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E Gebhart

Publications and source records attributed to E Gebhart.

At least 55 records · Page 3Linked to original sources
PubMed1995

Determination by interphase-FISH of the clonality of aberrant karyotypes in human hematopoietic neoplasias.

Interphase-FISH (fluorescence in situ hybridization) studies have been devoted to the determination of clonality of aberrant karyotypes in human leukemia. Various levels of its extent have been examined, including the meaning of a single aberrant karyotype as representing a microclone, the use of FISH to confirm clonality in bi- or multiclonal leukemia, the estimation of the residual (aberrant) clone after contrasexual bone marrow transplantation, and the redetectability in interphase of the abl/bcr rearrangement. The quantitative findings of all these lines of interphase FISH analyses were based on the comparison with data from a large-scale "control" study on normal cells using the same DNA probes which have been chosen for the determination of clonality, i.e. centromeric DNA probes for chromosomes #1, #3, from #6 to #12, from #15 to #18, #20, X and Y, and a specific probe for the abl/bcr rearrangement. In addition, the validity of interphase-FISH analysis on classical bone marrow smears was examined. As a common outcome it was concluded that interphase-FISH technique is a valuable tool for defining clonality of karyotypic changes and, as a consequence, yields additional prognostic information in many human leukemias. It is recommended to perform interphase FISH in routine cytogenetics of leukemia, whenever reasonable.

Adult↗
PubMed1995

Therapy with OKT3 monoclonal antibody in refractory T cell acute lymphoblastic leukemia induces interleukin-2 responsiveness.

Administration of cytokines to patients with leukemia or lymphoma may recruit dormant malignant cells into cell cycle and thus make them more susceptible to chemotherapy. We treated a patient with refractory T cell acute lymphoblastic leukemia (ALL) with OKT3 monoclonal antibody and observed a dramatic but transient decrease of lymphoblasts. The T ALL cells were rather mature by morphology and immunophenotyping, expressing CD7, CD4, CD8 and CD3 surface antigens and nuclear TdT. Cytogenetic analysis revealed inversion of chromosome 14(q11q32.1). A total of 500 mg OKT3 (maximum dose 50 mg/day) was given. A decrease of lymphoblasts in the blood and a reduction of spleen size was observed. Complement levels dropped remarkably. Despite increasing serum levels of tumor necrosis factor, treatment was well tolerated overall. CD3 therapy induced strong IL-2 responsiveness of the lymphoblasts. Thus, OKT3 antibody treatment not only significantly decreased CD3-positive tumor cells, but also induced IL-2-mediated proliferation. This may also allow sequential application of CD3 and IL-2 to render certain T cell tumors more susceptible to chemotherapy.

Adult↗
PubMed1995

[Can an extremely elevated radiosensitivity in patients be recognized by the in-vitro testing of lymphocytes?].

BACKGROUND: We have examined the in-vitro radiosensitivity of lymphocytes in patients with extreme acute and chronic reactions after curative radiotherapy under the assumption of increased genetic radiosensitivity. PATIENTS AND METHODS: 16 patients (14 females, 2 males, age 40 to 69 years) were retrospectively examined 1 to 108 months after radiotherapy. All had undergone definitive or postoperative curative radiotherapy for cancer (12 breast cancer, 2 lung, 1 bladder, and 1 head and neck cancer). None of them had known genetic disorders with increased radiosensitivity. Four patients were considered as having probably increased radiosensitivity; they had shown poor tolerance to radiotherapy (1 severe acute reaction with cessation of radiotherapy in bladder cancer and subsequent bladder shrinkage after 45 Gy, 1 acute skin reaction well above average with subsequent fibrosis after irradiation for regional recurrence of breast cancer, 1 radiation myelitis after palliative irradiation with 5 x 5 Gy for lung cancer, 1 severe acute reaction after mediastinal irradiation for lung cancer). Twelve patients were considered as having normal tolerance to radiotherapy. They had tolerated radiotherapy well with normal acute reactions and no or minimal signs of late radiation sequelae. Lymphocyte cultures were prepared from all patients and irradiated with 0.7 and 2 Gy, respectively; 1 culture served as control (0 Gy). Chromosomes 1, 2, and 4 were stained using fluorescence in-situ hybridization (FISH) with a 3-colour-chromosome-in-situ suppression technique. Chromosomal breaks were counted in 200 to 1000 mitoses. Radiation sensitivity was expressed as radiation-induced breaks per mitoses corrected for breaks at 0 Gy. The probes were coded and the examiner did not know the clinical course. RESULTS: Significant differences in interindividual radiation sensitivity were detectable. The frequency of radiation-induced breaks/1000 mitoses ranged from 70 to 556 after 0.7 Gy and from 420 to 1210 after 2 Gy. The 4 patients with increased clinical radiation sensitivity showed also increased chromosomal radiation-induced damage as compared to the 12 patients with normal radiation tolerance (469 +/- 103 vs. 126 +/- 79 breaks/1000 mitoses induced by 0.7 Gy, p = 0.0011, and 864 +/- 258 vs. 574 +/- 119 breaks/1000 mitoses induced by 2 Gy, p = 0.019). CONCLUSIONS: Patients with increased clinical radiosensitivity exhibited increased chromosomal damage in lymphocytes in vitro measured with chromosome painting with a FISH-technique. This technique may be useful to detect patients with severely enhanced radiosensitivity. The results suggest that if radiosensitivity is abnormally elevated this may be present and detectable in different organs.

Aged↗
PubMed1994

Karyotypic characterization of human T-cell lines immortalized by Herpesvirus saimiri.

Herpesvirus saimiri subgroup-C strains transform non-neoplastic human T lymphocytes in vitro to antigen-independent continuous growth. The karyotypes of 8 of these T-cell lines, derived from peripheral blood or bone marrow, are analyzed here. In general, these lines showed a normal diploid karyotype, although one of them had acquired a clonal chromosomal rearrangement after 21 months in culture. Chromosomally aberrant cell clones were found more frequently in cell lines derived from blood lymphocytes of leukemia patients than in cultures from healthy donors. However, the observed aberrations, some of which were defined in detail using chromosome in situ suppression hybridization (CISS) with chromosome-specific recombinant DNA libraries, did not show any relation between the various cell lines nor to the respective types of leukemia.

Cell Line↗
PubMed1994

Tetrasomy 8 as a clonal anomaly in myeloid neoplasias.

Tetrasomy of chromosome 8 as a sole anomaly is apparently extremely rare in acute non-lymphocytic leukemia (ANLL): Only two cases have been reported, one of ANLL (M5b) with this karyotype. Very recently, another case was reported of a myelodysplastic syndrome (MDS) with isolated tetrasomy 8. We report tetrasomy 8 in four cases of ANLL, two of them with M5 and one with M1 subtype. Although in the latter case, tetrasomy 8 was evident in all karyotypes analyzed, in all other cases it constituted a subpopulation of cells other than those with trisomy 8 and those with a normal karyotype (in only one case another change was evident in the karyotype). Using fluorescence in situ hybridization (FISH), the proportion of tetrasomic cells was determined in interphase nuclei. By this technique, small cell populations (3-9%) were detected in three additional trisomy cases. An additional "control" group of five trisomy cases did not show a significant population of tetrasomic interphase nuclei. The data show that tetrasomy 8, if present as a sole anomaly in ANLL, may play a rather specific role for the subtype, and probably for the progression of myeloid neoplasia as well.

Adult↗
PubMed1993

Cytogenetic studies in lymphocytes of patients with rectal cancer.

Spontaneous and clastogen-induced chromosomal instability in a high-risk group (i.e, 33 patients with rectal carcinomas) was investigated using peripheral blood lymphocytes as target cells. In addition to the analysis of spontaneous and clastogen-induced chromosome aberrations, this study also included classical karyotype analysis and scoring of sister chromatid exchanges (SCE) in some of the patients. Diepoxybutane (DEB), 4-nitroquinoline-1-oxide (NQO), and bleomycin were used as standard clastogens. Lymphocytes of healthy control individuals were studied in parallel with each cancer patient. While only slight but significant differences could be detected of the average spontaneous, DEB- and bleomycin (G2)-induced chromosome breakage between patient and control lymphocytes, individual patients and two of the control individuals showed a more distinct increase in the frequency of the studied end points. These increases were documented by a variegated mosaicism of karyotypic changes and by an increased breakage rate induced by the clastogens. Neither the bleomycin-exposure in the G1 phase nor SCE was capable of detecting differences between the patients and controls. Of particular interest in the sense of high-risk individuals were seven patients and two control persons whose lymphocytes exhibited increased chromosomal sensitivity under more than one of the studied experimental conditions.

4-Nitroquinoline-1-oxide↗
PubMed1992

Multiple chromosomal changes and karyotypic evolution in a patient with myelofibrosis.

Several subclones were identified in unstimulated peripheral blood cells from a patient with chronic myeloproliferative disease, which was classified as myelofibrosis by morphologic terms. These subclones were characterized by an unusual number of different karyotype anomalies. Some of the more complex chromosomal rearrangements could be clearly defined by fluorescence in situ hybridization. Chromosome arms involved in clonal aberrations were 1q, 3p, 6p, 7q, 11q, 13q, 15q, 17q, 18p, and 20q. Reconstruction of karyotype evolution was attempted by karyotypic analysis of 100 metaphase spreads each in two separate investigations.

Aged↗
PubMed1992

Cytogenetic, oncogenetic, and histopathologic characteristics of colorectal carcinomas with 17p abnormalities.

From a total of 65 colorectal adenocarcinomas studied by cytogenetic methods, 33 were selected for the present study; in addition to other karyotypic anomalies, these 33 showed a loss of the short arm of chromosome 17. This loss was either the result of a deletion or rearrangement, or caused by the loss of a whole chromosome 17. The 17p- tumors were characterized by a high grade of karyotypic abnormality including a high incidence of cases with double minutes. A gain of chromosomes 2, 7, 19, and 20, and the loss of chromosome 18 and the Y-chromosome were the most frequent numerical anomalies associated with 17p-, as were structural changes of chromosomes 1 and 5. The most impressive difference in the pattern of proto-oncogene over-expression between the 17p- tumors and those without this anomaly was the significantly increased frequency of cases with c-erbB over-expression. Some significant, but also loose, associations were found between cytogenetic/oncogenetic and histopathologic or clinical features of these tumors. The patterns of genetic changes in cells of colorectal carcinomas may thus reflect the potential of the future development, rather than the present clinical features, of the respective tumor. Therefore, the character of the change seems to be more prognostic than diagnostic.

Adenocarcinoma↗
PubMed1992

Anticlastogenicity in cultured mammalian cells.

Basic and applied research on anticlastogenicity has not only revealed valuable evidence on the mechanisms governing the induction of chromosomal aberrations by environmental mutagens, but also contributed effective ideas on a practical employment of this knowledge for the protection of individuals at risk. Considering the basic role played by chromosomal anomalies in oncogenesis, additional weight must be attributed to studies on anticlastogenicity. The employment of human cells in this kind of study dates back to 1969/70, while classical mammalian cell systems were used only later on. Various modes of application of both clastogens and anticlastogens (AC) were examined, but simultaneous addition to the cultures of both reagents was the most favored way. A wide spectrum of cytogenetic endpoints can be studied, but differences can be demonstrated with regard to efficacy of inhibitors on different types of cytogenetic changes, e.g., open breaks vs. rearrangements, but also vs. SCEs. Depending on their mode of influence on this spectrum, ACs can be arranged in various categories which are of practical importance, for instance, with regard to their oncogenic potential. A wide variety of factors was shown to influence AC action, e.g., time and mode of application of the test substances, physiologic and metabolic features of the cell types studied, type and mechanism of the clastogen used, etc. The addition of S9 mix can drastically change the patterns of efficacy of the ACs. The combined application of two or more ACs, as far as investigated, apparently neither potentiates nor even merely adds their effects.

Animals↗
PubMed1991

Changes in the proliferation of human lymphocytes induced by several cytostatics and revealed by the premature chromosome condensation technique.

Premature chromosome condensation was induced by cell fusion in stimulated human lymphocytes treated with different cytostatics. Changes in the proportion of the cell-cycle stages were investigated after 72 h of culture. Although it has been reported that some agents which induce severe DNA damage accumulate cells in G2, our results have shown some differences in the modes of action of the different tested chemicals. These variations could be due to several factors like mechanisms of action of the drugs, sensitivity of lymphocyte subpopulations to the cytostatics, inter- and intra-individual variability in the response of donors.

Cell Cycle↗
PubMed1991

[Ocular manifestations in a patient with Cockayne syndrome and simultaneous reduced DNA repair].

A 14 year old white boy presented with the typical clinical findings of Cockayne syndrome. Photodermatosis was known since the third week of life. He had disproportionate short stature with a short trunk, long limbs and flexion contractures of the large joints. He also was cachectic and prematurely aged. He had a typical facies. The hearing was slightly impaired. The prominent ocular findings were corneal opacifications, salt and pepper like retinal pigment epithelial changes and optic atrophy. On fibroblast culture the DNA repair activity is usually normal in patients with Cockayne syndrome. The DNA repair activity in our patient however was markedly reduced to 25% of normal. On lymphocyte culture a significantly increased 4-nitroquinoline-1-oxide sensitivity (cytotoxicity and increased break-rate) was found. These findings indicate that the boy has a specific variant of Cockayne syndrome with simultaneously reduced DNA-repair activity.

Adolescent↗
PubMed1990

[Chromosome mutagenicity of a 193 nm Excimer laser].

Considering the fundamental role somatic mutations play in carcinogenesis, inducing mutations by any form of therapy should be avoided as far as possible. The mutagenicity of UV irradiation in the wavelength range of 248 to 310 nm is well established. The data on shorter wavelengths, e.g. 193 nm, however, are so far not clear-cut. Therefore, the potential chromosome-damaging effect of a 193 nm excimer laser was examined in the present study. Cultures of primary human fibroblasts and the Chinese hamster cell line CHO were the object of examinations. The in situ preparation technique used allowed detection of a locally limited clastogenic (chromosome damaging) effect in the neighborhood of the irradiated area. A slight increase in the frequency of chromosome aberrations could be observed in the area close to the laser-exposed field, which was attributed to the fluorescence generated by the laser under the given experimental conditions. Quantitative comparison with the data obtained from experiments with 254 nm irradiation from a UV lamp or exposure to 248 nm excimer laser-pulse irradiation, however, made the former activity appear somewhat insignificant. If one considers the practical aspects of the new laser surgery, the chromosome-damaging effect of the 193 nm pulse laser seems to be negligible.

Animals↗
PubMed1989

The activity of bleomycin and modifiers of its clastogenic effect on the interphase chromatin of Indian muntjak fibroblasts.

Premature chromosome condensation was induced in Indian muntjak fibroblasts after exposure of the cells to bleomycin. Further experiments were devoted to the interaction of anticlastogens and a repair inhibitor, streptovitacin A. Chromosomal aberrations due to bleomycin treatment were S-phase-independently visible in the G1 and G2 phase of the cell cycle. For premature chromosome condensation experiments, a 100-fold lower concentration of the mutagen produced a similar extent of chromosome damage as in metaphase studies. Additional exposure to the anticlastogens beta-aminoethylisothiouronium or N-acetylcysteine revealed differences between corresponding interphase and metaphase effects and between different exposure conditions. Streptovitacin A, known as an inhibitor of protein synthesis, acted like an anticlastogen in the G2 phase of the cell cycle. Our studies show that the premature chromosome condensation technique offers various qualitative insights into primary processes of mutagenicity and antimutagenicity, but requires further improvement and careful choice of the cell system for study.

Acetylcysteine↗
PubMed1988

Clastogen-induced fragility may differentiate pancytopenia of congenital dyskeratosis from Fanconi anaemia.

A male infant is reported with congenital dyskeratosis and pancytopenia Zinsser-Engman-Cole. The bone marrow pathology showed similarities to Fanconi anaemia. Ophthalmological complications were vitreous haemorrhage, haemorrhagic cataracta complicata and glaucoma. Spontaneous and diepoxybutane-induced chromosomal fragility was within the range of normal cells but was elevated through induction with 4-nitroquinoline-oxide. These findings are contrasted with those of Fanconi anaemia.

Anemia, Aplastic↗
PubMed1988

Spontaneous and induced chromosomal instability in Werner syndrome.

In extension of a previous study, spontaneous and clastogen-induced chromosome damage was analyzed in cultures of peripheral blood lymphocytes from six further patients with Werner syndrome (WS) and six healthy controls. In addition, sister chromatid exchange (SCE) was estimated in four of these cases. Lymphocytes of patients with various other diseases were used for another series of control experiments. Diepoxybutane (DEB), 4-nitroquinoline-1-oxide (NQO), and bleomycin (BLM) were the standard clastogens throughout the study. While the spontaneous frequency of chromosomal breakage was significantly higher in lymphocytes from all the patients than in the control cells, the basis SCE rate was unaffected in WS cells. Sensitivity of WS cells to the chromosome-damaging action of BLM did not differ from that of control cells, and their sensitivity to DEB was slightly greater than that of control lymphocytes. However, NQO induced a more distinct increase of both break and interchange aberrations in the WS cells than in control cells or cells from patients with other diseases. This effect was not found for the SCE rate. Our data demonstrate the exceptional cytogenetic features of this syndrome: Although the spontaneous and the DEB- and NQO-induced chromosomal breakage rate would suggest that WS is like a classic chromosomal instability syndromes, the lack of sensitivity of WS cells to bleomycin and their stable SCE frequency compared with that of control cells clearly delimitate this syndrome from other entities.

4-Nitroquinoline-1-oxide↗
PubMed1987

Induction by chemical clastogens of aberrations in prematurely condensed interphase chromatin of Chinese hamster ovary cells.

The clastogenic activities of diepoxybutane and bleomycin were comparatively studied on prematurely condensed interphase chromatin and metaphase chromosomes of Chinese hamster ovary cells. The yield of chromosomal aberrations was distinctly higher in G2-premature chromosome condensation as compared to metaphase. Most notably, the clastogenic activity of bleomycin was visible in premature chromosome condensation after application of much lower final concentrations than necessary for induction of chromosome aberrations in metaphase. In addition, the different mechanisms of action of both clastogens were reflected by the aberration yield in G1 and G2 immediately after exposure. While bleomycin induced aberrations throughout all stages of interphase, diepoxybutane did not induce aberrations in G1 or G2. Though certainly not a routine system for genotoxicity testing, premature chromosome condensation analyses provide a powerful opportunity to demonstrate relationships between DNA damage and repair, and the production of chromosomal changes at the site of their formation.

Animals↗