A pharmacokinetic basis for the efficacy of 4-amino-6-trichloroethenyl-1,3,-benzenedisulfonamide against Fasciola hepatica in the rat.
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Animals↗
Biomedical subjects
M D Schulman
Publications and source records attributed to M D Schulman.
Factors influencing rumen fermentation: effect of hydrogen on formation of propionate.
The effect of hydrogen on fermentation of lactate, pyruvate, fumarate, and succinate by resting rumen microorganisms has been investigated. Under an atmosphere of nitrogen, lactate was fermented to yield acetate as the major product (85 to 100 mole %) and propionate (0 to 17 mole %) and butyrate (0 to 3%) as secondary products. Under hydrogen, there was increased formation of both propionate and total volatile fatty acids. The amount of propionate increased 4 to 8 times and total volatile fatty acids 2.5 to 3.2 times. Propionate formation was proportional to the hydrogen concentration and reached a maximum at a partial pressure of hydrogen of .2 N/m2. With [2-carbon-14] lactate, propionate was formed via the dicarboxylic acid pathway under both nitrogen or hydrogen. Hydrogen did not affect significantly the fermentation of pyruvate or succinate. With fumarate under hydrogen, propionate and total volatile fatty acids increased 6.8 and 2 times while acetate was unchanged. The mechanism by which hydrogen exerts these effects is discussed in relation to the role of methanogenesis in the rumen.
Animals↗
D-glyceraldehyde 3-phosphate dehydrogenases of higher plants.
The d-glyceraldehyde 3-P dehydrogenases of spinach leaf, pea seed, and pea shoot were purified. The NADP and NAD-linked enzymes of either spinach leaves and pea shoots could not be separated. Changes in the ratio of NADP- to NAD-linked activity of the spinach leaf and pea shoot enzymes were observed during both purification and storage of crude extracts. The spinach leaf, pea shoot, and pea seed enzymes differ electrophoretically from each other and from the rabbit muscle enzyme. The pea seed and shoot enzymes contain bound nucleotide cofactor, resist proteolytic attack, have similar Michaelis-Menton kinetic constants and are competitively inhibited by d-sedoheptulose-7-phosphate and d-sedoheptulose 1,7-diphosphate. Charcoal removes the bound nucleotide from the pea seed enzyme but not from the pea shoot enzymes. NADP and NADPH were found to inhibit the reductive but not oxidative reaction catalyzed by the charcoal treated seed enzyme. The function of the pea shoot NADP and NAD-linked enzymes in chloroplast metabolism is discussed in regard to their location and catalytic properties. Although the NADP-linked activity can be assigned a primary, if not exclusive function in photosynthesis, the assignment of a distinct metabolic function to the NAD-linked activity cannot be made at present.
Glyceraldehyde-3-Phosphate Dehydrogenases↗