Evolução dos ensaios para paratormônio

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.O metabolismo do PTH e complexo e as formas circulantes incluem o PTH 1-84, assim como fragmentos C-terminal. A primeira geração de ensaios para o PTH incluía vários ensaios competitivos com especificidades para as regiões carboxi, meio da molécula e amino-terminal. A limitação destes ensaios e a evolução metodológica, levaram ao desenvolvimento dos ensaios não competitivos de 2ª. geração no final dos anos 80, baseados no reconhecimento por dois anticorpos diferentes, contra a porção amino e carboxi-terminal respectivamente. A observação que em algumas circunstâncias segmentos carboxiterminais longos também eram detectados, levou ao desenvolvimento dos ensaios de 3ª. geração, baseados em anticorpos específicos para a porção aminoterminal com maior especificidade para os primeiros aminoácidos, e assim mensurando apenas a forma molecular que ativa o PTH1R. As vantagens práticas e o custo-benefício deste ensaio ainda e motivo de debate. A observação recente de que fragmentos carboxiterminais têm atividade biológica via receptor distinto, aponta para a necessidade futura de mais de um ensaio para avaliar a função do paratormônio.Laboratorio FleuryUniversidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina (EPM) Division of EndocrinologyUNIFESP, EPM, Division of EndocrinologySciEL

The effect of sun exposure on 25-hydroxyvitamin D concentrations in young healthy subjects living in the city of São Paulo, Brazil

The range of 25-hydroxyvitamin D (25OHD) concentration was determined in a young healthy population based on bone metabolism parameters and environmental and behavioral aspects. We studied 121 healthy young volunteers (49 men, 72 women) living in São Paulo (23º 34' south latitude) belonging to three occupational categories: indoor workers (N = 28), medical school students (N = 44), and resident physicians (N = 49). Fasting morning blood samples were collected once from each volunteer from August 2002 to February 2004, and 25OHD, total calcium, albumin, alkaline phosphatase, phosphorus, creatinine, intact parathyroid hormone, osteocalcin, and type I collagen carboxyterminal telopeptide were measured. Data are reported as means ± SD. Mean subject age was 24.7 ± 2.68 years and mean 25OHD level for the entire group was 78.7 ± 33.1 nM. 25OHD levels were lower (P < 0.05) among resident physicians (67.1 ± 27.0 nM) than among students (81.5 ± 35.8 nM) and workers (94.0 ± 32.6 nM), with the last two categories displaying no difference. Parathyroid hormone was higher (P < 0.05) and osteocalcin was lower (P < 0.05) among resident physicians compared to non-physicians. Solar exposure and frequency of beach outings showed a positive association with 25OHD (P < 0.001), and summer samples presented higher results than winter ones (97.8 ± 33.5 and 62.9 ± 23.5 nM, respectively). To define normal levels, parameters such as occupational activity, seasonality and habits related to solar exposure should be taken into account. Based on these data, we considered concentrations above 74.5 nM to be desired optimal 25OHD levels, which were obtained during the summer for 75% of the non-physicians

The benefits of a high-intensity aquatic exercise program (HydrOS) for bone metabolism and bone mass of postmenopausal women

This study aimed to evaluate the 24-week effects of a high-intensity aquatic exercise program on bone remodeling markers and bone mass of postmenopausal women. in this randomized, controlled trial we studied 108 women (58.8 +/- A 6.4 years), randomized into Aquatic Exercise Group (AEG), n = 64, performing 24 weeks of aquatic exercises, and Control Group (CG), n = 44, sedentary. They had their fasting morning blood sample collected for the measures of intact parathyroid hormone (iPTH), procollagen type 1 amino-terminal propeptide (P1NP) and carboxy-terminal cross-linking telopeptide of type I collagen (CTx). Bone mass was measured by dual-energy X-ray absorptiometry before and after the intervention. Participants of both groups received a daily supplementation of 500 mg of elementary calcium and 1,000 IU of vitamin D (cholecalciferol). Results showed an augment in bone formation marker (P1NP) only in the AEG (15.8 %; p = 0.001), and although both groups experienced significant enhancements in bone resorption marker (CTx), this increase was less considerable in the AEG (15 % in the AEG and 29 % in the CG). IPTH was increased by 19 % in the CG (p = 0.003) at the end. the femoral trochanter BMD presented a 1.2 % reduction in the CG (p = 0.009), whereas in the AEG no change was observed (p = 0.069). the proposed aquatic exercise program was efficient in attenuating bone resorption raise and enhancing bone formation, which prevented the participants in the AEG from reducing the femoral trochanter BMD, as happened in the CG.Universidade Federal de São Paulo, UNIFESP, Sch Med, Div Endocrinol, São Paulo, BrazilAmbulatorio Endocrinol UNIFESP, BR-04038030 São Paulo, BrazilUniv São Paulo, Sch Phys Educ & Sport, São Paulo, BrazilUniv Fed Rio Grande do Sul, Sch Phys Educ, Exercise Res Lab, Porto Alegre, RS, BrazilUniversidade Federal de São Paulo, UNIFESP, Sch Med, Div Endocrinol, São Paulo, BrazilAmbulatorio Endocrinol UNIFESP, BR-04038030 São Paulo, BrazilWeb of ScienceFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP: 08/50179-