Tissue specific regulation of renal n-nitrosodimethylamine-demethylase activity by testosterone in BALB/c mice

Nitrosodimethylamine (NDMA), like several other nitrosamines, is activated by the enzymes-mixed-function oxidases-present in the tissue microsomal fractions, producing mutagenic and carcinogenic effects. Previous studies in BALB/c mice have shown an age, sex and androgenic regulation of NDMA-induced mutagenicity. The present study was designed to test the correlation between renal NDMA-demethylase activity and previously published reports on NDMA-induced mutagenicity. Renal and hepatic NDMA-demethylases were determined from the microsomal fractions by quantitating formaldehyde. Renal NDMA-demethylase showed the presence of two isozymes, I and II, with Km values of 0.6 ± 0.2 and 20.2 ± 6.8 mM respectively. Isozyme I was detected in adult males and first appeared at the onset of puberty; it was absent in adult females and in immature mice. Renal isozyme II was detected in both males and females and was independent of age. Testosterone treatment of adult females resulted in the appearance of renal isozyme I. Castration of adult males caused a dramatic decrease in activity, whereas testesterone administration to such castrates increased activity, of renal isozyme I. Hepatic NDMA-demethylase activities were independent of age, sex or testosterone treatment. In conclusion, these results show an age, sex and tissue specific regulation of renal NDMA activity. Renal and hepatic NDMA-demethylase activities correlated positively with earlier studies on NDMA-induced mutagenesis and carcinogenesis. © 1988

Resilience in siblings of children with sickle cell disease

This pilot study was conducted to identify factors responsible for promoting resilience in siblings of children with sickle cell disease. Twenty siblings (10-17 years of age) of children (5-13 years) with sickle cell disease were selected from the Pediatric Clinic of Howard University Center for Sickle Cell Disease. The siblings responded to questionnaires, and the data obtained was analyzed by chi-square for association. The results indicated that age, birth order, and gender had no effect on resilience in the siblings. However, family size, number of parents in the home, sibling\u27s knowledge of the illness, degree of morbidity of the illness, socioeconomic status of the family, and parents\u27 attitudes and childrearing practices were all found to affect resilience. These findings provide additional insight into the psychosocial aspects of, and genetic counseling for sickle cell disease, as well as for other chronic genetic disorders. © 1995 National Society of Genetic Counselors, Inc