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Query: UMLS:C0243026 (sepsis)
 52,417 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In sheep, endotoxin (LPS) causes pulmonary hypertension, hypoxemia, leukopenia, exudation of protein-rich lung lymph, reduced dynamic compliance (Cdyn), and increased resistance to airflow (RL), changes similar to those seen in human sepsis and sepsis-induced ARDS. We used well-described methods in the awake sheep-endotoxin model to evaluate the effectiveness of a commercially manufactured antibody to prevent the physiologic changes of endotoxemia. In awake sheep with chronic lung lymph fistulas, we used a whole-body plethysmograph to measure Cdyn, RL, and FRC. Pulmonary artery, left atrial, and systemic arterial pressures were recorded continuously. Arterial blood gases (for calculating AaPO2), leukocyte counts, and lymph samples were collected every 30 min. Animals received a 30-min (2 mg/kg) infusion of antiendotoxin antibody 4 h before LPS (0.75 micrograms/kg) challenge (n = 4), or were given a mixture of LPS (0.75 micrograms/kg) and antibody (2 mg/kg) that had been incubated in vitro at 37 degrees C for 30 min before infusion (n = 6). A control group given only 2 mg/kg of antibody (n = 4) showed no change in any measured parameter, whereas control animals receiving LPS alone (n = 6) exhibited a typical endotoxin response. In all animals receiving endotoxin, Cdyn declined by approximately 50% within 30 to 60 min, and RL increased approximately sixfold over a similar time course. Accompanying the abnormalities in lung mechanics were pulmonary hypertension, leukopenia, and widening of the AaPO2.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Studies of an antiendotoxin antibody in preventing the physiologic changes of endotoxemia in awake sheep. 222 82

Gram-negative bacterial sepsis remains a major cause of lethality in hospitalized patients, despite routine therapy consisting of antimicrobial agents, hemodynamic monitoring and fluid resuscitation, and metabolic support. Because a large body of evidence supports the concept that Gram-negative bacterial lipopolysaccharide (endotoxin, LPS) is responsible for many of the direct and host mediator-induced deleterious effects, recent work has been centered on the development and use of anti-LPS antibody preparations in order to ameliorate lethality. Both polyclonal and monoclonal antibody preparations directed against the common deep core/lipid A region of LPS are cross-reactive in vitro and cross-protective in vivo against a wide range of challenge organisms and LPS, and preliminary clinical trials indicate that a reduction in lethality may be possible. The precise endotoxin epitope against which antibody should be directed in order to maximize protection, however, has not been established. This modality most probably will become a standard form of adjunctive therapy within the next several years for the treatment of Gram-negative bacterial sepsis.
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PMID:Development and potential use of antibody directed against lipopolysaccharide for the treatment of gram-negative bacterial sepsis. 225 68

Infection occurring in patients suffering from severe trauma or burns often leads to hypotension, disseminated intravascular coagulation, multiorgan failure, and death. These latter pathophysiologic changes often are associated with Gram-negative sepsis and endotoxemia. Substantial progress has been made in understanding the effector mechanisms for endotoxin (LPS) action with the recognition of the importance of LPS-inducible products of cells of monocytic lineage in mediating LPS-induced injury. Here we will review recent evidence that supports a model for monocyte/macrophage activation by LPS that involves a plasma protein known as lipopolysaccharide binding protein (LBP) and the monocyte differentiation antigen, CD14.
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PMID:A new model of macrophage stimulation by bacterial lipopolysaccharide. 225 81

Acute pulmonary failure or ARDS in severely injured patients continues to be a significant problem. The most important clinical risk factor identified is sepsis syndrome. Sepsis syndrome is the clinical correlate of a malignant systemic inflammatory process and is directed in large part by the tissue-fixed macrophage (M phi), such as the alveolar M phi. The M phi is capable of producing most of the central inflammatory mediators responsible for the pathophysiology seen during sepsis and organ injury. Two major mediators are procoagulant activity (PCA), leading to diffuse microvascular thrombosis, and tumor necrosis factor (TNF), causing much of the physiologic derangement of sepsis. Endotoxins (LPS) derived from Gram-negative bacterial cell walls are the primary inflammatory stimulus for the tissue-fixed M phi production of inflammatory mediators. It is not completely known how LPS interacts with its various cellular targets, but it is hoped that knowledge of the molecular interactions involved in stimulation of the M phi by endotoxin will lead to therapies to modulate the response and prevent deleterious processes such as ARDS. In the present studies, LPS from E. coli 0111:B4 was shown in a dose response to stimulate large levels of both PCA and TNF in alveolar M phi. LPS from Bacteroides fragilis and Lipid X (the monosaccharide precursor of endotoxin) were unable to cause stimulation of the M phi in vitro. However, both moieties, B. fragilis LPS and Lipid X, were able to effectively and specifically compete with E. coli LPS and block M phi stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Endotoxin requirements for alveolar macrophage stimulation. 225 91

Lipid A is the toxic component of bacterial endotoxins (LPS) and LPS has been thought to be clinically important in Gram-negative bacterial sepsis, as well as in non-bacteremic states where endotoxemia of enteric origin may be deleterious. The presently accepted method of detecting both LPS and its common lipid A moiety is the Limulus lysate amebocyte assay (LAL), but this test cross-reacts with non-bacterial antigens and serum contains natural inhibitors to the reaction. As an extension of previous work using a polyclonal antibody, we have developed a rapid and sensitive monoclonal antibody assay for lipid A. This 3-step inhibition ELISA is reproducible in aqueous solutions and capable of detecting less than 10 pg/ml of this shared toxic endotoxin component. The assay does not detect intact LPS but acid hydrolysis releases the active lipid A for reaction. While already valuable in detecting lipid A in biological solutions, the presence of naturally occurring anti-lipid A immunoglobulins in serum interfere with the reaction and cause false positives in this inhibition assay. Clinical usefulness of the assay will depend on removal of these antibodies from serum prior to testing.
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PMID:A rapid sensitive monoclonal assay for lipid A in solution. 242 64

Intestinal mucosal atrophy, as induced by total parenteral nutrition (TPN) and/or prolonged bowel rest, is hypothesized to enhance bowel endotoxin (LPS) translocation and may alter host responses to infection. To examine the effect of TPN-induced bowel atrophy on the response to LPS, 12 healthy volunteers were randomized to receive either enteral feedings (ENT, n = 6) or seven days of TPN without oral intake (TPN, n = 6). Enteral or TPN feedings were terminated 12 hours before the study period when a constant dextrose infusion (50 mg/kg/hour) was initiated and continued throughout the subsequent study period. After placement of arterial, hepatic vein, and femoral vein catheters, metabolic parameters were determined before and for six hours after an intravenous E. coli LPS challenge (20 U/kg). Subsequent peak levels of arterial glucagon (ENT, 189 +/- 39 pg/mL; TPN, 428 +/- 48; p less than 0.01), arterial epinephrine (ENT, 236 +/- 52 pg/mL; TPN, 379 +/- 49; p less than 0.05) and hepatic venous cachectin/tumor necrosis factor (cachectin/TNF) (ENT, 250 +/- 56 pg/mL; TPN, 479 +/- 136; p less than 0.05) were significantly higher in the TPN group than in the ENT group. The extremity efflux of lactate (ENT, -16 +/- 4 micrograms/min-100cc tissue; TPN, -52 +/- 13; t = 2 hours; p less than 0.05) and of amino acids (ENT, -334 +/- 77 nmol/min-100cc tissue; TPN, -884 +/- 58; t = 4 hours; p less than 0.05) were higher in the TPN subjects after the endotoxin challenge. Circulating C-reactive Protein (CRP) levels measured 24 hours postendotoxin were also significantly higher in the TPN subjects (ENT, 1.7 +/- 0.2 mg/dL; TPN, 3.2 +/- 0.3; p less than 0.01). Hence the counter-regulatory hormone and splanchnic cytokine responses to LPS were enhanced after TPN and bowel rest. This is associated with a magnified acute-phase response, peripheral amino acid mobilization, and peripheral lactate production. Thus antecedent TPN may influence the metabolic alterations seen in infection and sepsis via both an exaggerated counter-regulatory hormone response as well as an enhanced systemic and splanchnic production of cytokines.
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PMID:Total parenteral nutrition and bowel rest modify the metabolic response to endotoxin in humans. 250 83

Dietary n-3 polyunsaturated fatty acids (PUFAs) have been reported to improve clinical outcome in a number of inflammatory diseases including burns and sepsis. One mechanism contributing to the anti-inflammatory effect is the incorporation of n-3 PUFAs into membrane phospholipids which decreases macrophage eicosanoid production. We hypothesize that an additional mechanism for their effects is an alteration of membrane signal transduction that decreases macrophage responsiveness to inflammatory stimuli. Kupffer cells, the fixed macrophages of the liver, were obtained from rats pair fed diets for 6 weeks with 15% of calories supplied as menhaden (high n-3), corn (control), or safflower (high n-6) oils. The effects of the dietary oils on Kupffer cell membrane signal transduction and eicosanoid production were assessed by measuring inositol phospholipid (PI) metabolism, intracellular calcium responses, and prostaglandin E2 (PGE2) production to the inflammatory signals endotoxin (LPS) and platelet activating factor (PAF). The menhaden oil diet resulted in significant incorporation of n-3 PUFAs into total cellular PUFAs compared to corn and safflower oil. (total n-3 PUFAs, 28.1% menhaden vs 2.1% corn vs 1.2% safflower, P less than 0.03). This incorporation altered signal transduction of PAF as both PI turnover (65% +/- 10% of corn oil) and calcium response (0.6-fold vs 5.0-fold for corn oil) were significantly reduced in the menhaden oil group. (P less than 0.05) The menhaden oil diet also reduced significantly PGE2 production in response to PAF and LPS (corn, 348 +/- 23 pg/ml; menhaden, 48 +/- 6 pg/ml, P less than 0.01). We conclude that, in addition to modulating eicosanoid production, n-3 PUFAs can also alter macrophage membrane signal transduction.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Modulation of Kupffer cell membrane phospholipid function by n-3 polyunsaturated fatty acids. 254 Dec 81

A novel intravenous therapy consisting of polyvalent IgG antibodies to lipopolysaccharide (LPS, endotoxin) obtained from screening of blood donors was used for treatment of patients with profound septic endotoxin shock. Investigation of the anti-LPS IgG pharmacokinetics in the 10 patients revealed time related changes in the plasma concentrations of anti-LPS IgG, endotoxin, tumour necrosis factor (TNF) and the clinical parameters. A decrease in serum concentrations of IgG and IgM antibodies to LPS was observed prior to the immunotherapy as well as in a clinical example of lethal septicemia without anti-LPS immunotherapy. Increasing serum concentrations of anti-LPS IgG during antibody infusion was followed by a decrease in the concentration of endotoxin and TNF. In survivors an IgM and IgG anti-LPS antibody response developed. Using clinical parameters and APACHE II clinical severity scores to measure the clinical condition, a beneficial effect was observed within 24 h corresponding to a decrease in the calculated expected mortality rate from more than 80% to about 50%. Five patients (55%) expired during the study. One patient died in the early septic shock phase. One patient expired due to superimposed hemorrhagic shock. Three immunosuppressed patients died 1-2 weeks after initial recovery, 1 with fungal sepsis and 2 patients due to pseudomonas infection.
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PMID:Preliminary study on treatment of septic shock patients with antilipopolysaccharide IgG from blood donors. 261 11

Pulmonary complications secondary to postburn sepsis are a major cause of death in burned patients. Using an in vitro organotypic culture system, we examined the effect of E. coli endotoxin (LPS) on lung cell surfactant synthesis. Our results showed that E. coli endotoxin (1.0, 2.5, 10 micrograms LPS/ml) was capable of suppressing the incorporation of 3H-choline into de novo synthesized surfactant, lamellar bodies (LB), and common myelin figures (CMF) at 50%, 68%, and 64%, respectively. In a similar study, we were able to show that LPS also inhibited 3H-palmitate incorporation by cultured lung cells. LPS-induced suppression of surfactant synthesis was reversed by hydrocortisone. Our results suggest that LPS may play a significant role in reducing surfactant synthesis by rat lung cells, and thus contribute to the pathogenesis of sepsis-related respiratory distress syndrome (RDS) in burn injury.
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PMID:Endotoxin suppresses surfactant synthesis in cultured rat lung cells. 264 10

TNF is a small protein secreted by activated monocytes and macrophages that mediates the in vivo effects of endotoxin. When injected into experimental animals, TNF reproduces the picture of septic or endotoxin shock. In addition, antibodies to TNF protect animals against the deleterious effects of IV injections of either LPS or live bacteria. Specifically, the available evidence suggests that TNF may be necessary for the organ injury and failure seen in sepsis. However, TNF probably is not the final common pathway to shock and tissue injury. Inhibition of cyclooxygenase is protective from the lethal effects of both LPS and TNF infusion, suggesting that prostanoids play an important, and perhaps more proximal role in the generation of tissue injury. In addition, TNF is produced and cleared from the blood-stream within a short period of time after an LPS stimulus, suggesting that TNF sets into motion a chain of events that may be self-perpetuating even in the absence of further TNF stimulus. In the near future, the treatment of sepsis may involve the administration of antibodies both to TNF and to LPS. Cyclooxygenase inhibitors should also begin to play a role in the therapy of sepsis. In the more distant future it is likely that we will be able to manipulate the state of activation of genes that code for TNF to exert some control over its production and secretion. It is perhaps within our grasp to finally reduce the morbidity and mortality of this lethal condition.
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PMID:Role of tumor necrosis factor in sepsis and acute lung injury. 264 25


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