Search

A novel method is presented for the evaluation of Jvalues from total correlation spectra. The series expansion of the density matrix for a system undergoing isotropic mixing shows that a convenient approximation can be exploited to evaluate the extent of net transfer as a function of Jvalues. Peak amplitude quantitation of short mixing time spectra provides tentative estimates of scalar couplings that can be further refined by fitting the experimental data with theoretical transfers obtained by full density-matrix calculation. The method is applied to conventional 2D TOCSY and heteronuclear resolved relayed TOCSY (SQCTOCSY) spectra of model compounds. The extracted coupling constants agree satisfactorily with the corresponding values obtained by 1D spectrum simulation.

In this study we describe the application of an enzyme-linked immunosorbent assay (ELISA) for the measurement of anti-a-gliadin antibodies (AGA) in absolute units (µmlg protein/ml). Enriched samples of IgA and IgG AGA were obtained by means of protein A chromatography after immunoaffinity purification of pooled sera from untreated celiac patients. No cross-reactivity with other food antigens (ß-lactalbumin, soya proteins, ovalbumin) was detected. The quantitative evaluation of protein content in IgA and IgG AGA samples obtained by immunoaffinity chromatography, was performed by means of ELISA sandwich method using a reference curve obtained with pure standard human immunoglobulins. Scalar concentrations of purified IgA and IgG were then used to obtain a reference standard curve by means of an ELISA method. Such standard curve was utilized for titrating AGA in 214 sample sera. The minimal detectable concentration of IgA and IgG AGA was 0.02 µmlg/ml. The reproducibility of within- and between-assay resulted very good for IgA-AGA and acceptable for IgG-AGA. The method here described seems to be satisfactory not only for quantitative diagnostic purposes in routine screenings but also in epidemiological studies. Moreover, it can constitute a suitable way to solve practical problems of quality control of AGA ELISA assay.

In this study we describe the application of an enzyme-linked immunosorbent assay (ELISA) for the measurement of anti-α-gliadin antibodies (AGA) in absolute units (μmlg protein/ml). Enriched samples of IgA and IgG AGA were obtained by means of protein A chromatography after immunoaffinity purification of pooled sera from untreated celiac patients. No cross-reactivity with other food antigens (β-lactalbumin, soya proteins, ovalbumin) was detected. The quantitative evaluation of protein content in IgA and IgG AGA samples obtained by immunoaffinity chromatography, was performed by means of ELISA sandwich method using a reference curve obtained with pure standard human immunoglobulins. Scalar concentrations of purified IgA and IgG were then used to obtain a reference standard curve by means of an ELISA method. Such standard curve was utilized for titrating AGA in 214 sample sera. The minimal detectable concentration of IgA and IgG AGA was 0.02 μmlg/ml. The reproducibility of within- and between-assay resulted very good for IgA-AGA and acceptable for IgG-AGA. The method here described seems to be satisfactory not only for quantitative diagnostic purposes in routine screenings but also in epidemiological studies. Moreover, it can constitute a suitable way to solve practical problems of quality control of AGA ELISA assay.

Le mélanome est l’un des cancers de la peau les plus agressifs et son incidence et sa prévalence sont en continuelle augmentation. Des facteurs génétiques, environnementaux et comportementaux ont été impliqués dans sa pathogenèse et son pronostic. L’association entre le mélanome et le tabagisme est aujourd’hui largement débattue. Jusqu’ici, les biomarqueurs associés au développement du mélanome métastatique malin restent difficile à saisir, des conclusions contradictoires pouvant partiellement découler de milieux ethniques hétérogènes. De récentes découvertes indiquent l’implication de la vitamine D et du récepteur de la vitamine D (VDR) dans le développement du mélanome. Le but de l’étude est d’explorer l’association du polymorphisme Bsml (rs 1544410, localisé dans l’intron 8 du VDR) et du tabagisme parmi 85 cas de mélanome et 102 témoins sains.

The molecular basis for the DNA binding specificity of the thyroid transcription factor 1 homeodomain (TTF- 1HD) has been investigated. Methylation and ethylation interference experiments show that the TTF-1HO alone recapitulates the DNA binding properties of the entire protein. Studies carried out with mutant derivatives of TTF-1HD indicate a precise correspondence of some of its amino acid residues with specific bases in its binding site, allowing a crude orientation of the TTF- 1HD within the protein - DNA complex. TTF-1HD shows an overall geometry of interaction with DNA similar to that previously observed for Antennapedia class HDs, even though the binding specificities of these two types of HDs are distinct. We demonstrate that the crucial difference between the binding sites of Antennapedia class and TTF-1 HDs is in the motifs 5′-TAAT-3′, recognized by Antennapedia, and 5′-CAAG-3′, preferentially bound by TTF-1. Furthermore, the binding of wild type and mutants TTF-1 HD to oligonucleotides containing either 5′-TAAT-3′ or 5′-CAAG-3′ indicate that only in the presence of the latter motif the Gln50 in TTF-1 HD is utilized for DNA recognition. Since the Gin at position 50 is an essential determinant for DNA binding specificity for several other HDs that bind to 5′-TAAT-3′ containing sequences, we suggest that utilization by different HDs of key residues may depend on the sequence context and probably follows a precise hierarchy of contacts.