A novel method for spectrophotometric determination of pregabalin in pure form and in capsules

<p>Abstract</p> <p>Background</p> <p>Pregabalin, a γ-amino-n-butyric acid derivative, is an antiepileptic drug not yet official in any pharmacopeia and development of analytical procedures for this drug in bulk/formulation forms is a necessity. We herein, report a new, simple, extraction free, cost effective, sensitive and reproducible spectrophotometric method for the determination of the pregabalin.</p> <p>Results</p> <p>Pregabalin, as a primary amine was reacted with ninhydrin in phosphate buffer pH 7.4 to form blue violet colored chromogen which could be measured spectrophotometrically at λ_max402.6 nm. The method was validated with respect to linearity, accuracy, precision and robustness. The method showed linearity in a wide concentration range of 50-1000 μg mL^-1with good correlation coefficient (0.992). The limits of assays detection was found to be 6.0 μg mL^-1and quantitation limit was 20.0 μg mL^-1. The suggested method was applied to the determination of the drug in capsules. No interference could be observed from the additives in the capsules. The percentage recovery was found to be 100.43 ± 1.24.</p> <p>Conclusion</p> <p>The developed method was successfully validated and applied to the determination of pregabalin in bulk and pharmaceutical formulations without any interference from common excipients. Hence, this method can be potentially useful for routine laboratory analysis of pregabalin.</p

Oral fluid testing facilitates understanding of hepatitis A virus household transmission

The public health response to sporadic hepatitis A virus (HAV) infection, hepatitis A, can be complex especially when the index case is a child and no obvious source is identified. Identifying an infection source may avoid mass immunisation within schools when transmission is found to have occurred within the household. Screening of asymptomatic contacts via venepuncture can be challenging and unacceptable, as a result non-invasive methods may facilitate public health intervention. Enzyme-linked immunoassays were developed to detect HAV immunoglobulin M (IgM) and immunoglobulin G (IgG) in oral fluid (ORF). A validation panel of ORF samples from 30 confirmed acute HAV infections were all reactive for HAV IgM and IgG when tested. A panel of 40 ORF samples from persons known to have been uninfected were all unreactive. Two hundred and eighty household contacts of 72 index cases were screened by ORF to identify HAV transmission within the family and factors associated with household transmission. Almost half of households (35/72) revealed evidence of recent infection, which was significantly associated with the presence of children ⩽11 years of age (odds ratio 9.84, 95% confidence interval: 2.74–35.37). These HAV IgM and IgG immunoassays are easy to perform, rapid and sensitive and have been integrated into national guidance on the management of hepatitis A cases

Utility of certain nucleophilic aromatic substitution reactions for the assay of pregabalin in capsules

<p>Abstract</p> <p>Background</p> <p>Pregabalin (PG) is an anticonvulsant, analgesic and anxiolytic drug. A survey of the literature reveals that all the reported spectrophotometric methods are either don't offer high sensitivity, need tedious extraction procedures, recommend the measurement of absorbance in the near UV region where interference most probably occurs and/or use non specific reagent that don't offer suitable linearity range.</p> <p>Results</p> <p>Two new sensitive and simple spectrophotometric methods were developed for determination of pregabalin (PG) in capsules. Method (I) is based on the reaction of PG with 1,2-naphthoquinone-4-sulphonate sodium (NQS), yielding an orange colored product that was measured at 473 nm. Method (II) is based on the reaction of the drug with 2,4-dinitrofluorobenzene (DNFB) producing a yellow product measured at 373 nm. The different experimental parameters affecting the development and stability of the reaction product in methods (I) and (II) were carefully studied and optimized. The absorbance-concentration plots were rectilinear over the concentration ranges of 2-25 and 0.5-8 μg mL^-1for methods (I) and (II) respectively. The lower detection limits (LOD) were 0.15 and 0.13 μg mL^-1and the lower quantitation limits (LOQ) were 0.46 and 0.4 μg mL^-1for methods (I) and (II) respectively.</p> <p>Conclusion</p> <p>The developed methods were successfully applied to the analysis of the drug in its commercial capsules. The mean percentage recoveries of PG in its capsule were 99.11 ± 0.98 and 100.11 ± 1.2 (n = 3). Statistical analysis of the results revealed good agreement with those given by the comparison method. Proposals of the reaction pathways were postulated.</p

Rescue of Photoreceptor Degeneration by Curcumin in Transgenic Rats with P23H Rhodopsin Mutation

The P23H mutation in the rhodopsin gene causes rhodopsin misfolding, altered trafficking and formation of insoluble aggregates leading to photoreceptor degeneration and autosomal dominant retinitis pigmentosa (RP). There are no effective therapies to treat this condition. Compounds that enhance dissociation of protein aggregates may be of value in developing new treatments for such diseases. Anti-protein aggregating activity of curcumin has been reported earlier. In this study we present that treatment of COS-7 cells expressing mutant rhodopsin with curcumin results in dissociation of mutant protein aggregates and decreases endoplasmic reticulum stress. Furthermore we demonstrate that administration of curcumin to P23H-rhodopsin transgenic rats improves retinal morphology, physiology, gene expression and localization of rhodopsin. Our findings indicate that supplementation of curcumin improves retinal structure and function in P23H-rhodopsin transgenic rats. This data also suggest that curcumin may serve as a potential therapeutic agent in treating RP due to the P23H rhodopsin mutation and perhaps other degenerative diseases caused by protein trafficking defects

Исследование износа алмазных буровых долот. 4. Уравнение изнашивания

Разработан подход для исследования кинетики изнашивания алмазного долота в условиях бурения скважины. Модель учитывает дифференциальное уравнение для абразивного износа, зависимость коэффициента износа от температуры, радиальные и касательные контактные напряжения и зависимость скорости скольжения от радиальной координаты. Окончательные выражения получены в явном виде, позволяют определить износ долота в произвольный момент времени и анализировать различные факторы, влияющие на кинетику данного процесса.The approach for studying the kinetics of diamond drill bit wear in hole drilling conditions is developed. The model takes account of the differential equation for abrasive wear, the coefficient dependence upon temperature, radial and tangential thermoelastic stresses and sliding velocity. The final expressions are obtained in an explicit form, they enable to define the components of quasi-static thermoelastic stresses at a random point of time and to analyze the main factors influencing on kinetics of the given proces

Down-regulation of estrogen receptor-alpha and rearranged during transfection tyrosine kinase is associated with withaferin a-induced apoptosis in MCF-7 breast cancer cells

<p>Abstract</p> <p>Background</p> <p>Withaferin A (WA), a naturally occurring withanolide, induces apoptosis in both estrogen-responsive MCF-7 and estrogen-independent MDA-MB-231 breast cancer cell lines with higher sensitivity in MCF-7 cells, but the underlying mechanisms are not well defined. The purpose of this study was to determine the anti-cancer effects of WA in MCF-7 breast cancer cells and explore alterations in estrogen receptor alpha (ERα) and its associated molecules <it>in vitro </it>as novel mechanisms of WA action.</p> <p>Methods</p> <p>The effects of WA on MCF-7 viability and proliferation were evaluated by 3-(4, 5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay and trypan blue exclusion assays. Apoptosis was evaluated by Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) flow cytometry and Western blot analysis of poly (ADP-ribose) polymerase (PARP) cleavage. Cell cycle effects were analyzed by PI flow cytometry. Western blotting was also conducted to examine alterations in the expression of ERα and pathways that are associated with ERα function.</p> <p>Results</p> <p>WA resulted in growth inhibition and decreased viability in MCF-7 cells with an IC50 of 576 nM for 72 h. It also caused a dose- and time-dependent apoptosis and G2/M cell cycle arrest. WA-induced apoptosis was associated with down-regulation of ERα, REarranged during Transfection (RET) tyrosine kinase, and heat shock factor-1 (HSF1), as well as up-regulation of phosphorylated p38 mitogen-activated protein kinase (phospho-p38 MAPK), p53 and p21 protein expression. Co-treatment with protein synthesis inhibitor cycloheximide or proteasome inhibitor MG132 revealed that depletion of ERα by WA is post-translational, due to proteasome-dependent ERα degradation.</p> <p>Conclusions</p> <p>Taken together, down-regulation of ERα, RET, HSF1 and up-regulation of phospho-p38 MAPK, p53, p21 are involved in the pro-apoptotic and growth-inhibitory effects of WA in MCF-7 breast cancer cells <it>in vitro</it>. Down-regulation of ERα protein levels by WA is caused by proteasome-dependent ERα degradation.</p

Intestine-Specific, Oral Delivery of Captopril/Montmorillonite: Formulation and Release Kinetics

The intercalation of captopril (CP) into the interlayers of montmorillonite (MMT) affords an intestine-selective drug delivery system that has a captopril-loading capacity of up to ca. 14 %w/w and which exhibits near-zero-order release kinetics

Glycosylation of Erythrocyte Spectrin and Its Modification in Visceral Leishmaniasis

Using a lectin, Achatinin-H, having preferential specificity for glycoproteins with terminal 9-O-acetyl sialic acid derivatives linked in α2-6 linkages to subterminal N-acetylgalactosamine, eight distinct disease-associated 9-O-acetylated sialoglycoproteins was purified from erythrocytes of visceral leishmaniaisis (VL) patients (RBCVL). Analyses of tryptic fragments by mass spectrometry led to the identification of two high-molecular weight 9-O-acetylated sialoglycoproteins as human erythrocytic α- and β-spectrin. Total spectrin purified from erythrocytes of VL patients (spectrinVL) was reactive with Achatinin-H. Interestingly, along with two high molecular weight bands corresponding to α- and β-spectrin another low molecular weight 60 kDa band was observed. Total spectrin was also purified from normal human erythrocytes (spectrinN) and insignificant binding with Achatinin-H was demonstrated. Additionally, this 60 kDa fragment was totally absent in spectrinN. Although the presence of both N- and O-glycosylations was found both in spectrinN and spectrinVL, enhanced sialylation was predominantly induced in spectrinVL. Sialic acids accounted for approximately 1.25 kDa mass of the 60 kDa polypeptide. The demonstration of a few identified sialylated tryptic fragments of α- and β-spectrinVL confirmed the presence of terminal sialic acids. Molecular modelling studies of spectrin suggest that a sugar moiety can fit into the potential glycosylation sites. Interestingly, highly sialylated spectrinVL showed decreased binding with spectrin-depleted inside-out membrane vesicles of normal erythrocytes compared to spectrinN suggesting functional abnormality. Taken together this is the first report of glycosylated eythrocytic spectrin in normal erythrocytes and its enhanced sialylation in RBCVL. The enhanced sialylation of this cytoskeleton protein is possibly related to the fragmentation of spectrinVL as evidenced by the presence of an additional 60 kDa fragment, absent in spectrinN which possibly affects the biology of RBCVL linked to both severe distortion of erythrocyte development and impairment of erythrocyte membrane integrity and may provide an explanation for their sensitivity to hemolysis and anemia in VL patients

Gentamicin supplemented polyvinylidenfluoride mesh materials enhance tissue integration due to a transcriptionally reduced MMP-2 protein expression

<p>Abstract</p> <p>Background</p> <p>A beneficial effect of gentamicin supplemented mesh material on tissue integration is known. To further elucidate the interaction of collagen and MMP-2 in chronic foreign body reaction and to determine the significance of the MMP-2-specific regulatory element (RE-1) that is known to mediate 80% of the MMP-2 promoter activity, the spatial and temporal transcriptional regulation of the MMP-2 gene was analyzed at the cellular level.</p> <p>Methods</p> <p>A PVDF mesh material was surface modified by plasma-induced graft polymerization of acrylic acid (PVDF+PAAc). Three different gentamicin concentrations were bound to the provided active sites of the grafted mesh surfaces (2, 5 and 8 μg/mg). 75 male transgenic MMP-2/LacZ mice harbouring the LacZ reporter gene under control of MMP-2 regulatory sequence -1241/+423, excluding the RE-1 were randomized to five groups. Bilateral of the abdominal midline one of the five different meshes was implanted subcutaneously in each animal. MMP-2 gene transcription (anti-ß-galactosidase staining) and MMP-2 protein expression (anti-MMP-2 staining) were analyzed semiquantitatively by immunohistochemistry 7, 21 and 90 days after mesh implantation. The collagen type I/III ratio was analyzed by cross polarization microscopy to determine the quality of mesh integration.</p> <p>Results</p> <p>The perifilamentary ß-galactosidase expression as well as the collagen type I/III ratio increased up to the 90^thday for all mesh modifications, whereas no significant changes could be observed for MMP-2 protein expression between days 21 and 90. Both the 5 and 8 μg/mg gentamicin group showed significantly reduced levels of ß-galactosidase expression and MMP-2 positive stained cells when compared to the PVDF group on day 7, 21 and 90 respectively (5 μg/mg: p < 0.05 each; 8 μg/mg: p < 0.05 each). Though the type I/III collagen ratio increased over time for all mesh modifications significant differences to the PVDF mesh were only detected for the 8 μg/mg group at all 3 time points (p < 0.05 each).</p> <p>Conclusions</p> <p>Our current data indicate that lack of RE-1 is correlated with increased mesh induced MMP-2-gene expression for coated as well as for non-coated mesh materials. Gentamicin coating reduced MMP-2 transcription and protein expression. For the 8 μg/mg group this effect is associated with an increased type I/III collagen ratio. These findings suggest that gentamicin is beneficial for tissue integration after mesh implantation, which possibly is mediated via RE-1.</p

Fingolimod: therapeutic mechanisms and ocular adverse effects.

Fingolimod is an oral immunomodulating drug used in the management of relapsing-remitting multiple sclerosis (RRMS). We aim to review the published literature on ocular manifestations of fingolimod therapy and their possible underlying mechanisms. The therapeutic effects of fingolimod are mediated via sphingosine receptors, which are found ubiquitously in various organs, including lymphoid cells, central nervous system, cardiac myocytes, and smooth muscle cells. Fingolimod-associated macular oedema (FAME) is the most common ocular side effect but retinal haemorrhages and retinal vein occlusion can occur. The visual consequences appear to be mild and, in cases of FAME, resolution is often attained with discontinuation of therapy. However, in cases of retinal vein occlusion, discontinuation of fingolimod alone may not be sufficient and intra-vitreal therapy may be required. We also propose a pragmatic service pathway for monitoring patients on fingolimod therapy, which includes stratifying them by risk and visual acuity