The role of oxidative stress, antioxidants and vascular inflammation in cardiovascular disease (a review).

The concept of mild chronic vascular inflammation as part of the pathophysiology of cardiovascular disease, most importantly hypertension and atherosclerosis, has been well accepted. Indeed there are links between vascular inflammation, endothelial dysfunction and oxidative stress. However, there are still gaps in our understanding regarding this matter that might be the cause behind disappointing results of antioxidant therapy for cardiovascular risk factors in large-scale long-term randomised controlled trials. Apart from the limitations of our knowledge, limitations in methodology and assessment of the body's endogenous and exogenous oxidant-antioxidant status are a serious handicap. The pleiotropic effects of antioxidant and anti-inflammation that are shown by some well-established antihypertensive agents and statins partly support the idea of using antioxidants in vascular diseases as still relevant. This review aims to provide an overview of the links between oxidative stress, vascular inflammation, endothelial dysfunction and cardiovascular risk factors, importantly focusing on blood pressure regulation and atherosclerosis. In view of the potential benefits of antioxidants, this review will also examine the proposed role of vitamin C, vitamin E and polyphenols in cardiovascular diseases as well as the success or failure of antioxidant therapy for cardiovascular diseases in clinical trials.

The harmful effects of consumption of repeatedly heated edible oils: a short review.

It has been a regular practice to repeatedly heat the cooking oil and consume it without knowing the harmful effects of such. The procedure to use repeatedly heated cooking oil is aimed to curb the cost of expenses. Heating results is the formation of free reactive oxygen species (ROS) which is responsible for the oxidative stress and damage to various organs in the body. The present review article discusses the harmful events occurring due to consumption of repeated heating of edible oil. A strong message is aimed to generate public awareness of the deleterious effects of consumption of heated edible oil which may help in curbing hypertension and atherosclerosis.

Effect of curcumin on aortic changes in ovariectomized rats fed with repeatedly heated soy oil: a preliminary electron microscopic study.

BACKGROUND AND AIMS: Consumption of repeatedly heated soy oil has been linked with incidence of atherosclerosis particularly in oestrogen deficient states. In the present study, effect of curcumin extract on the prevention of atherosclerosis was evaluated. MATERIALS AND METHODS: Forty eight female Spraque-Dawley rats (weighing 200-250 gm) were divided into eight groups. All groups were fed with 2% cholesterol diet. The sham control groups consisted of vitamin E free-RBD Olein (IV62) that acted as vehicle, and curcumin treated groups without undergoing ovariectomy. The other six groups were subjected to ovariectomy and later treated with vehicle-only, curcumin-only, once heated soy oil (1HSO) with vehicle, 1HSO with curcumin, five times heated soy oil (5HSO) with vehicle and 5HSO with curcumin. Curcumin was administered orally at a dose of 50 mg/kg which was commenced two weeks following ovariectomy. Following four months, the rats were sacrificed and serial sections of arch of aorta were harvested and processed for electron microscopic studies (EM). RESULTS: EM studies showed thickened tunica intima, fenestration of internal elastic lamina and migration of smooth muscle cells from tunica media to tunica intima in the ovariectomized control, 1HSO and 5HSO treated groups, with the latter being most prominent. There were no significant ultra structural changes in the curcumin-treated groups compared to the non-treated groups. CONCLUSION: Oral administration of curcumin at a dose of 50 mg/ kg body weight did not show any changes in the aorta of the ovariectomized rats fed with 2% cholesterol and heated soy oil.

Reheating of soy oil is detrimental to bone metabolism in oestrogen deficient rats.

INTRODUCTION: The short-term and long- term effects of heated soy oil on bone metabolism in ovariectomised Sprague-Dawley rats were studied. METHODS: Three-month-old female rats, were divided into five groups: normal control (NC); ovariectomised control (OVXC); ovariectomised and fed rat chow with added fresh soybean oil (SOF) or once-heated soy oil (SO1) or five-times-heated soy oil (SO5). Short-term parameters measured after one month were serum interleukin-6 (IL-6) and osteocalcin. Long-term parameters measured after six months were the structural bone histomorphometrical parameters. Vitamin E content in the soy oil subjected to the different heating treatments were also measured. RESULTS: Rats in the SO5 group had higher levels of IL-6 after one month compared to the other four groups. Osteocalcin levels in the SO1 and SO5 groups remained high after treatment, while those in the NC and SOF groups declined. After six months, bone mass declined in the SO5 group. Vitamin E assay in the oils showed that levels of alpha-tocopherol decreased after heating the oil once and five times, while levels of gamma- and delta-tocopherols only declined after heating five times. CONCLUSION: Repeated heating of soy oil destroyed the tocopherols causing raised serum IL-6 and osteocalcin levels, leading to increased bone resorption and osteoporosis in the long term.

The effects of repeatedly heated frying oil and high cholesterol diet on the bone in ovariectomised rats.

The use of repeatedly heated frying oils and intake of high cholesterol diet have been linked to bone damage. The aim of this study is to determine the combined effects of taking repeatedly heated frying oils (palm or soy oil) and high cholesterol diet on the dynamic histomorphometric parameters of bone. Ovariectomised rats were used as animal model of post-menopausal osteoporosis. After six months of treatment, Double-labeled Surface (dLS/BS), Mineralising surface (MS/BS) and Bone Formation Rate (BFR/BS) of ovariectomised rats (OvxC) were significantly reduced compared to the normal control group. Additions of fresh or once-heated palm or soy oil into high cholesterol diet seem to have improved the dynamic parameters towards the normal control values. However, when these oils were repeatedly heated, the protective effects were lost and the dynamic parameters except MS/BS dropped back towards the ovariectomised-control values.

The effects of repeatedly heated frying oil and high cholesterol diet on the bone in ovariectomised rats

The use of repeatedly heated frying oils and intake of high cholesterol diet have been linked to bone damage. The aim of this study is to determine the combined effects of taking repeatedly heated frying oils (palm or soy oil) and high cholesterol diet on the dynamic histomorphometric parameters of bone. Ovariectomised rats were used as animal model of post-menopausal osteoporosis. After six months of treatment, Double-labeled Surface (dLS/BS), Mineralising surface (MS/BS) and Bone Formation Rate (BFR/BS) of ovariectomised rats (OvxC) were significantly reduced compared to the normal control group. Additions of fresh or once-heated palm or soy oil into high cholesterol diet seem to have improved the dynamic parameters towards the normal control values. However, when these oils were repeatedly heated, the protective effects were lost and the dynamic parameters except MS/BS dropped back towards the ovariectomised-control values.

Comparative effects of a tocotrienol-rich fraction and tocopherol in aspirin-induced gastric lesions in rats.

This study examined the effects of a tocotrienol-rich fraction (TRF) obtained from palm oil on the healing of aspirin-induced gastric mucosal lesions. Thirty-six male Sprague-Dawley rats (200-250 g) were randomly divided into three groups. Group I was fed a vitamin E-deficient diet (control), Group II was fed a vitamin E-deficient diet supplemented with tocopherol (300 mg/kg food) and Group III was fed a vitamin E-deficient diet supplemented with TRF (300 mg/kg food). After eight weeks, the control and treated groups received a single intragastric dose of 400 mg/kg body weight aspirin. The rats were killed 24 h after exposure to aspirin. Assessment of gastric lesions showed a lower gastric lesion index in the TRF (P = 0.0005) and tocopherol groups (P = 0.0008) compared to the control. The gastric malondialdehyde (MDA) content was also lower in the TRF (P = 0.025) and tocopherol groups (P = 0.025) compared to control. There were, however, no significant differences in the gastric lesion index and gastric MDA content between the TRF and tocopherol-fed groups. There were no significant differences in the adherent gastric mucous concentration and gastric acid concentration among all groups. We conclude that the TRF and tocopherol are equally effective in preventing aspirin-induced gastric lesions. The most probable mechanism is through their ability to limit lipid peroxidation, which is involved in aspirin-induced gastric lesions.

Effect of nicardipine on fasting plasma lipids and apolipoproteins in male new zealand white rabbits.

The effect of nicardipine on fasting plasma lipid profiles was studied in rabbits given a 2% cholesterol diet. Twenty four New Zealand White rabbits (2.2 - 2.8 kg) were divided into 3 groups. Group 1 (control) was fed a normal diet, group II (HC) was fed a 2% cholesterol diet and group III (HC+NICA) was fed a 2% cholesterol diet with nicardipine treatment (0.5mg kg(-1) body weight twice daily intramuscularly for 10 weeks). The following parameters which included fasting plasma total cholesterol, triglycerides, HDL cholesterol and apolipoprotein A and B were measured before and after 10 weeks of study. In the present study we observed that a 2% cholesterol diet caused a significant increase in plasma total cholesterol, LDL cholesterol, HDL cholesterol and triglycerides. However, the increase in total cholesterol and LDL cholesterol were not prevented by treatment with nicardipine. Nicardipine appeared to cause further increase in HDL cholesterol and prevented further rise in plasma triglycerides after 10 weeks of treatment.

Once daily felodipine monotherapy in mild to moderate hypertension.

In a single-blind study conducted at our centres, 78 hypertensive patients were enrolled with 58 completing the study according to the protocol. Mean supine and standing blood pressures were significantly reduced after treatment with felodipine, reductions being 27/21 mmHg (p < 0.0001) and 25/19 mmHg (p < 0.0001) respectively. Of 46 patients given felodipine 5 mg, 44 (95.7%) achieved target blood pressure defined as a diastolic blood pressure of < 90 mmHg, while all 12 patients on felodipine 10 mg did so. The 2 patients who did not achieve target pressure at the final visit did so on previous visits. There were no differences in pre and post-treatment laboratory variables. Treatment was discontinued in 6 patients because of headaches. No adverse events of clinical significance were reported in the 58 patients who completed the study. In conclusion, we found felodipine given once daily to be effective in the treatment of mild to moderate hypertension.

Dose requirement and effect of nicardipine on lipid profile in mild to moderate essential hypertensives.

Twenty eight patients who satisfied the entry criteria and had completed an initial 2 weeks treatment with placebo were titrated fortnightly with doses of Nicardipine ranging from 30 mg to 90 mg daily in two or three divided doses. Nicardipine treatment significantly reduced blood pressures both in the supine and standing positions (p < 0.0004) when compared with placebo treatment. Heart rates however did not change significantly. Forty six percent (13/28) of patients on 20 mg twice daily, 25% (7/28) on 10 mg three times daily, 18% (5/28) of patients on 20 mg three times daily and 11% (3/28) on 30 mg three times daily achieved supine diastolic blood pressures < 90 mm Hg. Nicardipine treatment at 16 weeks and at 24 weeks did not significantly alter the lipid profile when compared to the end of placebo treatment period. No other biochemical abnormalities were reported during the study period. Except for 2 cases of mild pedal oedema and 2 cases of transient headaches, no serious side-effects were encountered.