Monday, March 29, 2010
The factors instrumental in triggering latent tuberculosis (TB) infection to progress into active disease have long remained elusive to researchers. Now, Professor David Russell and his group at Cornell University in New York, USA, have demonstrated that TB-causing bacteria are able to hijack fat metabolism in the host to drive the progression of the disease.
The research shows that Mycobacterium tuberculosis (Mtb) is able to stimulate macrophages - the immune cells the bacterium infects - to accumulate fat droplets, turning them into "foamy" cells. This cellular transformation can trigger a reawakening of the TB infection from its latent state.
Following initial infection by Mtb, the infected immune cells in the body can clump together in the lungs in a cellular mass that is surrounded by a fibrous cuff.
This containing structure, called a tubercle, physically protects the bacteria from being destroyed by the immune system.
This allows them to persist inside the host for years during a latent period in which the host shows no symptoms.
The respiratory infection is reactivated only in a small percentage of individuals in whom it progressively destroys lung tissue. Very little is known about the exact causes of reactivation and the relative roles of the host and the pathogen.
Russell's group discovered that inside the tubercle, surface molecules of Mtb prompted host macrophage cells to take up vast quantities of cholesterol-type lipids from the surrounding blood vessels.
"We think that the lipids in the newly-formed foamy cell are then expelled into the cellular environment, which contributes to the collapse of the tubercle," he said.
Once freed from their containing structure, the infectious bacteria are able to leak out into the airways where they can progressively destroy lung tissue.
"If our model is correct, it has huge implications for vaccines and chemotherapy programmes. A more detailed knowledge of the bacterium's life cycle and its host interactions will allow us to spot new targets for drugs - opening up new possibilities for treatment," said Russell.
Wednesday, March 24, 2010
Alcoholism affects over 17 million people. Without proper treatment, it's a devastating disease that can ruin lives and relationships. A new therapy that comes in a pill is bringing new hope to alcoholics.
There was a time in Christine Flemming's life when alcohol came before her kids.
"I can't remember when my daughter was very little, because I was drinking so much," said Flemming. "That affected me a lot."
Flemming needed help, but traditional treatment methods didn't work. Now she's on a new kind of therapy in the form of a pill called topiramate. It has changed her life. "I can tell you that it cuts my cravings, and I don't feel like I have to drink," Flemming said. "I don't feel like that's something I need in my life and I have to do."
Alcohol increases levels of dopamine, a chemical in the brain that makes us feel good. The drug works by blocking the right amount of the feel-good effects from alcohol to reduce cravings and help stop heavy drinking.
During clinical trials, neuropharmacologists were surprised to learn it also lowers blood pressure and cholesterol levels, which may lead to a decrease in heart disease in alcohol dependent patients.
"Most of the morbidity due to alcoholism is caused by secondary effects of all these other systems, so to have a drug that begins to correct all those other physical abnormalities is extremely helpful," said Bankhole Johnson, Ph.D., a Neuropharmacologist at the University of Virginia in Charlottesville, Va.
The drug helped improve Fleming's health and end her dependence on alcohol. She cut her drinking from 15 beers a day to just three, so time with her kids is now a priority.
"It's made a big difference," Flemming said. "It's made a really big difference, and I feel like I'm actually there for my family."
Qualifying patients can find out how to receive the drug by contacting their primary care doctors.
WHAT IS TOPIRAMATE? Topiramate is a drug originally discovered in 1979. It is prescribed as an epilepsy medication and for migraine headaches. It is also used for a number of other purposes, including as a treatment for people with alcoholism. Researchers believe that topiramate works in two ways. First, it reduces the release of dopamine that follows the consumption of alcohol. This reduces the positive feeling that people receive from alcohol, and thus reduce the incentive to drink. Second, topiramate interferes with the protein glutamate which normally excites dopamine neurons and again, lessening the ýfeel goodý effect of dopamine from alcohol.
WHAT IS ALCOHOL? Alcohol is created through the natural process of fermentation. This happens when yeast and sugar from vegetables and grains change the sugar into alcohol. When you drink alcohol, it is absorbed into your bloodstream, where it can affect the central nervous system, which is the control center for your entire body. Alcohol slows down this control center with its sedative effect. In moderation it can reduce anxiety, but it also blocks some of the commands the brain sends to other parts of the body, so it alters your senses. Thatýs why, when drunk, people often have trouble walking, talking, and some may even "black out," forgetting what they said or did. Drinking an excessive amount of alcohol can even be fatal.
Monday, March 1, 2010
The body only needs the stuff when severely dehydrated
According to a new investigation, it would now appear that the body's internal clock is directly responsible for this ability that we have. It has direct control over a water-storing hormone that regulates our need to intake or dispose of liquids. The direct mechanism that allows for this to happen was evidenced by neurophysiologists Eric Trudel and Charles Bourque, in a scientific paper they published in the latest issue of the respected scientific journal Nature Neuroscience. The two, who are based at the Research Institute of the McGill University Health Center, in Montreal, Canada, propose that the hormone vasopressin is directly responsible for storing water during the night,
They argue that the circadian rhythm, or the body's internal clock, allows for certain types of water-sensing cells in the body to activate other cells that produce vasopressin, when an individual is sleeping. They argue that the hormone essentially instructs the body to store water and not parade it around, as it does while the person is awake, and able to find water for drinking.
“We've known for years that there's a rhythm of vasopressin that gets high when you're sleeping. But no one knew how that occurred. And this group identified a very concrete physiological mechanism of how it occurs,” adds University of California in Los Angeles (UCLA) David Geffen School of Medicine neuroscientist Christopher Colwell. He has been studying the relationships between sleep and the circadian rhythm for many years. The new investigation was conducted on lab mice, but the results are very likely to hold out in humans as well. However, more research is needed before this correlation is validated.