Editor's Note: Science Scan is a roundup of recently published biotechnology-relevant research.
A compound dubbed "reversine" by its discoverers causes cells, which are normally programmed to form muscles, to undergo reverse differentiation. That is, retreat along their differentiation pathway and turn into precursor cells. Those cells are multipotent, having the potential to become different cell types. Thus, the researchers who found it suggest that reversine represents a potentially useful tool for generating unlimited supply of such precursors. Those subsequently can be converted to other cell types, such as bone or cartilage.
Dedifferentiation implies moving backward developmentally from its current state to form its own precursor cell. Researchers from The Scripps Research Institute in La Jolla, Calif. released findings Dec. 19, 2003, in the weekly Journal of the American Chemical Society (JACS). Their article bears the title "Dedifferentiation of lineage-committed cells by a small molecule."
"That [type of approach]," observed the paper's co-author, "has the potential to make stem cell research more practical. It will allow one to derive stem-like cells from your own mature cells, thus avoiding the technical and ethical issues associated with embryonic stem cells [ESCs]. Stem cells," he continued, "have huge potential in medicine because they have the ability to differentiate into many different cell types. This capability potentially provides doctors with the ability to produce cells that have been permanently lost by a patient. For instance, the damage of neurodegenerative diseases like Parkinson's, in which dopaminergic neurons in the brain are lost, may be ameliorated by regenerating those neurons. Another example of a potential medical application is Type I diabetes, an autoimmune condition in which pancreatic islet cells are destroyed by the body's immune system. Because stem cells have the power to differentiate into islet cells, stem cell therapy could potentially cure this chronic condition.
"However bright this promise," the co-author went on, "many barriers must be overcome before embryonic stem cells can be used in medicine. Stem cell therapy would be most effective if a person could use his own stem cells, which would avoid potential complications from immune rejection of foreign intruders. However, in general, it has proven very difficult to isolate and propagate stem cells from adults. Embryonic stem cells offer an alternative, but face both practical and ethical hurdles. Reversine is a step in that process.
"Normally," he explained, "cells develop along a pathway of increasing specialization. Muscles, for instance, develop after ESCs develop into mesenchymal' progenitor cells, which then develop into myogenic' cells. These fuse and form the fibrous bundles we know as muscles. In humans and other mammals, these events are irreversible. One wouldn't expect a muscle cell to develop into a progenitor cell any more than one would expect a woman to give birth to her own mother."
Single SARS Human Suspect In South China Set Off Order To Wipe Out 10,000 Cat-Like Civets
The so-called civet cat is not a cat. The feline-mimicking mammal (viral family viverridae) takes after weasels and ferrets and mongooses. The latter beasties (mongoose are famed for killing poisonous snakes) also are consumed as winter delicacies in upper-crust Chinese restaurants. Mongoose musk goes into select perfumes as well. Civets are thick on the ground in parts of Asia and Africa, where of late they are suspected of spreading severe acute respiratory syndrome. Provincial officials in southern China have just launched a campaign to kill 10,000 civet cats to prevent SARS from spreading. But the World Health Organization (WHO) has issued a warning to curb such a slaughter, which if not done properly could spread the viral infections to the workers culling them. WHO's SARS expert, Jeffrey Gilbert, addressed a New York Times conference Monday in Beijing. He urged "extreme caution," stating that "we do feel that there is a potential hazard" in the extermination campaign.
What triggered that fear was a single 32-year-old male patient with all the earmarks and symptoms of SARS. He surfaced as a sole case since the first SARS outbreak subsided last summer, and it put those 10,000 civet cats on the kill order. How that one-and-only SARS suspect contracted the disease (from which he is now recovered) remains a mystery.
Weight-Loss Booster Bites Dust As FDA Bans Ephedra, Citing Hazard To Health, Life
On Dec. 30, 2003, the FDA announced a ban on Ephedra, an over-the-counter herbal supplement sold as a very popular weight-loss product. The agency advised Ephedra's millions of consumers to stop taking the plant supplement immediately. The FDA took this drastic step after reviewing 16,000 reports of the product's adverse reactions - ranging from heart attack to stroke to sudden death.
Ephedra, a Chinese plant also known as Ma Huang, is a stimulant as well as an appetite-suppressor, which increases heart rate, blood pressure, and accelerates brain activity. FDA counseled the now-deprived body-weight reducers to turn to prescription weight-controlling compounds. One it mentioned is Orlistat (brand name Xenical) made by F. Hoffman-La Roche Ltd., of Basel, Switzerland. Unlike Ephedra, instead of working on the brain, it cons the digestive tract into blocking one-third of the fat a person eats. Therefore, doctors add a daily fat-soluble multivitamin to go along with Orlistat, which costs about $3.50 a day. It's been shown to shed 5 percent to 9 percent of a consumer's body weight in a year.