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Query: UMLS:C0036690 (sepsis)
 59,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although studies indicate that polymicrobial sepsis produces marked depression in lymphocyte functions, it remains unclear whether this dysfunction is due to the chronic exposure of immune cells to endotoxin (ETX; a product of the gram-negative bacterial cell wall) at levels typically encountered in the septic state. The aim of this study, therefore, was to determine whether the changes in lymphokine release seen during polymicrobial sepsis are comparable to those observed with chronic ETX infusion. To assess this, splenocytes were harvested from C3H/HeN mice (ETX-sensitive) at 1 or 24 hr following cecal ligation and puncture (CLP; to induce polymicrobial sepsis), Sham CLP (Sham), or laparotomy followed by peritoneal implantation of a mini-osmotic pump which delivered either saline vehicle (Sal-pump) or ETX (ETX-pump; 0.025 micrograms lipopolysaccharide/25 g body wt/24 hr). Splenocytes were then stimulated with concanavalin A (2.5 micrograms/ml/48 hr) and their capacity to release interleukin (IL)-2, interferon (IFN)-gamma, IL-4, and IL-10 was determined by bioassay or ELISA. The results indicated that there were no changes in lymphokine release capacity at 1 hr after CLP or ETX-pump implantation. However, prolonged sepsis (i.e., at 24 hr) caused a marked suppression of IL-2 and IFN-gamma release (immune-enhancing lymphokines characteristic of Th1-cells), while enhancing the release of immunosuppressive Th2-cell products IL-4 and IL-10. Chronic exposure to ETX at a level comparable to that seen in CLP caused no depression in lymphokine (IL-2/IFN-gamma) release. This implies that a bacterial component other than ETX mediates the differential alterations observed in lymphokine release during prolonged polymicrobial sepsis.
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PMID:Polymicrobial sepsis but not low-dose endotoxin infusion causes decreased splenocyte IL-2/IFN-gamma release while increasing IL-4/IL-10 production. 801 14

Sepsis was induced in rats by cecal ligation and puncture. A nutrient mixture was infused that also contained either (A) sodium 2-ketoisocaproate (NaKIC) or (B) NaHCO3, at 18.75 mmol kg/day. In group A, 34 of 43 rats (79%) survived, while only 24 of 44 rats (55%) in group B survived (P < 0.02). In a second experiment, cecal ligation and puncture were performed 1 week after bilateral adrenalectomy or sham adrenalectomy. All adrenalectomized rats died within 2 days of CLP, whether corticosterone replacement level was low, normal, or high. Four of eight sham-adrenalectomized rats receiving NaHCO3 died, but none of seven receiving NaKIC died. Combining both experiments by ANOVA, the effect of KIC on survival in adrenal-intact animals is highly significant (P = 0.002). In NaKIC-infused rats, blood level of pyruvate was higher on day 5 (P < 0.01), and plasma as well as blood levels of oxidized glutathione and ratio of oxidized/reduced glutathione were significantly lower. We conclude that KIC infusion improves survival of septic rats by an antioxidant mechanism, probably involving reaction with hydrogen peroxide.
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PMID:Ketoisocaproate infusion improves survival from experimental sepsis by an antioxidant mechanism. 814 49

Hepatic dysfunction is a major contributor to death in multiple organ system failure. To evaluate whether this dysfunction increases with the length of sepsis, we studied the effect of fulminant CLP peritonitis with hyperoxia on mixed-function oxidase-MFO (cytochrome P450 content and activity) and lipid peroxidation in rat livers. Livers were harvested at 18, 21, 24, and 27 hr, homogenized, and microsomal fractions prepared. Cytochrome P450 concentration was determined by assay and P450 activity was determined by the metabolism of ethoxyresorufin and ethoxycoumarin. Lipid peroxidation was estimated by measuring malondialdehyde content. Septic rats showed decreases in P450 levels and activity, which worsened with duration of sepsis. These decreases were partially lessened by hyperoxia. Although there was a trend toward increased lipid peroxidation, this effect was not statistically significant. This study suggests that while MFO content and activity decrease with sepsis, these decreases do not appear to be related to the production of oxygen-derived free radicals. Furthermore, hyperoxia actually appears to have a protective role in this instance.
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PMID:Mixed-function oxidase activity in sepsis. 853 82

Although studies have indicated that the levels of catecholamines increase during sepsis, it remains unknown whether the elevated levels of epinephrine, norepinephrine, and dopamine observed in early sepsis are sustained during late, hypodynamic stages of sepsis. In this study, rats were subjected to sepsis by cecal ligation and puncture (CLP, i.e., polymicrobial sepsis). Immediately after CLP or sham operation, animals received 3 mL/100 g body weight normal saline subcutaneously. At .5, 2, 10 (i.e., early sepsis), or 20 h (late sepsis) after CLP, blood samples were drawn and the plasma was separated. Plasma levels of epinephrine, norepinephrine, and dopamine were determined using a [3H]-radioenzymatic assay. The results indicate that plasma levels of epinephrine, norepinephrine, and dopamine increased significantly as early as .5 h after CLP. The increase in catecholamine levels persisted throughout the study periods. Thus, circulating levels of catecholamines were elevated in both early and late stages of polymicrobial sepsis. These results suggest that the increased catecholamine levels at .5-10 h after CLP may contribute to the hypermetabolic conditions that occur during early, hyperdynamic sepsis. However, there is a lack of an association between the elevated plasma catecholamine levels and hypometabolic/hypodynamic state in late sepsis.
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PMID:Sustained elevation in circulating catecholamine levels during polymicrobial sepsis. 856 55

Apoptosis (A O) is a pathological process by which cells undergo a form of inducible nonnecrotic cellular suicide. In vitro studies suggest that changes in the rate of macrophage (Mo) A O may be associated with elevated proinflammatory cytokine secretory capacity, such as interleukin-1 beta (IL-1 beta) (via IL-1 converting enzyme activation). Furthermore, it has been reported that Mo are activated during early (0-4 hours) experimental septic insult to act as sources of proinflammatory cytokines, such as IL-1. However, with the progression of sepsis, these same cells become refractory to further stimulation (appearing dysfunctional). Nonetheless, it remains unknown if this acquired immunosuppression (dysfunction) is associated with an acceleration in macrophage A O. To determine this, male C3H/HeN mice were subjected to sepsis (cecal ligation and puncture, CLP) or sham-CLP and 4 or 24 hours thereafter Mo were isolated from the peritoneum (PMo) and liver (KMo). Macrophage monolayers were lysed either after stimulation with lipopolysaccharide (LPS) (10 microgram/mL, 24 hours) in vitro or immediately (ex vivo) before LPS stimulation and the cytoplasmic cell fraction was retained. The extent of A O was determined using a cell-death enzyme-linked immunosorbent assay, which detects the presence of cytoplasmic oligonucleosomes and changes in the propidium iodide staining intensity. The results indicate that, early after CLP (4 hours) only PMo stimulated with LPS in vitro showed evidence of increasing A O. At 24 hours (late) after the onset of sepsis, the ex vivo extent of A O in PMo was increased but it was decreased in KMo. However, the addition of LPS in vitro results in a marked increase in both septic PMo and KMo A O. This latter result suggests that the inability of Mo to release cytokines in response to stiumulants, such as LPS during late sesis (24 hours), may be because of induciton of accelerated A O in these Mo populations.
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PMID:Is sepsis-induced apoptosis associated with macrophage dysfunction? 861 34

Apoptosis (Ao), is a process by which cells undergo a form of nonnecrotic cellular suicide. Although for most cells this is a constitutive process, it can be induced in immature and differentiating immune cell populations by stress mediators associated with inflammation. This inducible form of A(o) is referred to as programmed cell death. However, it is not clear whether hematopoietic cell populations such as the thymus and bone marrow are induced to undergo A(o) during polymicrobial sepsis. To assess this, thymocytes, bone marrow cells, or splenocytes (as a source of comparative nonhematopoietic cells) were harvested from C3H/HeN mice at 1, 4, or 24 hours after cecal ligation and puncture (CLP; to induce polymicrobial sepsis) or sham-CLP (Sham). The results showed that mixed bone marrow cells ex vivo, although not to the same extent as thymus, showed a marked increase in the percentage of cells in A(o), increased endonuclease activity, and a significant decrease in cell yield at 24 hours but not at 4 hours after CLP. Similar changes were not evident in splenocytes. Phenotypic, as well as morphologic assessment, indicated that most of the increase in apoptotic cells in the thymus was associated with the immature T cells (CD4+CD8+) and CD8-CD4- cells. In contrast, the increase in bone marrow cell A(o) was associated with only the B220+ cells, with no significant contribution from myeloid cells. Treatment of CLP mice in vivo with either RU-38486 or PEG-(rsTNF-R1)2 was unable to reverse the increased A(o) in the bone marrow of these animals. Taken together, these findings indicate that A(o) as a process induced by polymicrobial sepsis is not limited to the thymus, but can also be detected in the bone marrow. However, unlike thymic A(o), bone marrow is not affected directly/indirectly by glucocorticoids or tumor necrosis factor released during sepsis.
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PMID:Differential induction of apoptosis in lymphoid tissues during sepsis: variation in onset, frequency, and the nature of the mediators. 863 85

We postulated that the attenuated pulmonary and systemic vascular contractility observed in sepsis was secondary to the release of vasodilator prostaglandins. We used the cyclooxygenase inhibitor meclofenamate to inhibit prostaglandin synthesis in an unanesthetized, chronically instrumented model of hyperdynamic sepsis. Sixteen male Sprague-Dawley rats (300-350 g) were randomized to either sepsis induced by cecal ligation and perforation (CLP, n = 8) or a sham procedure (Sham, n = 8). Vascular reactivity was assessed by measuring the hypoxic (FiO2 = 0.08) pulmonary pressor response (HPV), and the systemic pressor response to an intravenous infusion of phenylephrine (1.5-7.5 micrograms/kg/min) before and after the administration of meclofenamate (5 mg/kg intravenously, i.v.). Twenty-four hours postoperatively, CLP animals had significantly increased cardiac output (CO) as compared with Sham animals (204 +/- 12 vs. 148 +/- 5 ml/min, p < 0.05), slightly decreased mean arterial pressure (MAP) (109 +/- 4 vs. 118 +/- 3 mm Hg, p < 0.05), and decreased total systemic vascular resistance (TSVR) (0.546 +/- 0.046 vs. 0.805 +/- 0.030 mm Hg.min.ml-1, p < 0.05). Mean pulmonary artery pressure (MPAP) and total pulmonary vascular resistance (TPVR) were similar in both groups (p > 0.05). In response to hypoxia, the change in MPAP (delta MPAP) was 3.6 +/- 1.0 and 6.9 +/- 0.8 (mm Hg) in CLP and Sham animals, respectively (p < 0.05). Similarly, the change in TPVR (delta TPVR) during hypoxia was 0.012 +/- 0.006 and 0.038 +/- 0.009 mm Hg.min.ml-1 in CLP and Sham (p < 0.05). The pulmonary and systemic blood pressure (BP) response to phenylephrine was also attenuated in CLP as compared with Sham animals. After treatment with meclofenamate, differences were no longer apparent in the HPV response between CLP and Sham animals, due to a slight increase in the HPV response of CLP animals and a slight decrease in the HPV response in Sham animals. The attenuated pressor response to phenylephrine was not changed in either the pulmonary or the systemic circulation after the administration of meclofenamate. These data suggest that vasodilator prostaglandins may contribute to the attenuated pulmonary pressor response in sepsis. However, the mechanism of the attenuated HPV may be different than the attenuated response to exogenous catecholamines since meclofenamate had no effect on either the pulmonary or systemic response to a phenylephrine infusion in septic animals.
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PMID:Cyclooxygenase inhibition and vascular reactivity in a rat model of hyperdynamic sepsis. 879 33

Melatonin administration has been reported to have beneficial effects on immune function in some clinical studies and in several animal models of immune dysfunction. Furthermore, recent studies suggest beneficial effects of melatonin on depressed immune function following trauma-hemorrhage. Nonetheless, it remains unknown whether this hormone has any salutary effects on survival following hemorrhagic shock and subsequent septic challenge. Male C3H/HeN mice were bled to and maintained at a mean arterial blood pressure of 35 +/- 5 mm Hg for 90 min, adequately resuscitated, and 48 hr thereafter subjected to sepsis (cecal ligation and puncture; CLP). Melatonin-treated mice received either short-term treatment on Days 1 and 2 after hemorrhage or continuous treatment throughout the study. Treatment with vehicle (10% ethanol in normal saline) or melatonin (10 mg/kg body weight) was administered daily starting in the evening of the day of hemorrhage/sham-operation. Short-term melatonin administration after hemorrhage significantly improved survival in animals subjected to septic challenge. Continuous melatonin treatment did not improve survival, as compared to vehicle-treated mice subjected to shock and CLP. Moreover, continuous melatonin treatment in sham-operated animals significantly increased mortality compared to short-term-treated and vehicle-treated animals. While the mechanisms of the differential effects of melatonin administration are yet to be clearly defined, this study, nonetheless, demonstrates the salutary effects of short-term melatonin administration in the treatment of immune dysfunction following hemorrhagic shock.
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PMID:Melatonin administration following hemorrhagic shock decreases mortality from subsequent septic challenge. 890 55

Recent studies indicate that polymicrobial sepsis can markedly increase inducible macrophage Ao (nonnecrotic cellular suicide) and that this is associated with decreased M phi function. In vitro studies suggest that M phi Ao can be induced by IL-1 beta via interleukin-1 beta-converting enzyme (ICE, a cysteine protease), prostanoids, or reactive oxygen/nitrogen. However, the mechanism(s) underlying this process in septic M phi remains unknown. To determine this, male C3H/HeN mice were subjected to sepsis (cecal ligation and puncture, CLP) or sham-operation. Twenty-four hours thereafter, M phi were isolated from the peritoneum (PM phi) and liver (LM phi). Macrophage monolayers were treated with LPS (10 micrograms/ml) alone (Cont) or in the presence of iodoacetamide (Iodo, 5 mM), N-methylmalamide (meth, 5 mM), ibuprophen (Ibu, 40 micrograms/ml), N-methyl-L-arginine (LNMA, 0.4 mM), or superoxide dismutase (SOD, 60,000 U/ml) for 24 hr. The extent of Ao was determined using an enzyme-linked immunosorbent cell-death assay, which detects the presence of cytoplasmic oligonucleosomes measured as optical density. The results indicate that both PM phi and LM phi from septic animals exhibit increased Ao over cells from sham animals. However, only the nonspecific cysteine protease inhibitors (Iodo and meth) and the NO inhibitor LNMA blocked septic mouse M phi Ao. Furthermore, only PM phi from CLP mice treated with Iodo, but not LNMA or IBU, showed an improved capacity to release IL-6. We conclude that increased M phi Ao seen during sepsis appears to be mediated by both ICE-like cysteine protease activation and NO release but the level/mechanism of action of these inhibitors differs.
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PMID:Inducible macrophage apoptosis following sepsis is mediated by cysteine protease activation and nitric oxide release. 924 58

The hemodynamic effects of sepsis have been attributed in part to increased nitric oxide (NO) production and activation of guanylate cyclase, resulting in increased cGMP and relaxation of vascular smooth muscle. Heme oxygenase-1 (HO-1), a heat shock protein, has been shown to increase intracellular cGMP levels by formation of carbon monoxide (CO). We hypothesized that HO may be an important mediator of the hepatic response to infection. Male Swiss Webster mice underwent standard cecal ligation and puncture (CLP, 18 gauge 2X) or sham operation, and received either normal saline (NS) or Zn protoporphyrin IX (ZN PP IX), a competitive HO inhibitor (n = 6-8/group). Hepatic tissue samples were collected at 3, 6, 12, and 24 hr from separate mice. Serum was collected at 3 and 24 hr. A semiquantitative reverse transcriptase polymerase chain reaction method was used to measure HO-1 mRNA levels. Hepatic cGMP levels were measured by ELISA. Groups were repeated (n = 10/group) to assess mortality. Serum was collected at 3 and 24 hr to measure serum aspartate aminotransferase (AST) levels. HO-1 mRNA expression increased significantly by 3 hr after CLP and with HO inhibition alone (P < 0.05 vs sham + NS). HO-1 mRNA remained elevated through 24 hr. CLP animals with HO inhibition showed a significant reduction of hepatic cGMP following CLP compared with CLP + saline at 24 hr (P < 0.05). Mortality was significantly increased in the CLP + ZN PP group at 24 hr (P < 0.05 CLP NS vs CLP ZN PP). CLP caused a marked increase in AST activity, which was increased further with HO inhibition. HO-1 mRNA expression was induced by CLP. AST levels following CLP were markedly increased with HO inhibition. HO-1 function appeared to contribute to elevation of hepatic cGMP during peritonitis and may be an important hepatic adaptive response to infection.
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PMID:Heme oxygenase-dependent carbon monoxide production is a hepatic adaptive response to sepsis. 927 Dec 71


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