Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0036690 (sepsis)
 59,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Platelet-activating (PAF) is a putative mediator in endotoxemia and sepsis. Administration of a PAF receptor antagonist prior to endotoxin improves survival in rats and attenuates the hypotension of endotoxemia. Both PAF and endotoxin stimulate eicosanoid production. We hypothesized that a PAF receptor antagonist, BN 52021, would alter the hemodynamic events, improve the survival and attenuate the eicosanoid release associated with endotoxemia in a resuscitated, but lethal, canine model. Male dogs were randomzied to two groups (n = 10 each). Group I received only E. coli endotoxin, 1 mg/kg IV, at time 0, while group II received BN 52021, 5 mg/kg IV, 30 min before and again 240 min after endotoxin treatment. During the 4-h study period, hemodynamics were measured and blood samples were taken at 0, 2, 60, 120, and 240 min. Survival was determined at 24, 48, and 72 h. All group I animals died before 24 h; all group II lived longer than 72 h (P less than 0.05). In group I, plasma TXB2 values increased from a baseline value of 0.26 +/- .04 ng/ml to 4.38 +/- 1.56 ng/ml at 120 min and then decreased to 2.64 +/- .96 ng/ml by 240 min. For group II, respective plasma TXB2 values were 0.35 +/- 0.13 ng/ml at baseline, 0.58 +/- 0.14 ng/ml at 120 min, and 0.39 +/- .09 ng/ml at 240 min. At the 120-min and 240-min time points, the groups differed at P less than 0.05. Heart rate tended to be less in group II, but MAP was unaffected. In group I, pH values were more acidotic than those observed in group II.
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PMID:A PAF receptor antagonist, BN 52021, attenuates thromboxane release and improves survival in lethal canine endotoxemia. 166 Mar 55

PAF has been implicated as a mediator of shock, sepsis and MOF. The results of experimental data demonstrate that PAF induces changes characteristic of endotoxemia and sepsis, including systemic hypotension and diffuse microvascular leakage. These effects are prevented by PAF antagonists. PAF induces many of the characteristic changes of MOF, including functional impairment in the lung, kidney, gastrointestinal tract and heart. PAF antagonists will inhibit these adverse effects. PAF antagonists are now being manufactured by a number of pharmaceutical companies studying the beneficial effects of PAF antagonists in human disease. Data from these studies promise valuable information with significant clinical relevance to the practicing surgeon.
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PMID:The role of platelet activating factor and its antagonists in shock, sepsis and multiple organ failure. 185 37

Disseminated intravascular coagulation (DIC) or renal damage associated with septicemia was induced in rats by ligating the cecum or by injecting endotoxin. In the septicemia model, the number of E. coli and Bacteroides spp in the blood increased concomitantly with an increase of endotoxin. In this model the development of hypercoagulability with mild fibrinolysis was observed. Histopathologic findings in the kidneys, including the formation of microthrombi in the glomeruli and the vacuolization and dilatation of renal tubular cells, suggest the development of mild DIC. In the endotoxin-induced DIC model, both remarkable state of hypercoagulability and fibrinolysis were observed with fibrin thrombi in glomeruli. The administration of the platelet-activating factor antagonist, CV-6209, or of human antithrombin III, ameliorated DIC significantly by limiting the increases in prothrombin time, activated partial thromboplastin time and fibrin degradation products. These agents significantly reduced the deposition of fibrin in the glomeruli and significantly prolonged the survival time of the endotoxin injected rats. These observations suggest that the PAF antagonist CV-6209 and ATIII merit clinical evaluation in the management of DIC caused by septisemia.
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PMID:Effect of a platelet activating factor antagonist and antithrombin III on septicemia and endotoxemia in rats. 206 2

The catastrophe theory evolved by Thom and Zeeman proposes a mathematical definition for the abrupt or 'catastrophic' changes that can suddenly occur in normally well-ordered and smooth-running systems. We have integrated this theory with our own PAF/cytokine feedback network hypothesis to explain the control and dysfunction of the inflammatory response. This process involves the activation of cells and factors such as proteases, and is coordinated by mediators such as PAF, cytokines and growth factors, minute amounts of which can prime cells to respond in an enhanced manner to subsequent agonistic stimuli. PAF and certain cytokines also possess the unique property of being able to induce the release of each other and their own generation in vivo. This 'singularity' may enable a self-generating feedback network to become established. The priming ability of these mediators indicates the extreme sensitivity of the inflammatory process and importance of a homeostatic equilibrium between the vectors involved in the priming and feedback processes and internal suppressive mechanisms. In pathological conditions, one can consider the phenomenon of PAF and cytokine autogeneration as a 'fold' in the feedback network and an expression of the singularity characteristic of the catastrophe hypothesis. This may lead to systemic toxicity and microcirculatory collapse, a characteristic feature of shock, sepsis, asthma, ischemia and graft rejection. A combination of drugs antagonizing the various feedback components may inhibit this catastrophic process and thus provide more successful therapy of these conditions.
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PMID:PAF/cytokine auto-generated feedback networks in microvascular immune injury: consequences in shock, ischemia and graft rejection. 251 89

Platelet-activating factor causes pulmonary hypertension, shock, hypoxemia, neutropenia, and increased pulmonary vascular permeability; some of its effects are due to thromboxane A2 release. Evidence for a possible role of these mediators in the genesis of group B Streptococcus (GBS)-induced pulmonary hypertension was sought using specific receptor antagonists for PAF and thromboxane A2 (TxA2) in anesthetized, ventilated piglets (less than or equal to 12 d of age; n = 22). Infusion of 1 X 10(8) GBS/kg/min for one hour resulted in a sustained and significant increase in pulmonary artery pressure (PPA) from 17 +/- 1 to 35 +/- 3 torr. Pretreatment with the TxA2 antagonist SQ 29548 (0.75 mg/kg intravenous), completely inhibited the effect of GBS on PPA. Pretreatment with either platelet-activating factor antagonists SRI 63072 (3 mg/kg intravenous) or SRI 63441 (1 mg/kg) did not affect the pulmonary hypertension due to GBS infusion. GBS-induced pulmonary hypertension could be reversed by SQ 29548; SRI 63072 did not affect PPA when administered to pigs with GBS-induced elevation in PPA. Inasmuch as prevention and reversal of GBS-induced pulmonary hypertension are accomplished with the TxA2 antagonist but not with PAF antagonists, these data suggest that TxA2, rather than PAF, is responsible for the early pulmonary hypertension in this model of neonatal GBS sepsis. Therefore, TxA2 antagonists may be clinically useful in treating pulmonary hypertension related to GBS sepsis.
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PMID:Roles of platelet-activating factor and thromboxane in group B Streptococcus-induced pulmonary hypertension in piglets. 268 99

The aim of this chapter was to highlight the major components of PAF actions which lead to a state of shock, i.e. inadequate perfusion of essential organs which if sustained over a critical period of time, leads to irreversible damage in essential organs and eventually death. The heart, the pulmonary vessels and the microcirculation seem to be the primary target organs to PAF-induced hypotension. The effects of PAF on the pulmonary airways in some species (bronchoconstriction) might lead to hypoxemia and further exacerbate organ function. Thrombocytopenia, leukopenia and activation of the complement system are also important in PAF-induced shock by promoting thrombi formation and generation of multiple secondary mediators (e.g. histamine kinins, TXA2, leukotrienes, oxygen radicals). Identification of PAF production during specific or generalized pathophysiological processes is a critical step to implicate this vasoactive lipid in disease processes. So far, only limited information has been derived from studies involving immune responses (anaphylaxis) or bacterial endotoxins. Yet, the growing number of selective and potent PAF antagonists provide important information on the potential role of PAF in shock states. Such evidence, summarized in table I, is of great importance in designing new therapeutic strategies to a highly complex and lethal disease such as septicemia. However, the data summarized in table I clearly show that little is known on the mechanism of action of the various PAF antagonists. It is also important to note that PAF-induced shock and death can be prevented by drugs which are not necessarily PAF antagonists. For example, dexamethasone is extremely efficient in preventing PAF-induced shock and death in the mouse [24, 39] and thyrotropin releasing hormone in the guinea pig [15]. Therefore, it is conceivable that pathological conditions in which PAF might play a fundamental role might be reversed by pharmacological interventions which activate physiological mechanisms which can overcome and reverse the pathological processes activated by PAF. In conclusion, PAF is a powerful vasoactive lipid which can produce severe derangements in essential biological functions which can lead to death. The role of PAF in pathological processes in vivo is well supported in conditions such as anaphylaxis and endotoxemia. Yet, direct proof for PAF production in other shock states, such as multiple trauma, ischemia, inflammation and hemorrhage, is still missing. Furthermore, it is important to keep in mind that in shock, trauma or inflammation, multiple mediators in addition to PAF are formed.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Platelet-activating factor and shock. 304 32

Endotoxemia and gram negative sepsis remain a clinically important problem since mortality rate is still high in these diseases. Recently, the participation of some new potential mediators in this pathology is beginning to be demonstrated but the results obtained on animal models with specific inhibitors are contradictory. In order to clarify the pathological importance of icosanoids and PAF-acether in the septicemic process, we investigated the effects of indomethacin (IND) a cyclooxygenase inhibitor, NDGA and EP 10045 two lipoxygenase inhibitors, dexamethasone (DXM) a phospholipase A2 inhibitor and BN 52021 a PAF-acether receptor antagonist, on the Salmonella enteritidis-induced endotoxic shock (E.S.) in the rat. Injected subcutaneously 15 min before the test, NDGA, EP 10045 and IND were moderately effective when DXM completely prevented the endotoxin lethality. BN 52021 decreased the death rate in a dose-related manner and exerted at a non-active dose a synergistic effect on IND treatment. Furthermore, given orally 1 hour before endotoxin, it provided a potent protective effect. Our results seem to confirm that PAF-acether exerted alone, or in conjunction with products of the cyclooxygenase pathway, a key role in E.S. when LTs seem to play a role of minor importance.
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PMID:The relative role of PAF-acether and icosanoids in septic shock. 377 51

Gram-negative sepsis was induced in rats by intraperitoneal injection of Escherichia coli. The development of bacterial peritonitis and septicemia was monitored by counting the number of peritoneal cells and by performing cultures of blood samples. Mortality reached a 50% rate when rats were injected with 2 X 10(8) colony-forming units. Rats injected with the doses of bacteria which induced mortality showed a time- and dose-dependent increase of vascular permeability as judged by the presence of abundant peritoneal exudate and by the depletion of the circulating volume. In order to know whether the generation of PAF-acether could be involved in the development of the permeability changes, the formation of this mediator was measured in the peritoneal cells and spleen of animals at different times and in response to different doses of E. coli. Significant amounts of PAF-acether could be obtained preceding the development of blood volume depletion in response to the injection of doses of E. coli which induced both mortality and the development of permeability. These data suggest that PAF-acether might be one of the inflammatory mediators involved in the pathogenesis of the hemodynamic changes observed in endotoxemia.
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PMID:Synthesis of PAF-acether and blood volume changes in gram-negative sepsis. 388 98

Bacterial lipopolysaccharide (LPS) stimulates the production and release of endogenous mediators [e.g., tumor necrosis factor (TNF), interleukins-1 and -6 (IL-1 and IL-6), and Platelet Activating Factor [PAF] responsible for the pathophysiologic changes and the mortality associated with sepsis. We recently demonstrated that lysozyme (LZM) bound to LPS (LZM-LPS complex) suppresses LPS-induced tumor necrosis factor-alpha (TNF-alpha) production in vivo. In the present study, we investigated the effect of LZM-LPS complex formation on LPS-induced IL-6 production, both in vitro and in vivo. With the addition of LZM-LPS complex, TNF-alpha and IL-6 release was significantly reduced compared with that by LPS in a dose-dependent manner in mouse macrophage-like cells, RAW264.7. IL-6 production in serum by LPS in carrageenan (CAR)-primed mice peaked at 2 hr following injection. LZM-LPS and LZM-Escherichia coli cell complex (as 1 microgram of LPS per mouse) released significantly reduced concentrations of IL-6 in serum (P < 0.01 and P < 0.001 versus CAR-pretreated LPS- or cell-injected mice). These results emphasize the important role of LZM in vivo in the neutralization of endotoxin. However, in the case of IL-6, by administration of a lethal dose of LPS (as 100 micrograms of LPS per mouse), the IL-6 level was reduced by LZM, but a significant concentration of IL-6 was still released; although the TNF- alpha concentration was negligible in this experimental condition. Thus, it is suggested that LZM might regulate the systemic inflammation induced during Gram-negative bacterial infections by inhibiting the release of cytokines in serum.
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PMID:Lysozyme regulates LPS-induced interleukin-6 release in mice. 762 57

The study deals with an animal model for the problems of surgical intensive care patients. Following repeated applications of E. coli endotoxin WO 111:B4 under standard conditions, specific hemodynamic and biochemical (TNF, TXA2, PGI2, IL-6, PAF) and morphological (endothelium of the lung) alterations were detected. ARDS patterns induced by the sepsis were analyzed by high-frequency measurement of pressure and flow (385 measurements per breathing cycle). The role of the intestine in sepsis was investigated by ion-selective monitoring of surface potassium activity comparing mucosa and serosa. Every injection of endotoxin was followed by a selective increase of the potassium activity revealing relative ischemia induced by the endotoxin. The profile of the potassium levels on the surface correlates both with the cardiac output and with the prostacyclin levels. The continuous narrowing of the difference between mucosa and serosa, potassium during the period of investigation can be regarded as evidence for pathologic change in permeability fostering the septic course.
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PMID:[Septic shock and multiple organ failure in surgical intensive care. An animal experiment model on the analysis of pulmonary and intestinal dysfunction]. 769 Jan 6


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