Interruption of cell transformation and cancer formation.

A review of the results of X-ray and chemical carcinogen induction of transformation of mouse cells supports a two-step epigenetic model of transformation. According to this model, exposure induces an epigenetic regulatory alteration that makes the cells hypermutable so that when the cell population inheriting this alteration becomes sufficiently large, the second step, a mutation to the transformant phenotype, becomes increasingly likely. The epigenetic alteration in X-ray-exposed mouse cells has been demonstrated to be reversible by brief exposure to certain protease inhibitors. If the rodent cell experiments constitute a valid system for studying human cancer, then this two-step model may herald rich opportunities for preventing and perhaps even treating cancer in humans.

Relationship between age, renal function and bone mineral density in the US population.

Bisphosphonate drugs for treating osteoporosis are excreted by the kidney. However, many of the major trials on efficacy and safety of the bisphophonates for treating osteoporosis excluded patients with significant renal compromise. Since both osteoporosis and renal insufficiency become more prevalent with age, it seems prudent for physicians to be aware of the prevalence of renal dysfunction in patients with osteoporosis who are candidates for treatment with bisphosphonates. Data on 13,831 men and women aged 20+ from the Third National Health and Nutrition Examination Survey, 1988-1994 (NHANES III) were used to study the occurrence of compromise in renal clearance function in men and women with osteopenia and osteoporosis. To estimate creatinine clearance (CCr), a measure of renal function, serum creatinine (sCr), weight and age were inserted into the Cockcoft-Gault (C-G) formula. The World Health Organization gender specific bone mineral density (BMD) cut-offs were used to define the populations with osteopenia and osteoporosis. For women ages 20-80+ with osteoporosis, the percent prevalence (95% CI) for mild to moderate compromise of CCr