Racial Differences in Heart Rate, Cardiac Autonomic Modulation and Physical Activity in Children

Click the PDF icon to download the abstrac

Plasma prekallikrein levels are positively associated with circulating lipid levels and the metabolic syndrome in children.

Plasma prekallikrein (PK) has been shown to be associated with cardiovascular disease (CVD) and its risk factors, but these associations have not been investigated in children. The present study examined PK activity in relation to well-established cardiovascular risk factors in a cohort of children aged 9–11 years (N = 97). We found a significant and positive association between PK and fasting levels of total cholesterol (p \u3c 0.01), non-high-density lipoprotein cholesterol (p \u3c 0.01), and triglycerides (p \u3c 0.001). In addition, there was a significant association between PK activity and the metabolic syndrome, a clustering of risk factors considered to have an impact on atherosclerosis and CVD mortality. Finally, we found that children with a family history of CVD had significantly elevated PK activity. These novel findings warrant further investigations into the relationship between circulating PK levels and CVD risk factors because PK may be involved in the progression of the disease state. Il est bien connu que la pre´kallicre´ine (PK) est associe´e a` la maladie cardiovasculaire (CVD) et a` ses facteurs de risque, mais ces associations n’ont pas e´te´ ve´rifie´es chez les enfants. Cette e´tude se propose de ve´rifier l’association entre l’activite´ de la PK et les facteurs de risque de CVD aupre`s d’une cohorte d’enfants aˆge´s de 9 a` 11 ans (N = 97). On observe une corre´lation positive significative entre la PK et les variables suivantes : la concentration totale de choleste´rol a` jeun (p \u3c 0,01), les concentrations des lipoprote´ines non a` haute densite´ (p \u3c 0,01) et la concentration des triglyce´rides (p \u3c 0,001). De plus, on observe une corre´lation significative entre l’activite´ de la PK et le syndrome me´tabolique constitue par un ensemble de facteurs ayant un effet sur l’athe´roscle´rose et la mortalite´ due a` la CVD. En dernier lieu, les enfants avec des ante´ce´dents familiaux de CVD pre´sentent une plus importante activite´ de la PK, et ce, de fac¸on significative. Ces premie`res observations sugge`rent d’autres e´tudes sur la relation entre la concentration sanguine de PK et les facteurs de risque de CVD, car la PK pourrait eˆtre implique´e dans la progression de la malad

Low-Level Prenatal and Postnatal Blood Lead Exposure and Adrenocortical Responses to Acute Stress in Children

BACKGROUND: A few recent studies have demonstrated heightened hypothalamic–pituitary–adrenal (HPA) axis reactivity to acute stress in animals exposed to heavy metal contaminants, particularly lead. However, Pb-induced dysregulation of the HPA axis has not yet been studied in humans. OBJECTIVE: In this study, we examined children’s cortisol response to acute stress (the glucocorticoid product of HPA activation) in relation to low-level prenatal and postnatal Pb exposure. METHODS: Children’s prenatal blood Pb levels were determined from cord blood specimens, and postnatal lead levels were abstracted from pediatrician and state records. Children’s adrenocortical responses to an acute stressor were measured using assays of salivary cortisol before and after administration of a standard cold pressor task. RESULTS: Pb exposure was not associated with initial salivary cortisol levels. After an acute stressor, however, increasing prenatal and postnatal blood Pb levels were independently associated with significantly heightened salivary cortisol responses. CONCLUSIONS: Our results suggest that relatively low prenatal and postnatal blood lead levels— notably those below the 10 µg/dL blood lead level identified by the Centers for Disease Control and Prevention for public health purposes—can alter children’s adrenocortical responses to acute stress. The behavioral and health consequences of this Pb-induced HPA dysregulation in children have yet to be determined

Physical Function, Cognitive Function, and Aortic Stiffness in Older Adults

Please view abstract in the attached PDF file

Depressive Symptomology Predicts Nighttime Central Systolic Blood Pressure Dipping in Adults

poste

Academic Performance and Behavioral Patterns

Identifying the factors that influence academic performance is an essential part of educational research. Previous studies have documented the importance of personality traits, class attendance, and social network structure. Because most of these analyses were based on a single behavioral aspect and/or small sample sizes, there is currently no quantification of the interplay of these factors. Here, we study the academic performance among a cohort of 538 undergraduate students forming a single, densely connected social network. Our work is based on data collected using smartphones, which the students used as their primary phones for two years. The availability of multi-channel data from a single population allows us to directly compare the explanatory power of individual and social characteristics. We find that the most informative indicators of performance are based on social ties and that network indicators result in better model performance than individual characteristics (including both personality and class attendance). We confirm earlier findings that class attendance is the most important predictor among individual characteristics. Finally, our results suggest the presence of strong homophily and/or peer effects among university students

An Examination of the Association of Selected Toxic Metals with Total and Central Obesity Indices: NHANES 99-02

It is conceivable that toxic metals contribute to obesity by influencing various aspects of metabolism, such as by substituting for essential micronutrients and vital metals, or by inducing oxidative stress. Deficiency of the essential metal zinc decreases adiposity in humans and rodent models, whereas deficiencies of chromium, copper, iron, and magnesium increases adiposity. This study utilized the NHANES 99-02 data to explore the association between waist circumference and body mass index with the body burdens of selected toxic metals (barium, cadmium, cobalt, cesium, molybdenum, lead, antimony, thallium, and tungsten). Some of the associations were significant direct relationships (barium and thallium), and some of the associations were significant inverse relationships (cadmium, cobalt, cesium, and lead). Molybdenum, antimony, and tungsten had mostly insignificant associations with waist circumference and body mass index. This is novel result for most of the toxic metals studied, and a surprising result for lead because high stored lead levels have been shown to correlate with higher rates of diabetes, and obesity may be a key risk factor for developing diabetes. These associations suggest the possibility that environmental exposure to metals may contribute to variations in human weight gain/loss. Future research, such as prospective studies rather than the cross-sectional studies presented here, is warranted to confirm these findings

Pancreatic Transcription Factors Containing Protein Transduction Domains Drive Mouse Embryonic Stem Cells towards Endocrine Pancreas

Protein transduction domains (PTDs), such as the HIV1-TAT peptide, have been previously used to promote the uptake of proteins into a range of cell types, including stem cells. Here we generated pancreatic transcription factors containing PTD sequences and administered these to endoderm enriched mouse embryonic stem (ES) cells under conditions that were designed to mimic the pattern of expression of these factors in the developing pancreas. The ES cells were first cultured as embryoid bodies and treated with Activin A and Bone morphogenetic protein 4 (BMP4) to promote formation of definitive endoderm. Cells were subsequently plated as a monolayer and treated with different combinations of the modified recombinant transcription factors Pdx1 and MafA. The results demonstrate that each transcription factor was efficiently taken up by the cells, where they were localized in the nuclei. RT-qPCR was used to measure the expression levels of pancreatic markers. After the addition of Pdx1 alone for a period of five days, followed by the combination of Pdx1 and TAT-MafA in a second phase, up-regulation of insulin 1, insulin 2, Pdx1, Glut2, Pax4 and Nkx6.1 was observed. As assessed by immunocytochemistry, double positive insulin and Pdx1 cells were detected in the differentiated cultures. Although the pattern of pancreatic markers expression in these cultures was comparable to that of a mouse transformed β-cell line (MIN-6) and human islets, the expression levels of insulin observed in the differentiated ES cell cultures were several orders of magnitude lower. This suggests that, although PTD-TFs may prove useful in studying the role of exogenous TFs in the differentiation of ES cells towards islets and other pancreatic lineages, the amount of insulin generated is well below that required for therapeutically useful cells