August 10, 2006, 6:47 AM CT

Genetics Of Successful Aging

Researchers have identified genes correlation to reaching age 90 with preserved cognition, as per a research studyreported in the recent issue of the American Journal of Geriatric Psychiatry. The study, which was conducted at the University of Pittsburgh is among the first to identify genetic links to cognitive longevity.

"Successful aging has been defined in a number of ways, however, we focused on individuals who had reached at least 90 without significant decline in mental capacity," said lead researcher George S. Zubenko, M.D., Ph.D., professor of psychiatry and biological sciences at the University of Pittsburgh. "While this is a goal that a number of of us share, such a definition of 'successful aging' can be determined objectively and consistently across subjects--an important requirement of scientific studies."

While prior research has revealed that genes make important contributions to exceptional longevity, the goal of this study was to identify regions of the human genome that contributed, along with lifestyle factors, to reaching age 90 with preserved cognition.

The study involved 100 people age 90 and older who had preserved cognition as measured by clinical and psychometric assessments. Half of the subjects were male, half were female. Using a novel genome survey method, researchers compared the DNA of the study sample with that of 100 young adults, aged 18-25, who were matched for sex, race, ethnicity and geographic location. Particularly, Dr. Zubenko and his research team attempted to identify specific genetic sequences present in older individuals that may be associated with reaching older ages with preserved cognitive abilities, or on the other hand, specific genetic sequences present in younger individuals (and not present in those over age 90) that may impede successful aging. The study also looked at a variety of lifestyle factors, such as smoking and alcohol consumption, with the goal of eventually exploring the interactive effects of genes and lifestyle on successful aging.........

Posted by: Daniel      Permalink         Source

August 9, 2006, 11:22 PM CT

Blocking Human HIV Transmissions

As primates evolved 7 million years ago, the more advanced species stopped making a protein that University of Central Florida scientists believe can effectively block the HIV-1 virus from entering and infecting blood cells.

HIV-1 often mutates quickly to overcome antiviral compounds designed to prevent infections. But a research team led by Associate Professor Alexander Cole of UCF's Burnett College of Biomedical Sciences has demonstrated that over 100 days the virus develops only weak resistance to retrocyclin, a defense peptide still found in monkeys and lower primates.

If additional laboratory tests demonstrate only weak resistance, Cole will study how retrocyclin could be developed into a drug designed to prevent the HIV virus from entering human cells.

Cole is also working with Henry Daniell, a UCF professor of molecular biology and microbiology, to develop a way to grow retrocyclin through genetically engineered tobacco plants. The retrocyclin gene would be incorporated into the chloroplast genome of tobacco cells before the plants grow. Daniell has developed a similar approach to growing anthrax vaccine in tobacco plants.

An inexpensive way to produce the drug with only a small amount of tobacco would help to make it accessible in areas such as Southeast Asia, Africa and the Caribbean where the disease spreads most quickly.........

Posted by: Mark      Permalink         Source

August 8, 2006, 9:36 PM CT

Exploring Alzheimer's Causes

Some people live to be 100 without falling victim to Alzheimer's disease. Li-Huei Tsai, who joined MIT this spring as Picower Professor of Neuroscience, wants to know why.

Amyloid beta or Abeta (a protein fragment that accumulates in the brains of Alzheimer's patients) is a telltale sign of the disease, which affects 4 million Americans, most over age 65. Normally, the body manages to break down and eliminate these fragments, but in the aging brain, they tend to form insoluble plaques.

To add to the mystery, some people function relatively normally with plaques nestled among their neurons, while others are virtually incapacitated. "There are people with a significant plaque load who can keep up with their daily lives," said Tsai, who has appointments in the Department of Brain and Cognitive Sciences and at the Picower Institute for Learning and Memory. "Obviously, other factors are determining whether they have full-blown Alzheimer's."

Tsai, who as a child in Taipei witnessed her beloved grandmother's descent into dementia, is determined to unravel the thorny questions linked to neurodegenerative and psychiatric disorders.

Tsai uses a combination of molecular, cellular and biochemical approaches to study Alzheimer's disease and psychiatric and developmental disorders. She focuses on a kinase (kinases are enzymes that change proteins) called Cdk5. Cdk5, paired with the protein p35, helps new neurons form and migrate to their correct positions during brain development. But Cdk5, paired with an aberrant form of p35 called p25, also is implicated in age-related neurodegenerative diseases.........

Posted by: Daniel      Permalink         Source

August 7, 2006, 11:58 PM CT

Best Memorization Strategies

Exploring exactly why some individuals' memory skills are better than others has led researchers at Washington University in St. Louis to study the brain basis of learning strategies that healthy young adults select to help them memorize a series of objects. Using functional magnetic resonance imaging (fMRI), the researchers uncovered brain regions specifically correlated with the diverse strategies that subjects adopt.

Brenda Kirchhoff, research associate in psychology in the University's School of Arts and Sciences, conducted this study in the then-Washington University lab of Randy L. Buckner, now a professor of psychology at Harvard University and investigator at the Howard Hughes Medical Institute. Their findings have been published in the July 20, 2006, issue of Neuron. (Kirchhoff is the article's first author and Buckner is senior author.).

"Randy and I were interested in exploring individual differences in memory - why some people are better at learning new information than others," said Kirchhoff. "Our main goal was to determine the learning strategies that people use and their relationship to memory performance. Secondly, we wanted to know if individual differences in learning strategies were associated with individual differences in brain activity".........

Posted by: Daniel      Permalink         Source

August 7, 2006, 11:39 PM CT

Surprise Finding For Stretched DNA

Most of us are familiar with the winding staircase image of DNA, the repository of a biological cell's genetic information. But few of us realize just how tightly that famous double helix is wound. Stretched to its full length, a single molecule of human DNA extends more than three feet, but, when wound up inside the nucleus of a cell, that same molecule measures about one millionth of an inch across. Biologists have long believed that as a molecule of DNA is stretched, its double helix starts to unwind. As much sense as this makes from an intuitive standpoint, a recent experiment proved it not to be the case.

Scientists with the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California at Berkeley used a combination of microscopic beads and magnetic tweezers to observe that when a DNA molecule is stretched, it actually begins to overwind. This overwinding continues until the force being applied to stretch the DNA exceeds about 30 picoNewtons. (One picoNewton is about a trillionth the force mandatory to hold an apple against Earth's gravity.) Beyond the 30 picoNewton threshold, the DNA double helix did begin to unwind in accordance with predictions.

"DNA's helical structure implies that twisting and stretching should be coupled, hence the prediction that DNA should unwind when stretched," said biophysicist Carlos Bustamante, who led this experiment. "That is why it was such surprise when we directly measured twist-stretch coupling to find instead DNA overwinds when stretched. The DNA molecule, when studied at close range, continues to surprise us!".........

Posted by: Scott      Permalink         Source

August 4, 2006, 0:05 AM CT

Links between DNA damage and breast cancer

Scientists from the Pacific Northwest Research Institute (PNRI) and the National Institute of Standards and Technology (NIST) have uncovered a pattern of DNA damage in connective tissues in the human breast that could shed light on the early stages of breast cancer and possibly serve as an early warning of a heightened risk of cancer.

In the United States, breast cancer is the second leading cause of cancer-related death in women. Breast cancer detection and treatment generally target epithelial cells, the primary locus of breast cancers, but in recent years evidence has accumulated that genetic mutations that develop into cancer may occur initially in a deeper layer of breast tissue, called the stroma. Genetic changes in this connective tissue that supports the breast's network of glands and ducts have been reported to precede the cancerous conversion of tumor cells, but the actual role of stromal cells in the early stages of breast cancer initiation and progression is not well understood.

In two recent papers*, the PNRI/NIST team explored the occurrence of damage to stromal DNA caused by free radicals and other oxidants. NIST scientists used a high-precision chemical analysis technique (liquid chromatography/mass spectrometry with isotope dilution) to identify specific DNA lesions, while the PNRI team used a spectroscopic technique (Fourier transform-infrared spectroscopy) to reveal subtle conformational changes to DNA base and backbone structures. Such alterations to the molecular structure can change or disrupt gene expression.........

Posted by: Janet      Permalink         Source

August 3, 2006, 11:58 PM CT

Race Affects Type 2 Diabetes Treatment

African Americans may be less likely than whites to take their medicine for Type 2 diabetes as it is prescribed, a new study suggests.

The scientists observed that adherence rates were as much as 12 percent lower among black people when in comparison to whites.

"That's an unacceptable difference, especially because African Americans tend to have higher rates of diabetes and disease-related complications," said Rajesh Balkrishnan, a co-author of study and the Merrell Dow professor of pharmacy at Ohio State University.

Each of the nearly 2,700 study participants were covered by Medicaid, which provided prescription medicine coverage to all enrollees. Still, more than a third of the African Americans and whites in this study failed to take their anti-diabetic medications properly.

"Adherence rates for these types of medications should be better than 90 percent, regardless of who takes them," Balkrishnan said. "Such low rates of adherence may be correlation to lower socioeconomic status and to lower levels of education.

"A number of commercial insurers pay for educators to teach patients the importance of taking their medications as prescribed," he continued. "Medicaid needs to do the same thing. While it invests a lot of money in providing services, it does little to educate its recipients about those services and how to use them. People need to understand the importance of taking their medications".........

Posted by: JoAnn      Permalink         Source

August 3, 2006, 11:49 PM CT

Protector Of DNA, Enemy Of Tumors

A single gene plays a pivotal role launching two DNA damage detection and repair pathways in the human genome, suggesting that it functions as a previously unidentified tumor suppressor gene, scientists at The University of Texas M. D. Anderson Cancer Center report in Cancer Cell.

The advance online publication also reports that the gene - called BRIT1 - is under-expressed in human ovarian, breast and prostate cancer cell lines.

Defects in BRIT1 seem to be a key pathological alteration in cancer initiation and progression, the authors note, and further understanding of its function may contribute to novel, therapeutic approaches to cancer.

"Disruption of BRIT1 function abolishes DNA damage responses and leads to genomic instability," said senior author Shiaw-Yih Lin, Ph.D., assistant professor in the Department of Molecular Therapeutics at M. D. Anderson. Genomic instability fuels the initiation, growth and spread of cancer.

A signaling network of molecular checkpoint pathways protects the human genome by detecting DNA damage, initiating repair and halting division of the damaged cell so that it does not replicate.

In a series of laboratory experiments, Lin and his colleagues show that BRIT1 activates two of these checkpoint pathways. The ATM pathway springs into action in response to damage caused by ionizing radiation. The ATR pathway responds to DNA damage caused by ultraviolet radiation.........

Posted by: Janet      Permalink         Source

August 2, 2006, 11:53 PM CT

Key Fat And Cholesterol Cell Regulator

Boston, MA -- Scientists at Harvard Medical School and Massachusetts General Hospital have identified how a molecular switch regulates fat and cholesterol production, a step that may help advance therapys for metabolic syndrome, the constellation of diseases that includes high cholesterol, obesity, type II diabetes, and high blood pressure. The study is now reported in the online version of the scientific journal Nature and will appear in the August 10th print edition.

"We have identified a key protein that acts together with a family of molecular switches to turn on cholesterol and fat (or lipid) production," says principal investigator Anders Nr, PhD, assistant professor of cell biology at Harvard Medical School and the Massachusetts General Hospital Cancer Center. "The identification of this protein interaction and the nature of the molecular interface may one day allow us to pursue a more comprehensive approach to the therapy of metabolic syndrome".

High levels of cholesterol and lipids are associated with many interrelated medical conditions and diseases, including obesity, type II diabetes, fatty liver, and high blood pressure. This set of conditions and diseases, known as metabolic syndrome, are afflicting a rapidly increasing portion of society and serve as a major risk factor for heart disease, the leading cause of death in the developed world.........

Posted by: Daniel      Permalink         Source

August 2, 2006, 11:40 PM CT

CT Images Faster Than Traditional Scanners

Researchers at the University of North Carolina at Chapel Hill have developed a new method to create computed tomography (CT) images using carbon nanotube x-rays that works much faster than traditional scanners and uses less peak power.

The work is another step toward developing scanners for medical imaging and homeland security that are smaller, faster, and less expensive to operate, said Dr. Otto Zhou, Lyle Jones Distinguished Professor of Materials Science, in the curriculum in applied and materials sciences and the department of physics and astronomy, both in UNC's College of Arts and Sciences.

"The current Computerized axial tomography scanners take images sequentially, which is slow and inefficient. Using the nanotube x-ray technology, we show in this paper the feasibility of multiplexing - taking multiple images at the same time," Zhou said.

Carbon nanotubes, made of layers of carbon atoms, can be as small as one nanometer - one billionth of a meter - in diameter. The UNC team uses them in this work because they can emit electrons without high heat.

The new development is reported in the current edition of the journal Applied Physics Letters. The lead author of the paper is Dr. Jian Zhang, a postdoctoral research associate in the UNC School of Medicine's department of radiation oncology. In addition to Zhou, other authors - all from UNC - are Dr. Sha Chang, associate professor of radiation oncology; doctoral candidate Guan Yang and Dr. Jianping Lu, professor of condensed matter physics, both of the department of physics and astronomy; and Dr. Yueh Lee, an intern at the medical school and an adjunct assistant professor in physics and astronomy.........

Posted by: Sue      Permalink         Source