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Biomedical subjects

L Friedman

Publications and source records attributed to L Friedman.

At least 343 records · Page 19Linked to original sources
PubMed1967

Variations in the isotopic composition of carbon in urban atmospheric carbon dioxide.

Measurement of the abundance of atmospheric carbon dioxide as an indicator of air pollution has been of very limited value because of variations in urban areas in the substantial concentration of natural carbon dioxide produced from combustion and noncombustion (natural) sources. A solution to this problem is the use of precise isotopic assay of ratios of carbon-13 to carbon-12 in atmospheric carbon dioxide. There is very little variation of carbon isotopic composition in samples taken over rural or urban areas where rapid mixing and diffusion of gaseous combustion products is possible. Significant differences in this composition in samples taken at centrally located points at street level in the lower Manhattan business district show an increase in concentration of atmospheric carbon dioxide of roughly 20 percent produced primarily by automobile exhaust.

Air Pollution↗
PubMed1967

Experimental study of the pathogenicity of aspergilli for mice.

The relative virulence was determined for 14 species of aspergilli, by inoculating normal mice intravenously with graded doses of spores. Eleven were found to possess some degree of virulence, whereas three others were avirulent. Members of the Aspergillus flavus group were the only species that consistently killed mice with doses as low as 10(4) viable spores. When the in vivo fate of spores was compared for a virulent and an avirulent strain of Aspergillus, spores of the latter were cleared rapidly from the liver and spleen but grew in the kidneys and brain, producing progressive disease. Mice which inhaled spores did not succumb, but macrophages washed from their lungs contained spores. A relationship of virulence to spore characteristics such as germination time, size, shape, and external markings could not be established. Virulence could not be related to aflatoxin production inasmuch as at least one virulent strain did not produce aflatoxin in vitro.

Aerosols↗
PubMed1965

Effect of Aflatoxin B(1) on Cell Cultures.

Gabliks, J. (Massachusetts Institute of Technology, Cambridge), W. Schaeffer, L. Friedman, and G. Wogan. Effect of aflatoxin B(1) on cell cultures. J. Bacteriol. 90:720-723. 1965.-Aflatoxin B(1), a metabolite of the mold Aspergillus flavus, is toxic to cell cultures. The toxic effect is evidenced by an inhibition of growth followed by progressive granulation, rounding, and finally sloughing of the cells from the glass. In studies with embryonated eggs, duck embryos were found to be four to five times more susceptible than chick embryos. In studies on Chang liver cultures, there were decreases in cell number, protein, ribonucleic acid (RNA), and deoxyribonucleic acid (DNA) per culture with increasing aflatoxin B(1) concentrations. Since the cell number decreased and the protein, RNA, and DNA content per cell increased with increasing concentrations of aflatoxin, enlarged cells were suggested. These data are consistent with in vivo data of other workers who have found hypertrophic cells with enlarged nuclei in histological studies on the tissues of rats and ducklings fed toxic peanut meal.

Journal Article↗