Effects of dietary cobalt on testicular structure

Adult male rats were maintained on a diet containing 265 ppm cobalt for up to 98 days. Three rats were sacrificed weekly and assayed for testicular damage by light and electron microscopy. Testicular damage was first apparent after 70 days of treatment, followed by a progressive deterioration of cell architecture and decrease in testicular volume. The degenerative changes were of a very general nature; e.g., thickening of basal lamina and basement membranes, increased packing of red blood cells in veins and arteries, formation of "giant" cells, loss of sperm tail filaments, and degeneration of sperm mitochondria. No cobalt residues could be detected by energy dispersive x-ray microanalysis. These data indicate that testicular degeneration was not a primary response to cobalt and suggest that the testes become hypoxic due both to blockage of veins and arteries by red blood cells and to changes in permeability caused by thickening of basal lamina and basement membranes.     

Characteristics of bacterium GB-2, a presumptiveCytophaga species with novel immunoregulatory properties

A Gram-negative, psychrophilic bacterium, designated GB-2, was isolated from fetal calf serum and analyzed for its morphological, physiological, and biochemical characteristics. Gliding motility, sensitivity to actinomycin D, the presence of the pigment flexirubin and cytochrome c, growth on a variety of carbohydrates, the production of acid fermentation products, and a 34.9 mol% guanine+cytosine (G+C) content of bacterial DNA indicate GB-2 to be a member either of the generaCytophaga orFlexibacter. Growth of GB-2 was optimized in a simple defined medium to facilitate isolation and characterization of bacterial products. Liquid growth of GB-2 resulted in the release of significant quantities of a macromolecule free of both endotoxin and protein into the growth supernatant, which activated the proliferation of murine lymphocytes. The relationship between this bacterium and its end-products to other species of theCytophaga/Flexibacter group is discussed.     

Free radical damage to cultured porcine aortic endothelial cells and lung fibroblasts: Modulation by culture conditions

Summary Culture conditions modulating cell damage from xanthine plus xanthine oxidase-derived partially reduced oxygen species were studied. Porcine thoracic aorta endothelial cells and porcine lung fibroblasts were maintained in monolayer culture. Cells were prelabeled with⁵¹Cr before xanthine plus xanthine oxidase exposure. Endothelial cells showed 30 to 100% more lysis than fibroblasts and thus seemed more sensitive to this oxidant stress. The effect of cell culture age, as indicated by population doubling level (PDL), was examined. Response of low PDL endothelial cells and fibroblasts subjected to oxidant stress was compared with the response of PDL 15 cells. Both low PDL endothelial cells and fibroblasts responded differently to the lytic effect of xanthine oxidase-derived free radicals than did higher PDL cells. Specific activities of the antioxidant enzymes catalase, managanese superoxide dismutase, copper-zinc superoxide dismutase, glutathione peroxidase, and glucose-6-phosphate dehydrogenase were measured in both low and high PDL fibroblasts and endothelial cells. Antioxidant enzyme specific activities could only partially explain the differences in response to oxidant stress between fibroblasts and endothelial cells and between low and high PDL cells. Cell culture medium composition modulated the rate of production, and relative proportions of xanthine plus xanthine oxidase-derived partially reduced species of oxygen, i.e. superoxide, hydrogen peroxide, and hydroxyl radical. Serum content of medium was important in modulating free radical generation; superoxide production rates decreased 32%, H₂O₂ became undetectable, and hydroxyl radical generation decreased 54% in the presence of 10% serum. The medium protein and iron content also modulated free radical generation. The data suggest that cell culture media constituents, cell type, and cell culture age greatly affect in vitro response of cells subjected to oxidant stress. Research supported by American Lung Association Fellowship Training Grant and Research Training Grant, the R. J. Reynolds Corporation, and National Institutes of Health Grants HL29784 and 1 HL 23805.     

Additive by Additive Variance with Inbreeding and Linkage

Two-locus coancestries, which provide the coefficients of the additive by additive component in the variance and covariance of relatives for a quantitative trait, were formulated generally in terms of two-locus probabilities of identity by descent for combinations of parental and recombinant gametes. Explicit expressions, with linkage, were developed for all relatives of self-fertilization, for selfed and outbred relatives and for full and half sibs from unrelated inbred parents. The relative effect of linkage on the two-locus coancestry decreases rapidly as inbreeding and relatedness of the relatives increase. It was concluded that the error caused by ignoring linkage would probably be small in the estimation of genetic variances or in the projection of selection response with self-fertilization.     

Immobilization of enzymes in porous supports: Effects of support-enzyme solution contacting

Proteins have been immobilized in porous support particles held in a fixed-bed reactor through which protein solution is continuously circulated. Changing the recirculation flow rate alters the observed immobilization kinetics and the maximum enzyme loading which can be achieved for glucose oxidase and glucoamylase on carbodiimide-treated activated carbon and for glucoamylase immobilized on CNBr-Sepharose 4B. Direct microscopic examination of FITC-labelled protein in sectioned Sepharose particles and indirect activity-loading studies with activated carbon-enzyme conjugates all indicate that immobilized enzyme is increasingly localized near the outer surface of the support particles at larger recirculation flow rates. Restricted diffusion of enzymes may be implicated in this phenomenon. These contacting effects may be significant considerations in the scaleup of processes for protein impregnation in porous supports, since apparent activity and stability of the final preparation depend on internal protein distribution.     

Generation of phenotypic helper/inducer and suppressor/cytotoxic T-cell lines from cerebrospinal fluid in multiple sclerosis

The investigation of cell-mediated events in man has been largely limited to the study of the cells in the peripheral circulation. The study of T cells from localized anatomic compartments has been difficult due to the small numbers of cells usually obtainable from these sites. Investigation of such compartmentalized responses theoretically may yield information relating to both normal immunoregulation and autoimmune diseases--information that may not be obtainable through the investigation of the circulating cellular immune system. Utilizing cerebrospinal fluid (CSF) lymphocytes from patients with multiple sclerosis as a model of compartmentalized immunologically relevant cells, the technology for the generation of long-term T-cell lines from compartments both in continuous culture and after cryopreservation and that consist of both helper/inducer and suppressor/cytotoxic phenotypes have been generated. The 10(4) to 10(5) CSF cells obtained initially from individual patients have often been expanded into greater than 10(8) total cells within 4 months. The ability to generate large, stable, cryopreservable helper and suppressor/cytotoxic T-cell lines from limited access compartments will allow for new investigative approaches into both normal immunoregulation and autoimmune diseases in man.     

Possible change in noradrenergic receptor sensitivity following methylphenidate treatment: Growth hormone and MHPG response to clonidine challenge in children with attention deficit disorder and hyperactivity

Growth hormone (GH) and 3-methoxy-4-hydroxyphenelethylene glycol (MHPG) response was measured hourly for 4 hours in 8 children with Attention Deficit Disorder with Hyperactivity (ADD+H) following an acute single-dose of clonidine. The clonidine challenge was repeated before, during, and one day after 12 weeks of treatment with methylphenidate (MPH). Before MPH treatment, the plasma growth hormone (GH) rose to 31.3 ± 4.6 (Mean ± SE) ng/ml; during MPH treatment, the GH peak was only 14.8 ± 3.2 ng/ml; one day after discontinuation of MPH, GH rose to only 20.8 ± 3.9 ng/ml. MHPG release was inhibited by clonidine in all treatment conditions but tended to be more decreased during MPH treatment. Some children with ADD+H may have hypersensitivity of the post-synaptic alpha-1 noradrenergic receptor which is diminished by MPH treatment. The extent to which these effects are pharmacological or represent a change in receptor sensitivity requires further study.     

Fluidity of a retrovirus genome.

Comparison of the genomic sequences of the Friend spleen focus-forming virus with other murine retroviral sequences indicated that the spleen focus-forming virus was derived from at least three retroviruses. The 5' end of the virus, from the primer binding site through most of gag, was derived from AKV. The rest of gag and all of pol were of uncertain origin, but were probably derived from the same xenotropic virus that gave rise to the 5' half of env. The remainder was derived from Friend murine leukemia virus. The positions of a 585-base deletion, a 6-base duplication, and a point insertion that leads to a frame shift and premature protein termination in the ecotropic 3' end of env were invariant between three spleen focus-forming virus strains, indicating that they had a single common ancestor. However, the point of crossover between xenotropic viral sequences and Friend murine leukemia virus was different in each strain, and two strains were much more closely related to each other than to the third in the xenotropic region, indicating that these strains had diverged by multiple recombinations. Furthermore, a different nucleotide comprised the single point insertion near the 3' end of env, suggesting that these viruses have an extremely high transition and transversion rate.     

The effects of a settled industrial–domestic sewage works effluent from percolating filters on the survival and growth of various stages of rainbow trout, Salmo gairdneri (Richardson)

Comparisons were made of the mortality, growth and condition factor over a 50-day period of eleutheroembryos, alevins, 2-month fry, 4-month fry and 1 + rainbow trout, Salmo gairdneri , in water of three qualities–Birmingham tap-water, 50% and 100% settled effluent from percolating filters (Minworth Effluent Treatment Works) when dissolved oxygen levels were maintained near 100% ASV.
There was no significant mortality among life stages in control tap-water but the LT50 values of life stages in both 50% effluent and 100% effluent revealed significant differences. Inter-treatment comparisons showed similar mortalities of eleutheroembryos, of 2-month fry and of 1 + fish in the three treatments but LT50 values of 4-month fry showed significant differences. Growth rates of 2-month and 4-month fry were suppressed in both effluents after 7 days and there was a significant deterioration in the K factor of these life stages after 14 days. Predicted toxicities (the sum of the proportions of the 48-h LC50 of the individual poisons to rainbow trout) were compared with the observed toxicity in 50% and 100% effluent. The relevance of in vivo testing in comparison to predictive techniques is compared.     

Epitope mapping of the human surface suppressor/cytotoxic T cell molecule Tp32

The complexity of the suppressor/cytotoxic subset marker of human T lymphocytes was demonstrated by biochemical analysis, cross-blocking experiments, phylogenetic comparisons, and functional studies. At the biochemical level, the antigen was shown to be a heteromultimer of at least three polypeptide chains covalently associated into four different higher m.w. species. Sixteen different murine monoclonal antibodies were used to map epitopes of this heteromultimeric complex. Cross-blocking experiments undertaken with six directly labeled reference antibodies identified at least seven spacially distinct epitopes. Flow microfluorometric analysis of peripheral blood lymphocytes showed two distinct subpopulations of bright and dull-stained cells that differed approximately 10-fold in antigen density. The distribution of epitopes on bright and dull cells was not uniform because in several combinations, blocking was observed on bright cells only. Studies with nonhuman primate T cells demonstrated a high degree of phylogenetic heterogeneity in the antigen. The combined cross-blocking and primate data divided the 17 antibodies into 15 groups. Each of the antibodies was capable of blocking lysis by alloreactive cytotoxic T lymphocytes, indicating that the mechanism of inhibition may not necessarily involve hindrance of an active site.