Non-centrosymmetric superconductor Th[Formula: see text]Be[Formula: see text]Pt[Formula: see text] and heavy-fermion U[Formula: see text]Be[Formula: see text]Pt[Formula: see text] cage compounds

Unconventional superconductivity in non-centrosymmetric superconductors has attracted a considerable amount of attention. While several lanthanide-based materials have been reported previously, the number of actinide-based systems remains small. In this work, we present the discovery of a novel cubic complex non-centrosymmetric superconductor [Formula: see text] ([Formula: see text] space group). This intermetallic cage compound displays superconductivity below [Formula: see text] K, as evidenced by specific heat and resistivity data. [Formula: see text] is a type-II superconductor, which has an upper critical field [Formula: see text] T and a moderate Sommerfeld coefficient [Formula: see text] mJ [Formula: see text] [Formula: see text]. A non-zero density of states at the Fermi level is evident from metallic behavior in the normal state, as well as from electronic band structure calculations. The isostructural [Formula: see text] compound is a paramagnet with a moderately enhanced electronic mass, as indicated by the electronic specific heat coefficient [Formula: see text] mJ [Formula: see text] [Formula: see text] and Kadowaki-Woods ratio [Formula: see text] [Formula: see text] [Formula: see text] cm [Formula: see text] [Formula: see text] (mJ)[Formula: see text]. Both [Formula: see text] and [Formula: see text] are crystallographically complex, each hosting 212 atoms per unit cell.

Predictors of treatment requirement in HBeAg-negative chronic hepatitis B patients with persistently normal alanine aminotransferase and high serum HBV DNA levels

OBJECTIVES

Serum alanine aminotransferase (ALT) is a controversial marker for disease monitoring in hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (CHB) patients. The aim of this study was to determine the fibrosis stage and histological activity index (HAI) in HBeAg-negative CHB patients with persistently normal ALT (PNALT) and high serum HBV DNA (≥2000 IU/ml) and to investigate clinical risk factors for the requirement of treatment through the examination of liver biopsy specimens.

METHODS

HBeAg-negative CHB patients with PNALT (≤40 IU/l) and high serum HBV DNA (≥2000 IU/ml) were included. HBV fibrosis stage and HAI were scored according to the Ishak system. Multivariate logistic regression analysis was used to estimate the independent risk factors for fibrosis stage ≥2 and/or HAI ≥6. Receiver operating characteristic curve analysis was used to determine an optimal age cut-off for liver biopsy.

RESULTS

A total 120 patients were enrolled. These patients had a mean HBV DNA level of 123680±494500 IU/ml; the HBV DNA load was 2000-20000 IU/ml in 68 patients (56.6%) and ≥20000 IU/ml in 52 (43.4%). Eighteen patients (15%) had moderate-to-severe histological activity (HAI ≥6). Forty-three patients (35.9%) had a fibrosis stage ≥2. Forty-eight patients (40%) had a fibrosis stage ≥2 and/or HAI ≥6. On multivariate logistic regression analysis, independent variables associated with fibrosis stage ≥2 and/or HAI ≥6 included age and HBV DNA viral load. Patients with HBV DNA 2000-20000 IU/ml were more likely to require treatment compared to those with a viral load ≥20000 IU/ml. The optimal age cut-off to predict fibrosis stage ≥2 and/or HAI ≥6 was 46 years.

CONCLUSIONS

Significant liver damage was detected in 40% of CHB patients with PNALT and high HBV DNA upon biopsy. Age and HBV DNA viral load were independent predictors of significant liver damage. A biopsy to determine the degree of liver damage is advisable for CHB patients older than 46 years.

Can Helicobacter pylori be eradicated with high-dose proton pump inhibitor in extensive metabolizers with the CYP2C19 genotypic polymorphism?

Proton pump inhibitors (PPI) metabolism and pharmacokinetics are regulated by cytochrome P450 enzymes in the liver. Cytochrome P450 2C19 (CYP2C19) polymorphism plays an import role in the metabolism of PPIs. The three possible genotypes for CYP2C19 each has a distinct effect on the pharmacodynamics of PPIs. Homozygote extensive metabolizers (HomEM) are the most frequent genotype and have two wild-types (non-mutant) (*1/*1) alleles. HomEM is associated with increased enzyme activity, which increases the rate of PPI metabolism. Intragastric pH, which is required for eradication, is lowest in HomEM. In HomEMs, an insufficient increase in intragastric pH results in decreased anti-Helicobacter pylori (HP) efficacy of the antibiotics and, therefore, lower eradication rates. We determined whether the HP eradication rate would increase after high-dose PPI treatment of extensive PPI metabolizers who had been treated unsuccessfully with a standard PPI dose. In our report, increasing the PPI dosage in patients with genotype polymorphisms may be effective on eradication rates. Eradication rates are directly affected by CYP2C19 polymorphisms, and eradication treatments should be planned considering such genotypic polymorphisms. Hence, CYP2C19 genotyping prior to treatment may facilitate determination of the optimum PPI dose to improve the therapeutic outcome. However, further researches are required to confirm this hypothesis.

Effect of cytochrome P450 2C19 polymorphisms on the Helicobacter pylori eradication rate following two-week triple therapy with pantoprazole or rabeprazole

OBJECTIVE

Cytochrome P450 2C19 (CYP2C19) polymorphisms play an important role in the metabolism of proton pump inhibitors. Rabeprazole is primarily metabolized via non-enzymatic pathways. In this study, we determined whether rabeprazole- and pantoprazole-based eradication treatments were influenced by CYP2C19 polymorphisms.

PATIENTS AND METHODS

A total of 200 patients infected with Helicobacter pylori were treated with either 40 mg of pantoprazole or 20 mg of rabeprazole plus 500 mg of clarithromycin, 1000 mg of amoxicillin twice daily for 2 weeks. CYP2C19 genotype status was determined by Polymerase Chain Reaction (PCR)-restriction-fragment-length polymorphism. The genotypes of cytochrome P450 2C19 were classified as homozigote extensive metabolizer (HomEM), heterozigote metabolizer (HetEM) and poor metabolizer (PM). The CYP2C19 genotype of all patients, the effectiveness of the treatment, the effect of the genotypic polymorphism on the treatment were assessed.

RESULTS

The frequencies of HotEM, HetEM, PM were 78%, 19.5% and 2.5%, respectively. 48% (n = 96) of the patients received treatment with rabeprazole and 52% (n = 104) with pantoprazole. The eradication rate was 64.7% for HomEM, 79.4% for HetEM, 100% for PM (p = 0.06). In HetEM, PM, are considered as a single group, the eradication rates were higher in patients with the HetEM and PM (HetEM+PM) genotypes than in those with the wild-type genotype (81.8 vs. 64.7% p = 0.031). Among the patients treated with rabeprazole, the eradication rates were significantly lower in those with the HomEM genotype than in those with the HetEM+PM genotypes (60% vs. 85.7% p = 0.023).

CONCLUSIONS

The genotypic polymorphism is effective on the rate of eradication. Eradication treatment rate with rabeprazole is influenced by CYP2C19 genotype.

Electronic band structure and low-temperature transport properties of the type-I clathrate Ba8Ni(x)Ge(46-x-y□y)

We present the evolution of the low-temperature thermodynamic, galvanomagnetic and thermoelectric properties of the type-I clathrate Ba8Ni(x)Ge(46-x-y□y) with the Ni concentration studied on polycrystalline samples with 0.0 ≤ x ≤ 6.0 by means of specific heat, Hall effect, electrical resistivity, thermopower and thermal conductivity measurements in the 2-350 K temperature range and supported by first-principles calculations. The experimental results evidence a 2a × 2a × 2a supercell described in the space group Ia3d for x ≤ 1.0 and a primitive unit cell a × a × a (space group Pm3n) above this Ni content. This concentration also marks the limit between a regime where both electrons and holes contribute to the electrical conduction (x ≤ 1.0) and a conventional, single-carrier regime (x > 1.0). This evolution is traced by the variations in the thermopower and Hall effect with x. In agreement with band structure calculations, increasing the Ni content drives the system from a nearly-compensated semimetallic state (x = 0.0) towards a narrow-band-gap semiconducting state (x = 4.0). A crossover from an n-type to a p-type conduction occurs when crossing the x = 4.0 concentration i.e. for x = 4.1. The solid solution Ba8Ni(x)Ge(46-x-y□y) therefore provides an excellent experimental platform to probe the evolution of the peculiar properties of the parent type-I clathrate Ba8Ge43□3 upon Ge/Ni substitution and filling up of the vacancies, which might be universal among the ternary systems at low substitution levels.

High temperature thermoelectric properties of the type-I clathrate Ba8NixGe46-x-y□y

Polycrystalline samples of the type-I clathrate Ba(8)Ni(x)Ge(46-x-y)□(y) were synthesized for 0.2 ⩽ x ⩽ 3.5 by melt quenching and for 3.5<x ⩽ 6.0 by melting with subsequent annealing at 700 °C. The maximum Ni content in the clathrate framework at this temperature was found to be x ≈ 4.2 atoms per unit cell. Thermoelectric and thermodynamic properties of the type-I clathrate were investigated from 300 to 700 K by means of electrical resistivity, thermopower, thermal conductivity and specific heat measurements. As the Ni content increases, the electronic properties gradually evolve from a metallic character (x < 3.5) towards a highly doped semiconducting state (x ⩾ 3.5). Below x ≈ 4.0 transport is dominated by electrons, while further addition of Ni (x ≈ 4.2) switches the electrical conduction to p-type. Maximum value of the dimensionless thermoelectric figure of merit ZT ≈ 0.2 was achieved at 500 K and 650 K for x ≈ 2.0 and x ≈ 3.8, respectively.

Crystal structure of niobium chromium nickel, Nb(Cr1-xNix)2 (x = 0.49)

Cr1.02NbNi0.98, hexagonal, P63/mmc (no. 194), a = 4.8692(5) Å, c = 7.9628(8) Å, V = 163.5 Å3, Z = 4, Rgt(F) = 0.052, wRref(F2) = 0.111, T = 293 K.

Electron Localization Function in Full-Potential Representation for Crystalline Materials

The electron localization function (ELF) is implemented in the first-principles, all-electron, full-potential local orbital method. This full-potential implementation increases the accuracy with which the ELF can be computed for crystalline materials. Some representative results obtained are presented and compared with the results of other methods. Although for crystal structures with directed bonding only minor differences are found, in simple elemental metals, there are differences in the valence region, which give rise to different ELF topologies.