Vitamina D: uma abordagem molecular / Vitamin D: A Molecular Boarding

Introdução: A expressão vitamina D é uma denominaçãoempregada para designar os diversos compostos que possuem apropriedade de prevenir e curar o raquitismo, Os mais importanteso ergocalciferol (D2) e o colecalciferol (D3), embora cerca de dezcompostos expressem atividade de vitamina D. Todas são vitaispara manutenção e controle da homeostase do cálcio e do fósforo.São formadas a partir de suas pró-vitaminas no organismo, pelaação da radiação ultra-violeta (UV) da luz solar. O 7-dehidrocolesterol é convertida na vitamina D3. A forma ativa é a1,25-diidroxicolecalciferol, ou calcitriol. De origem exógena ouendógena, esta forma ativa tem comportamento de hormônioesterólico. Importantes atividades da vitamina D, em particular nointestino, rim e osso colocam-na na condição de um hormônio paraa manutenção da homeostase do cálcio e do fosfato. A ocorrênciade receptores desse hormônio nos tecidos do homem se constituinuma relevante constatação que justifica as outras ações a elaatribuídas, independente da atividade específica sobre ometabolismo mineral. A vitamina D dispõe de uma via endógena deformação – ação da radiação ultra-violeta da luz solar sobre ocolesterol na pele – embora seu aporte exógeno seja um importantefator para a manutenção de níveis considerados ideais. Alteraçõesou deficiências no seu mecanismo de ativação e de controle daabsorção, resultam em distúrbios orgânicos, podendo evoluir paraimportantes patologias como o raquitismo e a osteomalácia.Objetivo: Analisar a relevância da vitamina D, atualmenteconsiderada como um hormônio esterólico,...

Introduction: The term vitamin D is a generic denomination used to refer to the compounds that have the property of preventing and healing raquitism, among which the most important are ergocalciferol (D2) and cholecalciferol (D3), although nearly 10 different compounds express different vitamin D activities and are all vital to calcium and phosphor homeostasis. Both can be formed from their provitamins by ultraviolet irradiation (UV) present in sunlight. In human skin, provitamin 7-dehydrocholesterol is converted into vitamin D3 . The form of vitamin D that is biologically active in the body is 1,25- dihydroxycholecalciferol or calcitriol. Whether exogenous or endogenous in its origin, the behavior of this active form is typical of esterolic hormone. Vitamin D activities, particularly in the bowels, kidneys, and bones make it stand as a hormone for the maintenance of calcium and phosphate homeostasis, thus enabling the skeleton healthy development. Ocurrence of receptors of this hormone in almost all human body tissues is a relevant observation that justifies the other actions attributed to it, independently from their specific activity on the metabolism of minerals. Vitamin D formation has an endogenous route ­ action of ultra-violet irradiation on cholesterol contained in the skin ­ although it holds in its exogenous contribution an important factor for the maintenance of levels considered ideal to the fulfillment of organic requirements. Alterations or deficiencies in their activation and absorption control mechanisms result in organic disturbances, which raquitism and osteomalatia. Objective: This study it aims at the analysis of the relevance of vitamin D currently considered as a esterolic hormone for the maintenance of the homeostasia in human being. Conclusion: Therefore, regular expositions to sun irradiation and even food supplements become necessary in cases of compromised absorption or transformation in its active form. Theme relevance is the motivation for this scientific update article.

Formaldehyde levels in absorbent paper points through hplc

Formaldehyde tablets have been frequently used to keep absorbent paper points sterilized. However, the toxicity of this drug must be considered. The present study aims to determine rates of formaldehyde impregnation in absorbent paper points kept in environments containing formaldehyde tablets. Thus, an accurate analytical methodology requiring simple operations and providing the determination of low concentration levels (ppm) of the formaldehyde impregnated in absorbent paper points was used. The absorbent paper points which had been kept in environments containing formaldehyde tablets were placed in test tubes containing 2.4-dinitrophenylhydrazine and, following an ultrasound bath, were transferred to a microcolumn and washed withdistilled water. The retained hydrazones were diluted in acetonitrile and the amount of 10ml was injected in the High Performance Liquid Chromatographer. The results were subjected to descriptive statistics encompassing the estimation of mean values, the standard deviation, and the confidence interval (95%) for mean values. This study showed a significant rate of formaldehyde impregnation in absorbent paper points of any size, especially in those kept in environments containing formaldehyde tablets over a seven-day period.