Protein type, protein dose, and age modulate dietary protein digestion and phenylalanine absorption kinetics and plasma phenylalanine availability in humans

This is the final version. Available from the publisher via the DOI in this record.BACKGROUND: Dietary protein ingestion stimulates muscle protein synthesis by providing amino acids to the muscle. The magnitude and duration of the postprandial increase in muscle protein synthesis rates are largely determined by dietary protein digestion and amino acid absorption kinetics. OBJECTIVE: We assessed the impact of protein type, protein dose, and age on dietary protein digestion and amino acid absorption kinetics in vivo in humans. METHODS: We included data from 18 randomized controlled trials with a total of 602 participants [age: 53 ± 23 y; BMI (kg/m2): 24.8 ± 3.3] who consumed various quantities of intrinsically l-[1-13C]-phenylalanine-labeled whey (n = 137), casein (n = 393), or milk (n = 72) protein and received intravenous infusions of l-[ring-2H5]-phenylalanine, which allowed us to assess protein digestion and phenylalanine absorption kinetics and the postprandial release of dietary protein-derived phenylalanine into the circulation. The effect of aging on these processes was assessed in a subset of 82 young (aged 22 ± 3 y) and 83 older (aged 71 ± 5 y) individuals. RESULTS: A total of 50% ± 14% of dietary protein-derived phenylalanine appeared in the circulation over a 5-h postprandial period. Casein ingestion resulted in a smaller (45% ± 11%), whey protein ingestion in an intermediate (57% ± 10%), and milk protein ingestion in a greater (65% ± 13%) fraction of dietary protein-derived phenylalanine appearing in the circulation (P < 0.001). The postprandial availability of dietary protein-derived phenylalanine in the circulation increased with the ingestion of greater protein doses (P < 0.05). Protein digestion and phenylalanine absorption kinetics were attenuated in older when compared with young individuals, with 45% ± 10% vs. 51% ± 14% of dietary protein-derived phenylalanine appearing in the circulation, respectively (P = 0.001). CONCLUSIONS: Protein type, protein dose, and age modulate dietary protein digestion and amino acid absorption kinetics and subsequent postprandial plasma amino acid availability in vivo in humans. These trials were registered at clinicaltrials.gov as NCT00557388, NCT00936039, NCT00991523, NCT01317511, NCT01473576, NCT01576848, NCT01578590, NCT01615276, NCT01680146, NCT01820975, NCT01986842, and NCT02596542, and at http://www.trialregister.nl as NTR3638, NTR3885, NTR4060, NTR4429, and NTR4492

Empowering self-direction in return to work of employees with low and high levels of education:A qualitative comparative study

BACKGROUND: Dutch legislation encourages active participation of employees in their return-to-work (RTW) process. Empowering leadership may support employees' self-direction in this process (i.e. by allowing and enabling their involvement in decision-making). OBJECTIVE: Building upon a previous study, we aimed to study (1) how representatives of a university, i.e. an employer for employees with high levels of education (EH), manage RTW, (2) the similarities and differences between the RTW management of employers (or representatives thereof) of employees with low (EL) and high levels of education, and (3) the degree to which the employers' roles resemble empowering leadership. METHODS: Qualitative methodology was applied. A thematic analysis of interview transcripts (rq1) was followed by a comparison of themes (rq2) and pattern matching (rq3). RESULTS: (1) EH tend to engage in dialogue and accommodate their employees as much as possible. (2) EL and EH showed several similarities, such as aiming to meet legal requirements on RTW management. Compared to EL, EH tend to focus more on facilitating employees. (3) Empowering leadership seems to be more common among EH. CONCLUSIONS: Compared to employees with low levels of education, those with high levels of education may be granted more opportunity to self-direct their RTW. The study results provide starting points for employers for employees with both low and high levels of education who aim to enable employees' self-direction in RTW, and help them to develop empowering leadership styles

Empowering self-direction in return to work of employees with low and high levels of education: A qualitative comparative study

BACKGROUND: Dutch legislation encourages active participation of employees in their return-to-work (RTW) process. Empowering leadership may support employees' self-direction in this process (i.e. by allowing and enabling their involvement in decision-making). OBJECTIVE: Building upon a previous study, we aimed to study (1) how representatives of a university, i.e. an employer for employees with high levels of education (EH), manage RTW, (2) the similarities and differences between the RTW management of employers (or representatives thereof) of employees with low (EL) and high levels of education, and (3) the degree to which the employers' roles resemble empowering leadership. METHODS: Qualitative methodology was applied. A thematic analysis of interview transcripts (rq1) was followed by a comparison of themes (rq2) and pattern matching (rq3). RESULTS: (1) EH tend to engage in dialogue and accommodate their employees as much as possible. (2) EL and EH showed several similarities, such as aiming to meet legal requirements on RTW management. Compared to EL, EH tend to focus more on facilitating employees. (3) Empowering leadership seems to be more common among EH. CONCLUSIONS: Compared to employees with low levels of education, those with high levels of education may be granted more opportunity to self-direct their RTW. The study results provide starting points for employers for employees with both low and high levels of education who aim to enable employees' self-direction in RTW, and help them to develop empowering leadership styles

Can we have our cake and still eat it? A review of flexibility in the structural spatial development and passenger transport relation in developing countries

With growing urban populations, higher mobility needs, limited available space for transport infrastructure, and the increasing need for more attractive urban areas, these urban areas are faced with a complex dilemma, which gets more challenging by the day. This paper examines the role of flexibility in the relationship between structural spatial development and passenger transport, its economic, environmental, and social perspectives, the long-term impacts of this relationship and the role of this relationship in developing countries. The paper identifies the need for a better understanding of long-term flexibility in development options in order to make better future-proof decisions as a key research avenue, and sets a pathway to achieve this. Main research gaps as identified in the paper include the lack of understanding on the potential for flexibility in optimizing the structural spatial development and passenger transport relationship, the valuation of flexibility, and the application of flexibility approaches in developing countries. This paper emphasizes the importance of acting sooner rather than later, since the future costs of sub-optimal development are rising by the day and the bill is being pushed towards future generations

Comprehensive overview of the quality of plant- And animal-sourced proteins based on the digestible indispensable amino acid score

Indispensable amino acid (IAA) composition and standardized ileal digestibility (SID) of five animal- and 12 plant-based proteins were used to calculate their respective Digestible Indispensable Amino Score (DIAAS) according to the three age categories defined by the Food and Agriculture Organization (FAO). Mean IAA content and mean SID obtained from each protein dataset were subsequently used to simulate optimal nutritional quality of protein mixtures. Datasets revealed considerable variation in DIAAS within the same protein source and among different protein sources. Among the selected protein sources, and based on the 0.5- to 3-year-old reference pattern, pork meat, casein, egg, and potato proteins are classified as excellent quality proteins with an average DIAAS above 100. Whey and soy proteins are classified as high-quality protein with an average DIAAS ≥75. Gelatin, rapeseed, lupin, canola, corn, hemp, fava bean, oat, pea, and rice proteins are classified in the no quality claim category (DIAAS &lt;75). Potato, soy, and pea proteins can complement a broad range of plant proteins, leading to higher DIAAS when supplied in the form of protein mixtures and at specific ratios. Such complementarity highlights the potential to achieve an optimal nutritional efficiency with plant proteins alone

The single biopsy approach is reliable for the measurement of muscle protein synthesis rates in vivo in older men

We aimed to assess the reliability of the single biopsy approach for calculating muscle protein synthesis rates compared with the well described sequential muscle biopsy approach following a primed continuous infusion of L-[ring-2H5]phenylalanine and GC-MS analysis in older men. Two separate experimental infusion protocols, with differing stable isotope amino acid incorporation times, were employed consisting of n = 27 (experiment 1) or n = 9 (experiment 2). Specifically, mixed muscle protein FSR were calculated from baseline plasma protein enrichments and muscle protein enrichments obtained at 90 min or 50 min (1BX SHORT), 210 min or 170 min (1BX LONG), and between the muscle protein enrichments obtained at 90 and 210 min or 50 min and 170 min (2BX) of the infusion for experiments 1 and 2, respectively. In experiment 2, we also assessed the error that is introduced to the single muscle biopsy approach when nontracer naive subjects are recruited for participation in a primed continuous infusion of isotope-labeled amino acids. In experiment 1, applying the individual plasma protein enrichment values to the single muscle biopsy approach resulted in no differences in muscle protein FSR between the 1BX SHORT (0.031 ± 0.003%·h−1), 1BX LONG (0.032 ± 0.002%·h−1), or the 2BX approach (0.034 ± 0.002%·h−1). A significant correlation in muscle protein FSR was observed only between the 1BX LONG and 2BX approach (r = 0.8; P < 0.001). Similar results were observed in experiment 2. In addition, using the single biopsy approach in nontracer naïve state results in a muscle protein FSR that is negative for both the 1BX SHORT (−0.67 ± 0.051%·h−1) and 1BX LONG (−0.19 ± 0.051%·h−1) approaches. This is the first study to demonstrate that the single biopsy approach, coupled with the background enrichment of L-[ring-2H5]-phenylalanine of mixed plasma proteins, generates data that are similar to using the sequential muscle biopsy approach in the elderly population

Automated observation and analysis of earthworm surface behaviour under experimental habitat quality and availability conditions

Currently, the driving factors of active earthworm dispersal across the soil surface are not sufficiently understood, and distances traversed by individual earthworms have rarely been quantified. Research progress has been hampered by the lack of adequate observation methods as well as fast, objective and quantitative measurements of nocturnal earthworm behaviour. In this work, we report on the potential of a new, automated method using infrared-sensitive webcams and computer image analysis. Nightly surface activities of Lumbricus terrestris L. were monitored quantitatively while manipulating levels of disturbance, burrow availability and congener presence in standard observation units. The automated observation system proved to be simple and inexpensive to build, provided reliable quantitative measures of locomotive behaviour without animal isturbance, and considerably reduced human workload and bias. Waterlogging of the burrow zone stimulated surface ctivities around and away from the home burrow as compared to habitat disturbance by pesticide application and vibration. However, dispersing earthworms never settled in prefabricated burrows. Surface activity of individuals subjected to waterlogged conditions was influenced by the availability of alternative habitat. Minimal habitat disturbance (vibration) and the presence of conspecific individuals resulted in an increased amount of burrow-anchored, possibly sexually oriented, behaviour, but reciprocal burrow visits and mating were not observed. Pesticide application did not result in dispersal, increased foraging activities or sexual attraction attempts during this short-term study. The presence, extent and mechanisms of the remote assessment of important cues in the surroundings of the home burrow by L. terrestris need further research. Infrared monitoring opens new research avenues of earthworm surface behaviour studies (e.g. density-dependent dispersal, habitat selection, (re)colonization, invasion).status: publishe