[Show abstract][Hide abstract] ABSTRACT: Systemic inflammation, which is associated with various conditions such as sepsis, pneumonia, and trauma, can lead to multiple organ dysfunction syndrome. Systemic inflammation can be life-threatening and is often associated with conditions seen in the intensive care unit. Leukocytes exert a proinflammatory effect and damage various tissues during systemic inflammation. The purpose of this study was to determine whether leukocytapheresis therapy can prevent lipopolysaccharide (LPS)-induced systemic inflammation in a rat model.
Male Wistar rats weighing 250 to 300 g were used for all experiments. Rats received an LPS injection, followed 6 h later by filtration leukocytapheresis or mock treatment for 30 min under sevoflurane anesthesia. Systemic inflammation was induced in rats by intravenous LPS injection (7.5 mg/kg) followed by filtration leukocytapheresis. Following blood filtration, we evaluated lung and liver histology, serum cytokine levels, and survival rate of rats for each treatment group.
Histologic examination revealed markedly reduced inflammatory injury in lung and liver tissue harvested from rats 24 h after leukocytapheresis therapy compared with mock treatment. LPS-induced tumor necrosis factor (TNF)-α and interleukin (IL)-6 secretion was also inhibited by leukocytapheresis therapy. Moreover, survival was significantly increased in rats treated with high-efficiency leukocytapheresis compared to mock-treated rats (P<0.05).
Taken as a whole, our findings indicate that filtration leukocytapheresis therapy protects against LPS-induced systemic inflammation. Therefore, leukocytapheresis shows potential as a new therapy for various systemic inflammatory diseases.
No preview · Article · Dec 2011 · Journal of Surgical Research
[Show abstract][Hide abstract] ABSTRACT: Systemic inflammation can result in multiple organ dysfunction syndrome, a potentially life-threatening condition. Some reports suggest that continuous hemodiafiltration can effectively remove proinflammatory cytokines from circulation during systemic inflammation. In the present study, we investigated whether continuous hemodiafiltration therapy could prevent LPS-induced systemic inflammation and improve survival in a rat model.
Male Wistar rats were injected with lipopolysaccharide (LPS; 7.5 mg/kg body weight), and 6 h later were treated with either single-pass hemofiltration (C group), continuous hemofiltration (CHF group), continuous hemodiafiltration (CHDF group), or mock filtration (Control group). We performed histologic examinations of lung and liver tissues, determined serum cytokine levels, and survival rates for each treatment group, and compared cytokine removal between CHF and CHDF therapies.
Histologic examination revealed significant reduction in inflammation in lung and liver tissues harvested 24 h after CHDF compared with the Control group. Likewise, LPS-induced serum TNF-α and IL-6 levels decreased with continuous hemodiafiltration along with a significant improvement in survival. After 30 min of treatment, both CHF and CHDF removed significant amounts of TNF-α and IL-6 from the blood. However, serum cytokine levels measured before and after filtration were not significantly different.
Continuous hemodiafiltration therapy lowered inflammatory cytokines and increased survival rates in a rat model of systemic inflammation. Therefore, continuous hemodiafiltration may be a potential therapy for use against various systemic inflammatory diseases.
No preview · Article · Dec 2011 · Journal of Surgical Research
[Show abstract][Hide abstract] ABSTRACT: Postoperative stress produces an inflammatory response. Recent studies have shown that narcotic analgesics suppress the immune system. Nutritional management during perioperative care has also been reported to affect inflammation. We therefore examined whether remifentanil or glucose administration could ameliorate postsurgical inflammatory responses using a rat model of surgical stress.
We divided male Wistar rats randomly into five groups: (1) control, (2) sevoflurane+lactated Ringer's solution, (3) sevoflurane+lactated Ringer's solution with 1% glucose, (4) sevoflurane+remifentanil+lactated Ringer's solution, and (5) sevoflurane+remifentanil+ lactated Ringer's solution with 1% glucose. In all groups, serum samples were obtained at various time points after surgery, and secreted cytokine concentrations were determined. In addition, we assessed the activation of protein kinase B (Akt) and forkhead/winged helix box class O (FOXO3), which play a role in gluconeogenesis/stress responses.
Surgical stress increased the serum concentrations of tumor necrosis factor-α and interleukin-6. Groups receiving remifentanil with anesthesia showed an attenuated inflammatory response. The inflammatory response was also reduced by administering 1% glucose. Furthermore, 1% glucose induced Akt and FOXO3 phosphorylation in the quadriceps femoris muscle 12 h after surgery.
Anesthesia based on remifentanil and perioperative administration of lactated Ringer's solution containing 1% glucose may be able to control inflammatory responses caused by surgical stress.
[Show abstract][Hide abstract] ABSTRACT: Diabetes is a common comorbidity in patients with various medical conditions. Tight glucose control is known to improve systemic inflammation; however, whether it is effective in diabetic patients is unknown. The purpose of this study was to examine how strict glucose control affects systemic inflammation in diabetic patients.
Male Wistar rats. We determined the effect of insulin therapy on cardiac function in a rat model of systemic inflammation. We administered lipopolysaccharide intravenously, with or without insulin, to streptozotocin-induced diabetic rats. After induction of systemic inflammation, we determined serum cytokine (IL-6 and TNFα) and nitrate/nitrite levels and measured cardiac function.
Cytokine levels and cardiac function were significantly reduced in diabetic rats compared to non-diabetic rats. Moreover, insulin treatment was associated with higher cytokine levels and decreased cardiac function.
In systemic inflammatory conditions, diabetes increases various proinflammatory mediators and inhibits cardiac function; insulin treatment exacerbates these effects. Thus, strict glucose control may not be desirable in diabetic patients with systemic inflammatory conditions.
No preview · Article · Nov 2011 · Journal of Surgical Research
[Show abstract][Hide abstract] ABSTRACT: Acute renal damage has numerous causes, including renal ischemia-reperfusion injury. Due to its diverse actions, cepharanthine is used to treat many acute and chronic diseases, including pit viper bites, alopecia areata, and leucopenia in radiation therapy. In this study, we examined whether cepharanthine provides a renal-protective effect in a renal ischemia-reperfusion model.
Male Wistar rats were divided into four groups that received the following treatments: induction of renal ischemia-reperfusion (I/R group); subcutaneous injection of cepharanthine (10 mg/kg) followed 1 h later by induction of renal ischemia-reperfusion (Cepha + I/R group); subcutaneous injection of cepharanthine (10 mg/kg) (Cepha group); and subcutaneous injection of saline followed 1 h later by sham treatment (control group). Rats were sacrificed 24 h after renal ischemia-reperfusion or sham treatment. Serum blood urea nitrogen (BUN) and creatinine (Cre) concentrations were determined, histologic examination was performed, and oxidative stress was evaluated in kidney tissue. In addition, antimycin A (AMA)-stimulated RAW264.7 cells were treated with cepharanthine to determine its antioxidant effects.
Serum BUN and Cre levels were increased in the I/R group; however, these increases were significantly inhibited in the Cepha + I/R group. Similarly, kidney tissue damage observed in the I/R group was attenuated in the Cepha + I/R group. In vitro, cells treated with both cepharanthine and AMA showed reduced reactive oxygen species activity compared with cells treated with AMA alone.
Our findings suggest that cepharanthine may be effective in the treatment of various types of ischemia-reperfusion injuries.
No preview · Article · Nov 2011 · Journal of Surgical Research
[Show abstract][Hide abstract] ABSTRACT: Recent studies have reported that controlling blood glucose with insulin can suppress systemic inflammation. In the present study, we evaluated how perioperative intensive insulin therapy (IIT) influences the inflammatory response in an artificial pancreas during cardiac surgery with cardiopulmonary bypass.
We randomly divided the patients undergoing cardiac surgery with cardiopulmonary bypass into two groups: an IIT group (n = 13) and a conventional treatment (CT) group (n = 12). For the IIT group, blood glucose control was initiated with an artificial pancreas at initiation of surgery. Blood glucose was maintained at 100 mg/dl until 24 h postoperatively. Blood samples were collected to determine changes in serum cytokine levels over time.
Patients' characteristics did not differ significantly between groups. Blood glucose levels were significantly higher in the CT group after surgery. Serum levels of tumor necrosis factor-α, interleukin-6, and high-mobility group box 1 were higher in the CT group than in the IIT group.
Use of IIT in the artificial pancreas during the perioperative period significantly decreased the inflammatory response. Moreover, we did not find evidence of hypoglycemia in those treated with IIT. This suggests that use of IIT in an artificial pancreas can be safe and effective for critically ill patients.
[Show abstract][Hide abstract] ABSTRACT: Heat shock protein 72 (HSP72(a)) exhibits cell- and organ-protective effects in response to inflammation. Moreover, high mobility group box 1 (HMGB1) protein is a lethal mediator of acute inflammation. We examined associations between HMGB1 expression and protective effects observed when whole-body hyperthermia (WH) induces HSP72 in a lipopolysaccharide (LPS(b))-induced inflammation model.
Serum cytokine and HMGB1 levels, as well as HSP72 and HMGB1 expression in lung tissue were analyzed after WH treatment. Furthermore, effects of prior induction of HSP72 and silencing of HSP72 on HMGB1 secretion were examined in cultured RAW264.7 cells.
Survival improved significantly from 33% in the LPS group to 78% in the WH+LPS group. Interleukin-6, tumor necrosis factor-α, and HMGB1 concentrations were significantly lower in WH-treated rats. Furthermore, inflammation was reduced in lungs of WH-treated rats. Prior induction of HSP72 resulted in significantly decreased HMGB1 secretion by RAW264.7 cells in vitro, while silencing of HSP72 prevented this decrease.
Our results suggest that HSP72 induction by thermal pretreatment reduced inflammation and improved survival in the LPS-induced systemic inflammation model. These effects, which were associated with inhibition of HMGB1 expression, potentially involve HSP-mediated inhibition of HMGB1 secretion.
No preview · Article · Jul 2011 · Journal of Surgical Research
[Show abstract][Hide abstract] ABSTRACT: Septic shock is characterized by systemic inflammation and can lead to hemorrhage and necrosis in multiple organs. Septic shock is one of the leading causes of death. Studies have reported that septic shock is strongly associated with coagulation abnormality. The adenosine diphosphate (ADP) receptor antagonist, clopidogrel sulfate (CS), inhibits platelet function. Thus, we hypothesized that CS could inhibit LPS-induced systemic inflammation in a rat model. Male Wistar rats weighing 250 to 300 g received an LPS injection, followed 6 h later by filtration leukocytapheresis or mock treatment for 30 min under sevoflurane anesthesia. Five days before LPS injection, rats were given an oral dose of water or CS (10 mg/kg body weight). Levels of proinflammatory markers were determined in serum and tissue samples, and high-mobility group box 1 (HMGB1) expression was evaluated in lung and liver tissues. Compared with LPS-treated rats, induction of cytokines (IL-6 and TNF-α) was reduced in rats pretreated with CS. In addition, histological changes observed in lung and liver tissue samples of LPS-treated rats were attenuated in CS-pretreated rats. Clopidogrel sulfate pretreatment also reduced LPS-induced HMGB1 expression in lung and liver tissues. Collectively, our findings demonstrate that CS pretreatment may have value as a new therapeutic tool against systemic inflammation.
No preview · Article · Mar 2011 · Shock (Augusta, Ga.)
[Show abstract][Hide abstract] ABSTRACT: Autophagy is a natural process by which a cell maintains homeostasis, usually taking place unnoticed by adjacent cells. Glucose is involved in a negative feedback loop in autophagy. Autophagy is characterized by the induction and secretion of HMGB1, yet the nature of the inflammatory response during and the effect of glucose administration on autophagy are not well understood. Systemic inflammation was induced in experimental animals by LPS injection (7.5 mg/kg) followed by a continuous infusion of either 1%, 5%, or 25% glucose. Autophagy was visualized by immunohistochemistry 12 h after LPS injection. Likewise, protein levels of microtubule-associated protein light chain 3 (LC3)-II, autophagy-related protein 7 (Atg7), and high-mobility group box 1 (HMGB1) were assayed by western blot analysis. We found that autophagy increased in liver tissue in response to LPS-induced systemic inflammation. However, protein levels decreased in rats receiving LPS and a 5% glucose solution. Our results suggest that LPS-induced systemic inflammation increases autophagy in liver cells, potentially involving the upregulation of LC3-II, Atg7, and HMGB1. We also show that a 5% glucose infusion reduces autophagy. We propose that maintaining serum glucose levels with an adequate glucose dose improves systemic inflammation by reducing autophagy.
[Show abstract][Hide abstract] ABSTRACT: Cardiac remodeling after acute myocardial infarction is regulated by components of the extracellular matrix. The 47 kD heat shock protein 47 (HSP47) is a collagen-specific molecular chaperone that plays a major role during procollagen processing and/or secretion.
The purpose of the study was to determine whether HSP47 inhibition can mitigate ligated left anterior descending (LAD) coronary artery-induced myocardial infarction in rats.
Rats were randomly divided into four experimental groups and subjected to the following treatments: 1) intravenous (IV) administration of saline; 2) ligation of the LAD coronary artery; 3) ligation of the LAD coronary artery + IV administration of HSP47 antisense oligonucleotides; or 4) IV administration of HSP47 antisense oligonucleotides. We investigated cardiac histopathology, performed immunoblot and immunohistochemical analyses, and examined cardiac function.
Rats with ligated LAD coronary artery experienced upregulation of HSP47 expression, remodeling of the left ventricle, and cardiac dysfunction. In contrast, rats with ligated LAD coronary artery treated with HSP47 antisense oligonucleotides had significantly reduced HSP47 expression, cardiac remodeling, and improved cardiac function. Intravenous (IV) administration of HSP47 antisense oligonucleotides alone had no effect on cardiac morphology.
The data strongly support the idea that changes in the extracellular matrix and its components are important determinants of cardiac remodeling after myocardial infarction.
No preview · Article · Mar 2011 · The Thoracic and Cardiovascular Surgeon
[Show abstract][Hide abstract] ABSTRACT: Calorie restriction (CR) exerts cytoprotective effects by up-regulating survival factors, such as mammalian target of rapamycin (mTOR), sirtuin, and peroxisome proliferator-activated receptor-γ co-activator 1α (PGC-1α). These survival factors have well-established roles in attenuating the inflammatory response. However, it is unclear whether CR affects sepsis-related inflammation. The purpose of this study was to determine whether CR affects sepsis-induced inflammation in a cecal ligation and puncture (CLP)-induced mouse model of sepsis.
Male C57BL/6N mice underwent alternate day calorie restriction or normal feeding for 8 d before CLP-induced sepsis. After induction of sepsis, liver and lung histopathology and serum levels of cytokines and survival factors were assessed.
Serum cytokine and high mobility group box protein 1 (HMGB1) levels were lower in animals that underwent alternate day calorie restriction compared with normally-fed mice after CLP. Alternate day calorie restriction also increased levels of sirtuin, PGC-1α, and mTOR. While 80% of mice in the CLP group died within 48 h after undergoing CLP, 50% of mice died in the ACR + CLP group (P < 0.05).
Alternate day calorie restriction decreased mortality in a mouse model of sepsis. In addition to attenuated organ injury, a significant reduction in cytokine and HMGB1 levels was observed. These findings suggest that alternative day calorie restriction may reduce excessive inflammation.
No preview · Article · Dec 2010 · Journal of Surgical Research
[Show abstract][Hide abstract] ABSTRACT: The dysregulated metabolism associated with diabetes mellitus (DM) impairs membrane trafficking events in the liver, including the process of autophagy, which is an essential ongoing cellular process that is highly regulated by nutrients, endocrine factors, and signaling pathways. High-mobility group box 1 (HMGB1) is a nuclear protein with a known role in systemic inflammation and the related various organ injuries. However, its relationship to autophagy is not well understood. The aim of this study was to investigate the effects of inflammation injury on autophagy in the liver in a rat model of DM. DM was induced in animals with streptozotocin, followed four weeks later by induction of inflammation by LPS injection. At 12 h after LPS administration, autophagy was assessed by immunohistochemistry and Western blot analysis of microtubule-associated protein light chain 3 (LC3)-II, as well as transmission electron microscopy. Expression of HMGB1 was also examined by immunohistochemistry and Western blot analysis. Western blot analysis of liver tissue revealed that levels of LC3-II and HMGB1 protein increased in DM rats subjected to LPS-induced inflammation compared with non-DM rats. Autophagy was particularly enhanced in DM rats. Thus, autophagy might be related to progression to organ injury in patients with DM, and inflammation in these patients might be associated with over-induction of autophagy and increased HMGB1 expression.
No preview · Article · Oct 2010 · Biomedical Research
[Show abstract][Hide abstract] ABSTRACT: The incidence of acute kidney injury (AKI) in the elderly population has steadily increased in recent years. Functional recovery after AKI is also impaired in the elderly; however, the mechanism underlying these age-related differences is not well understood. In the present study, we assessed kidney morphology, function, and oxidative stress in young and aged rats after renal ischemia and reperfusion.
Young (6- to 7-wk-old) and aged (60- to 65-wk-old) male Wistar rats were divided into four groups based on age and treatment: renal ischemia-reperfusion in young rats (young IR); renal ischemia-reperfusion in aged rats (aged IR); sham treatment in young rats (young control), and sham treatment in aged rats (aged control). Rats were sacrificed 24 h after treatment, serum blood urea nitrogen (BUN) and creatinine (Cre) concentrations were determined, and kidney tissue histology and 8-hydroxydeoxyguanosine (8-OHdG) levels were evaluated.
After ischemia-reperfusion, serum BUN, and Cre levels were higher in aged rats than in young rats. Reperfusion-induced kidney damage and kidney tissue 8-OHdG levels were also more severe in the aged IR group. Moreover, plasma antioxidant potential was lower in aged IR rats than in young IR rats.
Aged rats exhibited reduced antioxidant potential and increased oxidative stress after ischemia-reperfusion. Our findings demonstrate that aged rats experience more severe reperfusion-induced injuries compared with young rats.
No preview · Article · Sep 2010 · Journal of Surgical Research
[Show abstract][Hide abstract] ABSTRACT: Ischemia-reperfusion (I/R) contributes to acute kidney injury (AKI). On the other hand, anti-oxidative drugs help to prevent renal injury caused by I/R. The current study examined whether a new antioxidant, ETS-GS, inhibits reactive oxygen species (ROS) generation and thereby prevents renal I/R injury in rodent models.
Rats with experimentally-induced renal I/R injury were treated concurrently with an intravenous injection of either ETS-GS or saline. Anesthesia was induced with sevoflurane.
Histologic examination revealed marked reduction of interstitial congestion, edema, inflammation, and hemorrhage in kidney tissue harvested 24 h after ETS-GS treatment. Renal I/R-induced secretion of nitric oxide (NO) in serum was inhibited by ETS-GS treatment. Furthermore, malondialdehyde (MDA) levels in the kidney were significantly lower in ETS-GS-treated rats with renal I/R. Moreover, when murine macrophage-like RAW264.7 cells were stimulated with antimycin A in the presence or absence of simultaneous ETS-GS treatment, ETS-GS decreased ROS levels.
Thus, ETS-GS lowered ROS levels in cultured cells, reduced serum NO levels, decreased renal MDA levels, and protected rats against I/R-induced kidney injury. Given these in vitro and in vivo findings, ETS-GS is a strong candidate for future exploration of therapeutic potential in various human I/R diseases.
No preview · Article · Feb 2010 · Journal of Surgical Research
[Show abstract][Hide abstract] ABSTRACT: Recent studies have increased our understanding of the important role that the immune system plays in ischemia-reperfusion (I/R) injury. Although dendritic cells (DCs) are important regulators of intestinal immunity, their role in the response to intestinal I/R injury is not well understood. The aim of this study was to determine whether I/R injury affects DC infiltration into the intestinal barrier.
Wistar rats were subjected to I/R injury or a sham operation. Dendritic cells were visualized by immunohistochemistry, and after 12 h of reperfusion protein levels for nucleotide-binding oligomerization domain protein 2 (NOD2), high-mobility group box 1 (HMGB1), and Toll-like receptor 4 (TLR4) were assayed by Western blotting.
The number of DCs increased at the small intestine barrier in response to intestinal I/R. A Western blot analysis of small intestinal tissue revealed that levels of NOD2, HMGB1, and TLR4 protein increased in rats subjected to I/R injury in comparison to control rats.
These results suggest that intestinal I/R increases the infiltration of DCs into the small intestine, thus potentially involving the upregulation of NOD2, HMGB1, and TLR4. Therefore, intestinal I/R might activate DCs through NOD2 and HMGB1.
[Show abstract][Hide abstract] ABSTRACT: Systemic inflammatory response syndromes involving sepsis continue to have extremely high mortality rates. Inflammation is difficult to control when it spreads throughout the body and often progresses into multiple organ dysfunction, eventually leading to death. Cepharanthine (CE) is a plant alkaloid that possesses bioactive properties, with various known actions. In the present study, we investigated protective effects of CE in a lipopolysaccharide (LPS)-induced systemic inflammatory response model and examined underlying mechanisms.
We intravenously administered LPS (7.5 mg/kg) to male Wistar rats after intraperitoneal injections of either physiologic saline (LPS group) or CE (10 mg/kg; CE + LPS group), or 2 h before intraperitoneal injection of CE (post-CE + LPS group). We then compared changes in serum cytokine and nitrogen oxide levels over time, and performed histologic examinations of the lungs and liver in each group. Using mouse macrophage RAW264.7 cells, we determined the effect of CE on LPS-induced cytokine secretion into the cell culture medium, as well as NF-κB activity.
The increase in LPS-induced cytokine levels in rat serum was significantly inhibited by CE treatment; this effect was also seen in the post-CE + LPS group. In addition, we observed histologic improvements with CE co-treatment. In vitro, CE inhibited NF-κB activation by inhibiting the IKK pathway.
These results suggest that CE exerts protective effects, at least in part, via NF-κB inhibition. CE may thus be a potential agent for treating systemic inflammatory response syndromes such as sepsis.
No preview · Article · Feb 2010 · Journal of Surgical Research
[Show abstract][Hide abstract] ABSTRACT: The incidence and prevalence of diabetes have recently increased. Hyperglycemia, which is commonly seen in intensive care medicine, is associated with increased morbidity and mortality. For instance, diabetes is associated with altered immune and hemostatic responses. High mobility group box 1 (HMGB1) protein plays a key role in various inflammatory diseases. This study investigated the increase in lung damage due to diabetes and the rise in HMGB1 levels in a lipopolysaccharide (LPS)-induced systemic inflammation rat model. Diabetes was induced by streptozotocin infusion 4 wk prior to LPS administration, followed by measurements of blood glucose and serum cytokine levels. Separate cohorts were sacrificed 12h post-LPS administration and analyzed for lung damage. Diabetic animals had significantly higher blood glucose and enhanced lung damage. In addition, levels of serum HMGB1, tumor necrosis factor-α, and interleukin-6 were increased in diabetic rats. Diabetes may exacerbate systemic inflammation as evidenced by higher serum HMGB1 and cytokine levels and enhanced lung damage in the rat systemic inflammation model.
No preview · Article · Aug 2009 · Journal of Surgical Research
[Show abstract][Hide abstract] ABSTRACT: Hyperglycemia is frequently observed in nondiabetic patients during acute illness. Furthermore, intensive insulin therapy significantly reduces mortality and morbidity due to several critical illnesses, including cardiac or infectious diseases. The purpose of this study was to determine whether cardiac function is affected by hyperglycemia and its treatment with insulin.
Lipopolysaccharide (LPS) was administered intravenously to rats, with or without the administration of insulin with glucose.
University Medical Center research laboratory.
Male Wistar rats.
In this study, we determined the effect of hyperglycemia and insulin therapy on cardiac function in an LPS-induced systemic inflammation model.
Levels of serum cytokines, nitrate/nitrite, and high-mobility group box 1 protein after LPS treatment were measured in hyperglycemic rats and those treated with insulin. The following parameters were examined to assess cardiac function in Langendorff-perfused hearts: left ventricular developed pressure, left ventricular end-diastolic pressure, and left ventricular pressure development during isovolumetric contraction (+dP/dtmax) and relaxation (-dP/dtmin). We observed that levels of cytokines, nitrate/nitrite, and high-mobility group box 1 significantly increased. However, treatment of hyperglycemic rats with insulin was associated with significantly less severe disease as assessed by cytokine levels. Furthermore, hyperglycemia was associated with decreased +dP/dtmax and -dP/dtmin in Langendorff-perfused hearts of hyperglycemic rats, whereas insulin treatment improved these parameters.
Hyperglycemia was associated with the induction of various inflammatory mediators and an inhibition of cardiac function. Treatment of hyperglycemia with insulin protected against inflammation and cardiac dysfunction in a rat model of LPS-induced systemic inflammation. This improvement is likely because of the neutralization of deleterious effects associated with hyperglycemia and the specific actions of insulin on the inflammatory response.
Full-text · Article · Aug 2009 · Critical care medicine