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Biomedical subjects

M Chopra

Publications and source records attributed to M Chopra.

At least 37 records · Page 2Linked to original sources
PubMed2000

Influence of increased fruit and vegetable intake on plasma and lipoprotein carotenoids and LDL oxidation in smokers and nonsmokers.

BACKGROUND: Epidemiological studies suggest a cardioprotective role for carotenoid-rich foods. Smokers have a high risk of cardiovascular disease and low dietary intake and plasma concentrations of carotenoids. The aim of this study was to determine the carotenoid response of smokers and nonsmokers to increased intake of 300-400 g of vegetables and its effect on LDL oxidation. METHODS: After a depletion period of 8 days, 34 healthy females (18 nonsmokers, 16 smokers) were supplemented with beta-carotene- and lutein-rich (green) and lycopene-rich (red) vegetable foods, each for 7 days. RESULTS: Baseline concentrations (mean +/- SD) of plasma beta-carotene (0.203+/-0.28 micromol/L vs. 0.412+/-0.34 micromol/L; P <0.005) and lutein (0.180 +/-0.10 vs. 0.242+/-0.11 micromol/L; P<0.05) but not lycopene (0.296+/-0.10 vs. 0.319+/-0.33 micromol/L) were significantly lower in smokers compared with nonsmokers. After supplementation, the change (supplementation minus depletion) in plasma beta-carotene (0.152+/- 0.43 vs. 0.363+/-0.29 micromol/L in smokers vs. nonsmokers; P = 0.002) and LDL lutein (0.015+/-0.03 vs. 0.029+/-0.03 micromol/mmol cholesterol; P = 0.01) was significantly lower in smokers than nonsmokers. Green-vegetable supplementation had no effect on the resistance of LDL to oxidation (lag-phase) in either group. After red-vegetable supplementation, plasma and LDL lycopene concentrations were increased in both groups, but only nonsmokers showed a significant increase in the lag-phase (44.9+/-9.5 min at baseline, 41.4+/-6.5 min after depletion, and 49.0+/-8.9 min after supplementation; P<0.01) compared with depletion. CONCLUSIONS: In this short-term intervention study, a dietary intake of >40 mg/day of lycopene by a group of nonsmoking individuals significantly reduced the susceptibility of LDL to oxidation, whereas an equivalent increase in lycopene by a group of smokers showed no such effect.

Adult↗
PubMed1999

Antioxidants and lipoprotein metabolism.

Lipoprotein metabolism plays a significant role in the pathogenesis of atherosclerosis and risk of vascular disease. Elevated levels of LDL and low levels of HDL are linked to the risk of cardiovascular disease. It is now widely accepted that oxidative modification of LDL affects the metabolism of lipoproteins, leading to their increased accumulation in arterial intima. The present paper will examine some of the accumulating evidence from studies showing relationships between dietary intake of antioxidant nutrients, i.e. vitamins E and C, the carotenoids and the flavonoids, and their influence on lipoprotein metabolism. In particular, the present paper will review the available literature on the affect of antioxidant supplementation on lipoprotein oxidation, and hence metabolism of LDL in human subjects.

Antioxidants↗
PubMed1998

A mutation affecting dihydropyridine-sensitive current levels and activation kinetics in Drosophila muscle and mammalian heart calcium channels.

The Dmca1D gene encodes a Drosophila calcium channel alpha1 subunit. We describe the first functional characterization of a mutation in this gene. This alpha1 subunit mediates the dihydropyridine-sensitive calcium channel current in larval muscle but does not contribute to the amiloride-sensitive current in that tissue. A mutation, which changes a highly conserved Cys to Tyr in transmembrane domain IS1, identifies a residue important for channel function not only in Drosophila muscle but also in mammalian cardiac channels. In both cases, mutations in this Cys residue slow channel activation and reduce expressed currents. Amino acid substitutions at this Cys position in the cardiac alpha1 subunit show that the size of the side chain, rather than its ability to form disulfide bonds, affects channel activation.

Amiloride↗
PubMed1997

Effect of increased fruit and vegetable intake on the susceptibility of lipoprotein to oxidation in smokers.

OBJECTIVE: To evaluate the effect of an increased dietary intake of fruit and vegetables on susceptibility of LDL to oxidation in smokers and nonsmokers. DESIGN: A descriptive and prospective study. SETTING: Joseph Fourier University, Grenoble. SUBJECTS: Volunteers were age and sex matched in the smoking and nonsmoking groups and were recruited by announcement. INTERVENTIONS: Increased intake of fruits and vegetables for two weeks providing 30 mg/day of carotenoids. MAIN OUTCOME MEASURES: Circulating levels of beta-carotene, lutein, lycopene, alpha-tocopherol; susceptibility of LDL to oxidation. Cu-Zn superoxide dismutase (Cu-Zn SOD), and Se glutathione peroxidase (Se-GSH-Px) activities and reduced (GSH) and oxidized (GSSG) glutathione. RESULTS: At entry (week 0: W0) smokers exhibited a lower plasma carotene level but the plasma parameters of oxidative stress and LDL oxidizability were not different from nonsmokers. After two weeks of increased intake of fruits and vegetables the circulating levels of carotenoids increased in smokers 23% and 11% in nonsmokers. At the same time the resistance of LDL to oxidation increased by 14% in smokers (P < or = 0.05) and by 28% in nonsmokers (P < or = 0.025). The mean whole blood GSH level was higher in smokers at entry but returned to a concentration similar to nonsmokers at the end of the study. CONCLUSION: This pilot study indicates that an increased, carotenoid rich food intake through its inhibitory effect on the susceptibility of LDL to oxidation may be an interesting approach to reduce the risk of atherosclerosis both in smokers and nonsmokers.

Adult↗
PubMed1997

Epidemic shigella dysentery in children in northern KwaZulu-Natal.

OBJECTIVES: To describe the epidemiology, clinical features, management and outcome of children with Shigella dysenteriae type I infection admitted to a rural district hospital. DESIGN: Prospective cohort study. SETTING: Hlabisa Hospital, KwaZulu-Natal. SUBJECTS: Children aged under 12 years admitted with a history of bloody mucoid diarrhoea between February and December 1995. MAIN OUTCOME MEASURES: Number of admissions, age, sex, clinical features, complications and outcome. RESULTS: Between February and December 1995, 158 cases of bloody diarrhoea were admitted, compared with 6 the previous year. Shigella dysenteriae type I, resistant to ampicillin, tetracycline, chloramphenicol, trimethoprim and sulphamethoxazole, but susceptible to nalidixic acid and ceftriaxone, was isolated. The mean age of patients was 30 months. Patients typically presented with frequent bloody mucoid diarrhoea, fever, abdominal pain and dehydration. One hundred and sixteen (73%) recovered, 17 (11%) were transferred for tertiary care, 4 (3%) absconded, and 21 died (case fatality rate = 13%; 95% confidence interval (CI) 8-20). Seventeen (11%) developed haemolytic uraemic syndrome and 4 (3%) a protein-losing enteropathy. The malnourished (adjusted relative risk (RR) 3.3, 95% CI 1.6-7.1; P < 0.01) and those aged less than 2 years (adjusted RR 4.2; 95% CI 1.0-17.2; P = 0.05) were more likely to die. Dysentery deaths accounted for 19% of total paediatric hospital mortality. CONCLUSION: A serious epidemic of shigella dysentery has established itself and is having a significant impact in this area. The virulence and drug resistance of the organism has resulted in high levels of morbidity and mortality. Broad public health measures will be needed to contain the epidemic. Further community-based surveillance is urgently needed, as is research to determine modes and risk factors for transmission.

Anti-Bacterial Agents↗
PubMed1997

Paediatric burns in a rural South African district hospital.

OBJECTIVES: To describe the epidemiology, clinical features, management and outcome of children with burns admitted to a rural district hospital. DESIGN: A retrospective analysis of the case notes of consecutive cases of paediatric burns. SETTING: Hlabisa Hospital, KwaZulu-Natal-a 450-bed rural district hospital serving approximately 200,000 people. SUBJECTS: All cases of paediatric burns (age < 12 years) admitted to Hlabisa Hospital in 1994. MAIN OUTCOME MEASURES: Number of admissions, month of admission, age, sex, time to presentation, site of burn, complications, number of surgical procedures, adherence to management protocol and outcome. RESULTS: One hundred and forty-nine children presented to the outpatient department in 1994 and 88 (59%) were admitted. The median age of those admitted was 36 months with 66 (75%) aged less than 5 years; 42 (48%) were boys. Thirty-nine children (44%) were admitted during the four winter months of May to August. The average interval from the time of the burn to presentation at hospital was 42 hours (range 1-120). Sixty-eight burns (77%) were due to hot fluid or food burning the legs, trunk or arms. There was a high level of morbidity. Nineteen (22%) children developed wound infections, 5 (6%) developed contractures and 20 (23%) required a total of 32 surgical procedures. There was 1 death. Burns were responsible for more paediatric patient days spent in hospital than any condition other than malnutrition, and a longer length of stay was associated with delay in presentation. Children presenting within 24 hours of the burn had a mean length of stay of 12.8 days, compared with 25.2 days (P = 0.03) for children presenting 24 hours or more after the burn. Twenty of the 22 children who stayed for longer than 3 weeks or who required transfer were judged to have been managed inadequately in at least one respect compared with 3 of 48 who were discharged within 2 weeks or not transferred (P < 0.001). CONCLUSION: This study shows that paediatric burns are an important cause of morbidity and contribute significantly to inpatient stay in this rural setting. The lengthy delay from time of burn to presentation at hospital is of serious concern and our results show that this delay is associated with increased hospital stay. As most burns were due to spillage of hot fluids or food there seems to be significant potential for preventive interventions. Community-based studies would help to estimate the true incidence of burns and would contribute to an understanding of the reasons for delay in presentation. The information gathered is being used to inform the development of a burns prevention programme.

Burns↗
PubMed1997

Growth monitoring--is it a task worth doing in South Africa?

Childhood undernutrition is a serious public health problem in South Africa. Growth monitoring (GM) is a central tool in attempts to prevent and detect undernutrition. Despite its widespread adoption by international and national agencies, there has been very little evidence which shows that it has made an impact in reducing undernutrition. An important problem has been the conceptual confusion as to the exact role of GM. This article reviews the international evidence for the effectiveness of GM when used in various roles and proposes some of the factors necessary for GM to be successful in South Africa.

Child↗
PubMed1997

Epidemiology of obsessive-compulsive disorder: a world view.

The worldwide prevalence of obsessive-compulsive disorder (OCD) is approximately 2% of the general population. Symptoms of OCD include fear of contamination by dirt or germs; constant checking; repetitive, intrusive thoughts of a somatic, aggressive, or sexual nature; extreme slowness; and an inordinate concern with orderliness and symmetry. Differential diagnosis is sometimes complicated by the overlap between OCD and obsessive-compulsive personality disorder (OCPD). The most common complication of OCD is depression. However, while both serotonergic and nonserotonergic antidepressants are effective in treating patients with depression, only serotonergic medications are effective in treating OCD patients. Because OCD patients often attempt to conceal their symptoms, it is incumbent on clinicians to screen for OCD in every mental status examination, since appropriate treatment can often result in improved quality of life.

Adult↗
PubMed1995

Cloning and functional analysis of TipE, a novel membrane protein that enhances Drosophila para sodium channel function.

Voltage-dependent sodium channels are involved in the initiation and propagation of action potentials in many excitable cells. Here we report that tipE, a gene defined by a temperature-sensitive paralytic mutation in Drosophila, encodes a novel integral membrane protein that dramatically stimulates functional expression in Xenopus oocytes of the Drosophila sodium channel alpha subunit encoded by the paralytic (para) locus. Using a heat shock promoter to control tipE+ gene expression in transgenic flies, we demonstrate that tipE+ gene expression is required during pupal development to rescue adult paralysis. In addition, we demonstrate a role for the tipE gene product in adults.

Amino Acid Sequence↗
PubMed1995

Nitric oxide donors induce extrusion of cyclic GMP from isolated human blood platelets by a mechanism which may be modulated by prostaglandins.

In the presence of 3-isobutyl-methylxanthine (IBMX), induction of cyclic 3',5'-guanosine monophosphate (GMP) production in human washed platelets (HWP) by nitric oxide donors (NOD) is followed by its accumulation in the surrounding medium in a time- and concentration-dependent manner. Thirty minutes incubation of HWP with 3-morpholino-sydonimine (SIN-1, 10 microM) at 37 degrees C resulted in a 4.6-fold increase of cyclic GMP in platelets, whereas in the extracellular medium the increase was 17.6-fold. Similar results were obtained when other NOD such as S-nitroso-N-acetylpenicyllamine (SNAP) and 3-(2-methoxy-5-chlorophenyl)oxatriazol-5-imine (GEA 3184) and the selective phosphodiesterase inhibitor, zaprinast (M&B 22948, 10 microM), were used. Probenecid (1-300 microM), an inhibitor of organic anion transport, or ouabain (1-300 microM), an inhibitor of Na+/K+ adenine triphosphate (ATP)-ase had no effect on cyclic GMP production or extrusion after stimulation with SIN-1. Significantly prostaglandin A1 (PGA1) and prostaglandin D2 (PGD2) inhibited the efflux of cyclic GMP from platelets induced by SNAP (10 microM) in a concentration-dependent fashion, with an IC50 of 63 +/- 16 and 143 +/- 17 microM, respectively. These studies suggest that the extrusion of cyclic GMP from human platelets after activation of soluble guanylate cyclase by NOD may contribute to the control of cyclic GMP levels in platelets with potential physiological and therapeutic consequences.

1-Methyl-3-isobutylxanthine↗