Lovastatin impairs cellular proliferation and enhances hyaluronic acid production in fibroblast-like synoviocytes

INTRODUCTION

Statins have demonstrated chondroprotective effects by reducing inflammation and mitigating extracellular matrix degradation. However, statins are also reported to be cytotoxic to several types of cells. Early-onset osteoarthritis (OA) is characterized by synovial inflammation, which adversely affects hyaluronan (HA) production in fibroblast-like synoviocytes (FLSs). Nevertheless, the precise effects of statins on the synovium remain unclear.

METHODS

This study investigated the impact of lovastatin on human FLSs, and HA secretion-related genes, signaling pathways, and production were evaluated.

RESULTS

The findings revealed that high doses of lovastatin (20 or 40 μM) decreased FLS viability and increased cell death. FLS proliferation ceased when cultured in a medium containing 5 or 10 μM lovastatin. mRNA expression analysis demonstrated that lovastatin (5 and 10 μM) upregulated the gene level of hyaluronan synthase 1 (HAS1), HAS2, and proteoglycan 4 (PRG4), but not HAS3. While the expression of multidrug resistance-associated protein 5 transporter gene remained unaffected, both inward-rectifying potassium channel and acid-sensing ion channel 3 were upregulated. Western blot further confirmed that lovastatin increased the production of HAS1 and PRG4, and activated the PKC-α, ERK1/2, and p38-MAPK signaling pathways. Additionally, lovastatin elevated intracellular cAMP levels and HA production in FLSs.

CONCLUSION

Lovastatin impairs cellular proliferation but enhances HA production in human FLSs.

[Pay attention to molecular pathological diagnosis of pediatric glioma]

Glioma is one of the most common central nervous system tumors in children.Increasing studies show that compared with adults, some gliomas in children have unique molecular genetic characteristics and completely different biological behaviors, although they are similar to adults in morphology and nomenclature. Therefore, pediatric glioma is by no means a "miniature version" of adults. In the 5th edition of WHO classification of central nervous system tumors published in the end of 2021, one of the most important revisions is the division of the classification into adult-type and pediatric-type diffuse gliomas, and the latter is further divided into pediatric-type diffuse low-grade gliomas and pediatric-type diffuse high-grade gliomas. In addition to histological morphology and clinical features, the basis of classification includes more molecular features. Therefore, in clinical practice, we need to pay more attention to the significance of molecular pathological diagnosis in the diagnosis and treatment of gliomas in children.

[Research progress of pyruvate kinase type M2 in hepatocellular carcinoma]

Primary hepatocellular carcinoma is one of the most common high-grade malignant tumors in the world. Its incidence ranks fifth among malignant tumors in China, and various therapeutic measures have poor curative effect. Pyruvate kinase type M2 is a key enzyme in the glycolytic pathway, and its abnormal expression in liver cancer is closely related to the proliferation, metastasis, diagnosis, treatment, prognosis, as well as drug and radiation resistance. Therefore, multi-pathway targeted regulation of pyruvate kinase type M2 use is expected to become a new direction for the treatment of primary liver cancer.

[Analysis of the short-and medium-term curative effect of TIPS approach combined with AngioJet thrombus aspiration technology treatment in acute portal vein thrombosis]

Objective: To evaluate the short- and medium-term clinical efficacy of TIPS approach combined with AngioJet thrombus aspiration technology treatment in acute portal vein thrombosis. Methods: 63 cases with acute portal vein thrombosis treated in our center from May 2017 to July 2019 were studied retrospectively, including 49 males and 14 females, aged 35-61 (46 ± 5) years. TIPS approach (with/without) combined with Angiojet thrombus aspiration and gastroesophageal varices embolization was performed simultaneously according to the patient's condition. Regular follow-up for 3-33 (22 ± 3) months after surgery was used to observe the curative effect. Results: The technical success rate was 100%. Portal vein and superior mesenteric vein blood flow were returned to normal after the operation. Two cases of biliary tract injury were untreated. Simultaneously, two cases of intrahepatic arteriovenous fistula were treated with superselective arterial embolization. During the follow-up period, 47 cases (74.61%) had complete portal vein recanalization, 13 cases (20.63%) had partial recanalization, 3 cases (4.76%) had complete portal cavernoma, 7 cases (11.11%) had symptomatic hepatic encephalopathy, 1 case had received artificial liver treatment (1.59%), 1 case had peptic ulcer (11.11%), 6 cases (9.52%) had lost to follow-up, and there was no portal hypertension-related bleeding or death. Conclusion: TIPS approach combined with AngioJet thrombus aspiration technology is safe, effective and feasible in the treatment of acute portal vein thrombosis, and the short- and medium-term clinical effects are satisfactory.

[Clinicopathological features of diffuse leptomeningeal glioneuronal tumor]

Objective: To investigate the clinicopathological features, diagnosis and prognosis of diffuse leptomeningeal glioneuronal tumor (DLGNT). Methods: Five cases of DLGNT diagnosed from January 2016 to January 2020 were collected from Xuanwu Hospital, Capital Medical University. The clinical features, histopathologic characteristics, immunohistochemical and molecular genetic findings and prognosis were analyzed and the relevant literature was reviewed. Results: The five patients (two males and three females) were aged 2 to 52 years (median 11 years), and had history of increased intracranial pressure (headache and vomiting) or limb weakness. Three of them were younger than 16 years of age. The imaging studies showed diffuse intracranial and intraspinal nodular leptomeningeal thickening and enhancement, with or without parenchymal involvement. At times there were associated small cyst-like lesions. Imaging interpretations were inflammatory lesions in three cases and space occupying lesions in two. Microscopically, in three cases the tumors showed low to moderate cellularity, consisting of relatively monomorphous oligodendrocyte-like cells arranged in small nests or diffusely distribution. No mitosis and necrosis were observed. In two cases there were increased cellularity with a diffuse honeycomb pattern. The tumor showed mild to moderate polymorphism with hyperchromatic nuclei. Mitosis, endothelial vascular proliferation and glomeruloid vessels were seen. Necrosis was absent. The tumor cells in all five cases were positive for synaptophysin,Olig2 and negative for IDH1 and H3 K27M. GFAP was focally positive in four cases and only one case expressed NeuN partly. The Ki-67 labeling index was 1%-35%. BRAF fusion was detected in four cases. Genetic analysis showed solitary 1p deletion in two cases (2/5), while all cases were negative for 1p/19q co-deletion (0/5). The five patients were followed up for 13 to 28 months (median 15 month). One patient died after 27 months. There was no evidence of tumor progression in the remaining four patients. Conclusions: DLGNT is rare and easily confused with other central nervous system tumors and inflammatory lesions. Therefore, the diagnosis of DLGNT should be made based on comprehensive information including imaging, morphologic and corresponding immunohistochemical examinations and molecular genetics to avoid misdiagnosis and delay in management.

[Chordoid glioma: a clinicopathological study]

Objective: To analyze the clinicopathological features of chordoid glioma. Methods: A total of 12 cases of chordoid gliomas from 2009 to 2020 in Xuanwu Hospital of Capital Medical University and General Hospital of Chinese People's Liberation Army were retrospectively analyzed. The clinical and imaging characteristics, pathologic and molecular characteristics were analyzed, and the relevant literature was reviewed. Results: All 12 patients (4 males and 8 females) aged from 25 to 67 years (mean 39 years) and mainly had a history of headache or/and vision loss. MRI showed that the lesions located in the third ventricle, and they showed abnormal enhancement. Pathologically, these 12 cases displayed the morphologic characteristics of chordoid gliomas, including papillary structures in two cases. Immunohistochemically, GFAP and vimentin were expressed in all 12 cases (12/12). TTF1 was also expressed in all cases (10/10). CD34 and CKpan were seen in 11 cases (11/12). EMA with dot-and/or-ring like positivity was seen in 9 cases (9/10). Tissues were available in nine chordoid gliomas for Sanger sequencing to detect PRKCA and IDH gene mutation, and eight cases (8/9) showed PRKCA gene D463H mutation. None of these cases showed IDH1 R132 and IDH2 R172 mutation. All 12 patients underwent surgery, and four were lost to follow up. The remaining eight patients were progression or recurrence free at last follow-up in January 2021. Conclusions: Chordoid gliomas have relatively distinguishing clinical and histopathological features. PRKCA gene mutation in chordoid gliomas can be considered as a biomarker for the diagnosis and differential diagnosis of chordoid gliomas, and may provide a direction for future targeted therapy.

Silymarin modulates catabolic cytokine expression through Sirt1 and SOX9 in human articular chondrocytes

Background

Silymarin (SMN), a polyphenolic flavonoid, is involved in multiple bioactive functions including anti-inflammation. Pretreatment with SMN demonstrated chondroprotection against tumour necrosis factor-alpha (TNF-α) stimulation in a chondrocyte cell line. However, pre- and posttreatment with phytochemicals have varying effects on osteoarthritis (OA) chondrocytes, and the therapeutic potential of SMN after catabolic cytokine stimulation is not fully elucidated.

Methods

The cytotoxicity of SMN (12.5, 25, 50 and 100 μM) was evaluated in human primary chondrocytes. The chondrocytes were supplemented with SMN (25 and 50 μM) after interleukin-1beta (IL-1β) stimulation. The mRNA expression and protein production of catabolic/anabolic cytokines as well as extracellular matrix (ECM) components were evaluated.

Results

High-dose SMN (100 μM) impaired the mitochondrial activity in chondrocytes, and 50 μM SMN further caused cell death in IL-1β-stimulated cells. The addition of 25 μM SMN ameliorated cell senescence; downregulated the catabolic genes of inducible nitric oxide synthase, IL-1β, TNF-α, matrix metalloproteinase-3 (MMP-3), MMP-9 and MMP-13; upregulated the anabolic genes of tissue inhibitor of metalloproteinase-1 (TIMP-1) and collagen type II alpha 1; and restored the expression of chondrogenic phenotype genes SOX9 and sirtuin-1 (Sirt1). In addition, the production of IL-1β, MMP-3 and MMP-9 decreased with an increase in TIMP-1 secretion. However, the mRNA levels of IL-6, IL-8 and IL-10 and protein production remained high. The addition of nicotinamide, a Sirt1 inhibitor, downregulated SOX9 and attenuated the therapeutic effects of SMN on IL-1β-stimulated chondrocytes.

Conclusion

SMN regulates the chondrocyte phenotype through Sirt1 and SOX9 to improve ECM homeostasis and may serve as a complementary therapy for early-stage knee OA.

Evaluation of the post-treatment anti-inflammatory capacity of osteoarthritic chondrocytes: An in vitro study using baicalein

INTRODUCTION

Targeting inflammatory cascades is considered a promising way to prevent knee osteoarthritis (OA) progression. In terms of down-regulating the expression of inducible nitric oxide synthase (iNOS), interleukin (IL)-6, and matrix metalloproteinases (MMPs), pre-treatment with the flavonoid baicalein reportedly protects articular chondrocytes against the cytotoxicity of IL-1β. However, the benefits of post-treatment baicalein on osteoarthritic chondrocytes are not fully elucidated.

METHODS

In this study, primary human chondrocytes were stimulated with IL-1β prior to baicalein application to evaluate the therapeutic effect of post-treatment.

RESULTS

Post-treatment baicalein alleviated cell death and partially restored mitochondrial viability, while the senescence-associated secretory phenotype was not improved in IL-1β-stimulated chondrocytes. Post-treatment baicalein down-regulated the expressions of IL-1β, tumor necrosis factor-alpha, MMP-3, MMP-9, and MMP-13 mRNA as well as the protein production in stimulated cells. Even so, the levels of these factors were relative higher than those in un-treated chondrocytes. Moreover, iNOS, IL-6, IL-8, and COL1A1 expressions were consistently high, and IL-10 protein synthesis steadily increased in IL-1β-treated chondrocytes under baicalein treated status. Moreover, Western blot analyses showed that post-treatment baicalein suppressed nuclear factor kappa-light-chain-enhancer of activated B cells and p50 production while downstream cyclooxygenase-2 was still highly expressed.

CONCLUSION

Baicalein post-treatment to osteoarthritic chondrocytes had a minor benefit to the homeostasis of cartilaginous extracellular matrix.

Chitosan-cartilage extracellular matrix hybrid scaffold induces chondrogenic differentiation to adipose-derived stem cells

Introduction

Adipose-derived stem cells (ASCs) are potential cell sources for cartilage tissue engineering. Chitosan has been shown to enhance the stemness and differentiation capability of ASCs, and the native extracellular matrix (ECM) derived from articular cartilage has been also reported to induce chondrogenic differentiation of ASCs. Here we tested the hypothesis that a porous three-dimensional (3D) hybrid scaffold composed of chitosan and cartilage ECM can provide a better environment to induce ASC chondrogenesis.

Methods

Mixed solution composed of chitosan and cartilage ECM was frozen and lyophilized to form a composite construct. The porous 3D scaffolds were further crosslinked by genipin and used for ASC culture.

Results

Cultivation of ASCs in the chitosan/cartilage ECM composite 3D scaffolds induced the formation of cell spheroids with profound glycosaminoglycan production after 14 and 28 days culture. Chondrogenesis of ASCs seeded in the 3D scaffolds was also evident by mRNA expressions of cartilage-specific gene COL2A1 and ACAN on day 14. Histology and immunohistochemistry on day 28 also showed abundant cartilage-specific macromolecules, namely collagen type II and proteoglycan, deposited in a surface layer of the composite scaffold with tangential layer, transitional layer, and lacunae-like structures. Otherwise, hypertrophic markers collagen type I and X were concentrated in the area beneath the surface.

Conclusion

Our findings demonstrated spatial chondrogenic differentiation of ASCs in the chitosan-cartilage ECM composite scaffolds. This 3D hybrid scaffold exhibits great potentials for ASC-based cartilage tissue engineering.

•

Cultivation of ASCs in the chitosan and cartilage ECM hybrid scaffold induced chondrogenesis.

•

ASCs in composite scaffold expressed cartilage-specific genes COL2A1 and ACAN.

•

Histologic inspections showed abundant cartilage-specific collagen type II and proteoglycan productions.

•

Chitosan-cartilage ECM hybrid scaffold exhibits great potentials for ASC-based cartilage tissue engineering.

Band-dependent superconducting gap in SrFe2(As0.65P0.35)2 studied by angle-resolved photoemission spectroscopy

The isovalent-substituted iron pnictide compound SrFe₂(As_1−xP_x)₂ exhibits multiple evidence for nodal superconductivity via various experimental probes, such as the penetration depth, nuclear magnetic resonance and specific heat measurements. The direct identification of the nodal superconducting (SC) gap structure is challenging, partly because the presence of nodes is not protected by symmetry but instead caused by an accidental sign change of the order parameter, and also because of the three-dimensionality of the electronic structure. We have studied the SC gaps of SrFe₂(As_0.65P_0.35)₂ in three-dimensional momentum space by synchrotron and laser-based angle-resolved photoemission spectroscopy. The three hole Fermi surfaces (FSs) at the zone center have SC gaps with different magnitudes, whereas the SC gaps of the electron FSs at the zone corner are almost isotropic and k_z-independent. As a possible nodal SC gap structure, we propose that the SC gap of the outer hole FS changes sign around the Z-X [(0, 0, 2π) − (π, π, 2π)] direction.

The chondroprotective effect of diosmin on human articular chondrocytes under oxidative stress

Excessive oxidative stress, which can amplify inflammatory responses, is involved in the pathologic progression of knee osteoarthritis. Diosmin is known to possess a variety of biological functions such as antiinflammatory and antioxidant activities. We therefore demonstrated the chondroprotective potentials of diosmin on human articular chondrocytes under oxidative stress. The cytotoxicity of diosmin (5, 10, 50, and 100 μM) to chondrocytes was first evaluated. Subsequently, the cells were treated with diosmin (5 and 10 μM) after hydrogen peroxide (H₂ O₂ ) exposure. We found that the cytotoxicity of diosmin occurred in a dose-dependent manner (10, 50, and 100 μM), and low-dose diosmin (5 μM) slightly impaired cell viability. Diosmin supplementations (5 and 10 μM) did not show beneficial effects on mitochondrial activity, cytotoxicity, proliferation, and survival and the cell senescence was ameliorated in H₂ O₂ -exposed chondrocytes. On the other hand, diosmin down-regulated the mRNA levels of iNOS, COX-2, IL-1β, COL1A1, MMP-3, and MMP-9; up-regulated TIMP-1 and SOX9; and improved COL2A1 in chondrocytes under oxidative stresses. Furthermore, diosmin also regulated glutathione reductase and glutathione peroxidase of H₂ O₂ -exposed chondrocytes. In conclusion, diosmin displayed a remarkable antiinflammatory effect compared with the antioxidant capacity on human chondrocytes. Diosmin can maintain the homeostasis of extracellular matrix of articular cartilage.

Spectral Evidence for Emergent Order in Ba_{1-x}Na_{x}Fe_{2}As_{2}

We report an angle-resolved photoemission spectroscopy study of the iron-based superconductor family, Ba_{1-x}Na_{x}Fe_{2}As_{2}. This system harbors the recently discovered double-Q magnetic order appearing in a reentrant C_{4} phase deep within the underdoped regime of the phase diagram that is otherwise dominated by the coupled nematic phase and collinear antiferromagnetic order. From a detailed temperature-dependence study, we identify the electronic response to the nematic phase in an orbital-dependent band shift that strictly follows the rotational symmetry of the lattice and disappears when the system restores C_{4} symmetry in the low temperature phase. In addition, we report the observation of a distinct electronic reconstruction that cannot be explained by the known electronic orders in the system.

[Neuropathologic study of massive subcortical heterotopia]

Objective: To investigate the clinicpathologic features and probable mechanisms of massive subcortical heterotopia. Methods: Clinical data, histologic features and neuropathologic data were analyzed in five cases of massive subcortical heterotopia collected from Xuanwu Hospital, Capital Medical University from January 2014 to October 2017. Results: All five patients (three males and two females) had a history of refractory epilepsy with a mean period of 15.4 years (range 7 to 21 years). The median age at surgery was 28.6 years(range 20 to 39 years). Magnetic resonance imaging showed that the lesions were located in the temporal lobe (two cases), parietal lobe (one case), both temporal and occipital lobes (one case) and both temporal and parietal lobes (one case). Pathologic examination disclosed that massive gray matter in subcortical and deep white matter with various shape and size. Moreover, one case also showed subpial and periventricular heterotopias and polymicrogyria. Polymicrogyria or hippocampal sclerosis were seen in the remaining three cases. None of the five patients experienced seizure attacks during the follow-up period. Conclusions: Heterotopia is malformations due to abnormal neuronal migration. Massive subcortical heterotopia due to widespread abnormal neuronal migration is relatively rare. The mechanism of heterotopia together with polymicrogyria needs further discussion.

Impairment of social behaviors in Arhgef10 knockout mice

Background

Impaired social interaction is one of the essential features of autism spectrum disorder (ASD). Our previous copy number variation (CNV) study discovered a novel deleted region associated with ASD. One of the genes included in the deleted region is ARHGEF10. A missense mutation of ARHGEF10 has been reported to be one of the contributing factors in several diseases of the central nervous system. However, the relationship between the loss of ARHGEF10 and the clinical symptoms of ASD is unclear.

Methods

We generated Arhgef10 knockout mice as a model of ASD and characterized the social behavior and the biochemical changes in the brains of the knockout mice.

Results

Compared with their wild-type littermates, the Arhgef10-depleted mice showed social interaction impairment, hyperactivity, and decreased depression-like and anxiety-like behavior. Behavioral measures of learning in the Morris water maze were not affected by Arhgef10 deficiency. Moreover, neurotransmitters including serotonin, norepinephrine, and dopamine were significantly increased in different brain regions of the Arhgef10 knockout mice. In addition, monoamine oxidase A (MAO-A) decreased in several brain regions.

Conclusions

These results suggest that ARHGEF10 is a candidate risk gene for ASD and that the Arhgef10 knockout model could be a tool for studying the mechanisms of neurotransmission in ASD.

Trial registration

Animal studies were approved by the Institutional Animal Care and Use Committee of National Taiwan University (IACUC 20150023). Registered 1 August 2015.

Electronic supplementary material

The online version of this article (10.1186/s13229-018-0197-5) contains supplementary material, which is available to authorized users.

Antagonism of proteasome inhibitor-induced heme oxygenase-1 expression by PINK1 mutation

PTEN-induced putative kinase 1 (PINK1) is an integral protein in the mitochondrial membrane and maintains mitochondrial fidelity. Pathogenic mutations in PINK1 have been identified as a cause of early-onset autosomal recessive familial Parkinson’s disease (PD). The ubiquitin proteasome pathway is associated with neurodegenerative diseases. In this study, we investigated whether mutations of PINK1 affects the cellular stress response following proteasome inhibition. Administration of MG132, a peptide aldehyde proteasome inhibitor, significantly increased the expression of heme oxygenase-1 (HO-1) in rat dopaminergic neurons in the substantia nigra and in the SH-SY5Y neuronal cell line. The induction of HO-1 expression by proteasome inhibition was reduced in PINK1 G309D mutant cells. MG132 increased the levels of HO-1 through the Akt, p38, and Nrf2 signaling pathways. Compared with the cells expressing WT-PINK1, the phosphorylation of Akt and p38 was lower in those cells expressing the PINK1 G309D mutant, which resulted in the inhibition of the nuclear translocation of Nrf2. Furthermore, MG132-induced neuronal death was enhanced by the PINK1 G309D mutation. In this study, we demonstrated that the G309D mutation impairs the neuroprotective function of PINK1 following proteasome inhibition, which may be related to the pathogenesis of PD.

[Expression and bioinformatics analysis of long-chain non-coding RNA PVT1 in tumors]

Objective: To study the expression and mechanism of long-chain non-coding RNA PVT1 in tumor by bioinformatics analysis and experimental verification, and to provide new ideas for the study of the pathogenesis of tumors. Methods: The expression of PVT1 in 14 common tumors was downloaded from starBase v2.0 public database, which also was verified by PVT1 RNA-in situ hybridization.The upstream transcription factors, the downstream target microRNA(miRNA) for PVT1 and the target genes for the target miRNAs were predicted and analyzed by using bioinformatics based on the database of UCSC Genome Browser, HMDD v2.0, miRTar Base, JASPAR databases. Results: StarBase database analysis and RNA in situ hybridization showed that PVT1 was highly expressed in kidney clear cell carcinoma and colon and rectal adenocarcinoma. PVT1 was regulated by the upstream transcription factors CREB1, Atf1, SP1, KLF5, STAT3, while it could control the expression of the downstream target miR-16. bcl-2, VEGFA, CCNE1, CCND1 and SHOC2 showed an interaction with the transcription factor of PVT1, which formed a feedback regulatory pathway. Conclusions: PVT1 is highly expressed in kidney clear cell carcinoma and colon and rectal adenocarcinoma.The predictive analysis of bioinformatics demonstrates that transcription factor/PVT1/miR-16/target gene signal axon may be an important molecular mechanism, which provide a valuable clue for further functional mechanism research of long-chain non-coding RNA.

Distinct Electronic Structure for the Extreme Magnetoresistance in YSb

An extreme magnetoresistance (XMR) has recently been observed in several nonmagnetic semimetals. Increasing experimental and theoretical evidence indicates that the XMR can be driven by either topological protection or electron-hole compensation. Here, by investigating the electronic structure of a XMR material, YSb, we present spectroscopic evidence for a special case which lacks topological protection and perfect electron-hole compensation. Further investigations reveal that a cooperative action of a substantial difference between electron and hole mobility and a moderate carrier compensation might contribute to the XMR in YSb.

Superconducting Gap Anisotropy in Monolayer FeSe Thin Film

Superconductivity originates from pairing of electrons near the Fermi energy. The Fermi surface topology and pairing symmetry are thus two pivotal characteristics of a superconductor. Superconductivity in one monolayer (1 ML) FeSe thin film has attracted great interest recently due to its intriguing interfacial properties and possibly high superconducting transition temperature over 65 K. Here, we report high-resolution measurements of the Fermi surface and superconducting gaps in 1 ML FeSe using angle-resolved photoemission spectroscopy. Two ellipselike electron pockets are clearly resolved overlapping with each other at the Brillouin zone corner. The superconducting gap is nodeless but moderately anisotropic, which puts strong constraint on determining the pairing symmetry. The gap maxima locate on the d_{xy} bands along the major axis of the ellipse and four gap minima are observed at the intersections of electron pockets. The gap maximum location combined with the Fermi surface geometry deviate from a single d-wave, extended s-wave or s_{±} gap function, suggesting an important role of the multiorbital nature of Fermi surface and orbital-dependent pairing in 1 ML FeSe. The gap minima location may be explained by a sign change on the electron pockets, or a competition between intra- and interorbital pairing.

[Clinicopathologic study of intractable epilepsy-related encephalitis]

OBJECTIVE

To investigate the clinicopathologic features of intractable epilepsy related encephalitis.

METHODS

The clinical and pathologic findings of 15 cases of intractable epilepsy after functional neurosurgical treatment were reviewed and analyzed retrospectively.

RESULTS

All patients, including four male and 11 female, had medically intractable epilepsy. The mean age of onset for seizure was 5.3 years (1-15 years) and the disease duration was 4.7 years (0.5-15 years). A definite past history was identified in 11 patients, including viral encephalitis in nine patients, anoxia in utero and head trauma in one patient respectively. The extent and sites of involvement were different, including single cerebral hemisphere diffusely in five cases, multiple lobes in seven cases, and single lobe in three cases. Temporal lobe was involved in 13 cases, frontal lobe in eight, parietal lobe in eight, occipital lobe in seven, and insular lobe in four. Microscopically, all cases were characterized by perivascular inflammatory cells infiltration in the subarachnoid space. The focal cerebral cortex showed obvious atrophy with various degrees of the neuronal loss and glial proliferation, eventually leading to glial scar formation. In addition, microglia nodules, lymphatic cuff and neuronophagia were also observed. Seven cases of focal cortical dysplasia were identified among the 11 cases with adequate perilesional cerebral cortex. Hippocampus sclerosis was found in two cases. Intranuclear inclusions were seen in six cases, and these were immunopositive of cytomegalovirus-late antigen, and three cases also showed multinucleated giant cells and calcifications.

CONCLUSION

Encephalitis is one of the common causes of refractory epilepsy, and may result in refractory epilepsy as a sequel.

Bandwidth and Electron Correlation-Tuned Superconductivity in Rb_{0.8}Fe_{2}(Se_{1-z}S_{z})_{2}

We present a systematic angle-resolved photoemission spectroscopy study of the substitution dependence of the electronic structure of Rb_{0.8}Fe_{2}(Se_{1-z}S_{z})_{2} (z=0, 0.5, 1), where superconductivity is continuously suppressed into a metallic phase. Going from the nonsuperconducting Rb_{0.8}Fe_{2}S_{2} to superconducting Rb_{0.8}Fe_{2}Se_{2}, we observe little change of the Fermi surface topology, but a reduction of the overall bandwidth by a factor of 2. Hence, for these heavily electron-doped iron chalcogenides, we have identified electron correlation as explicitly manifested in the quasiparticle bandwidth to be the important tuning parameter for superconductivity, and that moderate correlation is essential to achieving high T_{C}.

Inhibition of hyperactivity and impulsivity by carbonic anhydrase inhibitors in spontaneously hypertensive rats, an animal model of ADHD

RATIONALE

Dysregulation of noradrenergic and dopaminergic systems is involved in the pathology of attention deficit hyperactivity disorder (ADHD). Carbonic anhydrase (CA) has been reported to affect monoamine transmission in the central nervous system.

OBJECTIVES

The aim of this study is to investigate the effect of CA inhibitors on the hyperactivity and impulsivity of the spontaneously hypertensive rat (SHR), which is currently the best-validated animal model of ADHD.

METHODS

SHRs and Wistar Kyoto rats at 6 to 8 weeks of age were pretreated with intraperitoneal injections of acetazolamide and methazolamide, both carbonic anhydrase inhibitors, before the behavior tests. The open-field locomotion test and the electro-foot shock aversive water drinking test were then applied to quantify their hyperactivity and impulsivity, respectively. The Morris water maze test, on the other hand, monitored their spatial learning.

RESULTS

Acetazolamide and methazolamide significantly inhibited the hyperactivity of SHRs but had no effects in Wistar Kyoto rats. Acetazolamide also inhibited the impulsivity of SHRs. Low doses of acetazolamide had the greater inhibitory effects on the hyperactivity and impulsivity, but did not impair the spatial learning of SHRs.

CONCLUSIONS

This is the first study to show that carbonic anhydrase inhibitors can strain-specifically antagonize the hyperactivity and impulsivity of SHRs. Under a low dose of acetazolamide, there was no cognition impairment in SHRs. Carbonic anhydrase inhibitors may be the novel drugs for treatment for patients with ADHD.

Observation of universal strong orbital-dependent correlation effects in iron chalcogenides

Establishing the appropriate theoretical framework for unconventional superconductivity in the iron-based materials requires correct understanding of both the electron correlation strength and the role of Fermi surfaces. This fundamental issue becomes especially relevant with the discovery of the iron chalcogenide superconductors. Here, we use angle-resolved photoemission spectroscopy to measure three representative iron chalcogenides, FeTe_0.56Se_0.44, monolayer FeSe grown on SrTiO₃ and K_0.76Fe_1.72Se₂. We show that these superconductors are all strongly correlated, with an orbital-selective strong renormalization in the d_xy bands despite having drastically different Fermi surface topologies. Furthermore, raising temperature brings all three compounds from a metallic state to a phase where the d_xy orbital loses all spectral weight while other orbitals remain itinerant. These observations establish that iron chalcogenides display universal orbital-selective strong correlations that are insensitive to the Fermi surface topology, and are close to an orbital-selective Mott phase, hence placing strong constraints for theoretical understanding of iron-based superconductors.

A proper theoretical description for unconventional superconductivity in iron-based compounds remains elusive. Here, the authors, to capture the electron correlation strength and the role of Fermi surfaces, report ARPES measurements of three iron chalcogenide superconductors to establish universal features.

Spectroscopic evidence for negative electronic compressibility in a quasi-three-dimensional spin-orbit correlated metal

Negative compressibility is a sign of thermodynamic instability of open or non-equilibrium systems. In quantum materials consisting of multiple mutually coupled subsystems, the compressibility of one subsystem can be negative if it is countered by positive compressibility of the others. Manifestations of this effect have so far been limited to low-dimensional dilute electron systems. Here, we present evidence from angle-resolved photoemission spectroscopy (ARPES) for negative electronic compressibility (NEC) in the quasi-three-dimensional (3D) spin-orbit correlated metal (Sr1-xLax)3Ir2O7. Increased electron filling accompanies an anomalous decrease of the chemical potential, as indicated by the overall movement of the deep valence bands. Such anomaly, suggestive of NEC, is shown to be primarily driven by the lowering in energy of the conduction band as the correlated bandgap reduces. Our finding points to a distinct pathway towards an uncharted territory of NEC featuring bulk correlated metals with unique potential for applications in low-power nanoelectronics and novel metamaterials.

Autism-associated gene Dlgap2 mutant mice demonstrate exacerbated aggressive behaviors and orbitofrontal cortex deficits

BACKGROUND

As elegant structures designed for neural communication, synapses are the building bricks of our mental functions. Recently, many studies have pointed out that synaptic protein-associated mutations may lead to dysfunctions of social cognition. Dlgap2, which encodes one of the main components of scaffold proteins in postsynaptic density (PSD), has been addressed as a candidate gene in autism spectrum disorders. To elucidate the disturbance of synaptic balance arising from Dlgap2 loss-of-function in vivo, we thus generated Dlgap2 (-/-) mice to investigate their phenotypes of synaptic function and social behaviors.

METHODS

The creation of Dlgap2 (-/-) mice was facilitated by the recombineering-based method, Cre-loxP system and serial backcross. Reversal learning in a water T-maze was used to determine repetitive behaviors. The three-chamber approach task, resident-intruder test and tube task were performed to characterize the social behaviors of mutant mice. Cortical synaptosomal fraction, Golgi-Cox staining, whole-cell patch electrophysiology and transmission electron microscopy were all applied to investigate the function and structure of synapses in the orbitofrontal cortex (OFC) of Dlgap2 (-/-) mice.

RESULTS

Dlgap2 (-/-) mice displayed exacerbated aggressive behaviors in the resident-intruder task, and elevated social dominance in the tube test. In addition, Dlgap2 (-/-) mice exhibited a clear reduction of receptors and scaffold proteins in cortical synapses. Dlgap2 (-/-) mice also demonstrated lower spine density, decreased peak amplitude of miniature excitatory postsynaptic current and ultra-structural deficits of PSD in the OFC.

CONCLUSIONS

Our findings clearly demonstrate that Dlgap2 plays a vital role in social behaviors and proper synaptic functions of the OFC. Moreover, these results may provide valuable insights into the neuropathology of autism.

Targeted delivery of erythropoietin by transcranial focused ultrasound for neuroprotection against ischemia/reperfusion-induced neuronal injury: a long-term and short-term study

Erythropoietin (EPO) is a neuroprotective agent against cerebral ischemia/reperfusion (I/R)-induced brain injury. However, its crossing of blood-brain barrier is limited. Focused ultrasound (FUS) sonication with microbubbles (MBs) can effectively open blood-brain barrier to boost the vascular permeability. In this study, we investigated the effects of MBs/FUS on extending the therapeutic time window of EPO and its neuroprotective effects in both acute and chronic phases. Male Wistar rats were firstly subjected to two common carotid arteries and right middle cerebral artery occlusion (three vessels occlusion, 3VO) for 50 min, and then the rats were treated with hEPO (human recombinant EPO, 5000 IU/kg) with or without MBs/FUS at 5 h after occlusion/reperfusion. Acute phase investigation (I/R, I/R+MBs/FUS, I/R+hEPO, and I/R+hEPO+MBs/FUS) was performed 24 h after I/R; chronic tests including cylinder test and gait analysis were performed one month after I/R. The experimental results showed that MBs/FUS significantly increased the cerebral content of EPO by bettering vascular permeability. In acute phase, both significant improvement of neurological score and reduction of infarct volume were found in the I/R+hEPO+MBs/FUS group, as compared with I/R and I/R+hEPO groups. In chronic phase, long-term behavioral recovery and neuronal loss in brain cortex after I/R injury was significantly improved in the I/R+hEPO+MBs/FUS group. This study indicates that hEPO administration with MBs/FUS sonication even at 5 h after occlusion/reperfusion can produce a significant neuroprotection.

Speed limit of the insulator-metal transition in magnetite

As the oldest known magnetic material, magnetite (Fe3O4) has fascinated mankind for millennia. As the first oxide in which a relationship between electrical conductivity and fluctuating/localized electronic order was shown, magnetite represents a model system for understanding correlated oxides in general. Nevertheless, the exact mechanism of the insulator-metal, or Verwey, transition has long remained inaccessible. Recently, three-Fe-site lattice distortions called trimerons were identified as the characteristic building blocks of the low-temperature insulating electronically ordered phase. Here we investigate the Verwey transition with pump-probe X-ray diffraction and optical reflectivity techniques, and show how trimerons become mobile across the insulator-metal transition. We find this to be a two-step process. After an initial 300 fs destruction of individual trimerons, phase separation occurs on a 1.5±0.2 ps timescale to yield residual insulating and metallic regions. This work establishes the speed limit for switching in future oxide electronics.

Dextromethorphan inhibits osteoclast differentiation by suppressing RANKL-induced nuclear factor-κB activation

Dextromethorphan (DXM), a commonly used antitussive, is a dextrorotatory morphinan. Here, we report that DXM inhibits the receptor activator of nuclear factor kappa B ligand (RANKL)-induced osteoclastogenesis and bone resorption by abrogating the activation of NF-κB signalling in vitro. Oral administration of DXM ameliorates ovariectomy (OVX)-induced osteoporosis in vivo.

INTRODUCTION

DXM was reported to possess anti-inflammatory properties through inhibition of the release of pro-inflammatory factors. However, the potential role and action mechanism of DXM on osteoclasts and osteoblasts remain unclear. In this study, in vitro and in vivo studies were performed to investigate the potential effects of DXM on osteoclastogenesis and OVX-induced bone loss.

METHODS

Osteoclastogenesis was examined by the TRAP staining, pit resorption, TNF-α release, and CCR2 and CALCR gene expression. Osteoblast differentiation was analyzed by calcium deposition. Osteogenic and adipogenic genes were measured by real-time PCR. Signaling pathways were explored using Western blot. ICR mice were used in an OVX-induced osteoporosis model. Tibiae were measured by µCT and serum markers were examined with ELISA kits.

RESULTS

DXM inhibited RANKL-induced osteoclastogenesis. DXM mainly inhibited osteoclastogenesis via abrogation of IKK-IκBα-NF-κB pathways. However, a higher dosage of DXM antagonized the differentiation of osteoblasts via the inhibition of osteogenic signals and increase of adipogenic signals. Oral administration of DXM (20 mg/kg/day) partially reduced trabecular bone loss in ovariectomized mice.

CONCLUSION

DXM inhibits osteoclast differentiation and activity by affecting NF-κB signaling. Therefore, DXM at suitable doses may have new therapeutic applications for the treatment of diseases associated with excessive osteoclastic activity.

Real-time manifestation of strongly coupled spin and charge order parameters in stripe-ordered La(1.75)Sr(0.25)NiO(4) nickelate crystals using time-resolved resonant x-ray diffraction

We investigate the order parameter dynamics of the stripe-ordered nickelate, La(1.75)Sr(0.25)NiO(4), using time-resolved resonant x-ray diffraction. In spite of distinct spin and charge energy scales, the two order parameters' amplitude dynamics are found to be linked together due to strong coupling. Additionally, the vector nature of the spin sector introduces a longer reorientation time scale which is absent in the charge sector. These findings demonstrate that the correlation linking the symmetry-broken states does not unbind during the nonequilibrium process, and the time scales are not necessarily associated with the characteristic energy scales of individual degrees of freedom.

Observation of temperature-induced crossover to an orbital-selective Mott phase in A(x)Fe(2-y)Se2 (A=K, Rb) superconductors

Using angle-resolved photoemission spectroscopy, we observe the low-temperature state of the A(x)Fe(2-y)Se(2) (A=K, Rb) superconductors to exhibit an orbital-dependent renormalization of the bands near the Fermi level-the d(xy) bands heavily renormalized compared to the d(xz)/d(yz) bands. Upon raising the temperature to above 150 K, the system evolves into a state in which the d(xy) bands have depleted spectral weight while the d(xz)/d(yz) bands remain metallic. Combined with theoretical calculations, our observations can be consistently understood as a temperature-induced crossover from a metallic state at low temperatures to an orbital-selective Mott phase at high temperatures. Moreover, the fact that the superconducting state of A(x)Fe(2-y)Se(2) is near the boundary of such an orbital-selective Mott phase constrains the system to have sufficiently strong on-site Coulomb interactions and Hund's coupling, highlighting the nontrivial role of electron correlation in this family of iron-based superconductors.

Measurement of coherent polarons in the strongly coupled antiferromagnetically ordered iron-chalcogenide Fe1.02Te using angle-resolved photoemission spectroscopy

The nature of metallicity and the level of electronic correlations in the antiferromagnetically ordered parent compounds are two important open issues for the iron-based superconductivity. We perform a temperature-dependent angle-resolved photoemission spectroscopy study of Fe(1.02)Te, the parent compound for iron chalcogenide superconductors. Deep in the antiferromagnetic state, the spectra exhibit a "peak-dip-hump" line shape associated with two clearly separate branches of dispersion, characteristics of polarons seen in manganites and lightly doped cuprates. As temperature increases towards the Néel temperature (T(N)), we observe a decreasing renormalization of the peak dispersion and a counterintuitive sharpening of the hump linewidth, suggestive of an intimate connection between the weakening electron-phonon (e-ph) coupling and antiferromagnetism. Our finding points to the highly correlated nature of the Fe(1.02)Te ground state featured by strong interactions among the charge, spin, and lattice and a good metallicity plausibly contributed by the coherent polaron motion.

Acetazolamide impairs fear memory consolidation in rodents

Acetazolamide (AZ) is an carbonic anhydrase inhibitor, which has been used in the treatment of seizures, mountain sickness and glaucoma. Memory impairment by AZ has been reported in patient interviews; however, the related mechanism is unclear. We applied two fear conditioning paradigms, shuttle avoidance and passive avoidance, in both rats and mice to investigate this clinical anecdote. Adult Wistar rats receiving AZ 1 h before the shuttle avoidance test showed decreased avoidance rates, especially at high dosage. Adult ICR mice receiving AZ both before and after acquisition trials showed the decreased step-through latencies during the passive avoidance test. This impairment of fear memory was corroborated with decreased LTP by AZ in the amygdala. AZ only inhibited fear conditioning-induced ERK phosphorylation and had no effect on Akt phosphorylation. In conclusion, our study confirmed the adverse cognitive effect of AZ in animal and electrophysiological studies. In clinical practice, clinicians should be aware of this side effect in patients taking AZ. In addition, this inhibition of fear memory by AZ could potentially be applied to patients with posttraumatic stress disorder.

Reaffirming the d(x2-y2) superconducting gap using the autocorrelation angle-resolved photoemission spectroscopy of Bi1.5Pb0.55Sr1.6La0.4CuO(6+δ)

Knowledge of the gap function is important to understand the pairing mechanism for high-temperature (T(c)) superconductivity. However, Fourier transform scanning tunneling spectroscopy (FT STS) and angle-resolved photoemission spectroscopy (ARPES) in the cuprates have reported contradictory gap functions, with FT-STS results deviating strongly from a canonical d(x2-y2) form. By applying an "octet model" analysis to autocorrelation ARPES, we reveal that a contradiction occurs because the octet model does not consider the effects of matrix elements and the pseudogap. This reaffirms the canonical d(x2-y2) superconducting gap around the node, which can be directly determined from ARPES. Further, our study suggests that the FT-STS reported fluctuating superconductivity around the node at far above T(c) is not necessary to explain the existence of the quasiparticle interference at low energy.

From a single-band metal to a high-temperature superconductor via two thermal phase transitions

The nature of the pseudogap phase of cuprate high-temperature superconductors is a major unsolved problem in condensed matter physics. We studied the commencement of the pseudogap state at temperature T* using three different techniques (angle-resolved photoemission spectroscopy, polar Kerr effect, and time-resolved reflectivity) on the same optimally doped Bi2201 crystals. We observed the coincident, abrupt onset at T* of a particle-hole asymmetric antinodal gap in the electronic spectrum, a Kerr rotation in the reflected light polarization, and a change in the ultrafast relaxational dynamics, consistent with a phase transition. Upon further cooling, spectroscopic signatures of superconductivity begin to grow close to the superconducting transition temperature (T(c)), entangled in an energy-momentum-dependent manner with the preexisting pseudogap features, ushering in a ground state with coexisting orders.

Single Dirac cone topological surface state and unusual thermoelectric property of compounds from a new topological insulator family

Angle resolved photoemission spectroscopy study on TlBiTe2 and TlBiSe2 from a thallium-based ternary chalcogenides family revealed a single surface Dirac cone at the center of the Brillouin zone for both compounds. For TlBiSe2, the large bulk gap (∼200 meV) makes it a topological insulator with better mechanical properties than the previous binary 3D topological insualtor family. For TlBiTe2, the observed negative bulk gap indicates it as a semimetal, instead of a narrow-gap semiconductor as conventionally believed; this semimetality naturally explains its mysteriously small thermoelectric figure of merit comparing to other compounds in the family. Finally, the unique band structures of TlBiTe2 also suggest it as a candidate for topological superconductors.

Enhanced superconducting gaps in the trilayer high-temperature Bi2Sr2Ca2Cu3O(10+δ) cuprate superconductor

We report the first observation of the multilayer band splitting in the optimally doped trilayer cuprate Bi2Sr2Ca2Cu3O(10+δ) (Bi2223) by angle-resolved photoemission spectroscopy. The observed energy bands and Fermi surfaces are originated from the outer and inner CuO2 planes (OP and IP). The OP band is overdoped with a large d-wave gap around the node of Δ0∼43  meV while the IP is underdoped with an even large gap of Δ0∼60  meV. These energy gaps are much larger than those for the same doping level of the double-layer cuprates, which leads to the large Tc in Bi2223. We propose possible origins of the large superconducting gaps for the OP and IP: (1) minimal influence of out-of-plane disorder and a proximity effect and (2) interlayer tunneling of Cooper pairs between the OP and IP.

Dependence of band-renormalization effects on the number of copper oxide layers in Tl-based copper oxide superconductors revealed by angle-resolved photoemission spectroscopy

Here we report the first angle-resolved photoemission measurement on nearly optimally doped multilayer Tl-based superconducting cuprates (Tl-2212 and Tl-1223) and a comparison study to single-layer (Tl-2201) compound. A "kink" in the band dispersion is found in all three compounds but exhibits different momentum dependence for the single-layer and multilayer compounds, reminiscent to that of Bi-based cuprates. This layer number dependent renormalization effect strongly implies that the spin-resonance mode is unlikely to be responsible for the dramatic renormalization effect near the antinodal region.

Experimental realization of a three-dimensional topological insulator, Bi2Te3

Three-dimensional topological insulators are a new state of quantum matter with a bulk gap and odd number of relativistic Dirac fermions on the surface. By investigating the surface state of Bi2Te3 with angle-resolved photoemission spectroscopy, we demonstrate that the surface state consists of a single nondegenerate Dirac cone. Furthermore, with appropriate hole doping, the Fermi level can be tuned to intersect only the surface states, indicating a full energy gap for the bulk states. Our results establish that Bi2Te3 is a simple model system for the three-dimensional topological insulator with a single Dirac cone on the surface. The large bulk gap of Bi2Te3 also points to promising potential for high-temperature spintronics applications.

A brief update of angle-resolved photoemission spectroscopy on a correlated electron system

In this paper, we briefly summarize the capabilities of state-of-the-art angle-resolved photoemission spectroscopy (ARPES) in the field of experimental condensed matter physics. Due to the advancement of the detector technology and the high flux light sources, ARPES has become a powerful tool to study the low energy excitations of solids, especially those novel quantum materials in which many-body physics are at play. To benchmark today's state-of-the-art ARPES technique, we demonstrate that the precision of today's ARPES has advanced to a regime comparable to the bulk-sensitive de Haas-van Alphen (dHvA) measurements. Finally, as an example of new discoveries driven by the advancement of the ARPES technique, we summarize some of our recent ARPES measurements on underdoped high-T(c) superconducting cuprates, which have provided further insight into the complex pseudogap problem.

Transient electronic structure and melting of a charge density wave in TbTe3

Obtaining insight into microscopic cooperative effects is a fascinating topic in condensed matter research because, through self-coordination and collectivity, they can lead to instabilities with macroscopic impacts like phase transitions. We used femtosecond time- and angle-resolved photoelectron spectroscopy (trARPES) to optically pump and probe TbTe3, an excellent model system with which to study these effects. We drove a transient charge density wave melting, excited collective vibrations in TbTe3, and observed them through their time-, frequency-, and momentum-dependent influence on the electronic structure. We were able to identify the role of the observed collective vibration in the transition and to document the transition in real time. The information that we demonstrate as being accessible with trARPES will greatly enhance the understanding of all materials exhibiting collective phenomena.