Back out to stud: veterinarians perform first reverse vasectomy on an endangered horse
Veterinarians at the Smithsonian Institute's National Zoo  in Washington, D.C., announced this week that they reversed a vasectomy that had been performed nearly a decade ago on a Przewalski's horse (pronounced "zshah-VAL-skeez"), a short, stocky breed that only grows to about four feet (1.3 meters) tall. About 1,500 of the animals have been raised in zoos worldwide since 1970, when they were declared extinct in the wild in their native Mongolia and China. Fearing a loss of genetic diversity in the tiny remaining population, scientists surveyed captive Przewalski's horses in search a set of genes worthy of being passed on. One of their primo candidates: a  20-year-old male named Minnesota, a former resident of the Minnesota Zoo. Alas, it turned out that Minnesota had had a vasectomy in 1999 so that he could be housed with but not impregnate female Przewalski's horses. A first attempt to reverse his vasectomy in March 2007 failed, but zoo officials say a second effort seven months later seems to have done the trick. National Zoo scientists hope to arrange a rendezvous between Minnesota and a suitable female next month.

Cloning man's best friend
For a nominal price, you could go down to your local dog shelter and find yourself a new best friend. Or, if you've already got one, you can spend $100,000 or more to make sure that your pal (or at least a clone of him or her) stays with you a while longer, considering most dogs live only 15 years or less. That's the promise that BioArts International, Inc., a San Francisco–area biotech startup, is making through its July 5–9 online auction to clone five dogs—the highest bidders win the right to have their dog cloned by the company. The company claims to hold the exclusive rights to clone dogs thanks to a deal announced last month with Start Licensing, Inc., a company formed in 2005 by Geron Corporation and Exeter Life Sciences, Inc. to manage both companies' intellectual property rights, including the transfer cloning technology developed at the University of Edinburgh's Roslin Institute and used to clone Dolly the sheep.  BioArts is also planning to clone one dog for free as part of its Golden Clone Giveaway (it will chose the winner based on a 500-word essay explaining why the writer feels his or her dog deserves to be cloned). Meanwhile, BioArts and Start Licensing denounced plans by South Korea's RNL Bio to start a dog cloning business, insisting that it does not have the rights to the patented cloning technology. BioArts chief executive officer Lou Hawthorne in a statement accused RNL of engaging in "black market cloning."

Adult stem cells may help mend broken bones
Researchers at the University of North Carolina at Chapel Hill (UNC) have devised a treatment that may help heal the roughly 600,000 patients in the U.S. each year who have trouble regenerating tissue after breaking bones. The scientists announced this week at a meeting of the Endocrine Society in San Francisco that they had infused stem cells from the marrow (the core of bones, where new blood cells are manufactured) of mice with broken legs with insulin growth factor 1 (IGF-1), a protein produced in the liver that encourages cells to grow. They then injected the enriched stem cells into the mice and discovered that they formed cartilage and bone tissue needed to mend the fractures. New bone generated in mice that received it was three times heartier than that formed in mice left to heal on their own. Study co-author Anna Spagnoli, a pediatrician at UNC, said that if human trials are successful, the procedure may aid patients with bone-thinning diseases such as osteoporosis.

Is there a doctor in the house? No?
It apparently doesn't pay to be a family doctor anymore, which is why the U.S. could face a shortage of up to 44,000 general practitioners within 20 years, according to a new study.  University of Missouri researchers report in the online edition of the journal Health Affairs that generalist physicians (GP) have fallen victim to a system that rewards specialists. Today, generalist physicians account for a third of the U.S. physician workforce and are responsible for more than half of all patient visits to doctors' offices, according to the survey. Over the past decade, the number of medical school graduates who opted to become GPs dipped by 22 percent, even as the U.S. population grew by about 10 percent (about 1 percent annually). The remedy, according to the researchers: new models of primary care called "medical homes," which do not refer to a type of housing but rather an approach to medicine that relies more on teams of generalist physicians, nurse practitioners and physician assistants than on specialists to provide comprehensive primary care services, even to patients with chronic illnesses. They envision a system in which patients and their families will have expanded e-mail and phone access to healthcare workers. The Association of American Medical Colleges recommends that medical schools strive to increase their enrollment by 30 percent, although to address the researchers' concerns, there will need to be incentives for students to pursue general medicine.

Sea levels rising due to faster warming oceans
A new study indicates that climate change has warmed the world's seas 50 percent faster over the past 40 years than scientists previously believed. Researchers from Australia and the U.S. report in Nature thatthe upper layers of oceans have been heating up more than had been reported, which, combined with other factors such as melting glaciers, resulted in sea levels rising six inches during the 20th century. Scientists say it's unclear how fast and how much water levels will climb in the future.

Latrines best toilets when it comes to preventing disease
A new study shows that latrines are less likely than traditional toilets to spread germs in the developing world. The reason, according to researchers from Michigan Technological University: waste from toilets often contaminates local drinking water supplies unless filtered by often absent, pricey sewer and treatment systems. Latrines—which, in essence, are little more than holes in the ground—on the other hand, safely separate human waste from the water supply. David W. Watkins, an associate professor at Michigan Technological University and co-author of the study published in Environmental Science & Technology, says this shows that often simply digging a pit beats fancier options.

Ladies do love jerks: Three character flaws make a man a stud
If all that cologne you're wearing and those drinks you're buying aren't translating into luck with the ladies, take note: New Mexico State University psychologist Peter Jonason says a survey of 200 college students showed that women prefer guys who are rude, manipulative narcissists. The London-based newspaper, The Guardian, reports the findings—reported at a recent meeting of the Human Behavior and Evolution Society—are backed up by a survey of 35,000 sexual active residents of 57 countries (conducted by David Schmidtt, a psychologist at Bradley University in Illinois). Go figure.

Early solar system was super dusty
A new study that ups the amount of dust believed to have been floating around in the early solar system brings scientists a step closer to understanding how planets formed. Researchers from the Carnegie Institution, American Museum of Natural History, and U.S. Geological Survey report in Science this week that they analyzed the chemical content of a 4.6-billion-year-old meteorite containing relatively pristine chondrules—millimeter-size grains of glass and crystal that were mysteriously flash fused out of dust when the Earth and neighboring planets were materializing. That heating should have seared away trace chemicals such as sodium, but the group says that the chondrules were unexpectedly rich in sodium, suggesting that dust must have been at least 100 times denser—about 10 grams per cubic yard—than previously believed. The results indicate these chondrules were likely intimately associated with the creation of mile-wide chunks called planetesimals from which planets formed.

Custom magnets might add "color" to MRI
Microscopic magnetic particles might give researchers a way to extract more information from magnetic resonance imaging (MRI) by, in effect, switching from black and white to color images. In MRI scans, powerful magnetic fields applied to the body cause tissues to emit radio signals, which can be used to visualize tissues in the body. However, those signals all come in the same frequency. To bump up the contrast between tissues, patients sometime receive chemicals that highlight certain ones. Writing in Nature, researchers from the National Institute of Neurological Disorders and Stroke, and the National Institute of Standards and Technology, report they have designed microscopic nickel magnets that show up during magnetic scanning at different radio frequencies (analogous to colors) depending on their shape. Although such particles are a long way from hitting anyone's bloodstream—nickel is toxic, for starters—they speculate that by targeting the micromagnets to specific cell types, scans might more easily pick out tumors or other tissues.