Biomedical subjects
G W Buffaloe
Publications and source records attributed to G W Buffaloe.
Evaluation of a parallel plate membrane plasma exchange system.
A new parallel plate membrane plasma exchange system (Centry TPE System) has been developed and clinically evaluated. A series of 27 consecutive plasma exchanges were performed on 14 patients with autoimmune diseases. Blood access was obtained by routine means identical to centrifugal procedures. The blood flow rate was 94 +/- 20 ml/min and plasma filtration rate was 37 +/- 9 ml/min, with an average patient hematocrit of 36%. The sieving coefficients for a wide range of plasma solutes including immunoglobulins, immune complexes, and lipids, clustered about 1.00, indicating nonselective plasma filtration. The average reduction in patient plasma solutes of 60 to 70% was in close agreement with the predicted value for unhindered plasma filtration. There was no appreciable loss of blood cells, as compared to a study with a centrifugal system showing a 56% reduction in circulating platelets. Complement activation measured by C'3 conversion was undetectable in patient samples and either undetectable or minimal in plasma filtrate samples. The system was convenient to operate and problems were rare. No untoward patient effects attributable to the membrane system were observed. These results show that the parallel plate membrane plasma exchange system described in this report is capable of delivering safe, efficient plasma exchange.
Clinical evaluation of a flat-plate membrane plasma exchange system.
A new flat-plate membrane plasma separation system specifically designed for therapeutic plasma exchange (TPE) was clinically evaluated in both research and routine clinical settings. The study included a comparison to a currently available centrifugal cell separation system employed for TPE. A total of 267 membrane procedures were performed on 39 patients over a 14-month period. Both qualitative and quantitative studies showed that membrane plasma exchange procedures were equivalent to centrifugal procedures in the removal of plasma constituents from patients. A notable difference between the two types of procedure was the effect on the peripheral blood platelet count: the plasma filtrate from the membrane system was essentially cell-free and platelet counts fell only 11% during the procedure, compared to a 53% decrease during the centrifugation runs. Patient responses to both types of procedure were similar and the frequency of side-effects was low. A sampling of patient opinion revealed a preference for the membrane system for a variety of reasons. Procedure times were shorter with the membrane system because of higher achievable blood flow rates, and thus higher plasma exchange rates, while the overall nursing time requirement was lower. The results show that this flat-plate membrane TPE system enables rapid and effective plasma exchange therapy, and offered a number of monitoring and control functions that provided a safer, more efficient therapeutic procedure in the majority of patient treatments performed in this study.
Antibodies to human glomerular basement membrane: modified methodology for detection in human serum.
A new radioimmunoassay for detection of circulating antibodies to human glomerular basement membrane (GBM) is described. GBM was isolated, purified, and an antigenic component extracted by 8 M urea incubation. The 8 M urea extract was radiolabelled, separated on Sephadex G-150, and employed as GBM antigen for detection of binding in a double antibody radioimmunoassay (RIA). Three groups of sera were studied: (a) 40 normal subjects bound a mean of 0.5% +/- 3.4% (s.d.), (b) 12 patients with glomerulonephritis with non-linear immune deposits in direct immunofluorescent staining of kidneys bound a mean of 0.2% +/- 4.4% (s.d.), (c) 14 patients with Goodpasture's syndrome or glomerulonephritis with linear deposits in direct immunofluorescent staining of kidneys bound a mean of 23% +/- 9.1% (s.d.). Serial dilutions of sera from patients with Goodpasture's syndrome showed a progressive reduction in binding while binding of positive sera was inhibited by increasing quantities of unlabelled GBM. The GBM antigen extracted with 8 M urea is convenient to prepare and conditions for performance of the RIA are reproducible. Hence, this may represent a valuable on-site aid for diagnosis and management of patients with anti-GBM mediated glomerulonephritis.
Plasma volume nomograms for use in therapeutic plasma exchange.
Nomograms have been developed for the convenient estimation of the plasma volumes of patients undergoing therapeutic plasma exchange (TPE), based on equations employing height, body weight, and hematocrit. These nomograms are offered as an aid to prescribing continuous-flow TPE procedure exchange volumes.