Energy Metabolism

A phenomenological model of muscle energy expenditure developed in part I of the paper, is utilized as a physiological cost function to estimate the muscle forces during normal locomotion. The model takes into account muscular behaviors typically observed during human gait, such as submaximal activation, variable muscular contraction conditions and muscular fiber type. The solution of the indeterminate biomechanical problem is obtained by integrating multibody dynamics and the global static optimization technique that considers the whole motion. The results for an application case indicate the important role of muscle groups in coordinating multijoint motion with the objective of minimizing metabolic costs of transport during locomotion.

Competitive diving involves grace, power, balance, and flexibility, which all require satisfying daily energy and nutrient needs. Divers are short, well-muscled, and lean, giving them a distinct biomechanical advantage. Although little diving-specific nutrition research on performance and health outcomes exists, there is concern that divers are excessively focused on body weight and composition, which may result in reduced dietary intake to achieve desired physique goals. This will result in low energy availability, which may have a negative impact on their power-to-weight ratio and health risks. Evidence is increasing that restrictive dietary practices leading to low energy availability also result in micronutrient deficiencies, premature fatigue, frequent injuries, and poor athletic performance. On the basis of daily training demands, estimated energy requirements for male and female divers are 3,500 kcal and 2,650 kcal, respectively. Divers should consume a diet that provides 3-8 g/kg/day of carbohydrate, with the higher values accommodating growth and development. Total daily protein intake (1.2-1.7 g/kg) should be spread evenly throughout the day in 20 to 30 g amounts and timed appropriately after training sessions. Divers should consume nutrient-dense foods and fluids and, with medical supervision, certain dietary supplements (i.e., calcium and iron) may be advisable. Although sweat loss during indoor training is relatively low, divers should follow appropriate fluid-intake strategies to accommodate anticipated sweat losses in hot and humid outdoor settings. A multidisciplinary sports medicine team should be integral to the daily training environment, and suitable foods and fluids should be made available during prolonged practices and competitions.

Fractal analysis in cancer cell investigation provided meaningful insights into the relationship between morphology and phenotype. Some reports demonstrated that changes in cell shape precede and trigger dramatic modifications in both gene expression and enzymatic function. Nonetheless, metabolomic pattern in cells undergoing shape changes have been not still reported. Our study was aimed to investigate if modifications in cancer cell morphology are associated to relevant transition in tumour metabolome, analyzed by nuclear magnetic resonance spectroscopy and principal component analysis. MCF-7 and MDA-MB-231 breast cancer cells, exposed to an experimental morphogenetic field, undergo a dramatic change in their membrane profiles. Both cell lines recover a more rounded shape, loosing spindle and invasive protrusions, acquiring a quite "normal" morphology. This result, quantified by fractal analysis, shows that normalized bending energy (a global shape characterization expressing the amount of energy needed to transform a specific shape into its lowest energy state) decreases after 48 h. Later on, a significant shift from a high to a low glycolytic phenotype was observed on both cell lines: glucose flux begins to drop off at 48 h, leading to reduced lactate accumulation, and fatty acids and citrate synthesis slow-down after 72 h. Moreover, de novo lipidogenesis is inhibited and nucleotide synthesis is reduced, as indicated by the positive correlation between glucose and formate. In conclusion, these data indicate that the reorganization of cell membrane architecture, induced by environmental cues, is followed by a relevant transition of the tumour metabolome, suggesting cells undergo a dramatic phenotypic reversion.

BLAAKAND THE NUGENOB CONSORTIUM. Impaired fat-induced thermogenesis in obese subjects: the NUGENOB study. Obesity. 2007;15: 653-663. Objectives: To study energy expenditure before and 3 hours after a high-fat load in a large cohort of obese subjects (n ϭ 701) and a lean reference group (n ϭ 113). Research Methods and Procedures: Subjects from seven European countries underwent a 1-day clinical study with a liquid test meal challenge containing 95% fat (energy con-tent was 50% of estimated resting energy expenditure). Fasting and 3-hour postprandial energy expenditures, as well as metabolites and hormones, were determined. Results: Obese subjects had a reduced postprandial energy expenditure after the high-fat load, independent of body composition, age, sex, research center, and resting energy expenditure, whereas within the obese group, thermogenesis increased again with increasing BMI category. Additionally, insulin resistance, habitual physical activity, postprandial plasma triacylglycerols, and insulin were all independently positively related to the postprandial energy expenditure. Resting energy expenditure, adjusted for fat-free mass, increased with degree of obesity, a difference that disappeared after adjustment for fat mass. Furthermore, insulin resistance, fasting plasma free fatty acids, and cortisol were positively associated, whereas fasting plasma leptin and insulin-like growth factor-1 were negatively associated, with resting energy expenditure. Discussion: The 3-hour fat-induced thermogenic response is reduced in obesity. It remains to be determined whether this blunted thermogenic response is a contributory factor or an adaptive response to the obese state. REE, resting energy expenditure; HOMA IR , homeostasis model assessment of insulin resistance; AU, arbitrary units; EI, energy intake; FFA, free fatty acid; IGF-1, insulin-like growth factor-1. Model 1 includes the indicated variables in addition to FM, FFM, and center. Model 2 includes the indicated variables in addition to Model 1. p Values of the multiple regression analysis are indicated in the right column.

Background: Root-knot nematodes are sedentary endoparasites that can infect more than 3000 plant species. Root-knot nematodes cause an estimated $100 billion annual loss worldwide. For successful establishment of the root-knot nematode in its host plant, it causes dramatic morphological and physiological changes in plant cells. The expression of some plant genes is altered by the nematode as it establishes its feeding site. Results: We examined the expression of soybean (Glycine max) genes in galls formed in roots by the root-knot nematode, Meloidogyne incognita, 12 days and 10 weeks after infection to understand the effects of infection of roots by M. incognita. Gene expression was monitored using the Affymetrix Soybean GeneChip containing 37,500 G. max probe sets. Gene expression patterns were integrated with biochemical pathways from the Kyoto Encyclopedia of Genes and Genomes using PAICE software. Genes encoding enzymes involved in carbohydrate and cell wall metabolism, cell cycle control and plant defense were altered. Conclusions: A number of different soybean genes were identified that were differentially expressed which provided insights into the interaction between M. incognita and soybean and into the formation and maintenance of giant cells. Some of these genes may be candidates for broadening plants resistance to root-knot nematode through over-expression or silencing and require further examination.