RESUMO
The advantages of using (2)H(2)O to quantify cholesterol synthesis include i) homogeneous precursor labeling, ii) incorporation of (2)H via multiple pathways, and iii) the ability to perform long-term studies in free-living subjects. However, there are two concerns. First, the t(1/2) of tracer in body water presents a challenge when there is a need to acutely replicate measurements in the same subject. Second, assumptions are made regarding the number of hydrogens (n) that are incorporated during de novo synthesis. Our primary objective was to determine whether a step-based approach could be used to repeatedly study cholesterol synthesis a subject. We observed comparable changes in the (2)H-labeling of plasma water and total plasma cholesterol in African-Green monkeys that received five oral doses of (2)H(2)O, each dose separated by one week. Similar rates of cholesterol synthesis were estimated when comparing data in the group over the different weeks, but better reproducibility was observed when comparing replicate determinations of cholesterol synthesis in the same nonhuman primate during the respective dosing periods. Our secondary objective was to determine whether n depends on nutritional status in vivo; we observed n of â¼25 and â¼27 in mice fed a high-carbohydrate (HC) versus carbohydrate-free (CF) diet, respectively. We conclude that it is possible to acutely repeat studies of cholesterol synthesis using (2)H(2)O and that n is relatively constant.
Assuntos
Colesterol/biossíntese , Óxido de Deutério/química , Espectrometria de Massas/métodos , Animais , Chlorocebus aethiops , Óxido de Deutério/metabolismo , Feminino , Cromatografia Gasosa-Espectrometria de Massas , Hidrogênio/metabolismo , Masculino , Camundongos , Estado Nutricional , IncertezaRESUMO
Protein synthesis can be estimated by measuring the incorporation of a labeled amino acid into a proteolytic peptide. Although prelabeled amino acids are typically administered, recent studies have tested (2)H(2)O; the assumption is that there is rapid equilibration of (2)H (in body water) with the carbon-bound hydrogens of amino acids before those amino acids are incorporated into a protein(s). We have determined the temporal changes in (2)H labeling of body water and amino acids which should build confidence in (2)H(2)O-based studies of protein synthesis when one aims to measure the (2)H labeling of proteolytic peptides.
Assuntos
Aminoácidos/química , Água Corporal/química , Peptídeos/química , Proteoma/biossíntese , Proteômica/métodos , Animais , Chlorocebus aethiops , Deutério/química , Cromatografia Gasosa-Espectrometria de Massas , Marcação por Isótopo , Fatores de TempoRESUMO
Ms. Andrews-Kelly recounts the experiences and inspirations that have guided her career in providing care, enrichment and training for non-human primates.