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Biomedical subjects

G Macdonald

Publications and source records attributed to G Macdonald.

At least 19 recordsLinked to original sources
PubMed1995

Decontaminating dental instruments: testing the effectiveness of selected methods.

The decontamination of dental instruments before sterilization is designed to safeguard dental personnel from exposure to bloodborne pathogens and to remove gross contamination. The authors studied the relative effectiveness of decontamination methods that included ultrasonic cleaning, presoaking with an enzymatic cleaner and dishwashing. Results indicated that the most effective methods involved presoaking followed by cleaning. However, no single procedure eliminated detectable concentrations of blood contamination.

Analysis of Variance↗
PubMed1991

Physical characteristics of the hand and early clinical skills. Their relationship in a group of dental hygiene students.

Twelve hand measurements were made on 45 first-year dental hygiene students within one week of their entering a dental hygiene program. Multiple regression was performed, using three clinical examinations (use of periodontal probe, use of 3-A explorer, and use of Gracey curets) as dependent variables, to assess whether or not hand measurements predicted early clinical skill development. None of the hand measurements were predictive for the explorer examination. Wrist width accounted for 13% of the variance on the probing examination and 24% of the variance on the curet examination. Finger span added 16% variance to the equation. A total of 40% variance was explained by these measures on the curet examination. Results suggest that wrist width and finger span may be important predictors of early dental hygiene clinical skill development.

Aptitude Tests↗
PubMed1990

Uridine kinase inhibition is involved in the vasodilator effects of minoxidil in the rat.

1. Since minoxidil is a pyrimidine derivative, its actions on vascular smooth muscle may derive from structural relationships to the uridine nucleotides, which have been shown to be vasoconstrictive in the rat. 2. Minoxidil at a low vasodepressor dose of 0.03 mg/kg per min abolished the pressor response to uridine at doses from 2 to 8 mumol/kg per min, but did not reduce the responses to uridine monophosphate or uridine diphosphate in similar pressor doses, suggesting an action on either transport of uridine into cells or on uridine kinase which catalyses phosphorylation of uridine to uridine monophosphate, the mediator of uridine's vascular actions. 3. The active metabolite of minoxidil was found to inhibit rat liver uridine kinase in vivo using an HPLC technique. 4. Plasma uridine concentration was significantly higher in 11 hypertensive patients on minoxidil compared with pretreatment values, suggesting that uridine kinase inhibition is of a degree sufficient to increase the circulating pool of uridine. 5. The data is consistent with uridine kinase inhibition being a mechanism for the vasodilator actions of minoxidil.

Animals↗
PubMed1987

Effect of nifedipine on carbohydrate metabolism and serum lipoproteins in hypertensive patients with and without diabetes mellitus.

Newly diagnosed hypertensive patients, and patients with hypertension which was not controlled by their existing therapy, were studied in a single-blind, placebo-controlled trial. Criteria for inclusion in the study were a systolic blood pressure less than 160 mmHg and a diastolic blood pressure greater than 95 mmHg. The study group was composed of 15 non-diabetic patients, 14 patients with non-insulin dependent diabetes mellitus (NIDDM) and 13 patients with insulin-dependent diabetes mellitus (IDDM). Mean supine and erect, systolic and diastolic blood pressure were reduced in all three groups after 2 and 14-16 weeks of nifedipine therapy (P less than 0.001). Mean fasting blood glucose, mean haemoglobin A1, mean total serum cholesterol, mean high density lipoprotein (HDL) cholesterol and mean serum triglycerides were not affected by nifedipine in any of the three groups over the 14-16 weeks' treatment. Forty out of the 42 patients entering, completed the study. One patient with NIDDM and angina died from a myocardial infarction in the final 4 weeks of the study, and one non-diabetic patient was unable to tolerate nifedipine after two weeks of treatment and was withdrawn from the study. No patients were withdrawn due to treatment failure.

Adult↗
PubMed1987

The use of nitrendipine in the treatment of elderly hypertensives.

The ability of nitrendipine to control blood pressure (BP) over a 24-hour period was assessed in elderly patients over 65 years of age with a systolic BP (SBP) greater than 170 mmHg, and a diastolic BP (DBP) greater than 100-130 mmHg. Twenty-two patients were randomized equally to two groups: group 1 received the drug once daily and group 2, twice daily. The study was double-blind, with patients in group 1 receiving a matching placebo tablet instead of the second dose of nitrendipine before retiring to bed. Patients attended the hospital clinic at 10 a.m. before taking their morning tablet, so that BP was recorded 24 hours (group 1) or 12 hours (group 2) after nitrendipine. The study design permitted one dose titration if the target SBP of less than 170 mmHg or DBP of less than 100 mgHg was not achieved after three weeks of active therapy; the dose was doubled and the patients received 6 weeks of therapy at the preferred dosage. Mean DBP after 6 weeks' nitrendipine was comparable in the two groups and significantly lower than that with placebo (P less than 0.001), but mean systolic BP was lowered only in group 2 patients (P less than 0.001). There was no significant difference in mean SBP or DBP between patients on 20 mg daily and 10 mg b.d. Therefore, in elderly patients, once daily nitrendipine controls DBP as satisfactorily as the same daily dose given in two divided doses, but does not reduce SBP as adequately.

Aged↗
PubMed1987

The uridine nucleotides constitute a natriuretic pressor system.

1. Uridine monophosphate was tested in the conscious rat for natriuretic properties and an immunoperoxidase technique was used to localize uridine-containing compounds in the rat kidney. 2. Uridine monophosphate, infused in a moderate pressor dose, caused a significant natriuresis compared to the effect of control infusions of solvent vehicle. 3. Uridine-containing compounds were found in most tubular elements with particularly dense staining in the distal and collecting tubules. 4. While the increased sodium excretion may have been due to increased renal perfusion pressure, the high density of uridine staining in distal nephrons suggests that the uridine nucleotides have a specific nephron function, possibly relating to sodium transport.

Animals↗
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↗