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Biomedical subjects

R M Chanock

Publications and source records attributed to R M Chanock.

At least 343 records · Page 19Linked to original sources
PubMed1969

Characterization of a newly identified mycoplasma (Mycoplasma orale type 3) from the human oropharynx.

Six mycoplasma strains, isolated under anaerobic conditions from the human oropharynx, were studied by biologic and serologic means. The strains produced nippled colonies with weak hemolytic activity for guinea pig erythrocytes on agar medium. In addition, the strains metabolized arginine with a concomitant alkaline shift in the pH of the medium but did not produce a pH shift when grown in the presence of glucose or urea. The strains failed to reduce 2-3-5 triphenyl tetrazolium and were inhibited by 0.001% methylene blue. In addition, they required fresh yeast extract for growth. When compared by several serologic methods, the strains were found to be related to each other but distinct from 23 serotypes of human, animal, and avian origin. However, one-way serologic relationships between one of the new strains and Mycoplasma orale type 1 and M. salivarium were observed when they were tested by complement fixation. Furthermore, partial relationship of one of the new strains to all of the arginine-utilizing mycoplasma species of human origin was demonstrated with the agar gel diffusion technique. Thus, the new strains appear to constitute a new mycoplasma species, for which the name M. orale type 3 is tentatively proposed. M. orale type 3 accounted for 1.4% of 437 mycoplasma isolates from the oropharynx of adults. The new species probably is a rare member of the normal mycoplasmal flora of man.

Complement Fixation Tests↗
PubMed1969

Temperature-sensitive mutants of respiratory syncytial virus.

Four conditional-lethal temperature-sensitive mutants of RS virus were detected among the progeny of 454 plaques derived from virus grown in the presence of 10(-4)m 5-fluorouridine. These mutants were stable (reversion frequency, 10(-5.0) or less and failed to produce plaques at 38 or 39 C. Plaquing efficiency was depressed 100-fold or more at 37 C. Variable suppression of growth at the restrictive temperature of 39 C was observed, ranging from 16-fold to complete suppression. The temperature-sensitive defect of three of the mutants appeared to affect functions which were expressed late in the replicative cycle. One of the mutants produced atypical nonsyncytial plaques.

Antigens↗
PubMed1969

Biophysical properties of Australia antigen.

Biophysical studies with Australia complement-fixing (CF) antigen showed it to be a particle with a buoyant density of 1.20 g/cm(3) in CsCl, a sedimentation coefficient of 110, and an average diameter of 25 nm. The CF antigen was not inactivated by ether, 1% deoxycholate, 1% Tween 80 or overnight heating at 56 C. The antigen was unstable when treated with 1% sodium dodecyl sulfate. A procedure is described for the isolation and partial purification of Australia antigen from serum by using isopycnic banding and rate separation techniques. Treatment of the 1.20 g/cm(3) Australia antigen with 1% Tween 80 yielded a minor peak of CF activity with a buoyant density of 1.39 g/cm(3) in CsCl.

Adult↗
PubMed1969

The effect of an interferon inducer on influenza virus.

The double-stranded complex of polyriboinosinic acid and polyribocytidilic acid (poly I.poly C) was shown to inhibit effectively the infection of human cells with 4 common human respiratory pathogens-influenza A2, rhinovirus 13, respiratory syncytial and parainfluenza-1 viruses. This protection was observed with levels of poly I.poly C which did not induce the release of detectable amounts of interferon. Mice could be protected from pulmonary influenza A2 infections by intranasal instillation of poly I.poly C before challenge with virus. Administration of poly I.poly C directly to the respiratory tract was found superior to systemic administration in the case of the pulmonary infection studied.

Animals↗
PubMed1969

Evaluation of influenza virus mutants for possible use in a live virus vaccine.

Two approaches to the attenuation of influenza A2 virus were studied: adaptation to a sub-optimum growth temperature and the production of temperature-sensitive mutants.A strain of A2/Hong Kong/68 virus was adapted to growth at 25 degrees C in calf kidney tissue culture, and a virus suspension was prepared for administration to volunteers after cloning by 2 terminal dilution purifications. The results indicated that the low-temperature-adapted strain had reduced infectivity for man, but was not attenuated since illness occurred when sufficient virus was administered to infect all volunteers.More encouraging results were obtained with 2 temperature-sensitive mutants of influenza A2/1965 virus. One of these mutants was unable to form plaques in calf kidney tissue culture at temperatures above 36 degrees C; the other showed restriction of plaque formation only at 38 degrees C and above. Both mutants were able to infect hamsters, but compared with the wild-type virus there was marked restriction of replication in the lungs. Prior infection of hamsters or mice with either mutant induced significant resistance to subsequent challenge with wild-type influenza A2 virus.

Animals↗
PubMed1968

Adsorption of Mycoplasma pneumoniae to neuraminic acid receptors of various cells and possible role in virulence.

Monkey, rat, and chicken tracheal epithelial cells, as well as monkey, rat, guinea pig, and chicken erythrocytes, adsorbed firmly to colonies of Mycoplasma pneumoniae and M. gallisepticum. Colonies of M. pulmonis also adsorbed erythrocytes but with less avidity than M. pneumoniae or M. gallisepticum; unlike the latter organisms, M. pulmonis did not adsorb tracheal epithelial cells. Colonies of M. orale type 1 and M. orale type 3 adsorbed only chicken red cells. Other mycoplasma species tested, including four of human origin and one of animal origin, did not adsorb red cells or epithelial cells. M. pneumoniae and M. gallisepticum appeared to attach to erythrocytes or tracheal epithelial cells by neuraminic acid receptors on these cells, whereas M. orale types 1 and 3 and M. pulmonis seemed to utilize another type or other types of receptors. Pretreatment of red cells or tracheal epithelial cells with receptor-destroying enzyme, neuraminidase, or influenza B virus removed the adsorption receptors for M. pneumoniae. Similarly, pretreatment of M. pneumoniae colonies with neuraminic acid-containing materials prevented adsorption of erythrocytes or respiratory tract cells. The adsorption sites on M. pneumoniae were specifically blocked by homologous but not heterologous antisera. This property made it possible to study the nature of the mycoplasma adsorption sites by testing the capacity of different fractions of the organism to block the action of adsorption-inhibiting antibodies. Such studies suggested that the mycoplasma binding sites were probably lipid or lipoprotein in nature. The glycerophospholipid hapten was implicated as one such site, since this serologically active hapten blocked the action of hemadsorption-inhibiting antibodies in M. pneumoniae rabbit antiserum. The affinity of M. pneumoniae for respiratory tract epithelium, unique among the mycoplasmas that infect man, may play a role in virulence, since this type of attachment provides an unusual opportunity for peroxide, secreted by the organism, to attack the tissue cell membrane without being rapidly destroyed by catalase or peroxidase present in extracellular body fluids.

Adsorption↗