若干重要微量金属元素的生物化学功能及其与人体健康的关系

铁、铜、锌、锰、钼和钴是人体中必需的微量元素,对这几种微量元素与人体健康的关系进行了论述,包括它们在人体内的存在与分布、代谢、生理功能及对人体健康的影响。     

Dual effect of N-ethylmaleimide on agonist-mediated conformational changes of β-adrenergic receptors

β-Adrenergic agonists cause adenylate cyclase activation via a conformational change of their receptor. This was earlier revealed by the use of N-ethylmaleimide as a structural probe: agonist-bound receptors are rapidly inactivated by 0.1 mM N-ethylmaleimide while free and antagonist-bound receptors remain unaffected. Furthermore, the β-adrenergic receptors only change conformation when coupled to the guanine nucleotide regulatory component of the adenylate cyclase system.It is shown in this report that treatment of turkey erythrocyte membranes with the sulphydryl-specific agent 2,2′-dinitro-5,5′-dithiodibenzoic acid and elevated concentrations of N-ethylmaleimide (1–10 mM) do not affect the total receptor number, but prevent the ability of β-adrenergic agonists to mediate conformational changes. This effect is mimicked by GTP. These three compounds cause also a two-to four-fold decrease in agonist affinity. Both phenomena may be explained by the ability of the reagents to prevent, and of GTP to reverse, the functional coupling between the receptors and the regulatory component of the adenylate cyclase system.Removal of Mg²⁺ from the incubation medium (i.e. presence of 1 mM EDTA) produces a similar decrease in agonist affinity, but does not impair the ability of agonist/N-ethylmaleimide to inactivate the receptors. This suggests that Mg²⁺ increases the agonist affinity for the receptor-regulatory component complex, but is not required for its formation.     

Documento de consenso para la determinación e informe del perfil lipídico en laboratorios clínicos españoles: ¿Qué parámetros debe incluir un perfil lipídico básico?

Cardiovascular diseases (CVD) continue to be the main cause of death in our country. Adequate control of lipid metabolism disorders is a key challenge in cardiovascular prevention that is far from being achieved in real clinical practice. There is a great heterogeneity in the reports of lipid metabolism from Spanish clinical laboratories, which may contribute to its poor control. For this reason, a working group of the main scientific societies involved in the care of patients at vascular risk, has prepared this document with a consensus proposal on the determination of the basic lipid profile in cardiovascular prevention, recommendations for its realization and unification of criteria to incorporate the lipid control goals appropriate to the vascular risk of the patients in the laboratory reports.