摘要:

ABSTRACTPostinjury neutrophil (PMN) dysfunction is a well recognized event that may be responsible for increased infections. PMN cytokine production is an important component of their bactericidal capacity. When PMNs are stimulated, inhibitory factor KB (IKB) is degraded, allowing nuclear factor KB (NFKB) to translocate to the nucleus and promotes genes for the transcription of the interleukin-8 (IL-8) and tumor necrosis factor (TNF) genes. We hypothesize that similar to their late postinjury depressed superoxide production, postinjury PMNs manifest suppressed cytokine production, which is mediated by stabilization of IKB levels. Methods: Twelve severely injured patients with an injury severity score (ISS) of 24 (±4.6) were studied as well as 10 elective surgical patients as a control. PMNs were isolated and incubated for 24 h in RPMI. PMNs were stimulated with lipopolysaccharide (LPS; 100 ng) or PAF (200 nm) and fMLP (1 ±M) and release of IL-8, TNF, and interleukin-1 receptor antagonist (IL-1 ra) were measured. Postinjury PMNs were also stimulated with LPS (100 ng), and IkB breakdown was measured at 0, 30, and 60 min using gel electrophoresis. Results: Postinjury PMNs displayed a significant suppression of both IL-8 and TNF on postinjury Days 1–3, while the release of IL-1ra was preserved throughout the entire study period. In contrast, elective surgical patients demonstrated no decrease in IL-8 or TNF. Furthermore, IKB levels were preserved in the postinjury PMNs as compared with normal control PMNs. Conclusion: Postinjury PMNs have a suppressed release of both IL-8 and TNF following injury that did not occur in elective surgical patients. Furthermore, the NFKB/IKB-independent IL-1ra did not show suppression of release. In addition, stabilization of IKB following severe injury leads to decreased PMN IL-8 and TNF production. This genetic reprogramming may help explain PMN dysfunction and subsequent infections seen in severely injured patients.

ISSN:1073-2322    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ABSTRACTPolymyxin B (PLB) is a cationic antibiotic that also stoichiometrically neutralizes the lipid A moiety of endotoxin. We examined effects of a small dose of PLB on the mortality of rats with cecal ligation and puncture, on LPS-stimulated nitric oxide (NO) production, and on tumor necrosis factor a (TNF±) production by isolated rat Kupffer cells. Materials and Methods: In vivo studies: Cecal ligation and puncture (CLP) was performed under anesthesia in 28 rats. One hour after CLP, either 600 U/kg of PLB or saline was administered intramuscularly every 6 h (PLB group: n = 12; control group: n = 16). Plasma endotoxin was measured at 3 and 24 h after the CLP by the Endospecy test. This was compared with survival. In vitro studies: Kupffer cells were isolated from the normal rat liver. The cells were incubated with LPS or LPS+PLB. After 24 h, NO and TNF± content were measured using the Griess and ELISA methods, respectively. Results: Low dose PLB significantly decreased the endotoxin levels at both 3 and 24 h (5.5 ±2.1 pg/mL vs. 32.8 ± 3.6 at 3 h; 26.1 ± 6.1 vs. 49.1 ± 5.6 at 24 h (p < .05) after CLP. PLB significantly improved survival of CLP rats (68.8% in the control group vs. 100% in the PLB treated group on 3 days after CLP, p < .001). PLB also attenuated NO and TNF± production from the Kupffer cells. Conclusion: Intramuscular PLB administered in low doses may improve the mortality of sepsis.

ISSN:1073-2322    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ABSTRACTHemorrhage is known to induce the production of inflammatory cytokines such as interleukin-6 (IL-6). IL-6 plays an intermediate role as a factor in the activation of coagulation cascade and exerts a lethal effect in sepsis. To examine the effect of endogenous IL-6 on blood loss, we performed four experiments in female ddY mice. Enzyme immunoassay using an uncontrolled hemorrhage model, i.e., 75% tail resection, revealed the production of serum IL-6 (Experiment 1). We also measured cumulative blood loss and survival rate (Experiment 2); measured blood pressure and performed thrombelastogram (TEG) (Experiment 3); and measured plasma thrombin-antithrombin III (TAT) complex levels in two groups, one pretreated with 1 mg of anti-IL-6 monoclonal antibody (mAb), and one with normal rat globulin (NRG) using the same model (Experiment 4). The mAb group showed a significantly higher blood loss than the NRG group. All mice survived for 5 days in both groups. Blood pressure did not differ between either group. The TEG results suggest that administration of anti-IL-6 mAb caused mild suppression of coagulation activation, but did not affect fibrinolysis or platelets. In the mAb group, plasma TAT complex concentrations showed a significant decrease compared with the NRG group. In conclusion, hemorrhage-induced IL-6 may contribute to hemostasis through activation of coagulation, thus reducing blood loss.

ISSN:1073-2322    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ABSTRACTTumor necrosis factor-± (TNF-±) and interferon-± (IFN-±), potent inflammatory cytokines, are released by macrophages during endotoxin shock. However, the contribution of these cytokines to endotoxin-induced inflammation has not been defined. The expression of E-selectin, measured using the dual radiolabeled monoclonal antibody (mAb) technique, was monitored in different tissues of endotoxin-challenged wild-type and IFN-±-deficient mice receiving a mAb to TNF-± (TN3). A significant elevation in E-selectin expression occurred in all tissues of wild-type mice challenged with endotoxin. Injection of TN3 in wild-type mice significantly attenuated the endotoxin-induced up-regulation of E-selectin in all tissues (p < .05) except the pancreas. The level of reduction in endotoxin-induced E-selectin expression ranged between 30% in the stomach to 60% in the small intestine. E-selectin expression in endotoxin-challenged, IFN-±-deficient mice was significantly reduced in the small and large intestines, when compared with endotoxin-challenged wild-type mice. Although IFN-± deficiency had no effect on E-selectin expression in other tissues, administration of TN3 to endotoxin-challenged, IFN-±-deficient mice significantly reduced E-selectin expression to levels observed in endotoxin-challenged, wild-type mice that received TN3. These findings indicate that TNF-± is essential for achievement of maximal E-selectin expression in most vascular beds during endotoxemia, whereas the contribution of IFN-± is largely confined to the small intestine.

ISSN:1073-2322    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ABSTRACTOverproduction of NO by an inducible NO synthase (iNOS) plays a role in the pathophysiology of septic shock. In such situations, NOS inhibition might be of therapeutic value, although detrimental side effects possibly related to inhibition of constitutive NOS have been reported. The use of L-canavanine, a selective inhibitor of iNOS, might be more suitable. The aim of the study was to compare in a rodent endotoxic shock the effects of saline (2 mlVh), NG-methyl-L-arginine(L-NMMA) (10 mg/kg/h) and L-canavanine (100 mg/kg/h) on muscle intracellular pH (pHi) and intracellular bioenergetic patterns (ATP, phosphocreatine/inorganic phosphate ratio) using in vivo31P magnetic resonance spectroscopy (31P MRS). Three groups of anesthetized, mechanically ventilated and paralyzed rats received an intravenous infusion of 15 mg/kg of endotoxin. A fourth time-matched control group (n = 8) received 2 mL/h of saline. Mean arterial pressure, femoral blood flow, arterial blood gases, lactate, nitrate level, and31P nuclear magnetic resonance (31P MRS) measurements were acquired at onset (T = 0), 90 min (T = 90), and 180 min (T180) after the endotoxin challenge. Femoral oxygen delivery was calculated as the product of femoral blood flow (mL/min) and arterial oxygen content. Endotoxin induced a marked decrease in arterial pressure and femoral oxygen delivery and an increase in lactate level. Intracellular pH and phosphocreatine/inorganic phosphate ratio decreased. ATP level did not change. Both L-NMMA and L-canavanine reversed the endotoxin-induced decrease in arterial pressure. L-NMMA attenuated the decrease in femoral oxygen delivery and the increase in lactate level while these were corrected by L-canavanine. Considering31P MRS derived bioenergetic indices, the endotoxin-induced decrease in pHiand Pcr/Piwas attenuated by L-NMMA and corrected by L-canavanine. In conclusion, in a rodent model of endotoxinic shock, the continuous infusion of L-canavanine, a selective iNOS inhibitor, improved the systemic hemodynamic parameters and the intracellular bio-energetic patterns estimated by in vivo31P MRS. To the contrary, the continuous infusion of both constitutive and inducible NOS inhibitor L-NMMA was not followed by the same achievement.

ISSN:1073-2322    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ABSTRACTThis study was designed to investigate changes in mucosal NOS activity after burns and its relation to barrier failure. In Experiment 1, female specific pathogen free (SPF) Sprague-Dawley rats underwent 35% total body surface area (TBSA) burn. One to six days after burn, intestinal permeability was determined from the plasma leakage of fluorescein isothiocyanate (FITC)-dextran 4400, intestinal mucosal cNOS and iNOS activity were assayed using Griess' reagent, and the cellular localization of iNOS was examined using immunostaining. In Experiment 2, S-methylisothiourea (SMT) was given (5 mg/kg, i.p. every 12 h) for 2 days to suppress inducible NOS (iNOS) activity after thermal injury. On postbum Day 2, the effect of SMT on gut mucosal NOS activity, intestinal permeability, and barrier function were evaluated. The activity of iNOS increased 24 h after the injury and up to a maximum of twofold on postburn Day 2, and decreased thereafter. The increase in iNOS activity in gut mucosa correlated well with the increase in intestinal permeability, an index for barrier failure (r = .776, p = .0002). Results from iNOS immunostaining showed that changes in mucosal iNOS activity after the burn occurred mainly in the enterocytes rather than in the macrophages. Administration of SMT decreased mucosal iNOS activity, intestinal permeability, and bacterial translocation incidence to mesenteric lymph node concurrently. In conclusion, thermal injury induces intestinal mucosal iNOS, which is principally in the enterocytes. The increased intestinal iNOS activity was closely related to barrier failure. SMT inhibited intestinal mucosal iNOS activity and prevented barrier failure as demonstrated by a decrease in BT occurrence and intestinal permeability.

ISSN:1073-2322    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ABSTRACTOur purpose was to see whether endothelin- (ET) 1 could produce a change in the endothelial membrane barrier to protein in skeletal muscle. Previous studies in other tissues have suggested that ET-1 affects this barrier, but the measurement methods used could not exclude vascular protein extravasation due to microvascular pressure changes or the effects of changes in perfused capillary surface area. We measured the protein sieving coefficient, a specific measure of the permeability of the membrane to protein, in the isolated, perfused cat hindlimb preparation. The integral-mass balance method determined this coefficient from the changes in hematocrit and plasma protein concentration induced by a period of transvascular fluid filtration. The data clearly indicate that ET-1 produces a dose (1–20 nM) dependent increase in permeability indicative of barrier dysfunction. Hence, elevated ET levels may contribute to the perivascular edema, hemoconcentration, and impaired tissue perfusion found in systemic inflammatory response syndromes and related diseases.

ISSN:1073-2322    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ABSTRACTEnhanced intestinal nitric oxide production observed during sepsis is thought to play a central role in lipopolysaccharide-induced intestinal damage. In contrast intestinal polyamines, both from endogenous and exogenous origin, are essential for the maintenance of mucosal integrity. Polyamines have been shown to inhibit lipopolysaccharide-induced nitric oxide release in vitro and have been claimed to exert additional antiinflammatory actions. In this study, the effect of the polyamine spermine on the release of the proinflammatory mediators nitric oxide and tumor necrosis factor-± by a murine macrophage cell line was investigated. Furthermore, we investigated whether oral spermine administration inhibits lipopolysaccharide-induced intestinal inducible nitric oxide synthase and nitrotyrosine expression and modulates the release of inflammatory mediators. Our results show that although spermine inhibited lipopolysaccharide-induced nitric oxide release in a murine macrophage cell line, no effect on tumor necrosis factor-± release was observed. In addition, oral spermine administration inhibited intestinal inducible nitric oxide synthase and nitrotyrosine expression suggesting a protective effect of spermine on lipopolysaccharide-induced intestinal damage. In parallel a decrease in serum levels of the proinflammatory mediators nitrate, nitrite, and interferon-± and an increase in the antiinflammatory cytokine interleukin-10 was observed, although tumor necrosis factor-± levels were unaffected. These results indicate that spermine inhibits lipopolysaccharide-induced nitric oxide release in vitro as well as in vivo. Further, intraluminally derived polyamines modulate the systemic immune response. It is concluded that oral spermine administration might have therapeutic perspectives for several disorders characterized by systemic inflammation and intestinal damage.

ISSN:1073-2322    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ABSTRACTSepsis and hypoxia are important stressors for the neonate. Newborn infants receiving total parenteral nutrition are routinely deprived of carnitine and develop low carnitine plasma and tissue levels. Because of its high metabolic rate and dependence on fatty acids for energy, the newborn heart may be particularly vulnerable to stress in the face of an inadequate carnitine supply. To investigate whether carnitine deprivation affects cardiac performance under stress, 23 neonatal piglets received parenteral nutrition for 2–3 weeks that was either carnitine free (CARN -) or supplemented (CARN +) with L-carnitine (400 mg/L). Bacterial endotoxin (lipopolysaccharide (LPS), 250 ±g/kg intravenous bolus) or saline vehicle was administered to anesthetized piglets 3 h prior to study of isolated perfused hearts. Left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure, and left ventricular developed pressure (LVDP) were measured in vitro under aerobic, hypoxic, and reoxygenation conditions in all animals. Plasma and tissue carnitine values were lower in CARN - than in CARN + piglets. In hearts from LPS-treated animals prior to hypoxia, there was no difference in ventricular compliance between CARN - and CARN + groups. LVSP and LVDP were lower in CARN - than CARN + hearts. During hypoxia, LVSP and LVDP fell, but left ventricular end diastolic pressure increased in hearts from both LPS- and saline- treated piglets. Reoxygenation led to poorer recovery in CARN - than CARN + hearts from LPS-treated animals, but not from saline controls. During hypoxia/reoxygenation, lactate efflux initially rose and then fell, while carnitine efflux increased continually. Acetyl- and medium-chain acylcarnitines were detected in the coronary effluent. Our findings suggest that carnitine deprivation diminishes heart carnitine concentrations and impairs cardiac recovery from combined endotoxic and hypoxic stress. Possible mechanisms include reduced acyl buffering and/or impaired transport of fatty acyl groups into mitochondria.

ISSN:1073-2322    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ABSTRACTThe renin angiotensin system is highly activated in shock states and has been suggested to be involved in the pathophysiology of the markedly deteriorated splanchnic circulation seen in septic shock. The purpose of the present study was to elucidate the capability of losartan, a nonpeptide angiotensin II type 1 (AT1) receptor antagonist, to attenuate splanchnic blood flow disturbances and counteract intestinal mucosal acidosis in endotoxin shock. A total of 20 pigs were anesthetized and catheterized. Central and regional hemodynamics were monitored. A tonometer in the ileum was used for measurement of mucosal pH. Onset of endotoxin challenge was followed by losartan administration (n = 10) 2 h later. Ten animals receiving endotoxin only served as controls. The experiments were terminated 5 h after onset of endotoxin challenge. Endotoxin infusion induced an hypodynamic shock with a reduction in cardiac index and systemic oxygen delivery. Losartan reduced both systemic vascular resistance and pulmonary capillary wedge pressure while stroke volume was improved. Pulmonary hypertension induced by endotoxin was significantly reduced by losartan without further changes in gas exchange. The profound reduction in gut oxygen delivery in response to endotoxin was counteracted by losartan administration. However, losartan failed to improve the markedly deteriorated intestinal mucosal pH and mucosal-arterial Pco2gap (i.e., difference in intestinal mucosal Pco2and arterial Pco2). Also the mucosal-portal venous Pco2gap, used as a monitor of the mucosa in relation to the gut as a whole (including the spleen and pancreas), was greatly increased by endotoxemia but unaffected by losartan administration. In summary, although the angiotensin II type 1 receptor antagonist losartan improved gut oxygen delivery and reduced pulmonary hypertension during established endotoxin shock, it had no effect on intestinal mucosal acidosis. These findings suggest contribution of the angiotensin II type 1 receptor to perfusion disturbances, but not to deterioration of intestinal mucosal homeostasis seen during endotoxemia.

ISSN:1073-2322    

出版商:OVID    

年代:1999

数据来源: OVID