Raised arterial pressure in parents of proteinuric insulin dependent diabetics.

Arterial pressure is raised early in the subset of insulin dependent diabetics at risk of later development of progressive renal failure, suggesting that liability to arterial hypertension may play a part in the aetiology of diabetic kidney disease. Evidence for a genetic basis was therefore sought by measuring the blood pressures of the 26 surviving parents of 17 insulin dependent diabetic patients with proteinuria and comparing them with those of the parents of 17 matched insulin dependent diabetic patients without proteinuria selected from the same cohort. Systolic and diastolic pressures were significantly higher in parents of the proteinuric (mean (SD) 161 (27)/94 (14) mm Hg) than in parents of the non-proteinuric patients (146 (21)/86 (11) mm Hg). The difference between the sample mean blood pressures was 15 mm Hg (95% confidence interval 3.3 to 26.7 mm Hg) for systolic pressure and 8 mm Hg (95% confidence interval 0.8 to 15.2 mm Hg) for diastolic pressure. These differences were independent of age, sex, and adiposity. There was a significant correlation between the mean arterial pressures in the proteinuric patients and the higher mean blood pressure in their parents. High blood pressure in non-diabetic parents may be a marker of susceptibility to clinical nephropathy in their insulin dependent diabetic offspring.     

Specificity of an HPETE peroxidase from rat PMN

The 15,000xg supernatant of sonicated rat PMN contains 5-lipoxygenase that converts arachidonic acid to 5-hydroperoxyeicosatetraenoic acid (5-HPETE) and leukotriene A4 and an HPETE peroxidase that catalyzes reduction of the 5-HPETE. The specificity of this HPETE peroxidase for peroxides, reducing agents, and inhibitors has been characterized to distinguish this enzyme from other peroxidase activities. In addition to 5-HPETE, the HPETE peroxidase will catalyze reduction of 15-hydroperoxyeicosatetraenoic acid, 13-hydroperoxyoctadecadienoic acid, and 15-hydroperoxy-8,11,13-eicosatrienoic acid, but not cumene or t-butylhydroperoxides. The HPETE peroxidase accepted 5 of 11 thiols tested as reducing agents. However, glutathione is greater than 15 times more effective than any other thiol tested. Other reducing agents, ascorbate, NADH, NADPH, phenol, p-cresol, and homovanillic acid, were not accepted by HPETE peroxidase. This enzyme is not inhibited by 10 mM KCN, 2 mM aspirin, 2 mM salicylic acid, or 0.5 mM indomethacin. When 5-[14C]HPETE is generated from [14C]arachidonic acid in the presence of unlabeled 5-HPETE and the HPETE peroxidase, the 5-[14C]HETE produced is of much lower specific activity than the [14C]arachidonic acid. This indicates that the 5-[14C]HPETE leaves the active site of 5-lipoxygenase and mixes with the unlabeled 5-HPETE in solution prior to reduction and is a kinetic demonstration that 5-lipoxygenase has no peroxidase activity. Specificity for peroxides, reducing agents, and inhibitors differentiates HPETE peroxidase from glutathione peroxidase, phospholipid-hydroperoxide glutathione peroxidase, a 12-HPETE peroxidase, and heme peroxidases. The HPETE peroxidase could be a glutathione S-transferase selective for fatty acid hydroperoxides.     

The structural mimicry of membrane sterols by tamoxifen: evidence from cholesterol coefficients and molecular-modelling for its action as a membrane anti-oxidant and an anti-cancer agent

The anti-cancer drug tamoxifen is a potent inhibitor of lipid peroxidation induced by Fe(III)-ascorbate in ox-brain phospholipid liposomes. Similar anti-oxidant effects, but with varying potencies, are also shown by 4-hydroxytamoxifen, cholesterol, ergosterol and 17-β-oestradiol. We now describe a computer-graphic fitting technique that demonstrates a structural similarity between the five compounds. In addition, we have quantified the differences (relative to cholesterol) between the anti-oxidant activities of the compounds in terms of a novel expression reffered to here as the cholesterol coefficient (C_c) Finally, we discuss how the inhibitory effect of tamoxifen on lipid peroxidation may result from a membrane stabilization that is associated with a decrease in membrane fluidity. This action may be related to the anti-proliferative effect exerted by tamoxifen on cancer and fungal cells.     

Changes in host cell membrane activities in response to adhesion of Neisseria gonorrhoeae

Physiological changes in host cell model membranes (intact human erythrocytes and ghosts) as a consequence of bacterial adhesion were studied with special reference to Neisseria gonorrhoeae. Membrane activities examined were transport of K+, Cl- ions, pyruvate kinase, Na-K-dependent ATPase, and cAMP. We found that K+ and Cl- transport were affected, more so in membranes with attached pilated (P+) organisms than in those with apilated (P-) isogenic strains. In N. gonorrhoeae and in several other species of gram-negative bacteria studied, hemagglutination titres were directly correlated with effects on anion transport, suggesting that perturbations in anion transport are an immediate result of adhesion. Of three P+ gonococcus strains tested, two depressed Na-K-ATPase activity in the membrane, indicating a possible effect on the Na-K pump. Pyruvate kinase activity associated with the membrane appeared to be stimulated by attached gonococci, again by P+ strains to higher levels than P- organisms. Clearly, some enzyme properties of host membranes are intrinsically affected by bacterial adhesion. Human polymorphonuclear neutrophils were also investigated, and with some exceptions, changes observed in leukocyte enzyme activities tended to parallel those in erythrocytes. Since hypochlorous acid production is considered to be an important microbicidal mechanism in neutrophils, interference with Cl- transport could jeopardize their role in host defense.     

Absence of sexual dimorphism in the goat: Induction of luteinizing hormone discharge in the castrated male and female and in the intersex with estradiol benzoate

Gonadectomized male (n = 5) and female (n = 5) and intact intersex goats (n = 2) were injected i.m. with 50 mug 17(beta)-estradiol benzoate (EB). After treatment, there was a transient 6- to 9-hr decrease in circulating levels of LH followed by a preovulatory-like discharge of LH in all goats. Release peaked at 12 to 18 hr after EB treatment. The magnitude of discharge and the time from treatment until peak of release were not influenced by the goat's sex. These findings suggested that the positive feedback effects of estrogen on LH release were not sexually differentiated in the goat. Since tonic concentrations of LH prior to EB treatment were not different among the groups, the studies also suggested that the intersex goats lacked the inhibitory gonadal influences on gonadotropin release that characterize intact animals.     

A comparative description of mitochondrial DNA differentiation in selected avian and other vertebrate genera

Levels of mitochondrial DNA (mtDNA) sequence divergence between species within each of several avian (Anas, Aythya, Dendroica, Melospiza, and Zonotrichia) and nonavian (Lepomis and Hyla) vertebrate genera were compared. An analysis of digestion profiles generated by 13-18 restriction endonucleases indicates little overlap in magnitude of mtDNA divergence for the avian versus nonavian taxa examined. In 55 interspecific comparisons among the avian congeners, the fraction of identical fragment lengths (F) ranged from 0.26 to 0.96 (F = 0.46), and, given certain assumptions, these translate into estimates of nucleotide sequence divergence (p) ranging from 0.007 to 0.088; in 46 comparisons among the fish and amphibian congeners, F values ranged from 0.00 to 0.36 (F = 0.09), yielding estimates of P greater than 0.070. The small mtDNA distances among avian congeners are associated with protein-electrophoretic distances (D values) less than approximately 0.2, while the mtDNA distances among assayed fish and amphibian congeners are associated with D values usually greater than 0.4. Since the conservative pattern of protein differentiation previously reported for many avian versus nonavian taxa now appears to be paralleled by a conservative pattern of mtDNA divergence, it seems increasingly likely that many avian species have shared more recent common ancestors than have their nonavian taxonomic counterparts. However, estimates of avian divergence times derived from mtDNA- and protein-calibrated clocks cannot readily be reconciled with some published dates based on limited fossil remains. If the earlier paleontological interpretations are valid, then protein and mtDNA evolution must be somewhat decelerated in birds. The empirical and conceptual issues raised by these findings are highly analogous to those in the long-standing debate about rates of molecular evolution and times of separation of ancestral hominids from African apes.      

Methods for computing the standard errors of branching points in an evolutionary tree and their application to molecular data from humans and apes

Statistical methods for computing the standard errors of the branching points of an evolutionary tree are developed. These methods are for the unweighted pair-group method-determined (UPGMA) trees reconstructed from molecular data such as amino acid sequences, nucleotide sequences, restriction-sites data, and electrophoretic distances. They were applied to data for the human, chimpanzee, gorilla, orangutan, and gibbon species. Among the four different sets of data used, DNA sequences for an 895-nucleotide segment of mitochondrial DNA (Brown et al. 1982) gave the most reliable tree, whereas electrophoretic data (Bruce and Ayala 1979) gave the least reliable one. The DNA sequence data suggested that the chimpanzee is the closest and that the gorilla is the next closest to the human species. The orangutan and gibbon are more distantly related to man than is the gorilla. This topology of the tree is in agreement with that for the tree obtained from chromosomal studies and DNA-hybridization experiments. However, the difference between the branching point for the human and the chimpanzee species and that for the gorilla species and the human-chimpanzee group is not statistically significant. In addition to this analysis, various factors that affect the accuracy of an estimated tree are discussed.