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we all inherit and acquire different characteristics. When we experience a treatment aimed at changing our physiology, these characteristics may modify the effect of the treatment, making it more or less beneficial, harmful, or ineffective in different individuals. The issue of individual responses

The volume of red blood cells (VRBC) is used routinely in the diagnostic workup of polycythemia, in assessing the efficacy of erythropoietin administration, and to study factors affecting oxygen transport. However, errors of various methods of measurement of VRBCand related parameters are not well characterized. We meta-analyzed 346 estimates of error of measurement of VRBCfor techniques based on Evans blue (VRBC,Evans),51chromium-labeled red blood cells (VRBC,51Cr), and carbon monoxide (CO) rebreathing (VRBC,CO), as well as hemoglobin mass with the carbon-monoxide method (MHb,CO), in athletes and active and inactive subjects undergoing various experimental and control treatments lasting minutes to months. Subject characteristics and experimental treatments had little effect on error of measurement, but measures with the smallest error showed some increase in error with increasing time between trials. Adjusted to 1 day between trials and expressed as coefficients of variation, mean errors for MHb,CO(2.2%; 90% confidence interval 1.4–3.5%) and VRBC,51Cr(2.8%; 2.4–3.2%) were much less than those for VRBC,Evans(6.7%; 4.9–9.4%) and VRBC,CO(6.7%; 3.4–14%). Most of the error of VRBC,Evanswas due to error in measurement of volume of plasma via Evans blue dye (6.0%; 4.5–7.8%), which is the basis of VRBC,Evans. Most of the error in VRBC,COwas due to estimates from laboratories with a relatively large error in MHb,CO, the basis of VRBC,CO. VRBC,51Crand MHb,COare the best measures for research on blood-related changes in oxygen transport. With care, VRBC,Evansis suitable for clinical applications of blood-volume measurement.

Epigenomic regulation of the transcriptome by DNA methylation and posttranscriptional gene silencing by miRNAs are potential environmental modulators of skeletal muscle plasticity to chronic exercise in healthy and diseased populations. We utilized transcriptome networks to connect exercise-induced differential methylation and miRNA with functional skeletal muscle plasticity. Biopsies of the vastus lateralis were collected from middle-aged Polynesian men and women with morbid obesity (44 kg/m2 ± 10) and Type 2 diabetes before and following 16 wk of resistance ( n = 9) or endurance training ( n = 8). Longitudinal transcriptome, methylome, and microRNA (miRNA) responses were obtained via microarray, filtered by novel effect-size based false discovery rate probe selection preceding bioinformatic interrogation. Metabolic and microvascular transcriptome topology dominated the network landscape following endurance exercise. Lipid and glucose metabolism modules were connected to: microRNA (miR)-29a; promoter region hypomethylation of nuclear receptor factor ( NRF1) and fatty acid transporter ( SLC27A4), and hypermethylation of fatty acid synthase, and to exon hypomethylation of 6-phosphofructo-2-kinase and Ser/Thr protein kinase. Directional change in the endurance networks was validated by lower intramyocellular lipid, increased capillarity, GLUT4, hexokinase, and mitochondrial enzyme activity and proteome. Resistance training also lowered lipid and increased enzyme activity and caused GLUT4 promoter hypomethylation; however, training was inconsequential to GLUT4, capillarity, and metabolic transcriptome. miR-195 connected to negative regulation of vascular development. To conclude, integrated molecular network modelling revealed differential DNA methylation and miRNA expression changes occur in skeletal muscle in response to chronic exercise training that are most pronounced with endurance training and topographically associated with functional metabolic and microvascular plasticity relevant to diabetes rehabilitation.

case studies are rare in our journals and for good reason: without a sample, it is hard to assess the representativeness or uniqueness of an individual. The case studies that do get published are therefore so obviously exceptional that we cannot help but be interested in where nature or nurture has