Deleterious effects of cardiopulmonary bypass on early graft function after single lung allotransplantation: evaluation of a heparin-coated bypass circuit

Clinical lung transplantation may necessitate the use of cardiopulmonary bypass during the procedure, resulting in increased morbidity with more severe early graft dysfunction and increased blood loss. A heparin surface-coated cardiopulmonary bypass circuit is now available with improved biocompatibility and reduced systemic heparin requirements and may offer advantages compared with standard uncoated cardiopulmonary bypass circuits. This study investigates in a canine model of single-lung allotransplantation whether cardiopulmonary bypass adversely affects early graft function and whether a heparin-coated cardiopulmonary bypass circuit with reduced systemic heparin dosage improves results compared with standard uncoated cardiopulmonary bypass systems. Fifteen dogs underwent left single-lung allotransplantation with occlusion of the contralateral pulmonary artery and bronchus 1 hour after reperfusion. In one group, five animals underwent the procedure without cardiopulmonary bypass. In the group with uncoated circuits, five animals underwent the procedure with the use of standard uncoated cardiopulmonary bypass circuits with full systemic heparin dosage. In the group with heparin-coated circuits, five animals underwent the procedure with the use of heparin-coated cardiopulmonary bypass circuits and reduced systemic heparin dosage. Early graft function was evaluated by arterial oxygenation, pulmonary mechanics, lung water measurements, and histologic analysis. Hemodynamics and postoperative blood loss were also measured. Two hours after reperfusion, partial pressure of oxygen in arterial blood on an inspired oxygen fraction = 1.0 was significantly greater (p < 0.001) in the group without cardiopulmonary bypass (467 +/- 58 mm Hg) than in the group with uncoated circuits (114 +/- 90 mm Hg) and the group with heparin-coated circuits (193 +/- 105 mm Hg), with no significant difference between the groups undergoing bypass procedures. Lung compliance decreased and lung water increased in all transplanted lungs without significant differences between groups. Histologic analysis did not differentiate between the groups. After reperfusion, cardiac index and mean arterial pressure were significantly reduced in the groups with uncoated circuits and with heparin-coated circuits compared with the group that did not undergo cardiopulmonary bypass (p < 0.001). Postoperative blood loss was significantly less (p < 0.002) in the group that did not undergo cardiopulmonary bypass (90 ml +/- 38 ml) compared with both the group with uncoated circuits (750 +/- 15 ml) and the group with heparin-coated circuits (690 +/- 387 ml), with no significant difference between the groups that underwent bypass. The use of cardiopulmonary bypass with systemic heparinization is detrimental to early graft function in this canine model of left single-lung allotransplantation.(ABSTRACT TRUNCATED AT 400 WORDS)     

Polarisation-insensitive fibre optic Michelson interferometer

A polarisation-insensitive fibre optic Michelson interferometric sensor configuration is demonstrated. The approach is based on the use of birefringence compensation in a retraced fibre path using Faraday rotator mirror elements.<>     

Multiplexing of sensors based on fibre-optic differential delay RFfilters

Describes frequency-division multiplexing of intensity modulation filtering sensors. The feasibility of the scheme was demonstrated by multiplexing a pressure sensor, measured over the range 0-500 psi, and a temperature sensor, measured over the range 10-40°C     

Optimization and stabilization of visibility in interferometricfiber-optic sensors using input-polarization control

The effects of input polarization on the output fringe visibility of two-beam interferometric fiber-optic sensors are investigated, and an analysis which predicts the existence of input states of polarization of eigenmodes of the interferometer for which optimum output visibility is obtained is presented. Experimental results obtained using both a bulk-optic and a fiber Mach-Zehnder interferometer are reported that verify this analysis. Active feedback stabilization of the output fringe visibility of an interferometric sensor using automatic input-polarization control is demonstrated     

Prediction of the PPARα agonism of fibrates by combined MM-docking approaches

Fibrates are peroxisome proliferator-activated alpha receptor (PPARα) activators derived from fibric acid and are the most clinically used therapeutics in the treatment of hypertriglyceridemia. Long standing studies on these drugs have accumulated a large body of experimental data about their biological activity and, more recently, on the molecular mechanism mediating their PPARα agonism. An immense interest for the discovery of new fibrates with improved potency and PPARα selectivity has stimulated many investigations toward a deeper understanding of structure-activity relationships controlling their activity. The present study aimed at investigating the binding properties of a set of 23 fibrates, characterized by similar carboxylic heads but differing in the size and orientation of the hydrophobic portion, using computational approaches. We combined standard docking and molecular mechanics approaches to better describe the adaptation of the protein target to the bound ligand. The agonist potencies were then regressed against the calculated binding energies to elaborate predictive model equations. The obtained models were characterized by good performances realizing a fair trade-off between accuracy and computational costs. The best model was obtained with a regression procedure allowing automatic generation of a training subset from the whole set of trials and filtering out outliers, thus highlighting the importance of regression strategies.     

Numerical diffusive terms in weakly-compressible SPH schemes

A discussion on the use of numerical diffusive terms in SPH models is proposed. Such terms are, generally, added in the continuity equation, in order to reduce the spurious numerical noise that affects the density and pressure fields in weakly-compressible SPH schemes. Specific focus has been given to the theoretical analysis of the diffusive term structure, highlighting the main benefits and drawbacks of the most widespread formulations. Finally, specific test cases have been used to compare such formulations and to confirm the theoretical findings.     

Scientometric portraits of recognized scientists: a structured literature review

Scientometrics - The purpose of scientometric portraits is to recognize prominent scholars, inspire others, and guide those who dedicate their lives to scientific advancement. This study presents...     

Properties of constitutive matrices for electrostatic and magnetostatic problems

Constitutive matrices allow one to write the constitutive relations, in an algebraic form, in some finite-volume-based numerical methods, such as the cell method and the finite integration technique. This paper shows some properties that link a general class of constitutive matrices to the finite-element stiffness matrices. One of these properties can be exploited to provide an alternative sufficient condition for the stability of a generalized finite-difference time-domain algorithm set up by these numerical methods.     

A model-driven approach for vulnerability evaluation of modern physical protection systems

Software and Systems Modeling - Modern physical protection systems integrate a number of security systems (including procedures, equipments, and personnel) into a single interface to ensure an...