Myocardial release of malondialdehyde and purine compounds during coronary bypass surgery

Targeted Metabolomics Highlights Dramatic Antioxidant Depletion, Increased Oxidative/Nitrosative Stress and Altered Purine and Pyrimidine Concentrations in Serum of Primary Myelofibrosis Patients

To date, little is known concerning the circulating levels of biochemically relevant metabolites (antioxidants, oxidative/nitrosative stress biomarkers, purines, and pyrimidines) in patients with primary myelofibrosis (PMF), a rare form of myeloproliferative tumor causing a dramatic decrease in erythropoiesis and angiogenesis. In this study, using a targeted metabolomic approach, serum samples of 22 PMF patients and of 22 control healthy donors were analyzed to quantify the circulating concentrations of hypoxanthine, xanthine, uric acid (as representative purines), uracil, β-pseudouridine, uridine (as representative pyrimidines), reduced glutathione (GSH), ascorbic acid (as two of the main water-soluble antioxidants), malondialdehyde, nitrite, nitrate (as oxidative/nitrosative stress biomarkers) and creatinine, using well-established HPLC method for their determination. Results showed that PMF patients have dramatic depletions of both ascorbic acid and GSH (37.3- and 3.81-times lower circulating concentrations, respectively, than those recorded in healthy controls, p < 0.0001), accompanied by significant increases in malondialdehyde (MDA) and nitrite + nitrate (4.73- and 1.66-times higher circulating concentrations, respectively, than those recorded in healthy controls, p < 0.0001). Additionally, PMF patients have remarkable alterations of circulating purines, pyrimidines, and creatinine, suggesting potential mitochondrial dysfunctions causing energy metabolism imbalance and consequent increases in these cell energy-related compounds. Overall, these results, besides evidencing previously unknown serum metabolic alterations in PMF patients, suggest that the determination of serum levels of the aforementioned compounds may be useful to evaluate PMF patients on hospital admission for adjunctive therapies aimed at recovering their correct antioxidant status, as well as to monitor patients' status and potential pharmacological treatments.

Hyperkalemic or Low Potassium Cardioplegia Protects against Reduction of Energy Metabolism by Oxidative Stress

Open-heart surgery is often an unavoidable option for the treatment of cardiovascular disease and prevention of cardiomyopathy. Cardiopulmonary bypass surgery requires manipulating cardiac contractile function via the perfusion of a cardioplegic solution. Procedure-associated ischemia and reperfusion (I/R) injury, a major source of oxidative stress, affects postoperative cardiac performance and long-term outcomes. Using large-scale liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based metabolomics, we addressed whether cardioplegic solutions affect the baseline cellular metabolism and prevent metabolic reprogramming by oxidative stress. AC16 cardiomyocytes in culture were treated with commonly used cardioplegic solutions, High K+ (HK), Low K+ (LK), Del Nido (DN), histidine-tryptophan-ketoglutarate (HTK), or Celsior (CS). The overall metabolic profile shown by the principal component analysis (PCA) and heatmap revealed that HK or LK had a minimal impact on the baseline 78 metabolites, whereas HTK or CS significantly repressed the levels of multiple amino acids and sugars. H2O2-induced sublethal mild oxidative stress causes decreases in NAD, nicotinamide, or acetylcarnitine, but increases in glucose derivatives, including glucose 6-P, glucose 1-P, fructose, mannose, and mannose 6-P. Additional increases include metabolites of the pentose phosphate pathway, D-ribose-5-P, L-arabitol, adonitol, and xylitol. Pretreatment with HK or LK cardioplegic solution prevented most metabolic changes and increases of reactive oxygen species (ROS) elicited by H2O2. Our data indicate that HK and LK cardioplegic solutions preserve baseline metabolism and protect against metabolic reprogramming by oxidative stress.

Metabolic Signature of Energy Metabolism Alterations and Excess Nitric Oxide Production in Culture Media Correlate with Low Human Embryo Quality and Unsuccessful Pregnancy

Notwithstanding the great improvement of ART, the overall rate of successful pregnancies from implanted human embryos is definitely low. The current routine embryo quality assessment is performed only through morphological criteria, which has poor predictive capacity since only a minor percentage of those in the highest class give rise to successful pregnancy. Previous studies highlighted the potentiality of the analysis of metabolites in human embryo culture media, useful for the selection of embryos for implantation. In the present study, we analyzed in blind 66 human embryo culture media at 5 days after in vitro fertilization with the aim of quantifying compounds released by cell metabolism that were not present as normal constituents of the human embryo growth media, including purines, pyrimidines, nitrite, and nitrate. Only some purines were detectable (hypoxanthine and uric acid) in the majority of samples, while nitrite and nitrate were always detectable. When matching biochemical results with morphological evaluation, it was found that low grade embryos (n = 12) had significantly higher levels of all the compounds of interest. Moreover, when matching biochemical results according to successful (n = 17) or unsuccessful (n = 25) pregnancy, it was found that human embryos from the latter group released higher concentrations of hypoxanthine, uric acid, nitrite, and nitrate in the culture media. Additionally, those embryos that developed into successful pregnancies were all associated with the birth of healthy newborns. These results, although carried out on a relatively low number of samples, indicate that the analysis of the aforementioned compounds in the culture media of human embryos is a potentially useful tool for the selection of embryos for implantation, possibly leading to an increase in the overall rate of ART.

Biochemical Discrimination of the Down Syndrome-Related Metabolic and Oxidative/Nitrosative Stress Alterations from the Physiologic Age-Related Changes through the Targeted Metabolomic Analysis of Serum

Down Syndrome (DS) is a neurodevelopmental disorder that is characterized by an accelerated aging process, frequently associated with the development of Alzheimer’s disease (AD). Previous studies evidenced that DS patients have various metabolic anomalies, easily measurable in their serum samples, although values that were found in DS patients were compared with those of age-matched non-DS patients, thus hampering to discriminate the physiologic age-related changes of serum metabolites from those that are truly caused by the pathologic processes associated with DS. In the present study we performed a targeted metabolomic evaluation of serum samples from DS patients without dementia of two age classes (Younger DS Patients, YDSP, aging 20–40 years; Aged DS Patients, ADSP, aging 41–60 years), comparing the results with those that were obtained in two age classes of non-DS patients (Younger non-DS Patients, YnonDSP, aging 30–60 years; Aged-nonDS Patients, AnonDSP, aging 75–90 years). Of the 36 compounds assayed, 30 had significantly different concentrations in Pooled non-DS Patients (PnonDSP), compared to Pooled DS Patients (PDSP). Age categorization revealed that 11/30 compounds were significantly different in AnonDSP, compared to YnonDSP, indicating physiologic, age-related changes of their circulating concentrations. A comparison between YDSP and ADSP showed that 19/30 metabolites had significantly different values from those found in the corresponding classes of non-DS patients, strongly suggesting pathologic, DS-associated alterations of their serum levels. Twelve compounds selectively and specifically discriminated PnonDSP from PDSP, whilst only three discriminated YDSP from ADSP. The results allowed to determine, for the first time and to the best of our knowledge, the true, age-independent alterations of metabolism that are measurable in serum and attributable only to DS. These findings may be of high relevance for better strategies (pharmacological, nutritional) aiming to specifically target the dysmetabolism and decreased antioxidant defenses that are associated with DS.

ILB® Attenuates Clinical Symptoms and Serum Biomarkers of Oxidative/Nitrosative Stress and Mitochondrial Dysfunction in Patients with Amyotrophic Lateral Sclerosis

Oxidative/nitrosative stress and mitochondrial dysfunction is a hallmark of amyotrophic lateral sclerosis (ALS), an invariably fatal progressive neurodegenerative disease. Here, as an exploratory arm of a phase II clinical trial (EudraCT Number 2017-005065-47), we used high performance liquid chromatography(HPLC) to investigate changes in the metabolic profiles of serum from ALS patients treated weekly for 4 weeks with a repeated sub-cutaneous dose of 1 mg/kg of a proprietary low molecular weight dextran sulphate, called ILB®. A significant normalization of the serum levels of several key metabolites was observed over the treatment period, including N-acetylaspartate (NAA), oxypurines, biomarkers of oxidative/nitrosative stress and antioxidants. An improved serum metabolic profile was accompanied by significant amelioration of the patients' clinical conditions, indicating a response to ILB® treatment that appears to be mediated by improvement of tissue bioenergetics, decrease of oxidative/nitrosative stress and attenuation of (neuro)inflammatory processes.

Translocator Protein Modulation by 4'-Chlorodiazepam and NO Synthase Inhibition Affect Cardiac Oxidative Stress, Cardiometabolic and Inflammatory Markers in Isoprenaline-Induced Rat Myocardial Infarction

The possible cardioprotective effects of translocator protein (TSPO) modulation with its ligand 4'-Chlorodiazepam (4'-ClDzp) in isoprenaline (ISO)-induced rat myocardial infarction (MI) were evaluated, alone or in the presence of L-NAME. Wistar albino male rats (b.w. 200-250 g, age 6-8 weeks) were divided into 4 groups (10 per group, total number N = 40), and certain substances were applied: 1. ISO 85 mg/kg b.w. (twice), 2. ISO 85 mg/kg b.w. (twice) + L-NAME 50 mg/kg b.w., 3. ISO 85 mg/kg b.w. (twice) + 4'-ClDzp 0.5 mg/kg b.w., 4. ISO 85 mg/kg b.w. (twice) + 4'-ClDzp 0.5 mg/kg b.w. + L-NAME 50 mg/kg b.w. Blood and cardiac tissue were sampled for myocardial injury and other biochemical markers, cardiac oxidative stress, and for histopathological evaluation. The reduction of serum levels of high-sensitive cardiac troponin T hs cTnT and tumor necrosis factor alpha (TNF-α), then significantly decreased levels of serum homocysteine Hcy, urea, and creatinine, and decreased levels of myocardial injury enzymes activities superoxide dismutase (SOD) and glutathione peroxidase (GPx) as well as lower grades of cardiac ischemic changes were demonstrated in ISO-induced MI treated with 4'-ClDzp. It has been detected that co-treatment with 4'-ClDzp + L-NAME changed the number of registered parameters in comparison to 4'-ClDzp group, indicating that NO (nitric oxide) should be important in the effects of 4'-ClDzp.

Protection of cholinergic and antioxidant system contributes to the effect of Vitamin D3 ameliorating memory dysfunction in sporadic dementia of Alzheimer's type

OBJECTIVE

Investigate Vitamin D3 (VD3) effect on the Acetylcholinesterase (AChE), oxidative damage and behavioral tests in animals subjected to Intracerebroventicular injection of Streptozotocin (ICV-STZ) simulating a Sporadic Dementia of Alzheimer's Type (SDAT) and treated with VD3 (21 days).

METHODS

Animals were divided into eight groups: Vehicle, VD12.5 μg/kg, VD42 μg/kg, VD125 μg/kg, STZ, STZ+VD12.5 μg/kg, STZ+VD42 μg/kg, STZ+VD125 μg/kg.

RESULTS

VD3 prevented the increase in AChE in groups of VD42 µg/kg and VD125 µg/kg; in AChE of synaptossomes and TBARS levels prevented the increase in group VD125 µg/kg; in ROS levels there was not a significant difference; for the Carbonyl Content all doses prevented the increase. Total Thiols prevent the decrease in VD42 µg/kg and VD125 µg/kg, and Reduced Glutathione prevented the decrease in VD125 µg/kg, Oxidized Glutathione prevented the increase in VD125 µg/kg. In relation to behavioral tests, the VD3 prevented the increase in time to find (days 2 and 3), in the time to find the platform (day 3) and in time spent in the quadrant (day 2). However, in relation to crossings there was not difference in groups. These results indicated the therapeutic effect of the VD3 in model of STZ in rats.

Malondialdehyde and Uric Acid as Predictors of Adverse Outcome in Patients with Chronic Heart Failure

In chronic heart failure (HF), some parameters of oxidative stress are correlated with disease severity. The aim of this study was to evaluate the importance of oxidative stress biomarkers in prognostic risk stratification (death and combined endpoint: heart transplantation or death). In 774 patients, aged 48-59 years, with chronic HF with reduced ejection fraction (median: 24.0 (20-29)%), parameters such as total antioxidant capacity, total oxidant status, oxidative stress index, and concentration of uric acid (UA), bilirubin, protein sulfhydryl groups (PSH), and malondialdehyde (MDA) were measured. The parameters were assessed as predictive biomarkers of mortality and combined endpoint in a 1-year follow-up. The multivariate Cox regression analysis was adjusted for other important clinical and laboratory prognostic markers. Among all the oxidative stress markers examined in multivariate analysis, only MDA and UA were found to be independent predictors of death and combined endpoint. Higher serum MDA concentration increased the risk of death by 103.0% (HR = 2.103; 95% CI (1.330-3.325)) and of combined endpoint occurrence by 100% (HR = 2.000; 95% CI (1.366-2.928)) per μmol/L. Baseline levels of MDA in the 4^th quartile were associated with an increased risk of death with a relative risk (RR) of 3.64 (95% CI (1.917 to 6.926), p < 0.001) and RR of 2.71 (95% CI (1.551 to 4.739), p < 0.001) for the occurrence of combined endpoint as compared to levels of MDA in the 1^st quartile. Higher serum UA concentration increased the risk of death by 2.1% (HR = 1.021; 95% CI (1.005-1.038), p < 0.001) and increased combined endpoint occurrence by 1.4% (HR = 1.014; 95% CI (1.005-1.028), p < 0.001), for every 10 μmol/L. Baseline levels of UA in the 4^th quartile were associated with an increased risk for death with a RR of 3.21 (95% CI (1.734 to 5.931)) and RR of 2.73 (95% CI (1.560 to 4.766)) for the occurrence of combined endpoint as compared to the levels of UA in the 1^st quartile. In patients with chronic HF, increased MDA and UA concentrations were independently related to poor prognosis in a 1-year follow-up.

Shortage of Cellular ATP as a Cause of Diseases and Strategies to Enhance ATP

Germline mutations in cellular-energy associated genes have been shown to lead to various monogenic disorders. Notably, mitochondrial disorders often impact skeletal muscle, brain, liver, heart, and kidneys, which are the body’s top energy-consuming organs. However, energy-related dysfunctions have not been widely seen as causes of common diseases, although evidence points to such a link for certain disorders. During acute energy consumption, like extreme exercise, cells increase the favorability of the adenylate kinase reaction 2-ADP -> ATP+AMP by AMP deaminase degrading AMP to IMP, which further degrades to inosine and then to purines hypoxanthine -> xanthine -> urate. Thus, increased blood urate levels may act as a barometer of extreme energy consumption. AMP deaminase deficient subjects experience some negative effects like decreased muscle power output, but also positive effects such as decreased diabetes and improved prognosis for chronic heart failure patients. That may reflect decreased energy consumption from maintaining the pool of IMP for salvage to AMP and then ATP, since de novo IMP synthesis requires burning seven ATPs. Similarly, beneficial effects have been seen in heart, skeletal muscle, or brain after treatment with allopurinol or febuxostat to inhibit xanthine oxidoreductase, which catalyzes hypoxanthine -> xanthine and xanthine -> urate reactions. Some disorders of those organs may reflect dysfunction in energy-consumption/production, and the observed beneficial effects related to reinforcement of ATP re-synthesis due to increased hypoxanthine levels in the blood and tissues. Recent clinical studies indicated that treatment with xanthine oxidoreductase inhibitors plus inosine had the strongest impact for increasing the pool of salvageable purines and leading to increased ATP levels in humans, thereby suggesting that this combination is more beneficial than a xanthine oxidoreductase inhibitor alone to treat disorders with ATP deficiency.

Ameliorating role of whey syrup against ageing-related damage of myocardial muscle of Wistar Albino rats

Age-ing is involved in gradual breakdown of biological structure and function of body organs. The heart represents the main organ responsible for pumping the main issues of life which involving oxygen, nutrients and bioactive molecules necessary for maintaining the body functions. The present study has been conducted to assess the anti-aging properties of whey syrup collected from fermented milk in 4, 18 and 30-months-old rats. The histopathological and histochemical changes of carbohydrates and proteins were investigated. Immunohistochemical expression of smooth muscle actin and P53 was performed to assess the function of cardiomyocytes. Furthermore, Annexin v and biochemical changes of different cardio-biomarkers were carried out to evaluate the effects of aging. The present result of 30 months-old rats revealed myocardial infarction assessed by widening of myocardial fibers, diffused with numerous blood capillaries and dense leukocytic infiltration. The assessed biochemical markers confirmed myocardial damage. Whey supplementation improved the myocardial structure, but less improvement was observed for the 30-months-old rats. The author recommended supplementation with whey is beneficial in giving a body the demand for amino acids and minerals essential for supporting the myocardium and also provides protection against age-ing.

Lipid peroxidation in cardiac surgery: towards consensus on biomonitoring, diagnostic tools and therapeutic implementation

This review focuses on oxidative stress and more specifically lipid peroxidation in cardiac surgery, one of the fundamental theories of perioperative complications. We present the molecular pathways leading to lipid peroxidation and integrate analytical methods that allow detection of lipid peroxidation markers in the fluid phase with those focusing on volatile compounds in exhaled breath. In order to explore the accumulated data in the literature, we present a systematic review of quantitative analysis of malondialdehyde, a widely used lipid peroxidation product at various stages of cardiac surgery. This exploration reveals major limitations of existing studies in terms of variability of reported values and significant gaps due to discrete and variable sampling times during surgery. We also appraise methodologies that allow real-time and continuous monitoring of oxidative stress. Complimentary techniques highlight that beyond the widely acclaimed contribution of the cardiopulmonary bypass technology and myocardial reperfusion injury, the use of diathermy contributes significantly to intraoperative lipid peroxidation. We conclude that there is an urgent need to implement the theory of oxidative stress towards a paradigm change in the clinical practice. Firstly, we need to acquire definite and irrefutable information on the link between lipid peroxidation and post-operative complications by building international consensus on best analytical approaches towards generating qualitatively and quantitatively comparable datasets in coordinated multicentre studies. Secondly, we should move away from routine low-risk surgeries towards higher risk interventions where there is major unmet clinical need for improving patient journey and outcomes. There is also need for consensus on best therapeutic interventions which could be tested in convincing large scale clinical trials. As future directions, we propose combination of fluid phase platforms and 'metabography', an extended form of capnography-including real-time analysis of lipid peroxidation and volatile footprints of metabolism-for better patient phenotyping prior to and during high risk surgery towards molecular prediction, stratification and monitoring of the patient's journey.

Assessing Free-Radical-Mediated DNA Damage during Cardiac Surgery: 8-Oxo-7,8-dihydro-2'-deoxyguanosine as a Putative Biomarker

Coronary artery bypass grafting (CABG), one of the most common cardiac surgical procedures, is characterized by a burst of oxidative stress. 8-Oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG), produced following DNA repairing, is used as an indicator of oxidative DNA damage in humans. The effect of CABG on oxidative-induced DNA damage, evaluated through the measurement of urinary 8-oxodG by a developed and validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method in 52 coronary artery disease (CAD) patients, was assessed before (T0), five days (T1), and six months (T2) after CABG procedure. These results were compared with those obtained in 40 subjects with cardiovascular risk factors and without overt cardiovascular disease (CTR). Baseline (T0) 8-oxodG was higher in CAD than in CTR (p = 0.035). A significant burst was detected at T1 (p = 0.019), while at T2, 8-oxodG levels were significantly lower than those measured at T0 (p < 0.0001) and comparable to those found in CTR (p = 0.73). A similar trend was observed for urinary 8-iso-prostaglandin F_2α (8-isoPGF_2α), a reliable marker of oxidative stress. In the whole population baseline, 8-oxodG significantly correlated with 8-isoPGF_2α levels (r = 0.323, p = 0.002). These data argue for CABG procedure in CAD patients as inducing a short-term increase in oxidative DNA damage, as revealed by 8-oxodG concentrations, and a long-term return of such metabolite toward physiological levels.

Metabotyping Patients' Journeys Reveals Early Predisposition to Lung Injury after Cardiac Surgery

Cardiovascular disease is the leading cause of death worldwide and patients with severe symptoms undergo cardiac surgery. Even after uncomplicated surgeries, some patients experience postoperative complications such as lung injury. We hypothesized that the procedure elicits metabolic activity that can be related to the disease progression, which is commonly observed two-three days postoperatively. More than 700 blood samples were collected from 50 patients at nine time points pre-, intra-, and postoperatively. Dramatic metabolite shifts were observed during and immediately after the intervention. Prolonged surgical stress was linked to an augmented anaerobic environment. Time series analysis showed shifts in purine-, nicotinic acid-, tyrosine-, hyaluronic acid-, ketone-, fatty acid, and lipid metabolism. A characteristic 'metabolic biosignature' was identified correlating with the risk of developing postoperative complications two days before the first clinical signs of lung injury. Hence, this study demonstrates the link between intra- and postoperative time-dependent metabolite changes and later postoperative outcome. In addition, the results indicate that metabotyping patients' journeys early, during or just after the end of surgery, may have potential impact in hospitals for the early diagnosis of postoperative lung injury, and for the monitoring of therapeutics targeting disease progression.

Oxidative stress in coronary artery bypass surgery

Objective

The aim of this prospective study was to assess the dynamics of oxidative stress during coronary artery bypass surgery with cardiopulmonary bypass.

Methods

Sixteen patients undergoing coronary artery bypass grafting were enrolled. Blood samples were collected from the systemic circulation during anesthesia induction (radial artery - A1), the systemic venous return (B1 and B2) four minutes after removal of the aortic cross-clamping, of the coronary sinus (CS1 and CS2) four minutes after removal of the aortic cross-clamping and the systemic circulation four minutes after completion of cardiopulmonary bypass (radial artery - A2). The marker of oxidative stress, malondialdehyde, was measured using spectrophotometry.

Results

The mean values of malondialdehyde were (ng/dl): A1 (265.1), B1 (490.0), CS1 (527.0), B2 (599.6), CS2 (685.0) and A2 (527.2). Comparisons between A1/B1, A1/CS1, A1/B2, A1/CS2, A1/A2 were significant, with ascending values (P<0.05). Comparisons between the measurements of the coronary sinus and venous reservoir after the two moments of reperfusion (B1/B2 and CS1/CS2) were higher when CS2 (P<0.05). Despite higher values ​​after the end of cardiopulmonary bypass (A2), when compared to samples of anesthesia (A1), those show a downward trend when compared to the samples of the second moment of reperfusion (CS2) (P<0.05).

Conclusion

The measurement of malondialdehyde shows that coronary artery bypass grafting with cardiopulmonary bypass is accompanied by increase of free radicals and this trend gradually decreases after its completion. Aortic clamping exacerbates oxidative stress but has sharper decline after reperfusion when compared to systemic metabolism. The behavior of thiobarbituric acid species indicates that oxidative stress is an inevitable pathophysiological component.

Malondialdehyde-Modified LDL IgG Antibody Levels and Indices of Cardiac Function in Valvular Heart and Coronary Artery Disease Patients

OBJECTIVE

To compare the changes in anti-malondialdehyde-modified low-density lipoprotein (MDA-LDL) IgG levels among patients undergoing off-pump and on-pump coronary artery bypass grafting (CABG) or valvuloplasty.

SUBJECTS AND METHODS

A total of 38, 39 and 34 patients who underwent off-pump CABG, on-pump CABG and valvuloplasty, respectively, were enrolled in this study. Serum anti-MDA-LDL IgG values were measured 24 h before and after the operative procedures and at discharge. Echocardiography was also done before surgery and before discharge. The results were compared with values from 50 healthy controls.

RESULTS

In all patients, a reduction in antibody titers was observed post-operatively. However, the decrease was significant only in the off-pump CABG - before surgery: 42.33 (25.83-58.51), after surgery: 30.86 (16.36-51.33) and at discharge: 10.96 (6.82-23.57; p = 0.027). There was a significant positive association between anti-MDA-LDL IgG levels and ejection fraction (r = 0.248, p = 0.036) and a negative association with E/E', a marker of pulmonary capillary wedge pressure, in the coronary patients (r = -0.345, p = 0.012), but no significant associations were found in patients with valvular heart disease.

CONCLUSIONS

Serum anti-MDA-LDL IgG levels were associated with cardiac function indices in coronary patients undergoing CABG.

Oxidative stress and antioxidant status of pregnant rural women in north-west Nigeria: prospective cohort study

BACKGROUND/OBJECTIVE

This research was undertaken to determine the oxidative stress and antioxidant status of pregnant northern Nigerian women.

METHODS

Prospective cohort study. The study was done at General Hospital, Dawakin Kudu LGA, Kano. Kano has a population of 9.2 million and predominantly Muslims. Two hundred consecutive women presenting for antenatal care and 100 apparently normal controls. Ethical approval was obtained. Socio-demographic and clinical information were obtained via interviewer-administered questionnaires from 200 consecutive pregnant women who presented for antenatal care. Serum levels of vitamins A, C, E and malondialdehyde were determined. Data was analyzed with SPSS version 16.0 statistical software. Descriptive statistics was used. Means were compared using analysis of variance (ANOVA). Associations between trimesters and oxidative stress/antioxidant status were tested using chi-square test and p < 0.05 was considered statistically significant.

RESULT

The mean serum vitamin A, E and C levels were 13.39 ± 9.44 µg/dl, 0.35 ± 0.51 mg/dl and 5.99 ± 3.95 µ/dl respectively (below normal limits). The prevalence of vitamins A, C and E deficiency were 65.5%, 79.5% and 51% respectively. The mean serum levels of malondialdehyde was 4.04 ± 0.91 nmol/l (pregnant) and 1.84 ± 0.40 nmol/l (non-pregnant) (p = 0.001). There was strong negative correlation between serum levels of malondialdehyde and vitamins A, C and E.

CONCLUSION

Vitamins A, C, E deficiency and oxidative stress is a problem among Northern Nigeria pregnant women, therefore the value of antioxidant vitamin supplementation should be explored.

Cardioprotection and pharmacological therapies in acute myocardial infarction: Challenges in the current era

In patients with an acute ST-segment elevation myocardial infarction, timely myocardial reperfusion using primary percutaneous coronary intervention is the most effective therapy for limiting myocardial infarct size, preserving left-ventricular systolic function and reducing the onset of heart failure. Within minutes after the restoration of blood flow, however, reperfusion itself results in additional damage, also known as myocardial ischemia-reperfusion injury. An improved understanding of the pathophysiological mechanisms underlying reperfusion injury has resulted in the identification of several promising pharmacological (cyclosporin-A, exenatide, glucose-insulin-potassium, atrial natriuretic peptide, adenosine, abciximab, erythropoietin, metoprolol and melatonin) therapeutic strategies for reducing the severity of myocardial reperfusion injury. Many of these agents have shown promise in initial proof-of-principle clinical studies. In this article, we review the pathophysiology underlying myocardial reperfusion injury and highlight the potential pharmacological interventions which could be used in the future to prevent reperfusion injury and improve clinical outcomes in patients with coronary heart disease.

Oxidative damage in clinical ischemia/reperfusion injury: a reappraisal

AIMS

Ischemia/reperfusion (I/R) injury is a common clinical problem. Although the pathophysiological mechanisms underlying I/R injury are unclear, oxidative damage is considered a key factor in the initiation of I/R injury. Findings from preclinical studies consistently show that quenching reactive oxygen and nitrogen species (RONS), thus limiting oxidative damage, alleviates I/R injury. Results from clinical intervention studies on the other hand are largely inconclusive. In this study, we systematically evaluated the release of established biomarkers of oxidative and nitrosative damage during planned I/R of the kidney and heart in a wide range of clinical conditions.

RESULTS

Sequential arteriovenous concentration differences allowed specific measurements over the reperfused organ in time. None of the biomarkers of oxidative and nitrosative damage (i.e., malondialdehyde, 15(S)-8-iso-prostaglandin F2α, nitrite, nitrate, and nitrotyrosine) were released upon reperfusion. Cumulative urinary measurements confirmed plasma findings. As of these negative findings, we tested for oxidative stress during I/R and found activation of the nuclear factor erythroid 2-related factor 2 (Nrf2), the master regulator of oxidative stress signaling.

INNOVATION

This comprehensive, clinical study evaluates the role of RONS in I/R injury in two different human organs (kidney and heart). Results show oxidative stress, but do not provide evidence for oxidative damage during early reperfusion, thereby challenging the prevailing paradigm on RONS-mediated I/R injury.

CONCLUSION

Findings from this study suggest that the contribution of oxidative damage to human I/R may be less than commonly thought and propose a re-evaluation of the mechanism of I/R.

Serum malondialdehyde level: Surrogate stress marker in the Sikkimese diabetics

BACKGROUND

The pbreakdown of phospholipids lead to accumulation of malondialdehyde (MDA) that is preferred as a surrogate marker of oxidative stress in diabetics.

OBJECTIVE

To compare serum MDA levels along with other biochemical parameters between type 2 diabetic patients with and without complications.

MATERIALS AND METHODS

This cross-sectional study was carried out in the Department of Biochemistry of a tertiary care teaching hospital in Sikkim on 60 type 2 diabetics and compared with 100 non-diabetic participants. The un-hemolyzed blood samples were used for estimation of biochemical parameters; MDA was estimated in serum by using trichloroacetic acid (TCA) and 1% thiobarbituric acid (TBA). Whole blood was used for estimation of glycated hemoglobin. The comparison of different parameters between cases and control was calculated by using Student's t test.

RESULTS

In the study and control groups, no significant difference was noted with regard to independent variables. The fasting and postprandial serum glucose along with glycated hemoglobin from whole blood and the lipid profile differed significantly between the study and control groups. Overall, tmean serum MDA level in the study group was significantly higher thanin the controls. Male sex, addiction to tobacco (smoking and smokeless inclusive), longer duration of diabetes (≥5 years), and presence of complications (both microvascular and macrovascular) significantly increased the MDA level.

CONCLUSION

To sum up, the serum MDA level was observed to be significantly high in diabetics with and without complication along with other parameters.

HPLC analysis for the clinical-biochemical diagnosis of inborn errors of metabolism of purines and pyrimidines

The determination of purines and pyrimidines in biofluids is useful for the clinical-biochemical characterization of acute and chronic pathological states that induce transient or permanent alterations of metabolism. In particular, the diagnosis of several inborn errors of metabolism (IEMs) is accomplished by the analysis of circulating and excreted purines and pyrimidines. It is certainly advantageous to simultaneously determine the full purine and pyrimidine profile, as well as to quantify other compounds of relevance (e.g., organic acids, amino acids, sugars) in various metabolic hereditary diseases, in order to screen for a large number of IEMs using a reliable and sensitive analytical method characterized by mild to moderate costs. Toward this end, we have developed an ion-pairing HPLC method with diode array detection for the synchronous separation of several purines and pyrimidines. This method also allows the quantification of additional compounds such as N-acetylated amino acids and dicarboxylic acids, the concentrations of which are profoundly altered in different IEMs. The application of the method in the analysis of biological samples from patients with suspected purine and pyrimidine disorders is presented to illustrate its applicability for the clinical-biochemical diagnosis of IEM.

Modulation of circulating purines and pyrimidines by physical exercise in the horse

This study was designed to examine the influence of sub-maximal exercise on purine and pyrimidine catabolism in horses. Ten horses were initially trained for 12 weeks at the end of which they underwent a standardized exercise test (SET); venous blood samples were taken at rest, 5 and 30 min after the SET. Six untrained healthy horses, from which a blood withdrawal was taken at rest, were used as the control group. Samples were analyzed by HPLC for the simultaneous determination of uric acid, uridine, β-pseudouridine and creatinine in plasma. Glucose and lactate were measured in blood. Trained horses had basal uridine levels significantly lower than sedentary horses. The SET caused significant increase in plasma uric acid, uridine, β-pseudouridine and creatinine. Following the SET, a significant negative correlation was found between plasma uridine and glucose, whilst a significant positive correlation was observed between plasma uric acid and creatinine. These results indicate that increase in energy demand during exercise in the horse causes not only the degradation of purine but also of pyrimidine compounds, the latter possibly exerting a control on glucose uptake as also demonstrated in human beings.

Association between thyroid hormones, lipids and oxidative stress biomarkers in overt hypothyroidism

BACKGROUND

The aim of this study was to investigate the effect of hypothyroidism on lipid peroxidation and the antioxidant profile, as well as to evaluate the interaction between thyroid hormones and biomarkers of oxidative stress in patients with overt hypothyroidism. We also evaluated the influence of cholesterol concentrations on biomarkers of oxidative stress in these same patients.

METHODS

Total cholesterol (TC), high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD), catalase (CAT), and vitamin E were measured in 20 subjects with overt hypothyroidism (OH) and 20 controls.

RESULTS

TC, LDL cholesterol, triglycerides, TBARS, SOD, CAT, and vitamin E were significantly higher in the OH group. Significant correlation was observed for TSH and SOD, CAT, vitamin E and TBARS. Correlation was observed for triiodothyronine (T3) and SOD, CAT, vitamin E and TBARS. Significant correlation was also observed for free thyroxine and vitamin E and TBARS. However, correlation between T3 and CAT remained significant after controlling for TC concentrations.

CONCLUSIONS

Overt hypothyroidism is associated with an increase in oxidative stress, and hypercholesterolemia has a stronger influence on development of oxidative stress in hypothyroid conditions compared with thyroid hormones.

Increase of uric acid and purine compounds in biological fluids of multiple sclerosis patients

OBJECTIVES

In this study, the concentrations of uric acid, purine profile and creatinine in samples of cerebrospinal fluid and serum of multiple sclerosis (MS) patients were measured by HPLC and compared with corresponding values recorded in patients without MS (cerebrospinal fluid) and healthy subjects (serum).

DESIGN AND METHODS

All samples were deproteinized with ultrafiltration (which ensures minimal sample manipulation and efficient protein removal) and then assayed for the synchronous HPLC separation of uric acid, hypoxanthine, xanthine, inosine, adenosine, guanosine and creatinine.

RESULTS

The values of all compounds assayed were significantly higher in both biological fluids of MS patients with respect to values measured in controls. In particular, serum hypoxanthine, xanthine, uric acid and sum of oxypurines were, respectively, 3.17, 3.11, 1.23 and 1.27-fold higher in these patients than corresponding values recorded in controls (p<0.001).

CONCLUSIONS

Differently from what previously reported, we here demonstrate that all purine compounds, including uric acid, are elevated in biological fluids of MS patients. Reinforced by the trend observed for creatinine, this corroborates the notion of sustained purine catabolism, possibly due to imbalance in ATP homeostasis, under these pathological conditions. These results cast doubt on the hypothesis that uric acid is depleted in MS because of increased oxidative stress, rather suggesting that this disease causes a generalized increase in purine catabolism. As observed in other pathological states, uric acid, purine compounds and creatinine, can be considered markers of metabolic energy imbalance rather than of reactive oxygen species, even in MS.

Uric acid administration in patients with acute stroke: a novel approach to neuroprotection

Uric acid (UA) is the end product of purine catabolism in humans and is a powerful antioxidant whose generation is increased under ischemic conditions. However, both clinical and experimental studies reveal a gradual exhaustion of the antioxidant capacity after transient cerebral ischemia, and the magnitude of this consumption seems to be correlated with the extent of brain tissue injury, growth of the infarction, severity of neurological impairment in the acute phase, and long-term functional outcome. Growing evidence supports the neuroprotective effect of UA administration after brain ischemia. In experimental conditions, the administration of UA is neuroprotective both in mechanical models of brain ischemia (transient or permanent intraluminal occlusion of the middle cerebral artery) and in thromboembolic models of autologous clot injection. The administration of UA is feasible and safe in healthy volunteers. In acute stroke patients treated with recombinant tissue plasminogen activator (rt-PA), co-administration of UA has proven to reduce lipid peroxidation and to prevent the fall in UA blood levels that occur very early after stroke onset. Currently, a multicentric Phase III clinical trial is testing whether the administration of UA increases the clinical benefits of rt-PA, which represents the only approved therapy in patients with acute ischemic stroke. This review summarizes the available information justifying such a novel therapeutic approach in this devastating clinical condition.

Uric acid as a pathogenic factor in preeclampsia

Hyperuricemia is a common finding in preeclamptic pregnancies evident from early pregnancy. Despite the fact that elevated uric acid often pre-dates the onset of clinical manifestations of preeclampsia, hyperuricemia is usually considered secondary to altered kidney function. Increased serum uric acid is associated with hypertension, renal disease and adverse cardiovascular events in the non-pregnant population and with adverse fetal outcomes in hypertensive pregnancies. We hypothesize that an elevated concentration of uric acid in preeclamptic women is not simply a marker of disease severity but rather contributes directly to the pathogenesis of the disorder. Using epidemiological and experimental evidence, gained largely outside of pregnancy, we will propose pathogenic roles for uric acid in preeclamptic pregnancies. Uric acid's ability to promote inflammation, oxidative stress and endothelial dysfunction will be highlighted with discussions of the potential impact on placental development and function and maternal vascular health.

Vasopressors for cardiopulmonary resuscitation. Does pharmacological evidence support clinical practice?

Adrenaline (epinephrine) has been used for cardiopulmonary resuscitation (CPR) since 1896. The rationale behind its use is thought to be its alpha-adrenoceptor-mediated peripheral vasoconstriction, causing residual blood flow to be diverted to coronary and cerebral circulations. This protects these tissues from ischaemic damage and increases the likelihood of restoration of spontaneous circulation. Clinical trials have not demonstrated any benefit of adrenaline over placebo as an agent for resuscitation. Adrenaline has deleterious effects in the setting of resuscitation, predictable from its promiscuous pharmacological profile. This article discusses the relevant pharmacology of adrenaline in the context of CPR. Experimental and clinical evidences for the use of adrenaline and alternative vasopressor agents in resuscitation are given, and the properties of an ideal vasopressor are discussed.

Low plasma glutathione levels after reperfused acute myocardial infarction are associated with late cardiac events

OBJECTIVE

To clarify whether an altered redox state persists in the subacute phase of myocardial infarction and if specific redox patterns are associated with later cardiac events.

METHODS

Ninety-seven patients [80 men, median 63 (interquartile range, 53, 69) years] with a first acute myocardial infarction, with (53%) or without ST segment elevation, treated with successful percutaneous interventions, were tested at 5-6 days after admission for plasma alpha-tocopherol, ascorbic acid, total and reduced homocysteine, cysteine, glutathione, cysteinylglycine and blood-reduced glutathione, all assessed by high-pressure liquid chromatography. Free malondialdehyde was evaluated by gas chromatography. A subgroup of 14 patients had adjunctive blood samples within 1 h and at 72 h after angioplasty. Blood samples from 44 patients matched for age, sex, and risk factors served as controls. Patients were followed up for median 15 (interquartile range, 9, 17) months for cardiac events.

RESULTS

All plasma-reduced aminothiols, vitamins and plasma total glutathione were significantly lower in myocardial infarction at 5-6 days than in controls. In the 14 myocardial infarction patients sampled repeatedly, plasma-reduced glutathione, cysteinylglycine, total glutathione, and alpha-tocopherol significantly decreased, whereas blood-reduced glutathione, total homocysteine, and cysteine significantly increased over time. During follow-up, 20 of 97 (21%) patients had adverse cardiac events. Multivariate analysis revealed that only plasma-reduced glutathione was independently associated with events (hazard ratio 0.42, 95% confidence interval 0.18-0.99, P=0.04).

CONCLUSIONS

Acute myocardial infarction patients have an altered redox state at 5-6 days after successful reperfusion with respect to controls. Low plasma levels of reduced glutathione at discharge are associated with cardiac events at follow-up.

Could uric acid have a role in acute renal failure?

Acute renal failure (ARF), induced by either toxins or ischemia, is associated with significant morbidity. The pathogenesis of ARF is complex and is characterized by renal vasoconstriction and oxidative stress in association with tubular and microvascular injury and interstitial inflammation. In many situations, ARF is associated with a rise in serum uric acid as a result of both increased generation and decreased excretion. Although it is widely recognized that markedly elevated levels of uric acid can cause ARF via supersaturation within the tubules with crystallization and intrarenal obstruction ("acute urate nephropathy"), the possibility that uric acid may affect renal outcomes at concentrations that do not lead to tubular obstruction have not been considered. This article reviews both the salutary and the adverse effects of uric acid on biologic processes and presents the hypothesis that hyperuricemia, particularly if chronic and marked, likely represents a true risk factor for ARF. Hyperuricemia also may account for the paradoxic lack of benefit of diuretics in the management of ARF. It is suggested that studies are needed to investigate the role of chronic hyperuricemia on renal outcomes after acute tubular injury.

Effects of postconditioning of adenosine and acetylcholine on the ischemic isolated rat ventricular myocytes

In this study, protective effects of adenosine and acetylcholine-induced postconditioning were investigated on the contractile function of the ischemic isolated rat ventricular myocytes. A video-based edge-detection system was used to monitor single ventricular myocytes contraction. Adenosine and acetylcholine were administrated for 6 min before ischemia as preconditioning, or 15 min after ischemia as postconditioning. Adenosine and acetylcholine receptor antagonists and mitoKATP inhibitor were used to analyze pathways underlying the effects on postconditioning.

RESULTS

(1) The peak shortening of ischemic heart cells was improved by both adenosine and acetylcholine during preconditioning (84.72+/-5.34% and 68.61+/-8.10% vs. control: 8.43+/-5.35% of the pre-ischemia value), as well as postconditioning (76.47+/-7.87% and 57.48+/-6.97% vs. control: 8.43+/-5.35% of the pre-ischemia value) and the effects of preconditioning and postconditioning were comparable. More datum in the normal text. (2) Observed effects of adenosine and acetylcholine postconditioning were missing in the presence of adenosine A1 receptor and muscarinic M2 receptor antagonists, respectively. (3) Adenosine and acetylcholine-induced postconditioning was also blocked by mitoKATP antagonist. These results suggest that both adenosine and acetylcholine protect the contractile function of ischemic heart cells to a similar extent during preconditioning and postconditioning. The postconditioning of adenosine and acetylcholine is relative to the adenosine A1 and muscarinic M2 receptors, respectively. MitoKATP is implicated in the postconditioning of both acetylcholine and adenosine.

Urate oxidation during percutaneous transluminal coronary angioplasty and thrombolysis in patients with coronary artery disease

Thrombolysis and percutaneous transluminal coronary angioplasty (PTCA) are kinds of procedures that can be used to restore the blood flow of previously ischemic myocardium that can be the result of excessive production of reactive oxygen and nitrogen species, such as superoxide and hydroxyl radical, hypochlorous acid and peroxynitrite. Reaction of urate with some of these potent oxidants results in allantoin production. In this study, we measured the serum allantoin levels, an oxidation product of urate, and "in vivo" marker of free radical generation in reperfusion of ischemic myocardium. After an overnight fasting state, blood samples were collected from 35 patients with coronary occlusive diseases (7 women and 28 men) and 31 healthy subjects (8 women and 23 men). Serum allantoin and urate levels were measured by a GC-MS method. Serum allantoin levels of patients on PTCA therapy (mean+/-SD, 27.4 +/- 15.2 micromol/l) and thrombolytic therapy (24.6 +/- 8.6 micromol/l) were significantly higher than those of the patients without therapy (15.8 +/- 6.2 micromol/l, p < 0.05 with PTCA and p < 0.006 with thrombolysis) and healthy controls (12.6 +/- 6.3 micromol/l, p < 0.002 with PTCA and p < 0.0001 with thrombolysis). Although serum urate levels in PTCA (380.1 +/- 72.6 micromol/l) and thrombolysis (359.5 +/- 60.0 micromol/l) were higher than those in the non-therapy patients (336.6 +/- 53.8 micromol/l) and controls (318.3 +/- 81.0 micromol/l), there were no significant differences among groups (p > 0.05). The results of the study are consistent with others which have demonstrated, higher urate levels are associated with coronary occlusive diseases. Our data support the hypothesis that generation of ROS occurs during myocardial reperfusion. Increased allantoin levels may be used as an index of increased oxidative stress during reperfusion.

Simultaneous high performance liquid chromatographic separation of purines, pyrimidines, N-acetylated amino acids, and dicarboxylic acids for the chemical diagnosis of inborn errors of metabolism

OBJECTIVES

To set up a novel simple, sensitive, and reliable ion-pairing HPLC method for the synchronous separation of several purines, pyrimidines, N-acetylated amino acids, and dicarboxylic acids for the chemical diagnosis and screening of inborn errors of metabolism (IEM).

DESIGN AND METHODS

The separation was set up using a Hypersil C-18, 5-microm particle size, 250 x 4.6 mm column, and a step gradient using two buffers and tetrabutylammonium hydroxide as the pairing reagent. A highly sensitive diode array UV detector was set up at a wavelength between 200 and 300 nm that revealed purines and pyrimidines at 260 nm and other compounds at 206 nm.

RESULTS

Compounds were determined in the plasma of 15 healthy adults, in the urine of 50 healthy subjects (1-3 years, 4-6 years, 8-10 years, 12-18 years, 25-35 years), and in 10 non-pathological amniotic fluid samples. To assess the validity of the chemical diagnosis of IEM, plasma and urine samples were analyzed in patients affected by Canavan disease (n = 10; mean age 4.6 +/- 2.3). Low plasma levels of N-acetylaspartate (16.96 +/- 19.57 micromol/L plasma; not detectable in healthy adults) and dramatically high urinary N-acetylaspartate concentrations (1872.03 +/- 631.86 micromol/mmol creatinine; 450 times higher than that which was observed in age-matched controls) were recorded. Neither N-acetylglutamate nor N-acetylaspartylglutamate could be detected in the plasma or urine of controls or patients with Canavan disease.

CONCLUSIONS

The results demonstrate the suitability of the present ion-pairing HPLC separation with UV detection of cytosine, cytidine, creatinine, uracil, uridine, beta-pseudouridine, adenine, 3-methyladenine, hypoxanthine, xanthine, xanthosine, inosine, guanosine, ascorbic acid, thymine, thymidine, uric acid, 1-methyluric acid, orotic acid, N-acetylaspartate, N-acetylglutamate, N-acetylaspartylglutamate, malonic acid, methylmalonic acid, GSH, and GSSG as a reliable method for the prenatal and neonatal chemical diagnosis and screening of IEM using biological fluids.

Myocardial ischemia/reperfusion-injury, a clinical view on a complex pathophysiological process

Myocardial infarction is the major cause of death in the world. Over the last two decades, coronary reperfusion therapy has become established for the management of acute myocardial infarction (AMI). However, restoration of blood flow to previously ischemic myocardium results in the so-called ischemia/reperfusion (IR)-injury. The different clinical manifestations of this injury include myocardial necrosis, arrhythmia, myocardial stunning and endothelial- and microvascular dysfunction including the no-reflow phenomenon. The pathogenesis of ischemia/reperfusion injury consists of many mechanisms. Recently, there's increasing evidence for an important role in IR-injury on hypercontracture induced by high levels of cytosolic calcium or by low concentrations of ATP. In the last years, many studies on experimental models were investigated, but the clinical trials confirming these effects remain spare. Recently, the beneficial effect of Na(+)/H(+)-exchange inhibitor cariporide and of the oxygen-derived free radical (ODFR) scavenger vitamin E on coronary bypass surgery-induced IR-injury were demonstrated. Also recently, the beneficial effect of allopurinol on the recovery of left ventricular function after rescue balloon-dilatation was demonstrated. The beneficial effect of magnesium and trimetazidine on IR-injury remains controversial. The beneficial effect of adenosine remains to be further confirmed. There's also increasing interest in agentia combining the property of upregulating NO-synthase (e.g. L-arginine) and restoring the balance between NO and free radicals (e.g. tetrahydrobiopterin). One of such agents could be folic acid. In this review article the authors give an overview of the recent insights concerning pathogenesis and therapeutic possibilities to prevent IR-induced injury.

Effects of ischaemia-mimetic factors on isolated rat ventricular myocytes

Conventional ischaemia-mimetic solutions contain several key components for inducing hypoxia, glucose deficiency, acidosis, lactate accumulation and hyperosmosis. The effect of each component on myocyte contractility during cardiac ischaemia was investigated in this study. A video-based edge-detection system was used to monitor single ventricular myocytes isolated from the rat. The effect of each factor was compared by preparing the following ischaemia-mimetic solutions: solution A, containing all of the above-mentioned factors; and solutions B, C, D, E and F, each with one of the factors excluded. The solutions that contained lactate severely reduced the contractility of the cardiomyocytes, but cell contraction did not differ significantly between the cardiomyocytes in these solutions. The effect of the solution without the acidosis-inducing component was weaker than that of the conventional ischaemia-mimetic solution. The solution lacking lactate produced the least depression of cell contractility. Lactate impaired cardiomyocyte contractility in a concentration-dependent manner. Our observations suggest that lactate is the main contributor to cardiac ischaemic injury and that its effects are attributable to acidosis and are concentration dependent. Imposition of hypoxia, glucose deficiency and hyperosmosis had little impact on the cardiomyocytes.

Uric acid in chronic heart failure

The pathophysiologic understanding of chronic heart failure (CHF) has shifted from a mere hemodynamic disorder to a much more complex approach including changes and imbalances in neurohormonal, immune, and metabolic functions. Among metabolic abnormalities, hyperuricemia is a constant finding in CHF. The xanthine oxidase metabolic pathway increasingly is appreciated as an important contributor to both symptoms of CHF as well as progression of the disease. Recent data suggest hyperuricemia to be an independent marker of impaired prognosis in CHF. In this article, the significance of the xanthine oxidase metabolic pathway in CHF is discussed. Data on xanthine oxidase inhibition are reviewed, which suggest a beneficial effect of therapeutically targeting this enzymatic pathway.

Pyruvate-fortified cardioplegia suppresses oxidative stress and enhances phosphorylation potential of arrested myocardium

Cardioplegic arrest for bypass surgery imposes global ischemia on the myocardium, which generates oxyradicals and depletes myocardial high-energy phosphates. The glycolytic metabolite pyruvate, but not its reduced congener lactate, increases phosphorylation potential and detoxifies oxyradicals in ischemic and postischemic myocardium. This study tested the hypothesis that pyruvate mitigates oxidative stress and preserves the energy state in cardioplegically arrested myocardium. In situ swine hearts were arrested for 60 min with a 4:1 mixture of blood and crystalloid cardioplegia solution containing 188 mM glucose alone (control) or with additional 23.8 mM lactate or 23.8 mM pyruvate and then reperfused for 3 min with cardioplegia-free blood. Glutathione (GSH), glutathione disulfide (GSSG), and energy metabolites [phosphocreatine (PCr), creatine (Cr), P(i)] were measured in myocardium, which was snap frozen at 45 min arrest and 3 min reperfusion to determine antioxidant GSH redox state (GSH/GSSG) and PCr phosphorylation potential {[PCr]/([Cr][P(i)])}. Coronary sinus 8-isoprostane indexed oxidative stress. Pyruvate cardioplegia lowered 8-isoprostane release approximately 40% during arrest versus control and lactate cardioplegia. Lactate and pyruvate cardioplegia dampened (P < 0.05 vs. control) the surge of 8-isoprostane release following reperfusion. Pyruvate doubled GSH/GSSG versus lactate cardioplegia during arrest, but GSH/GSSG fell in all three groups after reperfusion. Myocardial [PCr]/([Cr][P(i)]) was maintained in all three groups during arrest. Pyruvate cardioplegia doubled [PCr]/([Cr][P(i)]) versus control and lactate cardioplegia after reperfusion. Pyruvate cardioplegia mitigates oxidative stress during cardioplegic arrest and enhances myocardial energy state on reperfusion.

The effects of propofol on lipid peroxidation and inflammatory response in elective coronary artery bypass grafting

OBJECTIVE

To determine whether the antioxidant and anti-inflammatory properties of propofol confer benefit in adult patients undergoing elective coronary artery bypass grafting.

DESIGN

Prospective, blinded, randomized, controlled clinical investigation.

SETTING

Single-center, university teaching hospital and academic research laboratory.

PARTICIPANTS

Twenty-one adult patients (11 control, 10 intervention) with chronic stable angina and normal ventricular function scheduled to undergo elective coronary artery bypass grafting.

INTERVENTIONS

All patients received a standardized fentanyl-isoflurane anesthetic. Fifteen minutes before reperfusion, patients in the intervention group received a target-controlled infusion of propofol, continued for 4 hours after cross-clamp release. Patients in the control group received saline administered in a similar fashion.

MEASUREMENTS

Serum concentration of malondialdehyde (MDA) (from systemic and coronary sinus blood); systemic concentrations of interleukins 4, 6, 8, and 10; and systemic leukocyte functions (respiratory burst, phagocytosis, and beta(2) integrin expression) were measured up to 36 hours after reperfusion.

RESULTS

A high serum malondialdehyde concentration was detected in the coronary sinus in control patients, 10 minutes after reperfusion; serum malondialdehyde was not detected in the coronary sinus at this time in patients who received propofol (41.4 [15.6-1,150] micromol/L v 0, p = 0.004). Interleukin-8 concentrations increased 2 and 4 hours after reperfusion in the control group. Interleukin-6 concentrations were greater in the control group than the propofol group 4 hours after clamp release (289.1 [165.2-561] rhog/mL v 153.2 (58.2-280.3) rhog/mL, respectively, p = 0.003). Mean dose of propofol was 31.7 mg/kg during the study period.

CONCLUSION

Clinically relevant concentrations of propofol may attenuate free radical-mediated and inflammatory components of myocardial reperfusion injury in patients undergoing elective coronary artery bypass graft surgery.

Independent association of uric acid levels with peripheral arterial disease in Taiwanese patients with Type 2 diabetes

AIMS

Hyperuricaemia may be a risk factor for atherosclerotic disease. Its association with peripheral arterial disease (PAD) has not been studied in Taiwanese patients with Type 2 diabetes.

METHODS

Uric acid (UA) levels and PAD were evaluated in 508 Taiwanese outpatients with Type 2 diabetes (210 men, 298 women; mean age +/- sd, 63.8 +/- 10.6 years). PAD was diagnosed when the ankle-brachial index was < 0.9. Patients with an ankle-brachial index of > or = 1.3 were excluded because of possible medial arterial calcification. Potential confounding variables with P < 0.10 were adjusted for in multivariate analyses.

RESULTS

In univariate analyses, UA levels were higher in patients with PAD than in those without PAD (345.0 +/- 95.2 vs. 309.3 +/- 89.2 micromol/l; P < 0.0005). Prevalences of PAD for quintiles of UA levels were 6.8, 8.9, 10.2, 13.1 and 16.5%, respectively (P-trend < 0.05). With UA level as a continuous variable, the multivariate-adjusted odds ratio (95% confidence interval) for PAD was 1.005 (1.001-1.008) (P < 0.01). The optimal cut-off point for UA as determined by the receiver operating characteristic curve was 264.7 micromol/l. The sensitivity and specificity at this cut-off point was 82.6 and 33.3%, respectively. The area under curve was 0.60 (95% confidence interval: 0.53-0.68). The multivariate-adjusted odds ratio for PAD for UA above this level was 2.736 (1.239-6.043) (P < 0.05). The results after excluding 56 cases using diuretics were similar.

CONCLUSIONS

Elevated uric acid level is a significant and independent risk factor for PAD in Taiwanese patients with Type 2 diabetes.

Reactive oxygen species as mediators of signal transduction in ischemic preconditioning

Ischemic preconditioning (IPC) is a most powerful endogenous mechanism for myocardial protection against ischemia/reperfusion injury. It is now apparent that reactive oxygen species (ROS) generated in the mitochondrial respiratory chain act as a trigger of IPC. ROS mediate signal transduction in the early phase of IPC through the posttranslational modification of redox-sensitive proteins. ROS-mediated activation of Src tyrosine kinases serves a scaffold for interaction of proteins recruited by G protein-coupled receptors and growth factor receptors that is necessary for amplification of cardioprotective signal transduction. Protein kinase C (PKC) plays a central role in this signaling cascade. A crucial target of PKC is the mitochondrial ATP-sensitive potassium channel, which acts as a trigger and a mediator of IPC. Mitogen-activated protein (MAP) kinases (extracellular signal-regulated kinase, p38 MAP kinase, and c-Jun NH(2)-terminal kinase) are thought to exist downstream of the Src-PKC signaling module, although the role of MAP kinases in IPC remains undetermined. The late phase of IPC is mediated by cardioprotective gene expression. This mechanism involves redox-sensitive activation of transcription factors through PKC and tyrosine kinase signal transduction pathways that are in common with the early phase of IPC. The effector proteins then act against myocardial necrosis and stunning presumably through alleviation of oxidative stress and Ca(2+) overload. Elucidation of IPC-mediated complex signaling processes will help in the development of more effective pharmacological approaches for prevention of myocardial ischemia/reperfusion injury.

Effects of different steroid treatment on reperfusion-associated production of reactive oxygen species and arrhythmias during coronary surgery

BACKGROUND

During conventional cardiac surgery ischemia and reperfusion may cause excessive production of reactive oxygen species leading to tissue damage including early arrhythmias. We therefore assessed the kinetics of markers of radical stress including oxidized and reduced glutathione (GSSG/GSH), oxidized proteins (PCG) and malondialdehyde (MDA), and tested the hypothesis that different steroid treatments inhibit these markers and early reperfusion-associated supraventricular and ventricular extrasystolic beats.

METHODS

In a randomized, controlled, blinded, prospective trial 36 patients received a preoperative infusion of methylprednisolone (MP, 15 mg kg-1, n = 12), tirilazad mesylate (TM, 10 mg kg-1, n = 12) or placebo (PL, NaCl, n = 12). Coronary sinus and arterial blood was drawn at baseline and 2, 5, 15, 30, 60 and 240 min after aortic declamping. Holter-ECG analysis was used to identify arrhythmias.

RESULTS

Cardiac GSSG release occurred very early (< 15 min) and was not significantly attenuated by either drug treatment. Cardiac PCG production showed biphasic increases, lasted > 4 h and was significantly reduced only by TM. Cardiac MDA release was short (< 30 min) and significantly reduced by MP and TM. Neither treatment had a significant influence on the early occurrence of ventricular or supraventricular arrhythmias. The number of patients needing cardioversions or defibrillations also were not different.

CONCLUSIONS

The results indicate that cardiac production of reactive oxygen species occurs after reperfusion in humans and is not inhibited by steroid treatment. Steroid treatment effectively reduces lipid peroxidation during cardiac surgery but has no influence on arrhythmias.

Elevated serum uric acid levels are associated with diastolic dysfunction in patients with dilated cardiomyopathy

OBJECTIVE

To assess whether serum uric acid, which is a marker of impaired oxidative metabolism, might correlate with left ventricular systolic and diastolic dysfunction in patients with chronic heart failure (CHF).

BACKGROUND

Uric acid levels, which are frequently elevated in patients with CHF, correlate with leg vascular resistance. The effects of elevated levels of uric acid on cardiac function in patients with CHF have never been evaluated.

METHODS

We studied 150 outpatients with CHF who came to our heart failure clinic. Patients underwent a complete echo-Doppler examination, with measurement of mitral E wave and mitral A wave velocities, E/A ratio, E wave deceleration time (DtE), left ventricular volumes, ejection fraction, and stroke volume. A restrictive mitral filling pattern (RMFP) was defined as either E/A ratio >2 or E/A >1 and DtE <140 milliseconds.

RESULTS

Mean age was 62.2 +/- 7.8 years (86% male); 24 patients (16%) had an RMFP. Patients with an RMFP had significantly higher uric acid levels compared with patients without RMFP (0.48 +/- 0.14 mmol/L vs 0.38 +/- 0.08 mmol/L, respectively, P <.001). Uric acid levels correlated significantly with mitral E wave velocity (r =.22, P <.01), E/A ratio (r =.21, P <.05), DtE (r =.26, P <.01), and RMFP (P =.0001). There was no correlation between uric acid and left ventricular volumes, ejection fraction, or stroke volume. In a multivariate model, uric acid predicted DtE independently of renal function, diuretic dose, and left ventricular volumes.

CONCLUSION

Elevated uric acid levels are associated with diastolic dysfunction in CHF. Xanthine oxydase inhibition in patients with CHF might theoretically result in an improvement of diastolic function.

Elevated plasma lipid peroxide levels in angina pectoris and myocardial infarction

BACKGROUND

The concept that oxidised low-density lipoprotein (LDL), not native LDL, plays a major role in atherogenesis is gaining support. Lipid hydroperoxides in plasma are carried almost exclusively in LDL and reflect oxidised LDL. Previously, elevated plasma lipid hydroperoxides were reported in coronary artery disease (CAD) patients following bypass surgery. To determine whether the increased lipid hydroperoxide was related to bypass or reflected ongoing atherosclerosis, plasma lipid hydroperoxide was measured in acute myocardial infarction (AMI) and stable angina.

METHODS

Patients with AMI (n=39) and stable angina (n=40) were compared with matched controls. Lipids and lipoproteins were selectively removed from plasma by absorption to Liposorb gel. Lipid hydroperoxide concentration in the gel was measured by a sensitive triiodide spectrophotometric technique.

RESULTS

Lipid hydroperoxide levels in AMI and stable angina were elevated (3.47+/-0.21 micromol/l, P<.001 and 3.76+/-0.24 micromol/l, P<.001) compared to controls (2.18+/-0.13 micromol/l). Previously, a concentration >3 mol/l was considered pathological. Using this criterion, we detected pathological lipid hydroperoxide concentrations in 10.3% of controls, 57.5% of AMI and 61.5% of angina patients.

CONCLUSION

Plasma lipid hydroperoxide levels are significantly elevated in AMI and angina. This is not attributable to previous cardiopulmonary bypass but to the presence of atherosclerotic disease and is likely to play a role in atherogenesis.

Elective coronary angioplasty with 60 s balloon inflation does not cause peroxidative injury

BACKGROUND

The aim of this study was to evaluate the ongoing controversial issue of whether ischemia/reperfusion during elective coronary angioplasty evokes myocardial peroxidative injury.

DESIGN

We measured indicators of free radical damage to lipids (free malondialdehyde) and proteins (sulphydryl groups) in coronary sinus blood in 19 patients with stable angina who were undergoing elective angioplasty for isolated stenosis of the proximal left anterior descending coronary artery. Ischemia induced by 60 s balloon inflations was confirmed by lactate washout into coronary sinus after deflation, with immediate and 1 min samples. Peroxidative injury was assessed from washout of (a) malondialdehyde measured directly by high performance liquid chromatography and (b) reduced sulphydryl groups, inverse marker of protein oxidative stress.

RESULTS

Mean lactate concentration immediately after each deflation increased by 120-150% of the initial value, confirming ischemia and showing that blood originated largely from the ischemic region. Lack of myocardial production of malondialdehyde was confirmed by (a) no arteriovenous differences in individual basal concentrations (aortic, range 0.33-12.03 nmol mL-1, mean 7.82; coronary sinus blood, range 0.52-15.82 nmol mL-1, mean 8.18), and (b) after deflations, mean concentrations were not significantly different from preocclusion value. There was no decrease in concentration of sulphydryl groups throughout angioplasty.

CONCLUSION

Elective coronary angioplasty with 60 s balloon inflations is a safe procedure that does not induce peroxidative myocardial injury as assessed by methods used in the present study.