Development and validation of a liquid chromatographic method for the simultaneous determination of aniracetam and its related substances in the bulk drug and a tablet formulation

Simultaneous determination of aniracetam and its related impurities (2-pyrrolidinone, p-anisic acid, 4-p-anisamidobutyric acid and (p-anisoyl)-4-methyl-2-pyrrolidinone) was accomplished in the bulk drug and in a tablet formulation using a high performance liquid chromatographic method with UV detection. Separation was achieved on a Hypersil BDS-CN column (150 mm × 4.0 mm, 5 μm) using a gradient elution program with solvent A composed of phosphate buffer (pH 4.0; 0.010 M) and solvent B of acetonitrile-phosphate buffer (pH 4.0; 0.010 M) (90:10, v/v). The flow rate of the mobile phase was 1.0 mL min⁻¹ and the total elution time, including the column re-equilibration, was approximately 20 min. The UV detection wavelength was varied appropriately among 210, 250 and 280 nm. Injection volume was 20 μL and experiments were conducted at ambient temperature. The developed method was validated in terms of system suitability, selectivity, linearity, range, precision, accuracy, limits of detection and quantification for the impurities, short term and long term stability of the analytes in the prepared solutions and robustness, following the ICH guidelines. Therefore, the proposed method was suitable for the simultaneous determination of aniracetam and its studied related impurities.     

Cellular Mechanisms of Epilepsy and Potential New Treatment Strategies

Summary: Over the last 15 years, neurobiologists have begun to unravel the cellular mechanisms that underlie epileptiform activity. Such investigations have two main objectives: (I) to develop new methods for treating, "curing" or preventing epilepsy; and (2) to learn more about the normal functioning of the human brain at the cellular/ molecular and the neurological/psychological levels by analyzing abnormal brain functioning. The electroencephalogram (EEG) spike is a marker for the hyperexcitable cortex and arises in or near an area with a high epileptogenic potential. The depolarizing shift (DS) that underlies the interictal discharge (ID) appears to be generated by a combination of excitatory synaptic currents and intrinsic voltagedependent membrane currents. The hyperpolarization that follows the DS (post-DS HP) limits ID duration, determines ID frequency, and prevents ID deterioration into seizures. The disappearance of the post-DS HP in some models is related to the onset of seizures and the spread of epileptifonn activity. During the transition to seizures , the usually self-limited ID spreads in time and anatomical space. Several processes may intervene in the pathophysioogical dysfunction. These include enhancing GABA-mediated inhibition, dampening NMDA-mediated excitability, interfering with specific Ca²⁺ currents in central neurons, and perhaps stimulating "gating" pathways.     

Reversal of P-glycoprotein-mediated multidrug resistance by Alisol B 23-acetate

Herbal drugs were screened for their activity in reversing multidrug resistance (MDR) in P-glycoprotein (P-gp) over-expressing cancer cells. Through bio-assay guided fractionation an active compound was isolated from Rhizoma Alismatis, the underground part of Alisma orientale and the chemical structure of the isolate compound was confirmed by HPLC, LC-MS and NMR as Alisol B 23-acetate (ABA). ABA restored the sensitivity of MDR cell lines HepG2-DR and K562-DR to anti-tumor agents that have different modes of action but are all P-gp substrates. It restored the activity of vinblastine, a P-gp substrate, in causing G2/M arrest in MDR cells. In a dose-dependent manner, ABA increased doxorubicin accumulation and slowed down the efflux of rhodamin-123 from MDR cells. ABA inhibited the photoaffinity labeling of P-gp by [125I]iodoarylazidoprazosin and stimulated the ATPase activity of P-gp in a concentration-dependent manner, suggesting that it could be a transporter substrate for P-gp. In addition, ABA was also a partial non-competitive inhibitor of P-gp when verapamil was used as a substrate. Our results suggest that ABA may be a potential MDR reversal agent and could serve as a lead compound in the development of novel drugs.     

Emerging themes in GABAergic synapse development

Glutamatergic synapse development has been rigorously investigated for the past two decades at both the molecular and cell biological level yet a comparable intensity of investigation into the cellular and molecular mechanisms of GABAergic synapse development has been lacking until relatively recently. This review will provide a detailed overview of the current understanding of GABAergic synapse development with a particular emphasis on assembly of synaptic components, molecular mechanisms of synaptic development, and a subset of human disorders which manifest when GABAergic synapse development is disrupted. An unexpected and emerging theme from these studies is that glutamatergic and GABAergic synapse development share a number of overlapping molecular and cell biological mechanisms that will be emphasized in this review.     

Contributors to the length-of-stay trajectory in burn-injured patients

Objectives

Burn patients have a highly variable length-of-stay (LOS) due to the complexity of the injury itself. The LOS for burn patients is estimated as one day per percent total body surface area (TBSA) burn. To focus care expectation and prognosis we aimed to identify key factors that contribute to prolonged LOS.

Bridging burn care education with modern technology,an integration with high fidelity human patient simulation

Objective

The Advanced Burn Life Support (ABLS) program is a burn-education curriculum nearly 30 years in the making, focusing on the unique challenges of the first 24 h of care after burn injury. Our team applied high fidelity human patient simulation (HFHPS) to the established ABLS curriculum. Our hypothesis was that HFHPS would be a feasible, easily replicable, and valuable adjunct to the current curriculum that would enhance learner experience.

Combining linkage and association mapping identifies RECEPTOR-LIKE PROTEIN KINASE1 as an essential Arabidopsis shoot regeneration gene

De novo shoot organogenesis (i.e., the regeneration of shoots on nonmeristematic tissue) is widely applied in plant biotechnology. However, the capacity to regenerate shoots varies highly among plant species and cultivars, and the factors underlying it are still poorly understood. Here, we evaluated the shoot regeneration capacity of 88 Arabidopsis thaliana accessions and found that the process is blocked at different stages in different accessions. We show that the variation in regeneration capacity between the Arabidopsis accessions Nok-3 and Ga-0 is determined by five quantitative trait loci (QTL): REG-1 to REG-5. Fine mapping by local association analysis identified RECEPTOR-LIKE PROTEIN KINASE1 (RPK1), an abscisic acid-related receptor, as the most likely gene underlying REG-1, which was confirmed by quantitative failure of an RPK1 mutation to complement the high and low REG-1 QTL alleles. The importance of RPK1 in regeneration was further corroborated by mutant and expression analysis. Altogether, our results show that association mapping combined with linkage mapping is a powerful method to discover important genes implicated in a biological process as complex as shoot regeneration.The capacity to regenerate in vitro adventitious shoots is of major importance for biotechnological breeding and commercial in vitro initiation and propagation of plants. Unfortunately, shoot regeneration is not always easy to achieve: among plant species, varieties, and cultivars, it is highly variable and currently unpredictable. The impact of shoot regeneration for horticulture and agriculture is illustrated by the numerous studies that assess the natural allelic variation and map quantitative trait loci (QTL) for the regeneration capacity in diverse crops, such as tomato (Solanum lycopersicum), wheat (Triticum aestivum), rice (Oryza sativa), barley (Hordeum vulgare), sunflower (Helianthus annuus), cabbage (Brassica oleracea), and potato (Solanum tuberosum) (1–12). However, it is difficult to draw general conclusions from these studies because of the low-resolution linkage maps and little detailed knowledge about gene functions in these crops.Therefore, the use of the model plant Arabidopsis thaliana is more appropriate. In a widely applied two-step regeneration procedure, root explants are first incubated on an auxin-rich callus-inducing medium (CIM) and subsequently transferred to a cytokinin-rich shoot-inducing medium (SIM) (13). Genome-wide analyses of the gene expression profiles accompanying the successive steps in the regeneration process revealed multiple key regulators and genes implicated in phytohormonal signaling during shoot regeneration (14–18). Reporter gene fusions with marker genes allowed visualization of their spatiotemporal expression patterns during regeneration, contributing to the elucidation of the function of important shoot-related genes, such as CUP SHAPED COTYLEDON1, CUP SHAPED COTYLEDON2, SHOOT MERISTEMLESS, WUSCHEL (WUS), and CLAVATA3 (14, 19–22). By means of classical forward and reverse genetics approaches, additional genes involved in shoot regeneration have been identified (23).Shoot regeneration in Arabidopsis has also been studied by QTL mapping with recombinant inbred lines (RILs) of Ler × Col (24, 25) or Ler × Cvi (26). These studies revealed multiple QTL, but thus far, no quantitative trait gene (QTG) or quantitative trait nucleotide (QTN) responsible for any of these QTL has been reported. Indeed, linkage mapping studies often fail to identify the causal gene because of their limiting mapping resolution (27).Recently, genome-wide association studies with an increased mapping resolution have received much attention for the identification of QTL in plants, particularly in Arabidopsis, as an alternative to or combined with linkage mapping approaches (28–31). Here, we aimed at identifying QTGs underlying the natural shoot regeneration variation in Arabidopsis by using linkage mapping complemented with association mapping. Furthermore, early parameters, such as callus and root formation, explant greenness, and shoot primordia development, were examined in a set of 88 Arabidopsis accessions. We calculated pairwise correlations between the different parameters and shoot formation to assess whether the early observations could predict regeneration. We phenotyped 86 RILs derived from a cross of Nok-3 and Ga-0, accessions with high- and low-regeneration abilities, respectively, and mapped five regeneration QTL. A local association mapping revealed that RECEPTOR-LIKE PROTEIN KINASE1 (RPK1) is the most likely gene underlying the major QTL REG-1, which was supported by mutant analysis and a quantitative complementation test.     

Antibody and immunoglobulin levels in aged humans

IgM and IgG type antibody titers and levels of serum IgG, IgA and IgM were determined in healthy young and aged subjects. The proportion of subjects of low antibacterial agglutinin titers progressively increased during the 7th and 8th decades of life. Anti-streptolysin-O titers were also shifted to the lower values in aged subjects, at least until the 8th decade of life, although subnormal values compared to the young control range were less frequent than in the case of IgM type antibodies. Anti-streptokinase values did not seem affected by age.In contrast to antibody levels, serum IgM was similar or slightly higher in old compared to young subjects. Evidence is presented that the proportion of 7 S IgM drops with aging. Both IgA and IgG levels increased through the 7th, 8th and 9th decades of life. Different class immunoglobulin levels seemed to be considerably correlated and a tendency to correlate was found between IgG type antibody and serum IgG levels.Complex investigations including quantitation of antibodies to extrinsic and intrinsic antigens and serum immunoglobulins are proposed to define the humoral immune status of aged subjects and to understand the causes as well as the diagnostic and prognostic significance of old age ‘imbalances’.