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1.  Prevention of isoproterenol-induced cardiac hypertrophy by eugenol, an antioxidant 
Recent reports on the involvement of calcineurin in cardiac hypertrophy and its susceptibility to free radicals, prompted us to examine possible beneficial effects of dietary antioxidants in this regard. In continuation of initialin vitro studies revealing eugenol to be a potent calcineurin inhibitor, we investigated its ability to reverse isoproterenol-induced cardiac hypertrophy in rats. Intraperitoneal administration of isoproterenol (1 mg/kg body wt/day for 10 days) induced cardiac hypertrophy with increased heart weight and enhanced apoptosis of myocytes concomitant with accumulation of reactive oxygen species, decreased glutathione contents, increased activities of calcineurin and protein kinase C in ventricular tissue. Administering eugenol for 3 days (1 mg/kg body wt/twice a day), followed by combined administration of isoproterenol and eugenol resulted in significant reversal of cardiac hypertrophy and restoration of above changes. These results suggest that eugenol, a natural antioxidant of dietary origin, may offer potential benefits in the management of cardiac hypertrophy.
PMCID: PMC3453984  PMID: 23105625
Antioxidants; Calcineurin activity; Cardiac hypertrophy; Eugenol; ROS; Isoproterenol
2.  Biological effects of power frequency magnetic fields: Neurochemical and toxicological changes in developing chick embryos 
There are several reports that indicate a linkage between exposure to power frequency (50 – 60 Hz) magnetic fields with abnormalities in the early embryonic development of the chicken. The present study was designed to understand whether power frequency electromagnetic fields could act as an environmental insult and invoke any neurochemical or toxicological changes in developing chick embryo model.
Fertilized chicken eggs were subjected to continuous exposure to magnetic fields (50 Hz) of varying intensities (5, 50 or 100 μT) for a period of up to 15 days. The embryos were taken out of the eggs on day 5, day 10 and day 15. Neurochemical (norepinephrine and 5-hydroxytryptamine) and amino acid (tyrosine, glutamine and tryptophan) contents were measured, along with an assay of the enzyme glutamine synthetase in the brain. Preliminary toxicological investigations were carried out based on aminotransferases (AST and ALT) and lactate dehydrogenase activities in the whole embryo as well as in the liver.
The study revealed that there was a significant increase (p < 0.01 and p < 0.001) in the level of norepinephrine accompanied by a significant decrease (p < 0.01 and p < 0.001) in the tyrosine content in the brain on day 15 following exposure to 5, 50 and 100 μT magnetic fields. There was a significant increase (p < 0.001) in glutamine synthetase activity resulting in the significantly enhanced (p < 0.001) level of glutamine in the brain on day 15 (for 100 μT only). The possible mechanisms for these alterations are discussed. Further, magnetic fields had no effect on the levels of tryptophan and 5-hydroxytryptamine in the brain. Similarly, there was no effect on the activity of either aminotransferases or lactate dehydrogenase in the whole embryo or liver due to magnetic field exposure.
Based on these studies we conclude that magnetic field-induced changes in norepinephrine levels might help explain alterations in the circadian rhythm, observed during magnetic field stress. Also, the enhanced level of glutamine can act as a contributing factor for developmental abnormalities.
PMCID: PMC375542  PMID: 14754460
3.  Calcineurin activity as an indicator of oxidative stress in normal islet cells and insulinoma cells 
A comparative study was conducted to evaluate calcineurin activity in normal pancreatic beta cells and insulinoma cells in relation to their oxidative state. In comparison to normal islets, insulinoma cells had enhanced oxidative stress as evidenced by increased content of thiobarbituric acid reactive substances. In addition, diminished activity of calcineurin in insulinoma cells was concomitant with decreased content of reduced glutathione and glutathione peroxidase activity signifying diminished antioxidant status in these cells. Culturing insulinoma cells in presence of the calcineurin inhibitor cyclosporin A resulted in further decrease of calcineurin activity with restoration of glutathione peroxidase but without restoration of reduced glutathione levels. These results indicate that an estimate of oxidative stress in pancreatic islets and insulinoma cells can be obtained by assaying calcineurin activity.
PMCID: PMC3453735  PMID: 23105363
Calcineurin; Cyclosporin; Glutathione peroxidase; Insulin; Insulinoma; Oxidative stress
4.  Early oxidative change in low density lipoproteins during progressive chronic renal failure 
Modified low density lipoproteins (LDL), including their oxidized forms, have been widely implicated in the etiology of atherosclerosis and concomitant cardiovascular disease (CVD) in chronic renal failure (CRF). The nature of events that lead to oxidative changes in LDL proteins are not clearly understood. Thus, patients suffering from CRF were grouped into mild, moderate and severe categories based on their blood urea and serum creatinine levels. Progression of CRF was accompanied not only with gradual increase in serum malondialdehyde (MDA) but also parallel increase in conjugated diene and MDA levels in LDL fractions separated from serum. Serum superoxide dismutase (SOD) activity was concurrently found to decrease, along with a decrease in high-density lipoprotein (HDL) cholesterol, during the progression of CRF. Gradual increase in the appearance of LDL oxidation products seems to accompany progressive manifestation of CRF. The results presented suggest that determination of serum MDA and SOD levels may enhance the diagnostic significance of the study of lipid profile in determining the risk for cardio vascular disease in CRF.
PMCID: PMC3453591  PMID: 23105216
Chronic renal failure; Malondialdehyde; Superoxide dismutase; Low density lipoproteins; Lipid peroxidation
5.  Cell Wall Composition of Neurospora crassa Under Conditions of Copper Toxicity 
The mycelia of Neurospora crassa grown in the presence of high concentrations of copper were blue in color, but only on a medium containing inorganic nitrate and phosphate as the nitrogen and phosphate sources, respectively. The cell wall isolate of the blue mycelia contained large amounts (12%) of copper and higher amounts of chitosan, phosphate, and amino groups, with a 42% decrease in the chitin content. Although all the glucosamine of the cell wall of control cultures could be released within 6 h of hydrolysis with acid, that of the blue mycelium required prolonged hydrolysis for 24 h. On removal of copper, the cell wall of the blue mycelium could quantitatively bind again to copper as well as to zinc. Although zinc binding was fivefold greater, copper alone was preferentially bound from a mixture of the two metal ions. Supplementation of iron along with copper in the culture medium resulted in the disappearance of the blue color of the mycelium and restoration of normal growth and composition of the cell wall, probably by limiting the uptake of copper from the medium. The possibility of the cell wall being a specific site of lesion in copper toxicity in the mold is discussed.
PMCID: PMC239320  PMID: 16346385

Results 1-5 (5)