Unicompartmental knee arthroplasty (UKA) is an alternative to total knee arthroplasty for patients who require treatment of single-compartment osteoarthritis, especially for young patients. To ...satisfy this requirement, new patient-specific prosthetic designs have been introduced. The patient-specific UKA is designed on the basis of data from preoperative medical images. In general, knee implant design with increased conformity has been developed to provide lower contact stress and reduced wear on the tibial insert compared with flat knee designs. The different tibiofemoral conformity may provide designers the opportunity to address both wear and kinematic design goals simultaneously. The aim of this study was to evaluate wear prediction with respect to tibiofemoral conformity design in patient-specific UKA under gait loading conditions by using a previously validated computational wear method.
Three designs with different conformities were developed with the same femoral component: a flat design normally used in fixed-bearing UKA, a tibia plateau anatomy mimetic (AM) design, and an increased conforming design. We investigated the kinematics, contact stress, contact area, wear rate, and volumetric wear of the three different tibial insert designs.
Conforming increased design showed a lower contact stress and increased contact area. In addition, increased conformity resulted in a reduction of the wear rate and volumetric wear. However, the increased conformity design showed limited kinematics.
Our results indicated that increased conformity provided improvements in wear but resulted in limited kinematics. Therefore, increased conformity should be avoided in fixed-bearing patient-specific UKA design. We recommend a flat or plateau AM tibial insert design in patient-specific UKA.
: Y-G. Koh, K-M. Park, H-Y. Lee, K-T. Kang. Influence of tibiofemoral congruency design on the wear of patient-specific unicompartmental knee arthroplasty using finite element analysis.
2019;8:156-164. DOI: 10.1302/2046-3758.83.BJR-2018-0193.R1.
A simple surface modification technique was developed to functionalize polymeric and cellulosic materials with bactericidal polycationic groups. The poly(ethylene terephthalate) (PET) film was first ...graft copolymerized with 4-vinylpyridine (4VP) and subsequently derivatized with hexyl bromide via the quaternization of the grafted pyridine groups into pyridinium groups. The amount of pyridinium groups on the film surface could be controlled by varying the 4VP monomer concentrations used for grafting. The pyridinium groups introduced on the surface of the substrate possess antibacterial properties, as shown by their effect on Escherichia coli (E. coli). The bacteria killing efficiency is very high when the concentration of pyridinium groups on surfaces is 15 nmol/cm2 or higher. E. coli adhered on the functionalized surfaces are no longer viable when released into an aqueous culture medium. Filter paper, as a typical cellulosic material, was also functionalized in the same manner to introduce the pyridinium groups. The antibacterial activity was also similarly observed for this substrate. Thus, the present surface functionalization method has the advantage of being effective in conferring both polymeric and cellulosic materials with antibacterial properties.
Summary
Samarium (Sm) based perovskite nanorod‐like structures were processed for electrocatalytic functions involving oxygen and hydrogen evolution reactions. Influence of erbium (Er) ions on the ...structural and electrocatalytic properties of SmFe1−xErxO3 perovskites were studied under varied alkaline pH (8.5‐14) conditions. The rod‐like dimensional analysis was obtained through scanning/transmission electron microscopes. Diffraction signals affirmed the presence of samarium oxide (Sm2O3) traces in processed perovskites. X‐ray photoelectron spectroscopy data signified the presence of corresponding oxides and determined the valence state of Sm, Er and Fe ions. Er ions were found to boost the production of oxygen and hydrogen molecules. The anodic overpotential values improved from 216 mV to 184 mV, while cathodic overpotential values improved from 231 mV to 213 mV upon Er inclusion. Electrocatalytic results approved SmFe1−xErxO3 as a promising oxygen/hydrogen liberating electrocatalyst with remarkable stability and Tafel slopes that improved from 96 to 77 mV/dec and 78 to 55 mV/dec upon Er incorporation in host perovskite.
SmFe1‐xErxO3 rare earth perovskite metal oxides with improved conductivity facilitates the efficient interaction of charge carriers to create additional catalytic sites for improved OER/HER performance.
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Recently there has been immense interest in the exploration of richly available two-dimensional non-toxic layered material such as tin disulfide (SnS2) for potential employment in ...energy and environmental needs. In this regard, we report on the synthesis of few-layered Sn1−xMgxS2 nanosheets through a facile one-step hydrothermal route to address all such functions concerning photocatalysis and photoelectrochemical conversion. The crystalline order and structure of processed layered Sn1−xMgxS2 were initially found to exhibit a strong influence on their physicochemical properties. Their optical properties attest the Mg doping in SnS2 to benefit us with enhanced visible-light absorption via red-shift in their absorption edge. In the photoluminescence spectrum the emissions observed along visible and red region signifies the association of Mg related trap states in Sn1−xMgxS2. Next, the photocurrent and electrochemical impedance spectroscopic results revealed the Mg doping to promote the effective charge transfer process (which was beneficial to enhance their photocatalytic activity). Consequently, the layered Sn0.98Mg0.02S2 made photoanodes displayed 1.7 fold higher photocurrent density under simulated solar radiation with respect to their undoped counterpart. Furthermore, the layered Sn0.98Mg0.02S2 nanosheets exhibits enhanced visible light decomposition of organic dye while compared with pristine SnS2 nanosheets. The value of rate constants obtained for the Sn0.98Mg0.02S2 nanosheets was found to be 1.4 times higher than that of pristine SnS2. Finally, the results obtained through the present study projects the huge potential of layered Sn0.98Mg0.02S2 nanosheets for future multifunctional applications.
Metabolic dysfunction accompanies neurodegenerative disease and aging. An important step for therapeutic development is a more sophisticated understanding of the source of metabolic dysfunction, as ...well as to distinguish disease-associated changes from aging effects. We examined mitochondrial function in ex vivo aging and glaucomatous optic nerve using a novel approach, the Seahorse Analyzer. Optic nerves (ON) from the DBA/2J mouse model of glaucoma and the DBA/2-
Gpnmb
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control strain were isolated, and oxygen consumption rate (OCR) and extracellular acidification rate (ECAR), the discharge of protons from lactate release or byproducts of substrate oxidation, were measured. The glial-specific aconitase inhibitor fluorocitrate was used to limit the contribution of glial mitochondria to OCR and ECAR. We observed significant decreases in maximal respiration, ATP production, and spare capacity with aging. In the presence of fluorocitrate, OCR was higher, with more ATP produced, in glaucoma compared to aged ON. However, glaucoma ON showed lower maximal respiration. In the presence of fluorocitrate and challenged with ATPase inhibition, glaucoma ON was incapable of further upregulation of glycolysis to compensate for the loss of oxidative phosphorylation. Inclusion of 2-deoxyglucose as a substrate during ATPase inhibition indicated a significantly higher proportion of ECAR was derived from TCA cycle substrate oxidation than glycolysis in glaucoma ON. These data indicate that glaucoma axons have limited ability to respond to increased energy demand given their lower maximal respiration and inability to upregulate glycolysis when challenged. The higher ATP output from axonal mitochondria in glaucoma optic nerve compensates for this lack of resiliency but is ultimately inadequate for continued function.
Glutamate excitotoxicity leads to fragmented mitochondria in neurodegenerative diseases, mediated by nitric oxide and S-nitrosylation of dynamin-related protein 1, a mitochondrial outer membrane ...fission protein. Optic atrophy gene 1 (OPA1) is an inner membrane protein important for mitochondrial fusion. Autosomal dominant optic atrophy (ADOA), caused by mutations in OPA1, is a neurodegenerative disease affecting mainly retinal ganglion cells (RGCs). Here, we showed that OPA1 deficiency in an ADOA model influences N-methyl-D-aspartate (NMDA) receptor expression, which is involved in glutamate excitotoxicity and oxidative stress. Opa1(enu/+) mice show a slow progressive loss of RGCs, activation of astroglia and microglia, and pronounced mitochondrial fission in optic nerve heads as found by electron tomography. Expression of NMDA receptors (NR1, 2A, and 2B) in the retina of Opa1(enu/+) mice was significantly increased as determined by western blot and immunohistochemistry. Superoxide dismutase 2 (SOD2) expression was significantly decreased, the apoptotic pathway was activated as Bax was increased, and phosphorylated Bad and BcL-xL were decreased. Our results conclusively demonstrate that not only glutamate excitotoxicity and/or oxidative stress alters mitochondrial fission/fusion, but that an imbalance in mitochondrial fission/fusion in turn leads to NMDA receptor upregulation and oxidative stress. Therefore, we propose a new vicious cycle involved in neurodegeneration that includes glutamate excitotoxicity, oxidative stress, and mitochondrial dynamics.
To investigate the impacts of body weight status on surgical outcomes and shifts of body weight status after adenotonsillectomy(T&A) in children with obstructive sleep apnea (OSA).
From 2009 to 2011, ...161 children (mean age, 7.0 ± 3.4 years; 78% boys) were included. All the children had clinical symptoms and preoperative polysomnographic evaluations diagnosis of OSA. Children were divided into four weight status groups (underweight, normal weight, overweight and obese), based on age and gender corrected body mass index (BMI).
Following T&A, the four different weight status groups significantly improved in apnea/hypopnea index (AHI) and minimum oxygen saturation. However, 49.1% of the children (79/161) had residual OSA (AHI ≥ 1). The incidence of residual OSA (AHI ≥ 1) in the obese group was 75%, which was significantly higher than the other three groups (P<0.01). Weight status changes after T&A were documented, and 54% (13/24) of the underweight children shifted to normal weight status within 6 months after surgery.
Although sleep parameters improved in all weight statuses, obese children had a higher incidence of residual OSA postoperatively. About half of the underweight children shifted to normal weight status after T&A.
Multiple sclerosis (MS) is an autoimmune and neurodegenerative disease driven by inflammation and demyelination in the brain, spinal cord, and optic nerve. Optic neuritis, characterized by ...inflammation and demyelination of the optic nerve, is a symptom in many patients with MS. The optic nerve is the highway for visual information transmitted from the retina to the brain. It contains axons from the retinal ganglion cells (RGCs) that reside in the retina, myelin forming oligodendrocytes and resident microglia and astrocytes. Inflammation, demyelination, and axonal degeneration are also present in the optic nerve of mice subjected to experimental autoimmune encephalomyelitis (EAE), a preclinical mouse model of MS. Monitoring the optic nerve in EAE is a useful strategy to study the presentation and progression of pathology in the visual system; however, current approaches have relied on sectioning, staining and manual quantification. Further, information regarding the spatial load of lesions and inflammation is dependent on the area of sectioning. To better characterize cellular pathology in the EAE model, we employed a tissue clearing and 3D immunolabelling and imaging protocol to observe patterns of immune cell infiltration and activation throughout the optic nerve. Increased density of TOPRO staining for nuclei captured immune cell infiltration and Iba1 immunostaining was employed to monitor microglia and macrophages. Axonal degeneration was monitored by neurofilament immunolabelling to reveal axonal swellings throughout the optic nerve. In parallel, we developed a convolutional neural network with a UNet architecture (CNN-UNet) called BlebNet for automated identification and quantification of axonal swellings in whole mount optic nerves. Together this constitutes a toolkit for 3-dimensional immunostaining to monitor general optic nerve pathology and fast automated quantification of axonal defects that could also be adapted to monitor axonal degeneration and inflammation in other neurodegenerative disease models.
The relationship between weight status, adenotonsillar hypertrophy and obstructive sleep apnea (OSA) in children has not yet been well studied. As the sleep parameters may show a disparity in ...different weight statuses, this study examined the relationship between the data of over-night polysomnography and different weight statuses, as well as the impact of adenotonsillar hypertrophy on children with OSA.
Children with sleep disturbances were recruited from our clinics. Standard physical examinations, history taking, lateral neck roentgenography, and full-night polysomnography were obtained. Children were divided into four groups based on the age- and gender-corrected body mass index (BMI): underweight, normal weight, overweight and obese. An adenoidal/nasopharyngeal ratio of more than 0.67 was considered adenoidal hypertrophy. Tonsillar hypertrophy was defined as having Grade III tonsils or above.
From July 2006 to January 2009, 197 children were included in this study. Obese children had a significantly higher apnea-hypopnea index (AHI), obstructive apnea index and lower minimum oxygen saturation (MinSaO(2)) than those of the other groups. Underweight children had the second highest AHI. A negative correlation was also found between BMI z scores and MinSaO(2) (r = -0.194; P = 0.007). Children with tonsillar hypertrophy (P = 0.001) were associated with a higher risk of having OSA. The risk of having OSA was significantly higher in obese children (P = 0.001) and underweight children (P = 0.043) than in those with a normal weight.
Obesity, underweight status and tonsillar hypertrophy are associated with children having OSA, and obese children have a significantly higher risk than children with underweight status.
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