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  • 11
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The N1303K mutation was identified in the second nucleotide binding fold of the cystic fibrosis (CF) gene last year. We have gathered data from laboratories throughout Europe and the United States of America in order to estimate its frequency and to attempt to characterise the clinical manifestations of this mutation. N1303K, identified on 216 of nearly 15000 CF chromosomes tested, accounts for 1.5% of all CF chromosomes. The frequency of the N1303K allele varies significantly between countries and ethnic groups, being more common in Southern than in Northern Europe. This variation is independent of the AF508 allele. It was not found on UK Asian, American Black or Australian chromosomes. N1303K is associated with four different linked marker haplotypes for the polymorphic markers XV-2c, KM.19 and pMP6d-9. Ten patients are homozygous for this mutation, whereas 106 of the remainder carry one of 12 known CF mutations in the other CF allele. We classify N1303K as a “severe” mutation with respect to the pancreas, but can find no correlation between this mutation, in either the homozygous or heterozygous state, and the severity of lung disease.
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  • 12
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Mutations in the cystic fibrosis (CF) conductance transmembrane regulator (CFTR) gene have been detected in patients with CF and in males with infertility attributable to congenital bilateral absence of the vas deferens (CBAVD). Thirty individuals with CBAVD and 10 with congenital unilateral absence of the vas deferens (CUAVD) were analyzed by single-strand conformation analysis and denaturing gradient gel electrophoresis for mutations in most of the CFTR gene. All 40 individuals were pancreatic sufficient, but twenty patients had recurrent or sporadic respiratory infections, asthma/asthmatic bronchitis, and/or rhino-sinusitis. Agenesia or displasia of one or both seminal vesicles was detected in 30 men and other urogenital malformations were present in six subjects. Among the 40 samples, we identified 13 different CFTR mutations, two of which were previously unknown. One new mutation in exon 4 was the deletion of glutamic acid at codon 115 (ΔE115). A second new mutation was found in exon 17b, viz., an A→C substitution at position 3311, changing lysine to threonine at codon 1060 (K1060T). CFTR mutations were detected in 22 out of 30 (73.3%) CBAVD patients and in one out of 10 (10%) CUAVD individuals, showing a significantly lower incidence of CFTR mutations in CBAVD/CUAVD patients (P ≪ 0.0001), compared with that found in the CF patient population. Only three CBAVD patients were found with more than one CFTR mutation (ΔF508/L206W, ΔF508/R74W+D1270N, Rl 17H/712-1G→T), highlighting L206W, R74W/ D1270N, and R117H as benign CF mutations. Sweat electrolyte values were increased in 76.6% of CBAVD patients, but three individuals without CFTR mutations had normal sweat electrolyte levels (10% of the total CBAVD patients), suggesting that factors other than CFTR mutations are involved in CBAVD. The failure to identify a second mutation in exons and their flanking regions of the CFTR gene suggests that these mutations could be located in introns or in the promoter region of CFTR. Such mutations could result in CFTR levels below the minimum 6%–10% necessary for normal protein function.
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  • 13
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We present the genotype/phenotype correlation analysis for 16 cystic fibrosis (CF) patients who carry mutation R334W. Current age and age of diagnosis was significantly higher in the R334W/any-mutation group (P 〈 0.05 and P 〈 0.01), compared with the Δ508/Δ508 group. A slightly, but not significantly, worse lung function was found in the R334W/any-mutation group, when compared with the Δ508/Δ508 patients. The proportion of patients with lung colonization with bacterial pathogens was slightly, but not significantly, higher in the R334W/any-mutation group (71.4%), compared with the Δ508/Δ508 or R334W/Δ508 groups (55.5%). None of the R334W patients had meconium ileus but 60% were pancreatic insufficient (PI), a significantly lower proportion (P ≪ 0.001) than Δ508/Δ508 patients. Two R334W/N1303K compound heterozygous sisters were PI but discrepant for lung function. Two groups of three sibs with genotype R334W/Δ508 showed interfamilial discordant clinical data for lung and pancreatic function. The data provided here for mutation R334W demonstrate that this mutation is responsible for a less severe form of CF than Δ508. Interfamilial differences for PI and lung function suggest that other factors, viz. genetic, environmental and medical, contribute to the wide spectrum of clinical differences observed in CF patients with the same CF transmembrane conductance regulator genotypes.
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  • 14
    ISSN: 1546-1718
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] ΔF508 is the most frequent cystic fibrosis (CF) mutation and accounts for approximately 70% of CF chromosomes worldwide. Three highly polymorphic microsatellite markers have been used to study the origin and evolution of ΔF508 chromosomes in Europe. Haplotype data demonstrate that ...
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  • 15
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We describe a rare single-strand conformation polymorphism that occurs at nucleotide 3030 (G or A) in exon 15 of the cystic fibrosis transmembrane conductance regulator gene.
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  • 16
    ISSN: 1438-2199
    Keywords: rBAT ; SLC3A1 gene ; Cystinuria ; System b0,+-like
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The cDNAs of mammalian amino acid transporters already identified could be grouped into four families. One of these protein families is composed of the protein rBAT and the heavy chain of the cell surface antigen 4F2 (4F2hc). The cRNAs of rBAT and 4F2hc induce amino acid transport activity via systems b0,+ -like and y+L -like inXenopus oocytes respectively. Surprisingly, neither rBAT nor 4F2hc is very hydrophobic, and they seem to be unable to form a pore in the plasma membrane. This prompted the hypothesis that rBAT and 4F2hc are subunits or modulators of the corresponding amino acid transporters. The association of rBAT with a light subunit of ~40kDa has been suggested, and such an association has been demonstrated for 4F2hc. The b0,+-like system expressed in oocytes by rBAT cRNA transports L-cystine, L-dibasic and L-neutral amino acids with high-affinity. This transport system shows exchange of amino acids through the plasma membrane ofXenopus oocytes, suggesting a tertiary active transport mechanism. The rBAT gene is mainly expressed in the outer stripe of the outer medulla of the kidney and in the mucosa of the small intestine. The protein localizes to the microvilli of the proximal straight tubules (S3 segment) of the nephron and the mucosa of the small intestine. All this suggested the participation of rBAT in a high-affinity reabsorption system of cystine and dibasic amino acids in kidney and intestine, and indicated rBAT (named SLC3A1 in Gene Data Bank) as a good candidate gene for cystinuria. This is an inherited aminoaciduria due to defective renal and intestinal reabsorption of cystine and dibasic amino acids. The poor solubility of cystine causes the formation of renal cystine calculi. Mutational analysis of the rBAT gene of patients with cystinuria is revealing a growing number (~20) of cystinuria-specific mutations, including missense, nonsense, deletions and insertions. Mutations M467T (substitution of methionine 467 residue for threonine) and R270X (stop codon at arginine residue 270) represent approximately half of the cystinuric chromosomes where mutations have been found. Mutation M467T reduces transport activity of rBAT in oocytes. All this demonstrates that mutations in the rBAT gene cause cystinuria. Three types of cystinuria (types, I, II and III) have been described on the basis of the genetic, biochemical and clinical manifestations of the disease. Type I cystinuria has a complete recessive inheritance; type I heterozygotes are totally silent. In contrast, type II and III heterozygotes show, respectively, high or moderate hyperaminoaciduria of cystine and dibasic amino acids. Type III homozygotes show moderate, if any, alteration of intestinal absorption of cystine and dibasic amino acids; type II homozygotes clearly show defective intestinal absorption of these amino acids. To date, all the rBAT cystinuria-specific mutations we have found are associated with type I cystinuria (~70% of the chromosomes studied) but not to types II or III. This strongly suggests genetic heterogeneity for cystinuria. Genetic linkage analysis with markers of the genomic region of rBAT in chromosome 2 (G band 2p16.3) and intragenic markers of rBAT have demonstrated genetic heterogeneity for cystinuria; the rBAT gene is linked to type I cystinuria, but not to type III. Biochemical, genetic and clinical studies are needed to identify the additional cystinuria genes; a low-affinity cystine reabsortion system and the putative light subunit of rBAT are additional candidate genes for cystinuria.
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  • 17
    ISSN: 1572-9567
    Keywords: high temperature ; molten salts ; oscillating-cup viscometer ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An oscillating-cup viscometer for the measurement of the viscosity of molten materials from room temperature to 1400 K was developed. The instrument is described in detail and the working equations are presented. The operational behavior was tested with water at room temperature. Preliminary measurements show that the new viscometer is capable of measuring the viscosity of water at room temperature to within 0.2%. As the primary objective of this work is the establishment of standard reference data for high-temperature viscosity measurements in molten salts, molten metals, and molten semiconductors, references of earlier viscosity measurements of molten KNO3 are given.
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