Experimental and analytical performance investigation of air to air two phase closed thermosyphon based heat exchangers

In recent years, the use of wickless heat pipes (thermosyphons) in heat exchangers has been on the rise, particularly in gas to gas heat recovery applications due to their reliability and the level of contingency they offer compared to conventional heat exchangers. Recent technological advances in the manufacturing processes and production of gravity assisted heat pipes (thermosyphons) have resulted in significant improvements in both quality and cost of industrial heat pipe heat exchangers. This in turn has broadened the potential for their usage in industrial waste heat recovery applications. In this paper, a tool to predict the performance of an air to air thermosyphon based heat exchanger using the ε-NTU method is explored. This tool allows the predetermination of variables such as the overall heat transfer coefficient, effectiveness, pressure drop and heat exchanger duty according to the flow characteristics and the thermosyphons configuration within the heat exchanger. The new tool's predictions were validated experimentally and a good correlation between the theoretical predictions and the experimental data, was observed. © 2014 Elsevier Ltd. All rights reserved

Renal oncocytoma: experience of Clinical Urology A, Urology Department, CHU Ibn Sina, Rabat, Morocco and literature review

Renal oncocytoma is a rare and benign renal tumor. Only few cases have been reported in Moroccan populations. In the present study, we reportour experiences in the diagnosis, management and follow-up of this disease. We report on six cases of renal oncocytoma indentified between 1990 and 2008 in the urology department of “CHU Ibn Sina” in Rabat. These six cases are listed among 130 kidney tumors reported during the study period. We assess the clinical, radiological and therapeutic features of the patients and we review literature. Six cases of renal oncocytoma,representing 4.6% of all primitive kidney tumors treated in our institution during the study period. The mean age was 53 ±9.7 years (range 34 to61 years). One patient was asymptomatic at presentation, five patients (83%) had flank pain and two (33%) had macroscopic hematuria. Thetumor was right sided in 4 cases (66%) and left sided in 2 cases (33%). All patients underwent CT scan which showed, in three cases, a centrallylocated stellate area of low attenuation. The clinical suspicion of  oncocytoma was made preoperatively in only 3 patients by imaging studies, but the suspicion of renal cell carcinoma persist and all patients were treated with radical nephrectomy. Definitive diagnosis was made in all cases postoperatively. All the tumors were well circumscribed but unencapsulated. The mean tumor size was 8,75±2,04 cm. Four patients were classified at stage pT2 and two at stage p T1. Most of the pathological features in our patients were typical of this entity.  Predominant cell type was a typical oncocytoma with general low mitotic activity. No extension to peri-nephric fat tissue or lymphovascular invasion was observed. After a mean follow-up of 36 months (range 26-62 months), there was neither recurrence nor death from oncocytoma. Accordingly, the disease-specific survival was 100%. Renal oncocytoma has a benign clinical course with excellent long-term outcomes. In our series, it happened mostly in females and is more frequently symptomatic. Although radical nephrectomy is the usual treatment, a conservative approach should be considered whenever there are signs of clinical and radiological presumptions.Key words: Renal oncocytoma, tumor, diagnosis, treatmen

Séminome Spermatocytaire: à Propos d’un Cas et Revue de La Littérature Spermatocytic Seminoma

Le séminome spermatocytaire est une tumeur rare, représentant moins de 2% des cancers du testicule, survenant essentiellement chez le sujet âgé. Nous rapportons une nouvelle observation d’un patient âgé de 48 ans. La tumeur se présentait comme une prolifération de cellules en nappescompactes, avec 3 types cellulaires, des cellules de petite taille, des cellules intermédiaires et des grandes cellules. Il n’a été retrouvé ni contingent sarcomateux, ni séminome classique. L’analyse en immun histochimie n’a retrouvé aucune expression des cellules tumorales pour les anticorpsclassiques testés, notamment l’Ac anti PLAP et les marqueurs lymphoïdes. Le séminome spermatocytaire doit être reconnu, car son évolution est très favorable et ne nécessite qu’une simple orchidectomie, en l’absence d’un exceptionnel contingent sarcomateux ou de métastase où une chimiothérapie s’impose

Migration Intravésicale du Dispositif Intra-Utérin à Propos de Cinq Cas

La migration intravésicale du dispositif intra-utérin (DIU) par perforation utérine est une complication rare. Dans cette étude rétrospective monocentrique, nous présentons notre expérience de 5 cas colligés au sein de notre établissement entre 2004 et 2009. L’âge moyen de nos patientes est de 39 ans (32-48 ans). La symptomatologie clinique révélatrice était dominée par le syndrome irritatif vésical. Le diagnostic a été évoqué sur le couple écho/AUSP, puis confirmé par la cystoscopie. Le traitement a consisté en une lithotritie balistique du calcul avec extraction du stérilet par voie endoscopique chez 4 patientes et extraction chirurgicale chez une seule.Mots clés : Calcul vésical, dispositif intra-utérin, lithotritie balistique, migration

Alpha Bloquants en Urologie

En urologie, les alpha-bloquants occupent une place prépondérante dans le traitement de nombreuses pathologies. Ils sont des dérivés de la quinazoline comme l’afluzosine, la térazosine et la doxazosine et des sulfones comme la tamsulosine, la silodosine et la prazosine. Ces molécules sont largement utilisées dans la pathologie prostatique et ont un effet relaxant sur les cellules musculaires lisses au niveau du col vésical avec comme conséquence une amélioration considérable des troubles urinaires du bas appareil et de la fonction sexuelle. Ils partagent un avantage majeur, qui est leur rapidité d’action symptomatique avec amélioration de la qualité de vie. Ils ne modifient pas le volume de la prostate et leur association avec d’autres classes thérapeutiques est prometteuse et a montré son efficacité. Ils sont également utilisés dans le traitement de la maladie du col vésical, la dyssynergie vésico-sphinctérienne, la vessie neurologique, le syndrome douloureux pelvien chronique et peuvent favoriser l’expulsion des calculs de l’uretère en particulier pelvien. Cependant les alpha-bloquants ne sont pas dénudés d’effets indésirables et leurs contre indications sont bien précisées

A novel role of CD4 Th17 cells in mediating cardiac allograft rejection and vasculopathy

T-bet plays a crucial role in Th1 development. We investigated the role of T-bet in the development of allograft rejection in an established MHC class II–mismatched (bm12 into B6) model of chronic allograft vasculopathy (CAV). Intriguingly, and in contrast to IFN-γ−/− mice that are protected from CAV, T-bet−/− recipients develop markedly accelerated allograft rejection accompanied by early severe vascular inflammation and vasculopathy, and infiltration by predominantly IL-17–producing CD4 T cells. Concurrently, T-bet−/− mice exhibit a T helper type 1 (Th1)–deficient environment characterized by profound IFN-γ deficiency, a Th2 switch characterized by increased production of interleukin (IL) 4, IL-5, IL-10, and IL-13 cytokines, as well as increased production of the proinflammatory cytokines IL-6, IL-12p40, and IL-17. Neutralization of IL-17 inhibits accelerated allograft rejection and vasculopathy in T-bet−/− mice. Interestingly, CD4 but not CD8 T cell deficiency in T-bet−/− mice affords dramatic protection from vasculopathy and facilitates long-term graft acceptance. This is the first study establishing that in the absence of Th1-mediated alloimmune responses, CD4 Th17 cells mediate an aggressive proinflammatory response culminating in severe accelerated allograft rejection and vasculopathy. These results have important implications for the development of novel therapies to target this intractable problem in clinical solid organ transplantation

Blockade of the Programmed Death-1 (PD1) Pathway Undermines Potent Genetic Protection from Type 1 Diabetes

Aims/Hypothesis Inhibition of PD1-PDL1 signaling in NOD mice accelerates onset of type 1 diabetes implicating this pathway in suppressing the emergence of pancreatic beta cell reactive T-cells. However, the molecular mechanism by which PD1 signaling protects from type 1 diabetes is not clear. We hypothesized that differential susceptibility of Idd mouse strains to type 1 diabetes when challenged with anti PDL1 will identify genomic loci that collaborate with PD1 signaling in suppressing type 1 diabetes. Methods: Anti PDL1 was administered to NOD and various Idd mouse strains at 10 weeks of age and onset of disease was monitored by measuring blood glucose levels. Additionally, histological evaluation of the pancreas was performed to determine degree of insulitis. Statistical analysis of the data was performed using Log-Rank and Student's t-test. Results: Blockade of PDL1 rapidly precipitated type 1 diabetes in nearly all NOD Idd congenic strains tested, despite the fact that all are moderately (Idd5, Idd3 and Idd10/18) or highly (Idd3/10/18 and Idd9) protected from spontaneous type 1 diabetes by virtue of their protective Idd genes. Only the Idd3/5 strain, which is nearly 100% protected from spontaneous disease, remained normoglycemic following PDL1 blockade. Conclusions: These results indicate that multiple Idd loci collaborate with PD1 signaling. Anti PDL1 treatment undermines a large portion of the genetic protection mediated by Idd genes in the NOD model of type 1 diabetes. Basal insulitis correlated with higher susceptibility to type 1 diabetes. These findings have important implications since the PD1 pathway is a target for immunotherapy

A Novel Clinically Relevant Strategy to Abrogate Autoimmunity and Regulate Alloimmunity in NOD Mice

OBJECTIVE - To investigate a new clinically relevant immunoregulatory strategy based on treatment with murine Thymoglobulin mATG Genzyme and CTLA4-Ig in NOD mice to prevent alloand autoimmune activation using a stringent model of islet transplantation and diabetes reversal. RESEARCH DESIGN AND METHODS - Using allogeneic islet transplantation models as well as NOD mice with recent onset type 1 diabetes, we addressed the therapeutic efficacy and immunomodulatory mechanisms associated with a new immunoregulatory protocol based on prolonged low-dose mATG plus CTLA4-Ig. RESULTS - BALB/c islets transplanted into hyperglycemic NOD mice under prolonged mATG+CTLA4-Ig treatment showed a pronounced delay in allograft rejection compared with untreated mice (mean survival time: 54 vs. 8 days, P < 0.0001). Immunologic analysis of mice receiving transplants revealed a complete abrogation of autoimmune responses and severe downregulation of alloimmunity in response to treatment. The striking effect on autoimmunity was confirmed by 100% diabetes reversal in newly hyperglycemic NOD mice and 100% indefinite survival of syngeneic islet transplantation (NOD.SCID into NOD mice). CONCLUSIONS - The capacity to regulate alloimmunity and to abrogate the autoimmune response in NOD mice in different settings confirmed that prolonged mATG+CTLA4-Ig treatment is a clinically relevant strategy to translate to humans with type 1 diabetes