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1.
Heliyon ; 10(13): e32883, 2024 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-39035531

RESUMO

Leveraging governance structures: Shaping Power Relations and Decision-Making Processes within Organizations. While traditional governance approaches tend to favor hierarchical structures with concentrated authority, the growing demand for increased stakeholder engagement and empowerment has spurred the emergence of innovative governance models. This article examines traditional and evolving governance approaches in major United States professional sports leagues-the National Football League (NFL), Major League Baseball (MLB), National Basketball Association (NBA), and National Hockey League (NHL). Through a review of literature and governance documents, the traditional hierarchal models of the NFL and MLB are analyzed. Their incremental shifts toward more inclusive structures are also explored. In contrast, the NBA's adoption of a franchise model with decentralized authority and the NHL's establishment of a Players' Association are examined as examples of governance innovation. The impacts of these evolving approaches are considered in the context of league operations, labor relations, and overall stakeholder interest representation. This paper shows insights into the dynamics of governance change and the factors influencing shifts toward more collaborative and empowering structures within professional sports organizations.

2.
Zhonghua Nan Ke Xue ; 15(3): 207-11, 2009 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-19452690

RESUMO

OBJECTIVE: To investigate the effects of phytoestrogens (daidzein and genistein) on the testosterone production of rat Leydig cells and the possible mechanisms. METHODS: Primary Leydig cells were obtained from 3-month old male SD rats using discontinuous Percoll density gradient centrifugation. The effects of phytoestrogens at various concentrations were evaluated by ELISA, with hCG as the positive control. The mRNA expression of P450 side-chain cleavage enzyme (P450scc) was analyzed by semi-quantitative RT-PCR. RESULTS: Genistein at 0.1 micromol/L obviously promoted the secretion of testosterone and upregulated the mRNA level of P450scc. At a higher concentration of 5 micromol/L, however, both daidzein and genistein significantly inhibited the testosterone production of Leydig cells (P > 0.05). CONCLUSION: Genistein can promote the testosterone production of Leydig cells at a low concentration (0.1 micromol/L), but both daidzein and genistein can inhibit it at a higher concentration ( >5 micromol/L).


Assuntos
Células Intersticiais do Testículo/efeitos dos fármacos , Células Intersticiais do Testículo/metabolismo , Fitoestrógenos/farmacologia , Testosterona/biossíntese , Animais , Células Cultivadas , Genisteína/farmacologia , Isoflavonas/farmacologia , Masculino , Ratos , Ratos Sprague-Dawley
3.
J Chromatogr Sci ; 46(8): 751-6, 2008 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-18796236

RESUMO

A method for the determination of metolcarb and diethofencarb in apples and apple juice is developed using solid-phase microextraction (SPME) coupled with high-performance liquid chromatography (HPLC). The experimental conditions of SPME, such as the kind of extraction fiber, extraction time, stirring rate, pH of the extracting solution, and desorption conditions are optimized. The SPME is performed on a 60 microm polydimethylsiloxane/divinylbenzene fiber for 40 min at room temperature with the solution being stirred at 1100 rpm. The extracted pesticides on the SPME fiber are desorbed in the mobile phase into SPME-HPLC interface for HPLC analysis. Separations are carried out on a Baseline C18 column (4.6 i.d. x 250 mm, 5.0 microm) with acetonitrile-water (55/45, v/v) as the mobile phase at a flow rate of 1.0 mL/min, and photodiode-array detection at 210 nm. For apple samples, the method is linear for both metolcarb and diethofencarb in the range of 0.05-1.0 mg/kg (r > 0.99), with a detection limit (S/N = 3 ) of 15 and 5 microg/kg, respectively. For apple juice, the method is linear for both metholcarb and diethofencarb over the range of 0.05-1.0 mg/L (r > 0.99) with the detection limit (S/N = 3 ) of 15 and 3 microg/L, respectively. Excellent recovery and reproducibility values are achieved. The proposed method is shown to be simple, sensitive, and organic solvent-free, and is suitable for the determination of the two pesticides in apples and apple juice.


Assuntos
Bebidas/análise , Cromatografia Líquida de Alta Pressão/métodos , Malus/química , Fenilcarbamatos/análise , Calibragem , Concentração de Íons de Hidrogênio , Concentração Osmolar , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Temperatura
4.
Artigo em Inglês | MEDLINE | ID: mdl-18311622

RESUMO

A new analytical method for the determination of carbendazim (MBC) and thiabendazole (TBZ) in apples is reported, based on solid-phase microextraction (SPME) coupling HPLC with fluorescence detection. The main SPME and HPLC experimental conditions were optimized. The apples were first blended and centrifuged. Then, an aliquot of the resulting solution was subjected to SPME on a 60 microm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre for 35 min at room temperature with the solution being stirred at 1100 rev min(-1). The extracted pesticides on the SPME fibre were desorbed in the mobile phase into the SPME/HPLC interface for HPLC analysis. The method was linear over the range 0.01-1 mg kg(-1) in apples for both MBC and TBZ, with detection limits of 0.005 and 0.003 mg kg(-1) and correlation coefficients of 0.9995 and 0.9998, respectively. The average recoveries for MBC and TBZ were 91.5 and 92.3% with the relative standard deviations (RSD) of 4.7 and 4.1% at the 0.1 mg kg(-1) level, and 94.6 and 96.1% with RSD of 3.3 and 3.8% at the 0.5 mg kg(-1) level, respectively. The method is simple, sensitive, organic solvent-free and is suitable for the determination of MBC and TBZ in apples.


Assuntos
Benzimidazóis/análise , Carbamatos/análise , Contaminação de Alimentos/análise , Fungicidas Industriais/análise , Malus , Resíduos de Praguicidas/análise , Tiabendazol/análise , Cromatografia Líquida de Alta Pressão/métodos , Microextração em Fase Sólida/métodos
5.
Se Pu ; 24(5): 516-23, 2006 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-17165552

RESUMO

The liquid-phase microextraction (LPME), based on disposable hollow fiber, has been developed to be a new environmentally benign sample preparation technique which incorporate sampling, extraction and concentration into a single step. The novel technique can be easily manipulated in combination with high performance liquid chromatography, gas chromatography and capillary electrophoresis, and can provide excellent sample clean-up effect and high degree of extraction recovery and enrichment. It is proved to be simple, low-cost and virtually solvent-free. The extraction set-up, extraction mode, basic principles and recent applications of the hollow fiber-based liquid-phase microextraction are reviewed.


Assuntos
Métodos Analíticos de Preparação de Amostras/métodos , Membranas Artificiais , Cromatografia Gasosa , Cromatografia Líquida de Alta Pressão , Eletroforese Capilar , Praguicidas/análise , Preparações Farmacêuticas/análise
6.
Se Pu ; 24(4): 389-91, 2006 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-17017167

RESUMO

A simple capillary electrophoresis method was developed for the determination of levodopa and methyldopa in human serum. The effects of pH and concentration of buffer, voltage and injection time on separation were investigated. As a result, an optimized separation was obtained with a fused-silica capillary of 60.2 cm (50 cm effective length) x 75 microm i. d. in a running buffer of 40 mmol/L sodium tetraborate (pH 9.5) with an applied voltage of 22 kV at 25 degrees C. Sample introduction was performed at 3.45 kPa (0.5 psi) for 7 s and on-column detection was made with a diode array detector at 200 nm. The linear responses covered the ranges from 1.0 to 64.0 mg/L (r = 0.999 8) for methyldopa and from 1.0 to 71.0 mg/L (r = 0.999 4) for levodopa. The detection limits (S/N = 3) of methyldopa and levodopa were shown to be 0.6 mg/L and 0.8 mg/L, respectively. The recoveries for levodopa and methyldopa in human serum were between 82.8% and 88.8% with relative standard deviations between 2.10% and 2.63%.

7.
Yao Xue Xue Bao ; 41(7): 666-70, 2006 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-17007362

RESUMO

AIM: To study the interaction between strychnine and bovine serum albumin. METHODS: Fluorescence spectroscopy and ultraviolet spectroscopy were used. RESULTS: The static quenching and the non-radiation energy transfer are the two main reasons to leading the fluorescence quenching of BSA. The apparent combining constants (K(A)) between strychnine and BSA are 3.72 x 10(3) at 27 degrees C, 4.27 x 10(3) at 37 degrees C, 4.47 x 10(3) at 47 degrees C and the combining sites are 1.01 +/- 0.03. The combining distance (r = 3.795 nm) and energy transfer efficiency (E = 0.0338) are obtained by Förster's non-radiation energy transfer mechanism. CONCLUSION: The interaction between strychnine and BSA was driven mainly by hydrophobic force.


Assuntos
Soroalbumina Bovina/química , Estricnina/química , Animais , Sítios de Ligação , Bovinos , Transferência de Energia , Plantas Medicinais/química , Ligação Proteica , Sementes/química , Soroalbumina Bovina/metabolismo , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta , Estricnina/metabolismo , Strychnos nux-vomica/química , Termodinâmica
8.
J Pharm Biomed Anal ; 42(2): 272-6, 2006 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-16616824

RESUMO

A novel reversed-phase high-performance liquid chromatographic (HPLC) method has been established for the determination of a newly developed anti-cancer agent desoxyepothilone B (dEpo B) in nude mice plasma. The sample preparation involved deproteination of 200 microl of plasma sample first, followed by liquid-liquid extraction of the resultant supernatant with chloroform. The compound taxol was used as the internal standard. Chromatographic separations were carried out on a 250 mm x 4.6 mm Zorbax SB-phenyl column with acetonitrile-0.25% orthophosphoric acid (50/50, v/v) as mobile phase and UV detection at 250 nm. For dEpo B and taxol at the concentration level of 10 microg/ml in nude mice plasma, the absolute extraction recoveries were 85.3 and 87.2%, respectively. The linear quantification range of the method was 0.1-100 microg/ml in nude mice plasma with linear correlation coefficients greater than 0.999. The within-day and between-day relative standard deviations (R.S.D.s) for dEpo B at 0.5, 2.5 and 10 microg/ml levels in nude mice plasma fell in the range of 2.8-4.8 and 1.5-4.6%, and the within-day and between-day recoveries were in the range of 96.5-101.7 and 97.7-101.2%, respectively.


Assuntos
Antineoplásicos/sangue , Cromatografia Líquida de Alta Pressão/métodos , Epotilonas/sangue , Animais , Antineoplásicos/farmacocinética , Epotilonas/farmacocinética , Camundongos , Camundongos Nus , Padrões de Referência , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
9.
Se Pu ; 23(6): 581-4, 2005 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-16498985

RESUMO

A novel method for the determination of carbendazim (MBC) and thiabendazole (TBZ) in tomatoes by solid-phase microextraction (SPME) coupled with high performance liquid chromatography (HPLC) and fluorescence detection was developed. The experimental conditions of SPME, including extraction fiber, extraction time, extraction temperature, desorption time, desorption solvent, desorption mode, pH value, organic solvent and ionic strength, and HPLC conditions were optimized. The SPME for MBC and TBZ was performed on a 65 microm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre for 50 min at room temperature with the solution being stirred at 1 100 r/min. The florescence detection was made at 315 nm with excitation wavelength at 280 nm. The method is linear for MBC and TBZ over the range assayed from 0.01 to 1.0 mg/kg tomatoes with the detection limits of 0.003 mg/kg and 0. 001 mg/kg and the correlation coefficients of 0.995 8 and 0.996 7, respectively. The average recoveries for MBC and TBZ were 83.5% and 85.6% with the relative standard deviations (RSDs) of 6.5% and 3.8%, respectively. The method is fast, simple, sensitive, solvent-free and suitable for the determination of MBC and TBZ in tomatoes.


Assuntos
Benzimidazóis/análise , Carbamatos/análise , Cromatografia Líquida de Alta Pressão/métodos , Solanum lycopersicum/química , Microextração em Fase Sólida/métodos , Espectrometria de Fluorescência/métodos , Tiabendazol/análise , Benzimidazóis/química , Carbamatos/química , Reprodutibilidade dos Testes , Tiabendazol/química
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