Volatile anesthetic preconditioning modulates oxidative stress and nitric oxide in patients undergoing coronary artery bypass grafting.

Background: Myocardial preconditioning using volatile anesthetics such as isoflurane and sevoflurane have beneficial effects in decreasing morbidity in cardiac surgical patients. Studies in animal models have indicated that reactive oxygen and nitrogen species probably play a role in mediating these effects. However, data from human studies are scarce and the differential effect of sevoflurane vs. isoflurane on reactive oxygen species (ROS) and reactive nitrogen species (RNS) has not been studied extensively. Materials and Methods: Randomized clinical control trial comparing preconditioning effects of volatile agents isoflurane and sevoflurane when administered during coronary artery bypass surgeries on cardiopulmonary bypass (CPB). Serum samples were collected at 3 time points before induction, after cross clamp release and one hour after separation from CPB. Levels of oxidative stress markers and nitric oxide were analyzed in these samples. Results: Hemodynamic indices, cardio-pulmonary bypass duration, and ICU stay were similar between the groups. CKMB values 12 hours post-op were decreased in majority of patients in the sevoflurane group compared to isoflurane. Serum malondialdehyde and nitrate levels were lower with sevoflurane (P < 0.05) when compared to the isoflurane group, but no significant differences in protein carbonyl content or protein thiol content were evident between the 2 groups. Sevoflurane also prevented the decrease in total thiols during later stages of surgery. Conclusions: Volatile anesthetics, isoflurane and sevoflurane modulate oxidative and nitrosative stress during CABG. Between the two pre-conditioning agents, isoflurane seems to provide better protection during the pre-bypass period, while sevoflurane provides protection during both pre- as well as post-bypass period.

Fatty acids influence binding of cobalt to serum albumin in patients with fatty liver.

Human serum albumin binds ligands such as fatty acids and metals in circulation. Oxidative stress can modify albumin and affect ligand binding. This study examines the role of oxidative stress and fatty acids in modulating cobalt binding to albumin in patients with fatty liver. Elevated levels of malondialdehyde and protein carbonyls, indicative of oxidative stress were evident in serum of patients with fatty liver. A significant decrease in albumin-cobalt binding was also observed. Albumin isolated from patient serum also showed an increase in bound fatty acids. In vitro experiments indicated that while oxidant exposure or removal of fatty acids independently decreased cobalt binding to albumin, removal of fatty acids from the protein prior to oxidant exposure did not influence the oxidant effect on albumin-cobalt binding. These results suggest that oxidative stress and fatty acids on albumin can influence albumin-cobalt binding in patients with fatty liver by independent mechanisms.

Retinoid metabolism in the small intestine during development of liver cirrhosis.

BACKGROUND AND AIMS: Retinoids are important mediators of cellular differentiation and proliferation in various epithelia of the body including the small intestine. Though alterations in intestinal epithelial cell proliferation have been noted in liver cirrhosis, mechanisms involved in the process are not well understood. This study examined the levels of various retinoids and retinoid-metabolizing enzymes in the small intestine during development of liver cirrhosis. METHODS: Four groups of animals were used (control, phenobarbitone control, thioacetamide and carbon tetrachloride treatment). Twice-weekly intragastric or i.p. administration of carbon tetrachloride or thioacetamide, respectively, produced liver cirrhosis after 3 months, which was confirmed through histology and serum markers. Retinoid levels were measured by high-performance liquid chromatography. RESULTS: A decrease in the levels of retinal, retinoic acid and retinol was evident in the intestine by 3 months, when cirrhosis was evident histologically, and these remained low until 6 months. A decrease in the activities of retinaldehyde oxidase, retinaldehyde reductase and retinol dehydrogenase was also seen in intestine from cirrhotic rats. CONCLUSION: These results suggest that altered retinoid metabolism in the intestine of cirrhotic rats might have an influence on changes in intestinal epithelial cell differentiation, seen in liver cirrhosis.

Role of Oxygen Free Radicals, Nitric Oxide and Mitochondria in Mediating Cardiac Alterations During Liver Cirrhosis Induced by Thioacetamide.

Thioacetamide (TAA) administration is widely used for induction of liver cirrhosis in rats, where reactive oxygen radicals (ROS) and nitric oxide (NO) participate in development of liver damage. Cardiac dysfunction is an important complication of liver cirrhosis, but the role of ROS or NO in cardiac abnormalities during liver cirrhosis is not well understood. This was investigated in animals after TAA-induced liver cirrhosis and temporal changes in oxidative stress, NO and mitochondrial function in the heart evaluated. TAA induced elevation in cardiac levels of nitrate before development of frank liver cirrhosis, without gross histological alterations. This was accompanied by an early induction of P38 MAP kinase, which is influenced by ROS and plays an important signaling role for induction of iNOS. Increased nitrotyrosine, protein oxidation and lipid peroxidation in the heart and cardiac mitochondria, suggestive of oxidative stress, also preceded frank liver cirrhosis. However, compromised cardiac mitochondrial function with a decrease in respiratory control ratio and increased mitochondrial swelling was seen later, when cirrhosis was evident. In conclusion, TAA induces elevations in ROS and NO in the heart in parallel to early liver damage. This leads to later development of functional deficits in cardiac mitochondria after development of liver cirrhosis.

Plasma von Willebrand factor levels predict in-hospital survival in patients with acute-on-chronic liver failure.

BACKGROUND AND AIMS: Circulating levels of von Willebrand factor (vWF) predict mortality in patients with cirrhosis. We hypothesized that systemic inflammation in acute-on-chronic liver failure (ACLF) will stimulate endothelium, increase vWF levels, and promote platelet microthrombi causing organ failure. METHODS: In this prospective study, we correlated plasma vWF levels with organ failure, liver disease severity, sepsis, and systemic inflammatory response syndrome (SIRS) and also analyzed if vWF levels predicted in-hospital composite poor outcome (i.e. death/discharged in terminal condition/liver transplantation) in consecutive ACLF patients. RESULTS: Twenty-one of the 50 ACLF patients studied had composite poor outcome. ACLF patients had markedly elevated vWF antigen and activity (sevenfold and fivefold median increase, respectively) on days 1 and 3. Median ratio of vWF to a disintegrin and metalloprotease with thrombospondin type 1 motif, member 13 (ADAMTS13) activity on day 1 was significantly higher in ACLF patients (11.2) compared to 20 compensated cirrhosis patients (3.3) and healthy volunteers (0.9). On day 1, area under ROC curve (AUROC) to predict composite poor outcome of hospital stay for ACLF patients for vWF antigen, vWF activity, and model for end-stage liver disease (MELD) score were 0.63, 0.68, and 0.74, respectively. vWF activity correlated better with liver disease severity (MELD score, ACLF grade) and organ failure (Sequential Organ Failure Assessment [SOFA] score) than vWF antigen; in contrast, neither vWF antigen nor activity correlated with platelet count, sepsis, or SIRS. CONCLUSIONS: vWF levels are markedly elevated, correlate with organ failure, and predict in-hospital survival in ACLF patients. This data provides a mechanistic basis for postulating that vWF-reducing treatments such as plasma exchange may benefit ACLF patients.

Arsenicosis, possibly from contaminated groundwater, associated with noncirrhotic intrahepatic portal hypertension.

BACKGROUND AND AIMS: Idiopathic noncirrhotic intrahepatic portal hypertension (NCIPH), a chronic microangiopathy of the liver caused by arsenicosis from use of contaminated groundwater, was reported from Asia. This study aimed to see, if in the twenty-first century, arsenicosis was present in NCIPH patients at our hospital and, if present, to look for groundwater contamination by arsenic in their residential locality. METHODS: Twenty-seven liver biopsy proven NCIPH patients, 25 portal hypertensive controls with hepatitis B or C related cirrhosis and 25 healthy controls, matched for residential locality, were studied. Eighty-four percent to 96 % of study subjects belonged to middle or lower socioeconomic category. Arsenicosis was looked for by estimation of arsenic levels in finger/toe nails and by skin examination. Arsenic levels in nails and in ground water (in NCIPH patients with arsenicosis) was estimated by mass spectrometry. RESULTS: Nail arsenic levels were raised in five (10 %) portal hypertensive study subjects [two NCIPH patients (both had skin arsenicosis) and three portal hypertensive controls]. All of these five patients were residents of West Bengal or Bangladesh. Skin arsenicosis was noted in three NCIPH patients (11 %) compared to none of disease/healthy controls. Ground water from residential locality of one NCIPH patient with arsenicosis (from Bangladesh) showed extremely high level of arsenic (79.5 µg/L). CONCLUSIONS: Arsenicosis and microangiopathy of liver, possibly caused by environmental contamination continues in parts of Asia. Further studies are needed to understand the mechanisms of such 'poverty-linked thrombophilia'.

Role of Oxidative and Nitrosative Stress in Pathophysiology of Toxic Epidermal Necrolysis and Stevens Johnson Syndrome-A Pilot Study.

BACKGROUND: Oxidative and nitrosative stress caused by drug metabolism may be a trigger for keratinocyte apoptosis in the epidermis seen in toxic epidermal necrolysis (TEN) and Stevens Johnson syndrome (SJS). AIMS: To estimate oxidative damage in the serum and to examine the role of nitric oxide in mediating epidermal damage in patients with TEN and SJS. MATERIALS AND METHODS: A prospective study was conducted among TEN and SJS patients and controls in a tertiary care center between January 2006 and February 2010. Patients with a maculopapular drug rash without detachment of skin constituted the control group 1 (drug exposed). Patients without a drug rash constituted the control group 2 (drug unexposed). The serum values of protein carbonyls, malondialdehyde, conjugated diene and nitrates were measured. Two-group comparison with the non-parametric Mann-Whitney U test was used. Significance of differences if any was established using Pearson's Chi-square test. RESULTS: Ten patients in the SJS-TEN group (study group), 8 patients in control group 1 and 7 patients in control group 2 were included. More than one drug was implicated in 4/10 patients in group 1 and 3/8 patients in group 2. SCORTEN of 0, 1 and 3 at admission were seen in 2, 6 and 2 patients, respectively. The serum values of protein carbonyls, malondialdehyde, conjugated diene and nitrates were not significantly increased in the study group when compared to the controls. CONCLUSIONS: There was no elevation of oxidative stress markers in patients with TEN and SJS as compared to the control population.

Low dose aspirin prevents duodenoesophageal reflux induced mucosal changes in wistar rat esophagus by MAP kinase mediated pathways.

BACKGROUND: Investigations of molecular mechanisms behind the progression of neoplastic changes in the esophagus have uncovered the role of the COX & 5-Lox pathways. Human squamous esophageal mucosa produces relatively large amounts of eicosanoids in the presence of inflammation. Laboratory and epidemiological data suggest that aspirin and non-steroidal anti-inflammatory drugs may be chemo preventive through their inhibitory effect on COX25, 10. Cell culture studies have shown that the members of the mitogen activated protein (MAP) kinase family plays an important role in the development of bile acid-induced carcinogenesis. Differences in MAPK pathways activated by bile exposure were also noted in esophageal squamous cell lines and biopsies from patients with GERD. The protective role of aspirin and its molecular mechanism is not well understood. AIMS: 1. The effect of duodenal reflux on esophageal mucosa. 2. The role of aspirin in preventing duodenal reflux induced esophageal mucosa changes. 3. If it is proven to be preventive, the mechanism of its action. A duodenal reflux rat animal model was used by an end- to-side esophago duodenostomy. METHODS: Total of 56 rats was included. 3 were "Naive control" animals which did not undergo the surgical procedure. The remaining animals were divided into two groups: Surgery alone (experimental) and Surgery + aspirin [therapy group], esophagoduodenostomy. At 40 weeks, the rats were euthanized and appropriate esophageal samples were analysed for histopathology and p38 & ERK MAP kinases, VEGF, protease activity and caspase 3 activities. RESULTS: The presence of gross mucosal nodularity was seen in 21 and 10 rats of the experimental and therapy group respectively (p = 0.03; Table 1). Reflux-associated changes such as basal cell hyperplasia were more common in the experimental group, however this association did not reach statistical significance (p = 0.15; Table 1). Epithelial hyperplasia was seen more in the experimental group, which was prevented by aspirin [p < 0.01]. Papillomatosis, as shown in Fig. 4 was more common in the experimental group (p = 0.02). Activation of p38 & ERK MAP kinases was prevented in aspirin group (p < 0.05, CI -1.796--0.014). Examination of protease activity by zymographic analysis of the esophageal samples revealed a number of gelatinolytic bands in 50% rats of the experimental group, not observed in the therapy group. No significant changes were seen in Caspase 3 [Normal areas -99.74 & nodular areas - 100.34 percent of controls] or VEGF [mean 0.64, sd ± 0.76 Vs 0.69 ± 0.96] activity. CONCLUSIONS: Our data demonstrated that low dose aspirin reduced the incidence of duodenoesophageal reflux induced histological changes in the esophagus by preventing activation of proliferative & anti-apoptotic MAP kinases such as p38 & ER as well as protease activity. Though Barretts' changes and adenocarcinoma have not developed, it could explain the role of duodenoesophageal reflux in the development of different histological but potential premalignant lesions and molecular level changes which are prevented by low dose aspirin.