Anomalous anisotropic behaviour of spin-triplet proximity effect in Au/SrRuO3/Sr2RuO4 junctions.

Spin-polarized supercurrents can be generated with magnetic inhomogeneity at a ferromagnet/spin-singlet-superconductor interface. In such systems, complex magnetic inhomogeneity makes it difficult to functionalise the spin-polarized supercurrents. However, spin-polarized supercurrents in ferromagnet/spin-triplet-superconductor junctions can be controlled by the angle between magnetization and spin of Copper pairs (d-vector), that can effectively be utilized in developing of a field of research known as superconducting spintronics. Recently, we found induction of spin-triplet correlation into a ferromagnet SrRuO3 epitaxially deposited on a spin-triplet superconductor Sr2RuO4, without any electronic spin-flip scattering. Here, we present systematic magnetic field dependence of the proximity effect in Au/SrRuO3/Sr2RuO4 junctions. It is found that induced triplet correlations exhibit strongly anisotropic field response. Such behaviour is attributed to the rotation of the d-vector of Sr2RuO4. This anisotropic behaviour is in contrast with the vortex dynamic. Our results will stimulate study of interaction between ferromagnetism and unconventional superconductivity.

Dripping of a crystal.

Dripping is usually associated with fluid motion, but here we describe the analogous phenomenon of a 3He crystal growing and melting under the influence of surface tension and gravity. The pinch-off of the crystal is described by a purely geometric equation of motion, viscous dissipation or inertia being negligible. In analogy to fluid pinch-off, the minimum neck radius R{n} goes to zero like a power law, but with a new scaling exponent of 12 . However, for a significant part of the neck's macroscopic evolution the scaling exponent is found to be much closer to 13 . This observation may be consistent with simulations and theoretical results showing a very slow approach to the asymptotic pinch solution, making the "critical region" very small, both in time and space. After pinch-off, we observe a similar 13 -scaling for the recoil of a crystal tip, both in simulation and experiment. For very early times our experiments are consistent with an approximate theory predicting an asymptotic regime with exponent 12 . Future experiments must show whether the transient 13 scaling is a universal feature of crystal melting, or perhaps an artifact of our experimental setup.

Direct penetration of spin-triplet superconductivity into a ferromagnet in Au/SrRuO3/Sr2RuO4 junctions.

Efforts have been ongoing to establish superconducting spintronics utilizing ferromagnet/superconductor heterostructures. Previously reported devices are based on spin-singlet superconductors (SSCs), where the spin degree of freedom is lost. Spin-polarized supercurrent induction in ferromagnetic metals (FMs) is achieved even with SSCs, but only with the aid of interfacial complex magnetic structures, which severely affect information imprinted to the electron spin. Use of spin-triplet superconductors (TSCs) with spin-polarizable Cooper pairs potentially overcomes this difficulty and further leads to novel functionalities. Here, we report spin-triplet superconductivity induction into a FM SrRuO3 from a leading TSC candidate Sr2RuO4, by fabricating microscopic devices using an epitaxial SrRuO3/Sr2RuO4 hybrid. The differential conductance, exhibiting Andreev-reflection features with multiple energy scales up to around half tesla, indicates the penetration of superconductivity over a considerable distance of 15 nm across the SrRuO3 layer without help of interfacial complex magnetism. This demonstrates potential utility of FM/TSC devices for superspintronics.

Fusion of dioleoylphosphatidylcholine vesicles induced by an amphiphilic cationic peptide and oligophosphates at neutral pH.

Peptide E5 is an analogue of the fusion peptide of influenza virus hemagglutinin and K5 is a cationic peptide which has an arrangement of electric charges complementary to that of E5. We reported that a stoichiometric mixture of E5 and K5 caused fusion of large unilamellar vesicles (LUV) of neutral phospholipids (Murata, M., Kagiwada, S., Takahashi, S. and Ohnishi, S. (1991) J. Biol. Chem. 266, 14353-14358). K5 caused fusion of LUV composed of dioleoylphosphatidylcholine (DOPC) at pH > 10, but not at neutral pH. In the presence of oligophosphates, such as 1 mM ATP, GTP, or polyphosphate, K5 caused rapid and efficient fusion of DOPC LUV at neutral pH without hydrolysis of oligophosphate groups, but another anions such as citrate, acetate, AMP, phosphate, or EDTA were ineffective. The peptide/oligophosphate-induced fusion behaviors have been investigated by a fluorescence resonance energy transfer assay for lipid mixing of LUV and negative staining electron microscopy. At higher ionic strengths ( > 0.3 M KCl) or in the presence of 5.0 mM MgCl2, the fusion was inhibited. Even at the inhibitory conditions, the association of K5 with lipid vesicles at neutral pH was directly confirmed by the Ficoll gradient assay method and by blue shifts of the tryptophan fluorescence of the peptide. A nonhydrolyzable GTP analogue, GTP gamma S, also induced fusion. These observations suggested that the electrostatic interactions between the positive and negative charges of K5 and oligophosphate, respectively, induced complex formation, triggering membrane fusion.

Cyclin D1 amplification correlates with early recurrence of squamous cell carcinoma of the tongue.

Amplification of CCND1 was studied in 23 tongue carcinoma patients by fluorescence in situ hybridization (FISH) using a paraffin embedded specimen. All the patients received complete resection of the primary site with or without neck dissection. CCND1 amplification was positive in 13 (56.5%) out of 23 cases. Correlations between CCND1 amplification and histological grading, T category, N category, and Stages were not significant. The 5-year disease-free survival rate, which was 23.1% for CCND1 amplification positive patients and 80.0% for negative patients, was significantly better for the CCND1 amplification negative patients (P=0.0070). Nine patients were examined by dual-color FISH with the probe for centromere of chromosome 11 and 11q13. In five patients, who had positive amplification for CCND1, cell numbers with a larger number of signals for 11q13 than the centromere of chromosome 11 were significantly higher than those of CCND1 amplification negative patients (P=0.013). This indicates that amplification of 11q13 occurs more frequently than aberration of chromosome 11 in CCND1 amplification positive patients. From these results, the amplification of CCND1 is a key factor in predicting the aggressiveness of tongue cancer. Furthermore, FISH proved to be a useful method for such evaluation.

Granulocyte-macrophage colony-stimulating factor upregulates matrix metalloproteinase-2 (MMP-2) and membrane type-1 MMP (MT1-MMP) in human head and neck cancer cells.

Matrix metalloproteinase-2 (MMP-2) and membrane type 1-MMP (MT1-MMP) play an important role in the invasion and metastasis of head and neck squamous cell carcinoma (HNSCC), but the mechanism of their regulation is not clearly understood. Recently, granulocyte-macrophage colony-stimulating factor (GM-CSF) has been shown to be associated with cancer invasion and metastasis. We hypothesized that GM-CSF may upregulate MMP-2 and/or MT1-MMP expression in HNSCC cells, and may thereby influence their ability to invade and metastasize. We studied the effects of GM-CSF on the production of MMP-2 and MT1-MMP in HNSCC cell lines SAS and HSC-2. Gelatin zymography of conditioned media derived from HNSCC cells revealed a major band of 68 kDa, which was characterized as proMMP-2. GM-CSF stimulated the production of proMMP-2 in both cell lines in a dose-dependent manner. Treatment with 50 ng/ml GM-CSF for 24 h increased the proMMP-2 activity 3.4-fold in SAS cells and 2.3-fold in HSC-2 cells compared with untreated controls. Northern blot analyses demonstrated that GM-CSF led to elevated mRNA levels of MMP-2 and MT1-MMP in both cell lines. The results identify GM-CSF as a regulator of MMP-2 and MT1-MMP expression in certain types of HNSCC, and suggest that GM-CSF may contribute to the invasiveness of HNSCC through the regulation of MMP-2 and MT1-MMP expression.

[Measurement of human thyroid peroxidase autoantibodies by enzyme immunoassay using recombinant human TPO].

An EIA for measuring anti-TPO autoantibodies (rhTPO-EIA) was developed using recombinant human TPO expressed in CHO cells and was compared with MC-HA generally used in laboratory routine work. rhTPO-EIA showed a satisfactory reproducibility in the intra-assay test and did not have an accidental error of lots. Almost equal number of healthy females and males were measured for their IgG binding to TPO to define a normal range of anti-TPO autoantibodies. After setting 20 IU/ml as an upper limit of normal range, sera from patient with thyroid disorders were measured for their anti-TPO autoantibodies. Chronic thyroiditis and Graves' disease were highly positive, while adenoma, thyroid cancer, SLE, and RA were low in their positivity. The positive rate of anti-TPO autoantibodies was compatible to those of previous reports in each disorder. Seventy-two sera from patients with chronic thyroiditis or Graves' disease were measured for their autoantibodies by both rhTPO-EIA and MC-HA and the results were compared between both methods. A correlation coefficient was 0.486. Following absorption with thyroglobulin, sera were measured again and as the results, the correlation coefficient increased to 0.723. Therefore, MC-HA was thought to be influenced in the presence of anti-thyroglobulin autoantibodies. Since rhTPO-EIA is excellent in quality and not affected by anti-thyroglobulin antibodies, it is useful and applicable to clinical diagnosis and observation of thyroid disorders.

[Medical cost analysis of neoadjuvant chemotherapy for advanced tongue and oropharyngeal cancer].

We performed a medical cost analysis on the use of neoadjuvant chemotherapy (NAC) in multi-modal treatments for advanced tongue and oropharyngeal cancer. Twenty-two patients with stage III and IV squamous cell carcinoma of the tongue and oropharynx were enrolled in this study. Two courses of NAC with CDDP and 5-FU followed by radiotherapy were performed in 13 patients who showed a partial response or a complete response after the first course of NAC. The doses of radiation were 60 Gy for 4 patients (rad. group), and 72 Gy for 9 patients who received hyperfractionated radiotherapy with simultaneous Carboplatin (HF rad. group). Radical surgery was performed in 9 patients who did not respond to NAC (surg. group). The mean duration of hospital stay was 89.3 days for the rad. group, 92.0 days for the HF rad. group, and 113.3 days for the surg. group. The mean medical cost was 238,700 points for the rad. group, 264,846 points for the HF rad. group, and 459,468 points for the surg. group. The mean amounts and percentages of cost for NAC were 39,473 points and 16.1% for the rad. group, 44,802 points and 16.9% for the HF rad. group, and 23,451 points and 5.1% for the surg. group. The mean amounts of cost for NAC including examination costs and nursing costs for chemotherapy were 130,196 points and 54.5% for the rad. group, 150,046 points and 55.7% for the HF rad. group, and 113,839 points and 24.8% for the surg. group. The cost of NAC accounted for half of the total cost of chemo-radiation treatment for functional preservation. The duration of the hospital stay was prolonged by NAC, which accounted for a quarter of the total cost for the surg. group. Survival benefits are considered in the analysis of treatment cost-effectiveness for head and neck cancers. In the future, QOL, which is defined as the utility achieved as a result of multi-modal treatments, should also be analyzed along with survival benefits. Cost-utility analyses should include quality-adjusted life years, based upon the cost identification results of our analysis for NAC, to evaluate the efficacy of NAC in multi-modal treatments for head and neck cancers.

Anomalous switching in Nb/Ru/Sr2RuO4 topological junctions by chiral domain wall motion.

A spontaneous symmetry breaking in a system often results in domain wall formation. The motion of such domain walls is utilized to realize novel devices like racetrack-memories, in which moving ferromagnetic domain walls store and carry information. Superconductors breaking time reversal symmetry can also form domains with degenerate chirality of their superconducting order parameter. Sr2RuO4 is the leading candidate of a chiral p-wave superconductor, expected to be accompanied by chiral domain structure. Here, we present that Nb/Ru/Sr2RuO4 topological superconducting-junctions, with which the phase winding of order parameter can be effectively probed by making use of real-space topology, exhibit unusual switching between higher and lower critical current states. This switching is well explained by chiral-domain-wall dynamics. The switching can be partly controlled by external parameters such as temperature, magnetic field and current. These results open up a possibility to utilize the superconducting chiral domain wall motion for future novel superconducting devices.

Superfluidity of grain boundaries and supersolid behavior.

When two communicating vessels are filled to a different height with liquid, the two levels equilibrate because the liquid can flow. We have looked for such equilibration with solid (4)He. For crystals with no grain boundaries, we see no flow of mass, whereas for crystals containing several grain boundaries, we detect a mass flow. Our results suggest that the transport of mass is due to the superfluidity of grain boundaries.

Pinning of texture and vortices of the rotating B-like phase of superfluid 3He confined in a 98% aerogel.

We have investigated pinning effects on texture and vortices of the B-like phase of superfluid (3)He in a rotating aerogel up to +/-2pi rad/s by cw-NMR. We observed deformation of the NMR spectra in rotation, due to counterflow between the superflow and the normal flow. The average intensity of the counterflow was calculated from the change of NMR spectra. The rotation dependence of the counterflow intensity is similar to the magnetization curve of hard type II superconductors or the counterflow response of (4)He-II in packed powders. This counterflow behavior is in qualitative agreement with a model that vortices are pinned unless the counterflow exceeds a critical velocity v(c). The temperature independence of v(c) suggests that v(c) is associated with the expansion of primordial vortices.

Interaction of fusogenic synthetic peptide with phospholipid bilayers: orientation of the peptide alpha-helix and binding isotherm.

We studied the binding characteristics of a synthetic 20-residue peptide to supported single planar bilayers of phosphatidylcholine, and the orientation of the peptide by Fourier-transform infrared spectroscopy with an attenuated total reflection method. This peptide, designed to resemble a putative fusion peptide of influenza virus hemagglutinin, assumes an amphiphilic alpha-helix and induces fusion of liposomes in an acidic solution (pH approximately 5). At neutral pH, the peptides were bound to lipid bilayers in the manner of a Langmuir's adsorption isotherm, and their orientation was nearly random or oblique. On the other hand, at acidic pH, the peptides were bound, making their helix axis parallel to the membrane surface, and the binding was cooperative. This cooperativity suggested dimerization of the peptides. These characteristics are expected to be important for the synthetic fusogenic peptide or the fusion peptide in hemagglutinin to induce membrane fusion.

Orientation of fusion-active synthetic peptides in phospholipid bilayers: determination by Fourier transform infrared spectroscopy.

A group of synthetic peptides having an amino acid sequence related to the N-terminal region of the influenza virus hemagglutinin HA-2 chain can induce phospholipid membrane fusion in a pH-dependent manner. These peptides bind to membranes to form alpha-helices even at pH's where no fusion activity is seen. We determined the orientation of these alpha-helical peptides in lipid multibilayers using attenuated total reflection infrared spectroscopy and found that the peptide alpha-helices took a preferential orientation, the helix axis being about 70 degrees from the normal of the membrane plane, or in other words rather parallel to the membrane plane. The orientation was almost independent of pH and a modification of the N-terminal amino group which reduced the fusion activity of the peptides. The determination was carried out for peptides in lipid multibilayers in dry or hydrated (membranes equilibrated with D2O vapor) conditions. Although a slight decrease in the helix orientation angle from the membrane normal was noticed for a hydrated system, the difference between the results for dry and hydrated conditions was small.

Coalescence of crystalline drops.

We present the first experimental analysis of drop coalescence in a case where the dynamics is not governed by viscous dissipation in the bulk nor by the inertia of the fluid flow, only by the geometry and mobility of surfaces. We found such a situation in the physics of 3He crystals near 0.32 K where the latent heat of crystallization vanishes. Two crystalline drops of 3He coalesce if their crystalline orientations are identical: a neck forms after the contact at time t=0, and the shape evolves towards that of one convex crystal by local growth and melting in a fraction of a second. We have found that the neck radius initially increases as t(1/3), as predicted by Maris. This behavior is also expected for superfluid drops. It is clearly distinguished from the logarithmic behavior and from the t(1/2) power law which have been predicted by Eggers et al. in more usual situations.

Modification of the N-terminus of membrane fusion-active peptides blocks the fusion activity.

The amphiphilic anionic peptides E5 and E5L can mimic the fusogenic activity of influenza hemagglutinin(HA). These peptides induced fusion of egg yolk phosphatidylcholine small or large unilamellar vesicles only at acidic pH in a similar manner to viral HA. Acetylation or acetimidylation of the N-terminus of the peptides drastically reduced the fusion activity of the intact peptides, while C-terminal amidation left the activity unchanged. The binding assay suggested that the interaction of the modified peptides with lipid membranes was almost unchanged in comparison with those of the parent peptides, and the CD spectra showed that these peptides were alpha-helical. The results showed the importance of the N-terminus of the peptides on the membrane fusion activity, although why the N-terminal modifications affect the activity is still unclear.

Vortex formation and annihilation in three textures of rotating superfluid 3He-A.

Textures, textural transformation, and formation and annihilation of a single vortex were investigated in narrow cylinders with 100 microm radius in A-phase under rotation up to 6.28 rad/sec. Three textures were found, depending on the cooling conditions of the sample through the superfluid transition temperature T(c). We found the gyromagnetic effect of textures; that is, two textures (A or B) could be selected either by applying a magnetic field in parallel or anti-parallel to the rotation axis. The critical angular speed of a single vortex formation Omega(f) and that of annihilation Omega(a) for each texture were measured. The textural transformation in type A texture was induced by rotation. Both type A and B textures held macroscopic angular momentum along the rotation axis. We identified the texture for type A, B, and C as Mermin-Ho, radial disgyration, and a soliton type of defect along the axis, respectively.