Bimetallic PdAu alloy nanostructures incorporated ethylene diamine functionalized silicate sol-gel (ES) nanocomposite materials on indium-tin-oxide (I) electrodes (I/ES-PdAu) were prepared by facile ...electrochemical method. X-ray diffraction patterns confirmed the formation of single-phase bimetal PdAu alloy nanostructures at the electrode. X-ray photoelectron spectroscopy analysis confirmed the existence of a zero oxidation state of Pd and Au metals at the I/ES-PdAu electrode. Morphology analysis revealed the formation of anisotropic nanostructures of Au, Pd and PdAu alloy nanostructures with different sizes and shapes at the modified electrodes. Electrocatalytic methanol oxidation reaction (MOR) was studied and enhanced methanol oxidation activity was observed at the bimetallic I/ES-Pd
75
Au
25
and I/ES-Pd
50
Au
50
modified electrodes when compared to pristine I/ES-Pd
100
, I/Pd
100
and I/ES-Au
100
modified electrodes. The I/ES-Pd
75
Au
25
modified electrode was found to be the best electrocatalyst which showed lower overpotential with higher mass activity (0.144 A/mg
Pd
) for MOR. Interestingly, when Pd was combined with Au in the presence of ES silicate sol-gel the bimetallic PdAu alloy nanomaterials showed enhanced MOR activity. The MOR current observed at the I/ES-Pd
75
Au
25
electrode was nearly 1.8 times higher than that of the I/Pd
75
Au
25
electrode without ES silicate sol-gel. The stability of the I/ES-Pd
75
Au
25
electrode was tested by scanning 200 continuous cycles and the catalytic current was found to decrease only <5%.
Graphical abstract
Electrochemically co-deposited PdAu bimetallic materials embedded in N-3-(trimethoxysilyl) propylethylenediamine silicate (ES) sol-gel modified electrode (I/ES-Pd
75
Au
25
) displayed 8.7 and 3.2 times higher methanol oxidation current and mass activity when compared to the pristine I/ES-Pd
100
modified electrode due to ES silicate sol-gel supported mass interaction between PdAu alloy nanostructure with the analyte.
This scientific commentary refers to 'De novo PHACTR1 mutations in West syndrome and their pathophysiological effects', by Hamada et al. (doi:10.1093/brain/awy246).
Objective
Developmental epileptic encephalopathies (DEEs) are genetically heterogeneous severe childhood‐onset epilepsies with developmental delay or cognitive deficits. In this study, we explored ...the pathogenic mechanisms of DEE‐associated de novo mutations in the CACNA1A gene.
Methods
We studied the functional impact of four de novo DEE‐associated CACNA1A mutations, including the previously described p.A713T variant and three novel variants (p.V1396M, p.G230V, and p.I1357S). Mutant cDNAs were expressed in HEK293 cells, and whole‐cell voltage‐clamp recordings were conducted to test the impacts on CaV2.1 channel function. Channel localization and structure were assessed with immunofluorescence microscopy and three‐dimensional (3D) modeling.
Results
We find that the G230V and I1357S mutations result in loss‐of‐function effects with reduced whole‐cell current densities and decreased channel expression at the cell membrane. By contrast, the A713T and V1396M variants resulted in gain‐of‐function effects with increased whole‐cell currents and facilitated current activation (hyperpolarized shift). The A713T variant also resulted in slower current decay. 3D modeling predicts conformational changes favoring channel opening for A713T and V1396M.
Significance
Our findings suggest that both gain‐of‐function and loss‐of‐function CACNA1A mutations are associated with similarly severe DEEs and that functional validation is required to clarify the underlying molecular mechanisms and to guide therapies.
Mosaic mutant analysis, the study of cellular defects in scattered mutant cells in a wild-type environment, is a powerful approach for identifying critical functions of genes and has been applied ...extensively to invertebrate model organisms. A highly versatile technique has been developed in mouse: MASTR (mosaic mutant analysis with spatial and temporal control of recombination), which utilizes the increasing number of floxed alleles and simultaneously combines conditional gene mutagenesis and cell marking for fate analysis. A targeted allele (R26MASTR) was engineered; the allele expresses a GFPcre fusion protein following FLP-mediated recombination, which serves the dual function of deleting floxed alleles and marking mutant cells with GFP. Within 24 hr of tamoxifen administration to R26MASTR mice carrying an inducible FlpoER transgene and a floxed allele, nearly all GFP-expressing cells have a mutant allele. The fate of single cells lacking FGF8 or SHH signaling in the developing hindbrain was analyzed using MASTR, and it was revealed that there is only a short time window when neural progenitors require FGFR1 for viability and that granule cell precursors differentiate rapidly when SMO is lost. MASTR is a powerful tool that provides cell-type-specific (spatial) and temporal marking of mosaic mutant cells and is broadly applicable to developmental, cancer, and adult stem cell studies.
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► MASTR: a highly versatile technique for mosaic mutant analysis in mouse ► Combines FLPoER and conditional expression of GFPcre with deletion of floxed genes ► Useful in studies of mutant cell behaviors during development and in adult stem cells ► MASTR can be used to model sporadic human diseases and isolate mutant cells (GFP+)
Mosaic mutant analysis is a powerful technique for determining cell-autonomous and nonautonomous gene functions; however, the development of approaches in mouse has lagged behind other multicellular model organisms. Joyner and colleagues describe a new technique in mouse that utilizes any floxed allele and simultaneously combines conditional gene mutagenesis and cell marking to produce mosaic mutants. MASTR is a powerful tool that provides cell-type-specific and temporal control and is broadly applicable to developmental, cancer, and adult stem cell studies.
The cutting parameters like cutting speed, feed, and depth of cut can affect the tool life. Also, the vibration of the tool can affect the tool life. The aim of this study is to predict the cutting ...tool vibration to enhance the tool life. In this paper, vibration of tool is studied with HSS tool (high speed steel) while turning mild steel. The tool vibration is measured using X Viber vibration meter. The experimental data are tabulated and imported to artificial neural network (ANN). A multilayer perceptron model is trained with back-propagation algorithm using the experimental data. The rake angle, cutting speed, and feed are considered as input parameters for training the ANN. The trained ANN is used to predict tool vibration for different conditions. The predicted values are compared for the specific range to justify the tool change.
Juvenile myoclonic epilepsy (JME) is a common form of epilepsy with a substantial genetic basis to its etiology. While earlier studies have identified EFHC1 as a causative gene for JME, subsequent ...studies have suggested that ethnicity may play a role in determining expression of the JME phenotype among individuals carrying EFHC1 mutations. Here, we report on our studies on EFHC1 in JME patients from India. We examined the complete structure of the EFHC1 transcript from 480 JME patients and 700 control chromosomes by direct sequencing. Functional correlates of mutations were studied by immunolocalization experiments in cultured mammalian cells and protein homology modeling by in silico methods. Thirteen mutations, of which 11 were previously not known, were identified in 28 JME patients. These mutations accounted for about 6% of the patients examined. Functional studies suggest that these EFHC1 mutations result in microtubule‐related abnormalities during cell division. In silico analysis for a subset of mutations suggests that they may affect EFHC1 protein domains, compromising its ability to interact with other proteins. Our observations strengthen the evidence supporting a role for EFHC1 in JME in a population ethnically and geographically distinct from the one in which the gene was initially identified, and broaden the extent of allelic heterogeneity in the gene.
We report identification of previously unknown EFHC1 mutations among 480 JME patients from India. Functional studies suggest that these EFHC1 mutations result in microtubule‐related defects in cell division; and in silico analysis for a subset of mutations suggests that they may affect EFHC1 protein domains, compromising its ability to interact with other proteins. Our observations strengthen the role of EFHC1 in etiology of JME in a population ethinically distinct from the one in which the gene was initialy identified.
The preparation of gold (Au) nanostructures electrodeposited on reduced graphene oxide (RGO) modified glassy carbon (GC) electrode and its application towards fuel cell reactions in alkaline medium ...are reported. The modified electrode was characterized by cyclic voltammetry, reflectance UV–VIS spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. The Au nanostructures deposited RGO modified electrode showed synergistic catalytic behavior towards the electrocatalytic oxygen reduction reaction (ORR). The cyclic voltammogram recorded for the modified electrode revealed a quasi-reversible behavior for ORR and the Koutecky–Levich (K–L) plots showed a two-electron transfer process involved ORR at the modified electrode. The modified electrode also showed a good electrocatalytic activity towards the oxidation of formic acid. Therefore, the present work reports a facile method to fabricate RGO based noble metal nanostructures as electrocatalyst for fuel cell applications.
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•RGO/Au modified electrode was fabricated and characterized.•Synergistic ORR activity was observed at the modified electrode.•ORR followed a two electron transfer pathway to form H2O2.•Oxidation of formic acid followed a dehydrogenation pathway at modified electrode.
Abstract Mouse models have increased our understanding of the pathogenesis of medulloblastoma (MB), the most common malignant pediatric brain tumor that often forms in the cerebellum. A major goal of ...ongoing research is to better understand the early stages of tumorigenesis and to establish the genetic and environmental changes that underlie MB initiation and growth. However, studies of MB progression in mouse models are difficult due to the heterogeneity of tumor onset times and growth patterns and the lack of clinical symptoms at early stages. Magnetic resonance imaging (MRI) is critical for noninvasive, longitudinal, three-dimensional (3D) brain tumor imaging in the clinic but is limited in resolution and sensitivity for imaging early MBs in mice. In this study, high-resolution (100 μm in 2 hours) and high-throughput (150 μm in 15 minutes) manganese-enhanced MRI (MEMRI) protocols were optimized for early detection and monitoring of MBs in a Patched-1 ( Ptch1 ) conditional knockout (CKO) model. The high tissue contrast obtained with MEMRI revealed detailed cerebellar morphology and enabled detection of MBs over a wide range of stages including pretumoral lesions as early as 2 to 3 weeks postnatal with volumes close to 0.1 mm3 . Furthermore, longitudinal MEMRI allowed noninvasive monitoring of tumors and demonstrated that lesions within and between individuals have different tumorigenic potentials. 3D volumetric studies allowed quantitative analysis of MB tumor morphology and growth rates in individual Ptch1- CKO mice. These results show that MEMRI provides a powerful method for early in vivo detection and longitudinal imaging of MB progression in the mouse brain.
Pediatric high-grade gliomas, specifically diffuse midline gliomas, account for only 20% of clinical cases but are 100% fatal. A majority of the DMG cases are characterized by the signature K27M ...mutation in histone H3. The H3K27M mutation opposes the function of enhancer of zeste homolog 2 (EZH2), the methyltransferase enzyme of the polycomb repressor complex 2. However, the role of EZH2 in DMG pathogenesis is unclear. In this study, we demonstrate a tumor suppressor function for EZH2 using Ezh2 loss- and gain-of-function studies in H3WT DMG mouse models. Genetic ablation of Ezh2 increased cell proliferation and tumor grade while expression of an Ezh2 gain-of-function mutation significantly reduced tumor incidence and increased tumor latency. Transcriptomic analysis revealed that Ezh2 deletion upregulates an inflammatory response with upregulation of immunoproteasome genes such as Psmb8, Psmb9, and Psmb10. Ezh2 gain-of-function resulted in enrichment of the oxidative phosphorylation/mitochondrial metabolic pathway namely the isocitrate dehydrogenase Idh1/2/3 genes. Pharmacological inhibition of EZH2 augmented neural progenitor cell proliferation, supporting the tumor suppressive role of EZH2. In vivo 7-day treatment of H3K27M DMG tumor bearing mice with an EZH2 inhibitor, Tazemetostat, did not alter proliferation or significantly impact survival. Together our results suggest that EZH2 has a tumor suppressor function in DMG and warrants caution in clinical translation of EZH2 inhibitors to treat patients with DMG.
Proteins anchored to the cell surface via glycosylphosphatidylinositol (GPI) play various key roles in the human body, particularly in development and neurogenesis. As such, many developmental ...disorders are caused by mutations in genes involved in the GPI biosynthesis and remodeling pathway. We describe ten unrelated families with bi-allelic mutations in PIGB, a gene that encodes phosphatidylinositol glycan class B, which transfers the third mannose to the GPI. Ten different PIGB variants were found in these individuals. Flow cytometric analysis of blood cells and fibroblasts from the affected individuals showed decreased cell surface presence of GPI-anchored proteins. Most of the affected individuals have global developmental and/or intellectual delay, all had seizures, two had polymicrogyria, and four had a peripheral neuropathy. Eight children passed away before four years old. Two of them had a clinical diagnosis of DOORS syndrome (deafness, onychodystrophy, osteodystrophy, mental retardation, and seizures), a condition that includes sensorineural deafness, shortened terminal phalanges with small finger and toenails, intellectual disability, and seizures; this condition overlaps with the severe phenotypes associated with inherited GPI deficiency. Most individuals tested showed elevated alkaline phosphatase, which is a characteristic of the inherited GPI deficiency but not DOORS syndrome. It is notable that two severely affected individuals showed 2-oxoglutaric aciduria, which can be seen in DOORS syndrome, suggesting that severe cases of inherited GPI deficiency and DOORS syndrome might share some molecular pathway disruptions.