[Inflammatory mechanisms associated with acute coronary syndrome].
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Acute Disease↗
Biomedical subjects
G Emanuelli
Publications and source records attributed to G Emanuelli.
Role of platelet activating factor in acute pancreatitis induced by lipopolysaccharides in rabbits.
In the present study we demonstrated that a single injection of endotoxin (lipopolysaccharides, E. Coli 0111-B4) into the superior pancreaticoduodenal artery of rabbits induced a dose-dependent acute necrotizing pancreatitis. The lesions observed by light microscopy were significant for 10 micrograms lipopolysaccharides and were maximal for 20 micrograms. After 24 h the main findings were edema, acinar cell vacuolisation, polymorphonuclear neutrophil infiltration and tissue necrosis. The pancreatic lesions developed strictly in the area supplied by the artery injected with lipopolysaccharides, without significant intestinal involvement. Since platelet-activating factor (1-O-hexadecyl-2-acetyl-sn-glycero-3- phosphocholine, PAF; 50-500 ng), a phospholipid mediator of endotoxin-induced inflammation and shock, was previously shown to cause an acute necrotizing pancreatitis in rabbits, the role of PAF in the development of acute pancreatitis induced by lipopolysaccharides was studied by evaluating: (1) the synergism between doses of lipopolysaccharides (5-10 micrograms), which produced a mild tissue injury, and doses of PAF (10 ng) not producing, per se, any significant injury, and (2) the effect of three structurally unrelated PAF receptor antagonists. The results obtained demonstrated that 10 ng of PAF significantly potentiated pancreatic tissue damage induced by 10 micrograms of lipopolysaccharides.(ABSTRACT TRUNCATED AT 250 WORDS)
Acute Disease↗
Tumor necrosis factor alpha-induced angiogenesis depends on in situ platelet-activating factor biosynthesis.
Tumor necrosis factor (TNF) alpha, a potent inhibitor of endothelial cell growth in vitro, is angiogenic in vivo. Therefore, it was suggested that the angiogenic properties of this agent might be consequent to the production of secondary mediators. Since TNF-alpha stimulates the synthesis of platelet-activating factor (PAF) by monocytes and endothelial cells, we investigated the possible involvement of PAF in the angiogenic effect of TNF-alpha. Angiogenesis was studied in a murine model in which Matrigel was used as a vehicle for the delivery of mediators. In this model the angiogenesis induced by TNF-alpha was shown to be inhibited by WEB 2170, a specific PAF receptor antagonist. Moreover, in mice injected with TNF-alpha, PAF was detected within the Matrigel, 6 and 24 h after TNF-alpha injection. The synthesis of PAF within the Matrigel was concomitant with the early migration of endothelial cells and infiltration of monocytes. No infiltration of lymphocytes or polymorphonuclear leukocytes was observed. Synthetic PAF as well as PAF extracted and purified from mice challenged with TNF-alpha induced a rapid angiogenic response, inhibited by WEB 2170. These results suggest that the angiogenic effect of TNF-alpha is, at least in part, mediated by PAF synthesized from monocytes and/or endothelial cells infiltrating the Matrigel plug.
Animals↗
Inflammatory pseudotumour of the liver: diagnosis by fine needle biopsy in two cases and a review of the literature.
Inflammatory pseudotumours of the liver are rare: over 40 cases had been reported up to 1992, the majority of which are surgical or laparoscopic findings. In this paper we describe two additional cases in which diagnosis was acquired by fine needle biopsy under ultrasonographic guidance. This approach allowed sufficient sampling of tissue for diagnostic purposes.
Aged↗
Streptokinase induces intravascular release of platelet-activating factor in patients with acute myocardial infarction and stimulates its synthesis by cultured human endothelial cells.
BACKGROUND: Reocclusion of a successfully recanalized infarct-related artery may account for failure of thrombolytic therapy. Evidence suggests that the intravascular activation of platelets may limit the response to this treatment. The aim of the present study was to investigate whether platelet-activating factor (PAF), an ether lipid mediator with multiple potent biological activities, is synthesized during therapy with thrombolytic agents. Two sets of experiments were performed: (1) we extracted and quantified PAF in blood of patients with acute myocardial infarction treated or untreated with streptokinase (SK), and (2) since the endothelium/platelet interaction is thought to be at the basis of vascular reocclusion, we studied whether cultured human endothelial cells synthesize PAF after stimulation with SK or plasmin. METHODS AND RESULTS: PAF was extracted from blood samples immediately after acidification to destroy the acid-labile PAF-acetylhydrolase in 25 patients with acute myocardial infarction treated (group A, n = 14) and untreated (group B, n = 11) with intravenous infusion of SK. PAF was detected in 10 of 14 patients of group A and none of group B. PAF began to be detectable 60 to 90 minutes after SK infusion and disappeared from the circulation within 120 to 180 minutes. Percent variation of platelet count over basal values correlated negatively with the amount of PAF present in the circulation at 90 minutes (r = -.719; P < .001) and at 120 minutes (r = -.652; P < .001). Cultured human umbilical cord vein-derived endothelial cells (ECs) synthesized PAF in a dose-dependent manner in response to SK and plasmin, with a synthesis that peaked at 15 minutes and persisted up to 30 minutes for SK and 2 hours for plasmin. PAF extracted from blood samples or from ECs was quantified by bioassay performed after purification by thin-layer chromatography and high-performance liquid chromatography (HPLC). PAF-bioactive material was characterized as PAF with physicochemical and enzymatic treatments, HPLC-tandem mass spectrometry, and specific PAF-receptor antagonists. CONCLUSIONS: The observation that PAF was detectable in the blood of patients of group A only after treatment with SK and was not detectable in patients with a comparable infarct not treated with SK (group B) suggested that SK stimulates the synthesis of this mediator either directly or via plasmin generation. Indeed, cultured human ECs synthesize PAF after stimulation with both SK and plasmin. PAF production by ECs may promote platelet activation and interaction of these cells as well as of circulating leukocytes with endothelium. These events may limit the beneficial effects of thrombolytic therapy.
Cells, Cultured↗
Role of platelet-activating factor in hypotension and platelet activation induced by infusion of thrombolytic agents in rabbits.
Infusion of the thrombolytic agents streptokinase (SK, 666 units/kg per minute for 60 minutes) and tissue-type plasminogen activator (t-PA, 10 micrograms/kg per minute for 15 minutes) in rabbits induced a significant hypotension and decrease in platelet count that were completely prevented by treatment with platelet-activating factor (PAF) receptor antagonists SDZ 63-675 and WEB 2170. PAF synthesis by vascular tissue was suggested by its extraction from blood-free heart and aorta of rabbits treated in vivo with SK or t-PA but not of control rabbits. In contrast, PAF was not detected in peripheral blood. Ex vivo studies on platelet aggregation response to ADP and PAF performed on platelet-rich plasma obtained before and after SK and t-PA infusion demonstrated an early hyperaggregable phase, abrogated by PAF receptor antagonists and followed by reduced sensitivity of platelets to PAF. The ED50 values for the aggregation of washed rabbit platelets induced by PAF but not thrombin were significantly increased at 60 and 120 minutes after SK and t-PA infusion, suggesting a specific desensitization of platelets to PAF. In contrast to PAF receptor antagonists, aspirin did not significantly modify the hypotension and the platelet hyperaggregability induced by SK or t-PA or the platelet hypoaggregability induced by t-PA. Thrombocytopenia induced by t-PA, but not by SK, was partially prevented by aspirin. The effect of SK, t-PA, and plasmin on the aggregation of washed platelets from untreated rabbits and from humans was also studied. Whereas SK and t-PA were inactive, plasmin induced dose-dependent platelet aggregation that was inhibited by platelet pretreatment with PAF receptor antagonists. In conclusion, the effect of PAF receptor antagonists observed in the present experimental model suggests that the hypotension and activation of platelets induced by SK and t-PA infusion are mediated by PAF.
Animals↗
The des-gamma-carboxyprothrombin for the diagnosis of hepatocellular carcinoma.
Des-gamma-carboxyprothrombin level was measured by enzyme immunoassay in the plasma of 39 patients suffering from hepatocellular carcinoma and 26 controls. Two of these were anticoagulated by warfarin and revealed very high positive values; the remaining 24, 8 healthy subjects and 16 patients with cirrhosis or chronic hepatitis, were negative. Values indicating pathology were found in 56.40% of patients suffering from hepatocellular carcinoma. All malignancies presenting diameter < or = 3 cm were negative, while high positive levels were found in patients with more advanced neoplasia. The alpha-fetoprotein was increased in 43.58% of the patients with hepatocellular carcinoma and in 6.25% of controls with chronic liver diseases. Positive values for both des-gamma-carboxyprothrombin and alpha- fetoprotein were detected in 12/39 patients. An increase of sensitivity (from 43.58 to 69.23%) in detecting hepatocellular carcinoma was found by the complementary use of the two markers relative to sole use of alpha-fetoprotein.
Adult↗
Role of platelet-activating factor in polymorphonuclear neutrophil recruitment in reperfused ischemic rabbit heart.
This study investigated the role of platelet-activating factor in the recruitment of polymorphonuclear neutrophils (PMN) in a rabbit model of cardiac ischemia and reperfusion. The accumulation of PMN was evaluated 2 and 24 hours after removal of 40 minutes of coronary occlusion by morphometric analysis and 111In-labeled PMN infiltration. The administration of two structurally unrelated platelet-activating factor-receptor antagonists (SDZ 63-675, 5 mg/kg body weight, and WEB 2170, 5 mg/kg body weight) before reperfusion significantly reduced the accumulation of PMN, as well as the hemodynamic alterations and the size of necrotic area. Two hours after reperfusion, the percentage of increase of 111In-labeled PMN in transmural central ischemic zone was significantly reduced in rabbits pretreated with SDZ 63-675 (51.4 +/- 7.9) or WEB 2170 (32.4 +/- 8.8) with respect to untreated rabbits (107.6 +/- 13.5). The morphometric analysis of myocardial sections confirmed the reduction of PMN infiltration at 2 hours and demonstrated that at 24 hours the phenomenon was even more significant. In addition, SDZ 63-675 and WEB 2170 prevented early transient bradycardia and hypotension and reduced the infarct size, judged by staining with tetrazolium at 2 and 24 hours after reperfusion, and by histological examination at 24 hours. These results suggest that platelet-activating factor is involved in the accumulation of PMN in the reperfused ischemic myocardium and contributes to the evolution of myocardial injury.
Animals↗
[The role of surgery in the prevention of pulmonary thromboembolism].
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Anticoagulants↗
Endotoxin tolerance and polymyxin B modify liver damage and cholestasis induced by a single dose of alpha-naphthylisothiocyanate in the rat.
A single oral dose of alpha-naphthylisothiocyanate (ANIT) induces intrahepatic cholestasis and endotoxemia in the rat. To assess if a pathogenic relationship between endotoxin and ANIT-induced liver injury could be postulated, rats were pretreated by either induction of endotoxin tolerance, or with the anti-endotoxin agent polymyxin B. A single oral dose (10 or 20 mg/100 g body wt) of ANIT was then given to ascertain whether these methods of modifying endotoxicity would protect the animals against ANIT damage. Both pretreatments significantly reduced the incidence of endotoxemia after ANIT administration, as detected by either lead acetate enhancement method or the Limulus gelation test (LGT). The lethality of a single 20 mg/100 g body wt dose of ANIT was reduced from 55% to 15% by polymyxin B administration, and to 10% by an endotoxin-tolerant state. Moreover, when 10 mg/100 g body wt ANIT was given none of the animals died in 10 days, and the serum levels of bilirubin, alkaline phosphatase (AlPh), gamma-glutamyl transferase (gamma-GT), and transaminases (evaluated 1, 2, and 5 days after treatments) were significantly lower in the endotoxin-tolerant or polymyxin B administered rats; this biochemical protection was mirrored in the lack of histological alteration. The results demonstrate that the modification of endotoxicity offers significant protection against acute liver damage induced by ANIT. Thus the development of endotoxemia may play a pathogenic role in ANIT-induced liver injury. This conclusion is supportive of the hypothesis that endotoxins are necessary for the hepatotoxic agent to exert its full effects.
1-Naphthylisothiocyanate↗
Platelet-activating factor (PAF) induces platelet/neutrophil co-operation during myocardial reperfusion.
The purpose of this study was to evaluate the role of platelet-activating factor (PAF) in cardiac dysfunctions occurring in ischemic isolated rabbit heart reperfused in the presence of polymorphonuclear neutrophils (PMN) and platelets (PLT). In a first set of experiments two different PAF-receptor antagonists were used to investigate the role of endogenous PAF released in the coronary vessels of post-ischemic heart. Mechanical and electrical dysfunctions occurring during reperfusion of ischemic heart were worsened in the presence of both PMN and PLT. Co-operation between PMN and PLT was suggested by the absence of effect when reperfusion was done with PMN alone, and by the significant enhancement of the effect of PLT after addition of PMN. The activation of PMN and PLT was mediated by PAF, since it was prevented by receptor antagonists SDZ 63-675 (3 x 10(-6)M) and WEB 2170 (3 x 10(-6)M). In a second set of experiments, the infusion of PAF in non-ischemic rabbit heart perfused with PMN and PLT was used to evaluate whether PAF can induce PMN-PLT interaction and reproduce the effects of ischemia. In this condition, the infusion of synthetic PAF (1 x 10(-7)M) induced mechanical and electrical dysfunctions similar to that occurring during reperfusion. The protective effect of both PAF receptor antagonists (SDZ 63-675 and WEB 2170) and of a leukotrienes receptor antagonist (FPL 55712, 1 x 10(-6)M) suggested that PAF is the mediator that triggers the co-operation between PMN and PLT, while leukotrienes produced by these cells are the final effector of cardiac dysfunction. In conclusion, these results suggested that PAF released during reperfusion of ischemic rabbit heart may amplify mechanical and electrical dysfunctions by triggering PMN-PLT co-operation.
Animals↗
Antibodies to Mycobacterium paratuberculosis in patients with Crohn's disease.
IgG antibodies against Mycobacterium paratuberculosis protoplasmic antigen were looked for by an enzyme immunosorbent assay in patients with Crohn's disease, Ulcerative colitis, active pulmonary tuberculosis, past pulmonary tuberculosis, and in healthy controls. Serum reactivity for these antibodies was not correlated to PPD skin test positivity without history of mycobacterial disease. A cutoff based on the mean absorbance value of a pool of healthy blood donors was chosen. Positive values were found in 12/24 (50%) patients with active pulmonary tuberculosis and 2/10 (20%) skin-test-positive subjects with past pulmonary tuberculosis as expected, because antigenic sharing is common among different mycobacteria. The control group of blood donors showed borderline positivities in 3/149 cases (2.01%). Positive values were found in 4/108 (3.70%) patients with Crohn's disease and 2/40 (5%) with ulcerative colitis. We conclude that our data do not support a causal relationship between the M. paratuberculosis and Crohn's disease, but occasional patients with inflammatory bowel diseases show unexpected positivities for these mycobacterial antibodies.
Adolescent↗
Effects of diltiazem on thromboxane B2 production from platelet-rich plasma and whole blood.
The present study evaluated the effects of the calcium-channel blocking agent diltiazem on platelet aggregation and on synthesis of thromboxane B2 (the stable metabolite of thromboxane A2) from platelet-rich plasma (PRP) and whole blood samples. Our results showed that diltiazem inhibits collagen- and thrombin-induced platelet aggregation and TXB2 production from PRP. Since no significant interference with conversion of arachidonate to thromboxane A2 was demonstrated, inhibition of phospholipase A2 activity may be the prevailing mechanism of the diltiazem effect. The drug demonstrated a dose-related inhibitory activity on TXB2 synthesis from whole blood samples during spontaneous clotting or following stimulation with collagen or thrombin. The present results give further evidences for an antiplatelet activity of diltiazem and support the hypothesis that inhibition of platelet function contributes to the therapeutic efficacy of this drug in the treatment of cardiovascular diseases.
Adult↗
A double blind randomized placebo-controlled study demonstrates the protective efficacy of rosaprostol on aspirin-induced gastrointestinal bleeding in man.
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Adult↗
[Nutrition and andrological problems].
Andrologic problems were considered as nutrition is concerned: vitamin and oligo-element deficiencies, metabolic alterations, and toxic intake. Ethanol role was examined and discussed for its relevance in psychological and organic impairment due to both chronic abuse and acute intake, mainly for its role on hypothalamic-pituitary-gonadal axis. Rational nutrition is a clue in sexual disturbance prevention, correction and integrated care.
Alcoholism↗
Studies on inhibition of human platelet response by diltiazem.
1. Aim of the present investigation was to investigate the effects of calcium blocking agent diltiazem on human platelet response to aggregating agents. 2. Results showed that diltiazem inhibits platelet aggregation induced by ADP, arginine vasopressin, adrenaline, collagen, Na arachidonate, thrombin and phorbol ester PMA in a dose-dependent way. 3. Diltiazem decreased also beta-thromboglobulin release and Thromboxane B2 production from stimulated platelets. 4. Intraplatelet cyclic AMP levels were not modified by the substance. 5. Data provide evidence that the modulation of human platelet function by diltiazem could be also related to inhibition of protein kinase C.
Adult↗
Arginine vasopressin release from human platelets after irreversible aggregation.
1. The release of arginine vasopressin from human platelets was investigated in platelet-rich plasma after irreversible aggregation induced by adenosine 5'-pyrophosphate, collagen, sodium arachidonate, thrombin and adrenaline in vitro. 2. Arginine vasopressin levels were significantly higher in the supernatant from stimulated platelet-rich plasma than from unstimulated samples, reaching 3.5 X 10(-12) (range 1.6-12.5 X 10(-12) mol/l in the absence of an aggregating agent, 8.8 X 10(-12) (range 4.2-17.5 X 10(-12) mol/l after adenosine 5'-pyrophosphate, 13.7 X 10(-12) (2.2-63.2 X 10(-12) mol/l after collagen, 7.8 X 10(-12) (2.2-14.6 X 10(-12) mol/l after sodium arachidonate, 7.8 X 10(-12) (2.2-16.3 X 10(-12) mol/l after thrombin and 12.2 X 10(-12) (4.8-32.1 X 10(-12) mol/l after adrenaline. 3. An arginine vasopressin level of 18 X 10(12) mol/l, which can be achieved physiologically, increased the sensitivity of platelets to adenosine 5'-pyrophosphate and collagen in vitro; the same concentration of arginine vasopressin caused a potentiation of the effect of catecholamines on the response of platelets to sodium arachidonate. 4. These results indicate that intraplatelet arginine vasopressin is released during aggregation and suggest that a local release of arginine vasopressin could occur after complete platelet aggregation in vivo.
Adenosine Diphosphate↗
Desensitization of the platelet aggregation response to adrenaline during insulin-induced hypoglycaemia in man.
The aim of the present study was to investigate the influence of insulin-induced hypoglycaemia on platelet sensitivity to adrenaline and non-adrenergic agonists in man. Twenty-five healthy male subjects volunteered for the study. To evaluate the effects on platelets of different insulin-adrenaline interrelationships, two experimental models were used. In the first, hypoglycaemia was induced by a 60-min IV infusion of human insulin at the rate of 64 mU m-2 min-1, whereas in the other the same insulin dose was administered as an IV bolus (3.84 U m-2). Throughout the studies, plasma glucose, insulin, and adrenaline were measured together with platelet sensitivity to adrenaline, ADP, platelet activating factor, collagen, and sodium arachidonate. In both studies, hypoglycaemia induced a reduction of platelet sensitivity to adrenaline (p = 0.006 in infusion and p = 0.045 in injection study). In particular, maximal aggregation to adrenaline fell from 47.9 +/- 9.9 (+/- SE) to 31.1 +/- 11.3% at the hypoglycaemic nadir in the infusion study, and from 64.6 +/- 8.2 to 34.6 +/- 10.3% at the hypoglycaemic nadir in the injection study. In the injection study an increase of platelet sensitivity to ADP (p = 0.05), platelet activating factor (p = 0.018), sodium arachidonate (p = 0.035), and collagen (p = 0.027) was also found, in agreement with observations already published using the infusion protocol. Thus, insulin-induced hypoglycaemia increases platelet sensitivity to non-adrenergic agonists and decreases platelet response to adrenaline.
Adenosine Diphosphate↗