Search PubMed⌕ Search

Biomedical subjects

G Macdonald

Publications and source records attributed to G Macdonald.

At least 55 records · Page 3Linked to original sources
PubMed1987

Treatment of high blood pressure in overweight patients.

Weight reduction was compared with metoprolol (200 mg daily) in a randomized placebo-controlled trial of first-line treatment of mild hypertension (diastolic blood pressure 90-109 mm Hg) in 56 overweight patients aged under 55 years. After 21 weeks of follow-up the weight-reduction group had lost an average of 7.4 kg. The fall in their systolic pressure of 13 mm Hg was significantly greater than that in the placebo group (7 mm Hg) but not different from that in the metoprolol group (10 mm Hg). Their fall in diastolic pressure (10 mm Hg) was greater than that in both the metoprolol (6 mm Hg) and placebo (3 mm Hg) groups. At the end of the follow-up period, 50% of patients in the weight-reduction group had a diastolic pressure of less than 90 mm Hg. In the weight-reduction group, left ventricular mass decreased by 18% in comparison with placebo; in the metoprolol group left ventricular mass was unchanged. In the weight-reduction group there was a decrease both in total cholesterol and in the ratio of total to HDL-cholesterol; in the metoprolol group there was a decrease in high density lipoprotein(HDL)-cholesterol and an increase in the ratio of total to HDL-cholesterol. In this study, weight reduction produced significant falls in both blood pressure and left ventricular mass but not the adverse effects on plasma lipids commonly associated with antihypertensive drug therapy.

Adult↗
PubMed1987

The antihypertensive efficacy of nifedipine alone and in combination in general practice.

A multi-centre study in general practice involving 3242 hypertensive patients, aged up to 70 years, was carried out to evaluate the efficacy and tolerability of nifedipine used alone or in combination with other antihypertensive agents in step-care treatment. Patients were treated for up to 8 weeks with one of four regimens: nifedipine monotherapy; diuretic and nifedipine; beta-blocker plus nifedipine; and nifedipine added to a combination of diuretic and beta-blocker. All patients received 20 mg nifedipine, in slow-release tablet form, twice daily; at Week 4, dosage was increased to 40 mg twice daily in 8.5% patients because their supine diastolic blood pressure still exceeded 95 mmHg. Changes in mean blood pressure of the total study group for systolic and diastolic, supine and standing, were highly significant both from baseline (Week 0) to Week 4 (p less than 0.0001) and from baseline to Week 8 (p less than 0.0001). Mean blood pressure reduction was 29/18 mmHg supine and 27/18 mmHg standing. Statistical differences in blood pressure response between age, sex and treatment groups were not of clinical significance. Statistically significant reductions in heart rate (mean 1.9 beats/min, p less than 0.001) and body weight (mean 0.48 kg, p less than 0.001) were noted, but were not of clinical relevance. Nifedipine produced a net increase of 12% in side-effects at Week 4 compared to the profile at entry.

Adult↗
PubMed1983

Nitrous oxide.

Explore the source record for details and available documents.

Anesthesia, Dental↗
PubMed1980

Thymidine Metabolism and the Measurement of the Rate of DNA Synthesis in Carrot Suspension Cultures: EVIDENCE FOR A DEGRADATION PATHWAY FOR THYMIDINE.

The kinetics of [(3)H]thymidine incorporation into the DNA of carrot suspension cultures were investigated. At a thymidine concentration of 0.1 micromolar, incorporation into DNA is not quantitative but ceases after only 14% of the thymidine has been incorporated. Thymidine incorporation into DNA is resumed following addition of a second aliquot of thymidine, which is consistent with substrate depletion. In vivo tracer experiments indicate that this may be due to a catabolic route for converting thymidine to beta-aminoisobutyric acid. Bearing these observations in mind, conditions for determining the rate of DNA synthesis using [(3)H]thymidine incorporation have been investigated. It is concluded that by increasing the thymidine concentration to 10 micromolar the assay period may be increased, by reducing the influence of the degradative pathway, and that cell density and incubation time are critical factors in establishing a valid measure of the rate of DNA synthesis using this method.

Journal Article↗
PubMed1979

Lipoprotein lipids in chronic renal failure and haemodialysis. The influence of etiology and implications for atherogenesis.

Lipoprotein lipid analysis has been carried out in 39 women and 28 men with chronic renal failure on haemodialysis. The results have been analysed in relation to the etiology of the renal disease and compared with those obtained in age- and sex-matched controls and in triglyceride-matched controls. Serum cholesterol was normal or low in glomerulonephritis but was normal in analgesic nephropathy. Serum triglycerides and VLDL lipids were raised uniformly regardless of the etiology of the renal disease. LDL triglyceride and HDL triglyceride were also raised. LDL cholesterol and phospholipid were low in glomerulonephritis but were normal in analgesic nephropathy. HDL cholesterol was reduced in both male and female patients regardless of etiology, statistical significance was not reached for the women. The ratio of esterified to free cholesterol tended to be reduced in all the lipoproteins regardless of sex or etiology but the changes were not significant in all groups. Comparison of the lipid abnormalities with those found in other hyperlipidaemic states suggests that the lipid disorders found in chronic renal failure are probably insufficient to explain the rapid development of vascular disease which has been reported.

Adult↗
PubMed1975

Different selectivities in acylation and methylation pathways of phosphatidylcholine formation in guinea pig and rat livers.

Radioactivity from intraperitoneally or intraportally injected 1-acyl-snglycero-3-phosphorylcholine, doubly labelled in either palmitoyl, glycerol or phosphoryl moities, was incorporated largely into disaturated or mixed disaturated-oligoenoic fractions of phosphatidylcholine in guinea pig liver. In rat liver the tetraenoic class was the most highly labelled and only very low radioactivity was recovered from disaturated or monoenoic species. The methylation of phosphatidylethanolamine to phosphatidylcholine, as judged by the incorporation of intraperitoneally injected L-[Me-14 C] methionine, involved selectively tetraenoic and polyenoic (greater than 4 double bonds) classes in rat liver. In guinea pig liver, methylation activity was much lower and led to the formation principally of dienoic classes of phosphatidylcholine. These experiments confirm the work of others that in rat liver, which has a high level of polyunsaturated classes of phosphatidylcholine, the "indirect" pathways of synthesis give rise chiefly to these classes. However, the priorties in guinea pig liver are different, since the levels of polyunsaturated classes are much lower, and although the "indirect" pathways of synthesis are operative they are directed mainly toward the formation of more saturated classes.

Acylation↗
PubMed1970

Contingency counseling by school personnel: an economical model of intervention.

An Attendance Counselor contacted adults (mediators) who controlled reinforcers for six chronic nonattenders (targets); agreements (deals) were made between mediators and targets that reinforcers would be provided, contingent on school attendance. Absence of the Attendance Counselor from school for a two-week period constituted a reversal condition, after which the "deals" were reinstituted. Results showed a significant increase over baseline in school attendance during the time in which deals were in effect. A second study involved 20 chronic nonattenders for whom deals were arranged as in Study One (contingency counseling), and 15 nonattenders provided more traditional attendance counseling (contact counseling). Contingency Counselors achieved results with the 20 nonattenders similar to those achieved in Study One. An experienced Contact Counselor did not achieve improved school attendance among her group of 15 nonattenders.

Journal Article↗
PubMed1968

The dynamics of malaria.

Previous studies on dynamic systems of transmission of malaria, and of eradication of infection following the interruption of transmission, have now been adapted for advanced techniques using the facilities offered by computers.The computer programmes have been designed for a deterministic model suitable for a large community and also for a stochastic model relevant to small populations in which infections reach very low finite numbers. In this model, new infections and recoveries are assessed by the daily inoculation rate and are subject to laws of chance. Such a representation is closer than previous models to natural happenings in the process of malaria eradication. Further refinements of the new approach include the seasonal transmission and simulation of mass chemotherapy aimed at a cure of P. falciparum infections.These programmes present models on which the actual or expected results of changes due to various factors can be studied by the analysis of specific malaria situations recorded in the field. The value of control methods can also be tested by the study of such hypothetical epidemiological models and by trying out various procedures.Two specific malaria situations (in a pilot project in Northern Nigeria and in an outbreak in Syria) were studied by this method and provided some interesting results of operational value. The attack measures in the pilot project in Northern Nigeria were carried out according to the theoretical model derived from the basic data obtained in the field.

Disease Outbreaks↗