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  • Articles: DFG German National Licenses  (2)
  • Interfacial polycondensation  (1)
  • Linkage disequilibrium  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Pharmaceutical research 12 (1995), S. 248-256 
    ISSN: 1573-904X
    Keywords: Nylon 610 ; Film ; Interfacial polycondensation ; Polymer ; Permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Nylon 610 is a hydrophilic polymer with considerable potential as a membrane for drug microencapsulation. To better understand drug transport through such membranes, the influence of the solvents and monomers used in the synthesis of nylon films were examined using a full factorial study. Nylon 610 films were synthesized by an interfacial polycondensation reaction using hexamethylenediamine (HD) in the water phase and sebacoyl chloride (SC) in the organic phase, which was a solvent blend of chloroform and trichlorotrifluoroethane at ratios of 1:1, 1:4, and 4:1. Monomer concentrations studied were 0.2, 0.4, and 0.6 M with respect to their appropriate phase, while the monomer ratios were 1:1, 3:1, and 1:3. The molecular weight, porosity, thickness, and crystallinity of the films were characterized. The transport of potassium chloride, hydrocortisone, and m-cresol was studied at 25°C as a function of the syntheses variables. Potassium chloride was selected to measure the porosity of the membrane. Hydrocortisone and m-cresol, a known solvent for nylon 610, were used to study pore and solution-diffusion transport, respectively. The molecular weight of the films was proportional to the chloroform concentration. As the molecular weight increased, film thickness, porosity, and hydrocortisone permeability increased. As the molecular weight decreased, film thickness and porosity decreased, while m-cresol permeability increased. These results can be explained on the basis of HD ability to readily partition into a good solvent such as chloroform permitting high molecular weight polymer to form before precipitation.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1435-232X
    Keywords: Key words Myotonic dystrophy ; CTG repeat ; Haplotype A ; Linkage disequilibrium ; Multistep model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The myotonic dystrophy (DM) mutation is an unstable (CTG) n repeat, present at a copy number of 5–37 repeats on normal chromosomes but amplified to 50–3000 copies on DM chromosomes. Previous findings in Caucasian populations of a DM founder chromosome raise a question about the molecular events involved in the expansion mutation. To investigate whether a founder chromosome for the DM mutation exists in the Japanese population, we genotyped families using polymorphic markers near the (CTG) n repeat region and constructed haplotypes. Six different haplotypes were found and DM alleles were always haplotype A. To find an origin of the (CTG) n repeat mutation and to investigate the mechanism of the expansion mutation in the Japanese population we have studied 90 Japanese DM families comprising 190 affected and 130 unaffected members. The results suggest that a few common ancestral mutations in both Caucasian and Japanese populations have originated by expansion of an ancestral n = 5 repeat to n = 19–37 copies. These data support multistep models of triplet repeat expansion that have been proposed for both DM and Friedreich's ataxia.
    Type of Medium: Electronic Resource
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