Effects of progressive fatigue and expertise on self-talk content in running: an ambulatory assessment approach

Effects of Progressive Fatigue and Expertise on Self-Talk Content in Running: An Ambulatory Assessment Approach Arne Nieuwenhuys (1)*, Laurens J. Veltman (2), Louise M.A. Braakman-Jansen (2), & Paul A. Davis (3) (1) Behavioural Science Institute, Radboud University Nijmegen, The Netherlands (2) Institute for Behavioral Research, Twente University, The Netherlands (3) Department of Sport Development, Northumbria University, United Kingdom Introduction In this study we investigated how progressive fatigue differentially affects self-talk use (nr. of statements) and content (instructional, motivational, positive, negative) in recreational and competitive runners, by using a new ambulatory assessment method called “PsyqRun” – a smartphone application that enables online assessment of psychological states and variables (e.g. self-perceived exertion, self-talk) during exercise. Methods 42 participants (20 recreational runners, 22 competitive runners) performed a strenuous running exercise in which they attempted to reach a maximal distance over eight 2-minute intervals. Self-perceived exertion (RPE) and self-talk were assessed at the end of every interval by using the PsyqRun application. Heart rate was measured continuously with a heart rate monitor. Results RPE scores and heart rate measurement confirmed that fatigue systematically increased as a function of exercise interval. Under high levels of fatigue (i.e., at later intervals) participants generally reported more self-talk statements than under low levels of fatigue (i.e., at earlier intervals). More specifically, with increasing fatigue, participants’ use of positive and motivational self-talk strongly increased at the cost of instructional self-talk, which strongly decreased. Finally, a marginally significant effect of expertise (p = .058) indicated that competitive runners used more instructional self-talk than recreational runners – also under high levels of fatigue. Discussion Using modern smartphone technology, the current study was the first to provide an online assessment of fatigue and self-talk in running. Findings indicated that participants actively focused on their running technique at the start of the exercise (e.g., “keep running smoothly”) but shifted to self-motivation and perseverance during later intervals, when they became more fatigued (e.g., “just one more interval!”). These results are consistent with research on fatigue and attentional focus and indicate that – with increasing fatigue – runners’ thoughts and attention are automatically drawn inwards towards the monitoring of internal states and processes. Finally, it is suggested that by using more instructional self-talk, competitive runners may be able to maintain a more efficient running technique, also under high levels of fatigue. Further development of the PsyqRun application should clarify this matter, by relating the assessment of self-talk to objective measures of running technique and performance

Lipid-mediated Wnt protein stabilization enables serum-free culture of human organ stem cells

Wnt signalling proteins are essential for culture of human organ stem cells in organoids, but most Wnt protein formulations are poorly active in serum-free media. Here we show that purified Wnt3a protein is ineffective because it rapidly loses activity in culture media due to its hydrophobic nature, and its solubilization requires a detergent, CHAPS (3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate), that interferes with stem cell self-renewal. By stabilizing the Wnt3a protein using phospholipids and cholesterol as carriers, we address both problems: Wnt activity remains stable in serum-free media, while non-toxic carriers allow the use of high Wnt concentrations. Stabilized Wnt3a supports strongly increased self-renewal of organ and embryonic stem cells and the serum-free establishment of human organoids from healthy and diseased intestine and liver. Moreover, the lipophilicity of Wnt3a protein greatly facilitates its purification. Our findings remove a major obstacle impeding clinical applications of adult stem cells and offer advantages for all cell culture uses of Wnt3a protein

Folding of the human immunodeficiency virus type 1 envelope glycoprotein in the endoplasmic reticulum

The lumen of the endoplasmic reticulum (ER) provides a unique folding environment that is distinct from other organelles supporting protein folding. The relatively oxidizing milieu allows the formation of disulfide bonds. N-linked oligosaccharides that are attached during synthesis play multiple roles in the folding process of glycoproteins. They stabilize folded domains and increase protein solubility, which prevents aggregation of folding intermediates. Glycans mediate the interaction of newly synthesized glycoproteins with some resident ER folding factors, such as calnexin and calreticulin. Here we present an overview of the present knowledge on the folding process of the heavily glycosylated human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein in the ER

Low-density lipoprotein structure and folding

The endoplasmic reticulum (ER) is a major cellular production factory for many membrane and soluble proteins. A quality control system ensures that only correctly folded and assembled proteins leave the compartment. The low-density lipoprotein receptor (LDLR) is the prototype of a large family of structurally homologous cell surface receptors, which fold in the ER and function as endocytic and signaling receptors in a wide variety of cellular processes. Patients with familial hypercholesterolemia carry single or multiple mutations in their LDLR, which leads to malfunction of the protein, in most patients through misfolding of the receptor. As a result, clearance of cholesterol-rich LDL particles from the circulation decreases, and the elevated blood cholesterol levels cause early onset of atherosclerosis and an increased risk of cardiac disease in these patients. In this review, we will elaborate on the structural aspects of the LDLR and its folding pathway and compare it to other LDLR family members

Cellular protein folding and modification in the endoplasmic reticulum

Analysis of the human genome reveals that approximately a third of all open reading frames code for proteins that enter the endoplasmic reticulum (ER), demonstrating the importance of this organelle for global proteinmaturation.The path taken by a polypeptide through the secretory pathway starts with its translocation across or into the ER membrane. It then must fold and be modified correctly in the ER before being transported via the Golgi apparatus to the cell surface or another destination. Being physically segregated from the cytosol means that the ER lumen has a distinct folding environment. It contains much of the machinery for fulfilling the task of protein production, including complex pathways for folding, assembly, modification, quality control, and recycling. Importantly, the compartmentalization means that several modifications that do not occur in the cytosol, such as glycosylation and extensive disulfide bond formation, can occur to secreted proteins to enhance their stability before their exposure to the extracellular milieu. How these various machineries interact during the normal pathway of folding and protein secretion is the subject of this review

Glycoprotein folding in the endoplasmic reticulum

Our understanding of eukaryotic protein folding in the endoplasmic reticulum has increased enormously over the last 5 years. In this review, we summarize some of the major research themes that have captivated researchers in this field during the last years of the 20th century. We follow the path of a typical protein as it emerges from the ribosome and enters the reticular environment. While many of these events are shared between different polypeptide chains, we highlight some of the numerous differences between proteins, between cell types, and between the chaperones utilized by different ER glycoproteins. Finally, we consider the likely advances in this field as the new century unfolds and we address the prospect of a unified understanding of how protein folding, degradation, and translation are coordinated within a cell

Cellular protein folding and modification in the endoplasmic reticulum

Analysis of the human genome reveals that approximately a third of all open reading frames code for proteins that enter the endoplasmic reticulum (ER), demonstrating the importance of this organelle for global proteinmaturation.The path taken by a polypeptide through the secretory pathway starts with its translocation across or into the ER membrane. It then must fold and be modified correctly in the ER before being transported via the Golgi apparatus to the cell surface or another destination. Being physically segregated from the cytosol means that the ER lumen has a distinct folding environment. It contains much of the machinery for fulfilling the task of protein production, including complex pathways for folding, assembly, modification, quality control, and recycling. Importantly, the compartmentalization means that several modifications that do not occur in the cytosol, such as glycosylation and extensive disulfide bond formation, can occur to secreted proteins to enhance their stability before their exposure to the extracellular milieu. How these various machineries interact during the normal pathway of folding and protein secretion is the subject of this review