Boost invariant marginally trapped surfaces in Minkowski 4-space

The extremal and partly marginally trapped surfaces in Minkowski 4-space, which are invariant under the group of boost isometries, are classified. Moreover, it is shown that there do not exist extremal surfaces of this kind with constant Gaussian curvature. A procedure is given in order to construct a partly marginally trapped surface by gluing two marginally trapped surfaces which are invariant under the group of boost isometries. As an application, a proper star-surface is constructed.Comment: 13 pages, comment added in section

Enhanced circulating retinol and non-esterified fatty acids in pregnancies complicated with intrauterine growth restriction

IUGR (intrauterine growth restriction) increases the incidence of perinatal complications and, although several placental transport functions have been shown to be altered in pregnancies complicated by IUGR, the mechanism behind it is not well understood. The aim of the present study was to investigate factors in maternal and cord blood plasma from normal and IUGR-complicated pregnancies associated with the body weight of newborns. At the time of Caesarean section, 24 women with IUGR pregnancies were compared with a group of 30 normal controls with AGA (appropriate gestational age) fetuses who were studied at Caesarean section, which took place 5 weeks later than IUGR pregnancies, and also to a group of 25 non-delivered gestational age-matched control pregnant women (AGA-35wk). Maternal plasma retinol, gamma- and alpha-tocopherol, NEFAs (non-esterified fatty acids), and palmitic, palmitoleic, gamma-linolenic and arachidonic acids were higher in women with IUGR pregnancies than in AGA-35wk controls, whereas stearic and alpha-linolenic acids were lower. Smaller differences were found when comparing these variables for IUGR and AGA women. However, umbilical vein plasma gamma-tocopherol, cholesterol, triacylglycerols and NEFAs were higher in the IUGR group than in the AGA group, whereas arachidonic acid was lower. Maternal plasma retinol and NEFAs were the only variables negatively correlated with birthweight when multiple linear regressions were analysed. In conclusion, the increased levels of circulating retinol and NEFAs in maternal plasma are negatively associated with birth and placental weights, which may reflect an impaired placental transfer in IUGR pregnancies. As retinoids are involved in the control of gene transcription, it is proposed that a decrease in placental transfer of retinol could underlie the metabolic dysfunction of IUGR pregnancies

Leptin concentration, obesity, and plasma non-esterified fatty acid levels in children

The association between obesity and higher non-esterified fatty acid (NEFA) levels has been established in adults. In contrast, lower NEFA levels have been described in children with obesity although the reason behind this association remains unclear. Leptin, which regulates body weight and plays a role in lipolysis, could be involved in this relationship. We evaluated the influence of leptin in the association between obesity and NEFA concentrations in children, analyzing two cohorts including 684 6- to 8-year-olds and 836 12- to 16-year-old children, respectively. After adjusting by leptin, insulin levels remained significantly higher in adolescents with obesity as compared with levels in those without obesity. However, insulin levels showed no differences between prepubertal children with and without obesity. The significantly lower NEFA concentrations observed in 6- to 8-year-old girls with obesity disappeared when comparing NEFA levels between girls with and without obesity after adjusting by leptin. We report an influence of leptin levels on the association between obesity and insulin and NEFA in young children that is not observed in adolescents. Our findings add information about factors that may contribute to explain the lower NEFA levels described in prepubertal children with obesityThis work was supported by the Instituto de Salud Carlos III (grants number PI 18/01016 and FI 19/00180) and Biobank (grant number FEDER RD09/0076/00101). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscrip

Gestational Diabetes Mellitus Upsets the Proportion of Fatty Acids in Umbilical Arterial but Not Venous Plasma

OBJECTIVE—Neonates of women with gestational diabetes mellitus (GDM) have reduced levels of arachidonic acid (AA) (20:4 n-6) and docosahexaenoic acid (DHA) (22:6 n-3). To assess whether this is the result of impaired placental transfer or endogenous fetal metabolism, fatty acids in umbilical venous and arterial plasma were analyzed in neonates of GDM women

Aging Hallmarks: the benefits of physical exercise

World population has been continuously increasing and progressively aging. Aging is characterized by a complex and intraindividual process associated with nine major cellular and molecular hallmarks, namely, genomic instability, telomere attrition, epigenetic alterations, a loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication. This review exposes the positive antiaging impact of physical exercise at the cellular level, highlighting its specific role in attenuating the aging effects of each hallmark. Exercise should be seen as a polypill, which improves the health-related quality of life and functional capabilities while mitigating physiological changes and comorbidities associated with aging. To achieve a framework of effective physical exercise interventions on aging, further research on its benefits and the most effective strategies is encouraged

Henar Ortega-Senovilla's Quick Files

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Efecto de las interacciones entre antioxidantes sobre la resistencia de las LDL a la oxidación y estudio de los determinantes de las vitaminas antioxidantes liposolubles en la población infantil

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid. Facultad de Ciencias. Departamento de Biología Molecular. Fecha de lectura: 24-09-2004Está ampliamente aceptada la participación de la oxidación de las LDL en la patogenia de la aterosclerosis. El consumo elevado de frutas y hortalizas y la ingesta moderada y regular de vino se consideran una práctica sana para la prevención de la enfermedad cardiovascular, por los antioxidantes que conllevan. Sin embargo, los estudios de intervención con antioxidantes, especialmente vitamina E, han mostrado resultados ambivalentes. El tocoferol, en su acción antioxidante se convierte en radical tocoferilo que, en determinadas condiciones, puede oxidar ácidos grasos. Para que se recupere la acción protectora se requiere la presencia de otros co-antioxidantes que regeneren el tocoferol y eliminen el radical del entomo lipofilico. En este contexto, nos planteamos el estudio de los efectos de la combinación de antioxidantes in vino sobre la resistencia a la oxidación de las LDL. Observamos que la adición de los diferentes antioxidantes al medio de ensayo retrasó efectivamente la oxidación de las LDL inducida por cobre. Al combinar a-tocoferol con ácido ascórbico o con quercetina, un flavonol de solubilidad intermedia que está presente en alta concentración en los derivados de la uva, se produjeron efectos sinérgicos entre ellos. Sin embargo, al combinar a-tocoferol con probucol, muy lipofilico, se produjeron efectos aditivos. También se produjeron efectos sinérgicos al combinar probucol con ácido ascórbico o con quercetina, asi como la quercetina con el ácido ascórbico. Todo ello seilala la importancia del carácter hidrosoluble de uno de ellos, que permita la retirada del radical libre de la lipoproteh, para que se establezca la potenciación del efecto antioxidante. En un segundo objetivo nos planteamos determinar el efecto del tratamiento con probucol sobre la resistencia de las LDL a la oxidación en pacientes con hipercolesterolemia familiar bomozigótica, con alto riesgo cardiovascular. Este tratamiento produjo el efecto hipolipemiante esperado y cambios en la composición de las LDL: el enriquecimiento en probucol se acompañó de un descenso en el contenido de las vitaminas lipofilicas. Con ello se incrementó la resistencia de las LDL a la oxidación, que fue proporcional al contenido en probucol. La adición de quercetina al medio de oxidación incrementó de forma sinérgica el tiempo de latencia de la oxidación. Un caso severo de deficiencia de a-tocoferol, que conduce a la ataxia, se produce como consecuencia de la mutación de la proteina transferidora de a-tocoferol (a-TTP). En consonancia con ello, las LDL de un paciente con esta enfermedad presentaban una alta susceptibilidad a su oxidación in vino, con un tiempo de latencia apenas perceptible. Se instauró el tratamiento con vitamina E intramuscular, que supuso el aumento del contenido de las LDL en a-tocoferol e, inesperadamente, la disminución de y-tocoferol y de licopeno. Con esta pauta se normalizó prácticamente la susceptibilidad de la LDL a la oxidación in vitro. Es más, se incrementó el efecto sinérgico de la quercetina y del ácido ascórbico, lo que sugiere un cambio en la localización del a-tocoferol en las partículas de LDL de estos pacientes. Para determinar el posible efecto del genotipo de apo E sobre las vitaminas antioxidantes liposolubles, se estudió una amplia muestra de niños de 6 a 8 años, donde la influencia de los cambios hormonales y del ambiente es limitada. La concentración media de vitamina E fue de 23,s pmoleslL, que se considera elevada, sin encontrarse ningún caso de deficiencia. Las concentraciones medias de licopeno, a-caroteno y p-caroteno fueron de 0,370, 0,060 y de 0,23 1 pmoledL, y la de retinol fue de 1,02 pmolesn, comparable a la de oms poblaciones infantiles occidentales, con un nivel de desarrollo similar al nuestro. Las concentraciones de estas vitaminas lipofílicas se correlacionaron con las de los lipidos y las apolipoproteinas mayoritarias. Para el a-tocoferol, los determinantes con mayor poder de predicción fueron üiglicéridos, apo A-1 y apo B, explicando el 27,6% de la variabilidad. Para y-tocoferol, licopeno y carotenos, los determinantes fueron las apolipoproteinas, aunque con menor poder de predicción. El retinol también se relacionó de forma lineal con estas apolipoproteinas y con el indice de masa corporal, lo que concuerda con el carácter de indice nuúicional que le aüibuyen a esta vitamina los estudios realizados en población adulta. Al segregar la población según el genotipo de apo E, se observaron diferencias en las concentraciones medias de y-tocoferol, a-tocoferol, licopeno y a-caroteno, que desaparecieron al ajustar por los lipidos y apolipoprotehs, salvo en el caso de los tocoferoles. Analizados los determinantes dentro de los principales genotipos de apo E, se observó que el poder determinante de la apo B se mantenia en todos ellos, el de la apo A-1 desaparecia en los portadores de apo E4, mientras que el de los macilglicéridos se detectaba sólo en los portadores de apo E2. Esta interacción entre los üiglicéridos y la apo E2 puede relacionarse con el menor catabolismo de las VLDL y baja conversión en LDL que se da en estos individuos. Finalmente, en esta población se estudió la capacidad antioxidante total del plasma con un método basado en la reducción del ión ABTS', que previamente se puso a punto para mejorar la linealidad y la cinética con respecto a uno comercial. Se observó que la capacidad antioxidante se relacionaba linealmente con las concentraciones de ácido úrico, b i l i m b h y proteínas totales. En regresión lineal múltiple, el principal determinante fue el ácido úrico y, sólo cuando se analizó la capacidad antioxidante en función del descenso de la absorbancia debida al ión ABTS' a un tiempo determinado, resultaron significativos el licopeno y el a-tocoferol. No se detectaron cambios por efecto del genotipo de apo E. Por lo tanto, y a pesar de la sensibilidad de este método para detectar la presencia de los antioxidantes hidrosolubles, principalmente ácido úrico, su interés como indicador de la resistencia a la peroxidación lipidica es incierta

Angiopoietin-like protein 4 (ANGPTL4) is related to gestational weight gain in pregnant women with obesity

Angiopoietin-like protein 4 (ANGPTL4) is a circulating protein involved in the regulation of adipose tissue metabolism. However, its role in obesity and pregnancy is unknown. To evaluate the relationship between gestational weight gain (GWG) and circulating concentrations of ANGPTL4 in pregnant women with overweight and obesity, weight gain and fasting maternal blood samples of thirty-one pregnant women was drawn at 15, 24 and 32 weeks of gestation. ANGPTL4 concentrations continuously rose throughout gestation, whereas VEGF and leptin did not show the same trend. NEFA and glycerol concentrations remained stable during pregnancy. In contrast, total concentrations of saturated, monounsaturated and n-6 fatty acids, but not n-3 fatty acids, increased with pregnancy. In multiple regression analysis, the increase in plasma ANGPTL4 and decrease in linoleic acid concentrations were the most significant predictors of GWG, although only ANGPTL4 was significantly associated with the weight gain from early pregnancy (area under the ROC curve was 0.80 p < 0.01(95% CI 0.61–0.99)). In conclusion, in pregnant women with overweight and obesity, an increase in plasma ANGPTL4 concentrations throughout pregnancy is positively associated with GWG and could be used as an early marker of increased susceptibility to excess gestational weight gain

Lack of relationship between cord serum angiopoietin-like protein 4 (ANGPTL4) and lipolytic activity in human neonates born by spontaneous delivery.

BackgroundLigands of peroxisome-proliferator activated receptors (PPARs), such as non-esterified fatty acids (NEFAs), induce expression of angiopoietin-like protein 4 (ANGPTL4). Recently ANGPTL4 has been reported to be a mediator of intracellular adipose lipolysis induced by glucocorticoids.ObjectiveTo determine the concentrations of ANGPTL4 in cord serum of neonates born by spontaneous vaginal delivery (SVD) and by pre-labor cesarean section (CS) from healthy women, and to relate them to parameters of neonatal lipolytic activity at birth.MeasurementsIn 54 neonates born by SVD and in 56 neonates born by CS, arterial cord blood was drawn to determine insulin, cortisol, triacylglycerols (TAGs), glycerol, non-esterified fatty acids (NEFAs), individual fatty acids, ANGPTL4, adiponectin, retinol binding protein 4 (RBP4) and leptin.ResultsBirth weight and neonatal fat mass in SVD and CS showed no difference, but the concentrations of glycerol, adiponectin, RBP4, NEFAs and most individual fatty acids were higher in cord serum of neonates born by SVD compared to CS, indicating a higher adipose tissue breakdown in the SVD group. The concentrations of TAG and cortisol were also higher and that of insulin was lower in cord serum of SVD compared to the CS group. However, the concentration in cord serum of ANGPTL4 did not differ between the two groups and no positive correlation with either NEFA or glycerol concentrations were detected.ConclusionANGPTL4 is known to stimulate lipolysis in adults, but does not appear to mediate the increased activity in SVD, indicating the presence of different regulatory inputs