The effect of nitrosocimetidine (NC) on the frequency of sister-chromatid exchanges (SCEs) in human lymphocytes has been studied. The frequency of SCEs induced by a 1-h exposure to 2.6 X 10(-4) M NC was 4-fold greater than that in the solvent control. A 72-h exposure to NC had a similar dose-related effect. We also examined the effect of the sulfhydryl compounds cysteine, cysteamine, cystamine and glutathione, the reducing agent dithionite, and vitamins C and E on the NC-induced SCEs. None of these compounds induced SCEs. Cysteine, cysteamine, and cystamine significantly reduced the number of NC-induced SCEs, and the others did not.

Ascorbic Acid↗

PubMedDate not supplied

Enhancement of ectopic bone formation in mice with a deficit in Fas-mediated apoptosis.

Bone formation is under the control of cytokines as well as growth factors such as bone morphogenetic proteins (BMP). This suggests the possibility that osteogenesis might be modulated by factors which also modulate the immune system. To test whether immune disorders in the host may influence bone formation, we studied BMP-induced bone formation in a C3H/HeJ strain of mice bearing a mutant gene, the lymphoproliferation gene (lpr) or the generalized lymphoproliferative disease gene (gld), both of which are known to be a Fas deletion mutant and a Fas ligand mutant, respectively, and to induce immune disorders via a deficit in Fas-mediated apoptosis. Crude BMP derived from bovine bone were injected into the muscular tissue in the femur of adult C3H/HeJ mice or C3H/HeJ mice bearing an lpr or gld gene. Quantitative analysis of the resulting ectopic bone formation by X-ray photography 2 weeks after injection revealed that the presence of either the lpr or gld gene caused a bone mass significantly larger in dimension than that seen in the wild type mice. Histological examination also revealed the different influence between these mutant genes on the level of bone formation exhibited by hyaline cartilage and bone trabeculae. Based on these results, we discussed the possible mechanisms of the enhanced ectopic bone formation under the deficit in Fas-mediated apoptosis.

Animals↗

PubMedDate not supplied

Maternal or umblical venous levels of nitrite/nitrate during pregnancy and at delivery.

OBJECTIVE: This study was intended to measure serum concentrations of nitrite plus nitrate as an index of nitric oxide synthesis, in the maternal vein during pregnancy, just after a spontaneous delivery and at the puerperium, and at an elective cesarean section, and in the umblical vein and artery. METHODS: Maternal venous sera, and umblical venous and arterial sera were collected, and serum concentrations of nitrite/nitrate were measured by an automated procedure based on the Greiss reaction after reduction of nitrate to nitrite. RESULTS: Compared to a serum concentration of nitrite/nitrate at the first trimester (12-13 weeks of pregnancy), a serum concentration of nitrite/nitrate slightly increased at the second trimester (27-28 weeks), and became maximal at the third trimester (35-36 weeks), followed by a significant decrease near the term (38-40 weeks). A serum concentration of nitrite/nitrate slightly increased just after a spontaneous delivery with labor pains, and at the puerperium to levels slightly more than that at the first trimester. Serum concentrations of nitrite/nitrate in the umblical vein and artery did not differ. They were significantly higher than a serum concentration of nitrite/nitrate in the maternal vein just after a spontaneous delivery with labor pains but not at an elective cesarean section without labor pains. CONCLUSION: A decrease in maternal serum levels of nitrite/nitrate near term may support a hypothesis that NO is one of factors responsible for the maintenance of uterine quiescence during pregnancy. Moreover, the present results suggest that NO plays some role in the feto-placental circulation during a spontaneous delivery.

Adult↗