Agent Orange Tied to Diabetes, Heart Risks

Confirming the fears of some Vietnam veterans and their families, a government study has found that exposure to the defoliant Agent Orange increases the risk of diabetes and heart disease. But the panel could find no evidence of a link to cancer.

The study, conducted by the office of the Air Force surgeon general, was based on physical examinations in 1997 of 1,000 Air Force veterans who had been exposed to the chemical and another 1,300 who were not.

The concern revolves around a contaminant of Agent Orange called dioxin. The study, released Wednesday, found a 47% increase in diabetes among veterans with the highest levels of dioxin in their blood. It also found a 26% increase in heart disease among those exposed to dioxin, although the risk did not increase with higher exposures. The toxin was also linked to high blood pressure, but the group could find no convincing evidence that it produced a higher incidence of cancer.

It is not clear how many veterans were exposed to Agent Orange, but an estimated 7,600 have been awarded compensation payments for health problems that may be linked to such exposure. The current study has been ongoing since 1982. Preliminary results released in 1992 suggested, but did not prove, a link to diabetes.

Beta-Blockers Linked to Diabetes in Study

High blood pressure itself may also lead to diabetes, according to a study from Johns Hopkins University in Thursday's New England Journal of Medicine. People with hypertension are 2.5 times as likely to develop diabetes as those without it, according to Dr. Frederick L. Brancati and his colleagues. People taking any of a family of drugs called beta-blockers to reduce their blood pressure had an additional 28% risk of diabetes, apparently associated with use of the drugs.

The findings come from a national ongoing study called Atherosclerosis Risk in Communities that involves 12,550 adults between the ages of 45 and 64 who had heart disease or were at risk of developing it when they entered the study. None had diabetes at the start of the study.

Six years into the study, there were 569 cases of Type 2 diabetes among the 3,804 people who had hypertension at the beginning of the study and 577 cases among the 8,746 who did not. Among those with hypertension, people taking beta-blockers had a 28% higher risk of developing diabetes.

"We're not suggesting that people stop taking beta-blockers, as they have proven benefits in lowering the risk of cardiac events," Brancati said. "But physicians need to weigh the benefits against the diabetes risk and monitor patients carefully."

Merck Manual for Consumers Goes Online

For 100 years, physicians needing information about symptoms and treatment of disease have consulted the Merck Manual, a basic medical handbook that is a mainstay of doctors' offices. Recently, Merck, the pharmaceutical firm that publishes the manual, has put out a version for consumers written in plain English. It is available on the Internet at http://www.merck.com/pubs/mmanual_home.

Blood Levels of HIV May Affect Infection Rate

Reducing levels of the AIDS virus in the bloodstream lowers the likelihood of transmitting it to sexual partners, according to a new study conducted in Uganda. Researchers from the United States and Uganda studied 415 couples of whom only one member was HIV-positive when the study began. The couples received counseling about prevention and free condoms but no treatment because anti-AIDS drugs are not widely available in that country. About 22% of the previously uninfected partners became HIV-positive during the course of the study.

The team reported in Thursday's New England Journal of Medicine that every tenfold increase in concentration of the virus in the blood led to a doubling in the rate of transmission. Nearly 80% of the cases of new infection resulted from exposure to partners with more than 10,000 copies of HIV per milliliter of blood. The results were similar regardless of whether the infected partner was male or female. They also found that the highest infection rates occurred in younger couples, ages 15 to 19, and that circumcision in men reduced the risk of contracting the virus.

Mental Acuity Can Be Chemotherapy Casualty

Chemotherapy for cancer may cause long-term mental problems, according to a new study by psychologist Tim A. Ahles of the Dartmouth Medical School. Cancer patients have long reported muddied thinking, poor memory and inability to do math during the course of chemotherapy, but physicians have always believed the effects would fade with time. Ahles' results in the first study of the problem suggest they do not.

Ahles studied 71 patients who were cancer-free after receiving chemotherapy 10 years earlier and compared them to 58 who had been treated with only radiation therapy or surgery. He reported Tuesday at an American Cancer Society meeting in Tampa, Fla., that the chemotherapy survivors performed significantly worse on tests of mental agility.

In most cases, the alternative to the therapy would probably have been death. But Ahles noted that patients with early-stage cancer often opt for aggressive chemotherapy, even though statistically it offers only a percentage point or two increase in survival. In such cases, he cautioned, less aggressive treatment may be preferable.

Magnets Tested on Chemotherapy Patients

The efficacy of cancer chemotherapy can be increased and side effects diminished by using magnets to direct drugs to the tumor, according to preliminary results from a team headed by Dr. Scott C. Goodwin of the UCLA Medical Center. The technique has been studied in only 16 liver cancer patients so far, but the results were promising enough to warrant further studies, Goodwin told a San Diego meeting of the Society of Cardiovascular and Interventional Radiology on Monday.

For the study, chemists attached small magnetic particles to the cancer drug doxorubicin. A physician then infused the drug into a blood vessel leading to the tumor while a magnet was positioned over the tumor. The magnet caused most of the drug to be trapped inside the tumor, limiting its ability to kill non-cancer cells elsewhere in the body and thereby produce side effects like nausea and hair loss.

In the 12 patients studied for at least 28 days, Goodwin said, two tumors shrank, seven stabilized and three grew. He predicts the response will improve as drug dosages are increased in future studies.

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Medical writer Thomas H. Maugh II can be reached at thomas.maugh@latimes.com.

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