Quantitative assessment of muscle activity of back and lower extremities, whole body sagittal alignment, body sway, and health-related quality of life in adult spinal deformity patients before and after spinopelvic correction surgery: From the standpoint of the "cone of economy".

BACKGROUND AND AIMS: Pain and muscle fatigue in the low back and lower extremity associated with adult spinal deformity (ASD) markedly limit daily activities and affect quality of life. This study aimed to clarify if spinal correction surgery decreases the muscle activity requirements in relation to alignment and balance parameters. METHODS: Integrated electromyogram (I-EMG) studies of the low back and lower extremity in addition to whole body alignment, body sway, and health-related quality of life (HRQOL) were evaluated in 16 patients with ASD before and after surgery. Sixteen healthy volunteers were included as control subjects. Muscle activities of the bilateral lumbar paravertebral, biceps femoris, rectus femoris, gastrocnemius, and tibialis anterior were measured using surface electromyogram in both resting and working standing positions. Surgical outcomes were based on improvements in muscle fatigue using the sum of the whole muscle I-EMGs and body sway. HRQOL was evaluated by SRS-22r, which measures 4 domains (function, pain, self-image, mental health) and subtotal scores. RESULTS: In controls, the sum of the 10 whole I-EMGs (mVms; mean ± SD) was 3316 ± 1247 in the resting standing position and 5625 ± 2065 in the working standing position. The I-EMG values were higher in ASD patients than in healthy subjects; in the resting standing position, the sum of the whole 10 I-EMGs significantly decreased from baseline (9125 ± 3529) to 3 (6088 ± 1793) and 6 (6381 ± 1776) months postoperatively (p < 0.01). In the working standing position, the sum in ASD patients also significantly decreased from baseline (14,160 ± 5474) to 3 (8085 ± 2540) and 6 (8557 ± 3025) months postoperatively (p < 0.01). I-EMG values did not differ significantly between the 3- and 6-month time points in either condition. Body sway was also improved postoperatively at 3 months and maintained at 6 months along with the amelioration of whole-body sagittal alignment, and 4 domains and subtotal SRS-22r scores significantly increased postoperatively. CONCLUSION: Following spinopelvic correction surgery, whole body sagittal alignment was improved, and muscle activity based on I-EMG and body sway were significantly decreased. The SRS-22r scores after surgery also indicated significant improvement, suggesting that muscle fatigue in the standing position was ameliorated, i.e., the "cone of economy" was normalized.

Rapid production of silver nanofibers using a self-reducing solution.

Silver nanofibers (Ag NFs) have gained considerable attention because of their high transmittance resulting from the size effect, excellent electrical conductivity, and mechanical properties. However, synthesizing high-quality Ag NFs remains a challenge. This paper reports a novel self-reducing solution that contains platinum nanoparticles for the rapid production of Ag NFs. The method involves generating the precursor NFs and heating them in air, which reduces silver nitrate to Ag NFs within a few minutes. The as-prepared solution is characterized by its simple preparation, cost-effectiveness, and broad applicability. Additionally, the use of high-pressure airflow to directly spin the solution and a complete self-reduction system that does not depend on external conditions broadens the application prospects of the as-developed solution. Furthermore, we provide insights into the self-reduction mechanism and guidance on the preparation of self-reducing solutions.

New Neuromuscular Training for Peripheral Nerve Disorders Using an Ankle Joint Hybrid Assistive Limb: A Case Series.

Peripheral nerve disorder of the lower extremities causes drop foot and disturbs the daily living activities of patients. The ankle joint hybrid assistive limb (HAL) provides voluntary ankle joint training using surface bioelectrical signals from the muscles of the lower extremities. We investigated the neurological effects of ankle joint HAL training in three patients. Sensory nerve action potentials (SNAPs) and compound muscle action potentials (CMAPs) were analyzed for the peroneal and tibial nerves prior to the first ankle joint HAL training session. Integrated surface electromyography EMG signals were recorded before and after the HAL training sessions to evaluate the effects of training for neuromuscular disorders. The patients were hospitalized to receive rehabilitation with HAL training for 2 weeks. The HAL training was performed daily with two 60 min sessions. All cases demonstrated severe neuromuscular impairment according to the result of the CMAP. All integrated EMG measurements of antagonistic muscle activities decreased after the ankle joint HAL training. The manual muscle testing (MMT) scores of each muscle were slightly increased after the HAL intervention for Case 2(tibialis anterior, from 2 to 2+; gastrocnemius muscles, from 2- to 2; extensor digitorum longus, and extensor hallucis longus, from 1 to 3). The MMT scores were also slightly increased except for gastrocnemius muscle for Case 3 (tibialis anterior, extensor digitorum longus, and extensor hallucis longus, from 2- to 2). These two patients demonstrated voluntary muscle contractions and nerve signals in the CMAP before the HAL training. Even though the amplitude of CMAPs was low, the HAL training may provide voluntary ankle joint movements by reducing the antagonistic muscle contraction via computer processing. The HAL training may enhance muscle movement and coordination through motor learning feedback.

Doxorubicin induces cardiomyocyte death owing to the accumulation of dysfunctional mitochondria by inhibiting the autophagy fusion process.

Doxorubicin (Dox), an anthracycline antibiotic, is an anticancer drug that inhibits DNA replication and cellular metabolic processes in cancer cells with high proliferative potential. However, Dox causes severe side effects, including myocardial damage and heart failure, but the molecular mechanism underlying Dox-induced myocardial injury remains uncertain. In the present study, we evaluated the effects of Dox on the mitochondrial quality control system and regulation of mitochondrial respiration and autophagy in an in vitro rat myoblast H9c2 cell culture model using western blotting, immunohistochemistry, the Seahorse XF24 system, and flow cytometry. Our results showed that Dox did not impair the initiation of autophagic flux or the functions of lysosomes; however, Dox affected the mitochondrial quality control system, leading to a fission-dominant morphology and impaired regulation of mitochondrial respiration, thereby increasing oxidative stress and inhibited progression of autophagy, particularly the fusion of autophagosomes with lysosomes. This inhibition caused a significant decrease in the formation of autolysosomes and was responsible for the accumulation of dysfunctional mitochondria and subsequent increase in oxidative stress, eventually leading to increased myocardial cell death.

Rapid Ag Nanofiber Formation Via Pt Nanoparticle-Assisted H2-Free Reduction of Ag+-Containing Polymers.

One-dimensional Ag nanostructure-based networks have garnered significant attention as next-generation transparent conductive materials. Ag nanofibers (NFs) with high aspect ratios decrease the number density required for percolation; hence, they form qualitatively superior transparent conductive films. This study reports a novel method for rapidly fabricating Ag NFs via Pt nanoparticle-assisted H2-free reduction of solid-state AgNO3. Our results first indicated that polymers can be a source of hydrogen gas in the presence of Pt nanoparticles; Ag NFs with aspect ratios above 105 were obtained herein by heating AgNO3-containing polymer NFs in a short period of time and in an open-air environment. Our method not only successfully reduced the amount of polymer residue often encountered in spun NFs but also created an effective self-supporting reduction system that does not require an external reducing gas supply. The obtained Ag NF networks were highly conductive and transparent. Moreover, the mechanism of Ag NF formation was investigated. We demonstrate that the proposed method exhibits a high potential for producing high yields of Ag NFs in a simple and rapid manner.

Mechanical self-organization of Pt nanocoil network.

Helical-structured metallic nanocoils (NCs) may have special interactions with electromagnetic waves and hence attract considerable attention. Although several fabrication methods for metallic NCs have been reported, it is still challenging to obtain a network of well-shaped metallic NCs. This paper reports a novel and simple approach to fabricate metallic NC network. We show that well-shaped Pt NCs with symmetrical left- and right-handed segments can be formed through a spontaneous progress of mechanical deformation. The mechanisms of the driving force for the self-organization, formation of helical chirality balance, and shape control are demonstrated.

Nanomachining by rubbing at ultrasonic frequency under controlled shear force.

This study proposes a new method of proximal-probe machining that uses a rubbing process by introducing concentrated-mass (CM) cantilevers. At the second resonance of the CM cantilever vibration, the tip site of the cantilever becomes a node of the standing deflection wave because of the sufficient inertia of the attached concentrated mass. The tip makes a cyclic motion that is tangential to the sample surface, not vertical to it, as in a tapping motion. This lateral tip motion that is selectively excited by CM cantilevers was effective for the material modification of a sample due to the friction between the tip and the sample. Imaging and nanomachining under controlled shear force were demonstrated by means of the modified cantilever and a normal atomic force microscope. We were able to write a micron-sized letter "Z" having a line width of 30-100 nm on a resin surface.

Characterization of Films with Thickness Less than 10 nm by Sensitivity-Enhanced Atomic Force Acoustic Microscopy.

We present a method for characterizing ultrathin films using sensitivity-enhanced atomic force acoustic microscopy, where a concentrated-mass cantilever having a flat tip was used as a sensitive oscillator. Evaluation was aimed at 6-nm-thick and 10-nm-thick diamond-like carbon (DLC) films deposited, using different methods, on a hard disk for the effective Young's modulus defined as E/(1 - ν(2)), where E is the Young's modulus, and ν is the Poisson's ratio. The resonant frequency of the cantilever was affected not only by the film's elasticity but also by the substrate even at an indentation depth of about 0.6 nm. The substrate effect was removed by employing a theoretical formula on the indentation of a layered half-space, together with a hard disk without DLC coating. The moduli of the 6-nm-thick and 10-nm-thick DLC films were 392 and 345 GPa, respectively. The error analysis showed the standard deviation less than 5% in the moduli.

Mechanical characterization of nanowires based on optical diffraction images of the bent shape.

A mechanical characterization technique for nanowires (NWs) longer than approximately 10 microm is proposed, based on optical microscopic observations under bending test. Low flexural rigidity of NWs often results in large deflection, which rules out the use of linear beam theory; however, the largely bent shape is optically visible as a diffraction image under transmitted illumination. The NW standing on a rod-like substrate was deflected by means of a micro-cantilever, where interactive forces, such as van der Waals forces, provide sufficient adhesion for fixing the free end of the NW. The reactive force was measured from the cantilever deflection and detected by a laser interferometer. The luminance profile of the diffraction image provided a good measure of the NW diameter. Inverse analysis using geometrically nonlinear mechanics for the bent shape enabled successful evaluation of the Young's modulus. In addition, a fracture test was conducted by manipulating the cantilever for intense deformation of the NW, such as buckling. The maximum curvature was observed at the freely suspended part of the bent NW where fracture was assured. The bending strength was determined from observation of the curvature at the fracture. Examples for CuO NWs of 40 nm to 190 nm in diameter indicated dependence of the Young's modulus and strength on the NW diameter.

Residual-strain-induced nanocoils of metallic nanowires.

Metallic nanocoils are attractive nanowire (NW) structures, which are expected to have an application as small inductors, but have not been reported before. This study proposes a coating technique for permanently bending a straight, metallic NW into a helix. A physical vapor deposition is applied to oblique NWs standing on a substrate. The deposition produces a biased thickness of the coating on NWs, resulting in a mismatch in internal strains, namely thermal strain and intrinsic strain, between a NW and the coating. These residual strains are driving forces for the bending process of NWs. In particular, the intrinsic strain of the overlayer contributes the bending deformation. In addition, elastic anisotropy of NWs couples bending with a twist, contributing to the formation of helixes. We have demonstrated nanocoils, comprised of Cr-coated Cu NWs, with a coil diameter of about 300 to 500 nm.