Jewish World Review Dec. 21, 2001 / 6 Teves, 5762




Vaccination of children controls hepatitis a in the community

By Robert A. Wascher, M.D., F.A.C.S.

http://www.jewishworldreview.com -- THIS week's journal of the American Medical Association reports on the community-wide impact of vaccinating children against hepatitis A. Hepatitis A is a virus that causes inflammation of the liver, and is most often transmitted through poor hygienic habits, as the virus is shed in the feces. Hepatitis A can easily be spread by contact between an infected person and foodstuffs or food preparation surfaces. The virus is able to remain intact for many months at room temperature or in freezers. It can also be spread by sexual contact and by blood transfusions. Fortunately, however, an effective vaccine has recently been developed for hepatitis A.

The study's authors evaluated the community of Butte County, California, which had one of the highest incidences of hepatitis A in the state. An aggressive hepatitis A vaccination program for children aged 2 to 12 years was undertaken in Butte County, beginning in January of 1995 and ending in December of 2000. Children were vaccinated without charge.

During the study, 66% of all eligible children received hepatitis A vaccinations. During the study period, the number of hepatitis A cases in Butte County declined a dramatic 94% (from 1995 to 2000), making Butte County's incidence of the disease in the year 2000 the lowest of any of any county in the state! The authors concluded that rigorous vaccination of children against hepatitis A not only protected the vaccinated children, but also protected the unvaccinated members (both adults and children) throughout the community.

A POSSIBLE CURE FOR SICKLE CELL DISEASE

Approximately one in 13 African Americans carries the mutated gene known to cause sickle cell disease. Mutations in both copies of the gene are needed to cause the actual disease, a condition that is present in about 72,000 Americans. The disease commonly causes acute "sickle cell crises" in afflicted children, resulting in excruciating bone, joint and abdominal pain. Repeated crises can leave patients with damaged joints and internal organs. The chronic anemia ("thin blood") associated with the disease also requires frequent blood transfusions, with all of the risks entailed by that treatment. Arteries feeding vital organs, including the brain, heart, kidneys and lungs, can become blocked as well, causing serious-and sometimes fatal-damage to these organs. At the present time, there is no known cure for the disease.

The current issue of the journal Science reports on a very promising treatment for sickle cell disease, using gene therapy in experimental mice. A modified HIV virus was created to deliver a gene for a protein that prevents sickle cell patients' red blood cells from becoming deformed ("sickling"). Mice afflicted with two forms of sickle cell disease were treated with this modified virus in this study.

The study's authors found that 99% of the mouse red blood cells expressed the protein coded by the gene after they were infected by the modified virus. Moreover, the treated mice did not develop sickling of their blood cells for up to 10 months after treatment (the lifespan of a mouse is only 2-3 years).

This is a dramatic application of gene therapy to a disease that afflicts thousands of children each year in the United States, and provides hope that effective treatment for this genetic disease-and others-will soon be available. Remaining issues to be resolved, however, include proving the safety of the modified HIV virus that was used to carry the treatment gene, and demonstrating that the same gene will have similar effects in human patients.

LEPTIN AND THE RISK OF HEART ATTACKS

Leptin, an interesting hormone that was recently found to be related to obesity (at least in mice), is in the news again. Mice with abnormally low levels of normal leptin appear to lose control of their appetites, becoming quite obese in the process. This finding resulted in much speculation about leptin as "the cure" for human obesity. Unfortunately, as is often the case in medical research, what works in mice often does not work in humans. Indeed, subsequent research seemed to suggest that obese humans frequently have higher blood levels of leptin!

The current issue of the journal Circulation features an intriguing study of the blood levels of leptin, and the relationship between heart attacks and leptin blood levels. This Scottish study evaluated the blood leptin levels of 377 men who later experienced a heart attack, and compared them with the blood leptin levels of 783 men who did not develop any cardiac events during the 5-year study period.

The study confirmed that patients with elevated leptin levels in their blood were 25% more likely to develop a heart attack than patients with low or normal blood levels.

Although the full biological function of this hormone is poorly understood in humans, it seems to play an important role in the metabolism of fat. While it has not lived up to its early promise as a potential cure for obesity, leptin may well have a few more surprises up its sleeve as we learn more about its function.

JWR contributor Dr. Robert A. Wascher is a senior research fellow in molecular & surgical oncology at the John Wayne Cancer Institute in Santa Monica, CA. Comment by clicking here.

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© 2001, Dr. Robert A. Wascher