The interaction of homocysteine and copper markedly inhibits the relaxation of rabbit corpus cavernosum: new risk factors for angiopathic erectile dysfunction?

OBJECTIVES: To explore whether homocysteine (HCy), an independent risk factor for atherosclerosis (the angiopathic effect of which occurs through the generation of superoxide anions and hydrogen peroxide, augmented by copper, the superoxide anions reacting with nitric oxide, NO, to produce peroxynitrite, a highly angiopathic free radical) and copper contribute to erectile dysfunction (ED) through similar mechanisms, by assessing their interactive effects on the relaxation of corpus cavernosum using organ-bath techniques. MATERIALS AND METHODS: Cavernosal smooth muscle strips were obtained from adult New Zealand White rabbits and mounted in organ baths. After precontraction with phenylephrine (100 micromol/L), relaxation responses to carbachol or sodium nitroprusside (SNP) were assessed in the presence or absence of HCy and copper. The effects of HCy and copper in the presence of superoxide dismutase or catalase were also investigated. RESULTS: HCy alone inhibited carbachol-stimulated (NO-dependent) but not SNP-stimulated relaxations (NO-independent). This effect of HCy was significantly augmented by copper, which alone had no effect. The combined effect of HCy and copper was significantly (P<0.05) reversed by superoxide dismutase or catalase. CONCLUSIONS: HCy inhibited NO-mediated cavernosal smooth muscle relaxation, an effect that was potentiated by copper and reversed by superoxide dismutase or catalase. It is therefore proposed that the effect of HCy on cavernosal smooth muscle relaxation is mediated by an interaction between NO and superoxide anions. Moreover, HCy may constitute a new risk factor for angiopathic ED.

Investigation of the inhibitory effects of homocysteine and copper on nitric oxide-mediated relaxation of rat isolated aorta.

1. Elevated plasma levels of homocysteine (HC) and copper have both been associated with the development of inflammatory vascular diseases, such as atherosclerosis. In this study, the effects of a combination of HC and copper on nitric oxide (NO)-mediated relaxation of isolated rat aortic rings were investigated. 2. Exposure to HC (10-100 microM; 30 min) had no effect on relaxation to acetylcholine (ACh; 0.01-10 microM, n=4). Pre-incubation of aortic rings with a higher concentration of HC for an extended period (1 mM; 180 min) significantly inhibited endothelium-dependent relaxation (n=4), but this inhibition was prevented by the presence of the copper chelator bathocuprione (10 microM, 180 min, n=6). 3. Exposure to HC (100 microM) and copper (10-100 microM; 30 min) caused a copper concentration-dependent inhibition of endothelium-dependent relaxation (n=4). This inhibitory effect was reduced in the presence of either superoxide dismutase (SOD; 100 u ml(-1); n=4) or catalase (100 u ml(-1); n=4), and further reduced by the presence of both enzymes (n=5). 4. HC and copper (100 microM; 30 min) significantly inhibited endothelium-independent relaxation to glyceryl trinitrate (0.01-10 microM; n=8). In contrast, HC (1 mM), alone or in combination with copper (100 microM), did not inhibit relaxation to the endothelium-independent relaxant sodium nitroprusside (0.01-10 microM; n=4). 5. These data indicate that the presence of copper greatly enhances the inhibitory actions of HC on NO-mediated relaxation of isolated aortic rings. The reduction of inhibition by catalase and SOD indicates a possible role for copper-catalyzed generation of superoxide and hydrogen peroxide leading to an increased inactivation or decreased production of endothelium-derived NO.

Integration of classical and molecular approaches of genetic selection: egg production.

Poultry breeding has demonstrated success from the use of a complex mixture of assessment tools. New proposals are regularly sought out and tested for their ability to translate data into information that enhances genetic gain from selection. Details long hidden from view are already being uncovered by molecular genetics, calling for great skill and discipline to discern and harness their real potential. Some aspects of egg production grudgingly may yield to the influence of new associations suggested from molecular work. In particular, diverse environments call for the kind of genetic variation found only under expensive multiple-location testing, longer flock production life calls for better early predictors, and new egg products call for novel measures of egg component value. In the final analysis, selection on a mix of phenotypic and molecular data is an essential step in evaluating its worth for improving a physiologically complex trait like egg production.

Endogenous viral genes influence infection with avian leukosis virus.

The influence of endogenous viral (ev) genes on avian leukosis virus (ALV) infection was studied in ALV-free white leghorn chickens exposed to chicks from ALV shedding dams. The study included four lines, each segregating for one ev gene, one line free of ev genes, and four commercial stocks segregating for a number of ev genes. Genes ev12 and ev21 that produce the complete endogenous virus were associated with significant reductions in antibody response to ALV. In commercial stocks with ev21 in all birds, both antibody response and ALV in oviducts were significantly influenced by the genomic background (stock). In one commercial stock, 37.6% of 133 birds with ev21 and only 5.8% of 120 birds without the gene were test-positive for virus in their oviducts at 180 days of age. No such differences were associated with ev1, ev3 or ev6 that do not produce complete endogenous virus. Thus, virus-producing ev genes were a predisposing factor for shedding ALV.

Nucleolar size polymorphisms in commercial layer chickens; determination of incidence, inheritance, and nucleolar sizes.

In the chicken, one chromosome pair encodes the ribosomal (r)RNA genes and two nucleoli are formed in interphase cells. The nucleolus is the site of rRNA synthesis and ribosome biogenesis. Nucleolar size polymorphisms have been detected in research strains of chickens and found to represent heterozygosity for rRNA gene copy number. The objectives of the present study were to determine whether nucleolar size polymorphisms exist in commercial chicken flocks and whether such polymorphisms are under genetic control. The occurrence of nucleolar size polymorphisms was studied in three lines of commercial layer chickens (designated A, B, and C). Nucleolar size polymorphisms were found in all three lines. However, the lines differed in the proportion of individuals exhibiting the polymorphic phenotype of two unequal-sized nucleoli (2P). The 2P phenotype, determined in successive years, was found in 10 to 14% of Line A birds, 18 to 23% of Line B birds, and 41 to 63% of Line C birds. The inheritance pattern of the nucleolar size polymorphism and nucleoli sizes were studied in Line C birds. The 2P phenotype was found to be inherited in Mendelian fashion. The large nucleolus was 1.7x and 1.6x that of the smaller nucleolus in 2P males and females, respectively, and was larger than the nucleoli of 2E birds (2E = nonpolymorphic phenotype of two equal-sized nucleoli). Total nucleolar size was greater in cells of 2P birds than in cells of 2E birds. These data suggest that the genetic basis for the large nucleolus in Line C 2P cells is a "larger than normal" rDNA cluster.

Effects of genetic strain, slow versus rapid-feathering maternal genotype, and cage density on the performance of Single Comb White Leghorns.

Two hatches involving 11,158 pullets from 22 Single Comb White Leghorn strain crosses were used in these experiments: 13 from rapid-feathering (k+/-) and 9 from slow-feathering (K/-) dams, some of which shared common genetic backgrounds; and all from 5 homozygous k+ sire types. Birds were grown intermingled within hatch, and were subsequently caged in two laying houses, one with 30.5 cm x 40.6-cm cages and the other with 40.6 cm x 30.5-cm cages, at densities of three or four birds/cage. Data were collected by cage on hen-day rate of lay from 50% production to 52 wk of age; (HD%), number of eggs produced per hen housed (EHH), percentage mortality (%M) to 52 wk of age; 35-wk BW (BW35); egg weight (EW34), specific gravity (SG34), and percentage bloodspots (BS%34) at 34 wk of age. The effects of hatches or house (H), density (D), maternal feathering type (MFT), genetic strain within MFT (GS/MFT), bank level within house (BL/H), and all possible interactions were included in the analysis model. Hatch, house, and cage type were completely confounded, so no general conclusion can be made concerning the effects of the reverse and standard cages on performance. The H effects were significant for all traits except HD%. Cage D significantly affected all traits except SG34 and BS%34. Pullets housed at three/cage weighed 26 g less, produced 5.5 more eggs that were .3 g/egg lighter, laid at a 1.7% higher hen-day rate, and had 3.6 less %M from 20 to 52 wk of age than those housed at four/cage. The MFT significantly affected all traits except %M, SG34, and BS%34. The k+/- daughters from K/- dams weighed 34 g less, produced at a 2.8% lower HD%, laid 6.9 fewer eggs, which eggs averaged .6 g/egg less than the eggs from the k+/- daughters of the k+/- dams. Interactions were in general small and nonsignificant. However, the H x GS/MFT interactions were significant for HD%, EHH, BW35, %M, and EW34 (P less than .05); their significance is suggestive of the presence of genotype x environment interactions.