Optimization of bilayer floating tablet containing metoprolol tartrate as a model drug for gastric retention

The purpose of the present study was to develop an optimized gastric floating drug delivery system (GFDDS) containing metoprolol tartrate (MT) as a model drug by the optimization technique. A 2³ factorial design was employed in formulating the GFDDS with total polymer content-to-drug ratio (X₁), polymer-to-polymer ratio (X₂), and different viscosity grades of hydroxypropyl methyl cellulose (HPMC) (X₃) as independent variables. Four dependent variables were considered: percentage of MT release at 8 hours, T_50%, diffusion coefficient, and floating time. The main effect and interaction terms were quantitatively evaluated using a mathematical model. The results indicate that X₁ and X₂ significantly affected the floating time and release properties, but the effect of different viscosity grades of HPMC (K4M and K10M) was nonsignificant. Regression analysis and numerical optimization were performed to identify the best formulation. Fickian release transport was confirmed as the release mechanism from the optimized formulation. The predicted values agreed well with the experimental values, and the results demonstrate the feasibility of the model in the development of GFDDS.     

Antimalarial and antileishmanial activities of histone deacetylase inhibitors with triazole-linked cap group

Histone deacetylase inhibitors (HDACi) are endowed with plethora of biological functions including anti-proliferative, anti-inflammatory, anti-parasitic, and cognition-enhancing activities. Parsing the structure–activity relationship (SAR) for each disease condition is vital for long-term therapeutic applications of HDACi. We report in the present study specific cap group substitution patterns and spacer-group chain lengths that enhance the antimalarial and antileishmanial activity of aryltriazolylhydroxamates-based HDACi. We identified many compounds that are several folds selectively cytotoxic to the plasmodium parasites compared to standard HDACi. Also, a few of these compounds have antileishmanial activity that rivals that of miltefosine, the only currently available oral agent against visceral leishmaniasis. The anti-parasite properties of several of these compounds tracked well with their anti-HDAC activities. The results presented here provide further evidence on the suitability of HDAC inhibition as a viable therapeutic option to curb infections caused by apicomplexan protozoans and trypanosomatids.     

Biosynthesis of dihydrochalcomycin: Characterization of a deoxyallosyltransferase (gerGTI)

Through an inactivation experiment followed by complementation, the gerGTII gene was previously characterized as a chalcosyltransferase gene involved in the biosynthesis of dihydochalcomycin. The glycosyltransferase gerGTI was identified as a deoxyallosyltransferase required for the glycosylation of D-mycinose sugar. This 6-deoxyhexose sugar was converted to mycinose, via bis-O-methylation, following attachment to the polyketide lactone during dihydrochalcomycin biosynthesis. Gene sequence alignment of gerGTI to several glycosyltransferases revealed a consensus sequence motif that appears to be characteristic of the enzymes in this sub-group of the glycosyltransferase family. To characterize its putative function, genetic disruption of gerGTI in the wild-type strain Streptomyces sp. KCTC 0041BP and in the gerGTII-deleted mutant (S. sp. ΔgerGTII), as well as complementation of gerGTII in S. sp. ΔgerGTII-GTI, were carried out, and the products were analyzed by LC/MS. S. sp. ΔgerGTII-GTI mutant produced dihydrochalconolide macrolide. S. sp. ΔgerGTI and S. sp. ΔgerGTII-GTI complementation of gerGTII yielded dihydrochalconolide without the mycinose sugar. The intermediate shows that gerGTI encodes a deoxyallosyltransferase that acts after gerGTII.     

HLA class II haplotype DRB1*04-DQB1*0301 contributes to risk of familial generalized vitiligo and early disease onset

Generalized vitiligo is a common autoimmune disorder characterized by white patches of skin and overlying hair caused by loss of pigment-forming melanocytes from involved areas. Familial clustering of vitiligo is not uncommon, and patients and their relatives are at increased risk for a specific complex of other autoimmune diseases. Compared with sporadic vitiligo, familial vitiligo is characterized by earlier disease onset and greater risk and broader repertoire of autoimmunity, suggesting a stronger genetic component, and perhaps stronger associations with specific alleles. To determine whether the major histocompatibility complex (MHC) contributes to the familial clustering of vitiligo and vitiligo-associated autoimmune/autoinflammatory diseases, we performed case-control and family-based association analyses of HLA class II-DRB1 and -DQB1 alleles and haplotypes in affected probands and their parents from 76 European-American Caucasian families with familial vitiligo. Affected probands showed a significantly increased frequency of DRB1*04-DQB1*0301 and a significantly decreased frequency of DRB1*15-DQB1*0602 compared with a large sample of reference chromosomes. Family-based association analyses confirmed these results. Probands with DRB1*04-DQB1*0301 developed vitiligo an average of 13.32 yr earlier than probands with DRB1*15-DQB1*0602. Overall, our results indicate that specific MHC-linked genetic variation contributes to risk of familial vitiligo, although HLA does not completely explain familial clustering of vitiligo-associated autoimmune/autoinflammatory diseases.     

Modelling calcium carbonate biomineralisation processes

The structure-directing influence of the organic dicarboxylates malonate, succinate, glutarate and adipate as templating species on the hydrothermal formation of CaCO(3) was investigated at different temperatures (60, 80, 90, 120, 150 and 190 degrees C) and with a range of molar ratios of [Ca(2+)]/[templating species] (20, 14.3, 10, 7.7, 5, 1, 0.5 and 0.33). In the presence of the dicarboxylates, one, two or three polymorphs of CaCO(3) - calcite, aragonite and vaterite - could be formed, depending on the reaction conditions. In addition changes in crystal morphology were observed for the CaCO(3) polymorphs depending on the concentration of the template. In contrast, synthesis under ambient conditions of temperature and pressure resulted only in calcite formation, although template-dependent morphological changes were again observed. Crystalline products were all characterized by powder X-ray patterns and SEM (Scanning Electron Microscopy) micrographs. The ambient reactions with the chelating, dinucleating carboxylato ligands H(3)heidi and H(5)hpdta produce more profound changes in calcite morphology. With H(3)heidi rounded calcite crystals with shapes similar to that of otoliths are formed and with H(5)hpdta the formation of microtrumpets of constructed from bundles of nanocrystals of calcite is observed. The possible mode of action of these ligands on calcite formation is discussed in the context of known coordination chemistry with other metal ions.     

Biodegradation of vinyl chloride and cis-dichloroethene by a Ralstonia sp. strain TRW-1

An aerobic bacterium, Ralstonia sp. strain TRW-1, that assimilates vinyl chloride (VC) or ethene (ETH) as the sole carbon source was isolated from a chloroethene-degrading enrichment culture. Phylogenetic analysis of 16S rDNA sequence of the isolate revealed almost 99% sequence similarity to Ralstonia pickettii. To our knowledge, this is the first report describing the isolation of a member of Ralstonia that can degrade VC as the growth substrate. The measured growth yield values for VC and ETH were 11.27 and 18.90 g protein/mole, respectively. The estimated half-velocity constant K _m values for VC and ETH were 9.09±2.97 and 5.73±2.96 μM, respectively. These values are almost three- to tenfold higher than for other VC-assimilating Mycobacterium sp. The strain also degrades cis-dichloroethene (cis-DCE) in mineral salts medium containing yeast-extract, beef-extract, casamino acids, or peptone. This ability of the strain TRW-1 to degrade cis-DCE in the presence of a nontoxic, water-soluble substrate is relevant to in-situ remediation of cis-DCE-contaminated aquifers.     

Activation of calpains, calpastatin and spectrin cleavage in the brain during the pathology of fatal murine cerebral malaria

Neuronal calpains appear to be activated uncontrollably by sustained elevation of cytosolic calcium levels under pathological conditions as well as neurodegenerative diseases. In the present study, we have characterized calpain activation in cytosolic extract of mice cerebral cortex and cerebellum using an experimental model of fatal murine cerebral malaria (FMCM). Pathology of FMCM resulted in the increase in activity of calpains in both cerebral cortex and cerebellum. Western blot analysis revealed an increase in the levels of mu-calpain (calpain-1) in the cytosolic fraction of infected cerebral cortex and cerebellum although a decrease in the level of m-calpain was observed in the cytosolic fraction of infected cerebellum and cerebral cortex. Calpain activation was further confirmed by monitoring the formation of calpain-specific spectrin breakdown products (SBDP). Protease-specific SBDP revealed the formation of calpain-generated 150kDa product in the infected cerebral cortex and cerebellum. The specific signature fragment of calpain activation and spectrin breakdown after Plasmodium berghei ANKA infection provide a strong evidence of the role of calpains during the cell death in cerebral cortex and cerebellum. Given the role of calpains in neurodegeneration and cell death, our results strongly suggest that calpains are important mediators of cell injury and neurological sequelae associated with FMCM.     

A Kunitz proteinase inhibitor from Archidendron ellipticum seeds: purification, characterization, and kinetic properties

Leguminous plants in the tropical rainforests are a rich source of proteinase inhibitors and this work illustrates isolation of a serine proteinase inhibitor from the seeds of Archidendron ellipticum (AeTI), inhabiting Great Nicobar Island, India. AeTI was purified to homogeneity by acetone and ammonium sulfate fractionation, and ion exchange, size exclusion and reverse phase chromatography (HPLC). SDS-PAGE of AeTI revealed that it is constituted by two polypeptide chains (alpha-chain, M(r) 15,000 and beta-chain, M(r) 5000), the molecular weight being approximately 20 kDa. N-terminal sequence showed high homology with other serine proteinase inhibitors belonging to the Mimosoideae subfamily. Both Native-PAGE as well as isoelectric focussing showed four isoinhibitors (pI values of 4.1, 4.55, 5.27 and 5.65). Inhibitory activity of AeTI remained unchanged over a wide range of temperatures (0-60 degrees C) and pH (1-10). The protein inhibited trypsin in the stoichiometric ratio of 1:1, but lacked similar stoichiometry against chymotrypsin. Also, AeTI-trypsin complex was stable to SDS unlike the SDS unstable AeTI-chymotrypsin complex. AeTI, which possessed inhibition constants (K(i)) of 2.46 x 10(-10) and 0.5 x 10(-10)M against trypsin and chymotrypsin activity, respectively, retained over 70% of inhibitory activity after being stored at -20 degrees C for more than a year. Initial studies on the insecticidal properties of AeTI indicate it to be a very potent insect anti-feedant.     

Effect of long-chain fatty acids in the culture medium on fatty acid composition of WEHI-3 and J774A.1 cells

As a first step in determining the mechanism of action of specific fatty acids on immunological function of macrophages, a comparative study of the effect of long-chain polyunsaturated fatty acids (PUFA) in the medium was conducted in two macrophage cell lines, J774A.1 and WEHI-3. The baseline fatty-acid profiles of the two cell lines differed in the % distribution of saturated (SFA) and unsaturated fatty acids (UFA). J774A.1 cells had a higher % of SFA (primarily palmitic acid) than WEHI-3 cells. Conversely, WEHI-3 cells had a higher % of UFA (primarily oleic acid) than J774A.1 cells. Neither cell line had detectable amounts of alpha-linolenic acid (ALA) or eicosapentaenoic acid (EPA). The most abundant polyunsaturated fatty acid in both cells lines was arachidonic acid (AA). The efficiency of transport of fatty acids from the medium to the macrophages by two delivery vehicles (BSA complexes and ethanolic suspensions) was compared. Overall, fatty acids were transported satisfactorily by both delivery systems. Alpha-linolenic acid and doscosahexenoic acid (DHA) were transported more efficiently by the ethanolic suspension system. Linoleic acid (LA) was taken up more completely than ALA, and DHA was taken up more completely than EPA by both cell cultures and delivery systems. A dose-response effect was demonstrated for LA, ALA, EPA and DHA in both J774A.1 and WEHI-3 cells. Addition of polyunsaturated fatty acids (PUFA) to the cell cultures modified the total lipid fatty acid composition of the cells. The presence of ALA in the culture medium resulted in a significant decrease in AA in both cell lines. The omega-3/omega-6 fatty acid ratio (omega-3/omega-6), polyunsaturated/saturated fatty acid ratio (P/S), and unsaturation index (UI) increased directly with the amount of PUFA and omega-3 fatty acid provided in the medium. The results indicate that the macrophage cell lines have similar, but not identical, fatty acid profiles that may be the result of differences in fatty acid metabolism. These distinctions could in turn produce differences in immunological function. The ethanol fatty-acid delivery system, when compared with the fatty acid-BSA complex system, is preferable for measurement of dose-response effects, because the cellular fatty acid content increased in proportion to the amount of fatty acid provided in the medium. Similar dose-response results were observed in a previous in vivo study using flaxseed, rich in ALA, as a source of PUFA.