Evaluation of four methods for enumeration of Vibrio parahaemolyticus.

Two membrane filter (MF) and two most-probable-number methods for enumerating Vibrio parahaemolyticus were compared. The MF methods used elevated-temperature incubations (41 and 42 degrees C) and were more specific than the most-probable-number methods (conducted at 35 degrees C). The MF method with a hydrophobic grid and a repair step was most effective.     

Incidence of Vibrio parahaemolyticus in U.S. coastal waters and oysters.

Oyster and seawater samples were collected seasonally from May 1984 through April 1985 from shellfish-growing areas in Washington, California, Texas, Louisiana, Alabama, Florida, South Carolina, Virginia, and Rhode Island which had been designated as approved or prohibited by the National Shellfish Sanitation Program. Fecal coliforms counts, aerobic plate counts, and Vibrio parahaemolyticus densities were determined for the samples. Mean V. parahaemolyticus density was more than 100 times greater in oysters than in water, whereas density of fecal coliforms was approximately 10 times higher in oysters. Seasonal and geographical distributions of V. parahaemolyticus were related to water temperature, with highest densities in samples collected in the spring and the summer along the Gulf coast. The synthetic DNA probe for thermostable direct hemolysin hybridized with 2 of 50 isolates, 1 of which was positive by the Kanagawa test.     

Species richness, environmental fluctuations, and temporal change in total community biomass

Theory and empirical results suggest that high biodiversity should often cause lower temporal variability in aggregate community properties such as total community biomass. We assembled microbial communities containing 2 to 8 species of competitors in aquatic microcosms and found that the temporal change in total community biomass was positively but insignificantly associated with diversity in a constant temperature environment. There was no evidence of any trend in variable temperature environments. Three non-exclusive mechanisms might explain the lack of a net stabilising effect of species richness on temporal change. (1) A direct destabilising effect of diversity on population level variances caused some populations to vary more when embedded in more diverse communities. (2) Similar responses of the different species to environmental variability might have limited any insurance effect of increased species richness. (3) Large differences in the population level variability of different species (i.e., unevenness) could weaken the relation between species richness and community level stability. These three mechanisms may outweigh the stabilising effects of increases in total community biomass with diversity, statistical averaging, and slightly more negative covariance in more diverse communities. Our experiment and analyses advocate for further experimental investigations of diversity-variability relations.     

Elevated temperature method for recovery of Vibrio cholerae from oysters (Crassostrea gigas)

Of 222 Vibrio cholerae isolates from diverse clinical and environmental sources, 219 produced visible growth in alkaline peptone broth when incubated overnight at 42 degrees C. In field trials conducted to compare enrichment at incubation temperatures of 42 and 35 degrees C, significantly higher rates of isolation (P less than 0.05) and recovery (P less than 0.01) of V. cholerae from oysters were observed at 42 degrees C.     

Association between teenage pregnancy rates and the age and sex of general practitioners: cross sectional survey in Trent 1994-7

This cross-sectional study examined variations in teenage pregnancy rates in the Trent region, UK, and determined possible associations with local general practice characteristics such as the age and sex of the doctors. The study sample included all pregnancies of teenagers, aged 13-19 years, between 1994 and 1997 that resulted in a hospital admission. It also included all 826 general practices in the Trent region between 1994 and 1997. Upon a multivariate analysis, lower teenage pregnancy rates were associated with the presence of a female or young doctor and more nurse time. Practices in deprived areas had higher teenage pregnancy rates. Overall, general practices with female doctors, young doctors, or more nurse time had lower teenage pregnancy rates. These findings may have implications for the mix of health professionals within primary care.     

Complementation of integrase function in HIV-1 virions.

Proviral integration is essential for HIV-1 replication and represents an important potential target for antiviral drug design. Although much is known about the integration process from studies of purified integrase (IN) protein and synthetic target DNA, provirus formation in virally infected cells remains incompletely understood since reconstituted in vitro assays do not fully reproduce in vivo integration events. We have developed a novel experimental system in which IN-mutant HIV-1 molecular clones are complemented in trans by Vpr-IN fusion proteins, thereby enabling the study of IN function in replicating viruses. Using this approach we found that (i) Vpr-linked IN is efficiently packaged into virions independent of the Gag-Pol polyprotein, (ii) fusion proteins containing a natural RT/IN processing site are cleaved by the viral protease and (iii) only the cleaved IN protein complements IN-defective HIV-1 efficiently. Vpr-mediated packaging restored IN function to a wide variety of IN-deficient HIV-1 strains including zinc finger, catalytic core and C-terminal domain mutants as well as viruses from which IN was completely deleted. Furthermore, trans complemented IN protein mediated a bona fide integration reaction, as demonstrated by the precise processing of proviral ends (5'-TG...CA-3') and the generation of an HIV-1-specific (5 bp) duplication of adjoining host sequences. Intragenic complementation between IN mutants defective in different protein domains was also observed, thereby providing the first evidence for IN multimerization in vivo.     

Evaluation of four methods for enumeration of Vibrio parahaemolyticus

Two membrane filter (MF) and two most-probable-number methods for enumerating Vibrio parahaemolyticus were compared. The MF methods used elevated-temperature incubations (41 and 42 degrees C) and were more specific than the most-probable-number methods (conducted at 35 degrees C). The MF method with a hydrophobic grid and a repair step was most effective.     

Elevated temperature method for recovery of Vibrio cholerae from oysters (Crassostrea gigas).

Of 222 Vibrio cholerae isolates from diverse clinical and environmental sources, 219 produced visible growth in alkaline peptone broth when incubated overnight at 42 degrees C. In field trials conducted to compare enrichment at incubation temperatures of 42 and 35 degrees C, significantly higher rates of isolation (P less than 0.05) and recovery (P less than 0.01) of V. cholerae from oysters were observed at 42 degrees C.     

Incidence of Vibrio parahaemolyticus in U.S. coastal waters and oysters

Oyster and seawater samples were collected seasonally from May 1984 through April 1985 from shellfish-growing areas in Washington, California, Texas, Louisiana, Alabama, Florida, South Carolina, Virginia, and Rhode Island which had been designated as approved or prohibited by the National Shellfish Sanitation Program. Fecal coliforms counts, aerobic plate counts, and Vibrio parahaemolyticus densities were determined for the samples. Mean V. parahaemolyticus density was more than 100 times greater in oysters than in water, whereas density of fecal coliforms was approximately 10 times higher in oysters. Seasonal and geographical distributions of V. parahaemolyticus were related to water temperature, with highest densities in samples collected in the spring and the summer along the Gulf coast. The synthetic DNA probe for thermostable direct hemolysin hybridized with 2 of 50 isolates, 1 of which was positive by the Kanagawa test.