Mostrando entradas con la etiqueta GENETICA. Mostrar todas las entradas
Mostrando entradas con la etiqueta GENETICA. Mostrar todas las entradas

jueves, 27 de febrero de 2014

Biomarked for Death—Four Blood Proteins Can Predict Early Demise

While you may appear to be healthy, you may be frailer than you know. You may even be at risk of death—from one disease or another—within the next five years. Would you want to know? You may now have the choice, thanks to researchers at the Estonian Genome Center and the Institute for Molecular Medicine, Finland.
These researchers have developed a screening technology. It looks for four biomarkers that have been associated with a risk of dying from any disease in the near future. Ordinarily, biomarkers are used to assess an individual’s risk of developing a specific condition. The new screening technology, however, is used to reveal general frailty, even in apparently healthy people. It reflects the risk for dying, whatever the ultimate cause—heart disease, cancer, or any other condition.
The biomarkers identified by the researchers are albumin, alpha-1-acid glycoprotein, citrate, and the size of very-low-density lipoprotein particles. Of these, albumin was the only one previously linked with mortality. All these molecules are normally present in everyone's blood—the amounts of these molecules are what matter. To assess the degree to which an individual’s biomarkers are imbalanced, the researchers found a way to compile a biomarker score.
The researchers found that individuals with a biomarker score in the top 20% had a risk of dying within five years that was 19 times greater than that of individuals with a score in the bottom 20% (288 versus 15 deaths). In addition, biomarker scores were still predictive of early death—that is, a death within the next five years—independent of well-known risk factors such as age, smoking, drinking, obesity, blood pressure, and cholesterol.
The researchers detailed their results February 25 in PLOS Medicine, in an article entitled “Biomarker Profiling by Nuclear Magnetic Resonance Spectroscopy for the Prediction of All-Cause Mortality: An Observational Study of 17,345 Persons.” To carry out their study, the researchers relied on technology that allowed them to screen blood samples for a wide range of blood biomarkers.
This technology, nuclear magnetic resonance (NMR) spectroscopy, screened for over 100 potential biomarkers in two cohorts of healthy people. The first cohort, investigated by Estonian members of the research team, consisted of 9,842 people. So astonished by what they found, the Estonian scientists asked their Finnish colleagues to repeat the experiment. The Finnish cohort, consisting of 7,503 people, produced the same result: Just four biomarkers are predictive of cardiovascular mortality, as well as death from cancer and other nonvascular diseases.
While the researchers emphasized that more studies would be needed before their findings could be implemented in clinical practice, they expressed optimism that their work could alert seemingly healthy people to the need for medical intervention. One of the study’s Finnish authors, Johnannes Kettunen, said, “We believe that in the future these measures can be used to identify people who appear healthy but in fact have serious underlying illnesses and guide them to proper treatment.”
In discussing their results, the authors of the PLOS Medicine story wrote, “In spite of [this study’s] limitations, the fact that the same four biomarkers are associated with a short-term risk of death from a variety of diseases does suggest that similar underlying mechanisms are taking place. This observation points to some potentially valuable areas of research to understand precisely what's contributing to the increased risk.”

Tomado de genengnews.com

sábado, 14 de septiembre de 2013

Researchers Extend Human Epigenomic Map

Ten years ago, scientists announced the end of the Human Genome Project, the international attempt to learn which combination of four nucleotides -- adenine, thymine, cytosine, and guanine -- is unique to Homo sapiens DNA. This biological alphabet helped researchers identify the approximately 25,000 genes coded in the human genome, but as time went on, questions arose about how all of these genes are controlled.
Now, Harvard Stem Cell Institute Principal Faculty member Alexander Meissner, PhD, reports another milestone, this time contributing to the multilayered NIH-funded human Roadmap Epigenomics Project. Epigenetics is the study of how the over 200 human cell types (e.g., muscle cells, nerve cells, liver cells, etc.) can have an identical complement of genes but express them differently. Part of the answer lies in the way that DNA is packaged, with tight areas silencing genes and open areas allowing for genes to be translated into proteins. Stem cells differentiate into various cell types by marking specific genes that will be open and closed after division.
New research by Meissner, published online as a letter in the journal Nature, describes the dynamics of DNA methylation across a wide range of human cell types. Chemically, these marks are the addition of a methyl group -- one carbon atom surrounded by three hydrogen atoms (CH3) -- anywhere a cytosine nucleotide sits next to a guanine nucleotide in the DNA sequence.
Meissner's team, led by graduate student Michael Ziller, at Harvard's Department of Stem Cell and Regenerative Biology mapped nearly all of the 28-million cytosine-guanine pairings among the 3-billion nucleotides that make up human DNA, and then wanted to know which of these 28 million are dynamic or static across all the cell types.
"When we asked, how many of them are changing, the answer was a very small fraction," said Meissner. The researchers found that eighty percent of the 28-million cytosine-guanine pairs are largely unchanged and might not participate in the regulation of the cell types, while the dynamic ones sit at sites that are relevant for gene expression -- in particular distal regulatory sites such as enhancers. "Importantly this allows us to improve our current approaches of mapping this important mark through more targeted strategies that still capture most of the dynamics," Meissner said.
The methylation map generated by the Meissner lab is part of a larger National Institutes of Health (NIH) consortium to look at all of the different epigenetic modification that are found across a large number of human cell and tissue types. Earlier this year, the Meissner's lab recorded all of the gene expression and multi-layered epigenetic dynamics that take place in early stem cell differentiation when they prepare to divide into their next fated cell type.
In addition to his roles at Harvard, Meissner is affiliated with the Broad Institute and the New York Stem Cell Foundation. Only a graduate student in 2007, he has quickly established himself as a leader in the epigenetics field. "It just happens to be that we're at the right time and at the right place, both physically and sort of in time, " he said. "Just five years ago, we would have had the same question, but we wouldn't have had the same tools to answer the question."
Harvard University. "Researchers extend human epigenomic map." ScienceDaily, 8 Aug. 2013. Web. 14 Sep. 2013.