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U Claussen

Publications and source records attributed to U Claussen.

At least 19 recordsLinked to original sources
PubMed2006

Ferric iron is genotoxic in non-transformed and preneoplastic human colon cells.

Iron could be a relevant risk factor for carcinogenesis since it catalyses the formation of reactive oxygen species (ROS), which damage DNA. We previously demonstrated genotoxic effects by ferric iron using the human colon cancer cell line HT29. Here we investigated ferric iron in primary non-transformed colon cells and in a preneoplastic colon adenoma cell line (LT97), which both are suitable models to study effects of carcinogens during early stages of cell transformation. Genetic damage was determined using the Comet assay. Comet FISH (fluorescence in situ hybridization) was used to assess specific effects on TP53. Fe-NTA (0-1000 microM, 30 min, 37 degrees C) significantly induced single strand breaks in primary colon cells (500 microM Fe-NTA: Tail intensity [TI] 22.6%+/-5.0% versus RPMI control: TI 10.6%+/-3.9%, p<0.01) and in LT97 cells (1000 microM Fe-NTA: TI 26.8%+/-7.3% versus RPMI control: TI 11.1%+/-3.7%, p<0.01). With the Comet FISH protocol lower concentrations of Fe-NTA significantly increased DNA damage already at 100 and 250 microM Fe-NTA in primary colon and LT97 adenoma cells, respectively. This damage was detected as an enhanced migration of TP53 signals into the comet tail in both cell types, which indicates a high susceptibility of this tumor relevant gene towards Fe-NTA. In conclusion, Fe-NTA acts genotoxic in non-transformed and in preneoplastic human colon cells, in which it also enhances migration of TP53 at relatively low concentrations. Translated to the in vivo situation these results suggest that iron overload putatively contributes to a genotoxic risk during early stages of colorectal carcinogenesis on account of its genotoxic potential in non-tumorigenic human colon cells.

Adenoma↗
PubMed2006

Small supernumerary marker chromosomes--progress towards a genotype-phenotype correlation.

Small supernumerary marker chromosomes (sSMC) are still a major problem in clinical cytogenetics as they are too small to be characterized for their chromosomal origin by traditional banding techniques, but require molecular cytogenetic techniques for their identification. Apart from the correlation of about one third of the sSMC cases with a specific clinical picture, i.e. the i(18p), der(22), i(12p) (Pallister Killian syndrome) and inv dup(22) (cat-eye) syndromes, most of the remaining sSMC have not yet been correlated with clinical syndromes. Recently, we reviewed the available >1600 sSMC cases (Liehr T, sSMC homepage: http://mti-n.mti.uni-jena.de/~huwww/MOL_ZYTO/sSMC.htm). A total of 387 cases (including the 45 new cases reported here) have been molecularly cytogenetically characterized with regard to their chromosomal origin, the presence of euchromatin, heterochromatin and satellite material. Based on analysis of these cases we present the first draft of a basic genotype-phenotype correlation for sSMC for all human chromosomes apart from the chromosomes Y, 10, 11 and 13.

Adolescent↗
PubMed2006

A molecular cytogenetic study of chromosome evolution in chimpanzee.

We applied multitude multicolor banding (mMCB) in combination with a novel FISH DNA probe set including subcentromeric, subtelomeric and whole chromosome painting probes (subCTM) to characterize a Pan paniscus (PPA) cell line. These powerful techniques allowed us to refine the breakpoints of a pericentric inversion on chimpanzee chromosome 4, and discovered a novel cryptic pericentric inversion in chimpanzee chromosome 11. mMCB provided a starting point for mapping and high resolution analysis of breakpoints on PPA chromosome 4, which are within a long terminal repeat (LTR) and surrounded by segmental duplications, as well as the integration/expansion sites of the interstitial heterochromatin on chimpanzee chromosomes 6 and 14. Moreover, we found evidence at hand for different types of heterochromatin in the chimpanzee genome. Finally, shedding new light on the human/chimpanzee speciation, karyotypes of three members of the genus Pan were studied by mMCB and no cytogenetic differences were found although the phylogenetic distance between these subspecies is suggested to be 2.5 million years.

Animals↗
PubMed2006

Different breakage-prone regions on chromosome 1 detected in t(11;14)-positive mantle cell lymphoma cell lines and multiple myeloma cell lines are associated with different tumor progression-related mechanisms.

To better define secondary aberrations that occur in addition to translocation t(11;14)(q13;q32) in mantle cell lymphomas (MCL) and in multiple myelomas (MM), seven t(11;14)-positive MCL cell lines and four t(11;14)-positive MM cell lines were analysed by fluorescence R-banding and spectral karyotyping (SKY). Compared with published data obtained by G-banding, most chromosome aberrations were redefined or further specified. Furthermore, several additional chromosome aberrations were identified. Thus, these cytogenetically well defined t(11;14)-positive MCL and MM cell lines may be useful tools for the identification and characterization of genes that might be involved in the pathogenesis of MCL and MM, respectively. Since MCL and MM were found to have different alterations of chromosome 1, these were investigated in more detail by fluorescence in situ hybridization (FISH) and multicolor banding (MCB) analyses. The most frequently altered and deletion-prone loci in MCL cell lines were regions 1p31 and 1p21. In contrast, breakpoints in MM cell lines most often involved the heterochromatic regions 1p12-->p11, and the subcentromeric regions 1q12 and 1q21. These data are in accordance with previously published data of primary lymphomas. Our findings may indicate that different pathways of clonal evolution are involved in these morphologically distinct lymphomas harboring an identical primary chromosome aberration, t(11;14).

Cell Line, Tumor↗
PubMed2005

Evolution versus constitution: differences in chromosomal inversion.

We compared the chromosomal breakpoints of evolutionary conserved and constitutional inversions. Multicolor banding and human-specific bacterial artificial chromosomes were applied to map the breakpoints of constitutional pericentric inversions on human chromosomes 2 and 9. For the first time, we present a high-resolution analysis of the breakpoint regions, which are characterized by gene destitution, co-localization with fragile sites, multitude repeats as well as pseudogenes and, remarkably, a large sequence homology to the opposite breakpoint. In contrast, evolutionary inversion breakpoints lack such extensive cross-hybridizing regions and are often associated with fragile sites of the genome and low-copy repeats. These molecular characteristics gave evidence for different types of inversion formation and indicate that evolutionary inversions cannot originate from constitutional inversions like those of chromosomes 2 and 9. Finally, the constitutional inversion breakpoints were investigated on three different great ape species and on four test persons each bearing the same cytogenetically determined inversion on chromosomes 2 and 9, respectively. Our data indicate the existence of different molecular breakpoints for the two variant chromosomes.

Animals↗
PubMed2005

New insights into the evolution of chromosome 1.

A complex low-repetitive human DNA probe (BAC RP11-35B4) together with two microdissection-derived region-specific probes of the multicolor banding (MCB) probe-set for chromosome 1 were used to re-analyze the evolution of human chromosome 1 in comparison to four ape species. BAC RP11-35B4 derives from 1q21 and contains 143 kb of non-repetitive DNA; however, it produces three specific FISH signals in 1q21, 1p12 and 1p36.1 of Homo sapiens (HSA). Human chromosome 1 was studied in comparison to its homologues in Hylobates lar (HLA), Pongo pygmaeus (PPY), Gorilla gorilla (GGO) and Pan troglodytes (PTR). A duplication of sequences homologous to human 1p36.1 could be detected in PPY plus an additional signal on PPY 16q. The region homologous to HSA 1p36.1 is also duplicated in HLA, and split onto chromosomes 7q and 9p; the region homologous to HSA 1q21/1p12 is present as one region on 5q. Additionally, the breakpoint of a small pericentric inversion in the evolution of human chromosome 1 compared to other great ape species could be refined. In summary, the results obtained here are in concordance with previous reports; however, there is evidence for a deletion of regions homologous to human 1p34.2-->p34.1 during evolution in the Pongidae branch after separation of PPY.

Animals↗
PubMed2005

Chromosomics.

The term "chromosomics" is introduced to draw attention to the three-dimensional morphological changes in chromosomes that are essential elements in gene regulation. Chromosomics deals with the plasticity of chromosomes in relation to the three-dimensional positions of genes, which affect cell function in a developmental and tissue-specific manner during the cell cycle. It also deals with species-specific differences in the architecture of chromosomes, which has been overlooked in the past. Chromosomics includes research into chromatin-modification-mediated changes in the architecture of chromosomes, which may influence the functions and life-spans of cells, tissues, organs and individuals. It also addresses the occurrence and prevalence of chromosomal gaps and breaks.

Chromosomes↗
PubMed2005

Three cases with rare interstitial rearrangements of chromosome 1 characterized by multicolor banding.

In this report, we describe three unrelated patients with similar symptoms such as mental retardation, growth delay and multiple phenotypic abnormalities. GTG-banding analysis revealed karyotypes with add(1p) in two cases and an add(1q) in the third. Fluorescence in situ hybridization (FISH) analysis using high resolution multicolor banding (MCB) characterized the aberrations of the abnormal chromosomes 1 as a (sub)terminal duplication and inverted duplications, respectively. Although three different chromosomal regions i.e. 1p36.1, 1p36.2-->1p31.3 and 1q41-->1q44 were involved, all three patients had similar patterns of dysmorphic findings. These cases demonstrate the power of MCB in the characterization of small interstitial chromosomal aberrations and resulted in the characterization of three previously unreported congenital chromosome 1 rearrangements.

Abnormalities, Multiple↗
PubMed2005

Unusual small supernumerary marker chromosome (sSMC) 9 in a Klinefelter patient.

Small supernumerary marker chromosomes (sSMC) are small additional chromosomes characterizable for their origin only by molecular cytogenetic approaches. sSMC have been reported previously in four types of syndromes associated with chromosomal imbalances: in approximately 150 cases with Turner syndrome, 26 cases with Down syndrome and only one case each with Klinefelter syndrome and "Triple-X"-syndrome. Here we report the second case with an sSMC detected in addition to a Klinefelter karyotype. Molecular cytogenetics applying centromere-specific multicolor FISH (cenM-FISH) and a specific subcentromere-specific (subcenM-FISH) probe set characterized the sSMC as a dic(9)(:p12-->q11.1::q11.1--> p11.1:). The reported patient was described with hypogonadism, gynaecomastia plus a bronchial carcinoma. The patient's clinical features are discussed in connection with other Klinefelter cases and possible consequences of presence of the sSMC(9). Furthermore, a suggestion is made for the mode of sSMC-formation in this case.

Adenocarcinoma↗
PubMed2004

Molecular cytogenetic characterization of the mantle cell lymphoma cell line GRANTA-519.

Combining fluorescence R-banding, fluorescence in situ hybridization and spectral karyotyping allowed us to precisely define chromosomal breakpoints, gains, losses and a newly detected amplification in the human mantle cell lymphoma (MCL) cell line GRANTA-519. GRANTA-519 is characterized by the t(11;14)(q13;q32) resulting in overexpression of cyclin D1, a key player in cell cycle control. Hitherto unresolved complex rearrangements involve 1p, 1q, 3cen, 9p, 11q, 12p, 12q, 16p, 17p, and 18cen. Moreover, a 4- to 6-fold gain of sequences on 18q leads to a low-level amplification of the BCL2 gene and to an overexpression of the BCL2 protein. These results provide the basis for the identification of not only candidate oncogenes responsible for MCL in gained regions, but also for the identification of putative tumor suppressor genes in commonly deleted regions like 1p22, which would eventually enable functional studies of these genes.

Cell Culture Techniques↗
PubMed2004

Molecular-cytogenetic characterization of the origin and the presence of pericentromeric euchromatin on minute supernumerary marker chromosomes (SMCs).

Small supernumerary marker chromosomes (SMCs) in human can be defined as additional centric chromosome fragments smaller than chromosome 20. For most small or minute SMCs a correlation with clinical symptoms is lacking, mostly due to problems in visualizing their euchromatic content. Recently we described two new molecular cytogenetic approaches for the comprehensive characterization of small SMCs, excluding those few cases with neo-centromeres. Minute SMCs, consisting preferentially of alpha-satellite DNA, are characterizable in one step by the centromere-specific multicolor FISH (cenM-FISH) approach. For further characterization of minute SMCs and eventually present euchromatic content, the recently developed centromere-near-specific multicolor FISH (subcenM-FISH) technique can be applied. These two approaches are highly informative and easy to perform, as demonstrated in the present report on the example of a prenatal case with a minute SMC derived from chromosome 3 cytogenetically described as min(3)(:p12.1 --> q11.2:).

Centromere↗
PubMed2004

The hierarchically organized splitting of chromosome bands into sub-bands analyzed by multicolor banding (MCB).

To clarify the nature of chromosome sub-bands in more detail, the multicolor banding (MCB) probe-set for chromosome 5 was hybridized to normal metaphase spreads of GTG band levels at approximately 850, approximately 550, approximately 400 and approximately 300. It could be observed that as the chromosomes became shorter, more of the initial 39 MCB pseudo-colors disappeared, ending with 18 MCB pseudo-colored bands at the approximately 300-band level. The hierarchically organized splitting of bands into sub-bands was analyzed by comparing the disappearance or appearance of pseudo-color bands of the four different band levels. The regions to split first are telomere-near, centromere-near and in 5q23-->q31, followed by 5p15, 5p14, and all GTG dark bands in 5q apart from 5q12 and 5q32 and finalized by sub-band building in 5p15.2, 5q21.2-->q21.3, 5q23.1 and 5q34. The direction of band splitting towards the centromere or the telomere could be assigned to each band separately. Pseudo-colors assigned to GTG-light bands were resistant to band splitting. These observations are in concordance with the recently proposed concept of chromosome region-specific protein swelling.

Chromosome Banding↗
PubMed2004

Small supernumerary marker chromosomes (sSMC) in humans.

Small supernumerary marker chromosomes (sSMC), defined as additional centric chromosome fragments too small to be identified or characterized unambiguously by banding cytogenetics alone, are present in 0.043% of newborn children. Several attempts have been made to correlate certain sSMC with a specific clinical picture, resulting in the description of several syndromes such as the i(18p)-, der(22)-, i(12p)- (Pallister Killian syndrome) and inv dup(22)- (cat-eye) syndromes. However, most of the remaining sSMC including minute-, ring-, inverted-duplication- as well as complex-rearranged chromosomes, have not yet been correlated with clinical syndromes, mostly due to problems in their comprehensive characterization. Here we present an overview of sSMC, including the first attempt to address problems of nomenclature and their modes of formation, problems connected with mosaicism plus familial occurrence. The review also discusses the frequency of sSMC in prenatal, postnatal, and clinical cases, their chromosomal origin and their association with uniparental disomy. A short review of the up-to-date approaches available for sSMC characterization is included. Clinically relevant correlations concerning the presence of a specific sSMC and its phenotypic consequences should become available soon.

Chromosomes, Human↗
PubMed2004

Multicolor FISH probe sets and their applications.

Multicolor fluorescence in situ hybridization (FISH) assays are nowadays indispensable for a precise description of complex chromosomal rearrangements. Routine application of such techniques on human chromosomes started in 1996 with the simultaneous use of all 24 human whole chromosome painting probes in multiplex-FISH (M-FISH) and spectral karyotyping (SKY). Since then different approaches for chromosomal differentiation based on multicolor-FISH (mFISH) assays have been described. Predominantly, they have been established to characterize marker chromosomes identified in conventional banding analysis. Their characterization is of high clinical impact and is the requisite condition for further molecular investigations aimed at the identification of disease-related genes. Here we present a review on the available mFISH methods including their advantages, limitations and possible applications.

Animals↗
PubMed2003

Putative colon cancer risk factors damage global DNA and TP53 in primary human colon cells isolated from surgical samples.

This study describes a novel in vitro method in genetic toxicology that is based on detection of chemical-induced DNA damage connected with altered migration of TP53 in primary human colonocytes. Techniques were developed to isolate high numbers of human epithelial colon cells from surgical tissues. High quantities of viable cells were obtained per donor. The primary cells were treated with the endogenous risk factors trans-2-hexenal, and hydrogen peroxide. Global DNA damage and repair were measured by single-cell gel electrophoresis (Comet assay). We compared responses of primary colon cells to HT29clone19A, a differentiated human colon tumour cell line, for which the karyotype was analysed with 24-colour FISH. Both compounds were genotoxic in both cell types and most of the induced DNA damage was repaired after 30 min. Specific migration of TP53 was determined by fluorescence in situ hybridization (Comet FISH). Using primary colon cells, we quantified the migration of TP53 signals into the comet tails. In these cells TP53 was more sensitive than global DNA for genotoxicity induced by trans-2-hexenal and H(2)O(2). HT29clone19A cells cannot be used for Comet FISH because of their aberrant karyotype. The approach described allows us to obtain more knowledge of putative risk factors in colon carcinogenesis.

Aged↗
PubMed2003

De novo 9-break-event in one chromosome 21 combined with a microdeletion in 21q22.11 in a mentally retarded boy with short stature.

We report on a moderately mentally retarded 12-year-old boy of short stature showing the most complex chromosomal rearrangement (CCR) within a single chromosome ever described. A de novo derivative chromosome 21 was recognized in GTG-banding shortly after birth. However, the nature of the rearrangement remained obscure up to the application of the chromosome 21-specific centromere-near multicolor-FISH (subcenM-FISH) probe set and of six selected locus-specific probes along chromosome 21. An unbalanced 9-break-event was uncovered with breakpoints in 21p13, 21p13-->12, 21q11.2, 21q21.1, 21q22.11, 21q22.11, 21q22.12, 21q22.22 and 21q22.3. A deletion of 21q22.11 was detected by application of the BAC probe bk249H10. The karyotype can be described as 46,XY,der(21)(:p13-->p1213::q22.3-->q22.22:: q11.2-->p1213::q11.2-->q21.1::q22.11-->q21.1::q22.12--> q22.22::p13-->p13). The clinical signs can either be due to gene inactivation in connection with structural changes at the break and fusion regions, to the building of new fusion genes within the CCR and/or to the deletion of genes in 21q22.11.

Abnormalities, Multiple↗