Screening for C283Y gamma-sarcoglycan mutation in a high-risk group of Bulgarian Gypsies: evidence for a geographical localization and a non-random distribution among Gypsy subgroups

Limb-girdle muscular dystrophy type 2C (LGMD2C) is an autosomal recessive disorder caused by mutations in the gamma-sarcoglycan gene. A 'private' Gypsy C283Y mutation was detected in this gene. Recently, a number of LGMD2C-affected families belonging to a Xoroxane Gypsy group have been detected in eastern Bulgaria and all of these cases were due to the same mutation. We have screened 300 unrelated individuals of reproductive age from this high-risk Xoroxane Gypsy group, settled in Sliven. The genetic test by PCR-SSCP analysis for the C283Y mutation revealed a carrier frequency of 7.7%. The screened sample was ethnically not homogeneous. It was divided in ethnonym groups on the basis of social and economic status, language characteristics and trades. We found that the C283Y was not randomly distributed among the Gypsy subgroups. The disease seemed to be limited to the Xoroxane Gypsy group and geographically localized in eastern Bulgaria.     

A Chromatographic Effect Observed during Deposition of Cu-Mn Precursors on Active Carbon

The possibility of appearance of a chromatographic effect during the deposition of Cu-Mn precursors on active carbon with a view to obtaining supported oxide catalysts with a definite active phase composition has been investigated. By impregnation of the support with aqueous solutions of copper and manganese nitrates and subsequent drying at 110 degrees, two types of samples have been obtained: one-component and two-component ones. They have been characterized by chemical analysis, IR spectroscopy, EPR analysis, and magnetic and adsorption measurements. It has been established that during the preparation of two-component precursors the chromatographic effect is not very strong. Due to the complex chemical nature of the active carbon surface, the copper and manganese ions are adsorbed at different sites. On the basis of the isoelectric point of the active carbon and the pH value of the impregnating solutions, a scheme for the occurrence of adsorption processes has been proposed. The porous texture of the active carbon permits deposition of the precursor at definite surface sites; due to this it is very promising as a support of two-component oxide catalysts. Copyright 2000 Academic Press.     

Transition metal-catalyzed orthogonal solid-phase decoration of the 2(1H)-pyrazinone scaffold using a sulfur linker

A new transition metal-catalyzed orthogonal solid-phase protocol for the synthesis of highly substituted 2(1H)-pyrazinones was developed, on the basis of Chan-Lam arylation and Liebeskind-Srogl cross-coupling reactions. This strategy opens the way for the generation of small libraries of 2(1H)-pyrazinone analogues for biological screening.     

Comparative measurements of mineral elements in milk powders with laser-induced breakdown spectroscopy and inductively coupled plasma atomic emission spectroscopy

Mineral elements contained in commercially available milk powders, including seven infant formulae and one adult milk, were analyzed with inductively coupled plasma atomic emission spectrometry (ICP-AES) and laser-induced breakdown spectroscopy (LIBS). The purpose of this work was, through a direct comparison of the analytical results, to provide an assessment of the performance of LIBS, and especially of the procedure of calibration-free LIBS (CF-LIBS), to deal with organic compounds such as milk powders. In our experiments, the matrix effect was clearly observed affecting the analytical results each time laser ablation was employed for sampling. Such effect was in addition directly observed by determining the physical parameters of the plasmas induced on the different samples. The CF-LIBS procedure was implemented to deduce the concentrations of Mg and K with Ca as the internal reference element. Quantitative analytical results with CF-LIBS were validated with ICP-AES measurements and nominal concentrations specified for commercial milks. The obtained good results with the CF-LIBS procedure demonstrate its capacity to take into account the difference in physical parameters of the plasma in the calculation of the concentrations of mineral elements, which allows a significant reduction of the matrix effect related to laser ablation. We finally discuss the way to optimize the implementation of the CF-LIBS procedure for the analysis of mineral elements in organic materials.     

A matrix effect and accuracy evaluation for the determination of elements in milk powder LIBS and laser ablation/ICP-OES spectrometry

Laser ablation coupled to inductively coupled plasma optical emission spectrometry (LA-ICP-OES) and laser-induced breakdown spectroscopy (LIBS) were investigated for the determination of Ca, Mg, Zn and Na in milk samples. The accuracy of both methods was evaluated by comparison of the concentration found using LA-ICP-OES and LIBS with classical wet digestion associated with ICP-OES determination. The results were not fully acceptable, with biases from less than 1% to more than 60%. Matrix effects were also investigated. The sample matrix can influence the temperature, electron number density (n _e) and other excitation characteristics in the ICP. These ICP characteristics were studied and evaluated during ablation of eight milk samples. Differences in n _e (from 8.9 to 13.8 × 10¹⁴ cm⁻³) and rotational temperature (ranging from 3,400 to 4,400 K) occurred with no correlation with trueness. LIBS results obtained after classical external calibration procedure gave degraded accuracy, indicating a strong matrix effect. The LIBS measurements clearly showed that the major problem in LA-ICP was related to the ablation process and that LIBS spectroscopy is an excellent diagnostic tool for LA-ICP techniques.     

A criterion for unitary similarity of upper triangular matrices in general position

Each square complex matrix is unitarily similar to an upper triangular matrix with diagonal entries in any prescribed order. Let A=[a_ij] and B=[b_ij] be upper triangular n×n matrices that

•

are not similar to direct sums of square matrices of smaller sizes, or

•

are in general position and have the same main diagonal.

We prove that A and B are unitarily similar if and only if

     

Structure elucidation and vasodilator activity of methoxy flavonols from Calycotome villosa subsp. intermedia

Two flavonols identified as 3,5,7,4′-tetrahydroxy-3′-methoxyflavone (1) and 3,5,7,4′-tetrahydroxy-8-methoxyflavone (2) were isolated from the seeds of Calycotome villosa subsp. intermedia. The structure elucidation of the isolated compounds was performed by the spectroscopic methods (UV, IR, ¹H NMR, ¹³C NMR and MS) and also by a single crystal X-ray analysis in the case of compound (2). Vasodilator activity of compound (2) was demonstrated in isolated rat aorta contracted with high KCl or with noradrenaline.     

Spherical and lamellar octadecylsilane hybrid silicas

Silicas bearing different contents of octadecylsilane groups were synthesized by the sol–gel method and characterized by solid-state magic angle spin ¹³C nuclear magnetic resonance spectroscopy, Raman spectroscopy, attenuated total reflectance infrared spectroscopy, small angle X-ray scattering, laser light scattering and atomic force microscopy. A structural model for such hybrid materials is proposed in which spherical or lamellar morphology, fern-like or Porod’s structure, are proposed depending on the tetraethyl orthosilicate (TEOS)/octadecylsilane (ODS) molar ratio. The effect of the ODS addition time on the chain conformation and on the particle morphology and texture was also investigated. The degree of organization lowered as the amount of ODS increased. The nanostructured xerogel obtained in the case of pure TEOS evolutes from spherical to lamellar patterns, as the amount of octadecylsilane is increased.