8 research outputs found
Modelling the associations between fat-free mass, resting metabolic rate and energy intake in the context of total energy balance
© 2016 Macmillan Publishers Limited.The relationship between body composition, energy expenditure and ad libitum energy intake (EI) has rarely been examined under conditions that allow any interplay between these variables to be disclosed.Objective:The present study examined the relationships between body composition, energy expenditure and EI under controlled laboratory conditions in which the energy density and macronutrient content of the diet varied freely as a function of food choice.Methods:Fifty-nine subjects (30 men: mean body mass index=26.7±4.0 kg m-2; 29 women: mean body mass index=25.4±3.5 kg m-2) completed a 14-day stay in a residential feeding behaviour suite. During days 1 and 2, subjects consumed a fixed diet designed to maintain energy balance. On days 3-14, food intake was covertly measured in subjects who had ad libitum access to a wide variety of foods typical of their normal diets. Resting metabolic rate (RMR; respiratory exchange), total daily energy expenditure (doubly labelled water) and body composition (total body water estimated from deuterium dilution) were measured on days 3-14.Results:Hierarchical multiple regression indicated that after controlling for age and sex, both fat-free mass (FFM; P<0.001) and RMR (P<0.001) predicted daily EI. However, a mediation model using path analysis indicated that the effect of FFM (and fat mass) on EI was fully mediated by RMR (P<0.001).Conclusions:These data indicate that RMR is a strong determinant of EI under controlled laboratory conditions where food choice is allowed to freely vary and subjects are close to energy balance. Therefore, the conventional adipocentric model of appetite control should be revised to reflect the influence of RMR
Energy expenditure of rugby players during a 14-day in-season period, measured using doubly labelled water.
Criterion data for total energy expenditure (TEE) in elite rugby are lacking, which prediction equations may not reflect accurately. This study quantified TEE of 27 elite male rugby league (RL) and rugby union (RU) players (U16, U20, U24 age groups) during a 14-day in-season period using doubly labelled water (DLW). Measured TEE was also compared to estimated, using prediction equations. Resting metabolic rate (RMR) was measured using indirect calorimetry, and physical activity level (PAL) estimated (TEE:RMR). Differences in measured TEE were unclear by code and age (RL, 4369 ± 979; RU, 4365 ± 1122; U16, 4010 ± 744; U20, 4414 ± 688; U24, 4761 ± 1523 Kcal.day-1). Differences in PAL (overall mean 2.0 ± 0.4) were unclear. Very likely differences were observed in RMR by code (RL, 2366 ± 296; RU, 2123 ± 269 Kcal.day-1). Differences in relative RMR between U20 and U24 were very likely (U16, 27 ± 4; U20, 23 ± 3; U24, 26 ± 5 Kcal.kg-1.day-1). Differences were observed between measured and estimated TEE, using Schofield, Cunningham and Harris-Benedict equations for U16 (187 ± 614, unclear; -489 ± 564, likely and -90 ± 579, unclear Kcal.day-1), U20 (-449 ± 698, likely; -785 ± 650, very likely and -452 ± 684, likely Kcal.day-1) and U24 players (-428 ± 1292; -605 ± 1493 and -461 ± 1314 Kcal.day-1, all unclear). Rugby players have high TEE, which should be acknowledged. Large inter-player variability in TEE was observed demonstrating heterogeneity within groups, thus published equations may not appropriately estimate TEE
Natural and genetically engineered proteins for tissue engineering
To overcome the limitations of traditionally used autografts, allografts and, to a lesser
extent, synthetic materials, there is the need to develop a new generation of scaffolds with
adequate mechanical and structural support, control of cell attachment, migration, proliferation
and differentiation and with bio-resorbable features. This suite of properties would
allow the body to heal itself at the same rate as implant degradation. Genetic engineering
offers a route to this level of control of biomaterial systems. The possibility of expressing
biological components in nature and to modify or bioengineer them further, offers a path
towards multifunctional biomaterial systems. This includes opportunities to generate new
protein sequences, new self-assembling peptides or fusions of different bioactive domains
or protein motifs. New protein sequences with tunable properties can be generated that
can be used as new biomaterials.
In this review we address some of the most frequently used proteins for tissue engineering
and biomedical applications and describe the techniques most commonly used to functionalize
protein-based biomaterials by combining them with bioactive molecules to enhance
biological performance. We also highlight the use of genetic engineering, for protein heterologous
expression and the synthesis of new protein-based biopolymers, focusing the
advantages of these functionalized biopolymers when compared with their counterparts
extracted directly from nature and modified by techniques such as physical adsorption or
chemical modification.Silvia Gomes thanks the Portuguese Foundation for Science and Technology (FCT) for providing her a PhD Grant (SFRH/BD/28603/2006). This work was carried out under the scope of the FIND & BIND project funded by the agency EU-EC (FP7 program), the FCT R&D project Proteo-Light (PTDC/FIS/68517/2006) funded by the FCT agency, the Chimera project (PTDC/EBB-EBI/109093/2008) funded by the FCT agency, the NIH (P41 EB002520) Tissue Engineering Resource Center and the NIH (EB003210 and DE017207)