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Biomedical subjects

U Claussen

Publications and source records attributed to U Claussen.

At least 109 records · Page 6Linked to original sources
PubMed1991

Tuberous sclerosis in a child with de novo translocation t(3;12) (p26.3;q23.3).

We report on an 8-year-old boy with severe mental retardation, epileptic seizures, autistic behaviour, and X-ray CT findings of the skull characteristics for tuberous sclerosis. At the age of 9 years, first signs of adenoma sebaceum developed. Chromosomal analysis revealed a translocation t(3;12)(p26.3;q23.3). The parents were both healthy and had normal karyotypes. As non-random association of a chromosomal abnormality and tuberous sclerosis is hypothesized, a third locus for this disorder on 3p26 or 12q23 has to be taken in account.

Autistic Disorder↗
PubMed1990

Microdissection of banded human chromosomes.

Physical dissection of metaphase chromosomes is the most straightforward approach for the isolation of DNA sequences from specific chromosome regions. However, conventional microdissection techniques are too crude and inefficient for analysis of the human genome. Here we describe a technique for the precise dissection of single bands from GTG-banded chromosomes. Cells from normal amniotic fluid cell cultures are harvested by the pipette method. Microdissection is performed on an inverted microscope (magnification 1250X) with the help of extended siliconized glass needles and an electronically controlled micromanipulator. Enzymatic amplification of the dissected DNA allows the construction of band-specific DNA libraries from as few as 20 dissected chromosome fragments.

Cells, Cultured↗
PubMed1990

Construction and characterization of band-specific DNA libraries.

A universally primed polymerase chain reaction was developed to amplify DNA dissected from GTG-banded human chromosomes. The amplification products are cloned into plasmid vectors, which allow the rapid characterization of recombinant clones. Starting from 20-40 chromosome fragments, several thousand independent clones detecting single-copy sequences can be obtained. Although these libraries comprise only a few percent of the dissected DNA, they provide narrowly spaced anchor clones for the molecular characterization of chromosome bands and the identification of gene sequences. Here we describe the construction and characterization of DNA libraries for the Langer-Giedion syndrome chromosome region (LGCR, 8q23-24.1), Wilms tumor chromosome region 1 (WT1, 11p13), Prader-Willi syndrome/Angelman syndrome chromosome region (PWCR/ANCR, 15q11.2-12), meningioma chromosome region (MGCR, 22q12-13), and fragile X chromosome region (FRAXA, Xq27.3).

Base Sequence↗
PubMed1990

Microdissection of the Prader-Willi syndrome chromosome region and identification of potential gene sequences.

The Prader-Willi syndrome chromosome region on the long arm of human chromosome 15 was microdissected and microcloned from 20 GTG-banded metaphase chromosomes, and 5000 recombinant clones were obtained. Of these clones, 39% identify single-copy human DNA sequences, most of which map to the dissected chromosome region and are evolutionarily conserved in other species. Three of eleven clones studied in detail are deleted in several patients with Prader-Willi syndrome. The microclones will be useful for the physical characterization of the Prader-Willi syndrome chromosome region and the identification of the affected genes in this disease.

Adult↗
PubMed1990

Somatic cell hybrid and long-range physical mapping of 11p13 microdissected genomic clones.

Microdissection and microcloning of banded human metaphase chromosomes have been used to construct a genomic library of 20,000 clones that is highly enriched for chromosome 11p13 DNA sequences. Clones from this library have been mapped on a panel of human-rodent somatic cell hybrids that divides the region from distal p12 to proximal p14 into seven physical intervals, A total of 1500 clones has been isolated, 250 clones have been characterized, and 58 clones have been mapped. Six of the clones were used to complete a long-range physical map of 7.5 megabases through the region. Two of the clones are localized to the Wilms tumor (WT) region, three are localized to the aniridia (AN2) region, and two are localized to the region between WT and AN2. The library represents DNA sequences spanning a distance of approximately 13 x 10(6) base pairs, with an average density of one clone per 37,000 base pairs.

Animals↗
PubMed1990

Microdissection of the fragile X region.

We have microdissected and cloned the region around the fragile site at Xq27.3 on the human X chromosome. All of the clones tested map to the Xq27-Xq28 region, and detailed mapping on a panel of somatic cell hybrids indicates that the microdissected library contains sequences derived from both sides of the fragile X mutation. Some of these clones give signals in rodent DNA. This library demonstrates the power of microdissection for the identification of potential coding sequences near a disease locus and provides a promising resource for the identification of the fragile X mutation.

Animals↗
PubMed1989

Cloning defined regions of the human genome by microdissection of banded chromosomes and enzymatic amplification.

The molecular analysis of many genetic diseases requires the isolation of probes for defined human chromosome regions. Existing techniques such as the screening of chromosome-specific libraries, subtractive DNA cloning and chromosome jumping are either tedious or not generally applicable. Microdissection and microcloning has successfully been applied to various chromosome regions in Drosophila and mouse, but conventional microtechniques are too coarse and inefficient for analysis of the human genome. Because microdissection has previously been used on unbanded chromosomes only, cell lines in which the chromosome of interest could be identified without banding had to be used. At least one hundred chromosomes were needed for dissection and lambda vectors used to achieve maximum cloning efficiency. Recombinant phage clones are, however, more difficult to characterize than plasmid clones. Here we describe the dissection of the Langer-Giedion syndrome region on chromosome 8 from GTG-banded metaphase chromosomes (G-banding with trypsin-Giemsa) and the universal enzymatic amplification of the dissected DNA. Eighty per cent of clones from this library (total yield 20,000) identify single-copy DNA sequences. Fifty per cent of clones detect deletions in two patients with Langer-Giedion syndrome. Although the other clones have not yet been mapped, this result demonstrates that thousands of region-specific probes can be isolated within ten days.

Base Sequence↗
PubMed1989

Maternal origin of a de novo chromosome 8 deletion in a patient with Langer-Giedion syndrome.

The anonymous DNA probe L32, which defines the D8S48 locus within the Langer-Giedion syndrome chromosome region on the long arm of chromosome 8, was used to search for a common restriction fragment length polymorphism. A HindIII and an MspI polymorphism were detected (polymorphism information contents 0.25 and 0.19, respectively). Both polymorphisms were informative in the family of a Langer-Giedion patient carrying a de novo interstitial deletion 8q23-24.1. Lack of transmission of a maternal haplotype indicates that this deletion occurred during maternal gametogenesis. This finding contrasts with the frequent paternal origin of mutations in other microdeletion syndromes.

Chromosome Banding↗
PubMed1986

[Fetal neck edema--early sonographic indications of a chromosome abnormality].

Fetal nuchal edema is described as an early sonographic sign of a chromosomal anomaly. Eight cases of fetal nuchal edema were detected by sonography, and for this reason the fetal karyotypes were established by means of rapid karyotyping. Trisomy 21 (Down's syndrome) and the 45,XO constellation (Turner's syndrome) were most commonly found. In one case with trisomy 21, only a temporary occurrence of fetal nuchal edema could be identified. The pathogenesis of fetal edemas is discussed. If the likelihood of pathologic conditions can be ruled out by sonography, differentiated counseling for antenatal diagnosis is possible.

Abortion, Induced↗
PubMed1985

The embryotoxicity of cyclophosphamide in rabbits during the histiotrophic phase of nutrition.

After iv injection of cyclophosphamide (CP; 80 mg/kg) and dechlor-CP (60 mg/kg) on the 9th day of gestation (histiotrophic phase of nutrition) in rabbits, the concentrations of activated CP and activated dechlor-CP were determined fluorometrically in the maternal blood and in the yolk sac fluid. Activated CP and dechlor-CP could be measured in the maternal blood but not in the yolk sac fluid. This holds true for both the free as well as the protein bound form. During the histiotrophic phase of nutrition on the 9th day of gestation, the yolk sac wall seems to be a barrier for activated CP and dechlor-CP. This phenomenon has to be traced back on the oxazaphosphorinring activated in position C4 and not on the alkylating activity. Therefore, a direct effect of activated CP can be excluded as the main reason for the embryotoxicity of CP. Consequently, the effects of iv-injected CP on the entoderm of the visceral layer of the yolk sac placenta were investigated. Three, 6, 12, and 24 hours after CP injection, the maternal animals were laparotomized and the entoderm of the visceral layer of the yolk sac placenta in the mesometral parts of the blastoderms were prepared for electron microscopy. Like in the control group, 3 hours after CP injection no differences are found. Six hours after CP injection, a relatively flat cell-type can be observed, which is probably based on the reduced absorptive capability of the entoderm. Twelve hours after CP injection the entoderm cells are nearly uniformly of the columnar type; this is interpreted as a restored absorptive activity. Twenty-four hours after CP injection the columnar form of the entoderm cells and the reduced pinocytotic activity are interpreted as a state of secretion. During the histiotrophic phase of nutrition (9th day of gestation in rabbits), CP-induced inhibition of the absorptive activity of the entoderm cells might lead to a quantitatively and/or qualitatively changed nutrition of the developing embryo. This changed nutrition may be the source of the embryotoxic effects of CP.

Animals↗
PubMed1984

Exclusion of chromosomal mosaicism in prenatal diagnosis.

For use in prenatal diagnosis, tables were prepared giving the number of metaphases or clones, respectively, which must be analysed in order to detect fetal mosaicism of a given degree (= percentage of the aberrant cell population) or higher with at least 95% or 99% probability. Different tables are provided for the two techniques of chromosomal preparation: the colony method and the flask method.

Chromosome Aberrations↗