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Biomedical subjects

G Torelli

Publications and source records attributed to G Torelli.

At least 91 records · Page 5Linked to original sources
PubMed1996

P53 gene mutations in chronic myelogenous leukemia medullary and extramedullary blast crisis.

Molecular alterations of the P53 gene were investigated in 27 unselected patients with chronic myelogenous leukemia (CML) blast crisis. A rearrangement of the P53 gene was evident by Southern blotting in 3 cases, one of which also showed the same alteration in the chronic phase. Single strand conformation polymorphism and sequencing analysis showed point mutations in 4 blast crisis cases. Of interest, P53 point mutations were evident in all the 3 cases of extramedullary blast crisis examined and the same point mutation was found in the myeloblastoma tissues and in the subsequent peripheral blast cells. These data indicate that: a) P53 gene mutations occur in a significant but not a large number of CML acute phase cases; b) P53 gene point mutations seem to correlate strongly with the infrequent extramedullary presentation of the blast crisis; c) the presence of the same P53 gene point mutation in extramedullary and bone marrow blast cells confirms the common clonal origin of the two cellular populations.

Blast Crisis↗
PubMed1996

Hepatitis C virus infection in subsets of neoplastic lymphoproliferations not associated with cryoglobulinemia.

Hepatitis C virus (HCV) is both hepatotropic and lymphotropic and a clear-cut association has been proposed between HCV infection and mixed cryoglobulinemia (MC), a benign lymphoproliferative disorder, which sometimes evolves into a frank malignant B cell non-Hodgkin's lymphoma (B-NHL). Moreover, in the presence of antibodies to HCV, as well as of HCV-specific genomes has been reported in the sera of over 37% patients with B-NHL, not associated with MC. Thus, we decided to perform both a serologic and a molecular study to give insights into a possible relationship between HCV infection and neoplastic lymphoproliferations. We used ELISA and RIBA tests to show that anti-HCV antibodies were present in the serum of 29 out of 69 unselected B-NHL patients (42%), while seropositivity in a healthy population was about 1%. The prevalence of anti-HCV antibodies was low in definite subsets of B lymphoid disorders, including multiple myeloma, Waldenström's macroglobulinemia and monoclonal gammopathies of undetermined significance. Then, using reverse transcriptase polymerase chain reaction, we detected HCV sequences directly in the pathologic lymph node biopsies in 13 out of 34 B-NHL cases, and in particular in six out of eight low-grade lymphomas of MALT type and in five out of eight centroblastic-centrocytic follicular lymphomas. In contrast, the peripheral blood samples from 10 B cell chronic lymphocytic leukemia patients resulted negative for the presence of HCV genomes. Similarly, viral sequences were absent in 10 T cell NHL, while only one out of the 14 Hodgkin's disease cases tested resulted positive. Finally, we used a PCR-based assay to characterize the genotypes (I-IV) present in the positive lymphomatous tissues. The presence of both serologic and molecular markers of HCV infection in a high percentage of certain types of B-NHL, not associated with cryoglobulinemia, and its absence from other lymphoproliferative diseases extends the spectrum of HCV-associated lymphoproliferations arguing in favor of some role of this viral infection in the pathogenesis of the malignant proliferation of definite B lymphoid populations.

Cryoglobulinemia↗
PubMed1995

Spontaneous loss of Ph chromosome with maintenance of clonal hemopoiesis in an untreated patient with myeloproliferative disease and a long survival.

The unusual case of myeloproliferative disease described here is characterized by the following features: (1) a clinically completely silent course for 11 years without splenomegaly, marrow fibrosis, or cellular morphologic alterations; (2) the presence, at the onset, of a Philadelphia (Ph) chromosome without DNA breakpoints in the M-bcr region; (3) the spontaneous loss of detectable Ph-positive cells, 5 years after the first finding of leukocytosis, in the absence of any therapy; (4) the maintenance of the clonal nature of hematopoiesis, as revealed by the PGK X-linked inactivation pattern, in the absence of the Ph chromosome; and (5) a biphasic trend in the levels of leukocytes, red cells, and platelets during the years of observation.

Adult↗
PubMed1995

Geographic sequence variation of latent membrane protein 1 gene of Epstein-Barr virus in Hodgkin's lymphomas.

To assess the role of the Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) gene in the development of Hodgkin's lymphoma (HL), the polymorphism of this gene in EBV isolates from different geographic locations was analyzed. A 497 bp fragment spanning LMP1 gene exons 1 and 2 was amplified by polymerase chain reaction (PCR), using a primer pair bracketing a Xhol restriction site. PCR products were subjected to Xhol digestion and to DNA sequencing analysis. Twenty-five HL biopsy specimens from the United States and five HL and four non-Hodgkin's lymphoma (NHL) biopsy specimens from Italy were examined. Eighty percent of LMP1-positive samples (12 of 15) from the United States maintained the Xhol restriction site and the remaining 20% partially lost the Xhol site. One of four EBV-positive HL and one of the three EBV-positive NHL specimens from Italy lost the restriction site. The other three EBV-positive HL DNAs were partially cut by Xhol. Direct DNA sequencing analysis revealed that those Italian samples not digested by Xhol were due to a G to C transversion at the first base of codon 18, resulting in the change of glycine to arginine. Those DNA samples partially cut by Xhol were due to a mixture of G/C at the same location. In contrast, those partially digested American HL DNAs had a mixture of G/T at the second base of codon 17.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1995

Targeted integration of human herpesvirus 6 in the p arm of chromosome 17 of human peripheral blood mononuclear cells in vivo.

Out of 64 cases of non-Hodgkin's lymphomas (NHL), 55 cases of Hodgkin's disease (HD) and 31 cases of multiple sclerosis (MS), 2 NHL, 7 HD and 1 MS cases were found positive by polymerase chain reaction (PCR) for the presence of HHV-6 sequences in pathologic lymph nodes of the lymphomas and in peripheral blood mononuclear cells (PBMCs) of MS. A further analysis of the PBMCs of the PCR positive cases by standard Southern blot technique revealed only 2 NHL, 3 HD and 1 MS cases as positive, indicating that these six patients have an unusually high viral copy number in the PBMCs. Restriction analysis, carried out using probes representative of different regions of the virus, showed that three cases retain only a deleted portion of the viral genome. In the remaining three cases a complete viral genome was present, containing the right end sequences in which the rep-like gene, possibly crucial to the viral and cellular life cycle, is located. The analysis by pulsed field gel electrophoresis (PFGE) of the total DNA of the PBMCs obtained directly, without culture from PBMCs of these last three cases (1 NHL, 1 HD, and 1 MS), using the same probes, showed the absence of free viral molecules and the association of viral sequences with high molecular weight DNA. These results are consistent with in vivo integration of the entire virus in the cellular genome. A further study of the same patients with chromosome fluorescence in situ hybridization (FISH) showed in all the three cases the presence of a specific hybridization site, located at the telomeric extremity of the short arm of chromosome 17 (17p13), suggesting that this location is at least a preferred site of an infrequent, but possibly biologically important, integration phenomenon.

Adult↗
PubMed1995

Human herpesvirus-6: a survey of presence and distribution of genomic sequences in normal brain and neuroglial tumors.

In an attempt to study the frequency and distribution of human herpesvirus-6 (HHV-6) infection both in normal and neoplastic brain tissues in vivo, polymerase chain reaction was used to look for HHV-6 genomes: 1) in samples, obtained at necropsy, from different regions of the brain of immunocompetent adult subjects and of patients who died of AIDS; 2) in the surgical biopsies of a well-characterized series of primary brain tumors of neuroglial origin. HHV-6-specific sequences were identified in six of nine brain samples from immunocompetent subjects, and in four of seven brain samples from AIDS patients. Viral sequences were identified in the specimens derived either from the grey (frontal cortex and basal ganglia) or from the periventricular white matter. HHV-6 DNA was found only in 6 of the 37 primary brain tumor biopsies examined. This study provides for the first time molecular evidence of a wide distribution of HHV-6 infection in the brain tissues of a high proportion of subjects, both in normal and in impaired immunity. In this large series of tumor biopsies the presence of HHV-6 genomic sequences is a rare phenomenon, arguing against a major role of this herpesvirus in the pathogenesis of primary brain tumors of neuroglial origin in immunocompetent subjects.

Acquired Immunodeficiency Syndrome↗
PubMed1995

p53 gene point mutations in relation to p53 nuclear protein accumulation in colorectal cancers.

It is known that structural alterations of the p53 tumour suppressor gene cause malignant transformation and tumour progression in colorectal mucosa. In this study, 38 colorectal cancers were analysed for mutations detected in the p53 gene by single-strand conformational polymorphism and DNA sequence analysis, and the results were compared with p53 protein expression detected by immunohistochemistry. A very strict association (P < 0.0001) was found between genetic alterations and protein accumulation, as detected by the PAb 1801 monoclonal antibody. p53 expression and gene mutations were more frequent in rectal than in colonic cancers. No relation was observed with Dukes' stage, even though most of the mutations were at exon 7 in Dukes' A-B cancers and almost all mutations at exon 8 were observed in Dukes' C-D cancers. DNA ploidy was not generally associated with p53 protein expression or gene mutations. However, 83 per cent of cases with exon 5 and 6 mutations were diploid or near-diploid and 71 per cent of cases with mutations at exons 7 and 8 were aneuploid. Tumours with p53 gene mutations at exon 5 had a higher median [3H]thymidine labelling index (17 per cent) than those with mutations at exons 6, 7, and 8 (11.8 per cent).

Base Sequence↗
PubMed1995

Detection of PML-RAR alpha fusion transcript in Ph positive leukemia with acute promyelocytic phenotype lacking the t(15;17) cytogenetic abnormality.

A 39-year-old woman was diagnosed with acute promyelocytic leukemia (APL) with disseminated intravascular coagulation syndrome. The hematologic examination showed a morphologic, cytochemical, and immunophenotypic picture typical of an APL, with a marked leukocytosis and a mixed population of hypergranular and microgranular promyelocytes. The cytogenetic analysis showed a 46,XX,t(9;22) karyotype, without any alterations of chromosomes 15 and 17. The t(15;17) translocation was not evident in FISH experiments, while a molecular analysis revealed the presence of a PML-RAR alpha chimera.

Adult↗