Preparation of radioactive iodinated cholylhistamine for use in the radioimmunoassay of cholic acid

A major handicap in the development of simple and accurate radioimmunoassay procedures for bile acids has been the lack of a radioactive standard of high specific activity. To provide such a compound, we first synthesized cholylhistamine using the carbodiimide reaction. The hypothesized structure was confirmed by elemental analysis, thin-layer chromatography, infrared and mass spectral analysis. The cholylhistamine was then iodinated with 125I, using the choloramine-T method. The 125I-cholylhistamine was bound by antisera raised against a cholic acid-bovine serum albumin conjugate. This procedure should prove useful in preparing radioactive conjugates for all of the bile acids.     

Removal of carbohydrate from influenza A virus and its hemagglutinin and the effect on biological activities.

Treatment of influenza virus and its purified hemagglutining with glycosidases from Diplococcus pneumoniae, which included beta-galactosidase, beta-N-acetylglucosminidase, and endoglycosidase D, released amino and neutral sugars from the virus and these as well as large oligosaccharides from the purified hemagglutinin. The released glucosamine-containing oligosaccharides were of one discrete size. Large oligosaccharides not removed by the glycosidases were found on the virus as well as the hemagglutinin. Some oligosaccharides on the virus were inaccessible to the enzymes, since they could be removed only from the purified hemagglutinin. Approximately 50% of the hemagglutinin carbohydrates could be removed without effect on hemagglutinating activity. Similarly, removal of 20 to 25% of the carbohydrates from intact virus particles did not alter infectivity.     

Plasmodium cynomolgi: immunization of a rhesus monkey with exoerythrocytic stages cultured in autologous hepatocytes

To investigate the immune response to exoerythrocytic stages of malaria parasites, a rhesus monkey was immunized with autologous primary hepatocyte cultures infected with 7-day-old liver stage parasites of Plasmodium cynomolgi. A primary antibody response against EE stage antigens was obtained, and boosted after injection of homologous viable sporozoites. Antibodies directed against sporozoites and blood stages were also detected. The polyvalent immune response observed demonstrates the antigenicity of the liver stages and suggests their involvement in the general immune response against malaria.     

Taxonomic studies on 'Streptococcuspluton'

Strains of ' Streptococcus pluton ' isolated from honeybee larvae with European foul-brood from widely separate parts of the world represent a relatively homogeneous taxon; all are related serologically. Added cysteine or cystine make a variety of otherwise unsuitable nitrogen sources satisfactory for all strains, which all have the same fastidious culture requirements. Test strains lack respiratory quinones and possess a Group A peptidoglycan based upon lysine, primarily straight-chain and cyclopropane-ring fatty acids, and a DNA base composition of 29–30 G + C mol %. Results obtained indicate that the strains presently designated ' Strep. pluton ' should constitute the nucleus of a new genus.     

Arrangement of Integrated Avian Sarcoma Virus DNA Sequences Within the Cellular Genomes of Transformed and Revertant Mammalian Cells

We have examined the arrangement of integrated avian sarcoma virus (ASV) DNA sequences in several different avian sarcoma virus transformed mammalian cell lines, in independently isolated clones of avian sarcoma virus transformed rat liver cells, and in morphologically normal revertants of avian sarcoma virus transformed rat embryo cells. By using restriction endonuclease digestion, agarose gel electrophoresis, Southern blotting, and hybridization with labeled avian sarcoma virus complementary DNA probes, we have compared the restriction enzyme cleavage maps of integrated viral DNA and adjacent cellular DNA sequences in four different mouse and rat cell lines transformed with either Bratislava 77 or Schmidt-Ruppin strains of avian sarcoma virus. The results of these experiments indicated that the integrated viral DNA resided at a different site within the host cell genome in each transformed cell line. A similar analysis of several independently derived clones of Schmidt-Ruppin transformed rat liver cells also revealed that each clone contained a unique cellular site for the integration of proviral DNA. Examination of several morphologically normal revertants and spontaneous retransformants of Schmidt-Ruppin transformed rat embryo cells revealed that the internal arrangement and cellular integration site of viral DNA sequences was identical with that of the transformed parent cell line. The loss of the transformed phenotype in these revertant cell lines, therefore, does not appear to be the result of rearrangement or deletions either within the viral genome or in adjacent cellular DNA sequences. The data presented support a model for ASV proviral DNA integration in which recombination can occur at multiple sites within the mammalian cell genome. The integration and maintenance of at least one complete copy of the viral genome appear to be required for continuous expression of the transformed phenotype in mammalian cells.     

VARIABILITY OF SHORT-TERM CULTURES OF HeLa S-3 CELLS: CHANGES IN DNA DISTRIBUTIONS AND RATES OF DNA SYNTHESIS

DNA distributions of HeLa S-3 cells in spinner culture exhibit significant time—dependent changes. The major differences appear to occur in the S-phase region. Significant changes in the rates of DNA synthesis in several S-phase subcompartments correlated well with the changes in the DNA distributions. It is proposed that fluctuations in these rates of DNA synthesis are a reflection of the inherent instability of these abnormal, heteroploid cells.