Response of two cultivars of Phaseolus vulgaris L. (French beans) plants exposed to enhanced UV-B radiation under mountain ecosystem.

Enhanced solar ultraviolet-B (UV-B) irradiance resulting from depletion in the ozone layer has the potential to cause detrimental effects on plants. Higher altitudes tend to receive higher doses of ambient UV-B radiation. The present study was carried out to assess the effects of enhanced UV-B (ambient + 10.2 kJ m(-2) day(-1)) radiation on two cultivars of Phaseolus vulgaris L. (cv. Pusa Himlata and Pusa Parvati) at growth, physiological, and biochemical levels grown under mountain ecosystem. The magnitudes of negative effects of enhanced UV-B radiation were found more in Pusa Parvati as compared to Pusa Himlata. Non-enzymatic (total phenolics and flavonoids content) and enzymatic antioxidants (superoxide dismutase, catalase, and peroxidase) were increased in both cultivars at both the ages of growth but increase was found more in Pusa Himlata as compared to Pusa Parvati. The study further showed that the economic yield of Pusa Himlata and Pusa Parvati was decreased by 14 and 44%, respectively, due to enhanced UV-B radiation. The higher decrease in the economic yield of Pusa Parvati depicted that increased amounts of total flavonoids content and stimulation of their antioxidant defense mechanism via increasing the activities of enzymatic antioxidants were not able to completely detoxify the produced reactive oxygen species under enhanced UV-B radiation and made it more sensitive to applied stress. From the present study, it can be concluded that enhanced UV-B radiation in the mountain areas of the Indian Himalayan Regions could be one of the environmental causes for lower yields of agricultural crops. Cultivation of P. vulgaris L. cv. Pusa Himlata should be promoted at higher altitudes of the Indian Himalayan Regions.

Effect of vitamin E administration on blood pressure following reperfusion of patients with myocardial infarction.

BACKGROUND: Reperfusion of infarcted myocardium by thrombolysis is the major technique used to restore blood supply. Reperfusion, however, is associated with a burst of oxygen consumption, with the resultant excessive generation of free radicals causing reperfusion injury. OBJECTIVE: In the present study, the effect of vitamin E administration on the status of free radical-mediated injury and blood pressure in post reperfusion hypertensive patients with myocardial infarction is assessed. METHOD: POST REPERFUSION HYPERTENSIVE PATIENTS WERE DIVIDED INTO THREE GROUPS: those not receiving a beta-blocker (group I), those receiving acetylsalicylic acid (ASA) plus a beta-blocker (group II) and those receiving ASA, a beta-blocker and 400 mg vitamin E (group III). Groups II and III were comprised of patients from group I. Levels of malondialdehyde (MDA) and xanthine oxidase (XO) activity in blood were used as an index of oxidative stress. These parameters, along with blood pressure, were monitored in these groups. RESULTS: Patients not receiving a beta-blocker had elevated levels of MDA and XO activity when compared with healthy persons (P<0.0005 both for MDA and XO). Compared with group I, patients receiving a beta-blocker plus ASA (group II) had a significant decrease in the activity of XO (P<0.005) and the levels of MDA (P<0.005). When vitamin E was incorporated in the treatment, there was highly significant decrease in these oxidative stress parameters compared with groups I and II (P<0.0005 for XO and MDA). Use of vitamin E as an adjuvant in hypertensive therapy (group III) resulted in better management of blood pressure (systolic P<0.005, diastolic P>0.05) when compared with group II. CONCLUSION: Inclusion of vitamin E in antihypertensive therapy in post reperfusion hypertensive patients results in better management of blood pressure.

Xanthine oxidase as a marker of myocardial infarction.

In the present communication, we report remarkably elevated levels of xanthine oxidase activity in the blood of the patients with myocardial infarction when compared to age and sex matched healthy persons. Highly significant increase of malondialdehyde, serving as an index of lipid peroxidation and thus free radical mediated damage, has also been found in the patients. We propose the measurement of the blood levels of xanthine oxidase, a very simple, reliable and less time consuming method as an indicator of myocardial infarction.

Effect of vitamin E on the platelet xanthine oxidase and lipid peroxidation in the patients of myocardial infarction.

Platelets play important role in precipitating ischaemic myocardial syndromes in many ways. One of the consequences of ischaemic diseases is excessive generation of oxygen derived free radicals that have numerous pathophysiological consequences. Platelet pro-oxidant enzyme, xanthine oxidase is one of the sources of generation of free radicals. In the present paper, we report the effect of administration of vitamin E along with aspirin on the levels of platelet xanthine oxidase and extent of free radical mediated damage in the patients reperfused after myocardial infarction.Our findings show that administration of 400 mg. vitamin E for six days along with 80 mg. aspirin has an excellent anti-oxidant effect as evidenced by reduced platelet xanthine oxidase activity and lowering of malondialdehdye (MDA) levels which is an index of the extent of free radical mediated damage.