RESUMEN
In an effort to develop the biomimetic chemistry of [FeFe]hydrogenases for catalytic hydrogen evolution reaction (HER) in aqueous environment, we herein report the integrations of diiron dithiolate complexes into carbon nanotubes (CNTs) through three different strategies and compare the electrochemical HER performances of the as-resulted 2Fe2S/CNT hybrids in neutral aqueous medium. That is, three new diiron dithiolate complexes [{(µ-SCH2)2N(C6H4CH2C(O)R)}Fe2(CO)6] (R = N-oxylphthalimide (1), NHCH2pyrene (2), and NHCH2Ph (3)) were prepared and could be further grafted covalently to CNTs via an amide bond (this 2Fe2S/CNT hybrid is labeled as H1) as well as immobilized noncovalently to CNTs via π-π stacking interaction (H2) or via simple physisorption (H3). Meanwhile, the molecular structures of 1-3 are determined by elemental analysis and spectroscopic as well as crystallographic techniques, whereas the structures and morphologies of H1-H3 are characterized by various spectroscopies and scanning electronic microscopy. Further, the electrocatalytic HER activity trend of H1 > H2 ≈ H3 is observed in 0.1 M phosphate buffer solution (pH = 7) through different electrochemical measurements, whereas the degradation processes of H1-H3 lead to their electrocatalytic deactivation in the long-term electrolysis as proposed by post operando analysis. Thus, this work is significant to extend the potential application of carbon electrode materials engineered with diiron molecular complexes as heterogeneous HER electrocatalysts for water splitting to hydrogen.
Asunto(s)
Hidrógeno , Hidrogenasas , Proteínas Hierro-Azufre , Nanotubos de Carbono , Nanotubos de Carbono/química , Hidrogenasas/química , Hidrogenasas/metabolismo , Hidrógeno/química , Proteínas Hierro-Azufre/química , Proteínas Hierro-Azufre/metabolismo , Catálisis , Agua/química , Complejos de Coordinación/químicaRESUMEN
BACKGROUND: CA 19-9 is one of the most frequently used biomarkers for tumors. METHODS: We analyzed the influential factors of the Carbohydrate Antigen 19-9 (CA 19-9) levels in Chinese general population to better interpret the results of the CA 19-9 screening tests. 36,924 apparently healthy individuals and 1,335 patients with gastrointestinal (GI) tumors were involved in this study. Serum CA 19-9 levels were measured using a Roche Cobas E601. RESULTS: The serum CA 19-9 levels in apparently healthy individuals were correlated with age and gender. Its level was positively correlated with the age of males, while it showed a V-shape curve in female populations. This effect could be due to sex hormones, such as prolactin, which were found to have a negative effect on the level of CA 19-9 in the present study. CONCLUSIONS: Our data indicates that gender and age could affect the CA19-9 serum level. We can set up different cut-off values according to the patient's gender and age, which can help us to get a more individualized representation in different populations.
Asunto(s)
Biomarcadores de Tumor/sangre , Antígeno CA-19-9/sangre , Adolescente , Adulto , Anciano , China , Femenino , Humanos , Masculino , Persona de Mediana Edad , Adulto JovenRESUMEN
The causes of meningiomas are not well understood. Folate metabolism gene polymorphisms have been shown to be associated with various human cancers. It is still controversial and ambiguous between the functional polymorphisms of folate metabolism genes 5,10-methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTRR), and methionine synthase reductase (MTR) and risk of adult meningioma. A population-based casecontrol study involving 600 meningioma patients (World Health Organization [WHO] Grade I, 391 cases; WHO Grade II, 167 cases; WHO Grade III, 42 cases) and 600 controls was done for the MTHFR C677T and A1298C, MTRR A66G, and MTR A2756G variants in Chinese Han population. The folate metabolism gene polymorphisms were determined by using a polymerase chain reactionrestriction fragment length polymorphism assay. Meningioma cases had a significantly lower frequency of MTHFR 677 TT genotype [odds ratio (OR) = 0.49, 95 % confidence interval (CI) 0.330.74; P = 0.001] and T allele (OR = 0.80, 95 % CI 0.670.95; P = 0.01) than controls. A significant association between risk of meningioma and MTRR 66 GG (OR = 1.41, 95 % CI 1.021.96; P = 0.04) was also observed. When stratifying by the WHO grade of meningioma, no association was found. Our study suggested that MTHFR C677T and MTRR A66G variants may affect the risk of adult meningioma in Chinese Han population.
Asunto(s)
5-Metiltetrahidrofolato-Homocisteína S-Metiltransferasa/genética , Ferredoxina-NADP Reductasa/genética , Neoplasias Meníngeas/genética , Meningioma/genética , Metilenotetrahidrofolato Reductasa (NADPH2)/genética , Polimorfismo de Nucleótido Simple/genética , Adulto , Estudios de Casos y Controles , China/epidemiología , Femenino , Estudios de Seguimiento , Genotipo , Humanos , Masculino , Neoplasias Meníngeas/epidemiología , Neoplasias Meníngeas/patología , Meningioma/epidemiología , Meningioma/patología , Persona de Mediana Edad , Clasificación del Tumor , Reacción en Cadena de la Polimerasa , Polimorfismo de Longitud del Fragmento de Restricción , Pronóstico , Factores de RiesgoRESUMEN
OBJECTIVE: To investigate the effects of silencing the expression of mutant p53 gene with RNA interference technique on biological behavior of gastric cancer SGC7901 cells. METHODS: Recombinant plasmid of mutant p53 gene-targeting siRNA was transfected into gastric cancer SGC7901 cells by Lipofectamine(TM)2000. The expressions of mutant p53 gene mRNA and protein were identified by RT-PCR and Western blot assay. The proliferation of SGC7901 cells and changes of Oxaliplatin (OXA) drug sensitivity were detected by MTT assay. The cell cycle distribution and apoptosis rate were analyzed by flow cytometry. Changes in cell tumorigenicity ability were analyzed by colony formation assay and xenograft tumor formation in nude mice. RESULTS: The expression of mutant p53 in SGC7901 cells was remarkable suppressed by mutant p53-siRNA. The cell growth curve of the transfected group turned to left compared to untransfected group and control group. The cell number of G(0)/G(1) phase of transfected group was decreased by 7.4% and 6.7% respectively, and that of S phase was increased both by 17.2% compared to control group and untransfected group, and the cell apoptosis rate induced by Oxaliplatin was remarkable decreased. The IC(50) of OXA in untransfected group, control group and transfected group were 15.88 µmol/L, 14.32 µmol/L and 20.34 µmol/L respectively. The colony formation rate and tumorigenicity ability in nude mice of transfected group increased remarkably. CONCLUSION: Mutant p53-siRNA can significantly inhibit the expression of mutant p53 in SGC7901 cells, however, the use of RNA interference targeting mutant p53 gene in the treatment of gastric cancer is still uncertain.