Interplane Tunneling Magnetoresistance in a Layered Manganite Crystal

The current-perpendicular-to-plane magnetoresistance (CPP-MR) has been investigated for the layered manganite, La2-2xSr1+2xMn2O7 (x = 0.3), which is composed of the ferromagnetic-metallic MnO2 bilayers separated by nonmagnetic insulating block layers. The CPP-MR is extremely large (10(4) percent at 50 kilo-oersted) at temperatures near above the three-dimensional ordering temperature (Tc approximately 90 kelvin) because of the field-induced coherent motion between planes of the spin-polarized electrons. Below Tc, the interplane magnetic domain boundary on the insulating block layer serves as the charge-transport barrier, but it can be removed by a low saturation field, which gives rise to the low-field tunneling MR as large as 240 percent.

Visualization of the local insulator-metal transition in Pr0.7Ca0. 3MnO3

The light-induced insulator-metal transition in the "colossal magnetoresistance" compound Pr0.7Ca0.3MnO3 is shown to generate a well-localized conducting path while the bulk of the sample remains insulating. The path can be visualized through a change of reflectivity that accompanies the phase transition. Its visibility provides a tool for gaining insight into electronic transport in materials with strong magnetic correlations. For example, a conducting path can be generated or removed at an arbitrary position just because of the presence of another path. Such manipulation may be useful in the construction of optical switches.

Spatially Inhomogeneous Metal-Insulator Transition in Doped Manganites

Scanning tunneling spectroscopy was used to investigate single crystals and thin films of La(1-x)Ca(x)MnO(3) (with x of about 0.3), which exhibit colossal magnetoresistance. The different spectroscopic signatures of the insulating (paramagnetic) and metallic (ferromagnetic) phases enable their spatial extent to be imaged down to a lateral scale of the order of 10 nanometers. Above the bulk transition temperature T(c), the images show mostly insulating behavior. Below T(c), a phase separation is observed where inhomogeneous structures of metallic and more insulating areas coexist and are strongly field dependent in their size and structure. Insulating areas are found to persist far below T(c). These results suggest that the transition and the associated magnetoresistance behavior should be viewed as a percolation of metallic ferromagnetic domains.

Induction of IFN-gamma and IL-1 alpha production in macrophages stimulated with phosphopolysaccharide produced by Lactococcus lactis ssp. cremoris

The induction of interferon (IFN) and interleukin-1 (IL-1) production in murine macrophages by a phosphopolysaccharide, produced by a dairy lactic acid bacteria, Lactococcus lactis ssp. cremoris, was investigated. When the phosphopolysaccharide was added into macrophage cultures at concentrations from 1 to 200 micrograms/ml, substantial IFN titers (6.2-79.2 IU/ml) were detected. Using the reverse transcription-polymerase chain reaction (RT-PCR), the expression of mRNA encoding IFN-gamma was verified in spleen macrophage cultures. Macrophages stimulated with the phosphopolysaccharide also produced IL-1 alpha at a concentration of 50 micrograms/ml. This study showed for the first time that phosphopolysaccharide derived from a dairy lactic acid bacterium can induce IFN-gamma and IL-1 alpha production in macrophages. These findings strongly suggest that the phosphopolysaccharide is a type of 'biological response modifier' and the fermented dairy foods containing Lactococcus lactis ssp. cremoris can be designated as a physiologically functional food.

Molecular cloning of the nemA gene encoding N-ethylmaleimide reductase from Escherichia coli

Using the gene mapping membrane technique, we identified a gene (nemA) that encodes N-ethylmaleimide reductase in Escherichia coli. The open reading frame encodes a polypeptide of 365 amino acids with a molecular mass of 39,514 Da. The deduced amino acid sequence showed a high degree of homology (87% identical) with the pentaerythritol tetranitrate reductase of Enterobacter cloacae and the morphinone reductase of Pseudomonas putida (52% identical).

Heterogeneity of functional outcomes in patients with bipolar disorder: a cluster-analytic approach

OBJECTIVE

The aim was to examine the heterogeneity of psychosocial outcomes in euthymic bipolar disorder (BD) patients and analyse the potential influence of distinct variables on functioning.

METHOD

Using a hierarchical cluster exploratory analysis, 143 euthymic patients with diagnosis of BD were grouped according to their functional performance based on domains scores of the Functioning Assessment Short Test (FAST). The resulting groups were compared on sociodemographic, clinical and neurocognitive variables to find factors associated with each functional cluster.

RESULTS

Patients were grouped in three functional profiles: patients with good functioning in all the FAST areas, patients with an intermediate profile showing great difficulties in the occupational domain and milder difficulties in most of the rest domains, and a third group with serious difficulties in almost all functional areas. Both functionally impaired groups were characterized by higher subthreshold symptoms (depressive and manic) and higher unemployment rates. The most functionally impaired group also showed lower scores on some measures of processing speed.

CONCLUSION

Two of three functional profiles showed some kind of impairment which was associated with subsyndromal symptoms and cognitive performance. These patterns should be taken into consideration to develop more individualized interventions to restore, or improve, psychosocial outcomes.

Simultaneous quantification of prostaglandins in human synovial cell-cultured medium using liquid chromatography/tandem mass spectrometry

A liquid chromatographic-tandem mass spectrometric (LC/MS-MS) method was developed for the simultaneous quantification of prostaglandin (PG) E(2), PGF(2alpha), 6-keto-PGF(lalpha) and thromboxane (TX) B(2). These eicosanoids and their deuterium derivatives, using as internal standards, were extracted by solid-phase extraction and analyzed using LC/MS-MS in the selected reaction-monitoring (SRM) mode. A good linear response over the range of 10 pg to 10 ng for each eicosanoid was demonstrated. The accuracy of added eicosanoids ranged from 94.1 to 106.6% and coefficients of variation ranged from 0.62 to 7.8%. Furthermore, we applied this method for the determination of eicosanoids in the human synovial cell-cultured medium, stimulated by lipopolysaccharide (LPS). LPS produced each eicosanoid and they increased in a time-dependent manner. The production levels after 24 h stimulation were 6-keto-PGF(1alpha) > PGE(2) > TXB(2) >> PGF(2alpha). This simultaneous quantification method is so useful to clarify the function of synovial cells in rheumatoid arthritis (RA).

Underdeveloped uterus and reduced estrogen responsiveness in mice with disruption of the estrogen-responsive finger protein gene, which is a direct target of estrogen receptor alpha

The biological roles of estrogen-responsive finger protein (efp) in vivo were evaluated in mice carrying a loss-of-function mutation in efp by gene-targeted mutagenesis. Although efp homozygous mice were viable and fertile in both sexes, the uterus that expressed abundant estrogen receptor alpha exhibited significant underdevelopment. When the ovariectomized homozygotes were subjected to 17beta-estradiol treatment, they showed remarkably attenuated responses to estrogen, as exemplified by decreased interstitial water imbibition and retarded endometrial cell increase, at least, attributable to the lower ratio of G1 to S-phase progression in epithelial cells. These results suggest that efp is essential for the normal estrogen-induced cell proliferation and uterine swelling as one of the direct targets of estrogen receptor alpha.

Treatment of neurocognitive symptoms in unipolar depression: A systematic review and future perspectives

BACKGROUND

Cognitive symptoms in Major Depressive Disorder (MDD) are persistent and commonly entail neurocognitive impairment and a decline in quality of life. This systematic review gathers the current scientific evidence on therapeutic strategies for neuropsychological impairment in MDD.

METHOD

A systematic search on PubMed, PsycINFO and Clinicaltrials.gov was carried out on December 2016 according to PRISMA using Boolean terms to identify interventions for the treatment of cognitive dysfunction in MDD. Only English-written articles providing original data and focusing in adults with MDD were included with no time restrictions.

RESULTS

A total of 95 studies reporting data on 40 pharmacological and non-pharmacological interventions were included. Interventions were grouped into the following categories: 1) Pharmacological Therapies (antidepressants, stimulants, compounds acting on NMDA receptors, compounds acting on the cholinergic system, compounds showing anti-inflammatory or antioxidant properties, other mechanisms of action), 2) Physical Therapies and 3) Psychological Therapies, 4) Exercise. There are some promising compounds showing a positive impact on cognitive symptoms including vortioxetine, lisdexamfetamine or erythropoietin.

LIMITATIONS

The studies included showed significant methodological differences in heterogeneous samples. The lack of a standardized neuropsychological battery makes comparisons between studies difficult.

CONCLUSION

Current evidence is not sufficient to widely recommend the use of procognitive treatments in MDD although promising results are coming to light.

Coherent orbital waves in the photo-induced insulator-metal dynamics of a magnetoresistive manganite

Photo-excitation can drive strongly correlated electron insulators into competing conducting phases, resulting in giant and ultrafast changes of their electronic and magnetic properties. The underlying non-equilibrium dynamics involve many degrees of freedom at once, whereby sufficiently short optical pulses can trigger the corresponding collective modes of the solid along temporally coherent pathways. The characteristic frequencies of these modes range between the few GHz of acoustic vibrations to the tens or even hundreds of THz for purely electronic excitations. Virtually all experiments so far have used 100 fs or longer pulses, detecting only comparatively slow lattice dynamics. Here, we use sub-10-fs optical pulses to study the photo-induced insulator-metal transition in the magnetoresistive manganite Pr(0.7)Ca(0.3)MnO(3). At room temperature, we find that the time-dependent pathway towards the metallic phase is accompanied by coherent 31 THz oscillations of the optical reflectivity, significantly faster than all lattice vibrations. These high-frequency oscillations are suggestive of coherent orbital waves, crystal-field excitations triggered here by impulsive stimulated Raman scattering. Orbital waves are likely to be initially localized to the small polarons of this room-temperature manganite, coupling to other degrees of freedom at longer times, as photo-domains coalesce into a metallic phase.

Normal-state charge dynamics in doped BaFe₂As₂: roles of doping and necessary ingredients for superconductivity

In high-transition-temperature superconducting cuprates and iron arsenides, chemical doping plays an important role in inducing superconductivity. Whereas in the cuprate case, the dominant role of doping is to inject charge carriers, the role for the iron arsenides is complex owing to carrier multiplicity and the diversity of doping. Here, we present a comparative study of the in-plane resistivity and the optical spectrum of doped BaFe₂As₂, which allows for separation of coherent (itinerant) and incoherent (highly dissipative) charge dynamics. The coherence of the system is controlled by doping, and the doping evolution of the charge dynamics exhibits a distinct difference between electron and hole doping. It is found in common with any type of doping that superconductivity with high transition temperature emerges when the normal-state charge dynamics maintains incoherence and when the resistivity associated with the coherent channel exhibits dominant temperature-linear dependence.

Concise synthesis of ciguatoxin ABC-ring fragments and surface plasmon resonance study of the interaction of their BSA conjugates with monoclonal antibodies

Monoclonal antibodies (mAbs), 4H2 and 6H7, were prepared previously using a protein conjugate of a 1:1 epimeric mixture of the synthetic ABC-ring fragments of ciguatoxin (CTX), 3 and 4. Here, the interactions of these mAbs with the fragments of CTX and CTX3C, 3 and 5, were investigated by surface plasmon resonance (SPR) spectroscopy in an attempt to clarify an antigenic determinant. Compared with the previous synthesis, the fragment 3 possessing the 2S configuration was synthesized from tri-O-acetyl-D-glucal much more effectively. The mAb 4H2 was already known to show a dose-dependent binding to the bovine serum albumin (BSA) conjugate of 3, but not to that of 5. The present SPR study of 4H2 demonstrates that the A-ring side chain of 3 plays a decisive role as an epitope. Therefore, SPR can effectively replace the ELISA method for the analysis of mAbs.

Gate control of electronic phases in a quarter-filled manganite

Electron correlation often produces a variety of electrically insulating states caused by self-organization of electrons, which are particularly stable at commensurate fillings. Although collapsing such ordered states by minute external stimuli has been a key strategy toward device applications, it is difficult to access their true electronic phase boundaries due to the necessity of fine-tuning of material parameters. Here, we demonstrate the ambipolar resistance switching in Pr(1-x)Sr(x)MnO3 thin films (x = 0.5; an effectively 1/4-filled state) by quasi-continuous control of the doping level x and band-width W using gate-voltage and magnetic field, enabled by the extreme electric-field formed at the nanoscale interface generated in an electrolyte-gated transistor. An electroresistance peak with unprecedented steepness emerges on approaching a critical point in the x-W phase diagram. The technique opens a new route to Mott-insulator based transistors and to discovering singularities hitherto unnoticed in conventional bulk studies of strongly correlated electron systems.

Genetic variation in ABCB1 influences paclitaxel pharmacokinetics in Japanese patients with ovarian cancer

Paclitaxel, an antineoplastic agent used for the treatment of ovarian cancer, is metabolized by cytochrome P450 (CYP)3A4 and CYP2C8 and is excreted from cells by ATP-binding cassette (ABCB1) (multi-drug resistance [MDR1], P-glycoprotein). Expression of these proteins is regulated by pregnane X receptor (PXR). Although there are common genetic polymorphisms in the genes encoding these proteins, their effect on the clinical efficacy of paclitaxel is unclear. We therefore examined the relationship of the paclitaxel pharmacokinetics in 13 patients with ovarian cancer to polymorphisms in CYP2C8, CYP3A5, ABCB1, and PXR. We found high interindividual variability in the plasma concentrations of two metabolites, 6alpha-hydroxypaclitaxel and p-3'-hydroxypaclitaxel. All the patients were genotyped as CYP2C8*1/*1. Neither the CYP3A5 A6986G (CYP3A5*3) nor the PXR C-25385T alleles were associated with altered plasma concentrations of paclitaxel and its metabolites. ABCB1 T-129C, T1236C, and G2677(A,T), however, was associated with lower area under the plasma concentration-time curve (AUC) of paclitaxel. We also observed a significant correlation between the AUC (r=-0.721) or the total clearance of paclitaxel (CL(tot)) (r= 0.673) and the ABCB1 mutant allele dosage in each patient. Taken together, our findings suggest that interindividual variability in paclitaxel pharmacokinetics could be predicted by ABCB1 genotyping.

Colossal magnetoresistance without phase separation: disorder-induced spin glass state and nanometer scale orbital-charge correlation in half doped manganites

The magnetic and electrical properties of high-quality single crystals of A-site disordered (solid solution) Ln0.5Ba0.5MnO3 are investigated near the phase boundary between the spin-glass insulator and colossal-magnetoresistive ferromagnetic metal, locating near Ln=Sm. The temperature dependence of the ac susceptibility and the x-ray diffuse scattering of Eu0.5Ba0.5MnO3 are analyzed in detail. The uniformity of the random potential perturbation in Ln0.5Ba0.5MnO3 crystals with a small bandwidth yields, rather than the phase separation, an homogeneous short ranged charge or orbital order which gives rise to a nearly atomic spin-glass state. Remarkably, this microscopically disordered "charge-exchange-glass" state alone is able to bring forth the colossal magnetoresistance.

Random potential effect near the bicritical region in perovskite manganites as revealed by comparison with the ordered perovskite analogs

The orbital-charge-spin ordering phase diagram for half-doped perovskites Ln(1/2)Ba(1/2)MnO3 (Ln = rare earth) with ordered Ln/Ba cations has been investigated comparatively with that of the Ln/Ba solid-solution analogs. A large modification of the phase diagram is observed upon the A-site disordering near the original bicritical point between the charge-orbital ordering and ferromagnetic metallic phases. The random potential by quenched disorder inherent in the A-site solid solution is found to suppress the respective long-range orders and gives rise to the colossal magnetoresistive state.