Observation of Weakened V-V Dimers in the Monoclinic Metallic Phase of Strained VO_{2}.

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.

Surface plasmon resonance modulation in nanopatterned Au gratings by the insulator-metal transition in vanadium dioxide films.

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.

Long-lasting pro-inflammatory suppression of microglia by LPS-preconditioning is mediated by RelB-dependent epigenetic silencing.

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.

Direct observation of decoupled structural and electronic transitions and an ambient pressure monocliniclike metallic phase of VO2.

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.

Anisotropic electronic state via spontaneous phase separation in strained vanadium dioxide films.

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.

Resonant soft-X-ray emission as a bulk probe of correlated electron behavior in metallic SrxCa1-xVO3.

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.

Surface plasmon polaritons in VO2 thin films for tunable low-loss plasmonic applications.

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.

Spintronics: a spin-based electronics vision for the future.

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.

[Informant report of cognitive changes in the elderly. A first evaluation of the German version of the IQCODE]. / Fremdbeurteilung kognitiver Veränderungen im Alter. Erste Vergleichswerte für den deutschen IQCODE.

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.

[Neuropsychological differential diagnosis of degenerative dementias]. / Neuropsychologische Differenzialdiagnostik degenerativer Demenzen.

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.

Peduncular hallucinosis after sacrifice of veins of the petrosal venous complex for trigeminal neuralgia.

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.

Maternal immune activation results in complex microglial transcriptome signature in the adult offspring that is reversed by minocycline treatment.

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.

Regulation of insulin receptors in the human ovary: in vitro studies.

The association between insulin resistance and ovarian hyperstimulation has led to a hypothesis that insulin stimulates ovarian steroidogenesis. This possible effect of insulin on the ovary could be mediated by either the insulin receptor or the type I insulin-like growth factor (IGF) receptor, both of which have been described in the human ovary. We examined the in vitro regulation of insulin receptors by LH, FSH, multiplication-stimulating activity (MSA), and insulin in ovarian stromal fragments from 24 women. [125I]Insulin binding was measured in the presence and absence of increasing concentrations of insulin, IGF-I, LH, and FSH. Neither LH nor FSH competed with [125I]insulin for binding sites, but preincubation with LH or FSH reduced [125I]insulin binding by 19-38%. Preincubation with MSA reduced [125I]insulin binding by 34-48%. The affinity of the insulin receptors, determined by Scatchard analysis, did not change (Ka = 3.3 X 10(8) mol-1). A concentration of 10 ng/mL insulin in the preincubation medium reduced [125I]insulin binding by 40%, whereas an insulin concentration of 50 or 500 ng/mL completely obliterated specific [125I]insulin binding. [125I]Insulin binding fully recovered, however, 4 h after termination of tissue exposure to insulin. The specificity of [125I] insulin binding was confirmed by studies with IGF-I. We conclude that of the hormones examined, insulin is the most potent regulator of human ovarian insulin receptors in vitro. Down-regulation of insulin receptors by insulin was reversed within 4 h after withdrawal of insulin. MSA, FSH, and LH also down-regulated the number of human ovarian insulin receptors in vitro, but were less potent. These phenomena, if also present in vivo, could be important factors in the regulation of ovarian function by insulin in normal and pathological states.

Th2 cells support intrinsic anti-inflammatory properties of the brain.

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.

Endocrine disorders of the pancreas and adrenal cortex in pediatric patients.

Hyperinsulinemia, a common cause of persistent hypoglycemia in infants and children, can result in permanent damage to the central nervous system. Thus, early diagnosis and treatment are important. The typical clinical manifestation of hyperinsulinemic hypoglycemia is symptomatic hypoglycemia that responds poorly to medical therapy. Affected infants may have tremors, jitteriness, apnea, cyanosis, or seizures. If initial medical therapy (frequent feedings, large amounts of intravenously administered glucose, diazoxide, and glucocorticoids) fails to stabilize plasma glucose levels, subtotal pancreatectomy is indicated. This surgical intervention does not completely correct the hypoglycemia in all patients, but it effectively reduces the severity of the condition. Surgical treatment of pediatric patients with Cushing's syndrome or aldosteronoma has also been effective. In our experience, survival of patients with adrenocortical adenomas has been 100%, whereas only five of nine children with adrenocortical carcinomas survived, and four of the five were younger than 10 years of age.

The continent ileostomy: a viable alternative.

The continent ileostomy is one of the alternative techniques in managing patients who require a proctocolectomy. Although previously plagued with up to 30% revisions, the continent ileostomy appears to contribute significantly to the social and psychologic well-being of these patients. Our experience suggests that improved surgical techniques make this procedure a safe and favorable alternative to the traditional Brooke ileostomy.

Duodenal osmoregulation after total parenteral nutrition in neonatal piglets.

The physiologic effects of intestinal rest on the efficiency of gastroduodenal osmoregulation of hypertonic and hypotonic carbohydrate meals were studied in neonatal piglets 3 to 5 days old. Sixteen piglets underwent laparotomy, gastrostomy, and end jejunostomy just distal to the ligament of Treitz. Sixteen littermates had insertion of a central venous catheter and received 2 weeks of total parenteral nutrition (TPN) before laparotomy, gastrostomy, and end jejunostomy. Experiments were performed 2 days after laparotomy in all groups. Each piglet received intragastric infusions of two test meals (25 ml/kg), half the pigs receiving glucose (494 +/- 11, 147 +/- 3 mOsm/L) and half mannitol (493 +/- 11, 150 +/- 4 mOsm/L) (SD). Gastric samples and jejunal effluent were collected every 30 minutes for 2 hours. TPN did not influence duodenal osmoregulation. Significant changes in osmolality occurred during duodenal transit after all meals, and these changes were similar for all groups. However, jejunal osmolality did not approach basal levels until late in the observation period. These results demonstrate significant but incomplete intraduodenal osmoregulation of carbohydrate meals in neonatal piglets that is unaffected by 2 weeks of intestinal rest.

Effect of proximal gastric vagotomy on gastric acid hypersecretion and hypergastrinemia after massive small bowel resection in dogs.

Fasting and postprandial gastric acid secretion and gastrin were determined in Heidenhain pouch dogs before (C) and after (R) massive enterectomy (five dogs) and after additional proximal gastric vagotomy (PGV) in three dogs. Basal acid output was unchanged (C = 7 +/- 2 microneq/hour; R = 11 +/- 4 microneq/hour), but postprandially the hourly (third through eighth hour) and cumulative acid outputs (C = 3.6 +/- 0.3 mEq/8 hour; R = 7.2 +/- 0.4 MEq/8 hour) were significantly increased by resection (P less than 0.001). Similarly, fasting gastrin was unaltered by resection (C = 41 +/- 2 pg/ml; R = 46 +/- 8 pg/ml), whereas hourly gastrin concentrations significantly (P less than 0.05) exceeded control values. Increased gastrin correlated linearly (P less than 0.02) with increased acid output. After PGV, basal acid levels remained unchanged (R = 4 +/- 2 micronEq/hour; PGV = 9 +/- 4 micronEq/hour), but postprandial acid output significantly exceeded prevagotomy values at all time periods (P less than 0.05). Cumulative acid output also was increased (R = 6.8 +/- 0.6 MEq/8 hour; PGV = 11.2 +/- 0.6 mEq/8 hour; P less than 0.001). Serum gastrin, however, remained unchanged. Hypersecretion of acid from Heidenhain pouches after massive enterectomy is increased further by PGV without a concomitant increase in serum gastrin.

Intestinal osmoregulation of single component meals in neonatal piglets.

The ability of the neonatal stomach and duodenum to modify the osmolality of hypotonic and hypertonic meals containing a single nutrient was studied in 3- to 5-day-old piglets. Test meals were administered through a gastrostomy and samples of gastric content and all proximal jejunal effluent were collected every 30 minutes for 2 hours. Hypotonic meals (149 mosm/L) and hypertonic meals (497 mosm/L) of glucose, crystalline amino acids, or lipids were used. Results were similar after all meals. There were significant changes in intragastric osmolality at each postprandial time period. However, osmolality never returned to basal levels. During duodenal transit there were further increases in osmolality after hypotonic meals and decreases after hypertonic meals but isotonic levels were never achieved. As a result, chyme of widely divergent osmolality entered the jejunum until late in the observation periods. Influx of sodium, potassium, and chloride were similar after all meals and were independent of original meal osmolality. These data indicate that, in awake, unstressed neonatal piglets, the stomach and duodenum are capable of effective but incomplete osmoregulation of hypotonic and hypertonic single component meals.