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R A RIFKIND

Publications and source records attributed to R A RIFKIND.

17 recordsLinked to original sources
PubMed1964

ALTERATIONS IN POLYRIBOSOMES DURING ERYTHROID CELL MATURATION.

This communication presents a morphological study of the changes in ribosome content and organization which occur during the maturation of erythroid cells of the phenylhydrazine-treated rabbit. Electron micrographs of thin sectioned nucleated and non-nucleated erythroid cells have been subjected to a quantitative analysis of the distribution of ribosomes as polyribosomes of various sizes and as single ribosomes. The ribosomes of nucleated erythroid cells of marrow are virtually all arranged in the polyribosome configuration consisting of clusters of 2 to 6 individual ribosomes. These cells are the most active in the erythroid series in protein biosynthesis. During maturation to the non-nucleated reticulocyte stage, found in the circulating blood, there is a decrease in protein synthesizing capacity, a fall in total ribosome content, and, more significantly, a decrease in the number and size of polyribosomes. Maturation to the ribosome-free erythrocyte, either under in vitro or in vivo conditions, entails a further decrease in protein synthesis which correlates with a progressive disaggregation of the biosynthetically active polyribosomes into smaller clusters and inactive single ribosomes. Possible models which may account for the stability of the polyribosome and for the mechanism of polyribosome dissociation are discussed.

Animals↗
PubMed1963

FLUORESCENT, ELECTRON MICROSCOPIC, AND IMMUNOELECTROPHORETIC STUDIES OF LABELED ANTIBODIES.

Antibodies, produced in rabbits, to each of three bacterial species have been doubly labeled with fluorescein and ferritin. Irrespective of which label was conjugated to the antibody first, immunologic activity was maintained. Moreover, these preparations gave as high a degree of specificity in fluorescent and electron microscopic studies as did singly labeled antibodies. Immunoelectrophoretic analyses and other immunologic tests further confirmed that the antibodies were conjugated to both labels without loss of specific activity. The technique thus permits the relatively simple method of immunofluorescence to be used as an aid in selecting optimtum ferritin antibody conjugates for localizing of antigen at the molecular level by means of electron microscopy.

Animals↗
PubMed1962

Electron microscopic studies of experimental nephritis with ferritin-conjugated antibody. The basement membranes and cisternae of visceral epithelial cells in nephritic rat glomeruli.

Ferritin-conjugated antibody has been used to identify by electron microscopy the sites at which nephrotoxic globulins localize in rat kidney during acute experimental glomerulonephritis. Antibody was concentrated in the glomerular basement membrane and in basement membrane-like material contained in distended cisternae of the endoplasmic reticulum. These data confirm and amplify, at the ultrastructural level, the results of studies obtained with the fluorescent antibody technique, and are consistent with the hypothesis that the cisternae and capillary basement membrane possess common proteins.

Animals↗
PubMed1961

Structure and development of viruses as observed in the electron microscope. VI. ECHO virus, type 9.

Sequential stages in the development and release of ECHO 9 virus have been illustrated and described. It is suggested that viral particles differentiate and become oriented in columns upon a fine filamentous lattice at cytoplasmic template sites which are distinct from the endoplasmic reticulum. Subsequently, virus is dispersed in the peripheral cytoplasm and gains egress from the cell through rents in the plasma membrane. Complete cellular disruption with viral release may supervene. The virus consists of a 13 to 15 mmicro dense core and a poorly defined outer membrane, 22 to 24 mmicro in diameter. Incomplete forms, lacking the core, are observed in the cytoplasm but have not been seen in the extracellular space.

Animals↗
PubMed1957

Phase contrast and interferometric microscopy of the L. E. cell phenomenon.

Alterations in the cellular morphology of polymorphonuclear leukocytes and lymphocytes under the influence of serum from patients having disseminated lupus erythematosus were observed under the phase contrast microscope. These changes appear to involve the cell nucleus without significant visible incorporation of cytoplasm. In the formation of the L.E. body, there is a loss of internal nuclear structure and a subsequent nuclear swelling and extrusion of the nuclear contents from the cell to form the free L.E. body. The possible incorporation of cytoplasmic substance cannot alone account for the large mass of the L.E. body as contrasted with the parent nucleus or nuclear lobe. Measurements of dry mass by means of the interference microscope show a two and one-half-fold increment in dry mass in L.E. bodies compared to parent lymphocyte nuclei. This confirms previous cytochemical studies, and establishes that an influx of protein into the leukocyte nucleus is an integral part of the L.E. phenomenon. That the accumulation of extraneous protein within the L.E. body is simultaneous with or subsequent to a disruption of the normal structure of the leukocyte nucleus is apparent from these studies, but the pathogenesis of this alteration is as yet unknown.

Cell Nucleus↗