Optimization of acyclovir oral tablets based on gastroretention technology: factorial design analysis and physicochemical characterization studies

The purpose of this research was to prepare a floating drug delivery system of acyclovir. Floating matrix tablets of acyclovir were developed to prolong gastric residence time and increase its bioavailability. The tablets were prepared by direct compression technique, using polymers such as hydroxypropylmethylcellulose 4000, Compritol 888. Sodium bicarbonate was used as a gas-generating agent. A 32 factorial design using the Design Expert Software (version 7.1.6) was applied to optimize the drug release profile systematically. The amounts of hydroxypropylmethylcellulose 4000 (X?) and Compritol 888 (X?) were selected as independent variables and the percentage drug released in 1 (Q?), 6 (Q?), and 12 (Q??) h as dependent variables. The results of factorial design indicated that a high level of both hydroxypropylmethylcellulose 4000 (X?) and Compritol 888 (X?) favors the preparation of floating controlled-release of acyclovir tablets. Also, a good correlation was observed between predicted and actual values of the dependent variables chosen for the study. By fitting the data into zero-order, first-order, and Higuchi models, we concluded that the release followed Higuchi diffusion kinetics. Storage of the prepared formulations at 40°C/75% relative humidity for 3 months showed no significant change in drug release profiles and buoyancy of the floating tablets. We can conclude that a combination of hydroxypropylmethylcellulose 4000, Compritol 888, and sodium bicarbonate can be used to increase the gastric residence time of the dosage form up to 12?h. These floating tablets seem to be a promising gastroretentive drug delivery system.     

Photo-removal of sulfamethoxazole (SMX) by photolytic and photocatalytic processes in a batch reactor under UV-C radiation (λmax=254 nm)

In this study, photolytic and photocatalytic removal of the antibiotic sulfamethoxazole (SMX) under UVC radiation (λ=254 nm) was investigated. The light intensity distribution inside the batch photoreactor was characterized by azoxybenzene actinometry. The intensity of incident radiation was found to be a strong function of position inside the reactor. 12 mg L(-1) of SMX was completely removed within 10 min of irradiation under UVC photolysis, compared to 30 min under TiO(2) photocatalysis. COD measurement was used as an indication of the mineralization efficiency of both processes and higher COD removal with photocatalysis was shown. After 6h of reaction with photolysis and photocatalysis, 24% and 87% removal of COD was observed, respectively. Two of the intermediate photo-products were identified as sulfanilic acid and 3-amino-5-methylisoxazole by direct comparison of the HPLC chromatograms of standards to those of treated solutions. Ecotoxicity of treated and untreated solutions of SMX towards Daphnia magna was also investigated. It was found that a 3:1 ratio of sample to standard freshwater and a high initial concentration of 60 mg L(-1) of SMX were used to obtain reliable and reproducible results. The photo-products formed during photocatalytic and photolytic processes were shown to be generally more toxic than the parent compound.     

Characterization of the novel Listeria monocytogenes PCR serogrouping profile IVb-v1

The World Health Organization Collaborating Centre for Listeria (WHOCCL) has developed in 2004 a multiplex PCR assay that separates the 4 major Listeria monocytogenes serovars (1/2a, 1/2b, 1/2c, and 4b) into distinct PCR serogroups. A new PCR profile has been recently identified, constituted of amplified DNA fragments of prs, ORF2819, ORF2110 and lmo0737. Here we characterize 22 L. monocytogenes isolates of the WHOCCL collection with this PCR IVb variant 1 (IVb-v1) profile. The 22 isolates belong to the clinically predominant serovar 4b, exhibit 6 distinct pulsed-field gel electrophoresis ApaI/AscI combined profiles, and belong to 2 unrelated multilocus sequence types, indicating that the novel profile does not correspond to a recent clonal emergence. We have updated the WHOCCL serogroup-related PCR typing scheme to include this new profile.     

Eotaxin-2 activates chemotaxis-related events and release of reactive oxygen species via pertussis toxin-sensitive G proteins in human eosinophils

Eosinophils play an important role in allergic and autoimmune diseases. They are activated by distinct chemokines, leading to the immigration into the inflamed tissue, and mediate tissue damage by releasing reactive oxygen species. Recently, eotaxin was found to have the broadest spectrum of activities of all eosinophil-activating CC chemokines. In this study we investigated the effect of the novel CC chemokine, eotaxin-2, on eosinophil effector functions and compared its activity with eotaxin. Using nitrobenzoxadiazole-phallacidin staining and flow cytometry, we show that eotaxin-2 induced rapid and transient actin polymerization, a prerequisite for cell migration and modulation of the respiratory burst, in eosinophils in the same range of efficacy as observed for eotaxin. Eotaxin-2 induced the release of reactive oxygen species in a dose-dependent manner; half maximal and maximal release were found at 50 ng/ml and 500 ng/ml, respectively. Surprisingly, the efficacy of eotaxin-2 was comparable to that of eotaxin and C5a. Release of reactive oxygen species was inhibited by pertussis toxin, indicating the involvement of Gi proteins in the signaling of eotaxin-2. Moreover, the anti-CC chemokine receptor 3 (CCR3) monoclonal antibody, 7B11, was able to inhibit transient rise in the cytosolic Ca2+ concentration and the release of reactive oxygen species following stimulation with eotaxin-2. Therefore, eotaxin-2 represents a potent CC chemokine for human eosinophils activating chemotaxis-related events, such as actin polymerization, and the respiratory burst via the CCR3. Moreover, the efficacy of eotaxin-2 seems to be in the same range as that of eotaxin which might re-evaluate the recent profile of activity of CC chemokines in the activation of human eosinophils.     

Optical bistability in three-wave-mixing processes with guided waves

In this paper the response curves of an integrated Optical three-wave-mixing configuration are investigated. In contrast to degenerate four-wave-mixing (DFWM) configurations the shape of the response curves can be dynamically tuned by one of the input intensities and frequency switching is possible. For contradirectional input wave launching, optical bistability can occur. The versatility of the operational principle should permit the implementation of an opto-optical modulator, switch, limiter, or a logical device respectively within a fixed configuration.     

The N-terminal extracellular segments of the chemokine receptors CCR1 and CCR3 are determinants for MIP-1alpha and eotaxin binding, respectively, but a second domain is essential for efficient receptor activation

CCR1 and CCR3 are seven-transmembrane domain G protein-coupled receptors specific for members of the CC chemokine subgroup of leukocyte chemoattractants. Both have been implicated in the inflammatory response, and CCR3, through its expression on eosinophils, basophils, and Th2 lymphocytes, may be especially important in allergic inflammation. CCR1 and CCR3 are 54% identical in amino acid sequence and share some ligands but not others. In particular, macrophage inflammatory protein 1alpha (MIP-1alpha) is a ligand for CCR1 but not CCR3, and eotaxin is a ligand for CCR3 but not CCR1. To map ligand selectivity determinants and to guide rational antagonist design, we analyzed CCR1:CCR3 chimeric receptors. When expressed in mouse pre-B cells, chimeras in which the N-terminal extracellular segments were switched were both able to bind both MIP-1alpha and eotaxin, but in each case, binding occurred via separate sites. Nevertheless, neither MIP-1alpha nor eotaxin were effective agonists at either chimeric receptor in either calcium flux or chemotaxis assays. These data are consistent with a multi-site model for chemokine-chemokine receptor interaction in which one or more subsites determine chemokine selectivity, but others are needed for receptor activation. Agents that bind to the N-terminal segments of CCR1 and CCR3 may be useful in blocking receptor function.     

Fluctuations in self-esteem and paranoia in the context of daily life.

Studies investigating the relationship between self-esteem and paranoia have specifically focused on self-esteem level, but have neglected the dynamic aspects of self-esteem. In the present article, the authors investigated the relationship between self-esteem and paranoia in two different ways. First, 154 individuals ranging across the continuum in level of paranoia were studied with the Experience Sampling Method (a structured self-assessment diary technique) to assess the association between trait paranoia and level and fluctuation of self-esteem in daily life. Results showed that trait paranoia was associated with both lower levels and higher instability of self-esteem. Second, the temporal relationship between momentary (state) paranoia and self-esteem was investigated in the daily life of these individuals. Results showed that a decrease in self-esteem was associated with an immediate increase in paranoia. The findings indicate that paranoid individuals are not only characterized by a lower level of self-esteem but also by more fluctuations in their self-esteem and that fluctuations in self-esteem predict the degree of subsequent paranoia. These results are consistent with the hypothesis that paranoia is associated with dysfunctional strategies of self-esteem regulation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

In vivo studies on lead content of deciduous teeth superficial enamel of preschool children

The amount of lead in the superficial enamel of deciduous teeth from 4- and 5-year-old children was determined by means of an enamel biopsy followed by lead analysis by graphite furnace atomic absorption spectrometry. Children examined in this study (n=329) attended public preschools in the city of Piracicaba, SP, Brazil. The selection of preschools was based on geographical location: some were located in an industrial area of the city, whereas others were located in an area devoid of industries. The objectives of this study were (1) to test whether enamel biopsies were an appropriate method for lead content population screening in young children; (2) to verify the lead content of superficial enamel of preschool children's deciduous teeth and to compare the results obtained from children exposed to different environments; (3) to analyze how biopsy depth correlated with lead content and affected comparisons between groups. An adhesive tape with a central hole (diameter=1.6 mm) was placed on one of the upper central incisors. Five microliters of 1.6 mol l⁻¹ HCl in 70% glycerol (v/v) were applied to this area for 20 s, followed by a rinse with 5-μl ultrapurified water for 10 s. It was shown that the technique was feasible for population studies on young children. The lead concentration in enamel biopsies from the industrial area children (median: 169 ppm Pb) was significantly higher than that from the children living far from industries (118.1 ppm Pb) (P<0.0001). Analysis of the data showed that biopsies deeper than 3.9 μm gave more reliable results for comparisons between groups. To our knowledge, this study is the first to use an enamel microbiopsy to characterize a large sample of young children in vivo for lead monitoring in teeth.     

Management of the sulfur content in the gasoline transport logistics chain in a multi-product pipeline

Abstract

The authors’ objective is to manage sulfur content in gasoline over a multi-product pipeline using data derived from a correlation study. Sulfur content is analyzed by ultraviolet fluorescence or monochromatic wavelength dispersive X-ray fluorescence spectrometry in three different sampling points by three laboratories. At the same time, this study evaluates the homogeneity between laboratories/methods and if the analytical results of data vary in different sampling points of the pipeline. By means of two-way analysis of variance with interaction, the results show that there are variations along the multi-product pipeline besides differences between methods and laboratories.     

Graphitic mesoporous carbon as a support of promoted Rh catalysts for hydrogenation of carbon monoxide to ethanol

Graphitic mesoporous carbon (GMC), prepared through high-temperature graphitization of soft-templated amorphous mesoporous carbon (AMC), was used as the support for Mn, Li, and Fe triple-promoted Rh catalysts for CO hydrogenation to ethanol. The use of GMC results in C₂H₅OH selectivity and formation rate comparable to nonporous SiO₂ support along with a significant inhibition on the formation of undesired CH₄ and light hydrocarbons at the expense of appreciable amounts of CO₂ produced. The better catalytic performance of promoted-Rh/GMC than those supported on other carbon allotropes (AMC and non-porous graphitic carbon black) seems to be associated with the specific graphitic structure and mesoporosity of GMC. The surface modification of GMC by wet oxidation leads to considerable increases in C₂H₅OH selectivity and formation rate. The modified GMC as a support shows substantially greater CO₂-free selectivity for C₂H₅OH than the SiO₂.