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J R OVERMAN

Publications and source records attributed to J R OVERMAN.

At least 19 recordsLinked to original sources
PubMed1963

ELECTRON MICROSCOPY OF CYTOPLASMIC STRUCTURES IN FACULTATIVE AND ANAEROBIC ACTINOMYCES.

Overman, John R. (Duke University Medical Center, Durham, N.C.) and Leo Pine. Electron microscopy of cytoplasmic structures in facultative and anaerobic Actinomyces. J. Bacteriol. 86:656-665. 1963.-Electron microscopy of cytoplasmic complexes and the cytoplasmic fine structure of Actinomyces bovis, A. israelii, A. naeslundii, and A. propionicus demonstrated marked differences among these four species. Also included in the present study was Lactobacillus bifidus, an organism closely related to the Actinomyces species. A relatively small and compact cytoplasmic membrane complex of A. propionicus was unique in its morphology. Membrane structures of A. naeslundii and A. israelii were relatively large and consisted of coils of various sizes of the cytoplasmic membrane. No membrane complexes were found in L. bifidus or A. bovis. Measurements of cell-wall thickness indicated a significant difference between A. bovis and A. israelii. On the basis of general morphology, cell-wall thickness, and cytoplasmic membrane complexes, A. bovis and A. israelii appear to be distinct species. The relation of the fine structure complexity to phylogenetic position of these organisms is considered.

Actinomyces↗
PubMed1959

Ratios of vaccinia virus particles to virus infectious units; studies of ratio changes during growth and adaptation in eggs, guinea pigs, and rabbits.

Total virus particle counts, infectivity titrations and the ratios between particles and infective units have been determined for vaccinia virus infected tissues. Growth curves of vaccinia in the chorioallantoic membrane are characterized by relatively low ratios from 1 to 4 days after inoculation and a marked rise in the ratio at more prolonged intervals. Ratio determinations of vaccinia virus passages in the egg, rabbit skin, and guinea pig skin have been made to study the phenomenon of adaptation in different hosts. The embryonated egg chorioallantoic membrane shows no variation in the ratio of particles to infectious units during passage and it is concluded that this host is completely susceptible to vaccinia. During adaptive passages on the skin of rabbits and guinea pigs relatively large amounts of non-infective virus appear as indicated by a rise in the particle-infectivity ratios. The extent of ratio increase appears related to the general resistance of the host to the virus. Finally, treatment of crude tissue extracts with sonic vibration is described as an aid in dispersing the virus particles for quantitative particle counts.

Animals↗