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Biomedical subjects

L R Overby

Publications and source records attributed to L R Overby.

71 records · Page 4Linked to original sources
PubMed1966

Comparison of two serologically distinct ribonucleic acid bacteriophages. I. Properties of the viral particles.

Overby, L. R. (University of Illinois, Urbana), G. H. Barlow, R. H. Doi, Monique Jacob, and S. Spiegelman. Comparison of two serologically distinct ribonucleic acid bacteriophages. I. Properties of the viral particle. J. Bacteriol. 91:442-448. 1966.-Two ribonucleic acid (RNA) coliphages, MS-2 and Qbeta, have been characterized physically and serologically. MS-2 has an S(20, w) value of 79, a molecular weight of 3.6 x 10(6), a density of 1.422, and pH 3.9 as its isoelectric point. Qbeta has an S(20, w) of 84, a molecular weight of 4.2 x 10(6), a density of 1.439, and an isoelectric point at pH 5.3. One host (Escherichia coli A-19) permits a distinction between the two on the basis of a marked difference in plaque size. They are distinct immunochemically, no serological cross-reaction being detectable.

Centrifugation↗
PubMed1966

Comparison of two serologically distinct ribonucleic acid bacteriophages. II. Properties of the nucleic acids and coat proteins.

Overby, L. R. (University of Illinois, Urbana), G. H. Barlow, R. H. Doi, Monique Jacob, and S. Spiegelman. Comparison of two serologically distinct ribonucleic acid bacteriophages. II. Properties of the nucleic acids and coat proteins. J. Bacteriol. 92:739-745. 1966.-The ribonucleic acid (RNA) molecules and coat proteins of two RNA coliphages, MS-2 and Qbeta, have been characterized. MS-2 RNA shows an S(20,w) of 25.8 and a molecular weight by light scattering of 10(6). The corresponding parameters for Qbeta-RNA were 28.9 and 0.9 x 10(6). A difference in base composition was reflected in the adenine-uracil ratio, which was 0.95 for MS-2 and 0.75 for Qbeta. The two RNA preparations are readily separated by chromatography on columns of methylated albumin. Both gave identical bouyant densities in cesium sulfate of 1.64 g/ml. The coat protein subunits were of similar molecular weights: 15,500 (Qbeta) and 14,000 (MS-2). They differed, however, in that the Qbeta-protein lacked tryptophan and histidine, whereas the MS-2 protein lacked only histidine.

Adenine↗
PubMedDate not supplied

Serodiagnosis of recent hepatitis B infection by IgM class anti-HBc.

The time sequence, relative reactivity, and persistence of anti-HBc IgM were assessed in patients with HBsAg-positive viral hepatitis. A solid-phase immunoassay was developed using the IgM capture procedure with anti-mu-coated polystyrene beads. HBcAg was purified from serum Dane particles and used as a probe with 125I-labeled anti-HBc IgG. This immunoassay exhibited a pronounced prozoning phenomenon, and relative titers of sera differed widely depending upon the dilution of serum tested. When all sera were tested at 1:5,000 dilution, results were comparable in different patient groups. Anti-HBc IgM persisted at detectable levels for up to 2 years, and it was necessary to establish relative titers to discriminate current from remote infections. A cut-off assay value was established, and in 12 cases of acute hepatitis B virus (HBV) infection, antibody exceeded this value for about 6 months after onset of HBs antigenemia. A similar profile of anti-HBc IgM persistence was observed in seven patients who developed an HBsAg chronic carrier state. Long-term viral replication did not sustain elevated IgM class-specific antibody levels. The studies suggest that anti-HBc IgM analyses may be useful for differentiating recent and current HBV infections from remote infections, eliminating HBV as the agent for non-A, non-B hepatitis in asymptomatic HBsAg carriers, and detecting HBV as the etiologic agent during silent (HBsAg negative) infections.

Antibodies, Viral↗
PubMedDate not supplied

Non-A, non-B hepatitis: a prospective study of a hemodialysis outbreak with evaluation of a serologic marker in patients and staff.

An outbreak of non-A, non-B hepatitis (NANBH) in a hemodialysis unit was prospectively studied and the clinical, biochemical, and serologic events were correlated with an experimental immunodiffusion assay for serum antigen and antibody. One hundred sixteen subjects (76 dialysis patients and 40 staff members) were studied over an 8-month period. Hepatitis was defined as two consecutive SGPT levels greater than two times the upper limit of normal occurring in two separate samples drawn greater than 7 days apart in the absence of other likely causes of liver disease. Weekly serum specimens were obtained and tested for SGPT, SGOT, alkaline phosphatase, bilirubin HBsAg, anti-HBc, anti-HBs, total anti-HAV, and anti-HAV IgM by commercial reagents, and for antigen and antibody by agar gel diffusion using reference reagents previously obtained from well-documented posttransfusion NANBH patients. Clinical evaluations were performed three times per week. Thirty patients and none of the staff developed NANBH. The NANBH patients were asymptomatic, except for two patients with jaundice. Fifteen of the 30 patients were positive for antigen which was detectable in at least one serum collected during the acute phase. Six patients and 10 staff without clinical NANBH or abnormal serology had antigen. Antigenemia was also observed in three patients with acute hepatitis B, with chronic hepatitis B in one patient and with alcoholic hepatitis in one patient. Thus, an antigen was detected in a high proportion of patients during the acute phase of NANBH, and it was also found in exposed patients who had other liver diseases.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗