First-principles study of illite-smectite and implications for clay mineral systems

Illite-smectite interstratified clay minerals are ubiquitous in sedimentary basins and they have been linked to the maturation, migration and trapping of hydrocarbons(1), rock cementation(2), evolution of porewater chemistry during diagenesis(3) and the development of pore pressure(4). But, despite the importance of these clays, their structures are controversial. Two competing models exist, each with profoundly different consequences for the understanding of diagenetic processes: model A views such interstratified clays as a stacking of layers identical to endmember illite and smectite layers, implying discrete and independently formed units (fundamental particles)(5), whereas model B views the clays as composed of crystallites with a unique structure that maintains coherency over much greater distances, in line with local charge balance about interlayers(6). Here we use first-principles density-functional theory to explore the energetics and structures of these two models for an illite-smectite interstratified clay mineral with a ratio of 1:1 and a Reichweite parameter of 1. We find that the total energy of model B is 2.3 kJ atom(-1) mol(-1) lower than that of model A, and that this energy difference can be traced to structural distortions in model A due to local charge imbalance. The greater stability of model B requires re-evaluation of the evolution of the smectite-to-illite sequence of clay minerals, including the nature of coexisting species, stability relations, growth mechanisms and the model of fundamental particles.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62760/1/nature01155.pd

Nationwide epidemiological study of severe gallstone disease in Taiwan

<p>Abstract</p> <p>Background</p> <p>Our study aimed to assess the nationwide trends in the incidence of severe gallstone disease in Taiwan among adults aged ≥20.</p> <p>Methods</p> <p>A retrospective longitudinal study was conducted using Taiwan National Health Insurance Research Database collected during 1997–2005. Patients with incident severe gallstone disease (acute cholecystitis, biliary pancreatitis, acute cholangitis) and gallstone-related procedures (elective and non-elective cholecystectomy, endoscopic retrograde cholangiopancreatography [ERCP]) that led to hospital admission were identified using ICD-9-CM diagnostic and procedure codes. Annual incidence rates of gallstone-related complications and procedures were calculated and their 95% confidence intervals (CI) were estimated assuming a Poisson distribution.</p> <p>Results</p> <p>The hospital admission rate for severe gallstone disease increased with advancing age and the age-standardized rate (95% CI) per 1000 population was 0.60 (0.59–0.60) for men and 0.59 (0.59–0.60) for women. Men had a higher rate of acute cholecystitis, probably due to the substantially lower rate of elective cholecystectomy among men than women. For those aged 20–39, hospital admissions for all gallstone-related complications and procedures increased significantly. For those aged ≥60, incidences of biliary pancreatitis, acute cholangitis, and hospital admission for gallstone receiving ERCP increased significantly without substantial change in the incidence of acute cholecystitis and despite a decreased rate of elective cholecystectomy.</p> <p>Conclusion</p> <p>This population-based study found a substantial increase in the rate of admission for severe gallstone disease among those aged 20–39. Concurrently, the incidences of biliary pancreatitis and acute cholangitis have risen among those aged ≥60.</p

Male Germ Cell-Specific RNA Binding Protein RBMY: A New Oncogene Explaining Male Predominance in Liver Cancer

Male gender is a risk factor for the development of hepatocellular carcinoma (HCC) but the mechanisms are not fully understood. The RNA binding motif gene on the Y chromosome (RBMY), encoding a male germ cell-specific RNA splicing regulator during spermatogenesis, is aberrantly activated in human male liver cancers. This study investigated the in vitro oncogenic effect and the possible mechanism of RBMY in human hepatoma cell line HepG2 and its in vivo effect with regards to the livers of human and transgenic mice. RBMY expression in HepG2 cells was knocked down by RNA interference and the cancer cell phenotype was characterized by soft-agar colony formation and sensitivity to hydrogen-peroxide-induced apoptosis. The results revealed that RBMY knockdown reduced the transformation and anti-apoptotic efficiency of HepG2 cells. The expression of RBMY, androgen receptor (AR) and its inhibitory variant AR45, AR-targeted genes insulin-like growth factor 1 (IGF-1) and insulin-like growth factor binding protein 3 (IGFBP-3) was analyzed by quantitative RT-PCR. Up-regulation of AR45 variant and reduction of IGF-1 and IGFBP-3 expression was only detected in RBMY knockdown cells. Moreover, RBMY positive human male HCC expressed lower level of AR45 as compared to RBMY negative HCC tissues. The oncogenic properties of RBMY were further assessed in a transgenic mouse model. Liver-specific RBMY transgenic mice developed hepatic pre-cancerous lesions, adenoma, and HCC. RBMY also accelerated chemical carcinogen-induced hepatocarcinogenesis in transgenic mice. Collectively, these findings suggest that Y chromosome-specific RBMY is likely involved in the regulation of androgen receptor activity and contributes to male predominance of HCC

Urate oxidase for prevention and treatment of tumor lysis syndrome in children with cancer

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Cost-effectiveness of amlodipine compared with valsartan in preventing stroke and myocardial infarction among hypertensive patients in Taiwan

Lung Chan,1 Chen-Huan Chen,2 Juey-Jen Hwang,3 San-Jou Yeh,4 Kou-Gi Shyu,5 Ruey-Tay Lin,6 Yi-Heng Li,7 Larry Z Liu,8 Jim Z Li,9 Wen-Yi Shau,10 Te-Chang Weng,10 1Department of Neurology, Shuang-Ho Hospital, School of Medicine, College of Medicine, Taipei Medical University, New Taipei, 2Department of Internal Medicine, Faculty of Medicine, National Yang-Ming University, 3Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital, Taipei, 4Division of Cardiology, Department of Internal Medicine, Chang Gung Memorial Hospital, Taoyuan, 5Division of Cardiology, Department of Internal Medicine, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, 6Department of Neurology, Kaohsiung Medical University Hospital, Kaohsiung, 7Division of Cardiology, Department of Internal Medicine, National Cheng Kung University Hospital, Tainan, Taiwan; 8Pfizer Inc, New York, NY, USA; 9Pfizer Inc, San Diego, CA ,USA; 10Pfizer Ltd., New Taipei City, Taiwan Abstract: Hypertension is a major risk factor for strokes and myocardial infarction (MI). Given its effectiveness and safety profile, the calcium channel blocker amlodipine is among the most frequently prescribed antihypertensive drugs. This analysis was conducted to determine the costs and quality-adjusted life years (QALYs) associated with the use of amlodipine and valsartan, an angiotensin II receptor blocker, in preventing stroke and MI in Taiwanese hypertensive patients. A state transition (Markov) model was developed to compare the 5-year costs and QALYs for amlodipine and valsartan. Effectiveness data were based on the NAGOYA HEART Study, local studies, and a published meta-analysis. Utility data and costs of MI and stroke were retrieved from the published literature. Medical costs were based on the literature and inflated to 2011 prices; drug costs were based on National Health Insurance prices in 2014. A 3% discount rate was used for costs and QALYs and a third-party payer perspective adopted. One-way sensitivity and scenario analyses were conducted. Compared with valsartan, amlodipine was associated with cost savings of New Taiwan Dollars (NTD) 2,251 per patient per year: costs were NTD 4,296 and NTD 6,547 per patient per year for amlodipine and valsartan users, respectively. Fewer cardiovascular events were reported in patients receiving amlodipine versus valsartan (342 vs 413 per 10,000 patients over 5 years, respectively). Amlodipine had a net gain of 58 QALYs versus valsartan per 10,000 patients over 5 years. Sensitivity analyses showed that the discount rate and cohort age had a larger effect on total cost and cost difference than on QALYs. However, amlodipine results were more favorable than valsartan irrespective of discount rate or cohort age. When administered to Taiwanese patients for hypertension control, amlodipine was associated with lower cost and more QALYs compared with valsartan due to a lower risk of stroke and MI events. Keywords: cost-effectiveness, pharmacoeconomic, Markov model, CCB, AR

Variation and heritability of Hb F and F-cells among β-thalassemia heterozygotes in Hong Kong

Enhanced fetal hemoglobin (Hb F) production can partially compensate for the lack of adult hemoglobin (Hb A) in patients with β-thalassemia major or intermedia, and ameliorate the clinical severity of these diseases. To further elucidate factors governing Hb F levels, we evaluated demographic, clinical, laboratory, and genetic characteristics in 241 unrelated adult β-thalassemia carriers in Hong Kong. They had wide variations in Hb F and F-cell numbers skewing toward higher levels. Individuals who coinherited the Xmn I T-allele in the Gγ-globin gene promoter had higher Hb F and more F-cells compared with those lacking the Xmn I T-allele. However, both groups exhibited a similarly wide spread of Hb F and F-cells. The correlation of Hb F and F-cells corresponded well to both linear and exponential models, suggesting multiple mechanisms for Hb F augmentation. The heritabilities of Hb F and F-cells were calculated in 66 families (111 parents who were β-thalassemia carriers and 82 asymptomatic offspring) to be 0.7 to 0.9. The Xmn I polymorphism accounted for 9% of the Hb F and 13% of the F-cell heritabilities. These results suggest that these family members are well suited for genome wide association studies that will identify genetic loci regulating Hb F production, and likely novel pharmacological targets for reactivating Hb F production in adults. © 2008 Wiley-Liss, Inc.link_to_subscribed_fulltex