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J Toledo

Publications and source records attributed to J Toledo.

At least 19 recordsLinked to original sources
PubMed1995

The plasmacytoma growth inhibitor restrictin-P is an antagonist of interleukin 6 and interleukin 11. Identification as a stroma-derived activin A.

A stromal protein, designated restrictin-P, that specifically kills plasma-like cells was purified to homogeneity and shown to be identical with activin A. The specificity to plasma-like cells stemmed from the ability of restrictin-P/activin A to competitively antagonize the proliferation-inducing effects of interleukin (IL) 6 and IL-11. Restrictin-P further interfered with the IL-6-induced secretion of acute phase proteins by HepG2 human hepatoma cells and with the IL-6-mediated differentiation of M1 myeloblasts. A competition binding assay indicated that restrictin-P did not interfere with the binding of IL-6 to its receptor on plasma-like cells, suggesting that it may act by intervening in the signal transduction pathway of the growth factor. Indeed, concomitant addition of restrictin-P and IL-6 to cytokine-deprived B9 hybridoma cells was followed by sustained overexpression of junB gene until cell death occurred, while IL-6 alone caused a transient increase only. This altered response to IL-6 stimulation was accompanied by a moderate increase in STAT protein activation. Thus, in this study, we identified the plasmacytoma growth inhibitor, restrictin-P, as being activin A of stromal origin. It is shown that activin A is an antagonist of IL-6-induced functions and that it modifies the IL-6 signaling pattern.

Activins↗
PubMed1992

Dynamic changes in cytokine secretion by stromal cells during prolonged maintenance under protein-free conditions.

Stromal cells of bone marrow origin produce a variety of known cytokines and some factors exhibiting apparently new biological activities. Several of these were identified by the study of cell to cell interactions and were not found in detectable amounts in media conditioned by the cells. We describe here a culture system that enables the release of stromal cytokines into medium free of any added proteins and supplemented with peptides from casein hydrolysate (0.1%). The absence of serum proteins allows extensive concentration and monitoring of activities that are otherwise undetectable. Stromal cells of the MBA-2.1 clonal cell line were seeded in a stationary bed reactor packed with a carrier of non-woven fabric matrix. After a proliferation phase with serum containing medium, the cells were maintained for over 10 months in protein-free medium. Throughout this extended incubation in the absence of serum or serum replacing proteins, stromal cells retained their viability and continuously released transforming growth factor-beta (TGF-beta), macrophage-colony stimulating factor (M-CSF) and restrictin-P, a cytotoxic factor that specifically arrested the growth of plasmacytoma cells. In addition, interleukin-6 (IL-6) was first undetectable, and later in culture its titer reached a maximum of 180,000 international units (IU)/ml. Concomitantly, the production of restrictin-P diminished and reached its lowest levels at the end of 10 months. The results may imply a possible causal relationship between the expression of IL-6 and restrictin-P, since no similarly significant changes were observed in the titers of M-CSF and TGF-beta. This novel bioreactor system may be adaptable for efficient production of different cytokines under absolute serum-free conditions.

Animals↗
PubMed1991

Effects of an eicosapentaenoic and docosahexaenoic acid concentrate on a human lung carcinoma grown in nude mice.

The effects of the n-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), on the growth of a human lung mucoepidermoid carcinoma (HLMC) in athymic mice were studied. The mice were divided into three groups which were given either a control chow diet (C), a chow diet supplemented with EPA/DHA (P) (25 or 50 mg of free n-3 fatty acids/g of pellet/day), or chow diet supplemented with palmitic acid (S) (isocaloric with P). Two independent experimental schedules were followed: i) host mice bearing either tumors that were allowed to reach 4000 mm3, or only 35 mm3, were fed C, P or S for 21 or 41 days; ii) animals were fed C, P and S for 9 days before tumor implant and were maintained on these diets throughout tumor growth. Food consumption, mouse weight and liver/body weight ratio showed no significant differences between supplemented diets and chow. Tumor growth was markedly inhibited (45%) in both experiments by the EPA/DHA supplemented diet. In Experiment 2, only 60% of mice fed diet P had tumors. The fatty acid composition of neutral and polar lipids of host liver and tumor reflected the dietary intake of n-3 fatty acids; the content of arachidonic acid was reduced by 50%, and EPA/DHA was increased 3- to 5-fold. Tumor prostaglandin E2 levels were reduced 7.4-fold in the P group. The reduced PGE2 content may be a factor in tumor growth inhibition.

Animals↗
PubMed1990

Detection of interleukin-3 in the serum of mice infected with Mycobacterium lepraemurium.

Infection of mice by Mycobacterium lepraemurium is accompanied by ablation of erythropoiesis in the bone marrow and gross enlargement of the spleen. This, together with increased monocytopoiesis and the earlier demonstration of macrophage colony-stimulating factor in the serum of infected mice, suggested the activity of additional cytokines. Eight weeks after infection of mice by M. lepraemurium, interleukin-3 (IL-3) activity was demonstrated in the serum (titer, 1:3200). The serum titer of IL-3 activity was maximal after 13 weeks (greater than 1:6400) and was slightly reduced after 18 weeks (1:6400). That the IL-3 activity detected in the serum of the M. lepraemurium-infected mice reflected the presence of IL-3 itself was confirmed by a neutralization assay using anti-murine IL-3 antibodies; IL-3 activity in the serum of mice 13 weeks after infection was completely abolished by the anti-IL-3 antibodies. Finally, a 1-kb signal of IL-3 RNA was detected in the spleens of M. lepraemurium-infected mice 13 weeks after infection.

Animals↗
PubMed1989

Multilineage hemopoiesis induced by cloned stromal cells.

Long-term hemopoiesis in culture depends upon the presence of an adherent layer composed of a variety of stromal cells. A subtype of endothelial-adipocytes from the bone marrow stroma (clone 14F1.1) was previously shown to induce long-term myelopoiesis and renewal of pluripotent stem cells. One of a series of stromal cell lines and clones from mouse thymus stroma (STAC-1.2) has now been found to support long-term hemopoiesis. These marrow- and thymus-derived stromal cell clones also have lymphopoietic activities: precursor T cells, or pre-B cells accumulated in co-cultures of thymus cells and the stromal clones, as indicated by cell surface markers, T cell receptor and immunoglobulin gene rearrangements. The predominance of a cell type in these cultures depended upon the serum used to supplement the medium. Recombinant interleukin 2 (IL-2) and the 14F1.1 clone synergistically promoted the proliferation of thymocytes, while a thymus hormone, THF-gamma 2, shifted the population to a relatively mature phenotype. It is proposed that one major function of stromal cells, whether from the bone marrow or thymus, is to restrain the maturation flow and preferentially support the accumulation of cells at early differentiation stages.

Animals↗
PubMed1989

Age related changes in hemopoietic capacity of bone marrow cells.

The effect of aging on the hemopoietic capacity of bone marrow (BM) cells was investigated. No difference was found in the incidence of colony forming units-spleen (CFU-S) and granulocyte-macrophage colony forming cells (GM-CFC) present in the BM of young (2-4 months) or old (24-30 months) mice. However, increased proliferation (x3) of the old BM cells was observed when cultured in the presence of L-cell conditioned medium. The cells were also cultivated over an adherent layer of a BM stroma cell line (14F1.1, endothelial-adipocytes) and the non-adherent cells removed and tested weekly. Cells originating from the old BM proliferated to a greater extent and produced more GM-CFC than those from the young. Differentiation into T-cells after colonizing fetal thymus explants was also measured and found to be reduced in both groups, though to a greater extent in the old. Thus, under the present experimental conditions, myeloid progenitors in the old BM manifest a more pronounced self renewal and differentiation capacity than the young while for the T-cell progenitors the situation is reversed.

Aging↗
PubMed1989

Conservative and bronchoplastic resection for bronchial carcinoid tumours.

From January 1974 to December 1987, 45 cases of bronchial carcinoid were surgically managed at our Unit, 44 of which were evaluated. All patients but 2 were submitted to fiberoptic bronchoscopy prior to surgery. A standard resection was performed in 19 cases (13 lobectomies, 4 bilobectomies and 2 pneumonectomies). In 11 cases, pulmonary resection was complemented with a bronchoplastic technique (6 lobectomies, 2 bilobectomies, 2 pneumonectomies, 1 segmentectomy). Four cases were managed by minimal resections (2 segmental, 1 wedge, 1 enucleation) and 8 others by bronchotomy and local resection without the sacrifice of lung tissue. There were two major postoperative complications and no operative mortality. Mean follow-up has been 53 months and no local bronchial recurrence has been observed although 2 patients have developed distant metastases, with 1 death. The absence of local recurrence in a series in which more than 50% of patients were treated with some form of conservative surgery seems to indicate that resection of lung tissue should be avoided whenever possible.

Adult↗
PubMed1989

In vitro effect of eicosapentaenoic and docosahexaenoic acids on prostaglandin E2 synthesis in a human lung carcinoma.

The capacity to synthesize both prostaglandins E1 (PGE1) and E2 (PGE2) has been determined in human lung mucoepidermoid carcinoma homogenates when [14C]-fatty acid precursors were added to the incubation medium. Only 10% of the total radioactivity recovered in PGs was found in PGF1 alpha and PGF2 alpha. The experiments were principally focused to inhibit the PGE2 synthesis either with pure eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids or with mixtures of both n-3 fatty acids obtained from fish oil. The results demonstrated that significant inhibitions were found when using 25 microM or a higher concentration of pure EPA or DHA in the incubation medium; however, 5 microM of mixtures of different EPA/DHA ratio caused the same inhibition. The results suggest that EPA and DHA, when added together, may enforce their inhibitory effect on PGE2 synthesis.

Animals↗
PubMed1988

Serum cholesterol and coronary heart disease: Auckland general practitioners' attitudes and practices in 1986.

The relationship between elevated serum cholesterol and coronary heart disease, is now generally accepted as being causal. To examine current attitudes and practices regarding the treatment of high serum cholesterol, questionnaires were sent to a randomly selected sample of general practitioners in the Takapuna health district during 1986. The response rate among the 92 doctors in general practice at the time of the study was 80%. The majority of general practitioners (82.5%) believed that there was a casual relationship between high serum cholesterol and coronary heart disease and that reducing levels would help prevent coronary heart disease. Almost all general practitioners (96%) were screening some groups of patients for high serum cholesterol, with most screening those with symptomatic coronary heart disease or associated risk factors, and 15% screening all patients. Although almost 90% of general practitioners had patients on diet therapy and one third had patients on drug treatment, there was wide variation in attitudes regarding the serum cholesterol levels meriting dietary or drug treatment. This suggests that there is still considerable confusion as to when and how to treat high cholesterol levels and that specific national guidelines for the detection and management of high serum cholesterol are required as part of a comprehensive programme to prevent coronary heart disease.

Adult↗
PubMed1986

Differentiation stage and lineage-specific inhibitor from the stroma of mouse bone marrow that restricts lymphoma cell growth.

We have examined the mechanism by which stromal cells from the microenvironment of the bone marrow restricted the in vitro growth of certain hemopoietic tumors. A series of leukemia cell lines was used to monitor biological activities of stromal cell lines representing five distinct subtypes. Only an endothelial-like clone derived from mouse stroma (MBA-2.1) was consistently found to produce a cell-surface-associated glycoprotein that selectively inhibited the growth of plasmacytomas. The factor, designated leukemia cell inhibitory activity (LCIA), was not detected in anchorage-dependent cells of nonhemopoietic origin. Tumors of the lymphoid lineage and plasmacytomas in particular were the most sensitive to LCIA. Myeloid, macrophage, and erythroleukemia tumors were resistant to the factor, as were normal hemopoietic target cells including pluripotent stem cells, myeloid progenitor cells, and mitogen-stimulated spleen cells. Fractionation of trypsin-released proteins from MBA-2.1 cells by gel filtration and affinity binding to concanavalin A-Sepharose revealed two types of inhibitors; one was the specific leukemia cell inhibitor (i.e., LCIA); the other, present at a lower titer, was non-target-cell specific. The high sensitivity of plasmacytomas to LCIA versus the resistance of normal stem cells may be utilized for selective elimination of plasma cell tumors from bone marrow inocula.

Animals↗
PubMed1985

Cultured mouse marrow stromal cell lines. II. Distinct subtypes differing in morphology, collagen types, myelopoietic factors, and leukemic cell growth modulating activities.

A series of stromal cell lines were studied for their growth properties, electron microscopic morphology, cytochemical profile, collagen types, production of myelopoietic factors, and modulation of leukemic cell growth. Three cell types were identified in addition to the previously described macrophages (14M and 14M1) and preadipocytes (14F). MBA-1 cells were found to be fibroblasts by their ability to synthesize collagen types I and III, while the cell line MBA-13 shared properties in common with both fibroblasts and endothelial cells (collagen types I, III, IV, V). The third cell type, represented by the stromal cell line MBA-2, produced mainly collagen types IV and V and exhibited junctional complexes between adjacent cells. All of the cell lines tested produced and secreted a macrophage-colony-stimulating factor, CSF-1. MBA-2 and to a lesser extent, MBA-13, produced an additional activity resistant to anti-CSF-1 antiserum. Trypsin extraction of outer surface components from two clones of the MBA-2 cell line (MBA-2.1 and MBA-2.4) yielded high molecular weight factor(s) that specifically inhibited the growth of a plasmacytoma cell line (MPC-11). Such inhibitory activity was not detected in other stromal cell lines. It is possible that this variability in the nature of stromal cell lines represents corresponding diversity of cell types comprising the hematopoietic microenvironment in vivo.

Animals↗
PubMed1985

Acromegaly and bronchial carcinoid. Effect of removal of the latter.

A patient with a long-standing history of bronchial carcinoid and acromegaly was studied. There was pituitary enlargement with an intrasellar mass (brain computed tomography scan), high basal GH levels, and abnormal GH and other pituitary hormones response to oral glucose and a combined test (LHRH, TRH, insulin). After resection of the bronchial carcinoid, basal GH was normal, GH was normally suppressed during OGTT, pituitary function was within expected normal range, and there was regression of the pituitary tumor together with clinical improvement. These data suggest that the patient's acromegaly was secondary to pituitary stimulation due to the bronchial carcinoid.

Acromegaly↗
PubMed1985

Phenotypic heterogeneity among stromal cell lines from mouse bone marrow disclosed in their extracellular matrix composition and interactions with normal and leukemic cells.

Study of a series of stromal cell lines from mouse bone marrow (MBA) verified and extended their classification as phenotypically distinct subtypes. Production of extracellular matrix proteins was examined using specific antibodies. Fibronectin and laminin were detected in all of the cell lines tested, yet 14F1.1 adipocytes exhibited particularly prominent extracellular deposition. This cell line and MBA-13.2 cells were positive to both collagen types I and IV, whereas MBA-1 and MBA-2.1 were stained with anticollagen type I antibodies only. Coculture experiments revealed differences among the lines in their effects on normal myeloid cells and leukemic cell lines. In promoting the in vitro accumulation of myeloid progenitors (CFU-C), 14F1.1 cells surpassed the others. The MBA-2.1 cell line was particularly inhibitory to MPC-11 plasmacytoma and Friend erythroleukemia cells. However, the latter were refractory to other stromal cell lines, whereas MPC-11 cells were inhibited to various degrees by virtually all of the cell lines. Physical separation between the interacting cells reduced the inhibition in some but not all cases, and no inhibitory activity was detected in conditioned media. The MBA-13 stromal cells synergistically promoted the differentiation of dimethylsulfoxide (Me2SO)-induced Friend erythroleukemia. The latter cells themselves, at high concentrations, as well as some of the stromal cell lines and unrelated adherent cells, antagonized the Me2SO effect, revealing possible reversible stages in the Friend cell differentiation pathway.

Animals↗