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1.
Phys Rev Lett ; 121(25): 256403, 2018 Dec 21.
Article in English | MEDLINE | ID: mdl-30608778

ABSTRACT

Emergent order at mesoscopic length scales in condensed matter can provide fundamental insight into the underlying competing interactions and their relationship with the order parameter. Using spectromicroscopy, we show that mesoscopic stripe order near the metal-insulator transition (MIT) of strained VO_{2} represents periodic modulations in both crystal symmetry and V-V dimerization. Above the MIT, we unexpectedly find the long-range order of V-V dimer strength and crystal symmetry become dissociated beyond ≈200 nm, whereas the conductivity transition proceeds homogeneously in a narrow temperature range.

2.
Transl Psychiatry ; 7(5): e1120, 2017 05 09.
Article in English | MEDLINE | ID: mdl-28485733

ABSTRACT

Maternal immune activation (MIA) during pregnancy has been linked to an increased risk of developing psychiatric pathologies in later life. This link may be bridged by a defective microglial phenotype in the offspring induced by MIA, as microglia have key roles in the development and maintenance of neuronal signaling in the central nervous system. The beneficial effects of the immunomodulatory treatment with minocycline on schizophrenic patients are consistent with this hypothesis. Using the MIA mouse model, we found an altered microglial transcriptome and phagocytic function in the adult offspring accompanied by behavioral abnormalities. The changes in microglial phagocytosis on a functional and transcriptional level were similar to those observed in a mouse model of Alzheimer's disease hinting to a related microglial phenotype in neurodegenerative and psychiatric disorders. Minocycline treatment of adult MIA offspring reverted completely the transcriptional, functional and behavioral deficits, highlighting the potential benefits of therapeutic targeting of microglia in psychiatric disorders.


Subject(s)
Adult Children/psychology , Anti-Bacterial Agents/pharmacology , Immune System Phenomena/drug effects , Microglia/drug effects , Minocycline/pharmacology , Synaptic Transmission/physiology , Transcriptome/genetics , Alzheimer Disease/drug therapy , Alzheimer Disease/genetics , Animals , Anti-Bacterial Agents/administration & dosage , Behavior, Animal/drug effects , Disease Models, Animal , Female , Humans , Immune System Phenomena/physiology , Mice , Mice, Inbred C57BL/immunology , Microglia/metabolism , Minocycline/administration & dosage , Phagocytosis/immunology , Pregnancy , Schizophrenia/drug therapy , Schizophrenia/genetics
3.
Opt Express ; 23(10): 13222-9, 2015 May 18.
Article in English | MEDLINE | ID: mdl-26074574

ABSTRACT

Correlated experimental and simulation studies on the modulation of Surface Plasmon Polaritons (SPP) in Au/VO2 bilayers are presented. The modification of the SPP wave vector by the thermally-induced insulator-to-metal phase transition (IMT) in VO2 was investigated by measuring the optical reflectivity of the sample. Reflectivity changes are observed for VO2 when transitioning between the insulating and metallic states, enabling modulation of the SPP in the Au layer by the thermally induced IMT in the VO2 layer. Since the IMT can also be optically induced using ultrafast laser pulses, we postulate the viability of SPP ultrafast modulation for sensing or control.

4.
Brain Behav Immun ; 48: 205-21, 2015 Aug.
Article in English | MEDLINE | ID: mdl-25843371

ABSTRACT

Microglia, the innate immune cells of the central nervous system (CNS), react to endotoxins like bacterial lipopolysaccharides (LPS) with a pronounced inflammatory response. To avoid excess damage to the CNS, the microglia inflammatory response needs to be tightly regulated. Here we report that a single LPS challenge results in a prolonged blunted pro-inflammatory response to a subsequent LPS stimulation, both in primary microglia cultures (100 ng/ml) and in vivo after intraperitoneal (0.25 and 1mg/kg) or intracerebroventricular (5 µg) LPS administration. Chromatin immunoprecipitation (ChIP) experiments with primary microglia and microglia acutely isolated from mice showed that LPS preconditioning was accompanied by a reduction in active histone modifications AcH3 and H3K4me3 in the promoters of the IL-1ß and TNF-α genes. Furthermore, LPS preconditioning resulted in an increase in the amount of repressive histone modification H3K9me2 in the IL-1ß promoter. ChIP and knock-down experiments showed that NF-κB subunit RelB was bound to the IL-1ß promoter in preconditioned microglia and that RelB is required for the attenuated LPS response. In addition to a suppressed pro-inflammatory response, preconditioned primary microglia displayed enhanced phagocytic activity, increased outward potassium currents and nitric oxide production in response to a second LPS challenge. In vivo, a single i.p. LPS injection resulted in reduced performance in a spatial learning task 4 weeks later, indicating that a single inflammatory episode affected memory formation in these mice. Summarizing, we show that LPS-preconditioned microglia acquire an epigenetically regulated, immune-suppressed phenotype, possibly to prevent excessive damage to the central nervous system in case of recurrent (peripheral) inflammation.


Subject(s)
Epigenesis, Genetic , Gene Silencing , Lipopolysaccharides/pharmacology , Microglia/metabolism , Transcription Factor RelB/metabolism , Animals , Histones/metabolism , Interleukin-1beta/genetics , Interleukin-1beta/metabolism , Mice , Microglia/drug effects , NF-kappa B/genetics , NF-kappa B/metabolism , Promoter Regions, Genetic , Tumor Necrosis Factor-alpha/genetics , Tumor Necrosis Factor-alpha/metabolism
5.
Phys Rev Lett ; 113(21): 216402, 2014 Nov 21.
Article in English | MEDLINE | ID: mdl-25479508

ABSTRACT

We report the simultaneous measurement of the structural and electronic components of the metal-insulator transition (MIT) of VO2 using electron and photoelectron spectroscopies and microscopies. We show that these evolve over different temperature scales, and are separated by an unusual monocliniclike metallic phase. Our results provide conclusive evidence that the new monocliniclike metallic phase, recently identified in high-pressure and nonequilibrium measurements, is accessible in the thermodynamic transition at ambient pressure, and we discuss the implications of these observations on the nature of the MIT in VO2.

6.
Phys Rev Lett ; 111(9): 096602, 2013 Aug 30.
Article in English | MEDLINE | ID: mdl-24033058

ABSTRACT

We resolved the enigma of anisotropic electronic transport in strained vanadium dioxide (VO2) films by inquiring into the role that strain plays in the nanoscale phase separation in the vicinity of the insulator-to-metal transition. The root source of the anisotropy was visualized as the formation of a peculiar unidirectional stripe state which accompanies the phase transition. Furthermore, nanoscale infrared spectroscopy unveils distinct facets of electron-lattice interplay at three different stages of the phase transition. These stages include the initial formation of sparse nonpercolating metallic domains without noticeable involvement of the lattice followed by an electron-lattice coupled anisotropic stripe state close to percolation which ultimately evolves into a nearly isotropic rutile metallic phase. Our results provide a unique mesoscopic perspective for the tunable macroscopic phenomena in strained metal oxide films.

7.
Phys Rev Lett ; 111(4): 047402, 2013 Jul 26.
Article in English | MEDLINE | ID: mdl-23931404

ABSTRACT

The evolution of electron correlation in SrxCa1-xVO3 has been studied using a combination of bulk-sensitive resonant soft x-ray emission spectroscopy, surface-sensitive photoemission spectroscopy, and ab initio band structure calculations. We show that the effect of electron correlation is enhanced at the surface. Strong incoherent Hubbard subbands are found to lie ∼20% closer in energy to the coherent quasiparticle features in surface-sensitive photoemission spectroscopy measurements compared with those from bulk-sensitive resonant soft x-ray emission spectroscopy, and a ∼10% narrowing of the overall bandwidth at the surface is also observed.

8.
Opt Lett ; 37(20): 4335-7, 2012 Oct 15.
Article in English | MEDLINE | ID: mdl-23073454

ABSTRACT

We report on the first observation of optically excited surface plasmon polaritons (SPPs) in the conducting phase of vanadium dioxide (VO(2)) thin films. VO(2) is low-loss optical material that undergoes an insulator-metal transition (IMT) under suitable thermal, optical, or electrical stimulation, thus enabling tunable SPP excitation of the conducting phase. Here we applied IR light (1520 nm) to excite SPPs while thermally inducing the IMT by changing the VO(2) temperature, and observed a clear trend from nonabsorption in the insulator phase to high absorption in the conducting phase due to SPP excitation in the latter phase. Tunable SPPs in VO(2) enable a range of opportunities for low-loss optoplasmonic applications since the rate of the IMT excitation can also be tailored.

9.
Eur J Microbiol Immunol (Bp) ; 2(3): 239-48, 2012 Sep.
Article in English | MEDLINE | ID: mdl-24688771

ABSTRACT

Viral infections during pregnancy significantly increase the risk for psychological pathologies like schizophrenia in the offspring. One of the main morphological hallmarks of schizophrenia is a reduced size of the hippocampus. Since new neurons are produced in this particular brain compartment throughout life, it might be possible that low neurogenesis levels triggered by a maternal viral infection contribute to developmental deficits of the hippocampus. We injected polyinosinic:polycytidylic acid (Poly I:C) in pregnant C57Bl/6 mice to stimulate an anti-viral response through TLR3 and examined gene expressions in the neuronal progenitor cells (NPCs) of the offspring at different ages. Additionally, we treated adult NPC lines with Poly I:C to investigate its direct effect. We could show for the first time that TLR3 and its downstream effector molecule IRF3 are expressed in adult NPCs. Poly I:C treatment in vitro and in vivo led to the regulation of proliferation and genes involved in antiviral response, migration, and survival. These findings indicate that NPCs of the fetus are able to react towards an in utero immune response, and thus, changes in the neuronal stem cell pool can contribute to the development of neurological diseases like schizophrenia.

10.
Nervenarzt ; 80(10): 1176, 1178-80, 1182-9, 2009 Oct.
Article in German | MEDLINE | ID: mdl-19547946

ABSTRACT

BACKGROUND: Cognitive deficits occurring with dementia are frequently not reported by the affected subject. Therefore, informant reports from close relatives are especially important for the early diagnosis of dementia. Internationally, the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) has been evaluated with positive results and is a widely used informant-rated instrument for the diagnosis of cognitive decline. For the German speaking countries, norms and evaluation of the psychometric properties of the instrument are lacking. METHODS: Norms for the German long version of the IQCODE were established with 46 healthy elderly married couples. These were compared with respect to their concurrent and discriminative validity with groups of patients suffering from mild cognitive impairment (MCI, n=25), Alzheimer's or mixed dementia (AD, n=59) and frontotemporal lobe degeneration (FTLD, n=15). RESULTS: The German version of the IQCODE exhibited good psychometric properties and was able to best discriminate between cognitively intact and demented subjects with AD. Receiver-operating characteristic analyses indicated a cut-off score of 3.38 which corresponds well with the value given in international literature. Patients with MCI and with FTLD were also reliably distinguished from cognitively intact subjects. However, the instrument did not distinguish AD from FTLD with any significant degree of confidence. DISCUSSION: The German version of the IQCODE reliably discriminates cognitively intact persons from those suffering from MCI or cortical dementia, but not between different types of cortical dementia, such as AD and FTLD. The IQCODE is an efficient informant-rated screening instrument for the early diagnosis of cognitive decline and dementia.


Subject(s)
Cognition Disorders/diagnosis , Dementia/diagnosis , Neuropsychological Tests , Psychometrics/methods , Surveys and Questionnaires , Adult , Aged , Aged, 80 and over , Cognition Disorders/etiology , Dementia/complications , Female , Germany , Humans , Male , Middle Aged , Reproducibility of Results , Sensitivity and Specificity
11.
Fortschr Neurol Psychiatr ; 77(7): 376-88, 2009 Jul.
Article in German | MEDLINE | ID: mdl-19533573

ABSTRACT

Neuropsychological differential diagnosis of degenerative dementias is characterized by high sensitivity and specificity which allows syndrome assignment in most instances in early stages. According to the empirical evidence, Alzheimer's disease can be discriminated from frontotemporal lobar degeneration and from vascular dementia by quality and severity of memory deficits and also by the presence of visuo-perceptive and visuo-constructive deficits. In frontotemporal lobar degeneration and vascular dementia executive dysfunctions predominate in most controlled empirical studies. Moreover, in frontotemporal lobar degeneration severe aphasic and semantic impairments can be observed. Neuropsychological assessment contributes to the early detection, differential diagnosis and evidence-based treatment of dementia syndromes to a considerable extent. Once more specific treatments are available, the early differential diagnosis of degenerative dementias will become highly important.


Subject(s)
Dementia/diagnosis , Neurodegenerative Diseases/diagnosis , Aged , Alzheimer Disease/diagnosis , Alzheimer Disease/psychology , Dementia/psychology , Dementia, Vascular/diagnosis , Dementia, Vascular/psychology , Diagnosis, Differential , Humans , Lewy Body Disease/diagnosis , Lewy Body Disease/psychology , Neurodegenerative Diseases/psychology
12.
J Neuroendocrinol ; 20 Suppl 1: 15-9, 2008 May.
Article in English | MEDLINE | ID: mdl-18426494

ABSTRACT

Whereas, in most brain compartments, neuronal cell renewal during early life is replaced by synaptic plasticity and the potentiation of existing pathways and connections, neurogenesis in the hippocampus occurs throughout adulthood. Neuronal progenitor cells in the dentate gyrus of the hippocampus are thought to be the gatekeepers of memory. Neural progenitor cell proliferation and differentiation depends on their intrinsic properties and local environment and is down-regulated in conditions associated with brain inflammation. Conversely, newly-formed neurones can survive despite chronic inflammation and, moreover, specifically arise within an inflammatory environment. Since the endocannabinoid system controls immune responses via multiple cellular and molecular targets and influences cell proliferation, fate decision and cell survival in the central nervous system, we summarise how neurogenesis might be regulated by brain cannabinoids, either directly or indirectly via the immune system. This review presents clear evidence that the cannabinoid system influences adult neurogenesis. However, there is considerable variability with regard to the strain, model and methods utilised and therefore it is difficult to compare studies investigating the cannabinoid system. As a result, it remains far from clear exactly how endocannabinoids regulate neurogenesis.


Subject(s)
Brain/drug effects , Brain/immunology , Cannabinoid Receptor Modulators/pharmacology , Endocannabinoids , Immune System/drug effects , Neurons/drug effects , Animals , Cannabinoid Receptor Modulators/metabolism , Cannabinoid Receptor Modulators/physiology , Cell Differentiation/drug effects , Encephalitis/etiology , Encephalitis/physiopathology , Humans , Neuroimmunomodulation/drug effects , Neuroimmunomodulation/physiology , Neurons/physiology
13.
Nervenarzt ; 79(4): 444-53, 2008 Apr.
Article in German | MEDLINE | ID: mdl-18040655

ABSTRACT

BACKGROUND: Incipient Alzheimer's disease (AD) is frequently suspected by neurologists and psychiatrists, but diagnosis is difficult to establish. The aim of this report was to analyse to what extent suspicion is confirmed by a comprehensive neuropsychological examination intended to distinguish different types of dementia. METHODS: Descriptive data analysis was used for investigating the differential diagnoses of 47 outpatients with suspected AD referred to a department of neuropsychology by physicians in private practice. Data analysis was based upon the NINCDS-ADRDA diagnostic criteria of AD. RESULTS: Only 38% of the outpatients examined with suspected AD met the NINCDS-ADRDA diagnostic criteria for AD or mixed dementia from a neuropsychological point of view, whereas 22% met criteria for other types of dementia. The remaining patients met criteria for distinct differential diagnoses (23%) or lacked pathological findings in neuropsychological functions (17%). CONCLUSIONS: Neuropsychology is an essential part in the differential diagnosis of mild to moderate dementias. It can aid in differential therapeutic considerations concerning the treatment of dementia, for example in selecting appropriate treatments or avoiding expensive but inappropriate ones.


Subject(s)
Alzheimer Disease/diagnosis , Neuropsychological Tests , Aged , Aged, 80 and over , Alzheimer Disease/drug therapy , Alzheimer Disease/psychology , Ambulatory Care , Cholinesterase Inhibitors/therapeutic use , Dementia/diagnosis , Dementia/psychology , Dementia, Vascular/diagnosis , Dementia, Vascular/psychology , Diagnosis, Differential , Female , Germany , Humans , Male , Mass Screening , Middle Aged , Patient Care Team , Referral and Consultation , Treatment Outcome
14.
Acta Neurochir (Wien) ; 149(8): 831-2; discussion 832-3, 2007 Aug.
Article in English | MEDLINE | ID: mdl-17558458

ABSTRACT

Peduncular hallucinosis is characterized by striking visual images, highly colored and mobile, which are recognized by the patient as imaginary. A 50-year-old-man underwent microvascular decompression for a classical right sided trigeminal neuralgia. During the procedure, the petrosal vein and a transverse pontine vein were sacrificed for trigeminal decompression. On the second postoperative day, the patient developed peduncular hallucinosis that disappeared on the forth postoperative day. This is the third case in the literature of peduncular hallucinosis after obliteration of veins of the petrosal venous complex for trigeminal neuralgia. The best policy in cerebellopontine angle surgery is to preserve the petrosal vein whenever possible to avoid complications related to venous congestion.


Subject(s)
Cerebral Veins/surgery , Decompression, Surgical , Hallucinations/physiopathology , Microsurgery , Postoperative Complications/physiopathology , Tegmentum Mesencephali/physiopathology , Trigeminal Neuralgia/surgery , Cerebellopontine Angle/blood supply , Electrocoagulation , Hallucinations/diagnosis , Humans , Magnetic Resonance Imaging , Male , Middle Aged , Nerve Compression Syndromes/diagnosis , Nerve Compression Syndromes/surgery , Pons/blood supply , Postoperative Complications/diagnosis , Trigeminal Neuralgia/diagnosis
15.
Glia ; 36(3): 414-20, 2001 Dec.
Article in English | MEDLINE | ID: mdl-11746777

ABSTRACT

Autoreactive T-cells are involved in demyelination, neurodegeneration, and the recruitment of peripheral macrophages and nonspecific activated T-cells in autoimmune diseases such as multiple sclerosis (MS). The ligation of costimulatory B7 molecules on microglia with CD28/CTLA-4 on T-cells is thought to be crucial to the onset and course of MS and its rodent model experimental autoimmune encephalomyelitis (EAE). It is currently unclear as to how far the nature of infiltrating T-cells has an impact on the expression of the B7 molecules on microglia, the resident antigen-presenting cells (APCs) of the brain. We studied the expression of B7-1 and B7-2 on microglia after encounter with preactivated Th1 and Th2 cells from transgenic mice whose T-cells express a receptor (TCR) either specific to myelin basic protein (MBP) or ovalbumin (OVA) using murine organotypic entorhinal-hippocampal slice cultures (OEHSC). Our main finding was that Th1 cells downregulate the constitutive expression of B7-2 and induce B7-1 expression while Th2 cells do not induce this B7-1 upregulation. The main difference between MBP- and OVA-specific cells was seen in experiments were Th1 cells had direct contact to APCs but not to brain tissue. In contrast to MBP-specific Th1 cells, OVA-specific Th1 cells required the addition of antigen to upregulate B7-1 and downregulate B7-2. When the cells were allowed to have contact to brain tissue, no difference was seen in the pattern of B7 regulation between OVA- and MBP-specific T-cells. Our data suggest that T-cells are able to modulate B7 expression on microglial cells in the brain independent of antigen presentation through TCR/MHC-II ligation but presumably by soluble mediators.


Subject(s)
Antigens, CD/immunology , B7-1 Antigen/immunology , Brain/immunology , Membrane Glycoproteins/immunology , Microglia/immunology , Multiple Sclerosis/immunology , Th1 Cells/immunology , Th2 Cells/immunology , Animals , Antigen Presentation/immunology , Antigens/immunology , Antigens/pharmacology , Antigens, CD/metabolism , B7-1 Antigen/metabolism , B7-2 Antigen , Brain/cytology , Coculture Techniques , Down-Regulation/immunology , Epitopes/immunology , Gene Expression Regulation/immunology , Membrane Glycoproteins/metabolism , Mice , Mice, Inbred BALB C , Microglia/cytology , Models, Biological , Multiple Sclerosis/pathology , Multiple Sclerosis/physiopathology , Myelin Basic Protein/immunology , Ovalbumin/immunology , Th1 Cells/cytology , Th2 Cells/cytology , Up-Regulation/immunology
16.
Science ; 294(5546): 1488-95, 2001 Nov 16.
Article in English | MEDLINE | ID: mdl-11711666

ABSTRACT

This review describes a new paradigm of electronics based on the spin degree of freedom of the electron. Either adding the spin degree of freedom to conventional charge-based electronic devices or using the spin alone has the potential advantages of nonvolatility, increased data processing speed, decreased electric power consumption, and increased integration densities compared with conventional semiconductor devices. To successfully incorporate spins into existing semiconductor technology, one has to resolve technical issues such as efficient injection, transport, control and manipulation, and detection of spin polarization as well as spin-polarized currents. Recent advances in new materials engineering hold the promise of realizing spintronic devices in the near future. We review the current state of the spin-based devices, efforts in new materials fabrication, issues in spin transport, and optical spin manipulation.

17.
J Neuroimmunol ; 119(1): 73-80, 2001 Sep 03.
Article in English | MEDLINE | ID: mdl-11525802

ABSTRACT

In experimental autoimmune encephalomyelitis (EAE), Th1 cells are responsible for disease induction while Th2 cells can be protective. To address the mechanisms of this differential behavior, we utilized organotypic murine entorhinal-hippocampal slice cultures to analyze interactions between myelin basic protein-specific Th1 and Th2 cells with microglial cells. While both Th1 and Th2 cells induced CD40 expression, only Th1 cells induced intercellular adhesion molecule-1 (ICAM-1) expression on microglia. Moreover, Th2 cells prevented or even reversed Th1-induced ICAM-1 upregulation. Evidently, Th2 cells could diminish Th1-induced inflammatory reactions and actively support the resting state of microglia, which could be one mechanism of Th2-mediated remission of neuroinflammation during EAE.


Subject(s)
Encephalitis/prevention & control , Th2 Cells/physiology , Animals , Brain/cytology , CD40 Antigens/metabolism , Cell Communication , Cell Movement/physiology , Cytokines/biosynthesis , In Vitro Techniques , Intercellular Adhesion Molecule-1/metabolism , Mice , Mice, Inbred Strains , Microglia/metabolism , Microglia/physiology , Th1 Cells/physiology
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