Derivative spectrophotometric analysis of benzophenone (as an impurity) in phenytoin

Three simple and rapid spectrophotometric methods were developed for detection and trace determination of benzophenone (the main impurity) in phenytoin bulk powder and pharmaceutical formulations. The first method, zero-crossing first derivative spectrophotometry, depends on measuring the first derivative trough values at 257.6 nm for benzophenone. The second method, zero-crossing third derivative spectrophotometry, depends on measuring the third derivative peak values at 263.2 nm. The third method, ratio first derivative spectrophotometry, depends on measuring the peak amplitudes of the first derivative of the ratio spectra (the spectra of benzophenone divided by the spectrum of 5.0 μg/mL phenytoin solution) at 272 nm. The calibration graphs were linear over the range of 1-10 μg/mL. The detection limits of the first and the third derivative methods were found to be 0.04 μg/mL and 0.11 μg/mL and the quantitation limits were 0.13 μg/mL and 0.34 μg/mL, respectively, while for the ratio derivative method, the detection limit was 0.06 μg/mL and the quantitation limit was 0.18 μg/mL. The proposed methods were applied successfully to the assay of the studied drug in phenytoin bulk powder and certain pharmaceutical preparations. The results were statistically compared to those obtained using a polarographic method and were found to be in good agreement

Characterization of Engineered Actin Binding Proteins That Control Filament Assembly and Structure

Eukaryotic cells strictly regulate the structure and assembly of their actin filament networks in response to various stimuli. The actin binding proteins that control filament assembly are therefore attractive targets for those who wish to reorganize actin filaments and reengineer the cytoskeleton. Unfortunately, the naturally occurring actin binding proteins include only a limited set of pointed-end cappers, or proteins that will block polymerization from the slow-growing end of actin filaments. Of the few that are known, most are part of large multimeric complexes that are challenging to manipulate.We describe here the use of phage display mutagenesis to generate of a new class of binding protein that can be targeted to the pointed-end of actin. These proteins, called synthetic antigen binders (sABs), are based on an antibody-like scaffold where sequence diversity is introduced into the binding loops using a novel "reduced genetic code" phage display library. We describe effective strategies to select and screen for sABs that ensure the generated sABs bind to the pointed-end surface of actin exclusively.From our set of pointed-end binders, we identify three sABs with particularly useful properties to systematically probe actin dynamics: one protein that caps the pointed end, a second that crosslinks actin filaments, and a third that severs actin filaments and promotes disassembly

Novel image–novel location object recognition task sensitive to age-related cognitive decline in nondemented elderly

Traditional tests used in the clinic to identify dementia, such as the mini-mental state examination (MMSE), are useful to identify severe cognitive impairments but might be less sensitive to detect more subtle age-related cognitive changes. Previously, the novel image–novel location (NINL) object recognition test was shown to be sensitive to detect effects of apolipoprotein E4, a risk factor for developing age-related cognitive decline and Alzheimer’s disease, in nondemented elderly. In the present longitudinal study, performance on the MMSE and the NINL tests were compared over a 4-year period. Individual NINL scores over this period were highly correlated. In addition, while MMSE scores did not change over the 4-year period, NINL scores did. In a final testing session of a subset of the participants, NINL scores correlated with logical memory and word recall lists, cognitive tasks used to detect dementia in the clinic, as well as clinical dementia rating scales. These results support that the NINL might be a valuable tool to assess age-related cognitive decline

The Expanded Kinesin-13 Repertoire of Trypanosomes Contains Only One Mitotic Kinesin Indicating Multiple Extra-Nuclear Roles

BACKGROUND: Kinesin-13 proteins have a critical role in animal cell mitosis, during which they regulate spindle microtubule dynamics through their depolymerisation activity. Much of what is known about Kinesin-13 function emanates from a relatively small sub-family of proteins containing MCAK and Kif2A/B. However, recent work on kinesins from the much more widely distributed, ancestral Kinesin-13 family, which includes human Kif24, have identified a second function in flagellum length regulation that may exist either alongside or instead of the mitotic role. METHODOLOGY/PRINCIPAL FINDINGS: The African trypanosome Trypanosoma brucei encodes 7 distinct Kinesin-13 proteins, allowing scope for extensive specialisation of roles. Here, we show that of all the trypanosomal Kinesin-13 proteins, only one is nuclear. This protein, TbKIN13-1, is present in the nucleoplasm throughout the cell cycle, but associates with the spindle during mitosis, which in trypanosomes is closed. TbKIN13-1 is necessary for the segregation of both large and mini-chromosomes in this organism and reduction in TbKIN13-1 levels mediated by RNA interference causes deflects in spindle disassembly with spindle-like structures persisting in non-mitotic cells. A second Kinesin-13 is localised to the flagellum tip, but the majority of the Kinesin-13 family members are in neither of these cellular locations. CONCLUSIONS/SIGNIFICANCE: These data show that the expanded Kinesin-13 repertoire of trypanosomes is not associated with diversification of spindle-associated roles. TbKIN13-1 is required for correct spindle function, but the extra-nuclear localisation of the remaining paralogues suggests that the biological roles of the Kinesin-13 family is wider than previously thought

Oxidative stress in pregnancy and fertility pathologies

Oxidative stress designates the state of imbalance between reactive oxygen species (ROS) production and antioxidant levels. In a healthy placenta, there is an increase in ROS production, due to formation of new tissues and inherent metabolism, but this is balanced by higher levels of antioxidants. However, this balance is lost in some situations, with a consequent increase in oxidative stress levels. Oxidative stress has been implicated in several placental disorders and pregnancy pathologies. The present review intends to summarize what is known about the relationship between oxidative stress and well-known pregnancy disorders

Genome Sequence of the Pea Aphid Acyrthosiphon pisum

Aphids are important agricultural pests and also biological models for studies of insect-plant interactions, symbiosis, virus vectoring, and the developmental causes of extreme phenotypic plasticity. Here we present the 464 Mb draft genome assembly of the pea aphid Acyrthosiphon pisum. This first published whole genome sequence of a basal hemimetabolous insect provides an outgroup to the multiple published genomes of holometabolous insects. Pea aphids are host-plant specialists, they can reproduce both sexually and asexually, and they have coevolved with an obligate bacterial symbiont. Here we highlight findings from whole genome analysis that may be related to these unusual biological features. These findings include discovery of extensive gene duplication in more than 2000 gene families as well as loss of evolutionarily conserved genes. Gene family expansions relative to other published genomes include genes involved in chromatin modification, miRNA synthesis, and sugar transport. Gene losses include genes central to the IMD immune pathway, selenoprotein utilization, purine salvage, and the entire urea cycle. The pea aphid genome reveals that only a limited number of genes have been acquired from bacteria; thus the reduced gene count of Buchnera does not reflect gene transfer to the host genome. The inventory of metabolic genes in the pea aphid genome suggests that there is extensive metabolite exchange between the aphid and Buchnera, including sharing of amino acid biosynthesis between the aphid and Buchnera. The pea aphid genome provides a foundation for post-genomic studies of fundamental biological questions and applied agricultural problems

Demographic, clinical and antibody characteristics of patients with digital ulcers in systemic sclerosis: data from the DUO Registry

OBJECTIVES: The Digital Ulcers Outcome (DUO) Registry was designed to describe the clinical and antibody characteristics, disease course and outcomes of patients with digital ulcers associated with systemic sclerosis (SSc). METHODS: The DUO Registry is a European, prospective, multicentre, observational, registry of SSc patients with ongoing digital ulcer disease, irrespective of treatment regimen. Data collected included demographics, SSc duration, SSc subset, internal organ manifestations, autoantibodies, previous and ongoing interventions and complications related to digital ulcers. RESULTS: Up to 19 November 2010 a total of 2439 patients had enrolled into the registry. Most were classified as either limited cutaneous SSc (lcSSc; 52.2%) or diffuse cutaneous SSc (dcSSc; 36.9%). Digital ulcers developed earlier in patients with dcSSc compared with lcSSc. Almost all patients (95.7%) tested positive for antinuclear antibodies, 45.2% for anti-scleroderma-70 and 43.6% for anticentromere antibodies (ACA). The first digital ulcer in the anti-scleroderma-70-positive patient cohort occurred approximately 5 years earlier than the ACA-positive patient group. CONCLUSIONS: This study provides data from a large cohort of SSc patients with a history of digital ulcers. The early occurrence and high frequency of digital ulcer complications are especially seen in patients with dcSSc and/or anti-scleroderma-70 antibodies