940 resultados para isolation
Protein-mediated isolation of plasmid DNA by a zinc finger-glutathione S-transferase affinity linker
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The sequence-specific affinity chromatographic isolation of plasmid DNA from crude lysates of E. coli DH5 fermentations is addressed. A zinc finger-GST fusion protein that binds a synthetic oligonucleotide cassette containing the appropriate DNA recognition sequence is described. This cassette was inserted into the Smal site of pUC19 to enable the affinity isolation of the plasmid. It is shown that zinc finger-GST fusion proteins can bind both their DNA recognition sequence and a glutathione-derivatized solid support simultaneously. Furthermore, a simple procedure for the isolation of such plasmids from clarified cell lysates is demonstrated. Cell lysates were clarified by cross-flow Dean vortex microfiltration, and the permeate was incubated with zinc finger-GST fusion protein. The resulting complex was adsorbed directly onto glutathione-Sepharose. Analysis of the glutathione-eluted complex showed that plasmid DNA had been recovered, largely free from contamination by genomic DNA or bacterial cell proteins. 2002 Wiley Periodicals, Inc.
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Workplace isolation has been recognized as a critical issue facing salespeople in field offices. Studies have recognized that field salespeople are physically and psychologically isolated, but there is little empirical research on the effects of perceived isolation on important job outcomes. One important issue that has yet to be considered is the effect of workplace isolation on trust in supervisors and coworkers. The current study uses a sample of pharmaceutical salespeople to replicate previous results pertaining to workplace isolation effects and to test an integrated model of workplace isolation, salesperson satisfaction, trust, organizational commitment, and overall job performance. The results reveal that perceptions of workplace isolation negatively affect trust in supervisors and coworkers and that the relationship between trust (in supervisors and coworkers) and organizational commitment is mediated by satisfaction with supervisors and coworkers. Further, the findings confirm previous research that indicates that organizational commitment is positively related to salesperson job performance.
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Clostridium difficile is a bacterial healthcare-associated infection, which houseflies Musca domestica may transfer due to their synanthropic nature. The aims of this thesis were to determine the ability of M. domestica to transfer C. difficile mechanically and to collect and identify flying insects in UK hospitals and classify any associated bacteria. M. domestica exposed to independent suspensions of vegetative cells and spores of C. difficile were able to mechanically transfer the bacteria on to agar for up to 4 hours following exposure. C. difficile could be recovered from fly excreta for 96hrs and was isolated from the M. domestica alimentary canal. Also confirmed was the carriage of C. difficile by M. domestica larvae, although it was not retained in the pupae or in the adults that subsequently developed. Flying insects were collected from ultra-violet light flytraps in hospitals. Flies (order Diptera) were the most commonly identified. Chironomidae were the most common flies, Calliphora vicina were the most common synanthropic fly and drain flies were surprisingly numerous and represent an emerging problem in hospitals. External washings and macerates of flying insects were prepared and inoculated onto a variety of agars and following incubation bacterial colonies identified by biochemical tests. A variety of flying insects, including synanthropic flies (e.g. M. domestica and C. vicina) collected from UK hospitals harboured pathogenic bacteria of different species. Enterobacteriaceae were the group of bacteria most commonly isolated, followed by Bacillus spp, Staphylococci, Clostridia, Streptococci and Micrococcus spp. This study highlights the potential for M. domestica to contribute to environmental persistence and spread of C. difficile in hospitals. Also illustrated is the potential for flying insects to contribute to environmental persistence and spread of other pathogenic bacteria in hospitals and therefore the need to implement pest control as part of infection control strategies.
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I. The target molecules are classified as 1-aryl 2-cyclopropyl substituted ethylene. In the ground state, these molecules have a number of conformers, which are in equilibrium through rotation about single bonds. Once excited, the conformers have fixed conformation and are no longer in equilibrium and can be distinguished by their UV-vis as well as fluorescence spectra. The synthetic strategy involves standard steps. Both 2-methylanthracene and 2-methylnaphthalene were brominated using N-bromosuccinimide to give the bromomethyl adduct, which then was reacted with triphenylphosphine to form the phosphonium salt. This was followed by the formation of the phosphorus ylide, which upon treatment with cyclopropanecarboxaldehyde gave the product.^ II. The degradation of three aliphatic haloethers: bis-(2-chloroethyl) ether, bis-(2-chloroisopropyl) ether, and bis-(2-chloroethoxy)methane and two aromatic haloethers: 4-chlorodiphenyl ether and 4-bromodiphenyl ether was studied. Product studies have been conducted on the titanium dioxide photocatalysis of these compounds including mass balance, monitoring and identifying intermediates to establish the reaction pathways to deduce a mechanism for their degradation. The extent of mineralization was determined from the measurement of halogen anion (Cl$\sp-$/Br$\sp-$) as well as total organic carbon. The relative rates of disappearance of the individual haloethers appear to be related to the hydrophobic character of the given compound. Reaction mechanisms involving hydroxyl radical are proposed to explain the observed results. ^
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The improvement of tropical tree crops using conventional breeding methods faces challenges due to the length of time involved. Thus, like most crops, there is an effort to utilize molecular genetic markers in breeding programs to select for desirable agronomic traits. Known as marker assisted breeding or marker assisted selection, genetic markers associated with a phenotype of interest are used to screen and select material reducing the time necessary to evaluate candidates. As the focus of this research was improving disease resistance in tropical trees, the usefulness of the WRKY gene superfamily was investigated as candidates for generating useful molecular genetic markers. WRKY genes encode plant-specific transcriptional factors associated with regulating plants' responses to both biotic and abiotic stress. ^ One pair of degenerate primers amplified 48 WRKY gene fragments from three taxonomically distinct, economically important, tropical tree crop species: 18 from Theobroma cacao L., 21 from Cocos nucifera L. and 9 from Persea americana Mill. Several loci from each species were polymorphic because of single nucleotide substitutions present within a putative non-coding region of the loci. Capillary array electrophoresis-single strand conformational polymorphism (CAE-SSCP) mapped four WRKY loci onto a genetic linkage map of a T. cacao F2 population segregating for resistance to witches' broom disease. Additionally, PCR primers specific for four T. cacao loci successfully amplified WRKY loci from 15 members of the Byttneriae tribe. A method was devised to allow the reliable discrimination of alleles by CAE-SSCP using only the mobility assigned to the sample peaks. Once this method was validated, the diversity of three WRKY loci was evaluated in a germplasm collection of T. cacao . One locus displayed high diversity in the collection, with at least 18 alleles detected from mobility differences of the product peaks. The number of WRKY loci available within the genome, ease of isolation by degenerate PCR, codominant segregation demonstrated in the F2 population, and usefulness for screening germplasm collections and closely related wild species demonstrates that the WRKY superfamily of genes are excellent candidates for developing a number of genetic molecular markers for breeding purposes in tropical trees. ^
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Gonadal development is an ideal model to study organogenesis because a variety of developmental processes can be studied during the differentiation of the bipotential primordium into testis or ovary. To better understand this process, Representational Difference Analysis of cDNA was used to identify genes that are differentially expressed in mouse gonads at 13.5 days post-coitus. The analysis led to the identification of three testis specific genes and a sequence that was only expressed in the ovary. The male genes identified: renin, Col9a3, and a novel gene termed tescalcin had patterns of expression that suggested a role in testis determination. ^ Studies of the tescalcin gene revealed that it is organized into eight exons and seven introns. The gene was located at 64 cM in mouse chromosome 5, where it spans approximately 35 Kb. Three mRNA variants resulting from alternative splicing of intron 5 were identified in mouse tissues. Gel mobility shift assays demonstrated that Sp1 and Sp3 from Y-1, msc-1, and MIN-6 cells nuclear extracts bind the GC-boxes within the tescalcin proximal promoter. Bisulfite sequencing analysis of tescalcin CpG island revealed that it is differentially methylated in male and female mouse embryonic gonads, and that hypermethylation of this region represses expression of tescalcin in the -TC3 cell line. ^ The major tescalcin mRNA encodes a protein with 214 amino acids that contains a consensus EF-hand Ca2+-binding domain and an N-myristoylation motif. The amino acid sequence of tescalcin is highly conserved among various species, and it showed the highest homology with calcineurin B homologous proteins 1 and 2, and calcineurin B. Western blot analysis using antibodies generated against the tescalcin protein confirmed its presence in specific mouse tissues and cell lines. Immunohistochemical analysis of mouse embryos confirmed the pattern of expression of tescalcin mRNA in fetal testis. Using pull-down assays, glyceraidehydes-3-phosphate dehydrogenase was identified as an interacting and potential functional partner of tescalcin. ^ The identification and characterization of tescalcin as a novel embryonic testicular marker will contribute to the elucidation of the genetic pathways involved in testis development and likely to the understanding of pathological conditions such as sex reversal and infertility. ^
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In isolation and characterization studies, expression level U1 and U2 snRNA isoforms were obtained from the 5th instar larval stage silk gland (SG). The DNA content of the SG cells is approximately 200,000-fold higher compared to the usual (2N) somatic cells of B. mori due to endoreduplication. In this study, the existence of U1 and U2 snRNA isoforms in the SG of the organism is investigated. Bombyx mori U1 and U2-specific RT-PCR libraries from the silk gland were generated. Five U1 and eight U2 isoforms were isolated and characterized. Nucleotide differences, structural alterations, as well as protein and RNA interaction sites were analyzed in these variants. For the U1 snRNA variants, they were compared to the previously reported BmN isoforms. In all these U-snRNA variants, polymorphic sites do not predominate at the core of known functional sequences, which were interspecifically conserved. Variant sites and inter-species differences are located in moderately conserved regions. Free energy (G) values for the entire U1 and U2 snRNA secondary structures and for the individual stem/loops domains of the isoforms were generated and compared to determine their structural stability. This will be the first time that U1 and U2 variants are shown specific for a development stage (larval) other than embryonic or adult. ^ Using phylogenetic analysis, evolutionary trees were generated for the U1 and U2 snRNAs using animal, plant, protista and fungal species. The resulting trees were boostrapped for robustness and rooted with the self-splicing RNA group II intron sequence from the cyanobacterium Calothrix. Using phylogenetic analyses, possible structural and functional evolutionary interdependence between the U1 and U2 snRNAs was investigated. ^
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Funding This work was supported by the HADEEP projects, funded by the Nippon Foundation, Japan (2009765188), the Natural Environmental Research Council, UK (NE/E007171/1) and the Total Foundation, France. We acknowledge additional support from the Marine Alliance for Science and Technology for Scotland (MASTS) funded by the Scottish Funding Council (Ref: HR09011) and contributing institutions. We also acknowledge support from the Leverhulme Trust to SBP. Additional sea time was supported by NIWAs Impact of Resource Use on Vulnerable Deep-Sea Communities project (CO1_0906)
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Mmoire numris par la Direction des bibliothques de l'Universit de Montral.
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<p>Cancer comprises a collection of diseases, all of which begin with abnormal tissue growth from various stimuli, including (but not limited to): heredity, genetic mutation, exposure to harmful substances, radiation as well as poor dieting and lack of exercise. The early detection of cancer is vital to providing life-saving, therapeutic intervention. However, current methods for detection (e.g., tissue biopsy, endoscopy and medical imaging) often suffer from low patient compliance and an elevated risk of complications in elderly patients. As such, many are looking to liquid biopsies for clues into presence and status of cancer due to its minimal invasiveness and ability to provide rich information about the native tumor. In such liquid biopsies, peripheral blood is drawn from patients and is screened for key biomarkers, chiefly circulating tumor cells (CTCs). Capturing, enumerating and analyzing the genetic and metabolomic characteristics of these CTCs may hold the key for guiding doctors to better understand the source of cancer at an earlier stage for more efficacious disease management.</p><p> The isolation of CTCs from whole blood, however, remains a significant challenge due to their (i) low abundance, (ii) lack of a universal surface marker and (iii) epithelial-mesenchymal transition that down-regulates common surface markers (e.g., EpCAM), reducing their likelihood of detection via positive selection assays. These factors potentiate the need for an improved cell isolation strategy that can collect CTCs via both positive and negative selection modalities as to avoid the reliance on a single marker, or set of markers, for more accurate enumeration and diagnosis.</p><p> The technologies proposed herein offer a unique set of strategies to focus, sort and template cells in three independent microfluidic modules. The first module exploits ultrasonic standing waves and a class of elastomeric particles for the rapid and discriminate sequestration of cells. This type of cell handling holds promise not only in sorting, but also in the isolation of soluble markers from biofluids. The second module contains components to focus (i.e., arrange) cells via forces from acoustic standing waves and separate cells in a high throughput fashion via free-flow magnetophoresis. The third module uses a printed array of micromagnets to capture magnetically labeled cells into well-defined compartments, enabling on-chip staining and single cell analysis. These technologies can operate in standalone formats, or can be adapted to operate with established analytical technologies, such as flow cytometry. A key advantage of these innovations is their ability to process erythrocyte-lysed blood in a rapid (and thus high throughput) fashion. They can process fluids at a variety of concentrations and flow rates, target cells with various immunophenotypes and sort cells via positive (and potentially negative) selection. These technologies are chip-based, fabricated using standard clean room equipment, towards a disposable clinical tool. With further optimization in design and performance, these technologies might aid in the early detection, and potentially treatment, of cancer and various other physical ailments.</p>
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<p>Rolling Isolation Systems provide a simple and effective means for protecting components from horizontal floor vibrations. In these systems a platform rolls on four steel balls which, in turn, rest within shallow bowls. The trajectories of the balls is uniquely determined by the horizontal and rotational velocity components of the rolling platform, and thus provides nonholonomic constraints. In general, the bowls are not parabolic, so the potential energy function of this system is not quadratic. This thesis presents the application of Gauss's Principle of Least Constraint to the modeling of rolling isolation platforms. The equations of motion are described in terms of a redundant set of constrained coordinates. Coordinate accelerations are uniquely determined at any point in time via Gauss's Principle by solving a linearly constrained quadratic minimization. In the absence of any modeled damping, the equations of motion conserve energy. This mathematical model is then used to find the bowl profile that minimizes response acceleration subject to displacement constraint.</p>
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Mmoire numris par la Direction des bibliothques de l'Universit de Montral.
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Ageing of the population is a worldwide phenomenon. Numerous ICT-based solutions have been developed for elderly care but mainly connected to the physiological and nursing aspects in services for the elderly. Social work is a profession that should pay attention to the comprehensive wellbeing and social needs of the elderly. Many people experience loneliness and depression in their old age, either as a result of living alone or due to a lack of close family ties and reduced connections with their culture of origin, which results in an inability to participate actively in community activities (Singh & Misra, 2009). Participation in society would enhance the quality of life. With the development of information technology, the use of technology in social work practice has risen dramatically. The aim of this literature review is to map out the state of the art of knowledge about the usage of ICT in elderly care and to figure out research-based knowledge about the usability of ICT for the prevention of loneliness and social isolation of elderly people. The data for the current research comes from the core collection of the Web of Science and the data searching was performed using Boolean? The searching resulted in 216 published English articles. After going through the topics and abstracts, 34 articles were selected for the data analysis that is based on a multi approach framework. The analysis of the research approach is categorized according to some aspects of using ICT by older adults from the adoption of ICT to the impact of usage, and the social services for them. This literature review focused on the function of communication by excluding the applications that mainly relate to physical nursing. The results show that the so-called digital divide still exists, but the older adults have the willingness to learn and utilise ICT in daily life, especially for communication. The data shows that the usage of ICT can prevent the loneliness and social isolation of older adults, and they are eager for technical support in using ICT. The results of data analysis on theoretical frames and concepts show that this research field applies different theoretical frames from various scientific fields, while a social work approach is lacking. However, a synergic frame of applied theories will be suggested from the perspective of social work.
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Objective<br/>Scant evidence is available on the discordance between loneliness and social isolation among older adults. We aimed to investigate this discordance and any health implications that it may have.<br/><br/>Method<br/>Using nationally representative datasets from ageing cohorts in Ireland (TILDA) and England (ELSA), we created a metric of discordance between loneliness and social isolation, to which we refer as Social Asymmetry. This metric was the categorised difference between standardised scores on a scale of loneliness and a scale of social isolation, giving categories of: Concordantly Lonely and Isolated, Discordant: Robust to Loneliness, or Discordant: Susceptible to Loneliness. We used regression and multilevel modelling to identify potential relationships between Social Asymmetry and cognitive outcomes.<br/><br/>Results<br/>Social Asymmetry predicted cognitive outcomes cross-sectionally and at a two-year follow-up, such that Discordant: Robust to Loneliness individuals were superior performers, but we failed to find evidence for Social Asymmetry as a predictor of cognitive trajectory over time.<br/><br/>Conclusions<br/>We present a new metric and preliminary evidence of a relationship with clinical outcomes. Further research validating this metric in different populations, and evaluating its relationship with other outcomes, is warranted.