RESUMEN
A natural phosphate rock and two synthetic mesoporous hydroxyapatites were evaluated for the removal of pyridine and phenol from aqueous solutions. Experiments performed by the batch method showed that the sorption process occurs by a first order reaction for both pyridine and phenol. In contrast, the Freundlich model was able to describe sorption isotherms for phenol but not for pyridine. In parallel, the three apatites exhibit similar pyridine sorption capacities whereas phenol loading was in agreement with their respective specific surface area. This was attributed to the strong interaction arising between pyridine and apatite surface that hinders further inter-particular diffusion. This study suggests that, despite its low specific surface area, natural phosphate rock may be used as an efficient sorbent material for specific organic pollutants, with comparable efficiency and lower processing costs than some activated carbons.
Asunto(s)
Apatitas/química , Fenol/aislamiento & purificación , Piridinas/aislamiento & purificación , Contaminantes Químicos del Agua/aislamiento & purificación , Adsorción , Apatitas/economía , Costos y Análisis de Costo , Fosfatos , Porosidad , Propiedades de SuperficieRESUMEN
In order to analyze dexamethasone effects on peripheral blood lymphocyte proliferation, we defined various experimental conditions: dexamethasone introduced (i) at the time of phytohemagglutinin stimulation, (ii) 48 h after the beginning of phytohemagglutinin stimulation, and (iii) on unstimulated lymphocytes. In stimulated lymphocytes, we observed an early G1 accumulation (P < 0.005), a delayed increase in the duration of S-phase (P < 0.03), and a consequent increase in cell-cycle duration. The expression of several cyclins, cyclin-dependent kinases (CDKs), and CDK inhibitors (CKIs) was modified. Cyclin D3, CDK4, and CDK6 involved in G1-phase control were significantly decreased under dexamethasone treatment whatever the level of stimulation of lymphocytes (stimulated or unstimulated PBL). Cyclin E and CDK2, acting in G1/ S-phase transition and S-phase regulation, decreased in stimulated lymphocytes before any modification of S-phase (P < 0.002). The expression of CKIs, mainly of p27Kip1, appeared to vary with the degree of cell stimulation: a decrease was observed on treated unstimulated lymphocytes, while p27Kip1 increased in dexamethasone-treated cells during stimulation. Our results indicate sequential modifications of the cell-cycle regulation by dexamethasone starting with an action on G1 followed by S-phase control modifications. The protein analysis pinpoints the major complexes concerned: CDK4 and CDK6/cyclin D are mainly involved in G1-phase modifications, while CDK2 and its partner, cyclin E, might be specifically involved in the lengthening of S-phase. The variations observed for p27Kip1 might amplify the functional effects of dexamethasone on kinasic complexes.
Asunto(s)
Quinasas CDC2-CDC28 , Proteínas de Ciclo Celular/metabolismo , Dexametasona/farmacología , Glucocorticoides/farmacología , Inhibidores de Crecimiento/farmacología , Linfocitos/efectos de los fármacos , Proteínas Proto-Oncogénicas , Proteínas Supresoras de Tumor , Apoptosis , Proteína Quinasa CDC2/metabolismo , Diferenciación Celular , Células Cultivadas , Ciclina D3 , Ciclina E/metabolismo , Quinasa 2 Dependiente de la Ciclina , Quinasa 4 Dependiente de la Ciclina , Quinasa 6 Dependiente de la Ciclina , Inhibidor p16 de la Quinasa Dependiente de Ciclina/metabolismo , Inhibidor p27 de las Quinasas Dependientes de la Ciclina , Quinasas Ciclina-Dependientes/metabolismo , Ciclinas/metabolismo , Fase G1 , Humanos , Linfocitos/metabolismo , Proteínas Asociadas a Microtúbulos/metabolismo , Mitógenos/farmacología , Fitohemaglutininas/farmacología , Proteínas Serina-Treonina Quinasas/metabolismo , Fase SRESUMEN
An automated kinetic method for assaying ethylene glycol in serum using glycerol dehydrogenase with the multiparametric analyzer Cobas Mira is described. Initially, 5 microL of sample is mixed with tris-NAD buffer; after enzyme addition, the variation of the absorbance at 340 nm is automatically measured, and the instrument calculates the ethylene glycol concentration of the specimen. The method has good precision and specificity and is suitable for emergency screening. Some applications developed in our laboratory are also described.