Chemistry of the alkali-labile lesion formed from iron(II) bleomycin and d(CGCTTTAAAGCG)

Two sets of products are formed from DNA upon treatment with Fe(II).bleomycin + O2. One set, which is believed to derive from a C-4' hydroperoxy derivative of the DNA deoxyribose moiety, includes the four possible base propenals, as well as DNA oligomers having deoxynucleoside 3'-(phosphoro-2"-O-glycolates) at their 3'-termini. The other set of products consists of free bases and alkali-labile lesions, the latter of which had not previously been characterized structurally. By use of the self-complementary dodecanucleotide d(CGCTTTAAAGCG) having a site modified by Fe-bleomycin three nucleotides from the 5'-end, it has been possible to characterize the alkali-labile product as a C-4' hydroxyapurinic acid. When the bleomycin-treated dodecanucleotide was treated with agents that effected decomposition of the alkali-labile lesion, products of the form CpGpx were obtained, and these proved useful for structural characterization of the alkali-labile lesion. Treatment with alkali produced CpGpx, where x was 2,4-dihydroxycyclopentenone. Alternatively, treatment with hydrazine provided a pyridazine derivative, and aqueous alkylamines led to formation of CpGp itself. The structures of all dinucleotides produced from the alkali-labile lesion were verified by direct comparison with authentic synthetic samples.

The influence of proglumide, a putative CCK antagonist, on cerebral ischemia in gerbil

Studies were conducted to clarify the possible role of CCK in cerebral ischemia and to evaluate the effects of proglumide, a competitive and reversible CCK antagonist, as a potential therapeutic or prophylactic tool in the treatment of cerebral ischemia. Proglumide at the doses of 10, 50 and 150 mg/kg was administered to gerbils before unilateral carotid ligation, and its effect on stroke index score, incidence and mortality rate was observed. Our results show that proglumide injected prior to carotid ligation at the dose of 150 mg/kg significantly reduces both incidence and mortality rate and changes the distribution of the stroke index score in gerbils. There was a significant inverse relationship between the dose of proglumide and both incidence and mortality: the greater the injection dose of proglumide, the lower the incidence and mortality. These results suggest that CCK may be involved in the pathological processes of cerebral ischemia and proglumide or related compounds prove to be effective in the pharmacological prophylaxis of ischemic brain damage.

Differences in immunogenicity indicating polymorphism of sperm antigens from mice of different inbred strains

Polymorphism of mouse sperm was investigated by analysis of immune sera generated in BALB/c female mice against sperm from 6 inbred strains. The immune sera were analyzed by immunofluorescence and Western blot techniques against sperm antigens from the 6 immunizing strains. Immunofluorescence revealed no differences in reactivity patterns or titers. However, several different reaction patterns were detected by Western blot technique which indicated that both the sperm extracts and the antisperm immune sera contained different components. Syngeneic (anti-BALB/c sperm) antisera showed far fewer reactive antibody species than allogeneic immune sera. The anti-BALB/c sera recognized an antigen of 23 kDa in sperm extracts from DBA/2J and C57BL/6 mice, and failed to react with an antigen of the same molecular weight when applied to sperm from A/J and 129/J mice, indicating antigenic differences between sperm from these inbred strains. Anti-C57BL/6 sera contained a unique antibody which reacted with an antigen of 80 kDa in all of the 6 sperm extracts, whereas others antisera did not detect this antigen. These findings indicate antigenic and immunogenic polymorphism in sperm from different inbred strains of mice.

Carotid ligation alters cholecystokinin-8 (CCK-8) immunoreactivity in gerbil brains

The unilateral or bilateral carotid arteries were ligated in gerbils used as a model of cerebral ischemia. The effect of different times of bilateral ischemia on the content of CCK-8 in fore regions of gerbil brain and the effect of 30 min of unilateral ischemia on the content of CCK-8 of the same regions in gerbils with or without neurological signs were observed. Our results show that the content of CCK-8 of cortex, basal ganglia, thalamus and hypothalamus decreased significantly. But, in brain stem it remained basically unchanged no matter whether the ischemia was unilateral or bilateral. This suggests that there is a close relationship between CCK-8 and cerebral ischemia, and raises the possibility that CCK-8 may be involved in cerebral ischemia through a yet unclear mechanism.

A cellular analysis of long-term haematopoietic damage in mice after repeated treatment with cyclophosphamide

Following repeated treatment of mice with cyclophosphamide (5 X 200 mg/kg) it was found that slight, but significant, residual marrow damage persisted for at least half the lifespan of the animals. This long-term damage occurred despite preferential sparing of those multi-potential haematopoietic cells (CFU-S) that had a high self-renewal capacity after each step of the multistep regimen and despite a smaller CFU-S kill after each successive dose. The damage was characterized by low mean numbers of CFU-S and stromal colony-forming cells (CFU-F) which were around 70% of control values. Examination of individual animals revealed that the majority had slightly subnormal numbers of CFU-S and CFU-F, with only a few suffering a more severe injury, including 8% of mice with clinical hypoplasia or myelodysplasia.

Analysis of products formed during bleomycin-mediated DNA degradation

By the use of DNA, copolymers of defined nucleotide composition, and a synthetic dodecanucleotide having putative bleomycin cleavage sites in proximity to the 5'- and 3'-termini, the products formed concomitant with DNA strand scission have been isolated and subjected to structural identification and quantitation via direct comparison with authentic synthetic samples. The products of DNA strand scission by Fe(II)-bleomycin include oligonucleotides having each of the four possible nucleoside 3'-(phosphoro-2''-O-glycolates) at their 3'-termini, as well as the four possible base propenals. At least for 3-(adenin-9'-yl)propenal and 3-(thymin-1'-yl)propenal, the products formed were exclusively of the trans configuration.

Antithrombin III activity in women with hypertension during pregnancy

Antithrombin III activity was measured prospectively in 127 pregnant women within four weeks of delivery, and the results were tabulated with respect to the clinical diagnosis of their hypertensive disorder. Plasma antithrombin III activity was significantly lower than controls in women with preeclampsia and in women with chronic hypertension and superimposed preeclampsia (P less than .001). In contrast, women with chronic hypertension alone had antithrombin III activities similar to controls. Based on discriminant analysis, an antithrombin III activity of less than 70% was selected as indicative of the preeclampsia-eclampsia syndrome. The sensitivity and specificity of plasma antithrombin III for preeclampsia was 76 and 91%, respectively. Importantly, an antithrombin III activity in excess of 70% accurately predicted the absence of preeclampsia in 89% of study patients. Although gestational ages at delivery were similar in preeclamptic women with antithrombin III activity above and below 70%, women with antithrombin III activity above 70% delivered larger infants and experienced less fetal distress during labor. These findings suggest antithrombin III measurement may be useful in the management of hypertensive pregnant patients who are unresponsive to bedrest.