Cellophane Membrane Research Articles

Improvement of oral bioavailability of prednisolone by beta-cyclodextrin complexation in humans.

Inclusion complex of prednisolone with beta-cyclodextrin (beta-CyD) in 1:2 molar ratio was prepared and its dissolution, membrane permeation and oral absorption behaviors were examined. The rates of dissolution and permeation through a cellophane membrane in water were significantly increased by beta-CyD complexation. A crossover bioavailability study was performed using human subjects with lower doses of prednisolone tablets, where the plasma levels of the drug were determined by radioimmunoassay. The enhanced bioavailability of prednisolone by beta-CyD complexation suggested the possibility of smaller doses and fewer side effects in prednisolone therapy.

Formation of protein polymers in erythrocyte ghosts incubated with sonicated lipid vesicles. Effects on spectrin extractibility, permeability of ghosts to vesicles, intramembrane particle distribution and bleb formation

The incubation of human erythrocyte white ghosts with phosphatidylcholine (PC) vesicles or cholesterol/phosphatidylcholine (C/PC) vesicles under hypotonic or isotonic conditions generated membrane protein cross-links. The latter appeared in the form of a high molecular weight polymer after SDS-polyacrylamide gel electrophoresis. The polymer started to develop within a few minutes of incubation, arising largely from spectrin, and required 24 h or more for completion. It occurred regardless of cholesterol depletion undergone by the ghosts in the presence of PC vesicles. It was not reversed upon further incubation in a hypotonic, vesicle-free medium. When initial incubation was carried out under hypotonic conditions, a number of other alterations were recorded: (i) spectrin extractibility was abolished; (ii) ghosts became gradually impermeable to vesicles within a few hours, a process referred to as slow ‘resealing’ and generating an irreversible sequestration of the vesicles; (iii) intramembrane particles aggregated and blebs free of intramembrane particles pinched off inward or outward. When initial incubation was conducted under isotonic conditions, the following was observed: (i) spectrin was unextractible, as could be expected; (ii) vesicles did not enter the ghosts, a fact indicating an immediate and complete impermeabilization of ghosts to vesicles, a process referred to as fast ‘resealing’; (iii) intramembrane particle aggregation and blebs free of intramembrane particles were also present. When initial incubation was performed under isotonic conditions, but in the absence of vesicles, the polymer failed to be associated with spectrin inextractibility. These data support the view that lipid vesicles generate a high molecular weight polymer-associated, slow resealing of erythrocyte ghosts that differs, at least in part, from the polymer-free, fast resealing induced by a vesicle-free isotonic medium. Resistance to β-mercaptoethanol of the polymer makes unlikely the sole participation of disulfide bonds. Absence of added Ca 2+ in the medium is inconsistent with the transglutaminase-catalyzed formation of amide linkages. When ghosts were separated from the vesicles by a cellophane membrane upon hypotonic incubation, spectrin remained extractible and no polymer developed. Sonication of the vesicles under nitrogen and in the presence of butylated hydroxytoluene did not prevent the formation of the polymer.

A separation chamber to sort cells and cell organelles by weak physical forces: III. Preparative electrophoresis of cells in stationary density gradients at low electric field strength

An apparatus was designed for preparative density gradient electrophoresis of mammalian cells. In a low conductivity isotonic Ficoll density gradient of 1.5 cm length, human erythrocytes treated with neuraminidase were separated from untreated erythrocytes at an electric field strength of approximately 2.7 v/cm. Within 5 min two bands of erythrocytes were visible. Electrophoretic separation was completed within 25 min. The fractionation is performed in a design consisting of three Perspex circular plates, bottom and top plates of which can be displaced simultaneously relative to the stationary middle plate by a worm-gear mechanism. The middle plate contains a cylindrical separation chamber of 50 cm 2 and 1.5 cm high. Top and bottom plates contain cones and flow deflectors for the undisturbed thin layering of cell suspensions and for introduction of the density gradient. Also present in top and bottom plates are electrode compartments containing a large platinum electrode and a cellophane membrane that isolates the separation chamber hydrodynamically but not electrically from the electrode compartment. The electrode compartments were flushed with electrophoresis buffer to remove products of electrophoresis as well as the (low) generated Joule heat.

Medicament Release from Suppository Bases I: Physicochemical Characteristics and Bioavailability of Indomethacin in Rabbits

This investigation was designed to determine the in vitro release of indomethacin from suppository bases and the in vivo bioavailability in rabbits. Suppositories containing 25 mg of indomethacin were made by the fusion method with theobroma oil, esterified fatty acids (C10-C18), and polyethylene glycol 1000. To produce an exact dosage form, a formula for the determination of the displacement value was derived, and it was found that theobroma oil > esterified fatty acids (C10-C18) > polyethylene glycol 1000. The suppository hardness was determined by using appropriate apparatus and it was found that the esterified fatty acids (C10-C18) allowed the formation of more brittle suppositories. The release rates were determined with the USP dissolution apparatus, with or without cellophane membrane, and it was found that polyethylene glycol 1000 > esterified fatty acids (C10-C18) > theobroma oil. The bioavailability of indomethacin after rectal administration was greater with polyethylene glycol base. Significant correlation was obtained during the first 45 min between the in vitro release (dialyzing tubing) and the in vivo bioavailability.

Role of diffusion potential on the flow of angiotensin II, bradykinin and related molecules through cellophane membranes

The diffusion of electrically charged peptides (angiotensin II, bradykinin and [Suc 1]angiotensin II) across tight cellophane membranes, obtained by different degrees of acetylation, shows a kinetic behaviour which was interpreted in the literature as indicative of the existence of different molecular conformations presenting slow interconversion velocities and different permeabilities across the membrane. A diffusion potential (Δψ) was found to be present across the membrane along diffusion experiments performed in low ionic strength. Upon annihilation of δψ by chemical voltage clamping (by equally increasing the ionic strength on both bathing solutions) the diffusion rate was decreased and the flow followed first order kinetics, indicating a major role of Δψ in the process. As the ionic strength increase could also affect molecular conformation, the role of Δψ on the diffusion of those molecules was tested by fitting flux and Δψ experimental results by an integrated form of Nernst-Planck flux equation. It is concluded that the deviation from first order diffusion kinetics, observed in low ionic strength, is solely due to the diffusion potential, and not to the existence of more than one molecular conformation in aqueous solution. This study was extended to amino acids and other related charged molecules.

Improvements of some pharmaceutical properties of aralkylalcohols by cyclodextrin complexation

Inclusion complexations of 13 aralkylalcohols with three cyclodextrins (α-, β-, γ-CyDs) in water and in solid state were assessed by the solubility method, spectroscopies (ultraviolet (UV), circular dichroism (CD), infrared (IR), 1H-nuclear magnetic resonance (1H-NMR)), X-ray diffractometry, and thermal analyses (DTA, TG). The volatility of aralkylalcohols was significantly retarded by the formation of solid complexes, where the molar ratios (guest : host) of the complexes were generally found to be 1 : 2 and 1 : 1 for α-CyD and β-CyD systems, respectively. In the presence of CyDs, an increase in inhibitory-zone diameter of aralkylalcohols including 2, 4-dichlorobenzyl alcohol (DCBA) was observed by cup-plate method and no reduction of their antimicrobial activities was also found. The dissolution rate and permeation behavior of DCBA through a cellophane membrane were dependent upon the solubility of solid samples (DCBA alone>β-CyD complex>γ-CyD complex). The apparent release of DCBA from poorly soluble β-CyD complex was significantly improved by the addition of α-CyD into the dissolution medium. These results suggest that CyD complexation is practically useful to improve some pharmaceutical properties of aralkylalcohols without reduction of their antimicrobial activities.

Medicament Release from Suppository Bases: III. Ibuprofen - Physicochemical Characteristics and Bioavailability in Rabbits

AbstractThis investigation was designed to determine the invitro release of ibuprofen from suppository bases, and their invivo bioavailability in rabbits. Suppositories containing ibuprofen were made by the fusion method with Theobroma oil, Witepsol H-15 and PEG 1540. In order to produce an exact dosage form, the displacement value was determined. The suppository hardness was determined by utilizing the SBT (Erweka) apparatus and it was found that the Witepsol H-15 allows the formation of brittler suppositories. The release rates were determined with the USP dissolution apparatus and with cellophane membrane and it was found to be: PEG 1540 > Witepsol H-15 > Theobroma oil. The bioavail-ability of Indomethacin after rectal administration was: PEG 1540 > Witepsol H-15 > Theobroma oil which correlates with the invitro release.

Separation of liquid mixtures by using polymer membranes. III. Grafted poly(vinyl alcohol) membranes in vacuum permeation and dialysis

AbstractA series of poly(vinyl alcohol) membranes were modifed by radiation‐induced graft copolymerization with acrylic acid and methacrylic acid monomers. These grafted poly(vinyl alcohol) membranes were then tested for their separation and permeability characteristics in vacuum permeation and dialysis experiments. The permselectivity of the membranes toward methanol and water was studied on a vacuum permeation apparatus at 30, 40, and 50°C. The permeation process was found to be a temperature‐activated process. The logarithm of the permeation rate varied linearly with the reciprocal of the absolute temperature. The permeability of the grafted membranes was found to increase with the degree of grafting, with no appreciable selectivity toward water in binary mixtures. The acrylic acid‐grafted membranes generally showed greater improvement in permeability than the methacylic‐grafted membranes. The permeability of the grafted membranes toward methanol, sodium chloride, urea, creatinine, and uric acid was studied in a dialyzer. In all cases, the grafted membranes showed an improved permeability toward these solutes over the commercial poly(vinyl alcohol) membranes. The dialysis results were then compared with those obtained for dialysis‐grade cellophane membranes. For the case of sodium chloride, urea, and methanol, the permeability of the grafted membranes was comparable to that of cellophane. A comparison of commercial and grafted poly(vinyl alcohol) membranes in their permeability toward ionic solutes exhibited somewhat anomalous behavior in that the permeability of the commercial membranes was higher than that of the grafted membranes. This related to the ionic nature of the modified membrane. The permeability coefficients determined in the dialysis experiments were found to be directly related to the degree of hydration of the grafted membrane. This behavior was attributed to changes in the size and shape of voids within the membrane structure.

Investigations on nylon 4 membranes: Synthesis and transport properties. II. Transport properties of nylon 4 polymer membranes

AbstractThe reverse osmosis, ultrafiltration, and dialysis properties of nylon 4 membranes to separations of sodium chloride, urea, a series of ethylene glycols and other compounds in the aqueous phase were investigated. The nylon 4 membranes were prepared from a formic acid solution with and without organic or inorganic additives. The effects of polymer concentration, amount of additives, casting time, and temperature on the membrane performance in terms of salt separation and product rate were investigated. The tensile properties of the nylon 4 membranes in both the dry and wet states were determined. It was found that the highest salt separation of a 0.1% sodium chloride solution did not exceed 53.3%. However, these membranes showed some intersting dialysis properties which were comparable to those of commercial cellophane and cellulose acetate membranes.

Reversal of hemodialysis granulocytopenia and pulmonary leukostasis: A clinical manifestation of selective down-regulation of granulocyte responses to C5adesarg.

The transient granulocytopenia of hemodialysis results indirectly from plasma complement activation by dialyzer cellophane membranes. The C5a(desarg) so produced can induce reversible granulocyte aggregation in vitro and in vivo, and we hypothesized that the pulmonary leukostasis responsible for the granulocytopenia results from embolization of aggregates formed under the influence of C5a(desarg) produced in the dialyzer. These studies were designed to measure C5a(desarg) generation during dialysis by granulocyte aggregometry and to determine the reason for the transience of the leukostasis. C5a(desarg) generation was equally evident throughout dialysis, persisting well after granulocytopenia had reversed, and dialyzer-induced complement activation was insufficient to produce significant depletion of plasma complement titers. That granulocyte deactivation might be responsible for the transience was suggested by the absence of the usual granulocytopenia in a patient with uniquely high levels of C5a(desarg) in his predialysis plasma. Granulocytes drawn from seven stable uremic patients after granulocytopenia had reversed exhibited a dose-related, selective and irreversible refractoriness to stimulation with C5a(desarg), but their responses to n-formyl-Met-Leu-Phe remained normal. Identical deactivation was produced in normal cells by short- or long-term exposure of C5a(desarg) in vitro. These studies suggest that C5a(desarg) is indeed generated by the dialyzer throughout hemodialysis and that the transience of the leukostasis and granulocytopenia is due to selective down-regulation of cellular responses to C5a(desarg)-a phenomenon that hitherto has been described only in vitro and that may be important in limiting the deleterious effects of adherent granulocytes on the endothelium in patients with intravascular complement activation.

Human massive periretinal proliferation. In vitro characteristics of cellular components.

The sources of cellular constituents of fibrous and cellophane membranes formed in massive periretinal proliferation have been unclear. We successfully obtained cellular outgrowths from abnormal vitreous specimens collected at surgery for massive periretinal proliferation in 13 patients, using standard culture techniques. By phase-contrast and ultrastructural morphological criteria, we identified four major cellular constituents: (1) macrophages present in all specimens: (2) pigmented epithelioid cells, present in a majority of specimens; (3) glial-like cells, present in a majority of specimens; and (4) fibroblastic cells, present in all specimens but much more prominent in grossly fibrous tissues. Our findings confirm published reports of pigmented epithelioid cells and glial-like cells in fixed surgical specimens and advance our understanding of the heterogeneity of pathologic cells active in producing this serious complication of retinal reattachment surgery.

Distribution of the colicinogenic strains and the heat stability of their colicins.

Incidences of colicinogenic strains in the Escherichia coli strains isolated from various clinical materials were examined. The incidences were higher in the order in the strains isolated from pustular materials, feces, sputa and urine. Approximately 32% of the pustular strains were found to be colicino-genic. Heat stability of these colicins were examined and incidences of the heat stable colicins were found to be higher in the strains from pustular mate-rials than the strains from any other materials. Some of the colicins which retained their activity after treatment at 100°C for 30 minutes were con-centrated and tested for the cellophane membrane permeability and the re-sistance to methanol, acid and alkaline. They were all found to be permeable through cellophane membrane and resistant to all the chemicals.

β-シクロデキストリン複合体化によるフェニトインのバイオアベイラビリティの向上

The interactions of phenytoin (DPH) with α-, β-, and γ-cyclodextrins (CyD) in aqueous solution were investigated by solubility analysis, ultraviolet absorption and circular dichroism spectroscopies. The apparent stability constant of β-CyD-DPH complex was found to be the largest among the three CyD complexes. The solid complexes of β-CyD with DPH in molar ratio 1 : 1 were prepared by a variety of methods (freeze drying, kneading, solvent evaporation, and coprecipitation), and the interaction between host and guest molecules was confirmed by infrared and X-ray diffraction measurements. The pharmaceutical characteristics of the solid complexes such as dissolution, permeation through a cellophane membrane, particle size, and in vivo extent of bioavailability were examined in comparison with those of DPH alone. The complex obtained by the freeze drying method showed the smallest particle size with the highest dissolution rate and membrane permeability among the test powders. The complex increased significantly the levels of plasma concentration of DPH after oral administration to dogs. The increase of bioavailability of DPH by means of β-CyD complexation suggested the possibility of smaller doses and fewer side effects in DPH therapy.

PARTIAL CHARACTERIZATION OF CRUSTACEAN GONAD-INHIBITING HORMONE

Some properties of gonad-inhibiting hormone (GIH) from the eyestalks of male Cancer magister have been examined with normal and eyestalkless female Crangon crangon as test animals. GIH is neither sex- nor species-specific, is thermostable and is dialyzable through cellophane membranes. It has a molecular weight of about 2000.

Temperature polarization effects in thermo-osmosis

Water transport induced by heat flow across cellophane and cellulose acetate membranes has been extensively studied in recent years. In comparing the results obtained by the various authors, remarkable differences emerge among the apparent behaviour of otherwise similar membranes. Discrepancies are so large that in some cases the very existence of this transport phenomenon has been questioned. In this paper, an effect is discussed which appears significantly to affect heat-and-mass-transfer-coupled phenomena. A temperature polarization concept is used as an analogy to concentration polarization in reverse osmosis. This appears to account for most of the discrepancies in the published data. However, there remain differences in the experimental results which cannot be explained solely on the basis of “temperature polarization”. Thus, it appears necessary to perform further experimental investigations on thermo-osmosis through these membranes under well controlled thermal conditions. In this regard, a standard procedure is suggested which should allow determination of true thermo-osmotic transport coefficients, by accounting for thermal polarization effects. A physical interpretation of mass transfer across membranes induced by heat flow is also introduced. This will be further developed in subsequent papers.

Occurrence of a crinotoxin and hemagglutinin in the skin mucus of the moray eel Lycodontis nudivomer

The tropical Indo-Pacific moray eel Lycodontis nudivomer possesses a mucous skin secretion which shows hemolytic, toxic and hemagglutinating activities. The active components were extracted from the mucous secretion with 0.02 M phosphate buffer (pH 7.5) and purified by DEAE-cellulose and Sephadex G-200 column chromatography. The component(s) responsible for the hemolytic-toxic activities differ(s) from that (those) causing the hemagglutinating activity. The hemolysin was unstable in the presence of heat, acidic and alkaline media, and several organic solvents. It was undialyzable throught a cellophane membrane, and showed an absorption maxium at 280 nm in the phosphate buffer (pH 7.5). The hemolytic activity was completely lost when treated with trypsin, indicating that the hemolysin is a protein. Histochemical examination on the epidermis of L. nudivomer revealed the presence of clubbed peculiar cells, in addition to common mucous cells, which we speculate produced the hemolytic-toxic component(s). Eight other species of morays were found to possess clubbed peculiar cells similar to those of L. nudivomer in their epidermis. There are marked differences, however, in the abundance of these cells among these muraenids.

In vivo studies of dialysis-related endotoxemia and bacteremia.

The transfer of bacteria and endotoxin and the development of fever was monitored during hemodialysis of dogs. Bacterial and endotoxin levels in dialysis fluids exceeded those reportedly associated with pyrogenic reactions, and bacteria-free dialysate filtrates administered intravenously were shown to be pyrogenic in 2 of 2 dogs. During 18 hollow-fiber dialyses, neither bacteria nor endotoxin, as measured in the Limulus lysate assay (LLA), was detected in venous and arterial blood samples. Body temperatures did not increase during or within 1/2 h after dialysis. In experiments with parallel dialyzers, contaminated dialysate was simultaneously ultrafiltered into the second blood compartment. Ultrafiltrates were unreactive in the LLA and the absence of pyrogens was confirmed with the pyrogen test, USP, in five of five experiments. This investigation suggests that the intact cellophane membrane of the hollow-fiber dialyzer is an effective barrier to endotoxin and bacteria.

A solid-phase optoelectronic sensor for serum albumin

A simple solid-phase optoelectronic sensor for serum albumin is described. Bromocresol green covalently attached to a cellophane membrane is sandwiched between a red light emitting diode and a silicon photodiode with integral amplifier. Adsorption of serum albumin to the membrane at pH 3.8 causes a characteristic yellow to blue-green color change in the membrane and is thus monitored as a fall in the output voltage of the detector system. The response is reproducible and linear over the range 5–35 mg/ml albumin concentration. This report describes an investigation of this inexpensive and potentially reagentless albumin sensor.

The effect of ultrasound on diffusion through membranes

The effect of ultrasound and its mechanisms have been studied in the case of diffusion of electrolytes through cellophane membranes as a function of the intensity of the ultrasonic field, the concentration gradient and the irradiation time. The main cause of acceleration of diffusion with ultrasound is the appearance of acoustic microcurrents. Also taking part are: radiation pressure, gravitation, cavitation and acoustic pressure. Values of the diffusion coefficients were calculated from Fick's first law for the case of the stationary processes.

Plasma protein binding in uremia: Extraction and characterization of an inhibitor

The impairment of binding drugs and other substances to serum albumin in patients with uremia can be restored to normal or near normal levels by adsorption with charcoal or synthetic polymers at pH 3. We used a nonionic poly-styrene-divinylbenzene copolymer to treat uremic plasma at pH 3. We observed a marked improvement of binding. Subsequent elution of this resin with ethanol produced a substance that, when dried and recombined with normal plasma, caused dose-dependent impairment of phenytoin and tryptophan binding. Restoration of normal binding affinity occurred after retreatment of this abnormalized plasma with resin at pH 3. Plasma and pleural fluid exudate from patients with uremia yielded, after extraction by the above technique, and inhibitor(s) of phenytoin binding in amounts averaging five times that extracted from equal volumes of normal plasma. This inhibitor (IX) is water soluble, heat stable, and dialyzable across cellophane membranes. Unlike fatty acids, which can also interfere with binding, IX partitions primarily in the water phase in solvent partition studies but undergoes a sharp transition in th pH 4 to 5 range, suggesting the presence of carboxyl group. These findings lend further support to the hypothesis that a retained ligand(s) is responsible for impaired plasma binding associated with uremia and suggests a role for organic acids known to accumulate in renal failure.