Intestinal influenza: replication and characterization of influenza viruses in ducks.
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Biomedical subjects
Publications and source records attributed to W J Bean.
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Hyperextension of the fetal head in the breech presentation can be diagnosed by ultrasound. Straightening of the fetal spine and the widest diameter of the skull posterior to the long axis of the spine is diagnostic. Face presentation should also be diagnosable by these criteria.
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Eight genome RNA segments are present in both normal and von Magnustype influenza virus preparations and all species are transcribed by the virion-associated polymerase. Although the RNA polymerase activity and the amount of the three largest RNA segments are reduced in defective influenza virus preparations, these reductions do not appear to be great enough to account for the much greater loss of infectivity.
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A comparative study of the in vitro reaction kinetics of the virion RNA polymerase of influenza A strains WS and WSN was conducted to establish phenotypic differences for enzyme activity that might be exchanged as genetic markers among recombinants of these viruses. Characteristically, the RNA polymerase activity of WS virus showed an initial rate of synthesis about two- to threefold higher than that of WSN when assayed at 32 C. The two strains were also distinguishable by comparing the transcription rates of each strain at 32 and 37 C. The initial rate of WS was invariably higher at 37 than at 32 C, whereas the opposite was found with WSN. When a series of recombinants obtained from mixed infections with the WS and WSN viruses were examined for virion transcriptase activity, it was found that the two polymerase related markers behaved as properties which segregated independently of each other and of additional nonselective markers that were scored. Seven temperature-sensitive mutants of WSN virus representing distinct recombination-complementation groups were found to show a diminished transcriptase activity as compared to wild-type virus, and one of these clones (ts 24) was largely deficient for this function. None of these mutants appeared to possess a heat-liable virion polymerase.
A technique used for removal of residual biliary tract stones, too large to be withdrawn through a T-tube tract, is reported. Telescoping Teflon catheters were used in one patient to dilate the tract sufficiently to remove the stone with the Dormia type wire basket.
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