Modulation of Transaminase Activity by Encapsulation in Temperature-Sensitive Poly(N-acryloyl glycinamide) Hydrogels.

Smart hydrogels hold much potential for biocatalysis, not only for the immobilization of enzymes, but also for the control of enzyme activity. We investigated upper critical solution temperature-type poly N-acryloyl glycinamide (pNAGA) hydrogels as a smart matrix for the amine transaminase from Bacillus megaterium (BmTA). Physical entrapment of BmTA in pNAGA hydrogels results in high immobilization efficiency (>89 %) and high activity (97 %). The temperature-sensitiveness of pNAGA is preserved upon immobilization of BmTA and shows a gradual deswelling upon temperature reduction. While enzyme activity is mainly controlled by temperature, deactivation tended to be higher for immobilized BmTA (≈62-68 %) than for free BmTA (≈44 %), suggesting a deactivating effect due to deswelling of the pNAGA gel. Although the deactivation in response to hydrogel deswelling is not yet suitable for controlling enzyme activity sufficiently, it is nevertheless a good starting point for further optimization.

Multidimensional prediction approach in the assessment of male volleyball players' optimal body composition: the case of two elite European teams / Enfoque de predicción multidimensional en la evaluación de la composición corporal óptima de los jugadores de voleibol masculino: el caso de dos equipos europeos de élite

SUMMARY: This research aimed to create a multidimensional equation for predicting an optimal body composition model for elite-level European male volleyball players. The subject sample consisted of 36 elite volleyball players: national team members from two European countries - Slovenia and Serbia - in the 2017 season. Measurement of body composition was carried out using electrical multichannel bioimpedance (BIA - InBody 720), in which 11 variables were used (body height as a longitudinal one, and the other 10 as a system of body composition indicators). Based on the results of descriptive statistics, we can state that elite European male volleyball players are tall, heavy, and with nutritional status at the level of 198.5?6.5 cm, 92.3?5.9 kg and 23.44?1.44 kg•m-2, respectively. The percentage of body fat in the whole sample was 7.91?3.03 %, and the skeletal muscle mass index averaged 12.49?0.80 kg•m-2. For the evaluation and prediction of an optimal body composition model of elite male volleyball players, a multidimensional score (BC_Score) was defined, based on a simple, but sport-specific and playing position-sensitive model equation based on three dominant body characteristics of elite volleyball players: BH, PBF, and SMMI. In this manner, coaches can have a tool for managing the body composition status of players according to position, in terms of a deterministic, fully controlled system.

RESUMEN: Esta investigación tuvo como objetivo crear una ecuación multidimensional para predecir un modelo de composición corporal óptimo para los jugadores de voleibol masculinos europeos de élite. La muestra consistió en 36 jugadores de voleibol de élite, miembros del equipo nacional de dos países, Eslovenia y Serbia, en la temporada 2017. La composición corporal se realizó mediante bioimpedancia eléctrica multicanal (BIA - InBody 720), en la que se utilizaron 11 variables (la altura corporal como longitudinal y las otras 10 como sistema de indicadores de composición corporal). Con base en los resultados de las estadísticas descriptivas, observamos que los jugadores de voleibol de élite europeos son altos, pesados y con un estado nutricional de 198,5 ? 6,5 cm, 92,3 ? 5,9 kg y 23,44 ? 1,44 kg•m-2, respectivamente. El porcentaje de grasa corporal en toda la muestra fue de 7,91 ? 3,03 % y el índice de masa del músculo esquelético promedió 12,49 ? 0,80 kg•m-2. Para la evaluación y predicción de un modelo de composición corporal óptimo de jugadores de voleibol masculino de élite, se definió una puntuación multidimensional (BC_Score), basada en una ecuación de modelo simple, pero específica del deporte y sensible a la posición de juego, basada en tres características corporales dominantes de la élite. Jugadores de voleibol: BH, PBF y SMMI. De esta manera, los entrenadores pueden disponer de una herramienta para gestionar el estado de la composición corporal de los jugadores según la posición, en términos de un sistema determinista y totalmente controlado.

Are the Parameters of Novel Two-Point Force-Velocity Model Generalizable in Leg Muscles?

The two-point force-velocity model allows the assessment of the muscle mechanical capacities in fast, almost fatigue-free conditions. The aim of this study was to investigate the concurrent validity of the two-point parameters with directly measured force and power and to examine the generalization of the two-point parameters across the different functional movement tests of leg muscles. Twelve physically active participants were tested performing three functional lower limb maximal tests under two different magnitudes of loads: countermovement jumps, maximal cycling sprint, and maximal force under isokinetic conditions of the knee extensors. The results showed that all values from the two-point model were higher than the values from the standard tests (p < 0.05). We also found strong correlations between the same variables from different tests (r ≥ 0.84; p < 0.01), except for force in maximal cycling sprint, where it was low and negligible (r = -0.24). The results regarding our second aim showed that the correlation coefficients between the same two-point parameters of different lower limb tests ranged from moderate to strong (r -0.47 to 0.72). In particular, the relationships were stronger between power variables than between force variables and somewhat stronger between standard tests and two-point parameters. We can conclude that mechanical capacities of the leg muscles can be partially generalized between different functional tests.

Assessment of the two-point method applied in field conditions for routine testing of muscle mechanical capacities in a leg cycle ergometer.

PURPOSE: The aim of this study was to compare the reliability and magnitude of the force-velocity (F-V) relationship parameters [maximum force (F0), maximum velocity (V0), F-V slope, and maximum power (P0)] obtained through the application of only two loads (i.e., two-point method) vs. six loads (i.e., multiple-point method). METHODS: Ten physically active men (age 19.5 ± 0.9 years, body mass 79.0 ± 9.0 kg, height 183.9 ± 8.4 cm) conducted four testing sessions after a preliminary familiarization session with the leg cycle ergometer exercise. In a counterbalanced order, subjects performed two sessions of the multiple-point method (six loads applied for the F-V modeling) over 1 week and two sessions of the two-point method (only the lightest and heaviest loads were applied) over another week. RESULTS: The main findings revealed that (I) the reliability of the F-V relationship parameters was very high and generally of comparable magnitude for both the multiple- [coefficient of variation (CV) range 1.91-3.94%; intraclass correlation coefficient (ICC) range 0.72-0.99] and two-point methods [CV range 1.41-4.62%; ICC range 0.76-0.95], (II) the magnitude of the same parameters obtained from both methods was highly correlated (r > 0.80), and (III) the P0 assessed from the multiple-point method was significantly lower than the obtained from the two-point method [P = 0.041; effect size (ES) 0.36] due to a significant decrease in F0 (P = 0.039; ES 0.41) with no significant differences observed for V0 (P = 0.570; ES - 0.15). CONCLUSIONS: These results support the two-point method as a reliable, valid, and fatigue-free procedure of assessing the muscle mechanical capacities through the F-V relationship.