Methallylsulfonate Copolymer Research Articles

Contribution of Adsorption and Hematocrit Levels to Ganciclovir Clearance in an in Vitro Continuous Hemodiafiltration Model.

Estimation of the continuous hemodiafiltration (CHDF) clearance (CLCHDF) of ganciclovir (GCV) is crucial for achieving efficient treatment outcomes. Here, we aimed to clarify the contribution of diafiltration, adsorption, and hematocrit level to the CLCHDF of GCV in an in vitro CHDF model using three membranes: polyacrylonitrile and sodium methallyl sulfonate copolymer coated with polyethylenimine (AN69ST); polymethylmethacrylate (PMMA); and polysulfone (PS). In vitro CHDF was performed with effluent flow rates (Qe) of 800, 1500, and 3000 mL/h. The initial GCV concentration was 10 µg/mL while that of human serum albumin (HSA) was 0 or 5 g/dL. The CLCHDF, diafiltration rates, and adsorption rates were calculated. The whole blood-to-plasma ratio (R) of GCV for a hematocrit of 0.1 to 0.5 was determined using blood samples with 0.5 to 100 µg/mL of GCV. The in vitro CHDF experiment using AN69ST, PMMA, and PS membranes showed that the total CLCHDF values were almost the same as the Qe and not influenced by the HSA concentration. The diafiltration rate exceeded 88.1 ± 2.8% while the adsorption rate was lower than 9.4 ± 9.4% in all conditions. The R value was 1.89 ± 0.11 and was similar at all hematocrit levels and GCV concentrations. In conclusion, diafiltration mainly contributes to the CLCHDF of GCV, rather than adsorption. Hematocrit levels might not affect the relationship between the plasma and blood CLCHDF of GCV, and the CLCHDF of GCV can be estimated from the Qe and R, at least in vitro.

The influence of continuous renal replacement therapy on 1,3-β-d-glucan levels in critically ill patients: a single-center retrospective propensity score study

1,3-β-d-Glucan (BDG) is commonly used for diagnosing invasive fungal infections (IFIs). While exposure to cellulose-based hemodialyzers is known to cause false-positive BDG results, the impact of modern hemofilters used in continuous renal replacement therapy (CRRT) remains unclear. This retrospective, single-center cohort study aimed to evaluate the effect of CRRT on BDG levels in critically ill patients. We included adult intensive care unit (ICU) patients with ≥1 BDG measurement between December 2019 and December 2020. The primary outcome was the rate of false-positive BDG results in patients exposed to CRRT compared to unexposed patients. Propensity score analysis was performed to control for confounding factors. A total of 103 ICU patients with ≥1 BDG level were identified. Most (72.8%) were medical ICU patients. Forty patients underwent CRRT using hemofilter membranes composed of sodium methallyl sulfonate copolymer (AN 69 HF) (82.5%) and of polyarylethersulfone (PAES) (17.5%). Among the 91 patients without proven IFI, 31 (34.1%) had false-positive BDG results. Univariable analysis showed an association between CRRT exposure and false-positive BDG results. However, the association between CRRT exposure and false-positive BDG results was no longer significant across three propensity score models employed: 1:1 match (n = 32) (odds ratio (OR) 1.65, p = .48), model-adjusted (n = 91) (OR 1.75, p = .38), quintile-adjusted (n = 91) (OR 1.78, p = .36). In this single-center retrospective analysis, exposure to synthetic CRRT membranes did not independently increase the risk of false-positive BDG results. Larger prospective studies are needed to further evaluate the association between CRRT exposure and false-positive BDG results in critically ill patients with suspected IFI.

In vitro analysis of factors affecting the continuous hemodiafiltration clearance of teicoplanin.

In the treatment of sepsis, continuous hemodiafiltration (CHDF) and the administration of antibiotics such as teicoplanin (TEIC) are frequently performed in parallel. We aimed to clarify the factors influencing the CHDF clearance (CLCHDF ) of TEIC using a polymethylmethacrylate (PMMA) membrane or a polyacrylonitrile and sodium methallyl sulfonate copolymer membrane coated with polyethylenimine (AN69ST). We also investigated whether the adsorption of TEIC onto the hemofilters inhibits the adsorption of interleukin (IL)-6 onto the membranes. TEIC, human serum albumin (HSA), and IL-6 were incubated with pieces of hemofilter membranes and adsorption rates were calculated. The CLCHDF , diafiltration rate, and adsorption rate of TEIC were calculated using an in vitro CHDF circuit model. The adsorption rates of TEIC onto the pieces of PMMA and AN69ST membranes ranged from 15.0% to 100% and from -10% to 5%, respectively. The adsorption rate of IL-6 was similar with or without TEIC. The CLCHDF and adsorption rate of TEIC under PMMA-CHDF depended on HSA, but not on effluent flow rate (Qe). The CLCHDF under AN69ST-CHDF depended on HSA and Qe. The observed CLCHDF under AN69ST-CHDF was similar to the predicted value (the product of Qe and the plasma unbound fraction). The observed CLCHDF under PMMA-CHDF was 2.0-7.8 times greater than the predicted value. Adsorption mainly contributes to the CLCHDF of TEIC using PMMA membranes, whereas diafiltration mainly contributes to the CLCHDF of TEIC using AN69ST membranes. TEIC adsorption might not affect the adsorption of IL-6 onto PMMA membrane.

Contribution of diafiltration and adsorption to vancomycin clearance in a continuous hemodiafiltration circuit model in vitro.

Vancomycin (VCM) is eliminated mainly by diafiltration under continuous hemodiafiltration (CHDF), but the contribution of adsorption to CHDF clearance (CLCHDF ) of VCM using a polyacrylonitrile and sodium methallyl sulfonate copolymer membrane coated with polyethylenimine (AN69ST) or a polymethylmethacrylate (PMMA) membrane is unknown. This study sought to investigate the contribution of diafiltration and adsorption to the CLCHDF of VCM using AN69ST and PMMA membranes in vitro. An in vitro CHDF circuit model was developed. The initial concentration of VCM was 50μg/mL and human serum albumin (HSA) was prepared at a concentration of 0, 2.5, or 5.0g/dL. The effluent flow rate (Qe) was set at 800, 1500, or 3000mL/h. The CLCHDF , diafiltration rate, and adsorption rate of VCM were calculated. Total CLCHDF of VCM using the AN69ST membrane increased and decreased with increasing Qe and HSA concentration, respectively. Diafiltration and adsorption rates were 82.1±9.8% and 12.1±6.1% under all conditions, respectively. Total CLCHDF using the PMMA membrane increased with increasing Qe. Diafiltration and adsorption rates were 89.2±20.4% and 4.6±17.0% under all conditions, respectively. The observed CLCHDF values significantly correlated with the predicted CLCHDF , calculated according to a previous study as the product of Qe and the plasma unbound fraction. Diafiltration predominantly contributed to CLCHDF of VCM using AN69ST and PMMA membranes. When diafiltration rather than adsorption mainly contributes to the CLCHDF of VCM, the CLCHDF could be predicted from the Qe and HSA concentration, at least in vitro.

Synthesis of polyacrylonitrile-co-sodium methallyl sulfonate copolymer (AN69) and polyacrylic acid (PAA) membranes for the removal of methylene blue from water

The scope of this work is focused on the removal of methylene blue (MB) from aqueous solution by adsorption (bach method) on polyacrylonitrile-co-sodium methallyl sulfonate copolymer (AN69) and polyacrylic acid (PAA) synthetic membranes which were prepared specifically for this purpose. Investigations have covered membrane properties and the determination of adsorption parameters. The immobilization of PAA chains into AN69 matrix was revealed by FTIR analysis, whereas the presence of small superficial microcavities was demonstrated by AFM scanning. Otherwise, the increase in PAA fraction (0 to 10%), in membrane composition, induces an increase in swelling ratio (12–22%) and ionic exchange capacity (0.8–1.2 meq/g). Moreover, the equilibrium adsorption capacity improves with the increase in alkalinity of initial adsorbate solution (pH = 2–11) and with the concentration (C = 20–80 mg/L). The results of kinetic adsorption show that the mechanism of adsorption is perfectly fitted by pseudo-second order (R2 = 0.999) and the isotherm adsorption follows the Freundlich isotherm (R2 = 0.98). From the different applied adsorption models, it was found that the maximum Langmuir adsorption capacity Qm was 116 mg/g and the Freundlich index of adsorption n was 2.2.

Thrombogenicity and long-term cytokine removal capability of a novel asymmetric triacetate membrane hemofilter

Hemofilters applied in continuous renal replacement therapies (CRRTs) for the treatment of acute kidney injury must meet high standards in biocompatibility and permeability for middle and large molecules over extended treatment times. In general, cellulose-based membranes exhibit good biocompatibility and low fouling, and thus appear to be beneficial for CRRT. In this in vitro study, we compared a novel asymmetric cellulose triacetate (ATA) membrane with three synthetic membranes [polysulfone (PS), polyethersulfone (PES), and polyethylenimine-treated acrylonitrile/sodium methallyl sulfonate copolymer (AN69 ST)] regarding thrombogenicity and cytokine removal. For thrombogenicity assessment, we analyzed the thrombin-antithrombin complex (TAT) generation in human whole blood during 5h recirculation and filtration. Sieving coefficients of interleukin-6 (IL-6), IL-8, IL-10, and tumor necrosis factor-alpha (TNF-α) were determined using human plasma as test fluid. ATA and AN69 ST membrane permeability were determined also during long-term experiments (48.5h). ATA exhibited the lowest TAT generation (6.3µg/L at 5h), while AN69 ST induced a pronounced concentration increase (152.1µg/L) and filter clogging during 4 out of 5 experiments. ATA (IL-8: 1.053; IL-6: 1.079; IL-10: 0.898; TNF-α: 0.493) and PES (0.973; 0.846; 0.468; 0.303) had the highest sieving coefficients, while PS (0.697; 0.100; 0.014; 0.012) and AN69 ST (N/A; 0.717; 0; 0.063) exhibited lower permeability. Long-term experiments revealed stronger fouling of the AN69 ST compared to the ATA membrane. We observed the highest permeability for the tested cytokines, the lowest thrombogenicity, and the lowest fouling with the ATA membrane. In CRRT, these factors may lead to increased therapy efficacy and lower incidence of coagulation-associated events.

Separation of metabolic products by electroosmotic dialysis in the plasma model

Hemodialytic membrane separation of low molecular weight solutes e.g. urea and creatinine bases on diffusion processes generated by the respective concentration gradient between dialysate and blood plasma. Electroosmotic drag of liquid through membranes offers a new transport concept for separation of metabolic products in dialysis. In this work electroosmotic drag of membranes made of textile reinforced agar, collagen, bovine pericardium, acrylonitrile/sodium methallylsulfonate copolymer as well as cation exchange membranes was studied using a five chamber electroosmotic cell in continuous operation mode. The textile reinforced agar membrane, the copolymer membrane and the bovine pericard membrane were selected for electroosmotic dialysis experiments using plasma as biological model. Vitamin B12, myoglobin, albumin and beta-2-microglobulin plasma concentrations were monitored to investigate both, membrane permeation of these markers in direction of the electroosmotic flow and possible negative effects of the electroosmotic treatment on protein stability. Transport of low molecular weight substances urea and creatinine into the recipient electrolyte was achieved without permeation of Vitamin B12 and plasma proteins. Coagulation of proteins due to the electrical field applied was not on a significant level. Monitoring of biologically relevant ions Na+, K+, Ca2+, PO43−, Cl− demonstrated that the ion movement in electroosmosis also will permit control of ion concentrations during dialysis. The transported volume of up to 14 ml Ah−1 demonstrates the potential for a significant reduction in dimensions of devices for dialysis, thus offering new aspects for miniaturisation and home dialysis.

Adsorption of Nafamostat Mesilate on AN69ST Membranes: A Single-Center Retrospective and In Vitro Study.

We examined whether AN69ST (acrylonitrile and methallyl sulfonate copolymer) membranes adsorb nafamostat mesilate. This study retrospectively analyzed 87 continuous hemodiafiltration sessions in vivo. We divided the continuous hemodiafiltration sessions into AN69ST and non-AN69ST groups using the nafamostat mesilate dose and activated clotting time as indicators of nafamostat mesilate adsorption onto the membrane. Furthermore, we studied the in vitro adsorption of nafamostat mesilate from nafamostat mesilate solutions onto four different hemodialysis membranes. This in vivo study shows that nafamostat mesilate doses were significantly higher, but activated clotting times were shorter (P < 0.001) in the AN69ST group than in the non-AN69ST group. These results suggest that AN69ST adsorbs nafamostat mesilate. Further, the in vitro experiments show that nafamostat mesilate adsorbs AN69ST on membranes significantly more than the other membranes tested. These in vitro and clinical findings provide evidence that AN69ST may adsorb nafamostat mesilate.

Trimethoprim and Sulfamethoxazole Transmembrane Clearance during Modeled Continuous Renal Replacement Therapy

Background/Aims: There is limited data regarding trimethoprim (TMP)/sulfamethoxazole (SMX) continuous renal replacement therapy (CRRT) dosing. We aimed to estimate TMP/SMX transmembrane clearance (CLtm) during continuous hemofiltration (CH) and continuous hemodialysis (CD) to guide dosing. Methods: Using an in vitro model, TMP/SMX sieving coefficients (SC) and saturation coefficients (SA) were determined with high-flux polyarylethersulfone and polyacrylonitrile-sodium methallyl sulfonate copolymer hemodiafilters at ultrafiltration/dialysate rates of 1, 2, 3, and 6 l/h. TMP/SMX CLtm was calculated using measured SC and SA. TMP/SMX CRRT doses were modeled using CLtm and published TMP/SMX pharmacokinetic parameters. Results: TMP SC/SA during CH/CD were significantly higher than SMX SC/SA. During modeling, TMP 10 mg/kg/day and its corresponding SMX dose, 50 mg/kg/day, resulted in steady state TMP/SMX peak concentrations associated with efficacy against Pneumocystis jirovecii. Conclusions: CRRT resulted in greater TMP CLtm than SMX. TMP 10 mg/kg/day divided q12h may be an appropriate initial dose to consider in patients undergoing CRRT.

Potentialities of confocal fluorescence for investigating protein adsorption on mica and in ultrafiltration membranes

In conditions of tangential flow, the confocal fluorescence technique is applied to the determination of the concentration profile of a fluorescent protein in the direction normal to a sheet of mica and to the surface of sulfonated membrane (AN69 ®; acrylonitrile–methallylsulfonate copolymer) as a function of time. The penetration of the protein inside the nanoporous membrane with its large area available for adsorption is put into evidence. In addition, by means of the time resolved fluorescence technique in the confocal configuration, we compared the photophysical properties (fluorescence lifetime and correlation time) of the adsorbed labelled protein with those of the same protein in solution: (i) the fluorescence lifetime of the labelled protein in solution (4.1 ns) was found to be unchanged (4.0 ns) when adsorbed on the membrane and significantly smaller (3.2 ns) when adsorbed on mica, suggesting on the latter surface some quenching due to protein–surface or protein–protein interactions; (ii) the correlation time determined on both surfaces, mica and membrane, was found very large (>300 ns) with respect to the value in solution (33 ns). As the labelling was performed in such a way that the rotational motion of the label corresponded to that of the protein, these results exhibited the low rotational freedom of the protein in its adsorbed state. As a summary this technique should be helpful to characterize the membrane functioning under conditions similar to those encountered in applications, by the determination of both concentration profile as a function of time and rotational mobility.

A Proteomic Analysis of Human Hemodialysis Fluid

The vascular compartment is an easily accessible compartment that provides an opportunity to measure analytes for diagnostic, prognostic, or therapeutic indications. Both serum and plasma have been analyzed extensively by proteomic approaches in an effort to catalog all proteins and polypeptides. Limitations of such approaches in obtaining a comprehensive catalog of proteins include the fact that a handful of proteins constitute over 90% of plasma protein content and that the renal glomeruli filter out proteins and polypeptides that are smaller than 66 kDa from blood. We chose to study hemodialysis fluid because it contains a higher concentration of small proteins and polypeptides and is also simultaneously depleted of the most abundant proteins present in blood. Using gel electrophoresis in combination with LC-MS/MS, we identified 292 proteins of which greater than 70% had not been previously identified from serum or plasma. More than half of the proteins identified from the hemodialysis fluid were smaller than 40 kDa. We also found 50 N-terminally acetylated peptides that allowed us to unambiguously map the N termini of mature forms of the corresponding proteins. Several identified proteins, including cytokines, were only present as predicted transcripts in data bases and thus represent novel proteins. The proteins identified in this study could serve as biomarkers in serum using more sensitive methods such as ELISA-specific antibodies.

Acrylonitrile–sodium methallylsulfonate copolymer. DSC approach to membrane porosity of foam and hollow fibers

The porosity of membranes formed from acrylonitrile–sodium methallylsulfonate copolymer was characterized from the analysis of the depression of the melting point of absorbed water. Membranes were obtained either as a foam or as a hollow fiber; the foam consisted of interconnected macrocavities (mean diameter about equal to 1 mm) while the hollow fiber was a symmetric membrane used for blood ultrafiltration. Differential scanning calorimetry (DSC) of water revealed both the Gaussian distribution of pore sizes and correspondingly, their mean size: 5.2 nm for the pores through the walls separating macrocavities in the foam and 5.6 and 10.6 nm associated with two distributions representing nearly equal amounts of absorbed water, for the hollow fiber. In addition to DSC, the water magnetic relaxation showed that the isothermal dehydration of the foam was due to the deswelling of macrocavities while the increasing amount of absorbed water in pores reflects its strong interaction with the polymer.

Efficacy and Tolerability of Angiotensin II Type 1 Receptor Antagonists in Dialysis Patients Using AN69 Dialysis Membranes

Aims and Methods: Our aim was to evaluate the antihypertensive efficacy and tolerability of angiotensin II type 1 (AT₁) receptor antagonists. Valsartan or candesartan cilexetil was administered to 11 dialysis patients with elevated blood pressure. The patients (6 male, 5 female; mean age ± SD 61±11 years) were on regular bicarbonate hemodialysis three times weekly for more than 3 months using acrylonitrile and sodium methallyl sulfonate copolymer (AN69) dialysis membranes. Results: Within 252 days after administration of the AT₁ receptor antagonists the systolic blood pressure was significantly reduced from 161±13 to 130±12 mmHg (p<0.001), whereas the diastolic blood pressure did not change significantly (76±8 vs. 71±8 mmHg; p>0.05). In addition, heart rate (75±7 vs. 80±8/min), body weight, and laboratory variables (hemoglobin, creatinine, blood urea nitrogen, serum potassium, serum sodium, serum calcium, and total protein) showed no significant changes. During 1,188 hemodialysis sessions using AN69 membranes, no hypersensitivity reactions occurred after administration of AT₁ receptor antagonists. Conclusion: The results indicate that once–daily administration of AT₁ receptor antagonists efficiently reduces the systolic blood pressure in hemodialysis patients.

NMR approach to kinetics of polymer ordering in polyacrylonitrile solutions and acrylonitrile‐sodium methallylsulfonate copolymer solutions: Solution‐concentration and polymer‐tacticity effect

AbstractPartial crystallinity of polyacrylonitrile and acrylonitrile‐sodium methallylsulfonate copolymer is detected by X‐ray diffraction in dimethyl formamide and glycerol‐dimethyl formamide solutions in the range of polymer concentration (0.14, 0.325 mol/mol). Kinetics of isothermal ordering are followed by NMR for various temperatures, polymer concentration of the solutions and polymer tacticities. The rate of polymer ordering increases upon either a decrease of the temperature, an increase of the polymer concentration or an increase of the percentage of isotactic triads. Mandelkern's model of isothermal polymer crystallisation is applied to estimate the size of critical crystalline nuclei. Assuming that crystallites growth is negligible along polymer chain axis, one can deduce the maximal size of crystallites along this axis. The size of the crystallites perpendicularly to polymer chain axis is evaluated by X‐ray diffraction. It is found to be of the order of 100 Å.

Acrylonitrile‐sodium methallylsulfonate copolymer in dimethyl sulfoxide. NMR approach to the phase diagram

AbstractThe temperature and concentration dependences of the physical state of solutions of an acrylonitrile‐sodium methallylsulfonate copolymer in dimethyl sulfoxide (DMSO) are investigated from calorimetric and NMR measurements within the temperature range where the solvent crystallization and/or polymer ordering in solution can occur. (i) For solutions of global monomeric molar fraction higher than 0.45, ordering of a fraction (&lt;0.15) of the polymer can occur. Temperatures of polymer melting and polymer ordering are reported. The composition of the liquid phase coexisting with ordered polymer is found to depend on the global concentration of the solution. At low temperatures, i.e., at temperatures for which DMSO crystallizes, three phases are found to coexist: ordered polymer, crystalline DMSO and disordered solution. (ii) For solutions of global monomeric molar fractions smaller than 0.45, the polymer is disordered at all temperatures. Crystallization of pure DMSO is observed and the melting/crystallization curve of DMSO is determined by NMR and described with simple thermodynamic considerations.

Evidence for survival and metabolic activity of encapsulated xenogeneic hepatocytes transplanted without immunosuppression in Gunn rats.

Hepatocyte transplantation could be an alternative to whole organ transplantation to correct enzymatic disorders. To this end, it would be of major importance to use xenogeneic cells without immunosuppression. The aim of this study was to investigate the survival and metabolic activity of encapsulated xenogeneic hepatocytes in the absence of immunosuppression. For this purpose, we used Gunn rats genetically incapable of bilirubin conjugation. Xenogeneic (from guinea pigs) and allogeneic (from Lewis rats) hepatocytes (2x10(7)) were isolated, macroencapsulated in hydrogel hollow fibers made with an acrylonitrile-sodium methallyl-sulfonate copolymer, and transplanted into the peritoneum of Gunn rats without any immunosuppression. Plasma bilirubin levels were evaluated weekly. Bilirubin conjugates in bile and cell morphology were studied after 5 and 12 weeks, respectively. In Gunn rats transplanted with xenogeneic hepatocytes, a significant decrease in the serum bilirubin level was observed between 3 and 9 weeks after transplantation when compared with controls transplanted with empty hollow fibers: it fell to 62% of the initial level at weeks 5-7 (P < 0.01). A comparable result was observed in Gunn rats transplanted with encapsulated allogeneic cells. Bilirubin conjugates were observed in bile samples of rats transplanted with encapsulated hepatocytes. After explantation, hollow fibers appeared intact with minimal fibrosis. Cell viability and hepatocyte morphology were preserved. These results indicate that macroencapsulated xenogeneic hepatocytes can survive and remain functional for more than 2 months when transplanted in vivo in the absence of any immunosuppression.

Acrylonitrile‐sodium methallylsulfonate copolymer solutions. NMR approach to phase diagrams and ordering processes

AbstractThe physical behavior of solutions of an acrylonitrile‐sodium methallylsulfonate copolymer in dimethyl sulfoxide is described from NMR and calorimetric observations by varying concentration, temperature and thermal history of the systems. Both the solvent and the polymer can crystallize in the studied range of temperature. A method is proposed to determine the composition of the phases present in solution. At high polymer concentration, we observe that the physical state of a given solution depends on its thermodynamic history and that three distinct phases can coexist over a large temperature interval.

Differences in the In Vitro and In Vivo 5‐Hydroxytryptamine Extraction Performance Among Three Common Microdialysis Membranes

The present study summarizes the results of an in vitro and in vivo comparison of the apparent 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid, and 3,4-dihydroxyphenylacetic acid dialysis performance of three types of membrane frequently used in intracerebral microdialysis experiments. The dialysis fiber types examined were a regenerated cellulose Cuprophan (GF), a proprietary polycarbonate ether (CMA), and a polyacrylonitrile/sodium methallylsulfonate copolymer (HOSPAL). The experiments unexpectedly revealed that the HOSPAL membrane-equipped probes displayed clearly aberrant 5-HT diffusion dynamics compared with GF and CMA probes, demonstrable not only in vitro, but also in in vivo experiments. In vitro, the GF and CMA membrane-equipped probes exhibited maximum relative recovery for 5-HT already in the first 20-min sample, whereas the 5-HT recovery of HOSPAL probes increased in a very slow and protracted manner over a period of a little less than 2 h. The GF and CMA probes further displayed an immediate washout of 5-HT when the probes were subsequently transferred to artificial CSF only-containing medium (no 5-HT), whereas approximately 2 h was required to yield near-total extinction of dialysate 5-HT with the standard HOSPAL probes. In vivo, the rat ventral hippocampal dialysate 5-HT output responses to K+ (100 mM) infusion, to Ca2+ omission, and to systemic 8-hydroxy-2-(di-n-propylamino)tetralin injection were all markedly retarded and blunted when HOSPAL instead of GF membrane-equipped probes were used. However, the 5-hydroxyindoleacetic acid and 3,4-dihydroxyphenylacetic acid extraction in vitro and in vivo were comparable using either of the membrane types.(ABSTRACT TRUNCATED AT 250 WORDS)

Preparation of a chemisorptive sulfonate fibre and its properties

Conditions have been developed for preparation of a chemisorptive fibre containing sulfonate groups from an acrylonitrile-sodium methallylsulfonate copolymer which processes satisfactorily into textile articles.

Viscosity properties of acrylonitrile-sodium methallylsulfonate copolymer solutions

To obtain structurally uniform solutions of the acrylonitrile-sodium methallylsulfonate copolymer, it is advisable to prepare them at elevated temperatures.