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Biomedical subjects

P B Hamilton

Publications and source records attributed to P B Hamilton.

At least 181 records · Page 10Linked to original sources
PubMed1969

Glucose catabolism in Rhizobium japonicum.

Glucose catabolism in Rhizobium japonicum ATCC 10324 was investigated by the radiorespirometric method and by assaying for key enzymes of the major energy-yielding pathways. Specifically labeled glucose gave the following results for resting cells, with values expressed as per cent (14)CO(2) evolution: C-1=59%, C-2=51%, C-3=45%, C-4=59%, and C-6=43%. These values indicate that glucose was degraded by the Entner-Doudoroff pathway alone. Cells which grew in glucose-yeast extract-salts medium gave essentially the same pattern except for retardation of the C-6 carbon. The rates were: C-1=54%, C-2=42%, C-3=51%, C-4=59%, and C-6=32%. Hexokinase, glucose-6-phosphate dehydrogenase, transketolase, and an enzyme system which produces pyruvate from 6-phosphogluconate were found to be present in these cells. No 6-phosphogluconate dehydrogenase was detected. Oxidation of specifically labeled pyruvate gave the following (14)CO(2) evolution pattern: C-1=78%, C-2=48%, and C-3=37%; the pattern from acetate was C-1=73%; and C-2=56%. Oxidation of glutamate showed the preferential rate of (14)CO(2) evolution to be C-1 > C-2=C-5 > C-3, 4, whereas a higher yield of (14)CO(2) was obtained from the C-1 and C-4 carbons of succinate than from the C-2 and C-3 carbons. These data are consistent with the operation of the Entner-Doudoroff pathway and tricarboxylic acid cycle as the catabolic pathways of glucose oxidation in R. japonicum.

Acetates↗
PubMed1968

Murine Toxicity of Cochliobolus carbonum.

Seventeen wild-type strains of the phytopathogenic fungus Cochliobolus carbonum, tested by intraperitoneal injection into mice, were lethal within 48 hr. The lethal effect appeared to be a toxic rather than an infectious process, because death occurred within 3 hr after injection of two of the isolates and heat-killed cultures were lethal. Assays of ascospore progeny from two crosses involving three isolates indicated that the toxic metabolites were under genetic control and quantitative regulation. Studies of the toxicological, cultural, and chemical characteristics of these three strains indicated that more than one murine toxin was present.

Journal Article↗
PubMed1968

Murine toxicit of Agrobacterium tumefaciens.

Eleven strains of the crown gall organism, Agrobacterium tumefaciens, tested by intraperitoneal injection into mice, were lethal within 48 hr. Five other species had some lethal strains. The lethal effect of A. tumefaciens appeared to be the result of a toxic rather than an infectious process, since histopathological anomalies were not found in mice injected with live cultures and since heat-killed cultures were lethal. The murine toxin disappeared when A. tumefaciens was grown at 36 C and reappeared when the organism was subsequently incubated below 30 C. The murine toxin itself was not inactivated by exposure to 100 C for 30 min. The toxin was associated with the cells and was not excreted into the medium. Centrifugal fractionation revealed that the toxin was associated with the smaller cells in 3-day stationary-phase cultures. These data suggested a possible relationship between toxin production and the production of the agents responsible for the initiation of plant tumors.

Animals↗
PubMedDate not supplied

Induced systemic candidiasis in young broiler chickens.

Systemic candidiasis was induced in broiler chickens 14 days old by intravenous injection of a suspension of viable Candida albicans cells. Injection resulted in decreased body weight, moderate mortality, swollen and reddened livers and kidneys, pancreatitis, and disturbances of the nervous system. Three types of neutral disturbances were observed: 1) extreme opisthotonus with spasmodic tremors; 2) extreme torticollis with cranial rotation of 270 degrees: and 3) extreme torticolis which resulted in the head being drawn in a medial-ventral direction. None to 50% of the inoculated birds exhibited these neural disturbances, depending on the isolant of C. albicans used. Microbiological examination of internal organs and blood revealed that C. albicans localized in the meninges of the brain. There was also a significant isolant-related effect of C. albicans on the growth rate of the inoculated birds. These easily quantitated differential effects of various isolants of C. albicans offer the prospect of correlating biochemical characteristics with virulence and obtaining information about the mechanism of pathogenicity of this microorganism.

Animals↗