Effect of amphotericin B on the enzyme system of Candida albicans]

The mechanism of amphotericin B action was studied with the aid of cytochemical methods providing determination of the activity of the 4 main enzymes characterizing the cell energetics, i. e. succinate dehydrogenase, lactate dehydrogenase, alcohol dehydrogenase and glucose-6-phosphate dehydrogenase inside the cell. With an increase in the concentration of amphotericin B in the medium the activity of all the 4 enzymes decreased, the percentage of the inactive cells being regularly increased. Changes in the fermentative activity of C. albicans as dependent on the incubation time with the antibiotic were studied. Only the respiration activity decreased in 2 hours. As a result of a 4-hour exposure to the polyen in the cells of C. albicans the activity of the lactic acid fermentation, respiration through succinate dehydrogenase and activity of the pentose shunt decreased 1.5--2 times. In 24 hours of incubation the activity of the above decreased 80--90 per cent as compared to the activity of the initial culture.     

Pathogenicity of various species of Candida in an experimental murine system

The systemic infection induced by Candida albicans, Candida krusei and Candida viswanathii was studied in an experimental murine system. Candida albicans is able to kill outbred CD1 mice within a few days and at a very low concentration; C. krusei is not pathogenic not even when inoculated at a higher concentration; C. viswanathii is able to kill animals only a a higher concentration. The different resistances do not seem to be under genic control, in as much as the different strains of mice used (hybrid CD2F1 and B6C3HF1, inbred Balb/c) show the same degree of resistance as the CD1 mice to the three species of Candida. The colony forming units (CFU) in the kidneys of CD1 mice inoculated intravenously with 10(5) cells of the three species of Candida, collected at various intervals showed a good correlation with the median survival times: a rapid moltiplication of the C. albicans is evident in the kidneys of the animals 24 hours after the inoculation, while the C. krusei and the C. viswanathii do not moltiply.     

Effect of chronic ethanol administration on testicular antioxidant system and steroidogenic enzyme activity in rats

In order to find out the effect of chronic ethanol administration on testicular antioxidant system and steroidogenic enzyme activity, male rats fed with ethanol 1.6g/kg body weight per day for four weeks were studied. Besides a drastic reduction in body and testis weight, there was decrease in ascorbic acid, reduced glutathione and activities of superoxide dismutase, catalase, glutathione reductase and glutathione peroxidase in the testicular tissue of the treated animals. Simultaneously, there was increase in lipid peroxidation and glutathione S-transferase activity. Activities of 3 beta-hydroxy steroid dehydrogenase and 17 beta-hydroxy steroid dehydrogenase were also found decreased in the treated animals. The results indicate that chronic ethanol administration resulted in increase in oxidative stress and decrease in the activities of steroidogenic enzymes in the rat testes.     

Effect of cigarette smoke on placental antioxidant enzyme expression

Cigarette smoking is associated with systemic oxidative stress leading to an upregulation of antioxidant systems [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and heme oxygenase (HO)] in some tissues, but the response in the human placenta is unknown. The aim of this study was to determine the effect of cigarette smoke exposure on placental antioxidant expression in vivo, as well as the effect on antioxidant expression in the human trophoblast choriocarcinoma (HTR)-8SVNeo cell line. In the in vivo experiment, normal-term placentas were obtained following elective caesarean section. The chorionic villi (CV), anchoring villi (AV), and basal plate (BP) were dissected, and Western blot analysis was carried out for HO-1, HO-2, SOD, CAT, and GPx. In vitro experiment, a cigarette smoke extract (CSE) was prepared by bubbling the smoke form three cigarettes through 15 ml of RPMI. This 100% CSE was syringe filtered and diluted to 0.1, 0.5, 1, 2, 5, and 10% concentrations. HTR-8SVNeo cells were cultured with the CSE for 48 h. The cells were harvested, protein was extracted, and run on SDS-PAGE gels, and Western blot analysis was carried out for HO-1, HO-2, SOD, and CAT. Immunofluorescence for HTR-8SVNeo cells HO-1 was carried out following increasing concentrations of CSE. In the in vivo experiment, HO-1 and HO-2 expression was increased in the BP of placentas from smokers compared with nonsmokers. CAT, GPx, and SOD levels in all placental regions, as well as HO-1 and HO-2 expression in the AV and CV were unchanged. In the in vitro experiment, The 5%, 10%, and 20% dilutions were toxic to the cells. The 0.1% CSE solution did not significantly alter HO-1 expression. Treatment with the 0.5%, 1% and 2% CSE solutions resulted in a dose-dependent increase in HO-1 expression. None of the CSE treatments resulted in a significant alteration in HO-2, SOD, GPx, or CAT expression. HO-1 immunoflourescence confirmed the HO-1 expression studies. Cigarette smoke exposure increases HO-1 and HO-2 expression in the placental basal plate and increases HO-1 expression in the HTR-8SVNeo cell line. Increased HO-1 and HO-2 protein expression may increase the production of the antioxidants biliverdin and bilirubin, which are products of heme metabolism. This could function to reduce the oxidative load that is released into the maternal plasma from the preeclamptic placenta and may contribute to the observed decreased incidence of preeclampsia in smokers.     

镉处理对油菜生长和抗氧化酶系统的影响

通过盆栽实验研究了Cd处理对油菜生长和抗氧化酶系统的影响.结果表明,油菜整株鲜重、叶鲜重随Cd胁迫呈显著降低趋势.逐步回归表明,叶鲜重下降导致油菜整株鲜重下降.油菜叶细胞膜渗透性和MDA随Cd胁迫增大而增加.Cd处理浓度为20 mg·kg^-1时,叶细胞膜渗透性和MDA分别增加29.68％和15.19％,叶细胞膜渗透性和 MDA呈显著正相关,相关系数为0.823^*.Cd处理浓度为5 mg·kg^-1时,叶绿素a、b和a+b含量达到峰值,分别比对照高23.97%、33.63%和26.45%;Cd胁迫对类胡萝卜素含量无显著影响.几种色素对Cd敏感顺序为：叶绿素b>叶绿素a>叶绿素a+b>类胡萝卜素;3种抗氧化酶对Cd敏感顺序为：POD>CAT>SOD.各生理指标IC50表明,油菜只适宜种植在Cd含量小于5 mg·kg^-1的土壤中.     

Queuine promotes antioxidant defence system by activating cellular antioxidant enzyme activities in cancer

Constant generation of Reactive oxygen species (ROS) during normal cellular metabolism of an organism is generally balanced by similar rate of consumption by antioxidants. Imbalance between ROS production and antioxidant defense results in increased level of ROS causing oxidative stress which leads to promotion of malignancy. Queuine is a hyper modified base analogue of guanine, found at first anti-codon position of Q- family of tRNAs. These tRNAs are completely modified with respect to queuosine in terminally differentiated somatic cells, however hypomodification of Q-tRNAs is close association with cell proliferation. Q-tRNA modification is essential for normal development, differentiation and cellular functions. Queuine is a nutrient factor to eukaryotes. It is found to promote cellular antioxidant defense system and inhibit tumorigenesis. The activities of antioxidant enzymes like catalase, SOD, glutathione peroxidase and glutathione reductase are found to be low in Dalton's lymphoma ascites transplanted (DLAT) mouse liver compared to normal. However, exogenous administration of queuine to DLAT mouse improves the activities of antioxidant enzymes. The results suggest that queuine promotes antioxidant defense system by increasing antioxidant enzyme activities and in turn inhibits oxidative stress and tumorigenesis.     

The influence of hypomagnesemia on erythrocyte antioxidant enzyme defence system in mice

The effect of magnesium deficiency on antioxidant defence system was studied in RBC of mice suffering from hypomagnesemia. The animals were kept for 8, 15 and 22 days on magnesium-deficient diet with consequent reduction of magnesium level in plasma by 38% at the first 8 days and by 64% after 22 days of experiment. The activities of the most important antioxidant enzymes, catalase, glutathione peroxidase, superoxide dismutase, glutathione reductase, glutahione S-transferase were assayed in hemolysates. The level of reduced glutathione in erythrocytes was measured as well. Apart from catalase, the activities of antioxidant enzymes were decreasing. The activity of superoxide dismutase decreased gradually during the experiment and on the 15th and 22nd day of experiment was significantly (P<0,05) lowered by 30 and 32% respectively. The catalase activity was increased on each point of the experiment with the peak value up to 149% on 15th day, and by 32% on 22nd day. Glutathione peroxidase activity was insignificantly reduced. The reduction of Glutatione reductase and Glutathione S-transferase activities by 24 and 21%, respectively, were observed after 8 days of the experiment with a further downward tendency. The reduced glutathione was significantly depleted after 8 days by 33% and was kept on that level in the course of the study. These findings support previous reports on the hypomagnesemia – induced alteration in endogenous enzyme antioxidant defences and glutathione redox cycle of mice.     

镉对泥蚶抗氧化酶系统的影响

研究了不同浓度的重金属Cd²⁺对泥蚶抗氧化酶活性的影响。设置了四组镉的梯度(0、0.025、0.05和0.1 mg·L^-1,分别在第12、24、48、96和144 h对各组织取样,用泥蚶内脏团与鳃制成酶样,对非特异性免疫抗氧化酶SOD、CAT、GST、GPX进行指标测定。结果表明,在开始的12～24 h,中低浓度组SOD酶的活力与对照组相比有显著性地提高,高浓度组SOD酶的活力变化不显著,随着暴露时间的延长和Cd²⁺浓度的增加,随后至144 h,高中浓度组SOD酶的活力降至低于对照组水平(P<0.05);GPX和GST活力的变化与SOD变化相似,它们的活性在12～48 h的范围内达到顶峰,然后与对照组相比出现显著下降;中低浓度组的CAT酶活力在第144 h时与对照组相比无显著差异(P<0.05)。在一定程度的Cd²⁺胁迫会对泥蚶体内的抗氧化酶系统造成损伤。     

Solubilization of Acid-swollen cellulose by an enzyme system from a species of alternaria

An unknown species of Alternaria, when grown on a medium containing carboxymethylcellulose as a carbon source produced a mixture of extracellular enzymes which solubilized acid-swollen cellulose. The product of the hydrolysis was a 1:2 molar mixture of cellobiose and glucose. The organism apparently produced no cellobiase. It is suggested that the mixture of cellulolytic enzymes contains at least two different enzymes which degrade cellulose in an endwise manner.     

The alkane-hydroxylating enzyme system of the yeast Candida guilliermondii.

The growth of the investigated Candida guilliermondii strain on n-alkanes induces an alkane-hydroxylating enzyme system, which consists of a cytochrome P-450 and a NADPH-dependent reductase. The cytochrome P-450 was purified to 4 nmoles per mg protein. Long-chain alkanes, preferably hexadecane to octadecane, are hydroxylated to the corresponding primary alcohol by this enzyme system. The substrate induces a type I spectrum, other compounds checked type II spectra.     

Specificity of antioxidant enzyme inhibition in skeletal muscle to reactive nitrogen species donors

Nitric oxide (*NO) and its by-products modulate many physiological functions of skeletal muscle including blood flow, metabolism, glucose uptake, and contractile function. However, growing evidence suggests that an overproduction of nitric oxide contributes to muscle wasting in a number of pathologies including chronic heart failure, sepsis, COPD, muscular dystrophy, and extreme disuse. Limited data point to the potential of inhibition various enzymes by reactive nitrogen species (RNS), including (.)NO and its downstream products such as peroxynitrite, primarily in purified systems. We hypothesized that exposure of skeletal muscle to RNS donors would reduce or downregulate activities of the crucial antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX). Diaphragm muscle fiber bundles were extracted from 4-month-old Fischer-344 rats and, in a series of experiments, exposed to either (a) 0 (control), 1, or 5 mM diethylamine NONOate (DEANO: *NO donor); (b) 0, 100, 500 microM, or 1 mM sodium nitroprusside (SNP: *NO donor); (c) 0 or 2 mM S-nitroso-acetylpenicillamine (SNAP: *NO donor); or (d) 0 or 500 microM SIN-1 (peroxynitrite donor) for 60 min. DEANO resulted in a 50% reduction in CAT, GPX, and a dose-dependent inhibition of Cu, Zn-SOD. SNP resulted in significantly lower activities for total SOD, Mn-SOD isoform, Cu, Zn-SOD isoform, CAT, and GPX in a dose-dependent fashion. Two millimolar SNAP and 500 microM SIN-1 also resulted in a large and significant inhibition of total SOD and CAT. These data indicate that reactive nitrogen species impair antioxidant enzyme function in an RNS donor-specific and dose-dependent manner and are consistent with the hypothesis that excess RNS production contributes to skeletal muscle oxidative stress and muscle dysfunction.     

Effect of iron ions on the antioxidant enzyme activities in yeast Saccharomyces cerevisiae

A complex of physiological and biochemical indices has been compared in wild and isogenic catalase-deficient strains of Saccharomyces cerevisiae grown on the media with different iron ion concentrations is 2 times higher in cytosolic catalase deficient yeast. Superoxide dismutase activity grown in the medium with 500 microM of ferrous sulphate. Under such conditions, peroxisomal catalase deficient yeast had a 2-fold decreased activity of superoxide dismutase. There is a significant difference between TBA-reactive substances content of the wild and cytosolic catalase deficient strain. It has been suggested that the repletion of iron ions in the growth medium leads to the formation of lipid oxidation products. Catalase prevents TBA-reactive substances formation in the given conditions and plays a protective role.     

Effect of hydrogen peroxide on antioxidant enzyme activities in Saccharomyces cerevisiae is strain-specific

The effect of hydrogen peroxide on the survival and activity of antioxidant and associated enzymes in Saccharomyces cerevisiae has been studied. A difference found in the response of wild-type yeast strains treated with hydrogen peroxide was probably related to the different protective effects of antioxidant enzymes in these strains. Exposure of wild-type YPH250 cells to 0.25 mM H₂O₂ for 30 min increased activities of catalase and superoxide dismutase (SOD) by 3.4-and 2-fold, respectively. However, no activation of catalase in the EG103 strain, as well as of SOD in the YPH98 and EG103 wild strains was detected, which was in parallel to lower survival of these strains under oxidative stress. There is a strong positive correlation (R ² = 0.95) between activities of catalase and SOD in YPH250 cells treated with different concentrations of hydrogen peroxide. It is conceivable that catalase would protect SOD against inactivation caused by oxidative stress and vice versa. Finally, yeast cell treatment with hydrogen peroxide can lead to either a H₂O₂-induced increase in activities of antioxidant and associated enzymes or their decrease depending on the H₂O₂ concentration used or the yeast strain specificity. Published in Russion in Biokhimiya, 2006, Vol. 71, No. 9, pp. 1243–1252.     

Elevated plasma homocysteine elicits an increase in antioxidant enzyme activity

Elevated plasma homocysteine is considered to be a risk factor for cardiovascular disease. The mechanisms for this effect are not fully understood but there is some evidence for a role for reactive oxygen species (ROS). This study was conducted to explore the effects of elevated plasma total homocysteine (tHcy) concentration on activity of antioxidant enzymes in the circulation. The study group consisted of 10 patients with inherited defects of homocysteine metabolism, from whom 41 blood samples were collected over a period of six months. Blood samples were also collected from 13 of their obligate heterozygous parents. For data analysis samples were classified as those with plasma tHcy < 20 microM or > 20 microM. The activity of erythrocyte superoxide dismutase (SOD) and plasma glutathione peroxidase (GSHPx) was elevated in samples with plasma tHcy > 20 microM. Moreover, a significant correlation was demonstrated between plasma GSHPx activity, plasma glutathione peroxidase protein and plasma tHcy. III vitro studies confirmed that this observation was not due to a simple chemical enhancement of enzyme activity. Homocysteine protected GSHPx from loss of activity following incubation at 37 degrees C. A similar effect was seen with another thiol-containing amino acid, cysteine. Results suggest that elevated plasma tHcy represents an oxidative stress, resulting in an adaptive increase in activity of antioxidant enzymes in the circulation.     

Effect of long-term cold exposure on antioxidant enzyme activities in a small mammal

Aerobic organisms continually face exposure to reactive oxygen species (ROS) and many have evolved sophisticated antioxidant systems to effectively remove them. Any increase in ROS production or weakening in this defense system may ultimately lead to oxidative stress and cellular damage. We investigated whether long-term cold exposure, which is known to lead to an elevation in metabolic rate, increased the activities of the ROS-scavenging enzymes, catalase (CAT), selenium-dependent glutathione peroxidase (GPx), and total superoxide dismutase (Total-SOD) in liver, cardiac muscle, kidney, skeletal muscle (vastus lateralis), and duodenum of short-tailed field voles (Microtus agrestis), born and maintained at either 8 +/- 3 degrees C or 22 +/- 3 degrees C. CAT, GPx, and Total-SOD activities were determined at age 61 +/- 1.9 days. An increase in CAT activity in voles maintained at 8 +/- 3 degrees C was observed in skeletal muscle (71%) and kidney (20%), with both CAT and GPx activities significantly elevated (by 40 and 43%, respectively) in cardiac muscle, when compared to voles at 22 +/- 3 degrees C. Total-SOD activity and protein content did not differ significantly between groups in any tissue. We suggest that the compensatory increases in CAT (skeletal muscle, cardiac muscle, kidney) and GPx (cardiac muscle), but not Total-SOD activities, resulting from long-term cold exposure may reflect the elevated metabolic rate, and possibly also increased ROS production, at this time.     

Elevated plasma homocysteine elicits an increase in antioxidant enzyme activity

Elevated plasma homocysteine is considered to be a risk factor for cardiovascular disease. The mechanisms for this effect are not fully understood but there is some evidence for a role for reactive oxygen species (ROS). This study was conducted to explore the effects of elevated plasma total homocysteine (tHcy) concentration on activity of antioxidant enzymes in the circulation. The study group consisted of 10 patients with inherited defects of homocysteine metabolism, from whom 41 blood samples were collected over a period of six months. Blood samples were also collected from 13 of their obligate heterozygous parents. For data analysis samples were classified as those with plasma tHcy < 20 μM or ≥ 20 μM. The activity of erythrocyte superoxide dismutase (SOD) and plasma glutathione peroxidase (GSHPx) was elevated in samples with plasma tHcy > 20 μM. Moreover, a significant correlation was demonstrated between plasma GSHPx activity, plasma glutathione peroxidase protein and plasma tHcy. In vitro studies confirmed that this observation was not due to a simple chemical enhancement of enzyme activity. Homocysteine protected GSHPx from loss of activity following incubation at 37°C. A similar effect was seen with another thiol-containing amino acid, cysteine. Results suggest that elevated plasma tHcy represents an oxidative stress, resulting in an adaptive increase in activity of antioxidant enzymes in the circulation.     

Effect of Terminalia arjuna on antioxidant defense system in cancer

Constant production of reactive oxygen species (ROS) during aerobic metabolism is balanced by antioxidant defense system of an organism. Although low level of ROS is important for various physiological functions, its accumulation has been implicated in the pathogenesis of age-related diseases such as cancer and coronary heart disease and neurodegenerative disorders such as Alzheimer’s disease. It is generally assumed that frequent consumption of phytochemicals derived from vegetables, fruits, tea and herbs may contribute to shift the balance towards an adequate antioxidant status. The present study is aimed to investigate the effect of aqueous extract of medicinal plant Terminalia arjuna on antioxidant defense system in lymphoma bearing AKR mice. Antioxidant action of T. arjuna is monitored by the activities of catalase, superoxide dismutase and glutathione S transferase which constitute major antioxidant defense system by scavenging ROS. These enzyme activities are low in lymphoma bearing mice indicating impaired antioxidant defense system. Oral administration of different doses of aqueous extract of T. arjuna causes significant elevation in the activities of catalase, superoxide dismutase and glutathione S transferase. T. arjuna is found to down regulate anaerobic metabolism by inhibiting the activity of lactate dehydrogenase in lymphoma bearing mice, which was elevated in untreated cancerous mice. The results indicate the antioxidant action of aqueous extract of T. arjuna, which may play a role in the anti carcinogenic activity by reducing the oxidative stress along with inhibition of anaerobic metabolism.     

Photosynthetic characteristics and antioxidant enzyme system in high-chlorophyll rice Gc mutant

The physiological photosynthetic characteristics and antioxidant enzyme system of the high-chlorophyll rice (Oryza sativa L.) mutant (Gc) and its wild type (Zhenshan 97B) were compared and analyzed. Resulting data showed that the total chlorophyll (Chl) and Chl b contents in the Gc mutant were significantly increased by 19.0 and 81.7%, respectively, while the increase in Chl a and thylakoid membrane protein contents was insignificant. The net photosynthetic rate (P _N) was significantly higher in the mutant; stomatal conductance, intercellular CO₂ concentration, and transpiration rate decreased significantly, and water-use efficiency increased significantly, indicating the higher photochemical efficiency of the mutant. The chlorophyll fluorescence parameters: electron transport rate and effective quantum yield of PSII photochemistry of the mutant were significantly higher than those of Zhenshan 97B. The nonphotochemical quenching of the mutant under light adaptation increased by 52.3%. The enzymatic activity of superoxide dismutase, peroxidas, and catalase in the mutant roots and leaves were all higher than those for the wild-type plants. It is believed that the higher activity of antioxidant enzymes in the mutant may be an important factor making difficult the photo-inactivation of Chl, and thus, increasing the content of Chl, especially Chl b.