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Biomedical subjects

J M Walsh

Publications and source records attributed to J M Walsh.

At least 19 recordsLinked to original sources
PubMed1992

Death certification and coding for ischaemic heart disease in Tasmania.

Official records show that the rates of mortality from ischaemic heart disease (IHD) in Tasmania have been the highest of all the Australian states for most of the past decade. This study assesses the accuracy of the official Tasmanian mortality data for IHD in 1987 and 1988 for males aged 25 to 74 years using routinely available clinical and pathological data supplemented by information from the attending doctor. Our findings show that a death officially coded to ICD 9 rubrics 410-414 (IHD) in Tasmania has 94% sensitivity and a positive predictive value of 90% for fatal definite acute myocardial infarction or possible coronary death as defined by the WHO. Comparison of our results with those of two earlier studies undertaken in Australian mainland centres indicates that differences in the official statistics for coronary mortality between Tasmania and the mainland states reflect true differences in the risk of coronary death. While the results from three Australian studies suggest that the routine system of death certification is reasonably accurate, careful monitoring of death certification and coding practices need to be undertaken regularly in all states of Australia if secular changes in regional patterns of coronary mortality are to be regarded as credible.

Adult↗
PubMed1992

Structural change of the thorax in chronic obstructive pulmonary disease.

This study examines structural changes of the thorax in hyperinflated subjects with chronic obstructive pulmonary disease (COPD). Age-matched normal subjects were used for comparison. Thoracic dimensions were determined using anteroposterior and lateral chest radiographs performed at total lung capacity, functional residual capacity, and residual volume. Rib cage dimensions (lateral diameter, rib angle, anteroposterior diameter) and diaphragm position were determined at each lung volume. There were no significant differences in rib cage dimension between the COPD and normal subjects for all lung volumes. In contrast, the diaphragm was significantly lower in the COPD subjects. The change of rib cage dimensions in the COPD subjects (for a similar volume change) was not different from that in normal subjects, whereas the change of diaphragm position in the COPD subjects (for a similar volume change) was reduced. In conclusion, the primary structural change of the thorax in COPD with chronic hyperinflation is confined to the diaphragm, with no appreciable structural change in the rib cage.

Aged↗
PubMed1992

A systems model of clinical preventive care: an analysis of factors influencing patient and physician.

An ideal model for clinical preventive care must consider the physician, the patient and the many factors which influence each of them. In this paper, we review existing models, examining their strengths and weaknesses. We then propose a new model, the Systems Model of Clinical Preventive Care. This model is unique in its focus on the patient-physician interaction and details the factors impinging on each that promote or inhibit the completion of preventive care activities. These factors include patient and physician predisposing factors, such as health beliefs and attitudes; enabling factors, such as skills and resources; and reinforcing factors, such as social support. Additional factors include health care system organizational factors, such as access or availability; characteristics of the preventive activity, such as cost; and cues to action, such as symptoms or reminders. The proposed model contains components of behavioral, communication, health education and psychosocial theories. We then apply our model to mammography as an example of a screening activity. Finally, we describe the strengths and weaknesses of the proposed model, and identify areas for future research.

Delivery of Health Care↗
PubMed1992

Cancer screening in older adults.

Adults aged 65 and older represent an increasingly important segment of the US population. Cancer is an important cause of death in this group. Screening for cancer can significantly reduce cancer incidence and mortality. In this review I address screening for breast, cervical, prostate, lung, colorectal, and ovarian cancer in older Americans. Decisions about screening for cancer must consider the effects of screening, diagnostic evaluations, and treatments on the quality of life of each person.

Aged↗
PubMed1990

Production of recombinant human erythropoietin in Bowes melanoma cells in suspension culture.

Recombinant DNA technology was used to insert a fetal liver genomic library ApaI fragment encoding for human erythropoietin (Epo) into Bowes melanoma cells. The cells expressed the erythropoietin gene, and Epo was secreted into the culture medium together with the normally-secreted tissue plasminogen activator. Attempts to grow the cells in glass spinners in Dulbecco's medium supplemented with fetal bovine serum produced cell aggregates growing in suspension. When calcium-free suspension culture media (Joklik, DME-S, McCoy 5A-S) were used, single cell suspension cultures were obtained and high Epo production observed. When attempts were made to scale up the small glass spinners, poor growth or Epo production occurred unless the vessels were aerated. This was shown to be because of the drop in pH, possibly due to CO2 accumulation, rather than due to oxygen depletion. It was shown that a semi-continuous operation could be achieved in aerated 8-1 spinners fitted with either a conventional stirrer or a vibromixer agitator. The system was scaled up to a 100-1 stainless steel vessel fitted with a vibromixer agitator. This system was operated for over 4 months with weekly harvests producing over 100 million units of Epo in about 1000-1 of culture fluid. Interference by the serum proteins with downstream purification of the hormone from the culture fluid made the use of serum-free media highly desirable. Studies showed that the Epo was produced in serum-free systems containing peptones.

DNA, Recombinant↗
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↗