Diversity of epicotyl dormancy among tropical montane forest species in Sri Lanka.

Fruiting season of many Sri Lankan tropical montane species is not synchronised and may not occur when conditions are favourable for seedling establishment. We hypothesised that species with different fruiting seasons have different seed dormancy mechanisms to synchronise timing of germination with a favourable season for establishment. Using six species with different fruiting seasons, we tested this hypothesis. Germination and imbibition of intact and manually scarified seeds were studied. Effect of GA3 on germination was examined. Embryo length:seed length (E:S) ratio of freshly matured seeds and of those with a split seed coat was determined. Time taken for radicle and plumule emergence and morphological changes of the embryos were recorded. The radicle emerged from Ardisia missionis, Bheza nitidissima and Gaetnera walkeri seeds within 30 days, whereas it took >30 days in other species. Embryos grew in seeds of B. nitidissima and G. walkeri prior to radicle emergence but not in Microtropis wallichiana, Nothapodytes nimmoniana and Symplocos cochinchinensis. A considerable delay was observed between radicle and plumule emergence in all six species. Warm stratification and/or GA3 promoted germination of all species. All the tested species have epicotyl dormancy. Seeds of B. nitidissima and G. walkeri have non-deep simple morphophysiological epicotyl dormancy, and the other four species have non-deep physiological epicotyl dormancy. Differences in radicle and epicotyl dormancy promote synchronisation of germination to a favourable time for seedling development. Therefore, information on dormancy-breaking and germination requirements of both radicle and epicotyl are needed to determine the kind of dormancy of a particular species.

Ethnic differences in myocardial infarction in patients with hypertension: effects of diabetes mellitus.

BACKGROUND: It has been reported that hypertension carries a greater risk of myocardial infarction (MI) in South Asians living in the UK than in the indigenous British population. This has been attributed to some specifically Asian susceptibility factor. DESIGN: Using a longitudinal approach, we investigated the relationship between coronary heart disease (CHD) risk factors amongst hypertension patients attending Sandwell and City Hospitals, and the onset of cardiovascular events over a 5-year follow-up period. RESULTS: A total of 350 Caucasian (83.7% male) and 104 South Asian (66.3% male) patients with hypertension [age 63.7 (7.6) years and 57.1 (11.1) years respectively, P < 0.001] were followed-up for a mean (SD) period of 64.7(12.1) months. There were 11 (6.4/1000 patient years) cases of MI in Caucasian patients vs. 11 (17.8/1000 patient years) in South Asians, with event-free survival times being significantly lower amongst South Asians (log-rank test P = 0.04). The prevalence of diabetes mellitus was 22.9% higher amongst South Asians (P < 0.001), whilst mean serum cholesterol and fasting triglyceride levels were higher amongst Caucasians (P = 0.001). There were no ethnic differences in HDL cholesterol concentrations, the use of tobacco, statin therapy or anti-platelet therapies (all P = NS), or in composite endpoint (MI, angina, peripheral vascular disease, stroke, revascularization or death; P = 0.74). On Cox regression analysis of all independent cardiovascular risk variables, associated treatments and ethnicity, MI risk was associated with diabetes mellitus (odds ratio 3.77, 95%CI 1.55-9.15, P = 0.003) but not ethnicity per se (P = 0.26). CONCLUSION: Increased risk of MI in hypertensive South Asians in the United Kingdom appears to be the result of a higher prevalence of diabetes mellitus. Further work is required to understand the pathophysiological basis with which diabetes increases CHD risk in this ethnic group.

Secular trends in the cardiovascular risk profile and mortality of stroke admissions in an inner city, multiethnic population in the United Kingdom (1997-2005).

Our objective was to study ethnic differences in the cardiovascular risk profile and mortality of stroke admissions to an inner city teaching hospital serving a multiethnic population in Birmingham, UK, over a 9-year period (1997-2005). Hospital case notes and registry data of 3083 patients admitted with a first onset stroke were reviewed. Secular trends in the prevalence of risk factors (hypertension, diabetes, hyperlipidaemia, atrial fibrillation and myocardial infarction), hospital admission rates and 30-day mortality among Afro-Caribbean, European Caucasian and South Asian ethnic groups were analysed. Between 1997 and 2005, there were 3083 first onset strokes, of whom 47.6% (1595) were men, 9.3% Afro-Caribbean, 57.8% European Caucasian and 15.1% South Asian. There was a significant trend towards a reduction in non-haemorrhagic stroke admissions over the study period (P<0.001), with no ethnic variation (P=0.07). Increases in hypertension and hyperlipidaemia were observed (P<0.001), whereas myocardial infarction showed a decline (P<0.001). Compared to other ethnic groups, South Asian patients were younger on admission (P<0.001), had more hyperlipidaemia (P<0.05) and poorer survival at 30 days (P=002). We conclude that cardiovascular risk profiles among patients admitted with non-haemorrhagic stroke have changed over the last decade. In particular, hyperlipidaemia has increased, especially among South Asians. The reduced decline in stroke admissions and 30-day survival of stroke in South Asians in recent years warrants further investigation and highlights the importance of a targeted health-care approach in the migrant ethnic minorities.

Increased 5-year mortality in the migrant South Asian stroke patients with diabetes mellitus in the United Kingdom: the West Birmingham Stroke Project.

BACKGROUND: Stroke is a major cause of premature mortality in Britain, but its burden is markedly greater amongst South Asians. Because of the paucity of data in this area, we investigated the magnitude and impact of risk from cardiovascular comorbidities on survival amongst South Asian stroke patients. METHODS: We reviewed hospital case records of consecutive first in life time ischaemic stroke patients [self reported ethnicity and International Classification of Disease (ICD) 10th revision, codes 430-438] admitted to an inner city hospital in the UK between 1997 and 2001. In-hospital mortality data and CVD risk factors were analysed. Five-year mortality data was obtained from the National Health Tracing Services. RESULTS: Of 1474 ischaemic stroke patients, 242 (16%) were South Asian of whom, 143 (59.1%) were male. The prevalence of hypertension was 70.2%, followed by diabetes 56.2%, hyperlipidaemia 7% and myocardial infarction 10.3%. At 5 years follow-up, 40.5% had died. Cumulative event-free survival at 5 years was significantly poorer in patients with diabetes (log-rank test, p=0.009). On Cox regression analysis, incorporating age, gender and other CVD risk factors, diabetes mellitus was an independent predictor of mortality odds ratio=1.65 (1.02-2.6, p=0.039). Hypertension and dyslipidaemia did not discriminate survival amongst South Asian patients. CONCLUSION: Stroke mortality in South Asians is associated with presence of diabetes mellitus. This highlights the significance of early and intensive CVD risk modification strategies in ethnic minorities particularly in patients with diabetes. Further research is warranted in South Asians to examine the underlying basis and related pathophysiological abnormalities.