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Postural demands modulate tactile perception in the lower limb in young and older adults
(2025) Wachsmann, Fabian Dominik; Fiehler, Katja; Voudouris, Dimitris
Balance control requires the continuous integration of feedback signals from several sensory organs with feedforward estimates about the state of the body. Such feedback signals are important for standing upright, as shown in increased and more variable sway patterns when sensory feedback is compromised, for instance when standing with eyes closed or on unstable surfaces that make cutaneous signals from the foot less reliable. Poorer sensory processing is also considered to arise during healthy aging due to a decrease of the reliability and transmission rate of feedback signals. Here, we are interested in how processing of tactile signals from the lower leg is modulated when balance control is challenged and how this interacts with age-related sensorimotor changes. We examined tactile sensitivity on the lower leg during sitting, standing on stable ground, and standing on unstable ground (foam). We quantified the center of pressure during the two standing conditions by determining the area of a 95% confidence interval ellipse as well as the total displacement of the center of pressure. Tactile sensitivity was assessed by asking participants to detect brief vibrotactile probes of various intensities to the lower leg. As expected, postural sway increased when standing on foam than stable ground for both age groups. When postural demands were minimal (sitting), tactile sensitivity was overall poorer in older than younger adults. Tactile perception was also poorer when standing on foam than on the stable ground, for both age groups. We conclude that increased postural demands reduce reliance on tactile signals from the lower limb in both young and older adults.
Pr and Pfr structures of plant phytochrome A
(2025) Nagano, Soshichiro; von Stetten, David; Guan, Kaoling; Chen, Peng-Yuan; Song, Chen; Barends, Thomas; Weiss, Manfred S.; Feiler, Christian G.; Dörner, Katerina; de Diego Martinez, Iñaki; Schubert, Robin; Bielecki, Johan; Brings, Lea; Han, Huijong; Kharitonov, Konstantin; Kim, Chan; Kloos, Marco; Koliyadu, Jayanath C. P.; Koua, Faisal H. M.; Round, Ekaterina; Sarma, Abhisakh; Sato, Tokushi; Schmidt, Christina; Valerio, Joana; Wrona, Agnieszka; Schulz, Joachim; de Wijn, Raphael; Letrun, Romain; Bean, Richard; Mancuso, Adrian; Heyne, Karsten; Hughes, Jon
Phytochromes are biliprotein photoreceptors widespread amongst microorganisms and ubiquitous in plants where they control developmental processes as diverse as germination, stem elongation and floral induction through the photoconversion of inactive Pr to the Pfr signalling state. Here we report crystal structures of the chromophore-binding module of soybean phytochrome A, including ~2.2 Å XFEL structures of Pr and Pfr at ambient temperature and high resolution cryogenic structures of Pr. In the Pfr structure, the chromophore is exposed to the medium, the D-ring remaining α-facial following the likely clockwise photoflip. The chromophore shifts within its pocket, while its propionate side chains, their partners as well as three neighbouring tyrosines shift radically. Helices near the chromophore show substantial shifts that might represent components of the light signal. These changes reflect those in bacteriophytochromes despite their quite different signalling mechanisms, implying that fundamental aspects of phytochrome photoactivation have been repurposed for photoregulation in the eukaryotic plant.
Prophylaxis during multibracket appliance treatment : a survey among general dentists in Germany
(2025) Petker-Jung, Waldemar; Ruf, Sabine; Bock, Niko C.
Background: Accomplishing good oral hygiene represents a major challenge during multibracket appliance (MBA) treatment. In Germany, children, and adolescents between 6 and 18 years of age can attend an individual prophylaxis (IP) program free of charge twice a year. As part of this, they undergo training and receive recommendations to enhance oral hygiene. However, it remains unclear whether the general dentist feels responsible for prophylaxis during MBA treatment and how they adapt the IP sessions compared to patients without fixed appliances. Aim: To assess how general dentists manage IP in children and adolescents undergoing MBA treatment. Method: A questionnaire was sent to 2744 general dental practices in the region of Hesse, Germany. Dentists were asked regarding their opinion on the responsibility for prophylaxis during MBA treatment, the oral hygiene recommendations given to those patients and how they adapt the prophylaxis sessions to special MBA needs. Results: The response rate was 37.0% (n = 1014). While only 8% of the respondents consider the orthodontist as primarily responsible for IP in MBA patients, the majority considers the general dentist (46%) or both, the general dentist and the orthodontist (46%) to be responsible for IP in MBA patients. The vast majority of respondents answered that compared to patients without fixed appliances, MBA patients receive different oral hygiene recommendations during IP sessions. These recommendations are mostly related to 1. a longer toothbrushing duration (> 3 min) and 2. the use of additional tools for mechanical plaque removal (interdental brushes). Conclusion: The majority of respondents perceive the general dentist as having primary or shared responsibility for IP during MBA treatment and adapt oral hygiene recommendations to the special requirements. However, the large proportion of perceived shared responsibility also suggests considerable room for improvement. Furthermore, analysis showed a large range regarding oral hygiene recommendations, indicating the need for standardized clinical guidelines.
Should we stay or should we go? : recent insights on drug discontinuation in multiple sclerosis
(2025) Mrochen, Anne; Meuth, Sven G.; Pfeuffer, Steffen
Background: The decision to discontinue disease-modifying therapies (DMTs) in patients with multiple sclerosis (PwMS) is a critical clinical challenge. Historically, DMTs were discontinued due to side effects, treatment limitations, or progression to secondary progressive MS. However, advancements in MS therapies, particularly high-efficacy DMTs (HE-DMTs) and the increased knowledge on disease courses and phenotypes have resulted in more personalized treatment approaches and introduced discussion on scheduled DMT discontinuation. This review explores the current evidence on DMT discontinuation, focusing on its implications for aging populations and the interplay between cardiovascular diseases (CVD) and MS. Current evidence and interplay with CVD: Randomized trials such as DISCOMS and DOT-MS have provided insights into discontinuing DMTs in stable patients. In summary, both randomized clinical trials highlight the risk of disease reactivation following treatment discontinuation. Due to the limited sample size, neither study was able to conduct subgroup analyses based on age groups. Additionally, DOT-MS was terminated prematurely, direct comparisons with other studies should be avoided. While older studies and observational data (e.g., OFSEP) have shown relapse risks associated with discontinuation, particularly for drugs like natalizumab and fingolimod, there is limited data on HE-DMT discontinuation outcomes. Comorbidities, particularly CVDs, further complicate decisions regarding the continuation of DMTs in older adults. MS patients bear a higher burden of CVD, which is also associated with unfavorable disease courses. While optimizing cardiovascular risk profiles appears advisable, it remains unclear whether DMTs themselves have a positive impact on CVDs. Conclusion: Given the complexities associated with discontinuing DMTs in MS patients, it is essential to balance the avoidance of polypharmacy with the potential risks of disease reactivation and the impact of comorbidities, especially CVDs, on disease progression. The interplay between MS and CVD highlights the importance of a holistic risk assessment when considering DMT discontinuation.
Temporal modulation of tactile perception during balance control
(2025) Wachsmann, Fabian Dominik; Fiehler, Katja; Voudouris, Dimitris
Somatosensory feedback, like touch, is essential for body control and movement. Yet tactile sensations from a body part that is about to move or is moving are often suppressed. Most studies on tactile suppression focus on upper-limb movements, where suppression is typically reduced when tactile signals become important to the task. However, how tactile sensitivity changes at other body parts involved in more complex, whole-body actions is widely unexplored. This study examines the temporal tuning of tactile processing on the lower limb during balance control while varying feedback processing demands. Participants stood in a virtual room, with the front wall moving toward them at a moment of high or low temporal uncertainty challenging their posture. Tactile sensitivity was probed using vibrotactile stimuli at the lower leg at different time points relative to perturbation onset. We found that tactile sensitivity while standing improved around the time of perturbation, irrespective of the temporal uncertainty about perturbation onset. Such dynamic modulation indicates a continuous process of sensory feedback regulation to accomplish the task at hand. This expands previous knowledge about sensory integration on the lower limbs during postural control.