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Biomedical subjects

J M Walsh

Publications and source records attributed to J M Walsh.

15 recordsLinked to original sources
PubMed1978

Reduction of the incidence of decompression sickness in rats by smooth-muscle activating factor (SMAF).

Normal rats were injected with a smooth-muscle activating factor (SMAF) to examine the dose-response relationshio of SMAF to the incidence of decompression sickness. After injections of saline or 1.0, 5.0, or 10.0 mg/kg SMAF, the animals were compressed to 6 ATA breathing air for 1 h and were then rapidly decompressed to 1 ATA. Results indicate that predive injections of SMAF or exposure to the SMAF substance protected rats against decompression sickness and that higher doses appear to offer more protection.

Animals↗
PubMed1977

Reduction of the behavioral effects of delta9-tetrahydrocannabinol by hyperbaric pressure.

Delta9-tetrahydrocannabinol in doses of 0.5, 1.0, 2.0 and 4.0 mg/kg was administered to rats under normal (1 ATA) and increased (3, 5 and 7 times normal) atmospheric pressure. Behavior was maintained by a food-reinforced differential-reinforcemnet-of-low-rate (DRL) schedule. Dose-dependent decrements in performance was observed at the 1 ATA conditions, in which response rates increased and the well-established temporal discrimination disintegrated. Under the elevated pressure conditions, however, a reversal of behavioral toxicity occurred during which performance improved as a function of pressure. The behavioral disruptions occurring at the 5- and 7-ATA pressures were minimal compared with those occurring at 1 ATA under equivalent doses of the drug. The present experiment has demonstrated that delta9-tetrahydrocannabinol produces significant behavioral changes at 1 ATA pressure, but when atmospheric pressure is increased the drug effects are reduced.

Animals↗
PubMed1976

Studies on the control of 4-aminobutyrate metabolism in 'synaptosomal' and free rat brain mitochondria.

1. The specific activities of 4-aminobutyrate aminotransferase (EC 2.6.1.19) and succinate semialdehyde dehydrogenase (EC 1.2.1.16) were significantly higher in brain mitochondria of non-synaptic origin (fraction M) than those derived from the lysis of synaptosomes (fraction SM2). 2. The metabolisms of 4-aminobutyrate in both 'free' (non-synaptic, fraction M) and 'synaptic' (fraction SM2) rat brain mitochondria was studied under various conditions. 3. It is proposed that 4-aminobutyrate enters both types of brain mitochondria by a non-carrier-mediated process. 4. The rate of 4-aminobutyrate metabolism was in all cases higher in the 'free' (fraction M) brain mitochondria than in the synaptic (fraction SM2) mitochondria, paralleling the differences in the specific activities of the 4-aminobutyrate-shunt enzymes. 5. The intramitochondrial concentration of 2-oxoglutarate appears to be an important controlling parameter in the rate of 4-aminobutyrate metabolism, since, although 2-oxoglutarate is required, high concentrations (2.5 mM) of extramitochondrial 2-oxoglutarate inhibit the formation of aspartate via the glutamate-oxaloacetate transaminase. 6. The redox state of the intramitochondrial NAD pool is also important in the control of 4-aminobutyrate metabolism; NADH exhibits competitive inhibition of 4-aminobutyrate metabolism by both mitochondrial populations with an apparent Ki of 102 muM. 7. Increased potassium concentrations stimulate 4-aminobutyrate metabolsim in the synaptic mitochondria but not in 'free' brain mitochondria. This is discussed with respect to the putative transmitter role of 4-aminobutyrate.

4-Aminobutyrate Transaminase↗
PubMed1976

Mitochondrial DNA in yeast recombination and subsequent modification following mating between a Grande and a suppressive Petite.

The fate of mitochondrial DNA, following mating between a grande and suppressive petite of Saccharomyces cerevisiae, has been followed for up to 60 generations. The buoyant density of the mitochondrial DNA was seen to change in a manner explicable by a combination of recombination and subsequent modification phenomena whilst the suppressivity of the petite zygotic clones always remained high. These findings are consistent with current models of mitochondrial DNA metabolism in which petite strains have been observed to undergo deletion and reamplification of certain parts of their genomes.

Centrifugation, Density Gradient↗
PubMed1976

A normative approach to the definition of primary health care.

Primary care is the subject of many pronouncements and many recommendations for change in the literature on health care organization and delivery. Heretofore, there has been no attempt to assess the degree of agreement on the meaning of the term. This paper reports on a normative process used to construct 92 statements about important elements of primary care, and to rank these statements according to their relative degrees of importance in primary care. Three panels--nationally recognized "experts" on primary care, consumers, and public health nurses and social workers--participated in the development as well as the ranking of the statements. The rankings of the national experts are discussed in detail, and brief comparisons are made with the rankings of the consumer and public health worker panels. Experts gave a high ranking to the statements concerned directly with medical services and their linkages. All gave attention to equality and patient dignity. Consumers stressed the need to improve access to primary care services. Public health workers emphasized improvement in both access and the quality of the relationship between patients and providers. The overall findings suggest that increasing the base of participation in primary care planning may bring greater attention to patient defined needs, and that broadening of medical care objectives from medical care to a more inclusive health care is not imminent.

Community Participation↗