Subnanometer-resolution structures of the grass carp reovirus core and virion.

Grass carp reovirus (GCRV) is a member of the Aquareovirus genus of the family Reoviridae, a large family of double-stranded RNA (dsRNA) viruses infecting plants, insects, fishes and mammals. We report the first subnanometer-resolution three-dimensional structures of both GCRV core and virion by cryoelectron microscopy. These structures have allowed the delineation of interactions among the over 1000 molecules in this enormous macromolecular machine and a detailed comparison with other dsRNA viruses at the secondary-structure level. The GCRV core structure shows that the inner proteins have strong structural similarities with those of orthoreoviruses even at the level of secondary-structure elements, indicating that the structures involved in viral dsRNA interaction and transcription are highly conserved. In contrast, the level of similarity in structures decreases in the proteins situated in the outer layers of the virion. The proteins involved in host recognition and attachment exhibit the least similarities to other members of Reoviridae. Furthermore, in GCRV, the RNA-translocating turrets are in an open state and lack a counterpart for the sigma1 protein situated on top of the close turrets observed in mammalian orthoreovirus. Interestingly, the distribution and the organization of GCRV core proteins resemble those of the cytoplasmic polyhedrosis virus, a cypovirus and the structurally simplest member of the Reoviridae family. Our results suggest that GCRV occupies a unique structure niche between the simpler cypoviruses and the considerably more complex mammalian orthoreovirus, thus providing an important model for understanding the structural and functional conservation and diversity of this enormous family of dsRNA viruses.

ANAPHYLACTICALLY - MEDIATED EPITHELIAL CHLORINE ION SECRETORY RESPONSE INISOLATED JEJUNUM OF PARASITIZED GUINEA PIGS (TRICHINELLA SPIRALIS)

Electrophysiological studies were conducted to test the hypothesis that alterations in intestinal epithelial function are associated with immunological responses directed against the enteric parasite, Trichinella spirals. Trichinella antigens were used to challenge sensitized jejunum from infected guinea pigs while monitoring ion transport properties of the tissue in an Ussing-type chamber. The addition of antigen caused increases in transepithelial PD and I(,sc) that were rapidly induced, peaked at 1.5 to 2 min after antigen-challenge, and lasted 10 to 20 min thereafter. The increase in I(,sc) ((DELTA)I(,sc)) varied in a dose-dependent manner until a maximal increase of 40 (mu)A/cm('2) was obtained by the addition of 13 (mu)g of antigenic protein per ml of serosal fluid in the Ussing chamber. Trichinella antigen did not elicit alterations in either PD or I(,sc) of nonimmune tissue. Jejunal tissue from guinea pigs immunized with ovalbumin according to a protocol that stimulated homocytotropic antibody production responded electrically to challenge with ovalbumin but not trichinella antigen. Jejunal tissue which was passively sensitized with immune serum having a passive cutaneous anaphylaxis (PCA) titer of 32 for both IgE and IgG(,1) anti-trichinella anti-bodies responded electrically after exposure to trichinella antigen. Heat treatment of immune serum abolished the anti-trichinella IgE titer as determined by the PCA test but did not decrease either the electrical response of passively sensitized tissue to antigen or the anaphylactically mediated intestinal smooth muscle contractile response to antigen in the classical Schultz-Dale assay. These results strongly support the hypothesis that immunological responses directed against Trichinella Spiralis alter intestinal epithelial function and suggest that immediate hypersensitivity is the immunological basis of the response.^ Additional studies were performed to test the hypothesis that histamine and prostaglandins that are released from mucosal mast cells during IgE or IgG(,1) - antigen stimulated degranulation mediate electrophysiological changes in the intestinal epithelium that are reflective of Cl('-) secretion and mediated intracellularly by cAMP. Pharmacological and biochemical studies were performed to determine the physiological messengers and ionic basis of electrical alterations in small intestinal epithelium of the guinea pig during in vitro anaphylaxis. Results suggest that Cl('-) secretion mediated, in part, by cAMP contributes to antigen-induced jejunal ion transport changes and that histamine and prostaglandins are involved in eliciting epithelial responses. ^

Analyses of maternal and child mortality rates of five West African countries: Cote d'Ivoire, Guinea, Liberia, Senegal, Sierra Leone

After traveling to a small country in West Africa last summer, I became interested in learning more about the maternal, infant, and child death rates of that particular region of the continent. For the purposes of this paper I limited the number of countries that would be included in this research to five: Cote d'Ivoire, Guinea, Liberia, Senegal, and Sierra Leone. There are three hypotheses that were considered when conducting the research for this paper. The first was that there is no difference in the under five mortality rates for Cote d'Ivoire, Guinea, Liberia, Senegal, and Sierra Leone. The second hypothesis was that there is no difference in the female literacy rates for Cote d'Ivoire, Guinea, Liberia, Senegal, and Sierra Leone. The final hypothesis was that there is no difference in the male literacy rates for Cote d'Ivoire, Guinea, Liberia, Senegal, and Sierra Leone. The data used were collected from publicly available sources that include the CIA World Factbook, the WHO website, the UNICEF website, the Penn World Data table, and the World Bank website. The p-values that were calculated for all three hypotheses were found to be very significant, and all three of the null hypotheses were rejected. ^

Effects of asbestos and silica on superoxide anion production in the guinea pig alveolar macrophage

Asbestos and silica are important industrial hazards. Exposure to these dusts can result in pulmonary fibrosis and, in the case of asbestos, cancer. Although the hazards of asbestos and silica exposure have long been known, the pathogenesis of dust-related disease is not well understood. Both silica and asbestos are thought to alter the function of the alveolar macrophage, but the nature of the biochemical alteration is unknown. Therefore, this study examined the effect of asbestos and silica on the activation pathway of the guinea pig alveolar macrophage. Activation of macrophages by physiological agents results in stimulation of phospholipase C causing phosphatidyl inositol turnover and intracellular calcium mobilization. Phosphatidyl inositol turnover produces diacylglycerol which activates protein kinase C causing superoxide anion production.^ Chrysotile stimulated alveolar macrophages to produce superoxide anion. This stimulation proceeded via phospholipase C, since chrysotile stimulated phosphatidyl inositol turnover and intracellular calcium mobilization. The possible involvement of a coupling protein was evaluated by pretreating cells with pertussis toxin. Pertussis toxin pretreatment partially inhibited chrysotile stimulation, suggesting that chrysotile activates a coupling protein in an non-classical manner. Potential binding sites for chrysotile stimulation were examined using a series of nine lectins. Chrysotile-stimulated superoxide anion production was blocked by pretreatment with lectins which bound to N-acetylglucosamine, but not by lectins which bound to mannose, fucose, or N-acetylgalactosamine. In addition, incubation with the N-acetylglucosamine polymer, chitin, inhibited chrysotile-stimulated superoxide anion production, suggesting that chrysotile stimulated superoxide anion production by binding to N-acetylglucosamine residues.^ On the other hand, silica did not stimulate superoxide anion production. The effect of silica on agonist stimulation of this pathway was examined using two stimulants of superoxide anion production, N-formyl-nle-leu-phe (FNLP, which stimulates through phospholipase C) and phorbol-12,13-dibutyrate (which directly activates protein kinase C). Sublethal doses of silica inhibited FNLP-stimulated superoxide anion production, but did not affect phorbol-12,13-dibutyrate-stimulated superoxide anion production, suggesting that the site of inhibition precedes protein kinase C. This inhibition was not due to cell membrane damage, since cell permeability to calcium-45 and rubidium-86 was not increased. It is concluded that chrysotile binds to N-acetylglucosamine residues on macrophage surface glycoproteins to stimulate the physiological pathway resulting in superoxide anion production. In contrast, silica does not stimulate superoxide anion production, but it did inhibit FNLP-stimulated superoxide anion production. ^

SOCIO-ENVIRONMENTAL FACTORS ASSOCIATED WITH THE DISTRIBUTION OF DRACUNCULUS MEDINENSIS (GUINEA WORM DISEASE) AND SUGGESTED METHODS FOR CONTROL, IBARAPA, NIGERIA, 1982 (AFRICA)

A population-based cross-sectional survey of socio-environmental factors associated with the prevalence of Dracunculus medinensis (guinea worm disease) was conducted in Idere, a rural agricultural community in Ibarapa, Oyo state, Nigeria, during 1982.^ The epidemiologic data were collected by household interview of all 501 households. The environmental data were collected by analysis of water samples collected from all domestic water sources and rainfall records.^ The specific objectives of this research were to: (a) Describe the prevalence of guinea worm disease in Idere during 1982 by age, sex, area of residence, drinking water source, religion and weekly amount of money spent by the household to collect potable drinking water. (b) Compare the characteristics of cases with non-cases of guinea worm in order to identify factors associated with high risk of infection. (c) Investigate domestic water sources for the distribution of Cyclops. (d) Determine the extent of potable water shortage with a view to identifying factors responsible for such shortage in the community. (e) Describe the effects of guinea worm on school attendance during 1980/1982 school years by class and location of school from piped water supply.^ The findings of this research indicate that during 1982, 31.8 percent of Idere's 6,527 residents experienced guinea worm infection, with higher prevalence of infection recorded in males in their most productive years and females in their teenage years. The role of sex and age to risk of higher infection rate was explained in the context of water related exposure and water intake due to dehydration from physical occupational actitives of subgroups.^ Potable water available to residents was considerably below the minimum recommended by WHO for tropical climates, with sixty-eight percent of water needs of the residents coming from unprotected surface water which harbour Cyclops, the obligatory intermediate host of Dracunculus medinensis. An association was found between periods of relative high density of Cyclops in domestic water and rainfall.^ Impact of guinea worm infection on educational activities was considerable and its implications were discussed, including the implications of the research findings in relation to control of guinea worm disease in Ibarapa. ^

Effects of salinity, temperature and cadmium stress on cadmium -binding protein in the grass shrimp, {\it Palaemonetes pugio}

The combined effects of salinity, temperature and cadmium stress on survival and adaptation through cadmium-binding protein (CdBP) accumulation were studied in the grass shrimp, Palaemonetes pugio. In 96-hour bioassays, shrimp were exposed to zero or one of three levels of cadmium, under one of six different salinity (15, 25, or 35$\perthous$) and temperature (20 or 30$\sp\circ$C) regimes. CdBP concentrations were quantified in survivors from the 24 exposure groups. Salinity and temperature did not affect survivorship unless the shrimp were also exposed to cadmium. Grass shrimp were most sensitive to cadmium at low salinity-high temperature, and least sensitive at high salinity-low temperature. The incidence of cadmium-associated black lesions in gill tissue was influenced by salinity and temperature stress. P. pugio produced a 10,000 dalton metallothionein-like CdBP when exposed to at least 0.1 mg Cd$\sp{2+}$/L for 96 hours. Accumulation of CdBP was increased with increases in the exposure cadmium level, increases in temperature and decreases in salinity, independently and in conjunction with one another. Maximum CdBP concentrations occurred in grass shrimp that survived the salinity-temperature-cadmium conditions creating maximum stress as measured by highest mortality, not necessarily in shrimp exposed to the highest cadmium levels. The potential utility of this method as a monitor of physiological stress in estuarine biota inhabiting metal-polluted environments is discussed. ^