Contribution of Somatic Ras/Raf/Mitogen-Activated Protein Kinase Variants in the Hippocampus in Drug-Resistant Mesial Temporal Lobe Epilepsy

Importance: Mesial temporal lobe epilepsy (MTLE) is the most common focal epilepsy subtype and is often refractory to antiseizure medications. While most patients with MTLE do not have pathogenic germline genetic variants, the contribution of postzygotic (ie, somatic) variants in the brain is unknown. Objective: To test the association between pathogenic somatic variants in the hippocampus and MTLE. Design, Setting, and Participants: This case-control genetic association study analyzed the DNA derived from hippocampal tissue of neurosurgically treated patients with MTLE and age-matched and sex-matched neurotypical controls. Participants treated at level 4 epilepsy centers were enrolled from 1988 through 2019, and clinical data were collected retrospectively. Whole-exome and gene-panel sequencing (each genomic region sequenced more than 500 times on average) were used to identify candidate pathogenic somatic variants. A subset of novel variants was functionally evaluated using cellular and molecular assays. Patients with nonlesional and lesional (mesial temporal sclerosis, focal cortical dysplasia, and low-grade epilepsy-associated tumors) drug-resistant MTLE who underwent anterior medial temporal lobectomy were eligible. All patients with available frozen tissue and appropriate consents were included. Control brain tissue was obtained from neurotypical donors at brain banks. Data were analyzed from June 2020 to August 2022. Exposures: Drug-resistant MTLE. Main Outcomes and Measures: Presence and abundance of pathogenic somatic variants in the hippocampus vs the unaffected temporal neocortex. Results: Of 105 included patients with MTLE, 53 (50.5%) were female, and the median (IQR) age was 32 (26-44) years; of 30 neurotypical controls, 11 (36.7%) were female, and the median (IQR) age was 37 (18-53) years. Eleven pathogenic somatic variants enriched in the hippocampus relative to the unaffected temporal neocortex (median [IQR] variant allele frequency, 1.92 [1.5-2.7] vs 0.3 [0-0.9]; P =.01) were detected in patients with MTLE but not in controls. Ten of these variants were in PTPN11, SOS1, KRAS, BRAF, and NF1, all predicted to constitutively activate Ras/Raf/mitogen-activated protein kinase (MAPK) signaling. Immunohistochemical studies of variant-positive hippocampal tissue demonstrated increased Erk1/2 phosphorylation, indicative of Ras/Raf/MAPK activation, predominantly in glial cells. Molecular assays showed abnormal liquid-liquid phase separation for the PTPN11 variants as a possible dominant gain-of-function mechanism. Conclusions and Relevance: Hippocampal somatic variants, particularly those activating Ras/Raf/MAPK signaling, may contribute to the pathogenesis of sporadic, drug-resistant MTLE. These findings may provide a novel genetic mechanism and highlight new therapeutic targets for this common indication for epilepsy surgery

Catestatin Improves Post-Ischemic Left Ventricular Function and Decreases Ischemia/Reperfusion Injury in Heart

The Chromogranin A (CgA)-derived anti-hypertensive peptide catestatin (CST) antagonizes catecholamine secretion, and is a negative myocardial inotrope acting via a nitric oxide-dependent mechanism. It is not known whether CST contributes to ischemia/reperfusion injury or is a component of a cardioprotective response to limit injury. Here, we tested whether CST by virtue of its negative inotropic activity improves post-ischemic cardiac function and cardiomyocyte survival. Three groups of isolated perfused hearts from adult Wistar rats underwent 30-min ischemia and 120-min reperfusion (I/R, Group 1), or were post-conditioned by brief ischemic episodes (PostC, 5-cycles of 10-s I/R at the beginning of 120-min reperfusion, Group 2), or with exogenous CST (75 nM for 20 min, CST-Post, Group-3) at the onset of reperfusion. Perfusion pressure and left ventricular pressure (LVP) were monitored. Infarct size was evaluated with nitroblue-tetrazolium staining. The CST (5 nM) effects were also tested in simulated ischemia/reperfusion experiments on cardiomyocytes isolated from young-adult rats, evaluating cell survival with propidium iodide labeling. Infarct size was 61 ± 6% of risk area in hearts subjected to I/R only. PostC reduced infarct size to 34 ± 5%. Infarct size in CST-Post was 36 ± 3% of risk area (P < 0.05 respect to I/R). CST-Post reduced post-ischemic rise of diastolic LVP, an index of contracture, and significantly improved post-ischemic recovery of developed LVP. In isolated cardiomyocytes, CST increased the cell viability rate by about 65% after simulated ischemia/reperfusion. These results suggest a novel cardioprotective role for CST, which appears mainly due to a direct reduction of post-ischemic myocardial damages and dysfunction, rather than to an involvement of adrenergic terminals and/or endothelium

Multi-ancestry genome-wide association meta-analysis of Parkinson’s disease

\ua9 2023, This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply. Although over 90 independent risk variants have been identified for Parkinson’s disease using genome-wide association studies, most studies have been performed in just one population at a time. Here we performed a large-scale multi-ancestry meta-analysis of Parkinson’s disease with 49,049 cases, 18,785 proxy cases and 2,458,063 controls including individuals of European, East Asian, Latin American and African ancestry. In a meta-analysis, we identified 78 independent genome-wide significant loci, including 12 potentially novel loci (MTF2, PIK3CA, ADD1, SYBU, IRS2, USP8, PIGL, FASN, MYLK2, USP25, EP300 and PPP6R2) and fine-mapped 6 putative causal variants at 6 known PD loci. By combining our results with publicly available eQTL data, we identified 25 putative risk genes in these novel loci whose expression is associated with PD risk. This work lays the groundwork for future efforts aimed at identifying PD loci in non-European populations

Strain and Lattice Orientation Distribution in SiN/Ge CMOS Compatible Light Emitting Microstructures by Quick X-ray Nano-diffraction Microscopy

This paper presents a study of the spatial distribution of strain and lattice orientation in CMOS-fabricated strained Ge microstripes using high resolution x-ray micro-diffraction (µ-HRXRD). The recently developed model-free characterization tool, based on a quick scanning x-ray diffraction microscopy technique can image strain down to levels of 10-5 (Δa/a)with a spatial resolution of ~0.5 µm. Strain and lattice tilt are extracted using the strain and orientation calculation software package X-SOCS. The obtained results are compared with the biaxial strain distribution obtained by lattice parameter-sensitive µ-Raman and µ-photoluminescence measurements. The experimental data are interpreted with the help of finite element modeling (FEM) of the strain relaxation dynamics in the investigated structures

Imaging structure and composition homogeneity of 300 mm SiGe virtual substrates for advanced CMOS applications by scanning X-ray diffraction microscopy

Advanced semiconductor heterostructures are at the very heart of many modern technologies, including aggressively scaled complementary metal oxide semiconductor transistors for high performance computing and laser diodes for low power solid state lighting applications. The control of structural and compositional homogeneity of these semiconductor heterostructures is the key to success to further develop these state-of-the-art technologies. In this article, we report on the lateral distribution of tilt, composition, and strain across step-graded SiGe strain relaxed buffer layers on 300 mm Si(001) wafers treated with and without chemical−mechanical polishing. By using the advanced synchrotron based scanning X-ray diffraction microscopy technique K-Map together with micro-Raman spectroscopyand Atomic Force Microscopy, we are able to establish a partial correlation between real space morphology and structuralproperties of the sample resolved at the micrometer scale. In particular, we demonstrate that the lattice plane bending of thecommonly observed cross-hatch pattern is caused by dislocations. Our results show a strong local correlation between the strain field and composition distribution, indicating that the adatom surface diffusion during growth is driven by strain field fluctuations induced by the underlying dislocation network. Finally, it is revealed that a superficial chemical mechanical polishing of cross-hatched surfaces does not lead to any significant change of tilt, composition, and strain variation compared to that of as-grown complementary metal oxide semiconductor transistors for high performance computing and laser diodes for low power solid state lighting applications. The control of structural and compositional homogeneity of these semiconductor heterostructures is the key to success to further develop these state-of-the-art technologies. In this article, we report on the lateral distribution of tilt, composition, and strain across step-graded SiGe strain relaxed bu ff er layers on 300 mm Si(001) wafers treated with and without chemical − mechanical polishing. By using the advanced synchrotron based scanning X-ray di ff raction microscopy technique K-Map together with micro-Raman spectroscopy and Atomic Force Microscopy, we are able to establish a partial correlation between real space morphology and structural properties of the sample resolved at the micrometer scale. In particular, we demonstrate that the lattice plane bending of the commonly observed cross-hatch pattern is caused by dislocations. Our results show a strong local correlation between the strain fi eld and composition distribution, indicating that the adatom surface di ff usion during growth is driven by strain fi eld fl uctuations induced by the underlying dislocation network. Finally, it is revealed that a super fi cial chemical − mechanical polishing of cross- hatched surfaces does not lead to any significant change of tilt, composition, and strain variation compared to that of as-grown sample