alzheimer’s, and these two genes were involved in the production of AB. In 1995, Dr. Younkin and Harvard researcher Dennis Selkoe, M.D., independently found that all three of these mutations increase the production of either AB in general, or a particular type of AB that is made up of 42 amino acids — just slightly longer than the typical 40 amino acid AB fragment.

Dr. Younkin’s finding was pivotal, made just as the scientist moved his laboratory from Case Western Reserve to Mayo Clinic’s campus in Jacksonville. An avalanche of confirmatory studies was soon published, and the Alzheimer’s research world quickly turned its attention to figuring out ways to disrupt AB production. Some researchers, such as Dr. Younkin, believed that in the brains of people who have Alzheimer’s, AB42 is deposited first, providing the initial toxic damage that leads to plaque formation, and then to disruption of tau inside neurons. The concept is known as the amyloid cascade hypothesis and is now accepted by many Alzheimer’s researchers almost as a gospel truth.

Early laboratory analysis of AB42 showed that the extra two molecules seemed to form a hook on the amyloid protein, making it more likely to stick to other amyloid proteins in the brain. Thus, researchers concluded that AB42 is highly prone to forming deposits. Synthesized particles of AB42 will fuse to each other within hours in an animal’s brain, but weeks are required for AB40 to adhere. More recent research has shown that the AB42 protein folds in such a way that it creates a pleated-sheet-like “template” that acts to chemically attract other proteins, and together these proteins grow in a crystalline fashion like a snowball emerging from a single icy flake.

“With a potential target, many in the pharmaceutical industry who want to design treatments for AD began bearing down on the issue, and that effort has completely turned around the prospects of finding something that could eventually help our patients,” Dr. Younkin says.

Now more than 100 mutations have been found in the three genes that cause early Alzheimer’s, and all increase production of AB42.

Of the AB produced normally in humans, 5 percent to 20 percent is AB42. As people grow older, small numbers of plaques and tangles form. The risk that these lesions will cause dementia increases with age; half of all people 85 and older are believed to have some stage of Alzheimer’s. Researchers think this common form of Alzheimer’s is triggered by a combination of normal genetic susceptibilities and other damage, such as from head trauma or unknown environmental insults. Slowly, AB40 and AB42 build up in the brain and begin to disrupt the thoughts and memories that define who we are.

Ratios predict risk

Dr. Younkin joined a core group of researchers and physicians at Mayo Clinic already collaborating to study the basic biology of the disease and methods of caring for patients who have the disorder. Based on the knowledge that Alzheimer’s is a disease of tau tangles as well as AB plaque, these scientists were already developing a mouse that spontaneously overproduces tau proteins.

Mayo Clinic researchers were the first to genetically engineer a mouse to express a mutation of the gene that controls tau production, and in 2000 they reported in Nature Genetics that the “tau” mouse develops the same kind of neurofibrillary tangles seen in human dementia. In 2001, the Mayo Clinic team produced another new engineered mouse, the first to exhibit tangles as well as the two forms of plaque (AB40 and AB42). In the journal Science, Michael Hutton, Ph.D., Dennis Dickson, M.D., Jada Lewis, Ph.D., Shu-Hui Yen, Ph.D., and Eileen McGowan, Ph.D., presented the mouse model, saying it is the best animal model possible to test therapies aimed at slowing down, or halting, neurodegeneration.

The engineered mouse strengthened the notion that development of tangles followed that of plaque. The tangle pathology was enhanced in regions where the plaque occurred, says Dr. Hutton, a neurobiologist. But what was also interesting was that these mice, the ones that also developed plaque, produced more tau than did mice with only a tau mutation. “That proved that there is an interaction between tau and amyloid, and it is that interaction that causes cognitive deficits,” he says.

These Mayo mice are offered to any scientist studying Alzheimer’s disease for just the cost of producing them. They are also made available to pharmaceutical companies to help them test whether the drugs they are developing could reduce the production of tangles and/or plaque.

The mouse models helped provide a breakthrough discovery for the Mayo Clinic researchers.

Physicians at the three Mayo Clinic sites have been collecting blood from thousands of Alzheimer’s patients, as well as study participants who do not have the disease, to determine how blood chemistry changes over the years (see associated story, Defining Alzheimer’s disease risk with the help of thousands). With support from the National Institutes of Health, they had been examining blood serum for evidence of protein “markers” that could help predict which people would develop the disease over time. One marker is AB.

Although no one knows what the normal function of AB is, the Mayo Clinic researchers found that it could be measured in blood, and that levels of both AB40 and AB42 varied in people who developed the disease. What they discovered through this analysis, however, surprised them, says Neill Graff-Radford, M.D., who heads the ADRC’s Memory Disorder Clinic and has led the work on a blood test designed to predict a person’s risk of developing Alzheimer’s.

“Levels of both AB40 and AB42 in the blood rise as a person gets older, but then, in some people, AB42 decreases,” he says. Turning to the transgenic mice, the researchers found that as soon as plaque began to develop in the brain, levels of AB42 decreased in the blood and spinal fluid.

Drs. Graff-Radford and Younkin had expected aging and genetic-related overproduction of AB42 — the insult that leads of Alzheimer’s development — would be reflected in blood samples. But sitting together in a room, looking at the charts that lead statistician Julia Crook, Ph.D., put together, the researchers experienced a classic “a-ha” moment. They saw it. The researchers realized that levels of AB42 had dropped because the protein was being sopped up, absorbed, by quickly forming plaques. In contrast, they discovered that at the same time, plasma levels of AB40 either continued to increase or decline much slower than AB42.

Drs. Graff-Radford, Younkin and Crook found that a low level of AB42 and a higher level of AB40 in blood could be seen three to five years before symptoms of the disease occurred. From these data, the Mayo Clinic researchers determined a scale of ratios for determining when symptoms will begin: two, four, or eight to 10 years.

“This blood test reflects some of the risks of who is going to develop the disease and when it is going to show up,” says Dr. Graff-Radford. “The crucial point is that it could eventually offer us a predictive test.”

The Mayo Clinic team is continuing to “follow the blood” of 2,000 participants in Rochester, and 1,000 in Jacksonville.

But the researchers know that if their AB40/AB42 ratio blood test ultimately can predict who will develop Alzheimer’s disease, people won’t be interested in knowing their risk unless something can be done to reduce that risk.

A pill a day keeps Alzheimer’s away

In the late 1990s, Dr. Golde’s research group as well as other investigators discovered that compounds that inhibited production of AB actually inhibited AB40 more than AB42. As AB42 appeared to be the real culprit in Alzheimer’s, Dr. Golde was convinced that a systematic search for compounds that preferentially lowered AB42 would be successful. However, a two-year effort did not find such a compound.

Then in 2000, Dr. Golde and Eddie Koo, M.D., who worked at the University of California, San Diego, screened several nonsteroidal anti-inflammatory drugs (NSAIDs) at high concentrations. To their surprise, they found that while some NSAIDs, such as naproxen and aspirin, had no effect on AB42, others, such as ibuprofen and indomethacin, did.

The possible significance of this finding was immediately apparent, Dr. Golde says. Large population studies had hinted that people who have used NSAIDs had a lower risk of developing Alzheimer’s. While scientists thought these NSAIDs might be reducing inflammation in the brain — and there is a lot of it in a brain with Alzheimer’s — Drs. Golde and Koo wondered if any might be working to prevent the development of Alzheimer’s by selectively inhibiting production of AB42.

Still, Drs. Golde and Koo realized that, regardless of how NSAIDs might be working to decrease the risk of developing Alzheimer’s, conducting clinical trials of NSAIDs in populations at risk for Alzheimer’s or in those with the disease would be difficult. Long-term use of high-dose NSAIDs can cause stomach ulcers, kidney damage and gastrointestinal bleeding in anyone, and those side effects would be even more prevalent in the elderly. Moreover, if NSAIDs were working by lowering AB42, Dr. Golde knew very high doses of the NSAIDs would be needed to make a difference in Alzheimer’s risk.

This meant that a compound that could successfully and significantly lower AB42 must be one without such severe side effects. So, the first NSAIDs that Drs. Golde and Koo screened were known as COX2 inhibitors because they were believed to be safer. (NSAIDs reduce inflammation because they target enzymes that are known as cyclooxygenases or COX, and classic NSAIDs, such as ibuprofen and indomethacin, nonselectively inhibit the two types of COX enzymes, COX1 and COX2.)

But, again to their surprise, Drs. Golde and Koo found that many COX2 inhibitors actually had the opposite effect on AB42 — rather then decreasing it, they increased it. The investigators then expanded their search to look more closely at compounds related to NSAIDs that might lower AB42 but result in greatly reduced COX activity.

So they tested a compound called r-flurbiprofen.

R-flurbiprofen is the mirror image of the COX-inhibiting drug s-flurbiprofen, but because it is structurally distinct (much as a person’s right and left hands have the same overall structure but cannot be superimposed on each other), it does not inhibit COX enzymes. The result was, finally, encouraging — r-flurbiprofen inhibited AB42 production both in cells and in the brains of mice.

As it happened, the biotech firm Myriad Genetics was testing r-flurbiprofen to treat prostate cancer, because the agent had shown it could reduce the size of tumors in mice studies. Armed with additional data that r-flurbiprofen decreased AB levels in an Alzheimer’s mouse model and improved the cognitive deficits found in that model, Drs. Golde and Koo personally approached the drug company to encourage them to test r-flurbiprofen in Alzheimer’s disease.

Myriad Genetics agreed, and in 2006 the company reported results from a phase II clinical trial enrolling 207 patients with mild Alzheimer’s. The study found that r-flurbiprofen produced functional and cognitive improvements, ranging from 34 percent to 48 percent, in patients who took the highest dose, 1,600 milligrams a day. “And it was remarkably safe,” says Dr. Golde. “It was much better tolerated in humans than it was in mice.” There was also evidence that the drug not only improved symptoms but may have actually slowed the course of disease, he says. Current drugs offered to Alzheimer’s patients only relieve symptoms.

Based on these findings, Myriad Genetics launched a 1,600-participant phase III clinical trial in the summer of 2006, describing it as the largest placebo-controlled study ever to be undertaken of an investigational medicine in patients with Alzheimer’s. Patients will use r-flurbiprofen (known now as Flurizan) for 18 months.

Dr. Golde, who is not involved in this trial, suspects that r-flurbiprofen will show some benefit, but that newer, designer AB42-lowering agents might be better. “A more potent drug would likely be more effective, but it will take a long time to develop such a second-generation drug,” he says. “The beauty of r-flurbiprofen is that it can be on the market quickly.”

Dr. Golde stresses a cautionary note. He worries that because of these findings, people with Alzheimer’s, or those who are at risk for developing the disease, might decide to take high doses of an over-the-counter AB42-lowering NSAID, such as ibuprofen. Because of the side effects associated with NSAID use, this could be quite harmful, he says. Indeed, because it does not inhibit COX at therapeutic levels, r-flurbiprofen is not an NSAID, whereas flurbiprofen is, he adds.

AB42-lowering agents may turn out to be “either a magic bullet or a magic shotgun,” he says. “They might be lowering AB42, reducing inflammation and doing five other things that we don’t know about.”

But to Mayo Clinic researchers, the big question is whether this compound, or any other similar kind of agent, can be used much earlier in people deemed to be at risk of developing Alzheimer’s.

“I think Alzheimer’s is going to be much easier to treat if you can prevent accumulation of AB in your brain, than if you try to treat it once plaques form,” Dr. Golde says. “We know that statins don’t work very well if a heart artery is 99 percent blocked, but do if they are taken earlier. The same thing would go for a drug designed to prevent Alzheimer’s.”

If r-flurbiprofen shows solid benefit in the phase III clinical trial, then it could be tested as a preventive agent, Dr. Golde says. But he adds that this “could possibly be the costliest trial ever to be conducted,” because it would take decades and involve thousands of people. However, Dr. Golde and his clinical colleagues share a common goal: to eventually conduct cost-effective prevention trials.

Restoring memory via tau

Mayo Clinic researchers also are working to prevent additional damage from occurring and to repair existing lesions in people who already have symptoms of Alzheimer’s.

In the process, they are attempting to answer the question that has stumped the Alzheimer’s research world: to what degree is AB responsible for the neurodegeneration seen in the disease”

No one knows what AB “normally” does inside the brain. “That is the biggest secret in Alzheimer’s disease research,” says Dr. Caselli. “We’d like to know what role it plays.”

And no one understands how tau interacts with AB.

Mayo Clinic researchers know a lot about tau, which helps stabilize the roadlike microtubules that run inside nerve cell bodies. In the world of neurobiology, tau is the big player, responsible for about 30 forms of neurodegeneration, including frontotemporal dementia, the second most common form of dementia after Alzheimer’s.

Alzheimer’s disease is the only form of dementia in which AB is involved.

As Alzheimer’s develops, the shape of tau molecules inside neurons changes; they begin to come off the microtubules they had once supported, and bind together into paired and twisted filaments. “The hypothesis is that AB stresses neurons, releasing cascades of signals that affect the phosphorylated state of tau bound to microtubules, causing them to be released,” says Dr. Hutton. This process proves to be toxic to the microtubules, which in turn cannot transport the molecular cargo needed to keep the neuron alive.

“Either the roads provided by the microtubules break down because of loss of tau, or tau accumulates into tangles that block these roads,” he says. “We don’t have evidence as to whether it is the tangles or the loss of tau that is causing cell death.

“The tangles we see are an end-stage event, whereas there is plenty of tau aggregation that occurs before these roadblocks appear,” says Dr. Hutton. “In any case, the brain can’t cope without tau.”

Because of the connection between AB and tau loss, the Mayo Clinic researchers believe that if AB is treated before the onset of tau damage, progression of the disease can be prevented. “We also know that tau is responsible for neuronal death, so we also have been developing ways to prevent tau toxicity, which could cause a major slowing of the disease,” Dr. Hutton says.

So the researchers turned again to their tau transgenic mouse, which features a unique on-off “switch”¬ to control the expression of the mutant gene so that the disease could be studied at both early and late stages.

During these experiments, the Mayo Clinic group and their collaborators were stunned to find that they could reverse tau pathology early on, and restore memory to mice that had started to develop cognitive problems.

But researchers were in for an even bigger surprise, Dr. Hutton says. “What was amazing, absolutely staggering in fact, is that when we aged the mice further — to the point where the pathology was quite severe, a lot of neurons had died, and the mouse couldn’t remember any of its tasks — when we hit this molecular switch, the mouse recovered a lot of its memory.”

To the research team, this demonstrated that Alzheimer’s is potentially a reversible process: that if deposition of AB is not stopped in time, then it may be possible to halt tau degradation and restore damaged nerves. “Once you get the disease, the effectiveness of AB therapy may be limited, so we hope tau will be potentially a more exciting target,” Dr. Hutton says. “If we are able to remove the blockage that is clogging microtubules, it may be that the system will just start again, with neurons back functioning normally.”

Dr. Lewis says the studies suggest that toxicity to neurons caused by tau begins before tangles develop. “If so, we may be able to repair that process so that the neuron can rebound,” she says.

Their achievement was reported in 2005 in Science.

“These tau findings changed our ideas about what the potential for recovery is in Alzheimer’s, but also about what is causing memory loss in the patients in the first place,” Dr. Hutton says. “Our mice lost between 30 percent and 50 percent of the neurons in the parts of the brain that are responsible for memory function. But, still, sufficient numbers of neurons were left so that some memory function was actually recoverable. The neurons began to work properly once the disease process was halted.”

Dr. Hutton says the tau research is five to 10 years behind AB, and the focus of the “tauologists” at Mayo Clinic is to study how tau tangles disrupt microtubules as well as how the brain recovers and removes those tangles. What they find out can be applied to all diseases of dementia in which tau is involved — and that is the majority, if not all.

Researchers also are busy using the tau mouse to test small molecules that have already been developed for other diseases that may stop tau from initially changing its chemical shape. One design for a therapeutic drug could be to inhibit the molecules involved in the abnormal phosphorylation of tau, and another might be to find a way to stabilize the microtubules. Amazingly, a cancer drug, Taxol, works to do just that, Dr. Hutton says, because stable microtubules cannot divide — which a cancer needs to do. He is working with a pharmaceutical company to see if such a cancer treatment might work for Alzheimer’s disease.

All in the genes

Many diseases spring from a person’s unique mix of genes, the variations that flow down the generations through combinations of eggs and sperm. And given the progress science has made in decoding the human genome, Dr. Younkin is convinced that some day soon researchers will have a blueprint of all the genes that raise a person’s risk of developing Alzheimer’s, even if by just a little bit here and there.

“In the world of complex genetics, this is a very exciting time,” Dr. Younkin says. He is part of a team of scientists from four institutions who just reported locating the 14th gene that has a statistically significant association with Alzheimer’s disease.

In a January 2007 online issue of Nature Genetics, the researchers reported a new gene called SORL1 (sortilin-related receptor). They found that people who inherited certain variations of SORL1 appear to have an increased risk of developing the late-onset form of Alzheimer’s. Although they have not pinpointed the exact variations, the researchers connected the gene to disease in six different groups of people, finding that Caucasians who have Alzheimer’s displayed a variation in one area of the gene’s sequence, while African-Americans, Hispanics and a group of Arabs with the disease displayed variations in a different location. Almost 7,000 people, of whom about half had the disease, were included in the analysis.

In cell culture studies, the researchers found that decreasing the amount of SORL1 protein increased the cells’ production of AB.

While SORL1 will likely turn out to be a minor contributor to Alzheimer’s disease in general, adding all such players together could ultimately provide the missing puzzle pieces that solve the disease, Dr. Younkin says.

“Alzheimer’s is a great disease for doing genetics, because there are clear indications that a person has the disease, which makes it possible to test that individual’s DNA and RNA,” he says. Those genes never change, so profiling the more than 300,000 functional inherited variations in the approximately 30,000 genes each person has can define Alzheimer’s disease’s complex genetic signature, he says.

“We can now look at the difference in gene variants between a person who has Alzheimer’s and a person who does not; an analysis like that would only take several days,” Dr. Younkin says. “If we can find those variations in thousands of people, we could begin to see which genes play important roles in Alzheimer’s disease, and these genes could possibly be targets for novel therapeutic agents.”

“It is all possible to do, which is wonderful,” he says, but adds that while Mayo Clinic is doing such analysis with the thousands of patients the institution cares for across its three sites, many more people would need to be involved.

As much as Alzheimer’s disease research has advanced in the past 20 years, Mayo Clinic researchers say caution is warranted about the future prospect of breakthrough drugs in this decade, or even the next. Dr. Petersen expresses this hesitancy. “There are a million studies that describe how things could be happening, and they make sense, but we don’t know that they are true,” he says. “We have to keep an open mind.”

Still, there has never been a better time, or a brighter outlook, for Alzheimer’s disease researchers who spend their careers trying to find an answer to this most devastating of diseases. “Before, there was a lot of faith and not a lot of science. It was like you were leading a detective-like investigation into the Alzheimer’s killer using chisels and hammers to chip away at deeply buried clues,” Dr. Golde says.

“Now we have the scientific tools and fancy machines that allow us to be so much more productive and to progressively solve this mystery,” he says. “It’s a new century.”

Defining Alzheimer’s disease risk with the help of thousands

As much as investigators worldwide are betting that the sticky plaques made up of amyloid beta (AB) fulfill the role of central villain in Alzheimer’s disease, all researchers know about cognitively normal people who, during an autopsy, were found to have brains full of the plaque.

These patients may not be as sensitive to AB’s toxic effects as others are, some scientists speculate.

But really, scientists can’t explain it.

That is why Mayo Clinic researchers in Minnesota, Florida and Arizona are enrolling thousands of individuals, including patients who do not have memory problems, people in mild cognitive decline and patients with the disease, to participate in what collectively is one of the biggest Alzheimer’s disease epidemiological research efforts in the nation.

In Rochester, which is in Olmsted County, Minn., more than 2,000 residents from 70 to 89 years old have been randomly selected and have signed up. And in Scottsdale, Ariz., 600 asymptomatic adults in their 50s and 60s are enrolled in an effort to define “normal aging.” In Jacksonville, Fla., over 1,000 individuals, including more than 350 African-Americans, are participating. Hundreds of Alzheimer’s disease patients being treated at the three Mayo campuses are also taking part.

With the generous permission of participants, researchers are routinely collecting blood samples to define genetic profiles and look for changes in blood chemistry, including proteins that are sent floating downstream from the brain.

“We want to put all this information together to create a predictive equation that can determine an individual’s risk of developing Alzheimer’s disease,” says Ronald Petersen, M.D., Ph.D., director of the Mayo Clinic Alzheimer’s Disease Research Center. “The whole idea is to move back detection of the disease process earlier and earlier.”

Such biological profiling could also help in the effort to develop and test therapeutic drugs, he says. “If we have clarified who is more likely to develop the disease, we can allocate treatment appropriately,” he says.

Much of the blood collected by Mayo Clinic in Rochester and Scottsdale is shared with researchers at Mayo Clinic in Jacksonville. “The cross-talk between these three centers is really advancing Alzheimer’s disease science,” says Richard Caselli, M.D., who heads Alzheimer’s disease research at Mayo Clinic’s campus in Scottsdale.

The patients also undergo periodic cognitive testing, and many of them offer to participate in a bevy of different imaging studies. Based on the pioneering imaging work of Clifford Jack, M.D., in Rochester, patients may undergo magnetic resonance imaging (MRI) to examine brain structure, including changing volumes in white matter and hints of vascular damage; MR spectroscopy to assess chemical processing; functional MRI to look at the brain’s reaction to stimulus; positron emission tomography (PET) and glucose PET scanning to examine the functional aspects of performance; and the newest modality, amyloid imaging, which can provide a picture of amyloid deposition in the brain. Dr. Jack’s research has formed the basis of a $60 million, five-year grant, funded by a partnership of industry and the National Institute on Aging, to study these techniques nationwide, according to Dr. Petersen.

Through these studies, Dr. Petersen hopes doctors will be able to provide answers to those worried about developing Alzheimer’s disease — something no one has ever been able to do.

“Having a predictive equation will allow us to say, ‘You have a certain probability of developing Alzheimer’s,’” he says. “And if the probability is high, and if the therapy is risky or expensive, this information may help us determine how to intervene.”

Contact: Kevin Punsky
punsky.kevin@mayo.edu
904-953-0746
Mayo Clinic

Global Health Vision

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