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Biomedical subjects

J Ott

Publications and source records attributed to J Ott.

At least 181 records · Page 10Linked to original sources
PubMed1989

Assignment of autosomal dominant spinocerebellar ataxia (SCA1) centromeric to the HLA region on the short arm of chromosome 6, using multilocus linkage analysis.

A 7-generation kindred with the HLA-linked form of spinocerebellar ataxia (SCA1) was studied to determine whether the SCA1 gene maps centromeric or telomeric to the HLA loci. The DNA markers flanking the HLA-(A-B) region were used for polymorphism studies and multilocus linkage analysis. These two markers are the cDNA for the beta-subunit of HLA-DP, which is centromeric to HLA-(A-B), and the cDNA for coagulation factor XIIIa (F13A), which is telomeric to HLA-(A-B). Haplotypes were constructed using multiple polymorphisms for these two DNA markers, and pairwise linkage analysis revealed a maximum lod score of 2.18 for SCA1 versus HLA-DP at a recombination fraction of .05 and a maximum lod score of 0 for SCA1 versus F13A at a recombination fraction of .50. A possible crossover between HLA-(A-B) and HLA-DP was identified, but lack of samples from key individuals hampered the analysis. To clarify the phase and improve the analysis, the two chromosomes 6 for the crossover individual were separated in somatic cell hybrids. The results strongly favored the probability that the crossover occurred between HLA-(A-B-DR) and HLA-DP with SCA1 segregating with HLA-DP, consistent with a location centromeric to HLA-(A-B). Multilocus linkage analysis was used to evaluate further the location of SCA1 relative to F13A, HLA-(A-B), and HLA-DP; the results indicated that the SCA1 gene locus is centromeric to HLA-DP with odds of 46:1 favoring this most likely location over the second most likely location, i.e., telomeric to HLA-(A-B) between the HLA complex and F13A.

Animals↗
PubMed1988

Lead in human bones. Investigations on an occupationally non-exposed population in southern Bavaria (F.R.G.). II. Children.

The concentration of lead in three different bones (pelvic bone, cortical part of the mid-femur, petrous portion of the temporal bone) of 82 children who died in 1984 was determined by graphite furnace atomic absorption spectrometry. Three age classes were selected: less than 1 year (n = 25); 1-6 years (n = 18); 10-20 years (n = 35). The Pb content of all three types of bone increased steadily with age, and was most pronounced in the temporal bone. The differentiation of the bones with respect to the Pb concentration, as seen in adults, increased from babies (geom. mean, temporal bone 0.33 mg/kg wet wt., femur 0.33, pelvic bone 0.26) to pre-school children (0.62; 0.74; 0.49) and to youths (1.76: 1.18; 0.63). Babies showed no dependence of the Pb concentration in bone on sex. For pre-school children, in all three bones the concentration of Pb in girls was higher, while for youths, the concentration in males exceeded that found in females. In any sub-group the bones from urban children showed on average higher Pb concentrations than those from rural areas. For the mid-femur, and the age class 10-20 years, this difference was statistically significant. No difference was seen in the mean Pb concentration in bones of SIDS (sudden infant death syndrome) and non-SIDS babies, but in the temporal bone the distribution of the Pb concentrations for the SIDS group was significantly greater than that of the control babies.2off

Adolescent↗
PubMed1988

Genetic mapping of the Wiskott-Aldrich syndrome with two highly-linked polymorphic DNA markers.

The Wiskott-Aldrich syndrome (WAS) is an X-linked recessive genetic disease in which the molecular defect is unknown. In 15 families with WAS, seven restriction fragment length polymorphic loci from the X chromosome were used to map the disease locus. Of the eight intervals studied, the likelihood of the WAS gene lying between DXS7 (Xp11.3) and DXS14 (Xp11) was at least 128 times higher than that for any other interval. The most likely gene order is DXS84-OTC-DXS7-WAS-DXS14-DXS1-PGK-DXYS1. Close genetic linkage to DXS7 and DXS14 permits accurate prenatal diagnosis and carrier detection with greater than 98% confidence in fully informative WAS families.

DNA↗
PubMed1987

Protection of oligonucleotide primers against degradation by DNA polymerase I.

By use of a mutational assay employing an octadecamer with a mismatch in the center, it is shown that the introduction of phosphorothioate groups near the 5'-end can protect the mismatch against degradation by the 5'-3'-exonuclease activity of Escherichia coli DNA polymerase I. An optimal level of protection is achieved when the phosphorothioate groups are incorporated in at least the second and third internucleotidic linkages from the 5'-end. However, gel electrophoretic analysis as well as the use of an octadecamer with a mismatch closer to the 5'-end in the mutational assay reveals that degradation of the oligonucleotide is not completely blocked but only slowed down.

Base Sequence↗
PubMed1987

Goodness-of-fit tests for locus order in three-point mapping.

For the case of three-point linkage analysis, a simple goodness-of-fit test is proposed to test the order of gene loci. To use it for testing one locus order against another, one may apply the principle that evidence for one order comes from lack of fit of the observations to the other order. With n = 30 offspring from a phase known triple backcross mating, at a recombination fraction of 20% between adjacent loci, the test achieves a power of 80% (5% significance level). Interference (real interference as well as interference assumed in the analysis) increases power.

Chromosome Mapping↗
PubMed1987

The influence of exocyclic substituents of purine bases on DNA curvature.

Complementary oligonucleotides with 5' overhanging deoxyguanosine or deoxycytidine stretches, respectively, of the general form 5'-d(GGGCAARAAC).5'-d(CCCGTTYTTG), where R represents the bases adenine (A), hypoxanthine (base of inosine nucleoside, I), purine (R), 2-aminopurine (n2R), or 2,6-diaminopurine (n2,6(2)R) and where Y represents the pyrimidine bases thymine (T) or cytosine (C), have been chemically synthesized. After hybridization of complementary fragments, they were ligated to form multimers and analyzed by polyacrylamide gel electrophoresis. Anomalous gel migration was observed for the sequences 5'-d(AARAA) when the R.Y base pair was dA.dT, dI.dC, or dR.dT. All of these base pairs lack at least the amino group at position 2 of the purine base. The degree of anomalous gel migration was also related to the substituent at position 6 of the purine base. An amino group at position 6 was more effective than a carbonyl or a hydrogen in inducing anomalous gel migration. Additionally, the fragments 5'-d(GGGCAIAIAC).5'-d(CCCGTCTCTG), 5'-d(GGGCAIIIAC).5'-d(CCCGTCCCTG), and 5'-d(GGGCIIAIIC).5'-d(CCCGCCTCCG) were prepared in which increasing numbers of dA.dT base pairs are replaced by dI.dC base pairs. The degree of gel-migration anomaly of these sequences correlates with the number of dA.dT base pairs left in the five-base purine block. The data support the hypothesis that within the deoxyadenosine tracts, the base pairs fold into the minor groove at position 2 of the base to balance for the NH2 groups at position 6. This hypothesis explains the formation of a B'-form DNA structure for the deoxyadenosine tracts as well as DNA curvature.

DNA↗
PubMed1987

Tests of gene order from three-locus linkage data.

Exact tests for gene order are derived and compared for three loci using linkage data from phase-known, completely informative marker loci (i.e. parents are heterozygotes with at most one allele identical at each locus), or from triple back-cross matings. A simulation method, based on resampling genotypes of children, is introduced to obtain approximations to the distribution of the test statistics for general mating types in families consisting of children and parents, with or without grandparents, as are used in many studies in human gene mapping. The method is illustrated by an application to linkage data on chromosome 13.

Chromosome Mapping↗
PubMed1986

Heterogeneity in the map distance between X-linked agammaglobulinemia and a map of nine RFLP loci.

In nine family pedigrees in which X-linked agammaglobulinemia (XLA) is segregating, a multi-point linkage analysis has been carried out. In each family, the map distance, d, between XLA and a fixed point in a known map of nine RFLP loci on the X chromosome was estimated by calculating the log likelihoods, L(d). Using a new method, the 10-point likelihood was approximated by appropriately combining three 4-point likelihoods. Homogeneity tests (admixture tests) were performed showing clear evidence for heterogeneity of XLA.

Agammaglobulinemia↗
PubMed1986

Indication against genetic localisation of the human transcobalamin II gene (TC2) on chromosome 16.

The genetic locus of human transcobalamin II (TC2) is not yet known. The mouse transcobalamin II gene has been assigned to mouse chromosome 11, linked to hemoglobin A. This fact suggested a similar linkage of transcobalamin II in man, assigning it thus to human chromosome 16. Our linkage investigation in a family material of more than 600 individuals demonstrated absence of linkage between transcobalamin II and phosphoglycolate phosphatase, which is very closely linked to hemoglobin A on chromosome 16. Additionally we confirmed absence of linkage with the chromosome 16 gene marker system haptoglobin. These two gene marker systems are located far from each other, and the total length of chromosome 16 is estimated only about 100 cM. Together with recent results of investigations in somatic mouse-man cell hybrids, we conclude that TC2 is not located on chromosome 16. Additionally we found absence of linkage between transcobalamin II and 6-phosphogluconate dehydrogenase, rhesus blood group (both on chromosome 1), GC (chromosome 4), Esterase D (chromosome 13) and AG; absence of close linkage with "debrisoquin polymorphism".

Animals↗
PubMed1986

Y-linkage and pseudoautosomal linkage.

Presently existing computer program allow for an autosomal or an X-linked mode of inheritance of loci to be analyzed for genetic linkage. They do not, however, specifically allow for more general sex-linked modes of inheritance. This study proposes methods that permit the carrying out of linkage analyses of loci following a Y-linked or a pseudoautosomal mode of inheritance.

Alleles↗