Variation in coumarin 7-hydroxylase activity associated with genetic polymorphism of cytochrome P450 2A6 and the body status of iron stores in adult Thai males and females

The relationships between catalytic activity of cytochrome P450 2A6 (CYP2A6), polymorphism of CYP2A6 gene, gender and levels of body iron stores were analysed in a sample group of 202 apparently healthy Thais, aged 1947 years. Eleven individuals were found to have high activity of CYP2A6, judged by the relatively large amounts (11.2-14.6 mg) of 7-hydroyxcoumarin (7-OHC) excreted 3 h following administration of 15 mg of coumarin. Ten individuals, however, did not excrete any 7-OHC. Of these 10, four were found to have no CYP2A6 gene (whole gene deletion; CYP2A6*4 allele). The frequency of the CYP2A6 alleles; *1A, *1B and *4 in the whole sample group was 52, 40 and 8% while the frequency of the CYP2A6 gene types; *1A/* 1A, *1A/* 1B, *1B/* 1B, *1A/* 4, *1BI* 4, *4/* 4 was 29, 41, 16, 7, 5 and 2%. Subjects having CYP2A6* 1A/* 1B gene-type group were found to have higher rates of coumarin 7-hydroxylation compared with those of the CYP2A6* 1B/* 1B and CYP2A6* 1A/* 4 gene types. The inter-individual variability in CYP2A6 catalytic activity was therefore attributed in part to the CYP2A6 genetic polymorphism. Variation in CYP2A6 activity in this sample group was not associated with gender but, interestingly, it did show an inverse association with plasma ferritin; an indicator of body iron stores. Higher rates of coumarin 7-hydroxylation were found in individuals with low body iron stores (plasma ferritin < 20 μg/l) compared with subjects having normal body iron store status. Subjects (n = 16) with iron overload (plasma ferritin > 300 mug/l) also tended to have elevated rates of coumarin 7-hydroxylation. These results suggest an increased CYP2A6 expression in subjects who have excessive body iron stores. Further investigations into the underlying factors that may lead to increased expression of CYP2A6 in association with abnormal body iron stores are currently in progress in our laboratory. Pharmacogenetics 12:241-249 (C) 2002 Lippincott Williams Wilkins.

Age and gender differences in objectively measured physical activity in youth

TROST. S. G., R. R. PATE, J. F. SALLIS, P. S. FREEDSON, W. C. TAYLOR, M. DOWDA, and J. SIRARD. Age and gender differences in objectively measured physical activity in youth. Med. Sci. Sports Ererc., Vol. 34, No. 2, pp. 350-355, 2002. Purpose: The purpose of this study was to evaluate age and gender differences in objectively measured physical activity (PA) in a population-based sample of students in grades 1-12. Methods: Participants (185 male, 190 female) wore a CSA 7164 accelerometer for 7 consecutive days. To examine age-related trends. students were grouped as follows: grades 1-3 (N = 90), grades 4-6 (N = 91), grades 7-9 (N = 96). and grades 10-12 (N = 92). Bouts of PA and minutes spent in moderate-to-vigorous PA (MVPA) and vigorous PA (VPA) were examined. Results: Daily MVPA and VPA exhibited a significant inverse relationship with grade level, with the largest differences occurring between grades 1d-3 and 4-6. Boys were more active than girls; however, for overall PA, the magnitudes of the gender differences were modest. Participation in continuous 20-min bouts of PA was low to nonexistent. Conclusion: Our results support the notion that PA declines rapidly during childhood and adolescence and that accelerometers are feasible alternatives to self-report methods in moderately sized population-level surveillance studies.

Experimental study of drop-interface coalescence in the presence of polymer stabilisers

An experimental study has been carried out to characterise the performance of polymer stabilisers, partially hydrolysed polyvinyl acetate (PVAc), used in suspension polymerisation processes. The stabilisers are ranked by their ability to stabilise the dispersion characterised by the median coalescence time of a single drop with its homophase at a planar liquid/liquid interface. Results show that the stability of the dispersion relates closely to the molecular properties of the PVAcs. Other conditions being equal, PVAcs with higher molecular weights or lower degrees of hydrolysis can better stabilise a liquid-liquid dispersion. The stability of the dispersion also depends strongly on where the PVAc resides. The presence of a PVAc in the dispersed phase significantly reduces stability. Consistent with results reported in the literature, considerable scatter has been observed on the coalescence times of identical drops under the same conditions. An explanation for the scatter is also proposed in the paper, based on the classical Reynolds model for film thinning. (C) 2002 Elsevier Science B.V. All rights reserved.

Synthesis of polymer-montmorillonite nanocomposites by in situ intercalative polymerization

Two polymer-montmorillonite (MMT) nanocomposites have been synthesized by in situ intercalative polymerization. The styrene monomer is intercalated into the interlayer space of organically modified MMT, a layered clay mineral. Upon the intercalation, the complex is subsequently polymerized in the confinement environment of the interlayer space with a free radical initiator, 2,2-azobis isobutyronitrile. The aniline monomer is also intercalated and then polymerized within the interlayer space of sodium- and copper-MMT initiated by ammonium peroxodisulphate and interlayer copper cations respectively. X-ray diffraction indicates that the MMT layers are completely dispersed in the polystyrene matrix and an exfoliated structure has been obtained. The resulting polyaniline-MMT nanocomposites show a highly ordered structure of a single polyaniline layer stacked with the MMT layers. Fourier transform infrared spectra further confirm the intercalation and formation of both polymer-MMT nanocomposites.

A design method for superconducting MRI magnets with ferromagnetic material

The emphasis of this work is on the optimal design of MRI magnets with both superconducting coils and ferromagnetic rings. The work is directed to the automated design of MRI magnet systems containing superconducting wire and both `cold' and `warm' iron. Details of the optimization procedure are given and the results show combined superconducting and iron material MRI magnets with excellent field characteristics. Strong, homogeneous central magnetic fields are produced with little stray or external field leakage. The field calculations are performed using a semi-analytical method for both current coil and iron material sources. Design examples for symmetric, open and asymmetric clinical MRI magnets containing both superconducting coils and ferromagnetic material are presented.

Fast, scalable master equation solution algorithms. IV. Lanczos iteration with diffusion approximation preconditioned iterative inversion

In this paper we propose a second linearly scalable method for solving large master equations arising in the context of gas-phase reactive systems. The new method is based on the well-known shift-invert Lanczos iteration using the GMRES iteration preconditioned using the diffusion approximation to the master equation to provide the inverse of the master equation matrix. In this way we avoid the cubic scaling of traditional master equation solution methods while maintaining the speed of a partial spectral decomposition. The method is tested using a master equation modeling the formation of propargyl from the reaction of singlet methylene with acetylene, proceeding through long-lived isomerizing intermediates. (C) 2003 American Institute of Physics.

Evaluation of encapsulation techniques of probiotics for yoghurt

The health benefits provided by probiotic bacteria have led to their increasing use in fermented and other dairy products. However, their viability in these products is low. Encapsulation has been investigated to protect the bacteria in the product's environment and improve their survival. There are two common encapsulation techniques, namely extrusion and emulsion, to encapsulate the probiotics for their use in the fermented and other dairy products. This review evaluates the merits and limitations of these two techniques, and also discusses the supporting materials and special treatments used in encapsulation processes. (C) 2003 Elsevier Science Ltd. All rights reserved.

A review of drainage and spontaneous rupture in free standing thin films with tangentially immobile interfaces

A review of spontaneous rupture in thin films with tangentially immobile interfaces is presented that emphasizes the theoretical developments of film drainage and corrugation growth through the linearization of lubrication theory in a cylindrical geometry. Spontaneous rupture occurs when corrugations from adjacent interfaces become unstable and grow to a critical thickness. A corrugated interface is composed of a number of waveforms and each waveform becomes unstable at a unique transition thickness. The onset of instability occurs at the maximum transition thickness, and it is shown that only upper and lower bounds of this thickness can be predicted from linear stability analysis. The upper bound is equivalent to the Freakel criterion and is obtained from the zeroth order approximation of the H-3 term in the evolution equation. This criterion is determined solely by the film radius, interfacial tension and Hamaker constant. The lower bound is obtained from the first order approximation of the H-3 term in the evolution equation and is dependent on the film thinning velocity A semi-empirical equation, referred to as the MTR equation, is obtained by combining the drainage theory of Manev et al. [J. Dispersion Sci. Technol., 18 (1997) 769] and the experimental measurements of Radoev et al. [J. Colloid Interface Sci. 95 (1983) 254] and is shown to provide accurate predictions of film thinning velocity near the critical thickness of rupture. The MTR equation permits the prediction of the lower bound of the maximum transition thickness based entirely on film radius, Plateau border radius, interfacial tension, temperature and Hamaker constant. The MTR equation extrapolates to Reynolds equation under conditions when the Plateau border pressure is small, which provides a lower bound for the maximum transition thickness that is equivalent to the criterion of Gumerman and Homsy [Chem. Eng. Commun. 2 (1975) 27]. The relative accuracy of either bound is thought to be dependent on the amplitude of the hydrodynamic corrugations, and a semiempirical correlation is also obtained that permits the amplitude to be calculated as a function of the upper and lower bound of the maximum transition thickness. The relationship between the evolving theoretical developments is demonstrated by three film thickness master curves, which reduce to simple analytical expressions under limiting conditions when the drainage pressure drop is controlled by either the Plateau border capillary pressure or the van der Waals disjoining pressure. The master curves simplify solution of the various theoretical predictions enormously over the entire range of the linear approximation. Finally, it is shown that when the Frenkel criterion is used to assess film stability, recent studies reach conclusions that are contrary to the relevance of spontaneous rupture as a cell-opening mechanism in foams. (C) 2003 Elsevier Science B.V. All rights reserved.

Simultaneous FT-NIR and ESR analyses to yield propagation rate coefficients for polymerization of methyl methacrylate based monomers

A hyphenated instrumental approach has been used to obtain reliable values for the propagation rate coefficients as a function of conversion for polymerizations of methyl methacrylate (MMA) and a mixture of MMA and ethyleneglycol dimethacrylate (EGDMA) with a 1:1 concentration of double bonds, from near the onset of the Trommsdorf region into the glass region. ESR spectroscopy was used to measure the radical concentration while FT-NIR fibre-optic spectroscopy was employed to measure instantaneously the double-bond concentration within the temperature-controlled cavity of the ESR instrument during polymerization. The advantage of this approach to the measurement of the rate coefficient is that it is equally applicable to branching and linear polymerizations. For the polymerization of methyl methacrylate, the values of the rate coefficient at the lowest conversions at which reliable values could be obtained were in agreement with recently reported values obtained by the PLP-SEC method. For the lowest conversions, the values obtained were 403 1 mol(-1) s(-1) at 306 K for MMA and 5201 mol(-1) s(-1) at 310 K for a 1:1 mixture of MMA and EGDMA. (C) 2003 Society of Chemical Industry.

Dietary influences on survival after ovarian cancer

We evaluated the effects of various food groups and micronutrients in the diet on survival among women who originally participated in a population-based case-control study of ovarian cancer conducted across 3 Australian states between 1990 and 1993. This analysis included 609 women with invasive epithelial ovarian cancer, primarily because there was negligible mortality in women with borderline tumors. The women's usual diet was assessed using a validated food frequency questionnaire. Deaths in the cohort were identified using state-based cancer registries and the Australian National Death Index (NDI). Crude 5-year survival probabilities were estimated using the Kaplan-Meier technique, and adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were obtained from Cox regression models. After adjusting for important confounding factors, a survival advantage was observed for those who reported higher intake of vegetables in general (HR = 0.75, 95% CI = 0.57-0.99, p-value trend 0.01 for the highest third, compared to the lowest third), and cruciferous vegetables in particular (HR = 0.75, 95% CI = 0.57-0.98, p-value trend 0.03), and among women in the upper third of intake of vitamin E (HR = 0.76, 95% CI = 0.58-1.01, p-value trend 0.04). Inverse associations were also seen with protein (p-value trend 0.09), red meat (p-value trend 0.06) and white meat (p-value trend 0.07), and modest positive trends (maximum 30% excess) with lactose (p-value trend 0.04), calcium and dairy products. Although much remains to be learned about the influence of nutritional factors after a diagnosis of ovarian cancer, our study suggests the possibility that a diet high in vegetable intake may help improve survival. (C) 2003 Wiley-Liss, Inc.

Desenvolvimento e análise de uma rede neural artificial para estimativa da erosividade da chuva para o Estado de São Paulo

O conhecimento do valor da erosividade da chuva (R) de determinada localidade é fundamental para a estimativa das perdas de solo feitas a partir da Equação Universal de Perdas de Solo, sendo, portanto, de grande importância no planejamento conservacionista. A fim de obter estimativas do valor de R para localidades onde este é desconhecido, desenvolveu-se uma rede neural artificial (RNA) e analisou-se a acurácia desta com o método de interpolação "Inverso de uma Potência da Distância" (ID). Comparando a RNA desenvolvida com o método de interpolação ID, verificou-se que a primeira apresentou menor erro relativo médio na estimativa de R e melhor índice de confiança, classificado como "Ótimo", podendo, portanto, ser utilizada no planejamento de uso, manejo e conservação do solo no Estado de São Paulo.

Remuneração executiva e desempenho: evidências empíricas no mercado de capitais brasileiro

O objetivo desta dissertação é analisar a relação existente entre remuneração executiva e desempenho em companhias brasileiras de capital aberto listadas na BM&FBOVESPA. A linha teórica parte do pressuposto que o contrato de incentivos corrobora com o alinhamento de interesses entre acionistas e executivos e atua como um mecanismo de governança corporativa a fim de direcionar os esforços dos executivos para maximização de valor da companhia. A amostra foi composta pelas 100 companhias mais líquidas listadas em quantidade de negociações de ações na BM&FBOVESPA durante o período 2010-2012, totalizando 296 observações. Os dados foram extraídos dos Formulários de Referência disponibilizados pela CVM e a partir dos softwares Economática® e Thomson Reuters ®. Foram estabelecidas oito hipóteses de pesquisa e estimados modelos de regressão linear múltipla com a técnica de dados em painel desbalanceado, empregando como variável dependente a remuneração total e a remuneração média individual e como regressores variáveis concernentes ao desempenho operacional, valor de mercado, tamanho, estrutura de propriedade, governança corporativa, além de variáveis de controle. Para verificar os fatores que explicam a utilização de stock options, programa de bônus e maior percentual de remuneração variável foram estimados modelos de regressão logit. Os resultados demonstram que, na amostra selecionada, existe relação positiva entre remuneração executiva e valor de mercado. Verificou-se também que os setores de mineração, química, petróleo e gás exercem influência positiva na remuneração executiva. Não obstante, exerce relação inversa com a remuneração total à concentração acionária, o controle acionário público e o fato da companhia pertencer ao nível 2 ou novo mercado conforme classificação da BMF&BOVESPA. O maior valor de mercado influencia na utilização de stock options, assim como no emprego de bônus, sendo que este também é impactado pelo maior desempenho contábil. Foram empregados também testes de robustez com estimações por efeitos aleatórios, regressões com erros-padrão robustos clusterizados, modelos dinâmicos e os resultados foram similares. Conclui-se que a remuneração executiva está relacionada com o valor corporativo gerando riqueza aos acionistas, mas que a ausência de relação com o desempenho operacional sugere falhas no sistema remuneratório que ainda depende de maior transparência e outros mecanismos de governança para alinhar os interesses entre executivos e acionistas.

Eu bebo sim e estou vivendo : qualidade de vida, masculinidade, padrões de consumo de álcool e representações sociais de bebida alcoólica para homens usuários de unidade de saúde da família

A Política Nacional de Atenção Integral à Saúde do Homem propõe formas diferenciadas de atuação da equipe de saúde no atendimento da população masculina, uma vez que este público demanda estratégias diferenciadas de serviço. Ao se deparar com a realidade vivenciada pelos homens, surgem várias questões acerca do estereótipo social construído acerca das características masculinas e suas vivências. O objetivo da pesquisa foi compreender alguns aspectos relevantes para as práticas de saúde de homens usuários de Unidade de Saúde da Família, como qualidade de vida, consumo de álcool, representações sociais da bebida alcoólica e características de masculinidade. Foi utilizada uma amostra de 300 homens, frequentadores de Unidade de Saúde da Família, e aplicado um questionário contendo os dados sociodemográficos, o World Health Organization Quality of Life (Whoqol-bref), o Bem Sex-Role Inventory (BSRI), um exercício de evocação sobre bebida alcoólica, o Alcohol Use Disorders Identification Test (Audit) e um bloco para verificar os problemas ocasionados pelo consumo de álcool e a procura por tratamento. Os dados dos instrumentos quantitativos foram analisados com testes estatísticos de comparação de médias e de correlação. Os dados das evocações foram analisados com o software EVOC (Ensemble de Programmes Permettant l’Analyse des Évocations). Na primeira análise, constatou-se adesão mais alta a características femininas, alta percepção de qualidade de vida e padrões de consumo de álcool semelhantes às médias nacionais. Homens que declararam praticar sua religião apresentaram média significativamente menor de consumo de álcool. Apresentaram correlação inversamente proporcional ao consumo de álcool as características femininas de gênero, os domínios físico, social, psicológico e percepção global de qualidade de vida. Na análise das evocações, constatou-se que os elementos com tendência à centralidade são, em sua maioria, de cunho negativo. Os dados da população geral apresentaram o termo gosto como um aspecto positivo e central da bebida alcoólica. O grupo de abstinentes não apresentou avaliação positiva do termo e o grupo de bebedores apresentou o termo diversão na primeira periferia, referindo-se aos aspectos positivos e de socialização da bebida alcoólica. Os resultados indicaram uma qualidade de vida satisfatória, a religião e as características femininas destacaram-se como um fator de proteção ao uso de bebida alcoólica. Apresentaram, ainda, percepção dos problemas associados ao próprio consumo. Apesar de a maioria dos termos relacionados à bebida alcoólica ser negativo, este consumo ainda se dá em um nível considerável. Por isso, se faz necessária a construção de vínculo entre o profissional e o usuário do serviço de saúde a fim de dar oportunidade para que as reais práticas sobre a bebida alcoólica sejam evidenciadas. Esses dados podem ajudar profissionais de Saúde da Família a refletirem sobre as representações sociais que constroem acerca dos homens de classe popular usuários do serviço

Optimal design of piezolaminated structures using B-spline strip finite element models

A package of B-spline finite strip models is developed for the linear analysis of piezolaminated plates and shells. This package is associated to a global optimization technique in order to enhance the performance of these types of structures, subjected to various types of objective functions and/or constraints, with discrete and continuous design variables. The models considered are based on a higher-order displacement field and one can apply them to the static, free vibration and buckling analyses of laminated adaptive structures with arbitrary lay-ups, loading and boundary conditions. Genetic algorithms, with either binary or floating point encoding of design variables, were considered to find optimal locations of piezoelectric actuators as well as to determine the best voltages applied to them in order to obtain a desired structure shape. These models provide an overall economy of computing effort for static and vibration problems.

Studies on mosquitoes (Diptera: Culicidae) and anthropicenvironment: 5- Breeding of Anopheles albitarsis in flooded rice fields in South-Eastern Brazil

Studies on breeding Anopheles albitarsis and association with rice growth in irrigated paddy fields were carried out during the rice cultivation cycle from December 1993 to March 1994. This period corresponded to the length of time of permanent paddy flooding. Breeding occurred in the early stage up until five weeks after transplantation when rice plant height was small. That inverse correlation may give potential direction to control measures.