Biomedical subjects

K HUMMELER

Publications and source records attributed to K HUMMELER.

At least 19 recordsLinked to original sources

PubMed1965

CYTOCHEMICAL AND ELECTRON MICROSCOPICAL OBSERVATIONS ON THE PRESENCE AND ORIGIN OF ADENOSINE TRIPHOSPHATASE-LIKE ACTIVITY AT THE SURFACE OF TWO MYXOVIRUSES.

Dawson, C. R. (The Middlesex Hospital Medical School, London, England), M. A. Epstein, and K. Hummeler. Cytochemical and electron microscopical observations on the presence and origin of adenosine triphosphatase-like activity at the surface of two myxoviruses. J. Bacteriol. 89:1526-1532. 1965.-HeLa cells infected with either fowl plague virus (FPV) or Newcastle disease virus (NDV) were examined in thin sections by electron microscopy. Preparations were studied both after direct fixation and embedding and after the application of cytochemical staining for enzymes splitting adenosine triphosphate. Viral particles were identified by their size and characteristic structure, and were found to form at the cell surface by budding out through structurally altered plasmalemma. After cytochemical staining for adenosine triphosphatase activity, extracellular FPV or NDV particles lying close against cell membranes with enzyme activity likewise carried this function, whereas those particles which were associated with cell surfaces without reaction product were themselves free from it. This correspondence between enzyme function in cell membranes and the outer viral membranes of newly formed particles adjacent to them indicates that surface enzymatic capability of the host cell survives even when the cell membrane undergoes morphological and antigenic alteration into myxovirus outer membrane.

Adenosine Triphosphatases↗

PubMed1965

CYTOPATHOGENIC MYCOPLASMAS ASSOCIATED WITH TWO HUMAN TUMORS. II. MORPHOLOGICAL ASPECTS.

Hummeler, K. (The Children's Hospital of Philadelphia, Philadelphia, Pa.), D. Armstrong, and N. Tomassini. Cytopathogenic mycoplasmas associated with two human tumors. II. Morphological aspects. J. Bacteriol. 90:511-516. 1965.-Cytopathic effects (CPE) produced in HeLa cell cultures by two strains of mycoplasmas (F-11 and F-12) were studied by light and electron microscopy. CPE, which was marked by cytoplasmic vacuolization, did not appear to depend on intracellular mycoplasma infection. The cytopathogenic mycoplasmas appeared to be similar, both morphologically and in their intra- and extracellular distribution, to noncytopathogenic mycoplasmas previously studied by others. The probability that the CPE is related to depletion of essential nutrients is discussed, and the fine structure of the mycoplasmas is described.

Cytoplasm↗

PubMed1965

ULTRASTRUCTURE OF A MYCOPLASMA (NEGRONI) ISOLATED FROM HUMAN LEUKEMIA.

Hummeler, Klaus (The Children's Hospital of Philadelphia, Philadelphia, Pa.), Natale Tomassini, and Leonard Hayflick. Ultrastructure of a mycoplasma (Negroni) isolated from human leukemia. J. Bacteriol. 90:517-523. 1965.-A strain of mycoplasma isolated in tissue cultures from human leukemic bone marrow was cultivated in cell-free media for 23 passages. Concentrates of broth cultures were investigated under the electron microscope in thin sections and negative contrast. The ultrastructure of the mature mycoplasma cells and their elementary bodies is described. It was found that the elementary bodies, particularly in the negative contrast preparations, bear a close resemblance to viruslike particles seen in tissues and plasmas of leukemic patients.

Bone Marrow Cells↗

PubMed1964

THE ENTRY AND DISTRIBUTION OF HERPES VIRUS AND COLLOIDAL GOLD IN HELA CELLS AFTER CONTACT IN SUSPENSION.

The way in which herpes virus of a well adapted strain penetrates susceptible HeLa cells has been investigated using thin sectioning techniques for electron microscopy. Mature virus particles and cells were mixed together in suspension cultures for 15, 30, 60, or 120 minutes so that the stages in virus uptake could be followed in sequence. The ingestion of particles of colloidal gold by HeLa cells under similar conditions was studied for comparison in parallel experiments. After 15 minutes' contact, the mature virus was found adsorbed on the surface of the cells but separated from them by a narrow gap in which phosphotungstic acid staining was sometimes able to reveal an extraneous coat which appeared as an amorphous layer on the outer aspect of the plasma membrane. When mixing continued for longer the particles were present in deep invaginations or actual cytoplasmic vacuoles, with their outer layers in various stages of stripping and digestion. The stripped, naked, central portion of the virus was occasionally found in these vacuoles but was more commonly free in the cytoplasmic matrix; the mode of transition between these sites could not be determined. Where contact continued for 2 hours these phenomena were much less frequently observed. The larger particles of colloidal gold were ingested in the same way as the virus, but smaller ones were taken up in micropinocytosis vesicles. The gold passed through membrane-bounded cytoplasmic spaces to accumulate in vacuoles from which, in contrast to herpes particles, it did not escape. These findings are discussed, and considered with particular reference to their bearing on the initiation of infection, the uptake and disposal of particles by cells, and the influence on the latter of virus morphology.

Cytoplasm↗

PubMed1964