An incremental isoconversional method for kinetic analysis based on the orthogonal distance regression

The parameters obtained from a kinetic analysis of thermoanalytical data often exhibit a conversion‐dependent behavior. A novel incremental isoconversional method able to deal with this phenomenon is proposed. The kinetic model is directly fitted to the experimental data using nonlinear orthogonal least squares procedure. The data are processed without transformations, so their error distribution is preserved. As the objective function is based on a maximum likelihood approach, reliable uncertainties of the parameters can be estimated. In contrast to other methods, the activation energy and the pre‐exponential factor are treated as equally important kinetic parameters and are estimated simultaneously. Validity of the method is verified on simulated data, including a dataset with local nonlinearity in the temperature variation. A practical application on the nonisothermal cold crystallization of polyethylene terephthalate is presented. © 2014 Wiley Periodicals, Inc.     

Two new lignan-iridoid glucoside diesters from the leaves of Vaccinium bracteatum and their relative and absolute configuration determination by DFT NMR and TDDFT-ECD calculation

Two new lignan-iridoid glucoside diesters (2 and 3), together with their putative biosynthetic precursor 10-O-trans-caffeoyl-6α-hydroxyl-dihydromonotropein (1), were characterized from the leaves of Vaccinium bracteatum. Their planar structures and relative configuration were elucidated by spectroscopic measurements and DFT C NMR calculations, and their absolute configurations were determined by time-dependent density functional theory (TDDFT) electronic circular dichroism (ECD) calculations. The plausible biosynthetic pathways of new compounds were also proposed.     

Expression of Luteinizing Hormone-Releasing Hormone (LHRH) and Type-I LHRH Receptor in Transitional Cell Carcinoma Type of Human Bladder Cancer

Bladder cancer (BC) is the tenth most frequently detected cancer in both sexes. Type-I luteinizing hormone-releasing hormone (LHRH) receptor (LHRH-R-I) is expressed not only in the pituitary, but also in several types of cancer disease. There are few data about LHRH-R-I expression in human BC. This study aimed to investigate the expression of LHRH and LHRH-R-I in the transitional cell carcinoma (TCC) type of human BC. RNA was extracted from 24 human bladder tumor specimens and three BC cell lines. RT-PCR was performed to detect mRNA for LHRH and LHRH-R-I. The protein of LHRH-R-I was further studied by immunohistochemistry (IHC), ligand competition assay, and Western Blot. PCR products of LHRH were found in 19 of 24 (79%) specimens and mRNA of LHRH-R-I was detected in 20 of 24 specimens (83%). Positive immunostaining for LHRH-R-I with different expression intensity was found in all samples examined, showing negative correlation with TCC grade. Radioligand binding studies also showed the presence of specific LHRH-R-I and high affinity binding of LHRH analogs. The high incidence of LHRH-R in BC suggests that it could serve as a molecular target for therapy of human BC with cytotoxic LHRH analogs or modern powerful antagonistic analogs of LHRH.     

Effects of deep-freezing and storage time on human femoral cartilage

Surgical techniques including new, possible resources to repair injured joints and damaged cartilage are still evolving. The exact effects of cryopreservation on the collected cartilage samples require accurate determination prior to utilization. The aim of our study was to analyze the impact of cryopreservation at ?80 °C on the structural properties of the human cartilage. The effects of storage time were also evaluated in conjunction with optimal utilization. The human cartilage samples were derived during operation and considered to be waste material. Samples were fresh frozen and stored at ?80 °C. Cryopreservation times were: 0, 1, 3, 6, and 12 weeks. To assess the biological and structural properties of the frozen human cartilage, we performed calorimetric examinations using differential scanning calorimetry (DSC). During the first 3 weeks, the calorimetric enthalpy (ΔH _cal) showed an increasing tendency compared to controls, parallel with the denaturation temperature (T _m): ΔH _cal (J g^?1) = 1.60 versus 2.49, T _m1 (°C) = 61.73 versus 63.64. After the sixth week, both the enthalpy and the transition temperature decreased, compared to the control samples. The decrease in both the calorimetric enthalpy and T _m could be explained by the decrease in bound water and the time-related degeneration in the structure of the cartilage. Here we found that the duration of cryopreservation interferes with the morphology of human cartilage samples only after 6 weeks of storage time. The thermal analyzes of human cartilage by DSC could be a useful method to follow the morphological changes in the clinical practice.     

Imatinib mesylate cocrystals: synthesis, screening, and preliminary characterization

Abstract  

Drug–drug cocrystals of imatinib mesylate with several cocrystal formers, i.e. 5-chlorouracil, 5-fluorouracil, hydroxyurea, 5-fluorocytosine, N-acetylcytosine, chlorogenic acid, dacarbazine, curcumin, creatine, orotic acid, l-cysteine, glutathione, and caffeic acid, were prepared from mixtures by cogrinding or solvent cocrystallization. The samples prepared were analyzed by FTIR, DSC, and XRPD. Formation of cocrystals with different stoichiometry was observed. Novel cocrystals of imatinib mesylate with 5-fluorouracil or hydroxyurea were identified, characterized, and selected by the solid form screening approach. These cocrystals were non-hygroscopic and chemically and physically stable to thermal stress under the testing conditions.     

A Novel and Efficient Synthesis of 6-Alkyl-7-alkyloxy-2,2-dimethyl-Chromans

A series of 6-alkyI-7-alkyloxy-2,2-dimethyl-chroman was prepared via a novel pathway from the corresponding 7-alkyloxy-2,2-dimethyl-4-chromanones.     

Detection and characterization of twenty‐eight isomers of fumonisin B1 (FB1) mycotoxin in a solid rice culture infected with Fusarium verticillioides by reversed‐phase high‐performance liquid chromatography/electrospray ionization time‐of‐flight and ion trap mass spectrometry

Fumonisin mycotoxins which are hazardous to humans and animals were produced in a Fusarium verticillioides‐infected solid rice culture. To decrease the possibility of the formation of artifacts, the fumonisins were analysed by reversed‐phase high‐performance liquid chromatography/electrospray ionization time‐of‐flight (RP‐HPLC/ESI‐TOFMS) and ion trap mass spectrometry (RP‐HPLC/ESI‐ITMS) immediately after the extraction of the culture material, without any further sample clean‐up. The fumonisin isomers were separated by using a flat gradient on a special, high‐coverage C₁₈, narrow‐bore HPLC column (YMC‐Pack J'sphere ODS H80) suggested for the separation of structural isomers by the manufacturer. Exact mass measurements (TOFMS) of the protonated molecules and extraction of the ion chromatogram corresponding to the empirical formula (C₃₄H₅₉NO₁₅) of FB₁ toxins led to the identification of 29 peaks and shoulders, including those of FB₁. The FB₁ toxin and 28 of its isomers were also detected by ITMS after separation with RP‐HPLC. The characteristic m/z values of the product ions, including the backbones obtained by ITMS², undoubtedly indicated the structures of the FB₁ isomers for 28 peaks and shoulders. In the MS² spectra of the protonated molecules of the FB₁ isomers, with some exceptions, 15 characteristic product ions including the hydrocarbon backbone at m/z 299 were observed. The abundance ratio of the cation at m/z 299 ranged up to 5.8%. The relative quantities of the isomers found in the sample extract were expressed as percentages of the FB₁ content (0.001–0.579%). The total amount of the 28 FB₁ isomers was 2.803% of the quantity of FB₁ that is important from the aspect of food and feed safety. Copyright © 2009 John Wiley & Sons, Ltd.