Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027947 (neutropenia)
 17,527 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The present study demonstrates that CSA is capable of inhibiting indomethacin-induced leukocyte adherence to the vascular endothelium, and can reduce the severity of indomethacin-induced gastric mucosal injury. These results are therefore consistent with the hypothesis that leukocyte (particularly neutrophil) adherence is a critical event in the pathogenesis of NSAID-induced gastropathy. The mechanism through which CSA inhibits leukocyte adherence is not clear, and warrants further investigation. This study also confirmed the protective effects of IL-1 in experimental NSAID-gastropathy, and demonstrates that one of the ways the IL-1 may protect the mucosa is through its ability to inhibit the release of proinflammatory mediators (e.g., PAF) and promote the release of antiinflammatory mediators (e.g., nitric oxide). IL-1 modulated the release of these mediators from peritoneal mast cells at doses in the pg/ml to ng/ml range. IL-1 can inhibit the ability of neutrophils to respond to chemotactic stimuli and can prevent LTB4-induced neutropenia. Inhibition of neutrophil function by IL-1 may therefore account for its ability to reduce NSAID-induced gastric mucosal injury. Whether or not effects of IL-1 on the production of mediators such as nitric oxide and PAF is an underlying mechanism for the inhibitory effects on neutrophil function remains to be determined.
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PMID:Immunopathology of NSAID-gastropathy: inhibitory effects of interleukin-I and cyclosporin A. 145 66

The significance of the level of circulating 1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphorylcholine (C16-PAF, platelet-activating factor) in relation to transient neutropenia during hemodialysis with cuprophane membranes was examined. The neutrophil count was transiently and significantly decreased at 30 min after the start of hemodialysis, and it then gradually recovered during the period from 60 to 240 min after the start. Mirror image changes were observed in the circulating levels of C3a and C5a, suggesting that the decrease in the neutrophil count was triggered by activation of the complement factors. The circulating level of C16-PAF, although being similar to the basal level after 30 min of hemodialysis, was significantly increased after 60 and 120 min of hemodialysis. These data indicate that the increase in the circulating PAF level is not a direct cause of the transient decrease in the neutrophil count, but may be the result of activated neutrophils during hemodialysis with cuprophane membranes.
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PMID:Increases in circulating level of platelet-activating factor lag behind transient neutropenia during hemodialysis with cuprophane membranes. 175 37

Polymorphonuclear neutrophils (PMNs) play an important role in inflammation. Activated PMNs adhere to the vascular wall and release reactive oxygen radicals and enzymes, producing vascular injury. In the present study, we investigated whether PMNs play an important role in the pathogenesis of experimental necrotizing enterocolitis (NEC). NEC was induced in rats using platelet activating factor (PAF, 1 microgram/kg) and bacterial endotoxin (LPS, 1 mg/kg) intravenously. Neutropenia was accomplished by parenteral injection of Vinblastine (VB, 0.75 mg/kg) 4 days before the experiment to deplete the total white blood cell (WBC) and neutrophil counts. The animals were divided into 4 groups: (1) 1 microgram/kg PAF; (2) 1 mg/kg LPS; (3) 1 microgram/kg PAF + 1 mg/kg LPS; and (4) PMN depleted, 1 microgram/kg PAF + 1 mg/kg LPS. Combined administration of PAF and LPS produced prolonged hypotension (blood pressure 53.5 +/- 13.8 mm Hg at 2 hours), leukopenia (4,062 +/- 497.4), hemoconcentration (hematocrit 44.5% +/- 1.1%), reduced intestinal perfusion (74% +/- 13.3%), and segmental bowel necrosis. However, in VB-treated animals combined PAF + LPS induced only mild hypotension (84.3 +/- 9.2 mm Hg at 2 hours) and no hemoconcentration. In these animals the intestinal perfusion was normal, no bowel necrosis was observed, and the intestinal myeloperoxidase activity (.0034 +/- .0017 U/g tissue) was significantly lower than that of the nondepleted group (.0075 +/- .0012 U/g tissue). We conclude that the presence of neutrophils and/or neutrophil products play a major role in the pathogenesis of NEC.
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PMID:Experimental necrotizing enterocolitis: the role of polymorphonuclear neutrophils. 194 82

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 pathophysiology of anaphylaxis is very complex, and the sequelae of events are not fully explained in terms of the effects of histamine and peptide leukotrienes alone. Platelet-activating factor (1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine, PAF-acether) has been detected in animals undergoing anaphylaxis. Injection of synthetic PAF-acether induces similar effects, including bronchoconstriction, respiratory arrest, systemic hypotension, neutropenia, and thrombocytopenia. The results reported here demonstrate that the histamine- and leukotriene-independent component of guinea pig anaphylaxis in vivo and in isolated lung parenchymal strips in vitro is mediated by PAF-acether. However, PAF-acether is not responsible for the anaphylaxis-induced thrombocytopenia.
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PMID:Role of platelet-activating factor-acether in mediating guinea pig anaphylaxis. 308 8

Platelet activating factor is a multifaceted mediator of inflammation capable of stimulating platelet aggregation as well as anaphylaxis, neutropenia and numerous other in vitro and in vivo cellular changes. This lipid mediator, or autocoid, is released by a wide variety of inflammatory cells following an equally diverse group of cellular stimuli including phagocytosis or antigenic stimulation. The synthesized form of PAF is acetyl glyceryl ether phosphorylcholine (AGEPC). In this study AGEPC aggregated bovine platelets in a dose dependent manner. Maximal, irreversible aggregation occurred at 3.6 X 10(-11) M AGEPC with unwashed platelets and at 8.8 X 10(-12) M AGEPC with washed platelets. Aggregation failed to occur when platelets were tested with the biologically inactive structural analog of AGEPC. The possible contribution by platelet cyclooxygenase products was eliminated by showing lack of platelet aggregation to arachidonic acid and also by pretreating platelets with aspirin.
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PMID:Aggregation of bovine platelets by acetyl glyceryl ether phosphorylcholine (platelet activating factor). 643 5

Soluble and phagocytic stimuli released PAF-acether from PMN leucocytes, as determined by chromatography and bioassay by platelet aggregation. The same material caused aggregation of human and rabbit PMN leucocytes in vitro which was inhibited by ETYA and PGI2. PGI2 also inhibited PAF-acether release by PMN leucocytes and, in vivo, PGI2 abolished not only PAF-acether-induced, but also immune complex or C5a-induced thrombocytopenia and neutropenia in rabbits. These data suggest that PAF-acether may be involved in activation of both platelets and PMN leucocytes in vivo.
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PMID:Neutropenia induced by platelet-activating factor (PAF-acether) released from neutrophils: the inhibitory effect of prostacyclin (PGI2). 704 69

Platelet-activating factor (PAF; 100 ng i.v.) transiently modified the number of circulating neutrophils in the mouse, inducing a fast neutropenia (2 min) followed by a late onset neutrophilia (2 h). The potential involvement in PAF-induced neutrophilia of granulocytotic agents such as interleukin-1 and tumor necrosis factor-alpha could be excluded on the basis of the ineffectiveness of interleukin-1 receptor antagonist and of a specific monoclonal antibody anti-murine tumor necrosis factor-alpha. PAF granulocytosis was preceded by a significant rise in plasma corticosterone at 20 min. The involvement of endogenous corticosteroids was confirmed by the experiments with adrenalectomized mice and in animals pretreated with the steroid antagonist RU486 (11 beta-(4-dimethyl amino-phenyl) 17 beta-hydroxy, 17 alpha(prop-1-ynyl) estra 4,9-dien-3-one), where PAF-induced neutrophilia was greatly reduced (approximately 50%). Moreover, sustained increase in plasma corticosterone by administration of adrenocorticotropic hormone was paralleled by an intense neutrophilia. We show evidence that endogenous corticosterone acts through the glucocorticoid-inducible protein lipocortin 1.
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PMID:Endogenous corticosteroids mediate the neutrophilia caused by platelet-activating factor in the mouse. 749 25

1. Although recent observations suggest that endothelin-1 (ET-1) may play a role in the pathogenesis of asthma, to date little is known about the effects of ET-1 on parameters other than bronchoconstriction. The objectives of the present experiments were to study whether intravenously administered ET-1 could exert pro-inflammatory actions in the guinea-pig lung and to assess the involvement of endothelin ETA and ETB receptors in these events by using the ETA receptor-selective antagonist, FR 139317, the novel ETA/ETB receptor antagonist, bosentan and the ETB receptor-selective agonist, IRL 1620. 2. Bolus i.v. injection of ET-1 (0.1-1 nmol kg-1) to anaesthetized guinea-pigs evoked dose-dependent increases in mean arterial blood pressure which lasted for 6-12 min. This was accompanied by a dose-dependent haemoconcentration (8-15% plasma volume losses) and increases (up to 546%) in albumin extravasation in the trachea, upper and lower bronchi, but not in the pulmonary parenchyma. Qualitatively similar changes were observed following i.v. injection of the ETB receptor agonist, IRL 1620 (0.3 and 1 nmol kg-1), although IRL 1620 appeared to be about 3 times less potent than ET-1. The ETA receptor-selective antagonist, FR 139317 (2.5 mg kg-1) inhibited the ET-1 (1 nmol kg-1)-induced pressor response, haemoconcentration and albumin extravasation by 75, 77 and 60-70%, respectively, whereas it did not attenuate IRL 1620 (1 nmol kg-1)-induced changes. The ETA/ETB receptor antagonist, bosentan (10 mg kg-1) almost completely inhibited the pressor, haemoconcentration and permeability effects of both ET-1 and IRL 1620. 3. ET-1, but not IRL 1620 (0.1-1 nmol kg-1), produced a dose-dependent neutropenia with relative lymphocytosis and monocytosis, but did not induce influx of neutrophil granulocytes into pulmonary tissues or the bronchoalveolar space. ET-1 (1 nmol kg-1)-induced neutropenia was prevented by pretreatment of the animals with FR 139317 (2.5 mg kg-1), bosentan (10 mg kg-1) or adrenaline (90 nmol kg-1), indicating that ET-1 caused intravascular sequestration of neutrophil granulocytes. 4. ET-1 or IRL 1620 (10(-10)-10(-6) M) alone did not activate alveolar macrophages in vitro, whereas at a concentration of 10(-8) M, ET-1, but not IRL 1620, markedly potentiated superoxide production in response to f-Met-Leu-Phe (10(-9)-10(-7) M) and platelet-activating factor (PAF, 10(-9)-10(-7) M), but not to phorbol 12-myristate 13-acetate (10(-9) M). ET-1 did not affect f-Met-Leu-Phe- or PAF-induced increases in intracellular free calcium concentration. This potentiating effect of ET-1 was abolished by FR 139317(1.5 X 10-7 M).5. We conclude that, in addition to evoking airway contractions, ET-1 exerts pro-inflammatory actions via activation of the ETA and to a lesser extent the ETB receptors, and therefore, might contribute to the airway inflammation present in asthma. These findings also suggest the therapeutic potential of ETA/ETB receptor and perhaps ETA receptor-selective antagonists in this disease.
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PMID:Acute pro-inflammatory actions of endothelin-1 in the guinea-pig lung: involvement of ETA and ETB receptors. 767 Jul 25

Inhaled PAF provokes bronchoconstriction, causes peripheral blood neutropenia with rebound neutrophilia, and generates urinary production of the bronchoconstrictor eicosanoids, thromboxane (TX)A2, and the cysteinyl leukotrienes. We examined the effects of an oral PAF antagonist UK,74505 on each of these responses to a single 36 micrograms dose of inhaled PAF. In a double-blind randomized placebo-controlled crossover study, 12 normal male subjects inhaled PAF on two consecutive days, 3 and 24 h after intake of two doses of UK,74505 25 mg and 100 mg, or matched placebo (P). After P, inhalation of PAF provoked bronchoconstriction, measured at regular time points for 60 min as a change in sGaw from baseline and computed as area under the curve (AUC), induced a neutropenia at 5 min and rebound neutrophilia at 2 h, and stimulated production of urinary eicosanoids. Bronchoconstriction was maximal at 5 min but had receded at 1 h; (AUC mean [95% Cl]; 20.0 [13.2, 26.8] at 3 h; 11.0 [5.3, 16.6] at 24 h) and was completely abolished by both doses of UK,74505 at 3 h and by the higher 100 mg dose at 24 h. PAF-induced neutropenia and rebound neutrophilia were abolished by both doses of drug; neutropenia at 5 min (expressed as mean [95% Cl] change from baseline; -2.5 x 10(9)/L [-2.9, -2.1] after P; -0.3 [-0.7, 0.1] after 25 mg; 0.1 [-0.3, 0.4] after 100 mg), neutrophilia at 2 h (2.0 [-1.3, 2.6] after P; -0.2 [-0.8, 0.5] after 25 mg; -0.1 [-0.8, 0.5] after 100 mg).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Inhibitory effect of UK,74505, a potent and specific oral platelet activating factor (PAF) receptor antagonist, on airway and systemic responses to inhaled PAF in humans. 802 68


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