Kai-Yang Lv

Activation of p38 MAPK by Reactive Oxygen Species Is Essential in a Rat Model of Stress-Induced Gastric Mucosal Injury

Stress ulceration is a common complication in critically ill patients and can result in significant upper gastrointestinal bleeding associated with a high morbidity and mortality. At present, little is known of the molecular mechanisms underlying the incidence of this type of gastric damage. In the present study, we investigated the temporal activation of the redox-sensitive p38 signaling transduction cascade and its roles in a well-defined experimental model of cold immobilization stress-induced gastric ulceration. Exposure of Sprague-Dawley rats to 6 h of cold immobilization stress led to a rapid activation of p38 in the gastric mucosa at as early as 15 min after stress, and this activation was maximal after 1.5 h of stress and still persisted until the end of stress. Selectively blocking p38 by pretreatment with SB 239063, a potent and selective p38 inhibitor, suppressed the stress-promoted TNF-α, IL-1β, and CINC-1 production and then prevented the subsequent neutrophil infiltration, gastric mucosal epithelial necrosis and apoptosis, and the ulcerative lesions formation. Prior administration of the free radical scavengers, tempol and N-acetyl-l-cysteine, abolished the stress induction of p38 activation and the resulting mucosal inflammation and gastric injury. These results demonstrate that reactive oxygen species-mediated p38 activation plays an essential role in the pathogenesis of stress-induced gastric inflammatory damage in the rat model of cold immobilization stress. Our findings suggested that inhibition of p38 activation might be a potential strategy for the prophylaxis and treatment of stress ulceration.

TLR4 Mediates Lung Injury and Inflammation in Intestinal Ischemia-Reperfusion

BACKGROUND Splanchnic ischemia is common in critically ill patients, and it can result in injury not only of the intestine but also in distant organs, particularly in the lung. Local inflammatory changes play a pivotal role in the development of acute lung injury after intestinal ischemia, but the underlying molecular mechanisms are not fully understood. We sought to examine the role of Toll-like receptor 4 (TLR4) in the mouse model of intestinal ischemia-reperfusion (I/R)-induced lung injury and inflammation. MATERIALS AND METHODS Adult male TLR4 mutant (C3H/HeJ) mice and TLR4 wild-type (WT) (C3H/HeOuJ) mice were subjected to 40 min of intestinal ischemia by clamping the superior mesenteric artery followed by 6 h of reperfusion. Lung histology was assessed and parameters of pulmonary microvascular permeability, inflammatory cytokine expression, and neutrophil infiltration were measured. Activation of mitogen-activated protein kinases (MAPKs) and the transcription factors nuclear factor κB (NF-κB) and activator protein-1 (AP-1) in the lungs were also detected. RESULTS After intestinal I/R, lungs from TLR4 mutant mice demonstrated a significantly lower histological injury, a marked reduction of epithelial apoptosis associated with the decreased level of cleaved caspase-3 and the increased ratio of Bcl-xL to Bax proteins, and a large reduction in pulmonary vascular permeability and myeloperoxidase (MPO) activity in comparison with WT mice. TLR4 mutant mice also displayed marked decreases in tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and macrophage inflammatory protein-2 (MIP-2) expression. Following intestinal I/R, phosporylation of p38 MAPK and activation of NF-κB and AP-1 were significantly inhibited in lung tissue from TLR4 mutant mice compared with WT controls. CONCLUSIONS These data suggest that TLR4 plays an important role in the pathogenesis of intestinal I/R-induced acute lung injury and inflammation and that p38 kinase and NF-κB may be involved in TLR4 signaling-mediated lung inflammatory processes during intestinal I/R.

Factors affecting survival in adult patients with massive burns

OBJECTIVE To identify treatment-related factors associated with mortality in massively burned adult patients. METHODS This retrospective cohort study examined survival outcomes at a burn unit of 54 beds and 10 burn ICU beds, totaling 900 admissions per year. The cases of 102 adult patients, admitted consecutively from January 1993 to October 2007, with massive burns (burn area>70% of the total body surface area, TBSA) were studied. Relevant variables were recorded from the initial injury and throughout the hospital course. Survival analysis, based on univariate and stepwise multivariate Cox proportional hazards regression, was performed to determine which variables predicted mortality. RESULTS The overall mortality rate was 30.4%. Burn size, severe inhalation injury, full-thickness burns, serum creatinine levels, inotropic support, platelet counts<20,000 per mm3, sepsis and ventilator dependency were significantly associated with mortality as determined by univariate analysis. Only sepsis, ventilator dependency and platelet counts were significant independent predictors of mortality as determined by multivariate analysis. CONCLUSIONS Sepsis, ventilator dependence (indicating severe respiratory complications), and low platelet counts (indicating thrombocytopenia) are associated with increased mortality risk in adult patients with massive burns. Methods should be sought to ameliorate these complications during treatment in burn-care units.

Notoginsenoside R1 attenuates renal ischemia-reperfusion injury in rats.

Ischemia-reperfusion (I/R) injury of the kidney is a complex pathophysiological process and a major cause of acute renal failure. It has been shown that I/R injury is related to inflammatory responses and activation of apoptotic pathways. Inhibition of certain elements of inflammatory responses and apoptotic pathway seemed to ameliorate renal I/R injury. As an effective element of Panax notoginseng, NR1 has antioxidant, anti-inflammatory, antiapoptotic, and immune-stimulatory activities. Therefore, we speculate that NR1 can attenuate renal I/R injury. Ischemia-reperfusion injury was induced by renal pedicle ligation followed by reperfusion along with a contralateral nephrectomy. Male Sprague-Dawley rats were randomized to four groups: sham group, I/R control group, NR1-1 group (rats treated with NR1, 20 mg·kg−1·d−1) and NR1-2 group (rats treated with NR1, 40 mg·kg−1·d−1). All animals were killed 72 h after I/R induction. Blood and renal tissues were collected. Renal dysfunction was observed by the level of serum creatinine and histological evaluation. Apoptosis and inflammatory response in the tissue of kidney were detected mainly with molecular biological methods. NR1 attenuated I/R-induced renal dysfunction as indicated by the level of serum creatinine and histological evaluation. It prevented the I/R-induced increases in the levels of proinflammatory cytokine TNF-&agr;, myeloperoxidase activity, phosphorylation of p38, and activation of nuclear factor &kgr;B with cell apoptosis in the kidney and enhanced expression of antiapoptosis cytokine bcl-2. Treatment with NR1 improves renal function after I/R associated with a significant reduction in cell apoptosis and inflammatory responses, which may be related to p38 and nuclear factor &kgr;B inhibition.

Different normalization strategies might cause inconsistent variation in circulating microRNAs in patients with hepatocellular carcinoma.

Background Circulating microRNA (miRNA) are promising biomarkers for diagnosing and prognosticating numerous diseases. Reports have demonstrated controversial or even contradictory conclusions in studies on circulating microRNA. This study aimed to evaluate the potential bias of using different reference genes for analyzing circulating microRNAs in the same malignant digestive diseases. Material/Methods We measured plasma concentrations of U6-snRNA, let-7a, miRNA-21, miRNA-106a, miRNA-155, miRNA-219, miRNA-221, and miRNA-16 in patients with hepatocellular carcinoma (HCC), gastric carcinoma (GC), hepatic cirrhosis, hepatitis B, and healthy volunteers using quantitative real-time polymerase chain reaction (qPCR). The GeNorm, Normfinder, BestKeeper, and Comparative ΔCq algorithms integrated in RefFinder were used to screen the most suitable reference genes from the candidates. The 4 commonly used statistical evaluation software packages provided different results regarding the stability of the candidate reference genes. Results RefFinder revealed miRNA-106a and miRNA-21 as the most stably expressed reference genes, with comprehensive stability values of 1.189 and 1.861, respectively. U6-snRNA was the most unstable nucleic acid in our data. When 5 normalization strategies were compared using U6-snRNA, serum volume, miRNA-106a, miRNA-21, or the mean value of miRNA-106a and miRNA-21, obvious expression bias was detected in almost all target microRNAs. Intriguingly, all these normalization strategies indicated that circulating miRNA-155 is greatly upregulated in patients with HCC and GC, but downregulated in benign hepatic disease. Conclusions Single reference genes used without justification in plasma microRNAs produce significant analysis bias or even erroneous results. Circulating miRNA-155 may be a promising non-invasive biomarker for discriminating malignant digestive tumors from the corresponding benign diseases.

Angiotensin II induces type I collagen gene expression in human dermal fibroblasts through an AP-1/TGF-β1-dependent pathway

Angiotensin II is critically involved in skin wound healing, but the underlying mechanism remains unclear. This study investigated the effect of angiotensin II on type I collagen gene activation in human dermal fibroblasts and the possible mechanism involved. Angiotensin II stimulated the mRNA and protein expression of type I collagen and TGF-beta1. Effects were abolished by the angiotensin AT1 receptor antagonist ZD7155 but not by the AT2 blocker PD123319. Blockade of TGF-beta1 markedly inhibited angiotensin II-induced type I collagen gene expression. Activator protein-1 (AP-1) decoy ODNs transfection suppressed angiotensin II-induced TGF-beta1 expression, and also, diminished type I collagen expression. These data indicated that angiotensin II induces collagen gene activation in human dermal fibroblasts through an AT1-mediated AP-1/TGF-beta1 signaling pathway.

Role of inhibition of p38 mitogen-activated protein kinase in liver dysfunction after hemorrhagic shock and resuscitation

BACKGROUND The liver is one of the organs most frequently affected by trauma and hemorrhagic shock; the exact role of p38 mitogen-activated protein kinase (MAPK) activation in response to hepatic hemorrhagic shock/resuscitation (HS/R) remains unclear. MATERIALS AND METHODS C57Bl/6 mice were divided into four groups: sham-operated group, SB-only group, control group, and SB + HS/R group. Hepatocellular injury (aspartate aminotransferase [AST] and alanine aminotransferase [ALT]) and tumor necrosis factor (TNF-α) and interleukin (IL-1β) messenger ribonucleic acid (mRNA) expression in the liver were assessed 6 h after resuscitation, p38 MAPK activation in the liver was assessed at 30 min after resuscitation. RESULTS p38 MAPK activation was higher in the control group than other groups 30 min after resuscitation. p38 MAPK activation level in the SB + HS/R group did not change significantly compared with that of sham and SB-only groups, but was significantly lower than that in the control group. The TNF-α mRNA expression in the control group was significantly higher than that in the sham group. The TNF-α mRNA levels after HS/R in the SB + HS/R group were significantly lower than those in the control group and were roughly the same as those in the sham and SB-only groups. IL-1β mRNA expression showed similar changes in the four groups. Serum ALT and AST levels in the control group were significantly higher than those in the sham group. The increase in serum ALT and AST levels after HS/R in the SB + HS/R group was significantly less pronounced than that in the control group and markedly higher than that in the sham group. CONCLUSIONS p38 MAPK was phosphorylated during the HS/R process. Inhibiting the activation of p38 MAPK may attenuate HS/R injury to the liver.

Pathogenic alteration in severe burn wounds

The present study aims to define the trend of time related changes with local bacterial alteration of bacterial resistance in severe burns in our burn center during a 12-year period. Retrospective analysis of microbiological results on severely burned wounds between 1998 and 2009 was carried out. A study of 3615 microbial isolates was performed. Staphylococcus aureus was the most commonly isolated pathogen (38.2%) followed by A. baumannii (16.2%), Streptococcus viridans (11.4%), Pseudomonas aeruginosa (10.4%), coagulase-negative staphylococci (CNS, 9.2%). The species ratios of S. aureus and A. baumannii increased significantly from 1st to 8th week of hospitalization, while those of Streptococcus viridans, P. aeruginosa and coagulase-negative staphylococci decreased during the same period. Bacterial resistance rates were compared between the periods 1998-2003 and 2004-2009. Vancomycin remained as the most sensitive antibiotic in S. aureus including methicillin-resistant S. aureus (MRSA). It was very likely that the majority of infections caused by Streptococcus viridans, P. aeruginosa and coagulase-negative staphylococci occurred in the early stage of burn course and the majority of infections caused by A. baumannii occurred 4 weeks after admission. The use of different antibiotics was probably the major contributor to these trends.

Epidemiology and Outcome Analysis of Severe Extensive Burns: A 12-Year Summary of 103 Cases in a Burn Center in China

The purpose of this article is to improve the treatment of severe extensive burns (SEB) patients by summarizing treatment experience in recent 12 years in China and analyzing the follow-up quality of life (QOL) in these patients. Clinical data and rescue measures of 103 SEB patients (≥70% TBSA) admitted in a burn center in Shanghai between 1997 and 2009 were reviewed, and QOL and hand function of those who survived more than 2 years were assessed by Brief Version of Burn Specific Health scale-B and Michigan Hand Outcome Questionnaire. Of these, 76.7% were caused by flames and 15.5% caused by scald. The median burn area was 87.5% (interquartile range, 77.0–95.0%) TBSA, of which third-degree burns accounted for 56.5% (interquartile range, 25.8–80.0%) TBSA; 71.8% were complicated by inhalation injury. The occurrence of in-hospital complications was 75.7%, with the respiratory system complications predominating (49.5%). The fatality rate was 28.2%, mainly due to sepsis and multiple organ dysfunction syndrome. Work, body image, and heat sensitivity got the lowest Brief Version of Burn Specific Health scale-B scores in all nine domains, and Michigan Hand Outcome Questionnaire scores were also relatively poor. Flame burns remain to be the main cause of SEB in China in recent 12 years. Treatment is still challenged because of the depth and extensive burn area and high occurrence of multiple system complications. How to ameliorate QOL of SEB patients, intensify the functional rehabilitation, and improve their physical appearance in particular remain to be a crux.

Deficiency of Smad3 results in enhanced inducible nitric oxide synthase–mediated hypotension in lipopolysaccharide-induced endotoxemia

BACKGROUND Smad3 is a principal intracellular mediator of signaling for transforming growth factor β, a cytokine involved in pleiotropic pathophysiological processes including inflammation and immunity. The function of Smad3 in regulating inducible nitric oxide synthase (iNOS) expression and septic shock has not been characterized. METHODS Smad3(-/-) (referred hereafter as KO) and wild-type (WT) mice were injected intraperitoneally with lipopolysaccharide (LPS) to induce the septic hypotension. Mortality, blood pressure, and plasma levels of nitrite were measured. The iNOS messenger RNA and protein levels in lung, kidney, and spleen were also analyzed. RESULTS Mice lacking functional Smad3 respond to LPS with greater mortality than their WT littermates. The high mortality of KO mice is accompanied by enhanced hypotension after intraperitoneal injection of LPS. Both KO and WT mice displayed an increase in plasma nitrite during the experimental period; however, LPS administration caused more dramatic changes in KO mice than WT mice. Likewise, the iNOS messenger RNA and protein levels in lung, kidney, and spleen were more strongly increased in KO mice than in WT mice after LPS administration. CONCLUSIONS Defects in the Smad3 gene may increase susceptibility to the development of septic hypotension because of enhanced iNOS production.