Trace elements in trauma and 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.

The Influence of Heavy Metals and Trace Elements on Comatose Patients with Severe Traumatic Brain Injury in the First Week of Admission

Purpose

The aim of this study is to investigate the possible role of heavy metals (lead and cadmium) and imbalance of trace elements (chromium, iron, zinc, copper, and manganese) in death among patients with severe traumatic brain injury.

Material and Methods

A case-control study was conducted with 64 comatose patients with severe TBI, in the Department of Anesthesiology and Reanimation, Ibn Sina University Hospital and Hospital of Specialties in Rabat, Morocco; 22 healthy volunteers were recruited in Blood Transfusion Center of Rabat. Blood samples were collected from TBI patients, in the first week (3h after admission and each 48h during one week) and from healthy volunteers one time. Concentration of heavy metals and trace elements in serum was determined by electrochemical atomic absorption spectrometry. Statistical analysis was performed using Statistical software (SPSS) and the cases and controls were compared using the Mann–Whitney U test and Student's t-test for cadmium according to gender and final evolution. A P-value <0.05 was considered to be statistically significant.

Results

Our data showed that the difference of heavy metals concentration (lead and cadmium) between patients and healthy subjects was not statistically significant. However, the difference of some trace elements concentration (iron, copper, chromium, and selenium) between patients and healthy subjects was statistically significant. According to the final evolution, the concentration of manganese was higher in dead patients and statistically significant (p = 0.04) for heavy metals; the concentration of lead was not statistically significant while the concentration in cadmium was statistically significant (p = 0.004). By sex, lead and cadmium were statistically significant, respectively p = 0.02, p = 0.001, and cadmium was higher in women, while lead was higher in men.

Conclusion

Among all studied heavy metals (lead and cadmium) and trace elements (iron, zinc, copper, selenium, chromium, and manganese), manganese and cadmium may play a role in the death of patients from severe traumatic brain injury.

Long-Term Effects of Ketogenic Diet on Subsequent Seizure-Induced Brain Injury During Early Adulthood: Relationship of Seizure Thresholds to Zinc Transporter-Related Gene Expressions

The divalent cation zinc is associated with cortical plasticity. However, the mechanism of zinc in the pathophysiology of cortical injury-associated neurobehavioral damage following neonatal seizures is uncertain. We have previously shown upregulated expression of ZnT-3; MT-3 in hippocampus of neonatal rats submitted to flurothyl-induced recurrent seizures, which was restored by pretreatment with ketogenic diet (KD). In this study, utilizing a novel "twist" seizure model by coupling early-life flurothyl-induced seizures with later exposure to penicillin, we further investigated the long-term effects of KD on cortical expression of zinc homeostasis-related genes in a systemic scale. Ten Sprague-Dawley rats were assigned each averagely into the non-seizure plus normal diet (NS + ND), non-seizure plus KD (NS + KD), recurrent seizures plus normal diet (RS + ND) and recurrent seizures plus KD (RS + KD) group. Recurrent seizures were induced by volatile flurothyl during P9-P21. During P23-P53, rats in NS + KD and RS + KD groups were dieted with KD. Neurological behavioral parameters of brain damage (plane righting reflex, cliff avoidance reflex, and open field test) were observed at P43. At P63, we examined seizure threshold using penicillin, then the cerebral cortex were evaluated for real-time RT-PCR and western blot study. The RS + ND group showed worse performances in neurological reflex tests and reduced latencies to myoclonic seizures induced by penicillin compared with the control, which was concomitant with altered expressions of ZnT-7, MT-1, MT-2, and ZIP7. Specifically, there was long-term elevated expression of ZIP7 in RS + ND group compared with that in NS + ND that was restored by chronic ketogenic diet (KD) treatment in RS + KD group, which was quite in parallel with the above neurobehavioral changes. Taken together, these findings indicate that the long-term altered expression of the metal transporter ZIP7 in adult cerebral cortex might correlate with neurobehavioral damage and reduced seizure threshold following recurrent neonate seizures and further highlights ZIP7 as a candidate for therapeutic target of KD for the treatment of neonatal seizure-induced long-term brain damage.

Antioxidant Micronutrients in Major Trauma and Burns: Evidence and Practice

There has been a growing interest in micronutrients as a result of their essential role in endogenous antioxidant defense mechanisms and immunity. Critically ill burn and trauma patients are characterized by an increased free radical production, which is proportional to the severity of the injury. In addition, they are at high risk of negative trace element balances, which contribute to the imbalance in endogenous antioxidant capacity and the extension of primary lesions. Although selenium, zinc, and vitamin C and E status are altered in all injured patients, patients with major burns are unique for having copper deficiency. In major burns, high-dose ascorbic acid for 24 hours achieves reduction of resuscitation fluid requirements by endothelial antioxidant mechanisms both in animal models and in 1 human trial. Supplementation trials in trauma and burns including selenium and zinc have shown that early provision of micronutrients improves recovery. Vitamin supplementation trials without selenium have not achieved definitive effects. The human studies show that reinforcing antioxidant defenses early in the course of major injury is rational and that substituting the large initial micronutrient losses of selenium and zinc is safe in trauma, as is the addition of copper in burns. The IV route seems the only way to deliver the doses required to obtain a clinical effect.

Antioxidants as therapeutics in the intensive care unit: Have we ticked the redox boxes?

Critically ill patients are under oxidative stress and antioxidant administration reasonably emerged as a promising approach to combat the aberrant redox homeostasis in this patient cohort. However, the results of the antioxidant treatments in the intensive care unit are conflicting and inconclusive. The main objective of the present review is to highlight some inherent, yet widely overlooked redox-related issues about the equivocal effectiveness of antioxidants in the intensive care unit, beyond methodological considerations. In particular, the discrepancy in the literature partially stems from: (1) the largely unspecified role of reactive species in disease onset and progression, (2) our fragmentary understanding on the interplay between inflammation and oxidative stress, (3) the complex spatiotemporal specificity of in vivo redox biology, (4) the pleiotropic effects of antioxidants and (5) the divergent effects of antioxidants according to the temporal administration pattern. In addition, two novel and sophisticated practices with promising pre-clinical results are presented: (1) the selective neutralization of reactive species in key organelles after they are formed (i.e., in mitochondria) and (2) the targeted complete inhibition of dominant reactive species sources (i.e., NADPH oxidases). Finally, the reductive potential of NADPH as a key pharmacological target for redox therapies is rationalized. In light of the above, the recontextualization of knowledge from basic redox biology to translational medicine seems imperative to perform more realistic in vivo studies in the fast-growing field of critical care pharmacology.

Vitamin and Trace Element Loss from Negative-Pressure Wound Therapy

OBJECTIVE

This study investigated select vitamin and trace element loss from wound exudates in burn and trauma patients treated with negative-pressure wound therapy (NPWT).

DESIGN

A prospective observational study was performed using wound exudate samples.

SETTING

A level I trauma center acute care hospital.

PARTICIPANTS

The study was composed of 8 patients with open abdomens and 9 patients with 12 soft-tissue wounds.

MAIN OUTCOME MEASURES

The goal was to collect wound exudate samples daily for 3 days, then every other day to day 9 or until NPWT was discontinued, and to analyze for vitamins A (retinol), C, and E and zinc (Zn), iron (Fe), and copper (Cu). Daily loss of each micronutrient was calculated from their concentration and 24-hour volumes of the exudates.

MAIN RESULTS

Exudate loss in the open-abdomen group was significantly higher than in the patients with soft-tissue wounds (900 ± 547 vs 359 ± 246 mL/d). The mean 24-hour loss of vitamins A, C, and E were 0.3, 2.8, and 11 mg, respectively, in the open-abdomen group. Over the same period, the losses of Zn, Fe, and Cu were 0.5, 0.4, and 0.25 mg, respectively, in these patients. Micronutrient 24-hour loss was significantly lower in the soft-tissue wound patients than in the open-abdomen group.

CONCLUSIONS

The data support the concept that significant amounts of micronutrients can be lost from NPWT wound exudates, particularly in open abdomens. These losses should be considered in the nutritional support of these patients who typically are in a hypermetabolic and catabolic state.

Altered Levels of Zinc and N-methyl-D-aspartic Acid Receptor Underlying Multiple Organ Dysfunctions After Severe Trauma

BACKGROUND

Severe trauma can cause secondary multiple organ dysfunction syndrome (MODS) and death. Oxidative stress and/or excitatory neurotoxicity are considered as the final common pathway in nerve cell injuries. Zinc is the cofactor of the redox enzyme, and the effect of the excitatory neurotoxicity is related to N-methyl-D-aspartic acid receptor (NMDAR).

MATERIAL AND METHODS

We investigated the levels of zinc and brainstem NMDAR in a rabbit model of severe trauma. Zinc and serum biochemical profiles were determined. Immunohistochemistry was used to detect brainstem N-methyl-D-aspartic acid receptor 1 (NR1), N-methyl-D-aspartic acid receptor 2A (NR2A), and N-methyl-D-aspartic acid receptor 2B (NR2B) expression.

RESULTS

Brain and brainstem Zn levels increased at 12 h, but serum Zn decreased dramatically after the trauma. NR1 in the brainstem dorsal regions increased at 6 h after injury and then decreased. NR2A in the dorsal regions decreased to a plateau at 12 h after trauma. The levels of NR2B were lowest in the death group in the brainstem. Serum zinc was positively correlated with NR2A and 2B and negatively correlated with zinc in the brain. Correlations were also found between the brainstem NR2A and that of the dorsal brainstem, as well as between brainstem NR2A and changes in NR2B. There was a negative correlation between zinc and NR2A.

CONCLUSIONS

Severe trauma led to an acute reduction of zinc enhancing oxidative stress and the changes of NMDAR causing the neurotoxicity of the nerve cells. This may be a mechanism for the occurrence of MODS or death after trauma.

Ceruloplasmin and Hypoferremia: Studies in Burn and Non-Burn Trauma Patients

OBJECTIVE

Normal iron handling appears to be disrupted in critically ill patients leading to hypoferremia that may contribute to systemic inflammation. Ceruloplasmin (Cp), an acute phase reactant protein that can convert ferrous iron to its less reactive ferric form facilitating binding to ferritin, has ferroxidase activity that is important to iron handling. Genetic absence of Cp decreases iron export resulting in iron accumulation in many organs. The objective of this study was to characterize iron metabolism and Cp activity in burn and non-burn trauma patients to determine if changes in Cp activity are a potential contributor to the observed hypoferremia.

MATERIAL AND METHODS

Under Brooke Army Medical Center Institutional Review Board approved protocols, serum or plasma was collected from burn and non-burn trauma patients on admission to the ICU and at times up to 14 days and measured for indices of iron status, Cp protein and oxidase activity and cytokines.

RESULTS

Burn patients showed evidence of anemia and normal or elevated ferritin levels. Plasma Cp oxidase activity in burn and trauma patients were markedly lower than controls on admission and increased to control levels by day 3, particularly in burn patients. Plasma cytokines were elevated throughout the 14 days study along with evidence of an oxidative stress. No significant differences in soluble transferrin receptor were noted among groups on admission, but levels in burn patients were lower than controls for the first 5 days after injury.

CONCLUSION

This study further established the hypoferremia and inflammation associated with burns and trauma. To our knowledge, this is the first study to show an early decrease in Cp oxidase activity in burn and non-burn trauma patients. The results support the hypothesis that transient loss of Cp activity contributes to hypoferremia and inflammation. Further studies are warranted to determine if decreased Cp activity increases the risk of iron-induced injury following therapeutic interventions such as transfusions with blood that has undergone prolonged storage in trauma resuscitation.

Altered levels of trace elements in acute lung injury after severe trauma

Trace element (TE) supplementation can reduce the incidence of multiple organ failure after severe trauma. The lung plays a main role in post-injury multiple organ failure. In the present study, the relationship between TEs and acute lung injury (ALI) post-injury was investigated in a rabbit model of severe trauma with an injury severity score of 27. New Zealand white rabbits were randomly assigned to trauma-control, trauma-TE groups, and a control group. During days 1-5 post-trauma, each rabbit in the trauma-TE group received 0.1 ml multi-TE compound intraperitoneally to give a daily dose of 32.50 mg/kg of Zn, 6.35 mg/kg of Cu, 1.38 mg/kg of Mn, and 0.16 mg/kg of Se. Concentrations of blood and lung selenium (Se), copper (Cu), zinc (Zn), and manganese (Mn) were measured at 6 and 24 h, as well as 3, 6, 9, and 14 days after trauma. Levels of glutathione peroxidase (GPx), total superoxide dismutase (SOD), Cu/Zn superoxide dismutase (Cu/Zn-SOD), and malondialdehyde (MDA) in serum and lung tissue and the level of intercellular adhesion molecular-1 (ICAM-1) in serum were detected simultaneously. In addition, the lung coefficient (LC) and the lung permeation index (LPI) were measured. Serum and lung Zn, Se, and Mn levels decreased dramatically by 6 h after trauma in both experimental groups. Cu showed no significant changes after trauma. The serum and lung GPx and SOD levels in the experimental group decreased significantly on days 1 and 3, respectively. Serum and lung MDA began to increase on day 3 in the trauma group but increased less after TE supplementation. Serum ICAM-1 peaked on day 6 in the experimental group. LC and LPI increased gradually post-trauma, peaking on days 6 and 9, respectively. In conclusion, an acute lung injury causes declines of the levels of TEs in serum and lung which can be significantly prevented by TE supplementation and which can also mitigate some of the morphological and biomechanical changes in ALI.

Efficacy and tolerability of fitostimoline in two different forms (soaked gauzes and cream) and citrizan gel in the topical treatment of second-degree superficial cutaneous burns

A total of 227 patients (mean age 41.3 years, 52% females) with at least one second-degree superficial cutaneous burn of thermal origin of a smallest transverse diameter ≥20 mm and a largest transverse diameter ≤90 mm were randomised to receive the topical application of aqueous extract of Triticum vulgare (Fitostimoline) in two different forms (soaked gauzes and cream) or catalase of horse origin in form of gel (Citrizan Gel), given up to healing or to a maximum of 20 days. The rate of lesion healing at end of study was significantly higher in patients treated with Fitostimoline (gauzes 97.3%, cream 91.5%) than in those receiving catalase (84.5%). The pooled Fitostimoline groups were also significantly more effective than catalase gel in reducing total symptoms score, pain at medication, pain at rest, and burning at end of study. Both formulations of Fitostimoline and catalase gel were well tolerated in terms of adverse effects in the site of application.

Antioxidant-enriched enteral nutrition and immuno-inflammatory response after major gastrointestinal tract surgery

Major surgery induces an immuno-inflammatory response accompanied by oxidative stress that may impair cellular function and delay recovery. The objective of the study was to investigate the effect of an enteral supplement, containing glutamine and antioxidants, on circulating levels of immuno-inflammatory markers after major gastrointestinal tract surgery. Patients (n 21) undergoing major gastrointestinal tract surgery were randomised in a single-centre, open-label study. The effects on circulating levels of immuno-inflammatory markers were determined on the day before surgery and on days 1, 3, 5 and 7 after surgery. Major gastrointestinal surgery increased IL-6, TNF receptor 55/60 (TNF-R55) and C-reactive protein (CRP). Surgery reduced human leucocyte antigen-DR (HLA-DR) expression on monocytes. CRP decrease was more pronounced in the first 7 d in the treatment group compared with the control group. In the treatment group, from the moment Module AOX was administered on day 1 after surgery, TNF receptor 75/80 (TNF-R75) level decreased until the third post-operative day and then stabilised, whereas in the control group the TNF-R75 level continued to increase. The results of the present pilot study suggest that enteral nutrition enriched with glutamine and antioxidants possibly moderates the immuno-inflammatory response (CRP, TNF-R75) after surgery.

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.

Trace element supplementation after major burns modulates antioxidant status and clinical course by way of increased tissue trace element concentrations

BACKGROUND

After major burns, patients can develop nutritional deficiencies including trace element (TE) deficiencies. Various complications, such as infections and delayed wound healing, influence the clinical course of such patients.

OBJECTIVES

We aimed to investigate the effects of large, intravenous doses of TE supplements on circulating and cutaneous TE tissue concentrations, on antioxidant status, and on clinical outcome after major burns.

DESIGN

This was a prospective, randomized, placebo-controlled trial in 21 patients aged 35 +/- 11 y (x +/- SD) with burns on 45 +/- 21% of their body surface area. Intravenous copper, selenium, and zinc (TE group) or vehicle (V group) was given with a saline solution for 14-21 d. Blood and urine samples were collected until day 20, and skin biopsy specimens were collected on days 3, 10, and 20.

RESULTS

The age of the patients and the severity of their burns did not differ significantly between the groups. Plasma TE concentrations were significantly higher in the TE group. In burned areas, skin contents of both selenium (P=0.05) and zinc (P=0.04) increased significantly by day 20. Plasma and tissue antioxidant status was improved by supplementation. The number of infections in the first 30 d was significantly lower in the TE group (P=0.015), with a median number of 2 versus 4 infections per patient in the TE and V groups, respectively, as a result of a reduction in pulmonary infections (P=0.03). Wound healing was improved in the TE group, with lower requirements for regrafting (P=0.02).

CONCLUSIONS

TE supplementation was associated with higher circulating plasma and skin tissue contents of selenium and zinc and improved antioxidant status. These changes were associated with improved clinical outcome, including fewer pulmonary infections and better wound healing.

Trace element supplementation after major burns increases burned skin trace element concentrations and modulates local protein metabolism but not whole-body substrate metabolism

BACKGROUND

After major burns, patients exhibit an intense catabolism, and the wounds require surgery and grafting for closure. Complications, such as weight loss and delayed wound healing, are worsened by trace element (TE) deficiencies.

OBJECTIVE

We aimed to assess the effects of TE supplements on systemic substrate turnover and local protein metabolism during wound healing after major burns.

DESIGN

This was a prospective, randomized, placebo-controlled trial in 21 patients aged 35 +/- 11 y with burns on 45 +/- 16% of their body surface area; 12 had skin biopsies performed on days 3, 10, and 20, and 10 patients underwent a stable-isotope investigation on day 10. Intravenous copper, selenium, and zinc (TE group) or vehicle (V group) was given with a saline solution for 14-21 d. On day 10, [(13)C]phenylalanine (600-microg/kg bolus followed by 12 microg x kg(-1) x min(-1)) plus 6-[(2)H(2)]glucose and [(2)H(5)]glycerol were infused for 6 h to determine skin protein turnover. Biopsies were performed 1 and 6 h after the start of infusion to determine [(13)C]phenylalanine enrichment.

RESULTS

The patients' mean age and burn severity did not differ significantly between the groups nor between the skin investigations subgroups. Plasma TE concentrations were significantly higher in the TE group. In the burned areas, the skin contents of selenium (P=0.02) and zinc (P=0.03) increased by day 20. The supernatant-to-plasma (13)C enrichment ratio in burned skin was 0.363 +/- 0.094 (TE group) and 0.286 +/- 0.130 (V group) after 1 h (NS) and 0.592 +/- 0.153 (TE group) and 0.262 +/- 0.171 (V group) after 6 h, which reflected lower catabolism in the TE group (P=0.03). No significant differences in whole-body substrate turnover were found between the groups.

CONCLUSION

TE supplementation was associated with an increased skin tissue content of selenium and zinc and with a reduction in skin protein catabolism.

Trace element requirements in critically ill burned patients

Critically ill burned patients are characterized by a strong oxidative stress, an intense inflammatory response, and months-long hypermetabolism, all of which are proportional to the severity of injury. Trace element (TE) deficiencies have repeatedly been described. The clinical course is complicated by organ failures, infections, and delayed wound healing, which can be partly attributed to TE deficiencies. Among critically ill patients, TE deficiencies are the most severe in major burns, who suffer a specific copper deficiency. Plasma TE concentrations are low during any critical illness, as a result of TE losses in biological fluids, low intakes, dilution by fluid resuscitation, and redistribution from plasma to tissues mediated by the inflammatory response. The large exudative losses cause negative TE balances. Intravenous supplementation trials show that early substitution improves recovery, reduces infectious complications (particularly nosocomial pneumonia), normalize thyroid function, normalize skin tissue levels, improve wound healing and shorten hospital stay. Nevertheless, prolonged high dose delivery may be deleterious, as TE have potential for toxicity. In major burns, supplements up to 4 mg of Cu/day, 500 mcg [DOSAGE ERROR CORRECTED] Se/day and 40 mg Zn/day for 3 weeks have been found to be safe and effective. The intravenous route appears the only way to deliver the doses required to achieve antioxidant and clinical effects. Further research is required to determine the optimal combination and doses for different severities of injury.

Update on clinical micronutrient supplementation studies in the critically ill

PURPOSE OF REVIEW

During the past 2 years a number of studies, meta-analyses and reviews have shown that micronutrient supplementation may be beneficial in critical illness. Selenium is emerging as a particularly important micronutrient. This paper reviews the evidence from trials in the critically ill, putting mechanisms, methods and shortcomings into perspective.

RECENT FINDINGS

There is growing evidence that antioxidant supplements, particularly high-dose selenium, may reduce mortality, infectious complications, and improve wound healing. Deleterious effects may result from prolonged high doses, whereas short-term high dose supplements are probably safe in most critically ill populations.

SUMMARY

Plasma micronutrient concentrations are low during critical illness, as a result of losses, low intakes and dilution, and redistribution from plasma to tissues. An assessment of status is difficult. Micronutrient supplements appear beneficial in conditions such as major burns, trauma and sepsis and stroke, and are most likely to benefit patients with previous or actual depletion. The intravenous route seems more efficient than the enteral. Although chronic high intakes may be harmful, short-term interventions appear to be free of deleterious effects. Further research is required to determine the optimal micronutrient combinations and the doses required according to the timing of intervention and severity of disease.

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.

Burn-induced alterations of chromium and the glucose/insulin system in rats

Our objective was to demonstrate a role of chromium (Cr) in response to severe burn. A third-degree burn involving 20% of total body surface was applied under anaesthesia in accord with ethical guidelines. Chromium concentrations in liver decreased progressively and were non-detectable on days 5 and 10 following injury. In quadriceps muscle, Cr concentrations increased 6h after injury and then declined significantly within the first day and remained at these levels the following 9 days. Urinary Cr losses were also increased. Changes in kidney, brain and serum Cr were not significant. Non-fasting glucose rose 6h after injury and then returned to levels measured before the burn. There was a significant rise in corticosterone reaching a maximum the first day after injury that was accompanied by significant increases in circulating insulin and glucagon that were maximal after 2 days. Changes in IGF-1 were not significant. In summary, changes in Cr concentrations were associated with an early hyperglycemia, hyperinsulinemia and increased secretion of stress hormones. These observations strongly suggest a mobilization and utilization of Cr following severe burn. Additional studies are needed to document that improved Cr status might lead to improved recovery following burn.

Antioxidant therapy in intensive care

PURPOSE OF REVIEW

This review intends to summarize the recent findings regarding the presence of increased oxidative stress in critically ill patients and its potential pathophysiologic role, as well as the results of recent clinical trials of antioxidant therapies.

RECENT FINDINGS

Several lines of evidence confirm the increase in oxidative stress during critical illness. The oxidative damage to cells and tissues eventually contributes to organ failure. Prophylactic administration of antioxidant vitamins or glutamine, incorporated in the nutritional support or given as separate medications, efficiently attenuates the oxidative stress and in some studies improves the outcome of critically ill patients. Few data on the effects of N-acetylcysteine or trace elements have been published during the last two years.

SUMMARY

Patients at risk of organ failure could benefit from the early adjunction of antioxidant treatment, including vitamins and glutamine.

Micronutrients in the severely-injured patient

The trace element and vitamin requirements of severely-ill injured patients depend on a complex interaction of the status of the patient at the time of admission, ongoing losses and the potential benefit of supplying large amounts of individual micronutrients. Characteristic clinical deficiency states are now uncommon, but subclinical deficiency is of growing concern. The main effects of subclinical deficiency are: (1) an altered balance of reactive oxygen species and antioxidants, leading to oxidative damage of polyunsaturated fatty acids and nucleic acids, and possibly to increased activation of the transcription factor nuclear factor-kappaB, with increased production of pro-inflammatory cytokines: (2) impaired immune function with increased likelihood of infectious complications. Laboratory tests to optimize intake in such critically-ill patients lack sensitivity and specificity, this situation being made worse as a result of the acute-phase response. Recent studies have indicated the clinical benefit of providing large amounts of certain micronutrients in burned and head-injured patients. Further clinical studies are now required to define optimal levels of provision in different disease states, with a particular emphasis on markers of tissue function and clinical outcome.

Technical aspects of trace element supplementation

Routine supplementation of total parenteral nutrition mixtures with the readily available single or combination trace elements products is becoming more widespread. As more is learned about deficiency syndromes and monitoring techniques, so too must we understand more about the physicochemical interactions between individual trace elements and other nutrients, that could ultimately affect bioavailability. Expert pharmaceutical assessment of these complex reactions, that have been demonstrated to occur in solution, becomes increasingly important in order to optimize the efficacy of micronutrient therapy.