bluuebunny/crossref_metadata_2025 huggingface dataset:
Structure-based discovery of inhibitors of the YycG histidine kinase: New chemical leads to combat Staphylococcus epidermidis infections
Authors: Qin Zhiqiang , Zhang Jian , Xu Bin , Chen Lili , Wu Yang , Yang Xiaomei , Shen Xu , Molin Soeren , Danchin Antoine , Jiang Hualiang , Qu Di
Published: November 2006

Background

Coagulase-negative Staphylococcus epidermidis has become a major frequent cause of infections in relation to the use of implanted medical devices. The pathogenicity of S. epidermidis has been attributed to its capacity to form biofilms on surfaces of medical devices, which greatly increases its resistance to many conventional antibiotics and often results in chronic infection. It has an urgent need to design novel antibiotics against staphylococci infections, especially those can kill cells embedded in biofilm.

Results

In this report, a series of novel inhibitors of the histidine kinase (HK) YycG protein of S. epidermidis were discovered first using structure-based virtual screening (SBVS) from a small molecular lead-compound library, followed by experimental validation. Of the 76 candidates derived by SBVS targeting of the homolog model of the YycG HATPase_c domain of S. epidermidis, seven compounds displayed significant activity in inhibiting S. epidermidis growth. Furthermore, five of them displayed bactericidal effects on both planktonic and biofilm cells of S. epidermidis. Except for one, the compounds were found to bind to the YycG protein and to inhibit its auto-phosphorylation in vitro, indicating that they are potential inhibitors of the YycG/YycF two-component system (TCS), which is essential in S. epidermidis. Importantly, all these compounds did not affect the stability of mammalian cells nor hemolytic activities at the concentrations used in our study.

Conclusion

These novel inhibitors of YycG histidine kinase thus are of potential value as leads for developing new antibiotics against infecting staphylococci. The structure-based virtual screening (SBVS) technology can be widely used in screening potential inhibitors of other bacterial TCSs, since it is more rapid and efficacious than traditional screening technology.
Antimicrobial effects of liquid anesthetic isoflurane on Candida albicans
Authors: Barodka Viachaslau M , Acheampong Edward , Powell Garry , Lobach Ludmila , Logan David A , Parveen Zahida , Armstead Valerie , Mukhtar Muhammad
Published: November 2006

Candida albicans is a dimorphic fungus that can grow in yeast morphology or hyphal form depending on the surrounding environment. This ubiquitous fungus is present in skin and mucus membranes as a potential pathogen that under opportunistic conditions causes a series of systemic and superficial infections known as candidiasis, moniliasis or simply candidiasis. There has been a steady increase in the prevalence of candidiasis that is expressed in more virulent forms of infection. Although candidiasis is commonly manifested as mucocutaneous disease, life-threatening systemic invasion by this fungus can occur in every part of the body. The severity of candidal infections is associated with its morphological shift such that the hyphal morphology of the fungus is most invasive. Of importance, aberrant multiplication of Candida yeast is also associated with the pathogenesis of certain mucosal diseases. In this study, we assessed the anti-candidal activity of the volatile anesthetic isoflurane in liquid form in comparison with the anti-fungal agent amphotericin B in an in vitro culture system. Exposure of C. albicans to isoflurane (0.3% volume/volume and above) inhibited multiplication of yeast as well as formation of hyphae. These data suggest development of potential topical application of isoflurane for controlling a series of cutaneous and genital infections associated with this fungus. Elucidiation of the mechanism by which isoflurane effects fungal growth could offer therapeutic potential for certain systemic fungal infections.
Liver Receptor Homolog-1 and Steroidogenic Factor-1 Have Similar Actions on Rat Granulosa Cell Steroidogenesis
Authors: Saxena Deeksha , Escamilla-Hernandez Rosalba , Little-Ihrig Lynda , Zeleznik Anthony J.
Published: November 2006

Granulosa cells express the closely related orphan nuclear receptors steroidogenic factor-1 (SF-1) and liver receptor homolog-1 (LRH-1). To determine whether SF-1 and LRH-1 have differential effects on steroid production, we compared the effects of overexpressing LRH-1 and SF-1 on estrogen and progesterone production by undifferentiated rat granulosa cells. Adenovirus mediated overexpression of LRH-1 or SF-1 had qualitatively similar effects. Neither LRH-1 nor SF-1 alone stimulated estrogen or progesterone production, but when combined with FSH and testosterone, each significantly augmented progesterone production and mRNAs for cholesterol side-chain cleavage enzyme and 3β-hydroxysteroid dehydrogenase above that observed with FSH alone, with SF-1 being more effective than LRH-1. LRH-1 did not augment FSH-stimulated estrogen production, whereas SF-1 produced only a slight (∼30%) augmentation of FSH-stimulated estrogen production. The stimulatory actions of both were reduced by overexpression of dosage-sensitive sex reversal, adrenal hypoplasia congenita, critical region on the X chromosome, gene 1. Expression of either LRH-1 or SF-1 together with constitutively active protein kinase B in the absence of FSH stimulated progesterone production and mRNAs for 3β-hydroxysteroid dehydrogenase and cholesterol side-chain cleavage enzyme but did not stimulate estrogen production or mRNA for aromatase. These findings demonstrate that LRH-1 and SF-1 have qualitatively similar actions on FSH-stimulated estrogen and progesterone production, which would suggest that these factors may have overlapping actions in the regulation of steroidogenesis that accompanies granulosa cell differentiation.
Endogenous Relaxin Is a Naturally Occurring Modulator of Experimental Renal Tubulointerstitial Fibrosis
Authors: Hewitson Tim D. , Mookerjee Ishanee , Masterson Rosemary , Zhao Chongxin , Tregear Geoffrey W. , Becker Gavin J. , Samuel Chrishan S.
Published: November 2006

Relaxin is a naturally occurring regulator of collagen turnover. In this study, we determined the role of endogenous relaxin in the pathogenesis of primary tubulointerstitial fibrosis after unilateral ureteric obstruction (UUO). Four- to 6-wk-old relaxin (RLX) gene-knockout (RLX−/−) and age-matched wild-type (RLX+/+) mice, with equivalent baseline collagen levels, were subjected to UUO. Obstructed and contralateral kidneys were collected at d 0, 3, and 10 after surgery and analyzed for changes in inflammatory and fibrosis-related markers. UUO was associated with a progressive increase in fibrosis in all obstructed, but not contralateral kidneys. The increase in total collagen (hydroxyproline analysis) was associated with more α-smooth muscle actin (α-SMA) staining (myofibroblasts) and interstitial collagen sub-types (SDS-PAGE; types I, III, and V), whereas gelatin zymography demonstrated increased expression of matrix metalloproteinase-2 after surgery. By d 10 after UUO, there was a 5-fold decrease in RLX mRNA expression (quantitative RT-PCR) in RLX+/+ animals. Total collagen and α-SMA expression were significantly greater in the obstructed kidneys of RLX−/− mice 3 d after UUO (both P < 0.05 vs. RLX+/+ D3 after UUO), but comparable to that in RLX+/+ animals 10 d after UUO. Administration of recombinant H2 relaxin to RLX−/− mice 4 d before UUO ameliorated the increase in collagen and α-SMA expression (both P < 0.05 vs. untreated RLX−/− mice) by d 3 after UUO. Expression of monocyte chemoattractant protein-1 and macrophage infiltration (inflammation) in addition to that of matrix metalloproteinases was unaffected by genotype after UUO. These combined data demonstrate that endogenous RLX acts as a modulating factor in tubulointerstitial fibrosis, a hallmark of progressive renal disease. This is likely to be via direct effects on renal myofibroblast function.
Prolactin-Like Protein-F Subfamily of Placental Hormones/Cytokines: Responsiveness to Maternal Hypoxia
Authors: Ho-Chen Jennifer K. , Bustamante Juan J. , Soares Michael J.
Published: November 2006

The prolactin (PRL) family of hormones/cytokines is involved in the maintenance of pregnancy and adaptations to physiological stressors. In this report, we identify and characterize a new member of the rat PRL family, examine the impact of maternal hypoxia on placental PRL family gene expression, and investigate maternal adaptive responses to hypoxia. Perusal of the PRL gene family locus in the rat genome resulted in the identification of a putative new member of the rat PRL family. The new member is closely related to the previously reported PRL-like protein-F (PLP-F) and has been named PLP-Fβ and the originally characterized PLP-F, now termed PLP-Fα. The two proteins exhibit structural similarities but possess distinct cell- and temporal-specific expression profiles. In vivo hypoxia stimulates placental PLP-Fα and PLP-E mRNA expression in the rat and mouse, respectively. Rcho-1 trophoblast cells can differentiate into trophoblast giant cells, express PLP-Fα, and exhibit enhanced PLP-Fα mRNA levels when cultured under low oxygen tension (2%). Exposure to hypobaric hypoxia during latter part of pregnancy did not significantly impact the expression of PLP-Fβ mRNA. Finally, exposure to hypobaric hypoxia during midpregnancy led to increased maternal red blood cells, hemoglobin concentrations, hematocrit, and increased concentrations of maternal splenic mRNAs for key proteins involved in hemoglobin synthesis, erythroid Krüppel-like factor, erythroid 5-aminolevulinate synthase-2, and β-major globin. In summary, adaptive responses to maternal hypoxia include activation of placental PLP-Fα/E gene expression, which may then participate in maternal hematological adjustments required for maintaining maternal and fetal oxygen delivery.
1α,25(OH)2D3-Induced Transrepression by Vitamin D Receptor through E-Box-Type Elements in the Human Parathyroid Hormone Gene Promoter
Authors: Kim Mi-sun , Fujiki Ryoji , Murayama Akiko , Kitagawa Hirochika , Yamaoka Kazuyoshi , Yamamoto Yoko , Mihara Masatomo , Takeyama Ken-ichi , Kato Shigeaki
Published: November 2006

Although transactivation by the liganded vitamin D receptor (VDR) is well described at the molecular level, the precise molecular mechanism of negative regulation by the liganded VDR remains to be elucidated. We have previously reported a novel class of negative vitamin D response element (nVDRE) called 1αnVDRE in the human 25(OH)D31α-hydroxylase [1α(OH)ase] gene by 1α,25(OH)2D3-bound VDR. This element was composed of two E-box-type motifs that bound to VDIR for transactivation, which was attenuated by liganded VDR. Here, we explore the possible functions of VDIR and E-box motifs in the human (h) PTH and hPTHrP gene promoters. Functional mapping of the hPTH and hPTHrP promoters identified E-box-type elements acting as nVDREs in both the hPTH promoter (hPTHnVDRE; −87 to −60 bp) and in the hPTHrP promoter (hPTHrPnVDRE; −850 to −600 bp; −463 to −104 bp) in a mouse renal tubule cell line. The hPTHnVDRE alone was enough to direct ligand-induced transrepression mediated through VDR/retinoid X receptor and VDIR. Direct DNA binding of hPTHnVDRE to VDIR, but not VDR/retinoid X receptor, was observed and ligand-induced transrepression was coupled with recruitment of VDR and histone deacetylase 2 (HDAC2) to the hPTH promoter. These results suggest that negative regulation of the hPTH gene by liganded VDR is mediated by VDIR directly binding to the E-box-type nVDRE at the promoter, together with recruitment of an HDAC corepressor for ligand-induced transrepression.
Methylmercury Measurement in Whole Blood by Isotope-Dilution GC-ICPMS with 2 Sample Preparation Methods
Authors: Baxter Douglas C , Rodushkin Ilia , Engström Emma , Klockare Dennis , Waara Hans
Published: November 2006

Background: Despite its known toxicity, methylmercury is rarely measured directly in clinical studies; instead, conclusions are based on total mercury measurements. We have developed isotope–dilution-based methods for methylmercury-specific analysis of whole blood by coupled gas chromatography–inductively coupled plasma mass spectrometry (GC-ICPMS).

Methods: We analyzed animal and human blood samples after alkaline digestion or extraction of methylmercury into dichloromethane and back extraction into water. Methylmercury was converted to the volatile ethyl derivative, purged, and trapped on a solid-phase collection medium, and then introduced into the GC-ICPMS system.

Results: Limits of quantification were 0.4 and 0.03 μg/L at a signal-to-noise ratio of 10 with the alkaline digestion and extraction methods, respectively. Extraction met our selected acceptable total error criterion, with an SD of 0.58 μg/L at the critical maternal blood concentration of 5.8 μg/L. Results obtained with alkaline digestion indicated the need for improved random analytical uncertainty, which was achieved by increasing the enrichment of the isotope dilution. For 37 blood samples, the mean (SD) proportion of total mercury present as methylmercury was 60 (27)%, range 6%–100%.

Conclusions: The combination of extraction and isotope-dilution GC-ICPMS meets the requirements for use as a reference method for measuring methylmercury in whole blood.
Influencias y hegemonías en la orientación de la investigación de las reformas de salud
Authors: Palma-Solís Marco Antonio , Franco Giraldo Álvaro , Álvarez-Dardet Carlos
Published: November 2006

Analizamos la evolución de las publicaciones, incluidas en MEDLINE, LILACS y Sociological Abstracts, sobre las Reformas de Salud en el mundo y las influencias que determinan su orientación y distribución en el período de 1990-2004. En total se seleccionaron 8.729 publicaciones. Los principios de "Sostenibilidad" y "Calidad y Efectividad" son los más atendidos, existiendo distintos patrones de atención, dependiendo de regiones y países. De 199 países, el 61% tiene referencia sobre sus procesos de reforma, siendo Estados Unidos y Gran Bretaña los que agrupan la mayor cantidad. Se observó que existen fuertes influencias para el estudio de las Reformas de Salud, provenientes de los patrones Británico y Norteamericano de atención a los Principios de Reforma. Esto puede estar limitando la visibilidad científica de cuestiones como la equidad, participación y eficiencia.
Avaliação da cobertura do programa de triagem neonatal de hemoglobinopatias em populações do Recôncavo Baiano, Brasil
Authors: Silva Wellington dos Santos , Lastra Angel , Oliveira Silviene Fabiana de , Klautau-Guimarães Nazaré , Grisolia Cesar Kope
Published: November 2006

Em 2001, a Portaria n. 822/2001 do Ministério da Saúde tornou obrigatória a triagem neonatal para as hemoglobinopatias, especialmente a anemia falciforme, a doença genética mais comum no Brasil. A Bahia, em decorrência de sua história de povoamento, é o Estado com maior prevalência dessa doença no país. No presente trabalho, apresentamos a cobertura da triagem neonatal (número de recém-nascidos/número de triagens realizadas) no período de 2001 a 2003 nos municípios de Cachoeira, São Félix e Maragogipe, localizados na região do Recôncavo Baiano, e a freqüência das hemoglobinas variantes HbS e HbC na população dos mesmos municípios, com exceção de São Félix. A freqüência total estimada de portadores para as duas hemoglobinas nessas populações foi de 13,0% e nos recém-nascidos de 8,5% em 2001, 6,5% em 2002 e 11,6% em 2003. A cobertura da triagem neonatal, quando se considera o período de 2001 a 2003, caiu de 82,6% para 46,4% no Município de Cachoeira, aumentou de 23,7% para 56,2% em Maragogipe e em São Félix atingiu 100%. Os dados aqui apresentados apontam para a necessidade de um melhor preparo dos serviços de saúde pública na maioria dos municípios analisados do Recôncavo Baiano para a cobertura da triagem neonatal.
Atenção aos defeitos congênitos no Brasil: características do atendimento e propostas para formulação de políticas públicas em genética clínica
Authors: Horovitz Dafne Dain Gandelman , Cardoso Maria Helena Cabral de Almeida , Llerena Jr. Juan Clinton , Mattos Ruben Araújo de
Published: November 2006

O impacto dos defeitos congênitos no Brasil vem aumentando, apontando para a necessidade de estratégias específicas na política de saúde. Apesar da íntima ligação da genética clínica com a atenção aos defeitos congênitos, menos de 30% da demanda vem sendo absorvida pelos serviços do país. São problemas na atenção aos defeitos congênitos: dificuldades de acesso aos serviços de genética com concentração destes no Sul/Sudeste e suporte laboratorial insuficiente. Para melhor abordagem aos defeitos congênitos, ações para o estabelecimento de política em genética clínica deveriam ser deflagradas, preferencialmente sob coordenação de grupo técnico vinculado ao Ministério da Saúde, tendo como objetivo organizar rede clínico-laboratorial na especialidade. Ações visando à otimização de recursos e ao aumento da cobertura deverão ser consideradas. Para suporte laboratorial são prementes arranjos visando o fluxo de exames e criação de mecanismos de financiamento. Ações complementares de prevenção e registro epidemiológico dos defeitos congênitos, educação médica e do usuário são recomendadas. Com tais propostas contempladas, será possível a estruturação de uma rede regionalizada, hierarquizada e funcional, além de mais justa e mais democrática, voltada à atenção aos defeitos congênitos no Brasil.
Suicide rates in the State of Rio Grande do Sul, Brazil: association with socioeconomic, cultural, and agricultural factors
Authors: Faria Neice Müller Xavier , Victora Cesar Gomes , Meneghel Stela Nazareth , Carvalho Lenine Alves de , Falk João Werner
Published: November 2006

Rio Grande do Sul State has the highest suicide rates in Brazil. Previous studies have suggested a possible role of agricultural activities, especially tobacco farming, where pesticide use is intensive. An ecological study was designed to assess associations between age-adjusted suicide rates based on death certificates and socioeconomic and agricultural factors. Suicide rates in males and females were inversely associated with schooling level and directly associated with divorce/marital separation. Rates for men were higher in areas where traditional Protestant religious were more prevalent, and rates for women were lower in areas with a higher proportion of single-inhabitant households. Multivariate analyses showed no associations between increased suicide rates and any of the agricultural variables. These results confirm the role of socioeconomic determinants of suicide, but do not support the hypothesis of a specific role of agricultural practices.
Adaptação transcultural e análise das propriedades psicométricas da versão brasileira do Perfil de Atividade Humana
Authors: Souza Aline Cristina , Magalhães Lívia de Castro , Teixeira-Salmela Luci Fuscaldi
Published: November 2006

O objetivo deste estudo foi avaliar as propriedades psicométricas da versão brasileira do Perfil de Atividade Humana (PAH), um instrumento de avaliação funcional e do nível de atividade física. O PAH foi traduzido para o português segundo metodologia recomendada e aplicado em 230 idosos (66,32 ± 8,5 anos) da comunidade da cidade de Belo Horizonte, Minas Gerais, Brasil. Os dados foram submetidos à análise Rasch, que detectou itens muito fáceis e muito difíceis, possibilitando sua utilização em pessoas mais debilitadas ou mais capazes. O índice de separação de 3,1 indica que os itens dividiram os indivíduos em três níveis de habilidade funcional. Dos 94 itens, seis (6,38%) foram considerados erráticos. Esse resultado compromete a validade de constructo do teste, pois significa que nem todos os itens se "encaixaram" em um contínuo, sendo recomendada cautela ao interpretar o escore do PAH em idosos com características semelhantes às da amostra. Caso em novos estudos o número de itens erráticos continue acima de 5%, sugere-se modificação, substituição ou exclusão desses itens, para garantir que o PAH meça um constructo unidimensional.
A participação dos agentes indígenas de saúde nos serviços de atenção à saúde: a experiência em Santa Catarina, Brasil
Authors: Langdon Esther Jean , Diehl Eliana Elisabeth , Wiik Flávio Braune , Dias-Scopel Raquel Paiva
Published: November 2006

Este trabalho analisa a formação e o papel do agente indígena de saúde (AIS) nas Terras Indígenas (T.I.) Xapecó e Laklãnõ, Santa Catarina, Brasil, frente à Política Nacional de Atenção à Saúde dos Povos Indígenas. O papel do AIS na atenção básica de saúde é definido com base na mediação entre os saberes e práticas de atenção à saúde tradicionais e biomédicos, inserido no conceito de atenção diferenciada. Em ambas as T.I. foi constatada uma grande rotatividade de AIS, bem como a falta e/ou a inadequação de cursos de capacitação. Observaram-se ainda dificuldades dos AIS para entender a justificativa das atividades delegadas a eles, agravadas pela ambigüidade de seu papel frente à comunidade e por problemas na comunicação com os outros profissionais de saúde. Considerando os pressupostos da Política Nacional, esta pesquisa indicou que a articulação entre as práticas indígenas de auto-atenção e os serviços biomédicos é precária, necessitando de um aprofundamento nas discussões, com a efetiva participação de todos os atores envolvidos na atenção à saúde.
Expectativas sobre a assistência ao parto de mulheres usuárias de uma maternidade pública do Rio de Janeiro, Brasil: os desafios de uma política pública de humanização da assistência
Authors: Dias Marcos Augusto Bastos , Deslandes Suely Ferreira
Published: November 2006

Analisamos as expectativas de gestantes, usuárias de uma maternidade pública no Município do Rio de Janeiro, Brasil, sobre a assistência que receberam no parto e a avaliação que fazem do atendimento recebido em partos anteriores. A metodologia pautou-se pela análise temática de entrevistas realizadas entre o oitavo e o nono mês de gravidez. Foram analisadas informações das mulheres sobre humanização da assistência ao parto, experiências relativas à assistência recebida em parto(s) anterior(es), seu ideal de atendimento ao parto eminente e sobre a atenção da equipe de saúde. Os resultados mostram que as expectativas estão centradas em três elementos principais: admissão rápida na internação, garantia de vaga na maternidade e o atendimento por uma equipe atenciosa e competente que cuide de sua saúde e do seu bebê. As informações discordantes sobre a qualidade da assistência na maternidade trazem para essas mulheres uma tensão a mais nesse momento já que, a seu ver, a qualidade do cuidado dependerá mais de sorte do que da rotina institucional. A partir dessas expectativas, os autores avaliam os desafios da política de humanização da assistência ao parto em implantação nesse município.
Hospitalizações por causas respiratórias e cardiovasculares associadas à contaminação atmosférica no Município de São Paulo, Brasil
Authors: Gouveia Nelson , Freitas Clarice Umbelino de , Martins Lourdes Conceição , Marcilio Izabel Oliva
Published: November 2006

A constatação de que os atuais níveis de poluição atmosférica são suficientes para causar danos à saúde torna imprescindível a definição de processos reguladores para a qualidade do ar. Este estudo analisa a associação entre exposição à poluição atmosférica e internações hospitalares no Município de São Paulo, Brasil, visando subsidiar a elaboração de medidas para redução dos riscos à saúde. Realizou-se um estudo ecológico de séries temporais, analisando hospitalizações por causas respiratórias e cardiovasculares em crianças e idosos em relação aos níveis diários observados de poluentes, por meio de modelos aditivos generalizados em regressão de Poison. Todos os poluentes, com exceção do ozônio, apresentaram associação significante com internações respiratórias e cardiovasculares. Um aumento de 10µg/m³ no nível de material particulado inalável associa-se ao incremento de 4,6% nas internações por asma em crianças, de 4,3% por doença pulmonar obstrutiva crônica em idosos e de 1,5% por doença isquêmica do coração também em idosos. Essas associações entre aumento no nível de poluentes na atmosfera e o aumento de hospitalizações estão de acordo com a literatura nacional e internacional sobre o assunto e indicam que os níveis atuais de contaminação do ar no Município de São Paulo têm impacto na saúde de sua população.
Mutations in the pfmdr1, cg2, and pfcrt genes in Plasmodium falciparum samples from endemic malaria areas in Rondonia and Pará State, Brazilian Amazon Region
Authors: Viana Giselle Maria Rachid , Machado Ricardo Luís Dantas , Calvosa Vanja Sueli Pachiano , Póvoa Marinete Marins
Published: November 2006

The objectives of this study were to investigate the molecular basis for Plasmodium falciparum resistance to chloroquine in isolates from the Brazilian Amazon and to identify polymorphisms in the pfmdr1 gene, codons 184, 1042, and 1246, the kappa and gamma regions of the cg2 gene, and the K76T mutation of the pfcrt gene, in order to calculate the distribution of polymorphism within each target gene, comparing samples from distinct geographic areas, using allele-specific polymerase chain reaction (PCR) for the pfmdr gene and PCR plus restriction fragment length polymorphism (RFLP) for the cg2 and pfcrt genes. The sample consisted of 40 human blood isolates, already collected and morphologically diagnosed as carriers of P. falciparum parasites, from four localities: Porto Velho in Rondonia State and Maraba, Itaituba, and Tailandia in Pará State. Distribution of P. falciparum in vitro chloroquine resistance in the isolates was 100% for pfmdr1, cg2 gamma region, and pfcrt, except for the polymorphism in the cg2 kappa region, which was not found.
Melhorias nas propriedades químicas de um solo salino-sódico e rendimento de arroz, sob diferentes tratamentos
Authors: Gomes Everaldo Mariano , Gheyi Hans Raj , Silva Ênio Farias de França e
Published: November 2006

Instalou-se um experimento num solo salino-sódico no Perímetro Irrigado de São Gonçalo, com o objetivo de se avaliar o efeito de diferentes produtos condicionadores nas propriedades químicas do solo e seus reflexos nos componentes de produção e rendimento de grãos na cultura de arroz irrigado (Oryza sativa L.). O delineamento experimental foi inteiramente casualizado, com cinco tratamentos e cinco repetições. Os tratamentos estudados foram: gesso (20 Mg ha-1); casca de arroz (15 Mg ha-1); testemunha; vinhaça (40 m³ ha-1) e esterco de curral (40 Mg ha-1). Após aplicação dos tratamentos, o solo foi lixiviado durante 40 dias, mantendo uma lâmina de 8 cm de água nas parcelas. Os tratamentos mostraram efeitos positivos nas propriedades químicas do solo (percentagem de sódio trocável, condutividade elétrica do extrato de saturação e pH da pasta saturada) sendo que o esterco de curral e gesso proporcionaram apreciáveis decréscimos em comparação aos outros tratamentos; entretanto, os produtos utilizados não mostraram efeitos significativos no número de panículas, peso de panículas e rendimento do arroz.
Níveis adequados e tóxicos de zinco na produção de arroz, feijão, milho, soja e trigo em solo de cerrado
Authors: Fageria Nand Kumar
Published: November 2006

Foram conduzidos cinco experimentos em casa de vegetação, para determinação das doses e dos teores adequados e tóxicos de Zn no solo e na planta para as culturas de arroz de terras altas, feijão, milho, soja e trigo. Os tratamentos com Zn foram de 0, 5, 10, 20, 40, 80 e 120 mg de Zn kg-1 de solo. Considerando 90% da produção relativa de matéria seca como parâmetro de determinação das dosagens adequadas de Zn no solo e na planta, recomenda-se para arroz, feijão, milho, soja e trigo aplicação de 10, 1, 3, 2 e 1 mg de Zn kg-1 de solo, respectivamente. Os níveis tóxicos de Zn no solo obtidos com base na redução de 10% na produção foram de 70, 57, 110, 59 e 40 mg Zn kg-1 de solo, respectivamente para arroz, feijão, milho, soja e trigo e conforme a análise do solo pelo extrator Mehlich 1, os níveis adequados de Zn no solo para as citadas culturas foram de 5, 0,7, 2, 0,8 e 0,5 mg Zn kg-1, respectivamente. Pelo extrator DTPA, os níveis adequados de Zn no solo foram de 4 mg kg-1 para o arroz, 1 mg kg-1 para o milho e de 0,3 mg kg-1 para soja, feijão e trigo. A toxidez de zinco no solo com Extrator Mehlich 1 variou de 25 a 94 mg Zn kg-1 e, com extrator DTPA, de 25 a 60 mg Zn kg-1, dependendo da cultura. Os níveis adequados na planta variaram de 18 a 67 mg Zn kg-1 e os tóxicos variaram de 100 a 673 mg Zn kg-1, dependendo da cultura.
Potencialidades da metacaolinita e do tijolo queimado moído como substitutos parciais do cimento Portland
Authors: Farias Filho João de , Rolim Joselma Santos , Toledo Filho Romildo Dias
Published: November 2006

Avalia-se, neste trabalho, a potencialidade do uso da metacaolinita e dos resíduos de produção de tijolos cerâmicos queimados finamente moídos, como substitutos parciais do cimento Portland. Os materiais foram caracterizados física, química e mineralogicamente, além de determinado o índice de atividade pozolânica com cimento Portland. A evolução da resistência a compressão e a flexão das argamassas foi avaliada até as idades de, respectivamente, 365 e 208 dias. As porcentagens de substituição do cimento Portland, em peso, pelos materiais pozolânicos, variaram de 20 a 50%, enquanto o fator água/cimento variou de 0,37 a 0,45. Os resultados obtidos indicaram que a metacaolinita e o tijolo moído queimado possuem elevada atividade pozolânica e que a resistência a compressão, aos 28 dias, das argamassas mistas, foi superior à das argamassas de cimento Portland para os níveis de substituição e fatores água/cimento estudados. Um modelo matemático para predição da resistência à compressão das argamassas mistas é proposto com base em um desenho fatorial de experimentos.
Recursos hídricos, agricultura irrigada e meio ambiente
Authors: Paz Vital Pedro da Silva , Teodoro Reges Eduardo Franco , Mendonça Fernando Campos
Published: November 2006

Reconhece-se cada vez mais a crescente falta de água para irrigação e outros usos. Também, está-se consciente de que, por sua irregular disponibilidade, a qual varia marcadamente ao longo do ano, de ano a ano e de região a região, o uso da água de forma contínua e indefinida, torna-se impossível. Portanto, uma das metas estratégicas para a preservação da disponibilidade e da qualidade dos recursos hídricos consiste em se estabelecer critérios de uso adequado em todas as atividades produtivas, razão pela qual este trabalho aborda a escassez de água, a agricultura irrigada e o meio ambiente, com base em informações e estudos que possam contribuir para o direcionamento de uma agricultura planejada, conservando e otimizando os recursos naturais. Os modelos tecnológicos propostos devem considerar um rigoroso equilíbrio entre produção agrícola e preservação dos recursos naturais. O desenvolvimento atual da irrigação depende de procedimentos tecnológicos e econômicos para otimizar o uso da água, melhorar a eficiência de aplicação, proporcionar ganhos de produtividade baseados na resposta da cultura à aplicação de água e outros insumos, sem que comprometa a disponibilidade e a qualidade do recurso.
Prediction of pollutant movement in a regulated large river
Authors: Rim C.-S. , Lee J.-T. , Yoon S.-E. , Shin J.-K.
Published: November 2006

The major purpose of this study is to find out how possible it is to predict long-term river water quality variation using the coupled water quality prediction model in the lower reach of the River Geum from Daechung Dam, South Korea. The Water Quality Analysis Simulation Program 5 (WASP5) and Hydrologic Engineering Centre (HEC-2) models have been coupled and applied to find the possibility of simulation of long-term river water quality variation. The chlorophyll-a concentration in the main river was estimated by changing the PO4−P and/or NH3−N concentrations flowing from tributaries. The study results show that the trend of longitudinal variation of simulated water quality variables is consistent with that of measured water quality variables. The variation of chlorophyll-a concentration in the main river was almost negligible except when both NH3−N and PO4−P concentrations from Gab stream and Miho stream are decreased by about 70%. Based on the study results, it can be concluded that the coupled water quality prediction model is highly applicable to this regulated large river for water quality management.
On chromium direct ETAAS determination in serum and urine
Authors: Todorovska Nadica , Karadjova Irina , Arpadjan Sonja , Stafilov Trajce
Published: November 2006

A simple, accurate and reliable method for direct electrothermal atomic absorption spectrometric (ETAAS) determination of chromium in serum and urine samples without any preliminary sample pretreatment is described. Instrumental parameters are optimized in order to define: the most suitable atomizer, optimal temperature program and efficient modifier. An appropriate quantification method is proposed taking into account a matrix interference study. Pyrocoated graphite tubes and wall atomization, pretreatment temperature of 700 °C, atomization temperature of 2600 °C, hydrogen peroxide as modifier and standard addition calibration are recommended. The accuracy of the method proposed for Cr determination in serum and urine was confirmed by comparative analysis of parallel samples after wet or dry ashing as well as by the analysis of two certified reference materials: Serum, Clin Rep 1 and Lypochek Urine, level 1. The detection and determination limits achieved for both matrices are 0.08 µg/L and 0.15 µg/L respectively. The relative standard deviation varied between 15 and 18 % for the chromium content in the samples in the range 0.08–0.2 µg/L and between 4 and 7 % for the chromium content in the range 0.2–2.0 µg/L for both matrices.
Study of flocculation with PONILIT GT-2 anionic polyelectrolyte applied into a chemical wastewater treatment
Authors: Zaharia Carmen , Diaconescu Rodica , Surpăţeanu Mioara
Published: November 2006

This paper discusses the applications of synthetic PONILIT GT-2 anionic polyelectrolyte in conjuction with ferric sulfate in a chemical wastewater treatment viz. wastewater from ceramics manufacturing. Synthetic wastewaters with different colloid concentrations were prepared and the coagulation-flocculation process followed by sedimentation and/or filtration was studied. Variables associated with the chemical wastewater composition, mixing time, and the coagulant and flocculant dose are considered in order to appreciate the process efficiency in terms of turbidity, chemical oxygen demand (COD), and color removal. The degrees are higher for turbidity and color (> 80 %) removal respectively, and, satisfactory for COD (3 type, considering ferric sulfate dose, polyelectrolyte dose, and mixing time as independent variables, while the turbidity and color removal efficiencies were chosen as optimization criteria. The empirical model was found adequate for the chemical wastewater treatment. Also, an analysis of the model was performed to find the optimal operating conditions, in order to apply this process for an efficient chemical wastewater treatment using ferric sulfate as coagulation agent and PONILIT GT-2 anionic polyelectrolyte as flocculation agent. The optimal values correspond to a ferric ions concentration of 6.093 mg/L, a polyelectrolyte dose of 0.651 mg/L, and a mixing time of 24.024 minutes for turbidity removal (95.869 %), respectively, and, to a ferric ions concentration of 6.01 mg/L, a polyelectrolyte dose of 0.69 mg/L, and a mixing time of 26 minutes for color removal (98.741 %).
Ab-initio calculation of band structure and linear optical properties of SbSI in para- and ferroelectric phases
Authors: Akkus Harun , Mamedov Amirullah
Published: November 2006

An ab-initio pseudopotential calculation has been performed by using density functional methods within the local density approximation (LDA) to investigate the band structure and optical properties of the ferroelectric-semiconductor SbSI in the para- and ferroelectric phases. It has been shown that SbSI has an indirect gap in both phases (1.45 eV and 1.49 eV in the para- and ferroelectric phases respectively) and that the smallest direct gap is at the S point of the Brillouin zone (1.56 eV and 1.58 eV in the para- and ferroelectric phases respectively). Furthermore, it is shown that first-order phase transition, from the paraelectric phase to the ferroelectric phase (the transiton temperature is about 22 °C), does not change the nature of the band gap. Moreover, the linear frequency dependent dielectric function, including self-energy effects, has been calculated along the c-polar axis in the para- and ferroelectric phases.
How induced cells of Pseudomonas sp. increase the degradation of caffeine
Authors: Gummadi Sathyanarayana , Santhosh Devarai
Published: November 2006

Decaffeination is an important process for the removal of caffeine from wastes generated by coffee and tea industries. Microbial degradation of caffeine is more useful than conventional chemical treatment because of its low cost and because it does not involve the use of toxic solvents. However, biodegradation of caffeine remains a problem because of the difficulty of finding a strain that can resist high concentration of caffeine in addition to be able to degrade caffeine at higher rates. In this study, we used the induced cells of Pseudomonas sp. for the degradation of caffeine. The induced cells (8 mg/ml) showed complete degradation of a initial concentration of caffeine of 1.2 g/l in 6 hours. The optimum pH was 7.0, the agitation rate was 180 rpm and the optimum temperature for degradation was 35 °C. Under these conditions and in the presence of magnesium, complete degradation of 1.2 g/l of caffeine was accomplished in 4 hours. Additional trials determined that induced cells completely degraded an initial concentration of caffeine of 10 g/l in 26 hours. This is the first report on a strain that can degrade high concentrations of caffeine (e.g., 10 g/l) at the maximum rate of 0.385 g/l per hour. These results suggest that the strain can be used to successfully in developing a biological process for the degradation of caffeine.
Stimulated recovery of perturbed haematopoiesis by inhibition of prostaglandin production — promising therapeutic strategy
Authors: Hofer Michal , Pospíšil Milan
Published: November 2006

Inhibitors of prostaglandin production, designated as classical non-steroidal anti-inflammatory drugs (NSAIDs) and acting on the base of non-selective inhibition of cyclooxygenases, have been found in numerous studies to potentiate recovery of perturbed haematopoiesis by removing the negative feedback control mediated by prostaglandins. However, classical NSAIDs show pronounced undesirable gastrointestinal side effects, which limits the possibility of their utilization for various pathophysiological states including myelosuppression. Specific cyclooxygenase-2 (COX-2) inhibitors, targeted at selective inhibition of this inducible cyclooxygenase isoform and having much better gastrointestinal side effect profile, have been found in recent studies to retain the haematopoiesis-stimulating effects of classical NSAIDs. These results suggest that the indication spectrum of selective COX-2 inhibitors may be extended to the indication of myelosuppression of various etiology. Combining the anti-tumour and haematopoiesis-stimulating activities in a single COX-2 inhibitor may have a positive clinical impact.
Pleural mesothelioma (PMe): The evolving molecular knowledge of a rare and aggressive cancer
Authors: Rigon Manuel , Mutti Luciano , Campanella Michelangelo
Published: March 2024

Mesothelioma is a type of late‐onset cancer that develops in cells covering the outer surface of organs. Although it can affect the peritoneum, heart, or testicles, it mainly targets the lining of the lungs, making pleural mesothelioma (PMe) the most common and widely studied mesothelioma type. PMe is caused by exposure to fibres of asbestos, which when inhaled leads to inflammation and scarring of the pleura. Despite the ban on asbestos by most Western countries, the incidence of PMe is on the rise, also facilitated by a lack of specific symptomatology and diagnostic methods. Therapeutic options are also limited to mainly palliative care, making this disease untreatable. Here we present an overview of biological aspects underlying PMe by listing genetic and molecular mechanisms behind its onset, aggressive nature, and fast‐paced progression. To this end, we report on the role of deubiquitinase BRCA1‐associated protein‐1 (BAP1), a tumour suppressor gene with a widely acknowledged role in the corrupted signalling and metabolism of PMe. This review aims to enhance our understanding of this devastating malignancy and propel efforts for its investigation.
RIP140 regulates transcription factor HES1 oscillatory expression and mitogenic activity in colon cancer cells
Authors: Sfeir Nour , Kajdan Marilyn , Jalaguier Stéphan , Bonnet Sandrine , Teyssier Catherine , Pyrdziak Samuel , Yuan Rong , Bousquet Emilie , Maraver Antonio , Bernex Florence , Pirot Nelly , Boissière‐Michot Florence , Castet‐Nicolas Audrey , Lapierre Marion , Cavaillès Vincent
Published: March 2024

The transcription factor receptor‐interacting protein 140 (RIP140) regulates intestinal homeostasis and tumorigenesis through Wnt signaling. In this study, we investigated its effect on the Notch/HES1 signaling pathway. In colorectal cancer (CRC) cell lines, RIP140 positively regulated HES1 gene expression at the transcriptional level via a recombining binding protein suppressor of hairless (RBPJ)/neurogenic locus notch homolog protein 1 (NICD)‐mediated mechanism. In support of these in vitro data, RIP140 and HES1 expression significantly correlated in mouse intestine and in a cohort of CRC samples, thus supporting the positive regulation of HES1 gene expression by RIP140. Interestingly, when the Notch pathway is fully activated, RIP140 exerted a strong inhibition of HES1 gene transcription controlled by the level of HES1 itself. Moreover, RIP140 directly interacts with HES1 and reversed its mitogenic activity in human CRC cells. In line with this observation, HES1 levels were associated with a better patient survival only when tumors expressed high levels of RIP140. Our data identify RIP140 as a key regulator of the Notch/HES1 signaling pathway, with a dual effect on HES1 gene expression at the transcriptional level and a strong impact on colon cancer cell proliferation.
Dual‐Wavelength Vat Photopolymerization 3D Printing with Hybrid Acrylate‐Epoxy Resins: Influence of Resin Composition on Microstructure and Mechanical Properties
Authors: Cazin Ines , Plevová Kateřina , Alabiso Walter , Vidović Elvira , Schlögl Sandra
Published: March 2024

Dual‐wavelength vat photopolymerization 3D printing represents a convenient technology for the fabrication of objects with heterogeneous and locally controlled mechanical properties. By using two λ‐orthogonal cross‐linking reactions, it is possible to produce soft and stiff photopolymers with a single resin vat by switching the light source. Herein, hybrid acrylate‐epoxy resins are selectively cured by using either visible or UV light. At 405 nm, a free radical curing of the acrylate monomers is induced while irradiation with 365 nm triggers an additional cationic ring opening reaction of the epoxy monomer yielding interpenetrating photopolymer networks. In a comprehensive approach, the influence of the resin composition and the applied wavelength on cure kinetics, film morphology, (thermo)mechanical properties, and printability are studied. Fully separated as well as homogenous network morphologies are obtained depending on the ratio between acrylate and epoxy monomers, cure rate and applied light source (405 vs 365 nm). In general, glass transition temperature, stiffness, and tensile strength of the photopolymers increase with rising epoxy content. In contrast, a higher epoxy concentration in combination with a higher amount of the cationic photoinitiator compromises on the system's orthogonality, giving rise to the important role of the resin composition in dual‐wavelength vat photopolymerization 3D printing.
Hybrid Epoxy Composites Based on Basalt Fabric: A Case Study of Low‐Temperature Plasma Treatment and Reduced Graphene Oxide Flakes Addition
Authors: Marynowicz Stefan , Romanowska Agata , Baran Magdalena , Strachowski Tomasz , Możdżyńska Ewelina B. , Chlanda Adrian
Published: March 2024

The purpose of this study is to present a novel method for producing mechanically strong epoxy composite laminates of different compositions, reinforced with basalt fabric and reduced graphene oxide flakes. The laminates are prepared with basalt fabric, which is subjected to low‐temperature plasma treatment. This approach is aimed to enhance the adhesion of fabric to resin filled with reduced graphene oxide flakes. Physical properties, adhesion, and mechanical properties of the obtained materials are determined. Based on the experiments, it is found that the tensile strength is improved by 6–21% after using reduced graphene oxide filler, 9–23% after plasma treatment, and up to 27% using the combination of plasma and reduced graphene. It is found that the highest improvement of tensile strength is obtained for epoxy composite with 0.5 wt% graphene‐based filler and 3 min basalt fiber plasma treatment with 25 W plasma power.
Longitudinal Magnetic Resonance Imaging with ROS‐Responsive Bilirubin Nanoparticles Enables Monitoring of Nonalcoholic Steatohepatitis Progression to Cirrhosis
Authors: Jung Wonsik , Asaduddin Muhammad , Keum Hyeongseop , Son Youngju , Yoo Dohyun , Kim Dohyeon , Lee Seojung , Lee Dong Yun , Roh Jin , Park Sung‐Hong , Jon Sangyong
Published: March 2024

Despite the vital importance of monitoring the progression of nonalcoholic fatty liver disease (NAFLD) and its progressive form, nonalcoholic steatohepatitis (NASH), an efficient imaging modality that is readily available at hospitals is currently lacking. Here, a new magnetic‐resonance‐imaging (MRI)‐based imaging modality is presented that allows for efficient and longitudinal monitoring of NAFLD and NASH progression. The imaging modality uses manganese‐ion (Mn2+)‐chelated bilirubin nanoparticles (Mn@BRNPs) as a reactive‐oxygen‐species (ROS)‐responsive MRI imaging probe. Longitudinal T1‐weighted MR imaging of NASH model mice is performed after injecting Mn@BRNPs intravenously. The MR signal enhancement in the liver relative to muscle gradually increases up to 8 weeks of NASH progression, but decreases significantly as NASH progresses to the cirrhosis‐like stage at weeks 10 and 12. A new dual input pseudo‐three‐compartment model is developed to provide information on NASH stage with a single MRI scan. It is also demonstrated that the ROS‐responsive Mn@BRNPs can be used to monitor the efficacy of potential anti‐NASH drugs with conventional MRI. The findings suggest that the ROS‐responsive Mn@BRNPs have the potential to serve as an efficient MRI contrast for monitoring NASH progression and its transition to the cirrhosis‐like stage.