摘要:

Tumor necrosis factor-&agr; (TNF-&agr;) depresses myocardial contractility, and overexpression of TNF-&agr; in the myocardium contributes to cardiac dysfunction caused by both systemic and local insults. Sepsis, endotoxemia, hemorrhagic shock, and myocardial ischemia-reperfusion all promote cardiac dysfunction in part by a TNF-&agr;-mediated mechanism. Thus, TNF-&agr; represents an appealing therapeutic target for myocardial protection against multiple clinically relevant insults. The inducible 70-kD heat shock protein (Hsp70) is expressed in the myocardium in response to stress and has been linked to enhanced myocardial resistance to depression associated with ischemia-reperfusion or sepsis. The mechanism by which Hsp70 protects cardiac function against a subsequent insult remains obscure.In vitroinduction of Hsp70 in monocytes or macrophages inhibits TNF-&agr; production following bacterial lipopolysaccharide stimulation, andin vivoinduction of Hsp70 down-regulates tissue TNF-&agr; production following an injurious insult. Understanding of the regulatory role of Hsp70 in the myocardial inflammatory response will provide insights into the mechanism by which Hsp70 preserves cardiac function and may yield therapies for protection of the myocardium against depression associated injurious insults.

ISSN:1073-2322    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

We investigated the specificity for gram-negative stimuli as well as the contribution of signal transduction pathways for leukocyte hyporesponsiveness in sepsis or following cardiopulmonary bypass (CPB). Whole blood of nine patients undergoing CPB and 25 patients with severe sepsis was stimulatedex vivowith LPS (E. coliO111:B4) or withStaphylococcus aureusCowan strain I (SAC-I) lysate in the absence or presence of inhibitors of protein kinase C (PKC), protein-tyrosine kinase (PTK), or protein-tyrosine phosphatase (PTP). Both toxins stimulated a TNF-&agr; response through PTK signaling. Although suppression of the cytokine response was similar for LPS and SAC-I after CPB, it was significantly more pronounced for SAC-I in sepsis. Inhibition of PTP failed to increase TNF-&agr; upon LPS, whereas a moderate increase was observed with SAC-I. Impaired TNF-&agr; responses occur in sepsis and after CPB. Although this has primarily been reported for gram-negative stimuli, our data suggest that this is even more pronounced for gram-positive stimuli in severe sepsis. Although PTK was the predominant signaling pathway, inhibition of PTP only partially restored the TNF-&agr; response to SAC-I. Our results suggest that cellular mechanisms underlying monocyte deactivation are different in sepsis or following CPB and are discriminate for gram-positive and gram-negative toxins.

ISSN:1073-2322    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

The aim of the study was to compare peritoneal and systemic production of interleukin 6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1) in uninfected patients and in patients with peritonitis. Peritoneum was excised at laparotomy for acute peritonitis (n = 22) or noninfectious reasons (n = 61), and was incubated with or without lipopolysaccharide (LPS). Mediator concentrations in the culture-supernatants, in the patients' serum, and in plasma-supernatants of LPS-stimulated whole blood were related to outcome. Spontaneous production of IL-6 by the peritoneum was increased in infected patients compared with uninfected patients. In contrast to IL-6, LPS-stimulated production of MCP-1 was significantly less in infected patients. Serum concentrations of both mediators were higher in infected patients and the highest concentrations of MCP-1 were in patients who died. LPS-stimulated production of IL-6 in whole blood was least, whereas that of MCP-1 was greatest in infected patients who died. These contrasting results for local and systemic production of mediators illustrate the compartmentalized immune response to intra-abdominal infection.

ISSN:1073-2322    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Kupffer cells (KCs), the resident macrophages of the liver, contribute prominently to liver injury by inflammatory mediators. Pre-conditioning with the atrial natriuretic peptide (ANP), known also as a regulator of macrophage functions, attenuates hepatic ischemia-reperfusion injury. Therefore, the aim of this study was to determine the presence of functional ANP receptors on isolated KCs and to investigate whether this hepatoprotective hormone influences the activation of KCs. KCs were isolated by collagenase/pronase digestion followed by elutrial centrifugation and cultured for 1 to 3 days. Intracellular cyclic guanosine 3´5´-monophosphate (cGMP) concentrations were measured by radioimmunoassay after treating the cells with sodium nitroprusside or ANP. KCs were stimulated with bacterial lipopolysaccharide in the presence or absence of ANP, and inflammatory mediators were determined. Phagocytosis was assayed using Coumarin-labeled latex particles and flow cytometric analysis. Treatment of KCs with ANP but not with sodium nitroprusside resulted in a significant elevation of intracellular cGMP levels indicating functional type A natriuretic peptide receptors (NPR-As). ANP significantly reduced lipopolysaccharide (LPS)-induced tumor necrosis factor alpha (TNF&agr;) secretion, paralleled by an increased cell-associated TNF&agr;. LPS-induced TNF&agr; mRNA expression was not affected. ANP significantly increased phagocytotic activity of KCs via NPR-A. No effect of ANP on LPS-activated inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 protein levels, iNOS mRNA expression, nitric oxide, and PGE2-production was observed. We demonstrated functional cGMP-dependent ANP receptors in isolated rat KCs. ANP reduced TNF&agr; release possibly by influencing post-translational processing of TNF&agr; in LPS-activated KCs. In addition, we demonstrated that ANP enhances phagocytosis in KCs. These effects may contribute to the hepatoprotective actions of ANP.

ISSN:1073-2322    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Intestinal ischemia-reperfusion affects hemodynamics. We studied intratracheal vs. intraperitoneal methylene blue (MB) attenuation of hemodynamic and metabolic deterioration following superior mesenteric artery (SMA) clamping/unclamping. Murine SMAs (5/group) were clamped for 1 h. MB (2, 6, 20, or 60 mg/kg [MB-2, MB-6, MB-20, and MB-60]) was administered intraperitoneally or intratracheally 10 min before unclamping. Observation continued for another 3 h. Circulating xanthine oxidase and base deficit levels doubled among ischemia non-treated and ischemia MB-2- and MB-60-treated groups, blood pressure decreased by 50%, and heart rate increased by 35%, compared to controls (non-clamped/unclamped and non-MB-treated rats,P< 0.01). These three ischemia groups needed 3-fold the amount of fluid to maintain systolic pressure ≥60 mmHg than controls (P< 0.01). Only the MB-6 and MB-20 intraperitoneal and intratracheal regimens similarly afforded hemodynamic stability in ischemic animals; base deficit and resuscitation volumes normalized as well. No drug regimen affected heart rate. We concluded that intraperitoneal and intratracheal MB at specific doses prevented systemic derangement following SMA clamping/unclamping.

ISSN:1073-2322    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

To challenge whether the recommended dose of 4 mL/kg of 7.5% sodium chloride in 6% Dextran (HSD) is optimal for fluid resuscitation in uncontrolled hemorrhage, 30 anesthetized pigs were randomized to receive a 5-min intravenous infusion of either 1, 2, or 4 mL/kg of HSD beginning 10 min after inducing a 5-mm laceration in the infrarenal aorta. In addition to conventional hemodynamic monitoring, the blood loss was calculated as the difference in blood flow rates between flow probes placed proximal and distal to the injury. The results show that the bleeding stopped between 3 and 4 min after the injury and amounted to 338 ± 92 mL (mean ± SEM), which corresponds to 28.5% ± 6.6% of the estimated blood volume. After treatment with HSD was started, six rebleeding events occurred in the 1-mL group, 11 in the 2-mL group, and 16 in the 4-mL group. The amount of blood lost due to rebleeding increased significantly with the dose of HSD and was also associated with a fatal outcome. The total blood loss was 408 mL in the survivors and 630 mL in the nonsurvivors (median,P< 0.007). The mortality in the three groups was 20%, 50%, and 50%, respectively. In conclusion, infusing 4 mL/kg of HSD after uncontrolled aortic hemorrhage promoted rebleeding and increased the mortality, while a dose of 1 mL/kg appeared to be more suitable.

ISSN:1073-2322    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Endothelin 1 (ET-1) is a potent vasoactive peptide that acts at sinusoidal and extrasinusoidal sites in the liver. Sensitivity to ET-1 increases in LPS-primed animals and is associated with impaired liver microcirculation in these animals. We hypothesized that LPS priming leads to an exacerbation in the impaired oxygen delivery in response to intraportal infusion of ET-1. Rats were studied 24 h after LPS injection (1 mg/kg, i.p.). Surface PO2was determined using a recently developed technology of O2mapping. The baseline portal pressure was higher in LPS-primed animals (P< 0.05), and increased to similar magnitude as sham animals after a 10-min infusion of ET-1. The resultant portal pressure remained elevated in LPS compared to sham animals. There was no significant difference in baseline mean arterial pressure, and no significant systemic response to ET-1 in either group. In contrast to the macrohemodynamic, the decrease in tissue surface PO2in response to ET-1 infusion was potentiated by LPS treatment (increased from baseline levels 33.8 ± 9 to 46.8 ± 8.3 in sham; 42.3 ± 9.1 to 69 ± 6.5 gray scale units in LPS;P< 0.01, sham vs. LPS) at end of infusion of ET-1 for 10 min. This indicates tissue hypoxia in response to ET-1, which is exacerbated in livers from LPS-primed animals compared to sham. Frequency distribution analysis showed a shift in mode from lower intensity (higher PO2) to areas with higher fluorescent intensity ranges (lower PO2), indicating areas with shut down in perfusion in LPS-treated animals. In the whole liver, ET-1 suppressed oxygen consumption, and this response was potentiated by LPS pretreatment. We propose that ET-1 impairs oxygen delivery in the liver during endotoxemia, resulting in areas of focal hypoxia. This response is possibly due to potentiated action of ET-1 at both sinusoidal and extrasinusoidal sites in the liver during endotoxemia.

ISSN:1073-2322    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

The purpose of this study was to investigate alterations of phospholamban phosphorylation and its interaction with Ca2+transport (Ca2+-ATPase activity and Ca2+uptake) in sarcoplasmic reticulum (SR) during the progression of sepsis. Sepsis was induced by cecal ligation and puncture (CLP). Phospholamban phosphorylation was studied by the labeling of the myocardial ATP pool by perfusing isolated rat hearts with [32P]H3PO4followed by identification of the phosphorylated phospholamban. Results show that phospholamban phosphorylation was increased by 153% during the early hyperdynamic phase (9 h after CLP), while it was decreased by 51% during the late hypodynamic phase (18 h after CLP) of sepsis. The increase in phospholamban phosphorylation during early sepsis was associated with increases in +dP/dtmaxand tissue cAMP content, while Ca2+transport, left ventricular developed pressure (LVDP), and −dP/dtmaxremained unchanged. The decrease in phospholamban phosphorylation during late sepsis was accompanied by decreases in Ca2+transport, LVDP, ±dP/dtmax, and tissue cAMP content. When isoproterenol was present in the perfusion medium, all parameters measured were stimulated in all three experimental groups (control, early sepsis, and late sepsis) except that Ca2+-ATPase activity and SR Ca2+uptake were unresponsive in the early and the late septic groups. These findings demonstrate that during the late hypodynamic phase of sepsis, the observed decrease in myocardial contractility was due to the decrease in phospholamban phosphorylation, which resulted in decreased Ca2+transport across the SR. In contrast, during the early hyperdynamic phase of sepsis, the increase in phospholamban phosphorylation did not correlate with increases in Ca2+uptake and Ca2+-ATPase activity. Thus, the interaction between phospholamban phosphorylation and Ca2+transport across the SR was disrupted during the early phase of sepsis.

ISSN:1073-2322    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

We hypothesized that tumor necrosis factor-&agr; (TNF-&agr;) mimics endotoxin in attenuating endothelium-dependent vasodilation and smooth muscle constriction of rat renal arteries, and that tyrosine kinase is involved. Isolated rat renal arteries (n = 6 per group), pretreated for 2 h by genistein (4´,5,7-trihydroxyisoflavone, 10 &mgr;g/mL, a tyrosine kinase inhibitor) or vehicle, were exposed for 2 h to recombinant human (rh) TNF-&agr; (100 ng/mL) or vehicle. rhTNF-&agr; attenuated (P< 0.05) the constriction response to depolarizing 125 mM KCl (952.6 ± 125.3 mg/mm vs. 1191.4 ± 136.8 mg/mm in rhTNF-&agr;-exposed and control segments, respectively), but did not affect the constriction response to norepinephrine (NE, 0.01–10 &mgr;M). Genistein did not affect the constriction response to KCl. The concentration-response relation to NE in genistein-pretreated control segments showed (P< 0.05) a rightward shift, while the maximum constriction was not affected. Genistein did not prevent a reduction (P< 0.05) by rhTNF-&agr; in the maximum response to NE (721.7 ± 42.4 mg/mm vs. 999.8 ± 84.4 mg/mm in controls). The endothelium-dependent relaxation induced by (acetyl choline) ACh (0.001–1.0 &mgr;M) was attenuated (P< 0.05) by rhTNF-&agr; (39.4% ± 6.7% and 77.4% ± 10.0% in rhTNF-&agr;-exposed and control segments, respectively). The reduction (P< 0.05) in maximum ACh-induced relaxation after exposure to rhTNF-&agr; was not affected by genistein (44.6% ± 3.4% and 70.8% × 2.2% in genistein-pretreated rhTNF-&agr;-exposed and control segments, respectively). Hence, the attenuated endothelium-dependent relaxation and smooth muscle constriction of rat renal arteries following short-term rhTNF-&agr; exposure, mimicking the effect of endotoxin, does not involve the activity of tyrosine kinase. The latter may be involved in pharmacomechanical coupling, by increasing Ca2+sensitivity, but less in the electromechanical coupling of smooth muscle constriction.

ISSN:1073-2322    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Curcuminoids, derived from the plantCurcuma domesticaVal., have been shown to be free radical scavengers that suppress the production of superoxide by macrophages and potent anti-inflammatory agents that inhibit the lipopolysacharide (LPS)-induced production of tumor necrosis factor alpha (TNF&agr;), interleukin (IL)-1&bgr;, and the activation of nuclear factor (NF)-&kgr;B in human monocytic derived cells. The present study was undertaken to determine the efficacy of curcuminoids in inhibiting the hepatic microvascular inflammatory response elicited by LPS. BALB/C mice were gavaged intragastricly with curcuminoids [40 mg/kg body weight (bw) or 80 mg/kg bw] 1 h before intravenous injection of LPS (Escherichia coli, 0111:B4, 100 &mgr;g/kg bw). The liver was examined 2 h after LPS injection usingin vivomicroscopic methods. LPS-treated mice showed significantly increased phagocytic activity of centrilobular Kupffer cells. The numbers of leukocytes adhering to the sinusoidal wall and swollen endothelial cells increased significantly in both the periportal and centrilobular regions, concomitant with a reduction in the numbers of sinusoids containing flow. Pretreatment with curcuminoids at the doses of 40 mg/kg bw or 80 mg/kg bw to endotoxemic mice significantly reduced the phagocytic activity of Kupffer cells, the numbers of adhering leukocytes and swollen endothelial cells. As a result, the number of sinusoids containing flow was increased in animals treated with 40 mg/kg curcuminoids and restored to control levels with 80 mg/kg curcuminoids. Neutrophil sequestration was reduced when measured in sections stained with naphtol AS-D chloroacetate esterase technique. These results demonstrate that curcuminoids are effective in suppressing the hepatic microvascular inflammatory response to LPS and may be a natural alternative anti-inflammatory substance.

ISSN:1073-2322    

出版商:OVID    

年代:2002

数据来源: OVID