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Biomedical subjects

R G Allen

Publications and source records attributed to R G Allen.

At least 145 records · Page 8Linked to original sources
PubMed1977

Swine influenza A at Fort Dix, New Jersey (January-February 1976). I. Case finding and clinical study of cases.

After the isolation of A/New Jersey/76 (Hsw1N1) influenza virus from five soldiers at Fort Dix, New Jersey, case finding was initiated by obtaining specimens for viral isolation from 95 patients with acute respiratory disease and determining antibody to influenza A/Mayo Clinic/103/74 (Hsw1N1) antigen in paired sera from 74 soldiers who had been hospitalized with acute respiratory disease. Influenza A/New Jersey virus was not isolated, but serologic studies identified eight additional soldiers as A/New Jersey influenza patients. Development of heterotypic antibody to A/Mayo Clinic antigen following infection and/or immunization with influenza A (H3N2) strains was studied and was found to occur infrequently. One of the 13 identified patients had died, and postmortem findings were consistent with viral pneumonia. Four of the 12 surviving patients had radiologic evidence of pneumonia, but clinical syndromes in all 12 were similar to those described for other influenza A infections.

Adolescent↗
PubMed1977

Swine influenza A at Fort Dix, New Jersey (January-February 1976). II. Transmission and morbidity in units with cases.

Epidemiologic study of 13 influenza A/New Jersey/76 (Hsw1N1) patients indicated that person-to-person transmission had occurred in several distinct military units. Soldiers in eight of these units (companies) were studied to determine whether they had experienced influenza A/New Jersey infections and associated acute respiratory disease. Titers of hemagglutination-inhibiting antibody to influenza A/Mayo Clinic/103/74 (Hsw1n1) antigen were determined. In seven of these eight companies, individuals with titers of greater than or equal to 1:20 were found. In these seven companies, members of platoons with cases (contact platoons) had antibody prevalences of 7%-56%, and members of platoons without cases had prevalences of 0-40%. Hospital admissions for acute respiratory disease were proportionately greater in trainees with A/Mayo Clinic antibody titers of greater than or equal to 1:20 than in trainees without antibody in five of six contact platoons studied.

Antibodies, Viral↗
PubMed1977

Swine influenza A at Fort Dix, New Jersey (January-February 1976). III. Extent of spread and duration of the outbreak.

The extent and duration of transmission of influenza A/New Jersey/76 virus at Fort Dix, New Jersey, was examined with use of titers of hemagglutination-inhibiting antibody to influenza A/Mayo Clinic/74 (HswN1) antigen as an index of infection. Five hundred ninety-three soldiers (a 9.3% sample) in basic combat training (BCT) were grouped in weekly cohorts by the date on which BCT was started. Cohorts with 11 of the 12 BCT cases of A/swine influenza began training on January 12, 19, and 26, 1976, respectively; 9%-19% of the trainees in these cohorts had titers of antibody to A/Mayo Clinic antigen of greater than or equal to 1:20. In five other cohorts without cases, which began training before January 12 or after January 26, 0-5% of trainees had titers of greater than or equal to 1:20. Titers observed in persons from military units not in BCT and in the civilian population of the post were not consistent with widespread transmission of the virus. Transmission of influenza A/New Jersey virus at Fort Dix probably occurred between mid-January and mid-February with little involvement of people outside of BCT units.

Antibodies, Viral↗
PubMed1977

Retinal damage from long-term exposure to laser radiation.

The maculae of rhesus monkeys were exposed to an argon-ion lazer operated in the TEM00 continuous wave mode at a wavelength of 514.5 nm. Both ophthalmoscopic and histopathologic evaluations of exposure sites were obtained. Threshold (ED50) values were obtained for 0.5, 5, 30, 120, and 1,000 sec. exposure times. Presence of minimum visible lesions was assessed ophthalmoscopically at both 1 hour and 24 hours after exposure. With increasing exposure times, a 24 hr. lesion-appearance criterion resulted in ED50 values too low to be consistent with a thermal damage mechanism. In contrast, exposure to neodymium laser radiation at a 1,060 nm. wavelength for 120 sec. produced only ED50 values consistent with those associated with thermal injury. These results suggest that the damage mechanisms for long-duration exposures to visible light may involve photochemical processes initiated by the interaction of visible light with the retinal photopigments.

Animals↗
PubMed1977

Histopathology of retinal lesions produced by long-term laser exposure.

The maculae of rhesus monkeys were exposed for 120/s to Nd-YAG and argon laser radiation at wavelengths of 1060 and 514.5 nm, respectively. Histopathology of lesions associated with a thermal and a nonthermal damage mechanism were compared. Differences were observed for both lesion development and retinal layers affected, depending upon the damage mechanism involved.

Animals↗
PubMed1975

Regulation of membrane lipid synthesis in Escherichia coli. Accumulation of free fatty acids of abnormal length during inhibition of phospholipid synthesis.

Glycerol starvation of an Escherichia coli glycerol auxotroph results in a specific inhibition of membrane phospholipid synthesis. Mindich ((1972) J. Bacteriol. 110, 96-102) observed only a trace accumulation of free fatty acid following glycerol deprivation. We have repeated these experiments using glycerol auxotrophs which also possess a lesion in beta oxidation. This defect was introduced in order to control fatty acid degradation. In contrast to the previous results, we find free fatty acid does accumulate during glycerol starvation. Similar results were found using beta oxidation-defective (fadE-) derivatives of both gpsA and plsB glycerol auxotrophs. Upon glycerol starvation of a plsB- fadE- strain, phospholipid synthesis is 90 percent inhibited. Following a lag of 20 to 40 min, free fatty acid synthesis begins and proceeds at a rate that steadily increases until the rate of fatty acid synthesis is equal to that found in glycerol-supplemented cultures. The accumulation of free fatty acid is the result of de novo synthesis. The average chain length of the fatty acid in the unesterified fraction is abnormally long. Two 20-carbon fatty acids, cis-13-eicosenoic acid and arachidic acid, are found in this frction. Furthermore, a greatly increased level of stearic acid and a small amount of a C-22 (behenic) acid are found in the free fatty acid fraction. These data indicate that acyl transfer into phospholipid is a major determinant of phospholipid acyl moiety chain length. Other experiments have shown that the free fatty acid fraction in glycerol-starved cells is metabolically active. This fraction turns over despite the defective beta oxidation system. Restoration of glycerol to starved cells allows the incorporation of the unesterified fatty acids into phospholipid.

Cell Membrane↗
PubMed1975

Hand, foot and mouth disease associated with coxsackievirus group B.

This study from Frankfurt, although similar to other reports with respect to clinical findings, presents further evidence of a varied etiology for hand, foot and mouth disease (HFMD). Of the 6 patients with HFMD, 5 ahd virologic evidence of coxsackievirus B5 infection, and 1 had definite evidence of coxsackievirus B2 infection. Our data suggest an etiologic association of coxsackievirus group B with HFMD.

Antibodies, Viral↗
PubMed1974

Regulation of bacterial cell division: genetic and phenotypic analysis of temperature-sensitive, multinucleate, filament-forming mutants of Escherichia.

Three mutants of Escherichia coli K-12 which form filaments during 42 C incubation have been characterized. The mutant strains AX621, AX629, and AX655 continued to grow and to synthesize deoxyribonucleic acid at 42 C for 150 to 180 min, after which time growth ceased. When cultures of the mutants were transferred from 42 to 28 C, septation of the filaments began after a 25- to 30-min period and continued at a greater than normal rate until no filaments remained. Addition of chloramphenicol at the time of transfer from 42 to 28 C prevented cell division in strain AX655 and caused lysis of strains AX621 and AX629. The temperature sensitivity mutation in each strain mapped near leu. For strain AX621, the mutation was specifically located between leu and nadC by P1 transduction. Properties of these strains are compared with those of other cell division mutants.

Azides↗
PubMed1974

Bacterial cell division regulation: characterization of the dnaH locus of Escherichia coli.

The dnaH locus is the fourth gene to be identified as required for deoxyribonucleic acid polymerization in Escherichia coli. A temperature-sensitive mutant defective in this gene exhibited an abrupt decrease in rate of deoxyribonucleic acid synthesis when shifted to 42 C. The locus mapped in the proC-purE region of the chromosome by conjugation and was co-transducible with purE. dnaH(+) is carried on the F'(13) episome and is dominant over the dnaH(-) mutation.

Cell Division↗
PubMed1974

The place of the hospital library consortium in the National Biomedical Communications Network.

The National Library of Medicine has issued a policy statement outlining expectations of more self-sufficiency at the Basic Unit level than was required during earlier programs under the Medical Library Assistance Act. A consortium of hospital libraries is presented as one viable alternative for meeting NLM's expectations that hospital libraries serve the primary and most immediate information needs of their own constituencies. The Biomedical Communications Network is reviewed so that hospital administrators and librarians will have a more thorough understanding of the system which they should now enter as contributors rather than as recipients only. A Network configuration illustrating the interaction of Basic Units functioning in consortia relationships is presented, and general areas for sharing are discussed.

Biology↗
PubMed1971

Lipoprotein inhibitor of Newcastle disease virus from chicken lung.

A lipoprotein inhibitor of Newcastle disease virus was obtained from chicken lung tissue by means of dilute alkaline extraction procedures. The inhibitor was further purified by ammonium sulfate fractionation, isoelectric precipitation, and density gradient centrifugation. The purified lipoprotein inhibited active Newcastle disease virus hemagglutination at a concentration of 2.0 mug/ml which represented a 30-fold purification over the original extract. Infection of chicken embryo fibroblasts by Newcastle disease virus was also inhibited by the purified lipoprotein, the degree of inhibition depending upon the inhibitor-to-virus ratio. Chemical analysis of the purified inhibitor provided a composition of 72% lipid, 26% protein, and 3% carbohydrate, although some compositional variation was observed from one preparation to another. The chloroform-soluble lipids were shown to contain 40 to 50% phospholipid and 10 to 20% cholesterol; of the fatty acids recovered from the saponified lipoprotein, 39% was palmitic, 22% oleic, and 17% stearic. Careful analyses of large quantities of the inhibitor revealed a small (0.84%) but significant content of sialic acid. Removal of sialic acid from the lipoprotein by means of digestion with neuraminidase produced a sharp diminution in inhibitory properties. A delipidized form of the inhibitor was obtained by ether extraction, and this material produced a single broad band of precipitate in gel immunodiffusion tests.

Animals↗
PubMed1971

Bacterial cell division regulation: physiological effects of crystal violet on Escherichia coli lon + and lon - strains.

The Escherichia coli lon(-) mutants apparently are defective in the ability to recommence cell division after temporary periods of deoxyribonucleic acid (DNA) synthesis inhibition. They are also more susceptible to cell division inhibition by the basic dye, crystal violet (CV), than are lon(+) strains. In enriched broth, the lon(+) strain continued to grow and divide in the presence of CV, but lon(-) cell division was inhibited and filamentous growth resulted. In a supplemented minimal medium containing CV, lon(-) cell division was only temporarily inhibited. There was no detectable specific effect on DNA synthesis, although CV slowed the rate of mass increase in both media. Trichloroacetic acid-insoluble lipid synthesis was preferentially inhibited in both lon(+) and lon(-) strains. In CV-containing enriched broth, diaminopimelic acid incorporation into trichloroacetic acid-insoluble compounds occurred at a rate greater than the rate of mass increase in both lon(+) and lon(-) strains. In a CV-containing supplemented minimal medium, diaminopimelic acid was incorporated to a greater extent by lon(-) cells than by lon(+) cells.

Bacterial Proteins↗