Plasma oxidative parameters and mortality in patients with severe burn injury

Troxerutin attenuates inflammatory response in lipopolysaccharide-induced sepsis in mice

Troxerutin (Tx), known as vitamin P₄ is a derivative of natural bioflavonoid rutin. Tx possesses different biological activities such as antioxidant, anticancer, and anti-inflammatory. The current study was conducted to determine potential therapeutic effect of Tx in lipopolysaccharides (LPS)-induced sepsis in mice. In LPS-induced sepsis, the mice were treated intraperitoneally (ip) with Tx twice daily. Therapeutic effect was assessed by measuring serum level of cytokines, alanine aminotransferase (ALT) and lactate dehydrogenase (LDH). Level of nitric oxide (NO), superoxide dismutase (SOD), catalase (CAT), Myeloperoxidase (MPO) and Malondialdehyde (MDA) was measured. Expression of CD40 receptor on leucocytes was measured using flowcytometry. Splenocyte proliferation was evaluated using MTT assay. The effect of Tx on survival rate during administration of lethal dose of LPS was investigated. The results showed that Tx inhibited LPS induced NO production. Inflammatory pathways were suppressed by reduction of inflammatory cytokines production. Further, elevated CD40 expression of leucocytes and proliferation of splenocytes markedly reduced in Tx treated group. Antioxidant defense system was enhanced by increased activity of SOD and CAT and decreased level of MDA. MPO, ALT and LDH activity. Additionally, treatment with Tx significantly increased the mean survival time of mice compared with the LPS treated group. Histologically, Tx treatment decreased inflammatory cells infiltration and histopathologicl changes in the liver. Our findings showed that reduced inflammatory parameters, improved antioxidant activity, reduced histological lesions and increased survival rate. These findings suggest that Tx is an effective anti-inflammatory agent for the treatment of LPS-induced sepsis.

Changes of para-, meta- and ortho-tyrosine over time in burned patients

PURPOSE

Serious burn injury leads to oxidative stress resulting in production of meta- and ortho-tyrosine, while para-tyrosine is the physiological isoform. Our aim was to investigate the metabolism of these tyrosine isoforms following major burn injury.

METHODS

Fifteen patients requiring intensive care were followed for 5 consecutive days after major burn injury. Serum and urine concentrations of para-, meta-, and ortho-tyrosine were measured with high performance liquid chromatography. Fifteen healthy matching individuals were invited as control group.

RESULTS

Median serum concentration of normal isoform para-tyrosine decreased in burned patients between days 2 and 5 (p < 0.01). Mean meta-, and ortho-tyrosine levels were significantly higher in patients compared to controls in the same time period (p < 0.05). Renal excretion of para-tyrosine increased significantly in our observation period (p < 0.01).

CONCLUSIONS

Pathologic isoforms of tyrosine accumulate in serum meanwhile the level of normal isoform decreases possibly due to belated enhanced renal excretion or, to decreased synthesis after major burn injury.

Beef, Casein, and Soy Proteins Differentially Affect Lipid Metabolism, Triglycerides Accumulation and Gut Microbiota of High-Fat Diet-Fed C57BL/6J Mice

Consumption of dietary protein at recommended levels is considered a potential strategy to promote satiety and weight management, but how protein from different dietary sources effect the obesity development, lipid metabolism, and gut microbiota is not known. This study focused on the effects of beef, casein, and soy protein diet on lipid metabolism, triglycerides accumulation, and microbial diversity in colon of C57BL/6J mice, which were given either low-fat diets (LFD, 12% Kcal) or high-fat diets (HFD, 60% Kcal) for 12 weeks. Body and liver weight increased significantly in mice fed a beef protein HFD (HFB), whereas reduced cumulative energy intake was seen in a soy protein HFD (HFS) group. HFB-fed mice showed signs of impaired glucose metabolism and insulin resistance along with a significant elevation in the concentration of triglycerides, LDL-cholesterol, total cholesterol, IL1β, TNF-α, IL-6, and leptin in serum. HFB also enhanced lipid accumulation in liver with increased activity of genes important for lipogenesis and hepatic cholesterol metabolism. A 16S rRNA gene sequencing indicated that HFD, regardless of proteins, significantly enhanced the ratio of Firmicutes to Bacteroidetes in colonic microbiota. However, HFB not only reduced the abundance of Akkermansia, compared with LFD independent of proteins, but also decreased the abundance of butyrate-producing bacteria such as Anaerotruncus, Butyricicoccus, and Lactobacillus (P < 0.05) compared with HFS and HFC. In conclusion, consumption of HFB does not only affect the gut microbiota composition but also increases the problems related to metabolic syndromes like dyslipidemia, hypercholesterolemia, and triglycerides accumulation in liver, which lead to systemic inflammation and its associated comorbidities, for example, impaired glucose metabolism and insulin resistance.

Nrf2 plays a pivotal role in protection against burn trauma-induced intestinal injury and death

Nuclear factor (erythroid-derived 2)-like 2 (NRF2) is a basic leucine zipper transcription factor that principally defends against oxidative stress and also plays a unique role in severe sepsis. However, its contribution to intestinal injury and death after burn trauma is unclear.In this study, wild-type (Nrf2+/+) and Nrf2-deficient (Nrf2-/-) mice were subjected to 15% or 30% total body surface area burn or sham injury. Survival, systemic inflammation, and gut injury were determined.Nrf2-/- mice were more susceptible to burn-induced intestinal injury, as characterized by increases in damage to the gut structure and in intestinal permeability. This exacerbation was associated with an increase in the intestinal mRNA expression of inflammatory cytokines (interleukin [IL]-6, IL-1B, monocyte chemotactic protein 1, intercellular adhesion molecule, and vascular cell adhesion molecule) and a decrease in the intestinal mRNA expression of Nrf2-regulated genes (NAD(P)H dehydrogenasequinine-1 and glutamate-cysteine ligase modifier subunit). Nrf2-deficient mice also showed a lower survival rate and higher levels of systemic cytokines (IL-6 and IL-1B) and high-mobility group protein B1 than wild-type mice. This study demonstrates for the first time that mice that lack Nrf2 are more susceptible to burn-induced intestinal injury and have more systemic inflammation and a lower survival rate.

Assessment of biochemical and antioxidative status in patients suffering from dengue fever

A multi-centred study was designed to collect dengue epidemiologic data from government and registered private hospitals/clinics and maintained archive of frozen specimens in bio-bank to be used for future dengue epidemic control program, and assess the epidemiology of dengue fever (DF) by evaluating biochemical and oxidative status of patients. ELISA IgM antibodies test was done to confirm DF. From August 2010 to December 2011, 101 confirmed blood samples of DF patients referred to pathology lab of Jinnah Hospital Lahore were subjected to the epidemiologic assessment by evaluating the biochemical and physiological indices and alterations of circulating antioxidants. Clinical features of DF patients and effect of fever on blood components and serum proteins of liver were recorded. The hospital stay in DF, dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS) showed significant difference. Significant increases in serum alanine amino transferase (ALT) (P=0.000), aspartate amino transferase (AST) (P=0.000), alkaline phosphatase (ALP) (P=0.000), malondialdehyde (MDA) along with significant decreases in total protein (TP) (P=0.000), reduced glutathione (GSH) (P=0.000), superoxide dismutase (SOD), catalase (CAT) (P=0.000), and sialic acid contents (P=0.016) were observed. A positive correlation existed between bound sialic acid levels, liver enzymes and circulating antioxidants (r=0.656, P=0.016). In the present study, alterations of circulating antioxidants in DF suggest that DF might be a metabolic response to an acute, self-limiting tropical viral infection, and a consequence of the viral inflammatory process.

Biphasic changes (overreduction and overoxidation) of plasma redox status and clinical implications in early stage of severe burns

PURPOSE

Although the changes of redox status in the early stage of severe burns are considered to be associated with the disease progression, whereas antioxidant therapy cannot improve the prognosis, the characteristics and mechanisms of dynamic change of redox status related with the disease progression deserve further study.

METHODS

Blood redox potential (ORP) values (ΔORP value was adopted), plasma uric acid (UA) levels, and the inflammation-related indicators of 67 burn patients were dynamically monitored in the early stage.

RESULTS

Compared with healthy persons, the results revealed the biphasic changes of redox status in the early stage after burns, and both of them were closely related to the prognosis of severe burns. Overreduction status and overoxidation status were related to the dynamic changes of plasma UA level and the inflammation-related indicators of severe burns. In addition, the change of ΔORP value was found to associate with the traditional prognostic markers.

CONCLUSIONS

This study firstly revealed the excessive, biphasic changes of redox status and clinical implications in the early stage of severe burns, providing a new viewpoint for early pathological changes of severe burns and will be helpful for corresponding early treatment. ΔORP value also appears to be a potential early prognostic marker.

The anti-oxidative, anti-inflammatory, and protective effect of S100A8 in endotoxemic mice

Polymorphonuclear neutrophils (PMNs) produce and release copious amounts of reactive oxygen species (ROS) which target potential bacterial invaders but also contribute to the inflammation-associated organ injuries seen in sepsis. Calprotectin is an immune regulatory protein complex made of S100A8 and S100A9 that inhibits the oxidative metabolism of PMNs in vitro, an effect that can be potentiated by the controlled activation of the protease activated receptor-2 (PAR2). The aim of this study was to test the use of a dual strategy of calprotectin and PAR2 administration to mitigate the deleterious inflammation seen in sepsis. We hypothesized that exogenous calprotectin would protect against the injuries produced by lipopolysaccharides (LPS)-induced endotoxemia and that the controlled activation of PAR2 would potentiate this beneficial effect. Exogenous S100A8 and/or a PAR2 activating peptide (PAR2 AP) were administered in a mouse model of LPS induced endotoxemia. The survival rates as well as markers of inflammation and oxidative damage were measured in the lungs, kidneys, and livers of endotoxemic mice. Mice treated with S100A8 following LPS had less PMN infiltration and less severe histological changes in their lungs, kidneys, and livers. A significantly lower score of oxidative damage in the livers and lungs of S100A8/LPS treated mice was also noted when compared to mice treated with LPS alone. This protective and anti-inflammatory effect of S100A8 was potentiated by the controlled activation of PAR2. Finally, in further support to our hypothesis, the survival rate was almost doubled from 33% to 65% and 63% in mice treated by, respectively, S100A8 and PAR2 AP, whereas 85% of the mice treated with both PAR2 AP and S100A8 survived, a statistically significant higher rate. These results support an anti-inflammatory, anti-oxidative, and protective effect of S100A8 in sepsis, and warrant further studies on the role of PAR2.

Increased poly(ADP-ribosyl)ation in skeletal muscle tissue of pediatric patients with severe burn injury: prevention by propranolol treatment

Activation of the nuclear enzyme poly(ADP-ribose) polymerase (PARP) has been shown to promote cellular energetic collapse and cellular necrosis in various forms of critical illness. Most of the evidence implicating the PARP pathway in disease processes is derived from preclinical studies. With respect to PARP and burns, studies in rodent and large animal models of burn injury have demonstrated the activation of PARP in various tissues and the beneficial effect of its pharmacological inhibition. The aims of the current study were to measure the activation of PARP in human skeletal muscle biopsies at various stages of severe pediatric burn injury and to identify the cell types where this activation may occur. Another aim of the study was to test the effect of propranolol (an effective treatment of patients with burns) on the activation of PARP in skeletal muscle biopsies. Poly(ADP-ribose) polymerase activation was measured by Western blotting for its product, poly(ADP-ribose) (PAR). The localization of PARP activation was determined by PAR immunohistochemistry. The results showed that PARP becomes activated in the skeletal muscle tissue after burns, with the peak of the activation occurring in the middle stage of the disease (13-18 days after burns). Even at the late stage of the disease (69-369 days after burn), an elevated degree of PARP activation persisted in some of the patients. Immunohistochemical studies localized the staining of PAR primarily to vascular endothelial cells and occasionally to resident mononuclear cells. There was a marked suppression of PARP activation in the skeletal muscle biopsies of patients who received propranolol treatment. We conclude that human burn injury is associated with the activation of PARP. We hypothesize that this response may contribute to the inflammatory responses and cell dysfunction in burns. Some of the clinical benefit of propranolol in burns may be related to its inhibitory effect on PARP activation.

Role of oxidative tissue injury in the pathophysiology of experimentally induced equine laminitis: a comparison of 2 models

BACKGROUND

Oxidative stress reportedly plays a role in sepsis-induced organ dysfunction and failure in many species. In septic horses, laminae are targeted; evidence of laminar oxidative stress has been reported experimentally in the black walnut extract (BWE) model. Carbohydrate (CHO)-induced laminitis may be more similar to clinical sepsis-related laminitis than the BWE model in that animals with CHO-induced disease commonly develop laminar failure. The role of oxidative stress in the CHO model remains unknown.

HYPOTHESIS/OBJECTIVES

Markers of oxidative stress will be increased in laminae from horses with BWE- and CHO-induced laminitis.

ANIMALS

Banked laminar tissue from various time points from animals subjected to BWE (n = 15) and CHO (n = 20) protocols.

METHODS

Laminar 4-hydroxynonenal (4-HNE) and protein carbonyl content were evaluated by slot blot analysis. Laminar 3-nitrotyrosine (3-NT) immunohistochemistry was performed.

RESULTS

The number of laminar 3-NT (+) cells was increased at developmental and Obel grade 1 (OG1) time points in the BWE model (versus control [CON]; P= .013) and lower in OG1 tissues than CON in the CHO model (P = .04). No change in 4-HNE content was observed in the CHO model, and no increase in laminar protein carbonyl content was present in either model (P > .05).

CONCLUSIONS AND CLINICAL IMPORTANCE

These results do not support a prominent role for oxidative stress at examined time points in CHO-overload laminitis and support transient oxidative stress in the BWE model. Tissue oxidation does not appear to be a central early pathophysiologic event in CHO-associated laminitis.

Burn serum causes a CD14-dependent mitochondrial damage in primary cardiomyocytes

Studies from animal models suggest that myocardial mitochondrial damage contributes to cardiac dysfunction after burn injury. In this report, we used an ex vivo model of primary cardiomyocyte culture to investigate the mechanisms of burn-induced mitochondrial impairment. Briefly, blood serum was collected from Sprague-Dawley (SD) rats subjected to 40% total body surface area burn and added (10% vol/vol) to primary cardiomyocytes prepared from SD rats. The effect of the burn serum on mitochondrial function and membrane integrity in the myocytes was analyzed. Exposure of myocytes to burn serum doubled the mitochondrial membrane damage measured by two independent assays. This treatment also significantly elevated mitochondrial oxidative stress, indicated by a more than 30% increase in lipid oxidation. Downregulation of mitochondrial antioxidant defense was also evident since the activities of the antioxidant enzymes superoxide dismutase and glutathione peroxidase were reduced by about 30% and 50%, respectively. Burn serum also induced deficiency of mitochondrial metabolism, indicated by a 30% decrease in the activity of cytochrome c oxidase. These mitochondrial dysfunctions appear to be generated by oxidative stress because burn serum induced a significant increase of mitochondrial oxygen species (mtROS) in cardiomyocytes, and pretreatment of cardiomyocytes with the antioxidant N-acetyl-cysteine prevented the mitochondrial damages induced by burn serum. Remarkably, the increase in mtROS was abolished by an antibody-mediated blockade of CD14. Furthermore, burn injury-induced mitochondrial damage in cardiomyocytes was prevented in CD14 knockout mice. Taken together, these data suggested that burn injury produces CD14-dependent mitochondrial damage via oxidative stress in myocardium.

Injury severity and serum amyloid A correlate with plasma oxidation-reduction potential in multi-trauma patients: a retrospective analysis

Background

In critical injury, the occurrence of increased oxidative stress or a reduced antioxidant status has been observed. The purpose of this study was to correlate the degree of oxidative stress, by measuring the oxidation-reduction potential (ORP) of plasma in the critically injured, with injury severity and serum amyloid A (SAA) levels.

Methods

A total of 140 subjects were included in this retrospective study comprising 3 groups: healthy volunteers (N = 21), mild to moderate trauma (ISS < 16, N = 41), and severe trauma (ISS ≥ 16, N = 78). For the trauma groups, plasma was collected on an almost daily basis during the course of hospitalization. ORP analysis was performed using a microelectrode, and ORP maxima were recorded for the trauma groups. SAA, a sensitive marker of inflammation in critical injury, was measured by liquid chromatography/mass spectrometry.

Results

ORP maxima were reached on day 3 (± 0.4 SEM) and day 5 (± 0.5 SEM) for the ISS < 16 and ISS ≥ 16 groups, respectively. ORP maxima were significantly higher in the ISS < 16 (-14.5 mV ± 2.5 SEM) and ISS ≥ 16 groups (-1.1 mV ± 2.3 SEM) compared to controls (-34.2 mV ± 2.6 SEM). Also, ORP maxima were significantly different between the trauma groups. SAA was significantly elevated in the ISS ≥ 16 group on the ORP maxima day compared to controls and the ISS < 16 group.

Conclusion

The results suggest the presence of an oxidative environment in the plasma of the critically injured as measured by ORP. More importantly, ORP can differentiate the degree of oxidative stress based on the severity of the trauma and degree of inflammation.

[Hypovolemia and oxidative stress in patients with burn injuries]

Adequate treatment of the developing hypovolemia caused by marked oedema formation plays a key role in the care of burned patients. Oxidative stress may be an underlying cause of the excessive oedema formation. The aim of the study was to asses how can different resuscitation schemata be adapted better to the requirement of each individual patient. Effect of the use of different schemata on organ-function and developing oxidative stress and correlation between the extent of burn and oxidative stress has also been studied.

METHODS

Patients admitted to our level one intensive ward were involved in the study. Inclusion criterion was the start of our fluid resuscitation schema at least 3 hours after injury. Hemodynamic measurements were performed by transpulmonary thermodilution technique. Blood samples were taken on admission and on the 5 consecutive days thereafter. White blood cell count of the patients, the percentage of granulocytes, lymphocytes and monocytes, the levels of malondialdehyde, protein sulfhydryl groups in plasma, reduced glutathione, catalase, and superoxide dismutase enzyme activities, and phorbol myristate acetate induced free radical generating capacity were assessed.

RESULTS

Significantly more fluid was administered than predicted by the Parkland formula (p < 0.05). Patients in whom fluid resuscitation was guided by invasive hemodynamic parameters ScvO 2 was significantly higher (p < 0.05), multi organ dysfunction scores were lower (p < 0.05) than in the hourly urine output group. Patients whom fluid resuscitation was guided by invasive hemodynamic parameters relative number of the granulocytes and maximal rate of reactive oxygen species production (p < 0.05) were significantly higher (p < 0.05), the lag phases were significantly shorter (p < 0.05).

CONCLUSIONS

With the use of correction factors the Parkland formula can be more precise, still, fluid resuscitation guided by invasive hemodynamic measurements can provide the best results. The type of fluid resuscitation schema influences mainly the pro-oxidant system.

Nutritional therapy for burns in children and adults

Burns are a serious injury that requires optimal nutritional support. This review discusses the nutritional care for adults and children with major burns. A burned patient's metabolism is greatly accelerated with increased requirements for energy, carbohydrates, proteins, fats, vitamins, minerals, and antioxidants. Early nutrition by parenteral and enteral feedings is vital. Careful assessment of the nutritional state of the burn patient is also important to reduce infection, recovery time, and long-term sequelae.

Burn-induced oxidative stress is altered by a low zinc status: kinetic study in burned rats fed a low zinc diet

As an initial subdeficient status of zinc, considered as an essential antioxidant trace element, is frequent in burned patients, we aim to assess the effects of low zinc dietary intakes on burn-induced oxidative stress, in an animal model. After 8 weeks of conditioning diets containing 80 ppm (control group) or 10 ppm of zinc (depleted group), Wistar rats were 20% TBSA burned and sampled 1-10 days after injury. Kinetic evolutions of zinc status, plasma oxidative stress parameters, and antioxidant enzymes were also studied in blood and organs. The zinc-depleted diet induced, before injury, a significant decrease in zinc bone level and the increase of oxidative stress markers without stimulation of antioxidant enzyme activity. After burn, more markedly in zinc depleted animals than in controls, zinc levels decreased in plasma and bone, while increasing in liver. The decrease of thiol groups and GSH/GSSG ratio and the depression of GPx activity in liver are also moderately emphasized. Nevertheless, depleted zinc status could not be considered as determining for oxidative damages after burn injury. Further investigations must also be done to enlighten the mechanism of beneficial effects of zinc supplementation reported in burned patients.

Xanthine oxidase activity in patients with sepsis

OBJECTIVE

Determine the relation of xanthine oxidase (XO) activity and the outcome of septic patients and its relation to oxidative damage and clinical parameters of sepsis severity.

DESIGN AND METHODS

Patients admitted over a 6-month period were enrolled. Patients were assigned to groups according to the diagnosis of sepsis (n=8), severe sepsis (n=28) or septic shock (n=36). Blood samples were collected to the determination of thiobarbituric acid reactive species (TBARS), protein carbonyls and XO activity.

RESULTS

None of the studied oxidative parameters determined at the time of diagnosis were related to sepsis severity. XO activity, but not oxidative damage parameters, at the time of sepsis diagnosis was significantly higher in non-survival septic patients. In contrast, 24 h after sepsis diagnosis, XO activity was lower in non-survivors septic patients.

CONCLUSIONS

XO activity was increased in non-survivors patients and the variations in XO activity could be used for outcome prediction.

Oxidative stress induced changes in plasma protein can be a predictor of imminent severe dengue infection

OBJECTIVES

Oxidative stress in dengue viral infection has been suggested and severity of it was found to be associated with progress of illness. Hence assessing oxidative stress mediated changes in plasma proteins can be an early biomarker for prediction of severe dengue infection.

DESIGN AND METHODS

Thirty two dengue hemorrhagic fever (DHF), 21 dengue shock syndrome (DSS), 27 dengue fever (DF) and 63 age and sex matched controls, were included in this study. Blood samples were collected on the 3rd day of fever. Protein carbonylation (PCOs) and protein-bound sulphydryl (PBSH) group levels were determined by spectrophotometric method and analyzed as predictor of dengue hemorrhagic fever and dengue shock syndrome.

RESULTS

About 80-84% of cases presented with no signs of DHF/DSS at the time of sampling. Dengue infected individuals had significantly elevated PCOs and low PBSH group levels than the controls. Using one-way ANOVA we found a significant difference with high PCOs and low PBSH group levels between DHF and DSS when compared with DF (P<0.001). However, no difference was observed in PBSH group levels between DHF and DSS. A significant difference in PCOs to PBSH ratio was observed among DF, DHF and DSS (P<0.001). Linear regression analysis revealed that duration of hospitalization is dependent on PCOs and PBSH group levels. Receiver operator curve (ROC) analysis indicated that 5.22nmol/mg protein PCOs; 1.08 PCOs to PBSH group levels ratio were optimal cutoff value for predicting DHF with sensitivity and specificity of 87.5% and 74.1%; 96.9% and 81.5%, respectively. For DSS prediction, 6.13 nmol/mg protein PCOs; 1.16 PCOs to PBSH group levels ratio were found as effective cutoff with sensitivity and specificity of 81% and 71.9%; 95.2% and 56.2%, respectively.

CONCLUSION

Oxidative stress has been observed to develop since early days of onset of dengue infection. Plasma PCOs, PCOs to PBSH group ratio were found to very well predict DHF/DSS.

Evidence of altered cortisol metabolism in critically ill patients: a prospective study

CONTEXT

Changes in cortisol metabolism due to altered activity of the enzyme 11beta-hydroxysteroid dehydrogenase (11beta-HSD) have been implicated in the pathogenesis of hypertension, obesity and the metabolic syndrome. No published data exist on the activity of this enzyme in critical illness.

OBJECTIVE

To investigate cortisol metabolism in critically ill patients utilising plasma cortisol: cortisone ratio as an index of 11beta-HSD activity.

SETTING

Tertiary level intensive care unit.

PATIENTS

Three cohorts of critically ill patients: sepsis (n = 13); multitrauma (n = 20); and burns (n = 19).

MAIN OUTCOME MEASURES

Serial plasma cortisol: cortisone ratios.

MEASUREMENTS AND MAIN RESULTS

Plasma total cortisol cortisone ratios were determined serially after admission to the intensive care unit. As compared with controls, the plasma cortisol:cortisone ratio was significantly elevated in the sepsis and trauma cohorts on day 1 (22 +/- 9, p = 0.01, and 23 +/- 19, p = 0.0003, respectively) and remained elevated over the study period. Such a relationship was not demonstrable in burns. The ratio was significantly correlated with APACHE II (r = 0.77, p = 0.0008) and Simplified Acute Physiology Score (r = 0.7, p = 0.003) only on day 7 and only in the burns cohort. There were no significant correlations observed between total plasma cortisol or cortisone and sickness severity in the sepsis and trauma cohorts.

CONCLUSIONS

In critically ill patients, there is evidence of altered cortisol metabolism due to an increase in 11beta-HSD activity as demonstrated by an elevation of plasma cortisol: cortisone ratios. Further studies with larger sample sizes specifically designed to examine altered tissue 11beta-HSD activity and its clinical significance and correlation with outcome are warranted.

Cardiac mitochondrial damage and loss of ROS defense after burn injury: the beneficial effects of antioxidant therapy

Mechanisms of burn-related cardiac dysfunction may involve defects in mitochondria. This study determined 1) whether burn injury alters myocardial mitochondrial integrity and function; and 2) whether an antioxidant vitamin therapy prevented changes in cardiac mitochondrial function after burn. Sprague-Dawley rats were given a 3 degrees burn over 40% total body surface area and fluid resuscitated. Antioxidant vitamins or vehicle were given to sham and burn rats. Mitochondrial and cytosolic fractions were prepared from heart tissues at several times postburn. In mitochondria, lipid peroxidation was measured to assess oxidative stress, mitochondrial outer membrane damage and cytochrome-c translocation were determined to estimate mitochondrial integrity, and activities of SOD and glutathione peroxidase were examined to evaluate mitochondrial antioxidant defense. Cardiac function was measured by Langendorff model in sham and burn rats given either vitamins or vehicle. Twenty-four hours postburn, mitochondrial outer membrane damage was progressively increased to approximately 50%, and cytosolic cytochrome-c gradually accumulated to approximately three times more than that measured in shams, indicating impaired mitochondrial integrity. Maximal decrease of mitochondrial SOD activity occurred 8 h postburn ( approximately 63.5% of shams), whereas maximal decrease in glutathione peroxidase activity persisted 2-24 h postburn ( approximately 60% of shams). In burn animals, lipid peroxidation in cardiac mitochondria increased 30-50%, suggesting burn-induced oxidative stress. Antioxidant vitamin therapy prevented burn-related loss of membrane integrity and antioxidant defense in myocardial mitochondria and prevented cardiac dysfunction. These data suggest that burn-mediated mitochondrial dysfunction and loss of reactive oxygen species defense may play a role in postburn cardiac dysfunction.

The role of oxidative stress in adult critical care

Oxidative stress defines an imbalance in production of oxidizing chemical species and their effective removal by protective antioxidants and scavenger enzymes. Evidence of massive oxidative stress is well established in adult critical illnesses characterized by tissue ischemia-reperfusion injury and by an intense systemic inflammatory response such as during sepsis and acute respiratory distress syndrome. Oxidative stress could exacerbate organ injury and thus overall clinical outcome. We searched MEDLINE databases (January 1966 to June 2005). For interventional studies, we accepted only randomized trials. Several small clinical trials have been performed in order to reduce oxidative stress by supplementation of antioxidants alone or in combination with standard therapies. These studies have reported controversial results. Newer large multicenter trials with antioxidant supplementation should be performed, considering administration at an early stage of illness and a wider population of critically ill patients.

Protective effect of N-acetylcysteine and deferoxamine on carbon tetrachloride-induced acute hepatic failure in rats

OBJECTIVE

Carbon tetrachloride (CCl4) is a lipid-soluble potent hepatotoxic; thus, it widely is used as an animal model of severe hepatic failure. Treatment with antioxidants may modulate the toxic effects of CCl4 on liver, generally with drug administration before CCl4, which can restrict its use in the clinical setting. We here describe the effects of N-acetylcysteine, deferoxamine, or both in the treatment of CCl4-induced hepatic failure.

DESIGN

Prospective, randomized, controlled experiment.

SETTING

Animal basic science laboratory.

SUBJECTS

Male Wistar rats, weighing 200-250 g.

INTERVENTIONS

Rats exposed to CCl4 were treated with N-acetylcysteine and/or deferoxamine or vehicle.

MEASUREMENTS AND MAIN RESULTS

N-acetylcysteine plus deferoxamine treatment significantly attenuated hepatic and central nervous system oxidative damage after acute hepatic failure induced by CCl4. In addition, the serum levels of alanine aminotransferase, total bilirubin, and prothrombin time in the N-acetylcysteine plus deferoxamine group were significantly lower than those in the N-acetylcysteine or deferoxamine and saline groups. After N-acetylcysteine plus deferoxamine treatment, hepatocellular necrosis and inflammatory infiltration induced by carbon tetrachloride were greatly decreased. Survival in untreated rats was 5%. Survival increased to 25% and 35%, respectively, with N-acetylcysteine and deferoxamine treatment. In rats treated with N-acetylcysteine plus deferoxamine, survival was 80%.

CONCLUSIONS

Our data provide the first experimental demonstration that N-acetylcysteine plus deferoxamine reduces mortality rate, decreases oxidative stress, and limits inflammatory infiltration and hepatocyte necrosis induced by CCl4 in the rat.

Phospholipid plasmalogen, a surrogate marker of oxidative stress, is associated with increased cardiovascular mortality in patients on renal replacement therapy

BACKGROUND

There is a high incidence of premature cardiovascular disease (CVD) in patients with end-stage renal disease (ESRD). Free radical-induced tissue damage is thought to play a major role in the pathogenesis of atherosclerosis, and there are several reports indicating an increased oxidative stress in ESRD. However, it is not well established that increased oxidative stress predicts cardiovascular mortality in ESRD. Plasmalogens, a group of phospholipids with a vinyl ether bond in the sn-1 position, are considered to be sensitive markers of oxidative stress.

METHODS

Cardiovascular and non-cardiovascular mortality was recorded (follow-up time 1860+/-94 days) in 105 ESRD patients (mean age 51+/-2 years) in whom the fasting ratio of the erythrocyte levels of plasmalogens (DMA 16/C16:0 and DMA 18/C18:0) had been determined at the start of renal replacement therapy (RRT). The prevalence of malnutrition (subjective global assessment), diabetes mellitus (DM), smoking habits and CVD was also determined.

RESULTS

Thirty-eight patients who died of CVD (0.066+/-0.003) had a significantly lower DMA 16/C16:0 ratio than 15 patients who died of non-cardiovascular causes (0.078+/-0.005; P<0.05) and 52 patients alive at follow-up (0.075+/-0.003; P<0.05). A Cox proportional hazard model analysis showed that a low (<median) DMA 16/C16:0 ratio at the start of RRT was associated (relative risk 1.50; confidence interval 1.07-2.16; P<0.05) with CVD mortality independently of age, gender, DM and CVD.

CONCLUSION

These results suggest that increased oxidative stress may be a risk factor for cardiovascular mortality in ESRD.