Evaluation of the impact of exercise of gait on a treadmill on balance of people who suffered from cerebral stroke

Purpose: The aim of the study is to define the impact of exercise on a treadmill on static balance and stability of posture in a group of patients after cerebral stroke rehabilitated in a late period, with an application of a treadmill with the function of visual biofeedback. Methods: The examination was carried out in a group of 46 people in a late period after ischemic cerebral stroke. The patients examined were randomly put to a group with intervention (n = 23), in which a rehabilitation programme with an application of a treadmill with the visual feedback function was realized and to a control group (n = 23). They evaluated balance in standing on both feet by means of a force plate, symmetry of load of lower limbs and dynamic balance in Up & Go test. Results: A statistically significant change of stabilometric parameters was observed only in the area of postural sways of the centre of pressure (COP). A significant improvement of the symmetry of load of lower limbs in standing ( p = 0.0266) was diagnosed in the examined group after the end of the programme. After the end of the programme no significant difference between the group with intervention and the control group as for a change of balance of the examined patients was found. Conclusions: In the examined group in the chronic period after cs no significant improvement of stabilometrically evaluated balance was obtained, but improvement of the symmetry of load of lower limbs as well as improvement of dynamic balance were observed

Relationships between walking velocity and distance and the symmetry of temporospatial parameters in chronic post-stroke subjects

Purpose: Subjects with post-stroke hemiparesis frequently present with asymmetric gait patterns. Symmetry, reflecting similarities in temporospatial, kinematic parameters, is an important measure of gait assessment. The study was designed to examine the relationships between asymmetry of temporal, spatial and kinematic gait parameters and walking velocity and distance. Methods: Temporospatial and kinematic gait parameters were examined in a group of 50 chronic post-stroke subjects and in a group of 25 healthy controls. Symmetry ratio was calculated for all the parameters. Gait velocity was measured during 10-metre test, the walking distance during 2-Minute Walk Test, and balance during Up&Go Test. Results: The relationship between stance phase duration symmetry and gait speed was at a moderate level (r = –0.43, p = 0.0173). There was a moderate relationship between swing phase symmetry and walking velocity and distance. The findings did not show a significant correlation between step length symmetry versus gait speed and distance. Conclusions: There is a mild relationship between self-selected gait velocity and walking distance versus temporal parameters symmetry. The findings do not confirm a relationship between self-selected gait velocity and walking distance versus spatial and kinematic parameters as well as balance. Likewise, no evidence confirms that asymmetry of temporal, spatial, kinematic gait parameters changes with the age of post-stroke subjects or is related to the length of time from stroke onset. Given the above, gait symmetry may be recognized as an important indicator of the level of gait control in post-stroke patients because it enables unique gait assessment, independent from other parameters

β2\beta_2-Type Amyloidlike Fibrils of Poly-L\small{L} -glutamic Acid Convert into Long, Highly Ordered Helices upon Dissolution in Dimethyl Sulfoxide

Replacing water with dimethyl sulfoxide (DMSO) completely reshapes the free-energy landscapes of solvated proteins. In DMSO, a powerful hydrogen-bond (HB) acceptor, formation of HBs between backbone NH groups and solvent is favored over HBs involving protein’s carbonyl groups. This entails a profound structural disruption of globular proteins and proteinaceous aggregates (e.g., amyloid fibrils) upon transfer to DMSO. Here, we investigate an unusual DMSO-induced conformational transition of $\beta_2$-amyloid fibrils from poly-l-glutamic acid (PLGA). The infrared spectra of $\beta_2$-PLGA dissolved in DMSO lack the typical features associated with disordered conformation that are observed when amyloid fibrils from other proteins are dispersed in DMSO. Instead, the frequency and unusual narrowness of the amide I band imply the presence of highly ordered helical structures, which is supported by complementary methods, including vibrational circular dichroism and Raman optical activity. We argue that the conformation most consistent with the spectroscopic data is that of a PLGA chain essentially lacking nonhelical segments such as bends that would provide DMSO acceptors with direct access to the backbone. A structural study of DMSO-dissolved $\beta_2$-PLGA by synchrotron small-angle X-ray scattering reveals the presence of long uninterrupted helices lending direct support to this hypothesis. Our study highlights the dramatic effects that solvation may have on conformational transitions of large polypeptide assemblies

Non-isothermal cold crystallization kinetics of cork–polymer biocomposites based on polylactic acid for fused filament fabrication

Cork–polymer composites (CPC) based on polylactic acid (PLA) matrix were prepared for the development of flaments for fused flament fabrication. The non-isothermal cold crystallization behaviours of PLA and CPC were investigated by diferential scanning calorimetry. Cold crystallization kinetic behaviours of PLA and CPC with 15 mass/% of cork powder residues at diferent heating rates (1.25, 2.5, 5 and 7.5 K min−1) were studied. Results showed that cold crystallization temperature (Tcc) of PLA matrix decreased with the addition of cork. Crystallization kinetic behaviour was studied by Avrami and Tobin models. It was shown that cork powder surface acts as a nucleating agent during non-isothermal cold crystallization, by accelerating the crystallization rate and, therefore, by reducing the half-time crystallization (t1/2) values. Polarized optical microscopy and X-ray difraction were used to evaluate the crystalline structure of PLA and CPC. Kissinger and Friedman methods were employed to determine the crystallization activation energy (Ec).publishe