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HIV Patients May Be at Risk of Heart Problems When Taking Protease Inhibitor Drugs

A widely-used class of drugs that keep the HIV-virus infection from progressing to AIDS may cause serious and potentially lethal heart rhythm disturbances in some patients. The finding of a Mayo Clinic-led investigation appears in the current edition of The Lancet. In collaboration with colleagues from the HIV Program of Hennepin County Medical Center, Minneapolis; the University of Minn...

To sea or not to sea: When it comes to salmon sex, size sometimes doesn't matter

The ones that stay and the ones that stray are biological puzzles among Pacific salmon, of whom the vast majority ?but not all ?travel thousands of miles to sea and back to the streams where they hatched. There are chinook salmon populations in Idaho in which an occasional male stays put and matures when only 6 inches long ?that is, he's able to fertilize eggs at even that diminutive size,...

Rhesus monkeys can assess the visual perspective of others when competing for food

Researchers Jonathan Flombaum and Dr. Laurie Santos, both from Yale University, have found that rhesus monkeys consider whether a competitor can or cannot see them when trying to steal food. Working with semi-free-ranging rhesus monkeys on the island of Cayo Santiago in Puerto Rico, Flombaum and Santos set up a food competition game: Lone monkeys were approached by two human "competitors....

Immune system's distress signal tells bacteria when to strike back

The human opportunistic pathogen, Pseudomonas aeruginosa, has broken the immune system's code, report researchers from the University of Chicago, enabling the bacteria to recognize when its host is most vulnerable and to launch an attack before the weakened host can muster its defenses. In the 29 July 2005 issue of Science, the researchers show how this lethal organism detects interferon-g...

When it comes to cell entry, being average has its advantages

When it comes to gaining entry into cells, size matters. A team from Brown University and the Max Planck Institute for Metals Research has created a model that explains how viruses and other bioparticles slip inside cells without a special protein coating called clathrin. The secret, it seems, is to be average. Mid-sized nanomaterials ?about 27 to 30 nanometers in diameter, or about 1,000...

Understanding biases in epidemic models important when making public health predictions

Mathematical models have become invaluable decision-making tools for public health officials. As demonstrated during the United Kingdom's foot-and-mouth epidemic of 2001, models can be useful in two ways: they can reveal the underlying characteristics of an infection and they can allow the comparison of alternative control measures. Often, however, such models make implicit assumptions that may s...

Bumblebees copy one another when contending with unfamiliar flowers

Researchers have reported findings that offer a surprising new twist to our understanding of how bumblebees, a vital floral pollinator, select the flowers from which they collect nectar. When faced with unfamiliar plants, foraging bees do not choose flowers entirely alone but instead copy the choices of other bees. The new findings suggest that bees adjust their behavior when dealing with flowers...

Researchers seek to discover what really happens when a virus enters the body

A well-respected researcher who is now a chief of an immunology laboratory of the National Institutes of Health (NIH) has rocked the boat in the past few years for the experts in the understanding of the autoimmune system. NIH's Polly Matzinger has developed the "danger model," suggesting that the immune system is more concerned with damage detected on the basis of a biological cell's deat...

When smell cells fail they call in stem cell reserves

Hopkins researchers have identified a backup supply of stem cells that can repair the most severe damage to the nerves responsible for our sense of smell. These reservists normally lie around and do nothing, but when neighboring cells die, the scientists say, the stem cells jump into action. A report on the discovery will appear online next week in Nature Neuroscience. “These stem cells a...

South Africa still debating how to tackle HIV/AIDS when 5 million are infected

A national conference in South Africa was dominated this week by the continuing debate over HIV/AIDS drugs. Health Minister Manto Tshabalala-Msimang repeated yet again that drugs were not the only way to fight HIV/AIDS, and that eating habits were also important. After previously denying links between HIV and AIDS, the South African government began providing AIDS drugs in clinics last ye...

When in danger humans are similar to a deer in the headlights

Standing still when a threat is detected is a defensive, protective reaction. This ancestral and automatic behavior allows the prey to stay unnoticed by a potential predator. A new study published in Psychophysiology finds that humans, like many other complex animals, freeze when encountering a threat. The mere picture of an injured or mutilated human induces this reaction. When viewing these unp...

Female butterflies go for sparkle -- not size -- when choosing to mate

Size doesn't matter, at least not the size of the eyespots on a male butterfly's wings when female butterflies consider potential mates. The research, to be published onli...

Researchers find gland that tells fruit flies when to stop growing

Many baffled parents have wondered whether their teenagers would ever stop growing. The answer is obvious, but researchers have never really quite understood just how an organism determines when it has reached its optimal size and growth should cease. Now University of Washington biologists studying the physiology of Drosophila melanogaster, the common fruit fly, have discovered an organ t...

Worms know bad food when they smell it

For most people, just a whiff of food that has made them sick in the past is enough to trigger a wave of nausea ?and to prevent them from eating that food again. It's a response that's instantaneous, involuntary, and so fundamental to basic biology that it occurs in a broad range of species. Even worms, researchers have now shown, quickly learn to avoid smells associated with foods that have made...

Watch your step when the going gets rough

Placing your foot accurately is a complicated process. If something moves where you plan to place your foot then you can adjust your step while your foot is swinging through. Experts thought previously that if nothing changed in the path, or in your plans, then the place where your foot will land is fixed before it even leaves the ground. In this case, you would make no use of immediate visual in...

Free HIV tests cheaper than charging when goal is preventing AIDS

Offering free HIV tests instead of charging a small fee is more cost-effective at preventing HIV infections and draws in three times as many people for testing, according to a Duke University Medical Center study conducted in Tanzania. The Duke researchers provided free HIV tests and counseling during a two-week pilot program in 2003. The number of people seeking tests increased from 4.1...

Experimental vaccine protects nonhuman primates when given after exposure to Marburg virus

Using multi-disciplinary analysis that included cognitive, neurophysiologic, virologic, and molecular techniques, the team found both a low-level viral infection in the brain and immune cells that had infiltrated the brain in order to protect against the virus. "As in the rest of the body, in the brain immune cells achieve a level of control of the virus, but are unable to clear the infec...

Male rivalry increases when females at most fertile, say researchers

Men become more jealous of dominant males when their female partner is near ovulation, researchers at the University of Liverpool have found. Previous studies have found that women's preferences for male physical appearance vary according to their fertility status. During ovulation women tend to find masculine looking men more attractive and prefer their voices and odour. During this fer...

When mice choose mates, experience counts

Choosing a mate is a big decision. And, at least for mice, it's one that is best made with input from one's peers. In a series of experiments designed help scientists understand the brain chemicals that guide mate selection, Pfaff and his colleagues exposed female mice to odors of either a male mouse alone or a male mouse with a female. The females consistently preferred the scent of males...

When good DNA goes bad

When otherwise normal DNA adopts an unusual shape called Z-DNA, it can lead to the kind of genetic instability associated with cancers such as leukemia and lymphoma, according to a study by researchers at The University of Texas M. D. Anderson Cancer Center. The study, issued in advance of the Feb. 21 edition of the Proceedings of the National Academy of Sciences, demonstrates for the fir...

Study: Paramedics save more lives when they don't follow the rules

Survival rates following the most common form of cardiac arrest increased three-fold when emergency medical personnel used a new form of CPR developed at The University of Arizona Sarver Heart Center. The new approach, called Cardiocerebral Resuscitation, is dramatically different from guideline-directed CPR procedures. Because of its importance, the editors of the American Journal of Med...

Poison dart frog mimics gain when birds learn to stay away

Studying neotropical poison dart frogs, biologists at the University of Texas at Austin uncovered a new way that the frog species can evolve to look similar, and it hinges on the way predators learn to avoid the toxic, brightly colored amphibians. In the Mar. 8 issue of Nature, Catherine Darst and Molly Cummings show that a harmless, colorful frog living in the Amazonian rainforest gets p...

Suicide risk does not increase when adults start using antidepressants, study finds

The risk of serious suicide attempts or death by suicide generally decreases in the weeks after patients start taking antidepressant medication, according to a new study led by Group Health Cooperative researchers and published in the January issue of The American Journal of Psychiatry. The study also found that the risk of suicidal behavior after starting 10 newer antidepressant medications is l...

Even fish don't swim well when they're young!

Do you remember learning to swim? Thrashing around, floundering, until suddenly it all clicks into place and a few feeble strokes of doggy-paddle propel you away from your parent's arms. Surely, you think, fish must be born as expert swimmers. Actually, fish larvae are pretty feeble when it comes to an efficient mode of swimming called 'burst-and-coast'. Dr Ulrike Müller from Wageningen Universit...

Many cleaners, air fresheners may pose health risks when used indoors

When used indoors under certain conditions, many common household cleaners and air fresheners emit toxic pollutants at levels that may lead to health risks, according to a new study by researchers at the University of California, Berkeley, and Lawrence Berkeley National Laboratory. Exposure levels to some of the pollutants ?and to the secondary pollutants formed when some of the products m...

For diseases, when it comes to sharing a home, only close relatives will do

Being more generous to close relatives is a common theme in both our daily interactions and our understanding of how organisms resolve conflicts in nature. In a paper from July issue of The American Naturalist, biologists Britt Koskella (Indiana University), Tatiana Giraud (Université Paris-Sud), and Michael Hood (University of Virginia) asked whether similar rules apply to disease-causing microb...

When the going gets tough, slime molds start synthesizing

In times of plenty, the uni-cellular slime mold Dictyostelium discoideum leads a solitary life munching on bacteria littering the forest floor. But these simple creatures can perform heroic developmental acts: when the bacterial food supply dries up, Dictyostelium amebas band together with their neighbors and form a multi-cellular tower designed to save the children. In a forthcoming stud...

Cultural transmission in bats: When listening for dinner, bats learn from their neighbors

In an exciting study that provides new understanding of how animals learn--and learn from each other--researchers have demonstrated that bats that use frog acoustic cues to find quality prey can rapidly learn these cues by observing other bats. While numerous examples are known of instances where predators can use so-called "social learning" to learn new visual and olfactory cues associated with...

Primates take weather into account when searching for fruits

New findings reported this week reveal that at least some primates can use their stored knowledge of recent weather as a tool for guiding their foraging behavior when searching for ripening fruit. The work, which potentially informs our understanding of how cognitive skills developed in humans and other primates, is reported by Karline Janmaat, Richard Byrne, and Klaus Zuberbühler of the Universi...

Even when faint, ovary scent draws sperm cells

In this week's Analytical Chemistry, scientists at Indiana University Bloomington report biochemical machinery that allows mouse sperm cells to follow the weakest of scents. Even when ovary extracts were diluted 100,000 times, some sperm cells still found their mark. A video demonstrating sperm chemotaxis (oriented motion in response to a chemical gradient) can be downloaded at <A HREF="h...

When it comes to gene transcription, random pauses aren’t quite so random, study finds

Of the thousands of proteins produced in our cells, few are as important as the enzyme RNA polymerase (RNAP), which has the unique ability to faithfully copy genetic information from DNA. In fact, all organisms--from bacteria to people--depend on RNAP to initiate the complex process of protein synthesis. Despite its crucial role in cell biology, fundamental questions remain about how the RNAP enz...

Plants tell caterpillars when it's safe to forage

The world is filled with cues that could influence the daily feeding patterns of an organism. Many plants, for example, respond to foraging damage by releasing specialized chemical signals - volatile organic compounds that evaporate in the air - that attract the forager's natural enemies. This strategy is obviously no use against a cow, but proves effective when the offender is a caterpillar and...

Female birds boost up their eggs when hearing sexy song

In a new study published in the latest issue of Ethology researchers show that female songbirds can alter the size of eggs and possibly the sex of their chicks according to how they perceive their mate's quality. The researchers played back attractive ("sexy") songs and less attractive control songs of male canaries to female domesticated canaries. When the females started egg-laying they...

When nerve cells can't make contact

Using an animal model, brain researchers in Göttingen have examined the effects of mutations that cause autism in humans. These are mutations in the genes which carry the building instructions for proteins in the neuroligin family. The study published in the scientific journal Neuron (September 21, 2006) shows that neuroligins ensure that signal transmission between nerve cells functions. In the...

Brain protein improves stroke symptoms in rats, even when injected after 3 days

A protein naturally occurring in the brain improves recovery from stroke when injected up to three days after the onset of the stroke, and could be used as an effective stroke drug. A study in rats published today in the open access journal BMC Biology shows that an injection of Granulocyte-Colony Stimulating Factor (G-CSF), whose function in the brain is to control the formation of neurons and c...

Stanford discovery may help predict when toxoplasma can be deadly

Toxoplasma is arguably the most successful animal parasite on earth: It infects hundreds of species of warm-blooded animals, most notably half of humanity. Its unusual ability to overcome the numerous challenges of infecting and reproducing inside such a wide range of creatures has long intrigued scientists, and now researchers at the Stanford University School of Medicine have identified t...

Researchers discover mechanism that determines when detailed memories are retained

The levels of a chemical released by the brain determine how detailed a memory will later be, according to researchers at UC Irvine. The neurotransmitter acetylcholine, a brain chemical already established as being crucial for learning and memory, appears to be the key to adding details to a memory. In a study with rats, Norman Weinberger, research professor of neurobiology and behavior, a...

For Pacific white shrimp, gender matters when competing for food

Waimanalo, HI ?December 12, 2006 -- A new study in Journal of the World Aquaculture Society suggests that, while larger shrimp consistently win over smaller shrimp of the same gender when competing for food, male shrimp will almost always beat female shrimp ?even though adult males of the species are typically much smaller than the adult females of the same age. "Both size and gender are i...

When the label says 'low fat,' calories can pile up, study says

People -- especially overweight people -- consume up to 50 percent more calories when they eat low-fat versions of snack foods than when they eat the regular versions, according to a new Cornell study. Further, a companion study finds, when food labels show serving sizes on such packaged low-fat snacks as granola or chocolates, normal-weight people tend not to overeat them while overweight...

Invasive ants territorial when neighbors are not kin

A study led by University of California, San Diego biologists shows that invasive Argentine ants appear to use genetic differences to distinguish friend from foe, a finding that helps to explain why these ants form enormous colonies in California. In the December issue of the journal Molecular Ecology, the biologists provide the first data on territorial interactions among Argentine ants...