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Search Results: 1 - 10 of 4954 matches for " Olga Samsonova "
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Low Molecular Weight pDMAEMA-block-pHEMA Block-Copolymers Synthesized via RAFT-Polymerization: Potential Non-Viral Gene Delivery Agents?
Olga Samsonova,Christian Pfeiffer,Markus Hellmund,Olivia M. Merkel,Thomas Kissel
Polymers , 2011, DOI: 10.3390/polym3020693
Abstract: The aim of this study was to investigate non-viral pDNA carriers based on diblock-copolymers consisting of poly(2-(dimethyl amino)ethyl methacrylate) (pDMAEMA) and poly(2-hydroxyethyl methacrylate) (pHEMA). Specifically the block-lengths and molecular weights were varied to determine the minimal requirements for transfection. Such vectors should allow better transfection at acceptable toxicity levels and the entire diblock-copolymer should be suitable for renal clearance. For this purpose, a library of linear poly(2-(dimethyl amino)ethyl methacrylate- block-poly(2-hydroxyl methacrylate) (pDMAEMA -block-pHEMA) copolymers was synthesized via RAFT (reversible addition-fragmentation chain transfer) polymerization in a molecular weight (Mw) range of 17–35.7 kDa and analyzed using 1H and 13C NMR (nuclear magnetic resonance), ATR (attenuated total reflectance), GPC (gel permeation chromatography) and DSC (differential scanning calorimetry). Copolymers possessing short pDMAEMA-polycation chains were 1.4–9.7 times less toxic in vitro than polyethylenimine (PEI) 25 kDa, and complexed DNA into polyplexes of 100–170 nm, favorable for cellular uptake. The DNA-binding affinity and polyplex stability against competing polyanions was comparable with PEI 25 kDa. The zeta-potential of polyplexes of pDMAEMA-grafted copolymers remained positive (+15–30 mV). In comparison with earlier reported low molecular weight homo pDMAEMA vectors, these diblock-copolymers showed enhanced transfection efficacy under in vitro conditions due to their lower cytotoxicity, efficient cellular uptake and DNA packaging. The homo pDMAEMA 115 (18.3 kDa) self-assembled with DNA into small positively charged polyplexes, but was not able to transfect cells. The grafting of 6 and 57 repeating units of pHEMA (0.8 and 7.4 kDa) to pDMAEMA 115 increased the transfection efficacy significantly, implying a crucial impact of pHEMA on vector-cell interactions. The intracellular trafficking, in vivo transfection efficacy and kinetics of low molecular weight pDMAEMA -block-pHEMA are subject of ongoing studies.
The Terpolymer Produced by Azotobacter Chroococcum 7B: Effect of Surface Properties on Cell Attachment
Anton Bonartsev, Sergey Yakovlev, Arasha Boskhomdzhiev, Irina Zharkova, Dmitrii Bagrov, Vera Myshkina, Tatiana Mahina, Elena Kharitonova, Olga Samsonova, Anton Zernov, Vsevolod Zhuikov, Yurii Efremov, Vera Voinova, Garina Bonartseva, Konstantin Shaitan
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0057200
Abstract: The copolymerization of poly(3-hydroxybutyrate) (PHB) is a promising trend in bioengineering to improve biomedical properties, e.g. biocompatibility, of this biodegradable polymer. We used strain Azotobacter chroococcum 7B, an effective producer of PHB, for biosynthesis of not only homopolymer and its main copolymer, poly(3-hydroxybutyrate-co-3-hydroxyvaler?ate)(PHB-HV), but also novel terpolymer, poly(3-hydroxybutyrate-co-3-hydroxyvaler?ate)-poly(ethyleneglycol) (PHB-HV-PEG), using sucrose as the primary carbon source and valeric acid and poly(ethylene glycol) 300 (PEG 300) as additional carbon sources. The chemical structure of PHB-HV-PEG was confirmed by 1H nuclear-magnetic resonance analysis. The physico-chemical properties (molecular weight, crystallinity, hydrophilicity, surface energy) of produced biopolymer, the protein adsorption to the terpolymer, and cell growth on biopolymer films were studied. Despite of low EG-monomers content in bacterial-origin PHB-HV-PEG polymer, the terpolymer demonstrated significant improvement in biocompatibility in vitro in contrast to PHB and PHB-HV polymers, which may be coupled with increased protein adsorption, hydrophilicity and surface roughness of PEG-containing copolymer.
Modeling of Gap Gene Expression in Drosophila Kruppel Mutants
Konstantin Kozlov,Svetlana Surkova,Ekaterina Myasnikova,John Reinitz,Maria Samsonova
PLOS Computational Biology , 2012, DOI: 10.1371/journal.pcbi.1002635
Abstract: The segmentation gene network in Drosophila embryo solves the fundamental problem of embryonic patterning: how to establish a periodic pattern of gene expression, which determines both the positions and the identities of body segments. The gap gene network constitutes the first zygotic regulatory tier in this process. Here we have applied the systems-level approach to investigate the regulatory effect of gap gene Kruppel (Kr) on segmentation gene expression. We acquired a large dataset on the expression of gap genes in Kr null mutants and demonstrated that the expression levels of these genes are significantly reduced in the second half of cycle 14A. To explain this novel biological result we applied the gene circuit method which extracts regulatory information from spatial gene expression data. Previous attempts to use this formalism to correctly and quantitatively reproduce gap gene expression in mutants for a trunk gap gene failed, therefore here we constructed a revised model and showed that it correctly reproduces the expression patterns of gap genes in Kr null mutants. We found that the remarkable alteration of gap gene expression patterns in Kr mutants can be explained by the dynamic decrease of activating effect of Cad on a target gene and exclusion of Kr gene from the complex network of gap gene interactions, that makes it possible for other interactions, in particular, between hb and gt, to come into effect. The successful modeling of the quantitative aspects of gap gene expression in mutant for the trunk gap gene Kr is a significant achievement of this work. This result also clearly indicates that the oversimplified representation of transcriptional regulation in the previous models is one of the reasons for unsuccessful attempts of mutant simulations.
Prediction of Gene Expression in Embryonic Structures of Drosophila melanogaster
Anastasia A Samsonova ,Mahesan Niranjan,Steven Russell,Alvis Brazma
PLOS Computational Biology , 2007, DOI: 10.1371/journal.pcbi.0030144
Abstract: Understanding how sets of genes are coordinately regulated in space and time to generate the diversity of cell types that characterise complex metazoans is a major challenge in modern biology. The use of high-throughput approaches, such as large-scale in situ hybridisation and genome-wide expression profiling via DNA microarrays, is beginning to provide insights into the complexities of development. However, in many organisms the collection and annotation of comprehensive in situ localisation data is a difficult and time-consuming task. Here, we present a widely applicable computational approach, integrating developmental time-course microarray data with annotated in situ hybridisation studies, that facilitates the de novo prediction of tissue-specific expression for genes that have no in vivo gene expression localisation data available. Using a classification approach, trained with data from microarray and in situ hybridisation studies of gene expression during Drosophila embryonic development, we made a set of predictions on the tissue-specific expression of Drosophila genes that have not been systematically characterised by in situ hybridisation experiments. The reliability of our predictions is confirmed by literature-derived annotations in FlyBase, by overrepresentation of Gene Ontology biological process annotations, and, in a selected set, by detailed gene-specific studies from the literature. Our novel organism-independent method will be of considerable utility in enriching the annotation of gene function and expression in complex multicellular organisms.
A regression system for estimation of errors introduced by confocal imaging into gene expression data in situ
Ekaterina Myasnikova, Svetlana Surkova, Grigory Stein, Andrei Pisarev, Maria Samsonova
BMC Bioinformatics , 2011, DOI: 10.1186/1471-2105-12-320
Abstract: To predict error size in the data extracted from the averaged image we developed a regression system. The system is trained on the learning sample composed of images obtained from three different microscopes at different combinations of PMT parameters, and for each image all the scans are saved. The system demonstrates high prediction accuracy and was applied for correction of errors in the data on segmentation gene expression in Drosophila blastoderm stored in the FlyEx database (http://urchin.spbcas.ru/flyex/ webcite, http://flyex.uchicago.edu/flyex/ webcite). The prediction method is realized as a software tool CorrectPattern freely available at http://urchin.spbcas.ru/asp/2011/emm/ webcite.We created a regression system and software to predict the magnitude of errors in the data obtained from a confocal image based on information about microscope parameters used for the image acquisition. An important advantage of the developed prediction system is the possibility to accurately correct the errors in data obtained from strongly clipped images, thereby allowing to obtain images of the higher dynamical range and thus to extract more detailed quantitative information from them.Confocal scanning microscopy is a commonly used method for acquisition of high-quality digital two- and three-dimensional images of molecular biological objects. The high quality of confocal images makes it possible to extract quantitative data at a single cell resolution, the availability of which is a necessary prerequisite for successful systems biology studies. However the data accuracy is limited due to errors that arise in the course of confocal scanning. In our recent papers [1,2] we analyzed the sources of errors introduced by two-dimensional confocal imaging into the data on gene expression in situ and described algorithms for estimation and correction of these errors. For example, confocal images are inevitably contaminated by photon shot noise [3] and a common way to reduce the nois
Comments for Current Interpretation EEG Alpha Activity: A Review and Analysis  [PDF]
Olga Bazanova
Journal of Behavioral and Brain Science (JBBS) , 2012, DOI: 10.4236/jbbs.2012.22027
Abstract: Introduction: Exploring the EEG alpha oscillations generates considerable interest because there is well known its role in cognitive and psycho emotional aspects of human life. However, till now there isn’t well determined definition what is alpha activity phenomena and which indices are characterize it. Method: This article focuses on the attempt to determine EEG alpha-activity phenomena, its physical, molecular and morphological nature, to highlight its indices and their role in optimal functioning. Results: Specifically, this article examines individual alpha activity indices: 1) the individual alpha peak frequency; 2) activation magnitude measured by estimation the amount of alpha amplitude suppression in response to eyes open and individual alpha band width; 3) three alpha “autorhythmicity” indices: intra-spindle amplitude variability, spindle length and steepness. Conclusions: Throughout, the article provides a number of suggestions which alpha activity indices and in which conditions could be applied in psycho physiological investigations, what is their role in optimal functioning and what are possible directions for future research.
Legal Support of Planning in the PRC  [PDF]
Olga Kucher
Beijing Law Review (BLR) , 2013, DOI: 10.4236/blr.2013.42007
Abstract:

Looking at the Peoples Republic of China (PRC) reforms it is necessary to mention that they were not resulted from foreign experts or from other countries experience they were a result of a long term Chinese strategy. This strategy includes such aspects as economy system, social benefits national safety provided that PRC is open to international influence. This long term strategy has its main tools of planning system. With the help of such system government can control all market processes which, for sure, lead to the growth and success in economy. Alongside of such model, Chinese government before and nowadays use methods of direct and indirect regulations as well as administrative influence. It means that such government interference in market process will make state structures powerful and experienced players in this game. It is necessary to say that in the period of globalized world economy multinational corporations started influencing all processes more and more, and we need to review role of government regulation. In this work next step will be directed at legal support and identification of effective government functions which can influence and control private sector. These government functions regulation can help to create balance between state, private assets and international organization in order to have a good basis for competitive world economic position. The article has a purpose to analyze key features of Chinese planning system, distinguish peculiarities and apply to other systems. In the article following methods are used chronological development of the system starting from the beginning; dialectical method of making conclusion basing on facts; and elements of comparative analysis. Result of this article is opportunity to apply such characteristics to other countries.

Modification of Steel Surface Using the Laser Energy Olga Chudina  [PDF]
Olga Chudina
Journal of Surface Engineered Materials and Advanced Technology (JSEMAT) , 2014, DOI: 10.4236/jsemat.2014.44021
Abstract:

The article is devoted to surface hardening of steels by alloying with the use of laser energy. Two combined technologies were proposed: first—laser alloying by nitride-forming elements followed by nitriding, and secondthe local laser alloying followed by metallization in atmosphere of ammonia. It is shown that laser alloying in continuous radiation forms a layer with a homogeneous fine-grained structure with thickness of 600 microns. The subsequent nitriding increases the microhardness of the surface layer of low-carbon steels to 20,000 MPa, increases wear-resistance in a 3 - 15 times and crack resistance in a 1.5 times. Two-stage technology of metallization allows getting diffusion layer on the surface of steels with the thickness, which is 1.5 - 2 times higher than after traditional metallization. In addition, this method of surface modification can significantly reduce the temperature of diffusion metallization and reduce the processing time to 3 hours. The optimal regimes of both technologies, which provide homogeneous multiphase diffusion layers with high hardness and wear resistance, were determined.

The Significance and Role of Aesthetic Education in Schooling  [PDF]
Olga Denac
Creative Education (CE) , 2014, DOI: 10.4236/ce.2014.519190
Abstract: Every child needs planned, aesthetic education in order to influence the experiencing, feeling and enjoying of beautiful things as a counterbalance to our currently rationalized world. Since the contemporary school strives for the development of professional knowledge and skills on the basis of intellectual actions, while (at the same time) neglecting other dimensions of the child’s personality (emotions, feelings, etc.), it is one of the most important tasks of the education of children and young people to develop the ability to enjoy art and beauty, and in one’s inner and outer life to act in accordance with a sense of proportion, harmony and beauty. The purpose of the article is to highlight the significance of aesthetic education in the development of the personality as a whole, to shed light on the aims of aesthetic education, to define the aesthetic dimension of experience and to ascertain the reasons for the neglect of aesthetic education in theory and practice.
Siblings of a Child with a Serious Disease: Educational Family Guidelines for Developing the Emotional Health of This Minority Group  [PDF]
Olga Lizasoain
Open Journal of Social Sciences (JSS) , 2015, DOI: 10.4236/jss.2015.38005
Abstract: Diagnosis of a serious disease in childhood is a traumatic experience, not only for the sick child but also for those living in the same environment. The family life changes drastically, and the family members go through a period of time which is both hard and full of the unknown. Fear, confusion, anger and sadness will be the principal feelings present in each one of the family members. The sick child becomes the central focus of attention at the expense of the other children in the family, children who now take a secondary role, shifting into the background. Therefore, it is very important to offer support and give special care to these other children, not excluding them from everything that is occurring in the family. This article focuses on the feelings experienced by these group of siblings. The adaptation process when facing this difficult situation will be analyzed and educational guidelines which can help the family manage the emotional impact made by the serious disease will be offered, putting special emphasis on communication.
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