Genetic Test Could Eliminate Colon Cancer Procedure
A new genetic test could eventually eliminate invasive and cumbersome colonoscopies for detecting colorectal cancer, Baltimore researchers say, but it will be three to five years before the test is ready for general use.
Early detection of colon cancer could prevent most of the 56,000 deaths it now causes each year, but many people are unwilling to undergo the daylong fasting, intestinal flushing and invasive colonoscopies necessary to find early tumors. The new test requires no changes in diet and no cleansing of the gastrointestinal system.
The test looks for mutations in a gene called APC, which stands for adenomatous polyposis coli. Research by Dr. Bert Vogelstein and his colleagues at the Kimmel Cancer Center at Johns Hopkins University has shown that the APC gene is mutated in nearly all colorectal tumors. The new test relies on the fact that cells from a tumor are sloughed off into stool, where they can be detected. But it requires great technical sophistication to find the mutated gene because it is present in fewer than one in every 100 APC genes found in stool.
Vogelstein and his colleagues performed the test on stool samples from 46 patients with malignant or premalignant tumors and 28 healthy people. They reported in Thursday’s New England Journal of Medicine that the test was positive in 57% of the tumor patients but in none of the healthy controls. The team hopes to improve the test so that it detects at least 70% of tumors. The cost of the test is expected to be about $500. The study was partially funded by Exact Sciences Corp. of Maynard, Mass., which plans to market the test.
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Study Backs Daily Tests for Kidney Failure Patients
Daily hemodialysis is more effective than the currently used alternate-day blood cleansing for hospitalized patients with acute kidney failure, according to a new study.
Dr. Helmut Schiffl and his colleagues at the University of Munich in Germany studied 160 patients with acute kidney failure over a five-year period. Half were given daily dialysis, half alternate-day dialysis. The team reported in today’s New England Journal of Medicine that 46% of the patients getting alternate-day dialysis died, compared with just 28% of those receiving daily dialysis. Typically, the symptoms of kidney failure disappeared within nine days in those receiving daily dialysis compared with 16 days for those in the other regimen.
The daily regimen dramatically improves the chances of survival and speeds recovery of the kidney, the team concluded.
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Two Steps Better Than One in Cleaning Lenses
One-step contact lens solutions are not as effective as two-step systems in killing all forms of the bacterium Acanthamoeba, a main cause of eye infections in contact lens wearers.
Dr. Horst Aspock and his colleagues at the Clinical Institute of Hygiene in Vienna compared a one-step hydrogen peroxide solution, a one-step polyhexamethylene biguanide solution and a two-step hydrogen peroxide solution against Acanthamoeba. They reported in this month’s British Journal of Ophthalmology that only the two-step disinfectant solution successfully killed all the Acan- thamoeba when used as di- rected.
Because peroxide is harmful to the eye, such solutions must be neutralized before the lenses can be worn. One-step peroxide systems typically use a metal catalyst placed in the lens cup with the disinfecting solution to slowly destroy the peroxide.
In two-step peroxide systems, the lenses are immersed for 10 minutes in a second solution containing an enzyme that destroys the peroxide. Other one-step solutions use a detergent to inactivate bacteria.
The researchers speculated that the neutralizing disks in the one-step solutions destroyed the hydrogen peroxide before it had a chance to completely eradicate the bacteria. The detergent-based solutions are apparently simply not powerful enough to destroy all forms of Acanthamoeba.
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Regular Exercise Benefits Elasticity of Arteries
Your arteries are much less likely to stiffen as you age, thereby increasing blood pressure, if you exercise regularly, according to researchers at the University of Pittsburgh.
Retaining elasticity in the arteries does not necessarily require a regular exercise program, however. Regular physical activities such as moving around the house, dancing or yardwork may be sufficient.
Dr. Rachel Mackey and her colleagues studied 356 men and women ages 70 to 96. They questioned the subjects about the extent of their physical activity, then measured the stiffness of their arteries with a technique called pulse wave velocity.
The team reported in the January issue of the American Journal of Hypertension that the more exercise the patients reported, the greater the elasticity of their arteries, independent of other risk factors for heart disease. Among women, the team found that current and former users of hormone replacement therapy had more elastic arteries than those who had never used it.
The importance of hormone replacement therapy for maintaining blood vessel health was noted independently by UCLA researchers who measured blood flow to the heart at rest and in times of stress in post-menopausal women.
Dr. Heinz Schelbert and his colleagues studied 54 post-menopausal women--31 of whom were taking hormone replacement therapy--and 12 young healthy women who served as controls.
The team reported in Tuesday’s issue of Circulation: Journal of the American Heart Assn. that the women who were not receiving hormone replacement therapy had impaired blood flow to the heart during stress. Women receiving the therapy, however, had blood flow equivalent to that of the younger women--unless they had other risk factors for heart disease, such as high cholesterol.
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Thomas H. Maugh II is at thomas. maugh@latimes.com.
