Sodium Dextran Research Articles

Aftiphilin Regulation of Myosin Light Chain Kinase Activity Promotes Actin Dynamics and Intestinal Epithelial Barrier Function

The expression levels of aftiphilin (AFTPH) are significantly lower in inflamed colonic tissues from patients with ulcerative colitis (UC) and mice with experimental colitis. During colonic inflammation, the selective permeability of the colonic epithelium is compromised largely due to dysregulation of proteins associated with either the tight junction (TJ) complex and actomyosin contraction rings. Here, we hypothesized that inflammation-associated reduction in AFTPH levels might cause an increase in the selective permeability of the colonic epithelium. In this study, we measured the transepithelial electric resistance (TEER), sodium (Na+) ion flux and dextran permeability in polarized colonic epithelial cells after manipulation of AFTPH. Silencing of AFTPH reduced TEER, increased Na+ ion flow and dextran permeability. Examination of mRNA and protein levels of multiple TJ proteins and Na+ ion transporters suggested that AFTPH deficiency did not significantly change expression of most of these transmembrane proteins. While the gross structure of the TJs in AFTPH gene-silenced cells appeared normal, elevated levels of junctional Occludin were observed. Most notably we observed that AFTPH co-localized with myosin light chain kinase (MLCK) and attenuated cellular MLCK activity as observed by phospho- myosin light chain 2 (pMLC2) western blots. Importantly, inhibition of MLCK activity reversed the reduction of TEER in AFTPH-deficient monolayers. Lastly, examination of microvilli by transmission electron microscopy and immunofluorescence imaging of actin filament arrangement demonstrated that AFTPH deficiency also affected filament arrangement in colonic epithelial cells. Taken together, these results suggest that AFTPH regulates intestinal epithelial permeability and actin polymerization in colonic epithelium through interfering with MLCK/MLC interactions.

ENCAPSULATION OF ANTITUBERCULAR DRUGS BY BIOPOLYMERS AND POLYELECTROLYTE MULTILAYERS

The problem of drug-resistant tuberculosis treatment is complex and urgent: the standard of treatment includes the oral administration of six names of antibiotics, i.e. up to twenty tablets a day by the patient. This causes severe side effects, including those appeared due to the formation of toxic products of drug interactions in the body. Therefore, it is important that some drugs dissolve in a stomach, and others – in the intestine, which will lead to increased bioavailability, reduced dosage and toxicity. The development of targeted delivery systems for drugs with controlled release, targeted delivery and minimization of side effects are of interest. One of the promising methods is polyelectrolytic multilayers and the technology of creating such layers by a step-by-step adsorption of heterogeneously charged polyelectrolytes. The aim of this article is the microencapsulation of anti-tuberculous drugs into biopolymers coated with polyelectrolytic multilayers, and the solubility study of microcapsules at pH values simulating various parts of the gastrointestinal tract. Materials and methods . Drugs as isoniazide, pyrazinamide, moxifloxacin, and biopolymers: gellan, pectin and sodium alginate, chitosan and dextran sulfate, as well as Eudragit S are used to prepare microcapsules. The obtained microcapsules are studied by a method of scanning electron microscopy. Quantitative determination of the effectiveness of the inclusion of drugs in microcapsules was carried out using pharmacopoeial methods. Results and discussion. The inclusion efficiency rises with an increase of biopolymer concentration. The inclusion efficiency increases in the row isoniazide <pyrazinamide <moxifloxacin. The possibility of microencapsulation of anti-tuberculosis drugs of pyrazinamide, isoniazide and moxifloxacin by means of coating with polyelectrolytic multilayers is shown. At pH = 7.4, the degree of release of the drugs from microcapsules without applied multilayers for 12 hours was more than 80%, i.e. the prolongation was 12 hours. In the case of microcapsules coated with polyelectrolytic multilayers: for 12 hours – 55/50%, for 18 hours – more than 87/80%. Conclusion . The possibility of preparation of microcapsules of anti-tuberculosis drugs using biopolymers coated with polyelectrolytic layers, having a prolonged action is up to 18 hours, i1.5 times greater than that without coating.

Formulation studies on ibuprofen sodium–cationic dextran conjugate: effect on tableting and dissolution characteristics of ibuprofen

The effect of electrostatic interaction between ibuprofen sodium (IbS) and cationic diethylaminoethyl dextran (Ddex), on the tableting properties and ibuprofen release from the conjugate tablet was investigated. Ibuprofen exhibits poor flow, compaction (tableting) and dissolution behavior due to its hydrophobic structure, high cohesive, adhesive and viscoelastic properties therefore it was granulated with cationic Ddex to improve its compression and dissolution characteristics. Electrostatic interaction and hydrogen bonding between IbS and Ddex was confirmed with FT-IR and DSC results showed a stepwise endothermic solid–solid structural transformation from racemic to anhydrous forms between 120 and 175 °C which melted into liquid form at 208.15 °C. The broad and diffused DSC peaks of the conjugate granules as well as the disappearance of ibuprofen melting peak provided evidence for their highly amorphous state. It was evident that Ddex improved the flowability and densification of the granules and increased the mechanical and tensile strengths of the resulting tablets as the tensile strength increased from 0.67 ± 0.0172 to 1.90 ± 0.0038 MPa with increasing Ddex concentration. Both tapping and compression processes showed that the most prominent mechanism of densification were particle slippage, rearrangement and plastic deformation while fragmentation was minimized. Ddex retarded the extent of dissolution in general, indicating potentials for controlled release formulations. Multiple release mechanisms including diffusion; anomalous transport and super case II transport were noted. It was concluded that interaction between ibuprofen sodium and Ddex produced a novel formulation with improved flowability, tableting and dissolution characteristics with potential controlled drug release characteristics dictated by Ddex concentration.

Novel Cytotoxic Proteins of Bacillus thuringiensis Isolated from Peninsular India.

Abstract Bacillus thuringiensis (Bt) is a versatile soil born bacterium with potential insecticidal activity over a wide range of species of agriculture pests. These unusual properties are due to the crystal (Cry) inclusion proteins largely produced during the sporulation. Recent findings indicate that some non-insecticidal crystal inclusions are selectively cytotoxic to cancer cells. The toxicity is due to the induction of membrane permeability and apoptosis in susceptible cells. Recently, we have reported the cytotoxic effect of proteins extracted from three native strains of Bacillus thuringiensis from the Western Ghats of Kerala (India). Studies have shown that these potent toxins exhibit selective cytotoxicity against some human breast cancer cells including MCF-7, MDA-MB-231, ZR-75 and SKBR3. Presently, we report the cytotoxic properties of more number of Bacillus thuringiensis isolates from Peninsular India, which are already assessed for their diversity. The cytotoxic properties of isolates were primarily analysed by the amplification of DNA using specific primers designed for cytotoxic parasporal genes. The strains showing positive result were subjected to in vitro cytotoxic analysis using cancer cell lines. The crystal proteins were harvested from 72h old cultures in sporulating medium, after confirming the lysis of the cells and release of the protein. The cytotoxic proteins were isolated by aqueous biphasic (sodium dextran sulfate/polyethylene glycol) separation method and purified by various chromatographic (sephadex/nickel coated columns) and electrophoretic procedures. The molecular weight of proteins isolated from different isolates was varying and ranged from 15 to 80 kDa. The pro-protein isolated was activated and subjected in vitro cytotoxicity assay on various normal as well as breast cancer cell lines. The protein was found to have strong cytocidal activities against tumour cells and the treated cells showed remarkable morphological alterations and apoptotic cell death. Thus, a new 14 isolates were found to be cytotoxic by the study. The study revealed that the diversity of cytotoxic Cry genes in Peninsular India is perplexingly high and specific to certain cancers. Considering these results, we suggest that the receptor-mediated action of crystal proteins against tumour cells may find a new place in the therapeutic as well as diagnostic field of cancer therapy and the bacteria and its genetic potential may be utilized as versatile tools against cancer. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3143.

Separation characteristics of sodium fusidate in ultrafiltration

The aim of this study is the investigation of the separation characteristics of sodium fusidate by means of ultrafiltration. The influence of several parameters, such as feed concentration, applied transmembrane pressure, pH, ionic strength, temperature and membrane material, on the retention and flux behavior have been investigated. The experiments were performed in a thin channel module, with four different ultrafiltration membranes, in order to choose a membrane with a proper retention and good operating conditions. In addition, the influence of the hydraulic permeability of the membranes, taking into account each experiment and contact time with solutions of sodium fusidate and dextran, was also analyzed in this work. The film theory model was used to estimate the mass transfer coefficient by means of the variation velocity method. The membrane-sodium fusidate interactions were studied by measuring the water flux of the membranes and by using the finely pore model, which combines both the viscous flow and frictional models. The present study gives good insight on the interactions within membrane filtration in the downstream processing of sodium fusidate. However, the situation is often more complex in real fermentation broth, since fermentation media contain hydrophobic or surface active substances which strongly influence the performance of the membrane.

Energy Transfer between Pyrene and Proflavine Solubilized in Polymer/Surfactant Complexes

Energy transfer from excited pyrene (donor) to proflavine (acceptor) was measured in sodium dextran sulfate/dodecyltrimethylammonium bromide (DxS/DTAB), DxS/dodecyltrimethylammonium chloride (DxS/DTAC), poly(vinyl sulfate)/DTAB (PVS/DTAB), and poly(styrenesulfonate)/DTAB (PSS/DTAB) mixed solutions by monitoring both the quenching of pyrene emission and the enhancement of proflavine emission as a function of acceptor concentration at 0.1, 0.2, 0.3, 0.4, and 0.5 mmol dm-3 surfactant. A remarkably high enhancement of energy transfer was found in DxS/DTAB, DxS/DTAC, and PVS/DTAB complexes, but the energy transfer efficiency was low in PSS/DTAB complexes. The enhanced energy transfer is attributed to the presence of polymer/surfactant (P/S) aggregates which solubilize the donor and acceptor in monomeric form. The high energy transfer efficiency in the DxS and PVS systems is due to the larger aggregate sizes in these systems, related to the higher degree of cooperativity observed in the surfactant binding isotherm. Smaller aggregate sizes in the PSS/DTAB complex lead to a lower energy transfer efficiency. ET efficiences are relatively independent of the surfactant counterion, bromide or chloride, indicating the complete exclusion of the counterion from the surface of the P/S aggregate.

Opposite renal effects of a PGE1 analog and prostacyclin in humans

Renal effects of prostaglandins have been widely investigated in anesthetized animals, but in contrast only few studies have been devoted to healthy and diseased humans. Recently, both prostacyclin and a stable analog of PGE1, misoprostol, have been available for therapeutic purposes in clinical conditions associated with peripheral or renal vasoconstriction; however, the renal effects have not been defined. We have therefore studied the acute renal effects of PGI2 5 ng.kg/min intravenously and of misoprostol, a stable PGE1 analogue, 400 micrograms orally in two groups of respectively 8 and 12 healthy supine subjects on normal sodium diet using sodium, lithium, inulin, PAH and neutral dextran clearances. PGI2 induced a slight natriuretic effect, a systemic and renal vasodilation with a decrease in mean arterial pressure from 85.3 +/- 1.1 to 80.2 +/- 1.6 mm Hg (P < 0.01) and in renal vascular resistance from 94 +/- 6 to 75 +/- 5 mm Hg.min/ml (P < 0.001). GFR did not change whereas fractional clearance of dextran decreased over the 34 to 48 A radius range. Applying these changes on a hydrodynamic model of filtration of macromolecules through water-filled pores, we calculated that PGI2 decreased the glomerular transcapillary pressure gradient from 35 +/- 1 to 32 +/- 1 mm Hg (P < 0.001), decreased nonsignificantly the ultrafiltration coefficient Kf and did not affect the membrane parameters r0 and omega 0. Misoprostol had no natriuretic effect, induced slight renal vasoconstriction and moderate decrease in GFR from 124 +/- 9 to 114 +/- 10 ml/min.1.73 m2 (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Application of an improved methodology to demonstrate bacterial adherence during the menstrual cycle.

We studied bacterial adherence to uroepithelial cells of female patients in relation to the menstrual cycle. We determined the number of bacteria demonstrable on native cells and the number of adhering bacteria after incubation with E. coli. Free bacteria and uroepithelial cells with adhering bacteria were optimally separated by differential centrifugation using sodium metrizoate (9.6%) and dextran (5.6%) (Lymphoprep). Thus, contamination of the cell preparation by free (non-adhering) bacteria was avoided and results were well reproducible. A median of five bacteria/cell (range 0-19) was observed for uroepithelial cells obtained from urine of female patients. Such bacteria were mostly rods. After in vitro incubation with E. coli cultures, a median of 33 bacteria/cell (range 17-54) was counted. Our improved methodology failed to demonstrate a relationship between bacterial adhesion and the menstrual cycle.

The Influence of Aluminium Hydroxide Content, Dose Volume and the Inclusion of Saponin on the Efficacy of Inactivated Foot-and-Mouth Disease Vaccines

Summary Vaccines were prepared from the virus of foot-and-mouth disease by passaging strains of Types A, SAT 1 and SAT 2 in cultures of surviving fragments of bovine tongue epithelium: the virus was inactivated by formalin or acetylcthyleneimine, usually in the presence of aluminium hydroxide gel. In some experiments, the viral antigen was first concentrated in a 2-phase polymer system consisting of polyethylene glycol and sodium dextran. Comparative tests in guinea-pigs, cattle and sheep revealed that, in the range 5.0 to 15.0 ml., the volume of the dose generally had no effect on the immnuogenicity of the vaccine, provided that the concentration of viral antigen and aluminium hydroxide gel remained constant: reduction of the amount of gel decreased the potency of the vaccine. Using concentrated gels, vaccines were prepared which were effective in a dose of 5.0 ml. The potency of all vaccines was improved by the addition of saponin (5.0 to 10.0 mg./ dose), but care was required in the selection of saponin samples. The toxicity of saponin was decreased in the presence of aluminium hydroxide gels.

Effect of plasma osmolality on resistance to blood flow through skeletal muscle.

SummaryThe gastrocnemious-plantaris muscle group of the dog was pump-perfused at constant flow with fresh plasma from a donor dog. When the osmolality of the perfusing plasma was increased by adding sodium chloride, glucose, sucrose, mannitol, dextran, or urea, the resistance to flow through the muscle decreased. The decrease in resistance was proportional to the increase in plasma osmolality. When distilled water was added to the plasma to decrease the osmolality, the resistance to flow through the muscle increased in proportion to the decrease in osmolality. The response to most test substances persisted for at least 20 min. These data suggest a mechanism regulating blood flow in resting muscle that is sensitive to osmolar concentration differences.