Browsing by Author "Rodriguez, JA"

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    Bradykinin regulates cyclooxygenase-2 in rat renal thick ascending limb cells
    (2004) Rodriguez, JA; Vio, CP; Pedraza, PL; McGiff, JC; Ferreri, NR
    Cyclooxygenase-2 (COX-2) is constitutively expressed in a subset of thick ascending limb cells in the cortex and medulla and increases when the renin-angiotensin and kallikrein-kinin systems are activated. Although the contribution of angiotensin II to the regulation of COX-2 is known, the effects of bradykinin on COX-2 expression have not been determined in this nephron segment. We evaluated expression of B2 bradykinin receptors in thick ascending limb cells containing COX-2 and the effect of bradykinin on COX-2 expression in primary cultured medullary thick ascending cells. The presence of B2 receptors was studied in renal sections by immunohistochemistry with antibodies against B2, COX-2, and Tamm-Horsfall glycoprotein. B2 receptors were detected on the apical and basolateral portion of the thick ascending cells. These cells also contained COX-2, suggesting that COX-2 expression may be regulated via B2 receptor. Incubation of cultured medullary thick ascending cells with bradykinin (10(-7) to 10(-5) mol/L) induced a significant increase on COX-2 protein expression. Maximal expression of COX-2 was observed 4 hours after exposure to bradykinin (10(-7) mol/L), effect abolished by a B2 receptor antagonist (HOE-140; 10(-6) mol/L). Prostaglandin E-2 production increased when these cells were challenged with bradykinin for 4 hours, indicating that COX-2 was enzymatically active. We have demonstrated ( 1) the presence of B2 receptors in thick ascending limb cells expressing COX-2 and ( 2) the stimulatory effect of bradykinin on COX-2 protein expression, via B2 receptors, in cultured medullary thick ascending cells. We suggest that bradykinin can affect ion transport in the thick ascending limb via a COX-2-mediated mechanism.
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    gps Mutations in Chilean patients harboring growth hormone-secreting pituitary tumors
    (WALTER DE GRUYTER GMBH, 1999) Johnson, MC; Codner, E; Eggers, M; Mosso, L; Rodriguez, JA; Cassorla, F
    Hypersecretion of GH is usually caused by a pituitary adenoma and about 40% of these tumors exhibit missense gsp mutations in Arg(201) or Gln(227) of the Gs(alpha) gene. We studied 20 pituitary tumors obtained from patients with GH hypersecretion, One tumor was resected from an 11 year-old boy with a 3 year history of accelerated growth, associated with increased concentrations of serum GH and IGF-I, which were not suppressed by glucose administration, The remaining 19 tumors were obtained from adult acromegalic patients, who had elevated baseline serum GH levels that did not show evidence of suppression after administration of glucose, The gsp mutations were studied by enzymatic digestion of the amplified PCR fragment of exon 8 (Arg(201)) and exon 9 (Gln(227)) with the enzymes NlaIII and NgoAIV, respectively. The tumors obtained from the boy and from nine of the 19 patients with acromegaly exhibited the gsp mutation R201H. None of the tumors had the Gln(227) mutation. The gsp positive patients tended to be older, had smaller tumors, and had preoperative basal serum GH levels which were significantly lower (21 +/- 6 vs 56 +/- 16 mu g/l, p < 0.05) than the gsp negative patients, In this study, we documented the presence of a gsp mutation in Arg(201) in a boy with gigantism and in approximately half of 19 Chilean adult patients with acromegaly, similar to other populations.
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    Hypothalamic-pituitary-adrenal axis function and prolactin secretion in systemic lupus erythematosus
    (STOCKTON PRESS, 1998) Gutierrez, MA; Garcia, ME; Rodriguez, JA; Rivero, S; Jacobelli, S
    The objective was to study the response of cortisol and of prolactin (PRL) to specific stimuli in systemic lupus erythematosus (SLE). We measured the response of cortisol to insulin-induced hypoglycemia and of PRL to thyrotropin releasing hormone (TRH) in seven patients with active untreated SLE and in ten paired control subjects. All were women with regular menstrual cycles. With the exception of two patients, they had never received corticosteroids before the study.
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    Pathological characteristics of thyroid microcarcinoma. A review of 402 biopsies
    (2005) Fardella, C; Jimenez, M; Gonzalez, H; Leon, A; Goni, I; Cruz, F; Solar, A; Torres, J; Mosso, L; Gonzalez, G; Rodriguez, JA; Campusano, C; Lopez, JM; Arteaga, E
    Background: Thyroid microcarcinoma is a tumor of 10 mm or less. that should have a low risk of mortality. However a subgroup of these carcinomas is as aggressive as bigger tumors. Aim To describe the pathological presentation of these tumors.. and compare them with larger tumors. Material and methods. All Pathological samples of thyroid carcinoma that were obtained between 1992 and 2003, were studied. In all biopsies, the pathological type, tumor size. the focal or multifocal character the presence of lymph node involvement and the presence of lymphocytic thyroiditis or thyroid hyperplasia, were recorded. Results: One hundred eighteen microcarcinomas and 284 larger tumors were studied. The mean age of patients with microcarcinoma and larger tumors was 42.7 +/- 14 and 49.3 +/- 16 years respectively (p < 0,00.1) and 83% were female. without gender differences between tumor types. klean size of microcarcinomas was 8.6 mm and 116 (98%) were papillary carcinomas. Of these. 109 (94% were well differentiated and seven (6%) were moderatly differentiated. Thirty six(31%) were multifocal and in 10 (8,6%), there was lymph node involvement. The mean size of larger tumors was 23.8 mm and 241 (85%) were papillary carcinomas. Of these, 200 (83%) were well differentiated, and 41 (17%) were moderately differentiated.Eighty five (35%) were multifocal and in 44 (18%) there was lymph node involvement. The prevalence of thyroiditis and hyperplasia was significantly higher among microcardinomas than in larger tumors (15 and 2.5%, respectively, p < 0.001, for the former; 32.4 and 1.7%, respectively, p < 0.001, for the latter. Conclusions. In this series. one third of microcarcinomas were multifocal and 10% had lymph node involvement. Therefore, aggresiveness of these tumors is higher than what is reported in the literature and they should be treated with total thyroidectomy.