Rapid reperfusion causes stress failure in ischemic rat lungs

OBJECTIVE: Rapid reperfusion may be injurious to the ischemic lung. Our aim was to confirm that slow reperfusion improves postischemic pulmonary function and to elucidate the ultrastructural changes associated with slow versus rapid reperfusion. METHODS. We used an ex vivo perfused rat lung transplant model to study the effect of slow versus rapid reperfusion on subsequent lung function and morphologic conditional. Functional assessment was performed in (1) fresh lung, slowly reperfused; (2) fresh lung, rapidly reperfused; (3) ischemic lung (4 hours at 22 degrees C), slowly reperfused; and (4) ischemic lung, rapidly reperfused. RESULTS: In group 4, the shunt fraction (P=.001), airway pressure (P=.001), and wet/dry ratio (P=.01) were significantly higher than in groups 1 through 3. Light and electron microscopy of slowly reperfused ischemic lungs (n=4) appeared normal. Rapidly reperfused ischemic lungs (n=4) demonstrated massive alveolar edema hemorrhage, and epithelial "blebbing" by light microscopy. Electron microscopy identified the blebbing as separation of the epithelial layer from an intact basement membrane by edema fluid. The epithelial layer was disrupted in numerous locations. Complete disruption of all layers of the blood-gas barrier was occasionally present. CONCLUSION: Rapid reperfusion of the ischemic lung is an important contributing factor to reperfusion lung injury resulting in mechanical stress failure of the alveolar/capillary barrier. Gradual reintroduction of blood flow to the ischemic lung improves oxygenation.     

Decomposition of 1,2‐dichloroethane in an RF plasma environment

A radio frequency (RF) plasma system has been used to decompose 1,2‐dichloroethane (DCE). Final products were identified by a Fourier transform infrared (FTIR) spectrometer. The main products of DCE decomposition in O₂/Ar plasma were CO₂, CO, and HCl. Other minor chlorinated products were CCl₄, C₂HCl₃, C₂H₃Cl, C₂Cl₄, CHCl₃, C₂HCl₅, and COCl₂. Nonchlorinated products were C₂H₂, C₂H₄, C₂H₆, and HCOOH. The plasma reactor with a brass electrode had a higher decomposition fraction of DCE [η, (C_in ? C_out)/C_in × 100%] than that obtained with other materials (Au, Ni, and Cr). Different electrode configurations (inner and outer) were also evaluated for the decomposition of DCE. Argon plus oxygen was found to be the most suitable carrier/auxiliary gas for DCE decomposition. In addition, operational parameters for DCE decomposition in RF plasma including concentration, operational pressure, and total gas flow rate were evaluated. Copyright © 2003 Society of Chemical Industry     

Reoperation for failed prosthetic replacement used for limb salvage

Patients with segmental bone and joint replacement prostheses because of tumors increasingly need revision surgery because of their long term survival. Between 1970 and 1990, 208 custom prosthetic replacements were performed for limb salvage in patients with tumors. Reoperations were required in 52 patients. The mean time to reoperation was 37 months. The reoperation procedures included 35 prosthetic revisions, 11 amputations, four arthrodeses, one vascularized fibular graft, and one open reduction and internal fixation of a fracture with supplemental bone graft. Functional assessment using the new Musculoskeletal Tumor Society scoring system was available for the 36 living patients, and their mean rating was 63% (18.9) at 12 years' mean followup. Of the 35 patients who received a new prosthesis, 12 (33%) patients needed a third operation at mean followup of 68 months. The probability of prosthetic survival in the group of 35 patients needing revision to the same or another prosthesis was 79% at 5 years and 65% at 10 years. The chance and frequency of needing reoperation increased as patients survived longer. Reoperations for tumor recurrence or infection usually resulted in amputation. Reoperation for failed initial segmental bone and joint prosthetic replacement is feasible and effective and can be done without jeopardizing subsequent patient and implant survival or without significantly affecting functional results compared with the values before reoperation.     

Studies of glycolysis of poly(ethylene terephthalate) recycled from postconsumer soft‐drink bottles. II. Factorial experimental design

Glycolysis temperature, glycolysis time, and amount of catalyst are important factors affecting the glycolysis of recycled poly(ethylene terephthalate) (PET) flakes. A 2³ factorial experimental design is applied to study the main, two‐factor interaction, and three‐factor interaction effects of glycolysis temperature, glycolysis time, and amount of catalyst on the glycolysis of recycled PET flakes. In this study cobalt acetate is used as the glycolysis catalyst. The sequence of the main effects on the glycolysis conversion of the recycled PET flakes in ascending order is glycolysis time < glycolysis temperature < amount of catalyst. The sequence of the two‐factor interaction effects on the glycolysis conversion of the recycled PET flakes in ascending order is glycolysis temperature versus the glycolysis time < glycolysis time versus the amount of catalyst < glycolysis temperature versus the amount of catalyst. The three‐factor interaction effect is significantly related to the glycolysis conversion of the recycled PET flakes. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 956–962, 2001     

Two-point calibration procedure of the forced oscillation technique

The extent of xre gene divergence was studied in nine soil bacillus strains with different degrees of relationship to Bacillus subtilis 168. This gene product is a repressor of defective phages. Bac. subtilis 168 recipient strains were transformed by DNA from these bacillus strains for the xhi-1479 marker and ten markers of amino acid and nitrous bases metabolism. The efficiency of soil strain DNA hybridization with Bac. subtilis 168 DNA was assessed. Eight strains were close to Bac. subtilis 168 with respect to the efficiency of heterotransformation for all markers and hybridization, and one strain (1621) strongly differed from other strains with regard to these parameters. As determined by the degree of differences in heterotransformation for all markers, the nucleotide sequence of the xre gene diverged in the evolution process at a rate similar to that of the nucleotide sequences of the housekeeping genes. All examined genes were shown to have similar selective value.     

Studies on mesomorphic behaviors of segmented azoxy polyester containing polyoxyethylene

A series of a segmented copolymer, poly(4,4′-dioxy-2,2′-dimethyl-azoxybenzene dodecanedioyl)-co-polyoxyethylene 400 (PMABD-co-POE) was prepared; the average chain lengths n, of the PMABD studied are 8.1 to 20.6. The thermotropic properties and the mesophase texture of the segmented copolymers were elucidated as functions of n using a differential scanning calorimeter and a polarized optical microscope with a hot stage. The results show that the incorporation of POE with PMABD decreases the intermolecular interaction force and changes the chain flexibility. The nematic droplets obtained near the isotropic temperature all exhibited a twisted bipolar configuration. Also, in the undercooling process, the nematic textures obtained before crystallizing varied with n. The copolymers containing n ≥ 17, like PMABD, develop a Schlieren texture, whereas those containing n < 17 develop a distorted-stripe conformation. A possible mechanism for interpretation of the obtained results has been proposed. © 1995 John Wiley & Sons, Inc.     

Vascular complications in orthopaedic patients treated by orthopaedic microsurgeons

Over a 20 year period, five patients experienced serious vascular complications involving major arterial insult during various routine orthopaedic procedures. The nature of the vascular damage necessitated immediate surgical repair which was performed successfully by an orthopaedic microsurgeon who was either a member of the initial surgical team or the hospital's Orthopaedic Unit. The purpose of this study is to illustrate not only the severity of these limb and/or life-threatening complications, but also to focus attention on the importance of the orthopaedic surgeon's ability to manage these serious injuries promptly. This suggests the need for Orthopaedic Units to have surgeons with adequate training in microvascular techniques, so as to be able to successfully manage these unexpected and serious complications. We conclude that the presence of a vascular surgeon or an orthopaedic surgeon trained in microvascular surgery represents an invaluable attribute to the orthopaedic team, and minimizes, if not eliminates the potentially disastrous outcome from these serious intraoperative vascular complications.     

Finite element method for non-linear forced vibrations of circular plates

Geometric non-linearities for large amplitude free and forced vibrations of circular plates are investigated. In-plane displacement and in-plane inertia are included in the formulation. The finite element method is used. An harmonic force matrix for non-linear forced vibration analysis is introduced and derived. Various out-of-plane and in-plane boundary conditions are considered. The relations of amplitude and frequency ratio for different boundary conditions and various load conditions are presented.