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Biomedical subjects

U Bonk

Publications and source records attributed to U Bonk.

At least 19 recordsLinked to original sources
PubMed1998

Two cases of fibrocystic breast disease with polysomy 18 as the sole clonal cytogenetic abnormality.

In the present study, we describe the occurrence of numerical alterations of chromosome 18 in two cases of benign fibrous/fibrocystic tumors of the breast, both of which were studied by conventional cytogenetic investigations and one of which was additionally tested by fluorescence in situ hybridization with the use of an alphoid centromeric probe specific for chromosome 18. Case 1 showed a tetrasomy 18 in 2 of 33 metaphases as the only clonal chromosomal aberration. Case 2 revealed both trisomy and tetrasomy 18 as clonal alterations in metaphases and interphase nuclei.

Adult↗
PubMed1997

Expression of HMGI-C, a member of the high mobility group protein family, in a subset of breast cancers: relationship to histologic grade.

The high-mobility-group (HMG) protein gene HMGI-C is apparently involved in the genesis of a variety of benign human solid tumors with rearrangements of chromosomal region 12q14-15 affecting the HMGI-C gene. So far, no expression of HMGI-C has been found in adult tissues, and no data are available on the expression of HMGI-C in primary human malignant tumors of epithelial origin. Therefore, we analysed the HMGI-C expression patterns in 44 breast cancer samples and 13 samples of nonmalignant adjacent tissue by hemi-nested reverse transcriptase-polymerase chain reaction for HMGI-C expression. There was no detectable expression of HMGI-C in any nonmalignant adjacent breast tissues analyzed. In contrast, we found expression in 20 of 44 breast cancer samples investigated. In invasive ductal tumors, expression was noted predominantly in tumors with high histologic grade: 17 of 21 breast cancer samples with histologic grade 3 but only three of 16 samples with histologic grades 1 or 2 showed expression of HMGI-C. In addition, all seven lobular breast cancer samples tested did not express HMGI-C. From these results, we concluded that HMGI-C expression may be of pathogenetic or prognostic importance in breast cancer.

Adult↗
PubMed1997

[Genetic studies of differential fatty tissue tumor diagnosis].

Adipose tissue tumors are often characterized by typical or even specific chromosomal alterations. In some of the cases the molecular background of these microscopically visible alterations was already elucidated. In myxoid liposarcomas the translocation t(12;16) creates a fusion gene between the CHOP gene and the FUS gene and in lipomas the HMGI-C gene becomes rearranged by structural aberrations involving chromosomal region 12q14-15. Based on examples of a lipoma, a well-differentiated liposarcoma, a myxoid liposarcoma, and an aggressive angiomyxoma it is demonstrated in the present paper how cytogenetic investigation can be used as an additional tool for an improved diagnosis of adipose tissue tumors. Furthermore, the detection of molecular mechanisms underlying the visible cytogenetic alterations will certainly significantly increase our knowledge about the pathogenesis of these diseases.

Adult↗
PubMed1996

Telomeric repeat fragment lengths are not correlated to histological grading in 85 breast cancers.

The mean telomeric repeat fragment (TRF) lengths of 85 breast cancer samples were determined. The TRF length varied between 7260 bp and 14570 bp (average 11370 bp) reflecting a unimodal distribution. There was no significant correlation between TRF length and the histological grade of the tumor. Neither were there differences in telomeric length between different histological types of tumors, in particular lobular and ductal types, nor correlations between TRF length and age of patient, tumor volume, lymph node status, or steroid receptor status. These results contradict the hypothesis that the telomere repeat fragment sizes represent limiting or promoting factors for the growth of breast cancer.

Breast Neoplasms↗
PubMed1996

A fibroadenoma with a t(4;12) (q27;q15) affecting the HMGI-C gene, a member of the high mobility group protein gene family.

An intracanalicular fibroadenoma of the breast showing a clonal chromosomal aberration t(4;12) (q27;q15) as the sole cytogenetic abnormality is described. In order to narrow down the breakpoint region on chromosome 12 on the molecular level we performed fluorescence in situ hybridization (FISH) analysis with a cosmid pool originating from a YAC-contig overspanning part of the region 12q14-15. We were able to narrow down the breakpoint to an approximately 230kb fragment belonging to the HMGI-C gene which maps within an area recently designated as MAR (Multiple Aberration Region). The chromosomal breakpoints of other frequent benign solid tumors, i.e. lipomas, uterine leiomyomas, and pleomorphic adenomas are clustered within the third intron of that gene.

Adolescent↗
PubMed1996

Significance of clonal chromosome aberrations in breast fibroadenomas.

Despite the high frequency of fibroadenomas of the breast, cytogenetic results are relatively limited. We describe our cytogenetic findings in 30 fibroadenomas. Of these, three showed clonal chromosome abnormalities, i.e., 46,XX,der(6)t(1;6)(q25;p21.3); 48,XX,del(6)(q21),r(11)(?),der(14)t(6;14)(q21;q32),+2mar; and 47,XX,+5.

Adolescent↗
PubMed1996

Structural aberrations of chromosome 6 in three uterine smooth muscle tumors.

Clonal karyotypic alterations of chromosome 6 in three uterine smooth muscle tumors are reported. In all cases an apparently identical breakpoint on the short arm of chromosome 6 was found. Two cases displayed the histologic features of cell-rich myomas with severe nuclear atypia but no clear evidence for malignancy. The remaining case was a primary uterine leiomyosarcoma of an 80-year-old patient showing an apparently balanced reciprocal chromosomal translocation, t(1;6)(p32-33;p21.3), as the sole karyotypic abnormality. This type of aberration has not been reported before in leiomyosarcomas. Because of the nuclear atypia in the other myomas with a breakpoint involving the short arm of chromosome 6 we feel that this cytogenetically recognizable but rare subgroup of uterine smooth muscle tumors warrants a careful clinical follow-up.

Adult↗
PubMed1996

Trisomy 18 in a canine thyroid adenoma.

A canine thyroid adenoma showing trisomy 18 as the sole clonal cytogenetic abnormality (9 of 30 analyzed metaphases) is reported. Because trisomies are a recurrent cytogenetic finding in human benign thyroid tumors as well, it is suggested that the molecular relationship between these trisomies and the development of thyroid tumors can be determined by comparative gene mapping.

Adenoma↗
PubMed1996

HMGI-C expression patterns in human tissues. Implications for the genesis of frequent mesenchymal tumors.

Cytogenetically visible aberrations of chromosomal region 12q14-15 in a variety of frequent benign human tumors reflect rearrangements of the HMGI-C gene. The mechanisms by which the HMGI-C gene contributes to tumorigenesis are mostly unknown, although frequently aberrant transcripts containing exons 1 to 3 of HMGI-C and ectopic sequences from other genes due to breaks within the third intron of HMGI-C are detectable. This is the first report analyzing human tissue samples mainly of mesenchymal origin by a highly sensitive polymerase-chain-reaction-based approach detecting HMGI-C expression. We found HMGI-C expression in embryonic tissue but no expression in any of several adult tissues tested except for two myometrial tissues. These data suggest that HMGI-C is mainly expressed in human tissues during embryonal and fetal development. Thus, its particular role for tumor development may be due to the expression of at least exons 1 to 3 rather than to the formation of fusion transcripts.

Adult↗
PubMed1995

Telomere repeat fragment sizes do not limit the growth potential of uterine leiomyomas.

We have compared the length of telomere repeat fragments (TRF's) in 19 uterine leiomyomas from 6 patients with the corresponding myometrium. The advantage of this study of TRF length is that cells from uterine leiymyoma and cells from corresponding myometrium do not contain any considerable proportions of other cells as revealed by analysis of clonality. In all tumor samples a loss of TRF length ranging from 1120 to 4690 bp was noted. There was no correlation between tumor volume or size of tumor population as revealed by histological examination and loss of TRF length. From the obtained TRF length data (an average myometrial TFR length of 13 kb and an average loss of TRF length in myoma cells of 83 bp per cell division) we concluded that TRF length reduction does not limit the growth potential of uterine leiomyomas.

Base Sequence↗
PubMed1995

Trisomy 8 and 18 as frequent clonal and single-cell aberrations in 185 primary breast carcinomas.

For cytogenetic investigations short-term cultures of 185 breast carcinomas (135 invasive ductal, 21 invasive lobular, 12 invasive ductal with intraductal components, seven heterogeneous, six intraductal, four invasive ductal and lobular) were prepared. Cytogenetic examinations revealed clonal abnormalities in 39 cases with a predominance of simple numerical chromosome changes, i.e., trisomies of chromosomes 7, 8, and 18. One hundred forty-six tumors did not show clonal abnormalities, but single-cell aberrations other than monosomies occurred in 79 of these tumors. Compared to cells of epithelial hyperplasia of the breast, amniotic fluid cells, and cells from pleomorphic adenomas cultivated using the same medium, the frequency of single-cell trisomies was significantly higher. Trisomy 8 was not only found as a clonal aberration in 10 cases but was also the most frequent non-clonal aberration. Trisomy 7 and 18 were also frequent clonal as well as non-clonal cytogenetic deviations.

Adult↗
PubMed1994

Evidence that metacentric and submetacentric chromosomes in canine tumors can result from telomeric fusions.

We have hypothesized that metacentric and submetacentric chromosomes frequently observed in malignant canine tumors are a result of telomeric fusions. Therefore cells from a canine mammary pleomorphic adenoma were transformed with a plasmid containing the SV40 'early region', known to cause telomeric associations. Compared with non-transformed adenoma cells, the cells had a higher proliferative capacity and expressed the large SV40-T-antigen. Karyotype studies showed the conversion from a normal to an aberrant karyotype with an increase of bi-armed chromosomes resulting from fusions of acrocentric chromosomes. In addition, the length of the telomeric repeats (TTAGGG) was determined for an early and a late passage of the transformed cells by Southern hybridization. The length of the telomeric repeats was apparently longer in the 5th than in the 38th passage. In situ hybridization with a telomere-specific DNA revealed interstitial telomeric repeats in the bi-armed chromosomes. We have concluded that these findings reflect the clonal expansion of head-to-head-telomeric fusions of canine acrocentric chromosomes leading to dicentric chromosomes with a very short distance between the two centromeres. Our results support the idea that the apparent centric fusions that have been described in some canine tumors may in fact be the cytogenetic products of head-to-head-telomeric fusions.

Adenoma, Pleomorphic↗
PubMed1993

Trisomy 8 as a recurrent clonal abnormality in breast cancer?

The results of cytogenetic investigations on one benign and 15 malignant breast tumors are described. Trisomy 7, 8, 18, and 21 and monosomy X occurred as clonal numerical aberrations, and inv(7)(q21q31) and t(4;12)(q21;p13) occurred as clonal structural aberrations. Only trisomy 8 was a recurrent karyotypic abnormality, however. Thus, we assumed that trisomy 8 as an early genetic change characterizes a subtype of ductal breast carcinomas.

Adult↗
PubMed1987

Standardizing microcolposcopy. Assessing the criteria for evaluating the presence and degree of cervical intraepithelial neoplasia.

We established criteria for the detection and grading of cervical intraepithelial neoplasia with microcolposcopy. These criteria were assessed for their accuracy through comparison with the histologic evaluation of cone biopsy or hysterectomy specimens in 26 highly selected cases. There was a positive correlation of 88.5% and no false-negative cases. Microcolposcopy, performed in a standardized manner, may be a valuable adjuvant to colposcopy.

Biopsy↗