Study Questions Specificity of RNA Interference
RNA interference (RNAi) is gaining attention as a powerful new tool to silence defective genes in certain diseases such as cancer, but a new study suggests that the technique may not be as specific as researchers believe.
The discovery of short interfering RNAs (siRNAs) made RNAi possible in mammalian cells, and it was thought that siRNAs could overcome some of the inherent problems associated with RNAi, such as the activation of the interferon system, which is involved in the cells anti-viral response mechanism.
Carol A. Sledz, of the Lerner Research Institute in Cleveland, Ohio, and her colleagues tested six different siRNAs and found that they all activate genes in the interferon system. Full activation of the system leads to cell death.
"The induction of the interferon, and possibly other, cellular signaling pathways indicates that siRNAs have broad effects beyond the selective silencing of homologous target genes when introduced into cells," the researchers wrote. "Therefore, caution must be exerted in the interpretation of data from experiments using RNAi technology for suppression of specific gene expression."
The results were published in the August 24 advance online publication of Nature Cell Biology.
See also News, Vol. 95, No. 7, p. 500, "Better Blocker: RNA Interference Dazzles Research Community."
Watch and Wait Policy May Be Appropriate for Asymptomatic NHL
For patients with asymptomatic non-Hodgkins lymphoma (NHL), it may be appropriate to delay treatment until symptoms occur, according to a new study that found no difference in survival between asymptomatic patients managed by a watch-and-wait strategy and patients treated promptly after diagnosis.
The watch-and-wait approach has long been considered an option because neither chemotherapy alone or in combination with radiation has been able to cure NHL, and previous studies have found no advantage of immediate treatment over a watch-and-wait strategy.
In the new confirmatory study, Kirit Ardeshna, of Mount Vernon Cancer Centre in Northwood, United Kingdom, and collaborators from the British National Lymphoma Investigation, randomly assigned 309 patients with advanced-stage, low-grade NHL to be treated immediately with the oral chemotherapy chlorambucil or to be treated after symptoms developed. The patients were followed for an average of 16 years.
Patients in the immediate treatment group survived about as long (5.9 years vs. 6.7 years) as patients in the observation group. Cause-specific survival was also similar between the immediate treatment and observation group (9 years vs. 9.1 years). The chance of not needing chemotherapy after 10 years was 19% for patients younger than age 70 and 40% for patients ages 70 and older, suggesting that the watch-and-wait policy may be especially appropriate for patients older than age 70.
The study appeared in the August 16 issue of The Lancet.
Medicare Coverage Encourages Use of Prevention Tests, Study Finds
A new study has found that gaining access to Medicare, the federal insurance coverage for people age 65 and older, encourages greater use of preventive services among previously uninsured adults.
J. Michael McWilliams, M.D., of the Brigham and Womens Hospital and Harvard Medical School in Boston, and his colleagues compared the use of cholesterol tests, mammography, and prostate exams among 2,203 adults ages 60 to 64 who were classified as continuously uninsured, intermittently uninsured, or continuously insured before and after they became eligible for Medicare.
Prior to Medicare coverage, only 40.6% of the uninsured adults received cholesterol testing, compared with 76% of insured adults; 45.7% of uninsured adults received mammograms, compared with 76% of insured adults; and 28.9% of uninsured adults received prostate exams, compared with 74.1% of insured adults. After Medicare coverage, the difference in cholesterol testing rates between previously uninsured and insured patients fell from 35.4% to 17.7%, the difference in mammography rates fell from 30.3% to 15%, and the difference in prostate exam rates fell from 45.2% to 20%.
The researchers point out that the effect of Medicare coverage on cholesterol testing was substantially greater among uninsured adults with hypertension or diabetes than among those without the conditions. The findings are consistent with past studies suggesting an association between health insurance coverage and greater use of preventive services, the researchers concluded in the August 13 issue of the Journal of the American Medical Association.
![]() |
||||
|
Oxford University Press Privacy Policy and Legal Statement |