Cytogenetic study of six cases of radiation-induced meningiomas

It is known that, following radiotherapy, secondary cancer may occur after a long latent period. Few cytogenetic studies have been reported on tumors of the central nervous system occurring after radiotherapy. We report the cytogenetic study of six cases of radiation-induced meningiomas. In all cases, we observed the same chromosome abnormality, der(1)(1qter-->1p11::22q12-->22pter). SKY and CGH techniques allowed us to identify the chromosomal abnormalities. We suggest that a gene localized on 1p13 is involved in radiation-induced meningiomas.

Fluorescence in situ hybridization determination of 22q12-q13 deletion in two intracerebral ependymomas

The sole cytogenetic abnormalities encountered in two childhood anaplastic intracerebral ependymomas were an isodicentric chromosome 22 in one case and an unbalanced chromosome 22 translocation associated with a partial deletion in the other. Fluorescence in situ hybridization analysis showed that the common 22q arm loss did not involve the rhabdoid region but included the EWS and NF2 loci. These results, in conjunction with data in the literature, suggest that the most frequently recurrent genomic loss in ependymomas does not involve the proximal 22q11.2 chromosome region but is localized distally to the hSNF5/INI1 locus. A tumor-suppressor gene, independent of the NF2 gene, which seems to be exclusively involved in intramedullary spinal cord ependymomas, might be implicated in the genesis of these intracranial tumors.

Cytogenetic study of 33 ependymomas

Ependymomas are glial tumors. They constitute approximately 5-10% of intracranial tumors. Ependymomas are tumors which can recur. Predictive factors of outcome in ependymomas are not well-established. Karyotypic studies on ependymomas are relatively scarce, and no specific chromosomal change has been described in these neoplasms. We performed a cytogenetic study of 33 ependymomas, of which eight were recurrent tumors, to determine the type and incidence of cytogenetic changes.

Contribution of cytogenetics and FISH in the diagnosis of meningiomas. A study of 189 tumors

The correlation between cytogenetic and histopathological findings were analysed in 189 meningiomas. The tumors were classified according to increasing degrees of anaplasia. We observed normal karyotype or only monosomy 22 in grade 1 (benign) tumors, while in grade 3 (anaplastic) only 1.5% of karyotypes were normal. Grade 2 (atypical) and 3 (anaplastic) tumors showed complex structural abnormalities. Loss of chromosome 14 were only found in grade 3. In cases with complex structural rearrangements, fluorescence in situ hybridization technique (FISH) has been realized and permitted a best identification of abnormalities. In our series, five patients recurred. They presented chromosomal abnormalities. These complex karyotypes in recurrent meningiomas might indicate aggressive tumor characteristics. Our results indicate histolopathological and cytogenetics correlations might represent a prognostic factor in meningiomas.

Hidden chromosome abnormalities in a primary central nervous system lymphoma detected by multicolor spectral karyotyping

Cytogenetic analysis provides important information for diagnosis and prognosis in some tumors. But karyotype analysis can be difficult in some cases, because metaphase chromosomes are contracted. New techniques, such as fluorescence in situ hybridization and, more recently, spectral karyotyping, or SKY, based on the hybridization of 24 fluorescently labeled chromosome painting probes, allow the detection and identification of complex chromosomal rearrangements. We report here a case of primary central nervous system lymphoma in which chromosomal rearrangements and marker chromosomes not identified by a routine cytogenetic technique were clarified by SKY. This shows the value of the SKY technique in the cytogenetic diagnosis of tumors.

Are juvenile pilocytic astrocytomas benign tumors? A cytogenetic study in 24 cases

We performed a cytogenetic study on 24 pilocytic astrocytomas: 23 in children and 1 in a young adult. We observed 12 normal karyotypes. In 12 karyotypes with structural and/or numerical abnormalities, chromosomes 7, 8, and 11 were most frequently involved. One case recurred and presented chromosomal abnormalities (hyperdiploidy) in the first tumor and additional structural abnormalities in the second tumor. We believe that chromosomal abnormalities in pilocytic astrocytomas are frequent and indicate tumoral progression.

Translocation 1;19 in two brain tumors

We report two-cases of brain tumors, one childhood medulloblastoma and one adult glioblastoma with an unusual chromosomal abnormality: a t(1;19)(q23;q13). We analyzed these karyotypes using fluorescence in situ hybridization (FISH) and wonder if this chromosomal aberration could represent a particular entity in these brain tumors like t(1;19) in ALL.

The contribution of cytogenetics to the histogenesis of meningeal hemangiopericytoma

Some controversy has existed regarding the nosology of meningeal hemangiopericytoma. In the WHO's classification of 1979 these tumours were included as a subgroup of meningiomas, but for some authors, they should not be classified as meningiomas. Cytogenetic studies on meningioma demonstrate monosomy or partial deletion of chromosome 22 in 60% of these tumors. There have been few cytogenetic studies about meningeal hemangiopericytoma. We present here the results of cytogenetic studies and fluorescence in situ hybridization in six cases of meningeal hemangiopericytoma. In these tumours we have never found monosomy 22, but all six cases were hyperdiploid. These cytogenetic data might provide additional evidence to differenciate the meningeal hemangiopericytoma from the meningioma.

Unusual chromosome abnormalities in primary central nervous system lymphoma

Primary central nervous system (PCNS) lymphoma is a relatively rare disease. The Epstein-Barr virus (EBV) has often been implicated in the development of lymphomas. Few cytogenetic. studies on PCNS lymphomas have been reported. We describe here an unusual case of PCNS B cell lymphoma, centroblastic polymorphic type without coexistent immune deficiency. The cytogenetic study showed unusual abnormalities: t(l;9) (q25;p21); del (6) (q14 q25), trisomy 12 and in addition one clone with trisomy 7 and loss of chromosome X. We did not observe any chromosome 14 abnormality, which is more commonly reported in PCNS lymphomas.

Detection of i(17q) chromosome by fluorescent in situ hybridization (FISH) with interphase nuclei in medulloblastoma

Medulloblastomas are the most frequent primitive neurectodermal tumors in children. An isochromosome for the long arm of 17, i(17q), is found in 30% of medulloblastomas. For some authors, this abnormality is observed in cases with a shorter survival time. In our cytogenetic studies of 30 medulloblastomas, we observed i(17q) in only three cases, a monosomy 17 in two cases, a monosomy 22 in four cases, nonspecific numerical or structural abnormalities in five cases, and normal karyotypes in 12 cases. We compared the results of karyotypic analysis after culture and FISH with a chromosome 17 alpha satellite DNA probe on interphase nuclei in five cases of medulloblastoma. In one case, i(17q) was only observed in four cells in karyotypic analysis, in three cases a normal karyotype was found, and in one case karyotypic analysis was impossible. In all of these cases, i(17q) was observed in a great number of nuclei by FISH on interphase nuclei. Our study shows that the FISH on interphase nuclei permitted us to observe i(17q) in the cases where it was not or could not be completely detected by karyotypic analysis. The association of these two techniques is required to detect i(17q), an abnormality whose prognosis value in medulloblastomas is now recognized.

Platelet-derived growth factor (PDGF) and receptor (PDGFR) expression in human meningiomas: correlations with clinicopathological features and cytogenetic analysis

PDGFs and their receptors expression were examined in a series of 46 meningiomas by using specific monoclonal antibodies. The immunostaining was quantified by an image analyser and the results correlated with clinical and morphological data (histological type and grade). In addition, since the PDGFB chain is encoded by the c-sis proto-oncogene localized on chromosome 22 and because monosomy 22 has been frequently reported in meningiomas, PDGFs and PDGFRs expression have been correlated with cytogenetic analysis performed in 29 cases. The results demonstrate PDGF A and PDGF B expression in most meningioma specimens and co-expression of these growth factors in numerous cells. PDGF A and B immunoreactivity was related to histological grade. PDGFR beta expression was strong in almost all meningiomas whereas PDGFR alpha was low. PDGFR alpha expression was related to tumour location and grade and PDGFR beta to histological subtype only. The cytogenetic analysis was not related to PDGFB chain expression. Taken together these data further confirm PDGF and PDGFR expression in human meningioma; PDGF may exist as an heterodimer (AB) as well as its receptor. The lack of correlation between cytogenetic analysis and PDGF values, the low level of PDGFB in recurrent meningiomas suggests that it is unlikely that the c-sis proto-oncogene plays an important role in the genesis of meningiomas.

Correlation between cytogenetic and histopathological findings in 75 human meningiomas

The correlations between cytogenetic and histopathological findings were analyzed in 75 human meningiomas. The tumors were classified according to increasing degrees of anaplasia into three grades: Grade I, benign; Grade II, atypical; Grade III, anaplastic. In 45 tumors of Grade I (benign), we more often observed a normal karyotype or monosomy 22. In 23 tumors of Grade II (atypical), we observed karyotypes with structural and/or numerical abnormalities with the presence of telomeric associations in 8 of them. These last tumors were fibroblastic. In seven Grade III tumors (anaplastic), we also observed complex abnormalities, and in one case, we observed telomeric associations. Our observations show that complex chromosome abnormalities and telomeric associations are observed in tumors that histologically display a certain degree of anaplasia. It is possible that the result of histopathological and cytogenetic correlations might represent a prognostic factor in meningiomas.

Cytogenetic studies in 45 pediatric brain tumors

Brain tumors are the most frequent childhood tumors. There have been few cytogenetic studies published on these tumors in children compared to the numerous studies on adult brain tumors. We examined chromosomes from 45 primary pediatric brain neoplasms including 14 medulloblastomas, 12 astrocytomas, 4 glioblastomas, 7 ependymomas, 5 craniopharyngiomas, 2 meningiomas, and 1 ganglioglioma. Chromosomal abnormalities were found in 10 medulloblastomas out of the 14 analyzed. The most frequently observed abnormalities were the total or partial loss of one chromosome 17: monosomy 17, i(17q), and a monosomy 22 in 4 cases of desmoplastic medulloblastoma. In glioblastoma, we observed the gain of chromosome 7, chromosome 3, a monosomy 10, and hyperdiploidy. The loss of chromosome X was observed in 2 cases of ependymoma as was a monosomy 22. Our observations show that from the cytogenetic point of view childhood brain tumors differ from adult brain tumors.

Chromosome 2 abnormalities (+Der 2) in two cases of childhood rhabdomyosarcoma

Chromosome analysis was performed in two cases of rhabdomyosarcoma (RMS): one embryonal RMS and one alveolar RMS. Analysis showed number and structural abnormalities of chromosome 2. The relationship between these findings and published reports of karyotypes from RMS is discussed.

Nucleolus, nucleolar chromosomes, and nucleolus-associated chromatin from early diplotene to dictyotene in the human oocyte

The shape, relationships, relative DNA content, and nucleolar activity of the short arm of acrocentric bivalents were studied in human oocytes from early diplotene to dictyotene. At the beginning of diplotene, the short arms of the previously paired chromosomes were again separated and displayed the same morphological features as in mitotic prophase chromosomes. They were connected only with the nucleolus. In situ hybridization and silver staining showed that the nucleolar organizer regions (NORs) were located in the peripheral region of the nucleolus. Tritiated-uridine incorporation was active. At birth, the relationships of the acrocentric short arms showed increasing complexity. The chromosomes ended in nucleolus-associated chromatin blocks of irregular shape, containing large quantities of DNA as demonstrated by intense binding of 3H-actinomycin D. The number of chromosomes converging on these chromatin blocks exceeded the number of acrocentrics, suggesting that heterochromatic regions of other chromosomes were associated with the short arm of acrocentrics. In the electron microscope, the NORs were represented by fibrillar centers located on the periphery of the nucleolus and consistently connected with the blocks of dense chromatin. These relationships remained unchanged in the primordial oocyte in the adult ovary. Persistence of 3H-uridine uptake showed that the oocyte was not at a "resting" stage. The possible cytogenetic consequences of these observations are discussed.

Three-dimensional analysis of fibrillar centers and associated chromatin in the nucleolus of human oocytes in primordial follicles

The intranucleolar localization of fibrillar centers and their relationships with nucleolus-associated chromatin were determined in stereopairs of human oocyte nucleoli obtained by computer reconstruction of serial sections. This study showed that there was no numerical relationship between the number of fibrillar centers and the number of chromosomal NORs. The three-dimensional reconstruction demonstrated that the majority of fibrillar centers was directly connected with the nucleolus-associated chromatin.

The relationships between ribosomal genes and fibrillar centers in thyroid cells cultivated in vitro

Despite the fact that the fibrillar centers of the nucleolus and the chromosomal nucleolar organisers (NORs) are similarly stained with the NOR-silver technique, there remain some questions about the identification of fibrillar centers as NORs. The distinct delineation of the fibrillar centers in porcine thyroid cells allowed us to determine whether there was a numerical equivalence or correlation between fibrillar centers and NORs. Hybridization in situ and silver staining performed on pig chromosomes showed that pairs 8 and 10 contained rDNA sites. Silver staining of thyroid cells in electron microscopy showed that the fibrillar centers and their surrounding layer of dense fibrils were the sites of silver deposit. Chromatin fibers were demonstrated within the fibrillar centers through the aid of the osmiumammine reaction and with the oxidized diaminobenzidine technique. It was observed that in cultured thyroid cells the fibrillar centers could be identified in the light microscope as argyrophilic spherules, and easily counted. The number of fibrillar centers was variable according to culture conditions. In cells cultured for 5 hr, the mean number of fibrillar centers was 1.7. After 5 days of culture, the number of fibrillar centers increased, reaching a mean value of 5.93. When thyroid cells were stimulated with thyrotropin, the number of fibrillar centers again increased to a mean value of 7.54. These results demonstrate that the relationship between fibrillar centers and NORs is not a simple proportionality: the number of fibrillar centers increases with increased cellular activity. These data imply that in active cells each NOR may pass through several fibrillar centers.

[The bone marrow karyotype in refractory anemia and preleukemia]

The term preleukemia may be used to refer to patients with acquired chronic cytopenias (refractory anemia with an excess of blast cells, refractory sideroblastic idiopathic anemia, or others idiopathic refractory cytopenias) who develop acute myeloid leukemia (AML) months or years later. In these syndromes, an abnormal bone marrow karyotype is found in about 50% cases, like in de novo AML. These abnormalities are similar to those observed in AML (mostly +8, -7, -5 or 5q-). The translocations t(8;21) and t(15;17) are never observed in preleukemia. Correlations exist between hematological data and cytogenetic features namely, in the 5q- syndrome. Thus in preleukemia the cytogenetic analysis is a valuable diagnostic method. At the present time, the prognostic value of the bone marrow karyotype is not clearly established but in single chromosome deletions (5q-, 20q-) the acute transformation is rare or delayed. At the opposite, evolution of the karyotype is generally regarded as a progression to high malignancy.

Effect of actinomycin D on the quail oocyte nucleolus during meiotic prophase I

Actinomycine D alters profoundly the distribution of the nucleolar constituents in the quail oocyte at prophase I of meiosis. As a consequence of nucleolar segregation, the normally existing relations between the nucleolus fibrillar centers and the microchromosomes are ruptured. The relations between the fibrillar center and the dense fibrills which surround it remain intact, suggesting that they constitute together a functional unit.

Chromosomal constitution of nucleolus-associated chromatin in man

Use of specific stains permits analysis of the frequency of nucleolus-associated heterochromatin in chromosomes 1 and 9 from human fibroblasts. In 81 per cent of interphase nuclei the heterochromatic segment of both No. 1 chromosomes is associated with the nucleolus, while in 19 per cent only one heterochromatic segment shows such an association with the other occupying a random position in the nucleoplasm. The nucleolar association of chromosome 9 heterochromatin is less constant: in 42.3 per cent of the nuclei both segments are associated with the nucleolus, in 39 per cent of the nuclei only one heterochromatic segment presents such an association, and in 18.7 per cent neither of the two heterochromatic segments is in nucleolar association. In 6 per cent of the cells, one or two chromosome 9 heterochromatic segments are in contact with the nuclear membrane. In situ hybridization using tritium-labeled 28S and 18S RNA shows that in the interphase nucleus the acrocentric short arms, carriers of ribosomal cistrons, are associated with the nucleolus. These observations demonstrate the complexity of the nucleolus-associated chromatin which, in addition to segments of chromosomes 1, 9, 13, 14, 15, 21, 22, may include the Y chromosome. They also confirm that the nucleolus constitutes one of the orientation points determining the relative localization of chromosomes in the interphase nucleus.

Cytochemical study of pseudoisocyanine stained human chromosomes

Human meiotic and mitotic chromosomes were studied with N-N' diethyl pseudoisocyanine stain. Following methylation and oxydation, the staining allowed microscopic observation of slides with both monochromatic light and fluorescence. In addition, stained preparations can be permanently conserved. Preceeded by diverse methods of chromosome denaturation or 5-BUDR incorporation, PIC lends itself to a large number of banding techniques. Cytochemical study of stained chromosomes demonstrated a certain PIC affinity for DNA although tests performed do not exclude the possibility of PIC reaction with certain proteins.

[Location of nucleolar organizers in somatic nuclei of newly-formed ovary of Japanese quail (Coturnix coturnix japonica)]

The localization of nucleolar organizers has been studied in the nuclei of the somatic cells of one-day-old quail ovaries with in situ hybridization techniques. In these cells the nucleolus apparatus has a chromocentre formed by heterochromatin and small nucleoli typified by cytochemical and ultrastructural characteristics, associated at the periphery of the chromocentre. After hybridization wtih [3H] rRNA (28 S-18 S) and histoautoradiography, levels of radioactivity are detected only on the nucleoli, and not located on the chromocentre. In the interphasic nuclei of these cells, the ribosomal cistrons are intricated with nucleolus ribonucleoproteins.

[Study of human chromosomes using fluorescence technics]

Fluorescent techniques permitted us to draw up a system of banding of human chromosomes, using quinacrine derivatives. This procedure may be used to measure the density of the chromosomes. Recently, other techniques which use various fluorochromes after denaturation, have been developed. The latter, which use acridine orange, give remarkably reliable and reproducible results. These techniques are particularly useful for the analysis of structural changes in the chromosomes. Their use is illustrated by a certain number of observations where they permitted the authors to determine the type of structural change and identify the chromosomes involved. The method of constitution and significance of the fluorescent bands is very controversial. It is not clearly known whether the fluorochromes combine with DNA or with protein bound to the latter. In spite of this uncertainty, the existence of heterogeneity in the structure of the chromatids at the metaphase provides new information for the understanding of chromosome organisation.