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Biomedical subjects

D Rocha

Publications and source records attributed to D Rocha.

11 recordsLinked to original sources
PubMed1997

Molecular cloning, sequencing and expression of the mRNA encoding human Cdx1 and Cdx2 homeobox. Down-regulation of Cdx1 and Cdx2 mRNA expression during colorectal carcinogenesis.

Defining the molecular mechanisms involved in cancer formation and progression is still a major challenge in colorectal-cancer research. Our strategy was to characterize genes whose expression is altered during colorectal carcinogenesis. To this end, the phenotype of a colorectal tumour was previously established by partial sequencing of a large number of its transcripts and the genes of interest were selected by differential screening on high-density filters with mRNA of colorectal cancer and normal adjacent mucosa. Fifty-one clones were found over-expressed and 23 were underexpressed in the colorectal-cancer tissues of the 5 analyzed patients. Among the latter, clones 6G2 and 32D6 were found of particular interest, since they had significant homology with several homeodomain-containing genes. The highest degree of similarity was with the murine Cdx1 for 6G2, and with the murine Cdx2 and hamster Cdx3 for 32D6. Using a RT-PCR approach, complete sequence of both types of homeobox-containing cDNA was obtained. The amino-acid sequence of the human Cdx1 is 85% identical to the mouse protein, and human Cdx2 has 94% identity with the mouse Cdx2 and hamster Cdx3. Tissue-distribution analysis of Cdx1 and Cdx2 mRNA showed that both transcripts were specifically expressed in small intestine, in colon and rectum. Twelve tissue samples from colorectal adenocarcinomas and the corresponding normal mucosa were analyzed by Northern blot. Expression of the 2 types of mRNA was either reduced or absent in 10 of them. Several colon-cancer cell lines were also analyzed. Cdx2 mRNA was absent from LS174T cells and Cdx1 mRNA was absent in PF11, TC7 and SW480 cells; none was detected in HT29 cells. It was concluded that decrease in human Cdx1 and/or Cdx2 expression is associated with colorectal tumorigenesis.

Adenocarcinoma↗
PubMed1997

Differential mRNA expression in untreated and TNF-alpha elicited murine dendritic cells precursors.

We have compared the pattern of gene expression in long term cultured precursor dendritic cells (DC), either untreated (immature) or cultured for two days in the presence of recombinant murine (rm)-TNF alpha (mature). The hybridization signature of complex cDNA probes prepared from total RNA extracted from immature and mature DC were analyzed using a mouse thymic cDNA library, gridded on high density filters. For each clone spotted on the filters, we have measured using an imaging plate device the hybridization signals of the complex probe obtained from immature or mature DC. Comparative analysis of these values allowed us to identify differentially expressed gene products. Our goal is to identify a new set of genes induced or repressed during DC maturation elicited by rmTNF alpha treatment.

Animals↗
PubMed1997

Modulation of mRNA levels in the presence of thymocytes and genome mapping for a set of genes expressed in mouse thymic epithelial cells.

Modulation of gene expression in mouse thymic epithelium upon culture in the presence of thymocytes (coculture) was studied by comparison of hybridization signatures on a set of nearly 5000 mouse thymus cDNA clones. Forty-nine differentially expressed clones (usually down-regulated in coculture) were characterized by tag sequencing. Many of them corresponded to entities that had not been described previously in the mouse, and were further characterized by genome mapping. This set of genes appears to be involved in growth regulation and differentiation within the thymus.

Animals↗
PubMed1996

From hybridization image to numerical values: a practical, high throughput quantification system for high density filter hybridizations.

Hybridization to sets of bacterial colonies or PCR products arrayed on high density filters is used in a number of experimental schemes. In many cases it is desirable to collect quantitative information ('hybridization signatures') rather than indications on 'positive' and 'negative' colonies. We present a practical system, based on an imaging plate analyser and a customized version of commercial software, that makes such quantification feasible, and define its performance in terms of reproducibility and linearity. The system is far superior to methods based on autoradiography and should be useful in many projects that involve the increasingly popular high density filter format.

Animals↗
PubMed1995

Differential gene expression in the murine thymus assayed by quantitative hybridization of arrayed cDNA clones.

High-throughput measurement of hybridization signatures obtained using complex probes prepared from poly(A)+ RNA and high-density cDNA colony filters is described. The performance of the system, elimination of artifacts, and verification of the validity of the data are discussed. cDNAs corresponding to sequences present at levels of approximately 0.01% in the complex probe can be detected. Good correlation is observed between expression profiles determined by this method and by Northern blotting. The method is applied to a preliminary investigation of differential expression in three cell types present in the murine thymus.

Animals↗
PubMed1993

Overexpression of YAP2, coding for a new yAP protein, and YAP1 in Saccharomyces cerevisiae alleviates growth inhibition caused by 1,10-phenanthroline.

A new member of the yeast yAP family, designated YAP2, has been isolated and characterized. The protein displays a high homology with the DNA-binding domain of yAP-1, which contains a basic DNA-binding domain and leucine zipper motif and binds in vitro to the same cis-element. Growth arrest of yeast caused by low concentrations of 1,10-phenanthroline, resulting in zinc and/or iron deprivation, is overcome by over-expression of YAP1 or YAP2. In fact, yeast cells over-expressing YAP1 or YAP2 display pleiotropic drug resistance. On the other hand, a yap2 null mutant has an increased thermotolerance under starvation conditions caused by 1,10-phenanthroline. The latter mutant might become an excellent tool in the study of pathways leading toward thermotolerance acquisition.

Amino Acid Sequence↗
PubMed1988

Comparison of genetic probe with immunophenotype analysis in lymphoproliferative disorders: a study of 87 cases.

We examined 91 specimens (from 87 patients) for the expression of B-cell- and T-cell-associated differentiation antigens and rearrangements of the Ig and beta-chain of the T-cell (beta-TCR) genes. Of these, 74 were representative of various histologic subtypes of non-Hodgkin's lymphoma and related disorders, 11 of Hodgkin's disease, and 6 of reactive lymphoid hyperplasia. An Ig gene clonal rearrangement correlated to a monotypic (kappa/lambda) phenotype in 32 of 33 histologically defined lymphoma samples. The genotypic analysis also confirmed clonality in six of seven malignant diffuse lymphomas that were nonmonotypic but expressed pan-B antigens; in four, more than one clone was detected within individual tumors. A beta-TCR clonal rearrangement was found in 19 of 19 tumor samples considered as malignant T-cell lymphoma on the basis of histopathology and of the CD3-positive phenotype of tumoral cells, and in two cases of CD3-positive lymphomatoid disorders. A loss of pan-T antigens (CD7, CD5, CD2, CD4/CD8) was observed in all but three of these CD3-positive samples. Such an incomplete T-cell phenotype always correlated to the presence of a monoclonal process as revealed by genotypic analysis. DNA analysis was the only way to demonstrate clonality in other samples with either a polymorphous (partial involvement, pseudolymphoma, angioimmunoblastic lymphodenopathy [AILD]) or an undifferentiated (large cell anaplastic) phenotype. It is concluded that although in the majority of cases immunophenotyping alone provides criteria adequate for the diagnosis of lymphoid malignancy, in some, particularly polymorphous or large cell anaplastic processes, genetic probe analysis was additionally discriminative.

Antigens, Differentiation↗
PubMed1986

T-cell lymphoma revealed by a peripheral neuropathy. A report of two cases with an immunohistologic study on lymph node and nerve biopsies.

In two patients a peripheral neuropathy was the presenting symptom of a noncutaneous peripheral T-cell lymphoma. In the first patient, the neuropathy had a relapsing and remitting course, the symptoms improved under corticosteroid therapy. The second patient suffered from a relentless neuropathy. In both cases the lymphoma infiltrated the peroneal nerve with an angiocentric and perivascular pattern resembling that observed in central nervous system lymphomas. The characterization of T-cell subsets in the lymph node showed cells with the helper/inducer and suppressor/cytotoxic phenotype in the first case and a predominance of cells with the helper/inducer phenotype in the second case. In the nerve, lymphocytes beard the helper/inducer phenotype antigen. A typical paraneoplastic vasculitis of nerve showed clearly different immunologic features.

Adult↗
PubMed1975

Iophendylate cisternography in diagnosis of cerebellopontine angle tumors. Report of 60 cases.

60 cases of bilateral cerebellopontine angle pantopaque cisternography done between May, 1972, and April, 1974, are reported. Of these, 9 showed a unilateral acoustic neurinoma of different sizes, 1 showed a bilateral acoustic neurinoma all confirmed by operation. Technical details and advantages of the procedure are discussed. There were no complications related to the procedure.

Adult↗
PubMedDate not supplied

Growth of a leguminous tree (Centrolobium tomentosum Guill. ex Benth.) inoculated with Rhizobium and mycorrhizal fungi.

Leguminous trees are being suggested for revegetation programs due to their ability to develop associations with rhizobia and mycorrhizal fungi. The growth of a native species of the Tropical Atlantic Forest, Centrolobium tomentosum, was evaluated in a native forest soil and in a Eucalyptus forest soil under different treatments of inoculation. C. tomentosum produced more biomass under nursery conditions after inoculation with Rhizobium BHICB-Ab1 associated with arbuscular mycorrhizal (AM). This treatment improved shoot and root growth and nodule weight under forest soil condition, while in eucalyptus soil only shoot biomass and nodule weight were significantly modified. In another experiment, using forest soil, height and stem diameter were also increased by dual inoculation procedures. The height and diameter growth promoting effect was observed when BHICB-Ab1 was used as inoculant associated with AM, but not with BHICB-Ab1 alone. In contrast, plants inoculated with BHICB-Ab3 alone were similar in height and diameter growth, to those which were inoculated with BHICB-Ab3 associated with AM. These results suggest that benefits of dual inoculation depend on triparty symbiosis and especially on the choice of Rhizobium strain.

Biomass↗