Time course of oxidative stress after major burns

Serum Selenium-Binding Protein 1 (SELENBP1) in Burn Injury: A Potential Biomarker of Disease Severity and Clinical Course

Oxidative stress, systemic inflammation, and metabolic derangements are hallmarks of burn pathophysiology. Severely burned patients are highly susceptible to infectious complications. Selenium-binding protein 1 (SELENBP1) modulates intracellular redox homeostasis, and elevated serum concentrations have been associated with adverse clinical outcomes in trauma patients. We hypothesized that serum SELENBP1 at hospital admission and during hospitalization may constitute a meaningful biomarker of disease severity and the clinical course in burn injury, with pulmonary infection as primary endpoint. To this end, we conducted a prospective cohort study that included 90 adult patients admitted to the Burn Center of the University Hospital Zurich, Switzerland. Patients were treated according to the local standard of care, with high-dose selenium supplementation during the first week. Serum SELENBP1 was determined at nine time-points up to six months postburn and the data were correlated to clinical parameters. SELENBP1 was initially elevated and rapidly declined within the first day. Baseline SELENBP1 levels correlated positively with the Abbreviated Burn Severity Index (ABSI) (R = 0.408; p < 0.0001). In multiple logistic regression, a higher ABSI was significantly associated with increased pulmonary infection risk (OR, 14.4; 95% CI, 3.2-88.8; p = 0.001). Similarly, baseline SELENBP1 levels constituted a novel but less accurate predictor of pulmonary infection risk (OR, 2.5; 95% CI, 0.7-8.9; p = 0.164). Further studies are needed to explore the additional value of serum SELENBP1 when stratifying patients with respect to the clinical course following major burns and, potentially, for monitoring therapeutic measures aimed at reducing tissue damage and oxidative stress.

Icy core-shell composite nanofibers with cooling, antibacterial and healing properties for outdoor burns

Burns are usually difficult to treat because their susceptibe to bacterial infections. When burns is accompanied by hyperthermia, the heat accumulated on the skin will causes extensive tissue damage. Most dressings focus on the treatment process, while ignoring the first-aid treatment to remove hyperthermia. To make matters worse, when outdoors, it is hard to find clean water to wash and cool the burned area. A dressing which can simultaneously realize first-time cooling and repairing treatment of the burned area can shorten treatment time, and is especially beneficial for outdoor use. In this study, a handheld coaxial electrospinning device is developed for preparing platelet-rich plasma @Polycaprolactone-epsilon polylysine (PRP@PCL/ε-PL) core-shell nanofibers. The nanofibers can be synchronously transformed into ice fibers during the spinning process, and directly deposited on the skin. The whole process is convenient to use outdoor. Via dual cooling mechanisms, first aid can take away the excessive heat in the burn area by nanofibers. These core-shell nanofibers also show its excellent antimicrobial and tissue regeneration-promoting properties. Therefore, it achieves first-time cooling and repair treatment of the burned area at the same time. Moreover, due to direct in-situ deposition of this handheld coaxial electrospinning, better antimicrobial properties, and faster healing performance are achieved. By using this integrated strategy that combines cooling, antibacterial and healing promotion, the burn recovery time is shortened from 21 days to 14 days.

Cerium(III) Nitrate Containing Electrospun Wound Dressing for Mitigating Burn Severity

Thermal injuries pose a risk for service members in prolonged field care (PFC) situations or to civilians in levels of lower care. Without access to prompt surgical intervention and treatment, potentially salvageable tissues are compromised, resulting in increases in both wound size and depth. Immediate debridement of necrotic tissue enhances survivability and mitigates the risks of burn shock, multiple organ failure, and infection. However, due to the difficulty of surgical removal of the burn eschar in PFC situations and lower levels of care, it is of utmost importance to develop alternative methods for burn stabilization. Studies have indicated that cerium(III) nitrate may be used to prolong the time before surgical intervention is required. The objective of this study was to incorporate cerium(III) nitrate into an electrospun dressing that could provide burst release. Select dosages of cerium(III) nitrate were dissolved with either pure solvent or polyethylene oxide (PEO) for coaxial or traditional electrospinning set-ups, respectively. The solutions were coaxially electrospun onto a rotating mandrel, resulting in a combined nonwoven mesh, and then compared to traditionally spun solutions. Dressings were evaluated for topography, morphology, and porosity using scanning electron microscopy and helium pycnometry. Additionally, cerium(III) loading efficiency, release rates, and cytocompatibility were evaluated in both static and dynamic environments. Imaging showed randomly aligned polymer nanofibers with fiber diameters of 1161 ± 210 nm and 1090 ± 250 nm for traditionally and coaxially spun PEO/cerium(III) nitrate dressings, respectively. Assay results indicated that the electrospun dressings contained cerium(III) nitrate properties, with the coaxially spun dressings containing 33% more cerium(III) nitrate than their traditionally spun counterparts. Finally, release studies revealed that PEO-based dressings released the entirety of their contents within the first hour with no detrimental cytocompatibility effects for coaxially-spun dressings. The study herein shows the successful incorporation of cerium(III) nitrate into an electrospun dressing.

Preparation and characterization of selenium-rich polysaccharide from Phellinus igniarius and its effects on wound healing

The modified of polysaccharides show various bio-activities. In our work, Phellinus igniarius Selenium-enriched mycelias polysaccharides (PSeP) were prepared from Phellinus igniarius, and its antioxidant and anti-inflammatory effects on injured mice were evaluated. The selenium content and physical properties of polysaccharides were characterized by GC, HPGPC, and FT-IR analysis. The results showed that PSeP could reduce reactive oxygen species (ROS) levels, myeloperoxidase (MPO) activity as well as malondialdehyde (MDA) content. Meanwhile, it increased the enzyme activities of glutathione peroxidase (GSH-Px) and catalase (CAT). Finally, it showed obvious wound healing effects in vivo. Moreover, PSeP could clear the ROS without obvious cytotoxicity. PSeP could further improve its ability to clear ROS level to promote skin wound healing in mice three days in advance.

Burn injury induces elevated inflammatory traffic: the role of NF-κB

A burn insult generally sustains a hypovolemic shock due to a significant loss of plasma from the vessels. The burn injury triggers the release of various mediators, such as reactive oxygen species (ROS), cytokines, and inflammatory mediators. Damage-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns (PAMPs), stemming from foreign microbial discharge and damaged tissue or necrotic cells from the burn-injured site, enter the systemic circulation, activate toll-like receptors (TLRs), and trigger the excessive secretion of cytokines and inflammatory mediators. Inflammation plays a vital role in remodeling an injured tissue, detoxifying toxins, and helps in the healing process. A transcription factor, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), contributes to a variety of physiological and pathological conditions, including immune response, cell death, cell survival, and inflammatory processes. During the pathogenesis of a burn wound, upregulation of various cytokines and growth factors lead to undesirable tissue inflammation. Thus, NF-κB, a dominant moderator of inflammation, needs to be altered to prove beneficial to the treatment of burns or other inflammation-associated diseases. This review addresses the relationship between NF-κB and elevated inflammation in a burn condition that could potentially be altered to induce an early wound-healing mechanism of burn wounds.

Advanced Oxidation Protein Product (AOPP) Levels in Second- and Third-Degree Thermal Burns

Burn is a systemic injury affecting the entire organism according to its etiology and severity. The aim of this study was to investigate plasma AOPP levels before and after treatment of second- and third-degree thermal burn patients and determine the changes in this parameter, and also, to find out the relationship between AOPP level and hospitalization period and total body surface area (TBSA). The study material consisted of pediatric patients with the complaint of second- and third-degree thermal burns aged between 1 and 18 years, with a burn area exceeding 10%. Blood samples were taken twice before and after treatment. AOPP level in blood plasma was measured in ELISA. It was observed that in the second-degree thermal burn group, AOPP level was 25.85 ± 2.82 ng/ml before the treatment decreased to 22.16 ± 3.62 ng/ml after treatment, whereas in the third-degree thermal burn group before the treatment AOPP was 25.96 ± 3.49 ng/ml, and after the treatment dropped to 21.70 ± 3.79 ng/ml, decreases were significantly important (P < .05). There was no statistically significant difference between the two groups in terms of AOPP levels (P > .05). Correlation analyses in the second- and third-degree thermal burn group did not show any correlation between AOPP levels and burn area and length of hospitalization period. As a result, AOPP level has been studied, for the first time, in burn cases. In both groups, the level of AOPP increased due to oxidative stress before treatment and decreased after treatment.

Role of Pseudomonas aeruginosa Glutathione Biosynthesis in Lung and Soft Tissue Infection

The opportunistic pathogen Pseudomonas aeruginosa is a leading cause of morbidity and mortality worldwide. To survive in both the environment and the host, P. aeruginosa must cope with redox stress. In P. aeruginosa, a primary mechanism for protection from redox stress is the antioxidant glutathione (GSH). GSH is a low-molecular-weight thiol-containing tripeptide (l-γ-glutamyl-l-cysteinyl-glycine) that can function as a reversible reducing agent. GSH plays an important role in P. aeruginosa physiology and is known to modulate several cellular and social processes that are likely important during infection. However, the role of GSH biosynthesis during mammalian infection is not well understood. In this study, we created a P. aeruginosa mutant defective in GSH biosynthesis to examine how loss of GSH biosynthesis affects P. aeruginosa virulence. We found that GSH is critical for normal growth in vitro and provides protection against hydrogen peroxide, bleach, and ciprofloxacin. We also studied the role of P. aeruginosa GSH biosynthesis in four mouse infection models, including the surgical wound, abscess, burn wound, and acute pneumonia models. We discovered that the GSH biosynthesis mutant was slightly less virulent in the acute pneumonia infection model but was equally virulent in the three other models. This work provides new and complementary data regarding the role of GSH in P. aeruginosa during mammalian infection.

Evaluation of plasma oxidative stress, with or without antioxidant supplementation, in superficial partial thickness burn patients: a pilot study

BACKGROUND

Oxidative stress is one of the main causes of pathophysiological alterations observed during burn injury. The present pilot study aimed to determine whether a specific oral antioxidant supplementation could in any way influence free radical blood values in patients affected by superficial partial thickness burns.

MATERIALS AND METHODS

Plasma oxidants and plasma antioxidant capacity were analysed in 20 superficial partial thickness burn patients for a 2-week period; patients were randomly divided into two groups, one of which was supported with a specifically designed oral antioxidant formula (Squalene 100 mg, Vitamin C 30 mg, Coenzyme Q10 10 mg, Zinc 5 mg, Beta Carotene 3.6 mg, Bioflavonoids 30 mg, Selenium 55 mcg) administered daily, starting from the day of admission, for the whole study period.

RESULTS

No significant differences were found in plasma oxidants and plasma antioxidant capacity between the two groups of patients.

CONCLUSIONS

These results did not reflect any significant benefits of an antioxidant oral supplementation at usual dosages when considering oxidative plasmatic values of superficial partial thickness burn patients.

The characteristics and correlation between the ischemia-reperfusion and changes of redox status in the early stage of severe burns

OBJECTIVE

Both the ischemia-reperfusion injury and the abnormal changes of redox status are the important pathologic changes in the burn shock stage for severe burns. The study of clinical dynamic, quantitative relevance about them was performed.

METHODS

In this study, blood redox potential (ORP) values (ΔORP value was adopted, as the quantitative index to reflect the overall redox status), plasma uric acid levels (important antioxidant, as antioxidant index), and the burn shock state-related indicators (lactic acid and hematocrit) of 48 burn patients were dynamically, quantitatively monitored during the early stage after injury.

RESULTS

The results revealed that the duration of abnormal fluctuation of redox status in the early stage of severe burns was longer than that of the traditional clinical shock stage (2-3 days). The changes of overreduction soon after injury were closely related to the hypovolemia-related hypoxia, and the following overoxidation status was consistent with the pathophysiological changes related to the reperfusion, and the degrees of variation were closely related to the severity of burn injury and prognosis. Moreover, early surgery (3 days after injury) had no significant influence on the changing trend of abnormal redox status in the early stage of severe burns.

CONCLUSION

The ischemia-reperfusion injury caused by burn shock appears the main factor contributing to the abnormal biphasic changes of redox status in the early stage of severe burns. Our findings provide useful information for the redox regulation treatment for burn shock.

Effect of acute thermal injury in status of serum vitamins, inflammatory markers, and oxidative stress markers: preliminary data

The objective of this study was to evaluate the vitamin status, inflammatory markers, and oxidative stress markers in adult patients up to 3 days after thermal injury. This prospective study was conducted with 11 patients 24 to 72 hours after thermal injury (Burn Group), total surface area ranging from 10 to 41%, 34.3 ± 9.3 years, 82% of males, body mass index of 22.3 ± 2.9 kg/m(2). We included 11 healthy adults (Control Group), 36.5 ± 7.6 years, 73% of males, and body mass index of 23.8 ± 2.5 kg/m(2). Laboratory data were measured (plasma total protein, albumin, transferrin, lymphocyte counts, zinc, and iron), as well as serum vitamins (folic acid, vitamin B12, and vitamins A, C, and E), inflammatory stress markers (C-reactive protein, ferritin, and acid α1-glycoprotein) and oxidative stress markers such as glutathione peroxidase (GPx) and thiobarbituric acid reactive substances. The inflammatory stress was characterized by lower levels of total protein (median difference 1.2 g/dL, 95% CI: 0.4-2.1) and albumin (median difference 0.9 g/dL, 95% CI: 0.5-1.5), and higher levels of C-reactive protein (median difference -8.12 mg/dL, 95% CI: -11.62 to 4.61) and α-1 glycoprotein acid (median difference -28.56 mg/dL, 95% CI: -51.57 to -5.07) in burn patients. Decreased serum levels of vitamin A (median difference 1.10 μmol/L, 95% confidence interval [CI]: 0.42-1.66) and vitamin C (median difference 0.82 mg/dL, 95% CI: 0.50-1.04) were also detected. There was no statistical evidence of difference in the serum levels of glutathione peroxidase and thiobarbituric acid reactive substances between burn patients and controls, respectively. Even though there is an inflammatory stress, the obtained data showed that oxidative stress markers are normal 24 to 72 hours after burn injury. The decrease in negative acute phase protein may account for the diminished serum levels of vitamin A, which seems to be related to inflammatory stress. The marked decrease in the serum levels of vitamin C can be justified by augmented cutaneous loss and consumption in the regeneration of vitamin E.

Targeting the redox balance in inflammatory skin conditions

Reactive oxygen species (ROS) can be both beneficial and deleterious. Under normal physiological conditions, ROS production is tightly regulated, and ROS participate in both pathogen defense and cellular signaling. However, insufficient ROS detoxification or ROS overproduction generates oxidative stress, resulting in cellular damage. Oxidative stress has been linked to various inflammatory diseases. Inflammation is an essential response in the protection against injurious insults and thus important at the onset of wound healing. However, hampered resolution of inflammation can result in a chronic, exaggerated response with additional tissue damage. In the pathogenesis of several inflammatory skin conditions, e.g., sunburn and psoriasis, inflammatory-mediated tissue damage is central. The prolonged release of excess ROS in the skin can aggravate inflammatory injury and promote chronic inflammation. The cellular redox balance is therefore tightly regulated by several (enzymatic) antioxidants and pro-oxidants; however, in case of chronic inflammation, the antioxidant system may be depleted, and prolonged oxidative stress occurs. Due to the central role of ROS in inflammatory pathologies, restoring the redox balance forms an innovative therapeutic target in the development of new strategies for treating inflammatory skin conditions. Nevertheless, the clinical use of antioxidant-related therapies is still in its infancy.

Functional late outgrowth endothelial progenitors isolated from peripheral blood of burned patients

BACKGROUND

Bioengineered skin substitutes are increasingly considered as a useful option for the treatment of full thickness burn injury. Their viability following grafting can be enhanced by seeding the skin substitute with late outgrowth endothelial progenitor cells (EPCs). However, it is not known whether autologous EPCs can be obtained from burned patients shortly after injury.

METHODS

Late outgrowth EPCs were isolated from peripheral blood sampled obtained from 10 burned patients (extent 19.6±10.3% TBSA) within the first 24h of hospital admission, and from 7 healthy subjects. Late outgrowth EPCs were phenotyped in vitro.

RESULTS

In comparison with similar cells obtained from healthy subjects, growing colonies from burned patients yielded a higher percentage of EPC clones (46 versus 17%, p=0.013). Furthermore, EPCs from burned patients secreted more vascular endothelial growth factor (VEGF) into the culture medium than did their counterparts from healthy subjects (85.8±56.2 versus 17.6±14pg/mg protein, p=0.018). When injected to athymic nude mice 6h after unilateral ligation of the femoral artery, EPCs from both groups of subjects greatly accelerated the reperfusion of the ischaemic hindlimb and increased the number of vascular smooth muscle cells.

CONCLUSIONS

The present study supports that, in patients with burns of moderate extension, it is feasible to obtain functional autologous late outgrowth EPCs from peripheral blood. These results constitute a strong incentive to pursue approaches based on using autotransplantation of these cells to improve the therapy of full thickness burns.

Lycopene inhibits caspase-3 activity and reduces oxidative organ damage in a rat model of thermal injury

Oxidative stress has been implicated in various pathological processes including burn induced multiple organ damage. This study investigated the effects of lycopene treatment against oxidative injury in rats with thermal trauma. Under ether anesthesia, shaved dorsum of the rats was exposed to 90°C bath for 10s to induce burn and treated either vehicle (olive oil) or lycopene (50mg/kg orally). Rats were decapitated 48 h after injury and the tissue samples from lung and kidney were taken for histological analysis and the determination of malondialdehyde (MDA) and glutathione (GSH) levels, myeloperoxidase (MPO), superoxide dismutase (SOD), catalase (CAT) and caspase-3 activities. Proinflammatory cytokines, TNF-α and IL-1β, were assayed in blood samples. Severe skin scald injury caused a significant decrease in GSH levels, SOD and CAT activities, and significant increases in MDA levels, MPO and caspase-3 activities of tissues. Similarly, plasma TNF-α and IL-1β were elevated in the burn group as compared to the control group. Lycopene treatment reversed all these biochemical indices. According to the findings of the present study, lycopene possesses antiinflammatory, antiapoptotic and antioxidant effects that prevents burn-induced oxidative damage in remote organs.

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.

Oral preoperative antioxidants in pancreatic surgery: a double-blind, randomized, clinical trial

OBJECTIVE

Oxidative stress due to ischemia/reperfusion injury increases systemic inflammation and impairs immune defenses. Much interest has developed for the administration of antioxidant substrates in surgical patients. The purpose of this study was to perform a pilot evaluation of the impact of a carbohydrate- containing preconditioning oral nutritional supplement (pONS) enriched with glutamine, antioxidants, and green tea extract on postoperative oxidative stress.

METHODS

We performed a double-blind placebo-controlled randomized clinical trial, involving 36 cancer patients undergoing pancreaticoduodenectomy. Patients were randomized to receive either pONS or placebo twice the day before surgery and once 3 hours before surgery. Total endogenous antioxidant capacity (TEAC), plasma levels of vitamin C, vitamin E, selenium, zinc, F2-isoprostanes, and C-reactive protein were measured at baseline and on postoperative day (POD) 1, 3, and 7.

RESULTS

At surgery, the mean gastric residual volume (mL) was 54.2 in the pONS group versus 51.3 in the placebo group (P = NS). On POD 1 plasma levels of vitamin C (P = 0.001), selenium (P = 0.07), and zinc (P = 0.06) were higher in the pONS group compared to placebo. TEAC was improved on POD 1, 3, and 7 in the pONS group compared to placebo (P = 0.01). No difference was found in plasma C-reactive protein levels after surgery in both groups.

CONCLUSIONS

Perioperative pONS administration positively affected plasma vitamin C levels and improved TEAC shortly after surgery, but did not reduce oxidative stress and systemic inflammation markers.

Supplementation of vitamin E, vitamin C, and zinc attenuates oxidative stress in burned children: a randomized, double-blind, placebo-controlled pilot study

The aim of this study was to investigate the effect of supplementation of vitamin E, vitamin C, and zinc on the oxidative stress in burned children. In a prospective double-blind placebo controlled pilot study, 32 patients were randomized as no supplementation (n = 15) or antioxidant supplementation (n = 17) groups. Supplementation consisted of the antioxidant mixture of vitamin C (1.5 times upper intake level), vitamin E (1.35 times upper intake level), and zinc (2.0 times recommended dietary allowance) administered during 7 days starting on the second day of admittance into the hospital. Energy requirement was calculated by the Curreri equation, and protein input was 3.0 g/kg of ideal body mass index (percentile 50). Total antioxidant capacity of plasma and malondialdehyde were used to monitor oxidative stress. The time of wound healing was evaluated as the main clinical feature. Patients (age 54.2 +/- 48.9 months, 65.6% males), who exhibited 15.5 +/- 6.7% of total burn area, showed no differences in age and sex, when compared with controls. Intake of the administered antioxidants was obviously higher in treated subjects (P = .005), and serum differences were confirmed for vitamin E and C, but not for zinc (P = .180). There was a decrease in lipid peroxidation (malondialdehyde level) (P = .006) and an increase in vitamin E concentrations in the antioxidant supplementation group (P = .016). The time of wound healing was lower in the supplemented group (P < .001). The antioxidant supplementation through vitamin E and C and the mineral zinc apparently enhanced antioxidant protection against oxidative stress and allowed less time for wound healing.

Burn injury induces the expression of cystine/glutamate transporter (x(c)(-)) in mouse T cells

System x(c)(-) transporter, formed by the association of CD98 and xCT proteins, regulates the import of cystine into cells and is poorly expressed in T lymphocytes. Thermal injury is associated with high oxidative stress, decreased levels of glutathione (GSH) and protein deficiency, all described as promoters of xCT expression and system x(c)(-) activity. T cell dysfunction is a consequence of thermal injury and has been related to oxidative stress. In order to evaluate if thermal injury induced system x(c)(-) expression in splenic T lymphocytes, cells were isolated from sham- and burn-injured mice at day 10 post-burn and cultured in 2-mercaptoethanol (2-ME)-rich and -free media. Isolated splenic T cells were stimulated and cell proliferation, system x(c)(-) expression and cystine transport activity were measured. Our results demonstrate that only burn-injured T cells express xCT and proliferate in (2-ME)-free media. In these cells, viability and CD25 expression was higher than control T cells. x(c)(-) system expression was responsible for significantly higher (14)C-cystine uptake by burn-injured T cells and its inhibition by sulfasalazine (SASP) decreased significantly their proliferation. Overall, these results demonstrate that xCT expression is induced by thermal injury in T lymphocytes and that cystine import by x(c)(-) leads to T cell dysfunction.

Effect of burn injury on apoptosis and expression of apoptosis-related genes/proteins in skeletal muscles of rats

The purpose of this study was to investigate the occurrence and possible mechanisms of apoptosis in skeletal muscles after burn injury. After a 40% body surface area burn to rats, TA muscles were examined for apoptosis at varying times by TEM, TUNEL and cell death ELISA assay. Thermal injury was found to induce apoptosis in skeletal muscle on the first day and maximal apoptosis appeared 4 days post-injury. Apoptotic ligands in serum assessed by ELISA revealed rapidly increase of TNF-alpha and subsequent increase of sFasL to sFas ratio after burn injury. It implied TNF-alpha induced apoptosis in early stage and FasL induced apoptosis in later stage after burn injury. Apoptosis-related genes/proteins in skeletal muscles examined by real-time PCR array and Western blotting showed pro-apoptotic genes/proteins, including Tnfrsf1a, Tnfrsf1b and Tnfsf6 in TNF ligand and receptor family, Bax and Bid in Bcl-2 family, caspase-3 and caspase-6 in caspase family, Dapk1, FADD and Cidea in death and CIDE domain family, Apaf-1 in CARD family, and Gadd45a were up-regulated, while anti-apoptotic gene Bnip1 was down-regulated compared with that of time-matched controls. In addition, increment of caspase-3, caspase-8 and caspase-9 activity provided further evidence for their role in apoptosis in skeletal muscle. Significant increase in expression in pro-apoptotic genes/proteins and activity of caspases suggested that death receptor-mediated signaling pathways and other apoptotic related pathways participated in apoptosis in skeletal muscle after burn injury. However, it was found that some anti-apoptotic genes such as Bcl2l1, Mcl-1, Nol-3, Il-10 and Prok2 were also up-regulated, which might imply the co-existence of protective response of the body after burns. In conclusion, the data suggest that apoptosis and pro-apoptotic signaling are enhanced in muscles of burned rats. To further elucidate the underlying apoptotic mechanisms mediating the atrophic response is important in establishing potential therapeutic interventions that could prevent and/or reduce skeletal muscle wasting and preserve its physiological function.

Oxidative stress and anti-oxidative mobilization in burn injury

A severe burn is associated with release of inflammatory mediators which ultimately cause local and distant pathophysiological effects. Mediators including Reactive Oxygen Species (ROS) and Reactive Nitrogen Species (RNS) are increased in affected tissue, which are implicated in pathophysiological events observed in burn patients. The purpose of this article is to understand the role of oxidative stress in burns, in order to develop therapeutic strategies. All peer-reviewed, original and review articles published in the English language literature relevant to the topic of oxidative stress in burns in animals and human subjects were selected for this review and the possible roles of ROS and RNS in the pathophysiology of burns are discussed. Both increased xanthine oxidase and neutrophil activation appear to be the oxidant sources in burns. Free radicals have been found to have beneficial effects on antimicrobial action and wound healing. However following a burn, there is an enormous production of ROS which is harmful and implicated in inflammation, systemic inflammatory response syndrome, immunosuppression, infection and sepsis, tissue damage and multiple organ failure. Thus clinical response to burn is dependent on the balance between production of free radicals and its detoxification. Supplementation of antioxidants in human and animal models has proven benefit in decreasing distant organ failure suggesting a cause and effect relationship. We conclude that oxidative damage is one of the mechanisms responsible for the local and distant pathophysiological events observed after burn, and therefore anti-oxidant therapy might be beneficial in minimizing injury in burned patients.

Suplementação de antioxidantes: enfoque em queimados

Na queimadura, os radicais livres são produzidos durante a reposição de fluídos, alterando numerosos componentes, como os ácidos nucléicos, os lipídios e as proteínas. Sendo assim, se, por um lado, essa restauração do fluxo sanguíneo é, em geral, necessária para recuperar a função celular normal, por outro lado a reintrodução do sangue oxigenado nos tecidos isquêmicos contribui para uma produção excessiva de radicais livres derivados do oxigênio, exacerbando a lesão mediada pela isquemia. O papel dos neutrófilos ativados na célula após a queimadura também tem recebido atenção especial. A partir do sistema NADPH oxidase os neutrófilos aderidos podem produzir uma explosão de radical superóxido, produzindo um dano tecidual importante. A queimadura, além de aumentar a produção de radicais livres, também é capaz de impedir os mecanismos de defesa antioxidante, submetendo o paciente queimado ao estresse oxidativo, o qual se constitui em fator perpetuante da resposta inflamatória sistêmica, levando à piora progressiva do estado metabólico. Com esses dados, objetiva-se revisar os principais estudos com a suplementação de antioxidantes em pacientes críticos, com ênfase em pacientes queimados, e descrever os possíveis benefícios dessa intervenção.

Antioxidant therapy in critical care—Is the microcirculation the primary target?

This review presents the rationale for the therapeutic use of antioxidants in treating critically ill patients; it is not a systematic review of the clinical evidence that has been assessed recently by others. Clinical and nonclinical evidence is presented to support the notion that natural antioxidants are of therapeutic value in treating cardiovascular shock. Oxidative stress is a major promoter and mediator of the systemic inflammatory response. The microcirculation is particularly susceptible to oxidative stress that causes hemodynamic instability, leading to multiple organ failure due to systemic inflammatory response syndrome. Vitamin C is the antioxidant used experimentally to demonstrate oxidative stress as a key pathophysiologic factor in septic shock. Pharmacologic studies reveal that vitamin C (as ascorbate), at supraphysiologic doses, significantly affects the bioavailability of nitric oxide during acute inflammation, including inhibiting nitric oxide synthetase induction. Parenteral high-dose vitamin C inhibits endotoxin-induced endothelial dysfunction and vasohyporeactivity in humans and reverses sepsis-induced suppression of microcirculatory control in rodents. In severe burn injury, in both animals and patients, parenteral high-dose vitamin C significantly reduces resuscitation fluid volumes. Therefore, a significant body of pharmacologic evidence and sound preliminary clinical evidence supports the biological feasibility of using the exemplary antioxidant, vitamin C, in the treatment of the critically ill.

Practicalities of selenium supplementation in critically ill patients

PURPOSE OF REVIEW

To review the reason for and clinical effects of selenium supplementation in critically ill patients.

RECENT FINDINGS

Selenium-dependent enzymes and selenoprotein P regulate immune and endothelial cell function. Obviously not the anorganic compounds of selenium but the activity of selenium-dependent enzymes is the most important factor modulating the immune system and the clinical outcome of patients. Despite low selenium levels in severely ill patients and low glutathione peroxidase activity associated with the extent of multiorgan dysfunction, only a few trials have investigated the effect of selenium supplementation on clinical outcome. A metaanalysis did not reveal a statistically significant survival rate with selenium supplementation, but suggested a dose-dependent trend. The recently completed multicentre trial on high-dose selenium supplementation in septic patients also did not reveal a significant overall reduction in mortality.

SUMMARY

The available evidence suggests that selenoproteins play an important role in the immunomodulation of critically ill patients and a sodium selenite supplementation upregulates these selenoenzymes. The intervention trials with sodium selenite performed to date are small and therefore only a tendency in reduction of morbidity and mortality could be demonstrated. Larger trials are necessary to show the supposed benefits and risks of selenite supplementation in critically ill patients.

Kinetic Changes of Oxidative Stress and Selenium Status in Plasma and Tissues following Burn Injury in Selenium-Deficient and Selenium-Supplemented Rats

BACKGROUND

This study investigates the relationship between the burn-induced oxidative stress and the selenium status.

METHODS

The rats were fed with a selenium-adequate diet or a selenium-depleted diet for 5 weeks, before a third-degree thermal injury was applied to the animals. One group of selenium-depleted animals received injections of sodium selenite after the injury. The selenium status and the oxidative stress parameters were measured for 5 days.

RESULTS

The selenium-deficient diet leads to oxidative stress with a high stimulation of the superoxide dismutase activity. After the burn injury, the oxidative stress appears important because the initial selenium status is already impaired and, in all animals, the selenium levels and the antioxidant seleno-dependent glutathione peroxidase (GPx) activity decrease in the plasma and the tissues. A treatment with daily selenium injections is efficient in normalizing selenium levels and restores the GPx activity, but fails to counteract the initial oxidative damages induced by the selenium-deficient diet.

CONCLUSIONS

The selenium status before the burn injury is a modulating factor of the burn-induced oxidative stress. A single selenium supplement is not sufficient to counteract these oxidative damages and henceforth combined antioxidant supplementations should be investigated to improve the early treatment of the burn patients.

Optimization of selenium status by a single intraperitoneal injection of Se in Se-deficient rat: possible application to burned patient treatment

In order to investigate the efficiency of a single selenium (Se) administration in restoring selenium status, Se and antioxidant enzymes were studied in an animal model of Se depletion. In Se-depleted animals receiving or not a single parenteral administration of Se, plasma, red blood cell (RBC), and tissue Se levels were measured concurrently with glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities. The oxidative stress was assessed by thiobarbituric acid-reactive species (TBARs), total thiol groups, glutathione, and tocopherol measurements. Our study showed that Se depletion with alterations in the antioxidant defense system (Se and GPx activity decreases) led to an increase of lipid peroxidation, a decrease of the plasma vitamin E level, and SOD activation. Sodium selenite injection resulted after 24 h in an optimal plasma Se level and a reactivation of GPx activity. In liver, brain, and kidney, Se levels in injected animals were higher than those in reference animals. However, this single administration of Se failed to decrease free radical damage induced by Se depletion. Therefore, in burned patients who exhibit an altered Se status despite a daily usually restricted Se supplementation, the early administration of a consistent Se amount to improve the GPx activity should be of great interest in preventing the impairment of the antioxidant status.

Assessing the antioxidative status in critically ill patients

PURPOSE OF REVIEW

Oxidative stress is caused by a higher production of reactive oxygen and reactive nitrogen species or a decrease in endogenous protective antioxidative capacity. In all types of critical illness, such as sepsis, trauma, burn injury, acute pancreatitis, liver injury, severe diabetes, acute respiratory distress syndrome, AIDS and kidney failure, the occurrence of increased oxidative stress or a reduced antioxidative status is described. Whereas in the past, reactive oxygen and reactive nitrogen species were mainly known as harmful agents, recent investigations have given a new insight into the (patho)physiological importance of these substances as powerful messenger molecules involved in gene regulation, thereby enabling the synthesis of cytokines or adhesion molecules necessary for defending inflammatory processes. As shown in this review, there are numerous possibilities for the quantification of oxidative stress.

RECENT FINDINGS

Several investigations showed a close association of single or multiple parameters, such as total antioxidative capacity, lipid peroxidation, vitamins C and E, the activation of nuclear factor kappa B, and respiratory burst, with the patient's outcome. However, no recommendation for a single parameter to be measured can be given because the assays described do not allow the definition of an overall "antioxidative status" for patients.

SUMMARY

The occurrence of oxidative stress in critically ill patients is associated with a poor prognosis. The measurement of a cluster of assays representative of the quantification of reactive species or of antioxidants may improve the usefulness of therapeutic intervention and increase knowledge of pathophysiological alterations.

Early evolution of selenium status and oxidative stress parameters in rat models of thermal injury

The objective of the present study was to measure the relationship between selenium status and oxidative stress in two rat models of thermal injury. A non-lethal third-degree burn injury involving 20% (experiment 1) or 40% (experiment 2) of total body surface area (TBSA) was applied to male Wistar rats. Selenium level, glutathione peroxidase (GPx) activity in plasma, red blood cells (RBC) and tissues (liver, kidney, muscle, and brain), and plasma selenoalbumin (Se-alb) were measured in control rats and in burned rats respectively 6 hours after injury and daily from day 1 to day 5. In parallel, lipid and protein oxidative damages, monitored by plasma and tissue thiobarbituric acid reactive species (TBARs) levels and plasma total thiol groups were assessed. We observed a decrease of plasma Se and Se-albumin 6 hours after burn injury. In parallel, plasma GPx activity rapidly decreased and remained significantly lower than in control rats. These alterations were enhanced by the burn injury severity. Plasma TBARs followed the same pattern as that of plasma cholesterol, with an initial decrease and an increase at day 3 in 40% TBSA burned rats. Plasma thiol groups decreased in the two experiments indicating plasma protein oxidation. These results confirm an early oxidative stress in burn injury, and suggest an early selenium mobilization, which might counteract this oxidative stress. These data underline the crucial need of a restored selenium status in burned patients immediately after the burn injury.

Plasma oxidative parameters and mortality in patients with severe burn injury

OBJECTIVE

To determine xanthine oxidase and superoxide dismutase activities, lipid peroxidation, protein carbonylation, and total radical-trapping antioxidant parameter in survivors and nonsurvivors patients with severe burn injury.

DESIGN AND SETTING

Prospective, comparative observational study in an intensive care unit, burn division, in a trauma hospital.

PATIENTS

Twenty-five consecutive patients who met the established criteria for severe burn injury (total burn surface area of more than 30%).

MEASUREMENTS AND RESULTS

Plasma thiobarbituric acid reactive species and protein carbonyls levels were significantly higher in nonsurvivors than in survivors at 0 and 6 h. Elevated xanthine oxidase activity at 0 h was associated with adverse outcome after burn injury. In contrast, plasma superoxide dismutase activity and total radical-trapping antioxidant parameter did not differ significantly between nonsurvivors and survivors at any time point.

CONCLUSIONS

For the first time we demonstrate the value of oxidative parameters, namely thiobarbituric acid reactive species, protein carbonyls, and xanthine oxidase activity, in identifying burn patients with a poor prognosis. Whether these parameters are merely markers of clinical course, or whether they signal specific deleterious effects of oxidative stress during the burn injury remains to be elucidated.

Identification of an element within the promoter of human selenoprotein P responsive to transforming growth factor-beta

Selenoprotein P (SeP) is a plasma protein that contains up to 10 selenocysteine residues and accounts for about 50% of total selenium in human plasma. We have previously shown that SeP expression in the human liver cell line HepG2 is inhibited by transforming growth factor (TGF)-beta1 on a transcriptional level. Smad proteins are the transcriptional mediators of TGF-beta signalling and putative Smad-binding elements (SBE) comprising the core sequence CAGACA are present at two positions in the SeP promoter. The aim of our study was to investigate whether Smad molecules are involved in inhibition of SeP expression by TGF-beta1 and to locate the promoter region critical for this effect. As seen in electrophoretic-mobility-shift assays, TGF-beta1 treatment led to enhanced binding of nuclear proteins to a putative SBE from the SeP promoter. Overexpression of Smad 3 and 4, but not of Smad 2, resulted in a marked down-regulation of SeP mRNA expression. Similar effects were observed for luciferase expression under control of a human SeP-promoter construct. Deletion as well as point-mutation of putative SBEs led to a loss of promoter sensitivity towards TGF-beta1 treatment. Hence, we demonstrated an involvement of Smad 3 and 4 in transcriptional regulation of SeP by TGF-beta1 and we were able to identify the TGF-beta-responsive element in the SeP promoter.

Modulation of selenoprotein P expression by TGF-beta(1) is mediated by Smad proteins

Selenoprotein P (SeP) is a selenium-rich plasma protein which accounts for more than 50% this study, the effect of TGF-beta(1) on the expression of SeP in the human liver cell line HepG2 was investigated. Western analysis revealed a dose-dependent reduction of SeP content in cell supernatant. RT-PCR analysis of SeP-mRNA expression demonstrated a marked inhibition and a reporter gene under control of the SeP promoter was negatively regulated by TGF-beta(1). Smad proteins are the transcriptional mediators of TGF-beta signaling. A putative Smad-binding element (SBE) is present in the SeP promoter. In electrophoretic-mobility-shift assays, TGF-beta(1) enhanced the binding of nuclear proteins to this SBE. Overexpression of Smad3 and 4 resulted in a downregulation of SeP-promoter activity whereas deletion of the SBE led to a loss of TGF-beta(1) responsiveness. We conclude that SeP expression is modulated by the binding of Smad3/4 complexes to a functional SBE in the SeP promoter.