Determination of vitamin D metabolites in various biological samples through an improved chemical derivatization assisted liquid chromatography-tandem mass spectrometry approach.

Vitamin D (VD) metabolites are involved in a variety of important metabolic processes and physiological effects in organisms. Profiling of VD metabolites favors a deep understanding of the physiological role of VD. However, VD metabolites are difficult to detect due to their high chemical structural rigidity, structural similarity, and low sensitivities under liquid chromatography-tandem mass spectrometry (LC-MS). Herein, we present a chemical derivatization assisted LC-MS/MS strategy for the detection of VDs, in which 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) is employed to derivatize the conjugated diene of VD metabolites and provides sensitizing reporters for MS detection. After PTAD derivatization, the sensitivities of seven VD metabolites increased by 24-276 folds, with the limits of detection ranging from 3 to 20 pg mL-1. Using this method, we achieved a sensitive and accurate quantification of 7 VD metabolites (vitamin D2, vitamin D3, 25-hydroxyvitamin D2, 25-hydroxyvitamin D3, 1,25-dihydroxyvitamin D2, 1,25-dihydroxyvitamin D3, and 1,24,25-trihydroxyvitamin D3) of the VD metabolic pathway in different trace biological samples, including human serum, mouse tissues (namely liver, kidney, lung, and spleen), and cells. We believe that the present method can provide a promising tool for an in-depth analysis of VD metabolism.

[Risk factors for anorexia in children].

OBJECTIVE: To investigate the risk factors for anorexia in children, and to reduce the prevalence of anorexia in children. METHODS: A questionnaire survey and a case-control study were used to collect the general information of 150 children with anorexia (case group) and 150 normal children (control group). Univariate analysis and multivariate logistic stepwise regression analysis were performed to identify the risk factors for anorexia in children. RESULTS: The results of the univariate analysis showed significant differences between the case and control groups in the age in months when supplementary food were added, feeding pattern, whether they liked meat, vegetables and salty food, whether they often took snacks and beverages, whether they liked to play while eating, and whether their parents asked them to eat food on time (P<0.05). The results of the multivariate logistic regression analysis showed that late addition of supplementary food (OR=5.408), high frequency of taking snacks and/or drinks (OR=11.813), and eating while playing (OR=6.654) were major risk factors for anorexia in children. Liking of meat (OR=0.093) and vegetables (OR=0.272) and eating on time required by parents (OR=0.079) were protective factors against anorexia in children. CONCLUSIONS: Timely addition of supplementary food, a proper diet, and development of children's proper eating and living habits can reduce the incidence of anorexia in children.