Critical care and vitamin D status assessment: what about immunoassays and calculated free 25OH-D?

BACKGROUND: Interpretation of 25OH-D measurement during critical care (CC) may be problematic due to variations of binding protein concentrations (albumin, ALB, and vitamin D binding protein, VDBP). Determination of free 25OH-D concentration may thus be relevant in CC patients. The aim of this observational study was to evaluate effects of an acute hemodilution on vitamin D (VD) status. METHODS: Blood samples were obtained before (T1) and after a crystalloid load (T2) administered at anesthesia induction for minor surgery. 25OH-D was measured with LC-MS/MS and with 3 immunoassays (IA): DiaSorin Liaison, IDS iSYS and bioMérieux Vidas. VDBP was measured with the R&D Elisa and ALB on Cobas. Free 25OH-D was calculated using published formula. Accuracy of each 25OH-D IA was calculated as the percentage of IA values within 20% of their respective LC-MS/MS values. Performances of the three AI were compared with LC-MC/MS using Bland-Altman analysis. RESULTS: Twenty adults were included. Compared to T1 values, VDBP, ALB and LC-MS/MS values decreased in parallel by a mean of 23% at T2. IA values decreased less significantly (12, 14 and 15% for Liaison, iSYS and Vidas, respectively). IA-based calculated free 25OH-D significantly increased after dilution, while LC-MS/MS-based free values remained stable. At T1 and T2, bias were demonstrable for all IA. After hemodilution, bias would lead to overestimation for the three IA. Accuracy of IA decreased after dilution. CONCLUSIONS: Due to matrix effects, compared to LC-MS/MS, IA results were impacted by hemodilution. In CC patients, LC-MS/MS seems to be the best option to measure 25OH-D. Specific LC-MS/MS method should be developed to measure free 25OH-D.

Rapid assessment methods of resilience for natural and agricultural systems.

The resilience, ecological function and quality of both agricultural and natural systems were evaluated in the mountainous region of the Atlantic Rain Forest of Rio de Janeiro through Rapid Assessment Methods. For this goal new indicators were proposed, such as eco-volume, eco-height, bio-volume, volume efficiency, and resilience index. The following agricultural and natural systems have been compared according: (i) vegetables (leaf, fruit and mixed); (ii) citrus; (iii) ecological system; (iv) cattle, (v) silvo-pastoral system, (vi) forest fragment and (vii) forest in regeneration stage (1, 2 and 3 years old). An alternative measure (index) of resilience was proposed by considering the actual bio-volume as a function of the potential eco-volume. The objectives and hypotheses were fulfilled; it is shown that there does exist a high positive correlation between resilience index, biomass, energy efficiency and biodiversity. Cattle and vegetable systems have lowest resilience, whilst ecological and silvo-pastoral systems have greatest resilience. This new approach offers a rapid, though valuable assessment tool for ecological studies, agricultural development and landscape planning, particularly in tropical countries.

Rapid assessment methods of resilience for natural and agricultural systems

The resilience, ecological function and quality of both agricultural and natural systems were evaluated in the mountainous region of the Atlantic Rain Forest of Rio de Janeiro through Rapid Assessment Methods. For this goal new indicators were proposed, such as eco-volume, eco-height, bio-volume, volume efficiency, and resilience index. The following agricultural and natural systems have been compared according: (i) vegetables (leaf, fruit and mixed); (ii) citrus; (iii) ecological system; (iv) cattle, (v) silvo-pastoral system, (vi) forest fragment and (vii) forest in regeneration stage (1, 2 and 3 years old). An alternative measure (index) of resilience was proposed by considering the actual bio-volume as a function of the potential eco-volume. The objectives and hypotheses were fulfilled; it is shown that there does exist a high positive correlation between resilience index, biomass, energy efficiency and biodiversity. Cattle and vegetable systems have lowest resilience, whilst ecological and silvo-pastoral systems have greatest resilience. This new approach offers a rapid, though valuable assessment tool for ecological studies, agricultural development and landscape planning, particularly in tropical countries.

Foram avaliadas, em região montanhosa da Mata Atlântica do Rio de Janeiro a resiliência, função ecológica e qualidade tanto do sistema agrícola como natural, através dos métodos de avaliação rápida ("rapid assessment methods"). Para este fim, foram propostos novos indicadores como eco-volume, eco-altura, bio-volume, eficiência volumétrica e índice de resiliência. Os seguintes sistemas agrícolas e naturais foram comparados: (i) hortaliças (folhas, frutos e mistos); (ii) citros; (iii) sistema ecológico; (iv) gado; (v) sistema silvo-pastoral; (vi) fragmento florestal; (vii) floresta em estágio de recuperação (1, 2 e 3 anos de idade). Uma forma alternativa de resiliência foi proposta considerando o bio-volume real como uma função do eco-volume potencial. Os objetivos e hipóteses foram alcançados; demonstrou-se que existe uma correlação altamente positiva entre índice de resiliência, energia da biomassa, eficiência energética e biodiversidade. Pecuária e sistemas de hortaliças apresentaram as mais baixas resiliências enquanto sistemas ecológico e silvo-pastoral tiveram maiores resiliências. Esta nova estratégia oferece uma rápida e valiosa ferramenta de avaliação para estudos ecológicos, desenvolvimento agrícola e planejamento paisagístico, especialmente em países tropicais.