Search PubMed⌕ Search

Biomedical subjects

A G Logan

Publications and source records attributed to A G Logan.

At least 73 records · Page 4Linked to original sources
PubMed1985

Alterations in red cell cation transport in hypertensive disorders of pregnancy.

The results of a cross-sectional study of alterations in red cell Na-Li countertransport in hypertensive disorders of pregnancy indicated that the mean value of Na-Li countertransport increased with gestational age in pregnant normotensives but not in pregnant chronic hypertensives. In addition the mean value was significantly higher in pregnancy-induced hypertensives than in pregnant normotensives. Moreover the mean value falls to a level observed in non-pregnant normotensives in the late post-partum period and no difference was observed between women with normal blood pressure and chronic hypertension. In a prospective study of 62 pregnant normotensives, Na-Li countertransport increased and the Na-K cotransport decreased throughout their pregnancy. Finally, increased amounts of endogenous digoxin-like substance can be detected in the sera from some pre-term infants.

Adult↗
PubMed1984

Report of the Canadian Hypertension Society's consensus conference on the management of mild hypertension.

Since the publication in 1977 of joint recommendations by the Canadian Cardiovascular Society, the Canadian Heart Foundation and the Ontario Council of Health on the detection and management of hypertension in Canada, several clinical trials on the efficacy of antihypertensive drug treatment in patients with mild hypertension have been undertaken. The Canadian Hypertension Society (CHS) felt that the results of these trials should be reviewed to determine whether existing recommendations on treatment should be changed. Three expert panels appointed by the CHS reviewed evidence on the clinical efficacy of antihypertensive therapy, the diagnosis of hypertension and the treatment of mild hypertension, and formulated recommendations on the care of mildly hypertensive patients in Canada. A consensus conference of biomedical scientists, practising physicians and government representatives reviewed and reached agreement on the panels' recommendations. The final recommendations of the conference are presented in this report.

Adolescent↗
PubMed1984

Failure of weight reduction to reduce mildly elevated blood pressure: a randomized trial.

To determine the value of weight reduction on blood pressure, we randomly allocated 60 untreated, mildly hypertensive, obese individuals to a no-treatment control group or to a behaviourly-oriented weight loss ('diet') programme administered by professional dietitians. Behavioural techniques included self-monitoring, shaping, reinforcement and modelling. Subjects were reassessed after six months by an observer who was unaware of their study group. Fifty-four subjects (90%) completed the study. Diet subjects lost 4.1 kg and controls only 0.8 kg (P = 0.018). However, neither systolic nor diastolic blood pressures differed. The chance that we missed a clinically important diastolic difference of 6 mmHg (our pre-study target) is less than 1%. We conclude that our weight loss programme was successful in reducing weight but that weight loss is not useful in lowering blood pressure in mild, otherwise untreated hypertensives.

Blood Pressure↗
PubMed1983

The effect of patient 'familiarity' with blood pressure assessment on the accuracy of follow-up readings.

The fall in blood pressure that is commonly observed when groups of hypertensive individuals are followed without treatment is usually ascribed to two sources: regression towards the mean and increasing familiarity of the subject with the assessment process. Any effect of the latter process could bias the results of controlled studies in which one group is more frequently assessed than the other, a common situation in community trials. To assess the effect of familiarity, we randomly allocated 116 untreated, mildly hypertensive subjects to three-monthly or yearly assessments. At an independent, blind, year end assessment, both groups showed statistically significant reductions in diastolic blood pressure (P less than 0.001) of 8.4 +/- 1.2 (s.e.m.) and 7.6 +/- 1.6 mmHg respectively, but the difference between the groups was not significant (P = 0.682). We conclude that 'familiarity' does not play an important role in the reduction of blood pressure in long-term follow-up studies of hypertensive subjects.

Adult↗
PubMed1983

Liquid-chromatographic determination of nadolol in plasma.

We describe a liquid-chromatographic procedure for determining nadolol in plasma. After an analog of nadolol is added as internal standard, the plasma sample is passed through a disposable BondElut C18 column. After several column washes, nadolol and the internal standard are eluted with methanol, and the eluate is evaporated and reconstituted with the mobile phase (acetonitrile/water, perchloric acid, and tetramethylammonium hydroxide). An aliquot of the extract is chromatographed on a non-silica resin-base reversed-phase column. The peaks are detected by fluorescence (lambda ex = 265 nm and lambda em = 305). Drug and internal standard are well resolved, and only a few extraneous peaks appear. The standard curve ranges from 10 to 400 micrograms/L. We are using this procedure to determine steady-state concentrations of nadolol in patients receiving various dosages of nadolol along with other types of antihypertensive drugs.

Antihypertensive Agents↗
PubMed1982

Percutaneous transluminal dilatation of the renal artery: follow-up studies on renovascular hypertension.

Percutaneous transluminal dilatation of 80 renal artery stenoses was attempted in 68 patients. The procedure was technically successful in 58 (85%) patients. Fifty (86%) of the 58 patients were initially cured or improved. Life-table analysis of this group gives a cumulative success rate of 81% for a 3 year period. Hypertension recurred in only seven patients. There were no deaths related to the procedure, but four major complications occurred, including two secondary nephrectomies.

Adolescent↗
PubMed1980

Labetalol: potent antihypertensive agent that blocks both alpha- and beta-adrenergic receptors.

Labetalol was administered as the sole antihypertensive agent to 20 ambulatory patients with mild to moderate hypertension. The mean systolic and diastolic blood pressures (+/- standard error of the mean) with the patients sitting fell significantly (P < 0.001), from 145.5 +/- 3.2 and 103.7 +/- 1.6 mm Hg respectively at the start of labetalol therapy (after a period free of antihypertensive medication) to 125.7 +/- 2.0 and 87.2 +/- 1.1 mm Hg by the end of the trial. The diastolic blood pressure was well controlled (90 mm Hg or less) with labetalol therapy in 90% of the patients. The medication was well tolerated, and no orthostatic fall in the diastolic blood pressure was observed. Pharmacologically labetalol most closely resembles a combination of a nonselective beta-adrenergic blocker like propranolol and a postsynaptic alpha-adrenergic blocker like prazosin.

Adult↗
PubMed1980

The anatomy and blood system of the kidney in the river lamprey, lampetra fluviatilis.

The anatomy and blood system of the kidney in the river lamprey, Lampetra fluviatilis, was studied after injecting microfil into nephrons or the arterial system. Renal arteries arose at irregular intervals from the dorsal aorta and gave rise to a regular arrangement of afferent arterioles supplying the network of glomerular capillaries. Nephron units were arranged in two longitudinal series on each side of the glomerular capillaries, with the capsule of each nephron closely related to the capillary network. A short neck segment lead into the convoluted proximal segment, which accounted for over half the length of each nephron and was surrounded by a network of capillaries and sinusoids supplied by efferent glomerular arterioles. The end of each proximal segment formed the descending limb of a nephron loop, which lay parallel to the ascending distal limb and the end of each collecting duct. Peritubular blood flow in this region was generally opposite the flow of tubular fluid and blood eventually drained into large thin-walled sinuses connected to the post-cardinal vein.

Animals↗
PubMed1980

High performance liquid chromatographic analysis of urinary catecholamines employing amperometric detection: references values and use in laboratory diagnosis of neural crest tumors.

We have developed an high performance liquid chromatographic procedure employing amperometric detection for the measurement of urinary free norepinephrine, epinephrine and dopamine. The between-day precision (C.V.) at various concentrations of the above analytes varied from 4.8-11.6%. There was negligible between-urine difference in the percent recovery of norepinephrine and epinephrine but considerable between-urine difference for dopamine. The procedure has been used to determine reference ranges in infants, children and adults. Its preliminary application to the laboratory detection of neural crest tumors is also described.

Adolescent↗
PubMed1980

A micropuncture study of kidney function in the river lamprey Lampetra fluviatilis adapted to sea water.

Micropuncture techniques have been used to investigate kidney function in lampreys adapted to hyperosmotic media. Plasma electrolyte concentrations were maintained well below corresponding concentrations in the external environment. Urine composition was variable, but generally showed high concentrations of magnesium, sulphate and chloride ions. Lampreys in 50% sea water produced urine which was hypo or iso-osmotic to plasma, whereas those in 100% sea water produced hyperosmotic urine. Urine flow rate in 50% sea water was one tenth of that in fresh water, due to a reduction in filtration rate and an increase in water reabsorption by the kidney. As in fresh water, little if any filtered water was reabsorbed by the proximal segment. Almost 90% of filtered water was reabsorbed by the kidney of 100% sea water lampreys and most of this must have occurred in the distal and collecting segments.

Adaptation, Physiological↗
PubMed1979

Work-site treatment of hypertension by specially trained nurses. A controlled trial.

The clinical efficacy of using specially trained nurses to treat hypertension at the patient's place of work was compared in a controlled trial with management by the patient's family doctor. The 457 study participants were selected from 21 906 volunteers in industry and government whose blood-pressure was screened. The nurses were allowed to prescribe and change drug therapy at the work site without prior physician approval. Patients randomly allocated to receive care at work were significantly more likely to be put on antihypertensive medications (94.7% vs 62.7%, to reach goal blood-pressure in the first six months (48.5% vs 27.5%), and to take the drugs prescribed (67.6% vs 49.1%). Only 6% of patients were dissatisfied with the care provided by the nurses. Thus provision of care at work by specially tranined nurses was well accepted and resulted in significantly improved blood-pressure control and medication compliance among employees with asymptomatic and uncomplicated hypertension.

Adolescent↗
PubMed1979

High performance liquid chromatographic analysis of hydrochlorothiazide in serum and urine.

We report a high performance liquid chromatographic method for the analysis of hydrochlorothiazide in 500microliter of serum of 25 microliter of urine. The between-day precision of the analysis (CV 5.0-7.0%) is acceptable, as is the recovery of hydrochlorothiazide (90-96%) and trichloromethiazide (96%) added to serum. No drug or drug metabolite interferences have been noted. The method represents a considerable improvement over existing techniques described in the literature.

Chromatography, High Pressure Liquid↗