Porins and lipopolysaccharide stimulate platelet activating factor synthesis by human mesangial cells.

Porins, a family of hydrophobic proteins located in the outer membrane of the cell wall of gram-negative bacteria and lipopolysaccharide (LPS), were shown to stimulate the synthesis of platelet activating factor (PAF), a phospholipid mediator of inflammation and endotoxic shock, by cultured human glomerular mesangial cells (MC). The synthesis of PAF induced by porins was rapid (peak at 20 min) and independent either from contamination by LPS or from generation of an endotoxin-induced cytokine such as tumor necrosis factor (TNF) since it was not prevented by cycloheximide, an inhibitor of protein synthesis or anti-TNF blocking antibodies. LPS also stimulated PAF synthesis by MC. However, the kinetic of PAF synthesis induced by LPS was biphasic with an early and transient peak at 10 minutes and a second and sustained peak at three to six hours. This second peak required an intact protein synthesis and was prevented by anti-TNF antibodies, suggesting the dependency on LPS-induced synthesis of TNF. Experiments with labeled precursors demonstrated that in MC, either after stimulation with porins or LPS, PAF was synthesized via the remodeling pathway that involves acetylation of 1-0-alkyl-sn-glyceryl-3-phosphorylcholine (2-lyso-PAF) generated from 1-0-alkyl-2-acyl-sn-glyceryl-3-phosphorylcholine by phospholipase A2 (PLA2) activity. Porins and LPS, indeed, induced PLA2-dependent mobilization of [14C]-arachidonic acid that was inhibited by p-bromodiphenacylbromide (PBDB). PBDB, an inhibitor of PLA2, also blocked PAF synthesis by preventing the mobilization of 2-lyso-PAF, the substrate for PAF-specific acetyltransferase.(ABSTRACT TRUNCATED AT 250 WORDS)     

Platelet-activating factor biosynthesis by cultured mesangial cells is modulated by proteinase inhibitors.

Rat mesangial cells stimulated with calcium ionophore A23187 and phagocytosis were shown to produce platelet-activating factor (PAF), a mediator of inflammation and endotoxic shock. In the study presented here, the cultured human mesangial but not epithelial cells synthetized PAF not only in response to calcium ionophore A23187 and phagocytosis of immunoglobulin G-coated latex beads, but also after stimulation with cytokines such as tumor necrosis factor-alpha and interleukin-1 beta. PAF synthetized after stimulation with A23187 and to a lesser extent with phagocytosis was partially released. In contrast, PAF synthesized by stimulation with tumor necrosis factor-alpha and interleukin-1 beta remained cell associated. Experiments with labeled precursors demonstrated that PAF was synthetized via the remodeling pathway that involves the activation of phospholipase A2 and of an acetyl-coenzymeA:2-lyso-PAF acetyltransferase. Synthetic inhibitors of serine proteases as well as plasma alpha 1-proteinase inhibitor inhibited the activation of phospholipase A2 detected as release of (14C) arachidonic acid and the activation of acetyl-CoA:2-lyso-PAF acetyltransferase at concentrations 100-fold lower than those present in plasma. This raises the question about the ability of mesangial cells to synthetize PAF in vivo. However, the inhibitory effect of plasma alpha 1-proteinase inhibitor may be abrogated by oxidative inactivation due to a concomitant stimulation of mesangial cell respiratory burst or in zones of close contact among cells or matrix, which have been shown to exclude antiproteinases.     

Role of Estrogens on Human Male Reproductive System

This review focuses on estrogen role on human male physiology. Biological estrogen actions on male reproductive system are summarized with particular regard to the effects of congenital estrogen deprivation in men. The effects of estrogen on spermatogenesis, hormonal secretion and gonadotropin feedback and on sexual behavior are discussed. It is remarked that the role of estrogens in male reproduction is a very recent acquisition in reproductive endocrinology, but it promises new future fields of research to be investigated as well as the possible disclosure of new strategies in clinical practice.     

The effects of regional and general anesthesia on blood pressure control after carotid endarterectomy

We retrospectively reviewed the influence of preoperative blood pressure control and regional vs. general anesthetic techniques on the incidence of intraoperative and postoperative (recovery room and intensive care unit) hypotension and hypertension in 249 carotid endarterectomy patients. Preoperative blood pressure was classified as uncontrolled hypertension (systolic blood pressure >/= 170 mm Hg and/or diastolic blood pressure >/= 95 mm Hg), controlled hypertension (blood pressure <170/95 mm Hg on chronic antihypertensive therapy), or normotension (blood pressure <170/95 mm Hg without antihypertensive therapy). Hypotension, as defined by the requirement for vasopressor administration to maintain a systolic blood pressure of at least 120 mm Hg, occurred more frequently after regional than after general anesthesia (p < 0.05). Postoperative hypertension was defined as a systolic blood pressure >/= 200 mm Hg and/or a diastolic blood pressure >/= 110 mm Hg in the recovery room or in the Intensive Care Unit. Preoperative hypertension was not associated with acute postoperative hypertension in the intensive care unit in either the regional anesthesia (n = 190) or the general anesthesia (n = 59) groups, although with either type of anesthesia, preoperative hypertension was associated with an increased incidence of hypertension in the recovery room (p < 0.01 regional; p < 0.005 general).     

Anti-endothelial cell antibodies in patients with Wegener's granulomatosis and micropolyarteritis

Anti-endothelial cell antibodies (AECA) have been detected by cell surface radioimmunoassay in nine out of 15 patients with micropolyarteritis (MPA) and in two out of five patients with Wegener's granulomatosis. AECA mostly belonged to the IgG isotype and were present in the active phase of the diseases. These antibodies were not detectable in 10 sera from patients with essential mixed cryoglobulinaemia, suggesting that they were not a mere epiphenomenon consequent to the inflammatory vascular injury. The binding activity was not related to ABH antigens or to HLA class I antigens displayed by resting human endothelial cells in culture and was not influenced by removing immune complexes. Absorption of the anti-neutrophil cytoplasmic antibodies (ANCA), present in MPA and Wegener's granulomatosis sera, did not affect the endothelial binding. AECA-positive sera did not display lytic activity against endothelial cells, neither alone nor after addition of fresh complement or normal human peripheral blood mononuclear cells. Although AECA are not cytolytic for endothelial cell monolayers in vitro, the reactivity against intact endothelial cells suggests their possible involvement in in vivo pathological processes affecting vascular structures in small vessel primary vasculitides.     

Differential modulation of mediator release from human basophils and mast cells by mizolastine

BACKGROUND: Basophils and mast cells play a major role in the pathogenesis of allergic disorders by releasing several proinflammatory mediators. Some histamine H1 receptor antagonists exert anti-inflammatory activities by modulating mediator release from basophils and mast cells. OBJECTIVE: To study the in vitro effects of mizolastine, an H1 receptor antagonist, on the release of eicosanoids, histamine and IL-4 from human basophils and lung mast cells. METHODS AND RESULTS: Mizolastine (10(-7)-10(-5) M) concentration-dependently inhibited the release of cysteinyl leukotriene C4 from anti-IgE-stimulated basophils (IC(50): 3.85+/-0.28 microM) and mast cells (IC(50): 3.92+/-0.41 microM). The same concentrations of mizolastine did not affect anti-IgE-induced prostaglandin D2 release from lung mast cells. In contrast, mizolastine enhanced up to 80% IgE-mediated histamine release (EC(50): 4.63+/-0.14 microM) from basophils, but not from mast cells and it significantly potentiated IL-4 release from basophils induced by anti-IgE. Mizolastine did not affect histamine release from basophils induced by formyl peptide, whereas it inhibited cysteinyl leukotriene C4 release (IC(50): 1.86+/-0.24 microM). Blockade of cytosolic phospholipase A2 and arachidonic acid mobilization by pyrrolidine-1 did not alter the effect of mizolastine on histamine release from basophils, thereby excluding accumulation of arachidonic acid metabolic intermediates as the cause of this effect. Mizolastine did not influence anti-IgE-induced activation of extracellular signal-regulated kinase-1 and -2 (ERK-1 and -2) in human basophils. CONCLUSIONS: Mizolastine efficiently inhibits LTC4 synthesis in human basophils and mast cells presumably by interfering with 5-lipoxygenase. In contrast, it enhances histamine and IL-4 release only from anti-IgE-stimulated basophils. Therefore, mizolastine differentially regulates the production of mediators from basophils and mast cells in a cell- and stimulus-specific fashion.     

Central nervous system involvement in systemic lupus erythematosus: a new therapeutic approach with intrathecal dexamethasone and methotrexate

Summary In systemic lupus erythematosus (SLE), neurological involvement has been reported to occur with frequencies ranging from 14% (severe cases) to 83% (mild forms included). In spite of early diagnosis and aggressive treatment, neuropsychiatric SLE may represent a serious problem of management. We describe three cases, one with acute transverse myelitis, one with hemiparesis, and one with signs of focal and diffuse cerebral dysfunction, in whom improvement following intrathecal therapy with methotrexate and dexamethasone was observed.     

Antiphospholipid antibodies and the endothelium

The interaction between aPL (particularly anti-beta 2GPI antibodies) and endothelium does represent a potential pathogenetic mechanism for the thrombotic manifestations of the syndrome. The autoantibody-mediated EC activation probably plays a role in sustaining the appearance of a proadhesive, proinflammatory, and procoagulant phenotype. The heterogeneity of the APS clinical manifestations is likely linked to the varied effects that aPL can induce on ECs and to the different functions that ECs display depending on the anatomic localization.     

A Review on Joint Carotid Intima-Media Thickness and Plaque Area Measurement in Ultrasound for Cardiovascular/Stroke Risk Monitoring: Artificial Intelligence Framework

Journal of Digital Imaging - Cardiovascular diseases (CVDs) are the top ten leading causes of death worldwide. Atherosclerosis disease in the arteries is the main cause of the CVD, leading to...