90 research outputs found
Real-time quantitative PCR measurement of circulatory rhodopsin mRNA in healthy subjects and patients with diabetic retinopathy
No full textDiabetic retinopathy is the commonest complication of diabetes and is the biggest single cause of registered blindness in the UK. No biochemical tests exist to determine the precise state and rate of change of the eyes in the diabetic patient. In the present study, using real-time quantitative reverse transcriptase polymerase chain reaction (RT-PCR), we measured mRNA encoding the retina-specific pigment protein rhodopsin (RHO) in the peripheral blood of healthy individuals (n = 20) and diabetic patients (n = 46) with and without retinopathy. Beta-actin mRNA was also assayed and results are expressed as a ratio of RHO to beta-actin mRNA. Peripheral blood was taken by venipucture directly into PAXgene Blood RNA collection tubes and RNA extracted by use of the PAXgene Blood RNA extraction kit, as per the manufacturer's (Qiagen) instructions. Diabetic patients were divided into three groups defined by the severity of retinopathy as assessed by fundoscopy: A, diabetic without retinopathy; B, background retinopathy; and C, preproliferative retinopathy. Medians of the ratios between groups were compared. RHO mRNA was successfully detected and quantified in peripheral blood in all healthy and diabetic groups, with levels shown to be significantly higher in diabetic patients than in healthy controls (2.54 x 10(-5) vs. 1.29 x 10(-4); P = 0.002). Significant differences in RHO mRNA levels were also seen between healthy control subjects and diabetic groups A (2.52 x 10(-5); P = 0.022), B (1.98 x 10(-5)., P = 0.028), and C (5.08 x 10(-5); P = 0.002). The results suggest that there is an increase in circulatory RHO mRNA with the severity of diabetic retinopathy
Role of cell-free plasma DNA as a diagnostic marker for prostate cancer
No full textRecent evidence has shown elevated levels of cell-free plasma DNA in cancer patients. The aim of the present study was to quantify and compare the levels of cell-free plasma DNA in patients with prostate cancer, prostatic intraepithelial neoplasia (PIN), and benign prostatic hypertrophy (BPH) to examine if it offered a useful diagnostic test. Blood samples were obtained from 37 patients attending a clinic for prostate biopsies. Samples were taken prior to biopsy, within 1 hour of the biopsy, and then 2 weeks later. DNA was extracted using a QIAamp blood kit (Qiagen) and plasma DNA measured, in genome equivalents/milliliter plasma (GE/mL), using real-time quantitative PCR for the beta-globin gene. Prior to biopsy, plasma DNA concentration in BPH patients was 936 GE/mL (median; range: 633-2074 GE/mL), while cancer and PIN patients had significantly higher levels of DNA at 1734 GE/mL (median; range: 351-3131 GE/mL; P = 0.01) and 1780 GE/mL (median; range: 1514-2732 GE/mL; P = 0.04), respectively. Comparison of plasma DNA concentration before and after biopsy showed that 60 minutes after biopsy values were significantly higher in both BPH (1494 GE/mL; range: 613-2522 GE/mL; P = 0.029) and cancer (2758; range: 1498-5226 GE/mL; P = 0.007) patients. ROC analysis of the data indicated a sensitivity of 85% and a specificity of 73% when DNA concentration of 1000 GE/mL was taken as an indicator of malignancy or PIN. The data suggest that quantification of cell-free plasma DNA may have an important diagnostic role in distinguishing benign and malignant prostate disease
Twisted conjugacy in soluble arithmetic groups
No full textReidemeister numbers of group automorphisms encode the number of twisted conjugacy classes of groups and might yield information about self-maps of spaces related to the given objects. Here we address a question posed by Gonçalves and Wong in the mid 2000s: we construct an infinite series of compact connected solvmanifolds (that are not nilmanifolds) of strictly increasing dimensions and all of whose self-homotopy equivalences have vanishing Nielsen number. To this end, we establish a sufficient condition for a prominent (infinite) family of soluble linear groups to have the so-called property R-infinity. In particular, we generalize or complement earlier results due to Dekimpe, Gonçalves, Kochloukova, Nasybullov, Taback, Tertooy, Van den Bussche, and Wong, showing that many soluble S-arithmetic groups have R-infinity and suggesting a conjecture in this direction.</p
A Novel Susceptibility Locus for Type 1 Diabetes on Chr12q13 Identified by a Genome-Wide Association Study
No full textPrograma de atividade física e social para os portadores da Doença de Parkinson: o tênis de mesa e a análise dos fatores motivacionais
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Filosofia e Ciências Humanas, Programa de Pós-Graduação em Psicologia, Florianópolis, 2004A Doença de Parkinson (DP) é um distúrbio degenerativo do Sistema Nervoso Central que prejudica o controle das ações motoras. O portador desta doença deve praticar atividades físicas que prolonguem sua independência e qualidade de vida. Esta pesquisa promoveu um programa de tênis de mesa em uma associação de portadores da DP, com o intuito de verificar os fatores motivacionais que levaram os sujeitos à adesão e à continuidade no programa. A amostra foi formada por 16 portadores de DP, sendo 11 homens e 5 mulheres, com idade entre 47 e 83 anos e tempo de diagnóstico da doença entre 2 e 21 anos. Todos os participantes foram voluntários. O programa se estendeu por 2 meses, num total de 38 dias de atividades, contando com 120 participações que duraram em média 30 minutos. Os dados foram coletados através de um diário de campo e de uma entrevista semi-estruturada. Os 16 participantes foram divididos em 4 categorias, de acordo com o principal motivo demonstrado para a prática do programa. Após as entrevistas e com base no diário de campo, foram definidos os grupos: (1) "O jogo pelo prazer", (2) "Preocupação com a saúde", (3) "Influência de terceiros" e (4) "Fator social". Os resultados dos grupos 1 e 2 (definidos a partir das categorias) demonstraram o melhor desempenho na freqüência de comparecimento, enquanto os grupos 3 e 4 tiveram os piores desempenhos. Os fatores motivacionais encontrados nestes sujeitos são os mesmos encontrados na literatura. Como conclusão, observou-se que a identificação com a atividade, a busca por uma maior qualidade de vida e independência no dia-a-dia, a socialização e o caráter lúdico, foram os fatores motivacionais que promoveram a adesão dos sujeitos e a seqüência no programa da maioria deles
Accelerated partial breast irradiation using brachytherapy (APBIb) for breast cancer (bca): Predictors of use and guideline concordance.
No full text 84 Background: APBIb is a novel alternative to whole breast irradiation (WBI). The American Society for Radiation Oncology Guidelines (ASTRO-G) established appropriateness for APBIb use off protocol. Methods: 138,815 bca patients from the Surveillance, Epidemiology, and End Results database underwent WBI or APBIb after lumpectomy from 2000 to 2007. Patients were classified as suitable, cautionary, or unsuitable for APBIb according to ASTRO-G. Logistic regression was applied to study APBIb use overall and within each guideline category. Results: Overall, 2.6% received APBIb and use varied by ASTRO-G: 5% in suitable, 3.4% in cautionary, and 1.6% in unsuitable patients (p<0.0001). APBIb use increased with time (2000: 0.3%, 2007: 7%) and varied widely with region (0% Alaska; 7% Atlanta, Georgia). Independent predictors of APBIb among suitable patients included white (OR 2.0, p<0.001) race, region (OR 2.6-8.6, p<0.0001), later year (2006-7 v 2000-2 OR 20.3, p<0.0001), and lower grade (OR 1.3, p=0.01). Among cautionary patients, white race (OR 1.8, p<0.001), non-Hispanic ethnicity (OR 1.3, p<0.04), region (OR 3.1-10.2, p<0.0001), metropolitan location (OR 1.9, p=0.01), later year (2006-2007 OR 17.6, p<0.0001), and lower grade (OR 1.4, p<0.0001) predicted for APBIb. Among unsuitable patients, race (p<0.0001), region (OR 3.3-21.6, p<0.0001), later year (2006-7 OR 12.7, p<0.0001), estrogen receptor-positive status (OR 1.3, p=0.002), lower grade (OR 1.3, p<0.01), and negative lymph nodes (OR 2.0, p<0.0001) predicted for use. In several regions, odds of APBIb increased as appropriateness decreased (see Table). Conclusions: APBIb has been rapidly adopted in the US. Its use varied by race, ethnicity, and region, especially among patients who may not be suitable candidates for this technique. [Table: see text] </jats:p
BIOMECHANICAL STUDY OF THE MECHANICAL AND STRUCTURAL PROPERTIES OF ADHERENT CELLS
No full textA cell is a biological complex system and its understanding requires a combination of various approaches including biomechanics. Like engineering materials, cells deform when external forces act on them. There is evidence that many normal and diseased conditions of cells are dependent on, or regulated by the way cells mechanically interact with the environment.
A major interest in cell mechanics is the regulation of cellular function by mechanical forces, which is determined by the composition and structures of cells. While the exact structural mechanisms involved in force transmission inside the cells are not well understood, computational cell modelling can yield important insights. This may contribute to build up a structure- function relationship of different adherent cell types. One approach to studying the mechanosensing processes is to understand the mechanical properties of cells’ constitutive components individually.
For this purpose, a representative 3D finite element model of a single adherent cell was developed based on the internal structures of the cytoskeleton that provide the cells with their mechanical properties. The results indicate which cytoskeleton components are targeted to respond to specific loading conditions, such as compression and stretching. More specifically, actin cortex and microtubules are targeted to respond to compressive loads, while actin bundles and microtubules are major components in maintaining cell forces during stretching.
This approach clarifies the effects of cytoskeletal heterogeneity and regional variations on the interpretation of force-deformation measurements. With a sensitivity study of the material properties of the different cellular components, the model shows how these properties differ to define cell rigidity across different cell types. Cell force is mainly affected by changes in cortex
thickness, cortex Young’s modulus and rigidity of the cytoplasm. Changes in rigidity of actin bundles and number of microtubules influence cell response to shear loads, while the number of actin bundles deeper in the interior of the cell, affect cell response to compression.
The time dependent responses observed following a power-law are remarkably similar to those reported for a variety of measurements with atomic force microscopy, suggesting this model is a consensus description of the fundamental principles defining cell mechanics. Simulations of the dynamic response of a single cell suggest that the origin of different force-relaxation times is linked to the structural architecture of the cell. The results also suggest that it is important to consider the viscoelastic properties of the cortex, other than the cytoplasm, to properly define the time-dependent response of the cell to compressive loads.
The FE single-cell model includes the three parameters defining the fundamental principles defining cell mechanics: rigidity, prestress and time-dependence deformation following a power-law behaviour. This thesis con- tributes to understand the mechanical interaction and properties across different cell components, responsible for cell behaviour, that will ultimately lead to functional adaptation or pathological conditions
Solução de escoamentos reativos em bocais de expansão usando o método dos volumes finitos
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico.A previsão teórica de escoamentos compressíveis geralmente é feita admitindo-se a hipótese de fluido caloricamente perfeito. Quando as temperaturas alcançadas pelo escoamento são elevadas deve-se utilizar hipóteses mais realísticas, que contemplam as variações dos calores específicos e da composição química. Nesta dissertação são apresentados os modelos matemático e numérico empregados para simular os escoamentos congelado e em equilíbrio químico local no interior de bocais do tipo convergente-divergente. O modelo matemático quase-unidimensional é constituído pelas equações de conservação da massa, da quantidade de movimento linear e da energia, além da equação de estado dos gases perfeitos. Como a equação de conservação da energia é escrita em termos da entalpia, também é utilizada uma expressão que relaciona essa propriedade com a temperatura e pressão. O método das constantes de equilíbrio é empregado para determinar a composição química. O modelo numérico, baseado no método dos volumes finitos com solução segregada, utiliza uma formulação adequada a qualquer regime de velocidade e funções de interpolação de segunda ordem aplicadas com correção adiada. O objetivo do trabalho, utilizar o método dos volumes finitos para simular escoamentos em equilíbrio químico local, é alcançado com êxito. Os resultados aqui obtidos concordam bem com os da solução analítica para fluidos caloricamente perfeitos e com os do programa NASA SP-273 para escoamentos congelado e em equilíbrio químico local
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