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811.
The effect of histamine on exponentially growing, ascites form, Taper hepatoma cells (TLT) has been characterized by study of diamine-nucleic acid interactions. Thermal denaturation studies demonstrate that the midpoint of the melting profiles of unfractionated TLT ribosomal RNA and sheared native TLT DNA are increased 13°C and 18°C respectively when they are denatured in physiological concentrations of histamine. Similar shifts in melting profiles were observed in studies with the diamine, putrescine, and the intercalating dye ethidium bromide. The role of histamine-nucleic acid stabilization in the control of hepatoma cell differentiation is discussed. 相似文献
812.
Prenatal exposure to cocaine has been shown to produce a variety of effects on skeletal development and mineralization in humans, mice, and rats. The effects of cocaine on bone cell function and mineral metabolism pre- and postnatally are poorly understood. The present study examined the long term effects of prenatal cocaine exposure on femoral growth and mineralization in male rats. Pregnant rats were given 80 or 100 mg cocaine hydrochloride/kg during days 7-20 of gestation. At birth, body weights of pups born to these females were significantly decreased compared to normal and pair-fed controls. At the termination of the study (32 weeks), body weights of offspring from C100-treated females were still lower than normal. Long term effects of prenatal exposure to cocaine on femoral growth were most pronounced in offspring of C80-treated females. Femur dry weight, ash weight, organic matrix weight and density were significantly reduced in these animals compared to normal or pair-fed controls. The apparent osteopenic effects of prenatal exposure to cocaine suggests some long term postnatal impact on bone cell or mineral metabolism. Previous studies of cocaine use during pregnancy in humans and animals have focused primarily on physical and behavioral defects in offspring. The present findings indicate that prenatal exposure to cocaine may also have long term consequences to the skeleton. 相似文献
813.
Kevin M. Church Tamilyn A Moore Steven Luckey Mark Schaeper Kathryn Chase 《Bioorganic & medicinal chemistry letters》1993,3(12):2623-2626
One tryptophan (Trp-Net) and two tryptophan (Trp-Trp-Net) residues have been linked to the amino terminus of a minor groove binding Netropsin analogue. DNA metling measurements indicate that Trp-Trp-Net binds significantly stronger than Trp-Net to double helical DNA. Both compounds induce helix extension as measured by changes in DNA viscosity indicating the possibility of intercalation of the tryptophan indole ring. 相似文献
814.
At metaphase I synaptonemal complex (SC) material is located in a continuous but irregularly shaped bundle between sister chromatids. Only at the site of a chiasma is it present between homologous chromosomes. When the chromosomes pull apart at anaphase I the SC material becomes rearranged into poly-SCs which dissociate from the chromosomes. The observations agree with previous reports that modified SCs may function in meiotic chromosome disjunction. 相似文献
815.
Previously, we assigned the alpha A2-crystallin (Crya-1) structural gene to mouse chromosome 17 via Southern blot hybridization analysis of mouse x Chinese hamster somatic cell hybrids. Using in situ hybridization, we have now localized this gene to 17A3----B, a subchromosomal region containing several genes whose linkage relationships have been shown to be conserved on human chromosome 6. In man, however, the homologous gene (CRYA1) is located on human chromosome 21, indicating that internal rearrangements can occur within highly conserved chromosomal regions during the divergence of man and mouse. 相似文献
816.
C H Kennedy J M Dyer D F Church G W Winston W A Pryor 《Biochemical and biophysical research communications》1989,160(3):1067-1072
Eleven peroxides have been tested to determine if there is a correlation between tumor-promoting activity and the ability to stimulate radical production in mitochondria. When non-respiring rat liver mitochondria are treated with these peroxidic compounds in the presence of DMPO, ESR signals are observed from the spin trapping of carbon- and oxygen-centered radicals in the case of 4 of the 7 peroxides that are known to be tumor promoters. Enhancement of carbon-centered radical production is observed in the presence of respiratory substrate. Thus there does not appear to be a correlation between tumor-promoting activity of peroxidic compounds and radical production in mitochondria. Oxidants can act as promoters either by 1- or 2-electron oxidation pathways; both types of mechanisms may be inhibited by antioxidants, which can scavenge either radicals or electrophiles. 相似文献