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Biomedical subjects

L Negroni

Publications and source records attributed to L Negroni.

At least 19 recordsLinked to original sources
PubMed2000

Molecular typing of Mycobacterium tuberculosis based on variable number of tandem DNA repeats used alone and in association with spoligotyping.

Fingerprinting based on variable numbers of tandem DNA repeats (VNTR), a recently described methodology, was evaluated for molecular typing of Mycobacterium tuberculosis in an insular setting. In this study, VNTR fingerprinting was used alone or as a second-line test in association with spoligotyping, double-repetitive-element PCR (DRE-PCR), and IS6110 restriction fragment length polymorphism (RFLP) analysis, and the discriminatory power for each method or the combination of methods was compared by calculating the Hunter-Gaston discriminative index (HGI). The results obtained showed that in 6 out of 12 (50%) cases, VNTR-defined clusters were further subdivided by spoligotyping, compared to 7 out of 18 (39%) cases where spoligotyping-defined clusters were further subdivided by VNTR. When used alone, VNTR was the least discriminatory method (HGI = 0.863). Although VNTR was significantly more discriminatory when used in association with spoligotyping (HGI = 0.982), the combination of spoligotyping and DRE-PCR (HGI = 0.992) was still the most efficient among rapid, PCR-based methodologies, giving results comparable to IS6110 RFLP analysis. Nonetheless, VNTR typing may provide additional phylogenetical information that may be helpful to trace the molecular evolution of tubercle bacilli.

Bacterial Typing Techniques↗
PubMed1998

Two-site enzyme immunometric assays for determination of native and denatured beta-lactoglobulin.

Two enzyme immunometric assays suitable for measuring native and denatured beta-lactoglobulin (BLg) have been developed. The assays were performed in 96-well microtitre plates and were based on the use of pairs of monoclonal antibodies specific to either the native form or the reduced and carboxymethylated form of BLg (RCM-BLg). Detection limits of 30 and 200 pg/ml were obtained for the native BLg and the RCM-BLg assay, respectively, with very low or negligible cross-reactivity of the other milk proteins and tryptic fragments of BLg. The validity of the assays in different media such as cow's milk and cow's milk products, saline buffer or serum was supported by recovery experiments. The assays were first applied to the determination of BLg and RCM-BLg in PBS and in raw skimmed milk. The ability of the RCM-BLg assay to detect heat-denatured BLg was confirmed by a kinetic study of BLg heat-denaturation in the two media. During heat treatment, the decrease in the concentration of native BLg was associated with an increase in denatured BLg specifically detected by the RCM-BLg assay. By selecting an appropriate monoclonal antibody which failed to recognize caprine BLg, we were able to establish a modified sandwich immunoassay permitting very sensitive detection of cow's milk in goat's milk.

Animals↗
PubMedDate not supplied

Molecular basis of IgE cross-reactivity between human beta-casein and bovine beta-casein, a major allergen of milk.

Twenty patients allergic to cow's milk proteins and with high levels of specific IgE directed against bovine whole casein were selected to evaluate reactivity of their IgE antibodies with human beta-casein. Highly purified human and bovine beta-caseins were prepared by selective precipitations and FPLC separation. Their identity and purity were assessed by HPLC, analysis of amino acid composition, sequencing of the five N-terminal amino acid residues and immunochemical tests. Direct and indirect ELISAs were performed using human and bovine beta-casein coated into microtiter plates and monoclonal anti-human IgE antibody AChE labelled for revelation. Seven sera contained specific IgE directed against human beta-casein. Inhibition studies using native human and bovine beta-caseins as well as bovine beta-casein-derived peptides demonstrated that, depending on the sera, one or several common epitopes located in different parts of the molecule were shared by the two homologous proteins.

Adolescent↗