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J Squire

Publications and source records attributed to J Squire.

At least 55 records · Page 3Linked to original sources
PubMed1994

Malignant transformation in a ganglioglioma with anaplastic neuronal and astrocytic components. Report of a case with flow cytometric and cytogenetic analysis.

BACKGROUND: Malignant transformation of a ganglioglioma is rare and is generally restricted to the glial component. The authors described a unique case in which neuronal and glial elements exhibited anaplasia in a ganglioglioma. A subtotal resection of a large left temporal tumor extending into the diencephalon and brain stem in a 10-year-old boy revealed a ganglioglioma with no atypical features. The histologic findings were unchanged at further resections 4 and 12 months later. Radiotherapy was instituted with 5500 cGy in 30 fractions 21 months after initial resection. The patient returned 3 years later with a massive midline tumor recurrence. METHODS: The tumor was studied by conventional histologic methods, immunohistochemistry, flow cytometric methods, transmission electron microscopy, immune electron microscopy, and cytogenetic analysis. RESULTS: Although the first three resections revealed a typical ganglioglioma, the fourth resection revealed a cellular pleomorphic tumor with many multinucleated cells and mitoses. The tumor cells expressed glial fibrillary acid protein (GFAP) and synaptophysin on double labeling. By electron microscopy, intermediate filaments, microtubules and abundant rough endoplasmic reticulum, and neurosecretory granules were seen. Immune electron microscopy showed GFAP and synaptophysin within tumor cells. Flow cytometric studies revealed G0G1, 78%; S-phase, 9%; and G2M, 13%. Tumor cytogenetics on short term cultures revealed a complex abnormal karyotype with three sublines containing several structural chromosomal abnormalities. CONCLUSIONS: A unique anaplastic transformation of a ganglioglioma is reported with the anaplastic cells exhibiting neuronal and astrocytic features.

Anaplasia↗
PubMed1994

MYCN gene amplification in rhabdomyosarcoma.

BACKGROUND: Amplification of the MYCN oncogene, formerly known as N-myc, has been seen in several malignant tumors, particularly neuroblastoma, where its association with a poor clinical outcome is the clearest example of a clinically relevant oncogene mutation in any human cancer. METHODS: The incidence and clinical significance of MYCN amplification in rhabdomyosarcoma (RMS) was assessed by Southern blot analysis in this retrospective study of seven alveolar RMS and six embryonal RMS. RESULTS: MYCN amplification (4- to 13-fold) was present in three of seven alveolar RMS (42.9%) but in none of the embryonal RMS. There was no significant difference between the clinical behavior of the MYCN-amplified and unamplified tumors, and no correlation was found with the light microscopic appearances of the tumors or with desmin immunoreactivity. CONCLUSIONS: The findings are compatible with previous studies that demonstrated cytogenetic evidence of gene amplification in RMS, and help to clarify conflicting reports in the literature about MYCN amplification in alveolar and embryonal RMS. The results raise the possibility of important biologic differences between these subtypes of RMS, differences that warrant further investigation.

Blotting, Southern↗
PubMed1994

Pediatric malignant glioma with tubuloreticular inclusions and MYCN amplification. Report of a case with immunohistochemical, ultrastructural, flow cytometric, karyotypic, and Southern blot analysis.

BACKGROUND: The authors described unusual pathologic features in a left frontal lobe malignant glioma in a 31/2-year-old boy. The pathology was similar in the initial excision and two subsequent recurrences at 9 and 11 months and at autopsy, when extensive subarachnoid spread was noted. METHODS: The tumor was studied by conventional histology, immunohistochemistry, flow cytometry, transmission electron microscopy (TEM), immune electron microscopy (IEM), and cytogenetic and Southern blot analysis. RESULTS: The tumor revealed two different histologic patterns. One component showed large cells with eosinophilic cytoplasm, vesicular nuclei with prominent nucleoli, eosinophilic perinuclear inclusions, and immunoreactivity for glial fibrillary acidic protein (GFAP) and vimentin. The other component consisted of undifferentiated cells with hyperchromatic nuclei and scanty cytoplasm. By TEM, the perinuclear aggregates were composed of tubuloreticular inclusions, which were also observed in endothelial cells within the tumor vasculature. By IEM, the intermediate filaments in the tumor cell cytoplasm were decorated with GFAP. Flow cytometric results revealed a marked increase in the S-phase (48%), whereas cytogenetic analysis of short-term cultures showed an abnormal karyotype containing marker chromosomes and double minutes. In the second resection, additional karyotypic abnormalities were noted, including 1p- and several additional markers. The first and second resections showed MYCN amplification by Southern Blot analysis in the 60- to 80-fold range. CONCLUSIONS: This tumor presents unique histologic, ultrastructural, and cytogenetic findings as well as MYCN amplification that is notable for a pediatric malignant glioma. Tubuloreticular inclusions were a prominent feature in this tumor, which again is unique for a glioma.

Blotting, Southern↗
PubMed1994

Localization of Beckwith-Wiedemann and rhabdoid tumor chromosome rearrangements to a defined interval in chromosome band 11p15.5.

Chromosome rearrangements have provided useful landmarks to identify disease loci and have served as starting points for positional cloning strategies for candidate genes. We have used fluorescence in situ hybridization (FISH) and pulsed-field gel electrophoresis (PFGE) to map three Beckwith-Wiedemann syndrome (BWS) breakpoints and a rhabdoid tumor breakpoint more precisely. These breakpoints mapped to the interval between D11S679 and the insulin-like growth factor 2 (IGF2) gene on 11p15.5. A cosmid (c15-2) was identified that mapped centromeric to the BWS t(11;16) and the rhabdoid tumor-associated t(11;22), telomeric to the BWS t(11;22), and was found to span the BWS-associated inv(11) breakpoint. Pulsed-field gel analysis placed all four breakpoints into a 250-675 kb interval distal to D11S679 and at least 270 kb centromeric to the IGF2 and H19 loci. These data locate all three BWS rearrangements and the rhabdoid tumor t(11;22) breakpoint in the same region of 11p15.5, suggesting that they may be affecting the same locus or closely linked loci. Cosmid c15-2 provides a well-defined starting point in the search for candidate disease genes.

Beckwith-Wiedemann Syndrome↗
PubMed1994

Characterization of human hepatocyte lines derived from normal liver tissue.

Four separate continuous lines of human hepatocytes (HH01, HH02, HH09, HH25) were developed from normal liver tissue by subjecting cocultures of human hepatocytes with rat liver epithelial cells in a highly enriched medium to frequent subculturing. The addition of conditioned medium from either the human hepatoma line Hep G2 or one of these stable human hepatocyte lines (HH09) appeared to facilitate establishment of line HH25. These human hepatocyte lines have been in continuous culture for 2 to 5 yr and consist of approximately 95% human cells by analysis of cell surface antigens. Cytogenetic analysis also confirmed the human origin of these cells and showed clonal origin with abnormal ploidy. Cells in these human hepatocyte lines retain morphological features of hepatocytes by both light and electron microscopy. They also retain glucose-6-phosphatase activity and secrete proteins characteristic of hepatocytes, such as albumin, alpha-fetoprotein and transferrin. After incubation with 13 mumol/L dibenz(a,h) anthracene for 24 hr, each line had detectable activity of aryl hydrocarbon hydroxylase, ethoxyresorufin O-deethylase and methoxyresorufin O-demethylase. Thus, these human hepatocyte lines retain important differentiated characteristics of hepatocytes. Derived from normal liver tissue, they appear to be immortalized. They provide a new model system for studying human hepatocellular drug metabolism. These lines may also be useful for studying the regulation of synthesis of albumin, alpha-fetoprotein and other proteins in human hepatocytes, determining the effects of cytokines and growth factors and designing systems to effect gene transfer into human hepatocytes for the purpose of gene therapy.

Albumins↗
PubMed1994

NUB-7: a stable I-type human neuroblastoma cell line inducible along N- and S-type cell lineages.

Human NB cell lines express features of one or more of three recognizable phenotypes that include N-type (neuroblastic), S-type (Schwannian), and I-type (intermediate phenotype) cells. The I-type cell, which shares properties of both N- and S-type cells, is thought to represent the progenitor cell from which the other two cell types are derived. The MYCN amplified NB cell line NUB-7, established in our laboratory, is now shown to be composed principally of I-type cells. The observed phenotype was stable in culture and was representative of the original surgically resected tumor. The I-type cell designation was established based on morphological characteristics, the coexpression of various N-type (neurofilaments, peripherin, GAP-43, NCAM, MYCN) and S-type cell (vimentin, laminin, fibronectin) markers, and the relatively high level of expression of these markers in comparison to five predominantly N-type, one S-type, and one N/S mixed NB cell lines. Dibutyryl cyclic AMP and retinoic acid induced enhanced expression of N- and S-type phenotypes, respectively, in NUB-7 as supported by specific morphological changes, reduced growth, and changes in the levels of expression of both N- and S-type markers. Our studies with the NUB-7 cell line have now provided convincing evidence for the existence of a bipotential progenitor of N- and S-type cells in NB. As well, the NUB-7 cell line may also represent the tumor counterpart of a sympathetic ganglion progenitor cell.

Bucladesine↗
PubMed1994

Lymphoid blast crisis of B-lineage phenotype with monosomy 7 in a patient with juvenile chronic myelogenous leukemia (JCML).

We studied a patient with juvenile chronic myelogenous leukemia (JCML) whose terminal course was characterized by transformation to acute lymphoblastic leukemia. Karyotypic studies identified monosomy 7 in leukemic myelomonocytic marrow cells during the chronic phase and in the lymphoblasts during the transformation phase. Our ability to sustain the transformed lymphoblasts in culture allowed us to characterize them further. CD19, HLA-DR, and CD10 were present, consistent with a pre-B acute lymphoblastic leukemia phenotype. CD14 (My-4) and CD13 (My-7) were negative. Rearrangement of immunoglobulin heavy- and light-chain genes identified monoclonal populations of cells of the B lineage. This case provides further evidence that JCML is a clonal disease of pluripotent stem-cell origin.

Blast Crisis↗
PubMed1994

A hematopoietic protein tyrosine phosphatase (HePTP) gene that is amplified and overexpressed in myeloid malignancies maps to chromosome 1q32.1.

Tyrosine phosphorylation is an important regulator of cell growth and differentiation reflecting the interaction of protein tyrosine kinases (PTK) and protein tyrosine phosphatases (PTP). Although excessive PTK activity can result in hematopoietic cell transformation, perturbation of either of these two modulators may result in uncontrolled cell growth. Myeloid cells are responsive to growth factors and cytokines that induce tyrosine phosphorylation and can become ligand independent when endogenous PTKs become dysregulated. Specific PTPs, through mutation or altered expression, may enhance PTK activities and also cause myeloid ligand independence, though this has not yet been demonstrated. We have previously reported the isolation of a hematopoietic specific cytoplasmic PTP (HePTP). We now report that this gene maps to chromosome 1q32.1 utilizing fluorescent in situ chromosomal hybridization (FISH). This site is frequently amplified in preleukemic myeloproliferative diseases. FISH analysis of a patient with myelodysplastic syndrome characterized by myeloid hypoplasia and monocytosis reveals triplication of the HePTP gene on one allele with elevated protein expression in neoplastic myelomonocytic cells. Elevated expression is also identified in blasts from some patients with acute leukemia. These observations prompted us to examine the experimental effects on cell growth of HePTP overexpression. Though normal myeloid cells show minimal HePTP expression, all hematopoietic cell lines tested show high expression of HePTP. Gene transfer of HePTP into NIH 3T3 cells was therefore performed, which caused altered cell morphology, disorganized growth, anchorage independent colony formation and subtle differences in the pattern of tyrosine phosphoproteins compared to control cell lines. We conclude that amplification and overexpression of HePTP may be an important cofactor contributing to abnormal myeloid cell growth.

Adult↗
PubMed1993

Amplification of a DEAD box protein gene in retinoblastoma cell lines.

DEAD box proteins, characterized by the conserved motif Asp-Glu-Ala-Asp, are putative RNA helicases implicated in a number of cellular processes involving alteration of RNA secondary structure such as translation initiation, nuclear and mitochondrial splicing, and ribosome and spliceosome assembly. Based on their distribution patterns, some members of this family are believed to be involved in embryogenesis, spermatogenesis, and cellular growth and division. Here, we report that the mRNA encoding a DEAD box protein, designated HuDBP-RB, is present at elevated levels in two of six retinoblastoma (RB) cell lines tested and is preferentially expressed in fetal tissues of neuroectodermal origin. It is not possible to classify HuDBP-RB as a member of any of the DEAD box protein subgroups identified to date since the regions of amino acid similarity between HuDBP-RB and other DEAD box proteins are restricted to the conserved motifs found in all members of this family. The HuDBP-RB gene, which has been mapped to chromosome band 2p24, is amplified in the RB cell lines that overexpress HuDBP-RB RNA. Furthermore, the MYCN gene is also present in multiple copies in these two cell lines, suggesting coamplification of the two genes.

Amino Acid Sequence↗
PubMed1993

Variant translocations of chromosome 22 in Ewing's sarcoma.

Relatively few variant translocations have been reported in primary Ewing's sarcomas (ES). We report two new variant translocations, both of which involve chromosomal rearrangements of 22q12. Cytogenetic studies of tumor cells from a 12-year-old girl revealed a variant translocation, t(7;22)(p22;q12), the second example reported of a simple variant of the 22q12 reciprocal translocation in this type of sarcoma. The identity of this rearrangement was confirmed by in situ hybridization. In addition, a complex translocation was identified in a dysmorphic 15-year-old girl, t(4;11;22)(q21;q24;q12). No previous cases of variant translocations in ES have involved band 7p22 or 4q21, and there are no previous reports of an association between congenital abnormalities and unusual karyotype abnormalities in ES. Both variant translocations conserve the junction on the der (22), providing additional cytogenetic evidence that the sequences on chromosome 22 are critical.

Child↗
PubMed1993

Localization of the human interferon-induced, ds-RNA activated p68 kinase gene (PRKR) to chromosome 2p21-p22.

The interferon-induced dsRNA-activated protein kinase (PRKR) belongs to a subclass of serine/threonine kinases, involved in the regulation of protein synthesis by phosphorylation of the alpha subunit of initiation factor eIF2. Somatic cell hybrids segregating human chromosomes were used to assign this kinase to human chromosome 2. Fluorescence in situ hybridization confirmed this assignment and further localized the gene (PRKR) to the boundary region of bands p21 and 22.

Chromosome Banding↗
PubMed1993

Time-resolved studies of crossbridge movement: why use X-rays? Why use fish muscle?

The advantages of using time-resolved X-ray diffraction as a means of probing myosin cross-bridge behaviour in active muscle are outlined, together with the reasons that bony fish muscle has advantages in such studies. We show that the observed X-ray diffraction patterns from fish muscle can be analysed in a way that is rigorous enough to allow reliable information about crossbridge activity to be defined. Among the advantages of this muscle are that diffraction patterns from resting, active and rigor muscles are all well-sampled at least out to the 30 row-line, that the resting myosin layer-line pattern can be 'solved' crystallographically to define the starting position of the crossbridges in resting muscle, and that the equatorial intensity distribution, which in all patterns from vertebrate skeletal muscles comprises overlapping peaks from the A-band and the Z-band, can be analysed sufficiently rigorously to allow separation of the two patterns, both of which change when the muscle is active. Finally, we present results both on a new set of myosin-based layer-lines in patterns from active muscle (consistent with the presence of low-force bridges as also indicated by the time-courses of the intensity changes on the equator and the changing mass distribution in the A-band unit cell) and also on changes of the actin-based layer-lines (consistent with stereospecific labelling of the actin filaments by force-producing crossbridges). Our results to date, which demonstrate the enormous power of time-resolved X-ray diffraction studies, strongly support the swinging of myosin heads on actin as part of the contractile cycle.

Animals↗
PubMed1993

Disruption of insulin-like growth factor 2 imprinting in Beckwith-Wiedemann syndrome.

To study insulin-like growth factor 2 (IGF2) imprinting in BWS (Beckwith-Wiedemann syndrome, an overgrowth syndrome associated with Wilms and other embryonal tumours), we examined allele-specific expression using an Apal polymorphism in the 3' untranslated region of IGF2. Four of six BWS fibroblast strains demonstrated biallelic expression, as did the tongue tissue from one of these patients. Paternal heterodisomy was excluded for all BWS patients with biallelic expression, suggesting strongly that the BWS phenotype in some patients involves disruption of IGF2 imprinting. Constitutional loss of IGF2 imprinting in a subgroup of our BWS patients, and recent reports of loss of imprinting in sporadic Wilms tumour, further strengthens the view that IGF2 overexpression plays an important role in somatic overgrowth and the development of embryonal tumours.

Adolescent↗
PubMed1993

Characterization of abnormal one pronuclear human oocytes by morphology, cytogenetics and in-situ hybridization.

The morphology, chromosomal constitution and developmental capability of abnormal human oocytes (94/3500 oocytes; 2.7%) which after insemination exhibited only one pronucleus were examined. The majority of one pronuclear oocytes exhibited two or more distinct polar bodies. Dividing oocytes showed irregular chromosome distribution from haploid to diploid. Embryos resulting from abnormal oocytes displayed limited developmental potential. Many of them underwent fragmentation or were arrested at the 2- or 8-cell stage of development, and only some reached the morula or blastocyst state (11/35 oocytes). In approximately 45% (15/33) of examined oocytes, decondensed sperm heads or tiny nucleus-like structures were found in addition to a single nucleus. Chromosome Y was also detected in chromosomal preparations in approximately 10% of the oocytes by in-situ hybridization utilizing the human Y chromosome-specific DNA probe (DYZ3). These observations provided strong evidence that many of these oocytes originated from fertilized oocytes. The origin of the other one pronuclear oocytes could not be determined. Parthenogenetic activation of some oocytes cannot be excluded and other explanations concerning the origin of abnormal oocytes are discussed.

Adult↗
PubMed1993

Detection of MYCN gene amplification and deletions of chromosome 1p in neuroblastoma by in situ hybridization using routine histologic sections.

BACKGROUND: Amplification of the MYCN oncogene and partial deletion of chromosome 1p are genetic changes frequently seen in neuroblastoma that are indicators of poor prognosis. The identification techniques usually used--Southern blotting for MYCN gene amplification, and karyotypic analysis of viable tumor cells for large 1p deletions--are time-consuming and suited for specialized laboratories. EXPERIMENTAL DESIGN: We have developed an immunofluorescence in situ hybridization assay suitable for detection of MYCN amplification and 1p deletion in formalin-fixed, paraffin-embedded tissue sections. The technique is rapid, does not involve the use of radioactivity, and can be carried out in laboratories already familiar with conventional in situ hybridization and immunohistochemical detection methods. RESULTS: MYCN gene amplification appeared as multiple signals per nucleus, corresponding to double minute chromosomes. Deletion of 1p was detected by loss of one of the normal signals present within the nucleus of a neuroblastoma cell line. Use of different fluorophores enabled the simultaneous detection of MYCN gene amplification and 1p deletion at the individual cell level. Detection was found to be enhanced by RNase and pepsin treatment of tissue sections before hybridization and by a novel microwave denaturation method. CONCLUSIONS: Application of this methodology to formalin-fixed samples of neuroblastoma will permit comprehensive retrospective studies of these two genetic markers using archived tumors. In situ hybridization surveys will have widespread applications for studying known genetic aberrations in individual cells of a variety of solid tumors and for determining interrelationships and clinical significance in relation to tumor progression and patient outcome.

Chromosomes, Human, Pair 1↗
PubMed1992

Molecular genetic, cytogenetic, and immunohistochemical characterization of alveolar soft-part sarcoma. Implications for cell of origin.

BACKGROUND: Alveolar soft-part sarcoma is a rare tumor of uncertain histogenesis. METHODS: The authors report a patient who was studied using immunohistochemistry, cytogenetic analysis, and molecular probes for MyoD1 and MYCN (N-myc proto-oncogene). RESULTS: By immunoperoxidase, the tumor was focally positive for vimentin, neuron-specific enolase, and S-100 protein but negative for muscle-specific actin, desmin, and low-molecular-weight keratin. Direct chromosome analysis of primary tumor cells using G-banded preparations yielded two clonally abnormal lines: one demonstrated trisomy 47,XX+5; the other demonstrated 46,XX,1p-,17q+. Expression of the MYCN RNA was detectable at a low level, and MYCN was single copy at the DNA level. Expression of the myogenic molecular marker MyoD1 was not detected by Northern blotting analysis. CONCLUSIONS: This is the first detailed study to address the molecular biology and tumor cytogenetics of alveolar soft-part sarcoma. The results of this study indicate a neurogenic origin for this unusual tumor and fail to provide support for the notion of a myogenic origin.

Adolescent↗
PubMed1992

High-resolution mapping of mammalian genes by in situ hybridization to free chromatin.

Fluorescence in situ hybridization to metaphase chromosomes or chromatin fibers in interphase nuclei is a powerful technique in mapping genes and DNA segments to specific chromosome region. We have been able to release the chromatin fibers from cells arrested at G1 and G2 phases using different drugs and a simple alkaline lysis procedure. We have also demonstrated specific hybridization of fluorescence-labeled probes to single-copy genomic DNA sequences on the free chromatins. Fluorescence in situ hybridization signals have been detected for sequences separated as close as 21 kilobase pairs and as far as 350 kilobase pairs, with excellent correspondence between the observed and expected distances. The resolution of this technique should approach 10 kilobase pairs and its coverage should span millions of base pairs. Therefore, free chromatin mapping can be generally used to study the structure and organization of mammalian genomes.

Amsacrine↗