Dual-task turn velocity - a novel digital biomarker for mild cognitive impairment and dementia.

Background: Disorders associated with cognitive impairment impose a significant burden on both families and society. Previous studies have indicated that gait characteristics under dual-task as reliable markers of early cognitive impairment. Therefore, digital gait detection has great potential for future cognitive screening. However, research on digital biomarkers based on smart devices to identify cognitive impairment remains limited. The aim of this study is to explore digital gait biomarkers by utilizing intelligent wearable devices for discriminating mild cognitive impairment and dementia. Methods: This study included 122 subjects (age: 74.7 ± 7.7 years) diagnosed with normal cognition (NC, n = 38), mild cognitive impairment (MCI, n = 42), or dementia (n = 42). All subjects underwent comprehensive neuropsychological assessments and cranial Magnetic Resonance Imaging (MRI). Gait parameters were collected using validated wearable devices in both single-task and dual-task (DT). We analyzed the ability of gait variables to predict MCI and dementia, and examined the correlations between specific DT-gait parameters and sub-cognitive functions as well as hippocampal atrophy. Results: Our results demonstrated that dual-task could significantly improve the ability to predict cognitive impairment based on gait parameters such as gait speed (GS) and stride length (SL). Additionally, we discovered that turn velocity (TV and DT-TV) can be a valuable novel digital marker for predicting MCI and dementia, for identifying MCI (DT-TV: AUC = 0.801, sensitivity 0.738, specificity 0.842), and dementia (DT-TV: AUC = 0.923, sensitivity 0.857, specificity 0.842). The correlation analysis and linear regression analysis revealed a robust association between DT-TV and memory function, as well as the hippocampus atrophy. Conclusion: This study presents a novel finding that DT-TV could accurately identify varying degrees of cognitive impairment. DT-TV is strongly correlated with memory function and hippocampus shrinkage, suggests that it can accurately reflect changes in cognitive function. Therefore, DT-TV could serve as a novel and effective digital biomarker for discriminating cognitive impairment.

Regional white matter hyperintensity volume predicts persistent cognitive impairment in acute lacunar infarct patients.

Background: White matter hyperintensity (WMH) is often described in acute lacunar stroke (ALS) patients. However, the specific relationship between regional WMH volume and persistent cognitive impairment remains unclear. Methods: We enrolled patients with ALS who were hospitalized at the First Affiliated Hospital of Soochow University between January 2020 and November 2022. All patients were assessed for global cognitive function using the Montreal Cognitive Assessment (MoCA) scale at 14 ± 2 days and 6 months after the onset of ALS. Manifestations of chronic cerebral small vessel disease (CSVD) were assessed via MRI scan. The distributions of regional WMH were segmented, and their relationship with cognitive impairment was evaluated. Results: A total of 129 patients were enrolled. Baseline frontal WMH volume (OR = 1.18, P = 0.04) was an independent risk factor for long-term cognitive impairment after ALS. Furthermore, the presence of WMH at the genu of the corpus callosum (GCC) at baseline (OR = 3.1, P = 0.033) was strongly associated with persistent cognitive decline. Multivariable logistic regression analysis showed that depression (OR = 6.252, P = 0.029), NIHSS score (OR = 1.24, P = 0.011), and albumin at admission (OR = 0.841, P = 0.032) were also important determinants of long-term cognitive impairment after ALS. Conclusions: Our study found that WMH, especially frontal WMH volume and the presence of WMH at the GCC at baseline, independently contributed to long-term cognitive decline in ALS patients. This study provides new evidence of the clinical relationship between regional WMH volume and cognitive impairment in ALS patients.

Dual role of lipids for genome stability and pluripotency facilitates full potency of mouse embryonic stem cells.

While Mek1/2 and Gsk3ß inhibition ("2i") supports the maintenance of murine embryonic stem cells (ESCs) in a homogenous naïve state, prolonged culture in 2i results in aneuploidy and DNA hypomethylation that impairs developmental potential. Additionally, 2i fails to support derivation and culture of fully potent female ESCs. Here we find that mouse ESCs cultured in 2i/LIF supplemented with lipid-rich albumin (AlbuMAX) undergo pluripotency transition yet maintain genomic stability and full potency over long-term culture. Mechanistically, lipids in AlbuMAX impact intracellular metabolism including nucleotide biosynthesis, lipid biogenesis, and TCA cycle intermediates, with enhanced expression of DNMT3s that prevent DNA hypomethylation. Lipids induce a formative-like pluripotent state through direct stimulation of Erk2 phosphorylation, which also alleviates X chromosome loss in female ESCs. Importantly, both male and female "all-ESC" mice can be generated from de novo derived ESCs using AlbuMAX-based media. Our findings underscore the importance of lipids to pluripotency and link nutrient cues to genome integrity in early development.

Pharmacological disruption of mSWI/SNF complex activity restricts SARS-CoV-2 infection.

Identification of host determinants of coronavirus infection informs mechanisms of viral pathogenesis and can provide new drug targets. Here we demonstrate that mammalian SWItch/Sucrose Non-Fermentable (mSWI/SNF) chromatin remodeling complexes, specifically canonical BRG1/BRM-associated factor (cBAF) complexes, promote severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and represent host-directed therapeutic targets. The catalytic activity of SMARCA4 is required for mSWI/SNF-driven chromatin accessibility at the ACE2 locus, ACE2 expression and virus susceptibility. The transcription factors HNF1A/B interact with and recruit mSWI/SNF complexes to ACE2 enhancers, which contain high HNF1A motif density. Notably, small-molecule mSWI/SNF ATPase inhibitors or degraders abrogate angiotensin-converting enzyme 2 (ACE2) expression and confer resistance to SARS-CoV-2 variants and a remdesivir-resistant virus in three cell lines and three primary human cell types, including airway epithelial cells, by up to 5 logs. These data highlight the role of mSWI/SNF complex activities in conferring SARS-CoV-2 susceptibility and identify a potential class of broad-acting antivirals to combat emerging coronaviruses and drug-resistant variants.

Bat pluripotent stem cells reveal unusual entanglement between host and viruses.

Bats are distinctive among mammals due to their ability to fly, use laryngeal echolocation, and tolerate viruses. However, there are currently no reliable cellular models for studying bat biology or their response to viral infections. Here, we created induced pluripotent stem cells (iPSCs) from two species of bats: the wild greater horseshoe bat (Rhinolophus ferrumequinum) and the greater mouse-eared bat (Myotis myotis). The iPSCs from both bat species showed similar characteristics and had a gene expression profile resembling that of cells attacked by viruses. They also had a high number of endogenous viral sequences, particularly retroviruses. These results suggest that bats have evolved mechanisms to tolerate a large load of viral sequences and may have a more intertwined relationship with viruses than previously thought. Further study of bat iPSCs and their differentiated progeny will provide insights into bat biology, virus host relationships, and the molecular basis of bats' special traits.

The mean diffusivity of forceps minor is useful to distinguish amnestic mild cognitive impairment from mild cognitive impairment caused by cerebral small vessel disease.

Objectives: In recent years, the desire to make a more fine-grained identification on mild cognitive impairment (MCI) has become apparent, the etiological diagnosis of MCI in particular. Nevertheless, new methods for the etiological diagnosis of MCI are currently insufficient. The objective of this study was to establish discriminative measures for amnestic mild cognitive impairment (a-MCI) and MCI caused by cerebral small vessel disease (CSVD). Materials and methods: In total, 20 normal controls (NCs), 33 a-MCI patients, and 25 CSVD-MCI patients performed comprehensive neuropsychological assessments concerning global cognitive function and five cognitive domains as well as magnetic resonance imaging scan with diffusion tensor imaging (DTI). Diffusion parameters including fractional anisotropy and mean diffusivity of 20 major white matter metrics were obtained by ROI-based analyses. The neuropsychological tests and diffusion measurements were compared and binary logistic regression was used to identify the best differential indicator for the two MCI subgroups. The discriminating power was calculated by receiver operating characteristic analysis. Results: Amnestic mild cognitive impairment group showed significant impairment in memory and language function, while CSVD-MCI group revealed more deficits in multi-cognitive domains of memory, language, attention and executive function than controls. Compared to the a-MCI, CSVD-MCI was significantly dysfunctional in the executive function. The CSVD-MCI group had decreased fractional anisotropy and increased mean diffusivity values throughout widespread white matter areas. CSVD-MCI presented more severe damage in the anterior thalamic radiation, forceps major, forceps minor and right inferior longitudinal fasciculus compared with a-MCI group. No significant neuropsychological tests were found in the binary logistic regression model, yet the DTI markers showed a higher discriminative power than the neuropsychological tests. The Stroop test errors had moderate potential (AUC = 0.747; sensitivity = 76.0%; specificity = 63.6%; P = 0.001; 95% CI: 0.617-0.877), and the mean diffusivity value of forceps minor demonstrated the highest predictive power to discriminate each MCI subtype (AUC = 0.815; sensitivity = 88.0%; specificity = 72.7%; P < 0.001; 95% CI: 0.698-0.932). Conclusion: The mean diffusivity of forceps minor may serve as an optimal indicator to differentiate between a-MCI and CSVD-MCI.

A new nomogram including total cerebral small vessel disease burden for individualized prediction of early-onset depression in patients with acute ischemic stroke.

Objectives: The present study was designed to evaluate the effects of total cerebral small vessel disease (CSVD) on early-onset depression after acute ischemic stroke (AIS), and to develop a new nomogram including total CSVD burden to predict early-onset post-stroke depression (PSD). Methods: We continuously enrolled patients with AIS who were hospitalized at the First Affiliated Hospital of Soochow University between October 2017 and June 2019. All patients were assessed for depressive symptoms using the 17-item Hamilton Depression Scale (HAMD-17) at 14 ± 2 days after the onset of AIS. The diagnosis for depression was made according to the American Diagnostic and Statistical Manual of Mental Disorders Version 5 (DSM-5). The demographic and clinical data were collected including total CSVD burden. On the basis of a multivariate logistic model, the independent factors of early-onset PSD were identified and the predictive nomogram was generated. The performance of the nomogram was evaluated by Harrell's concordance index (C-index) and calibration plot. Results: A total of 346 patients were enrolled. When contrasted to a 0 score of total CSVD burden, the score ≥2 (moderate to severe total CSVD burden) was an independent risk factor for early-onset PSD. Besides, gender, cognitive impairments, baseline Barthel Index (BI), and plasma fibrinogen were independently associated with early-onset PSD. The nomogram based on all these five independent risk factors was developed and validated with an Area Under Curve (AUC) of 0.780. In addition, the calibration plot revealed an adequate fit of the nomogram in predicting the risk of early-onset depression in patients with AIS. Conclusions: Our study found the total CSVD burden score of 2-4 points was an independent risk factor of early-onset PSD. The proposed nomogram based on total CSVD burden, gender, cognitive impairments, baseline BI, and plasma fibrinogen concentration gave rise to a more accurate and more comprehensive prediction for early-onset PSD.

Generation of sex-reversed female clonal mice via CRISPR/Cas9-mediated Y chromosome deletion in male embryonic stem cells.

Mice derived entirely from embryonic stem (ES) cells can be generated through tetraploid complementation. Although XY male ES cell lines are commonly used in this system, occasionally, monosomic XO female mice are produced through spontaneous Y chromosome loss. Here, we describe an efficient method to obtain monosomic XO ES cells by CRISPR/Cas9-mediated deletion of the Y chromosome allowing generation of female clonal mice by tetraploid complementation. The monosomic XO female mice are viable and able to produce normal male and female offspring. Direct generation of clonal mice in both sexes can significantly accelerate the production of complex genetically modified mouse models.

Impact of schizophrenia GWAS loci converge onto distinct pathways in cortical interneurons vs glutamatergic neurons during development.

Remarkable advances have been made in schizophrenia (SCZ) GWAS, but gleaning biological insight from these loci is challenging. Genetic influences on gene expression (e.g., eQTLs) are cell type-specific, but most studies that attempt to clarify GWAS loci's influence on gene expression have employed tissues with mixed cell compositions that can obscure cell-specific effects. Furthermore, enriched SCZ heritability in the fetal brain underscores the need to study the impact of SCZ risk loci in specific developing neurons. MGE-derived cortical interneurons (cINs) are consistently affected in SCZ brains and show enriched SCZ heritability in human fetal brains. We identified SCZ GWAS risk genes that are dysregulated in iPSC-derived homogeneous populations of developing SCZ cINs. These SCZ GWAS loci differential expression (DE) genes converge on the PKC pathway. Their disruption results in PKC hyperactivity in developing cINs, leading to arborization deficits. We show that the fine-mapped GWAS locus in the ATP2A2 gene of the PKC pathway harbors enhancer marks by ATACseq and ChIPseq, and regulates ATP2A2 expression. We also generated developing glutamatergic neurons (GNs), another population with enriched SCZ heritability, and confirmed their functionality after transplantation into the mouse brain. Then, we identified SCZ GWAS risk genes that are dysregulated in developing SCZ GNs. GN-specific SCZ GWAS loci DE genes converge on the ion transporter pathway, distinct from those for cINs. Disruption of the pathway gene CACNA1D resulted in deficits of Ca2+ currents in developing GNs, suggesting compromised neuronal function by GWAS loci pathway deficits during development. This study allows us to identify cell type-specific and developmental stage-specific mechanisms of SCZ risk gene function, and may aid in identifying mechanism-based novel therapeutic targets.

High-sensitivity C-reactive protein as a better predictor of post-thrombolytic functional outcome in patients with previous antiplatelet therapy.

BACKGROUND: C-reactive protein (CRP) is an important biomarker of inflammation and plays a pivotal role in predicting the clinical prognosis of cardiovascular and cerebrovascular diseases. However, the mechanism of inflammation influencing the outcome of patients with ischemic stroke are unknown. AIMS: We aim to investigate the association between hsCRP and mRS in 194 eligible patients by therapy-stratified analyses. METHODS: The modification effects of antiplatelet therapy on the association between mRS and different exposure variables were analyzed. The retained variables were analyzed in the receiver operating characteristic (ROC) curve to discriminate patients with poor outcome. RESULTS: hsCRP was positively correlated with mRS in therapy-stratified analyses. There was a statistical modification effect of antiplatelet therapy on the association of hsCRP and mRS (P for interaction = 0.0101). The discriminative effect of poor outcome was further verified by ROC curve analyses (AUCwith from 0.758 to 0.872, AUCwithout from 0.709 to 0.713). CONCLUSIONS: hsCRP is correlated with the clinical outcome of patients treated with IVrt-PA, and may be a better predictor of post-thrombolytic functional outcome in patients with previous antiplatelet therapy than in non-used patients.

Sec61 Inhibitor Apratoxin S4 Potently Inhibits SARS-CoV-2 and Exhibits Broad-Spectrum Antiviral Activity.

There is a pressing need for host-directed therapeutics that elicit broad-spectrum antiviral activities to potentially address current and future viral pandemics. Apratoxin S4 (Apra S4) is a potent Sec61 inhibitor that prevents cotranslational translocation of secretory proteins into the endoplasmic reticulum (ER), leading to anticancer and antiangiogenic activity both in vitro and in vivo. Since Sec61 has been shown to be an essential host factor for viral proteostasis, we tested Apra S4 in cellular models of viral infection, including SARS-CoV-2, influenza A virus, and flaviviruses (Zika, West Nile, and Dengue virus). Apra S4 inhibited viral replication in a concentration-dependent manner and had high potency particularly against SARS-CoV-2 and influenza A virus, with subnanomolar activity in human cells. Characterization studies focused on SARS-CoV-2 revealed that Apra S4 impacted a post-entry stage of the viral life-cycle. Transmission electron microscopy revealed that Apra S4 blocked formation of stacked double-membrane vesicles, the sites of viral replication. Apra S4 reduced dsRNA formation and prevented viral protein production and trafficking of secretory proteins, especially the spike protein. Given the potent and broad-spectrum activity of Apra S4, further preclinical evaluation of Apra S4 and other Sec61 inhibitors as antivirals is warranted.

Artesunate restores mitochondrial fusion-fission dynamics and alleviates neuronal injury in Alzheimer's disease models.

Alzheimer's disease (AD) remains a leading cause of dementia and no therapy that reverses underlying neurodegeneration is available. Recent studies suggest the protective role of artemisinin, an antimalarial drug, in neurological disorders. In this study, we investigated the therapeutic potential of artesunate, a water-soluble derivative of artemisinin, on amyloid-beta (Aß)-treated challenged microglial BV-2, neuronal N2a cells, and the amyloid precursor protein/presenilin (APP/PS1) mice model. We found that Aß significantly induced multiple AD-related phenotypes, including increased expression/production of pro-inflammatory cytokines from microglial cells, enhanced cellular and mitochondrial production of reactive oxygen species, promoted mitochondrial fission, inhibited mitochondrial fusion, suppressed mitophagy or biogenesis in both cell types, stimulated apoptosis of neuronal cells, and microglia-induced killing of neurons. All these in vitro phenotypes were attenuated by artesunate. In addition, the over-expression of the mitochondrial fission protein Drp-1, or down-regulation of the mitochondrial fusion protein OPA-1 both reduced the therapeutic benefits of artesunate. Artesunate also alleviated AD phenotypes in APP/PS1 mice, reducing Aß deposition, and reversing deficits in memory and learning. Artesunate protects neuronal and microglial cells from AD pathology, both in vitro and in vivo. Maintaining mitochondrial dynamics and simultaneously targeting multiple AD pathogenic mechanisms are associated with the protective effects of artesunate. Consequently, artesunate may become a promising therapeutic for AD.

Mutations in SARS-CoV-2 variants of concern link to increased spike cleavage and virus transmission.

SARS-CoV-2 lineages have diverged into highly prevalent variants termed "variants of concern" (VOCs). Here, we characterized emerging SARS-CoV-2 spike polymorphisms in vitro and in vivo to understand their impact on transmissibility and virus pathogenicity and fitness. We demonstrate that the substitution S:655Y, represented in the gamma and omicron VOCs, enhances viral replication and spike protein cleavage. The S:655Y substitution was transmitted more efficiently than its ancestor S:655H in the hamster infection model and was able to outcompete S:655H in the hamster model and in a human primary airway system. Finally, we analyzed a set of emerging SARS-CoV-2 variants to investigate how different sets of mutations may impact spike processing. All VOCs tested exhibited increased spike cleavage and fusogenic capacity. Taken together, our study demonstrates that the spike mutations present in VOCs that become epidemiologically prevalent in humans are linked to an increase in spike processing and virus transmission.

Better Screening Value of Sylvian Fissure Ratio on Cognitive Decline Among Female Compared to Male: An Observational Study in Elderly Patients With Cerebral Small Vessel Disease in Soochow.

Background: Cognitive decline (CD) occurs frequently in elderly patients with cerebral small vessel disease (CSVD). In China, elderly patients are more likely to enter healthcare in community hospitals where no magnetic resonance imaging (MRI) is available. This study aimed to explore the screening value of Sylvian fissure ratio (SFR) on CD and compare its gender difference from community-transferred patients. Methods: We performed a single-center, observational study (collected between April 1, 2016, and March 1, 2019) to evaluate the association between Montreal Cognitive Assessment (MoCA) and SFR in 203 eligible community-transferred patients. Baseline characteristics of patients were collected during hospitalization. Multiple linear regression analyses were used to estimate the effect of variables on MoCA, and interactions between select variables were analyzed in different models. Receiver operating characteristic (ROC) curve analysis was used to evaluate the discriminative effect of SFR to severe CD. Results: We identified that a meaningful SFR cutoff of 0.05 had important screening value (likelihood ratio test, p = 0.067) on CD. The ratio had a lower screen value in males when compared to females (adjusted ß, -5.54; 95% CI, -8.78 to -2.30 vs. adjusted ß, -1.01; 95% CI, -2.84 to 0.82). The gender difference was further verified by ROC curve analysis, in which this discriminative effect was more potent in females (from 0.878 to 0.948) compared to males (from 0.838 to 0.837). Conclusion: An SFR of 0.05 may be more useful to distinguish CD in female patients with CSVD than male patients in whom the syndrome is suspected clinically.

Targeted gene correction and functional recovery in achondroplasia patient-derived iPSCs.

BACKGROUND: Achondroplasia (ACH) is the most common genetic form of dwarfism and belongs to dominant monogenic disorder caused by a gain-of-function point mutation in the transmembrane region of FGFR3. There are no effective treatments for ACH. Stem cells and gene-editing technology provide us with effective methods and ideas for ACH research and treatment. METHODS: We generated non-integrated iPSCs from an ACH girl's skin and an ACH boy's urine by Sendai virus. The mutation of ACH iPSCs was precisely corrected by CRISPR-Cas9. RESULTS: Chondrogenic differentiation ability of ACH iPSCs was confined compared with that of healthy iPSCs. Chondrogenic differentiation ability of corrected ACH iPSCs could be restored. These corrected iPSCs displayed pluripotency, maintained normal karyotype, and demonstrated none of off-target indels. CONCLUSIONS: This study may provide an important theoretical and experimental basis for the ACH research and treatment.

Breakthrough of interspecific chimerism: blocking apoptosis.

On January 28 in Nature online, Zheng et al. (Nature, 2021 (Online ahead of print)) reported that they developed an ingenious method of interspecies PSC co-culture system in vitro which unfolded interspecific cell competition. This study paves the way for discovering the mechanism of interspecific chimera and for further interspecific organogenesis between evolutionarily distant species.

Bilobalide alleviates neuroinflammation and promotes autophagy in Alzheimer's disease by upregulating lincRNA-p21.

EGb 761 has some protective effects on AD and can improve the cognitive functions of AD mice. However, the underlying molecular mechanisms are unknown. Here, we investigated the function of bilobalide, the effective component of EGb 761, in neuroinflammation and autophagy during AD. LPS-treated BV-2 cells were used as an in vitro model for neuroinflammation. The APP/PS1 AD mouse line was used to examine the function of bilobalide in AD. ELISA and qRT-PCR were used to measure the levels of proinflammatory cytokines, including TNF-α, IL-6 and IL-1ß. Western blotting was employed to determine the protein levels of p-p65, iNOS, COX-2, LC3, beclin-1, p62 and p-STAT3. Immunostaining was applied to examine the number of autophagosomes. LPS treatment induced inflammatory responses and inhibited autophagy in BV-2 cells. Bilobalide suppressed LPS-induced neuroinflammation and promoted autophagy. Furthermore, bilobalide treatment increased the lincRNA-p21 levels, which suppressed STAT3 signalling. Knockdown of lincRNA-p21 reversed the effects of bilobalide. Overexpression of lincRNA-p21 promoted autophagy and inhibited neuroinflammation as well while STAT3 inhibitor blocked the effects of si-lincRNA-p21. In vivo experiments revealed that bilobalide improved the learning and memory capabilities of APP/PS1 AD mice. Bilobalide improves the cognitive functions of APP/PS1 AD mice. Mechanistically, bilobalide suppresses inflammatory responses and promotes autophagy possibly by upregulating lincRNA-p21 levels.

The Efficacy of Percutaneous Patent Foramen Ovale Closure on Migraine: a Meta-Analysis of Randomized Controlled Trials and Observational Studies.

OBJECTIVES: Whether patent foramen ovale (PFO) closure is effective on migraine is controversial. This article was aimed at assessing the efficacy of PFO closure on migraine based on randomized controlled trials (RCTs) and observational studies. METHODS: We searched PubMed, Embase, and Cochrane databases up to October 2020 evaluating PFO closure versus control in patients with migraine, then conducted a meta-analysis of all RCTs and observational studies, respectively. The main outcomes were (1) respond rate: complete cessation of migraine; (2) reduction in the frequency of migraine attacks per month; and (3) reduction in migraine days per month. RESULTS: Seven studies (3 RCTs and 4 observational studies), containing 887 migraine patients, were identified. (1) The respond rate of PFO closure on migraine was significantly higher than control group both in RCT subgroup and observational studies subgroup (OR 3.86, 95% CI 1.35-11.04, P = 0.01 in RCTs; OR 8.28, 95% CI 2.31-29.67, P = 0.001 in observational studies). (2) Reduction in frequency of migraine attacks was higher in PFO closure group compared with control group in the RCT subgroup analysis (mean difference (MD) = 0.57, 95% CI 0.23-0.90, P = 0.0009). (3) Reduction in migraine days was also higher in PFO closure group compared with control group in the RCT subgroup analysis (MD = 1.33, 95% CI 0.35-2.31, P = 0.008). CONCLUSIONS: PFO closure might be suitable for migraine patients, especially for migraine with aura, by cessation of migraine headaches or reducing migraine attacks and migraine days.

Design Method of Multiwavelength EMATs Based on Spatial Domain Harmonic Control.

Conventional electromagnetic acoustic transducers (EMATs) are generally only used to generate and detect guided waves with a single wavelength, which increases their sensitivity at that particular wavelength but limits their application scenarios and the accuracy of defect assessment. This article proposes a design method for multiwavelength EMATs based on spatial-domain harmonic control. First, the EMAT model is analyzed, where it is then outlined that the eddy-current density distribution of the specimen is equivalent to the spatial low-pass filtering of the coil-current density distribution. This shows that the multiwavelength guided waves can be achieved as long as the spatial distribution of the coil-current density contains those multiple harmonics that are desired. It is then proposed that the structure of the EMAT coil is equivalent to the spatial sampled pulse sequences of a spatial signal. The coil parameter design based on pulse modulation technology is proposed. Taking a dual-wavelength EMAT design for Lamb waves as an example, details of the coil parameter design are presented. The simulation and experiment with the dual-wavelength EMAT proved the correctness of the proposed method. Finally, an experiment with a three-wavelength EMAT demonstrated the feasibility of the proposed method in designing multiwavelength EMATs.

Generation of Sex-Reversed Female Clonal Mice via CRISPR-Cas9-Mediated Y Chromosome Deletion in Male Embryonic Stem Cells.

Mice derived entirely from embryonic stem (ES) cells can be generated through tetraploid complementation. Although XY male ES cell lines are commonly used in this system, occasionally, monosomic XO female mice are produced through spontaneous Y chromosome loss. Here, we describe an efficient method to obtain monosomic XO ES cells by CRISPR-Cas9-mediated deletion of the Y chromosome, allowing generation of female clonal mice by tetraploid complementation. The monosomic XO female mice are viable and able to produce normal male and female offspring. Direct generation of clonal mice in both sexes can significantly accelerate the production of complex genetically modified mouse models.