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S Pedron

Publications and source records attributed to S Pedron.

10 recordsLinked to original sources
PubMed2000

Establishment and characterization of a spontaneously immortalized myofibroblast cell line derived from a human liver angiosarcoma.

BACKGROUND/AIM: Fibrosis and/or cirrhosis are present in the precursor stages of most liver cancers. However, little is known about the reciprocal interactions of fibroblasts, mainly responsible for fibrosis, and the other liver cells. We report here the isolation of a new liver myofibroblast cell line from a human liver angiosarcoma and its characterization. METHODS: The cells were isolated by the explant technique and characterization was performed, on one hand, using immunohistochemical and ultrastructural analysis and, in the other hand, by determining their karyotype, ras and p53 status and their tumorigenic properties. RESULTS: To date, the cells have undergone approximately 170 population doublings and are still proliferating. Immunohistochemically, they were negative for desmin, smooth muscle myosin, cytokeratin 19 and von Willebrand factor, positive for vimentin and alpha-smooth muscle actin, with an important deposition of fibronectin around the cells. Ultrastructure showed particularly cytoplasmic microfilament bundles. Their chromosome number ranged from 38 to 168 with a bimodal population, near diploid and hypotetraploid. No mutations were found in codons 12, 13 or 61 of Ha-, Ki- and N-ras genes but a homozygous missense mutation in codon 179 (CAT-->CTT) was detected in the p53 gene. They were unable to form foci in soft agar or tumors in nude mice. CONCLUSIONS: Taken together, these results show that these cells, called BM 2.2.1, exhibited typical myofibroblast-like features. Although they contained a karyotype suggestive of tumoral cells and a homozygous mutated p53 gene, they were not tumorigenic. The nature of these cells and the abnormalities of the p53 gene and the karyotype, suggest that: i) they were a component of the tumor stroma, and ii) they could have been involved in angiosarcoma development. Thus, this cell line may be valuable for the study of cellular interactions in liver carcinogenesis.

Animals↗
PubMed1996

p21/WAF1 cyclin-kinase inhibitor expression in non-Hodgkin's lymphomas: a potential marker of p53 tumor-suppressor gene function.

p21WAF1 (wild-type p53-activated fragment 1) is involved in the control of mammalian cell cycle through the binding and inhibition of cyclin-dependent kinases (Cdk). Because the product of WAF1 gene is a potent downstream effector of the p53 tumor-suppressor gene function, its pattern of cellular expression might correlate with nuclear accumulation of p53-encoded protein and/or p53 gene mutations occurring in malignant lymphomas. To investigate this issue, we analyzed immunohistochemically the expression of p53 and p21WAF1 proteins in tissue involved by non-Hodgkin's lymphomas (NHLs;253 cases) of various histologic types. In a proportion of them (80 cases), we also investigated the possible presence of p53 gene mutations using single-strand conformation polymorphism analysis and direct DNA sequencing. The absence of both p21WAF1 and p53 proteins was observed in 147 of 217 cases (67.7%) among CD30-NHL and in only 8 of 36 (22.2%) CD30+cases, which were mostly anaplastic large-cell lymphomas. A consistent number (> 10%) of p21WAF1-expressing cells was shown in 48 of 253 (18.9%) NHL cases, with a higher incidence in CD30+cases (25/36 [69.4%]), which mostly (21/36) coexpressed p53. These latter cases were characterized by a germline configuration of the p53 gene. In 50 of 253 NHL samples (19.7%), 47 of which (21.6%) belong to the CD30-group, neoplastic cells were p53+/p21-. In all of these cases, the p53+cells accounted for more than 50% of neoplastic cells, up to 100%. Point mutations of p53 gene were solely observed in all investigated cases with this latter phenotype. Our findings strongly suggest that the combined immunohistochemical evaluation of p53 and p21WAF1 is a valuable means of assessing the functional status of the p53 tumor-suppressor gene product in NHL with potential application in the monitorage and prognostication of individual cases.

Biomarkers↗
PubMed1996

Gangliosides protect human melanoma cells from ionizing radiation-induced clonogenic cell death.

With an experimental model of spontaneous lung metastases of melanoma developed in this laboratory, a range of sublines (variants and clones) with different metastatic potential and ganglioside expression was established from a single human melanoma cell line M4Be. Using an in vitro clonogenic assay and provided that cells were cultured for no more than five passages, variations in cellular radioresistance of M4Be and seven sublines derived from M4Be were detected. This study shows a positive correlation between the cell intrinsic radioresistance of M4Be and its seven sublines and their total ganglioside content. More precisely, the proportion of radioresistant cells in M4Be and the seven sublines correlated with the number of cells determined by flow cytometry that were positively labelled with a monoclonal antibody directed to GD3 disialoganglioside. Blocking the cellular biosynthesis of gangliosides with the inhibitor Fumonisin B1 or cleaving with Vibrio cholerae neuraminidase the cell surface ganglioside-bound sialic acid in a radioresistant poorly metastatic subline increased its radiosensitivity in vitro. In contrast, enrichment of a radiosensitive metastatic subline with exogenous bovine brain GM1 increased its radioresistance in vitro. These results suggest that, in the radiation dose range important for radioprotection (0-1 Gy), membrane gangliosides radioprotect human melanoma cells in vitro.

Animals↗
PubMed1995

Deficiency of ganglioside biosynthesis in metastatic human melanoma cells: relevance of CMP-NeuAc:LacCer alpha 2-3 sialyltransferase (GM3 synthase).

The glycosphingolipid patterns were analyzed on two clones derived from a human melanoma cell line and selected for their respectively high and low metastatic ability in immunosuppressed newborn rats. Conversely to the weakly metastatic cells which exhibited a pattern similar to that of the parental cell line, highly metastatic human melanoma cells appeared to be deficient in ganglioside biosynthesis. An accumulation of lactosylceramide was found in the latter cells, with low amounts of GM3 as the only ganglioside detected and a fourfold decreased activity of GM3 synthase (EC 2.4.99.9). After subcutaneous injection of metastatic cells in newborn rats, the cells proliferating in the tumor induced at the injection site re-expressed the four common gangliosides of melanoma: GM3, GM2, GD3 and GD2, whereas the cells growing in the lungs as metastatic nodules were deficient in ganglioside synthesis and showed an accumulation of lactosylceramide. Taken together, our results suggest that the human melanoma cells which are able to escape from the primary tumor and invade the lungs have an impaired ganglioside biosynthesis with a deficient GM3 synthase.

Animals↗
PubMed1994

A rapid immunostaining method for frozen sections.

A simple and rapid one-step method for demonstrating immunohistochemical markers (leukocyte common antigen, cytokeratin, etc.) is described, which can help define the nature of poorly differentiated neoplasms for diagnosis using frozen section. Microwave irradiation was used to speed immunohistochemical analysis using "Enhanced Polymer One-step Staining" (EPOS) reagents on cryostat sections from a variety of pathologic samples. Reproducible results were obtained using EPOS reagents for leukocyte common antigen and cytokeratin. The overall procedure takes less than 10 min and can be completed during surgery.

Frozen Sections↗
PubMed1993

Constitutive expression of tenascin in T-dependent zones of human lymphoid tissues.

Tenascin is a major extracellular matrix glycoprotein that can interfere with the action of fibronectin by inhibiting cell adhesion and spreading. Although tenascin is able to exert important immunomodulatory activities on T and B cells and macrophages, little is known about its distribution in different lymphohemopoietic tissues. In this study we have analyzed tenascin immunoreactivity on cryostat and paraffin sections of normal and pathological lymphoid tissues using two different monoclonal antibodies. We demonstrated strong tenascin expression in all peripheral lymphoid tissues, whereas it was barely detectable in the thymus and in bone marrow. In reactive lymph nodes, tenascin was mainly found in T-dependent zones, forming a variably close-woven reticular network corresponding to fibroblastic reticulum cells and blood vessels basal laminae, showing a partial co-localization with fibronectin. In B-dependent zones, tenascin was restricted to blood vessels. Using double-marker analysis, we performed a thorough study comparing tenascin expression in different compartments of lymphoid microenvironments. Tenascin network appeared much thicker in chronically stimulated tissues, where CD4+ lymphocytes with "memory" phenotype (CD45RO+/CD45RA-) were predominant, and at sites of ongoing inflammation. In particular, a striking increase of tenascin was observed in sarcoid lymph node, as well as in myasthenic hyperplastic thymuses. In addition, tenascin can be abnormally synthesized in tissue involved by various types of lymphomas, including Hodgkin's disease and hairy cell leukemia.

Bone Marrow↗
PubMed1991

Nonrandom cytogenetic changes in leiomyomas of the female genitourinary tract. A report of 35 cases.

Cytogenetic analysis of short-term cultures from 35 leiomyomas of the female genitourinary tract showed abnormal karyotypes in 14 cases. In 11 of 14 aberrant tumors, normal cells were also observed. Structural changes were most frequent, resulting in modal chromosome numbers in the diploid range. Our data confirm preferential breakpoint clusters at 7q, 12q14-15, and 14q23-24, mainly resulting from consistent, specific chromosome rearrangements such as t(12;14)(q14-15;q23-24) and del(7)(q21) or del(7)(q22q32). Together with previously published cases, we describe trisomy 12, ring chromosomes, and monosomy 22 as new additional recurrent findings in myomas. Statistical analyses of possible coherencies between tumor karyotype (abnormal versus normal) and clinicopathologic data, as well as age of the patients, menopausal status, and tumor size showed no correlations.

Adult↗
PubMed1991

[Maintenance therapy with beta-methyldigoxin in the elderly. A study of 40 patients].

The efficacy of beta methyldigoxin was examined in a group of 40 elderly patients who had been hospitalised due to congested heart decompensation. A good clinical response was obtained in 95.5% of cases with the presence of slight toxic phenomena in 2 cases only (4.5%). The paper underlines the excellent pharmacokinetic pattern of the substance used in the steady state. Steady state digitalemic values were within the acceptable range in 83.76% of cases, whereas underdosage and overdosage phenomena were observed in 6.87% and 9.37% of patients respectively.

Aged↗
PubMed1990

Cytogenetic findings in nine leiomyomas of the uterus.

Chromosomal analysis of nine benign leiomyomas of the uterus after short-term culture showed karyotypic abnormalities in four cases. All four exhibited multiple chromosome changes, including three cases characterized by complex chromosome rearrangements involving a number of chromosomes. Among others, these rearrangements included a translocation between chromosomes 12 and 14 in one case, a deletion of chromosome 7q in two cases, and both del(7q) and a complex translocation involving chromosomes 12 and 14 in another case. These results confirm the involvement of chromosomes 7, 12, and 14 in leiomyomas and indicate that benign tumors can also be characterized by complex cytogenetic changes.

Adult↗