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The ability of fecal bacteria to 7alpha-dehydroxylate primary bile acids was measured in vitro by incubating stool homogenates with labeled primary bile acids, and was compared to serum cholesterol levels in 4 South African groups: Rural Bantu (50 subjects), Urban White (20), Urban Bantu (17) and Urban Coloured (16). Mean serum cholesterol levels were 137 +/- 23, 213 +/- 51, 199 +/- 62 and 206 +/- 46 mg/100 ml, respectively. (Rural Bantu significantly different.) The in vitro conversion of cholic acid by stool homogenates of Rural Bantu was significantly slower than that of the Urban Whites or the Urban Bantu was significantly slower than that of the Urban Whites or the Urban Bantu in two-hour incubations. There was no difference of conversion rates in 24-hour incubations of cholic or chenodeoxycholic acids. Gas-liquid chromatographic analysis of stool homogenates showed little difference in the distribution pattern of fecal bile acids or neutral sterols. These data suggest that the activity of the intestinal bacterial flora to convert primary bile acids was significantly reduced in the Rural Bantu as compared to the other groups, corresponding with lower serum cholesterol levels. However, by the time the stools were excreted the degree of conversion was comparable in each group.

Quantitative histopathologic and biochemical comparisons were made between polyvinyl sponge capsular and sponge tissue in the rabbit on different days after subcutaneous implantation. Up to 9 days the predominant cell type in the capsular tissue is the fibroblast and in the sponge it is the neutrophil. During this time period the sponge tissue shows lower rates of (14C) proline and (14C) cytidine incorporation and lower rates of total (14C) collagen synthesis than the surrounding capsule. Different gel electrophoretic patterns of isolated radioactive proteins are found in sponge and capsule at 6 days. These biochemical differences appear to be related to the small number of fibroblasts, relative to granulocytes present in sponges during the first 9 days after implantation. It is suggested that future biochemical investigations of the early phase of connective tissue reactions (first 9 days) in this model utilize sponge capsular tissue within 1 cm of the sponge edge instead of the sponge and its contents.

Beta glucuronidase obtained from rat inflammatory fluid and granulocytes was studied kinetically. Linear increases in activity occurred with time and enzyme concentration. No evidence of enzyme degradation during incubation was obtained. Supernatant and granulocyte enzyme activity was identical in relation to Km, and pH optima and resistance to high NaCl concentration. Minimal contributions to supernatant activity occur from plasma and red cells.

DNA synthesis in rat and rabbit polyvinyl sponge induced granulation tissue has been studied using thymidine (methyl-3H). Synthesis was determined by measurement of thymidine incorporation into cold trichloroacetic acid insoluble material and by autoradiography. Granulation tissue was removed and immediately incubated in vitro in the presence of thymidine (methyl-3H) for three hours. The label was incorporated into the nuclei of fibroblasts and, to a lesser extent, of endothelial cells. The labeled material was 93% lysable by DNase and its synthesis was inhibited by hydroxyurea and bleomycin. In this system synthesis was linear for two hours and then ceased. A marked increase in DNA synthesis occurred in tissue harvested at 44 hours after sponge implantation. This rise was confirmed by autoradiographic studies which showed an increase in nuclear labeling at two days after implantation. Neutropenia produced by injections of antineutrophil serum or cyclophosphamide failed to inhibit activation of DNA synthesis in fibroblasts or endothelial cells. Amonocytosis also had no effect on this process. Rates of thymidine incorporation into DNA and thymidine phosphates in vivo were similar to those found during in vitro incubations of granulation tissue.

Wistar rats were depleted of complement components using purified cobra venom factor (CoF) administered over a 30-hour period by intraperitoneal injection. Complement depletion was confirmed by immunodiffusion assay, hemolytic assay and inhibition of the reverse Arthus reaction. Rats depleted to below 3% of their normal serum complement level showed marked inhibition of chemotaxis into inflammatory fluid produced in polyvinyl sponges 24 hours after implantation into the dorsal subcutaneous region. Subsequent studies were done to test the effect of high local concentrations of CoF on the microcirculation, the neutrophil and the connective tissue. Local exposure of these tissues and cells to CoF in vivo had no inhibiting effect on chemotaxis. Cobra venom factor did not affect neutrophil survival in vitro or in vivo. The most likely hypothesis is that CoF works by depleting complement and that in vivo chemotaxis of the nonbacterial, nonimmune type is complement dependent to the extent of 60 to 80%. The system described allows for quantitative determination of chemotaxis in vivo.

1. Purified citrate-extracted ichthyocol obtained from carp swim bladders has been further characterized with respect to its content of certain amino acids and carbohydrate substances. 2. The degree of solubilization or dispersion of ichthyocol by solutions of certain salts maintained in the range of neutral pH and at a temperature of 0-2 degrees C. has been determined. 3. While a number of salts of monovalent cations had no significant solubilizing effects on ichthyocol, ammonium chloride in a concentration of 1 M did cause solution of the protein. 4. Sodium thiosulfate in a range of concentrations caused the solubilization of ichthyocol but was most effective in an intermediate concentration of 0.25 M. 5. Several salts of divalent cations, in particular the chlorides of calcium, magnesium, and barium, and magnesium thiosulfate in concentrations ranging from 0.3 to 1 M caused the immediate and complete solubilization of the ichthyocol. 6. Solutions of ichthyocol in calcium chloride, magnesium chloride, and sodium thiosulfate buffered or adjusted to pH 7.0, were studied with respect to intrinsic viscosity of the protein, optical rotation, ultracentrifugal sedimentation, and reconstitution into fibers. It was found in each case that the original characteristics of the collagen, as determined previously in acid solution, were maintained when the protein was dissolved in salt solutions of neutral pH. No evidence of denaturation or gelatinization could be found when ichthyocol was solubilized under the stated conditions. 7. Collagen in neutral solution with sodium thiosulfate, calcium chloride, or magnesium chloride was not attacked by trypsin as determined viscometrically at 20.0 degrees C., but was rapidly degraded by a purified bacterial collagenase.