Navegando por Palavras-chave "Paratormônio"
Agora exibindo 1 - 5 de 5
Resultados por página
Opções de Ordenação
- ItemEmbargoAção do paratormônio humano (1-34) no tecido ósseo de ratas osteopênicas(Universidade Federal de São Paulo (UNIFESP), 2010-07-27) Costa, Rafael Pacheco da [UNIFESP]; Katchburian, Eduardo [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Introduction: Bone remodeling depends upon a variety of systemic and local factors. Systemic factors that have a direct effect include the parathyroid hormone which together with other factors maintains bone homeostasis. Biosynthetic human parathyroid hormone (1-34) [hPTH(1-34)] has been used to stimulate bone formation in patients with osteoporosis. However, the effects of hPTH (1-34) on bone tissue are not well unknown. Aim: The aim of this study was investigate the effects of the short-term intermittent treatment with hPTH (1-34) in different doses on bone constituents of osteopenic rats. Methods: Forty 6-month-old ovariectomized osteopenic rats were divided into four groups GI – group injected with saline solution (control); GII – group injected with 0.3μg/kg/day; GIII – group injected with 5μg/kg/day; GIV – group injected with 0.25 μg/kg 3 times per week. After one month of treatment the animals were sacrificed and the length and thickness of the femurs/tibias were measured. Measurements for sulfated glycosaminoglycans (GAGs), hyaluronic acid (HA) and physical and biomechanical properties (3-point bending) were conducted in unfixed/ fresh tissue. Biomechanical and physical properties were assessed from the tibias. Distal femurs were fixed in 4% formaldehyde (derived from paraformaldehyde) buffered with 0.1M sodium phosphate at pH 7.2 for 4 days. After decalcification in 25% formic acid (pH 2,0), the samples were processed for histology, histomorphometric analyses, histochemistry (Alcian blue pH 2.5 and pH 0.5 and Picro-sirius – polarization), immunohistochemistry for hyaluronic acid and TUNEL method. Results: There was an increase only on thickness tibia in GIII group. GIII revealed an increase in bone mineral density, bone density and organic material when compared to control group, but there was a decreased in water bone in GIII. The 3-point bending test showed no difference among the groups. Bone volume (BV/TV) was higher in GIII (6%). Cortical bone thickness (Ct.Wi) increased in GII and GIII. A decrease of sulfated GAGs was observed in GIII and GIV, as judged by the Alcian blue method and the sulfated GAGs assessment revealed a decrease of chondroitin sulfate only in the group that received the highest dose of hPTH (1-34). The ELISA method revealed a significant increase of HA in GIII, although a reduction as shown by immunohistochemistry in treated groups. An increase in the green birefringence (type I immature collagen) was observed on cortical and trabecular bone in all treated groups. The percentage of TUNEL positive osteocytes was significantly increased in the cortical and trabecular bone of GIV. Furthermore, we observed many TUNEL-positive cells in the periosteum of GIV group. Conclusion: Our results show that hPTH (1-34) administered intermittently in shortterm accelerates bone remodeling process by promoting bone formation and restoration of bone microarchitecture in osteopenic rats in a dose-dependent way.
- ItemAcesso aberto (Open Access)Baixas concentrações séricas de 25-hidroxivitamina D em crianças e adolescentes com lúpus eritematoso sistêmico(Universidade Federal de São Paulo (UNIFESP), 2011-06-29) Peracchi, Octávio Augusto Bedin [UNIFESP]; Hilário, Maria Odete Esteves [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Objective: to evaluate the levels of 25-hydroxivitamin-D (25(OH)D) in children and adolescents with Systemic Lupus Erythematosus (Juvenile SLE [JSLE]) and to associate them with disease duration and activity, use of medications (chloroquine and glucocorticoids), vitamin D intake, levels of calcium, phosphorus and alkaline phosphatase and bone mineral density. Methods: through a cross-sectional study 30 children and adolescents with SLE were evaluated and compared to 30 healthy individuals age and gender matched. Assessment of clinical status, disease activity, anthropometry, laboratory markers and bone mineral density were performed. Results: of the 30 patients included in the study, 25 (83.3%) were female, 16 (53.3%) caucasians, mean of age of 13.7 years. The mean of age at diagnosis was 10.5 years and the mean of disease duration was 3.4 years. The mean levels of calcium, albumin and alkaline phosphatase were significant lower in the patients with JSLE compared with controls (p<0.001, p=0.006 and p<0.001, respectively). Twenty-nine patients (97%) and 23 controls (77%) had 25(OH)D levels lower than 32 ng/mL with significantly difference between them (p<0.001). Fifteen patients (50%) had vitamin D levels <20 ng/ml and 14 between 20 and 32 ng/ml. However those values were not associated to greater disease activity, higher levels of parathormone, medications or bone mineral density. Vitamin D levels were not different related to ethnic group (p=0.083), body mass index (p=0.955), height to age (p=0.650) and pubertal stage (p=0.524). Conclusions: we observed insufficient serum concentrations of 25(OH)D in patients with JSLE significantly more frequently than in controls, however with no association with disease activity, higher levels of parathormone, use of medications or bone mineral density alterations.
- ItemAcesso aberto (Open Access)Diagnóstico Laboratorial do Hiperparatiroidismo Primário(Sociedade Brasileira de Endocrinologia e Metabologia, 2002-02-01) Hauache, Omar M. [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Fleury - Centro de Medicina DiagnósticaPrimary hyperparathyroidism (PHP) is a frequent endocrinopathy. Increased serum calcium levels may be considered as a potential marker for parathyroid autonomy and this explains why PHP should be routinely investigated in whoever presents with hypercalcemia. High or inappropriately normal PTH levels in the presence of hypercalcemia are very suggestive of PHP. On the other hand, PHP is very unlikely in the absence of hypercalcemia. Extracellular calcium concentrations may be evaluated by the measurement of total or ionized calcium, but the serum protein levels do not affect ionized calcium level. Regarding PTH, the current methods available detect the intact molecule of PTH (immunoradiometric and immunochemiluminescent assays), including PTH 1-84 and 7-84. Recently, assays that only detect the so-called bioactive PTH (1-84 PTH) are available. PTH levels are undetectable in humoral hypercalcemia of malignancy. In short, measuring serum calcium and PTH should be enough for the diagnosis of PHP. To further evaluate a patient with PHP and its potential bone and renal complications, one can order other exams such as evaluation of renal function, daily urinary calcium excretion, renal ultrassonography and bone densitometry. These exams may be useful to help the physician decide whether surgery should be indicated or not.
- ItemAcesso aberto (Open Access)Evolution of PTH assays(Sociedade Brasileira de Endocrinologia e Metabologia, 2006-08-01) Vieira, Jose Gilberto Henriques [UNIFESP]; Kunii, Ilda Sizue [UNIFESP]; Nishida, Sonia Kiyomi; Laboratorio Fleury; Universidade Federal de São Paulo (UNIFESP)PTH metabolism is complex and the circulating forms include the intact 1-84 molecule as well as several carboxyl-terminal fragments. The first generation of PTH assays included several types of competitive assays, with specificities that spanned carboxyl, mid-region and amino-terminal portions of the molecule. The limitations of these assays and the methodological evolution led to the description of 2nd generation non-competitive immunometric assays for PTH in the late 80's, based on the recognition of the PTH molecule by two different antibodies, one directed against de amino-terminal and other against the carboxyl-terminal segments. The observation that in some circumstances long carboxyl-terminal segments were also measured by 2nd generation assays led to the development of 3rd generation assays based on amino-terminal specific antibodies that are specific for the first amino acids, measuring only the molecular forms that activate PTH1R. The practical and cost-benefit advantages of these assays are still debatable. The recent observation that carboxyl-terminal fragments of PTH have biological activity via a distinct receptor than PTH1R, points to the future need of more than one assay in order to evaluate parathyroid hormone function.
- ItemAcesso aberto (Open Access)Paratormônio e osteoporose: encontrando o fio da meada. Bases fisiológicas para utilização do PTH no tratamento da osteoporose(Sociedade Brasileira de Endocrinologia e Metabologia, 2002-06-01) Gracitelli, Mauro E.c.; Vidoris, André Alexis C.; Luba, Ricardo; Lazaretti-Castro, Marise [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Parathyroid hormone (PTH) will be available in a few months for the treatment of osteoporosis. When used as a single daily subcutaneous injection for at least 1 year, it increases bone mass and reduces fracture rate more efficiently than the usual anti-resorptive therapy. Recently published articles show that PTH can act through different intracellular signaling pathways, depending on its concentration, time of exposure and molecular fragments. High concentration and prolonged exposure to amino-terminal PTH fragments stimulate bone resorption. On the other hand, in an intermittent way and in low concentrations, PTH administration increases bone formation. This review aims to present the principal results of clinical and experimental researches on PTH actions, while trying to explain the rationale for its dual effect on bone remodeling.