摘要:

Traumatic injury and its sequelae remains a major, unrecognized, public health problem in North America. It is the principle cause of death in patients aged 1-44 and the overall leading cause of life years lost in the United States. Recognizing this the National Heart, Lung and Blood Institute (NHLBI), in conjunction with other federal agencies, organized a conference in June 2000 to discuss the basic and clinical research projects that could lead to improved outcomes following cardiopulmonary or post-injury resuscitation. The Post Resuscitative and Initial Utility of Life Saving Efforts (PULSE) Workshop resulted and eight workgroups were established to focus on various aspects including organ systems, pharmacology, epidemiology, and trauma. The Trauma Work group recommendations are presented in this manuscript. Despite the recognition of improved survival and outcome through advancements in trauma systems and trauma care, the National Institutes of Health (NIH) support ratio for trauma research is only 0.10 compared to 1.65 for cancer research and a remarkable support ratio of 3.51 for AIDS and HIV infection research. The successful federal HIV research program has significantly decreased the morbidity and mortality over the last ten years at a cost of 1.4 billion dollars per year. A coordinated trauma research program should aim to replicate the success achieved by such programs; however, a centralized federal “home” for trauma research does not exist. Consequently, the existing limited research support is derived from NIH institutes in addition to other federal and state agencies. This report serves to describe some of the obstacles and to outline various strategies and priorities for basic science, clinical and translational trauma resuscitation research.

ISSN:1073-2322    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Chemokines mediate the migration of leukocytes to sites of inflammation. Changes in the plasma concentration of interleukin (IL)-8 and macrophage inflammatory protein (MIP)-1&bgr; have not been investigated in the very early phase starting immediately after unintentional trauma. Enrolled in the study were 94 patients with multiple blunt injuries. Blood samples were collected at the scene of accident, then at regular intervals for 24 h. IL-8 and MIP-1&bgr; plasma levels were determined by commercial test kits. Patients were grouped according to trauma severity, pattern of injury, as well as survivors vs. nonsurvivors. Serious casualties [Injury Severity Score (ISS) ≧ 32] revealed a significant increase in IL-8 compared to only a slight elevation in individuals with an ISS < 32. Nonsurvivors showed a highly significant(P< 0.005) increase in IL-8 levels beginning immediately after admission. Trauma resulted in a modest activation of MIP-1&bgr; production without differences regarding trauma severity, pattern of injury, or survival. A very strong trauma stimulus is necessary to activate IL-8 production. In contrast to MIP-1&bgr;, IL-8 levels were significantly elevated in nonsurvivors compared to survivors. Therefore, IL-8 might be an early predictor of survival.

ISSN:1073-2322    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Platelet activating factor (PAF) is a key proinflammatory mediator of septic shock and is metabolized by PAF-acetylhydrolase (PAF-AH). Low circulating levels of PAF-AH have been associated with the development of autodestructive excessive inflammatory responses such as post-injury multiple organ failure, and recombinant PAF-AH is being studied for the prevention of acute respiratory distress syndrome (ARDS). However, the potential role of PAF as an autocrine mediator of macrophage activation is unclear. We wanted to examine the role of PAF in the endotoxin- (LPS) induced macrophage response using PAF-AH. Rabbit alveolar macrophages were stimulated with LPS (10 ng/mL) with or without PAF-AH (0.1–10 &mgr;g/mL). Supernatants were collected to measure the production of tumor necrosis factor (TNF), interleukin 8 (Il-8), and prostaglandin E2 (PGE2). Cell monolayers were assessed for procoagulant activity (PCA). TNF mRNA production was determined by Northern blot and RNA stability was assessed. Evaluation of intracellular signaling pathways for LPS included western blots for phosphorylated p38 and ERK kinases and gel shift for nuclear factor-&kgr;B. There was a dose-response inhibition of TNF, PCA, Il-8, and PGE2 production following pretreatment with PAF-AH. Time course studies revealed effective inhibition of TNF production with administration of PAF-AH up to 2 h after LPS challenge. TNF mRNA production was inhibited, while mRNA stability was not affected. There was no effect on the phosphorylation of p38 or ERK 1 kinases; however, the nuclear translocation of NF-&kgr;B was inhibited. Macrophage cytokine production in response to endotoxin is PAF dependent. This effect involves the inhibition of TNF gene transcription and concomitant inhibition of NF-&kgr;B.

ISSN:1073-2322    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Studies indicate that endotoxin (LPS) causes intestinal injury, increases inducible nitric oxide synthase (iNOS) activity, leads to increased NO production, and promotes bacterial translocation (BT). To investigate the mechanism by which LPS causes gut injury and to test the hypothesis that NO produced by enterocytes promotes gut injury in an autocrine fashion, rat intestinal epithelial cell (IEC-6) monolayers were tested. IEC-6 monolayers grown in a bicameral system were incubated with media or with LPS (25 &mgr;g/mL) and tested for permeability to phenol red, BT, and nitrate/nitrite (NO2/NO3)production. To determine the direct effect of NO on permeability, monolayers were incubated with the NO donorS-nitroso-acetylpenicillinamide (SNAP; 1 mM) and tested for permeability. Next, the protective effects of two NOS inhibitors (L-NMMA and L-NIL) were tested. Finally, to determine if LPS-induced permeability occurs via a poly (ADP-ribose) synthetase- (PARS) dependent pathway, monolayers incubated with LPS alone or with the PARS inhibitor, INH2BP (100 &mgr;M) were tested. LPS significantly increased IEC-6 permeability to phenol red, as well as increased NO2/NO3by 20-fold (P< 0.001) and increased BT 10-fold (P< 0.001). SNAP mimicked the effect of LPS and significantly increased both permeability to phenol red and BT. Inhibition of iNOS significantly decreased the LPS-induced increase in monolayer permeability and BT (P< 0.05). Monolayers incubated with INH2BP had significantly decreased permeability to phenol red and BT, suggesting that LPS-induced NO production increases monolayer permeability at least in part via a PARS-dependent mechanism. In summary, LPS-induced disruption of monolayer barrier function appears to be related, at least in part, to enterocyte produced NO. This supports the hypothesis that NO produced by LPS-stimulated enterocytes promotes injury in an autocrine fashion and highlights the fact that enterocytes can be a target as well as a producer of NO.

ISSN:1073-2322    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Besides necrosis, apoptosis is the other major mode of cardiomyocyte loss in ischemic cardiovascular disease. In the present study, we examined the hypothesis that nitric oxide (NO) protects myocardial function by improving myocardial microcirculation and attenuating cardiomyocyte apoptosis in a rat model of myocardial ischemia/reperfusion (MI/R). The left main coronary artery of anesthetized male rats was ligated for 40 min, followed by 4 h reperfusion. Four groups of animals were studied: sham operated control + saline; sham operated control + NW-nitro-L-arginine methyl ester (L-NAME); MI/R + saline; MI/R + L-NAME (10 mg/kg,iv, 10 min prior to reperfusion). Results show that MI/R caused a decrease in mean arterial blood pressure (MABP), cardiac index (CI), and stroke volume index (SVI). Inhibition of NO synthesis by L-NAME attenuated plasma NO levels, but increased MABP and SVR in sham control rats and rats subjected to MI/R, and further depressed left ventricular function in rats subjected to MI/R as indicated by decreased CI and SVI. Furthermore, administration of L-NAME to rats subjected to MI/R enhanced cardiomyocyte apoptosis as indicated by a significant increase in DNA fragmentation compared to rats with MI/R alone. Histological study revealed that L-NAME caused arterial constriction and congestion of red blood cells in arteries and capillaries in the peri-ischemic areas of the hearts in rats subjected to MI/R and, interestingly, also in the sham control rats. Data suggest that the mechanism of increased reperfusion injury may be attributable to a “no-reflow” phenomenon induced by L-NAME, resulting in increased cardiomyocyte apoptosis secondary to ischemia and enhanced cytochrome-c release from mitochondria. In addition, cardiac injury may be increased due to the augmented oxygen consumption of cardiomyocytes caused by the increased SVR and afterload. These results suggest that endogenous NO may act to improve myocardial microvascular perfusion, reduce SVR, and limit cardiomyocyte apoptosis, thereby, attenuating myocardial dysfunction induced by MI/R.

ISSN:1073-2322    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

The present study was designed to test the hypothesis that induction of chronic peritoneal sepsis in rats would produce a more severe calcium paradox-mediated myocardial injury in isolated heart preparation than is seen in normal hearts, and that this would be inhibited by sucrose as in normal hearts. Male Sprague-Dawley rats were made septic using 200 mg of cecal material (obtained from a donor rat) suspended in 5 mL of 5% dextrose in sterile water (1) D5W/kg. In septic animals, the cecal material was injected in the peritoneum, while sham-septic animals received only D5W/kg (5 mL/kg). A third group consisting of normal rats (no surgery) group was also included. Hearts were harvested from all three groups and were subjected to a calcium paradox-mediated injury in an isolated heart preparation. Hearts were perfused with Krebs-Henseleit (KH) medium and were allowed to stabilize, followed by a perfusion with Ca2+-free KH for 10 min. After this 10-min Ca2+-free KH perfusion, rats were reperfused with KH medium for 60 min. Ca2+-free KH medium was used in control experiments, while sucrose experiments were conducted with the same medium except that 150 mM sucrose replaced 75 mM NaCl. A marked decrease in ATP and phosphocreatine occurred during Ca2+reperfusion in all hearts in absence of sucrose. In the presence of the disaccharide, no change in high-energy phosphate (HEP) levels was observed in normal hearts, while lower ATP concentrations were seen in sham and septic hearts. Thus, sucrose did not inhibit cellular injury in sham and septic hearts as it did in normal hearts, and this might be due to a smaller HEP availability. Control studies with normal, sham, and septic hearts exhibited cessation of contractions in the absence of Ca2+, and appearance of large amounts of cytosolic protein in the effluent perfusate during Ca2+reperfusion. With normal hearts, perfusion with sucrose caused a 96% inhibition of the total creatine kinase (CK) release observed in control experiments. With sham hearts, 32% of CK release was inhibited by sucrose, while 68% of the CK release was attributed to stress associated with surgery performed in the sham-septic group. In septic hearts, only 8% of the CK release was inhibited by sucrose, suggesting that more severe myocardial injury occurs when septic hearts are subjected to a calcium paradox as compared to other groups. It is evident that sucrose can inhibit a small fraction of the CK release from septic hearts during the calcium paradox as compared to the large CK loss associated with sham sepsis. We have concluded that induction of sepsis made the heart more susceptible to a calcium paradox-mediated myocardial injury.

ISSN:1073-2322    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Significant hepatic dysfunction occurs following endotoxin administration. Although the metabolism of lidocaine to one of the primary metabolites of lidocaine, monoethylglycinexylidide (MEGX), has been used as a marker of hepatic function under various conditions, it remains unknown whether these compounds can be usedin vivoto evaluate hepatic function in a rat model of endotoxic shock. To study this, cytochrome P450-3A4 (CYP3A4) was determined after harvesting hepatic microsomes, hepatic blood flow was determined using radioactive microspheres, and the pharmacokinetics of lidocaine and MEGX were evaluated. Adult male Sprague-Dawley rats were divided into endotoxin (45 mg/kg, intraperitoneally; n = 28) or control (n = 32) groups. The CYP3A4 was significantly reduced after endotoxic shock. Carboxylesterase (hydrolase S) content, which was used as a control for microsomal protein, was not significantly different between groups. Total hepatic blood flow was significantly decreased (36.2 ± 8.4 mL/min/100 g tissue vs. 120.4 ± 10.6 mL/min/100 g tissue), which was due to the decreased portal blood flow. For the lidocaine and MEGX experiment, lidocaine (2 mg/kg) was administered followed by serial blood samples collected up to 2 h for determination of serum lidocaine and MEGX concentrations. Mean arterial pressure (MAP) was recorded throughout the experiment. The MAP was significantly lower in the endotoxin treated rats vs. control 7.5 to 8 h following endotoxin administration. Serum concentrations of lidocaine were higher in endotoxic shock versus control animals at 2 h following lidocaine administration (1.5 ± 0.13 mg/L vs. 0.11 ± 0.03 mg/L). Similarly, MEGX concentrations were significantly higher in endotoxic shock versus control animals (0.55 ± 0.04 mg/L vs. 0.16 ± 0.02, respectively) under such conditions. These data demonstrate that the elimination of lidocaine and MEGX is impaired during endotoxic shock. The elevated lidocaine and MEGX concentrations are likely to be the result of primarily reduced hepatic blood flow and secondarily due to impaired CYP450, one of which was CYP3A4. The reduced elimination of MEGX concentrations is not due to decreased hepatic metabolism of the compound via carboxylesterase. The ratio of MEGX to lidocaine concentrations, which decreased significantly following endotoxic shock, appears to be a useful measure of hepatic function during endotoxic shock where profound reductions of hepatic blood flow are observed in addition to significant reductions in CYP450. The use of only MEGX concentrations in this endotoxic shock model is not useful in evaluating liver function.

ISSN:1073-2322    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Our recent evidence suggests that pancreatic digestive enzymes in the lumen of the intestine may play a major role in the production of cardiovascular stimulatory factors during splachnic artery occlusion and reperfusion. These stimulators are detected in plasma, but their origin and mechanism of production has remained uncertain. We examine here in the rat the role of pancreatic enzymes with and without administration of a serine protease inhibitor (FOY) into the lumen of the small intestine during splanchnic artery occlusion (90 min) and reperfusion (120 min). In the presence of pancreatic enzyme inhibition in the lumen of the intestine, there is significantly enhanced survival rate, lower levels of inflammatory mediator production, the femoral artery blood pressure is maintained close to control levels, and there are significantly lower levels of cell activators in plasma. These results support the hypothesis that pancreatic enzymes may escape across the brush border barrier during intestinal ischemia and thereby initiate the production of a powerful set of cytotoxic mediators. Blockade of pancreatic enzymes in the lumen of the intestine may be a tool to interfere with inflammation and early indicators of multiorgan failure.

ISSN:1073-2322    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

The free radical trapping compound phenylN-tert-butylnitrone (PBN) provides potent protection against lethal endotoxemia in rodents, but the mechanism of this protection is not well understood. The objective of this study was to show that PBN administration in lipopolysaccharide- (LPS) induced endotoxemia promotes enhanced production of endogenous interleukin 10 (IL-10), and the expressed IL-10 is a causal factor in the protection from endotoxemia. We show the amplified expression of IL-10 in liver and plasma in PBN- (150 mg/kg) plus LPS- (4 mg/kg) treated rats using ribonuclease protection assay (RPA) and ELISA.In situhybridization was utilized to visualize the overexpression of the IL-10 gene, and ELISA was used to determine plasma IL-10 and TNF&agr; levels. Plasma IL-10 showed a 3-fold increase in PBN/LPS-treated rats compared to those treated with LPS alone, and in contrast, TNF&agr; level decreased by more than 90%. However, the administration of PBN alone induced no IL-10 production. Immunoneutralization of IL-10 through anti-IL-10 antibody administration to PBN/LPS-treated rats abrogated PBN's suppression of systemic nitric oxide (NO) formation, a surrogate marker for the severity of endotoxemia, indicating that IL-10 is a causal factor for the protection. In these experiments, systemic NO level was quantified using anin vivoelectron paramagnetic resonance (EPR) NO-trapping technique. Gel-shift and immunohistochemical analyses indicated that the transcription factor NF-&kgr;B was deactivated after PBN treatment, suggesting that NF-&kgr;B deactivation is closely involved in IL-10 overexpression.

ISSN:1073-2322    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Immune system cytokines induce vascular shock. Tumor necrosis factor-&agr; (TNF-&agr;), interleukin 1&bgr; (IL-1&bgr;), and bacterial endotoxin (E) circulate in human heatstroke to suggest that E release from a heat-damaged gut may stimulate cytokines that contribute to hypovolemia. However, immune activation by heat-induced tissue necrosis might stimulate cytokine generation in the absence of E. To evaluate this potential and heat stress effects on the anti-inflammatory cytokines, IL-1 receptor antagonist (IL-1ra) and IL-1 soluble receptor II (IL-1srII), a human whole blood (HWB) model was employed in which the presence or absence of E could be controlled. Using thermoelectric technology to regulate the HWB heat exposures, the temperature modulations of lethal heatstroke were precisely replicated (maximum temperature = 42.4°C ± 0.04°C; thermal area = 52.3°C ± 1.5°C per min). Cytokine and mRNA measurements employed enzyme-linked immunosorbant-based assay systems. Significant elevations in TNF-&agr;, IL-1&bgr;, interleukin 6 (IL-6), and IL-1ra resulted when HWB was exposed to E concentrations (10 ng/ml) reported to circulate in heatstroke. While E-stimulated IL-1ra was significantly decreased by the presence of prior heat stress (PPHS), E-stimulated IL-1&bgr;, TNF-&agr;, and IL-6 were not significantly altered by PPHS, but tended to be elevated. IL-1srII expression was unchanged by PPHS and/or E. PPHS in the absence of E did not induce cytokine responses, nor were there elevations in TNF-&agr; or IL-1&bgr; mRNA. Thus, some factor normally absent underin vitroconditions, like endotoxin, was required to provoke HWB cytokine expressions and the heat stress and E conditions that characterize heatstroke affected HWB cytokine metabolism to favor a proinflammatory environment.

ISSN:1073-2322    

出版商:OVID    

年代:2002

数据来源: OVID