Promoting Catalytic Performance Involving Hydrogen Spillover by Ion Exchange of Pt@A Catalysts to Regulate Reactant Adsorption.

Zeolite-encapsulated metal nanoparticle systems have exhibited interesting catalytic performances via the hydrogen spillover process, yet how to further utilize the function of zeolite supports to promote catalytic properties in such a process is still challenging and has rarely been investigated. Herein, to address this issue, the strategy to strengthen the adsorption energy of reactant onto the zeolite surface via a simple ion exchange method has been implemented. Ion-exchanged linde type A (LTA) zeolite-encapsulated platinum nanoclusters (Pt@NaA, Pt@HA, Pt@KA, and Pt@CaA) were prepared to study the influence of ion exchange on the catalytic performance in the model reaction of hydrogenation of acetophenone to 1-phenylethanol. The reaction results showed that the Pt@CaA catalyst exhibited the best catalytic activity in the series of encapsulated catalysts, and the selectivity of 1-phenylethanol approached 100%. As revealed by density functional theory (DFT) calculations and acetophenone temperature-programmed desorption (acetophenone-TPD) experiments, in comparison with introduced cations of Na+, H+, and K+, ion-exchanged Ca2+ on the zeolite maximumly enhanced the adsorption of carbonyl groups in acetophenone, playing a critical role in achieving the highest activity and excellent catalytic selectivity among the Pt@A catalysts.

Template-Guided Regioselective Encaging of Platinum Single Atoms into Y Zeolite: Enhanced Selectivity in Semihydrogenation and Resistance to Poisoning.

It is challenging to establish single metal atoms with a uniform coordination environment at targeted sites of a zeolite. In this study, single platinum atoms were selectively encaged in the six-membered rings of sodalite (SOD) cages within Y zeolite using a template-guiding strategy. During the in situ synthesis process, template molecules were designed to occupy supercages and thereby force coordinated platinum species into SOD cages. Subsequent control of the post-treatment conditions yielded the Y zeolite with selectively encaged single platinum atoms, denoted Pt@Y-SOD. The Pt@Y-SOD catalyst had good stability and excellent catalytic selectivity in the semihydrogenation reaction, and it exhibited interesting thiophene and carbon monoxide resistance in this transformation because interactions with these poisons are weakened by the configuration of the encaged single platinum atoms.

Higher homocysteine and lower betaine increase the risk of microangiopathy in patients with diabetes mellitus carrying the GG genotype of PEMT G774C.

BACKGROUND: Diabetes represents one of the greatest medical and socioeconomic threats worldwide. The pathogenesis involved is complicated. The effect of methyl donors and genetic polymorphisms in metabolic enzymes on the risk of microangiopathy in patients with diabetes is not well understood. This study investigates the association of homocysteine, choline and betaine levels and phosphatidylethanolamine N-methyltransferase (PEMT) G774C (rs12325817) genotypes with the risk of diabetes and its related microangiopathic complications. METHODS: Between January 2009 and June 2010, 184 diabetic patients and 188 non-diabetic control subjects were enrolled in the hospital-based case-control study. Serum concentrations of betaine and choline were determined by high-performance liquid chromatography (HPLC)-mass spectrometry. Serum concentrations of homocysteine were assayed using HPLC. PEMT gene mutations were detected by polymerase chain reaction and restriction fragment length polymorphism. RESULTS: After adjustment for potential confounders, serum total homocysteine had a significant dose-dependent positive association, and serum choline had an inverse association with the risks of diabetes and its microangiopathic complications (both p < 0.001). Although serum betaine was not associated with the risk of diabetes, it had a significant inverse association with diabetic microangiopathy. Compared with GG genotype, the CC genotype of PEMT G774C was associated with a decreased risk of diabetes (OR 0.559, 95% CI 0.338, 0.926) and its microangiopathy (OR 0.452, 95% CI 0.218, 0.937). CONCLUSION: The GG genotype of the PEMT G774C polymorphism, higher levels of serum homocysteine and lower levels of serum betaine are associated with an increased risk of microangiopathy in patients with diabetes.

Neck circumference as an independent predictive contributor to cardio-metabolic syndrome.

BACKGROUND: The predictive potentials of neck circumference (NC) for cardio-metabolic risks remain uncertain. The aim of this study was to investigate whether NC independently contributes to the prediction of cardio-metabolic risks beyond body mass index (BMI), waist circumference (WC) and waist to hip ratio (WHpR) in a large Chinese population. METHODS: A total of 4201 participants (2508 men and 1693 women) aged 20-85 were recruited from the Health Examination Centre between May 2009 and April 2010, anthropometric indices, biochemical and clinical parameters were measured. Receiver operating characteristic, partial correlation and logistic regression analyses were employed to evaluate the association of the anthropometric indices to cardio-metabolic risks separately by gender. RESULTS: Neck circumference was positively correlated with SBP and DBP (r=0.250 and 0.261), fasting blood glucose (FBP) (r=0.177), TG (r=0.240), TC (r=0.143) and LDL-C (r=0.088) and negatively correlated with HDL-C (r=-0.202) in males (all P<0.01). Similar results were found in females with the exception of TC. The AUCs of NC for metabolic abnormalities ranged from 0.558 (Increased LDL-C) to 0.683 (MS-rf) in men and 0.596 (Increased LDL-C) to 0.703 (MS-rf) in women (P<0.01). The NC of ≥37 cm for men and ≥33 cm for women were the best cut-off points for metabolic syndrome. The adjusted ORs (95% CIs) of NC in men and women respectively were 1.29 (1.12-1.48) and 1.44 (1.20-1.72) for metabolic syndrome risk factors (MS-rf), 1.15 (1.01-1.32) and 1.22 (1.03-1.46) for high BP, 1.16 (1.02-1.33) and 1.42 (1.18-1.71) for increased TG, and 1.26 (1.06-1.50) and 1.32 (1.06-1.65) for increased FBP; the adjusted OR of NC in women for decreased HDL-C was 1.29 (1.10-1.51). CONCLUSIONS: Neck circumference was significantly associated with cardio-metabolic risk factors and independently contributed to the prediction of cardio-metabolic risks beyond the classical anthropometric indices in adults of China.

Betaine supplement alleviates hepatic triglyceride accumulation of apolipoprotein E deficient mice via reducing methylation of peroxisomal proliferator-activated receptor alpha promoter.

BACKGROUND: Betaine is a methyl donor and has been considered as a lipotropic effect substance. But its mechanism remains unclear. Hepatic steatosis is associated with abnormal expression of genes involved in hepatic lipid metabolism. DNA methylation contributes to the disregulation of gene expression. Here we hypothesized that betaine supplement and subsequent DNA methylation modifications alter the expression of genes that are involved in hepatic lipid metabolism and hence alleviate hepatic triglyceride accumulation. METHODS: Male wild-type (WT) C57BL/6 mice (n = 6) were fed with the AIN-93 G diet. ApoE-/- mice (n = 12), weight-matched with the WT mice, were divided into two groups (n = 6 per group), and fed with the AIN-93 G diet and AIN-93 G supplemented with 2% betaine/100 g diet. Seven weeks after the intervention, mice were sacrificed. Liver betaine, choline, homocysteine concentration were measured by HPLC. Liver oxidants activity and triglyceride level were assessed by ultraviolet spectrophotometry. Finally, hepatic PPAR alpha gene and its target genes expression levels and the methylation status of the PPAR alpha gene were determined. RESULTS: ApoE-/- mice had higher hepatic triglyceride and lower GSH-Px activity when compared with the WT mice. Betaine intervention reversed triglyceride deposit, enhanced SOD and GSH-Px activity in the liver. Interestingly, mice fed on betaine-supplemented diet showed a dramatic increase of hepatic choline concentration and a decrease of betaine and homocysteine concentration relative to the WT mice and the ApoE-/- mice absent with betaine intervention. Expression of PPAR alpha and CPT1 were decreased and expression of FAS was markedly increased in ApoE-/- mice. In parallel, PPAR alpha promoter methylation level were slightly increased in ApoE-/- mice though without significance. Betaine supplement upregulated expression of PPAR alpha and its target genes (CPT1, CYP2E1) and reversed hypermethylation of PPAR alpha promoter of ApoE-/- mice. Furthermore, PPAR alpha methylation was positively correlated with hepatic betaine concentration. CONCLUSIONS: Our findings indicate that betaine supplement could alleviate hepatic triglyceride accumulation and improve antioxidant capacity by decreasing PPAR alpha promoter methylation and upregulating PPAR alpha and its target genes mRNA expression.