Weight-shifting-based robot control system improves the weight-bearing rate and balance ability of the static standing position in hip osteoarthritis patients: a randomized controlled trial focusing on outcomes after total hip arthroplasty

Background After a total hip arthroplasty (THA), standing and walking balance are greatly affected in the early stages of recovery, so it is important to increase the weight-bearing amount (WBA) on the operated side. Sometimes, traditional treatments may not be enough to improve WBA and weight-bearing ratio (WBR) on the operated side in a satisfactory way. To solve this problem, we came up with a new weight-shifting-based robot control system called LOCOBOT. This system can control a spherical robot on a floor by changing the center of pressure (COP) on a force-sensing board in rehabilitation after THA. The goal of this study was to find out how rehabilitation with the LOCOBOT affects the WBR and balance in a static standing position in patients with unilateral hip osteoarthritis (OA) who had a primary uncemented THA. Methods This randomized controlled trial included 20 patients diagnosed with Kellgren–Lawrence (K–L) grade 3 or 4 hip OA on the operative side and K–L grade 0 normal hip on the nonoperative side. We used the minimization method for allocation and randomly assigned patients to either the LOCOBOT group or the control group. As a result, 10 patient seach were randomly assigned to the LOCOBOT and control groups. Both groups received 40 min of rehabilitation treatment. Out of the 40 min, the LOCOBOT group underwent treatment for 10 min with LOCOBOT. The control group performed COP-controlled exercises on a flat floor instead of using LOCOBOT for 10 of the 40 min. All theoutcome measures were performed pre-THA and 11.9 ± 1.6 days after THA (12 days after THA). The primary outcome measure included WBR in the static standing position. Results After12 days of THA, the LOCOBOT group exhibited significantly higher mean WBR and WBA (operated side) values than the control group. Furthermore, the LOCOBOT group exhibited significantly lower mean WBA (non-operated side) and outer diameter area (ODA) values than the control group. From pre-THA to 12 days after THA, the LOCOBOT group exhibited a significant improvement in mean WBR and WBA (operated side). Moreover, the mean WBA (non-operated side) and ODA significantly decreased. From pre-THA to 12 days after THA, the control group showed a significant increase in total trajectory length and ODA. Conclusions The most important finding of this study was that patients were able to perform the LOCOBOT exercise as early as the second day after THA, and that WBR and ODA significantly improved by the 12th day after THA. This result demonstrated that the LOCOBOT effectively improves WBR in a short period of time after THA and is a valuable system for enhancing balance ability. This expedites the acquisition of independence in activities of daily living after THA and may contribute to optimizing the effectiveness of medical care

Thermophoresis of cyclodextrins and cyclodextrin-drug-complexes

The behaviour of biomolecules in a temperature gradient, known as thermodiffusion, changes when a ligand binds. In recent years, this effect has been used to gain detailed information on binding dynamics, although the physicochemical processes are still unclear [1]. We focused on the question how the hydration layer affects thermodiffusion when it changes due to complex formation. As model system we used cyclodextrin complexes with acetylsalicylic acid (Aspirin). Cyclodextrins are cyclic oligosaccharides that show a strong tendency towards complex formation. For that reason they are interesting as drug delivery systems [2,3.] The thermodiffusion of different cyclodextrins [4] and their aspirin complexes was investigated in a temperature range from 10 to 50°C by infrared thermal diffusion forced Rayleigh scattering (IR-TDFRS). Additionally, NMR measurements were performed at 25 and 60°C to obtain information about stability and structure of the complexes. We found that all cyclodextrins show a stronger diffusion towards the cold side when Aspirin binds. This behaviour suggests a weaker interaction with the surrounding water that could be explained by hydrogen bond formation inside the complex.[1] M. Jerabek-Willemsen, T. André, W. Wanner, H. Roth, S. Duhr, P. Baaske, and D. Breitsprecher, J. Mol. Struct. (2014).[2] E. Del Valle, Process Biochemistry 39, 1033 (2004).[3] J. Szejtli, Drug Invest. 2, 11 (1990).[4] K. Eguchi, D. Niether, S. Wiegand, and R. Kita, Eur.Phys. J. E 39, 16086 (2016)

Role of Hydrogen Bonding of Cyclodextrin–Drug Complexes Probed by Thermodiffusion

The temperature-gradient induced migration of biomolecules, known as thermophoresis or thermodiffusion, changes upon ligand binding. In recent years, this effect has been used to determine protein-ligand binding constants. The mechanism through which thermodiffusive properties change when complexes are formed, however, is not understood. An important contribution to thermodiffusive properties originates from the thermal response of hydrogen bonds. Since there is a considerable difference between the degree of solvation of the protein-ligand complex and its isolated components, ligand-binding is accompanied by a significant change in hydration. The aim of the present work is therefore to investigate the role played by hydrogen bonding on the change in thermodiffusive behaviour upon ligand binding. As a model system we use cyclodextrins (CDs) and acetylsalicylic acid (ASA), where a quite significant change in hydration is expected, and where no conformational changes occur when a CD-ASA complex is formed in aqueous solution. Thermophoresis was investigated in a temperature range from 10 to 50°C by infrared thermal diffusion forced Rayleigh scattering (IR-TDFRS). NMR measurements were performed at 25°C to obtain information about the structure of the complexes. All CD-ASA complexes show a stronger affinity towards regions of lower temperature as compared to the free CDs. We found that the temperature sensitivity of thermophoresis correlates with the 1-octanol/water partition coefficient. This observation not only establishes the relation between thermodiffusion and the degree of hydrogen bonding, but also opens the possibility to relate thermodiffusive properties of complexes to their partition coefficient, which can not be determined otherwise. This concept is especially interesting for protein-ligand complexes where the protein undergoes a conformational change, different from the CD-ASA complexes, giving rise to additional changes in their hydrophilicity