Cardiovascular Journal of South Africa - latest Issue
Volume 18, Issue 2, 2007
Cardiovascular effects of Persea americana Mill (Lauraceae) (avocado) aqueous leaf extract in experimental animals : cardiovascular topicSource: Cardiovascular Journal of South Africa 18, pp 69 –76 (2007)More Less
The cardiovascular effects of Persea Americana Mill (Lauraceae) aqueous leaf extract (PAE) have been investigated in some experimental animal paradigms. The effects of PAE on myocardial contractile performance was evaluated on guinea pig isolated atrial muscle strips, while the vasodilatory effects of the plant extract were examined on isolated portal veins and thoracic aortic rings of healthy normal Wistar rats in vitro. The hypotensive (antihypertensive) effect of the plant extract was examined in healthy normotensive and hypertensive Dahl salt-sensitive rats in vivo.
P americana aqueous leaf extract (25-800 mg/ml) produced concentration-dependent, significant (p < 0.05-0.001), negative inotropic and negative chronotropic effects on guinea pig isolated electrically driven left and spontaneously beating right atrial muscle preparations, respectively. Moreover, PAE reduced or abolished, in a concentration-dependent manner, the positive inotropic and chronotropic responses of guinea pig isolated atrial muscle strips induced by noradrenaline (NA, 10-10-10-5 M), and calcium (Ca2+, 5-40 mM). PAE (50-800 mg/ml) also significantly reduced (p < 0.05-0.001) or abolished, in a concentration-dependent manner, the rhythmic, spontaneous, myogenic contractions of portal veins isolated from healthy normal Wistar rats. Like acetylcholine (ACh, 10-8-10-5 M), the plant extract (25-800 mg/ml) produced concentration-related relaxations of isolated endothelium-containing thoracic aortic rings pre-contracted with noradrenaline. The vasorelaxant effects of PAE in the isolated, endothelium-intact aortic rings were markedly inhibited or annulled by NG-nitro- L-arginine methyl ester (L-NAME, 10-5 M), a nitric oxide synthase inhibitor. Furthermore, PAE (25-400 mg/kg iv) caused dose-related, transient but significant reductions (p < 0.05-0.001) in the systemic arterial blood pressure and heart rates of the anaesthetised normotensive and hypertensive rats used.
The results of this laboratory animal study indicate that PAE caused bradycardia, vasorelaxation and hypotension in the mammalian experimental models used. The vasorelaxant action of PAE was endothelium dependent, and was, therefore, possibly dependent on the synthesis and release of nitric oxide (NO). The vasorelaxant effects of PAE appeared to contribute significantly to the hypotensive (antihypertensive) effects of the plant extract. However, the findings of this study tend to suggest that P Americana leaf could be used as a natural supplementary remedy in essential hypertension and certain cases of cardiac dysfunctions in some rural Africa communities.
Unexpectedly high prevalence of target-organ damage in newly diagnosed Nigerians with hypertension : cardiovascular topicSource: Cardiovascular Journal of South Africa 18, pp 77 –83 (2007)More Less
Introduction: Hypertension remains a formidable cardiovascular problem in the entire world. Untreated or poorly controlled hypertension predisposes to target-organ damage and is often followed by serious cardiovascular events. Knowledge of the type and distribution of endorgan damage in newly diagnosed hypertensive patients would help to determine the interventions or preventative measures needed in such patients.
Objective: To assess target-organ involvement in newly diagnosed, untreated hypertensive patients presenting at the University College Hospital, ibadan, Nigeria.
Methods: Newly diagnosed hypertensive men and women were recruited consecutively into the study. Target-organ damage was assessed using electroctrocardiography, echocardiography, renal function assessment (including tests for albuminuria) and fundoscopy.
Results: A total of 68 subjects were recruited, but only 54 (79.4%), with a mean age of 59.1 (+ 12.4) years, completed the study. There were 29 (+ 53.7%) men, mean age 63.5 (+ 12.6) years, and 25 (46.3%) women, mean age 54.1 (+ 10.4) years. Fifty per cent of the subjects had no symptoms. Some form of albuminuria was found in about 40.7%. Seventy-one per cent (71%) had between grade 1 and 2 hypertensive retinopathy. Only six (11.1%) had glomerular filtration rate greater than 90 ml/min. Systolic function was impaired in three (5.6%) of the subjects. Diastolic dysfunction was present in 36 (66.7%) subjects.
Conclusion: Target-organ damage already exists in newly diagnosed hypertensive subjects before presentation. We suggest early screening for cardiovascular risk factors and possibly a reduction in the criteria for the definition of hypertension in black Africans.
Source: Cardiovascular Journal of South Africa 18, pp 84 –89 (2007)More Less
Hereditary spherocytosis consists of a group of haemolytic anaemias caused by defects in the proteins involved in the vertical interactions between the membrane skeleton and the lipid bilayer of the red blood cell. inheritance is most commonly autosomal dominant with variable expression. Splenectomy may be indicated because of anaemia or for the prevention of gall-stones. We describe a patient who presented with symptoms of pulmonary hypertension 32 years after splenectomy. idiopathic pulmonary arterial hypertension (iPAH) and chronic thromboembolic pulmonary hypertension (CTEPH) have been associated with splenectomy, while chronic haemolysis may result in haemolysis-associated pulmonary hypertension. We briefly discuss the current views on the pathophysiology, diagnosis and management of this rare condition.
Author Francois WesselsSource: Cardiovascular Journal of South Africa 18, pp 95 –96 (2007)More Less
Clinical results of GENRES should provide a platform to guide the choice of antihypertensive drug treatment : the AB/CD scheme : drug trends in cardiologySource: Cardiovascular Journal of South Africa 18 (2007)More Less
Atorvastatin cuts risk of coronary events by half in recurrent stroke patients : drug trends in cardiologySource: Cardiovascular Journal of South Africa 18 (2007)More Less
Targeting the reduction of atherosclerosis in low-risk individuals. METEOR trial provides support for rosuvastatin (Crestor) atherosclerosis regulatory submission : drug trends in cardiologySource: Cardiovascular Journal of South Africa 18 (2007)More Less