Differential effects of antigens from L. braziliensis isolates from disseminated and cutaneous leishmaniasis on in vitro cytokine production

Background  

Disseminated leishmaniasis is an emerging infectious disease, mostly due to L. braziliensis, which has clinical and histopathological features distinct from cutaneous leishmaniasis.     

Invasive line placement in critically ill patients: do hemostatic defects matter?

BACKGROUND: Blood components are often given prophylactically before the placement of invasive lines in patients with coagulation defects. Little, however, is known about the epidemiology of defects in these patients. The purpose of this study is to ascertain what proportion of intensive care patients who receive invasive lines have hemostatic defects, what actions are taken by physicians to correct these abnormalities before invasive line insertion, and what the incidence is of bleeding complications after invasive line placement. STUDY DESIGN AND METHODS: Charts were retrospectively reviewed for 490 intensive care patients in whom 938 arterial, pulmonary artery, and central venous lines were placed. RESULTS: At least one defect in hemostasis was documented for 388 patients (41%) before line placement, with 253 (27%) of these patients evidencing severe abnormalities. Seventeen percent of patients had no preprocedure laboratory evaluation. Trauma patients showed the highest numbers of abnormalities in hemostatic testing, but medical patients had more-severe defects. The occurrence of isolated abnormal laboratory values did not predict bleeding, but a score derived from a consideration of multiple defects did. Correction of the abnormalities was attempted in 37 percent of patients with hemostatic defects. Sixteen patients had bleeding complications, but only two had complications that were life-threatening. None of the complications were fatal. CONCLUSION: Invasive lines are used frequently in patients with hemostatic defects, often without any attempt to correct the abnormalities. Nevertheless, rates of hemorrhage are low and appear to be closely related to the level of experience of the physician rather than to defects in hemostasis. These findings suggest that the use of blood components for preprocedure correction of hemostatic defects is not necessary, except in those patients who have the most severe hemostatic abnormalities.     

Differentiation of cellular processes involved in the induction and maintenance of stimulated neutrophil adherence

Neutrophil adherence stimulated by phorbol myristate acetate (PMA) was investigated by quantitating the attachment of 51Cr-labeled neutrophils to plastic surfaces and to the endothelium of umbilical veins mounted in compartmentalized Lucite chambers. PMA-induced adherence could be functionally separated into an induction phase requiring cellular metabolism and a Mg++ dependent maintenance phase that was independent of cellular metabolism. Thus, metabolic inhibitors (N-ethylmaleimide, 2- deoxyglucose) blocked adherence when added to neutrophils prior to PMA, but did not cause detachment of cells adhering as a consequence of prior exposure to PMA. PMA failed to induce adherence of neutrophils incubated at low (0.4 degree C) temperature, but temperature reduction, even for prolonged periods, did not cause detachment of adherent cells. Thus, the attractive forces that mediate stimulated adherence persist independently of any sustained metabolic response to the inducing stimulus. However, removal of Mg++ from the media above adherent cells resulted in immediate detachment, indicating that the cation was required for the persistent expression or maintenance of the attractive forces involved. The extent of stimulated adherence correlated well with the extent of degranulation when rates were varied by limiting the incubation time or stimulus concentration. This correlation was not absolute; in the absence of Mg++, PMA induced degranulation normally but failed to enhance adherence. To explain these findings, we investigated the possibility that PMA-stimulated adherence was maintained by Mg++-dependent cellular adherence molecules released during exocytosis. Supernatants of stimulated neutrophils were devoid of adherence-promoting activity, and only weak activity was recovered in supernatants of mechanically disrupted neutrophils. PMA effectively stimulated the tight adherence of degranulated neutrophil cytoplasts to plastic surfaces and did so in the absence of stimulated granule enzyme release. Thus, conditions have been identified under which degranulation occurs in the absence of adherence (removal of Mg++) and adherence occurs without concurrent degranulation. Since neutrophil cytoplasts do contain some granule products and granule material can be identified on cytoplast membranes, it is possible that degranulation or granule products may be involved in the adherent response. However, hyperadherence was shown to develop in the absence of de novo degranulation.(ABSTRACT TRUNCATED AT 400 WORDS)     

Mechanisms and implications of phosphoinositide 3-kinase delta in promoting neutrophil trafficking into inflamed tissue

The phosphoinositide 3-kinase (PI3K) catalytic subunit p110 delta is expressed in neutrophils and is thought to play a role in their accumulation at sites of inflammation by contributing to chemoattractant-directed migration. We report here that p110 delta is present in endothelial cells and participates in neutrophil trafficking by modulating the proadhesive state of these cells in response to tumor necrosis factor alpha (TNF alpha). Specifically, administration of the selective inhibitor of PI3K delta, IC87114, to animals reduced neutrophil tethering to and increased rolling velocities on cytokine-activated microvessels in a manner similar to that observed in mice deficient in p110 delta. These results were confirmed in vitro as inhibition of this isoform in endothelium, but not neutrophils, diminished cell attachment in flow. A role for PI3K delta in TNF alpha-induced signaling is demonstrated by a reduction in Akt-phosphorylation and phosphatidylinositol-dependent kinase 1 (PDK1) enzyme activity upon treatment of this cell type with IC87114. p110 delta expressed in neutrophils also contributes to trafficking as demonstrated by the impaired movement of these cells across inflamed venules in animals in which this catalytic subunit was blocked or genetically deleted, results corroborated in transwell migration assays. Thus, PI3K delta may be a reasonable therapeutic target in specific inflammatory conditions as blockade of its activity reduces neutrophil influx into tissues by diminishing their attachment to and migration across vascular endothelium.     

Circulating Activated Platelets Reconstitute Lymphocyte Homing and Immunity in L-selectin–Deficient Mice

Peripheral lymph nodes (PLN) are critical for immunologic memory formation in response to antigens that penetrate the skin. Blood-borne lymphocytes first encounter such antigens after they home to PLN through a multi-step adhesion process that is normally initiated by L-selectin (CD62L) in high endothelial venules (HEV). Since naive T cells can not enter PLN normally in L-selectin–deficient mice, a delayed type hypersensitivity response to cutaneously applied antigen cannot be mounted. In this study, we report that the administration of activated platelets into the systemic circulation of L-selectin knockout mice restores lymphocyte trafficking to PLN, and reconstitutes T cell–mediated immunity in response to a cutaneous antigen. These effects required platelet-expressed P-selectin that allows activated platelets to transiently form a bridge between lymphocytes and HEV, thereby enabling lymphocytes to undergo subsequent β2 integrin-dependent firm adhesion. These profound effects of platelet-mediated cell–cell interactions on lymphocyte trafficking and formation of immunologic memory may impact on a variety of autoimmune and inflammatory conditions.     

Live births after management of severe OHSS by GnRH antagonist administration in the luteal phase

Ovarian hyperstimulation syndrome (OHSS) is a serious complication of ovarian stimulation protocols. Currently, no curative therapy exists and the main preventive option is cycle cancellation. Gonadotrophin-releasing hormone (GnRH) antagonist administration in the luteal phase was recently proposed as a new approach for the management of patients with established severe OHSS. Three polycystic ovarian syndrome patients undergoing IVF treatment developed severe OHSS, diagnosed 6 days after oocyte retrieval. On day 6, the patients underwent blastocyst transfer and received GnRH antagonist for 4 days, combined with luteal phase support using exogenous oestradiol and progesterone. Two patients had successful pregnancies that resulted in births of healthy infants, while one patient had a biochemical pregnancy. In all patients, established severe OHSS regressed to a moderate form of the syndrome, no pregnancy-induced life-threatening OHSS was observed, while a short monitoring period was required at an outpatient level, avoiding the need for patient hospitalization. This is the first report in the literature on GnRH antagonist administration in the luteal phase, combined with embryo transfer and exogenous oestradiol and progesterone supplementation. This novel treatment was effective in the regression of established severe OHSS, and resulted in the birth of healthy infants.     

蝙蝠葛碱和粉防己碱对[~3H]WEB 2086与体外牛脑前动脉平滑肌细胞结合的影响(英文)

用标记的血小板活化因子拮抗剂[~3H]WEB 2086,在培养的牛脑前动脉平滑肌细胞上鉴定了血小板活化因子受体。结果表明在25℃时该细胞上存在两种与配基具有不同亲和力的受体结合位点,其中K_(d-1)=22.8±5.0 nmol·L~(-1),K_(d-2)=186+20.5 nmol·L~(-1);B_(max-1)=2.1±0.3 pmol/10~4细胞,B_(max-2)=12.1±1-5 pmol/10~6细胞。蝙蝠葛碱和粉防己碱均能抑制[~3H]WEB2086与上述细胞的结合。