Thiobarbituric Acid Reactive Substances Method Research Articles

Protective Effect of Selected Medicinal Plants against Hydrogen Peroxide Induced Oxidative Damage on Biological Substrates.

Oxidative stress is developed due to susceptibility of biological substrates to oxidation by generation of free radicals. In degenerative diseases, oxidative stress level can be reduced by antioxidants which neutralize free radicals. Primary objective of this work was to screen four medicinal plants, namely, Andrographis paniculata, Costus speciosus, Canthium parviflorum, and Abrus precatorius, for their antioxidant property using two biological substrates—RBC and microsomes. The antioxidative ability of three solvent extracts, methanol (100% and 80%) and aqueous leaf extracts, was studied at different concentrations by thiobarbituric acid reactive substances method using Fenton's reagent to induce oxidation in the substrates. The polyphenol and flavonoid content were analyzed to relate with the observed antioxidant effect of the extracts. The phytochemical screening indicated the presence of flavonoids, polyphenols, tannins, and β-carotene in the samples. In microsomes, 80% methanol extract of Canthium and Costus and, in RBC, 80% methanol extract of Costus showed highest inhibition of oxidation and correlated well with the polyphenol and flavonoid content. From the results it can be concluded that antioxidants from medicinal plants are capable of inhibiting oxidation in biological systems, suggesting scope for their use as nutraceuticals.

Antioxidant/prooxidant effects of α-tocopherol, quercetin and isorhamnetin on linoleic acid peroxidation induced by Cu(II) and H2O2

The peroxidation of linoleic acid (LA) in the presence of copper(II) (Cu(II)) ions alone and with α-tocopherol (α-TocH) was investigated in aerated and incubated emulsions at 37 °C and pH 7. Additionally, the effects of quercetin (QR) and its O-methylated derivative, isorhamnetin (IR), as potential antioxidant protectors were studied in the (Cu(II) + TocH)-induced LA peroxidation system. Cu(II)-induced LA peroxidation followed pseudo-first-order kinetics with respect to primary (hydroperoxides) and secondary (aldehydes- and ketones-like) oxidation products, which were determined by ferric thiocyanate and thiobarbituric acid-reactive substances methods, respectively. As opposed to the concentration-dependent (at 0.6 and 10.0 µM) prooxidative action of α-TocH in the absence of QR and IR, the latter two compounds showed antioxidant effect over TocH. The peroxidation of LA in the presence of Cu(II)−H2O2 combination alone and with TocH, QR and IR were also investigated in aerated and incubated emulsions, where the latter three compounds exhibited antioxidant effects.

Levothyroxine replacement therapy with vitamin E supplementation prevents oxidative stress and cognitive deficit in experimental hypothyroidism

Hypothyroidism has a variety of adverse effects on cognitive function. The treatment of levothyroxine alone cannot restore cognitive defects of hypothyroid patients. Antioxidant vitamin E supplementation could be useful in disturbances which are associated with oxidative stress and could effectively slow the progression of Alzheimer disease. Thus, the purpose of this study was to evaluate oxidative stress status of the serum and hippocampus in hypothyroidism and to examine the effects of levothyroxine replacement therapy with vitamin E supplementation on cognitive deficit. Sprague-Dawley rats were randomly divided into five groups: control group, PTU group, PTU+Vit E group, PTU+L-T4 group, and PTU+L-T4+Vit E group. Serum and hippocampus malondialdehyde (MDA) levels were determined using the thiobarbituric-acid reactive substances method. Serum and hippocampus superoxide dismutase (SOD) levels were determined by measuring its ability to inhibit the photoreduction of nitroblue tetrazolium. Learning and memory was assessed by Morris water maze test. In the present study, we found that the rats of PTU+Vit E group spent less time to find the platform on days 2, 3, 4, and 5 than the PTU group. Moreover, the rats of PTU+L-T4+Vit E group spent less time to find the platform on days 4 and 5 than the PTU+L-T4 group. The time spent in the target quadrants was measured in the probe test and no difference was observed in all groups. Oxidative damage has been observed in the serum and hippocampus of hypothyroidism rat. SOD levels of serum and hippocampus tissue were significantly increased and MDA levels were significantly decreased in the PTU+Vit E and PTU+L-T4+Vit E groups than the PTU and PTU+L-T4 groups. Therefore, these findings indicate that levothyroxine replacement therapy with vitamin E supplementation may ameliorate cognitive deficit in PTU-induced hypothyroidism through the decrease of oxidative stress status.

Effects of Low Dose Gamma-Radiation on Select Wheat Properties

The effects of space-travel-relevant radiation doses (gamma radiation) on structure, function, and antioxidant properties of select wheat cultivars (Triticum aestivum L.) were investigated. Following radiation treatment, proteins were analyzed using SDS-PAGE, mixograph, and atomic force microscopy methods. Starch granule damage and pasting curve functionality were evaluated; lipid oxidation was determined using a thiobarbituric acid reactive substances method; and antioxidant capacity was measured using 2,2-diphenyl-1-picrylhydrazyl analyses. Increasing radiation exposure resulted in significant differences between wheat cultivars. Therefore, low-dose gamma-radiation affects wheat, and differences exist between cultivars, so careful consideration is needed when selecting wheat for use in elevated radiation conditions. The Apogee cultivar is likely a better NASA candidate crop than Perigee; however, Yecora Rojo, Parshall, and/or Yavaros 79 cultivars may be more stable to radiation and provide better food functionality traits. Ultimately, wheat should be protected from radiation exposure during space travel, if possible, to maintain quality.

Insulin-induced hypoglycemia and stress oxidative state in healthy people

The purpose of this study is to assess the immediate effects of insulin-induced hypoglycemia on the natural antioxidant superoxide dismutase activity, malondialdehyde concentration, total antioxidative capacity and total thiol group concentration in young healthy subjects. In this clinical trial, 16 healthy men with the mean age of 29.3 ± 5.3 years (range 21-39 years) became volunteers to participate the study. Hypoglycemia was induced by intravenous administration of regular insulin 0.1 U/kg. Before and after inducing hypoglycemia, SOD activity was determined in red blood cells, whereas the MDA concentration was determined by thiobarbituric acid reactive substance method, total thiol groups by high-performance liquid chromatography method and total antioxidant capacity by ferric reducing/antioxidant power. A significant increase was seen in the TBARS levels following insulin-induced hypoglycemia (0.19 ± 0.07 vs. 0.38 ± 0.16 nmol/g, P < 0.001), while a significant decrement occurred in the antioxidant power (FRAP value) (321.4 ± 63.4 vs. 231.4 ± 57.5, P < 0.001), total thiol concentration (2.3 ± 0.8 vs. 1.3 ± 0.5, P = 0.001) and SOD enzyme activity (29.4 ± 8.2 vs. 23.1 ± 6.1, P < 0.001) subsequent the hypoglycemia with insulin.

Supranutritional selenium level affects fatty acid composition and oxidative stability of chicken breast muscle tissue

A total of 128 broilers were used to investigate the effect of selenium (Se) on fatty acid (FA) composition and oxidative stability of lipids in the breast muscle tissue. There were 4 replicates of 4 dietary treatments: T1 (basal diet with no added Se), T2 (T1 with 0.15 mg Se added per kg diet), T3 (T1 with 0.3 mg Se added per kg diet) and T4 (T1 with 3.0 mg Se added per kg diet). A yeast source was used for added Se. Breast muscle tissue was collected from two chickens per replicate pen for the determination of Se concentration by ICP-MS, FA profile by GC and lipid oxidation using thiobarbituric acid reactive substances method. Addition of supranutritional Se levels to chicken diets leads to the production of Se-enriched meat. Consumption of 100 g of breast meat from chickens fed diets supplemented with 0.15, 0.3 and 3 mg Se per kg of diet can provide 26, 41 and 220 μg of Se, respectively. Long-chain polyunsaturated fatty acids namely C20:3n-6, C20:4n-6, C20:5n-3, C22:5n-3 and C22:6n-3 increased linearly (p = 0.047, p < 0.001, p = 0.023, p = 0.003 and p = 0.002, respectively) as the Se inclusion levels in the diets increased. At slaughter, a linear decrease in lipid oxidation (p = 0.019) was observed with Se addition, possibly attributed to the antioxidant properties of Se. Addition of supranutritional Se to chicken diets, at levels well below those causing toxicity, leads to production of Se-enriched meat, protection of health-promoting long-chain FA like C20:5n-3 and C22:6n-3 and protection of meat quality from oxidation at day 1 after slaughter.

Salvia officinalis L. essential oils: effect of hydrodistillation time on the chemical composition, antioxidant and antimicrobial activities

Salvia officinalis L. oils were isolated from the plant's commercial dried aerial parts, by hydrodistillation, with different distillation times. The essential oils were analysed by gas chromatography and gas chromatography–mass spectrometry. The antioxidant ability was measured using a free radical scavenging activity assay using 2,2-diphenyl-1-picrylhydrazyl (DPPH), a thiobarbituric acid reactive substances (TBARS) assay, a deoxyribose assay for the scavenging of hydroxyl radical, an assay for site-specific actions and a 5-lipoxygenase assay. Antibacterial activity was determined by the agar diffusion method. 1,8-Cineole, α-pinene and camphor were the dominant components of all the essential oils. The different hydrodistillation times did not affect the oil yield nor the relative amount of the oil components. The time of hydrodistillation influenced the antioxidant activity. With the DPPH method, the oils isolated for 2 and 3 h were stronger free radical scavengers, while with the TBARS method, the highest antioxidant values were obtained in the oils isolated for 30 min, 2 and 3 h. Hydroxyl radical scavenging and lipoxygenase activity assays showed the best results with oils isolated for 1 and 3 h. With the deoxyribose method, sage oils at concentrations <1000 mg L−1 showed better activity than mannitol. The essential oil of S. officinalis showed very weak antimicrobial activity.

Bio-guided Isolation of Antioxidant Compounds from Chrysophyllum perpulchrum, a Plant Used in the Ivory Coast Pharmacopeia

Chrysophyllum perpulchrum (Sapotaceae) is used in the traditional Ivory Coast pharmacopeia to cure fevers. The extract of C. perpulchrum used for this study was the powdered form obtained from the maceration of the dried plant bark in 96% methanol, followed by evaporation to dryness. In the present study, the antioxidative and radical-scavenging activities of the methanolic extract were studied with three standard biological tests: DPPH reduction, ferric thiocyanate (FTC) lipidic peroxidation inhibition and thiobarbituric acid reacting substances (TBARS). Gallic acid and quercetin were used as references. The total amount of phenolic compounds in the extract was determined by ultraviolet (UV) spectrometry and calculated as gallic acid equivalents. Catechin and two dimeric procyanidins were found to be the compounds responsible for the activities. They were chemically dereplicated in the extract by LC-MS. For quantitation purposes, they were isolated by successive chromatographic methods and characterized by mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectrometry. The quantities of these compounds in C. perpulchrum were 5.4% for catechin (P1), and 5.6 and 9.2% for dimers (compounds 2 (P2) and 3 (P3)), respectively. They displayed antioxidant activity with IC50 values of 2.50 ± 0.15 µg/mL (P1), 2.10 ± 0.2 µg/mL (P2) and 2.10 ± 0.1 µg/mL (P3). The total extract, the active fractions and the pure compounds inhibited the lipid peroxidation by the FTC method and the TBARS method in the range of 60%. These values were comparable to those seen for quercetin.

Wine industry residue as antioxidant in cooked chicken meat

SummaryThe effectiveness of grape extracts as food ingredient has been tested in various systems. The objective of this study was to evaluate the efficiency of four concentrations of residues of the wine industry in delaying lipid oxidation in processed chicken meat stored under refrigeration. The development of oxidation during the 14‐day storage was evaluated through the thiobarbituric acid reactive substances method (TBAS). The analyses of phenolic compounds and antioxidant activity were performed in grape residue extracts through DPPH (1,1‐difenil‐2‐picrilidrazil) method, lipid peroxidation inhibition and Rancimat. The profile of polyphenols was determined using reversed‐phase high‐performance liquid chromatography. Isabel grape extract (IGE) and Niagara grape extract (NGE) showed significant content of phenolic compounds. NGE and IGE had high antioxidant activity. The addition of grape extracts significantly increased the oxidative stability of processed and cooked chicken meat during the storage time. The extracts from both grape varieties when applied in concentrations of 40 and 60 mg of GAE, presented results similar to that of Butyl hydroxy toluene (BHT).

Repercussion of acetylsalicylic acid during fetal development on later renal hemodynamics of rats

Acetylsalicylic acid (ASA) during pregnancy reaches the fetus. It seems important to know possible repercussions of ASA on later renal function of the offspring, as well as repercussions of this drug on factors that may influence fetal development, such as maternal plasma volume and placental oxidative stress. It was evaluated whether ASA changes maternal plasma volume and/or placental oxidative stress, fetal weight and renal function of the offspring at adult life. ASA (100 mg/kg/day, p.o., dissolved in ETOH 10%) or ETOH 10% was administered to Wistar rat dams, from the day 7 to day 20 of pregnancy/parturition. Plasma volume and the placental oxidative stress were evaluated on day 20 of pregnancy, using, respectively, the Evans blue dye and the thiobarbituric acid reactive substances methods. Mean arterial pressure, renal blood flow (RBF) and glomerular filtration rate (GFR) were evaluated in the anesthetized offspring, at the age of 90 days, using a blood pressure transducer, a flow probe and inulin clearance respectively. Plasma volume was 76% (P < 0.05) higher in ASA compared with that in control dams, but placental oxidative stress was the same for both groups. Fetal body weight, the number of nephrons, GFR, RBF and renal vascular resistance were similar for the same gender among the offspring of the two groups. However, reduced hematocrit (9.8%, P < 0.05), increased renal plasma flow (27%, P < 0.05) and reduced filtration fraction (32%, P < 0.05) were seen in the female offspring. In conclusion, although ASA had increased maternal plasma volume, it did not change nephrogenesis nor GFR in the adult offspring. The changes in renal plasma flow and filtration fraction seen in the ASA female offspring might partially be due to the reduced hematocrit.

Measurement of Antioxidant Activity of Wine Catechins, Procyanidins, Anthocyanins and Pyranoanthocyanins

Nowadays, there is considerable interest in finding out about antioxidants thatare consumed in the habitual diet. It is known that polyphenols are involved in reducing therisk of diseases associated with oxidative stress. The in vitro antioxidant activity of theprincipal wine polyphenolic compounds (catechins, procyanidins, anthocyanins andpyranoanthocyanins) was studied in this work. Four distinct methods were used to assessthe antioxidant capacity of the tested compounds: inhibition of peroxynitrite mediatedtyrosine nitration, TEAC (Trolox equivalent antioxidant capacity assay), FRAP (Ferricreducing/antioxidant power assay) and TBARS (thiobarbituric acid reactive substances)methods. In general, it could be concluded that procyanidins were, among the in vitrotested groups, the ones which showed more antioxidant capacity using the four differentmethods, followed by anthocyanins and pyranoanthocyanins. On the basis of the simpleregression testing, there was a statistically significant relationship between these differentmethods used in aqueous phase (r &gt; 0.92). However, no correlation was found between theresults obtained in lipid media with the TBARS method and those obtained in the aqueousmedia (peroxynitrite scavenging activity, TEAC and FRAP methods).

HIGH‐DOSE TAURINE SUPPLEMENTATION INCREASES SERUM PARAOXONASE AND ARYLESTERASE ACTIVITIES IN EXPERIMENTAL HYPOTHYROIDISM

1. Hypothyroidism is accompanied by hyperlipidaemia and oxidative stress and is associated with several complications, such as atherosclerosis. Paraoxonase activity has been reported to decrease in several situations associated with atherosclerosis and oxidative stress. In the present study, the effects of different doses of taurine on serum paraoxonase and arylesterase activities, as well as on the serum lipid profile, were investigated in hypothyroid rats. 2. Forty male Sprague-Dawley rats were randomly divided into five groups as follows: Group 1, rats received normal rat chow and tap water; Group 2, rats received standard rat chow + 0.05% propylthiouracil (PTU) in the drinking water; and Groups 3-5, taurine-supplemented PTU groups (standard rat chow + 0.5, 2 or 3% taurine in the drinking water, respectively, in addition to PTU). Paraoxon or phenylacetate were used as substrates to measure paraoxonase and arylesterase activity, respectively. Plasma and tissue malondialdehyde (MDA) levels, indicators of lipid peroxidation, were determined using the thiobarbituric-acid reactive substances method. Serum triglyceride, total cholesterol and high-density lipoprotein-cholesterol (following precipitation with dextran sulphate-magnesium chloride) were determined using enzymatic methods. 3. Serum paraoxonase and arylesterase activities were increased and plasma and tissue MDA levels and serum triglyceride levels were reduced in a dose-dependent manner in taurine-treated hypothyroid rats. Taurine concentrations were positively correlated with enzyme activities and negatively correlated with MDA and triglyceride levels. 4. Further studies are needed to investigate the role of taurine supplementation in hypothyroidism in human subjects.

Murta Leaves (Ugni molinaeTurcz) as a Source of Antioxidant Polyphenols

Extracts from Murta leaves are used by Chilean natives for their benefits on health and cosmetic properties, which are mainly due to the presence of polyphenolic compounds. Extraction of such compounds is strongly influenced by several variables, the effects of which are studied in this work; the antioxidant power of the resulting extracts was measured by two different methods [2,2-diphenyl-1-picrylhydrazyl (DPPH) and thiobarbituric acid reactive substances (TBARS)]. On the whole, maximum values of polyphenolic yields and antiradical power (DPPH method) were attained at 50 degrees C (from 25 to 50 degrees C) and a solvent-to-solid ratio (v/w) of 15:1 (15:1-25:1). The solvents assayed were ethanol, methanol, and water. The highest polyphenolic yield values (2.6% expressed as gallic acid) were reached with methanol, whereas maximum EC50 was attained by the ethanol extract (0.121 mol gallic acid/mol DPPH). Contact time was shown to have only a slight influence in alcoholic extraction, while in water a remarkable effect of increasing contact times (30-90 min) was observed. Just water was the solvent that offered the best result when the antioxidant power was measured by the TBARS method. High-performance liquid chromatography-mass spectrometry analysis revealed the presence of polyphenols, basically flavonols and flavanols, sometimes glycosilated; myricetin and quercetin glycosides were detected in all extracts, whereas epicatechin was present in alcoholic extracts and gallic acid was only present in water.

Oxidative Stress and Hematologic and Biochemical Parameters in Individuals With Down Syndrome

To evaluate the levels of thiobarbituric acid reactive substances (TBARS), uric acid, and seric superoxide dismutase and catalase activities, as well as total serum iron, total iron-binding capacity (TIBC), erythrocyte osmotic fragility, and hemograms in people with Down syndrome. The study sampled (July to December 2003) 50 people with Down syndrome and 50 individuals without Down syndrome (control group) matched by age and sex. The levels of TBARS were measured by the TBARS method. Serum superoxide dismutase and catalase activities and uric acid levels were determined spectrophotometrically. Erythrocyte osmotic fragility was assessed by the percentage of hemolysis. Hemograms, total serum iron level, and TIBC were determined with automated systems. The results showed that levels of TBARS, uric acid, and seric superoxide dismutase and catalase activities were higher in the Down syndrome group compared with the control group. We also observed a slight increase in erythrocyte osmotic fragility in the Down syndrome group, but the total serum iron levels, TIBC, and hemograms for both groups were within the age-related reference values. This was the first time, to our knowledge, that increases in seric superoxide dismutase and catalase activities were observed in people with Down syndrome. Although other studies are necessary, our results add to the understanding of the mechanisms responsible for the increased oxidative stress observed in individuals with Down syndrome and may be useful in supporting future antioxidant therapies that will improve the lives of people with Down syndrome.

Antioxidant activity of Siamese neem tree (VP1209)

Leaves, fruits, flowers and stem bark extracts from the Siamese neem tree ( Azadirachta indica A. Juss var. siamensis Valeton, Meliaceae) were assessed for antioxidant activity in vitro using the 1,1-diphenyl-2-picryl hydrazyl (DPPH) scavenging assay, total antioxidant activity and inhibition of lipid peroxidation in Chago K1 cancer cell culture by the thiobarbituric acid reactive substances (TBARS) method. The results showed that leaf aqueous extract, flower and stem bark ethanol extracts exhibited higher free radical scavenging effect on the DPPH assay with 50% scavenging activity at 26.5, 27.9 and 30.6 μg/ml, respectively. The total antioxidant activity of these extracts was found to be 0.959, 0.988 and 1.064 mM of standard trolox, respectively. At 100 μg/ml, the flower ethanol and leaf aqueous extracts significantly decreased malondialdehyde (MDA) levels (46.0 and 50.6%, respectively) by the TBARS method. The results suggest that extracts from leaf, flower and stem bark of the Siamese neem tree have strong antioxidant potential. This report supports the ethnomedical use of young leaves and flowers of this plant as a vegetable bitter tonic to promote good health.

Polyphenolic profile characterization ofAgrimonia eupatoria L. by HPLC with different detection devices

Liquid chromatography coupled to diode array and electrospray ionization mass spectrometry detection was used to establish the polyphenolic profile of an ethyl acetate fraction from Agrimonia eupatoria L. aqueous-alcoholic extract. Additionally, an HPLC technique with post-column derivatization by p-dimethylaminocinnamaldehyde was employed for the selective detection and quantification of flavan-3-ols. Important information was obtained by combining the data of these two HPLC techniques. Flavan-3-ols (catechin and procyanidins B1, B2, B3, B6, B7, C1, C2 and epicatechin-epicatechin-catechin), quercetin 3-O-glucoside, quercetin 3-O-galactoside, kaempferol 3-O-glucoside, kaempferol 3-O-(6''-O-p-coumaroyl)-glucoside, apigenin 6-C-glucoside and various phenolic acids were identified. Antioxidant activity of the Agrimonia eupatoria L. fraction containing these compounds was assessed through the 1,1-diphenyl-2-picrylhydrazyl, trolox equivalent antioxidant capacity and thiobarbituric acid reactive substances methods. Significant activity was observed for this fraction, where compounds with recognized antiinflammatory properties such as procyanidins, kaempferol 3-O-(6''-O-p-coumaroyl)-glucoside and quercetin glycosides were identified for the first time. These results are predictive of the beneficial effects of this fraction, or some of its compounds, in human health, as possible anti-inflammatory drug.

No Increase of Plasma Malondialdehyde after Primary Coronary Angioplasty for Acute Myocardial Infarction

Objective : Free radicals formed after coronary artery occlusion and reperfusion are assumed to produce myocardial stunning and possibly other forms of reperfusion injury as well. Malondialdehyde (MDA) is an end product in the lipid peroxidation chain reaction and is frequently used as a marker for free oxygen radical production. Increased levels of plasma MDA have been found following successful thrombolytic therapy. The aim of this study was to investigate whether plasma MDA levels also increase after successful primary percutaneous transluminal coronary angioplasty (PTCA) in acute myocardial infarction (AMI). Design : In 23 patients with AMI, treated with primary PTCA, plasma MDA was analysed using a high-performance liquid chromatography method (HPLC). The results obtained with this method were compared with those obtained with a fluorimetric assay of thiobarbituric acid reactive substances (TBARS). This assay measures MDA but with a lower specificity. Results : We found a significant decrease of plasma MDA from baseline 0.99 to 0.87 µmol/l at 30 min and to 0.90 µmol/l at 90 min following the primary PTCA ( p = 0.048 and 0.014, respectively). No significant changes in TBARS method levels were observed. Conclusion : Instead of the expected increase in MDA following reperfusion we found a significant decrease. The results from measurements of MDA and TBARS were significantly incompatible. The results raise serious doubts as to the usefulness of increased plasma levels of MDA as a marker of oxidative stress caused by coronary reperfusion in patients treated with angioplasty.

Elisa to quantify hexanal-protein adducts in a meat model system.

Monoclonal antibodies (MAb) were produced to hexanal-bovine serum albumin conjugates. An indirect competitive ELISA was developed with a detection range of 1-50 ng of hexanal/mL. Hexanal conjugated to three different proteins was recognized, whereas free hexanal and the native proteins were not detected. The antibody cross-reacted with pentanal, heptanal, and 2-trans-hexenal conjugated to chicken serum albumin (CSA) with cross-reactivities of 37.9, 76.6, and 45.0%, respectively. There was no cross-reactivity with propanal, butanal, octanal, and nonanal conjugated to CSA. The hexanal content of a meat model system was determined using MAb and polyclonal antibody-based ELISAs and compared with analysis by a dynamic headspace gas chromatographic (HS-GC) method and a thiobarbituric acid reactive substances (TBARS) assay. Both ELISAs showed strong correlations with the HS-GC and TBARS methods. ELISAs may be a fast and simple alternative to GC for monitoring lipid oxidation in meat.

The effects of chemical sympathectomy on testicular injury in varicocele.

To determine whether the sympathetic nervous system plays a role in the contralateral testicular deterioration encountered in varicocele. Forty male Sprague-Dawley albino rats (28 days old) were divided equally into four treatment groups, i.e. (1) sham operation, (2) with varicocele, (3) treated by chemical sympathectomy plus varicocele, and (4) chemical sympathectomy only. Chemical sympathectomy was induced by administering intraperitoneal 6-OH dopamine (100 microg/g for 5 days) in groups 3 and 4; groups 1 and 2 received equal volumes of physiological saline by the same route. All rats underwent laparotomy and part of the left renal vein (distal to the spermatic vein confluence) was isolated and encircled with a 4/0 silk suture. The suture was left untied in group 2, and tied around a 24 F peripheral venous cannula in groups 3 and 4. The testes were then excised when the rats were 70 days old; malondialdehyde (MDA) in the testicular tissue was assayed by the thiobarbituric acid-reactive substances method, and superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels were determined by spectrophotometric analysis. Varicocele resulted in a significant increase in MDA levels in both testes and chemical sympathectomy prevented this effect. SOD and GSH-Px values were significantly decreased in both testes in group 2; chemical sympathectomy also prevented this effect. An induced unilateral varicocele significantly increases the biochemical indicators of tissue hypoxia in both testes. As this increase was prevented by chemical sympathectomy, the sympathetic nervous system may play a role in the testicular degeneration associated with varicocele.

The Effects of Allopurinol in Hepatic Ischemia and Reperfusion: Experimental Study in Rats

Background/Aims: Some studies have shown that postischemic hepatic dysfunction is mainly due to oxygen free radicals that are generated by xanthine oxidase. The present study was undertaken to determine the effect of allopurinol, an inhibitor of xanthine oxidase, on oxidative stress, liver injury and histologic alterations induced by hepatic ischemia-reperfusion in rats. Methods: One hundred and sixty Wistar rats were used and divided into three groups. Group 1: sham operation; group 2: 50 min of ischemia followed by 1 h of reperfusion, and group 3: pretreatment with allopurinol and 50 min of ischemia followed by 1 h of reperfusion. The effect of allopurinol was evaluated by plasma levels of alanine aminotransferase and aspartate aminotransferase, histopathologic studies, and lipid peroxidation measured by the thiobarbituric acid reactive substances method and chemiluminescence initiated by tert-butyl hydroperoxide technique. Results: Ischemia followed by reperfusion promoted an increase in lipid peroxidation of the hepatic cells when compared to the sham-operated group (p < 0.05). This increase was attenuated in the group treated with allopurinol (p < 0.05). Allopurinol also showed a protective effect on hepatocellular necrosis (p < 0.05), and the plasma levels of liver enzymes returned earlier to the normal range in rats pretreated with allopurinol in comparison to those that did not receive the drug (p < 0.05). Conclusions: Allopurinol exerted a protective effect on hepatic ischemia and reperfusion in rats. The administration of this drug prior to liver operations should be considered to be submitted to trials in humans.