Archive for the ‘Dr. Rajadhyaksha’ Category

By Sarah C. P. Williams

There’s a reason people say “Calm down or you’re going to have a heart attack.” Chronic stress—such as that brought on by job, money, or relationship troubles—is suspected to increase the risk of a heart attack. Now, researchers studying harried medical residents and harassed rodents have offered an explanation for how, at a physiological level, long-term stress can endanger the cardiovascular system. It revolves around immune cells that circulate in the blood, they propose.

The new finding is “surprising,” says physician and atherosclerosis researcher Alan Tall of Columbia University, who was not involved in the new study. “The idea has been out there that chronic psychosocial stress is associated with increased cardiovascular disease in humans, but what’s been lacking is a mechanism,” he notes.

Epidemiological studies have shown that people who face many stressors—from those who survive natural disasters to those who work long hours—are more likely to develop atherosclerosis, the accumulation of fatty plaques inside blood vessels. In addition to fats and cholesterols, the plaques contain monocytes and neutrophils, immune cells that cause inflammation in the walls of blood vessels. And when the plaques break loose from the walls where they’re lodged, they can cause more extreme blockages elsewhere—leading to a stroke or heart attack.

Studying the effect of stressful intensive care unit (ICU) shifts on medical residents, biologist Matthias Nahrendorf of Harvard Medical School in Boston recently found that blood samples taken when the doctors were most stressed out had the highest levels of neutrophils and monocytes. To probe whether these white blood cells, or leukocytes, are the missing link between stress and atherosclerosis, he and his colleagues turned to experiments on mice.

Nahrendorf’s team exposed mice for up to 6 weeks to stressful situations, including tilting their cages, rapidly alternating light with darkness, or regularly switching the mice between isolation and crowded quarters. Compared with control mice, the stressed mice—like stressed doctors—had increased levels of neutrophils and monocytes in their blood.

The researchers then homed in on an explanation for the higher levels of immune cells. They already knew that chronic stress increases blood concentrations of the hormone noradrenaline; noradrenaline, Nahrendorf discovered, binds to a cell surface receptor protein called β3 on stem cells in the bone marrow. In turn, the chemical environment of the bone marrow changes and there’s an increase in the activity of the white blood cells produced by the stem cells.

“It makes sense that stress wakes up these immune cells because an enlarged production of leukocytes prepares you for danger, such as in a fight, where you might be injured,” Nahrendorf says. “But chronic stress is a different story—there’s no wound to heal and no infection.”

In mice living with chronic stress, Nahrendorf’s team reported today in Nature Medicine, atherosclerotic plaques more closely resemble plaques known to be most at risk of rupturing and causing a heart attack or stroke. When the scientists blocked the β3 receptor, though, stressed mice not only had fewer of these dangerous plaques, but also had reduced levels of the active immune cells in their plaques, pinpointing β3 as a key link between stress and atheroscelerosis.

The finding could lead to new drugs to help prevent cardiovascular disease, suggests biologist Lynn Hedrick of the La Jolla Institute for Allergy and Immunology in San Diego, California. “I think this gives us a really direct hint that the β3 receptor is important in regulating the stress-induced response by the bone marrow,” Hedrick says. “If we can develop a drug that targets the receptor, this may be very clinically relevant.”

More immediately, the new observations suggest a way that clinicians could screen patients for their risk of atherosclerosis, heart attack, and stroke, Tall says. “Rather than asking four questions about stress levels, we could use their white blood cell counts to monitor psychosocial stress,” he says.

Thanks to Dr. Rajadhyaksha for bringing this to the attention of the It’s Interesting community.

http://news.sciencemag.org/biology/2014/06/how-stress-can-clog-your-arteries

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Some guys have trouble remembering just what happened during their bachelor party, but a group of men on a recent stag send-off in New Mexico aren’t likely to forget their celebration very soon — since they stumbled upon a perfectly preserved three-million-year-old mastodon skull.

The party was on a hike in Elephant Butte Lake State Park near Albuquerque when they saw a bone jutting one to two inches from the sand. They started digging and uncovered the enormous skull. Their first thought was it could be the remains of a woolly mammoth so they snapped photos and sent them to the New Mexico Museum of Natural History and Science.

Scientists there made the identification — it wasn’t a woolly mammoth, but, in fact, a much more exciting find. The skull belonged to a stegomastodon — a prehistoric ancestor of the woolly mammoth — as well as today’s elephants. The massive animal stood about 9 feet tall, weighed six tons and walked the Earth during the Ice Age, according to Gary Morgan, a paleontologist at the museum who analyzed the fossil. He estimates the animal was about 50 years old when it died on a sandbar of the ancient Rio Grande River.

The family of mastodons migrated to North America around 15 million years ago and died out around 10,000 years ago.

“This is far and away the best one we’ve ever found,” said Morgan about the bachelor party’s discovery.

Scientists, following up on the party’s tip, went to the site and sealed the skull, which weighed more than 1,000 pounds, in a cast. It was transported to the museum, where it will eventually will be placed on display.

Antonia Gradillas, 33, was among the men who made the original discovery. He said, “This is the coolest thing ever. Some people with PhDs in this field might not even have this kind of opportunity. We were so lucky.”

Thanks to Dr. Rajadhyaksha for bringing this to the attention of the It’s Interesting community.

http://news.discovery.com/animals/paleontology/bachelor-party-finds-mastedon-skull-140616.htm

Dwarf spiders don’t need to take paternity tests to know who the father is—for the most part. Right after copulation, males plug up the genital tract of females (red box in picture) to ensure that competitors can’t deposit sperm. Researchers studying the technique found that the larger the plug, the more difficult it is for subsequent males to remove. Described this month in Behavioral Ecology and Sociobiology, the “stoppers” effectively prevent 67.5% of males who show up later from breeding.

Thanks to Dr. Rajadhyaksha for bringing this to the attention of the It’s Interesting community.

http://news.sciencemag.org/sifter/2014/06/how-male-spiders-keep-females-to-themselves

by Rebecca Cooper

Brewers have pulled yeast from pretty much everywhere to experiment with new strains — one West Coast brewery even brewed a beer using samples from the head brewer’s beard (http://www.huffingtonpost.com/2012/09/26/beard-beer-rogue-ales-yeast-john-maier_n_1917119.html) — but Lost Rhino in Ashburn may be breaking into new territory with its BoneDusters amber ale.

BoneDusters was brewed with a yeast that Lost Rhino’s Jasper Akerboom collected off a fossilized whale skeleton at the Calvert Marine Museum in Solomons, Maryland.

The collaboration came about because Akerboom, a bit of a yeast nut who handles quality assurance for Lost Rhino, is friends with Jason Osborne, a paleontologist who has donated fossilized whale skeletons to the museum.

Osborne asked Akerboom if there might be yeast present on those fossils that could be used to brew beer. Usually, yeast would not live on bone, given that it needs a sugary food source, but Akerboom decided to indulge his friend anyway.

They found a number of yeast strains on the bones, although Akerboom is pretty sure they’re more likely from the swamp where the bones were found rather than the bones themselves.

Several of the wild yeast strains flourished in Akerboom’s lab, but only one of the strains made any decent beer. The others didn’t ferment fully, making for “nasty-tasting” brews, he said.

The strain they ended up using, combined with some darker malts to create an amber ale, have yielded what Akerboom considers a tasty, well-balanced brew. The beer wasn’t made in the Belgian style, but it is “Belgian-esque,” he said, because the yeast has a slightly fruity flavor profile common in Belgian beers.

Lost Rhino plans to launch the beer June 18 at the brewery and begin distributing it to its networks after that, so it could be appearing at D.C. area bars in the next couple of weeks. A portion of the proceeds from the beer will go to Osborne’s nonprofit, Paleo Quest, which runs educational programs in the sciences.

For his part, Akerboom will keep experimenting with yeast in the lab he runs at Lost Rhino. It’s not necessarily common for a small microbrewery to have a quality assurance scientist with a Ph.D. in microbiology on staff. The Netherlands native previously isolated wild yeast from the air in Ashburn for Wild Farmwell Wheat, an “All-Virginia” beer Lost Rhino made in 2012. He now runs a yeast business on the side, and believes that focus on quality control is a big part of Lost Rhino’s consistently good beers.

“I think it adds a lot to the brewery. You have to make sure what you put in those cans is actually clean,” he said. “And you can do these kinds of projects, which keeps it fun.”

Thanks to Dr. Rajadhyaksha for bringing this to the attention of the It’s Interesting community.

http://www.bizjournals.com/washington/blog/top-shelf/2014/06/whats-the-key-ingredient-in-lost-rhino-s-newest.html?page=2

A high-tech helmet has reduced symptoms of depression in two-thirds of people who’ve worn it, BBC reports. Now undergoing clinical trials, the hood works by sending electromagnetic impulses to the brain to activate the formation of new blood vessels. Patients who wear the device daily for half an hour to an hour show mood improvement in as little as week, according to the results, published in Acta Neuropsychiatrica.

Thanks to Dr. Rajadhyaksha for bringing this to the attention of the It’s Interesting community.

http://news.sciencemag.org/sifter/2014/05/watch-electromagnetic-helmet-treats-depression

When you’re trying to track a fish in the murky ocean, forget about using your eyes—use your ears. Dolphins, orcas, and other toothed whales—known as odontocetes—pinpoint their prey by producing high-frequency sounds that bounce around their marine environment and reveal exactly where tricky fish are trying to hide. But when did whales evolve this sonarlike ability, known as echolocation? A newly named, 28-million-year-old whale may hold the answer.

Found in South Carolina among rocks dating back to the Oligocene epoch and christened Cotylocara macei, the fossil whale is named after Mace Brown, a curator at the College of Charleston’s Mace Brown Natural History Museum in South Carolina who acquired the specimen for his private collection about a decade ago. It was in that private accumulation of fossils that Jonathan Geisler, a paleontologist at the New York Institute of Technology College of Osteopathic Medicine in Old Westbury, first saw the skull. “I knew it was special then,” he says.

The only known specimen of the early odontocete includes a nearly complete skull and jaw, three neck vertebrae, and fragments of seven ribs. It’s the skull that makes Cotylocara so remarkable. While the whale’s soft tissue rotted away long ago, the skull bones show several features—such as a downturned snout and a slight asymmetry of the skull—that suggest Cotylocara was one of the earliest whales to use echolocation, Geisler’s team reports online today in Nature.

The strongest pieces of evidence for this hypothesis, Geisler explains, are cavities at the base of the snout and on top of the skull that probably held air sinuses. “These air sinuses are thought to have important roles in the production of high-frequency vocalizations that living odontocetes use for echolocation,” Geisler says, possibly helping direct returning sound waves or store air that can be used to make continuous sound.

“I think the authors have a good case for inferring that Cotylocara had some ability to produce some sound from its forehead, just as living toothed whales do today,” says Nicholas Pyenson, a marine mammal paleontologist at the Smithsonian Institution’s National Museum of Natural History in Washington, D.C. But even if Cotylocara made those sounds, could it have heard them? Living whales have specialized ear bones that let them hear the high-frequency sounds bouncing off their prey. The only known skull of Cotylocara doesn’t have well-preserved ear bones, and, therefore, knowing whether the whale could have actually used echolocation for hunting is unclear. “Overall, the description of Cotylocara underscores the need to investigate the inner ear of fossil Oligocene cetaceans in much more detail, because that’s where the answer will be,” Pyenson says.

Nevertheless, the whale’s probable sound-producing abilities give Cotylocara an important place in whale evolution. Whale’s biological sonar is thought to have evolved only once along the ancestral line leading to today’s toothed whales, Geisler notes. Cotylocara lies along that evolutionary stem, as do other Oligocene fossil whales that have already been found. The skull features that allowed Cotylocara to create sound, Geisler says, “can now be investigated in other fossil whales to more fully understand the evolution of echolocation.” For now, the evolutionary epic of whale echolocation is only just beginning to be heard.

http://news.sciencemag.org/paleontology/2014/03/fossil-whale-offers-clues-origins-seeing-sound

Thanks to Dr. Rajadhyaksha for bringing this to the attention of the It’s Interesting community.

Tastes are a privilege. The oral sensations not only satisfy foodies, but also on a primal level, protect animals from toxic substances. Yet cetaceans—whales and dolphins—may lack this crucial ability, according to a new study. Mutations in a cetacean ancestor obliterated their basic machinery for four of the five primary tastes, making them the first group of mammals to have lost the majority of this sensory system.

The five primary tastes are sweet, bitter, umami (savory), sour, and salty. These flavors are recognized by taste receptors—proteins that coat neurons embedded in the tongue. For the most part, taste receptor genes present across all vertebrates.

Except, it seems, cetaceans. Researchers uncovered a massive loss of taste receptors in these animals by screening the genomes of 15 species. The investigation spanned the two major lineages of cetaceans: Krill-loving baleen whales—such as bowheads and minkes—were surveyed along with those with teeth, like bottlenose dolphins and sperm whales.

The taste genes weren’t gone per se, but were irreparably damaged by mutations, the team reports online this month in Genome Biology and Evolution. Genes encode proteins, which in turn execute certain functions in cells. Certain errors in the code can derail protein production—at which point the gene becomes a “pseudogene” or a lingering shell of a trait forgotten. Identical pseudogene corpses were discovered across the different cetacean species for sweet, bitter, umami, and sour taste receptors. Salty tastes were the only exception.

“The loss of bitter taste is a complete surprise, because natural toxins typically taste bitter,” says zoologist Huabin Zhao of Wuhan University in China who led the study. All whales likely descend from raccoon-esque raoellids, a group of herbivorous land mammals that transitioned to the sea where they became fish eaters. Plants range in flavors—from sugary apples to tart, poisonous rhubarb leaves—and to survive, primitive animals learned the taste cues that signal whether food is delicious or dangerous. Based on the findings, taste dissipated after this common ancestor became fully aquatic—53 million years ago—but before the group split 36 million years ago into toothed and baleen whales.

“Pseudogenes arise when a trait is no longer needed,” says evolutionary biologist Jianzhi Zhang of the University of Michigan, Ann Arbor, who was not involved in the study. “So it still raises the question as to why whales could afford to lose four of the five primary tastes.” The retention of salty taste receptors suggests that they have other vital roles, such as maintaining sodium levels and blood pressure.

But dulled taste perception might be dangerous if noxious substances spill into the water. Orcas have unwittingly migrated into oil spills, while algal toxins created by fertilizer runoff consistently seep into the fish prey of dolphins living off the Florida coast.

“When you have a sense of taste, it dictates whether you swallow or not,” says Danielle Reed, a geneticist at the Monell Chemical Senses Center in Philadelphia, Pennsylvania. She was not involved with the current work, but co-authored a 2012 paper that found the first genetic inklings that umami and sweet taste receptors were missing in cetaceans, albeit in only one species—bottlenose dolphins.

Flavors are typically released by chewing, but cetaceans tend to swallow their food whole. “The message seems clear. If you don’t chew your food and prefer swallowing food whole, then taste really becomes irrelevant,” Reed says.

http://news.sciencemag.org/biology/2014/05/whales-cant-taste-anything-salt

Thanks to Dr. Rajadhyaksha for bringing this to the attention of the It’s Interesting community.