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Biomedical subjects

A Eva

Publications and source records attributed to A Eva.

48 records · Page 3Linked to original sources
PubMed1982

Differential expression of the amv gene in human hematopoietic cells.

Total cellular RNAs from a variety of fresh and culture-derived human hematopoietic neoplastic cell types at various stages of differentiation and human sarcoma, carcinoma, melanoma, and glioblastoma cell lines were enriched for poly(A)- containing sequences, fractionated by gel electrophoresis, and blot hybridized to a cloned DNA probe containing the transforming sequences (v-amv) of avian myeloblastosis virus (AMV), a virus known to cause myeloid leukemias in chickens. Expression of RNA sequences homologous to AMV was detected in all immature myeloid and lymphoid T cells in addition to the single erythroid cell line examined, but not in mature T cells or in B cells, including lymphoblast cell lines derived from patients with Burkitt lymphoma. In addition, induction of the cell line HL60, a promyelocytic leukemia line, to differentiate with dimethyl sulfoxide or retinoic acid resulted in a reduction of the level of expression of the human cellular gene c-amv homologous to v-amv. There was no detectable c-amv mRNA in any of the solid tumor cell lines examined. Thus, expression of the human c-amv gene could be correlated with the stage of differentiation of different hematopoietic cell types determined by morphologic and marker studies. Expression of c-amv could not be correlated with the extent of methylation in HL60 and in HL60 induced to differentiate with dimethyl sulfoxide.

Carcinoma↗
PubMed1982

Expression of cellular homologues of retroviral onc genes in human hematopoietic cells.

Total cellular poly(A)-enriched RNA from a variety of fresh human leukemic blood cells and hematopoietic cell lines was analyzed for homology with molecularly cloned DNA probes containing the onc sequence of Abelson murine leukemia virus (Ab-MuLV), Harvey murine sarcoma virus (Ha-MuSV), simian sarcoma virus (SSV), and avian myelocytomatosis virus strain MC29. Results with the fresh blood cells paralleled those obtained with the cell lines. With Ab-MuLV and Ha-MuSV, multiple RNA bands were visualized in all cell types examined without significant variation in the relative intensities of the bands. When SSV was used as the probe, expression of related onc sequences was absent in all of the hematopoietic cell types examined except for one neoplastic T-cell line (HUT 102), which produces the human T-cell leukemia (lymphoma) retrovirus HTLV. In this cell line, a single band (4.2 kilobases) was observed. With MC29 as the probe, a single band of 2.7 kilobases was visualized in all cell types examined with only a 10 to 2-fold variation in intensity of hybridization. An exception was the promyelocytic cell line, HL60, which expressed approximately 10-fold more MC29-related onc sequences. With induction of differentiation of HL60 with either dimethyl sulfoxide or retinoic acid, a marked diminution in the amount of the MC29-related, but not the Ab-MuLV-related, onc message was observed.

B-Lymphocytes↗
PubMed1981

Microsystem to evaluate the incorporation of 3H-uridine in macrophage RNA.

A method is described for the evaluation of the total 3H-uridine incorporated by macrophages in vitro into trichloroacetic acid (TCA)-precipitable material. The technique is based upon solubilization of the macrophage monolayers by guanidine-HCl, followed by TCA precipitation. The recovery of RNA into the precipitate and the reproducibility of the results were strictly dependent on the use of filtered reagents and on incubation of the TCA precipitate for 2 or more hours at 4 degree C before harvesting. Treatment with quanidine-HCl did not affect the recovery of labeled RNA. Moreover, we observed that radioactive precipitate had the characteristics of RNA, since its recovery was sensitive to the addition of unlabeled uridine in the culture medium and to the treatment of the macrophages with inhibitors of RNA synthesis, but not of protein synthesis. Tritiated uridine incorporation in microcultures of macrophages can be assessed with this technique, by processing the cells directly in the wells. The main advantages of this procedure are: 1) the radioactivity can be measured by semiautomatic cell harvesters, 2) a small number of macrophages are required, and 3) many samples can be processed simultaneously. Overall, the technique is simple, rapid, and could be successfully adapted to study other metabolic pathways.

Animals↗
PubMed1980

Suppression of T-cell mediated lymphokine production but not cytotoxic activity by macrophages.

We directly compared the effects of macrophages from infiltrating MSV-induced regressing tumors (T-M0) or from the peritoneal cavity of mice previously injected with light mineral oil (LMO-M0) on two functions of alloimmune spleen cells (ISC), the cytotoxic activity and production of a lymphokine, macrophage inhibitory factor (MIF). Addition of T-M0 or LMO-M0 to ISC did not inhibit their cytotoxicity. In contrast, T-M0, but not LMO-M0, mixed with ISC inhibited their ability to produce MIF. We propose that the differential sensitivity of the two immune functions to the macrophage-dependent suppressor activity is due to the ability to M0 to inhibit lymphocyte protein synthesis, with MIF production, but not T cell killing, requiring active protein synthesis.

Animals↗
PubMed1980

A microsystem to evaluate the synthesis of [3H]leucine labeled proteins by macrophages.

A method is described for evaluating protein synthesis by adherent M phi by measuring the incorporation of [3H]leucine into TCA precipitable material. By using guanidine-HCl it was possible to remove completely the radiolabeled proteins from the adherent cells that were cultured in microwells, and retain TCA precipitable material. This procedure enabled us to harvest the TCA precipitable proteins with a semiautomatic cell harvester. The guanidine-HCl treatment did not affect the recovery of the radioactive proteins and did not alter the sensitivity of the assay. This method is very simple and rapid and, since it is suitable for processing microcultures, permits detailed studies on the biology of small numbers of M phi.

Amino Acids↗
PubMed1979

Trichomonas vaginalis resistance to Mengo virus infection.

We have investigated the susceptibility of Trichomonas vaginalis to Mengo virus infection by comparing the outcome of Mengo virus or purified Mengo virus RNA infection in T. vaginalis and in CCL-1 mouse fibroblasts. While the adsorption and entry of Mengo virus into T. vaginalis occurred in the same manner as in fibroblasts, the uncoating was much slower. In addition, Mengo virus infection of T. vaginalis displayed no eclipse nor any subsequent production of infectious virus. Purified RNA failed to initiate productive infection in T. vaginalis, whereas it provoked viral replication in the fibroblast controls. It was shown by assessment of protein synthesis in T. vaginalis and mouse fibroblasts cell-free systems that the protozoan ribosomes were able to translate endogenous mRNA and poly-U, but not viral RNA.

Animals↗
PubMedDate not supplied

Isolation of a new human oncogene from a diffuse B-cell lymphoma.

Utilizing DNA transfection analysis with the continuous NIH 3T3 cell line as assay cell, we and other have observed that as many as 10-50% of human haematopoietic tumours contain oncogenes, the vast majority of which are members of the ras proto-oncogene family. In addition, Cooper and co-workers have reported the detection and isolation of specific oncogenes, B-lym and T-lym, which appear to be activated in human and rodent tumours of certain B and T lymphoid cells, respectively. In surveying human haematopoietic malignancies, we observed that DNA of a primary human diffuse B-cell lymphoma induced an unusual transformed focus on transfection of NIH 3T3 cells. Here, we report the molecular cloning and physical characterization of this human oncogene, whose transforming activity was shown to reside within a human DNA sequence of 45 kilobases (kb) cloned in a cosmid vector. Its properties distinguish it from previously reported retroviral or nonretroviral oncogenes.

Animals↗
PubMedDate not supplied

Preferential expression of the dbl proto-oncogene in some neuroectodermal tumors.

The dbl oncogene belongs to a unique class of human transforming genes. The dbl proto-oncogene is activated by substitution of the 5' portion of the gene with an unrelated human sequence. The proto-oncogene product is distributed between the soluble and membrane fractions of the cytoplasm and its function remains still unknown. In order to understand the biological role of dbl in human malignancies or during cell differentiation we have investigated the expression of the dbl oncogene in a wide number of human tumors of different embryological derivation. We found that dbl is preferentially expressed in a few neoplastic histiotypes of neuroectodermal origin. The transcript size of 5.3 Kb strongly suggests that the gene is not truncated in these tumors. These data, together with the information that the proto-oncogene has been found expressed in normal brain and adrenal medulla, indicate that dbl expression may be involved in cell differentiation of some tissues of neuroectodermic origin.

Gene Expression Regulation, Neoplastic↗