Biomedical subjects

U Claussen

Publications and source records attributed to U Claussen.

At least 91 records · Page 5Linked to original sources

PubMed1994

Chromosomal mosaicism in two patients with epidermal verrucous nevus. Demonstration of chromosomal breakpoint.

Linear epidermal nevi are hamartomas that originate in embryonic ectoderm. For epidermal nevi associated with involvement of other systems, such as the skeleton or central nervous system, the term epidermal nevus syndrome has been introduced. Chromosomal aberrations have been suggested but not proven as an underlying cause. We performed cytogenetic studies of skin cells from two unrelated men who had a verruciform epidermal nevus. Variegated translocation mosaicism with an identical breakpoint localized at the long arm of chromosome 1 was present in both patients. Normal skin and blood lymphocytes showed normal karyotypes.

Adult↗

PubMed1994

[Ultrasound detection of suspected chromosome abnormalities in the 1st and 2nd trimester. Results of a prospective study].

4053 pregnancies were studied prospectively during 4 years (July 1988 to June 1992) with regard to the sonographical recognition of indications of chromosomal anomalies from 9 to 24 weeks, irrespective of the mother's age. The morphology of the fetal organs, the phenotype, the proportions of the fetal body, biometrical data and disorders of the placenta and the amniotic fluid were scrutinised. For the prediction of a chromosomal anomaly, a high sensitivity of 86.3% and specificity of 99.8% were found; the prevalence was 1.8%. The thickening of the nuchal fold or a nuchal oedema was the most significant fetal stigma and a guiding symptom in Turner's syndrome and in trisomy 21 and 18. When suspicious facts were found during ultrasonography, karyotyping was proposed after detailed counselling, especially to mothers below the age of 35. The extended sonographical examination is considered a non-invasive tool to differentiate the statistical age related risk of a chromosomal anomaly in each individual case.

Adolescent↗

PubMed1994

Chromosomes are highly elastic and can be stretched.

Direct manipulation of human chromosomes in metaphase spreads using glass needles revealed that the consistency of chromosomes varies depending on their moisture content. Chromosomes are soft and highly elastic under wet conditions and are hard when dry. The elasticity of chromosomes is comparable to rubber threads and can be used for stretching experiments under phase contrast microscopy, after Giemsa staining, and after GTG-banding. The coiling structures of the chromosomes appear to be stretched evenly along the length of the chromosome. Chromosomes fixed for only a short time have a tendency to tear when stretched more than 5 times their length. Under the experimental conditions used, chromosomes were preferentially torn in the centromeric region. Chromosome stretching on GTG-banded human chromosomes leads to a splitting of bands into their subbands. This may be useful for creating new high resolution ideograms possibly showing more than 1700 bands per haploid set.

Biomechanical Phenomena↗

PubMed1993

Rapid karyotyping in prenatal diagnosis: a comparative study of the 'pipette method' and the 'in situ' technique for chromosome harvesting.

Rapid karyotyping in the second and third trimesters has important implications for the management of pregnancies at risk. From September 1985 to March 1992, 735 amniotic fluid samples sent to our laboratory for rapid karyotyping from 64 different diagnostic centres of the Federal Republic of Germany were included in a comparative study on harvesting for chromosome analysis using the 'pipette method' or the 'in situ' technique. The average time between preparation of the amniotic fluid and verbal notification of the analysed karyotype was 5.41 days. The 'pipette method' needed on average 4.65 days, and the 'in situ' technique 5.97 days. In comparison with other more invasive techniques available for rapid karyotyping such as cordocentesis and placental biopsy, amniocentesis and subsequent chromosome harvesting using the 'pipette method' and/or the 'in situ' technique proved very useful and efficient. The overall incidence of chromosome aberrations was 15.3 per cent. The high rate of structural chromosome aberrations and uncommon aneuploidies found in our investigation (12 per cent) indicates that for rapid karyotyping in the second and third trimesters, conventional cytogenetic techniques cannot be replaced by faster techniques based on fluorescent in situ hybridization on interphase cells in the near future.

Amniotic Fluid↗

PubMed1993

A human pseudoautosomal gene encodes the ANT3 ADP/ATP translocase and escapes X-inactivation.

We report that the human ANT3 ADP/ATP translocase gene is a pseudoautosomal gene located proximal to the GM-CSF receptor alpha chain gene (CSF2RA). An ANT3-homologous locus, likely corresponding to a pseudogene, maps to chromosome 9. The ANT3 gene is transcribed from the centromere to the telomere and contains in its first intron a CpG island mapped 1300 kb from the telomere. This gene is transcribed from the Y chromosome and from the active and inactive X chromosomes. This gene thus escapes X-inactivation as predicted for genes belonging to the pseudoautosomal region.

Aneuploidy↗

PubMed1993

Rapid detection of trisomy 21 by quantitative PCR.

Chromosomal aneuploidy is a major cause of fetal loss and genetic disease. We have devised a polymerase chain reaction (PCR)-based test that allows prenatal detection of trisomy 21 in as few as 15 fetal cells within 1 day. A pair of fluorescein-tagged primers directs amplification of a 216-bp fragment of the human S100B gene on chromosome 21. Primers that direct amplification of a 165-bp fragment of the IGF1 gene on chromosome 12 are included to generate an internal standard for quantitation. After 31 cycles of PCR, the amounts of S100B and IGF1 amplification products are determined on an Automated Laser Fluorescent DNA Sequencer. In trisomic cells, the relative amount of the S100B product is approximately 1.5-fold higher than that from normal cells. The test may be useful for non-invasive prenatal diagnosis performed on fetal cells isolated from maternal blood.

Amniotic Fluid↗

PubMed1993

Isolation of a somatic cell hybrid retaining the der(16)t(12;16)(q13;p11.2) from a myxoid liposarcoma cell line.

We developed cell line LIS-3/SV40 from a primary myxoid liposarcoma with the t(12;16)(q13;p11.2) and trisomy 8. Following fusion of LIS-3/SV40 to mouse A9 cells, we obtained hybrid LIS-3/SV40/A9-B4 which contained the der(16) but neither the der(12) nor some of the normal human chromosomes, including 12 and 16. Furthermore, microclone library ML12q1315 was constructed from microdissected fragments of chromosome bands 12q13-15 and its microclones were found to span the breakpoint in LIS-3/SV40.

Aged↗

PubMed1992

A DNA library from an individual Beta patellaris chromosome conferring nematode resistance obtained by microdissection of meiotic metaphase chromosomes.

We have used a standard protocol established for human chromosomes to create a chromosome-specific plasmid library from a Beta patellaris chromosome conferring nematode resistance. A monosomic addition line was chosen carrying 18 sugar-beet (Beta vulgaris L.) and one wild-beet (B. patellaris) chromosome. The wild-beet chromosome can readily be identified as a univalent during metaphase I of meiosis. Highly synchronized meiotic material was used to excise the univalents from four pollen mother cells. The chromatin was lysed in a 1 nl collection drop, the DNA purified and restricted with Rsa I, ligated into a vector containing universal sequencing primers, and amplified by the polymerase chain reaction. The amplified DNA was inserted into a standard plasmid vector and cloned. Approximately 23,000 recombinant plasmids were obtained of which 15,800 could be utilized. Their insert sizes ranged from 80 to 700 bp with an average of 130 bp. 61 clones were tested in more detail by genomic Southern hybridization with sugar-beet and wild-beet DNA. Of these 32 plasmids (52%) contained single-copy inserts, 11 (18%) were specific for wild-beet DNA indicating that the DNA cloned originates in the univalent chromosome. The application of this technique for establishing high-density RFLP maps for discrete regions of plant genomes is discussed.

Animals↗

PubMed1992

Interstitial deletions in DiGeorge syndrome detected with microclones from 22q11.

DiGeorge syndrome in humans is characterized by immunodeficiency, heart defects, mental retardation and facial dysmorphism; cytogenetic analysis has shown that deletions at 22q11 occur in approximately 25% of cases. To generate DNA markers from this region, we have microdissected and microcloned band q11 of human Chromosome (Chr) 22. Nineteen thousand clones were obtained from material dissected from 20 chromosome fragments. Seventeen of 61 clones analyzed (28%) were repetitive, 27 (44%) gave no signal, and 17 (28%) detected single copy sequences of which ten mapped to Chr 22. Two of these were found to be deleted in patients with DiGeorge syndrome and either monosomy for 22q11-pter or visible interstitial deletions of 22q11. These two markers are also hemizygous in patients with no visible chromosomal abnormality, demonstrating that submicroscopic deletions are common in DiGeorge syndrome patients.

Blotting, Southern↗

PubMed1992

11p15.5-specific libraries for identification of potential gene sequences involved in Beckwith-Wiedemann syndrome and tumorigenesis.

Constitutional and somatic chromosomal abnormalities of the chromosome 11p15 region are involved in an overgrowth malformation syndrome, the Beckwith-Wiedemann syndrome (BWS), and in several types of associated tumors. The bias in parental origin for the different etiologic forms of this syndrome and for loss of heterozygosity in the tumors suggests that a gene (or genes) mapping to this region undergoes genomic imprinting. However, the precise localization of the locus (or loci) for the BWS and associated tumors is still unknown and more markers are required. We therefore isolated 11p15 markers from two libraries: the first one obtained by microdissection of the chromosome 11p15.5 region and the second one, a phage library, constructed from a hybrid cell line containing this region as its sole human DNA. Of 19 microclones isolated from the microdissection library, 11 were evolutionarily conserved. Four phage clones were isolated; one (D11S774) detected a highly informative variable number of tandem repeats (VNTR) and another (D11S773) a biallelic polymorphism. These clones were sublocalized using a panel of somatic cell hybrids that defines eight physical intervals in 11p15.5. Twenty-one clones map to the distal interval that harbors the BWS locus.

Animals↗

PubMed1992

PCR-mediated cloning of HpaII tiny fragments from microdissected human chromosomes.

Vertebrate DNA contains a small fraction of unmethylated CpG-rich DNA sequences, many of which include the 5' end of a gene. This fraction can be detected by its cleavage to tiny fragments with the methylation-sensitive restriction enzyme HpaII. Thus, the isolation of HpaII tiny fragments (HTFs) from a specific chromosome region may be a useful approach for making an inventory of the genes contained in it. Using microdissection, we have isolated DNA from human chromosome band 8q24.1. The DNA was digested with HpaII, ligated to a ClaI-cut pUC plasmid, and amplified with Taq DNA polymerase and the standard M13/pUC forward and reverse sequencing primers. The amplification products were used to construct an HTF library, which is enriched for CpG-rich single-copy clones.

Animals↗

PubMed1992

Quality control in routine chromosome analysis: prediction of total number of bands for the individual case analyzed.

In routine diagnosis it is of importance for each single analysis to provide information about the level of quality at which the chromosomal analysis has been performed. The number of bands counted can be used as a direct criterion for the level of quality. Statistical prediction methods via linear regression were employed in order to predict the total number of bands of a haploid set of the metaphase (TNB) from those of single chromosomes or pairs of chromosomes. It was demonstrated that TNB can be predicted successfully by counting bands on just one chromosome, where chromosomes C2, C4, C5 or C7 were found suitable for prediction. If pairs of chromosomes are used to predict TNB, we would recommend C4/C7, C5/C6, and C2/C9.

Chromosome Banding↗

PubMed1992

Band-specific localization of the microsatellite at D13S71 by microdissection and enzymatic amplification.

Microsatellite DNA consists of tandemly repeated simple DNA sequence motifs, the number of these repeats being polymorphic. These recently described polymorphisms are ubiquitously distributed throughout the human genome and are highly informative, making them ideal markers for linkage analysis. Physical localization of these microsatellites is an important prerequisite for aligning physical and genetic maps. We have physically mapped the microsatellite at D13S71, which has previously been assigned to chromosome 13. Band-specific mapping of D13S71 to the distal part of band 13q32, near 13q33, was achieved by microdissection of GTG-banded chromosomes and subsequent enzymatic amplification with a heminested PCR approach. Analysis of a panel of somatic cell hybrids confirmed this localization. The technique presented may also be useful in a variety of complex mapping situations and whenever the precise localization of very small (as small as 70 bp) DNA probes is necessary.

Base Sequence↗

PubMed1991

Microdissection of chromosome band 11p15.5: characterization of probes mapping distal to the HBBC locus.

Both cytogenetic and molecular genetic analyses of the 11p15.5 subband suggest it may contain loci important in the genesis of a wide variety of tumors such as rhabdomyosarcomas and Wilms' tumors as well as the congenital tumors associated with the Beckwith-Wiedemann syndrome. As a first step in further defining the involvement of this chromosomal region in these various maladies, a library was constructed from the specific microdissection of chromosomal fragments representing 11p15.5-pter. Of 98 microclones analyzed, 31 identified single copy human DNA sequences, 21 of which mapped to 11p15.5 while 10 mapped proximal to the HBBC locus. Five of the 11p15.5-positioned microprobes detected restriction fragment length polymorphisms at their homologous genomic loci for various enzymes. These microprobes are now being utilized in several ways in order to address the underlying basis of the Beckwith-Wiedemann syndrome and its associated tumors.

Animals↗

PubMed1991

Detection of APC region-specific signals by nonisotopic chromosomal in situ suppression (CISS)-hybridization using a microdissection library as a probe.

The chromosome region 5q22 harbouring the putative gene associated with adenomatous polyposis coli (APC) was microdissected and microcloned from GTG-banded human metaphase chromosomes. In order to determine the precise regional localization of the microdissected material, we used polymerase chain reaction amplified microclones as a bulk-probe in nonradioactive chromosomal in situ suppression hybridization of human metaphase spreads. Specific in situ hybridization signals were obtained on the long arm of chromosome 5 in accordance with the chromosomal region excised for the cloning procedure. The application of this detection system should provide a rapid and powerful tool for analyzing patients with translocations or microdeletions of a given chromosome region.

Adenomatous Polyposis Coli↗

PubMed1991

Characterization and mapping of microdissected genomic clones from the adenomatous polyposis coli (APC) region.

The gene associated with adenomatous polyposis coli (APC) has been mapped to the long arm of chromosome 5. To saturate the APC region with DNA markers, two independent microdissection libraries with an emphasis on 5q21.2-21.3 and 5q22 have been constructed from GTG-banded human metaphase chromosomes. PCR-amplified insert DNA of the primary amplificate used as a probe in chromosomal in situ suppression (CISS) hybridization of human metaphase spreads revealed region-specific signals at the chromosomal site that was excised for cloning. One hundred forty-two inserts, derived from both libraries, have been characterized in more detail. Deletion mapping analysis was performed with 17 single-copy clones on a hamster-human hybrid cell panel. Seven of these clones were located within two interstitial deletions of 6-8 Mb from APC-affected individuals around chromosome bands 5q21-22. The identification of new microclones mapping into these deletions and their use in isolating YAC clones should contribute to the construction of a contiguous physical map of the APC region.

Adenomatous Polyposis Coli↗

PubMed1991

A tumor chromosome rearrangement further defines the 11p13 Wilms tumor locus.

A sporadic Wilms tumor, WT-21, with an (11;14)-(p13;q23) reciprocal translocation has been identified. The translocation is found in tumor cells, but not in the patients' circulating lymphocytes. Molecular analysis of somatic cell hybrids segregating the derivative translocation chromosomes reveals a submicroscopic interstitial deletion at the translocation breakpoint, as well as a cytologically undetectable interstitial deletion in the nontranslocation chromosome 11, resulting in a homozygous deletion in 11p13. Pulsed-field gel analysis of tumor DNA indicates that the two deletions are indistinguishable, and the homozygously deleted region is less than 875 kb. The homozygously deleted regions of three other sporadic Wilms tumors overlap with the deleted region in WT-21, and the candidate cDNA clone for the 11p13 Wilms tumor gene described by Call et al. (Cell 60, 509-520, 1990) is included in the deleted region. These findings strengthen previous conclusions regarding the obligate location for the 11p13 WT locus and support the suggestion that the Wilms tumor gene has been cloned.

Animals↗

PubMed1991

New markers for the neurofibromatosis-2 region generated by microdissection of chromosome 22.

To identify new DNA markers around the neurofibromatosis-2 gene on human chromosome 22, the critical region (22q12-q13.1) was microdissected and microcloned from GTG-banded metaphase chromosomes. Eighteen thousand recombinant clones were obtained. Twenty-seven of 55 clones tested (50%) detected single-copy DNA sequences. Nine of nine clones analyzed in detail were found to map to chromosome 22. Interestingly one clone (EAN04) is part of the leukemia inhibitory factor gene which has previously been mapped to 22q11.2-q13.1. Four clones (EAN01, EAN47, EAN57, and EAN68) detect DNA polymorphisms. These probes were used to compare constitutional and tumor genotypes of 41 patients with acoustic neurinoma. Loss of constitutional heterozygosity was identified in 17 of 31 informative cases (55%). From our data we conclude that the microdissection library is a valuable resource for physical and genetic mapping studies in neurofibromatosis-2.

Chromosome Mapping↗