Expression of p24, a novel p21Waf1/Cip1/Sdi1-related protein, correlates with measurement of the finite proliferative potential of rodent embryo fibroblasts.

Normal mammalian fibroblasts undergo a limited number of divisions when cultured in vitro before entering a state of replicative senescence. The molecular basis for the determination of the finite mitotic potential is not known. Nevertheless, simian virus 40 T antigen, among other oncogenes, is able to prevent senescence in rodent embryo fibroblasts.

Rat embryo fibroblasts immortalized with simian virus 40 large T antigen undergo senescence upon its inactivation.

Introduction of simian virus 40 T antigen into rodent fibroblasts gives rise to cells that can proliferate indefinitely but are dependent upon it for maintenance of their growth once the normal mitotic life span has elapsed. Inactivation of T antigen in these immortalized cells causes rapid and irreversible cessation of growth. To determine whether this growth arrest is associated with entry into senescence, we have undertaken a genetic and biological analysis of conditionally immortal (tsa) cell lines derived by immortalizing rat embryo fibroblasts with the thermolabile tsA58 T antigen.

Traditional veterinary medicine in India.

A tradition of veterinary therapy developed very early in India and this has survived to the present time. Based on the Ayurveda ('knowledge concerning longevity'), a medical art which had its roots in the literature of the Veda (1500-1000 BC), Indian veterinary medicine is known for its specialised literature, which provides information on ancient methods of preventing and treating diseases of animals before the advent of modern medicine. Some of these treatments, little known outside India, are still practised today.