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Biomedical subjects

F White

Publications and source records attributed to F White.

15 recordsLinked to original sources
PubMed1979

Isolation of a non-tumor-inducing mutant of the Ti plasmid of Agrobacterium tumefaciens strain B6.

A nonpathogenic mutant of Agrobacterium tumefaciens strain B6 was isolated and its properties compared with the parental strain in an effort to localize the mutation. Both B6 and its mutant (B6-95) had similar colony color and morphology, were ketolactose positive, utilized octopine, and contained plasmid DNA. Kinetic analysis of DNA reannealing showed that total DNA homology and plasmid DNA homology between B6 and B6-95 was at least 90%. The length of both plasmids was found to be 58 micrometer. Plasmid DNA from both B6 and the mutant was digested with endonucleases and the fragments separated by agarose gel electrophoresis. In all cases the pattern for B6 was identical with that of B6(-95). The Ti plasmid from B6 and the mutant was transferred to an avirulent, plasmidless strain of A. tumefaciens by in vitro conjugation and transformation. All of the B6 transconjugants and transformants were virulent, whereas all of the mutant transconjugants and transformants were avirulent. Electrophoretic patterns of endonuclease-digested plasmid DNA from transformants were identical to those of plasmid DNA from B6. Therefore, we conclude that the virulence mutation lies on the Ti plasmid.

Conjugation, Genetic↗
PubMed1978

Use of the Leiter International Performance Scale with adult aphasics.

Considered whether the Leiter International Performances Scales (LIPS), a general intelligence test used successfully with Ss age 2-18, can be adapted for use with aphasic adults. Six aphasic adults and 6 matched controls were given the Reitan Indians Screening Test of Aphasia and the LIPS. Results showed that the aphasic sample had total test scores comparable with the control group; however, the aphasic group required approximately 66% more time than the controls to complete the test. It was concluded that further work is merited based on the following results: (1) the test provided a sufficient range of difficulty so that each S errored on at least one-fourth of the test items; (2) the test could be given to the adult aphasics within a feasible time frame; (3) the aphasic adults were able to work with the test materials despite visual defects and hemiparesis of the dominant side; (4) feasible modifications can be made in the test.

Adult↗
PubMed1978

Motorized minitrack for exercising large animals.

A simply constructed device for exercise training large animals, e.g., swine, is described. Basically the device is a small, circular, enclosed track constructed of plywood and metal fence material. A centrally located, vertical shaft powered by a DC motor rotates at a variable speed. Attached to each of four horizontal metal beams extending from the shaft are four suspended partitions which hang freely above the enclosed track surface. As the shaft rotates, the four partitions move in unison, thus forcing animals in each compartment to move at the same pace. The advantages of this device are its cost, low maintenance, and the flexibility to train eight animals by one person. Preliminary results of a study on training pigs are discussed.

Animals↗
PubMed1978

Ultrastructural influence of reperfusing dog myocardium with calcium-free blood after coronary artery occlusion.

The ultrastructural effects of perfusing ischemic myocardium with calcium-free blood were determined in 12 dogs. In 6 dogs, the left anterior descending coronary artery was ligated for 45 minutes and was released for 5, 10, or 20 minutes. In 6 other dogs, the ischemic zone was perfused with blood free of calcium which was chelated with EGTA (ethylene glycol bis [B-aminoethylether-N,N'-tetraacetic acid] for 5, 10, or 20 minutes. After reperfusion with whole blood, the sarcomeres either were mildly contracted or formed contracted bands. The cells were usually pulled apart at the intercalated disk. The mitochondria were swollen and contained electron-dense deposits. Lanthanum was used as a marker for monitoring changes in cell membrane permeability and permeated into many ischemic myocardial cells. The hearts treated with calcium-free plasma showed well preserved morphology. Mitochondria were slightly swollen, their cristae were occasionally disrupted, and they lacked electron-dense deposits. No lanthanum leaked into these cells, with a few scattered exceptions. Even in the leaky cells, the mitochondria did not show any deposits. It is suggested that calcium overload plays a significant role in the pathogenesis of cell injury and that reduction in plasma levels of calcium, at least for a limited period may delay the onset of calcium overload and improve cell morphology. Alterations in the cell membrane are followed by lethal intracellular changes leading to events associated with cell death.

Animals↗
PubMed1977

Feline factor XII (Hageman) deficiency.

A coagulation profile from a clinically normal female cat revealed an intrinsic coagulation defect characterized by prolonged activated partial thromboplastin time, with normal bleeding time, platelet count, and prothrombin time. Subsequent correction studies, utilizing activated partial thromboplastin time, confirmed factor XII deficiency. Hematologic and clinical studies on the cat failed to reveal an underlying disease process that might result in acquired factor XII deficiency.

Animals↗
PubMed1975

The influence of food intake on portal blood flow and heat production in the digestive tract of sheep.

1. Measurements were made of portal blood flow, heat production and oxygen consumption in the digestive tract of sheep either fasted or given the following diets: chopped, dried grass, pelleted, dried grass; chopped, dried lucerne; pelleted, dried lucerne, or a pelleted barley diet. 2. For sheep that had been fasted for 48 h, portal blood flow was 1.84 l/min, total visceral heat production was 62.3 kJ/kg body-weight 0.75 per 24 h and aerobic heat production, estimated from oxygen consumption, was 62.1 kJ/kg body-weight 0.75 per 24 h. 3. Portal blood flow was markedly influenced by food intake, increasing from 1.8 l/min for starved sheep to 2.4 and 4 l/min for sheep feed at maintenance and 2.5 times maintenance levels of intake respectively. Variations in the quality and physical form of the diets had no apparent effect on portal blood flow. 4. There was a curvilinear relationship between total heat production in the gut and metabolizable energy (ME) intake. The increase obtained for levels of intake below maintenance was greatest with lucerne diets, and least with pelleted, dried grass or pelleted barley diets. Above maintenance levels of intake the rate of increase in heat production, with all diets, was about 150 kJ/MJ ME intake. 5. The heat of fermentation, estimated from the difference between total visceral metabolism and the aerobic metabolism of the tissues of the gut wall, was 76, 60 and 22 kJ/MJ digestible energy intake for the dried grass, lucerne and barley diets respectively. 6. The contribution of fermentation heat and the aerobic metabolism of the gut to the total heat increment of feeding in sheep was assessed. It was concluded that about half the heat increment must be derived from tissues outside the digestive tract.

Aerobiosis↗