排序方式: 共有123条查询结果,搜索用时 15 毫秒
41.
José Mauro Granjeiro Carmen Verissima Ferreira Paulo Afonso Granjeiro Cinthia Celestino Da Silva Eulázio Mikio Taga Pedro Luiz Onofre Volpe 《Journal of enzyme inhibition and medicinal chemistry》2013,28(5):345-350
Uric acid inhibited 50% of the activity of bovine kidney low molecular mass phosphotyrosine protein phosphatase at concentrations of 1.0, 0.4, 1.3, and 0.2 mM, respectively for p -nitrophenyl phosphate (p -NPP), flavine mononucleotide, β -naphthyl phosphate and tyrosine phosphate (Tyr-P) as substrates. The mixed type inhibition of p -NPP hydrolysis was fully reversible, with K ic and K iu values of 0.4 and 1.1 mM, respectively; the inhibition by uric acid shifted the pH optimum from 5.0 to 6.5. When Tyr-P was the substrate, competitive inhibition was observed with a K i value of 0.05 mM. Inhibition studies by uric acid in the presence of thiol compounds, and preincubation studies in the presence of inorganic phosphate suggest that the interaction of uric acid with the enzyme occurred at the active site, but did not involve SH residues, and that the mechanism of inhibition depended on the structure of the substrates. 相似文献
42.
A key issue to be taken into account in any mining operation or premises is workers’ health and safety. Noise has negative repercussions on workers’ health, which is why regular inspections of noise levels are necessary to ensure that noise is less than legally permitted limits. In our study we statistically analyzed functional data with a view to determining noise levels in an aggregates plant. Data were captured by a sound level meter that indicated equivalent sound pressure levels and peaks and the octave bands for a specific range of frequencies. Unlike the methods habitually used to construct noise maps (which only permit one of these parameters to be determined for each point), the methods applied in our research enable the noise level to be calculated at each point for the entire spectrum of frequencies picked up by a sound level meter. For each point we obtain, rather than a single value, a noise curve reflecting the entire range of frequencies detected by the sound level meter. This enables us to better understand the effects of noise and to determine its origin. 相似文献
43.
Jesús Adolfo Jiménez Nieves Alonso-Blázquez Dolores López-Vela Cristina Celestino Mariano Toribio Jesus Alegre 《In vitro cellular & developmental biology. Plant》2011,47(5):578-588
Somatic embryogenesis can be induced in the leaves of cork oak (Quercus suber L.) trees. The use of this propagation system in multivarietal forestry requires the mass production of cloned plants at
low cost. Investigations were made into the influence of three types of Erlenmeyer flask and three orbiting speeds (60, 110,
and 160 rpm) on oxygen transfer rate (KL
a), the shear force index (SFI), biomass production, and the proliferation of embryogenic clumps (EMCs) in cultures during
the proliferation phase. KL
a varied between 0.11 and 1.47 h−1 without biomass production being limited by oxygen availability. The EMCs grew even in hypoxic conditions, although the suppression
of gaseous exchange strongly reduced biomass production. Cultures with different levels of hydrodynamic stress and SFI values
(1.4·10−3–8.8·10−3 cm min−1) were obtained. Proliferation rates of EMCs increased with agitation rate and the SFI. The largest number of EMCs was obtained
in baffled flasks agitated at 160 rpm (KL
a of 1.47 h−1, and SFI of 8.8·10−3 cm min−1) with mild hydrodynamic stress enhancing growth. Biomass production increased with agitation and hydrodynamic stress, but
only when the SFI value was below 5·10−3 cm min−1. The greatest biomass production was obtained in smooth 100 ml flasks agitated at 160 rpm. The differentiation of embryos
was favoured by the lowest KL
a (0.11 h−1) and SFI (1.40·103 cm min−1) values, achieved using these flasks when agitated at 60 rpm. 相似文献
44.
Manuela Meireles Fátima Martel João Araújo Celestino Santos-Buelga Susana Gonzalez-Manzano Montserrat Dueñas Victor de Freitas Nuno Mateus Conceição Calhau Ana Faria 《The Journal of membrane biology》2013,246(9):669-677
The blood–brain barrier (BBB) plays a key role in limiting and regulating glucose access to glial and neuronal cells. In this work glucose uptake on a human BBB cell model (the hCMEC/D3 cell line) was characterized. The influence of some hormones and diet components on glucose uptake was also studied. 3H-2-deoxy-d-glucose ([3H]-DG) uptake for hCMEC/D3 cells was evaluated in the presence or absence of tested compounds. [3H]-DG uptake was sodium- and energy-independent. [3H]-DG uptake was regulated by Ca2+ and calmodulin but not by MAPK kinase pathways. PKC, PKA and protein tyrosine kinase also seem to be involved in glucose uptake modulation. Progesterone and estrone were found to decrease 3H-DG uptake. Catechin and epicatechin did not have any effect, but their methylated metabolites increased [3H]-DG uptake. Quercetin and myricetin decreased [3H]-DG uptake, and glucuronic acid-conjugated quercetin did not have any effect. These cells expressed GLUT1, GLUT3 and SGLT1 mRNA. 相似文献
45.
Polyphenols restore endothelial function in DOCA-salt hypertension: role of endothelin-1 and NADPH oxidase 总被引:2,自引:0,他引:2
Jiménez R López-Sepúlveda R Kadmiri M Romero M Vera R Sánchez M Vargas F O'Valle F Zarzuelo A Dueñas M Santos-Buelga C Duarte J 《Free radical biology & medicine》2007,43(3):462-473
Red wine polyphenols (RWPs) have been reported to exert beneficial effects in preventing cardiovascular diseases, such as hypertension. We studied the effects of chronic treatment with RWPs and apocynin, an inhibitor of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, on blood pressure, endothelial function, and oxidative status in deoxycorticosterone acetate (DOCA)-salt-induced hypertension. Rats were administered RWPs (40 mg/kg) or apocynin (33 microg/kg) daily by gavage for 5 weeks. Plasma catechin levels were detected only after RWP treatment. RWPs and apocynin prevented both the increase in systolic blood pressure and the proteinuria induced by DOCA-salt. Plasma malonyldialdehyde levels, urinary iso-prostaglandin F(2alpha) excretion, aortic superoxide production, and aortic NADPH oxidase activity were found to be increased in animals of the DOCA group. RWP and apocynin treatments reduced these parameters in DOCA-salt rats, having no effect on control rats. However, only RWPs reduced the increase in plasma endothelin-1 (ET-1) levels and aortic p22(phox) gene overexpression found in DOCA-salt animals. RWPs and apocynin also improved the blunted endothelium-dependent relaxation response to acetylcholine in noradrenaline-precontracted aortic rings. All these results suggest that chronic treatment with RWPs prevents hypertension and vascular dysfunction. RWPs prevent vascular oxidative stress by inhibiting NADPH oxidase activity and/or by reducing ET-1 release. 相似文献
46.
Azahara Barra-Jiménez Miquel Blasco Mar Ruiz-Galea Cristina Celestino Jesús Alegre Isabel Arrillaga Mariano Toribio 《Trees - Structure and Function》2014,28(3):657-667
Key message
Integuments from holm oak developing ovules were suitable initial explants to obtain embryogenic lines from which plants could be regenerated.Abstract
The implementation of multivarietal forestry as part of breeding strategies is expected to provide more productive forest plantations. To achieve this, a reliable and effective method for mass production of clonal plants is needed. Somatic embryogenesis is considered the enabling technology for implementing multivarietal forestry. The holm oak (Quercus ilex L.) is a Mediterranean evergreen tree of economic interests because of the acorn production for animal feed and edible fungi mycorrhization. The aim of this work was to obtain clonal plants by inducing somatic embryogenesis in tissues of female flowers from mature trees. The influence of the developmental stage of the explant, the genotype and medium composition, and the effect of arabinogalactan proteins on the induction frequency, were assessed. Somatic embryogenesis induction (frequency ranging from 1.2 to 3.2 %) was restricted to ovules excised at an advanced stage of development, when they were at least 3–4 mm wide and the rest of the ovules within the ovary had aborted. Somatic embryos arose from the integuments of those fertilized ovules. Embryogenic response was obtained on media with and without plant growth regulators. All the genotypes that were cultured on medium containing “as reported by Schenk and Hildebrandt (Can J Bot 50:199–204, 1972)” SH macronutrients could be captured. Treatments including Larix arabinogalactan proteins did not improve induction, while those from Acacia inhibited the embryogenic response. Several embryogenic lines were multiplied by repetitive embryogenesis on medium lacking plant growth regulators. Mature somatic embryos of three genotypes were germinated at frequencies ranging from 41 to 58 %, and converted into plants at frequencies from 11 to 30 %, depending on the genotype. 相似文献47.
48.
Muhammad Ntale Celestino Obua Jackson Mukonzo Margarita Mahindi Lars L Gustafsson Olof Beck Jasper W Ogwal-Okeng 《Malaria journal》2009,8(1):1-5
Background
Malaria remains a major public health problem in Ethiopia. Pyrethroid-treated mosquito nets are one of the major tools available for the prevention and control of malaria transmission. PermaNet® is a long-lasting insecticide-treated net (LLIN) recommended by WHO for malaria control.Objective
The objective of the study was to assess utilization and retention of PermaNet® nets distributed for malaria control in Buie and Fentalie districts and monitor the bio-efficacy of the nets using the WHO cone bioassay test procedures.Methods
A cross sectional study was carried out by interviewing household heads or their representative in Buie and Fentalie districts. The two districts were selected based on a priori knowledge of variations on ethnic background and housing construction. Clusters of houses were chosen within each of the study villages for selection of households. 20 households that had received one or more PermaNet® nets were chosen randomly from the clusters in each village. A total of eight used PermaNet® nets were collected for the bio-efficacy test. The bio-efficacy of PermaNet® nets was monitored according to the standard WHO procedures using a susceptible colony of Anopheles arabiensis to deltamethrin.Results
A total of 119 household heads were interviewed during the study. The retention rate of nets that were distributed in 2005 and 2006 season was 72%. A total of 62.2% of the interviewees claimed children under five years of age slept under LLIN, while only 50.7% of the nets were observed to be hanged inside houses when used as a proxy indicator of usage of LLIN. For the bio-efficacy test the mean knock-down was 94% and 100%, while the mean mortality rate observed after 24 hr holding period was 72.2% and 67% for Buie and Fentalie districts respectively.Conclusion
The study revealed a moderately high retention of PermaNet® in the study villages and effectiveness of the nets when tested according to the standard WHO procedure. 相似文献49.
Sanchez I Garcia-Nuñez M Ragull S Sopena N Pedro-Botet ML Estere M Rey-Joly C Sabria M Esteve M 《Environmental microbiology》2008,10(2):395-399
Genotypic variability and clonal persistence are important concepts in molecular epidemiology as they facilitate the search for the source of sporadic cases or outbreaks of legionellosis. We studied the genotypic variability and persistence of Legionella pulsed-field gel electrophoresis (PFGE) patterns over time (period > 6 months) in 34 positive cooling towers from two different areas. In area A, radius of 70 km, 52 indistinguishable PFGE patterns were differentiated among the 27 cooling towers. In 13 cooling towers we observed ≥ 2 PFGE patterns. Each cooling tower had its own indistinguishable Legionella PFGE pattern which was not shared with any other cooling tower. In area B, radius of 1 km, 10 indistinguishable PFGE patterns were obtained from the seven cooling towers. In four, we observed ≥ 2 PFGE patterns. Three of these 10 indistinguishable PFGE patterns were shared by more than one cooling tower. In 27 of 34 cooling towers the same PFGE pattern was recovered after 6 months to up to 5 years of follow-up. The large genotypic diversity of Legionella observed in the cooling towers aids in the investigation of community outbreaks of Legionnaires' disease. However, shared patterns in small areas may confound the epidemiological investigation. The persistence of some PFGE patterns in cooling towers makes the recovery of the Legionella isolate causing the outbreak possible over time. 相似文献
50.