DNA ploidy and proliferative index of cardiac myxoma.

Cardiac myxoma is the commonest tumour of heart. The histogenesis of this lesion is controversial as its origin has often been debated between the thrombogenic and neoplastic theories. We analysed DNA ploidy and proliferation indices of 30 cardiac myxomas which include 25 sporadic and five familial cases by image cytometry and proliferating cell nuclear antigen immunostaining. Of the 25 cases, 18 were aneuploid, three diploid and four tetraploid. Four of the five familial cases including the recurrent lesions were aneuploid. Poor tissue preservation precluded ploidy analysis in one familial case. The proliferation index of the sporadic cases ranged from 0.4 to 36.1 percent. The familial cases showed proliferation index between 10.2 and 22 percent. In addition to cardiac myxoma, proliferation index was assessed in 10 cardiac thrombi where it ranged from three to 58 percent. This study suggests that cardiac myxoma can be best interpreted as a neoplasm with a slow growth potential.

Effects of centchroman, a synthetic estrogen antagonist on the fertility of female hamsters.

Centchroman (3, 4-trans-2, 2-dimethyl-3-phenyl-4-p-beta-pyrrolidinoethoxy-phenyl-7-methoxy-chroman) , a non-steroidal, estrogen antagonist, injected subcutaneously (2 mg/kg body wt) on days 1, 2 and 3 post-coitum in hamsters, prevented implantation in 70% of the animals. A significant decrease in the circulating levels of estradiol and progesterone was observed on day 4 post-coitum as compared to control animals following the treatment of centchroman. The activities of various lysosomal enzymes were also found diminished in the treated animals. This study shows that centchroman may act as an anti-implantation agent in hamsters indicating that estrogen plays a key role during the process of ovum implantation in this species.

Endurance capacity for continuous effort in terms of aerobic and anaerobic fraction of oxygen supply.

Studies have been conducted on 13 young healthy adults of average fitness on endurance work of varying durations lasting for 2-31 minutes using bicycle ergometer. Aerobic-anaerobic fractions of oxygen supply during each effort was determined. The data from Astrand and Rodahl on aerobic O2--supply and duration in maximal efforts from 1-120 minutes on a highly trained subject have also been considered. The plot of log endurance time against log (aerobic/anaerobic ratio) exhibits a slight departure from linearity, indicating independent contributions from aerobic and anaerobic fractions of oxygen supply. An equation was derived of the form: T - Au1k1u2--k2 where u1 end u2 are the aerobic and anaerobic fractions respectively which has been found to yield highly significant correlation coefficient between log-estimated and log-observed endurance time (0.9996 for Astrand and Rodahl's data on a single subject and 0.9640 for the present data on 13 subjects). This index is, therefore, quite suitable for the assessment of endurance capacity in terms of a single physiological parameter, and is likely to be superior to indices in current use.