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Biomedical subjects

A G Logan

Publications and source records attributed to A G Logan.

86 records · Page 5Linked to original sources
PubMed1978

Measurement of single nephron filtration rate in the kidney of the river lamprey, Lampetra fluviatilis L.

1. The reliability of [3H]inulin as a reference substance for the measurement of glomerular filtration rate (GFR) in river lampreys was investigated. 2. Simultaneously measured renal clearances of [3H]inulin and [14C]-polyethylene glycol (PEG) were not significantly different. 3. Recoveries of [3H]inulin in the urine following its injection into the proximal tubule and urinary duct averaged 83.5+/-4.0% (n = 14) and 93.0+/-4.6% (n = 9) respectively. 4. No evidence was obtained to suggest penetration of the tubular wall by by [3H]inulin following its introduction into peritubular capillaries. 5. Gel-filtration of lamprey plasma and urine produced no signs of any significant degradation of the inulin to fructose. 6. [3H]inulin recoveries, though significantly below 100% (P less than 0.001), were considered adequate to justify its use after allowing for possible sources of error. 7. A mean single nephron filtration rate (SNGFR) value of 7.02+/-0.27 nl/min (n = 89) was obtained from the kidneys of anaesthetized freshwater lampreys. 8. [51 Cr]EDTA was found to be totally unsuitable for the measurement of GFR in this species.

Animals↗
PubMed1975

Blockade of renin release by lanthanum.

1. The effects of lanthanum on renin release and renal vasoconstriction were studied in the isolated perfused rat kidney. 2. Lanthanum reduced noradrenaline-induced renal vasoconstriction. 3. Lanthanum prevented isoprenaline-induced and glucagon-induced stimulation of renin secretion.

Animals↗
PubMedDate not supplied

Effect of reduced dietary sodium on blood pressure: a meta-analysis of randomized controlled trials.

OBJECTIVE: - To ascertain whether restriction of dietary sodium lowers blood pressure in hypertensive and normotensive individuals. DATA SOURCES: - An English-language computerized literature search, restricted to human studies with Medical Subject Heading terms, "hypertension," "blood pressure," "vascular resistance," "sodium and dietary," "diet and sodium restricted," "sodium chloride," "clinical trial," "randomized controlled trial," and "prospective studies," was conducted. Bibliographies of review articles and personal files were also searched. TRIAL SELECTION: - Trials that had randomized allocation to control and dietary sodium intervention groups, monitored by timed sodium excretion, with outcome measures of both systolic and diastolic blood pressure were selected by blinded review of the methods section. DATA EXTRACTION: - Two observers extracted data independently, using purpose-designed forms, and discrepancies were resolved by discussion. DATA SYNTHESIS: - The 56 trials that met our inclusion criteria showed significant heterogeneity. Publication bias was also evident. The mean reduction (95% confidence interval) in daily urinary sodium excretion, a proxy measure of dietary sodium intake, was 95 mmol/d (71-119 mmol/d) in 28 trials with 1131 hypertensive subjects and 125 mmol/d (95-156 mmol/d) in 28 trials with 2374 normotensive subjects. After adjustment for measurement error of urinary sodium excretion, the decrease in blood pressure for a 100-mmol/d reduction in daily sodium excretion was 3.7 mm Hg (2.35-5.05 mm Hg) for systolic (P<.001) and 0.9 mm Hg (-0.13 to 1.85 mm Hg) for diastolic (P=.09) in the hypertensive trials, and 1.0 mm Hg (0.51-1.56 mm Hg) for systolic (P<.001) and 0.1 mm Hg (-0.32 to 0.51 mm Hg) for diastolic (P=.64) in the normotensive trials. Decreases in blood pressure were larger in trials of older hypertensive individuals and small and nonsignificant in trials of normotensive individuals whose meals were prepared and who lived outside the institutional setting. CONCLUSION: - Dietary sodium restriction for older hypertensive individuals might be considered, but the evidence in the normotensive population does not support current recommendations for universal dietary sodium restriction.

Blood Pressure↗
PubMedDate not supplied

Personality differences between hypertensive and normotensive individuals: influence of knowledge of hypertension status.

Personality characteristics such as anxiety and anger have long been associated with essential hypertension, but the results of past studies have often been confounded by inadequate diagnosis of hypertension, antihypertensive medications, and use of unvalidated measures of personality. Moreover, little attention has been given to the importance of differential exposure to medical attention and labeling as determinants of personality. To overcome these shortcomings, personality characteristics were measured by self-report using validated questionnaires in untreated male and female hypertensives who were either aware (n = 80) or unaware (n = 82) of their hypertension at the time of assessment. Hypertension diagnosis was based upon repeated blood pressure measurements over 5 months. Hypertensives were compared to age-, sex-, ethnicity-, and occupation-matched normotensives. Results indicated that aware hypertensives scored significantly higher than normotensives and unaware hypertensives on neuroticism, trait and state anxiety, and self-reported Type A behavior. They also scored higher than normotensives on state anger, and there was a similar trend for anger suppression. There were no differences between unaware hypertensives and normotensives. The findings suggest that these personality factors are not a fundamental characteristic of hypertension but reflect the influence of exposure to medical attention or knowledge of hypertension status.

Adult↗
PubMedDate not supplied

Relaxation behavior therapy as sole treatment for mild hypertension.

This study tested the efficacy of relaxation therapy as sole treatment for mild hypertension in 110 men and women recruited from a five-stage worksite blood pressure screening program. Participants were randomized to 12-weeks of relaxation therapy or support therapy. Outcome blood pressure assessments made by assessors who were unaware of group allocation revealed similar decreases in both treatment groups at post-treatment and 6-month follow-up. While body weight did not change, alcohol consumption decreased similarly in both groups, and alcohol consumption was positively correlated with both absolute diastolic blood pressure and change in diastolic blood pressure at outcome. In conclusion, a superior blood pressure effect was not associated with relaxation therapy; however, alcohol consumption decreased in both treatment groups, suggesting that both interventions facilitated changes in health risk behaviors and indirectly on blood pressure level.

Adult↗
PubMedDate not supplied

Cost-effectiveness of a worksite hypertension treatment program.

The cost-effectiveness of treating hypertension at the patient's place of work was compared in a randomized controlled trial with care delivered in a community. The average total cost per patient for worksite care in this 12-month study was not significantly different from that for regular care ($242.86 +/- 6.94 vs $211.34 +/- 18.66, mean +/- SEM). The worksite health system cost was significantly more expensive ($197.36 +/- 4.99 vs $129.33 +/- 13.34, p less than 0.001) but the patient cost was significantly less ($45.40 +/- 3.23 vs $82.00 +/- 6.20, p less than 0.01). The mean reduction in diastolic blood pressure (BP) at the year-end assessment was significantly greater in the worksite group (12.1 +/- 0.6 vs 6.5 +/- 0.6 mm Hg, p less than 0.001). The incremental cost-effectiveness ratio of $5.63 per mm Hg for worksite care was less than the base cost-effectiveness ratio of $32.51 per mm Hg for regular care, indicating that the worksite program was substantially more cost-effective. Our findings support health policies that favor allocating resources to work-based hypertension treatment programs for the target group identified in this study.

Adolescent↗
PubMedDate not supplied

Clinical effectiveness and cost-effectiveness of monitoring blood pressure of hypertensive employees at work.

In this randomized controlled trial, the value of using occupational health nurses (OHNs) to monitor the care of hypertensive employees at work was compared with regular care (RC) delivered in the community. One year after entry, the blood pressure level, medication history, compliance with treatment, and cost of hypertensive care of the participants were determined by independent evaluators. The reduction in diastolic blood pressure (DBP), the measure of effectiveness, was 10.5 +/- 1.1 mm Hg (mean +/- SEM) in the OHN group and 7.7 +/- 1.1 mm Hg in the RC group, and the proportion under good blood pressure control was 41.8% and 31.0% respectively. These between-group differences were not statistically significant. Although the employees in the OHN group were more medicated and had a lower treatment dropout rate, neither difference was statistically significant. In addition, the proportion of employees who were compliant with prescribed medication was virtually identical in both groups. The cost of the care received by employees in the OHN group of $ 404.14 for the year was substantially higher than that of $ 250.15 in the RC group with the difference principally related to the cost of visiting the OHNs and a significant difference in drug cost (p less than 0.006). The incremental cost-effectiveness (C/E) ratio of $ 53.67 per mm Hg DBP reduction per year for onsite blood pressure monitoring was higher than the base C/E ratio of $ 32.65 per mm Hg for regular care. Our findings indicate that monitoring the blood pressure of hypertensive employees at work is neither clinically effective nor cost-effective.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

The P-wave in the electrocardiogram of hypertensive patients before and after therapy.

P-wave areas in the electrocardiogram (ECG) of 51 patients with hypertension and of 53 normotensive controls were measured in lead V1 using a computerised planimeter. The total area (in mm2) of P-waves was significantly larger in hypertensives than in normotensives, i.e. males 0.59 vs 0.31; females 0.55 vs 0.26 (p less than .0001) respectively. With exception of one male, the P-waves in hypertensives were either negative or biphasic with terminal negativity. In part 2 of the study, P-wave areas of 84 hypertensives were measured prior to and five years after treatment. The patients had no previous antihypertensive therapy, a diastolic blood pressure (DBP) 90-104 mmHg at the onset of the study, no ECG signs of left ventricular hypertrophy (LVH), and DBP less than 85 mmHg at the end of the trial. After five years, the mean values of the P-wave areas (in mm2) decreased in white males from 0.67 to 0.36; in white females from 0.63 to 0.42; in black males from 0.97 to 0.56; and in black females from 0.80 to 0.46. We conclude that ECG P-wave area is significantly larger in untreated hypertensives compared with normotensives. In successfully treated hypertensives, the P-wave area returns to normal values.

Blood Pressure↗