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P Thorner

Publications and source records attributed to P Thorner.

At least 37 records · Page 2Linked to original sources
PubMed1997

Relational mapping of MYCN and DDXI in band 2p24 and analysis of amplicon arrays in double minute chromosomes and homogeneously staining regions by use of free chromatin FISH.

MYCN amplification has been observed in diverse neuronal tumors including neuroblastoma, retinoblastoma, and small cell carcinoma of the lung, and has been correlated with a poor prognosis in advanced-stage neuroblastomas. Recent studies have shown a co-amplification of DDXI, a DEAD box gene, and MYCN in retinoblastoma and neuroblastoma. DDXI has been mapped to within a megabase of the MYCN gene in band 2p24. In the present study, the relational map of DDXI and MYCN by fluorescence in situ hybridization (FISH) mapping to metaphase cells and extended free chromatin fibers indicated that DDXI is telomeric to MYCN. Dual-color FISH analysis of amplicons within arrays of extended chromatin fibers was performed to examine the physical relationship of MYCN and DDXI within double minute chromosomes (dmins) and homogeneously staining regions (hsrs). No regular reiterated amplicon repeat unit was present in the hsrs, but detailed analysis of the configurations of DDXI and MYCN within each array indicated that multiple rearrangements generated a complex hsr amplicon structure. Similarly, analysis of a cell line bearing dmins showed that a composite amplicon structure involving deletions and/or duplications of MYCN and DDXI is a feature of dmin formation. These data are consistent with a molecular mechanism involving many rearrangements during the evolution of gene amplification, resulting in complex amplicon structures with distinct changes in relative gene copy number and considerable variation in intragenic distances between coamplified genes.

Blotting, Southern↗
PubMed1997

Novel COL4A5/COL4A6 deletions and further characterization of the diffuse leiomyomatosis-Alport syndrome (DL-AS) locus define the DL critical region.

Diffuse leiomyomatosis (DL) with Alport syndrome (AS) has been shown to be associated with contiguous gene deletions of the COL4A5 and COL4A6 genes, with the COL4A6 breakpoint of the deletions invariably located in the large intron 2 of the gene. We describe four YAC clones covering the locus and a refined restriction map of the entire COL4A6 gene. These resources have allowed us to make a precise estimate of the size of COL4A6 introns 2 and 3, as well as the size of the gene itself. We also describe five novel deletions which, in conjunction with previous reports, allow the definition of a 90-kb critical region in which to search for a gene or other entity involved in the pathogenesis of DL.

Adult↗
PubMed1997

Diffuse leiomyomatosis associated with X-linked Alport syndrome: extracellular matrix study using immunohistochemistry and in situ hybridization.

Inherited diffuse esophageal leiomyomatosis a benign tumor involving smooth muscle cells of the whole esophagus, is frequently associated with X-linked Alport syndrome, a hereditary disease of type IV collagen. Families with this condition are consistently found to have deletions encompassing the 5' ends of both the alpha 5 chain of type IV collagen (COL4A5) and the alpha 6 chain of type IV collagen (COL4A6) genes, always limited in COL4A6 to exons 1', 1, and 2. On the contrary, patients with COL4A5/COL4A6 deletions extending further into COL4A6 display no such tumors. Despite the deletion, a COL4A6 transcript including exon 4, but not exon 3, was found in a tumor sample, raising the possibility of the involvement of a truncated alpha 6(IV) chain in the tumorous process. Using immunohistochemistry and in situ hybridization methods, we analyzed the expression and distribution of the alpha 6 chain of type IV collagen in tumors in comparison with that of normal, fetal, and mature esophagus. We also studied associated changes in tumor basement membrane composition and in tumor-cell integrin subunit distribution. No labeling with alpha 6(IV) antibodies was detected in tumors, ruling out the hypothesis of a stably integrated truncated alpha 6(IV) chain in tumor basement membranes. In contrast, despite the deletions of the first two exons of the gene and its 5' end, a COL4A6 transcript is clearly expressed by tumor cells. This finding raises the question of a potential role for this RNA in the tumor process. The absence of the alpha 6(IV) chain is associated with the absence of the alpha 5(IV) chain, as was suggested by the COL4A5 deletion. An additional striking feature is the absence of the beta 1 chain of laminin in tumor basement membranes and the lack of or uneven expression of the alpha 5 integrin subunit. These findings show that dramatic changes in the composition of the matrix and the expression of integrin receptors also occur in this benign tumorous process.

Basement Membrane↗
PubMed1997

Congenital teratomas of the head and neck.

OBJECTIVE: This article reviews teratomas, neoplasms composed of the three germinal layers of the embryo that form tissues foreign to the part in which they arise. These are most common in the sacrococcygeal region and are rare in the head and neck. In this region, major concerns are airway obstruction and cosmesis. METHOD: Pathology records at two tertiary care paediatric hospitals were reviewed for diagnoses of head and neck teratomas. This revealed nine cases between 1983 and 1993, five males and four females. Two males were stillborn. Five were cervical, two were in the nasopharynx, and two were facial. The lesions were immature in two cases and mature in the remainder. All of the liveborn children underwent surgery within the first year of life, and only one required tracheotomy. RESULTS: One child had recurrence of teratomatous tissue diagnosed with CT, which was treated surgically. The child has remained free of tumour for over 3 years. Pathogenesis, clinical appearance, diagnostic work-up, and currently accepted modes of therapy are reviewed.

Female↗
PubMed1996

Heterotopic brain in the parapharyngeal space.

There have been numerous reports of various types of heterotopic tissue in the head and neck. Heterotopic cartilage, gastric tissue, thyroid, and salivary gland in such various locations as tongue, gingiva, palate, nasopharynx, parapharyngeal space, and neck have been frequently reported. Heterotopic brain in the parapharyngeal space causing airway obstruction in the neonate has been rarely described. These benign masses are capable of expansion and because of their location, can lead to significant airway and feeding difficulties. We describe 3 cases of heterotopic brain tissue in the parapharyngeal space causing feeding difficulties and airway obstruction in the neonatal period. Two were initially misdiagnosed as lymphatic malformations. In the third, a nine month delay in diagnosis occurred. The diagnostic features of heterotopic brain in this location and some management suggestions in treating such a lesion are discussed.

Airway Obstruction↗
PubMed1996

Unusual laryngeal cysts in the newborn.

In the newborn, severe airway obstruction is a rare occurrence. The possible etiologies include a broad spectrum of diseases with laryngeal cysts an unusual cause. If diagnosed and properly managed, however, the prognosis for this entity is excellent. Three cases presenting with airway obstruction secondary to unusual laryngeal cysts are the material for this report. In all three, cases the laryngeal cystic structure extended through the cricothyroid membrane and in two, pathologically contained both mesodermal and endodermal elements suggesting a laryngotracheal duplication cyst anomaly, previously unreported. Laryngofissure can be safely employed for complete excision even in the neonatal period.

Airway Obstruction↗
PubMed1996

Selection of probes for fluorescence in situ hybridization analysis by differential display polymerase chain reaction of mRNA from rhabdomyosarcoma.

Rhabdomyosarcoma (RMS) is a malignancy of skeletal muscle derivation encompassing two major subtypes, embryonal and alveolar, which differ in clinical behavior and genetic markers. Because RMS is a relatively circumscribed tumor system for which the beginnings of a molecular genetic framework are in place, it becomes an ideal model for the application of improved methods of molecular genetic analysis. We have applied the technique known as differential display polymerase chain reaction (DD-PCR) to characterize expression of RNA in rhabdomyosarcoma subtypes. Our studies have shown that DD-PCR generates a characteristic electrophoretic profile that can be used to isolate subtype specific probes for fluorescence in situ hybridization (FISH) analysis. We have isolated two cDNA fragments and obtained clones suitable for FISH mapping to metaphase chromosomes. One probe was mapped to the centromeric region of human chromosome 22 and the other probe to the human chromosome band 6q25-26. This approach demonstrates the utility of DD-PCR as a technique for isolating novel cDNA expressed in tumors and their subsequent use as probes for FISH analysis. As more genes are identified by DD-PCR and their roles in tumorigenesis become defined, they are likely to provide novel targets for future molecular cytogenetic analysis.

Base Sequence↗
PubMed1996

Identification of MYCN Copy Number Heterogeneity by Direct FISH Analysis of Neuroblastoma Preparations.

Background: Amplification of MYCN and deletion of 1p in neuroblastoma are associated wtih a poor prognosis. MYCN copy numbers of 10 or greater are considered to be indicative of poor outcome. However, most molecular genetic methods for estimating the number of MYCN genes do not directly address copy number heterogeneity at the cellular level. Methods and Results: MYCN copy number was assessed by fluorescence in situ hybridization (FISH), differential polymerase chain reaction (PCR), and Southern blot analysis, using 29 patient tumors. Copy number estimates by PCR or Southern blot analyses identified MYCN amplification in 11 tumors. There was complete concordance between FISH MYCN results in all 11 tumors with amplification. FISH identified 5 tumors with marked heterogeneity for MYCN copy number. Two tumors in which a small percentage of cells within the specimen were amplified would have gone undetected by molecular genetic methods alone. Conclusions: FISH offers the advantage over the other methods of detecting heterogeneity, thereby revealing tumors with small numbers of amplified cells that would otherwise be missed and, in cases of low (3-10) copies of MYCN, distinguishing small numbers of amplified cells (poor prognosis) from triploid tumors (good prognosis). FISH also allows detection of 1p deletion using the same preparations, which represents another advantage. A combination of FISH and conventional molecular methods provides an accurate definition of sample heterogeneity, and should be routinely applied to all neuroblastomas with low levels of MYCN copy number.

Journal Article↗
PubMed1996

Abnormal extracellular matrix in Ehlers-Danlos syndrome type IV due to the substitution of glycine 934 by glutamic acid in the triple helical domain of type III collagen.

A unique substitution of glycine 934 by glutamic acid in the triple helical domain of type III collagen was identified in a proband with Ehlers-Danlos syndrome type IV. The substitution was due to the transition of G 3302 to A in alpha 1(III) cDNA which is encoded by exon 46 of COL3A1. It resulted in a severe deficiency of type III collagen in fibroblast cultures and dermis. Dilatation of the endoplasmic reticulum of the dermal fibroblasts was probably due to the failure of these cells to secrete type III collagen molecules containing one or more mutant alpha 1(III) chains. The dermal collagen fibrils were narrow, but their constituent type III collagen molecules contained predominantly normal alpha 1(III) chains. As a results, the major effect of the substitution of glycine 934 by glutamic acid was to severely reduce the amount of normal type III collagen available for the formation of heterotypic collagen fibrils in the extracellular matrix.

Aged↗
PubMed1996

Immunohistochemical detection of p53 in Wilms' tumors correlates with unfavorable outcome.

The role of p53 in the pathogenesis and progression of Wilms' tumors is only partly understood. Although p53 mutations were initially reported only in anaplastic Wilms' tumors, we had reported that, of two of twenty-one cases that had a p53 mutation, one tumor showed no evidence of anaplasia. To determine the significance of p53 expression in all clinical stages of Wilms' tumor, twenty-eight cases were analyzed for p53 immunoreactivity. Paraffin sections were immunolabeled with two different monoclonal antibodies, recognizing both mutant and wild-type p53. Fifteen of sixteen tumors in the recurrent/metastatic group and three of twelve tumors in the nonmetastatic/nonrecurrent group showed p53 immunopositivity. Only one of three positive tumors in the latter group showed moderate to strong positivity, whereas twelve of sixteen metastatic/recurrent tumors revealed a similar degree of p53 positivity. The positivity was stronger in the metastasis/recurrences as compared with the corresponding primary tumor. Western blot analysis revealed p53 expression in all of the Wilms' tumors tested, suggesting its involvement in the development of Wilms' tumors. Single-strand conformation polymorphism analysis performed on twenty-three of these tumors revealed p53 mutations in four of fourteen recurrent/metastatic tumors and none in the nonmetastatic/nonrecurrent group. Our results show that, whereas 60% of cases were immunopositive for p53 protein, mutations were detected in only 16% of tumors, indicating that wild-type p53 protein is retained in the other tumors. We conclude that p53 immunopositivity strongly correlates with recurrence/metastasis in Wilms' tumors. Furthermore, the accumulation of p53 in these tumors is not only due to mutations but may also involve stabilization of normal p53 with other proteins.

Blotting, Western↗
PubMed1996

Is the EWS/FLI-1 fusion transcript specific for Ewing sarcoma and peripheral primitive neuroectodermal tumor? A report of four cases showing this transcript in a wider range of tumor types.

The presence of t(11;22)(q24;q12) is often considered diagnostic of Ewing sarcoma and peripheral primitive neuroectodermal tumor. We report four cases, all of which possessed this translocation as detected by reverse transcriptase polymerase chain reaction and confirmed by sequencing with or without fluorescent in situ hybridization, but none of which were Ewing sarcoma or peripheral primitive neuroectodermal tumor by histological criteria. Two were polyphenotypic tumors and two were mixed embryonal and alveolar rhabdomyosarcomas. Only one case was positive for MIC2 by immunohistochemistry and only in a rare cell. Two cases (one polyphenotypic tumor and one rhabdomyosarcoma) had double minute chromosomes with > 100 copies of the MDM2 gene. The presence of the t(11;22)(q24;ql2) translocation should probably not be considered diagnostic of Ewing sarcoma and peripheral primitive neuroectodermal tumor in the absence of supporting histological evidence. The presence of this translocation in Ewing sarcoma and peripheral primitive neuroectodermal tumor has been taken as evidence that these two tumors are related. Extending this relationship to include some polyphenotypic tumors and some rhabdomyosarcomas may not be justified unless additional evidence is gathered. Pathologists and oncologists will need to decide whether treatment regimens for tumors are better based on phenotype rather than genotype when these two profiles are seemingly in conflict.

Abdominal Neoplasms↗
PubMed1995

Molecular detection of the (2;5) translocation of non-Hodgkin's lymphoma by reverse transcriptase-polymerase chain reaction.

The t(2;5)(p23;q35) translocation was initially identified in cases of anaplastic large-cell lymphoma (ALCL) that expressed the Ki-1 (CD30) antigen. We have recently cloned this translocation and shown it to encode a chimeric product consisting of the N-terminal portion of a nonribosomal nucleolar phosphoprotein, nucleophosmin (NPM), from chromosome 5, fused to the kinase domain of a novel transmembrane tyrosine-specific protein kinase, anaplastic lymphoma kinase (ALK), from chromosome 2. To better define the spectrum of lymphomas that contain this translocation, we have analyzed 70 cases of non-Hodgkin's lymphoma (NHL) for expression of the t(2;5)-derived NPM/ALK chimeric message by reverse transcriptase-polymerase chain reaction (RT-PCR). Using a previously described set of oligonucleotide primers, NPM/ALK chimeric transcripts were detected in 21 of 22 cases that contained the t(2;5) by cytogenetic analysis and in 10 of 48 cases that either lacked evidence of the t(2;5) or had unsuccessful cytogenetics. In all but 1 case, the NPM/ALK PCR products were of identical size and sequence, suggesting that the genomic chromosome breaks are clustered in a single intron in both NPM and ALK. The NPM/ALK-expressing cases were not confined to NHLs with anaplastic morphology and included 15 ALCLs, 6 immunoblastic lymphomas, and 10 diffuse large-cell lymphomas. Moreover, only slightly greater than half of the cases with anaplastic morphology and 59% of CD30-expressing cases were NPM/ALK positive. Thus, neither anaplastic morphology nor the expression of CD30 accurately predicted the presence of this molecular genetic subtype of lymphoma.

Adult↗
PubMed1995

Perforation during attempted intussusception reduction in children--a comparison of perforation with barium and air.

This paper compares the effects on patients of perforation with barium and with air during attempted intussusception reduction by reviewing the clinical, radiological, surgical and pathological findings and sequelae in seven children who received barium and seven who received air. In both groups perforation occurred in infants under 6 months of age (with one exception) with a long duration of symptoms. All patients with barium enema required resection of bowel whereas only four with air enema required resection. Anesthetic times were longer in those patients with barium perforation in whom the intussusception did not move and there was a large leak. The patients with perforation due to air had a shorter hospital stay with decreased morbidity compared to those with perforation due to barium. Perforation occurred through areas of transmural necrosis in a minority of patients in each group. Perforations through normal bowel and shear injury (with air enema) indicate that increased pressure during the examination is an important factor in some patients. Because perforation with air is so much easier to deal with surgically and the children do better clinically, there is a tendency for some to consider perforation with air an inconsequential situation. However, a potential rare complication with this technique is tension pneumoperitoneum. Keeping this in mind, we continue to use air as the contrast of choice because the procedure in our hands is a safe, quicker and easier technique and we have achieved a substantial improvement in reduction rates. Overall reported perforation rates with air enema compare favourably with those due to barium enema.(ABSTRACT TRUNCATED AT 250 WORDS)

Air↗
PubMed1995

Transient leukemia followed by megakaryoblastic leukemia in a child with mosaic Down syndrome.

A case is presented of a child with mosaic Down syndrome, who presented at birth with a transient leukemia and later progressed to megakaryoblastic leukemia. Evidence is presented that both leukemias were of megakaryoblastic lineage and evolved from a trisomic hematopoietic precursor. This case is unique in the poor course of the initial transient neonatal leukemia with improvement following chemotherapy. It also highlights the form of leukemia and associated myelodysplasia that occurs in children with Down syndrome. This form of leukemia and transient leukemia are interrelated and are unique to children with Down syndrome.

Adult↗
PubMed1994

The pro-peptide of the pro beta-polypeptide chain of human beta-hexosaminidase is necessary for proper protein folding and exit from the endoplasmic reticulum.

We examine the function of the pro beta-peptide (residues 42-121) in the folding and intracellular transport of human beta-hexosaminidase B (beta-N-acetylhexosaminidase, EC 3.2.1.52). A construct was prepared that encoded an in frame deletion of residues 55-118. Expression of this construct in COS-1 cells produced a beta-polypeptide chain that formed insoluble aggregates and remained trapped in the endoplasmic reticulum (ER). We conclude that the pro beta-peptide may act as a type of intramolecular chaperone for the mature beta-subunit.

Amino Acid Sequence↗
PubMed1994

Pediatric malignant pheochromocytoma.

Pediatric malignant pheochromocytomas are very rare tumors, and no institution has more than one or two of these problem cases. The authors report on two children with such tumors, over a 9-year period, from two hospitals. In 1984, D.B. (14 years of age) presented with symptoms and signs of extradural metastasis from a right adrenal primary; he also had lung and bone metastases. After spinal decompression almost 4 years. He has remained well and is in remission 6 years later. In 1987, G.R. (13 years of age) presented with a larger right adrenal malignant pheochromocytoma invading surrounding structures; he also had liver metastasis. Preoperative chemotherapy did not shrink the tumor much; it was grossly resected, and there were many postoperative problems. In 1990, bone metastases developed, for which radiotherapy and chemotherapy were used. Three years later, the metastases have not disappeared; he remains on chemotherapy, and his liver function is borderline. From our small experience as well as a literature review, it appears that surgical excision remains the treatment of choice for the pediatric malignant phoechromocytoma. Unresectable tumors may be rendered resectable by intensive chemotherapy (similar to that used for neuroblastoma); adjuvant chemotherapy should be used for residual disease after surgery and for metastatic disease.

Adolescent↗
PubMed1994

Myelodysplasia and acute megakaryoblastic leukemia in Down's syndrome.

In this report we describe the clinical and hematologic features of 23 cases of myelodysplasia (MDS) or acute megakaryoblastic leukemia (AMKL) occurring in Down's syndrome. MDS was characterized by thrombocytopenia, abnormal megakaryocytopoiesis, megakaryoblasts (< 30%) in the marrow and abnormal karyotype, the most common of which was trisomy 8, found in 7/15 patients with MDS. Three of five patients achieved a complete remission with low dose cytosine arabinoside, vincristine and retinyl palmitate. The high cure rate and the distinctive features of the leukemic process in these cases suggest that this type of MDS and AMKL are unique to patients with Down's syndrome.

Adolescent↗