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Biomedical subjects

T D Lawrie

Publications and source records attributed to T D Lawrie.

At least 37 records · Page 2Linked to original sources
PubMed1980

Long-term comparison of metoprolol and methyldopa in the treatment of hypertension.

The effect of the cardioselective beta-adrenoreceptor blocking compound, metoprolol, was compared with methyldopa in the long-term management of hypertension. Thirty patients given metoprolol and twenty-six given methyldopa were treated for 2 years. The maximum dose of metoprolol was 200 mg twice daily (average 308 mg) and of methyldopa 1,000 mg twice daily (average 1,120 mg). Blood pressure was similar at entry to the study (metoprolol 177/110 mmHg and methyldopa 181/111 mmHg). After 2 years of treatment the blood pressure levels were again similar (metoprolol 149/91 mmHg and methyldopa 148/91 mmHg). Erect pressures were lower in the methyldopa group, but there was no difference between supine and erect blood pressure levels in those on metoprolol. At an exercise load of 300 and 600 kpm the increase in systolic pressure was significantly less in the metoprolol group. The proportional increase in systolic and diastolic pressure in response to a standardized stress situation was reduced by treatment with metroprolol but not by methyldopa. Tolerance to therapy did not develop in either group. The main difference between metoprolol and methyldopa was in the incidence and severity of side effects. Four patients were withdrawn from the metoprolol group. Seventeen were withdrawn from the methyldopa mainly because of side effects including drowsiness, depression, skin rash, and impotence. Six patients on metoprolol and seventeen on methyldopa continued on therapy although side effects were present. It is concluded that metoprolol and methyldopa lower blood pressure to the same extent, but metoprolol is advantageous because of a lower incidence of side effects.

Adult↗
PubMed1980

Comparison of newer antiarrhythmic agents.

In the past decade a number of new antiarrhythmic drugs ahve been introduced. They have been extensively used in the acute phase of myocardial infarction. Few, if any, long-term comparative trials of these newer agents have been reported. Most of these newer agents have been shown to be able to reduce the frequency of ventricular arrhythmias but not the mortality rate. Beta blockers and some antiplatelet adhesive drugs, however, have reduced the mortality rate following myocardial infarction. There is a need for long-term properly stratified trials of these effective agents.

Adrenergic beta-Antagonists↗
PubMed1980

Effect of blood pressure control on left ventricular hypertrophy in patients with essential hypertension.

1. Changes in left ventricular structure and function were assessed by echocardiography in 22 patients before and after 9 months blood pressure control. 2. Nine patients had normal baseline echocardiograms (group 1) and 13 had echocardiographic evidence of left ventricular hypertrophy (group 2). 3. Group 2 patients demonstrated significant reductions in posterior wall thickness (P < 0.01), septal wall thickness (P < 0.025) and left ventricular mass (P < 0.005). Only six of the 13 patients showed a reduction of greater than or equal to 3 mm in posterior wall thickness. The remainder showed no alteration or only a slight non-significant reduction. 4. The regression of voltage in some patients but not in others did not appear to be related to initial blood pressure, the extent of the fall in blood pressure or duration of follow-up. It was not possible to say whether any specific therapy was beneficial to regression since most of the patients were on multiple therapy.

Adult↗
PubMed1980

The effects of propranolol and acebutolol on left ventricular function and coronary haemodynamics in the conscious dog with myocardial ischaemia.

1 The cardiovascular effects of the beta-adrenoceptor blocking drugs, propranolol and acebutolol, on regional coronary blood flow and left ventricular function have been investigated in the conscious dog with developing myocardial infarction. 2 Propranolol (1 to 1.5 mg/kg) or acebutolol (4 to 5 mg/kg) were administered intravenously 2 to 3 h after occlusion of the left anterior descending coronary artery. 3 Propranolol or acebutolol administration resulted in a relative increase in flow to the ischaemic area of the myocardium, particularly to the subendocardium. 4 Propranolol produced a greater reduction in heart rate and myocardial contractility than acebutolol. 5 These results demonstrate that beta-adrenoceptor blocking drugs reduce myocardial oxygen consumption and increase coronary flow to the ischaemic area of the myocardium after coronary artery occlusion in the conscious dog.

Acebutolol↗
PubMed1980

Serial measurements of left ventricular dimensions by echocardiography. Assessment of week-to-week, inter- and intraobserver variability in normal subjects and patients with valvular heart disease.

The week-to-week, inter- and intraobserver variation in left ventricular echocardiographic measurements has been studied in 10 normal male volunteers and in five patients with stable valvular disease. A two-way analysis of variance showed no statistically significant variation either from week to week or between observers. Furthermore the within observer variation was minimal. Calculation of the coefficient of variation allowed confidence limits to be applied to each of the six ventricular measurements, thus providing ranges of variation in follow-up studies using M-mode echocardiography.

Aged↗
PubMed1980

Comparative study of the effects of penbutolol and propranolol in the treatment of angina pectoris.

1. Fourteen patients with angina with obstructive coronary artery disease were treated with propranolol, given four times daily, or penbutolol given once daily. 2. The frequency of anginal episodes and glyceryl trinitrate consumption were monitored using diary cards. Heart rate and blood pressure were recorded at rest and on exercise. Left ventricular function was assessed using systolic time intervals. 3. Penbutolol given once daily showed similar effects as propranolol, using both clinical assessment and changes in physiological parameters.

Adult↗
PubMed1979

The effects of cholestyramine on high density lipoprotein metabolism.

This study on 4 type II hyperlipoproteinaemic subjects examines the effects of pharmacologic doses (8 g twice daily) of the bile acid sequestrant cholestyramine on the plasma distribution and chemical composition of the high density lipoprotein subfractions, HDL2 and HDL3, and describes the influence of the drug on the metabolism of the major HDL aporoteins, apolipoprotein A-I and A-II. Cholestyramine lowered plasma low density lipoprotein cholesterol (32%; P less than 0.05) without affecting the level of that lipid in very low density or high density lipoproteins. However, the plasma HDL2/HDL3 ratio and apolipoprotein A-I concentration rose significantly on treatment, while apolipoprotein A-II remained unchanged. The rise in apolipoprotein A-I derived from an increase in its synthetic rate and produced a relative enrichment of the protein with respect to apolipoprotein A-II in both HDL subfractions. These results demonstrate the cholestyramine treatment affects HDL metabolism in a way which, according to current concepts, may prove beneficial to the recipient.

Apolipoproteins↗
PubMed1979

Effect of exercise in hypertension controlled with metoprolol or methyldopa.

1. The adequacy of the control of essential hypertension during exercise was studied in patients whose resting blood pressure had been controlled for 1 year with either metoprolol or methyldopa. 2. Systolic blood pressure increased with exercise in both groups, the increase being significantly less in the metoprolol group than in the methyldopa group.

Adult↗
PubMed1979

Objective measurement of performance during acute stress in patients with essential hypertension: assessment of the effects of propranolol and metoprolol.

1. A standardized method of objectively measuring performance during simulated car driving is described. 2. The effect of a single dose of propranolol and metoprolol were compared with placebo in two groups of patients with untreated essential hypertension. 3. Performance was similar after beta-adrenoreceptor-blocking agents or placebo. 4. Blood pressure response to stress persisted after administration of the blocking agents.

Adult↗
PubMed1978

The pharmacokinetics of slow-release procainamide.

Procainamide was given to 20 patients with normal renal function as an i.v. bolus of 500 mg followed by 1.0 or 1.5 g eight-hourly by mouth in the form of a slow release preparation (Durules). 97.6 +/- 27.1 (SD)% of the oral procainamide was absorbed, the absorption half life being 1.54 h. The elimination half life following the oral formulation was 6.0 +/- 0.8 h, compared to a mean of 3.4 +/- 0.4 h following i.v. administration. Elimination half life following i.v. administration was slightly related to acetylator status, being 2.75 +/- 0.9 h in fast acetylators, and 4.4 +/- 2.4 h in slow acetylators. This dependence on acetylator status was not seen in half life following oral administration. Total body clearance, steady state plasma procainamide and N-acetylprocainamide were not significantly dependent on acetylator status, although a few patients who are slow acetylators had unexpectedly low clearance and high steady state procainamide concentrations when given the higher dose.

Biological Availability↗
PubMed1978

Early treatment of myocardial infarction in the community.

The prehospital management of acute myocardial infarction by general practitioners and emergency-treatment service physicians was analysed in 53 patients. The correct clinical diagnosis was made or suggested before admission in 47 patients. Only 25 patients received analgesics from the general practitioner, and 32 were still in pain and needed diamorphine on admission to hospital. Only one patient received antiarrythmic treatment. The findings suggest that, despite accurate clinical diagnosis of acute myocardial infarction, deficiencies exist in the prehospital phase of management and that education programmes are worth consideration.

Analgesics↗
PubMed1978

Regulation of cholesterol synthesis in the hyperlipoproteinaemias. Polymorphonuclear leucocyte abnormality specific to familial type II hypercholesterolaemia.

A simple procedure has been devised to give virtually pure preparations of polymorphonuclear leucocytes. This has permitted study of the regulation of cholesterol biosynthesis at cell level. Freshly isolated cells from donors with various forms of hyperlipoproteinaemia have been shown to have very low levels of cholesterol synthesis, presumably due to high circulating levels of apoprotein-B in donor plasma [1]. The activity of the rate-limiting enzyme for cholesterol biosynthesis, 3-hydroxy-3-methylglutaryl coenzyme A reductase, rapidly increases as the cells are incubated in lipoprotein-deficient medium, until, by 12 h, cells from patients heterozygous for familial type IIa hypercholesterolaemia are clearly distinguished from other hyperlipoproteinaemias. The possible significance of this finding is discussed in relation to the causation and treatment of atherosclerotic disease.

Cells, Cultured↗
PubMed1978

Standardized stress and hypertension: comparison of effect of propranolol and methyldopa.

1 Using a standardized form of mental stress, 21 patients with idiopathic hypertension were investigated before and after treatment with placebo (n=8), propranolol (n=7) or methyldopa (n=6). 2 Blood pressure was satisfactorily controlled in the propranolol and methyldopa groups but only the propranolol group showed modification of the pressor response to stress testing. 3 These results suggest that propranolol may provide more uniform control of blood pressure than methyldopa in patients with essential hypertension.

Adult↗
PubMed1978

Hypothalamo-pituitary-thyroid axis function during cardiopulmonary bypass.

Marked alterations in levels of circulating thyroid hormone were found in patients undergoing cardiopulmonary bypass with a rise in the free thyroxine and a fall in the free triiodothyronine levels. Studies using thyrotropin-releasing hormone during bypass demonstrated a blunted response to this stimulus. This reduced response is related to changes in thyroid hormone levels and it is suggested that bypass surgery may have a direct inhibitory action on thyroid-stimulating hormone release at the hypothalamo-pituitary level. The potential significance of these hormonal changes is discussed.

Adult↗
PubMed1977

Lipoprotein concentrations in untreated adult onset diabetes mellitus and the relationship of the fasting plasma triglyceride concentration to insulin secretion.

Plasma lipoprotein concentrations in 64 untreated adult onset diabetics were compared to the lipoprotein levels found in non diabetics. No significant difference was found. The relationship of the fasting plasma triglyceride concentration to the plasma immunoreaction insulin response to 50 g glucose orally was investigated. Using correlation analysis a significant and insulin response in the non diabetics but not in the diabetics.

Cholesterol↗
PubMed1977

Centralised interpretation of electrocardiograms.

A system was devised so that a peripheral hospital could transmit electrocardiograms (ECGs) to a central computer for interpretation. The link that transmits both ECGs and reports is provided by the telephone network. Initial results showed that telephone transmission did not significantly affect the accuracy of the ECG interpretation. The centralised computer programme could be much more widely used to provide ECG interpretations. A telephone link would not be justified in health centres, where the demand for ECGs is fairly small, but ECGs recorded at a health centre can be sent to the computer for interpretation and returned the next day. The most cost-effective method of providing computer interpretation for several health centres in a large city would be to have a portable electrocardiograph and transmission facilities, which could be moved from centre to centre.

Diagnosis, Computer-Assisted↗
PubMed1977

Limb blood flow in treated hyperlipoproteinaemic patients with peripheral vascular disease. A preliminary report.

Fourteen patients with hyperlipoproteinaemia and peripheral vascular disease have been investigated to determine the effect on limb blood flow of hypolipidaemic therapy. Satisfactory lowering of serum lipoprotein levels was achieved in the treated group. There was a significant deterioration in peak reactive blood flow measurements in the placebo group compared with the treated group. Treatment of hyperlipoproteinaemia may, therefore, be of value in preventing the progression of peripheral atherosclerosis.

Adult↗