Prospective study of insulin-dependent diabetes mellitus.

Laboratory study fo 109 insulin-dependent diabetics younger than 17 yr of age and resident in greater Montreal at the time on onset of symptoms is reported. The cases were diagnosed during a 2-yr period (1976-1978). Sibling controls were obtained for 72 of the cases studied. Viral titers to coxsackie B, rubella, and mumps virus for the 72 patient-sibling pairs showed no difference in geometric mean titers or in change of titer between samples taken at the time of diagnosis and those taken 28 days later. The incidence of positive islet cell antibody in teh IDdM cases was 68.0% at the time of diagnosis compared with 56.(% 4 wk later. The comparative figures of sibling controls were 4.2% and 1.4%, respectively. The frequency of HLA B8, B15, B18, and B7 antigens were compared both with the sibling controls and a normal control population. Pairing of high risk HLA antigens were found more frequently in cases than controls. There was no difference in geometric mean viral titers in cases with risk risk haplotypes compared with those cases in which such haplotypes were absent.

A comparative study of G+C-rich satellite components of sheep and goat DNA.

Restriction fragment patterns of G+C-rich satellites of sheep and goat DNA were compared. The 1,712 g/cm3 satellites of both species appear homologous, consisting of repeats 760 base pairs long and showing coincidence of position of primary+ EcoRI, BamHI and most BspRI restriction target sites. The EcoRI and BamHI endonucleases produce mostly monomers of the repeating unit, while oligomers prevail in the A1uI and Bg1II digests. Species-specific differences in the frequency, position and mode of distribution of secondary+ restriction target sites for EcoRI, Bg1II and A1uI were observed. Unlike the 1,712 g/cm3 satellites, the 1,723 g/cm3 component of sheep DNA and the 1,719 g/cm3 material from goat DNA appear species--specific, since no homologous material could ever be detected in the DNA of the other species.

High resolution thermal denaturation of mammalian DNAs.

High resolution melting profiles of different mammalian DNAs are presented. Melting curves of various mammalian DNAs were compared with respect to the degree of asymmetry, first moment, transition breath and Tmi of individual subtransitions. Quantitative comparison of the shape of all melting curves was made. Correlation between phylogenetical relations among mammals and shape of the melting profiles of their DNAs was demonstrated. The difference between multi-component heterogeneity of mammalian DNAs found by optical melting analysis and sedimentation in CsCl-netropsin density gradient is also discussed.