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Biomedical subjects

S McGregor

Publications and source records attributed to S McGregor.

29 records · Page 2Linked to original sources
PubMed1977

Infection and vaccination of pigs with influenza A/New Jersey/8/76 (Hsw1N1) virus.

Pigs were infected and had mild signs of illness when exposed to influenza A/New Jersey/8/76 (Hsw1N1) virus. Virus was recovered for up to eight days after exposure. The virus was readily transmitted to susceptible pen mates. Vaccination with inactivated whole-virus vaccine did not provide protection against infection or disease. There was some protection against challenge when the pigs were vaccinated with a temperature-sensitive strain of influenza A/New Jersey/8/76 virus.

Animals↗
PubMed1977

Picornaviral capsid assembly: similarity of rhinovirus and enterovirus precursor subunits.

Cytoplasmic extracts of rhinovirus 1A-infected HeLa cells, pulsed 15 min with [3H]leucine, contained a 13S subunit which was rich in the capsid precursor, peptide 92. After a 30-min chase, most of the capsid-related protein sedimented in a 14S peak that contained equimolar amounts of the capsid peptides epsilon, alpha, and gamma, and some residual chain 92. The 14S subunit could be dissociated at pH 4.8 into 6S subunits containing only epsilon, alpha, and gamma chains in equal proportions, indicating that the 14S subunit is an oligomer of (epsilon gamma alpha) protomers. These subunits resemble subunits previously identified in the assembly of enteroviruses. These observations support the idea that rhinovirus assembly is basically similar to that of enteroviruses. Comparative studies on the peptide stoichiometry of the virion and the capsid precursor subunits indicate that rhinovirus 1A can contain as many as 11 immature protomers per virion.

Capsid↗
PubMed1975

Evidence for the existence of protomers in the assembly of encephalomyocarditis virus.

Two capsid precursor subunits, which sediment on glycerol gradients at 13S and 14S, respectively, have been identified in cytoplasmic extracts of encephalomyocarditis virus-infected HeLa cells. The 13S subunit, which was detected after a 10-min pulse label with -3H-labeled amino acids, contained only capsid precursor chain A (mol wt 100,000). When the 10-min pulse label in such cells was chased for 20 min, the A-containing 13S subunit in the cytoplasmic extracts was replaced by a 14S subunit containing equimolar proportions of three chains: epsilon, gamma, and alpha. This (epsilon, gamma, alpha)-containing 14S subunit could be dissociated into 6S subunits with the same polypeptide composition. The sedimentation properties and the polypeptide stoichiometry of these three precursor subunits, when compared with those of the 13S, (beta, gamma, alpha)(5), and 5S, (beta, gamma, alpha), subunits derived by acid dissociation of purified virions, suggest the following structural assignments: 13S, (A)(5); 14S, (epsilon, gamma, alpha)(5), 6S, (epsilon, gamma, alpha). The molecular weights of the individually isolated capsid chains were determined by gel filtration in 6 M guanidine hydrochloride to be: epsilon, 36,000; alpha, 32,000; beta, 29,500; gamma, 26,500; and delta, 7,800. With the exception of the delta-chain, these values are in reasonable agreement with the values previously determined by electrophoresis on sodium dodecyl sulfatepolyacrylamide gels. These data support the hypothesis that picornavirus capsids are assembled from identical protomers according to the following scheme: (A) leads to (A)(5) leads to (epsilon, gamma, alpha)(5) leads to (delta, beta, gamma, alpha)60-n(epsilon, gamma, alpha)n where n is the number of immature protomers per virion.

Amino Acids↗
PubMed1974

Picornaviridae.

Explore the source record for details and available documents.

Enterovirus↗
PubMed1974

Effects of septal lesions on latent inhibition and habituation of the orienting response in rats.

In Experiment I, the latent inhibition effect; i.e., retardation of conditioned response acquisition when a previously presented but not reinforced stimulus is subsequently used as the conditioned stimulus, was investigated in normal and septal-lesioned rats. Normal animals subjected to 30 nonreinforced CS presentations prior to CS-shock pairings, were retarded in active avoidance acquisition compared to normal animals given no nonreinforced CS presentations. The same manipulation failed to produce such a difference in septal-lesioned rats. In Experiment II, while drinking, thirsty normal and septal-lesioned rats were exposed to the same stimulus which served as CS in Experiment I. The course of suppression of on-going drinking was used as a measure of orienting response habituation. Since no differences in habituation were found between normal and septal-lesioned subjects, the deficiency of septal-lesioned rats in latent inhibition cannot be due to impairment of orienting response habituation. These results, in addition to other septal deficits, were discussed with respect to a theory of septal deficiency which suggests that septal lesions result in an impairment in situations which involve a discontinuity of response and reinforecement.

Animals↗
PubMed1971

Biophysical and biochemical studies on rhinovirus and poliovirus. II. Chemical and hydrodynamic analysis of the rhinovirion.

Chemical analysis of rhinovirus 14 revealed a ribonucleic acid (RNA) content of 29.8% and a high adenylic acid content (35%). A partial specific volume of 0.682 cm(3)/g was obtained for the rhinovirion. Rhinovirus and poliovirus had identical sedimentation coefficients of 158S. A diffusion coefficient of 1.71 x 10(-7) cm(2)/sec was consistent with a hydrated diameter of 25 nm for the rhinovirion. The calculated molecular weights of the rhinovirion and its genome were 7.1 x 10(6) and 2.1 x 10(6) daltons, respectively. Sedimentation analysis of infectious RNA confirmed the similarity of the molecular size of the poliovirus and rhinovirus genomes.

Acetates↗
PubMed1968

Biophysical studies on rhinovirus and poliovirus. I. Morphology of viral ribonucleoprotein.

An explanation has been sought for the high buoyant density of rhinoviruses, which are classified as acid-sensitive picornaviruses. Heat degradation of purified preparations of rhinovirus type 1B and poliovirus type LSc leads to the extrusion of ribonucleoprotein strands. Contour lengths of these strands were measured by electron microscopy, and the molecular weights of rhinovirus and poliovirus ribonucleic acid (RNA) were determined. Values of 2 x 10(6) and 4 x 10(6) daltons were obtained for the molecular weight of poliovirus and rhinovirus RNA, respectively. This additional nucleic acid in the rhinovirion probably accounts for the increased density and may be related to the acid sensitivity of the rhinovirus.

HeLa Cells↗