Influence on drug efficacy of the binding behavior of pioglitazone hydrochloride with tryptophan residues,and tyrosine residues in bovine transferrin

Abstract

The interaction of pioglitazone hydrochloride bound to tryptophan residues and tyrosine residues in bovine transferrin was investigated using synchronous fluorescence spectroscopy at various temperatures (298, 310, and 318?K). From binding constants and thermodynamic parameters, it was shown that 1:1 stable compound was formed by the electrostatic force interaction of pioglitazone hydrochloride bound to tryptophan residues and tyrosine residues in bovine transferrin. The extent of binding between pioglitazone hydrochloride and tryptophan residues in bovine transferrin was more than that between pioglitazone hydrochloride and tyrosine residues in bovine transferrin. At 310?K, the fluorescence quenching ratio number of tyrosine residues and tryptophan residues in bovine transferrin were 47.52% and 54.19%, respectively, which indicated that the fluorescence contribution of tryptophan residues was greater. At 310?K, pioglitazone hydrochloride-tyrosine residues(in bovine transferrin) binding rate were 55.60–73.82%, and the combined model was W?=??0.0315R²???0.1520R?+?0.7385. The value of Hill’s coefficients was greater than 1, which suggested that there was a positive cooperativity between pioglitazone hydrochloride and subsequent ligands. The results of molecular docking were consistent with that of experimental calculation.     

Fluorescence resonance energy transfer between cerium ion(III) and levofloxacin in micellar solution and its analytical application to the determination of levofloxacin

Fluorescence resonance energy transfer between cerium ion(III) and levofloxacin is studied in a micellar solution of cetyltrimethyl ammonium bromide. A non-fluorescent 1:2 complex was formed between excited cerium ion(III) and ground state levofloxacin. The fluorescence of cerium ion(III) is quenched by levofloxacin with the quenching in accordance with the Stern–Volmer relation. The analytical relationship was established between the ratio of the fluorescence of levofloxacin present and absent cerium ion (III) and the concentration of levofloxacin, which helped to estimate the content of levofloxacin directly.     

Variations in the Concentrations of Cu and Zn and in the Ratio of Cu to Zn in Whole Blood and Hair Samples from Hepatocellular Carcinoma Patients and from Healthy Controls in Taiwan

An atomic absorption spectrophotometer was used to determine concentrations of copper and zinc and the ratio of Cu to Zn in samples of whole blood and hair from hepatocellular carcinoma (HCC) patients (n=51) and from healthy controls (n=50) in Taiwan. Our results indicate that the HCC patients have higher copper concentrations and higher ratios of Cu to Zn than do the healthy controls both in whole blood and hair samples, but only the concentration of copper and the ratio of Cu to Zn in whole blood were significantly different (p<0.001 and p<0.05). Conversely, a lower concentration of zinc was found in whole blood and hair samples of HCC patients. Similarly, only the concentration of zinc in whole blood showed a significant difference (p<0.001). We concluded that the whole blood concentrations of copper and zinc and the ratio of Cu to Zn seemed to have a higher correlation with HCC. Thus, we suggest that a sample of whole blood may be a more suitable diagnostic sample than is a hair sample for HCC.     

The Mineral Content of Rhizona cyperi after Microwave-Assisted Digestion and Determination by AAS

ABSTRACT

Rhizoma cyperi (tuberal part of Cyperus rotundus Linn) obtained from 15 different zones of China was studied to determine the contents of 16 trace elements such as 4 minor (Ca, K, Mg, and Na), 9 trace (Co, Cr, Cu, Fe, Mn, Mo, Ni, V, and Zn), and 3 toxic (Ag, Cd, and Pb) elements. The concentration determination of 16 elements was performed by atomic absorption spectrophotometry (AAS) after microwave-assisted digestion. A microwave-assisted digestion procedure based on the mixture nitric acid–hydrogen peroxide was evaluated. The method was successfully validated with the good recoveries (97–105%) against CRM GBW07603 (bush twigs and leaves). The calibration curve furnished good linear correlation coefficients (r = 0.9956–0.9999), excellent recoveries (99.35–103.7%), and limits of detection (LOD = 1–50 ng·mL^?1) suitable to determine in Rhizoma cyperi. The results showed that K, Ca, Mg, and Na were the most abundant of the major elements in Rhizoma cyperi with average concentrations of K, 26,221 µg·g^?1; Ca, 1097 µg·g^?1; Mg, 714 µg·g^?1, and Na, 293 µg·g^?1, respectively. K element was determined for the first time in this plant.     

Grüneisen parameter for HCP iron at extreme compression

The Thomas–Fermi approximation gives the Grüneisen parameter γ=γ_∞=1/2 for all materials at extreme compression (P→∞ or V→0). After re-analyzing the existing experimental data of volume dependence of Grüneisen parameter γ of hexagonal close-packed (HCP) iron, we find that γ=1/2+a(V/V ₀)^1/3+b(V/V ₀) ⁿ , where a, b and n are constants. Based on this new form of γ, the second Grüneisen parameter q, the Debye temperature θ_D and the shear sound velocity v _s of HCP iron are discussed in the present work. It is found that the zero pressure second Grüneisen parameter q ₀=0.654, which is consistent with the previously determined value of HCP iron for Earth's core physics from Dubrovinsky et al. The calculations for the Debye temperature and the shear sound velocity are also found to be in good agreement with the experimental data.     

A comparative in vitro study of the digestibility of heat- and high pressure-induced gels prepared from industrial milk whey proteins

We undertook this study to compare the digestibility of heat- and high pressure-induced gels produced from whey protein isolate (WPI). To simulate in vivo gastrointestinal digestion of WPI gels, a pepsin–trypsin digestion system was used. The in vitro protein digestibility of WPI gels induced by high pressure (400 MPa and 30 min; P-gel) and those induced by heat (80°C and 30 min; H-gel) was compared using a protein concentration of 0.14 g mL^?1. The in vitro protein digestibility of P-gels was significantly greater than that of H-gels (p<0.05). The size-exclusion chromatography profiles of the hydrolysates showed that the P-gel generated more and smaller peptides than natural WPI and H-gels. Furthermore, Sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis showed some soluble disulfide-mediated aggregation in the P-gel, while there was more insoluble aggregation in the H-gel than the P-gel. The P-gel was more sensitive to proteinase than the H-gel, which was related to the content of S–S bonds, and this in turn could be attributed to the differences in the gelation mechanism between the H-gel and P-gel.     

Investigation of formation mechanism of Ti3SiC2 by high pressure and high-temperature synthesis

ABSTRACT

In this paper, synthesis of titanium silicon carbide (Ti₃SiC₂) under high pressure and high-temperature condition has been investigated by using the reactant systems Ti/Si/C, Ti/SiC/TiC, Ti/SiC/C and Ti/TiC/Si. Results reveal that Ti/TiC/Si is unsuited to the synthesis of Ti₃SiC₂ under a high pressure of 2.0?GPa, while an elemental mixture of Ti/Si/C is applicable. By the addition of Al, Ti₃SiC₂ with 95.8?wt% purity was obtained from elemental mixture with a large excess of silicon. The optimum experimental parameters were determined as Ti/Si/Al/C having the molar ratio of 3:1.5:0.5:1.9, holding at 2.0?GPa and 1300?°C for 60?min.     

Pressure effect on emission spectra and crystal field for La OBr : Eu

Abstract

The emission spectra for LaOBr : Eu were measured at pressures up to 13 GPa and room temperature. The pressure dependences of levels of ⁷F_0,1,2,3,4 and ⁵D_0,1,2 are given. The crystal field parameters B^k _q were computed by fitting the experimental levels. The strength of crystal field decreases with increasing pressure. A brief discussion on the observed phenomena is presented.     

Research on exponential regularization approach for nonnegative Tucker3 decomposition

Methods of nonnegative tensor factorization (NTF), such as NTF1, NTF2, etc., are extension of nonnegative matrix factorization (NMF) for multi-way data analysis. As an existing NTF method, nonnegative Tucker3 decomposition (NTD) is researched for three-way decomposition in this paper. Firstly, an approach utilizing matrix exponentials built on Tikhonov-type regularization to enforce sparseness is proposed to extract image features instead of exclusively using Tucker tensor decomposition. Meanwhile, updating algorithms, derived from updating rules of NMF, are allowed to efficiently implement updating of mode matrices and core tensors alternatively for accuracy. Then, experimental cases of alternating least squares (ALS) and conjugate nonnegative constraints, called nonnegative alternating least squares (NALS), are studied to remedy data overfitting in computing procedures. Lastly, the proposed method exhibits more advantageous results than other algorithms of Tucker3 for feature extraction, thanks to computer simulations performed in the context of data analysis.     

Measuring the wavelength of light wave with four-sides prism spectrograph

The angular dispersion of four-sides prism is presented. A more accurate amended expression of measuring the wavelength of light wave with the spacing between two spectral lines is presented. The spacing between two spectral lines is measured with measuring microscope, the wavelength of light wave is calculated with the amended expression, the experimental values of wavelengths agree well with the reference value.