HPLC and RIA procedure for cyclosporine A determination compared with clinical background

Summary The aim of our study was to monitor Cyclosporine A (CA) during a long-term period and to determine whether the whole-blood levels, estimated by HPLC and radio-immunoassay (RIA), provide a relevant indicator of the toxic effect of CA, of the interference of endogenous substances with CA and of interactions of erythromycin and ketoconazole with CA metabolims. The ratios of CA concentrations, estimated by RIA and by HPLC were calculated in order to analyse changes in CA metabolism. A decrease in this ratio was observed in these patients during periods of erythromycin and ketoconazole therapy deteriorating hepatic function. We observed unusual higher CA concentrations measured by HPLC compared with RIA in heart transplant patient with marked renal insiffuciency after one-year follow-up period of treatment of CA. The comparison of CA whole-blood levels estimated using HPLC and RIA makes it possible to analyse the individual biotransformation of CA to its metabolites, and interference of endogenous substance in special clinical situations.     

The influence of the sample dimension on the distance between twist disclinations in a planar sample of chiral smectic C liquid crystal

The influence of the finite dimension of a chiral smectic C liquid crystal planar sample on the helical pitch length is discussed. The discussion is based on the properties of the disclination PH₂ system described in Czech. J. Phys. B35 (1985) 655. It is concluded that the existence of the sample free surface can lead to pitch changes with respect to the pitch of a perfect infinite chiral smectic C liquid crystal.     

On the well-posedness of the Hammer X-ray problem

Summary In un precedente articolo [10] il secondo autore ha dimostrato che ogni corpo convesso piano è univocamente determinato dalle lunghezze dette corde tagliate da tre fasci propri, i cui sostegni non sono allineati. Si dimostra in questo articolo che il corrispondente problema ricostruttivo è ben posto, se si assume che il corpo convesso da ricostruire è contenuto in un preassegnato insieme limitato.

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Supported in part by a grant from the National Research Council (C.N.R.) of Italy.

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Contribution to the research projectReconstruction, Ko 506/8-1 of the German Research Council (D.F.G.), directed by Professor D.Kölzow, Erlangen.     

Variability of silicate glasses from the LUNAR regolith

⁵⁷Fe Mössbauer transmission spectra of a set of differently coloured sub-millimetre glassy particles from the Soviet LUNA-24 landing were measured. The quadrupole splittings and average line widths of their components correspond to the pyroxene pattern with various degrees of devitrification. On this basis, a correlation is proposed between their colour and thermal history.     

Chemically Treated Silver Electrodes for the Determination of Cysteine

 This paper describes the use of Ag/Ag₂S and Ag/AgI ion-selective electrodes by means of chemical pretreatment of a silver wire or tube for the determination of cysteine (RSH) in batch and flow injection analysis (FIA). Received December 15, 2000. Revision July 11, 2001.     

Fabrication and characterization of magnetic ferrofluids by the co-precipitation way using diglycolic acid

Developing of a simple method for the fabrication of superparamagnetic iron oxide nanoparticles (Nps) is still a challenge for materials scientists. This work reveals a way to fabricate especially stable ferrofluids from spherical Nps of magnetite using the co-precipitation method, for which a new (diglycolic acid) stabilizer was applied. The Nps of the average size of ~7.4–16.5 nm were characterized by means of high resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM), selective area electron diffraction (SAED), Raman, FTIR and Mössbauer spectroscopy. The stabilization effect of the diglycolic acid for the growth of superparamagnetic Nps growth was discussed on the basis of experimental results.