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Biomedical subjects

W H Raskind

Publications and source records attributed to W H Raskind.

At least 37 records · Page 2Linked to original sources
PubMed1995

Inactivation of p53 and the development of tetraploidy in the elastase-SV40 T antigen transgenic mouse pancreas.

Human pancreatic cancer develops in association with an acquired genomic instability, but the events that lead to instability are difficult to investigate because they occur sporadically and unpredictably. The elastase-SV40 T antigen transgenic mouse model of pancreatic adenocarcinoma reproducibly proceeds through a diploid --> tetraploid --> multiple aneuploid sequence of genetic abnormalities. We investigated the relationship between inactivation of p53 and development of tetraploidy in this model. Because T antigen inactivates p53 by forming a stable complex with it, we used multiparameter flow cytometry to assess p53 expression in pancreatic samples of transgenic and control mice between 8 and 24 days of age. On day 18, a cell cycle-specific inactivation of p53 developed between diploid G, and S phase and was associated with the appearance of a cycling tetraploid cell population that had p53 protein overexpression in both G1- and S-phase cells. Cytogenetic analysis of pancreatic samples confirmed the development of a tetraploid cell population. Inactivation of p53 in diploid cells of the transgenic pancreas is followed by the development of a tetraploid cell population. We have shown previously that this tetraploid intermediate is predisposed to progression to aneuploidy because it has abnormal mitotic poles. Therefore, our results suggest that inactivation of p53 by T antigen leads to formation of a tetraploid cell intermediate that is predisposed to chromosome segregation abnormalities and the development of multiple aneuploid cell populations.

Animals↗
PubMed1995

Cellular biology of acute myelogenous leukemia.

The acute myelogenous leukemias (AMLs) are a heterogeneous group of disorders with diverse morphologic, histochemical, and antigenic characteristics. In this article, we discuss the heterogeneous nature of AML with regard to its cellular level of origin, cell surface antigen expression, and hematopoietic growth factor responsiveness.

Antigens, Neoplasm↗
PubMed1995

Refinement of the multiple exostoses locus (EXT2) to a 3-cM interval on chromosome 11.

Hereditary multiple exostoses (EXT) is an autosomal dominant skeletal disorder characterized by the formation of multiple exostoses on the long bones. EXT is genetically heterogeneous, with at least three loci involved: one (EXT1) in the Langer-Giedion region on 8q23-q24, a second (EXT2) in the pericentromeric region of chromosome 11, and a third (EXT3) on chromosome 19p. In this study, linkage analysis in seven extended EXT families, all linked to the EXT2 locus, refined the localization of the EXT2 gene to a 3-cM region flanked by D11S1355 and D11S1361/D11S554. This implies that the EXT2 gene is located at the short arm of chromosome 11, in band 11p11-p12. The refined localization of EXT2 excludes a number of putative candidate genes located in the pericentromeric region of chromosome 11 and facilitates the process of isolating the EXT2 gene.

Chromosomes, Human, Pair 11↗
PubMed1995

Loss of heterozygosity in chondrosarcomas for markers linked to hereditary multiple exostoses loci on chromosomes 8 and 11.

Hereditary multiple exostoses (EXT; MIM 133700) is an autosomal dominant condition characterized by growth of multiple benign cartilage-capped tumors. EXT greatly increases the relative risk to develop chondrosarcoma, although most chondrosarcomas are sporadic. This observation suggests that, like the genes responsible for retinoblastoma and other dominantly inherited cancer susceptibility disorders, the genes that cause EXT may have tumor-suppressor function and may play a role in the pathogenesis of the related sporadic tumors. To investigate this hypothesis, we evaluated chondrosarcomas for loss of constitutional heterozygosity (LOH) at polymorphic loci linked to three recently identified genomic regions containing genes involved in EXT. LOH for markers linked to EXT1 on chromosome 8 was detected in a chondrosarcoma that arose in a man with EXT. Four of 17 sporadic tumors showed LOH for markers linked to EXT1, and 7 showed LOH for markers linked to EXT2 on chromosome 11. In all, LOH was observed for markers linked to EXT1 or EXT2 in 44% of the 18 tumors, whereas heterozygosity was retained for markers on 19p linked to EXT3. These findings support the hypothesis that genes on 8q and the pericentromeric region of 11 have tumor-suppressor function and play a role in the development of chondrosarcomas.

Alleles↗
PubMed1994

The natural history of hereditary multiple exostoses.

We established a database of hereditary multiple exostoses for the state of Washington, on the basis of a retrospective review of the medical records and a clinical evaluation of family members, to determine the prevalence, clinical range of expression, and rate of malignant degeneration. The database comprised forty-six kindreds with 113 affected members; all kindreds had at least one member living in the state of Washington. The over-all prevalence was at least one in 50,000. Approximately 10 per cent of the subjects had no family history of multiple exostoses. With the use of twenty-three pedigrees that demonstrated an adequate multigenerational history for determination of penetrance of the gene, we identified one unaffected individual among twenty-six obligate heterozygotes, a rate of penetrance of 96 per cent. There was no evidence for a substantial reduction of penetrance in female subjects. The median age at the time of the diagnosis in the 113 affected individuals was three years (range, birth to twelve years). In a cohort of eighty-four subjects for whom we had complete information, the clinical range of expression was wide: thirty-three (39 per cent) had an obvious deformity of the forearm, eight (10 per cent) had an inequality in the lengths of the limbs, seven (8 per cent) had an angular deformity of the knee, and two (2 per cent) had a deformity of the ankle. The average number of operations for the patients for whom the operative history was known was two.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Neoplasms↗
PubMed1993

Use of interferon alfa-2a to treat hematologic relapse of chronic myelogenous leukemia after bone marrow transplantation.

The use of recombinant human alpha interferon (IFN) to treat relapse of chronic myelogenous leukemia (CML) in chronic phase after bone marrow transplantation (BMT) was studied in a prospective trial. Relapse was defined as > 90% metaphases containing the Philadelphia chromosome (Ph) and hematologic abnormalities consistent with chronic phase CML. In the initial 18 patients, all received allogeneic marrow, 17 from a related donor, 1 from an unrelated donor. Only 1 patient received T-depleted marrow initially. Three patients had relapsed after second BMT. IFN was started at 3 x 10(6) IU/m2/day and escalated to the maximum tolerated dose or to a maximum of 6 x 10(6) IU/m2/day. Elevated white blood counts and platelet counts were controlled in 14 of 16 and 6 of 6 patients, respectively. Six patients (33%) have had a complete disappearance of the Ph (cytogenetic complete response) and 2 have had a partial response (cytogenetic partial response < 35% Ph+ metaphases but > 0%) on at least one sample. Six patients had no significant response after 9-12 months and 4 patients developed clinical accelerated phase or blast crisis after 3-6 months. IFN controlled the blood counts in 75% of patients. Of 4 patients with a sex marker, the Ph- population was of donor origin in 3 and of host origin in 1. Clonal cytogenetic abnormalities other than the Ph were present in 13 patients and did not predict for lack of response to IFN. IFN effectively produces hematologic control in the majority of patients and suppresses the Ph clone in up to one third. A trial of IFN treatment in an earlier stage of relapse is indicated.

Blast Crisis↗
PubMed1993

Clonal remission in childhood acute myeloid leukemia is an infrequent event.

Acute myeloid leukemia (AML) is a heterogeneous group of diseases that differ in pattern of both remission and lineage involvement. The observation that hematopoiesis remains clonal in some patients with AML in complete clinical remission suggests that the acute phase may develop from a clinically unrecognized preleukemic clone. To investigate the characteristics and significance of clonal remissions in childhood AML, we used X-chromosome-linked polymorphisms to study granulocytes obtained from pediatric female patients in complete clinical remission. Remission granulocytes from only one of 17 evaluable patients were clonally derived, suggesting that clonal remission is an infrequent event in childhood AML.

Acute Disease↗
PubMed1993

Further evidence for the existence of a clonal Ph-negative stage in some cases of Ph-positive chronic myelocytic leukemia.

The Ph chromosome abnormality is involved in the pathogenesis of almost all patients with chronic myelocytic leukemia (CML). Previous studies on the B-lymphoid cell lineage in two patients with Ph-positive CML suggest that there may also be a clonal Ph-negative stage in CML and that the Ph-positive stage arises by subclonal expansion. To determine whether this is a frequent or a rare occurrence, 14 additional glucose-6-phosphate dehydrogenase (G6PD)-heterozygous patients with CML were studied. In five of these patients there was a statistically significant excess of Ph-negative B-lymphoid cell lines expressing the same G6PD type expressed in the corresponding CML clone. In no case was an excess of B-lymphoid lines expressing the opposite G6PD type recovered. These data provide further evidence that in some patients the Ph chromosome arises in a pluripotent stem cell from a pre-existing Ph-negative clone that enjoys a growth advantage.

Adult↗
PubMed1992

Use of alpha interferon for the treatment of relapse of chronic myelogenous leukemia in chronic phase after allogeneic bone marrow transplantation.

Eighteen patients with relapse of chronic myelogenous leukemia (CML) after allogeneic bone marrow transplantation (BMT) were treated with recombinant human alpha 2a interferon (IFN). Relapse was defined as greater than 90% metaphases containing the Philadelphia chromosome (Ph) and hematologic abnormalities consistent with chronic-phase (CP) CML. There were 11 males and seven females, with a median age of 38 years (range, 3 to 55). Three patients relapsed after second BMT. Only one patient had received T-cell-depleted marrow initially. The initial IFN dose of 3 x 10(6) U/m2/d was escalated to the maximum tolerated dose or to a maximum of 6 x 10(6) U/m2/d. IFN controlled the white blood cell (WBC) counts in 14 of 16 patients who had abnormal counts, and in all six patients with an elevated platelet count. Six patients (33%) have had a complete disappearance of the Ph and two have had a partial response (less than 35% Ph+ metaphases). One patient has a decrease in Ph+ metaphases after 9 months of IFN. Five patients had no significant cytogenetic response after 9 to 12 months, and four developed clinical accelerated phase or blast crisis after 3 to 6 months on therapy. Of four patients with a sex marker, the Ph- population was of donor origin in three and of host origin in one. Clonal cytogenetic abnormalities other than Ph were present in 13 patients and did not predict for lack of response to IFN. IFN is effective in suppressing the Ph clone in some patients who relapse with CML after allogeneic BMT and controls the blood counts in the majority.

Adolescent↗
PubMed1992

Persistent clonal areas and clonal expansion in Barrett's esophagus.

Three patients with Barrett's esophagus who had cytogenetic abnormalities detected in their metaplastic epithelium developed high-grade dysplasia or adenocarcinoma during prospective surveillance over a period of 1.5 to 6 years. In the 3 cases, cytogenetic abnormalities that were associated with the most advanced histological lesions were present in samples obtained 11, 25, and 48 months prior to the diagnosis of high-grade dysplasia or carcinoma. In a fourth patient, marker chromosomes found in a Barrett's adenocarcinoma were also present in an esophageal region spatially removed from the tumor. In all four patients, clonal cytogenetic abnormalities were present in samples obtained at widespread locations in the Barrett's segment. These observations suggest that in some patients with Barrett's esophagus clonal proliferations arise in regions of benign histology and spread to involve large areas of Barrett's mucosa. These clones persisted when the disease progressed to high-grade dysplasia or adenocarcinoma.

Adenocarcinoma↗
PubMed1992

Loss of heterozygosity involving the APC and MCC genetic loci occurs in the majority of human esophageal cancers.

The tumor suppressor gene APC was recently identified, and the cDNA was cloned from chromosome 5q21. Point mutations affecting APC are seen in the hereditary syndrome familial adenomatous polyposis, and point mutations in APC and a closely linked gene, MCC, as well as loss of heterozygosity involving chromosome 5q have been reported in sporadic colon cancer. To our knowledge, loss of heterozygosity involving APC or MCC or both has not yet been described in any other human cancer besides lung cancer. We used the polymerase chain reaction and DNA content flow cytometric nuclear sorting to examine 30 primary human esophageal cancers for loss of heterozygosity of APC or MCC or both. Loss of one allele was detected in 77% of 26 informative cases. These data suggest that loss of heterozygosity of regions on 5q including the APC and MCC genetic loci is involved in the development and/or progression of most human esophageal cancers. They imply that inactivation of APC, MCC, and/or a linked gene on chromosome 5q plays a role in the pathogenesis of some cancers of the upper gastrointestinal tract, as well as in colon cancer and familial adenomatous polyposis.

Adenocarcinoma↗
PubMed1992

Identification of a highly polymorphic marker within intron 7 of the ALAS2 gene and suggestion of at least two loci for X-linked sideroblastic anemia.

We have identified a compound dinucleotide repeat within intron 7 of the human erythroid 5-aminolevulinate synthase (ALAS2) gene with a minimum of 9 alleles and heterozygosity of 78%. ALAS2 was placed on the multipoint linkage map of the X chromosome in the pericentromeric region with the locus order: pter-(DXS255, TFE3, DXS146)-(DXS14, ALAS2, DXZ1)-AR-(DXS153, DXS159)-qter. No recombination was observed between ALAS2 and the centromere marker DXZ1. As ALAS2 has recently been shown to be the defective locus in X-linked pyridoxine-responsive sideroblastic anemia (PRSA), the ALAS2 marker has allowed placement of the gene for PRSA into the multipoint linkage map of the X chromosome. With the previous exclusion of close linkage between DXS14 and sideroblastic anemia with ataxia, our data show that there are at least two loci for X-linked sideroblastic anemia.

5-Aminolevulinate Synthetase↗
PubMed1992

Different patterns of X inactivation in MZ twins discordant for red-green color-vision deficiency.

Two female identical twins who were clinically normal were obligatory heterozygotes for X-linked deuteranomaly associated with a green-red fusion gene derived from their deuteranomalous father. On anomaloscopy, one of the twins was phenotypically deuteranomalous while the other had normal color vision. The color vision-defective twin had two sons with normal color vision and one deuteranomalous son. X-inactivation analysis was done with the highly informative probe M27 beta. This probe detects a locus (DXS255) which contains a VNTR and which is somewhat differentially methylated on the active and inactive X chromosomes. In skin cells of the color vision-defective twin, almost all paternal X chromosomes with the abnormal color-vision genes were active, thereby explaining her color-vision defect. In contrast, a different pattern was observed in skin cells from the woman with normal color vision; her maternal X chromosome was mostly active. However, in blood lymphocytes, both twins showed identical patterns with mixtures of inactivated maternal and paternal X chromosomes. Deuteranomaly in one of the twins is explained by extremely skewed X inactivation, as shown in skin cells. Failure to find this skewed pattern in blood cells is explained by the sharing of fetal circulation and exchange of hematopoietic precursor cells between twins. These data give evidence for X inactivation of the color-vision locus and add another MZ twin pair with markedly different X-inactivation patterns for X-linked traits.

Chromosome Mapping↗
PubMed1991

17p allelic deletions and p53 protein overexpression in Barrett's adenocarcinoma.

Barrett's esophagus is a condition in which the stratified squamous epithelium of the esophagus is replaced by metaplastic columnar epithelium that predisposes to the development of esophageal adenocarcinoma. Allelic deletions of 17p and alterations of p53 including elevated p53 protein levels have been observed in many different tumors. To investigate the presence of 17p allelic deletions and p53 protein overexpression in Barrett's adenocarcinomas, we have combined the use of restriction fragment length polymorphism analysis, multiparameter flow cytometry, and DNA content cell sorting. The combined use of these methodologies permits the purification of aneuploid tumor cells for restriction fragment length polymorphism analysis of 17p allelic deletions and the evaluation of p53 protein expression by multiparameter flow cytometry in the same aneuploid tumor cell populations. We analyzed 15 aneuploid populations and one tetraploid populations from 13 Barrett's adenocarcinomas for 17p allelic deletions and p53 protein overexpression to determine whether both of these alterations are involved in carcinogenesis in Barrett's esophagus. Twelve of 13 tumors (92%) had 17p allelic deletions, and 8 of 13 tumors (62%) had p53 protein overexpression. Eight of the 12 tumors (67%) with 17p allelic deletions also had p53 protein overexpression. These data indicate that both 17p allelic deletions and p53 protein overexpression are frequently involved in carcinogenesis in Barrett's esophagus.

Adenocarcinoma↗
PubMed1991

Frequent loss of heterozygosity at the retinoblastoma locus in human esophageal cancers.

Abnormalities in the retinoblastoma tumor suppressor gene (Rb) have been observed in a large number of human cancers. Loss of heterozygosity is a common mode of allelic inactivation of Rb and other tumor suppressor genes. We investigated DNA from 61 primary human esophageal tumors for loss of heterozygosity at the Rb locus using a polymerase chain reaction-based restriction fragment length polymorphism assay. Of informative cases, we found loss of heterozygosity in 14 of 26 (54%) squamous cell carcinomas and 5 of 14 (36%) adenocarcinomas. These data support the hypothesis that Rb inactivation is involved in the pathogenesis and/or progression of esophageal cancer.

Adenocarcinoma↗
PubMed1991

X-linked sideroblastic anemia and ataxia: linkage to phosphoglycerate kinase at Xq13.

Molecular linkage analysis was performed on a kindred with X-linked sideroblastic anemia and ataxia. Two-point analysis with a DNA probe for phosphoglycerate kinase (PGK1), which maps to Xq13, suggested linkage to the disorder by a lod score of at least 2.60 at a recombination fraction of zero. The disease in this kindred appears to be clinically and genetically distinct from that in previously reported families with X-linked hereditary ataxia or spastic paraparesis. No mapping data are available for inherited X-linked sideroblastic anemia without neurologic abnormalities. However, structural alterations of band Xq13 may be involved in the development of idiopathic acquired sideroblastic anemia. No alterations in the restriction patterns of two X-linked genes involved in erythrocyte formation-i.e., a DNA-binding protein (GF-1) and 5-aminolevulinate synthase (ALAS)-were detected in DNA from affected males, arguing against a large deletion in either of these candidate genes.

Anemia, Sideroblastic↗
PubMed1991

Complete deletion of the proteolipid protein gene (PLP) in a family with X-linked Pelizaeus-Merzbacher disease.

Pelizaeus-Merzbacher disease (PMD) is an X-linked neurologic disorder characterized by dysmyelination in the central nervous system. Proteolipid protein (PLP), a major structural protein of myelin, is coded on the X chromosome. It has been postulated that a defect in the PLP gene is responsible for PMD. Different single-nucleotide substitutions have been found in conserved regions of the PLP gene of four unrelated PMD patients. Novel Southern blot patterns suggested a complex rearrangement in a fifth family. Linkage to PLP has been shown in others. We evaluated the PLP locus in a four-generation family with two living males affected with X-linked PMD. Analysis of DNA from the affected males revealed complete absence of a band, with PLP probes encompassing the promoter region, the entire coding region, and the 3' untranslated region and spanning at least 29 kb of genomic DNA. DNA from unaffected relatives gave the expected band pattern. Two obligate and one probable carrier women were hemizygous for the PLP locus by dosage analysis. Although it is unlikely, the previously described point mutations in PLP could represent polymorphisms. The finding of complete deletion of the PLP gene in our family is a stronger argument that mutations in PLP are responsible for X-linked PMD.

Adult↗