Vital breakthroughs mark year of medical research

TWIN BENEFIT: Treating discordant couples with antiretroviral drugs provides double benefit - reducing the viral load in individual patients while simultaneously cutting transmission rates.

The journal Science has lauded an eye-opening HIV study, known as HPTN 052, as the most important scientific breakthrough of 2011.

This clinical trial demonstrated that people infected with HIV are 96 per cent less likely to transmit the virus to their partners if they take antiretroviral drugs (ARVs).

According to a release from Science, the findings end a long-standing debate over whether ARVs could provide a double benefit by treating the virus in individual patients while simultaneously cutting transmission rates.

It's now clear that the drugs can provide treatment as well as prevention when it comes to HIV, researchers agree.

About 1,800 heterosexual couples from nine different countries: Brazil, India, Thailand, the United States, Botswana, Kenya, Malawi, South Africa and Zimbabwe were enrolled for the study. Each participating couple included one partner with an HIV infection.

The researchers administered ARVs to half of those HIV-infected individuals immediately and waited for the other half of the infected participants to develop CD4 counts below 250 - indicative of severe immune damage - before offering treatment. (A CD4 count below 200 indicates AIDS.)

Then, earlier this year, four years before the study was officially scheduled to end, an independent monitoring board decided that all infected study participants should receive ARVs at once.

The board members had seen the dramatic effects of early ARV treatment on HIV transmission rates, and they recommended that the trial's findings be made public as soon as possible. The results were published on August 11 in the New England Journal of Medicine

"This [HPTN 052 trial] does not mean that treating people alone will end an epidemic," said Science news correspondent Jon Cohen, who wrote about the trial for Science's Breakthrough of the Year feature. "But, combined with three other major biomedical preventions that have proven their worth in large clinical studies since 2005, many researchers now believe it is possible to break the back of the epidemic in specific locales with the right package of interventions."

"Most everyone expected that reducing the amount of virus in a person would somewhat reduce infectiousness," explained Jon Cohen. "What was surprising was the magnitude of protection and then the impact the results had among HIV/AIDS researchers, advocates and policy-makers."

These findings have added important momentum to a movement, already underway, that promotes the ongoing treatment of HIV to reduce viral loads in communities and could possibly eliminate HIV/AIDS epidemics in some countries. But there are many problems in implementing it on a large-scale.

Still, some researchers consider HPTN 052 a "game-changer" because of its near-100 percent efficacy in reducing HIV transmission rates. And, indeed, it has already sprung many clinicians and policy-makers into action. For all these reasons, Science spotlights the HPTN 052 study as the 2011 Breakthrough of the Year.

Science's and its publisher, AAAS, the non-profit science society, have identified other groundbreaking scientific accomplishments during 2011.

Unraveling Human Origins: Studying the genetic code of both ancient and modern human beings, researchers discovered that many humans still carry DNA variants inherited from archaic humans, such as the mysterious Denisovans in Asia and still-unidentified ancestors in Africa.

One study this year revealed how archaic humans likely shaped our modern immune systems, and an analysis of Australopithecus sediba fossils in South Africa showed that the ancient hominin possessed both primitive and Homo-like traits.

Getting to Know the Microbiome: Research into the countless microbes that dwell in the human gut demonstrated that everyone has a dominant bacterium leading the gang in their digestive tract: Bacteroides, Prevotella or Ruminococcus. Follow-up studies revealed that one of these bacteria thrives on a high-protein diet while another prefers vegetarian fare.

These findings and more helped to clarify the interplay between diet and microbes in nutrition and disease.

A Promising Malaria Vaccine: Early results of the clinical trial of a malaria vaccine, known as RTS,S, provided a shot in the arm to malaria vaccine research.

The ongoing trial, which has enrolled more than 15,000 children from seven African countries, reassured malaria researchers, who are used to bitter disappointment, that discovering a malaria vaccine remains possible.

Clearing Senescent Cells: Experiments have revealed that clearing senescent cells (those that have stopped dividing) from the bodies of mice can delay the onset of age-related symptoms.

Mice whose bodies were cleared of these loitering cells didn't live longer than their untreated cage-mates - but they did seem to live better, which provided researchers with some hope that banishing senescent cells might also prolong our golden years.

Courtesy: The Hindu

How the brain merges sights and sounds

In order to get a better picture of our surroundings, the brain has to integrate information from different senses, but how does it know which signals to combine? New research involving scientists from the Max Planck Institute for Biological Cybernetics, University of Oxford, and the University of Bielefeld has demonstrated that humans exploit the correlation between the temporal structures of signals to decide which of them to combine and which to keep segregated.

Multisensory signals originating from the same distal event are often similar in nature. Think of fireworks on New Year's Eve, an object falling and bouncing on the floor, or the footsteps of a person walking down the street.

The temporal structures of such visual and auditory events are always almost overlapping (i.e., they correlate), and we often effortlessly assume an underlying unity between our visual and auditory experiences.

In fact, the similarity of temporal structure of multiple unisensory signals, rather than merely their temporal coincidence as it has been previously thought, provides a potentially powerful cue for the brain to determine whether or not multiple sensory signals have a common cause. Cesare Parise from the Max Planck Institute for Biological Cybernetics set out to examine the role of signal correlation in multisensory integration by asking people to localize a stream of beeps and flashes.

Participants seated in front of a large screen where sounds (streams of noise bursts) and images (streams blurred blobs) were presented from different spatial locations. On some trials only visual or auditory stimuli were presented, while on other trials visual and auditory stimuli were presented in combination.

Critically, on combined audiovisual trials, the temporal structure of the visual and auditory stimuli could either be correlated or not.

Participants were required to report the spatial position of such stimuli by moving a cursor controlled by a graphic tablet.

In line with previous studies, participants were more precise when the auditory and visual streams were presented together than when they were presented in isolation.

Notably, precision was even higher when auditory and visual streams were correlated, and closely approached the theoretical maximum.

These results demonstrate that humans optimally combine multiple sensory signals only when they correlate in time. Previous research has demonstrated that optimal integration only occurs when the brain is sure that the signals have a common underlying cause. These results therefore demonstrate that the brain uses the statistical correlation between the sensory signals to infer whether they have a common physical cause, and hence whether they provide redundant information that should be integrated.

The researchers suggest the brain has evolved this ability to combine potentially related information from different senses so it can effectively pick its way through the noisy environments of everyday life.

"It's why at a noisy cocktail party you can tell who is speaking with which voice," says Parise. "Our eyes and ears are continually taking in sensory information and our brains make sense of it all by merging together sights and sounds with similar temporal structures."

In spite of being a pervasive aspect of sensory processing, little is known about the low-level statistical determinants of multisensory integration for signals with complex dynamic temporal patterns.

This research highlights the role of a key organizational principle for multisensory perceptual grouping. What at first glance appears to be a logical fallacy, namely inferring causation from correlation, turns out to be the rule in perception.

- Healthnews

Shedding new light on medicinal benefits of plants

Scientists from institutions around the world have collaborated to develop new resources poised to unlock yet another door in the hidden garden of medicinally important compounds found in plants. The resources were developed by the Medicinal Plant Consortium (MPC) led by Joe Chappell, Dean DellaPenna and Sarah O'Connor. They grew out of a $6 million initiative from the National Institutes of Health (NIH) to study how plants produce the rich diversity of chemical compounds, some of which are medicinally important.

"Our major goal in this project has been to capture the genetic blueprints of medicinal plants for the advancement of drug discovery and development," said Chappell, project coordinator for the MPC. "Most people are familiar with the natural products we derive from plants," Chappell added.

"These include the delightful fragrances that go into perfumes, soaps, household cleaning products and more. Just as the sensory properties of plants interact with and trigger your sense of smell, plants' natural compounds can target and cause a reaction within your body. This gives them tremendous pharmaceutical potential." The MPC project includes participants from Michigan State, Iowa State University, the University of Mississippi, Purdue University, Texas A&M University, MIT, and the John Innes Centre, in addition to UK.

The associated researchers represent a broad spectrum of expertise from plant biology and systematics to analytical chemistry, genetics and molecular biology, and drug development from natural products. Some well-known medicines have come from plants. For instance, the foxglove plant gives us the cardiac muscle stimulant digoxin, and the periwinkle plant offers a source for the widely used chemotherapy drugs vincristine and vinblastine. These and many other medicinal plants, often commonly found in household gardens and flower boxes, represent cornucopias of compounds ripe for discovering and developing diverse medicinal applications. "The current understanding of the molecules and genes involved in the formation of plant-derived medicinal compounds is very incomplete.

However, the ability to conduct genome-wide studies of model plant species has resulted in an explosive increase in our knowledge of and capacity to understand the biological processes," added O'Connor, also an MPC co-project coordinator. During this two-year project researchers from two consortia set out to develop a collection of data that would aid in understanding how plants make chemicals, a process called biosynthesis. This knowledge ultimately could make it possible to engineer plants to produce larger quantities of medicinally useful compounds as well as different versions with other therapeutic potential.

To develop the resources, the researchers studied the genes and chemical composition of 14 plants known for their medicinal properties or compounds with biological activity. These included plants such as foxglove, ginseng, and periwinkle. Altogether, these efforts are now providing a rich toolbox for researchers to discover the means for how nature's chemical diversity is created, thus empowering efforts to uncover new drug candidates and increase the efficacy of existing ones.

The work of the MPC included obtaining materials for all the medicinal plants used in this study. The MPC then determined the plants' chemical profiles and obtained their genetic blueprints to study how genes control the various chemical compositions. "This work offers a valuable data resource for understanding the genes, enzymes and complex processes responsible for the biosynthesis of important plant-derived drugs," said Warren Jones, who manages this and other research grants in biotechnology at NIH's National Institute of General Medical Sciences, through which the ARRA funds were provided. "The collaborative effort should greatly contribute to our ability to understand and exploit the rich biochemistry found in plants."

- MediLexicon

Diet patterns may keep brain from shrinking

People with diets high in several vitamins or in omega 3 fatty acids are less likely to have the brain shrinkage associated with Alzheimer's disease than people whose diets are not high in those nutrients, according to a new study published in a medical journal on Neurology.

Those with diets high in omega 3 fatty acids and in vitamins C, D, E and the B vitamins also had higher scores on mental thinking tests than people with diets low in those nutrients. These omega 3 fatty acids and vitamin D are primarily found in fish.

The B vitamins and antioxidants C and E are primarily found in fruits and vegetables.In another finding, the study showed that people with diets high in trans fats were more likely to have brain shrinkage and lower scores on the thinking and memory tests than people with diets low in trans fats. Trans fats are primarily found in packaged, fast, fried and frozen food, baked foods and margarine spreads.The study involved 104 people with an average age of 87 and very few risk factors for memory and thinking problems. Blood tests were used to determine the levels of various nutrients present in the blood of each participant.

All of the participants also took tests of their memory and thinking skills. A total of 42 of the participants had MRI scans to measure their brain volume.Overall, the participants had good nutritional status, but seven percent were deficient in vitamin B12 and 25 percent were deficient in vitamin D.Study author Gene Bowman, of Oregon Health & Science University in Portland said that the nutrient biomarkers in the blood accounted for a significant amount of the variation in both brain volume and thinking and memory scores.

For the thinking and memory scores, the nutrient biomarkers accounted for 17 percent of the variation in the scores.

Other factors such as age, number of years of education and high blood pressure accounted for 46 percent of the variation. For brain volume, the nutrient biomarkers accounted for 37 percent of the variation."These results need to be confirmed, but obviously it is very exciting to think that people could potentially stop their brains from shrinking and keep them sharp by adjusting their diet," Bowman said.The study was the first to use nutrient biomarkers in the blood to analyze the effect of diet on memory and thinking skills and brain volume. Previous studies have looked at only one or a few nutrients at a time or have used questionnaires to assess people's diet.

But questionnaires rely on people's memory of their diet, and they also do not account for how much of the nutrients are absorbed by the body, which can be an issue in the elderly.

- MNT

Why some older people lose their memory

New research links 'silent strokes,' or small spots of dead brain cells, found in about one out of four older adults to memory loss in the elderly.

"The new aspect of this study of memory loss in the elderly is that it examines silent strokes and hippocampal shrinkage simultaneously," said study author Adam M. Brickman, of the Taub Institute for Research on Alzheimer's Disease and the Aging Brain at Columbia University.

For the study, a group of 658 people ages 65 and older and free of dementia were given MRI brain scans. Participants also underwent tests that measured their memory, language, speed at processing information and visual perception.

A total of 174 of the participants had silent strokes.The study found people with silent strokes scored somewhat worse on memory tests than those without silent strokes. This was true whether or not people had a small hippocampus, which is the memory center of the brain."

Given that conditions like Alzheimer's disease are defined mainly by memory problems, our results may lead to further insight into what causes symptoms and the development of new interventions for prevention.

Since silent strokes and the volume of the hippocampus appeared to be associated with memory loss separately in our study, our results also support stroke prevention as a means for staving off memory problems," said Brickman.

- Sciencedaily.com