Compartmentalized metabolism supports midgestation mammalian development.

Mammalian embryogenesis requires rapid growth and proper metabolic regulation1. Midgestation features increasing oxygen and nutrient availability concomitant with fetal organ development2,3. Understanding how metabolism supports development requires approaches to observe metabolism directly in model organisms in utero. Here we used isotope tracing and metabolomics to identify evolving metabolic programmes in the placenta and embryo during midgestation in mice. These tissues differ metabolically throughout midgestation, but we pinpointed gestational days (GD) 10.5-11.5 as a transition period for both placenta and embryo. Isotope tracing revealed differences in carbohydrate metabolism between the tissues and rapid glucose-dependent purine synthesis, especially in the embryo. Glucose's contribution to the tricarboxylic acid (TCA) cycle rises throughout midgestation in the embryo but not in the placenta. By GD12.5, compartmentalized metabolic programmes are apparent within the embryo, including different nutrient contributions to the TCA cycle in different organs. To contextualize developmental anomalies associated with Mendelian metabolic defects, we analysed mice deficient in LIPT1, the enzyme that activates 2-ketoacid dehydrogenases related to the TCA cycle4,5. LIPT1 deficiency suppresses TCA cycle metabolism during the GD10.5-GD11.5 transition, perturbs brain, heart and erythrocyte development and leads to embryonic demise by GD11.5. These data document individualized metabolic programmes in developing organs in utero.

Quantitative metabolic flux analysis reveals an unconventional pathway of fatty acid synthesis in cancer cells deficient for the mitochondrial citrate transport protein.

The mitochondrial citrate transport protein (CTP), encoded by SLC25A1, accommodates bidirectional trafficking of citrate between the mitochondria and cytosol, supporting lipid biosynthesis and redox homeostasis. Genetic CTP deficiency causes a fatal neurodevelopmental syndrome associated with the accumulation of L- and D-2-hydroxyglutaric acid, and elevated CTP expression is associated with poor prognosis in several types of cancer, emphasizing the importance of this transporter in multiple human pathologies. Here we describe the metabolic consequences of CTP deficiency in cancer cells. As expected from the phenotype of CTP-deficient humans, somatic CTP loss in cancer cells induces broad dysregulation of mitochondrial metabolism, resulting in accumulation of lactate and of the L- and D- enantiomers of 2-hydroxyglutarate (2HG) and depletion of TCA cycle intermediates. It also eliminates mitochondrial import of citrate from the cytosol. To quantify the impact of CTP deficiency on metabolic flux, cells were cultured with a set of 13C-glucose and 13C-glutamine tracers with resulting data integrated by metabolic flux analysis (MFA). CTP-deficient cells displayed a major restructuring of central carbon metabolism, including suppression of pyruvate dehydrogenase (PDH) and induction of glucose-dependent anaplerosis through pyruvate carboxylase (PC). We also observed an unusual lipogenic pathway in which carbon from glucose supplies mitochondrial production of alpha-ketoglutarate (AKG), which is then trafficked to the cytosol and used to supply reductive carboxylation by isocitrate dehydrogenase 1 (IDH1). The resulting citrate is cleaved to produce lipogenic acetyl-CoA, thereby completing a novel pathway of glucose-dependent reductive carboxylation. In CTP deficient cells, IDH1 inhibition suppresses lipogenesis from either glucose or glutamine, implicating IDH1 as a required component of fatty acid synthesis in states of CTP deficiency.

Functional Assessment of Lipoyltransferase-1 Deficiency in Cells, Mice, and Humans.

Inborn errors of metabolism (IEMs) link metabolic defects to human phenotypes. Modern genomics has accelerated IEM discovery, but assessing the impact of genomic variants is still challenging. Here, we integrate genomics and metabolomics to identify a cause of lactic acidosis and epilepsy. The proband is a compound heterozygote for variants in LIPT1, which encodes the lipoyltransferase required for 2-ketoacid dehydrogenase (2KDH) function. Metabolomics reveals abnormalities in lipids, amino acids, and 2-hydroxyglutarate consistent with loss of multiple 2KDHs. Homozygous knockin of a LIPT1 mutation reduces 2KDH lipoylation in utero and results in embryonic demise. In patient fibroblasts, defective 2KDH lipoylation and function are corrected by wild-type, but not mutant, LIPT1 alleles. Isotope tracing reveals that LIPT1 supports lipogenesis and balances oxidative and reductive glutamine metabolism. Altogether, the data extend the role of LIPT1 in metabolic regulation and demonstrate how integrating genomics and metabolomics can uncover broader aspects of IEM pathophysiology.

Prevalence of rheumatoid cachexia assessed by bioelectrical impedance vector analysis and its relation with physical function.

Rheumatoid arthritis (RA) patients frequently have changes in their body composition, with a decrease in muscle mass and an increase in fat mass, a syndrome that is termed rheumatoid cachexia (RC). The prevalence of this nutritional alteration is not well known; there is as yet no consensus, seeing as it depends on the methods, techniques, and cutoff points that are used for its diagnosis. The main aim of this study was to identify RC through assessment by bioelectrical impedance vector analysis (BIVA) and its association with metabolic causes, physical function, and the main disease status, among others. The prevalence of RC was identified in those subjects who fell outside the right lower quadrant of the reference curve of RXc graph of BIVA. Clinical, anthropometric, biochemical and physical activity, emotional status, and diet markers were also evaluated. Ninety-four patients were included (92.55% women). The prevalence of RC assessed by BIVA was 21.28%. BIVA-cachexia patients had a lesser value of handgrip strength vs. patients without BIVA-cachexia 10.2 kg (7.2-13.4) vs. 14.7 kg (9.6-19), p = 0.0062. Disability and folic acid with methotrexate consumption are related to BIVA-cachexia ((OR 4.69, 95% CI 1.33, 16.54, p = 0.016) and (OR 0.19, 95%CI 0.058, 0.651, p = 0.008), respectively). BIVA could represent a valuable tool to assess presence of RC. It is important that RA patients have physical therapy to improve their nutritional status.

Internal and inter-rater reliability of the ASQ-3 in Mexican preschoolers / Confiabilidad interna e interevaluador del ASQ-3 en preescolares mexicanos

Abstract: Introduction: Monitoring child development includes the promotion of development in the healthy child and the detection of delays and early indicators of disorders that begin in the first five years of life through easy-to-use, easy to mark, and low-cost screening tests. Objective: To evaluate the internal reliability and inter-rater reliability of the ASQ-3 in Mexican preschool children. Method: The ASQ-3 was applied to parents and/or teachers of 33 - 60 month old children who attended the Centros de Desarrollo Infantil (Child Development Centers-CENDIS) in the public and private sectors of Mexico City. Results: A total of n = 1052 questionnaires were obtained, grouped into six age groups (33, 36, 42, 48, 54, and 60 months of age) according to the Ages and Stages Questionnaire-3 (ASQ-3). The levels of reliability of the ASQ-3 for each of the age groups were acceptable, with a range of α = .77 to α = .88. Regarding inter-rater reliability (parents vs. teachers), moderate correlation levels were observed. Discussion and conclusion: The results obtained suggest that this is a screening instrument that reliably evaluates the five areas of development that make up the ASQ-3 in pre-school children. This represents an opportunity to continue studying the psychometric characteristics of validity of this instrument in representative samples of Mexican children to optimize the process of early childhood development monitoring.

Resumen: Introducción: La vigilancia del desarrollo infantil contempla la promoción del desarrollo en el niño sano y la detección de retrasos e indicadores tempranos de trastornos que se inician en los primeros cinco años de vida por medio de pruebas de tamizaje de fácil aplicación, calificación y de bajo costo. Objetivo: Evaluar la fiabilidad interna y confiabilidad interevaluador del Cuestionario de Edades y Etapas-3 (ASQ-3) en preescolares mexicanos. Método: Se aplicó el ASQ-3 a padres y/o tutores de niños de edades entre 33 y 60 meses que asistían a Estancias de Desarrollo Infantil (CENDIS) del sector público y privado de la Ciudad de México. Resultados: Se obtuvieron un total de n = 1052 cuestionarios, agrupados en seis grupos de edad (33, 36, 42, 48, 54 y 60 meses de edad) de acuerdo con el ASQ-3. Los niveles de confiabilidad de los ASQ-3 para cada uno de los grupos de edad fueron aceptables con un rango de α =. 77 a α =. 88. Respecto a la confiabilidad interevaluador (padres vs. maestros), se observaron niveles de correlación moderados. Discusión y conclusión: Los resultados obtenidos sugieren que es un instrumento de tamizaje que evalúa de forma fidedigna las cinco áreas del desarrollo que conforman el ASQ-3 en los preescolares. Ello representa una oportunidad para seguir estudiando las características psicométricas de validez de este instrumento en muestras representativas de niños mexicanos con la finalidad de optimizar el proceso de vigilancia del desarrollo en edades tempranas.