Higher Thiobarbituric Acid Reactive Substances Research Articles

Changes in Red Hake (Urophycis chuss) Muscle Induced by Different Freezing Strategies

The effect of single and double freezing at −20°C on fresh and aged red hake with two different holding times of the thawed fillets between the first and second freezing treatments was determined. In addition, twice-frozen fresh red hake was treated with two antioxidation systems to assess their effectiveness in reducing lipid oxidation. Fresh, untreated red hake at 0 time was used for comparison. Significant dimethylamine (DMA) production occurred with all frozen samples, and the differences were not marked after 7-month storage. With a storage time of 3 months, however, there were differences between the treatments in both the fresh and aged samples with the once-frozen sample producing the least DMA, the twice-frozen sample with the 24-h holding time between freezings the most, and the twice-frozen sample with a 6-h holding time between freezings giving intermediate values. All samples showed a greater than 50% loss in protein solubility as determined by lithium chloride extraction after 3 months of storage, and the protein solubility declined further when samples were tested at 7 months. Samples with the best (once-frozen fresh) and worst (twice-frozen with 24-h holding time between freezings of 5-day aged muscle) treatments had the highest thiobarbituric acid-reactive substances (TBARS) values. Both antioxidant treatments were effective in reducing TBARS development.

Lipid Peroxidation Induced by Expandable Clay Minerals

Small-sized environmental particles such as 2:1 phyllosilicates induce oxidative stress, a primary indicator of cell damage and toxicity. Herein, potential hazards of clay particle uptake are addressed. This paper reports that the content and distribution of structural Fe influence the ability of expandable clay minerals to induce lipid peroxidation (LP), a major indicator of oxidative stress, in biological matrices. Three smectite clays, hectorite (SHCa-1) and two nontronites (NAu-1) and (NAu-2) containing varying total content and coordination environment of structural Fe, were selected. Screening and monitoring of LP was conducted using a thiobarbituric acid reactive substances (TBARS) assay. The higher content of TBARS in nontronites than that in SHCa-1 suspensions was explained because structural Fe contributes to LP. The observed lack of correlation between TBARS content and the extent of Fe dissolution indicated that the formation of TBARS is surface controlled. Results showing a high TBARS content in SHCa-1 but not in nontronite supematant solutions was explained because the former contains distinct, soluble chemical component(s) that could (i) induce LP by its (their) own right and (ii) whose chemical affinity for organic ligands used as inhibitors is weak. Clays serve as stronger inductors than 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) but are much weaker than FeSO4. The outcome of this work shows that LP is clay surface-controlled and dependent on clay structural composition.

EFFECT OF STORAGE TEMPERATURE ON MEAT QUALITY OF MUSCLE WITH DIFFERENT FIBER TYPE COMPOSITION FROM KOREAN NATIVE CATTLE (HANWOO)

ABSTRACT Three kinds of Hanwoo (Korean native cattle) muscles (Loin, strip loin and inside round) were obtained from a local farm and then divided into two storage temperatures (0 and 5C), respectively. In meat color, redness (a*) was significantly higher in 5C storage samples compared with 0C storage samples in all muscle samples after 7 days of storage. Loin had significantly lower purge loss than other muscle samples, whereas inside round was significantly higher in purge loss. Strip loin showed lower shear force values compared with those of other muscle samples. 5C storage samples had significantly higher thiobarbituric acid reactive substances value than 0C storage samples in all muscle samples. In sensory evaluation, overall acceptability was significantly higher at 14 or 21 days of storage in all muscle samples, and 5C storage samples showed higher overall acceptability compared with 0C storage samples.PRACTICAL APPLICATIONSThis result will obtain information to help understand the meat quality in Hanwoo for the foreign scientists. The results of the present study showed that meat qualities of Hanwoo were much higher in 5C storage sample compared with 0C samples in all muscle samples until 35 days of storage, and loin sample showed higher sensory score than strip loin and inside round samples.

Lipid peroxidation and biochemical parameters in umbilical cord blood of well-adapted term newborns

Lipid peroxidation (LPX) can play an important role in the development of pathological changes of foetal and neonatal tissues. We investigated LPX and biochemical parameters in plasma from mixed umbilical cord (m.u.c.) blood and acid-base balance (ABB) parameters in m.u.c. blood of well-adapted full-term newborns. LPX products were estimated as thiobarbituric acid reacting substances (TBARS) and were expressed by using of malondialdehyde (MDA) as a standard solution. Intensity of LPX was estimated in vitro in m.u.c. blood plasma without and with added LPX activator (125 μM L-ascorbate plus 5 μM FeSO4) and in the incubated plasma (30 min, 37°C) under both conditions. Actual TBARS (3.51 ± 0.49 nmol/mL) were determined in the non-incubated plasma without the added LPX activator. Approximately twice higher TBARS were found in the incubated plasma without the LPX activator (7.29 ± 2.17 nmol/mL) or with it (8.57 ± 2.20 nmol/mL), as well as in the non-incubated plasma after its addition (7.38 ± 1.98 nmol/mL). All analysed biochemical parameters (Fe, total iron-binding capacity, uric acid, proteins, Mg, Ca, phosphate, glucose, K, Na, Cl, ALT, AST, GMT, CK, LD, HBD, AMS, ALP, ACP) and ABB parameters were within their reference ranges. The actual TBARS levels were found being positively correlated with α-hydroxybutyrate dehydrogenase (HBD) activity and negatively with pO2. These results suggest that LPX in m.u.c. blood plasma might be activated. This activation could probably depend on extent of hypoxia. TBARS and their formation in vitro could be suitable parameters of LPX in m.u.c. blood.

ApoE(-/-)Mice에서 배추김치 활성 성분인 3-(4'-hydroxyl-3',5'-dimethoxylphenyl)Propionic Acid의 장기 지질저하 효과

본 연구는 동맥경화를 억제하는 것으로 보고된 김치 활성성분인 HDMPPA가 동맥경화 식이를 섭취한 apoE<SUP>(-/-)</SUP> mice 의 주요 장기(동맥제외)에서 지질 축적 억제 및 항산화 효과를 살펴보았다. ApoE<SUP>(-/-)</SUP> mice는 1% 콜레스테롤과 10% 라드를 함유한 합성식이를 8주간 섭취하면서 HDMPPA(1 ㎎/BW/day)를 복강 주사하였고 대조군은 동일양의 PBS를 주사하였다. 간, 신장, 비장, 폐, 고환 그리고 뇌 조직에서 콜레스테롤, 중성지질, TBARS, 총 GSH 농도 및 GSH-peroxidase 활성을 측정하였다. 대조군의 콜레스테롤 농도는 폐, 비장 그리고 뇌에서 높았으며 간이 가장 낮았는데 이러한 경향은 HDMPPA군에서도 동일하게 관찰되었으나 축적된 콜레스테롤 농도는 낮았다. HDMPPA의 콜레스테롤 축적 억제 효과는 간(22.65%, p＜0.01), 비장(11.73%, p＜0.05), 그리고 뇌(15.34%, p＜0.05)에서 유의적으로 관찰되었다. 이에 반해 중성지질의 농도는 간, 신장 그리고 고환에서 높아 총콜레스테롤 축적과 다른 양상을 보였는데 이는 apo E<SUP>(-/-)</SUP> 마우스의 간이 중성지질을 함유한 지단백질을 받아들이는 데는 문제가 없기 때문으로 생각된다. HDMPPA군의 간(14.7%, p＜0.05), 신장(22.83%, p＜0.001) 그리고 비장(35.87%, p<0.05)의 중성지질 농도는 유의적으로 낮았다. 지질과산화물 농도(TBARS)는 불포화지방산을 다량 함유한 뇌와 peroxisome이 발달하여 활성산소의 생성이 높은 비장에서 가장 높았으며 항산화물질을 다량 함유하고 있는 고환이 가장 낮았다. HDMPPA군의 비장의 TBARS 농도는 대조군에 비해 21.47%(p＜0.01) 유의적으로 낮았다. GSH 농도는 고환, 간, 그리고 신장에서 높아 TBARS 결과와 반대였다. GSH-px 활성이 높은 장기의 GSH 농도는 낮은 편이었으나 간과 비장은 예외였다. HDMPPA군의 GSH 농도는 대조군에 비해 모든 장기에서 유의적으로 높았는데 이는 알려져 있는 HDMPPA의 항산화작용 때문으로 생각된다. 이상의 결과로부터 김치의 활성 성분인 HDMPPA는 동맥경화유발 식이를 섭취한 apoE<SUP>(-/-)</SUP> mice의 주요 장기에서 지질축적을 억제하며 체내 항산화 작용을 돕는 효과가 있음을 확인하였다.

Abstract 854: Long-term Effects of Telmisartan, an Angiotensin II Receptor Blocker in Hypertensive Patients with Chronic Kidney Disease

Hypertension and Chronic Kidney Disease (CKD) is known as a major risk factor for cardiovascular disease (CVD). This study was designed to investigate endothelial function and long-term outcome of telmisartan, angiotensin II receptor blocker, in hypertensive patients with CKD. Seventy one untreated hypertensive patients with CKD (stage 3 or 4) were randomized to receive telmisartan ( Telmisartan group , n=35) or amlodipine ( Amlodipine group , n=36). Flow-mediated dilatation (FMD) and nitroglycerin-induced dilatation (NID) of brachial artery were measured by using ultrasound system. Pulse wave velocity (PWV) was measured by using oscilometric technique. We also measured high sensitivity C-reactive peptide (hsCRP) and thiobarbituric acid reactive substance (TBARS) as indexes of inflammation and oxidative stress. The primary outcome was death from CVD, or hospitalization for CVD during a follow-up period 4.2 to 4.7 years (median, 4.4 years). Blood pressure was significantly decreased in the both groups, and there was no difference between two groups at baseline and during study. FMD was significantly increased, and PWV, hsCRP, and TBARS were significantly decreased in the both groups after the treatment. However, these improvements were much better in the telmisartan group as compared with the amlodipine group. The 4.4-year cumulative primary-event rates were 12.6% in the telmisartan group and 37.4% in the amlodipine group (p=0.012 by long-lank test). Telmisartan improves not only endothelial function, PWV, hsCRP, or TBARS, but also long-term cardiovascular outcome in hypertensive patients with CKD.

Role of male factor in early recurrent embryo loss: do antioxidants have any effect?

To evaluate whether increasing antioxidant intake in men with high levels of DNA damage or lipid peroxidation improves gestational results in couples with history of recurrent embryo loss. Descriptive study (case series). Early recurrent embryo loss program at the University of Antioquia, Medellín, Colombia. Seventeen men whose spouses had a history of two or more embryo losses before 12 weeks of gestation. Male partners with increased DNA fragmentation index (%DFI) or high thiobarbituric acid reactive substances (TBARS) were instructed to consume a diet rich in antioxidants or commercial multivitamins containing beta-carotene, vitamin C, vitamin E, and zinc for at least 3 months. Pregnancy outcome was recorded in the spouses of men with increased %DFI or TBARS who received antioxidant supplementation. Of the 17 men, 9 (53%) presented with an increased %DFI or TBARS. They were started on an antioxidant supplementation regimen. Of these nine men, six of their spouses became pregnant. All couples whose male partners accepted antioxidant supplementation achieved a successful pregnancy. Our study demonstrates the benefits of an increased intake of antioxidant-rich food or antioxidant supplements by men who show high levels of sperm DNA fragmentation or lipid peroxidation, which could result in an improvement in gestational outcomes in couples with history of recurrent embryo losses.

The various impacts of the hepatitis C virus core protein upon hepatic oxidative stress after common bile duct ligation and partial hepatectomy

Introduction: Although it is uncertain how the hepatitis C virus (HCV) core protein influences hepatic oxidative stress after partial hepatectomy and common bile duct ligation (CBDL) this may be crucial for the prognosis of patients with HCV infection who have undergone hepatic resection, or who have complications due to a biliary tract obstruction.Materials and methods: A group of double transgenic mice (DTM) that express both the tetracycline transactivator (tTA) and the HCV core, with conditional, acute expression of the HCV core in the context of the mature liver were subjected to 43% partial hepatectomy and CBDL. The levels of thioredoxin-1, thiobarbituric acid reactive substances (TBARS), and 4-hydroxynonenal (4-HNE) were evaluated in liver samples taken 3 days after the operations.Results: The DTM had significantly higher TBARS levels than mice that were transgenic for only tTA (i.e. single transgenic mice; STM) and non-transgenic mice (NTM) after a sham laparotomy, CBDL and partial hepatectomy. Of the DTM, the TBARS levels were higher in female mice than in males after a sham laparotomy (P = 0.02) and CBDL (P = 0.0001). 4-HNE staining data were compatible with these results. Furthermore, male DTM exhibited higher levels of thioredoxin-1 than female DTM after sham laparotomy (P = 0.012) and CBDL (P = 0.008).Conclusions: The HCV core increases hepatic oxidative stress in vivo and female DTM are more vulnerable to the oxidative stress caused by acute core expression with, or without, CBDL. The fact that the female DTM had lower thioredoxin-1 levels may account for this observation.

Efeito do uso de óleo de vísceras de aves oxidado na ração de frangos de corte sobre o desempenho, a composição da carcaça e a estabilidade oxidativa da carne da sobrecoxa

Foi conduzido um experimento utilizando-se 200 pintos de corte da linhagem Ross de 10 a 40 dias de idade alimentados com ração à base de milho e farelo de soja e suplementada com 4% de óleo de vísceras de aves fresco ou oxidado, com o objetivo de avaliar os efeitos da qualidade do óleo utilizado nas rações sobre o desempenho de frangos de corte e a estabilidade oxidativa da carne de sobrecoxa congelada. Óleo de vísceras recém produzido com absorbâncias específicas de 5,80 a 232 nm e 0,690 a 532 nm, indicando a presença de quantidades mínimas de compostos de oxidação, foi congelado (-18ºC) até o momento da produção das rações. O óleo oxidado foi produzido a partir deste mesmo lote, que foi aquecido em uma fritadeira elétrica com temperatura em torno de 110 a 120ºC até atingir absorbâncias específicas de 11,33 (232 nm) e 2,31 (532 nm), caracterizando o acúmulo de compostos de ranço. Aos 41 dias de idade, 136 animais foram abatidos para avaliação das características de rendimento da carcaça e das partes e as sobrecoxas desossadas e sem pele foram embaladas e mantidas sob congelamento (-20ºC). O acompanhamento do processo de oxidação lipídica da carne congelada foi avaliado mensalmente pela determinação dos compostos secundários da oxidação (TBARS). O uso do óleo de vísceras oxidado não afetou o desempenho das aves, nem as características principais da carcaça. A partir do sexto mês de armazenamento, a estabilidade oxidativa da carne de sobrecoxa congelada foi comprometida pelo consumo de rações contendo o óleo oxidado, evidenciado pelo maior valor de TBARS.

Effects of Pork Meat Cut and Packaging Type on Lipid Oxidation and Oxidative Products during Refrigerated Storage (8 °C)

Lipid oxidation and oxidative products as affected by pork meat cut, packaging method, and storage time were evaluated during refrigerated storage. Pork belly had higher pH and thiobarbituric acid reactive substance (TBARS) values than pork loin, and aerobic-packaged belly had higher TBARS than vacuum-packaged counterparts. Loin had higher free fatty acid (FFA) values than belly, and increased FFA values were observed with increased storage time. Peroxide values increased up to 7 d and decreased thereafter. Volatile compounds such as alkanes, aldehydes, ketones, and alcohols with high volatility in belly were higher than those in loin. Nonanoic acid, ethyl ester in belly, and hexadecanoic acid in loin might be considered as indices of lipid oxidation. Overall, vacuum packaging was better than aerobic packaging to retard lipid oxidation and production of oxidative products, and loin was more sensitive to lipid oxidation than belly.

Evaluation of Lipid Oxidation and Oxidative Products as Affected by Pork Meat Cut, Packaging Method, and Storage Time during Frozen Storage (−10 °C)

Lipid oxidation and oxidative volatiles as affected by pork meat cut and packaging method during frozen storage at -10 degrees C were evaluated. Pork belly cut had higher thiobarbituric acid reactive substance (TBARS) and pH values than did the loin, whereas the loin had higher free fatty acid (FFA) values than that of the belly cut. Peroxide values increased with increased storage time, but were not affected by pork meat cut and packaging method. Volatiles with carbon numbers less than 10 in the belly cut were higher than those in the loin cut, whereas those with carbon numbers greater than 10 in the loin cut were higher than those in belly cut. Most volatiles were decreased with increased storage time, except for propane. Both 4-pentenal and 4-methyl-2-hexanone in the belly cut showed a positive correlation with FFA, whereas 2,4-dimethyl-1-heptene and 9-octadecenal in the loin cut were positively correlated with TBARS and FFA, respectively, even though the values were not high enough to predict the degree of lipid oxidation.

Oxidative stress implication in a new phenotype of amyotrophic quadricipital syndrome with cardiac involvement due to lamin A/C mutation

This study aimed at evaluating OS in an amyotrophic quadricipital syndrome with cardiac impairment in a family of 80 members with a mutation in lamin A/C gene. Twelve patients had cardiac involvement (5 cardiac and skeletal muscles impairment). OS was evaluated in blood samples (thiobarbituric acid-reactive substances (TBARS), carbonylated proteins (PCO)) 6 “affected patients” with phenotypic and genotypic abnormalities without heart failure and 3 “healthy carrier” patients. OS was higher in affected patients than in healthy, as shown by the higher TBARS and PCO values. Patients with cardiac and peripheral myopathy exhibited a higher OS than patients with only cardiac disease (TBARS: 1.73 ± 0.05 vs. 1.51 ± 0.04 mmol/l (p = 0.051), PCO: 2.73 ± 0.34 vs. 0.90 ± 0.10 nmol/mg protein (p = 0.47)), and with healthy carriers patients (TBARS: 1.73 ± 0.05 vs. 1.16 ± 0.14 mmol/l (p = 0.05), PCO: 2.73 ± 0.34 vs. 0.90 ± 0.20 nmol/mg protein (p = 0.47)).OS may thus contribute to the degenerative process of this laminopathy. ROS production occurs, prior to heart failure symptoms. We suggest that the extent activation may also promote the variable phenotypic expression of the disease.

Enhanced oxidative status but not corresponding elevated antioxidative status by anticardiolipin antibody and disease activity in patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is associated with premature atherosclerosis, and an increased susceptibility of plasma lipids and lipoproteins to oxidation could at least in part promote atherogenesis. The objective of this study was to identify the effects of anticardiolipin antibody (aCL) and disease activity on oxidative and antioxidative status in patients with SLE. In this study, patients in SLE/aCL+ group and in SLE disease activity index >3 group had significantly higher thiobarbituric acid reactive substance (TBARS) levels, titers of autoantibodies against oxidized low-density lipoprotein (ox-LDL), and glutathione peroxidase activity than that of healthy controls. However, only TBARS and titers of autoantibodies against ox-LDL but not antioxidant enzyme activities were significantly different between SLE subgroups. Thus, enhanced oxidative status but not corresponding elevated antioxidative status by the presence of aCL and active disease activity make potent antioxidant therapy valuable for these SLE patients in preventing oxidative damage.

Phospholipid oxidation, non-enzymatic browning development and volatile compounds generation in model systems containing liposomes from porcine Longissimus dorsi and selected amino acids

Lipid oxidation, non-enzymatic browning development and volatile compounds generation were studied in sterile meat-model systems containing selected amino acids and/or liposomes during 35 days at 25 °C under pro-oxidative conditions, in order to simulate the ripening conditions of dry-cured meat products. Liposomes were prepared with polar lipids (PL) from Longissimus dorsi muscle of outdoors pigs fed on grass and acorns (M) or indoors ones fed on concentrates (C). Thiobarbituric acid reactive substances (TBA-RS) in systems containing both amino acids and liposomes were higher than in those containing only liposomes. The higher susceptibility to lipid oxidation of liposomes from C animal was reflected in higher TBA-RS throughout the experiment. All model systems containing liposomes and/or amino acids showed non-enzymatic browning development, as measured by the yellowness index. Major volatile compounds were fatty acid oxidation products. Strecker-derived volatile compounds were predominantly detected in model systems containing both amino acids and liposomes. The chromatographic areas of Strecker-derived volatiles increased over time whereas those of lipid-derived volatiles decreased. The occurrence of lipid oxidation, non-enzymatic browning and Strecker-type degradation of amino acids were shown in sterile meat-model systems at low temperatures.

Shelf Life of Ostrich (Struthio camelus) Liver Stored under Different Packaging Conditions

Ostrich (Struthio camelus) liver is an important edible meat by-product. However, it has a low commercial value, and it is underutilized. The present study was conducted to establish the shelf life of ostrich liver, stored at 2 ± 1°C for 18 days, under different packing conditions. Fresh livers were sliced and packed under air exposure, vacuum, and modified atmosphere (MA: 80% CO2 plus 20% N2). Shelf-life evaluation was based on color, lipid and hemopigment oxidation, microbial counts, and sensory assessment of odor and color. Samples stored under air exposure showed the highest lipid and hemopigment oxidation rate, which was detected by higher thiobarbituric acid reactive substances values and metmyoglobin percentage and lower heme iron content than livers stored under vacuum or MA. On the basis of aerobic bacteria counts, the shelf life of ostrich liver stored under aerobic conditions would be 7 days, whereas under vacuum or MA, it would be 14 days. In livers stored under anaerobic conditions (vacuum or MA packed), lactic acid bacteria represented a significant proportion of the spoilage microbiota. Minimal changes in color perception were also obtained in vacuum-packed samples at the end of the storage period. In air-packed samples, high levels of off-odors were already perceived during the first 6 days of storage, whereas in livers stored under anaerobic conditions (vacuum and MA), these levels of off-odor were not yet perceived at that time.

Increased oxidative stress and DNA damage in bipolar disorder: A twin-case report

Objective There is an emerging body of data suggesting that oxidative stress may be associated with the pathophysiology of bipolar disorder (BD). In the present study we investigated the oxidative stress profile in two monozygotic twins during a manic episode. Methods Two monozygotic twins diagnosed as currently manic by the Structured Clinical Interview for DSM-IV were studied. Serum thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD) and catalase (CAT) were measured as parameters of oxidative stress. DNA damage was assessed using the single cell gel electrophoresis technique (Comet Assay). All biochemical measures were conducted at baseline and after a 6-week treatment. Results Bipolar twins had higher TBARS, SOD and DNA damage, and lower CAT than the healthy control. TBARS and SOD were normalized after mood stabilization, whereas CAT and DNA damage remained altered at week 6. Conclusions These findings support that oxidative stress may play a role in the pathophysiology of BD and that pharmacological treatment may exert antioxidant effects. Studies with larger samples are warranted to further clarify this issue.

Comparison of two chicken genotypes organically reared: oxidative stability and other qualitative traits of the meat

The effect of genotype on the oxidative stability and other qualitative traits of chicken meat was studied. Two groups of 200 chicks (Ross 205 and Kabir) were reared according to the organic farming system. At 81 d of age 20 birds per group were slaughtered and after refrigeration (24 h at 4°C) of the carcasses, Pectoralis major muscles were excised for analyses. Samples were analysed after 0, 24, 48, 72 and 96 hours of storage at 4°C under continuous fluorescent illumination (2300 lux). The analyses concerned the chemical composition and the shear force (only at time 0) and the progress of several traits as pH, CIELAB values, Thiobarbituric Acid Reactive Substances (TBARS), panel test and fatty acid composition (at 0 and after 96 h). Genotype greatly affected the physico-chemical characteristics and the sensory evaluation. The meat from Ross chickens showed high TBARS values, perhaps due to selection for growth rate that reduced their adaptability to greater space allowance and to poorer environmental conditions; these higher TBARS values were also negatively correlated to lightness and yellowness. The initial level of TBARS affected the oxidative stability of breast meat during storage. The amount of TBARS showed significantly negative relationship with the sensory evaluation; breast meat of Kabir had higher scores for liking when the level of malondialdehyde (MDA) was less than 2.5 mg kg-1.

LDL oxidized with iron in the presence of homocysteine/cystine at acidic pH has low cytotoxicity despite high lipid peroxidation

Fe(III) can have a strong oxidizing effect in the presence of reductants at acidic pH, which may occur under anaerobic conditions or in regions of inflammation. Low density lipoprotein (LDL) oxidation with Fe(III) and homocysteine/cystine at acidic pH provoked mainly formation of lipid hydroperoxides and thiobarbituric acid reactive substances (TBARS) in the absence of significant protein modification. Even when oxidized to a high TBARS content, LDL oxidized at acidic pH was not cytotoxic when added to THP-1 monocytes in a concentration causing cell death when LDL was oxidized to a similar TBARS content at plasma pH with Fe(III) or Cu(II) in the presence or absence of homocysteine/cystine. Inducible nitric oxide production by RAW264.7 mouse macrophages was only weakly inhibited by LDL oxidized at acidic pH, even if acetylated before oxidation to increase uptake, as compared to LDL oxidized with Cu(II) at plasma pH to a similar TBARS content or anodic electrophoretic mobility. LDL oxidized at acidic pH may mainly induce protective mechanisms against oxidative stress while causing little acute damage of cells.

Ventricular Arrhythmias Following Exposure of Failing Hearts to Oxidative Stress in Vitro

There is experimental evidence that heart failure (HF) is an oxidative stress and that HF myocytes may be damaged by oxygen-derived free radicals. However, the arrhythmogenicity of these radicals has not been studied in HF. Isolated perfused hearts were obtained from sham-operated (SHAM, n = 6), and fast pacing (250 ms, 2 weeks)-induced heart failure porcines (HF, n = 8). Epicardial conduction was mapped in the longitudinal and transverse directions and ventricular arrhythmias were closely monitored after perfusion of 100, 300, and 1000 micromol/L H(2)O(2). Left ventricular epicardium was sampled for action potentials recordings in the same conditions. Myocardial levels of thiobarbituric acid reactive substances and antioxidant enzymatic capacity were also assessed. Epicardial conduction velocities were unaffected by H(2)O(2) in both groups. Isolated ventricular premature beats and runs of slow ventricular rhythm with H(2)O(2) more frequently occurred in HF compared to SHAM despite an increased antioxidant capacity including Cu/Zn and Mn superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidase. Sustained arrhythmias were not observed. Higher thiobarbituric acid reactive substances levels were found in HF confirming endogenous oxidative stress. Action potential duration at plateau level was increased following H(2)O(2) in SHAM but not in HF epicardial fibers where a toxic effect developed at 1000 micromol/L. Oxidative stress with concomitant increase in antioxidant capacity develops in this HF model. There is a greater proclivity to oxidative stress-mediated arrhythmias in HF. These arrhythmias are mainly extrasystoles or slow ventricular rhythms and not dependent on abnormal myocardial conduction.

Paraoxonase (PON1) 55 and 192 polymorphism and its effects to oxidant-antioxidant system in Turkish patients with type 2 diabetes mellıtus.

Paraoxonase (PON1) is a serum enzyme with an antioxidant function, protecting the low density lipoproteins (LDL) from oxidative modifications. Because diabetic patients are at greater risk of oxidative stress, we investigated the effect of PON1 55 methione (M)/leucine (L) and PON1 192 glutamine (A)/arginine (B) polymorphisms on oxidant-antioxidant system in 213 individuals with type 2 diabetes mellitus and 116 non-diabetic control subjects from Turkish population were included in the study. Polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP), and agarose gel electrophoresis techniques were used to determine the PON1 genotypes. Thiobarbituric acid reactive substances (TBARS), conjugated dienes levels in the serum and glutathione (GSH) levels in whole blood were measured spectrophotometrically. In both groups PON1 192 AA and PON1 55 MM genotypes had higher TBARS, conjugated dienes levels and lower GSH levels, whereas PON1 192 BB and PON1 55 LL genotypes had lower TBARS, conjugated diene levels and higher GSH level than other genotypes. We thus conclude that PON1 192 BB and PON1 55 LL alleles have protective effect against oxidative stress.