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51.
Marlon Normandin Joel Gagn Julie Bernard Robert lie Dom Miceli Michel Baudry Guy Massicotte 《Brain research》1996,730(1-2):40-46
Low-frequency stimulation is associated with long-term depression (LTD) of synaptic efficacy in various brain structures. Like long-term potentiation (LTP), homosynaptic LTD in area CA1 of the hippocampus appears to require NMDA receptor activation, changes in postsynaptic calcium concentration and phospholipase A2 (PLA2) activation. Arachidonic acid (AA) is released after the activation of calcium-dependent phospholipases and free AA is rapidly metabolized to a family of bioactive products (the eicosanoids) which are thought to be both intracellular and extracellular messengers. In the present study, we investigated the involvement of the cyclooxygenase and lipoxygenase pathways of AA metabolism in the formation of homosynaptic LTD in the rat hippocampus. Stimulation at 1 Hz for 15 min was used to produce homosynaptic depression in area CA1 of hippocampal slices. LTD induction was partially blocked by bromophenacyl bromide (50–100 μM), a selective PLA2 inhibitor, and by the a nonselective lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA; 100 μM). In contrast, the specific cyclooxygenase blocker indomethacin (100 μM) did not significantly reduce hippocampal LTD. Since NDGA interferes with LTD formation, we examined whether specific inhibitors of 5- and 12-lipoxygenases were capable of blocking LTD expression. The 12-lipoxygenase inhibitor baicalein at a concentration of 50 μM reduced LTP formation when given in the bath, an effect that was less pronounced with the 5-lipoxygenase inhibitor AA-861. These data suggest that the activation of endogenous PLA2 and the formation of 12-lipoxygenase metabolites of AA may be important factors controlling the expression of hippocampal LTD. 相似文献
52.
We have investigated the distribution of vasopressin binding sites in the brain of male and female adult mice using a radio-iodinated ligand and film autoradiography. Vasopressin receptors were uncovered in various regions of the brain including the basal nucleus of Meynert, the substantia innominata, the hypothalamic paraventricular nucleus, the substantia nigra pars compacta and the hypoglossal nucleus. A sex-related difference in the expression of vasopressin receptors was seen in the medial preoptic area/anterior hypothalamus corresponding to the rat sexually dimorphic nucleus in the rat and in the hypothalamic mammillary nuclei. In both structures the autoradiographic labeling is more intense in females than in males. These observations confirm that vasopressin binding sites are present in the hypothalamic preoptic area of most species examined so far and that sex-related expression of neuropeptide receptors could trigger sex-related behavioral differences. 相似文献
53.
So far, laparoscopic approaches to kidney and adrenal have been limited because of their retroperitoneal location. We here report eight renal and adrenal endoscopic procedures performed in seven patients: two adrenalectomies for hyperaldosteronism, one adrenalectomy for isolated metastasis from an adenocarcinoma of the lung; two nephrectomies for end-stage infected hydronephrosis, two partial nephrectomies for small circumscribed lesions of the kidney, and one endoscopic resection for pain relief of a voluminous cyst at the kidney. The approach was transperitoneal in two cases and retroperitoneal in five cases using the retropneumoperitoneum insufflation technique. One patient was operated by a combined approach using the retro- and transperitoneal routes. All procedures were successfully completed endoscopically. The retroperitoneoscopic approach of the kidney is safe and does not interfere with the peritoneal organs. Its working space is tenuous, but allows a direct access on the kidney with good exposure of its pedicle. For adrenal surgery, the retroperitoneoscopic dissection is more difficult, because movements of instruments are often impaired by the closeness of the costal margin and the iliac crest. However, in case of difficulties we found it very convenient to switch from a retroperitoneal endoscopic approach to a combined coelioscopic and retroperitoneoscopic operation. Far from excluding each other, both approaches are complementary, particularly for difficult situations (i.e., previous peritoneal or retroperitoneal surgery). 相似文献
54.
The binding of [3H]4-diphenylacetoxy-N-methylpiperidine methiodide to longitudinal ileal smooth muscle muscarinic receptors 总被引:3,自引:0,他引:3
Muscarinic receptors present in longitudinal ileum were characterized using the non-selective radioligand [3H]N-methylscopolamine [( 3H]NMS) and the M3 selective radioligand [3H]4-diphenylacetoxy-N-methylpiperidine methiodide [( 3H]4DAMP). In saturation studies, [3H]4DAMP, but not [3H]NMS, identified two populations of binding sites with 17% of the sites (155 fmol/mg protein) displaying high affinity (Kd = 0.39 nM) for [3H]4DAMP and the remaining sites displaying low affinity for the radioligand (Kd = 4.43 nM). In competition studies gallamine and methoctramine, but not AF-DX 116, identified two populations of [3H]NMS binding sites. Affinity estimates for gallamine and methoctramine indicated that 80% of the [3H]NMS binding sites were of the M2 subtype. The minor population of [3H]NMS binding sites could not be readily characterized, due partly to the low selectivity of the competing ligands and also to the relatively low density of the sites. In studies using the M3 muscarinic receptor selective radioligand [3H]4DAMP, the minor population of sites could be preferentially labeled by using a low concentration (0.4 nM) of [3H]4DAMP. Under these conditions, [3H]4DAMP labeled approximately equal levels of the two muscarinic receptor binding sites present in the ileum. Competition studies with AF-DX 116, gallamine and methoctramine indicated that the two [3H]4DAMP binding sites displayed the pharmacology expected of the M2 and M3 receptors, respectively. These results provide additional evidence that longitudinal ileal smooth muscle membranes contain both M2 and M3 muscarinic receptors and indicate that [3H]4DAMP is a useful ligand for identifying heterogeneity of muscarinic receptor subtypes. 相似文献
55.
The action of iturin A on non-growing cells of Saccharomyces cerevisiae was tested. This antibiotic gave important modifications in the membrane permeability which permitted nucleotides, proteins, polysaccharides and lipids to escape from cells. The lipid content of cells was strongly disturbed; the level of phospholipids, essentially phosphatidylcholine, decreased while the level of fatty acids increased. A part of these fatty acids were extruded from yeast cells. The role of iturin A in these modifications was discussed. 相似文献
56.
57.
The incidence of group A Streptococcus (GAS) invasive infections has been increasing worldwide, and there is no obvious explanation for this phenomenon. In 1993, a working group on severe GAS infections was established to define accurately what constitutes an invasive infection. Three types of infection are particularly feared: necrotizing fasciitis, myositis and a newly defined entity, named streptococcal toxic shock syndrome (STSS) because of a certain analogy with its staphylococcal counterpart. GAS produces many toxins responsible for its clinical manifestations. Some of them, labelled streptococcal pyrogenic exotoxins, have been characterized as superantigens. These proteins play a key role in initiating the immune response to GAS and are mostly responsible for the precipitous course of invasive infections. Death rates are high in streptococcal invasive infections, ranging from about 20% for necrotizing fasciitis to almost 100% for myositis. Therapy consists mainly of high doses of antibiotic combinations, aggressive surgery, and intravenous administration of immunoglobulins for STSS. 相似文献
58.
59.
L A Michel J Jamart H A Bradpiece R A Malt 《The Journal of thoracic and cardiovascular surgery》1990,100(4):595-605
To determine the preoperative variables affecting the mortality rate and the development of severe complications in patients who have had myocardial revascularization or a valve replacement and who then undergo a noncardiac operation, we retrospectively studied data from 120 such patients over the 5 years from 1982 through 1986. Thirty-six percent of patients had a noncardiac operation during the first month after the cardiac operation. The mortality rate was 11%, and the morbidity rate was 56%. The statistical comparison of the predictive accuracy of postoperative complications of three simple, widely used classifications (American Society of Anesthesiologists physical status, New York Heart Association classification, Massachusetts General Hospital cardiac risk index) demonstrated the superiority of the simplified three-class cardiac risk index (Massachusetts General Hospital-cardiac risk index; predictive accuracy of 84%). In a multivariate discriminant analysis of 21 variables in this population, five variables (myocardial infarction in previous 6 months, S3 gallop or jugular vein distention, arrhythmia on last preoperative electrocardiogram, emergency operation, delay between cardiac and noncardiac operation) were identified as being the most predictive of a postoperative complication. When these variables were used in the function (DF3) obtained by linear discriminant analysis, the prediction accuracy of a postoperative complication reached 83%. Performance of the new models in a prospective validation population remained satisfactory (75% for Massachusetts General Hospital-cardiac risk index three-class index and 72% for DF3). Extensive statistical analysis of our data tested by a validation study provided simple predictive models based on clinical variables easily available even in emergency situations. 相似文献
60.
Fluorine-18-fluorodeoxyglucose positron emission tomography for preoperative parathyroid imaging in primary hyperparathyroidism 总被引:5,自引:3,他引:2
Pierre Melon Andre Luxen Etienne Hamoir Michel Meurisse 《European journal of nuclear medicine and molecular imaging》1995,22(6):556-558
Fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging was performed in seven consecutive patients with primary hyperparathyroidism to preoperatively locate parathyroid adenomas. Foci of FDG accumulation corresponding to abnormal parathyroid tissue were observed in two out of nine surgically excised parathyroid adenomas. It was concluded that FDG PET imaging demonstrated a too low sensitivity for systematic preoperative detection and localization of parathyroid glands causing primary hyperparathyroidism. 相似文献