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Biomedical subjects

D Carrasco

Publications and source records attributed to D Carrasco.

At least 55 records · Page 3Linked to original sources
PubMed1993

Expression of relB transcripts during lymphoid organ development: specific expression in dendritic antigen-presenting cells.

We have studied the expression of the relB gene during mouse development using in situ hybridization and immunocytochemical analysis. The results show that the expression of the relB gene is highly restricted to a subpopulation of cells that colonize the lymphoid tissues and that appear very late during the process of hematopoietic diversification. RNA transcripts of relB are very low or undetectable in early and late embryos. Low relB expression is observed in the thymus at late stages of embryogenesis but rapidly increases after birth. In adult lymphoid tissues, relB is detected in the medullary region of the thymus, the periarterial lymphatic sheaths of the spleen, and the deep cortex of the lymph nodes, which correspond to the regions where T cells of mature phenotype and interdigitating dendritic cells are present. Using double immunofluorescent labeling of thymic cell suspensions, we have identified the interdigitating dendritic cells as the target of RelB expression. These cells are part of a system of antigen-presenting cells that function in the induction of several immune responses, such as, tolerance, sensitization of MHC-restricted T cells, rejection of organ transplants and formation of T-dependent antibodies. Our observations indicate that RelB may play a particular role in the signal transduction pathway that regulate dendritic cell differentiation and its cellular responses.

Animals↗
PubMed1993

Expression of the nontransmembrane tyrosine phosphatase gene erp during mouse organogenesis.

We have studied the expression of the nontransmembrane tyrosine phosphatase gene erp during mouse development using in situ hybridization analysis. The results show that during the early postimplantational stages of development, erp expression is observed only in maternally derived decidual cells surrounding the developing embryo. At day 10.5, erp is weakly expressed in the embryo in the neural tube, hind gut, and other embryonic structures. However, in 12.5-day embryos, erp is present in most organs, with the highest expression restricted to the developing neural system. During later development, at day 17.5, the levels of erp decline in some neural structures but remain high in others, like the dorsal root ganglia. High levels of erp expression are maintained in several parts of adult brain, such as cortical layers, thalamus, hypothalamus, and hippocampus. High levels of erp transcripts are also observed in the cerebellar cortex, in the Purkinje cell layer, and in the granular cell layer. In all tissues analyzed, the expression of erp corresponds to regions undergoing terminal cell differentiation and/or regions where cell proliferation has declined.

Animals↗
PubMed1993

Developmental expression of the vav protooncogene.

We have examined the expression of the vav protooncogene during mouse embryogenesis using RNase protection assays, in situ hybridization, and immunocytochemical analysis. vav gene transcripts were first detected in E11.5 embryos in the blood-forming islands and megakaryocytes of the fetal liver. During diversification of hematopoietic activity in the embryo, vav gene expression became down-regulated in the liver and activated in thymus and spleen. In newborn animals, vav expression was also confined to hematopoietic tissues, with the exception of the ameloblastic cell layer at the latest stages of tooth morphogenesis. In the adult, vav transcripts were found in spleen, thymus, lymph nodes, and bone marrow, but not in liver. In spleen, vav transcripts were concentrated in the white pulp areas, whereas in the red pulp, the vav transcripts appeared to be primarily localized in the megakaryocytes. In thymus, vav expression was found to be more abundant in the cortical areas than in the medulla. In agreement with these observations, purified thymic lymphocytes showed heterogeneous immunoreactivity against the Vav protein, whereas splenic lymphocytes and bone marrow-derived cells displayed rather uniform levels of expression. These observations suggest that the vav protooncogene plays an important role in the signal transduction pathways that regulate the development and maintenance of the hematopoietic system.

Animals↗
PubMed1990

The incorporation of myo-inositol into phosphatidylinositol derivatives is stimulated during hormone-induced meiotic maturation of amphibian oocytes.

The incorporation of myo-[3H]inositol into phosphatidylinositol and its phosphorylated derivatives was studied by microinjection of the radioactive precursor into Xenopus laevis oocytes. Induction of meiotic maturation of the oocytes by treatment with either progesterone one or insulin resulted in a significant increase in the incorporation of myo-[3H]inositol into the phospholipid fraction. This increase occurred 3-6 h after hormonal treatment, a time coincident with the start of the breakdown of the nuclear envelope, and requires protein synthesis. The effect of progesterone and insulin contrasts with the effect of acetylcholine, which acts through a muscarinic receptor causing the activation of phospholipase C, since the latter effector causes an increase in myo-[3H]inositol incorporation, which is more rapid and does not require protein synthesis. These results suggest that the meiotic maturation process is connected with changes in inositol metabolism in the amphibian oocyte.

Acetylcholine↗
PubMed1989

Factors that regulate the activity of the phosphatidylinositol kinase present in oocyte membranes of Xenopus laevis.

1. Phosphatidylinositol kinase present in the membranes of Xenopus laevis oocytes was characterized. 2. The enzyme requires Mg2+ or Mn2+ at 10 mM and exogenous phosphatidylinositol (50 microM) increases the formation of phosphatidylinositol-4-phosphate. 3. The oocyte phosphatidylinositol kinase cannot use GTP as a phosphate donor but this compound inhibits competitively the utilization of ATP. 4. Addition of phosphatidylserine and phosphatidylinositol-4,5-bisphosphate stimulates the phosphorylation of phosphatidylinositol but 2,3-bisphosphoglycerate at 5 mM concentration is a strong inhibitor of the reaction.

1-Phosphatidylinositol 4-Kinase↗
PubMed1988

Diagnosis of malignant ascites. Comparison of ascitic fibronectin, cholesterol, and serum-ascites albumin difference.

The ascitic fluid concentrations of cholesterol and fibronectin and the serum-ascites albumin difference were compared with two conventional tests of ascitic fluid, total protein and LDH, in their diagnostic ability for detection of malignancy in ascitic samples from 69 patients with ascites: 54 with ascites due to liver disease and 15 whose ascites was caused by peritoneal metastases. Sixteen cirrhotic patients with superimposed hepatocellular carcinoma in whom ascites was of uncertain etiology were considered separately. The mean ascitic fluid total protein, LDH, cholesterol, and fibronectin values in the peritoneal metastases group were 3.70 +/- 1.20 g/dl, 247.26 +/- 148.14 units/liter, 109.06 +/- 29.85 mg/dl, and 91.57 +/- 41.52 micrograms/ml, respectively, and all were significantly higher than the corresponding values in the liver disease group (P less than 0.001), which were 1.37 +/- 0.59 g/dl, 75.40 +/- 110.70 units/liter, 23.75 +/- 11.22 mg/dl, and 31.86 +/- 10.51 micrograms/ml, respectively. Mean serum-ascites albumin difference in the peritoneal metastases group was 0.62 +/- 0.38 g/dl, which was significantly different from the corresponding value in the liver disease group (1.92 +/- 0.41 g/dl, P less than 0.001). Both ascitic cholesterol above 46 mg/dl and an ascitic fibronectin concentration greater than 50 micrograms/ml had high diagnostic accuracy (97%) for malignancy, being higher than that achieved using a serum-ascites albumin difference under 1.1 g/dl and an ascitic total protein above 2.5 g/dl, which had accuracies of 94% and 93%, respectively. Ascitic fluid LDH was the least reliable test. No differences in the ascitic fluid analysis were found between cirrhotic patients with and without hepatocellular carcinoma.(ABSTRACT TRUNCATED AT 250 WORDS)

Ascites↗
PubMed1988

Polylysine and polyamine stimulation of the phosphatidylinositol kinases of amphibian oocyte membranes.

Phosphatidylinositol kinase present in Xenopus laevis oocyte membranes catalyzes the formation of phosphatidylinositol 4-phosphate using phosphatidylinositol and ATP as substrates while the activity of a second enzyme, phosphatidylinositol-4-phosphate kinase, results in the synthesis of phosphatidylinositol 4,5-bisphosphate. Large (Mr greater than 20,000) homopolymers of L-lysine or L-ornithine can stimulate the activity of both of these enzymes by at least 2-fold at 10-20 microM concentrations. Under similar conditions poly-L-arginine fails to stimulate the reaction causing a partial inhibition. Smaller polylysine (25 lysines) or lysine-rich oligopeptides such as one corresponding to the last 14 amino acids of the carboxyl end of c-Ki-ras 2 protein produce appreciable stimulation of phosphatidylinositol but at concentrations of 300-500 microM. Spermine and spermidine at millimolar concentrations also stimulate exogenous phosphatidylinositol phosphorylation. The amino-glycoside antibiotic neomycin has a biphasic effect, stimulating the phosphatidylinositol kinase at concentrations below 0.5 mM and strongly inhibiting at higher concentrations. Polylysine also moderately stimulates the loss of radioactivity of phosphatidylinositol-4-[32P] phosphate observed in oocyte membranes. Polylysine and polyornithine do not change the apparent Km for ATP of the phosphatidylinositol kinase but increase the Vmax of the reaction.

1-Phosphatidylinositol 4-Kinase↗
PubMed1987

Casein kinase II is a major protein phosphorylating activity in the nuclei of Xenopus laevis oocytes.

The nuclei of Xenopus laevis oocytes contain kinases capable of phosphorylating endogenous and exogenous proteins using either ATP or GTP as phosphoryl donors. These enzymes are much more active with casein and phosvitin as substrates than with histones or protamines. The protein phosphorylating activity of oocyte nuclear extracts is not regulated by cyclic nucleotides, phorbol esters, calmodulin and calcium, or phospholipids. However, the casein phosphorylating activity can be greatly enhanced by the polyamines spermine or spermidine and drastically inhibited by heparin. Fractionation of the nuclear casein kinase activities by DEAE-Sephadex chromatography and glycerol gradient centrifugation indicate that the nuclei contain enzymes with the properties of casein kinases I and II as characterized in other species. Oocyte casein kinase I (Mr 37,000) is specific for ATP as phosphoryl donor, is only slightly inhibited by 10 micrograms/ml heparin, and is not significantly stimulated by polyamines. Casein kinase II (Mr 135,000) can use both ATP and GTP as substrates, and is very sensitive to heparin inhibition and polyamine stimulation. The fact that low concentrations of heparin (10 micrograms/ml) can inhibit a large percentage of the endogenous phosphorylation of nuclear extracts or of whole nuclei indicates that casein kinase II is probably the major protein phosphorylating activity of these oocyte organelles.

Animals↗
PubMed1985

Multiple hepatic adenomas after long-term therapy with testosterone enanthate. Review of the literature.

We report a case of multiple hepatic adenomas developed in a 32-year-old man with renal allograft after long-term therapy with testosterone enanthate. Histological assessment showed a benign hepatocellular adenoma, which has not regressed over a 6-month follow-up since androgen withdrawal. A review of primary hepatic tumors associated with androgenic-anabolic steroid therapy published in the English literature has been carried out, concentrating on the more relevant recent publications. No previous case of hepatic adenoma with possible relationship to the use of non-17-alpha alkylated compounds has been reported.

Adult↗
PubMed1978

The value of emergency angiography in the diagnosis and prognosis of acute mesenteric arterial insufficiency.

Selective angiography is the technic which provides a higher accuracy in diagnosing an acute mesenteric arterial insufficiency. If carried out at an early stage it surpasses any other technic. It permits not only obtaining topographic data to locate the occlusion but also the detection of aspects of the collateral circulation in the loops of the bowel, thus enabling us to determine the therapeutic procedure to follow. We have done selective angiography of the superior mesenteric artery in nine patients in all of whom we identified the embolic disease. In five of these patients the embolus was in the main trunk and in four it was in the distal branches. The mortality rate varied depending on the site of the embolus and the time elapsed in the process. In three of the patients with distal localization and in one with trunk localization and sufficient arterial permeation, a conservative therapy was used with good results in all of them.

Acute Disease↗