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C Rivas

Publications and source records attributed to C Rivas.

At least 109 records · Page 6Linked to original sources
PubMed1992

A multiparametric study of malignant lymphoma of mucosa associated lymphoid tissue (MALT).

A morphological, immunophenotypic and ultrastructural study, cell cycle estimation, DNA and cytogenetic analysis were performed in ten cases of B-MALT lymphomas. Five had low grade lymphoma and five had high grade. Low and high grade cases showed the same cells but in different percentages: These included centrocyte-like cells with occasional monocytoid cytoplasmic changes, and centroblast-like cells. However, in high grade cases more dysplastic and large cells were present. All cellular types showed an important development of rough endoplasmic reticulum. In all cases a large panel of monoclonal antibodies was employed to study the B-cell immunophenotype. Ki-67 positivity ranged from 5% to 30% in low-grade cases and from 50% to 70% in high-grade cases. Gene rearrangement analysis showed rearrangement with Jh probe and half of the cases were also rearranged with the Kde probe (Kappa constant chain gene). A rearrangement banding pattern with TCR genes was not present in any of the cases. Cytogenetic study showed complex alterations in high grade cases and a normal karyotype in low grade lymphomas. Only one case had rearrangement for the bcl-2 probe.

Female↗
PubMed1992

[Castleman's disease. A multifactorial study].

A case of Castleman's disease (hialino-vascular subtype) in a female patient 15-years-old is considered. Clinically there were isolated lymphadenopathies which relapsed after surgery and absence of general syndrome. Histoimmunological and electron microscopic studies were performed as DNA rearrangement and cytogenetics in order to exclude genetic abnormalities and monoclonality of this disorder. The role of follicular dendritic component in discussed.

Adolescent↗
PubMed1992

[T-lymphomas with splenic presentation].

Three cases of lymphomas with splenomegaly onset, without peripheric adenopathies, which required laparotomy to be diagnosed, are discussed. One of the cases was a primary splenic lymphoma and the other two were associated with reactive hemophagocytosis. Other malign lymphoproliferative processes of predominant splenic onset are discussed.

Adult↗
PubMed1992

Age-related capacity of neuroendocrine factors to differentiate T cells in vitro.

The present report shows the capacity of hypothalamic extract (HE) to differentiate bone marrow cells to Thy-1+ cells in vitro. A two-step short-term culture was used. In the first step thymus and pituitary were co-cultured in the presence of HE. Supernatant was then transferred to a bone marrow cell suspension and following a period of culture, the percentage of Thy-1+ cells was determined by a microcytotoxicity assay. Results indicated that: (a) HE from young mice show a very efficient differentiating capacity; (b) HE from young mice is equally efficient when old pituitary, thymus and marrow are used; (c) HE from old donors has no capacity to differentiate T cells; (d) there is a progressive age-related decline of this capacity; and (e) there is a feed-back mechanism involved in this process. It is concluded that hypothalamic factors can regulate the differentiation of T cells and that this effect operates through a mechanism involving pituitary and thymus.

Aging↗
PubMed1991

Characterization of Trypanosoma cruzi from Argentina by electrophoretic zymograms.

Polyacrylamide gel electrophoretic patterns for six enzymes in 73 isolates and 38 clones of Trypanosoma cruzi from different areas of Argentina were classified into 12 zymodemes. The isolates were obtained from human patients with acute, chronic or congenital Chagas' disease, vector insects, domestic and sylvatic animals. Two out of 8 isolates cloned were shown to be heterogeneous. Zymodemes 1 and 12 exhibit widespread geographic distribution; isolates belonging to both zymodemes account for 55% of the total analyzed. The other zymodemes are not widely geographically dispersed. Although there is a clear predominance of zymodeme 1 among asymptomatic patients, the data do not show a clear relationship between particular zymodemes and the clinical picture. The results suggest that the sylvatic and domestic transmission cycles overlap. This remarkable heterogeneity of T. cruzi in Argentina supports the possible multiclonal origin of these parasite populations.

Animals↗
PubMed1991

[Cytogenetic and molecular aspects in MALT lymphomas].

Cytogenetic and molecular results in 10 patients with extranodal lymphoma (MALT): 5 low grade and 5 high grade, were compared with the results observed in nodal lymphomas. This study suggests that there are cytogenetic differences between extranodal and nodal low grade lymphomas. Both molecular analysis by conventional Southern blot with probes for the major and minor regions of bcl-2 gene, and PCR analysis with primers from these regions, showed that t (14; 18) is a sporadic event in MALT lymphomas.

Aneuploidy↗
PubMed1991

Photodegradation of nalidixic and tiaprofenic acids and nifedipine in aerobic conditions.

Since nalidixic acid had been previously studied in acidic and basic media, nifedipine had been investigated in anaerobic conditions and under ultraviolet light and tiaprofenic acid had not been studied at all, their photodegradation was carried out in this laboratory under milder conditions, with methanol as the solvent and using visible light. The role of oxygen was demonstrated and the photoproducts were isolated and identified spectroscopically.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1991

[Molecular analysis in 23 patients with T-lymphomas].

Gene rearrangement analysis has been performed in 23 patients with T-cell lymphoproliferative diseases: 4 cases with T-gamma lymphocytosis, one case of a Sezary's syndrome, one case of T-cell angioimmunoblastic lymphoma, two cases of T-cell lymphoepitheloid lymphoma, 11 patients with T-cell pleomorphic lymphoma, 3 cases of large anaplastic T-cell lymphoma and one case of T-cell lymphoblastic lymphoma. Rearranged banding patterns have been observed for at least one of the T-cell receptors (TCR) in 19 of the cases, and germ line configuration of the TCR and Ig genes in the other four. Likewise, both Ig and TCR rearrangements have been observed in three cases (one case of T-cell pleomorphic lymphoma, one case of large anaplastic T-cell lymphoma and one case of T-cell lymphoblastic lymphoma). Molecular genetic techniques have been used in order to direct monoclonal proliferations of T cell in the tumoral tissues, to determine the T- or B-cell lineage of the neoplasia and also to outline the molecular characteristics of each group that constitutes the complex classification of T-cell malignancies.

Gene Rearrangement, B-Lymphocyte↗
PubMed1991

Inhibition of glutathione synthesis in the liver leads to S-adenosyl-L-methionine synthetase reduction.

The hepatic levels of glutathione in rats treated with buthionine sulfoximine (4 mmol/kg), an inhibitor of glutathione synthesis, were 72.5% +/- 4.9% of those determined in control animals. This decrease in glutathione concentration was prevented by the administration of glutathione monoethyl ester (7.5 mmol/kg). S-Adenosyl-L-methionine-synthetase activity in the liver of rats treated with buthionine sulfoximine was 39.4% +/- 6.5% of that determined in control animals. Again, glutathione monoethyl ester prevented the effect of buthionine sulfoximine on S-adenosyl-L-methionine-synthetase activity. There was a close correlation (r = 0.936) between the hepatic levels of glutathione and S-adenosyl-L-methionine-synthetase activity. The hepatic concentration of S-adenosyl-L-methionine in buthionine sulfoximine-treated animals was 59.7% +/- 3.7% of that measured in control rats. Contrasting with the protective effects mentioned above, glutathione monoester had no preventive action on buthionine sulfoximine-induced S-adenosyl-L-methionine depletion. Electron microscopic examination of liver samples of rats after buthionine sulfoximine administration showed evidence of liver degeneration, which was attenuated by glutathione monoethyl ester treatment. Glutathione (7.5 mmol/kg) treatment was less effective than glutathione monoethyl ester in attenuating buthionine sulfoximine effects on hepatic S-adenosyl-L-methionine metabolism and morphology. The reduction of S-adenosyl-L-methionine-synthetase activity observed after treatment with buthionine sulfoximine and its prevention by glutathione monoethyl ester, as well as the correlation between the activity of this enzyme and glutathione levels, indicate that glutathione plays an important role in maintaining S-adenosyl-L-methionine-synthetase activity in the liver.

Acetaminophen↗
PubMed1990

[Low-grade B cell gastric lymphoma originated in mucosa-associated lymphoid tissue. Relationship of tumor cells with the marginal zone and monocytoid B lymphocytes. An immunohistochemical and ultrastructural study].

Seven cases of gastric B-cell low-grade lymphomas were characterized by morphology, immunohistology and electron microscopy. All them were immunophenotyped with a panel of monoclonal antibodies against immunoglobulins and other B-cell determinants. Histologic study of gastric B-cell low-grade lymphomas showed germinal centers of lobated shape and polyclonal nature, mainly polyclonal subepithelial plasma cell (except in one case) and neoplastic interfollicular B-cells of monoclonal character. Light-chain restriction supports the neoplastic nature of gastric lymphoma of low-grade malignancy, a distinctive tumour of extranodal B-cell origin. Interfollicular B-cells share with marginal zone cells a perifollicular localization, morphology and phenotype, suggesting a possible relation between these two cellular subtypes. In two cases, the tumour appears constituted by monocytoid B-lymphocytes (MBL), which suggests a relation of tumoral interfollicular B-cells with this subpopulation.

Adult↗
PubMed1989

[Sézary syndrome: morpho-immuno-phenotypic, cytogenetic and molecular characterization].

The immunologic, cytogenetic and molecular data from a patient with Sézary syndrome are reported. Immunohistochemical analysis disclosed 90% helper CD4 cells and 10% CD8 cells. One of the most significant cytogenetic abnormalities was a t(7; 14) translocation at the level of the 7p13-15 and 14q11 bands, just where the T-cell receptors are located. At the molecular level, rearrangements of the alpha (in 14q11 chromosome), beta (in the 7q32) and gamma (in the 7p15) receptors were found. The translocation between chromosomes 7 and 14, at the level of the mentioned bands, could be responsible for some of the rearrangements found at the molecular level.

Chromosomes, Human↗