Functional and mutational analysis of p19, a DNA transfer protein with muramidase activity.

Protein P19 encoded by the conjugative resistance plasmid R1 has been identified as being one member of a large family of muramidases encoded by bacteriophages and by type III and type IV secretion systems. We carried out a mutational analysis to investigate the function of protein P19 and used in vivo complementation assays to test those of several P19 mutants. The results indicated that conserved residues present in the presumed catalytic center of P19 are absolutely essential for its function in conjugation of plasmid R1 and infection by the RNA phage R17. Overexpression of protein P19 in an early growth phase resulted in a massive lysis of Escherichia coli cells in liquid culture, as indicated by a rapid and distinct decrease in cell culture densities after induction. Change of the proposed catalytic glutamate at position 44 to glutamine completely abolished this effect. P19-induced cell lysis was directly shown by transmission and scanning electron microscopy. Typically, P19-overexpressing cells showed bulges protruding from the cell surfaces. Our interpretation is that these protrusions arose from a localized and spatially confined disruption of the bacterial cell wall. To our knowledge such an effect has not previously been documented for any member of the lytic transglycosylase family. From the data presented here, we conclude that protein P19 possesses the proposed localized peptidoglycan-hydrolyzing activity. This activity would be a prerequisite for efficient penetration of the cell envelope by the DNA translocation complex encoded by the conjugative plasmid.

Biochemical evidence for an interaction of ethanol and stress: preliminary studies.

Studies were carried out to examine the interaction of stress and ethanol. Ethanol (0.5 g/kg)-treated, stressed (electric foot shocks) rats exhibited less marked elevations in plasma levels of nonesterified fatty acids and of corticosterone compared to saline-treated stressed subjects. Stress alone markedly elevated these two parameters in plasma. Ethanol treatment alone also resulted in small elevations in both parameters. Results provide support for a significant interaction of ethanol and stress, and might provide some basis for the purported stress-relieving effect of low doses of ethanol.

Cholinergic mediation of motor effects of ethanol in rats.

The role of cholinergic neurons in the motor depressant effects of ethanol was examined. Choline chloride pretreatment (30-90 mg/kg i.p.) potentiated the hypomotility produced by 2 g/kg of ethanol. Physostigmine pretreatment (0.2 mg/kg i.p.) also enhanced the motor depression produced by ethanol. Conversely, in animals pretreated with scopolamine (0.25 and 0.5 mg/kg) the depressant effect of ethanol was less. The potentiation produced by choline was not associated with changes in levels of ethanol in blood. It is concluded that cholinergic neurons are involved in the motor activity changes produced by ethanol. Such a mechanism may operate in conjunction with the dopaminergic neuronal system.

Study of the area affected by onchocerciasis in Brazil: survey of local residents.

An epidemiologic survey encompassing most of Brazil's Federal Territory of Roraima and the northern tip of Amazonas State has been carried out in an effort to define the boundaries and the epidemiologic characteristics of onchocerciasis in Brazil. This article describes results relating to human infections--including discovery of a new focus at Auaris in northern Roraima and analysis of data from tests conducted there and at various other locations. These findings lead the authors to conclude that the three known Brazilian foci represent independent influxes of the disease from neighboring Venezuela, that groups of both Yanomama and Makiritare Indians have been infected, and that various factors (including proximity of these foci and the route for Brazil's Northern Perimeter Highway) indicate the disease could pose a potential danger for other areas of Brazil.

Study of the area affected by onchocerciasis in Brazil: survey of local residents

An epidemiologic survey encompassing most of Brazil's Federal Territory of Roraima and the northern tip of Amazonas State has been carried out in an effort to define the boundaries and the epidemiologic characteristics of onchocerciasis in Brazil. This article describes results relating to human infections--including discovery of a new focus at Auaris in northern Roraima and analysis of data from tests conducted there and at various other locations. These findings lead the authors to conclude that the three known Brazilian foci represent independent influxes of the disease from neighboring Venezuela, that groups of both Yanomama and Makiritare Indians have been infected, and that various factors (including proximity of these foci and the route for Brazil's Northern Perimeter Highway) indicate the disease could pose a potential danger for other areas of Brazil (Au)

Study of the area affected by onchocerciasis in Brazil: survey of local residents

An epidemiologic survey encompassing most of Brazil's Federal Territory of Roraima and the northern tip of Amazonas State has been carried out in an effort to define the boundaries and the epidemiologic characteristics of onchocerciasis in Brazil. This article describes results relating to human infections--including discovery of a new focus at Auaris in northern Roraima and analysis of data from tests conducted there and at various other locations. These findings lead the authors to conclude that the three known Brazilian foci represent independent influxes of the disease from neighboring Venezuela, that groups of both Yanomama and Makiritare Indians have been infected, and that various factors (including proximity of these foci and the route for Brazil's Northern Perimeter Highway) indicate the disease could pose a potential danger for other areas of Brazil (Au)