Sulphydryl Content Research Articles

Effect of Aegle marmelos on biotransformation enzyme systems and protection against free-radical-mediated damage in mice.

The effect of hydroalcoholic (80% ethanol, 20% water) extract of leaves of Aegle marmelos was examined on carcinogen-metabolizing phase-I and phase-II enzymes, antioxidant enzymes, glutathione content, lactate dehydrogenase and lipid peroxidation, using two doses of dried extract (50 and 100 mg kg(-1) daily for 14 days), in the liver of mice. The modulatory effect of the extract was also examined on extrahepatic organs (lung, kidney and fore-stomach) for effects on the activity of glutathione S-transferase, DT-diaphorase, superoxide dismutase and catalase. Extract treatment significantly increased the basal levels of acid-soluble sulphydryl (-SH) content, cytochrome P450, NADPH-cytochrome P450 reductase, cytochrome b5, NADH-cytochrome b5 reductase, glutathione S-transferase, DT-diaphorase, superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase in the liver. Aegle acted as a bifunctional inducer since it induced both phase-I and phase-II enzyme systems. Both doses significantly decreased the activity of lactate dehydrogenase and formation of malondialdehyde in liver, suggesting a role in cytoprotection as well as protection against pro-oxidant-induced membrane damage. Butylated hydroxyanisole (positive control) induced almost all the antioxidative parameters measured in this study. The extract was effective in inducing glutathione S-transferase, DT-diaphorase, superoxide dismutase and catalase in lung, glutathione S-transferase, DT-diaphorase and superoxide dismutase in fore-stomach, and DT-diaphorase and superoxide dismutase in lung. These significant changes in the levels of drug-metabolizing enzymes and antioxidative profiles are strongly indicative of the chemopreventive potential of this plant, especially against chemical carcinogenesis.

Heat damage evaluation in ultra-high pressure homogenized milk

The evaluation of heat damage in ultra-high pressure homogenized (UHPH)-treated samples has been studied by analyzing different thermal indicators such as compounds that absorb at 340 nm, hydroxymethylfurfural, free sulphydryl content, furosine, lactulose and whey protein denaturation. Milk was treated at 200 and 300 MPa with inlet temperature of 30 and 40 °C and was compared to high-pasteurized milk (PA; 90 °C, 15 s) and to commercial UHT, in bottle-sterilized and pasteurized milks. UHPH samples were differentiated from PA milk, basically by the determination of absorbance at 340 nm and β-Lactoglobulin denaturation. Both parameters indicated a reduced thermal effect in UHPH samples over PA milk. Comparison of UHPH samples with UHT and sterilized milks showed an increase of all heating indicators when severe heat process was applied. Overall, in spite of the increase of temperature during UHPH treatments, heat damage was lower compared to PA milk, suggesting the potential of this technology as an alternative to pasteurization.

Effects of konjac glucomannan on physicochemical properties of myofibrillar protein and surimi gels from grass carp (Ctenopharyngodon idella)

Abstract The cryoprotective effect of konjac glucomannan (KGM) on myofibrillar protein from grass carp ( Ctenopharyngodon idella ) during frozen storage at −18 °C and the influence of five levels of KGM (0%, 0.5%, 1%, 1.5%, and 2%) on texture properties, water-holding capacity, and whiteness of grass carp surimi gels were investigated. KGM as a novel cryoprotectant could significantly mitigate the decrease in salt extractable protein (SEP), Ca 2+ -ATPase activity, and total sulphydryl and active sulphydryl contents of myofibrillar protein during frozen storage. KGM at the level of 1% showed the same good cryoprotective effect as a conventional cryoprotectant (10% sucrose–sorbitol, 1:1, w/w). As the levels of KGM increased, breaking force and deformation of grass carp surimi gels increased significantly. Water-holding properties of the surimi gels are improved with the increasing addition of KGM, but the whiteness decreased and the colour became darker. The optimum addition level of KGM was suggested to be 1%.

Oxidative stress and intracellular pH in the young and old erythrocytes of rat

The effects of oxidative stress (OS) on the rat erythrocytes (RBCs) that were fractionated on the percoll/BSA gradient into young and old cells were studied to find out if the altered Na+/H+ and Cl⁻/ HCO3⁻ antiporters and in turn the intracellular pH (pHi) could act as one of the promoters of cell death. Old cells were more spherical with lesser surface area, more fragile osmotically and had lesser protein sulphydryl content than the young cells. OS was induced in RBCs by 2,20-azobis (2-amidinopropane) dihydrochloride (AAPH). AAPH increased the superoxide dismutase (SOD) activity and MDA level and, the changes between the young and old. Interestingly, vitamin C was effective in reducing MDA in the old. Further, in the old a rapid Na+-dependent acidification in the presence of AAPH and a marginal acidosis in the presence of vitamin C were evident. Old RBCs exhibited higher acidosis and vitamin C was less effective in lowering the stress-induced acidosis compared to the young. Our studies suggest that increased acidosis followed by low intracellular pH could be one of the determinant factors for the disappearance of old RBCs from circulation, and perhaps of the young too under OS.

Physicochemical and functional properties of acidic and basic polypeptides of soy glycinin

The amino acid composition, some selected physicochemical and functional properties of acidic and basic polypeptides of soy glycinin were investigated and compared. Large amount of these polypeptides were obtained by DEAE-Sepharose fast flow column chromatography. Free sulphydryl contents, surface hydrophobicity, solubility and emulsifying activities (at different pH values) were evaluated. Different polypeptides had different patterns of amino acid composition, especially contents of acidic (and basic) and hydrophobic amino acids. The free sulphydryl contents (including total and exposed) and surface hydrophobicity considerably varied with the type of polypeptides. Compared with glycinin, isoelectric point (pI) of individual polypeptides shifted towards a more acidic pH. At a given pH value (e.g. above or below pI), the solubility and emulsifying ability index of these polypeptides were closely related to their relative contents of acidic (and basic) amino acids. The results indicated that glycinin polypeptides with different amino acid character have different physicochemical and functional properties, especially solubility and emulsifying ability.

Heat-induced modifications in the functional and structural properties of vicilin-rich protein isolate from kidney (Phaseolus vulgaris L.) bean

Abstract Heat-induced changes in the physico-chemical (and/or functional) and structural properties of protein isolate from kidney beans (KPI) were characterised. The extent of protein denaturation, free sulphydryl contents, surface hydrophobicity, as well as structural characteristics of the proteins were evaluated. Analyses of size-exclusion chromatography combined with laser scattering showed that the heating at 95 °C led to transformation of 7S-form vicilin to its 11S-form, and even higher molar mass (MW) oligomers or polymers. Moderate heating (for 15–30 min) significantly improved protein solubility, emulsifying and foaming activities (at neutral pH), whilst extensive heating (for 60–120 min) on the contrary decreased these properties. Spectral analyses of fluorescence and/or Raman spectroscopy showed that tertiary and secondary conformations of protein in KPI were remarkably affected to a varying extent by the heating. The results suggested a close relationship between functional properties of the vicilin from kidney bean and its conformational characteristics.

Desialylation of Plasma Proteins in Severe Dengue Infection: Possible Role of Oxidative Stress

Oxidative stress in dengue infection has been suggested. This study was carried out to explore the plasma protein oxidation and its sialic acid content in dengue infection. Thirty-two dengue hemorrhagic fever (DHF), 25 dengue shock syndrome (DSS), 29 dengue fever (DF), and 63 healthy controls were included in this study. The extent of carbonylation, sulphydryl content, and desialylation of plasma protein was estimated in acute phase sample. Significantly higher levels of protein carbonyls and lower levels of sialic acid and sulphydryl groups were found in DHF and DSS compared with DF using one-way analysis of variance. Regression analysis showed that desialylation is dependent on protein carbonyls in DHF/DSS. This study indicates that, in dengue infection, plasma proteins undergo increased levels of desialylation, which can be attributed to the oxidative stress. Future studies on sialylation status of endothelium and platelets can show light into the pathogenesis of the dengue infection.

PACKAGING AND STORAGE EFFECTS ON THE FUNCTIONAL PROPERTIES OF FROZEN VENISON

ABSTRACT The functional stability of vacuum‐ and nonvacuum‐packaged venison semimembranosus muscle was determined after 0, 1, 2, 3, 6 and 9 months of frozen storage. Vacuum‐packaged samples had higher emulsion stability, chroma, shear force values, cooked batter torsion stress, strain and tensile stretch, lower malondialdehyde (MDA) and lower hue angle compared with nonvacuum‐packaged samples. The two packaging methods did not vary in the other functional attributes of venison measured. Total protein solubility, cooked batter torsion strain and tensile strength increased in the first month of storage and then decreased thereafter. Sarcoplasmic protein solubility increased (P < 0.05) in the first 6 months and declined in the ninth month. Reactive sulphydryl contents (P < 0.1) and moisture loss in raw (P < 0.001) and in cooked venison (P < 0.01) increased with storage time and peaked at 3 months and declined thereafter. MDA increased during the first 2 months, then declined and increased again at 9 months (P < 0.001). The results of this study suggest that most of the changes in frozen venison manufacturing functionality took place within the first month of storage and this peak functionality was extended to 3 months when venison was vacuum‐packaged.PRACTICAL APPLICATIONSThe following are some of the practical applications of this research: (1) Frozen venison has better functional properties for manufacturing purposes compared with fresh unfrozen venison immediately postrigor. (2) This functionality tends to peak at 1 month of frozen storage, with longer storage up to 9 months having little or no further effect on the functionality. (3) The peak functionality can be extended to 3 months through vacuum packaging.

Functional and Biochemical Characterization of Proteins Remaining in Solution After Isoelectric Precipitation

ABSTRACT The resulting supernatant from the isoelectric precipitation of “sawdust” from Cape hake portioning and blue whiting muscle was concentrated by ultrafiltration and the retentate spray-dried. Two main peaks corresponding to molecular weights of 15 kDa and 65 kDa were detected in the supernatant from both raw materials; in the retentate the main proteins had approximately 18 kDa and 73 kDa, and some proteins with 59 kDa were detected in the permeate. The protein content was 74.0% and 70.0% for hake by-products and blue whiting, respectively. Dried proteins had relatively low emulsifying and foaming capacity but high foaming stability and were whitish in color. Hydrophobicity and sulphydryl content were similar to those from other protein sources.

Acid-induced gelation of natural actomyosin from Atlantic cod ( Gadus morhua) and burbot ( Lota lota)

The acid-induced gelation of natural actomyosin (NAM) from burbot ( Lota lota) and Atlantic cod ( Gardus morhua) added with d-gluconic acid- δ-lactone (GDL) during incubation at room temperature (22–23 °C) for 48 h was investigated. During acidification, pH values of both NAMs reached 4.6 within 48 h. Both NAMs underwent aggregation during acidification as evidenced by increases in turbidity and particle size, especially after 6 h of incubation. The decreases in Ca 2+-ATPase activity and salt solubility of both NAMs were observed during incubation. Decreases in total sulphydryl content with the concomitant increases in disulphide bond content of NAM from both species were also noticeable. Additionally, surface hydrophobicity of NAM increased, suggesting the conformational changes in NAM induced by acidification. The storage modulus ( G′) values increased with increasing incubation time and G′ development was greater in Atlantic cod NAM, compared with burbot NAM. Differential scanning calorimetry (DSC) revealed that T max and enthalpy of myosin peak shifted to the lower values and endothermic peak of actin completely disappeared. In general, gel development was more pronounced in Atlantic cod NAM, compared with the burbot counterpart. As visualised by transmission electron microscopy, network strands of aggregates from Atlantic cod were finer and more uniform than those of the burbot counterpart. Acid-induced gelation of NAM from both fish species therefore involved both denaturation and aggregation processes. However, gelation varied with fish species and had an impact on the resulting gels.

Thermal denaturation and gelation of vicilin-rich protein isolates from three Phaseolus legumes: A comparative study

The thermal denaturation and gelation properties of vicilin-rich protein isolates from red bean, red kidney bean and mung beans (further denoted as RPI, KPI and MPI) were investigated by differential scanning calorimetry (DSC) and dynamic oscillatory measurements. The relation between the properties of these proteins to their free sulphydryl (SH)/disulfide bond (SS) contents was also evaluated. DSC analyses showed that many DSC characteristics of major endothermic peak (corresponding to vicilin component), including its denaturation temperature ( T d), enthalpy changes (Δ H) and width at half-peak height (Δ T 1/2), significantly varied with the type of protein isolates. Furthermore, the heat-induced gelation, including onset of gelation and the development of mechanical moduli, was also dependent on the type of protein isolates. The thermal denaturation of these proteins was nearly unaffected by the presence of reducing agent dithiothreitol (DTT), while the presence of DTT weakened the gel formation. The T d of vicilin components and the mechanical moduli of corresponding formed gels were positively related to their SS contents. Additionally, the formed gels were thermo-irreversible, and heat pretreatment (carried out at temperatures higher than or close to the T d of these vicilins) could improve the gel network formation. These results confirm that vicilin-rich protein isolates from various legumes show different patterns of thermal denaturation and gelation, and these properties are to a great extent related to their SH and/or SS contents.

Purification and Characterization of High Molecular Mass and Low Molecular Mass Cystatin from Goat Brain

Cystatin are thiol proteinase inhibitors ubiquitously present in mammalian body and serve various important physiological functions. In the present study two cystatins were isolated from goat brain using alkaline treatment, ammonium sulphate fractionation, gel filtration and ion exchange chromatography. The high molecular mass cystatin of 70.8 kDa was named as HM-GBC (high molecular mass goat brain cystatin) and the low molecular mass cystatin of 12.72 kDa was named as LM-GBC (low molecular mass goat brain cystatin). The molecular mass determined by SDS-PAGE was found to be 70.8 and 12.88 kDa for HM-GBC and LM-GBC, respectively, however with gel filtration the masses were found to be 70.8 and 12.58 kDa. Both the cystatins were found to be stable in broad range of pH and temperature. HM-GBC was found to have 2% carbohydrate content while LM-GBC lacks any carbohydrate content. Both cystatins were found to be devoid of any sulphydryl content. Stoke's radii of 36 and 16 A, and diffusion coefficient of 6.189 x 10(-15) and 1.392 x 10(-14) cm(2)/s were calculated for HM-GBC and LM-GBC. K (i) values with papain were found to be 1.875 x 10(-8) and 3.125 x 10(-8) M for HM-GBC and LM-GBC, respectively. K (+1), K (-1) and half-life calculated along with K (i) values obtained showed that HM-GBC inhibited papain more specifically as compared to LM-GBC. The IC(50) values obtained for HM-GBC and LM-GBC also showed that HM-GBC binds more effectively to papain than LM-GBC. Ultraviolet and fluorescence spectra indicated that upon formation of papain-HM-GBC/LM-GBC complex there is significant conformational change after interaction in one or both the proteins of the complex.

Intermittent hypobaric hypoxia‐induced oxidative stress in rat erythrocytes: protective effects of vitamin E, vitamin C, and carnitine

This study was aimed at determining the effect of vitamin E, vitamin C, and carnitine on intermittent hypobaric-hypoxia-induced oxidative stress (OS) in erythrocytes. For this purpose, male Wistar rats of 4 months of age were orally supplemented with one of the antioxidants prior to exposure to altitudes of 5700 m or 6300 m. Hemoglobin (Hb) and OS indices such as osmotic fragility and hemolysis were measured together with lipid peroxidation (LPO) and protein oxidation. The increase in Hb was accompanied by increase in activities of antioxidant enzymes, superoxide dismutase (SOD), and catalase (CAT) during exposure to both the altitudes without any further elevation by supplements. The extent of reduction in osmotic fragility and hemolysis by vitamin E and carnitine was greater at 6300 m than at 5700 m. Increase in LPO products, for example, malondialdehyde (MDA) and lipofuscin-like autofluorescent substances (AFS) was noticeable at both the altitudes, and vitamin E and carnitine were effective in reducing LPO. While protein oxidation products such as carbonyl content (PrC) and advanced oxidation protein products (AOPP) increased at 6300 m, protein sulphydryl (P-SH) content decreased. P-SH levels were restored on supplementation of antioxidants. Hence, our results indicate that vitamin E, vitamin C, and carnitine may be beneficial in overcoming OS and hemolysis under situations such as intermittent hypobaric hypoxia (IHH) and hypobarotherapy wherein hypoxia is used to correct many pathological situations in humans. Further, this study suggests that supplementation of vitamin E, vitamin C, and L-carnitine alone and not in combination can be beneficial in attenuating the OS associated with IHH compared to the unsupplemented rats exposed to two different altitudes.

Chemopreventive effects of mustard (Brassica compestris) on chemically induced tumorigenesis in murine forestomach and uterine cervix

As there is a strong correlation between diet and cancer, the dietary constituents that inhibit mutagenesis and/or carcinogenesis are of paramount importance for the prevention of human cancer. In the present study, cancer chemopreventive potentials of different doses of mustard (Brassica compestris) seed mixed diets were evaluated against benzo(a)pyrene [B(a)P]-induced forestomach tumorigenesis and 3-methylcholantrene (MCA)-induced uterine cervix tumorigenesis. Results showed a significant inhibition of stomach tumour burden (tumours/ mouse) by mustard seeds. Tumour burden was 7.08 +/- 2.47 in the B(a)P-treated control group, whereas it was reduced to 1.36 +/- 1.12 (P<0.001) by the 2.5% dose and 1.18 +/- 0.87 (P<0.001) by the 5% dose of mustard seeds. The cervical carcinoma incidence, as compared to MCA-treated control group (73.33%), was reduced to nil (P<0.05) by the 5% diet of mustard seeds and to 13.33% (P<0.05) by the 7.5% diet of mustard seeds. The effect of the 2.5% and 5% mustard seed mixed diets was also examined on the antioxidant enzymes, glutathione content, lactate dehydrogenase (LDH) and lipid peroxidation in the liver of Swiss albino mice. The glutathione-S-transferase-specific activity was increased (P<0.05) by the 2.5% dose, whereas there was no significant change in the activity of DT-diaphorase. In antioxidant systems, significant elevation of the specific activities of superoxide dismutase and catalase was observed with both doses of mustard seeds (P<0.05). The level of reduced glutathione (GSH) measured as nonprotein sulphydryl content was elevated by the 2.5% dose of mustard seeds only (P<0.05). Lipid peroxidation measured as formation of thiobarbituric acid reactive substances production showed significant inhibition (P<0.05) by the 5% dose of mustard seed mixed diet. LDH activity was decreased significantly (P<0.05) by both the doses. The results strongly suggest the cancer chemopreventive potentials of mustard seeds and their ability to enhance the antioxidant defence system and in turn provide protection against the toxic effects of carcinogens. It is likely that the use of mustard seeds in the diet may contribute to reducing the risk of cancer incidence and burden in the human population.

Glutathione and free sulphydryl content of seminal plasma in healthy medical students during and after exam stress

It has been reported that there is a relationship between stress and infertility. The mechanisms of stress-related semen quality alterations have not been fully elucidated. In the present study, we investigated the effect of examination stress on seminal glutathione and free sulphydryl content and sperm quality. Semen samples were collected from 34 healthy volunteers who were students of medical school in the fourth semester just before (stress period) and 3 months after (non-stress period) their final examinations. Their psychological examination stress was measured by the State Trait Anxiety Inventory (STAI) questionnaire. After standard semen analysis, semen samples were centrifuged at 10 000g for 15 min. Glutathione and free sulphydryl concentration of seminal plasma were measured. During the period of examination stress, the glutathione and free sulphydryl content of seminal plasma and the motility index of spermatozoa were significantly lower, whereas the percentage of morphologically abnormal spermatozoa was higher, than during the non-stress period (P < 0.001, for all). An association between seminal plasma glutathione and motility index was observed at both periods (P < 0.05 and P < 0.01, respectively). This study demonstrated that glutathione and free sulphydryl levels in seminal plasma decreased in subjects undergoing examination stress. Furthermore, poor sperm quality may be due to loss of glutathione and free sulphydryl content of seminal plasma.

Ultra-fast freezing and low storage temperatures are not necessary to maintain the functional properties of manufacturing beef

The effects of freezing rates and subsequent storage temperatures on the functional properties of meat were assessed. In the first trial, 24 Semitendinosus muscles were allocated to four freezing treatments to determine the effect of freezing rate alone (no frozen storage) on the functional properties of thawed muscle proteins. In the second trial, the effect of freezing rate, storage temperature and time were determined: 24 semimembranosus muscles were assigned to 30 treatment combinations using an incomplete factorial design with two freezing rates × three storage temperatures × five storage times. All samples individually sealed in water impermeable bags were thawed in water at 10 °C and then analysed. The rate of freezing alone in both trials and for both muscles had no effect on protein solubility; sulphydryl content; surface hydrophobicity; emulsion activity index or meat colour. Slowly frozen s emimembranosus had more drip than fast frozen muscles. Semimembranosus muscle sarcoplasmic protein solubility increased and myofibrillar protein solubility decreased with storage temperature below −18 °C. Storage temperature did not affect the other attributes measured. Functional properties were mainly affected by storage time and the interaction between storage time and freezing rate. It is concluded that the current practice of blast freezing and storage at −18 to 20 °C is sufficient to maintain the quality of manufacturing beef.

Modulatory influence of Andrographis paniculata on mouse hepatic and extrahepatic carcinogen metabolizing enzymes and antioxidant status.

The effects of two doses (50 and 100 mg/kg body wt/day for 14 days) of an 80% hydroalcohol extract of Andrographis paniculata and butylated hydroxyanisole (BHA) were examined on drug metabolizing enzymes, antioxidant enzymes, glutathione content, lactate dehydrogenase (LDH) and lipid peroxidation in the liver of Swiss albino mice (6-8 weeks old). The effect of the extract and BHA were also examined on lung, kidney and forestomach for the activities of glutathione S-transferase (GST), DT-diaphorase (DTD), superoxide dismutase (SOD) and catalase. A significant increase in the levels of acid soluble sulphydryl (-SH) content, cytochrome P450, cytochrome P450 reductase, cytochrome b5 reductase, GST, DTD and SOD were observed at both dose levels of extract treatment while catalase, glutathione peroxidase and glutathione reductase (GR) showed significant increases only at the higher dose in the liver. Both Andrographis treated groups showed a significant decrease in activity of LDH and malondialdehyde (MDA) formation. BHA treated mice showed a significant increase in the levels of cytochrome b(5), GST, DTD, -SH content, GR and catalase in liver; while LDH and MDA levels were reduced significantly compared with their control values. In the lung, SOD, catalase and DTD, in the kidney catalase, DTD and GST, and in the forestomach SOD and DTD showed a significant increase at both dose levels of treatment. In BHA treated mice GST, DTD and catalase were significantly induced in the lung and along with these enzymes SOD was also induced in the kidney. In the case of the forestomach of BHA treated mice GST, DTD and SOD were enhanced significantly. These findings indicate the chemopreventive potential of Andrographis paniculata against chemotoxicity including carcinogenicity.

2-Halopropionic Acid-induced Cerebellar Granule Cell Necrosis in the Rat: In Vivo and In Vitro Studies

Daily oral administration of 2.3 mmol/kg l-2-chloropropionic acid ( l-2-CPA), dl-2-bromopropionic acid (2-BPA) or dl-2-iodopropionic acid (2-IPA) but not dl-2-fluoropropionic acid (2-FPA) produced cerebellar granule cell necrosis in the rat. Twenty four hours after three doses of l-2-CPA or two doses of 2-BPA, animals showed clinical signs of motor incoordination and reduced hindlimb function which was associated with marked cerebellar oedema and cerebellar granule cell necrosis. Biochemical analyses showed a marked increase in cerebellar water and Na + content, and a reduction in cerebellar glutamate and aspartate. 2-IPA at this dose was toxic, the animals not surviving a second dose, histopathology showed hepatic and renal necrosis with mild cerebellar granule cell necrosis. 2-FPA was not neurotoxic after four daily doses. A marked decrease in hepatic and cerebellar non-protein sulphydryl (NP-SH) content was observed 4 h after a single dose of 2.3 mmol/kg l-2-CPA, 2-BPA and 2-IPA but not 2-FPA. Daily doses of 2-BPA for 3 days produced a sustained 50% depletion in cerebellar NP-SH. In vitro, l-2-CPA, 2-BPA and 2-IPA produced glutathione (GSH) depletion in the presence of rat liver cytosol, while 2-FPA did not. Depletion of GSH in the presence of cerebellar cytosol was only observed with 2-IPA. Studies using primary cultures of rat cerebellar granule cells, showed that all analogues produced a concentration dependent loss of cell viability. Mean EC 50 values for 2-FPA, l-2-CPA, 2-BPA and 2-IPA toxicity were 1.7, >10, 0.5 and 0.3 mM, respectively, for 24 h continuous exposure. MK-801 and Vitamin E afforded protection against l-2-CPA-induced cytotoxicity but not against the other analogues. In summary, in addition to l-2-CPA, both 2-BPA and 2-IPA produce cerebellar granule cell necrosis in the rat. Depletion of GSH in the cerebellum may be contributory factor in the cascade of events leading to neurotoxicity.

Lipid peroxidation, osmotic fragility and antioxidant status in children with acute post-streptococcal glomerulonephritis

Plasma and erythrocyte samples from acute post-streptococcal glomerulonephritis (APSGN) children and control children were enrolled in this study. Lipid peroxidation (LPO), measured in terms of thiobarbituric acid-reactive substances (TBARS) was found to be significantly increased in plasma and RBCs of APSGN children ( P<0.05) than in control children. Osmotic fragility of erythrocytes was examined. RBCs of APSGN patients were found to be osmotically more sensitive towards hypotonic saline (50% hemolysis at 7 g/l saline) when compared to control RBCs (50% hemolysis at 4 g/l saline). The activities of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione S-transferase (GST) were significantly lowered ( P<0.05) in APSGN RBCs when compared to control RBCs. Plasma ascorbic acid, reduced glutathione (GSH), RBC ascorbic acid, GSH and RBC total sulphydryl content (TSH) were significantly depleted in APSGN children relative to controls. The susceptibility of RBCs of APSGN children to lipid peroxidation was confirmed in this study.

Alterations of antioxidant enzymes and oxidative stress markers in aging.

In accordance with the present state of scientific knowledge, the excessive production of free radicals in the organism, and the imbalance between the concentrations of these and the antioxidant defenses may be related to processes such as aging and several diseases. The aging process has been described by various theories. In particular, the free radical theory of aging has received widespread attention which proposes that deleterious actions of free radicals are responsible for the functional deterioration associated with aging. Although, the relationship between lipid peroxidation and aging have been investigated extensively, the studies have produced conflicting results. To investigate the correlation between the oxidative stress and aging, we have determined the levels of lipid peroxidation expressed as thiobarbituric acid reactive substances (TBARS; MDA) and conjugated dien; oxidative protein damage as indicated by carbonyl content and activities of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) in a sample of 100 healthy men and women ranging in age from 20 to 70years. In addition, vitamin E, C levels, reduced glutathione and sulphydryl content were determined. The oxidation end product of nitric oxide (nitrate) was also studied to investigate any role of nitrogen radicals in aging. Our data show that there is an age related increase in lipid peroxidation expressed as MDA and oxidative protein damage as indicated by carbonyl content. Aging is not linked to a decline in antioxidant enzymes except GPx. Our data suggests that the level of oxidative stress increase cannot entirely be attributed to a decrease in the activities of antioxidant defense system and probably various factors may contribute to this process.