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Biomedical subjects

L Atkinson

Publications and source records attributed to L Atkinson.

At least 73 records · Page 4Linked to original sources
PubMed1984

Effect of timolol maleate on pacing induced myocardial ischaemia.

The effects of timolol maleate administered intravenously on coronary and systemic haemodynamics, myocardial metabolism, and plasma catecholamine concentrations were assessed in 10 patients with confirmed coronary artery disease. Rapid atrial pacing to the onset of angina was performed in all patients. Timolol reduced cardiac output at rest and during pacing and reduced resting heart rate but did not affect arterial blood pressure. Left ventricular stroke work index fell during pacing. Coronary sinus blood flow was unchanged, but pulmonary artery diastolic pressure rose after timolol. The drug produced clinical improvement in nine of the 10 patients with prolongation of the mean pacing time to angina. There was evidence of improved myocardial metabolism with a change from production to extraction of lactate: Arterial noradrenaline concentrations at rest rose after timolol. In these patients with coronary artery disease timolol produced an increased tolerance to atrial pacing stress, which appears to be due to a combination of effects including reduced myocardial contractility and decreased lipolysis.

Angina Pectoris↗
PubMed1983

Haemodynamic and metabolic effects of dazoxiben at rest and during atrial pacing.

1 Thromboxane B2 (TXB2) levels were measured in three sites (coronary sinus, pulmonary artery, and femoral artery) at rest and during atrial pacing in 11 patients with stable angina pectoris. 2 There was a highly significant increase in arterial TXB2 on pacing (by up to 820 pg/ml) but there was no change in the thromboxane levels at the other two sites. 3 Dazoxiben 200 mg orally abolished the increase in arterial TXB2, but had no effect on systemic, pulmonary or coronary haemodynamics, no effect on myocardial metabolism and a variable effect on atrial pacing time to angina.

Aged↗
PubMed1983

The pathophysiology of angina pectoris with normal coronary arteriograms. Histopathological and metabolic correlations with coronary vasospasm.

Angina pectoris may occur in the presence of normal major coronary vessels (NCA) in 10-20 per cent of patients investigated by coronary arteriography. Whilst hypertrophic cardiomyopathy, mitral valve prolapse and hyperthyroidism are excluded by routine investigation, in the remainder coronary vasospasm may be demonstrated. An organic basis for angina may not always be found. In order to document the pathophysiological basis for angina pectoris with NCA we have investigated patients using atrial pacing stress with measurement of coronary sinus blood flow and lactate metabolism, together with myocardial biopsy to determine biochemical and histopathological abnormalities. These have been correlated with localised coronary vasospasm induced by ergometrine (E). Thallium scintigraphy has also been used to detect the myocardial changes. Fifteen patients were investigated: 5 of 15 patients developed abnormal lactate metabolism on atrial pacing (change greater than 0.8 mg per cent in A/V lactate difference) and all had greater than 50 per cent coronary luman reduction after E. In 10 of 15 patients no lactate change occurred and in 7 no significant response to E was seen. However, significantly lower myocardial enzyme activities were found in the first group (lactate dehydrogenase p less than 0.01, malate dehydrogenase p less than 0.05, alpha hydroxy-butyrate dehydrogenase p less than 0.02). The change in myocardial enzyme activities in angina with NCA may indicate a metabolic basis for angina in those patients who develop both abnormal lactate metabolism on pacing and coronary vasospasm after ergometrine. The enzyme activities and histological changes in angina with NCA are similar to these in dilated cardiomyopathy.

Adult↗
PubMed1982

The measurement of enzyme activities in endomyocardial biopsies from patients with congestive (dilated) cardiomyopathy and specific heart muscle disease.

50 patients with heart muscle disease have been investigated using routine invasive and non-invasive techniques, including endomyocardial biopsy. Enzyme activities in myocardial tissue obtained by biopsy have been measured in dilated cardiomyopathy and heart muscle disease and compared. Significant differences in enzyme activity have been found between dilated cardiomyopathy and alcoholic heart muscle disease when the groups are defined by detailed drinking histories. CPK (p less than 0.002), MDH (p less than 0.001), LDH (p less than 0.001) and alpha HBD (p less than 0.001). The changes in the enzyme levels may be an adaptive response to alcohol although serial study did not show a fall in enzyme activities after 3-6 months abstinence. Preliminary data furthermore indicates an association of the alpha HBD/LDH and LDH/CPK enzyme activity ratios and ejection fraction. This data supports the diagnosis of a specific heart muscle disease in response to alcohol excess.

Adult↗
PubMed1982

Cancer reporting in Papua New Guinea: 1958-70 and 1971-78.

In 1958, a cancer registry was established in Papua New Guinea for a population of 2 million who had remained in near isolation for millenia until recently. This report includes cancer data for 1970 through 1978. During those years, the registrations increased from 200 to 600. The reasons for this increase and the patterns of reporting over the entire 21-year period are examined. The data offered us opportunities to examine changes in case findings according to geography, time, and sex. Genuine differences in cancer incidence and pattern within this diverse country, mainly between the highland and lowland regions, were studied, particularly concerning oral, skin, liver, and penile cancers, and Burkitt's lymphoma. The controversy remains over the relationship of oral cancer and chewing of substances other than tobacco; but in this country, at least, a chew consisting only of areca nut mixed with lime must be held suspect. With the emergence from isolation, profound socioeconomic changes are occurring in this country; the patterns of cancer must change also, and we may be seeing the beginning of this already. Possible fruitful areas for further detailed studies are indicated.

Burkitt Lymphoma↗
PubMed1981

Prostacyclin: haemodynamic and metabolic effects in patients with coronary artery disease.

The therapeutic potential of prostacyclin was evaluated in 10 patients with angina pectoris and angiographically proved coronary artery disease. Platelet aggregation and coronary and systemic haemodynamic effects were examined before and after intravenous infusions of 2, 4, 6, and 8 ng/kg/min of prostacyclin and were dose related. At 8 ng/kg/min the ADP concentration required to induce 50% of maximum platelet aggregation increased from 1.8 to 4.5 mumol/l (p less than 0.001). Heart rate and cardiac index rose from 77 to 93 beats/min and 2.47 to 3.48 l/min/m2, respectively (p less than 0.01). Mean blood pressure and systemic and pulmonary resistances fell from 107 to 92 mm Hg and 1704 to 1048 and 80 to 45 dyn s cm-5, respectively (p less than 0.01). Coronary vascular resistance also fell from 0.95 to 0.73 units (p less than 0.01). Mean atrial pacing time to angina rose from 142 to 241 s (p less than 0.05), while lactate production during rapid atrial pacing was decreased, lactate extraction ratio rising from -25 to -9% (p less than 0.05). These coronary and systemic vasodilator effects and the prolongation of pacing time to angina indicate an acute beneficial effect of prostacyclin on angina. Since prostacyclin has been shown to prevent platelet accumulation and progression to total occlusion in animals with experimental coronary stenoses, the observed inhibition of platelet aggregation suggests that prostacyclin should be further evaluated in unstable angina.

Angina Pectoris↗
PubMed1979

Craniofacial surgery.

The historical development of craniofacial surgery for congenital abnormality is reviewed. The work of a second Australian unit of craniofacial surgery which has been formed in Brisbane is described, current indications for surgery are defined, and the preoperative preparation is outlined. The treatment of six children with hypertelorism, Crouxon's disease, Apert's syndrome, and bicoronal craniostenosis is described and the postoperative results and complications are outlined. There is a case for early surgery.

Child↗
PubMed1978

Melanoma of the central nervous system.

The neurological manifestations of melanoma are analysed in this review of 1,500 patients in the Queensland Melanoma Project from 1963 to 1969. Three hundred and fifty patients have died, and 113 were recognized as having central nervous system metastases. The natural history of these metastases was examined, together with the results of a limited number of autopsies. The results of treatment are discussed.

Adult↗