PubMed Health⌕ Search

Biomedical subjects

A A Ajayi

Publications and source records attributed to A A Ajayi.

At least 55 records · Page 3Linked to original sources
PubMed1991

The effects of prednisolone and niacin on chloroquine-induced pruritus in malaria.

Chloroquine chemotherapy of malaria fever induces severe generalised pruritus in a large proportion of black Africans. In a double blind, placebo controlled, randomised, parallel group study in 28 historically chloroquine pruritus-reactor (R+) patients, with malaria, we evaluated the prophylactic and the palliative antipruritic actions of prednisolone (5 mg) or niacin (50 mg). There was a significant prophylactic effect of both drugs on the pruritogenecity of chloroquine as well as significant reduction in the area under the pruritus intensity-time curve, AUC(0-72 h) by niacin. The salutary effect both of niacin and prednisolone on chloroquine pruritogenecity resulted neither, in the mitigation of malaria parasite clearance, nor in the clinical amelioration following antimalaria therapy.

Adult↗
PubMed1991

Symptom-limited, self-paced walking in the assessment of cardiovascular disease in patients with and without heart failure: the predictive value of clinical, anthropometric, echocardiographic and ergonometric parameters.

The assessment of functional capacity in heart disease remains problematic, and it is unclear whether maximal exercise testing is physiologically reflective of the activities of daily living or the quality of life. We therefore employed a symptom-limited, self-paced walking protocol to assess the physical conditions of 41 Nigerian cardiac patients, with and without heart failure. The walking time, walking speed and distance as well as the energy expenditure (Kcal.min-1) were markedly reduced (P less than 0.001) in patients with heart failure (n = 26) compared to the cardiac patients not in failure (n = 15). The double product corrected for exercise time (an index of myocardial oxygen use) was, however, significantly higher (P less than 0.001) in the group with heart failure. Using multiple regression analysis, the parameters of self-paced walking capacity (distance, walking time, and speed) could reliably be predicted (r2 greater than 0.9) from age, body surface area, energy expenditure, and echocardiographic left ventricular dimension in the patients without heart failure. The presence of heart failure appeared to weaken the predictability of the regressions. A significant correlation was obtained between the self paced exercise time and the Bruce protocol treadmill time (r2 = 0.91, P = 0.004) in a subgroup of the patients with heart failure. Thus, the self-paced walking test is sensitive to changes in congestive heart failure and the exercise capacity can be predicted from age and biophysical parameters. The wider clinical usage of this modality, especially in frail patients, is hereby recommended.

Adult↗
PubMed1991

Angiotensin converting enzyme inhibitors in cardiovascular and renal disease in Africans: a review.

The discovery and clinical availability of ACE inhibitor drugs is a triumph of rational drug development and a land-mark in biochemical pharmacology and hypertension research. The clinical pharmacological properties and haemodynamics of the clinically available drugs, captopril and enalapril, are reviewed, as is their therapeutic efficacy in African patients with essential and renal hypertension and chronic congestive heart failure. ACE inhibitors act as balanced arteriolar vasodilators and venular dilators and do not excite a reflex tachycardia in contrast to other vasodilator drugs. Their efficacy is, at least in part, dependent on plasma renin activity, which is low in Blacks and in Africans. Consistent with this, is the poor response to ACE inhibitor monotherapy of essential hypertension in controlled studies in Africans. However, the compensatory neuroendocrine activation which occurs in malignant hypertension, renal failure and congestive heart failure and concurrent diuretic therapy appears to enhance the clinical response to ACE inhibitors in African patients.

Africa↗
PubMed1990

Correlation among radiologic, echocardiographic indices and self paced-exercise capacity in heart failure.

We investigated the relationships between the cardiothoracic ratio, M-mode echocardiographic indices and symptom-limited, self-paced exercise tolerance in 8 Nigerian patients with chronic stable congestive heart failure. Left ventricular diastolic dimension was inversely related to exercise duration; thus: log exercise time (sec) = 6.142-0.057x (r2 = 0.83, P less than 0.05), but was directly correlated to an index of myocardial oxygen demand, the ratio of the pressure rate product (PRP) to the exercise time; thus: log PRP/exercise time = 0.073x-3.04 (r2 = 0.87, P less than 0.05). These preliminary findings need extensive confirmatory evidence.

Echocardiography↗
PubMed1990

Sustained beneficial effects of enalapril in Africans with congestive heart failure.

A single blind, placebo controlled, dose-ranging 3 month study of the effects of enalapril on cardiovascular parameters, clinical status and self-paced exercise capacity was undertaken in 12 Nigerians with chronic heart failure. Enalapril exerted only a modest reduction in blood pressure and heart rate but significantly improved functional capacity (P less than 0.01), and prolonged self-paced exercise time (P less than 0.05) compared to the placebo baseline. The pressure rate product and the double product corrected for exercise time, an index of myocardial oxygen demand, exhibited a significant and sustained reduction on enalapril treatment (P less than 0.01). Concentration of sodium in the serum was significantly increased (P less than 0.05) but concentrations of potassium and creatinine were unaltered. These results demonstrate the sustained efficacy of enalapril in black Africans with heart failure and indicate no important racial difference in the response to inhibition of angiotensin converting enzyme in congestive heart failure.

Adult↗
PubMed1990

The cardiovascular and endocrine effects of cilazapril, a new angiotensin-converting enzyme inhibitor, in man.

The cardiovascular and renin-angiotensin-aldosterone effects of cilazapril, a new angiotensin-converting enzyme (ACE) inhibitor was evaluated in healthy Caucasians in a double-blind, placebo-controlled, cross-over study. Cilazapril significantly inhibited plasma ACE activity, with a peak inhibition of 82% at 2 h and a residual inhibition of 41% persisting at 24 h. There was a biphasic and significant hypotensive effect, corresponding temporally to plasma ACE inhibition (P less than 0.02, ANOVA). The hypotensive action was not accompanied by reflex tachycardia. Plasma renin activity rose significantly as a consequence of ACE inhibition (P less than 0.05, ANOVA) but plasma aldosterone was unaltered. Cilazapril is a potent ACE inhibitor with a rapid onset and prolonged duration of antihypertensive and endocrine effects. Studies of the effects on ACE inhibition on the renin-angiotensin system in Africans are required.

Administration, Oral↗
PubMed1989

Enalapril and hydrochlorothiazide in hypertensive Africans.

The antihypertensive efficacy both of angiotensin converting enzyme (ACE) inhibitors and thiazide diuretics has been claimed to be influenced by plasma renin activity, which declines with age and is low in blacks. In a double-blind, placebo-controlled, double-dummy, randomized, parallel-group preliminary study, the antihypertensive efficacy and tolerability of the ACE inhibitor enalapril (20 mg day-1) and hydrochlorothiazide (50 mg day-1) were evaluated and compared for 4 weeks in 20 African patients with essential hypertension. The two groups had similar baseline clinical features and serum Na+ and K+ levels. Hydrochlorothiazide caused a significant and sustained fall in erect blood pressure with a reflex tachycardia. Enalapril exerted only a modest antihypertensive action, but significantly reduced erect heart rate. Direct comparison of hydrochlorothiazide- and enalapril-induced hypotension suggested a greater fall in subjects on the thiazide. The 95% confidence limits for the thiazide-enalapril difference in antihypertensive action at the end of the study was 39.5 to -7.5 mm Hg systolic and 22.0 to -6.6 mm Hg diastolic. The maximal blood pressure fall after hydrochlorothiazide was positively correlated with age (r = 0.50; p less than 0.05), whilst that of enalapril was inversely related age to (r = -0.57, p less than 0.05). The results are compatible with the notion that ACE inhibitor monotherapy may be less effective than thiazide diuretic treatment in African and black patients with essential hypertension. The findings also support the concept that age and racial factors may influence the response to antihypertensive treatment.

Adult↗
PubMed1989

The influence of cilazapril on indices of autonomic function in normotensives and hypertensives.

1. In two single dose studies, acute blood pressure reduction with cilazapril was not associated with any significant change in supine or erect heart rate in either normotensives or hypertensives. 2. To investigate the lack of reflex cardioacceleration, a series of autonomic function tests was undertaken when there was maximum ACE inhibition, maximum evidence of angiotensin II withdrawal and the lowest blood pressure. 3. There was no evidence that cilazapril had any significant impact on indices of sympathetic nervous activity or the integrity of baroreflex mechanisms. 4. The results for the bradycardic response to apnoeic facial immersion, suggested enhanced parasympathetic activity, consistent with the withdrawal of the vagolytic actions of angiotensin II. 5. These results suggest that the absence of a heart rate response to ACE inhibition is not related to a profound sympatho-inhibitory effect or an impairment of baroreflex function. While there is some evidence of enhanced cardiac parasympathetic tone it seems unlikely that this is the sole explanation for the lack of cardioacceleration.

Adult↗
PubMed1989

Enalapril in African patients with congestive cardiac failure.

In a preliminary double-blind study in African patients with heart failure, enalapril tended to increase treadmill exercise duration relative to placebo (95% confidence interval--11.5 to 144.3 s). This was associated with a significant improvement in NYHA functional class and subjective well being (P less than 0.05 ANOVA) with a concomitant reduction in body weight (P less than 0.05 ANOVA). It significantly increased pulse pressure during forearm isometric exercise (P less than 0.05 ANOVA), but the Valsalva's manoeuvre and the orthostatic response were unchanged.

Adult↗
PubMed1989

A therapeutic audit in the management of hypertension in Nigerians.

The prevalence of hypertension in adult Nigerians is about 20% and hypertension remains a significant risk factor in cardiovascular morbidity and mortality. In Africans, hypertension carries a dismal prognosis, has a late clinical presentation and certain antihypertensives may be less effective. We therefore conducted a therapeutic audit in order to assess the initial cardiovascular risk profile of Nigerian patients as well as the safety and efficacy of different antihypertensive agents. A cross-sectional survey of 367 patients (M:F:2:1) modal age 25-44 years, mostly WHO II, enrolled in our clinic was undertaken. 56% had been on treatment for up to one year and 2% for longer than ten years. 12.5% had concomitant diabetes mellitus. Statistical analyses of drug efficacy were done by Spearman correlation and Analysis of Variance (ANOVA). The rank order of hypertensive efficacy was as follows: Thiazides (T) (r = 0.57, P less than 0.05), T + Methyldopa (M) (r = 0.91, P less than 0.001) T + M + Hydralazine (r = 0.92, P less than 0.001). Neither propranolol, nor frusemide showed significant overall efficacy. However, propranolol appeared efficacious in hypertensives with renal impairment. Postural dizziness was occasionally reported. Total mortality was 6% occurring mostly in the modal age group. Diabetic hypertensives had a 5 fold enhanced risk of a fatal outcome (X2 P less than 0.001). Our findings support a rational stepped care approach to pharmacotherapy of hypertension in black Africans, a cost-effectiveness analysis of common antihypertensives; it elucidates the associated adverse effects to patients, and draws attention to the lethality of concomitant hypertension and diabetes. Prospective large scale studies of the treatment of hypertension in Africans are required.

Adult↗
PubMed1988

Spectrum of treadmill exercise responses in Africans with normotension, essential hypertension and hypertensive heart failure.

Hypertension is an important and common risk factor for cardiovascular morbidity and mortality in Africans. In Africans, hypertension carries a more dismal prognosis for target organ damage. We therefore studied the influence of blood pressure on treadmill exercise performance in normotensives, hypertensives and patients with hypertensive heart failure, matched for age and sex. The spectrum of response was a progressive diminution of the systolic rise in blood pressure during exercise, exercise-induced tachycardia, exercise time, and maximal oxygen intake. There was an increase in functional aerobic impairment with a rank order from normotensives to WHO I hypertensives, then WHO II, with a non-linear extreme rise with the onset of heart failure. The results indicate that impaired exercise performance in African hypertensives occurs with the onset of ventricular hypertrophy, and that this is accentuated by the neuroendocrine response in congestive heart failure.

Adult↗
PubMed1988

Renin-angiotensin modulation of sympathetic reflex function in essential hypertension and in the elderly.

The renin-angiotensin system and the sympathetic nervous system are important control mechanisms in blood pressure regulation. A large body of in vitro and in vivo animal data indicate that angiotensin II regulates noradrenaline release and modifies sympathetic reflexes, although the physiological relevance of these to normal man remains unclear. It is established, however, that increasing age and hypertension independently modify autonomic responses in man. The hypothesis was therefore examined that angiotensin II exerts a pre-junctional effect on noradrenaline release and sympathetic cardiovascular function, in the elderly and in patients with essential hypertension. Inhibition of angiotensin-converting enzyme with enalapril and cilazapril, after short-term administration at doses sufficient to reduce circulating angiotensin II concentrations, did not alter sympathetically mediated orthostatic test, Valsalva's manoeuvre and cold pressor test, in young or elderly normotensives. Similarly, but in a separate study, the pressor, chronotropic and sympathoadrenal response to submaximal dynamic exercise were unchanged, following short-term converting enzyme inhibition in normal persons and essential hypertensive patients. These findings do not support a role for angiotensin II in presynaptic facilitation or post-junctional potentiation of noradrenergic transmission. It is proposed that the renin-angiotensin system exerts an independent, rather than a regulatory influence on sympathetic function in blood pressure control, in normal and hypertensive man.

Adult↗
PubMed1987

The relationship between serum enalaprilat concentration and the hypotensive effect in man.

The relationship between serum concentrations of the angiotensin converting enzyme inhibitor, enalaprilat, and its antihypertensive action was investigated using integrated pharmacokinetic-dynamic modelling techniques. The model was parameterized in terms of slope "m", describing the sensitivity to the fall of blood pressure, and an intercept term "i". A linear pharmacodynamic model: E = m. ce(t) + i, adequately characterized the concentration-effect relationship in most of the young (aged 22-30 years) and elderly normotensive subjects (aged 65-73 years). However, no age-related differences were seen, indicating that angiotensin II vasoconstrictor action is unaltered by senescence.

Adult↗
PubMed1986

Effects of angiotensin converting enzyme inhibitor, perindopril, on autonomic reflexes.

The effect of the angiotensin converting enzyme inhibitor, perindopril, on autonomic function was assessed in a double blind, placebo controlled, crossover study in 10 normotensive males. Eight milligram of perindopril given orally lowered blood pressure without a change in heart rate. Perindopril enhanced the vagally mediated heart rate variation with deep breathing. There was no impairment of the responses to either bicycle exercise at 175 W for 5 min or isometric handgrip. The pressor response to cold was not changed and the response to the Valsalva manoeuvre was unaltered. These results suggest that the absence of tachycardia after perindopril may be in part related, as has been reported with other converting enzyme inhibitors, to enhanced cardiac parasympathetic tone. Vagomimetic action may be a property of converting enzyme inhibitors in general.

Adolescent↗
PubMed1986

Captopril and opiate antagonism in essential hypertension.

Six patients maintained on 50-100 mg captopril, for 2-25 months, were administered captopril 50 mg orally, together with either naloxone or 0.9% saline vehicle (placebo) given intravenously, in a double-blind crossover study. Naloxone did not appear to modify the circulatory effects of captopril in these patients, in contrast to earlier findings after acute captopril administration in normotensives. The results do not support an important endogenous opioid role in the chronic antihypertensive effect of captopril, but provide evidence that different mechanisms may contribute to the early short term falls in blood pressure, compared to the later long term effects.

Adult↗