TAPP or TEP? Population-Based Analysis of Prospective Data on 4,552 Patients Undergoing Endoscopic Inguinal Hernia Repair

Background: Whether total extraperitoneal inguinal hernia repair (TEP) is associated with worse outcomes than transabdominal preperitoneal inguinal hernia repair (TAPP) continues to be a matter of debate. The objective of this large cohort study is to compare outcomes between patients undergoing TEP or TAPP. Methods: Based on prospective data of the Swiss association of laparoscopic and thoracoscopic surgery, all patients undergoing unilateral TEP or TAPP between 1995 and 2006 were included. The following outcomes were compared: conversion rates, intraoperative and postoperative complications, duration of operation. Results: Data on 4,552 patients undergoing TEP (n=3,457) and TAPP (n=1,095) were collected prospectively. Average age and American Society of Anesthesiologists score were similar in the two groups. Patients undergoing TEP had a significantly higher rate of intraoperative complications (TEP 1.9% vs. TAPP 0.9%, p=0.029) and surgical postoperative complications (TEP: 2.3% vs. TAPP: 0.8%, p=0.003). The postoperative length of stay was longer for patients undergoing TAPP (2.9 vs. 2.3days, p=0.002), whereas the duration of the operation was longer for TEP (66.6 vs. 59.0min, p<0.001) and the conversion rate was higher (TEP 1.0% vs. TAPP 0.2%, p=0.011). Conclusions: This study is one of the first population-based analyses comparing TEP and TAPP in a prospective cohort of more than 4,500 patients. Intraoperative and surgical postoperative complications were significantly higher in patients undergoing TEP. TEP is also associated with longer operating times and higher conversion rates. Therefore, on a population-based level, the TAPP technique appears to be superior to the TEP repair in patients undergoing unilateral inguinal hernia repai

Transabdominal pre-peritoneal mesh in inguinal hernia repair in elderly: end point of our experience

BACKGROUND: Aim of this study is to present our standardized laparoscopic transabdominal preperitoneal hernia repair (TAPP) technique, and to study our experience in the elderly as far as concerns preoperative and postoperative variables. METHODS: We described our standardized TAPP technique according with Stuttgart technique [1], and we evalutated our team's experience in TAPP inguinal hernia repair in elderly (> 65 yrs) and in young patients (< 65 yrs). RESULTS: We retrospectively reviewed our Surgery Division's experience about TAPP; we included in our study 185 patients. The sample was subdivided in two groups: TAPP Group (< 65 years patients) and TAPPe Group (> 65 years patients). TAPP Group was composed by 154 patients and TAPPe Group of 31 patients. According with literature, in this subgroup recurrence rate (3,2%), early and delayed complications and mean operative time (86 min). There were no major vascular or intestinal complications. At the moment follow-up is 31 months. There were no incisional hernias on umbilical trocar. Mean satisfaction rate was excellent also in elderly patients. CONCLUSIONS: According with literature, in our experience TAPP technique is a safe and feasible procedure, even in elderly patients

B cell-intrinsic function of TAPP adaptors in controlling germinal center responses and autoantibody production in mice

Control of B-cell signal transduction is critical to prevent production of pathological autoantibodies. Tandem PH domain containing proteins (TAPPs) specifically bind PI(3,4)P2, a phosphoinositide product generated by PI 3-kinases and the phosphatase SHIP. TAPP KI mice bearing PH domain-inactivating mutations in both TAPP1 and TAPP2 genes, uncoupling them from PI(3,4)P2, exhibit increased BCR-induced activation of the kinase Akt and develop lupus-like characteristics including anti-DNA antibodies and deposition of immune complexes in kidneys. Here we find that TAPP KI mice develop chronic germinal centers (GCs) with age and show abnormal expression of B cell activation and memory markers. Upon immunization with T-dependent Ag, TAPP KI mice develop functional but abnormally large GCs, associated with increased GC B cell survival. Disruption of chronic GCs in TAPP KI mice by deletion of the costimulatory molecule ICOS abrogate anti-DNA and anti-nuclear antibody production in TAPP KI mice, indicating an essential role for GCs. Moreover, TAPP KI B cells are sufficient to drive chronic GC responses and recapitulate the autoimmune phenotype in bone marrow chimeric mice. Our findings demonstrate a B cell-intrinsic role of TAPP-PI(3,4)P2 interaction in regulating GC responses and autoantibody production and suggest that uncontrolled Akt activity in B cells can drive autoimmunity. This article is protected by copyright. All rights reserved.</p

A combinatorial approximation algorithm for CDMA downlink rate allocation

This paper presents a combinatorial algorithm for downlink rate allocation in Code Division Multiple Access (CDMA) mobile networks. By discretizing the coverage area into small segments, the transmit power requirements are characterized via a matrix representation that separates user and system characteristics. We obtain a closed-form analytical expression for the so-called Perron-Frobenius eigenvalue of that matrix, which provides a quick assessment of the feasibility of the power assignment for a given downlink rate allocation. Based on the Perron-Frobenius eigenvalue, we reduce the downlink rate allocation problem to a set of multiple-choice knapsack problems. The solution of these problems provides an approximation of the optimal downlink rate allocation and cell borders for which the system throughput, expressed in terms of utility functions of the users, is maximized

Optimization of Heat Exchanger Design Parameters for Hydrocarbon Refrigerant Systems

Hydrocarbon refrigerants (HC's) are one alternative to hydrofluorocarbons (HFC???s) since they have zero ozone depletion potential and negligible global warming potential. However, due to their flammable nature, the amount of refrigerant used in systems is regulated for safety reasons. This report presents simulation results for a 3-ton R290 (propane) air-conditioning system, and identifies the optimum heat-exchanger geometries that would minimize system charge while trying to retain the same system efficiency. An existing R410A microchannel system simulation served as the base case, and then the geometries were optimized for the R290 system, and the results were compared to the base case. The model was then analyzed for the off-design conditions, and the conclusions presented. The optimal condenser geometry tended to have smaller port diameter and core depth with thicker webs between the ports. Also, the fins tended to be taller, thinner and more densely packed. Similar results were noted for the evaporator geometry. The optimal design reduced the combined heat exchanger charge by more than a factor of 5. The system efficiency was reduced by 3% in the process, but the loss could be recovered because the pressure drop was low enough to permit increasing the air-flow rates. The off-design behavior of the R290 microchannel system is very different from a traditional R410A round-tube plate-fin system. Typically with the increase in ambient temperature, charge from the evaporator and the liquid line moves to the condenser. In the R290 system, because of the oil/refrigerant solubility characteristics, charge from the compressor sump also moves to the condenser. In the microchannel systems, the heat exchangers account for only 20% of the system charge as opposed to 70% in the tube fin systems. At higher ambient temperatures, the additional charge flowing from the other components, provides the condenser with the additional ~7% charge it needs at hot ambient conditions. However, due to the small internal volume of the heat exchangers in microchannel systems, an additional 60% charge flows into the condenser, resulting in high values of subcooling, thus reducing system efficiency. One solution to this problem would be to install a receiver at the outlet from the condenser, to retain high levels of efficiency across a wide range of operating conditions.Air Conditioning and Refrigeration Project 14