Resistence to Antibiotics on Rise in US
By Serena Gordon HealthScoutNews Reporter FRIDAY, April 19 (HealthScoutNews) — In the wake of a new report that the strep throat germ is now showing significant antibiotic resistance in the United States, many people are wondering if they — or their children — are at risk. They just might be, unless all of us our dependence on antibiotics, says Philip Tierno, director of clinical microbiology at New York University Medical Center and Mt. Sinai Medical Center in New York City. “”Antibiotic resistance is more prevalent than you’d think,”" Tierno adds. There are two main reasons for it: Overprescription of antibiotics by doctors and the use of antibiotics in livestock, he says.
“”One hundred and fifty million prescriptions are written annually,”" Tierno says. “”Ninety million of those are for antibiotics, and 50 million of those are unnecessary.”" Many antibiotic prescriptions are written for sore throats, but only a small percentage of them are caused by Group A streptococci bacteria, which causes strep throat. The germ can also cause sinus, ear and skin infections. Left untreated, strep can progress into scarlet fever or the more serious rheumatic fever, with potentially fatal consequences. Young children are especially vulnerable to such complications. Strep throat is commonly treated with antibiotics, such as penicillin, or erythromycin for those who are allergic to penicillin. In yesterday’s New England Journal of Medicine report, researchers from Children’s Hospital of Pittsburgh studied a group of 100 area school children from kindergarten through eighth grade. They found that Group A streptococci was resistant to erythromycin in 48 percent of the throat cultures taken between October 2000 and May 2001. According to the researchers, this is the first time such a high level of resistance to erythromycin has been found in the United States. Similarly high levels of resistance have been reported in other countries, however, Tierno says. In Japan and Finland, he says, resistance to Group A strep has been reported at levels exceeding 50 percent. The good news, according to Tierno, is that in Japan the rate of resistance has fallen as health officials there decreased their use of erythromycin-based antibiotics. By not using these drugs, Tierno explains, the germs become vulnerable to them again. The Pittsburgh researchers followed the children for three years, and during the first two years, while they did find cases of strep, they found no signs of antibiotic resistance. It wasn’t until the third year that the antibiotic-resistant strain appeared. Tierno says this finding clearly points to overuse of antibiotics. “”What causes drug resistance is the inappropriate use of antibiotics by physicians,”" he says. But patients are partly to blame as well, he adds, because they push for inappropriate prescriptions when they’re ill. Dr. James Musser is chief of the Laboratory of Human Bacterial Pathogenesis at the National Institute of Allergy and Infectious Diseases in Hamilton, Mont. He says, “”From a national perspective, we need to be very concerned about increasing antibiotic resistance in any pathogen.”" And, he adds, we need a study that looks at a greater geographical area to assess how widespread the problem [uncovered in Pittsburgh] might be. In the meantime, he says, “”It’s important for patients to realize that not every upper-respiratory infection is of bacterial origin and to listen closely to the advice of the treating physician.”" That means patients shouldn’t badger their doctor for antibiotics unless they’re deemed necessary.
Science Begins to Add Weight to CLA
The flurry of activity in CLA applications is being backed by a growing body of research to support the ingredient, particularly for its effects on weight loss. A review published in this month’s Journal of Nutrition supports conjugated linoleic acid’s action on weight management, concluding that it is at least in part due to regulation of glucose and fatty acid uptake and metabolism.
Conjugated linoleic acid is the common name of a group of fatty acids found in dairy products and meat. CLA isomers have been studied for their action on an impressive range of diseases, including cancer, atherosclerosis, obesity, and immune function. However as scientists begin to reveal their effects on reduction of body fat, food makers are increasingly looking at the ingredient for the valuable slimming market.
In Canada, where many of the patents for CLA are held, the dairy industry has long been studying the production of high-CLA milk. In Europe, a research centre in Ireland is studying the compound which could add significant value to its dairy industry, while in Italy, Techno Foods introduced a strawberry flavoured yoghurt naturally rich in CLA (conjugated linoleic acid) and omega-3 fatty acids this summer.
Specific CLA isomers have been shown to prevent the development of obesity in certain rodent and pig models and this has been attributed mainly to trans-10, cis-12 CLA, both in vivo and in vitro, write the University of North Carolina researchers in the review. However, CLA’s ability to modulate human obesity remains controversial because data from clinical trials using mixed isomers are conflicting.
In vitro studies by the team demonstrated that while trans-10, cis-12 CLA prevents triglyceride accumulation in human cells, cis-9, trans-11 CLA increases triglyceride content. The team concluded that the isomers’ regulation of glucose and metabolism must partly explain its mechanism on human fat.
The news is also good for supplement marketers who recently learned of research carried out by Cognis backing the long-term safety of its Tonalin CLA.
Brain Cell Growth Boosted By DHEA Supplements
‘Anti-aging’ hormone DHEA Found to Boost Brain Cell Growth August 24, 2004
Human neural stem cells, exposed in a lab dish to the steroid DHEA, exhibit a remarkable uptick in growth rates, suggesting that the hormone may play a role in helping the brain produce new cells, according to a new study published this week in the online edition of the Proceedings of the National Academy of Sciences (PNAS).
The new work, conducted by a team of scientists at the University of Wisconsin-Madison, provides some of the first direct evidence of the biological effects of DHEA on the human nervous system, according to Clive Svendsen, the study’s senior author and an authority on brain stem cells at UW-Madison’s Waisman Center.
“What we saw was that DHEA significantly increased the division of the cells,” said Svendsen, a UW-Madison professor of anatomy and neurology. “It also increased the number of neurons produced by the stem cells, prompting increased neurogenesis of cells in culture.”
DHEA or dehydroepiandrosterone is among the most abundant naturally occurring steroids in the blood of young humans, but levels decline with age and its physiological effects are poorly understood.
A synthetic form of the hormone is sold over-the-counter as a dietary supplement in the US, thought to have anti-aging properties and to offer prevention against cancer and heart disease, Alzheimer’s and other diseases. But scientists know relatively little about the drug and its basic biological effects on humans.
“We don’t know much about DHEA, but this new work adds a piece to the puzzle,” said Svendsen, who conducted the study with colleagues Masatoshi Suzuki, Lynda S. Wright, Padma Marwah and Henry A. Lardy, all of UW-Madison. “This is the first real evidence of DHEA’s effects on human neural cells.”
Svendsen and Suzuki carried out the experiments by growing human fetal neural stem cells in culture. The cells form aggregates known as ‘neurospheres,’ which were exposed to a cocktail of DHEA and growth and inhibitory factors, and observed a 29 per cent increase in new brain cells compared to cells grown in a medium with the same factors, but without DHEA.
“We saw such a pure effect of DHEA,” Svendsen said.
“It’s the only steroid we tested that had such a direct effect on stem cell growth and new neuron formation,” according to Suzuki.
The new work is important because it provides a direct window to the controversial hormone’s effects on critical human cells. Similar studies have been conducted in mice and rats, but those models have shortcomings that are difficult to address, Svendsen notes.
“There are previous studies in rats that suggest DHEA is neuroprotective, but the problem with DHEA in rats is that it is not a major metabolite in that animal so its effects may not be the same as those seen in humans,” he said. According to Lardy, metabolic products of DHEA hormone have also been shown to aid memory retention in old mice.
Despite hints from the studies in rodents that DHEA may play a role in enhancing the brain and memory, the new findings reported in the PNAS article were a surprise, he said.
“We assumed the compounds we were testing would be more active than DHEA in brain stem cells,” Lardy explains. In previous studies, Lardy, with Wisconsin biochemistry colleagues James Ntambi and Brian Fox, showed that DHEA blocked a step in fat synthesis.
“The effects of DHEA on brain stem cells is a completely new finding,” said Lardy. “The problem of whether DHEA itself is having this effect, or if there’s another metabolite of the hormone involved, still exists.”
One of the intriguing aspects of the new work, according to Svendsen, is the possibility that DHEA could have some positive effects on the adult human brain.
It is known that DHEA amounts fall progressively during aging, and reduced levels of DHEA have been reported in both adolescents and adults with major depressive disorders. And given the fact that adult humans have neural stem cells that continue to make new neurons in some parts of the brain, there is a possibility that DHEA could play a role in moderating the genesis of new brain cells.