A double-blind clinical trial of laxogas evacuant suppositories.

A double-blind study was carried out to evaluate Laxogas gas producing suppositories--in inpatients confined to bed for long periods, and in elderly outpatients with constipation. Laxogas was found to give positive results in 92 per cent of cases treated, the time for evacuation of the bowel ranging from 15--40 min. No side effects were noticed.

Membrane plasma fractionation: effect of the surface area.

The influence of the surface area on the performance of plasma filters for dead-end mode of filtration is presented in this paper. Theoretical analysis of the dead-end filtration was performed and verified experimentally (using ENKA cellulose-diacetate PF-100 membranes) in respect to beta-lipoprotein. The theoretical model allows to optimize the course of the transmembrane pressure during plasma fractionation procedure in dependence of the surface area, initial concentration of macromolecules, total volume of the feed and membrane structure. The results indicate that the surface area effect is an important factor in the operation of membrane plasma fractionation and should be considered in the design of the plasma fractionation filter.

[Pharmacokinetics of acetaminophen in individuals occupationally exposed to polyvinyl chloride modified with plasticizers]. / Farmakokinetyka n-acetylo-p-aminofenolu u osób narazonych zawodowo na dzialanie polichlorku winylu modyfikowanego plastyfikatorami.

The aim of this study was to evaluate the health state of a random group of subjects occupationally exposed to polyvinyl chloride. The emphasis was put on the hepatic functional tests in comparison with acetaminophen pharmacokinetics. Forty two males were assigned to two groups: the control group free from occupational exposure and the group exposed to polyvinyl chloride. The latter one was divided into two subgroups according to the length of exposure. The following examinations were carried out in all subjects: subjective and physical examinations, basic laboratory and functional hepatic tests, radioisotope examinations of the liver and spleen, and acetaminophen pharmacokinetics was analysed as well. Acetaminophen was administered intragastrically in a single dose of 1.0 g. Blood was collected within 24 hrs after drug administration. The method of Routh et al. was used for determination of paracetamol concentration. A two-compartment open model for extravascular administration was used for calculation of pharmacokinetic parameters. The results suggest that polyvinyl chloride leads to an accelerated acetaminophen biotransformation, regardless of the length of occupational exposure. There was no correlation between changes in paracetamol metabolism and standard functional hepatic tests. The acetaminophen test can be useful in detecting alterations in the activity of hepatic microsomal enzymes, a symptom of early occupational exposure to chemical compounds with potential hepatoxic properties.

Blood cell effects in membrane plasma separation.

The blood cell and membrane properties are important in determining hemolysis and cell deposition, as shown previously, and thus are determinants of the maximum plasma separation rates. In general, membranes with large mean pore sizes exhibit hemolysis at lower operating transmembrane pressures. Surface structure and not necessarily por tortuosity has been found to be more important, at least for the hollow fiber membranes studied. Mean membrane pore data coupled with SEM observations were useful in correlating red cell lysis with membrane properties. The red cell may be likened to a liquid drop, encased by a flexible deformable membrane. Cell deformation, orientation, and rotation increase as does interfacial surface tension with rising rates of shear. A high correlation of interfacial surface tension with shear rate was determined using a filtration model incorporating cell deformability. Interfacial surface tensions of less than 6 dynes/cm for shear rates up to 1000s-1 were found. Inclusion of blood and membrane properties in the analysis of plasma separation gives significantly better fit of the experimental data to theoretical correlations than do other models which exclude their consideration.

Theoretical formulation of sieving coefficient evaluation for membrane plasma separation.

Three different sieving coefficient definitions were theoretically investigated. It has been shown that the local sieving coefficient, characterizing membrane property, can be calculated under specified assumptions from input-output measurements. In contrast, the evaluation of the device sieving coefficient, useful in kinetic modeling, is validated in a situation in which calculation of the local sieving coefficient is connected with substantial error. The relationship between different sieving coefficient definitions is also given.

Blood purification by a membrane technique--a new method for the effective removal of low-density lipoprotein cholesterol.

A membrane plasma fractionation (MPS) technique is applied in order to obtain selective removal of pathological plasma components from the extracorporeal circuit. An effective plasma fractionation procedure should be characterized by the highest possible removal of the pathological plasma components and, equally as important, the lowest unwanted protein losses caused mainly by adsorption to the membrane structure. In order to obtain a higher efficiency of the MPS procedure (high selectivity between removal of pathological plasma components and unwanted losses mainly represented by albumin) several methods such as thermofiltration, application of pulsate flow at the end of secondary filter, etc. have been developed. Clinical verification of these methods led to some improvement in MPS procedure but these results did not seem to be optimal. The main objective of this paper is to present a new two-stage membrane system utilizing a high flow recirculation circuit developed particularly, but not only, for effective removal of low-density lipoprotein cholesterol. The designed and developed system has been tested in vitro using several different plasma fractionation membranes. The results obtained indicated the importance of the membrane structure and membrane material on the efficiency of the tested plasma fractionation procedure. It was also found that it is possible to obtain negligible protein losses for some selected membrane structures applied in the assessed system. Based on preliminary results, it seems that the new two-stage membrane system proposed could be characterized by a very low range of unwanted protein losses leading to high effectiveness of the plasma fractionation procedure.

A high selectivity cascade filtration technique for LDL-cholesterol and Lp(a) removal.

This work proposes an improvement of the cascade filtration technique in the treatment of familial hypercholesterolemia. A model of the whole process permitted the definition of the parameters that could influence the selectivity of the fractionation: the pore size, the sieving coefficients of both fractionation and plasmapheresis membrane, and the final retentate flow rate. In vivo studies have shown that the dead-end mode for the secondary filter was not always practical because of severe membrane plugging except when a pulsatile pump was included in the extracorporeal circuit. This pump generated hydrodynamic instabilities which decreased membrane fouling and retarded the build up of the polarization concentration layer. Optimization of these specific operating conditions permitted increase in the selectivity index from 1.15 to 2.24. The performances of cascade filtration were then comparable to those of adsorption on dextran sulfate columns.

Ex vivo preclinical evaluation of membrane plasma separators.

Four different types of hollow-fiber membrane plasma separators, constructed of cellulose acetate, polyvinyl alcohol, polyethylene, and polymethylmethacrylate membranes, were evaluated in ex vivo dog perfusions under conditions simulating their clinical use. An arteriovenous (A-V) fistula constructed in the dogs for blood access enabled repeated access to be achieved without surgical intervention. All modules produced transient leukopenia and a reduction of platelet counts. The polymethylmethacrylate module showed minimum reductions of white blood cell counts and CH50. The early leukocyte count reduction in membrane plasmapheresis is most likely related to the magnitude of complement activation by the membrane, as is seen with hemodialysis.