The conversion of angiotensin I (AT-I) to angiotensin II (AT-II) by angiotensin I-converting enzyme (ACE) is a key step in the action of angiotensins. ACE is constitutively expressed in endothelial ...cells, but can also be detected at low levels in smooth muscle cells (SMC). Furthermore, in rats the ACE activity can be induced in SMC in vivo by experimental hypertension or vascular injury and in vivo by corticoid treatment. This study was therefore undertaken to evaluate the conversion of AT-I and its subsequent effects in SMC in basal conditions and after stimulation by dexamethasone. Using rat and human SMC, showed that dexamethasone induced ACE expression and that this enzyme was functional, leading to AT-II-dependent intracellular signaling. A fourfold increase in phospholipase C activity in response to AT-I was observed in dexamethasone-activated SMC compared with quiescent SMC. This effect of dexamethasone on signal transduction is dependent on ACE activity, whereas AT-II receptor parameters remain unchanged. The action of AT-I was blocked by an AT1 receptor antagonist, suggesting that it was mediated by AT-II. Similarly, dexamethasone-induced ACE expression was present in human SMC, and calcium signaling was mobilized in response to AT-I in activated human cells. Experiments performed with cocultures of endothelial cells and SMC in a Transwell system showed that the response to AT-I was limited to the compartment where AT-I was localized, suggesting that AT-I does not pass through the endothelial cell barrier to interact with underlying SMC. Our data suggest that in rat, as in human SMC, the conversion of AT-I into AT-II and the signal transduction in response to AT-I are ACE expression-dependent. In addition, the present findings show that this SMC response to AT-I is endothelium-independent, supporting the idea of a local generation of AT-II in the vascular wall.
Release and circulation of tumor DNA could be favored by surgery. No data is available for the effect of laparoscopy on this phenomenon.
The aim of this study was to assess the impact of CO2 ...laparoscopy on circulating tumor DNA. Two xenografts of ovarian cancer were obtained by intraperitoneal inoculation (IP) of IGR-OV1 or NIH:OVCAR-3 cells in nude rats. CO2 laparoscopy (L), gasless laparoscopy (GL), midline laparotomy (ML) or general anesthesia as a control (C) were randomly carried out when the tumor graft was present in the peritoneal cavity. A sterile blood sample was taken in each case as soon as the experiment was completed. DNA was subsequently extracted and amplified (PCR, primers HLA GH 26 and HLA GH 27 specific for human DNA). In each model, we compared the influence of each surgical approach on circulating tumor DNA. Statistics were performed with the Wilcoxon test and Fisher exact test. 1:
Eighteen rats were included in each group. Our protocol could detect an amount of tumor DNA equivalent to 10 cells/ml of blood. This technique was specific. Circulating tumor DNA was frequently observed in the IGR-OV1 model (45 to 50%), without significant difference between groups (p=0.6). In the NIH: OVCAR-3 model, the detection rate ranged from 22% (control group) to 64% (gasless group); but the overall comparison between the four groups was not significant (p = 0.2).
In this experimental trial, CO2 laparoscopy had no deleterious effect on circulating tumor DNA. Biologic characteristics of tumors could also play a role.
Abstract Sporadic colorectal tumorigenesis is caused by alterations in the Wnt ( APC , CTNNB1 ) and Ras pathways. Our objective was to analyze the occurrence of these genetic alterations in relation ...to tumor and patient characteristics. The prevalence of somatic alteration in the hot-spot regions of the APC , BRAF , and CTNNB1 genes was investigated in 48 unselected and unrelated Tunisian patients with sporadic colorectal cancer, and the association between the molecular features at these genes in relation to tumor and patient characteristics (age at diagnosis, sex, tumor localization, stage, and differentiation) was analyzed. Loss of heterozygosity was observed at the APC locus in 52% of the analyzed tumors. 6 novel mutations were detected by polymerase chain reaction sequencing in the mutation cluster region of the APC gene. No mutations were observed in the CTNNB1 gene in any tumor, but 8% of tumors harbored mutation in the BRAF gene. Clinicopathological analyses showed an association between APC point mutations and the earliest occurrence of sporadic colorectal cancer. The findings confirm the heterogeneity of APC gene alteration and also reveal a particular profile of this pathology among Tunisian patients that confirms the epidemiological data for this country.
Activités et collectifs Charue-Duboc, Florence; Chédotel, Frédérique; Coulet, Jean-Claude ...
Presses universitaires de Provence eBooks,
2017
Book
Odprti dostop
L'apprentissage des collectifs au sein des écosystèmes d'innovation est devenu un enjeu majeur questionnant tant praticiens que chercheurs. Quels sont les nouvelles dynamiques de l’apprentissage, les ...nouvelles figures des collectifs ? Comment se saisir de ces nouveaux phénomènes ? L’ouvrage propose des réponses inédites en s’appuyant sur une double exigence. Tout d’abord, en convoquant plusieurs disciplines (les sciences de gestion, la philosophie, la psychologie du développement, la psychologie cognitive et les sciences de l'éducation), il est possible de mieux appréhender l’émergence d’une nouvelle économie, de modes de gestion et de collaboration renouvelés dans le travail. Ensuite, en prenant au sérieux le développement d’une économie cognitive, les analyses présentes dans l’ouvrage ne réduisent pas leur recherche à une partition entre dimension sociale et dimension cognitive des apprentissages. L’ouvrage permet alors de mieux saisir le renouvellement des activités et des collectifs, rend compte de cas concrets et propose des modalités d’intervention pour accompagner ces nouvelles dynamiques. Cet ouvrage a bénéficié de l'appui scientifique de l'Association Francophone pour la Gestion des Connaissances dans la Société et les Organisations. L’ouvrage s’adresse aux étudiants de master et de doctorat ainsi qu’aux chercheurs dans les domaines suivants : économie et gestion, psychologie du développement et psychologie cognitive, ergologie, ergonomie et sociologie du travail.
Contient: La pédagogie universitaire : un courant en plein développement / Jean-Marie De Ketele; L'approche par compétences : un nouveau paradigme pour la pédagogie universitaire? / Christian ...Chauvigné et Jean-Claude Coulet; L'expérience pédagogique des moniteurs comme analyseur de l'université / Saeed Paivandi; Etudes de trois facteurs clés pour comprendre la persévérance à l'université / Julia Schmitz... etc.; Accompagner le développement pédagogique des enseignants universitaires à l'aide d'un cadre conceptuel original / Marianne Frenay... et al.; L'inéluctable ajustement des universités africaines au processus de Bologne.
