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Biomedical subjects

E Muñoz

Publications and source records attributed to E Muñoz.

At least 163 records · Page 9Linked to original sources
PubMed1992

Modifications of "A cells" in the development of experimentally induced pancreatic ductal adenocarcinoma: an ultrastructural and immunohistochemical study.

In the hamster-BOP model, modifications occur in the endocrine portion of the pancreas during the induction of well-differentiated ductal carcinomas. In the present work, using immunohistochemical techniques it was possible to observe that the A cells in preserved islets and in the initial phase of the carcinogenic process were localized in the peripheral part of the islets. In animals with tumours, A cells were found to form part of the tumour glands and/or the tumoral stroma; this localization was seen to depend on the developmental phase of the tumour. A focal dispersion of A cells was observed in the animals with ductal carcinoma.

Adenocarcinoma↗
PubMed1991

Captopril does not scavenge superoxide: captopril prevents O2-. production by chelating copper.

The purpose of this study was to use a direct method, that of electron spin resonance spectroscopy, to evaluate the ability of captopril, an angiotensin-converting enzyme inhibitor, to prevent the superoxide-mediated formation of phenyl radicals. Results indicate that, under certain conditions, captopril is a potent inhibitor of the generation of phenyl radicals, produced by the autoxidation of phenylhydrazine. The inhibitory effect of captopril, however, was better understood as a direct interaction of the drug with the metals that catalyze the autoxidation process rather than as a reaction of captopril with the free radicals generated. This last conclusion was supported by the finding that captopril was not able to inhibit the superoxide anion-mediated reduction of nitroblue tetrazolium.

Captopril↗
PubMed1991

Production of IL-1 alpha by activated Th type 2 cells. Its role as an autocrine growth factor.

Autocrine growth of Th type 2 cells has been reported to be mediated by the lymphokine IL-4. In this report we present evidence that in addition to IL-4 Th2 cells also produce IL-1 alpha in its active form in the absence of APC. We have found that this cytokine is an autocrine growth factor, because proliferation of Th2 cells in response to several stimuli is inhibited by anti-IL-1 alpha or anti-IL-1R mAb, or by an IL-1 alpha antisense oligodeoxynucleotide. However, Th1 cells do not produce this cytokine. We have investigated the role of endogenous IL-1 alpha on the induction of c-myc and c-myb, two protooncogenes involved in T cell activation. Here we show that endogenous IL-1 alpha is involved in the activation of both protooncogenes. Our results suggest that a possible function of IL-1 alpha, and perhaps other growth factors, might be to sustain or amplify the initial second messengers derived through the TCR. The possible implications of this finding with respect to interactions between T cell subsets and B cells or macrophages are discussed.

Antibodies, Monoclonal↗
PubMed1991

Superinduction of IL-2 gene transcription in the presence of cycloheximide.

Lymphokine production is regulated both at the transcriptional and the posttranscriptional level. To date, it has been shown that the protein synthesis inhibitor cycloheximide (CHX) up-regulates IL-2 expression in T cells by stabilizing its mRNA. In this report we have examined the effect of CHX on IL-2 at the transcriptional level. We have found that CHX has a positive regulatory function in IL-2 transcription, which is dependent on prior activation of this gene. This is not due to posttranslational conversion of inactive NFkB into its active form by CHX, because a clustered mutation in the kB-like sequence in the IL-2 enhancer that abrogates NFkB binding does not affect the up-regulation of IL-2 transcription. These results favor the hypothesis that, in addition to positive factors, negative elements regulate IL-2 transcription. Furthermore, we have tested the effect of CHX on IL-4 and granulocyte-macrophage-CSF transcription of both lymphokines. These results suggest that transcriptional up-regulation by CHX may be specific for IL-2 with respect to lymphokine expression.

Cells, Cultured↗
PubMed1991

Tyrosine protein phosphorylation is required for protein kinase C-mediated proliferation in T cells.

We have studied the role of tyrosine kinase in PMA-stimulated T cells. Protein kinase C (PKC)-mediated D10A cell proliferation is inhibited by the specific inhibitor of tyrosine kinase, tyrphostin. This inhibitor selectively blocks the mRNA expression of the proto-oncogene c-myc in response to the phorbol ester, PMA. On the other hand, the same doses of this inhibitor do not affect the mRNA expression of the proto-oncogene c-fos in PMA-stimulated D10A cells. Phorbol esters induce in this T cell line the tyrosine phosphorylation of a unique protein of 42 kDa and the enzyme PKC is required for this activity.

Blotting, Northern↗
PubMed1991

IL-1 signal transduction pathways. I. Two functional IL-1 receptors are expressed in T cells.

We have recently characterized a subline of the Th2 cell line D10.G4.1, D10A, which responds to exogenous IL-1 in the absence of cofactors. In this cell line IL-1 activates two distinct transmission signal pathways, one leading to increased levels of intracellular cAMP, and the other to the phosphorylation of an 80-kDa substrate of protein kinase C (PKC). To determine whether both pathways are activated upon occupancy of a single IL-1R, we used a mAb, M15, which blocks binding of IL-1 to the 80-kDa IL-1R, known to be expressed in Th2 cells. Whereas M15 was able to inhibit the accumulation of cAMP induced by IL-1, it had no effect on the IL-1-induced phosphorylation of the 80-kDa substrate of PKC or the c-fos mRNA expression. In addition, we show that IL-1 induces the expression of the two proto-oncogenes c-myb and c-myc through the 80-kDa IL-1R, and that this induction is PKC independent. The proliferation of D10A cells in response to IL-1 is blocked by M15, but is unaffected by H-7, a potent inhibitor of PKC. These results indicate that the IL-1-induced proliferation of D10A cells is independent of PKC. In addition, IL-1 induces c-fos mRNA expression in thymocytes but not in EL-4 cells.

Animals↗
PubMed1991

Study of the interaction of cadmium with membrane-bound succinate dehydrogenase.

Cadmium ions inhibit membrane-bound succinate dehydrogenase with a second-order rate constant of 10.42 mM-1 s-1 at pH 7.35 and 25 degrees C. Succinate and malonate protect the enzyme against cadmium ion inhibition. The protection pattern exerted by succinate and malonate suggests that the group modified by cadmium is located at the active site. The pH curve of inactivation by Cd2+ indicates the involvement of an amino acid residue with pKa of 7.23.

Animals↗
PubMed1991

Raynaud's phenomenon with digital necrosis as the first manifestation of undifferentiated connective tissue syndrome.

A patient with severe Raynaud's phenomenon (RP) associated with the presence of antibodies against extractable nuclear antigen (ribonucleoprotein) in the context of undifferentiated connective tissue syndrome is presented. The rapid course of digital necrosis in her case resulted in the surgical amputation of 9 of her fingers. We conclude that massive digital necrosis accompanied by severe RP could constitute the first manifestation of a connective tissue disease.

Adult↗
PubMed1991

Ultrastructural study of the initial phases of pancreatic carcinoma induced by BOP in the Syrian golden hamster.

A serial study was carried out on the lesions induced by N-nitroso-bis(2-oxopropyl)amine (BOP) in the Syrian golden hamster until the appearance of pancreatic ductal carcinomas. During the initial phase, first findings were cytolysis of acinar cells close to blood vessels and other cells, together with a loss of zymogen granules from the cytoplasm, and an increase in the diameters of the acinar lumens. After week 11 a proliferation of ductule-like cells was observed. We consider that a minimum proliferation of cells at the acinus-ductule junction would give rise to pseudoductules composed of remains of acinar cells together with ductule-like cells.

Animals↗
PubMed1991

Chronic gastritis associated with Helicobacter pylori. Correlation between histological and bacteriological findings.

Biopsy specimens of gastric and duodenal mucosa from 326 patients were examined bacteriologically and histologically to determine the correlation between chronic gastritis and H. pylori colonization. H. pylori was identified in 111 (66.5%) patients with evidence of chronic gastritis and in 97 (82.2%) individuals who had gastritis associated with other pathology (gastric o duodenal ulcer, carcinoma o bulboduodenitis). The spiral bacteria was found more frequently in specimens with chronic superficial gastritis (88/107) and no significant difference was observed between the grade of activity of gastritis and H. pylori colonization. Giemsa stain was the most suitable method for detecting H. pylori in histological sections. By electron microscopy the microorganism was seen on the surface of the gastric mucosa, beneath the mucous layer, and more occasionally in intercellular junctions and the gastric pit.

Adolescent↗
PubMed1991

Hospital costs, resource characteristics, and the dynamics of death for general surgery patients.

The world of health care finance and quality assessment is undergoing rapid change. We analyzed a large group of general surgical patients who died regarding hospital resource consumption. General surgical patients who died generated much greater resource consumption than survivors per DRG; increasing hospital LOS for general surgical patients who died was associated with increasing financial risk under DRGs. Patients who died after non-emergency admission generated similar financial risk to patients who died after emergency admission. General surgical patients who died who were referred from another clinical service generated, on average, similar resource consumption to non-referred patients who died. The results of this study support those of previous studies suggesting the payment inequities of DRGs for general surgical patients who die and suggest that attention should be directed at improving the DRG hospital payment system for these patients.

Aged↗
PubMed1990

Cholera toxin discriminates between T helper 1 and 2 cells in T cell receptor-mediated activation: role of cAMP in T cell proliferation.

CD4+ T helper (Th) clones can be divided into interleukin 2 (IL-2)-secreting Th1 and IL-4-secreting Th2 cells. We show in the present report that these two Th subsets have different activation requirements for lymphokine production and proliferation: namely, cholera toxin (CT) as well as forskolin inhibit T cell receptor (TCR)-mediated IL-2 production and proliferation in Th1 cells, while the same reagents fail to block IL-4 production and proliferation in Th2 cells. In addition, CT and forskolin differentially influence the proto-oncogene mRNA expression in Th1 vs. Th2 cells after stimulation with Con A. Since both reagents lead to elevated levels of intracellular cAMP, it is likely that Th1 and Th2 cells differ in their sensitivity to an increase in cAMP. Our results indicate that the two Th subsets use different transmission signal pathways upon TCR-mediated activation.

Animals↗
PubMed1990

IL-1 activates two separate signal transduction pathways in T helper type II cells.

We have investigated the signal transduction pathways mediated by IL-1 in the Th 2 cell line D10.A, and we have made the following findings. Interaction of IL-1 with its receptor leads to the translocation of protein kinase C (PKC) from the cytosol to the membrane, phosphorylation of the 80-kDa protein that is substrate for PKC, as well as an increase in the level of cAMP. In addition, IL-1 induced IL-5 mRNA expression in these cells. We have established that the IL-5 gene is activated in D10.A cells in response to either phorbol esters or 8-Br cAMP, and that the two agents act as cofactors. IL-1 is able to synergize with phorbol esters and is additive with 8-Br cAMP for IL-5 mRNA expression. There are two possibilities to explain these results: 1) D10.A cells express two types of functional IL-1R, each linked to an independent signal transduction pathway; or 2) these cells have only one kind of IL-1R which, upon ligand interaction, mediates the activation of both the PKC and the adenylate cyclase pathway.

Animals↗
PubMed1990

Hospital readmissions, otolaryngology, and the diagnosis related group hospital payment system.

An analysis of otolaryngologic patients requiring readmission was conducted at our institution during a 4-year period to determine the number of readmissions per patient and the time between discharge and hospital readmission. Readmitted otolaryngologic patients were found to have had greater hospital resource utilization, financial risk under diagnosis-related group payment, and mortality, compared with those patients not readmitted to our facility. For patients readmitted to otolaryngologic services (21.2% of total otolaryngologic patients), 20.4% of the readmissions occurred within 30 days of hospital discharge. Of these, 39.3% required one hospital readmission, 16.3% required two readmissions, and 46.4% of the patients called for three or more hospital admissions. Clinical factors were identified that resulted in a greater incidence of otolaryngologic readmission. Otolaryngologic patients readmitted to other clinical services were also studied. This analysis loads to the conclusion that inequities exist within the diagnosis related group hospital payment system vis-à-vis otolaryngologic readmissions. The results of these data also demonstrate leverage points in which we will be able to focus outpatient services for otolaryngologic patients requiring readmission and potentially decrease inpatient hospital expenditures in the days ahead.

Academic Medical Centers↗
PubMed1990

Neutrophilic eccrine hidradenitis in two neutropenic patients.

Neutrophilic eccrine hidradenitis is an uncommon, self-limited dermatosis with a variable clinical presentation. It seems to be due to chemotherapeutic drugs in most cases. Necrosis of the eccrine gland associated with a neutrophilic infiltrate is the histologic hallmark of this disease. We report two additional cases in neutropenic patients with acute myelogenous leukemia in which there was a striking lack of neutrophil infiltration. A new term, drug-associated eccrine hidradenitis, is suggested.

Adolescent↗
PubMed1990

Regulation of IL-4 lymphokine gene expression and cellular proliferation in murine T helper type II cells.

Activation of T cells results in the production of lymphokines and cellular proliferation. Protein kinase C (PKC) plays a key role in this process. It has been shown that this enzyme is essential to elicit a response to Con A or specific antigen in CD4+ T helper type 1 (Th 1) cells that secrete IL-2. We have now explored the signal transduction pathway that leads to transcription of the IL-4 gene and proliferation in murine CD4+ T helper type 2 (Th 2) cells. Surprisingly, we have found in two independently derived Th 2 clones that neither cellular proliferation nor IL-4 lymphokine production is affected by blocking or depletion of PKC. This differential mechanism of signal transmission leading to cellular activation implies a new distinction between murine Th 1 and Th 2 cells.

Animals↗