Magnetization control by angular momentum transfer from surface acoustic wave to ferromagnetic spin moments.

Interconversion between electron spin and other forms of angular momentum is useful for spin-based information processing. Well-studied examples of this are the conversion of photon angular momentum and rotation into ferromagnetic moment. Recently, several theoretical studies have suggested that the circular vibration of atoms work as phonon angular momentum; however, conversion between phonon angular momentum and spin-moment has yet to be demonstrated. Here, we demonstrate that the phonon angular momentum of surface acoustic wave can control the magnetization of a ferromagnetic Ni film by means of the phononic-to-electronic conversion of angular momentum in a Ni/LiNbO3 hybrid device. The result clearly shows that the phonon angular momentum is useful for increasing the functionality of spintronic devices.

Chirality Memory Stored in Magnetic Domain Walls in the Ferromagnetic State of MnP.

Chirality in a helimagnetic structure is determined by the sense of magnetic moment rotation. We found that the chiral information did not disappear even after the phase transition to the high-temperature ferromagnetic phase in a helimagnet MnP. The 2nd harmonic resistivity ρ^{2f}, which reflects the breaking down of mirror symmetry, was found to be almost unchanged after heating the sample above the ferromagnetic transition temperature and cooling it back to the helimagnetic state. The application of a magnetic field along the easy axis in the ferromagnetic state quenched the chirality-induced ρ^{2f}. This indicates that the chirality memory effect originated from the ferromagnetic domain walls.

Electric current control of spin helicity in an itinerant helimagnet.

A helimagnet is a chiral magnet in which the direction of the magnetic moment spatially rotates in a plane perpendicular to the propagation vector. The sense of the rotation known as spin helicity is a robust degree of freedom of matter and may provide a new concept of magnetic memory if it can be electrically controlled and detected. Here we show that the helicity can be controlled by magnetic fields and electric currents in an itinerant helimagnet MnP. Second-harmonic resistivity measurements allow us to read out the controlled helicity. In contract to an insulating multiferroic magnet, in which spin rotation was shown to be controllable by an electric field, we achieve helicity manipulation by using an electric current in the conducting helimagnet. The controllability of the spin helicity may pave the way to new method of realizing magnetic memories based on the spin internal degrees of freedom.

Magnetoelectrical control of nonreciprocal microwave response in a multiferroic helimagnet.

The control of physical properties by external fields is essential in many contemporary technologies. For example, conductance can be controlled by a gate electric field in a field effect transistor, which is a main component of integrated circuits. Optical phenomena induced by an electric field such as electroluminescence and electrochromism are useful for display and other technologies. Control of microwave propagation is also important for future wireless communication technology. Microwave properties in solids are dominated mostly by magnetic excitations, which cannot be easily controlled by an electric field. One solution to this problem is to use magnetically induced ferroelectrics (multiferroics). Here we show that microwave nonreciprocity, that is, different refractive indices for microwaves propagating in opposite directions, could be reversed by an external electric field in a multiferroic helimagnet Ba2Mg2Fe12O22. This approach offers an avenue for the electrical control of microwave properties.

Critical phenomena of emergent magnetic monopoles in a chiral magnet.

Second-order continuous phase transitions are characterized by symmetry breaking with order parameters. Topological orders of electrons, characterized by the topological index defined in momentum space, provide a distinct perspective for phase transitions, which are categorized as quantum phase transitions not being accompanied by symmetry breaking. However, there are still limited observations of counterparts in real space. Here we show a real-space topological phase transition in a chiral magnet MnGe, hosting a periodic array of hedgehog and antihedgehog topological spin singularities. This transition is driven by the pair annihilation of the hedgehogs and antihedgehogs acting as monopoles and antimonopoles of the emergent electromagnetic field. Observed anomalies in the magnetoresistivity and phonon softening are consistent with the theoretical prediction of critical phenomena associated with enhanced fluctuations of emergent field near the transition. This finding reveals a vital role of topology of the spins in strongly correlated systems.

Application of strain to orbital-spin-coupled system MnV2O4 at cryogenic temperatures within a transmission electron microscope.

The impact of mechanical stress on the morphology of crystallographic and magnetic domains in shape-controlled specimens of an orbital-spin-coupled system, MnV2O4, was examined by cryogenic Lorentz microscopy. Because of the difference in thermal expansion coefficients of MnV2O4 and the supporting Mo mesh, compression on the order of 0.01% was applied to the thin-foil specimens near the structural/magnetic phase transformation temperatures. The extent of compression was comparable to the lattice striction associated with the cubic-to-tetragonal phase transformation in MnV2O4 The applied strain thus clearly influenced the morphology of crystallographic domains (i.e. twinning configuration in the tetragonal phase) produced during cooling. The magnetic domain structure was entirely dependent on the configuration of twinning in the tetragonal phase. The observations in this study provided useful information for understanding the relationship between the crystallographic domains and the magnetic domains in MnV2O4.

Uniaxial stress control of skyrmion phase.

Magnetic skyrmions, swirling nanometric spin textures, have been attracting increasing attention by virtue of their potential applications for future memory technology and their emergent electromagnetism. Despite a variety of theoretical proposals oriented towards skyrmion-based electronics (that is, skyrmionics), few experiments have succeeded in creating, deleting and transferring skyrmions, and the manipulation methodologies have thus far remained limited to electric, magnetic and thermal stimuli. Here, we demonstrate a new approach for skyrmion phase control based on a mechanical stress. By continuously scanning uniaxial stress at low temperatures, we can create and annihilate a skyrmion crystal in a prototypical chiral magnet MnSi. The critical stress is merely several tens of MPa, which is easily accessible using the tip of a conventional cantilever. The present results offer a new guideline even for single skyrmion control that requires neither electric nor magnetic biases and consumes extremely little energy.

Elastic stiffness of a Skyrmion crystal.

We observe the elastic stiffness and ultrasonic absorption of a Skyrmion crystal in the chiral-lattice magnet MnSi. The Skyrmion crystal lattice exhibits a stiffness 3 orders of magnitude smaller than that of the atomic lattice of MnSi, being as soft as the flux line lattice in type-II superconductors. The observed anisotropic elastic responses are consistent with the cylindrical shape of the Skyrmion spin texture. Phenomenological analysis reveals that the spin-orbit coupling is responsible for the emergence of anisotropic elasticity in the Skyrmion lattice.

Comparison of calibrated dilute thrombin time and aPTT tests with LC-MS/MS for the therapeutic monitoring of patients treated with dabigatran etexilate.

Ways to monitor dabigatran etexilate (DE) therapy would be useful in certain situations. Functional assays such as aPTT or Hemoclot® Thrombin Inhibitor (HTI) have been proposed to evaluate dabigatran concentrations, but previous findings are based on in vitro studies and results must be confirmed in clinical samples. The aim of this study was to compare aPTT and HTI measurements with liquid chromatography-tandem mass spectrometry (LC-MS/MS) measurements of dabigatran in plasma samples from DE treated patients. Seventy-one plasma samples were included. aPTT was performed using STA-CKPrest® and SynthASil®. HTI was performed according to instructions from the manufacturer. The LC-MS/MS method utilised dabigatran-d3 as internal standard. The plasma concentration range was 0 to 645 ng/ml as measured by LC-MS/MS. Overall, the HTI and LC-MS/MS analyses correlated well (r²=0.97). The Bland-Altman analysis showed a mean difference of 9 ng/ml (SD: 20 ng/ml). However, the HTI performed poorly at concentrations <50 ng/ml. LC-MS/MS was sensitive (limit of quantification 1.1 ng/ml) and specific for dabigatran. The aPTT methods did not correlate well with plasma concentrations measured by LC-MS/MS (r² = 0.59 with SynthASil® and 0.50 with STA-CKPrest®). In conclusion, the poor sensitivity, the important inter-individual variability, and the poor correlation with LC-MS/MS preclude the use of aPTT to estimate dabigatran concentrations. Due to its small inter-individual variability and good agreement with LC-MS/MS measurements, we recommend the use of HTI assays to rather accurately estimate concentrations of dabigatran >50 ng/ml. Quantification of lower dabigatran levels in DE-treated patients requires the "reference" LC-MS/MS method.

Effect of high-fat diet on KKAy and ob/ob mouse liver and adipose tissue corticosterone and 11-dehydrocorticosterone concentrations.

The present study was performed to compare glucocorticoid levels in obese KKA (y) and ob/ob mice with those in normal C57BL/6J mice, and the effect of high-fat diet on glucocorticoids in KKA (y) and ob/ob mice. Liver, mesenteric and epididymal adipose tissue corticosterone and 11-dehydrocorticosterone concentrations as well as circulating corticosterone concentrations were measured. The KKA (y) and ob/ob mice displayed elevated serum corticosterone levels compared to normal mice, 2.0 to 2.8-fold in KKA (y), and 11 to 16-fold in ob/ob mice. Liver corticosterone levels were 3.0 to 5.1 and 6.2 to 8.1-fold, and 11-dehydrocorticosterone levels were 3.4 to 3.6 and 6.7 to 8.2-fold higher in KKA (y) and ob/ob mice compared to normal mice. Mesenteric adipose tissue corticosterone levels were 2.7 to 4.2-fold higher, and 11-dehydrocorticosterone levels were 2 to 4-fold higher in ob/ob than in KKA (y) mice. Epididymal adipose tissue corticosterone levels were 3.0 to 6.2-fold higher, and 11-dehydrocorticosterone levels were 1.8 to 2.0-fold higher in ob/ob than in KKA (y) mice. Circulating, hepatic, and mesenteric and epididymal adipose tissue glucocorticoid concentrations were low in the normal C57BL/6J mouse, high in the ob/ob mouse, and intermediate in the KKA (y) mouse. 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) mRNA levels were doubled in ob/ ob compared to KKA (y) mice in all three tissues. Glucocorticoid concentrations correlated with 11beta-HSD1 mRNA levels. High-fat diet had no effect on the tissue glucocorticoid concentrations.

Selective inhibition of 11beta-hydroxysteroid dehydrogenase type 1 decreases blood glucose concentrations in hyperglycaemic mice.

AIMS/HYPOTHESIS: Current pharmacological treatments for Type II (non-insulin-dependent) diabetes mellitus have various limitations. New treatments are needed to reduce long-term risks for diabetic complications and mortality. We tested a new principle for lowering blood glucose. It is well known that glucocorticoids in excess cause glucose intolerance and insulin resistance. The enzymes 11beta-hydroxysteroid dehydrogenase type 1 and type 2 inter-convert inactive and active glucocorticoids, thereby playing a major role in local modulation of agonist concentration and activation of corticosteroid receptors in target tissues. It has been hypothesized that selective inhibition of 11beta-hydroxysteroid dehydrogenase type 1 decreases excessive hepatic glucose production in hyperglycemia and diabetes. BVT.2733 is a new, small molecule, non-steroidal, isoform-selective inhibitor of mouse 11beta-hydroxysteroid dehydrogenase type 1. The aim of the present study is to test if selective inhibition of 11beta-hydroxysteroid dehydrogenase type 1 lowers blood glucose concentrations in a hyperglycaemic and hyperinsulinaemic mouse model. METHODS: BVT.2733 was given to spontaneously hyperglycaemic KKA(y) mice for 7 days using subcutaneous osmotic mini-pumps. RESULTS: BVT.2733 lowered hepatic PEPCK and glucose-6-phosphatase mRNA, blood glucose and serum insulin concentrations compared with vehicle treated mice. In contrast, hepatic 11beta-hydroxysteroid dehydrogenase type 1 mRNA, liver function marker enzyme expression (aspartate aminotransferase, alanine aminotransferase and alkaline phosphatases), daily food intake and body weight were not altered by the treatment. CONCLUSION/INTERPRETATION: These results suggest that a selective inhibitor of human 11beta-hydroxysteroid dehydrogenase type 1 can become a new approach for lowering blood glucose concentrations in Type II diabetes.

Effects of pH variation and NaCl on in vitro digestibility of cow's milk proteins in commercially available infant formulas.

Allergenicity and antigenicity of food proteins are generally dependent on their heat-stability and resistance to digestive enzymes. Using the methods of SDS-PAGE and immunoblots, we assessed peptic-digestibility of major milk proteins (casein, beta-lactoglobulin and alpha-lactalbumin) in commercially available infant formulas in acidic pH range (pH 1.5 to 4.0), and we also investigated the effect of NaCl on peptic-digestibility of cow's milk proteins at pH 2.0. The profile of peptic-digestion of casein was similar at pH range from 1.5 to 3.5 where the intact protein of casein rapidly disappeared, whereas slow digestibility of the protein was found at pH 4.0. Beta-lactoglobulin and alpha-lactalbumin were digested at pH range from 1.5 to 2.5 and were almost entirely resistant to peptic digestion at over pH 3.0. In the presence of NaCl at pH 2.0, casein showed a good digestibility by pepsin similar to that in the absence of NaCl, in contrast to beta-lactoglobulin and alpha-lactalbumin both having their peptic-digestibility decreased in the presence of 0.2 M NaCl. As the state of the stomach in new born infants shows low amounts of secretary pepsin and out of optimum pH of peptic activity, low digestibility of beta-lactoglobulin and alpha-lactalbumin in cow's milk based infant formulas at over pH 3.0 is supposed to be responsible for their allergenicity.

Heterogeneous expression of glycoconjugates among individual glomeruli of the hamster main olfactory bulb.

Glomeruli within the main olfactory bulb (MOB) are known as areas of synapse formation between axon terminals of olfactory neurons in the olfactory epithelium and dendrites of the first relay neurons (mitral and tufted cells) in the MOB, so that they serve as functional units in olfaction. We examined expression patterns of glycoconjugates in the glomeruli of the hamster MOB by lectin histochemistry using 21 biotinylated lectins. Thirteen lectins, WGA, s-WGA, DSL, DBA, SBA, WA, SJA, RCA-I, PNA, ECL, UEA-I, PSA and LCA, showed differential binding patterns among the glomeruli. To evaluate these differential binding patterns of lectins, we analysed staining intensity of each of the 13 lectins on the level of individual glomeruli by image analysis, and classified staining intensity into five grades (negative, 1+, 2+, 3+, 4+) on the basis of results obtained. This classification enables us to make detailed comparison among individual glomeruli. We further analysed the grade of staining intensity of each of the 13 lectins in the same glomerulus in adjacent serial sections by image analysis, and found that individual glomeruli varied in combination of grades of staining intensity and kinds of lectins. These results indicate that glycoconjugates are expressed heterogeneously in individual glomeruli, and that heterogeneous expression may contribute to the topographic organization of the primary olfactory pathway.

Translucence stereoscopy of interictal magnetoencephalographic epileptiform discharge.

We have developed a translucence stereoscopy method for displaying the distribution of multiple interictal epileptiform discharges within the intracranial space. The epileptiform discharges, measured using a whole-head magnetoencephalography system, were modeled by a least-squares method to obtain the equivalent current dipoles. The dipoles were located in the stereo pair of intracranial images composed of translucent brain slices at several selected levels. The technique demonstrated clearly the distribution of interictal dipoles within the brain in three patients. Three dimensional understanding of the intracranial distribution of multiple dipoles in one image is valuable in analyzing the intracerebral neurophysiological events in epileptic patients.

Does the central sulcus divide motor and sensory functions? Cortical mapping of human hand areas as revealed by electrical stimulation through subdural grid electrodes.

To clarify the exact anatomic relationship of electrically identified hand areas to the central sulcus, we constructed cortical surface renderings of magnetic resonance images (MRI) to locate the central sulcus accurately and measured the distances of stimulated points from the central sulcus and the Sylvian fissure. We obtained hand responses in 33 patients who underwent implantation of subdural grid electrodes for evaluation and surgical treatment of intractable epilepsy and analyzed these responses according to the presence of motor, sensory, mixed motor and sensory, and arrest responses. Hand motor responses occurred not only in the precentral gyrus but also in the postcentral gyrus, with great variability in superior-to-inferior distribution. Sensory responses also occurred in both the precentral and postcentral gyri with a distribution more ventral than that of motor responses. Mixed motor and sensory responses tended to be limited to the middle part of the central sulcus. Sites where electrical stimulation arrested simple hand repetitive voluntary movements occurred widely throughout the premotor and primary sensorimotor cortices. These data indicate a marked variability in the location of the human cortical hand area, and suggest that motor and sensory hand cortices overlap and are not divided in a simple manner by the central sulcus.

Subdivisions of the accessory olfactory bulb, as demonstrated by lectin-histochemistry in the golden hamster.

Lectin-binding patterns in the accessory olfactory bulb (AOB) of the golden hamster were investigated histochemically with 21 biotinylated lectins. The AOB was divided into rostral and caudal halves according to binding patterns of 16 lectins, WGA, s-WGA, LEL, STL, DSL, BSL-II, DBA, SBA, BSL-I, VVA, SJA, PNA, ECL, UEA-I, Con A and PSA. The caudal half of the AOB was further subdivided into anterior 2/3 and posterior 1/3 by 10 lectins, WGA, s-WGA, BSL-II, DBA, SBA, BSL-I, VVA, SJA, PNA and ECL. In addition, the rostral half of the AOB was subdivided into anterior 1/4 and posterior 3/4 by one lectin, PNA. Thus, the AOB of the golden hamster was divided into 4 divisions on the basis of lectin-binding patterns.

Enhanced phagocytosis of rat alveolar macrophages by intravenous infusion of an arginine-enriched solution.

Phagocytosis of rat alveolar macrophages (AM) was enhanced by the infusion of arginine-rich solution for 7 days. The enhancement of phagocytosis by arginine-rich solution was due to not the difference in the distribution of AM subpopulations (I to IV) but the difference in phagocytic activity of AM in fraction IV. In the process of phagocytosis, there were no significant differences in the stages of migration, attachment, and digestion between control and arginine-rich solutions, although AM from fraction IV of rats infused with arginine-rich solution showed significantly higher ingestion of opsonized sheep red blood cells (SRBC) compared to that of control group. Furthermore, the production of macrophage-activating factor (MAF) from rat splenocytes was higher in arginine-rich group than that of control group. AM from fraction IV of rats fed a stock diet had a higher arginase activity and showed a significant increase of phagocytosis following in vitro incubation with L-arginine (25 and 50 mM) for 24 h. From these results, the enhanced phagocytosis of AM by arginine-rich solution may be due to the increased phagocytosis of AM from fraction IV, in which the higher sensitivity of AM from fraction IV to arginine and the higher production of MAF from splenocytes following the infusion of arginine-rich solution participate.

Cell profile and elastase activity in diffuse panbronchiolitis investigated by bronchoalveolar and bronchial lavage.

To examine the mechanism of tissue damage which causes bronchiolectasis in diffuse panbronchiolitis (DPB), the cellular components, elastase and its main inhibitor, alpha 1-protease inhibitor (alpha 1-PI) were measured in bronchoalveolar and bronchial lavage fluid (BALF and BLF) from 14 DPB patients. A predominant increase in the neutrophil count was observed in DPB. Elastase activity in BALF and BLF was about 1,000-fold higher in the DPB group than in the control group. An inhibitor study and a positive correlation between elastase activity and the neutrophil count in both lavage fluids from the DPB group indicated that the activity was mainly that of neutrophil elastase. Western blot analysis of alpha 1-PI showed that most of the alpha 1-PI in the lavage fluids from DPB group was degraded. These results indicated that neutrophil infiltration increases the level of elastase in the DPB lesions; this increase seems to be closely related to tissue damage.