Simulação numérica do comportamento da madeira de Eucalytus citrodora ao cisalhamento através do ensaio de tração Off-Axis

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Valores de referência de cortisol salivar para a avaliação adrenal em crianças menores de três anos, sem patologias

Pós-graduação em Pediatria - FMB

Stimulatory effects of adenosine on prolactin secretion in the pituitary gland of the rat

We investigated the effects of adenosine on prolactin (PRL) secretion from rat anterior pituitaries incubated in vitro. The administration of 5-N- methylcarboxamidoadenosine (MECA), an analog agonist that preferentially activates A2 receptors, induced a dose-dependent (1 nM to 1 µM) increase in the levels of PRL released, an effect abolished by 1,3-dipropyl-7-methylxanthine, an antagonist of A2 adenosine receptors. In addition, the basal levels of PRL secretion were decreased by the blockade of cyclooxygenase or lipoxygenase pathways, with indomethacin and nordihydroguaiaretic acid (NDGA), respectively. The stimulatory effects of MECA on PRL secretion persisted even after the addition of indomethacin, but not of NDGA, to the medium. MECA was unable to stimulate PRL secretion in the presence of dopamine, the strongest inhibitor of PRL release that works by inducing a decrease in adenylyl cyclase activity. Furthermore, the addition of adenosine (10 nM) mimicked the effects of MECA on PRL secretion, an effect that persisted regardless of the presence of LiCl (5 mM). The basal secretion of PRL was significatively reduced by LiCl, and restored by the concomitant addition of both LiCl and myo-inositol. These results indicate that PRL secretion is under a multifactorial regulatory mechanism, with the participation of different enzymes, including adenylyl cyclase, inositol-1-phosphatase, cyclooxygenase, and lipoxygenase. However, the increase in PRL secretion observed in the lactotroph in response to A2 adenosine receptor activation probably was mediated by mechanisms involving regulation of adenylyl cyclase, independent of membrane phosphoinositide synthesis or cyclooxygenase activity and partially dependent on lipoxygenase arachidonic acid-derived substances.

Adenosine A1 receptor-mediated inhibition of in vitro prolactin secretion from the rat anterior pituitary

In previous studies, we demonstrated biphasic purinergic effects on prolactin (PRL) secretion stimulated by an adenosine A₂ agonist. In the present study, we investigated the role of the activation of adenosine A₁ receptors by (R)-N6-(2-phenylisopropyl)adenosine (R-PIA) at the pituitary level in in vitro PRL secretion. Hemipituitaries (one per cuvette in five replicates) from adult male rats were incubated. Administration of R-PIA (0.001, 0.01, 0.1, 1, and 10 µM) induced a reduction of PRL secretion into the medium in a U-shaped dose-response curve. The maximal reduction was obtained with 0.1 µM R-PIA (mean ± SEM, 36.01 ± 5.53 ng/mg tissue weight (t.w.)) treatment compared to control (264.56 ± 15.46 ng/mg t.w.). R-PIA inhibition (0.01 µM = 141.97 ± 15.79 vs control = 244.77 ± 13.79 ng/mg t.w.) of PRL release was blocked by 1 µM cyclopentyltheophylline, a specific A₁ receptor antagonist (1 µM = 212.360 ± 26.560 ng/mg t.w.), whereas cyclopentyltheophylline alone (0.01, 0.1, 1 µM) had no effect. R-PIA (0.001, 0.01, 0.1, 1 µM) produced inhibition of PRL secretion stimulated by both phospholipase C (0.5 IU/mL; 977.44 ± 76.17 ng/mg t.w.) and dibutyryl cAMP (1 mM; 415.93 ± 37.66 ng/mg t.w.) with nadir established at the dose of 0.1 µM (225.55 ± 71.42 and 201.9 ± 19.08 ng/mg t.w., respectively). Similarly, R-PIA (0.01 µM) decreased (242.00 ± 24.00 ng/mg t.w.) the PRL secretion stimulated by cholera toxin (0.5 mg/mL; 1050.00 ± 70.00 ng/mg t.w.). In contrast, R-PIA had no effect (468.00 ± 34.00 ng/mg t.w.) on PRL secretion stimulation by pertussis toxin (0.5 mg/mL; 430.00 ± 26.00 ng/mg t.w.). These results suggest that inhibition of PRL secretion after A₁ receptor activation by R-PIA is mediated by a Gi protein-dependent mechanism.

Polymorphism analysis in genes of the somatotropic axis in Nellore cattle selected for growth

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The Leukotriene B-4/BLT1 Axis Is a Key Determinant in Susceptibility and Resistance to Histoplasmosis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Thyroid Hormone Stimulates the Proliferation of Sertoli Cells and Single Type A Spermatogonia in Adult Zebrafish (Danio rerio) Testis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Endoscopic endonasal approach for pituitary adenoma: surgical complications in 301 patients

The authors investigate the complications of transnasal transsphenoidal endoscopic surgery in the treatment of 301 patients with pituitary adenomas. A retrospective analysis of complications in 301 patients submitted to transsphenoidal transnasal endoscopic surgery at the General Hospital of Fortaleza, Brazil between January 1998 and December 2009. The complications were divided in two groups: anatomical (oronasofacial, sphenoid sinus, intrasellar, suprasellar and parasellar) and endocrinological complications (anterior and posterior pituitary dysfunctions). We observed a total of 81 complications (26.9%) in our series. Anatomical complications occurred in 8.97% (27 cases): 8 CSF postoperative leaks (2.6%), 6 cases (1.9%) of delayed nasal bleeding, 5 cases (1.6%) of sphenoidal sinusitis, 3 cases (0.9%) of carotid artery lesion, 2 cases of meningitis (0.6%) and one case (0.3%) of each of the uncommon following complications: intrasella-suprasella hematoma, pontine hematoma and chiasmaplexy. Endocrinological complications occurred in 17.9% (54 cases): additional postoperative anterior lobe insufficiency in 35 cases (11.6%), and postoperative diabetes insipidus in 19 cases (6.3%). In our series, 3 cases of deaths (not directly related to the procedure) were also observed. Endoscopic transsphenoidal surgery represents an effective option for the treatment of patients with pituitary tumor. Complications still occur and must be reduced as much as possible. Successful endoscopic pituitary surgery requires extensive training in the use of an endoscope and careful planning of the surgery. Additional improvement can be expected with greater experience and new technical developments.

Low expression of sodium iodide symporter identifies aggressive thyroid tumors

A decreased radioiodine uptake is frequently detected in differentiated thyroid carcinomas (DTC) and is associated with high recurrence rate and reduced survival. We investigated the correlation between NIS mRNA expression levels in the primary tumor and patient outcome using a quantitative real-time RT-PCR method. NIS expression was decreased in 17 DTC (21.04 +/- 39.66 pg Eq) compared to four autoimune thyroid disease (180.51 +/- 92.63 pg Eq) and 14 normal tissues (75.71 +/- 66.98 pg Eq) (p < 0.0001). The 17 thyroid differentiated carcinoma patients were submitted to surgery complemented by radioiodine ablation and had at least 24 months of follow-up, under levothyroxine continued suppressive therapy. According to their outcome, we could characterize a group of papillary carcinoma patients with aggressive carcinomas, whose NIS mRNA levels were markedly lower than a group with non-aggressive carcinomas (0.62 +/- 0.79 versus 54.87 +/- 53.79: p < 0.005). We suggest that the quantification of NIS mRNA relative levels in the primary tumor may predict poor outcome. (C) 2003 Elsevier Ireland Ltd. All rights reserved.

Maternal Thyroid and Glucocorticoid Hormone Interactions in Larval Fish Development, and Their Applications in Aquaculture

Thyroid hormones (THs) have long been known to have regulatory roles in the differentiation and maturation of vertebrate embryos, beginning with the knowledge that hormones of maternal origin are essential for human fetal central nervous and respiratory system development. Precise measurements of circulating THs led to insights into their critically important actions throughout vertebrate growth and development, initially with amphibian metamorphosis and including embryogenesis in fishes. Thyroid cues for larval fish differentiation are enhanced by glucocorticoid hormones, which promote deiodinase activity and thereby increase the generation of triiodothyronine (T-3) from the less bioactive thyroxin (T-4). Glucocorticoids also induce the expression of thyroid hormone receptors in some vertebrates. Maternally derived thyroid hormones and cortisol are deposited in fish egg yolk and accelerate larval organ system differentiation until larvae become capable of endogenous endocrine function. Increases in the T-3/T-4 ratio during larval development may reflect the regulatory importance of maternal thyroid hormones. Experimental applications of individual hormones have produced mixed results, but treatments with combinations of thyroid and corticoid hormones consistently promote larval fish development and improve survival rates. The developmental and survival benefits of maternal endocrine provisioning are increased in viviparous fishes, in which maternal/larval chemical contact is prolonged. Treatments with exogenous thyroid and corticoid hormones consistently promote development and reduce mortality rates in larval fishes, with potential hatchery-scale applications in aquaculture.