Voltammetric Studies of the Electrochemical and Interfacial Behaviour of DNA at Charged Interfaces

A survey of the essentials of the experimental evidence assembled in systematic extended voltammetric studies of denatured and native DNA is rpresented. Applying an advanced verision of single triangle sveep voltammetry at the HMDE and by supporting measurements with various other polarographic methods, :such as phase sensitive a.c.-voltammetry, the adsrnrption parameters, the sequence of i!ll!terfacial events as a function of adsorption time and adso1rption potentia·l arid the kinetics of the electrode process have been elucidated. While for pH~ 7 in adsorbed DNA the adenine and cytosime moieties are immediately reducible in a totally irreversible electrode reaction Y•ielding a strongly adsorbed compact film of reduction products, they have to become accessible to electron and proton transfer in adsorbed native DNA in a sequence of prior deconformation steps involving opening and unwinding of the double helix under the co.nstraint exerted by the adsorption interactions and by the interfacial electric field. In a fundamental biophysicochemical sense the results enable general conclusions on the behaviour of DNA when it interacts with charged interfaces d.m the living cell

Voltammetric Studies of the Electrochemical and Interfacial Behaviour of DNA at Charged Interfaces

A survey of the essentials of the experimental evidence assembled in systematic extended voltammetric studies of denatured and native DNA is rpresented. Applying an advanced verision of single triangle sveep voltammetry at the HMDE and by supporting measurements with various other polarographic methods, :such as phase sensitive a.c.-voltammetry, the adsrnrption parameters, the sequence of i!ll!terfacial events as a function of adsorption time and adso1rption potentia·l arid the kinetics of the electrode process have been elucidated. While for pH~ 7 in adsorbed DNA the adenine and cytosime moieties are immediately reducible in a totally irreversible electrode reaction Y•ielding a strongly adsorbed compact film of reduction products, they have to become accessible to electron and proton transfer in adsorbed native DNA in a sequence of prior deconformation steps involving opening and unwinding of the double helix under the co.nstraint exerted by the adsorption interactions and by the interfacial electric field. In a fundamental biophysicochemical sense the results enable general conclusions on the behaviour of DNA when it interacts with charged interfaces d.m the living cell

Исследование кинетики процесса полимеризации 5-норборнен-2,3дикарбоксимид-n-метил ацетата

Previous family studies revealed a large number of calpain 3 (CAPN3) mutations that cause recessive forms of limb girdle muscular dystrophy (LGMD2A) with selective atrophy of the proximal limb muscles. Correlations between the nature and site of a particular mutation and its corresponding phenotype, however, can only be established from homozygous mutations, which are particularly rare in the alternatively spliced NS, IS1 and IS2 regions of CAPN3. Here we identified a sibling pair with LGMD2A-type muscular dystrophy caused by a homozygous Ser606Leu (S606L) substitution in the IS2 linker domain. Normal protein levels, unaltered myofibrillar targeting and conserved calcium-induced autocatalytic activity of the mutated protein could be demonstrated in muscle biopsies from one patient. Despite this inconspicuous modification of the IS2 linker between domains III and IV, both patients developed signs and symptoms of the disease within their second decade of life. The unexpected severity of the clinical manifestation points to the high relevance of the calpain 3-specific IS2 segment between domains III and IV. We conclude that the structural motif around the Ser606 residue represents an important functional site that may regulate the transient activation and limited proteolysis of calpain 3

Multidimensional Profiles of Health Status: An Application of the Grade of Membership Model to the World Health Survey

BACKGROUND: The World Health Organization (WHO) conducted the World Health Survey (WHS) between 2002 and 2004 in 70 countries to provide cross-population comparable data on health, health-related outcomes and risk factors. The aim of this study was to apply Grade of Membership (GoM) modelling as a means to condense extensive health information from the WHS into a set of easily understandable health profiles and to assign the degree to which an individual belongs to each profile. PRINCIPAL FINDINGS: This paper described the application of the GoM models to summarize population health status using World Health Survey data. Grade of Membership analysis is a flexible, non-parametric, multivariate method, used to calculate health profiles from WHS self-reported health state and health conditions. The WHS dataset was divided into four country economic categories based on the World Bank economic groupings (high, upper-middle, lower-middle and low income economies) for separate GoM analysis. Three main health profiles were produced for each of the four areas: I. Robust; II. Intermediate; III. Frail; moreover population health, wealth and inequalities are defined for countries in each economic area as a means to put the health results into perspective. CONCLUSIONS: These analyses have provided a robust method to better understand health profiles and the components which can help to identify healthy and non-healthy individuals. The obtained profiles have described concrete levels of health and have clearly delineated characteristics of healthy and non-healthy respondents. The GoM results provided both a useable way of summarising complex individual health information and a selection of intermediate determinants which can be targeted for interventions to improve health. As populations' age, and with limited budgets for additional costs for health care and social services, applying the GoM methods may assist with identifying higher risk profiles for decision-making and resource allocations

Multidimensional Profiles of Health Status: An Application of the Grade of Membership Model to the World Health Survey

BACKGROUND: The World Health Organization (WHO) conducted the World Health Survey (WHS) between 2002 and 2004 in 70 countries to provide cross-population comparable data on health, health-related outcomes and risk factors. The aim of this study was to apply Grade of Membership (GoM) modelling as a means to condense extensive health information from the WHS into a set of easily understandable health profiles and to assign the degree to which an individual belongs to each profile. PRINCIPAL FINDINGS: This paper described the application of the GoM models to summarize population health status using World Health Survey data. Grade of Membership analysis is a flexible, non-parametric, multivariate method, used to calculate health profiles from WHS self-reported health state and health conditions. The WHS dataset was divided into four country economic categories based on the World Bank economic groupings (high, upper-middle, lower-middle and low income economies) for separate GoM analysis. Three main health profiles were produced for each of the four areas: I. Robust; II. Intermediate; III. Frail; moreover population health, wealth and inequalities are defined for countries in each economic area as a means to put the health results into perspective. CONCLUSIONS: These analyses have provided a robust method to better understand health profiles and the components which can help to identify healthy and non-healthy individuals. The obtained profiles have described concrete levels of health and have clearly delineated characteristics of healthy and non-healthy respondents. The GoM results provided both a useable way of summarising complex individual health information and a selection of intermediate determinants which can be targeted for interventions to improve health. As populations' age, and with limited budgets for additional costs for health care and social services, applying the GoM methods may assist with identifying higher risk profiles for decision-making and resource allocations

HomozygosityMapper—an interactive approach to homozygosity mapping

Homozygosity mapping is a common method for mapping recessive traits in consanguineous families. In most studies, applications for multipoint linkage analyses are applied to determine the genomic region linked to the disease. Unfortunately, these are neither suited for very large families nor for the inclusion of tens of thousands of SNPs. Even if less than 10 000 markers are employed, such an analysis may easily last hours if not days. Here we present a web-based approach to homozygosity mapping. Our application stores marker data in a database into which users can directly upload their own SNP genotype files. Within a few minutes, the database analyses the data, detects homozygous stretches and provides an intuitive graphical interface to the results. The homozygosity in affected individuals is visualized genome-wide with the ability to zoom into single chromosomes and user-defined chromosomal regions. The software also displays the underlying genotypes in all samples. It is integrated with our candidate gene search engine, GeneDistiller, so that users can interactively determine the most promising gene. They can at any point restrict access to their data or make it public, allowing HomozygosityMapper to be used as a data repository for homozygosity-mapping studies. HomozygosityMapper is available at http://www.homozygositymapper.org/

A Loss of Function Screen of Identified Genome-Wide Association Study Loci Reveals New Genes Controlling Hematopoiesis

The formation of mature cells by blood stem cells is very well understood at the cellular level and we know many of the key transcription factors that control fate decisions. However, many upstream signalling and downstream effector processes are only partially understood. Genome wide association studies (GWAS) have been particularly useful in providing new directions to dissect these pathways. A GWAS meta-analysis identified 68 genetic loci controlling platelet size and number. Only a quarter of those genes, however, are known regulators of hematopoiesis. To determine function of the remaining genes we performed a medium-throughput genetic screen in zebrafish using antisense morpholino oligonucleotides (MOs) to knock down protein expression, followed by histological analysis of selected genes using a wide panel of different hematopoietic markers. The information generated by the initial knockdown was used to profile phenotypes and to position candidate genes hierarchically in hematopoiesis. Further analysis of brd3a revealed its essential role in differentiation but not maintenance and survival of thrombocytes. Using the from-GWAS-to-function strategy we have not only identified a series of genes that represent novel regulators of thrombopoiesis and hematopoiesis, but this work also represents, to our knowledge, the first example of a functional genetic screening strategy that is a critical step toward obtaining biologically relevant functional data from GWA study for blood cell traits

Development and Validation of an Anodic Stripping Voltammetric Method for Determination of Zn2+ Ions in Brain Microdialysate Samples

An easy, rapid, and sensitive anodic stripping voltammetric method with a controlled growth mercury drop electrode has been developed and validated for the determination of Zn2+ ions in brain microdialysate samples obtained from rats. The considered level of the zinc concentration in the dialysate was 0.5–6 ppb. In the investigated method, the stripping step was carried out by using a differential pulse potential-time voltammetric excitation signal. The optimal experimental conditions as well as the instrumental and accumulation parameters and supporting electrolyte composition were investigated. The optimized method was validated for precision, linearity, and accuracy. Mean recovery 82–110% was achieved, the precision expressed by CV not greater than 7.6% and the linearity given by correlation coefficient not lower than 0.9988. The limit of detection was 0.1 ppb. No interferences were observed. Due to high linearity, precision, and sensitivity, the developed method may be successfully applied in the determination of zinc ions in microdialysate brain samples. The results obtained for the first time demonstrate detailed characteristics of the determination of zinc in the brain microdialysate fluid by the ASV method. It may be applied in a wide range of physiological and pharmacological studies which focus on very low zinc concentration/alteration in various compartments of the organisms

CHD2 variants are a risk factor for photosensitivity in epilepsy

Photosensitivity is a heritable abnormal cortical response to flickering light, manifesting as particular electroencephalographic changes, with or without seizures. Photosensitivity is prominent in a very rare epileptic encephalopathy due to de novo CHD2 mutations, but is also seen in epileptic encephalopathies due to other gene mutations. We determined whether CHD2 variation underlies photosensitivity in common epilepsies, specific photosensitive epilepsies and individuals with photosensitivity without seizures. We studied 580 individuals with epilepsy and either photosensitive seizures or abnormal photoparoxysmal response on electroencephalography, or both, and 55 individuals with photoparoxysmal response but no seizures. We compared CHD2 sequence data to publicly available data from 34 427 individuals, not enriched for epilepsy. We investigated the role of unique variants seen only once in the entire data set. We sought CHD2 variants in 238 exomes from familial genetic generalized epilepsies, and in other public exome data sets. We identified 11 unique variants in the 580 individuals with photosensitive epilepsies and 128 unique variants in the 34 427 controls: unique CHD2 variation is over-represented in cases overall (P = 2·17 × 10−5). Among epilepsy syndromes, there was over-representation of unique CHD2 variants (3/36 cases) in the archetypal photosensitive epilepsy syndrome, eyelid myoclonia with absences (P = 3·50 × 10−4). CHD2 variation was not over-represented in photoparoxysmal response without seizures. Zebrafish larvae with chd2 knockdown were tested for photosensitivity. Chd2 knockdown markedly enhanced mild innate zebrafish larval photosensitivity. CHD2 mutation is the first identified cause of the archetypal generalized photosensitive epilepsy syndrome, eyelid myoclonia with absences. Unique CHD2 variants are also associated with photosensitivity in common epilepsies. CHD2 does not encode an ion channel, opening new avenues for research into human cortical excitability