摘要:

Appropriate polymorphonuclear neutrophil (PMN) recruitment is essential for host defense against infection. We investigated the significance of the preoperative PMN adhesion–migration process, as assessed by the flow chamber method, on postoperative infectious complications. Thirty-one consecutive patients with gastrointestinal malignancies, 21 colorectal and 10 gastric, who were undergoing elective surgery were enrolled. PMNs, isolated preoperatively from each patient's venous blood, were perfused onto a tumor necrosis factor &agr;-stimulated human umbilical vein endothelial cell (HUVEC) monolayer through the flow chamber. We evaluated the adherent PMN number, the migrated PMN number, and the stuck PMN number by directly inspecting PMN interactions with a HUVEC monolayer under continuous shear flow simulating postcapillary venules. The expression of adhesion molecules on circulating PMNs was also measured. Patients were grouped into an infectious and a noninfectious group according to the occurrence of postoperative infectious complications defined by the Centers for Disease Control criteria. Eleven patients developed postoperative infectious complications. Although the number of preoperativein vitroadherent PMNs in patients with postoperative infection was significantly higher than in those without postoperative infection (P= 0.01), migrated PMN number was similar in both groups. Stuck PMN number tended to be higher in the infectious group than in the noninfectious group. The migrated PMN number showed a significant positive correlation with the adherent PMN number in the noninfectious group but not in the infectious group. Preoperative CD31 expression on circulating PMNs was significantly lower in the infectious group than in the noninfectious group. Preoperativein vitroderangement of the PMN adhesion-migration process is closely associated with postoperative infectious complications.

ISSN:1073-2322    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Anti-inflammatory effects of adenosine were evaluated in two randomized, double-blind, placebo-controlled studies. In one study healthy male volunteers received no endotoxin (adenosine study, n = 10), in the other intravenous endotoxin (4 ng/kg, endotoxin study n = 11) was given. All subjects were treated with adenosine infusion (40 &mgr;g/kg/min) and placebo (saline) infusion in a crossover design. Heart rate, body temperature, blood pressure and plasma cytokines (tumor necrosis factor [TNF]-&agr;, interleukin [IL]-6, IL-10, and soluble TNF receptors I and II), nitric oxide oxidation products, nitrite and nitrate, as well as superoxide anions were determined. There were no significant changes of any measured parameter after adenosine treatment alone. Endotoxin elicited clinical signs of an inflammatory reaction, prominent release of all cytokines and O2−synthesis by neutrophils (N-formyl-methionin-leucyl-phenylalanin-stimulated cells measured by cytochrome C reduction). The plasma IL-6 response to endotoxin was attenuated by adenosine, as IL-6 increased from 0.9 (0.8–1.6) to 1345 (743–1906) pg/mL (median; 25–75th percentiles) with adenosine infusion, and from 0.8 (0.5–1) to 1,959 (1,344–2,505) pg/mL with placebo (P= 0.0065). There was no significant influence of adenosine infusion on the other variables examined. In conclusion, systemic adenosine infusion counteracts the release of IL-6 in healthy volunteers, indicating an anti-inflammatory effect of adenosine which should be further explored.

ISSN:1073-2322    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Neutral endopeptidase (NEP), a membrane-bound metallopeptidase enzyme that degrades neuropeptides, bradykinin, atrial natriuretic factor, enkephalins, and endothelin may regulate response to injury. We have previously demonstrated increased NEP localization and enzyme activity in diabetic wounds and skin compared with normal controls. We hypothesized that hyperlipidemia and hyperglycemia associated with type 2 diabetes mellitus may induce excessive NEP activity and thereby diminish normal response to injury. Human microvascular endothelial cells were treated with five different fatty acids (40 &mgr;M) with varying degrees of saturation, including oleic acid, linoleic acid, palmitic acid, stearic acid, and linolenic acid and/or glucose (40 mM) for 48 h. The effect of the antioxidative agents vitamin E and C on NEP enzyme activation was determined by treating the cultured cells with alpha-tocopherol succinate and/or L-ascorbic acid. Cell membrane preparations were assayed for NEP activity by incubation with glutaryl-Ala-Ala-Phe-4-methoxy-&bgr; naphthylamide to generate a fluorescent degradation product methoxy 2 naphthylamine. High glucose or fatty acid concentration upregulated NEP activity. The highest NEP activity was observed with combined elevated glucose, linoleic acid, and oleic acid (P< 0.05). Antioxidant vitamin E and C treatment significantly reduced NEP enzyme activity after fatty acid exposure (P< 0.05). Thus, hyperglycemia and hyperlipidemia associated with type 2 diabetes mellitus may increase endothelial cell NEP activity and thereby decrease early pro-inflammatory responses. The modulator effect of vitamin E and C on NEP membrane enzyme activity after exposure to fatty acid stimulation suggests that lipid oxidation may activate NEP.

ISSN:1073-2322    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

A mouse model of burn injury demonstrates increasing mortality to an infectious challenge in the form of cecal ligation and puncture (CLP) reaching a peak at 10 days after injury. Because it is widely believed that peritoneal mast cells play an important role in the defense against peritoneal sepsis, we wished to explore the possibility that peritoneal mast cell dysfunction contributed to increased CLP mortality after burn injury. KitW-vC57BL/6 mice, which were shown to lack peritoneal mast cells by cytospin and flow cytometry, and normal littermate control animals were subjected to 25% burn or sham burn injury and 10 days later underwent CLP. Burn injured KitW-vand normal littermates had a high CLP mortality when compared with sham-injured KitW-vand normal littermates (P< 0.003), but the sham- and burn-injured KitW-vand normal littermate animals did not differ from one another with respect to CLP mortality. This result prompted a comparison of CLP mortality in untreated WBB6F1 KitW/W-vmice, known to be mast cell deficient, and normal littermate controls, as well as untreated C57BL/6 KitW-vand normal littermates. The WBB6F1 KitW/W-vmice showed significantly increased mortality after CLP as compared with the littermate controls (P= 0.03), whereas both C57BL/6 KitW-vand littermate controls had very low mortality after CLP. A study of peritoneal cell populations 24 h after CLP failed to reveal an obvious cause for the difference in CLP survival between the two mast cell-deficient strains. Tumor necrosis factor-alpha (TNF-&agr;) measurements in peritoneal fluid showed appreciable amounts of TNF-&agr; in the littermate controls of both strains and little in the fluid obtained from the mast cell-deficient animals of both strains. We conclude that peritoneal mast cell dysfunction is unlikely to be a major cause of decreased resistance to peritoneal sepsis in burn-injured animals and that the importance of peritoneal mast cells in combating peritoneal sepsis in the mouse appears to be strain dependent.

ISSN:1073-2322    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Severe blunt chest trauma remains an important injury with high morbidity and mortality. However, the associated immunological alterations are poorly understood. Existing big animal models require large-scale settings, are often too expensive, and research products for immunological studies are limited. In this study we aimed to establish a new model of blunt, isolated and bilateral chest trauma in mice and to characterize its effects on physiological and inflammatory variables. Male C3H/HeN mice (n = 9–10/group) were anesthetized and a femoral artery was catheterized. The animals were subjected to trauma or sham procedure and monitored for 180 min. Blunt chest trauma was induced by a blast wave focused on the thorax. Trauma intensity was optimized by varying the exposure distance. Blood pressure, heart rate, respiratory rate, arterial blood gases and plasma cytokine levels were measured. Macroscopic and microscopic examinations were performed. In addition, outcome was evaluated in a 10-day survival study. Chest trauma caused a drop (P< 0.05) in blood pressure and heart rate, which partly recovered. Blood gases revealed hypoxemia and hypercarbia (P< 0.05) 180 min after trauma. There was marked damage to the lungs but none to abdominal organs. Histologically, the characteristic signs of a bilateral lung contusion with alveolar and intrabronchial hemorrhage were found. Plasma interleukin-6 and tumor necrosis factor &agr; were considerably increased after 180 min. Blunt chest trauma resulted in an early mortality of 10% without subsequent death. On the basis of these findings, this novel mouse model of blunt chest trauma appears suitable for detailed studies on immunological effects of lung contusion.

ISSN:1073-2322    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Heme oxygenase (HO) has both deleterious and protective effects in various shock models. Most of these data have been derived from experiments with hypodynamic shock states associated with depressed cardiac output. Therefore we studied the role of HO during long-term porcine hyperdynamic endotoxemia characterized by a sustained increase in cardiac output resulting from colloid resuscitation to maintain mean arterial pressure > 60 mmHg. Systemic, pulmonary, and hepatosplanchnic hemodynamic and metabolic effects of the HO-inhibitor tin–mesoporphyrin (SnMP) were assessed in anesthetized and mechanically ventilated animals. After 12 h of continuous intravenous lipopolysaccharide (LPS), animals received either vehicle (n = 6) or SnMP (n = 8; 6 &mgr;mol kg−1i.v. over 30 min at 12 and 18 h of LPS). Measurements were performed before LPS, before SnMP infusion, and at 24 h of LPS. SnMP did not influence systemic hemodynamics but significantly increased mean pulmonary artery pressure. Although liver blood flow was not affected, SnMP markedly impaired liver lactate clearance. HO inhibition was associated with increased plasma nitrate levels likely the result of increased NO production. Our results suggest a protective role of HO activation during hyperdynamic porcine endotoxemia possibly as a result of an interaction with the LPS-induced increase in NO formation.

ISSN:1073-2322    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Changes in the protein level of various subunits of GTP-binding protein and the activity of adenylate cyclase in the rat heart during different phases of sepsis were studied. Sepsis was induced by cecal ligation and puncture (CLP). Experiments were divided into three groups: control, early sepsis, and late sepsis. Early and late sepsis refers to those animals sacrificed at 9 and 18 h, respectively, after CLP. The protein levels of various subunits of GTP-binding protein were determined by Western blot analysis. The activity of adenylate cyclase was measured based on the rate of formation of cAMP from [&agr;-32P]ATP. The results show that protein levels of G&agr;s and G&bgr; remained stable during the early and the late phases of sepsis. The protein levels of G&agr;i-2 and G&agr;i-3 remained relatively unaltered during the early phase of sepsis, but they were increased by 46.5% (P< 0.05) and 61.3% (P< 0.01), respectively, during the late phase of sepsis. The basal adenylate cyclase activity remained unchanged during the early phase while it was decreased by 25.7% (P< 0.05) during the late phase of sepsis. The isoproterenol-stimulated adenylate cyclase activity was unchanged during early sepsis while it was decreased by 44.6% (P< 0.01) during late sepsis. These data demonstrate that during the late hypodynamic phase of sepsis, myocardial G&agr;i-2 and G&agr;i-3 protein levels were increased and the increases were coupled with a reduction in adenylate cyclase activity. Because GTP-binding proteins mediate sympathetic control of cardiac function, the present findings may have a pathophysiological significance in contributing to the understanding of the pathogenesis of cardiac dysfunction during the late stage of sepsis.

ISSN:1073-2322    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

The presence of increased levels of proinflammatory cytokines in the blood is associated with decreased muscle protein synthesis and the erosion of lean body mass in many catabolic conditions. However, little is known regarding the role of endogenous cytokine synthesis in muscleper se.The purpose of the present study was to characterize the cytokine expression profile of skeletal muscle in response to anin vivoinjection of endotoxin (lipopolysaccharide, LPS). Intraperitoneal injection of a nonlethal dose of LPS (1,000 &mgr;g/kgEscherichia coli) into male rats increased the mRNA content of tumor necrosis factor-alpha (TNF-&agr;) and interleukin (IL)-1&bgr; in gastrocnemius muscle as early as 1 h; IL-6 mRNA was not increased until 2 h post-LPS. Expression of TNF-&agr; and IL-1&bgr; peaked at 2 h (10- and 80-fold, respectively), whereas the increased IL-6 mRNA content (150-fold) peaked later at 4 h. The abundance of all measured cytokine mRNAs in skeletal muscle declined thereafter. The LPS-induced increase in muscle mRNA content for TNF-&agr;, IL-6, and IL-1&bgr; was dose-dependent with elevations being seen with as little as 10 &mgr;g/kg of LPS (2.5-, 8-, and 9-fold, respectively). In general, pretreatment of rats with dexamethasone attenuated but did not completely prevent the LPS-induced increase in muscle cytokine mRNA. LPS increased muscle TNF-&agr; protein content approximately 2-fold and this increase was prevented by pretreatment with dexamethasone. LPS-induced increases in muscle IL-1&bgr; and IL-6 protein were not detected. LPS also produced a 2-fold increase in the mRNA content of the high-mobility-group protein-1, a late-phase cytokine, in muscle at 12–24 h. Finally, although skeletal muscle was found to contain both the toll-like receptor (TLR)-2 and TLR4, LPS did not alter the mRNA content of TLR4 and produced a small (50%) but significant increase in TLR2 mRNA. These changes in TLRs were less dramatic than those observed for liver, spleen or cardiac muscle. Collectively these data indicate that skeletal muscle possesses many of the components of the innate immune system, including increases in both early- and late-phase cytokines and the presence of toll-like receptors.

ISSN:1073-2322    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

The protective effects and roles of AT1-receptor antagonists (AT1-RA) or angiotensin-converting enzyme inhibitors (ACEI) on vascular endothelial cell (EC) injury during hypoxia are not entirely known. Therefore, we investigated these effects and mechanisms in human aortic (HA) EC. DNA fragmentation, Lactate dehydrogenase (LDH) release, and caspase-3 activity were measured in cultured HAEC after exposure to hypoxia in the presence or absence of an AT1-RA (candesartan, CS) and/or an ACEI (temocaprilat, TC). Next, we investigated endothelial cell nitric oxide synthase (ecNOS) and inducible (i) NOS to determine the role of the bradykinin(BK)-NO pathway in the protective effect on ACEI and AT1-RA in the setting of hypoxia-induced apoptosis. Exposure to hypoxia increased DNA fragmentation in HAEC associated with the activation of caspase-3, but did not affect LDH release. In addition, hypoxia induced ecNOS mRNA but not mRNA iNOS. CS and/or TC reduced apoptosis induced by hypoxia in a dose-dependent manner, and significantly increased BK and ecNOS expression. This effect was attenuated by the kinin B2 receptor antagonist, HOE 140, and the NOS inhibitor, N-nitro-l-arginine methylester (L-NMMA). Hypoxia activates the pathway leading to apoptosis by enhancing caspase-3 activity. Both CS and TC can ameliorate hypoxia-induced apoptosis in HAEC through inhibiting caspase-3 activation by enhancing ecNOS activity, via the accumulation of BK.

ISSN:1073-2322    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Liver ischemia-reperfusion injury (IR) would be expected to alter the capacity of previously ischemic as well as continuously perfused segments that are exposed to circulating inflammatory mediators to respond to a subsequent infectious insult. IR is reported to induce tolerance to subsequent endotoxin stimulation if the lipopolysaccharide (LPS) challenge is delayed until the late, neutrophil-mediated phase of reperfusion. Whether ischemic or perfused liver is differentially affected and whether LPS-tolerance may be overcome by increasing exposure is unknown. We hypothesized that late tolerance after IR reflects a refractory state in which the liver's expression of pro-inflammatory mediators in response to secondary LPS is limited. Precision-cut tissue culture methodology was used to investigate the capacity of rabbit liver to respond to a spectrum of LPS stimulation 24 h after partial IR. Slices from normal liver showed a dose-dependent response to LPS for tumor necrosis factor (TNF-&agr;) expression. Slices from both previously ischemic and continuously perfused lobes retained dose responsiveness for TNF-&agr;, although TNF-&agr; was significantly decreased at high LPS concentrations compared with normal liver. Ischemic liver sustained this blunted response despite extended exposure to LPS, whereas perfused slices recovered responsiveness to high dose LPS with prolonged stimulation. IR induced interleukin-8 in both ischemic and perfused liver, but secondary LPS stimulation did not augment interleukin-8 expression. Hepatic IR induces a late tolerance to secondary LPS challenge in locally ischemic tissue that cannot be overcome by increasing LPS exposure. Nonischemic liver exposed to the systemic effects of IR injury, however, retains a capacity to respond to LPS with sufficient stimulation.

ISSN:1073-2322    

出版商:OVID    

年代:2003

数据来源: OVID