Effect of race on outcome after kidney and kidney-pancreas transplantation in type 1 diabetic patients

OBJECTIVE: The racial impact on graft outcome is not well defined in diabetic recipients. The purpose of this study is to analyze our experience with kidney-alone (A) and kidney-pancreas (KP) transplantation in type 1 diabetic recipients and evaluate the impact of racial disparity on outcome. RESEARCH DESIGN AND METHODS: The records of 217 kidney transplants (118 KA, 99 KP) performed on type 1 diabetic patients between 1985 and 1995 at the Medical University of South Carolina and the University of Texas Medical Branch were reviewed. RESULTS: A total of 53 (31%) white patients and 15 (33%) black patients experienced at least one episode of biopsy-proven acute rejection of the renal graft (NS). Patient survival at 1, 2, and 5 years was similar in white (92, 87, 69%) and black (91, 91, 69%) patients (NS). Kidney graft survival at 1, 2, and 5 years in the KA group was 72, 62, and 42% in blacks, compared with 79, 76, and 53% in whites (NS). Kidney graft survival at 1, 2, and 5 years in the KP group was 92, 92, and 74% in blacks, compared with 83, 77, and 58% in whites (NS). Pancreas graft survival at 1, 2, and 5 years was 81, 81, and 81% in blacks, compared with 81, 75, and 62% in whites (NS). Cox regression analysis revealed that donor age > or = 40 years increased the risk of renal graft failure 6.2-fold (P = 0.0001), whereas the addition of a pancreas transplant to a kidney and a living-related transplant decreased the risk of failure of the kidney graft 0.2 (P = 0.005) and 0.1 times (P = 0.005). CONCLUSIONS: Our results suggest that when compared with whites, there may be a trend toward an improved kidney and pancreas graft outcome in blacks undergoing KP transplants. These findings suggest that diabetes may override the risk factors that account for the pronounced disparity in outcome observed between nondiabetic white and black recipients.     

Controlled pore size, thickness and surface free energy of super-hydrophobic PVDF® and Hyflon®AD membranes

Super-hydrophobic membranes were manufactured by using two per-fluorinated polymers such as PVDF and Hyflon AD. The combination of controlled structure and supra-molecular chemistry made these membranes ideal interfaces to be used in membrane contactors.     

Electrochemical characterization of sulfonated PEEK-WC membranes for PEM fuel cells

Sulfonated PEEK-WC polymer was obtained according to chloro-sulfonic acid procedure making possible the preparation of different membrane samples with a sulfonation degree from 48 to 90%. Dense membranes were prepared from casting solutions of S-PEEK-WC dissolved in DMF. Proton conductivity measurements were performed on such S-PEEK-WC membranes in a range of temperature from 30 to 120 °C and 100% of relative humidity, reaching 2.5 × 10⁻² S cm⁻¹ as the best value at 100 °C and with a sulfonation degree of 90%. In the meanwhile, the open circuit voltage of this S-PEEK-WC membrane (DS = 90%) varied from 0.963 V at 60 °C to 0.802 V at 100 °C, demonstrating that an increase of temperature negatively affects the membrane performance due to the mechanical properties degradation. In this work, a wide experimental campaign was carried out to investigate the electrochemical performances in terms of polarization curves, open circuit voltage and proton conductivity of S-PEEK-WC membranes as well as the fuel crossover and water uptake.     

Urologic complications after simultaneous pancreas-kidney transplantation: hand-sewn versus stapled duodenocystostomy

Pancreas transplantation with bladder drainage of exocrine secretions may be associated with significant urologic complications. Stapled and hand-sewn duodenocystostomies were compared in 61 recipients of simultaneous pancreas-kidney transplants. Both methods resulted in similar urologic complication and allograft survival rates. Duodenal segment leaks were associated with significant morbidity and decreased patient and allograft survival.     

Evaluation of CO2 permeation through functional assembled mono-layers: Relationships between structure and transport

CO₂ transport through functional assembled mono-layers was evaluated in relation to H₂O and nonpolar gases such as CH₄, O₂, N₂. Membranes based on Pebax^®2533 were functionalised by incorporating chemical compounds containing free hydroxyl, N-alkyl sulphonamide, bulky benzoate groups. The effects of both the chemical nature and concentration of the modifier on the gas transport were reported, respectively. The permeability coefficients of different penetrating chemical species were compared, evidencing the higher affinity of the layers to water vapour and carbon dioxide, due to favourable interactions between polar moieties and penetrant. The condensability of the penetrant directed the permeability of the species considered and was responsible for the high solubility selectivity between H₂O and CO₂ (i.e. , DH₂O/D₂CO=0.6, SH₂O/S₂CO=11.4 at 25 °C for Pebax/KET 50/50 w/w). An increase in polar moieties resulted in enhanced permeability and selectivity with respect to the pure polymer. In contrast, the functionalised polymer was not capable to discriminate between the smallest penetrants such as O₂ and N₂, with consequent decrease in the ideal selectivity (P₂CO/O₂, P₂CO/N₂). The functional layers exhibited permeability and selectivity covering broad ranges of values.     

Sulfonation of PEEK-WC polymer via chloro-sulfonic acid for potential PEM fuel cell applications

The preparation and characterization of thin dense sulfonated poly-ether-ether-ketone with cardo group (PEEK-WC) membranes for proton exchange membrane fuel cell (PEMFC) applications are described. The sulfonation of PEEK-WC polymer was realized via chloro-sulfonic acid and different kinds of membrane samples were prepared with a sulfonation degree ranging from 67 to 99%. The degree of sulfonation, homogeneity and thickness significantly affect both the membrane transport properties and the electrochemical performances. The dense character of the membranes was confirmed by SEM analysis. Proton conductivity measurements were carried out in a temperature range from 30 to 80 °C and at 100% of relative humidity, reaching 5.40×10⁻³ S/cm⁻¹ as best value at 80 °C and with a sulfonation degree (DS) of 99%. At the same conditions, a water uptake of 17% was achieved. DSC and TGA characterizations were used in order to determine the thermal stability of the membranes, confirming a T_g ranging between 206 and 216 °C depending on the DS, whereas FT-IR yielded indication about intermolecular interactions and water uptake at various sulfonation degrees.     

Experimental and theoretical evaluation of the membrane affinity to water: role of modifiers in the control of the matrix performance

This work was aimed at evaluating adsorption of water molecules onto membrane surfaces modified by sulphonamide derivates. Controlling interfacial forces at the membrane-feed interface were assessed by combining experimental and theoretical studies. The phenomena experimentally observed were also interpreted by using quantum-chemical and dynamic approaches in order to correlate the membrane affinity to water with the availability and accessibility of polar moieties, enabling to form intermolecular interactions such as hydrogen bonds.     

Novel PEEK-WC membranes with low plasma protein affinity related to surface free energy parameters

There has been growing interest in innovative materials with specific physico-chemical properties that provide an improved blood/cell compatibility. In this paper we evaluated the performance of new membranes prepared from a modified polyetheretherketone (PEEK-WC) contacting human plasma proteins. These membranes were prepared by using the phase inversion technique. Membrane wettability and affinity to proteins were evaluated by means of contact angle experiments, roughness measurements, and quantitative UV analysis. The energy parameters of membrane surfaces were determined according to Good, van Oss and Chaudhury's theory. The extent of human albumin, fibrinogen and immunoglobulin G adsorption was related to quantitative expressions of the membrane surface hydrophilicity: the base parameter of surface free energy and the free energy of interfacial interaction. The performance of PEEK-WC membranes was compared to that of commercial membranes, which conventionally are used in biomedical applications. The experimental results showed a reduction of protein adsorption on PEEK-WC membranes with respect to other commercial membranes. The low protein affinity of PEEK-WC membranes is due to the intrinsic physico-chemical characteristics of the polymeric material which makes these membranes interesting for potential use in biomedical applications.     

Two simple new bibliometric indexes to better evaluate research in disciplines where publications typically receive less citations

The paper proposes two simple new indexes—k and w—to assess a scientist’s publications record based on citations. The two indexes are superior to the widely used h index (Hirsch, 2005), as they preserve all its valuable characteristics and try to overcome one of its shortcomings, i.e. that it uses only a fraction of the information contained in a scientist’s citations profile and, as a result, it is defined over the set of positive integers and does not show a sufficiently fine ‘granularity’ to allow a fully satisfactory ranking of scientists. This problem is particularly acute in many areas of Social Sciences and Humanities, where scientific productivity and citation practices typically yield fewer citations per paper and, as a consequence, are characterized by ‘structurally’ lower values of the h index. Both the indexes proposed are defined over R⁺, their integer part is equal to the scientist’s h index and they fall in the right-open interval [h, h+1). While the h index is influenced only by part of the citations received by a scientist’s most-cited publications, the k index takes into account all the citations received by her most-cited publications and the w index accounts for the citations received by the entire set of her publications. Variants of the k and w indexes are proposed which consider co-authorship. To show the extent to which the h index and the new indexes proposed may yield different results, they are calculated for 332 professors of economics in Italian universities and the results obtained used to rank Italian university departments.