Heparin decreases permeability of pig urinary bladder wall preliminarily enhanced by chitosan

Chitosan significantly increases the permeability of the isolated pig urinary bladder wall by causing urothelial desquamation, the extent of which depends also on the concentration of the polymer. By desquamation permeability barriers of the urothelium are removed. To gain additional insight into the mechanism by which chitosan acts an absorption enhancer into urinary bladder mucosa, we evaluated the influence of a polysaccharide heparin on the permeability of isolated pig urinary bladder wall preliminarily treated with chitosan. Moreover, we aimed to establish whether the effect of heparin depends on its concentration and on the degree of urothelial desquamation caused by chitosan. In the permeability studies performed by the use of diffusion cells, transport of a model drug, pipemidic acid, into the isolated pig urinary bladder wall was determined. Heparin did not have a significant effect on the permeability of the intact urothelium. When applied to the urinary bladder wall, whose permeability was preliminarily enhanced by 0.005% or 0.001% w/v chitosan, heparin decreased the permeation of pipemidic acid into the bladder wall to a level not significantly different from the intact tissue. However, the effect of heparin was not significant at the highest concentration of chitosan tested, where the damage to the urothelium was much more intense compared with that found at lower concentrations of the polymer. The formation of complexes between pipemidic acid and heparin cannot be excluded completely, but it seems that they are not the main reason for the decreased permeation of pipemidic acid in the presence of heparin. By application on the urothelium, damaged by chitosan, heparin is supposed to form a layer on the surface of the urothelium that prevents the transport of the model drug into the bladder wall. In this way heparin probably restores the impermeability properties of the urinary bladder wall to a degree dependent on the urothelial damage.     

Validation of a simple and rapid HPLC method for determination of metronidazole in dermatological formulations

A rapid and simple method using an isocratic high-pressure liquid chromatography (HPLC) and UV detection for the determination of metronidazole in dermatological formulations is presented. Metronidazole samples were extracted with a solution composed of 60% methanol and 40% mobile phase by a procedure that can be completed in less than 10 min. Subsequent separation and quantification was accomplished in less than 20 min using reversed-phase HPLC with isocratic elution with 0.01% trifluoroacetic acid/acetonitrile (85:15%, vol/vol). Validation experiments confirmed the precision and accuracy of the method. When applied to a commercial metronidazole cream and gel formulation, recoveries of 100.4% for cream formulations and 102.3% for gel formulations were obtained. The method should facilitate studies of the formulation compatibility of metronidazole topical formulations with agents that may improve its clinical tolerability for treatment of rosacea.     

Buccal bioadhesive delivery system of 5-fluorouracil: optimization and characterization

The objective of this work was to apply the response surface approach in the development of buccal bioadhesive tablets of 5-fluorouracil (5-FU). Experiments were performed according to a 3(2) factorial design to evaluate the effects of two polymers, Gantrez MS-955 (X(1)) and hydroxypropylmethyl cellulose (HPMC) K15M (X(2)) on the bioadhesive force, percentage drug release in 8 h (Rel(8 h)), time taken for 50% drug release (t(50%)), and diffusion coefficient (n). The effect of the two independent variables on the response variables was studied by response surface plots and contour plots generated by the Design Expert software. The compatibility between 5-FU and the tablet excipients was confirmed by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) studies. Both the polymers were found to have synergistic effect on bioadhesion but the effect of Gantrez was more pronounced. A nonlinear twisted relationship was obtained for Rel(8 h) at the intermediate and high levels of the polymers, which indicated an interaction between them at the corresponding factor levels. Kinetic treatment to the dissolution profiles revealed that the drug release ranged from Fickian to anomalous transport, which was mainly dependent on both the independent variables. The desirability function was used to optimize the response variables, and the observed responses were in agreement with the experimental values.     

Ultrasonography in dentistry

This paper reviews diagnostic applications of ultrasound to dentistry, or dental ultrasonography, beginning with pioneering work of the 1960s up through present lines of research. Clinical, in vivo applications that are of direct interest to dental practice are reviewed here, including measurements of enamel thickness and periodontal pocket depth. In vitro research that involves destructive tooth preparation or procedures, such as sound speed measurements or scanning acoustic microscopy, also are included. Although dental ultrasonography has been studied for over 40 years, most methods are not quite ready for routine clinical use, and there remains much opportunity for diagnostic ultrasonography to significantly impact the practice of dentistry.     

Wrap-bake-peel process for nanostructural transformation from beta-FeOOH nanorods to biocompatible iron oxide nanocapsules

The thermal treatment of nanostructured materials to improve their properties generally results in undesirable aggregation and sintering. Here, we report on a novel wrap-bake-peel process, which involves silica coating, heat treatment and finally the removal of the silica layer, to transform the phases and structures of nanostructured materials while preserving their nanostructural characteristics. We demonstrate, as a proof-of-concept, the fabrication of water-dispersible and biocompatible hollow iron oxide nanocapsules by applying this wrap-bake-peel process to spindle-shaped akagenite (beta-FeOOH) nanoparticles. Depending on the heat treatment conditions, hollow nanocapsules of either haematite or magnetite were produced. The synthesized water-dispersible magnetite nanocapsules were successfully used not only as a drug-delivery vehicle, but also as a T2 magnetic resonance imaging contrast agent. The current process is generally applicable, and was used to transform heterostructured FePt nanoparticles to high-temperature face-centred-tetragonal-phase FePt alloy nanocrystals.     

Synthesis of silicon nanowires and nanofin arrays using interference lithography and catalytic etching

We report results on the synthesis of silicon nanostructures that were fabricated using a combination of interference lithography and catalytic etching. With this technique, we were able to create nanostructures that are perfectly periodic over very large areas (1 cm(2) or more), where the cross-sectional shapes and the array ordering can be varied. Furthermore this technique can readily and independently control the sizes and spacings of the nanostructures down to spacings of 200 nm or less. These characteristics cannot be achieved using other known techniques.     

Magnetophoretic immunoassay of allergen-specific IgE in an enhanced magnetic field gradient

We demonstrate a novel magnetophoretic immunoassay of allergen-specific immunoglobulin E (IgE) based on the magnetophoretic deflection velocity of a microbead that is proportional to the associated magnetic nanoparticles under enhanced magnetic field gradient in a microchannel. In this detection scheme, two types of house dust mites, Dermatophagoides farinae (D. farinae) and Dermatophagoides pteronyssinus (D. pteronyssinus), were used as the model allergens. Polystyrene microbeads were conjugated with each of the mite extracts followed by incubation with serum samples. The resulting mixture was then reacted with magnetic nanoparticle-conjugated anti-human IgE for detection of allergen-specific IgE by using sandwich immuno-reactions. A ferromagnetic microstructure combined with a permanent magnet was employed to increase the magnetic field gradient ( approximately 10(4) T/m) in a microfluidic device. The magnetophoretic velocities of microbeads were measured in a microchannel under applied magnetic field, and the averaged velocity was well correlated with the concentration of allergen-specific IgE in serum. From the analysis of pooled sera obtained from 44 patients, the detection limits of the allergen-specific human IgEs for D. farinae and D. pteronyssinus were determined to be 565 (0.045 IU/mL) and 268 fM (0.021 IU/mL), respectively. These values are 1 order of magnitude lower than those by a conventional CAP system. For evaluation of reproducibility and accuracy, unknown sera were subjected to a blind test by using the developed assay system, and they were compared with the CAP system. As a result, coefficient of variance was less than 10%, and the developed method enabled a fast assay with a tiny amount of serum ( approximately 10 microL).     

Augmenting spectroscopic imaging for analyses of samples with complex surface topographies

Spectroscopic imaging has become a widely used tool for analyses of heterogeneous samples. Focal plane array detectors are incorporated into spectrometers that acquire a large number of spectra from different sample locations in parallel. This sensing technique facilitates analyses of spatial distributions of chemical information in an X-Y plane at high time resolution. In many cases, chemical reactions proceed in three spatial dimensions (X-Y-Z) and require the acquisition of spectroscopic information in an X-Y plane plus topographic (Z-dimension) information. However, capturing two-dimensional (2D, i.e., X-Y) images from three-dimensional (3D, i.e., X-Y-Z) samples inherently loses Z-dimension information. This technical note describes an augmented spectroscopic imager that gains both types of data, i.e., spatially resolved spectroscopic information and topography. For the latter purpose, a regular light pattern is generated and projected onto a sample. Due to its 3D topography, this light pattern is distorted. After extracting these distortions, the topography can be determined since the height structure is encoded in the light pattern. Because topographic probing must not affect infrared measurements, different wavelength ranges are used. Here spectroscopic information is acquired in the mid-IR while the light pattern probing the topography is generated in the visible. For relating distortions to physical height structures, the setup needs to be calibrated. For this purpose, calibration objects of known dimensions have been manufactured onto which the light pattern is projected. Determining distortions introduced by objects of known height derives a transform from distortions to topographies. Due to mechanical restrictions, the light pattern can only achieve a certain spatial resolution. In order to enhance the spatial resolution the topography is probed with, scanning the light pattern in X- and Y-direction is proposed.     

Elimination of cumulative effect of thickness errors in monochromatic monitoring of optical coating production: theory

We propose an algorithm for correcting deposition termination levels that allows elimination of the cumulative effect of errors in previously deposited layers. For the application of this algorithm at least one monitoring signal extremum should be registered during a layer deposition. We also derive a theoretical relation for the estimation of errors in layer refractive indices based on the results of on-line monitoring measurements. At least two monitoring signal extrema are required for its application.     

Removal of congo red using activated carbon and its regeneration

Activated carbon is used for the removal of colored toxic congo red dye. The effects of different operating conditions like, initial dye concentration, contact time, pH and temperature are studied for adsorption of congo red by a known amount of activated carbon (1.0g/L) under stirred batch condition. The zero point of charge of the activated carbon is found about 6.6. About 90% dye is removed for initial concentration of 50 and 100mg/L, it is about 80% at pH 7.0. Maximum adsorption (about 100%) of dye is observed at pH 2.0 for the concentration range studied here. Freundlich isotherm is found to fit the equilibrium data more adequately. Pseudo second order kinetic model explain successfully the kinetic data. The surfactant enhanced carbon regeneration (SECR) technique using both cationic and anionic surfactants is adopted for the regeneration of spent carbon by desorbing the dye. A kinetic model for dye desorption from the commercial activated carbon (CAC) is also proposed. Anionic surfactants show better performance than the cationic ones. Efficiency of dye desorption using surfactants is also compared with the desorption using pH change.