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M Bentz

Publications and source records attributed to M Bentz.

At least 73 records · Page 4Linked to original sources
PubMed1995

Comparative genomic hybridization in chronic B-cell leukemias shows a high incidence of chromosomal gains and losses.

In chronic B-cell leukemias, fluorescence in situ hybridization has greatly improved the ability to detect certain chromosomal aberrations, as cells in all phases of the cell cycle are analyzed. To obtain a comprehensive view of chromosomal gains and losses, we applied the recently developed technique of comparative genomic hybridization (CGH) to 28 patients with chronic B-cell leukemias. CGH results were compared with those obtained by chromosome banding analysis and interphase cytogenetics. In 19 of the 28 cases, chromosomal imbalances were detected, including amplified DNA sequences in three instances. The most common aberrations included gains of chromosomal material on 8q and 12 as well as losses of 6q, 11q, 13q, and 17p. In 13 cases, CGH revealed chromosomal gains and losses not detected by banding analysis. In 8 of these 13 cases, discrepancies were further investigated using other methods, and in all instances, the CGH findings were confirmed. A limitation of detecting small deleted regions by CGH was found in one example of 18p. In conclusion, our data show that the results of banding analysis in chronic B-cell leukemias often do not reflect the chromosomal changes in the predominant cell clone. This may be one explanation for the as yet poor correlation between cytogenetic findings and clinical course in this group of neoplasms.

Chromosome Aberrations↗
PubMed1995

Quantitative analysis of comparative genomic hybridization.

Comparative genomic hybridization (CGH) is a new molecular cytogenetic method for the detection of chromosomal imbalances. Following cohybridization of DNA prepared from a sample to be studied and control DNA to normal metaphase spreads, probes are detected via different fluorochromes. The ratio of the test and control fluorescence intensities along a chromosome reflects the relative copy number of segments of a chromosome in the test genome. Quantitative evaluation of CGH experiments is required for the determination of low copy changes, e.g., monosomy or trisomy, and for the definition of the breakpoints involved in unbalanced rearrangements. In this study, a program for quantitation of CGH preparations is presented. This program is based on the extraction of the fluorescence ratio profile along each chromosome, followed by averaging of individual profiles from several meta phase spreads. Objective parameters critical for quantitative evaluations were tested, and the criteria for selection of suitable CGH preparations are described. The granularity of the chromosome painting and the regional inhomogeneity of fluorescence intensities in metaphase spreads proved to be crucial parameters. The coefficient of variation of the ratio value for chromosomes in balanced state (CVBS) provides a general quality criterion for CGH experiments. Different cutoff levels (thresholds) of average fluorescence ratio values were compared for their specificity and sensitivity with regard to the detection of chromosomal imbalances.

Chromosome Banding↗
PubMed1995

Image analysis in comparative genomic hybridization.

Comparative genomic hybridization (CGH) is a new technique by which genomic imbalances can be detected by combining in situ suppression hybridization of whole genomic DNA and image analysis. We have developed software for rapid, quantitative CGH image analysis by a modification and extension of the standard software used for routine karyotyping of G-banded metaphase spreads in the Magiscan chromosome analysis system. The DAPI-counterstained metaphase spread is karyotyped interactively. Corrections for image shifts between the DAPI, FITC, and TRITC images are done manually by moving the three images relative to each other. The fluorescence background is subtracted. A mean filter is applied to smooth the FITC and TRITC images before the fluorescence ratio between the individual FITC- and TRITC-stained chromosomes is computed pixel by pixel inside the area of the chromosomes determined by the DAPI boundaries. Fluorescence intensity ratio profiles are generated, and peaks and valleys indicating possible gains and losses of test DNA are marked if they exceed ratios below 0.75 and above 1.25. By combining the analysis of several metaphase spreads, consistent findings of gains and losses in all or almost all spreads indicate chromosomal imbalance. Chromosomal imbalances are detected either by visual inspection of fluorescence ratio (FR) profiles or by a statistical approach that compares FR measurements of the individual case with measurements of normal chromosomes. The complete analysis of one metaphase can be carried out in approximately 10 minutes.

Humans↗
PubMed1995

Comparative genomic hybridization in the investigation of myeloid leukemias.

Comparative genomic hybridization (CGH) was used for the examination of ten cases of myeloid leukemia (eight acute myeloid leukemias and two myelodysplastic syndromes). In five cases, genomic gains or losses were identified, which mapped to chromosomal regions known to be involved in this group of malignancies. In comparison to the results obtained by banding analysis, discrepancies were found in three of the ten cases; in two cases, chromosomal imbalances were not identified by CGH because they were present only in small subclones. In the other case, there were no evaluable metaphase cells for banding analysis; CGH revealed an overrepresentation of chromosome 8, which was confirmed by interphase cytogenetics with a chromosome 8-specific alphoid probe. All abnormalities revealed by CGH were confirmed by G-banding or subsequent interphase cytogenetic analysis, which demonstrates the high specificity of the method. Furthermore, in all cases, CGH identified the chromosomal imbalances present in the major clone as detected by banding analysis. The good correlation between CGH and chromosome banding results in myeloid leukemias makes this tumor a good model for the assessment of tools that are developed for automated and quantitative CGH analysis.

Aneuploidy↗
PubMed1995

Mapping of chromosomal gains and losses in prostate cancer by comparative genomic hybridization.

Comparative genomic hybridization (CGH) allows detection of chromosomal imbalances in whole genomes in a comprehensive manner. With this approach, ten cases of prostate cancer (seven primary tumors and three metastases) were analyzed. Frequent chromosomal gains detected by CGH involved chromosome arms 7q, 8q, 9q, and 16p, and chromosomes 20 and 22, as well as frequent losses of chromosome arms 16q and 18q, in at least three of the ten cases. Overrepresentation of chromosome arm 9q has not been described in published reports. The CGH data were compared with results of a loss of heterozygosity (LOH) study, in which complete allelotyping was performed in the same prostate tumors with 74 different polymorphic markers. In general, a high concordance between the CGH and LOH results was observed (92%). Tumors revealing discrepancies by CGH and LOH analysis were investigated further by interphase cytogenetics, and the resulting picture regarding the genomic alterations is discussed in detail.

Chromosome Aberrations↗
PubMed1995

Diagnosis and monitoring of chromosome aberrations in hematological malignancies by fluorescence in situ hybridization.

Besides its application in biological research, fluorescence in situ hybridization (FISH) is increasingly used for the cytogenetic analysis of human malignancies. Compared to conventional cytogenetic analysis, FISH allows delineation of specific numerical and structural chromosome aberrations in interphase cells (interphase cytogenetics). We have developed sets of genomic DNA probes for the identification of chromosome aberrations associated with chronic lymphocytic leukemia (CLL), chronic myeloid leukemias (CML), and acute myeloid leukemia (AML). In CLL, interphase cytogenetics will greatly contribute to the evaluation of the true incidence of specific chromosome aberrations and will provide the basis for more accurate correlations with the clinical outcome. The Philadelphia chromosome can be detected by FISH with high specificity and sensitivity in both CML and acute lymphoblastic leukemia. In CML, it can be used to better assess the cytogenetic remission status following therapy with interferon-alpha. Finally, in AML interphase cytogenetics provides a rapid and reliable technique for the identification of chromosome aberrations which are one of the most important prognostic factors in this disease. With the design of complex DNA probe sets and the development of digital microscopy and automated image analysis, it will be possible to use such disease-specific probe sets for monitoring residual disease following chemotherapy.

Acute Disease↗
PubMed1995

Identification of genetic imbalances in malignant lymphoma using comparative genomic hybridization.

In comparison to leukemias, the clinical relevance of chromosomal aberrations in non-Hodgkin's lymphoma (NHL) is not as well understood. This is primarily due to limitations of chromosomal banding techniques which have been the central methods for cytogenetic analysis. These techniques depend on the availability of fresh tumor tissue and the examination of metaphase cells which may not be representative for the major cell clone in vivo. In contrast, the new technique of comparative genomic hybridization (CGH) allows researchers to obtain a comprehensive view of chromosomal gains and losses by analyzing tumor DNA, which can be prepared from archival tissue samples. Results of CGH studies in three different types of lymphoproliferative disorders are outlined in this paper demonstrating that: (1) in chronic B cell leukemias, chromosomal aberrations are missed by banding analysis in a high proportion of cases, (2) CGH on paraffin-embedded tissue samples can be used for cytogenetic analysis within clinical multicenter trials and (3) DNA amplifications are more frequent in NHL than previously assumed. Thus, it can be expected that CGH will contribute both to the understanding of pathogenetic mechanisms and the identification of clinically relevant chromosome aberrations in NHL.

Chromosome Aberrations↗
PubMed1995

Comparative clinical study of the sure-closure device with conventional wound closure techniques.

The Sure-Closure device, designed for wound closure, harnesses the viscoelastic properties of the skin. It has been used in clinical studies in the past. We have evaluated the role of this device in complex wound problems and compared it to closure achieved by conventional wound closure methods such as skin grafts and flaps. A total of 40 patients with multiple wound etiologies were examined. We used the device under local and general anesthesia. In addition, we performed cost analysis on the use of the device and compared this to traditional methods. We found a cost reduction trend associated with the Sure-Closure method (p < .05). All of the 24 patients in whom the device was used to close the wounds had complete primary closure. The device is also easy to use. When used for delayed stretching, as in some of our patients, the compliance rate was high.

Adolescent↗
PubMed1995

CDKN2 gene deletion is not found in chronic lymphoid leukaemias of B- and T-cell origin but is frequent in acute lymphoblastic leukaemia.

Homozygous deletions of the cyclin-dependent kinase 4 (CDK4) inhibitor gene CDKN2 (p16, MTS1) have been demonstrated to occur frequently in human cancer cell lines of different origin. However, in most primary tumours the frequencies of CDKN2 deletions are not well defined. We studied primary samples of 100 patients with lymphoid leukaemias [B-lineage acute lymphoblastic leukaemia (ALL), n = 23; T-ALL, n = 7; B-cell chronic lymphocytic (B-CLL) or prolymphocytic (B-PLL) leukaemia, n = 50; T-CLL/T-PLL, n = 20] using fluorescence in situ hybridization (FISH) with eight overlapping cosmid clones covering the region on chromosome band 9p21 containing CDKN2. We did not observe any CDKN2 deletions in the 70 patients with chronic lymphoid leukaemias of B- or T-cell origin. Of the 23 patients with B-lineage ALL, one (4%) exhibited a CDKN2 deletion: in this patient, two clones were detected, one exhibiting a hemizygous and the other a homozygous deletion. On chromosome banding analysis, four patients with B-lineage ALL had a 9p aberration, whereas all CDKN2 copies were retained. In contrast, six of the seven (86%) patients with T-ALL exhibited CDKN2 deletions (homozygous, n = 4; hemizygous, n = 2). We conclude that hemizygous or homozygous deletions of the CDKN2 gene occur at high frequency in T-ALL and at low frequency in B-lineage ALL, supporting the role of this gene as a tumour suppressor, especially in T-ALL. However, from our data there is no evidence that CDKN2 is involved in the pathogenesis of chronic lymphoid leukaemias of B- or T-cell origin.

Adolescent↗
PubMed1994

Detection of chimeric BCR-ABL genes on bone marrow samples and blood smears in chronic myeloid and acute lymphoblastic leukemia by in situ hybridization.

The presence of BCR-ABL fusion genes has important diagnostic and prognostic implications in chronic myeloid leukemia (CML) and acute lymphoblastic leukemia (ALL). The CML-specific chimeric BCR-ABL gene with a break involving the major breakpoint cluster region (M-bcr) of the BCR-gene has been detected by means of fluorescence in situ hybridization (FISH). In this study, we present a FISH protocol that allows the detection of breaks in both the major and the minor breakpoint cluster region (m-bcr). Three hybridization signals of D107F9, a yeast artificial chromosome (YAC)-derived probe spanning the breakpoint regions of the BCR gene, were indicative of the translocation events. To increase the specificity further, this probe was combined with cos-abl 8, a cosmid probe flanking the breakpoint within the ABL gene for dual-color hybridization. Samples of 21 patients with CML, the ALL-derived cell line SUP-B15, and of seven patients with Philadelphia chromosome (Ph1)-positive ALL (three of them with breakpoints within m-bcr) were examined. BCR-ABL fusion was detected in all cases with high specificity (false-positive nuclei: mean, 0.1%). On cytogenetic preparations, the percentages of BCR-ABL-positive interphase cells ranged from 53% to 91%. Comparable efficiencies were achieved on blood smears. In conclusion, hybridization with D107F9 and cos-abl 8 allows unambiguous diagnosis of BCR-ABL genes and is likely to become an important tool for the monitoring of therapies in patients with CML and ALL.

Adult↗
PubMed1994

Molecular cytogenetic analysis of RB-1 deletions in chronic B-cell leukemias.

Deletions or translocations of 13q, most commonly involving band 13q14, belong to the most frequent structural chromosome abnormalities in B-cell chronic lymphocytic leukemia (B-CLL). In a combined metaphase and interphase cytogenetic study using conventional G-banding analysis and fluorescence in situ hybridization (ISH) we previously analysed the retinoblastoma susceptibility gene (RB-1) and its chromosomal locus 13q14 in 35 patients with chronic B-cell leukemias. We report here on the interphase cytogenetic analysis of 109 cases with chronic B-cell leukemias [B-CLL = 90; B-prolymphocytic leukemia (B-PLL) = 6, hairy cell leukemia (HCL) = 13]; a subset of 49 patients (B-CLL = 45; B-PLL = 4) was studied by conventional G-banding analysis. By G-banding, 5/45 (11%) patients with B-CLL had deletions or translocations affecting band 13q14; in contrast, ISH to interphase cells showed RB-1 deletion in 19/90 (21%) patients with B-CLL. No 13q14 abnormalities or RB-1 deletion were detected in patients with B-PLL and HCL. Our data confirm the high frequency of RB-1 deletions in B-CLL and further emphasize the possible pathogenetic role of this genomic region.

Adult↗
PubMed1994

Fluorescence in situ hybridization in leukemias: 'the FISH are spawning!'.

Fluorescence in situ hybridization (FISH) is a powerful tool for the analysis of chromosomal abnormalities in metaphase and interphase cells. Interphase cytogenetics has become an important technique for the analysis of leukemias, since in many cases it may be difficult to obtain metaphase spreads representative for the malignant clone(s). Using suitable DNA probes, leukemia samples can be screened for the most relevant chromosomal abnormalities. Alternatively, chromosomal imbalances can be identified by applying the new approach of comparative genomic hybridization. In this review, recent advances in the analysis of leukemia made possible by FISH are presented and future prospects of molecular cytogenetics are discussed.

Chromosome Aberrations↗
PubMed1993

High frequency of monoallelic retinoblastoma gene deletion in B-cell chronic lymphoid leukemia shown by interphase cytogenetics.

Inactivation of the retinoblastoma tumor-suppressor gene (RB-1) has been associated with tumorigenicity in various human malignancies. In chronic lymphoid leukemias of B-cell origin (B-CLL) an involvement of RB-1 has been suggested based on cytogenetic data. We examined RB-1 and its chromosomal locus 13q14 in 35 cases of B-CLL by dual-color in situ hybridization to interphase nuclei and by G-banding analysis of metaphase chromosomes. In one patient (pt) a monosomy 13, and in three other pts deletions involving or encompassing band 13q14 were detected by conventional cytogenetic analysis. In contrast, in situ hybridization to interphase nuclei showed a monoallelic RB-1 deletion in 11 cases (31%). One pt showed a translocation with the breakpoint in 13q1?4 on G-banding, but on in situ hybridization analysis the RB-1 signals were not affected. Our data show that RB-1 deletions can be diagnosed accurately by in situ hybridization on the one-cell level. The frequency of RB-1 deletions detected in this study is significantly higher than previously assumed in B-CLL, and seems to be in the same range as in retinoblastoma.

Alleles↗
PubMed1993

[Bone marrow involvement in Hodgkin's disease: MR tomography and chemical-shift imaging].

The ranking of magnetic resonance imaging (MRI) and chemical shift imaging (CSI) of the bone marrow was assessed in 30 patients in the initial staging of Hodgkin's disease or in the restaging after relapse. The results were compared with other staging procedures, especially trephine biopsies. Pathologic findings were divided into diffuse and focal lesions resulting in a better differentiation between malignant infiltrations and unspecific marrow reactions that are common in Hodgkin's disease. Diffuse changes were unspecific, a diffuse marrow infiltration could not be established in 7 patients. Focal lesions proved to be infiltrations in 6 of 7 patients; only in one case an unspecific marrow reaction was found on histology. CSI showed a pathological increase of the relative water signal in focal and diffuse marrow changes, and made no individual diagnostic contribution.

Adolescent↗
PubMed1993

Trisomy 12 in chronic lymphoid leukemias--a metaphase and interphase cytogenetic analysis.

Trisomy 12 has been shown to be one of the most common chromosome abnormalities in chronic lymphoid leukemias of B-cell origin, and some studies suggested that it predicts poor overall survival. We have prospectively studied 42 patients with B-cell chronic lymphocytic leukemia (B-CLL) and three patients with B-prolymphocytic leukemia (B-PLL) for the incidence of trisomy 12 and other chromosome 12 aberrations applying fluorescence in situ hybridization (ISH) and conventional G-banding analysis. Dual-color hybridization experiments using centromere-12-specific DNA probes were performed for interphase cytogenetics. A subset of patients (n = 11) was analyzed using a DNA library for painting of chromosome 12. The incidence of trisomy/partial trisomy 12 was 18% (8/45 patients; 6/42 with B-CLL and 2/3 with B-PLL) by fluorescence ISH, and 11% (5/45 patients; 4/42 with B-CLL including one patient with partial trisomy 12q13-qter, and 1/3 with B-PLL) on G-banding analysis. Four patients with trisomy 12 were detected by ISH alone. One of these patients only had 4.5% interphase cells with three fluorescence signals indicating the presence of a small subclone with trisomy 12. On G-banding analysis, three of the four patients had a normal karyotype, and one patient had no analyzable metaphases. In conclusion, fluorescence ISH to interphase nuclei is a sensitive method for detecting trisomy 12 in patients with chronic lymphoid leukemias.

Chromosome Banding↗
PubMed1993

Detection of trisomy 8 on blood smears using fluorescence in situ hybridization.

In this study, fluorescence in situ hybridization (ISH) with an alphoid probe was used for the detection of trisomy 8 on archival blood smears (BS). The results were compared with hybridization experiments performed on methanol/acetic acid fixed cells of cytogenetic preparations (CP) which are widely used for ISH. Five controls and 20 patients with myeloid leukemias were examined. In the controls, CP and BS had the same percentages of cells with two or three fluorescence signals. In 5/20 patients, trisomy 8 was detected both on CP and BS. Two of the patients had 7 to 10% interphase cells with three hybridization signals, indicating the presence of small subclones with trisomy 8; one of the subclones was not detected by G-banding analysis. The remaining 15 patients were disomic for chromosome 8; hybridization results were within the range of the controls both on CP and BS. We conclude that using a chromosome 8 specific alphoid probe, fluorescence ISH to interphase cells can be performed on BS with the same efficiency that is reached on methanol/acetic acid fixed cells of CP.

Adult↗
PubMed1991

Examination of the roles of glycoprotein Ib and glycoprotein IIb/IIIa in platelet deposition on an artificial surface using clinical antiplatelet agents and monoclonal antibody blockade.

The mechanism of platelet thrombus growth on an artificial surface is incompletely understood. While glycoprotein (GP)Ib and GPIIb/IIIa are required for normal attachment and thrombus formation on subendothelium, their roles in platelet deposition to artificial surfaces remain unclear. Using selected platelet inhibitors (aspirin [ASA], low molecular weight dextran, monoclonal antibodies 10E5 [v GPIIb/IIIa], and 6D1 [GPIb]) we examined the mechanism of platelet deposition to polyethylene (PE) surfaces under steady laminar and oscillatory flow conditions. Polyethylene-100 (PE-100) tubes (0.86 mm internal diameter) were perfused under steady laminar flow with citrated human whole blood reconstituted with 111indium-labeled platelets at 312 seconds-1 shear rate in the presence and absence of platelet inhibitors. The effect of oscillatory flow on platelet deposition was examined in a microwell system using 3/16-inch diameter discs of National Heart, Lung, and Blood Institute primary reference PE as the test surface. ASA and dextran did not significantly (P greater than .05) inhibit platelet deposition in laminar flow (not tested in oscillatory). Antibody 10E5 was a potent inhibitor (laminar less than 1%, P less than .0001, oscillatory less than 1.6%, P less than .01) of platelet deposition in both systems, and in this case, true adhesion (first attached layer) was blocked. Antibody 6D1 unexpectedly inhibited 70% of platelet deposition (P less than .01) in steady laminar flow and 56.5% in oscillatory flow (P less than .01). Scanning electron microscopy demonstrated platelets atop platelets in the controls, rare platelets in the 10E5 group, and a patchy monolayer of platelets in the 6D1 group. Transmission electron microscopy of cross-sections confirmed these observations. We conclude that the adhesion of the first platelet layer to an artificial surface requires GPIIb/IIIa. The data also suggest that GPIb is required for the development of the second layer in vertical platelet thrombus growth.

Adenosine Diphosphate↗