Highly efficient and tunable spin-to-charge conversion through Rashba coupling at oxide interfaces.

The spin-orbit interaction couples the electrons' motion to their spin. As a result, a charge current running through a material with strong spin-orbit coupling generates a transverse spin current (spin Hall effect, SHE) and vice versa (inverse spin Hall effect, ISHE). The emergence of SHE and ISHE as charge-to-spin interconversion mechanisms offers a variety of novel spintronic functionalities and devices, some of which do not require any ferromagnetic material. However, the interconversion efficiency of SHE and ISHE (spin Hall angle) is a bulk property that rarely exceeds ten percent, and does not take advantage of interfacial and low-dimensional effects otherwise ubiquitous in spintronic hetero- and mesostructures. Here, we make use of an interface-driven spin-orbit coupling mechanism-the Rashba effect-in the oxide two-dimensional electron system (2DES) LaAlO3/SrTiO3 to achieve spin-to-charge conversion with unprecedented efficiency. Through spin pumping, we inject a spin current from a NiFe film into the oxide 2DES and detect the resulting charge current, which can be strongly modulated by a gate voltage. We discuss the amplitude of the effect and its gate dependence on the basis of the electronic structure of the 2DES and highlight the importance of a long scattering time to achieve efficient spin-to-charge interconversion.

Non-Gilbert-damping Mechanism in a Ferromagnetic Heusler Compound Probed by Nonlinear Spin Dynamics.

The nonlinear decay of propagating spin waves in the low-Gilbert-damping Heusler film Co_{2}Mn_{0.6}Fe_{0.4}Si is reported. Here, two initial magnons with frequency f_{0} scatter into two secondary magnons with frequencies f_{1} and f_{2}. The most remarkable observation is that f_{1} stays fixed if f_{0} is changed. This indicates, that the f_{1} magnon mode has the lowest instability threshold, which, however, cannot be understood if only Gilbert damping is present. We show that the observed behavior is caused by interaction of the magnon modes f_{1} and f_{2} with the thermal magnon bath. This evidences a significant contribution of the intrinsic magnon-magnon scattering mechanisms to the magnetic damping in high-quality Heusler compounds.

Nonlinear emission of spin-wave caustics from an edge mode of a microstructured Co2Mn(0:6)Fe(0:4)Si waveguide.

Magnetic Heusler materials with very low Gilbert damping are expected to show novel magnonic transport phenomena. We report nonlinear generation of higher harmonics leading to the emission of caustic spin-wave beams in a low-damping microstructured Co(2)Mn(0.6)Fe(0.4)Si Heusler waveguide. The source for the higher harmonic generation is a localized edge mode formed by the strongly inhomogeneous field distribution at the edges of the spin-wave waveguide. The radiation characteristics of the propagating caustic waves observed at twice and three times the excitation frequency are described by an analytical calculation based on the anisotropic dispersion of spin waves in a magnetic thin film.

Long-lived ultrafast spin precession in manganese alloys films with a large perpendicular magnetic anisotropy.

Spin precession with frequencies up to 280 GHz is observed in Mn(3-δ)Ga alloy films with a perpendicular magnetic anisotropy constant K(u)∼15 M erg/cm(3). The damping constant α, characterizing macroscopic spin relaxation and being a key factor in spin-transfer-torque systems, is not larger than 0.008 (0.015) for the δ=1.46 (0.88) film. Those are about one-tenth of α values for known materials with large K(u). First-principles calculations well describe both low α and large K(u) for these alloys.

Dependence of ferroelectric and magnetic properties on measuring temperatures for polycrystalline BiFeO(3) films.

A multiferroic BiFeO(3) film was fabricated on a Pt/Ti/SiO(3)/Si(100) substrate by a chemical solution deposition (CSD) method, and this was followed by postdeposition annealing at 923 K for 10 min in air. X-ray diffraction analysis indicated the formation of the polycrystalline single phase of the BiFeO(3) film. A high remanent polarization of 89 microC/cm(2) was observed at 90 K together with a relatively low electric coercive field of 0.32 MV/cm, although the ferroelectric hysteresis loops could not be observed at room temperature due to a high leakage current density. The temperature dependence of the ferroelectric hysteresis loops indicated that these hysteresis loops lose their shape above 165 K, and the nominal remanent polarization drastically increased due to the leakage current. Magnetic measurements indicated that the saturation magnetization was less than 1 emu/cm(3) at room temperature and increased to approximately 2 emu/cm(3) at 100 K, although the spontaneous magnetization could not appear. The magnetization curves of polycrystalline BiFeO3 film were nonlinear at both temperatures, which is different with BiFeO3 single crystal.

Ferroelectric and magnetic properties of multiferroic BiFeO(3)-based composite films.

BiFeO(3)-based composite films were fabricated onto the Pt/Ti/SiO(2)/Si(100) substrates by a chemical solution deposition (CSD) method using the precursor solutions with various excess iron composition followed by annealing at 923 K for 30 minutes under oxygen gas flow. Coexistence of spontaneous magnetization and remanent polarization could be obtained in the BiFeO(3)-based composite films with high excess iron composition. The remanent magnetization of almost 20 emu/cm(3) and the magnetic coercive field of 1.5 kOe were obtained at the iron composition ratio of Fe/Bi = 1.25. In this specimen, the remanent polarization at 90 K was approximately 10 microC/cm(2) at the electric field of 1500 kV/cm. Structural analysis suggested that the remanent polarization has a possibility to increase by suppressing the formation of the secondary phases of Bi(2)Fe(4)O(9) and alpha-Fe(2)O(3), these are the nonferroelectric material as well as antiferromagnetic phase.

[Reoperation due to failure of a Freestyle bioprosthesis].

We report re-do aortic valve and ascending aorta replacements by using the valve-on-valve technique for primary tissue failure of a Freestyle bioprosthesis. A 74-year-old male, who had had a 25 mm Freestyle bioprosthetic valve implanted by the sub-coronary method 5 years previously for aortic valve regurgitation due to congenital bicuspid valve, was referred to our hospital for dyspnea and palpitation. He presented with heart failure secondary to aortic regurgitation due to primary tissue failure, and computed tomography demonstrated an enlarged ascending aorta (5 cm in diameter). The operative findings revealed that the Freestyle bioprosthetic valve had a leaflet tear at the left coronary cusp. We replaced the degenerated Freestyle bioprosthesis with a 19 mm Mosaic aortic bioprosthesis by using the valve-on-valve technique, and ascending aorta replacement was performed simultaneously. This technique can be useful for re-do surgery for degenerated stentless valves to avoid potential risks of complete excision of the bioprosthesis.

[Treatment of a massive tracheal bleeding with percutaneous cardiopulmonary support].

A 69-year-old woman was admitted to our hospital with heart failure. Echocardiography demonstrated severe mitral valve regurgitation due to chordae rupture of the posterior mitral leaflet. Although she was intubated and ventilation was initiated, her condition did not improve. On the 17th hospital day, she was scheduled to undergo mitral valve plasty. After induction of anesthesia, massive bleeding occurred from the tracheal granuloma (diameter, 3 cm), which had developed at the tip of the tracheal tube, and the airway was obstructed. Emergency percutaneous cardiopulmonary support (PCPS) was then introduced. Thereafter, endoscopic hemostasis was performed, followed by the excision of the granulation tissue using a gastric fiberscope. After excising the tissue, the patient could be ventilated; therefore, she was weaned from PCPS. The maximum PCPS flow was 4.0 l/min, and it was conducted for a 210-minutes duration. Her respiratory condition improved, and she was weaned from the ventilator 3 days after surgery. Mitral valve plasty was performed 55 days after the first operation, and she was discharged from the hospital in good health.

[Multiple acute aortic dissection; report of a case].

A 60-year-old woman has been followed under the diagnosis of De Bakey type Illb acute aortic dissection. She developed sudden backache, and the diagnosis based on the emergent computed tomography (CT) was De Bakey type I dissection. At the operation, previous De Bakey type Illb dissection was far from the new dissection observed in the ascending aorta and arch aorta. We replaced the ascending aorta and aortic arch with woven Dacron graft (arch first technique) under retrograde cerebral perfusion. Since the residual dissection (De Bakey type III) in the multiple aortic dissection has tendency to dilate fast, intensive follow-up of the patient would be necessary.

Ph-negative non-Hodgkin's lymphoma occurring in chronic phase of Ph-positive chronic myelogenous leukemia is defined as a genetically different neoplasm from extramedullary localized blast crisis: report of two cases and review of the literature.

This report describes two cases of Philadelphia chromosome-negative (Ph(-)) non-Hodgkin's lymphomas (NHLs) recognized in patients with chronic phase Ph-positive (Ph(+)) chronic myelogenous leukemia (CML). Lymph node biopsy of patient 1 was initially diagnosed as diffuse large B cell non-Hodgkin's lymphoma (NHL, T cell rich variant), but at relapse showed immunoblastic features with a marked decrease of admixed lymphocyte components. Patient 2 presented with thickened parietal pleura which revealed a CD30-positive anaplastic large cell lymphoma showing null cell phenotype and genotype with abundant admixed neutrophils and lymphocytes. At the time of lymphoma diagnosis, the patients had CML for 33 and 10 months, respectively. DNA obtained from bone marrow cells at the time of lymphoma diagnosis showed BCR/ABL gene rearrangements by both Southern blot analysis and reverse transcription polymerase chain reaction (RT-PCR), but lacked both immunoglobulin and T cell receptor gene rearrangements. BCR gene rearrangement and BCR/ABL fusion gene were also identified in lymph node and pleural biopsies by Southern blot and RT-PCR analysis, respectively. However, both biopsy specimens also contained reactive lymphocytes and neutrophils, and no fusion signals between BCR and ABL genes were identified in the hyperdiploid lymphoma cells of either case by fluorescence in situ hybridization (FISH). These data suggest the lymphoma cells in both cases were not genetically associated with BCR/ABL. Therefore, these cases were not diagnosed as an extramedullary localized blast crisis in CML, but as Ph(-) NHLs. This represents the first definitive demonstration of peripheral B cell lymphoma occurring by a separate genetic pathway, lacking BCR/ABL, in patients with Ph(+) CML. A review of the literature identified two different subtypes of malignant lymphomas arising in patients with an antecedent or concurrent diagnosis of CML. The most common are T cell lymphomas displaying an immature thymic phenotype, while peripheral B cell lymphomas are more rare. Our study shows, however, that 'Ph(+) NHL' occurring in CML or acute lymphocytic leukemia (ALL) may represent an unrelated neoplasm, even if standard cytogenetic analysis reveals a Ph(+) chromosome, and that FISH is required to confirm whether a localized lymphoid neoplasm is either a true extramedullary localized blast crisis or genetically distinct neoplasm. Leukemia(2000) 14, 169-182.

Immunoelectron microscopic localization of aromatase in human placenta and ovary using microwave fixation.

In this study we investigated the immunohistochemical localization of a unique aromatase, a single protein of 51,000 daltons, in the human placenta and ovary at light and electron microscopic levels. Microwave fixation was adopted for the immunoelectron microscopic study because it is an excellent method for preserving antigenicity and subcellular structures in frozen sections. Tissue samples from four immature human placentas, four full-term human placentas, and two human ovaries fixed in 10% formalin were examined by light microscopy. In addition, tissues from three full-term human placentas and one immature human placenta fixed in 4% paraformaldehyde were examined by electron microscopy. By light microscopy, immunoreactivity for this aromatase was located in the syncytiotrophoblast and a part of the cytotrophoblast of the placenta and in the lutein and granulosa cells of the ovary. Immunoelectron microscopy revealed that the aromatase antigen was localized on the surface of the microvilli, the lateral plasma membrane, and in the endoplasmic reticulum (ER) in the syncytiotrophoblast of the placenta. The positive immunoreactivity in the syncytiotrophoblast ER is consistent with previous results using antibodies for other types of aromatase, whereas the reactivity on the microvilli has not been previously described. The present report describes the fine localization of this unique aromatase in placental and ovarian tissues; its localization on the plasma membranes requires further physiological investigation.

Atrioventricular groove patch plasty for anatomically corrected malposition of the great arteries.

OBJECTIVE: In anatomically corrected malposition of the great arteries, dextroposition of the posterior pulmonary artery and levoposition of the anterior aorta are associated with the leftward deviation of the proximal portion of the right coronary artery away from the right atrioventricular groove. This anatomic feature allows a transannular subpulmonary patch plasty of the right ventricular outflow tract along the right atrioventricular groove between the right coronary artery and the tricuspid anterior anulus (ie, atrioventricular groove patch plasty) for relief of subpulmonary stenosis without jeopardizing the right coronary artery. METHODS: This report describes the midterm results of a new surgical technique, atrioventricular groove patch plasty with a monocuspid transannular patch for subpulmonary stenosis, in 3 patients with anatomically corrected malposition of the great arteries, along with a concomitant closure of ventricular septal defects. RESULTS: Postoperative catheterization revealed adequate relief of pulmonary stenosis, with a pressure gradient of 8.0 +/- 3.5 mm Hg and with normalized right ventricular pressure (33 +/- 10 mm Hg), contributing to excellent midterm results with no late death and reoperation during a postoperative follow-up period of 70 +/- 47 months. CONCLUSION: This technique provides a promising alternative to Rastelli-type conduit repair for subpulmonary stenosis in anatomically corrected malposition of the great arteries.

Trandolaprilat, an angiotensin-converting enzyme inhibitor, is not excreted in bile via an ATP-dependent active transporter (cMOAT).

Trandolapril is the prodrug of an angiotensin-converting enzyme (ACE) inhibitor. It has been proposed that its active metabolite, trandolaprilat, is mainly excreted in bile, but this has not been clearly demonstrated. Recently it has been reported that temocaprilat, an active metabolite of the ACE inhibitor temocapril, is effectively excreted in bile via an ATP-dependent active transporter (canalicular multispecific organic anion transporter: cMOAT). To investigate whether trandolaprilat has the pharmacological ability to affect the cMOAT system in a manner similar to temocaprilat. The lipophilicity of trandolaprilat and temocaprilat was measured to determine the n-octanol-water partition coefficients. The dose-dependent inhibition of the up-take of [3H]-estradiol-17beta-D-glucuronide and [3H]-2,4-dinitrophenyl-S-glutathione, which are good substrates for cMOAT, in canalicular membrane vesicles (CMVs) prepared from Sprague-Dawley rats was determined in the presence of trandolaprilat and temocaprilat. The partition coefficient of trandolaprilat (log Po/w - 1.1) was about 30 times higher than that of temocaprilat (log Po/w - 2.5). The uptake of [3H]-estradiol-17beta-D-glucuronide and [3H]-2,4-dinitrophenyl-S-glutathione was dose-dependently inhibited by the presence of temocaprilat, but trandolaprilat had no effect on the transport of [3H]-estradiol-17beta-D-glucuronide or [3H]-2,4-dinitrophenyl-S-glutathione into CMVs even at concentrations as high as 200 microM. It could be concluded that trandolaprilat has a higher lipophilicity than temocaprilat. But the hepatobiliary excretion system via cMOAT may not contribute to the excretion of trandolaprilat in bile.

Antiplatelet and antithrombotic effects of orbofiban, a new orally active GPIIb/IIIa antagonist, in guinea pigs.

Antiplatelet and antithrombotic effects of orbofiban, a new orally active glycoprotein IIb/IIIa antagonist, were evaluated in guinea pigs. SC-57101A (0.03-1 microM), the hydrochloride salt of the active form of orbofiban, inhibited in vitro ADP- and collagen-induced platelet aggregation in a concentration-dependent manner. Oral administration of orbofiban (3-30 mg/kg) resulted in dose-dependent inhibition of ADP- and collagen-induced platelet aggregation. The inhibition peaked at 1-2 hours postdose and then declined slowly. The agent also showed similar inhibition of platelet aggregation in guinea pigs with dietary-induced hypercholesterolemia. In contrast, the antiaggregatory effects of acetylsalicylic acid differed more widely between normal and hyperlipidemic animals compared to those of orbofiban. Plasma concentration of the active form, measured by a column-switching HPLC method, correlated well with the inhibition of platelet aggregation. Orbofiban (3-100 mg/kg, p.o.) caused dose-dependent inhibition of thrombus formation in an arteriovenous-shunt-thrombosis model. Orbofiban at high doses (> or =30 mg/kg) and acetylsalicylic acid (100 mg/kg) both prolonged cutaneous bleeding time measured by the template method. These results demonstrate that orbofiban is an orally active and potent inhibitor of platelet aggregation with an efficacy that correlates well with the plasma concentration of its active form.

Enhancing effect of electric stimulation on cytotoxicity of anticancer agents against rat and human glioma cells.

Electropermeabilization, or electroporation, has been used to deliver genes or drugs into the cytoplasm through micropores in the cell membrane caused by electric stimulation. The cytotoxic effect of a combination of anticancer agents with electric stimulation on rat C6 and human T98G glioma cells was examined in vitro. Electric pulses of 100 microsec square waves (eight cycles at 1 Hz) at various electric fields were delivered to C6 or T98G glioma cell suspensions in combination with several anticancer agents. Cell growth was evaluated 48-72 h after treatment. Measurement of cell lysis by electric stimulation was used to assess the optimum field strength for electroporation. Electric stimulation enhanced significantly the cytotoxicity of bleomycin to both C6 and T98G cells by more than 1000-fold using an electric field of 1750 V/cm for C6 cells and 1000 V/cm for T98G cells. The enhancement disappeared when bleomycin concentration was reduced to 100 pg/ml. The cytotoxicity of carboplatin was weakly but significantly enhanced by electric stimulation when a high dose of carboplatin was used. However, there was no enhancement of the cytotoxicity of nimustine hydrochloride (ACNU), etoposide, and vincristine. These results indicate that the combination of bleomycin and electroporation is the most potent candidate for electrochemotherapy in vivo.

Spontaneous resolution of chronic subdural hematomas.

Four patients with chronic subdural hematomas, all of which resolved spontaneously, were followed from the time of injury to resolution of the chronic subdural hematoma. Periodic computed tomographic (CT) scans showed spontaneous resolution 78, 174, 231, and 326 days after the development of the chronic subdural hematoma, respectively. Features of the CT scans and a possible mechanism of spontaneous resolution are discussed.

Antiproliferative cytokines secreted by lymphokine-activated killer cells stimulated with tumor cells.

Antiproliferative cytokine secretion by lymphokine-activated killer (LAK) cells during coculture with glioblastoma cell lines, autologous glioma cells, and nongliomatous tumor cell lines (Daudi and K562 cells) was assessed, as was the antiproliferative activity of the culture supernatants against the T98G (glioblastoma) cell line. A neutralization test using agents against interferon-gamma (IFN-gamma), tumor necrosis factor (TNF), and lymphotoxin (LT) showed that antiproliferative activity was due to IFN-gamma, but not to TNF or LT. Nongliomatous tumor cells stimulated LAK cells to secrete cytokines, but gliomatous tumor cells did not. It was found that there is a discrepancy between the LAK cell capability to lyse malignant glioma cells and the ability to secrete cytokines. This may be due to the factors secreted by glioblastoma cells.

Localization of carcinoembryonic antigen in mature intracranial teratomas.

Carcinoembryonic antigen (CEA) in serum and cerebrospinal fluid (CSF) was measured in four patients with intracranial teratoma. The CEA levels were elevated in the CSF of two patients, but were within normal limits in the serum of all four. After surgical removal of the teratomas, which were verified as mature teratomas, CEA was localized by an immunohistochemical method. Positive reactions both to anti-CEA serum and to another anti-CEA serum absorbed with nonspecific cross-reacting antigen were seen in glandular structures, with or without goblet cells, and in some portions of stratified squamous epithelium. It is concluded that CEA, detected in CSF, may originate in mature teratomas, and CEA-positive structures (especially glandular) may differentiate into gastrointestinal tract structures. An examination of serum and CSF levels of CEA may offer additional clues to the diagnosis of intracranial germ-cell tumors.

Intracranial germ-cell tumors. Immunohistochemical study of three autopsy cases.

Histological and immunohistochemical findings in three cases with primary intracranial germ-cell tumors are reported. Based on histological examination, they were diagnosed, respectively, as an endodermal sinus tumor with immature teratoid differentiation, teratoma and embryonal carcinoma, and choriocarcinoma and germinoma. The first case was presumed to be a combination of endodermal sinus tumor and germinoma. An immunohistochemical examination showed positive reactions to alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA) in the endodermal sinus tumor, and to human chorionic gonadotropin (HCG) in the choriocarcinoma, but showed no reaction in the embryonal carcinoma. Human chorionic gonadotropin was demonstrated in syncytiotrophoblastic cells and CEA in a gland-like structure. The value of measuring CEA in cases of germ-cell tumors, in addition to AFP and HCG assays, is stressed, and the characteristics of CEA-positive tissue are discussed.

Resistance to growth inhibition by transforming growth factor-beta in malignant glioma cells with functional receptors.

OBJECT: The aim of this study was to investigate the mechanism by which malignant glioma cells escape from growth inhibition mediated by transforming growth factor-beta (TGF-beta), a ubiquitous cytokine that inhibits cell proliferation by causing growth arrest in the G1 phase of the cell cycle. METHODS: The authors measured the response of eight malignant glioma cell lines to the growth-inhibiting activity of TGF-beta in vitro and the expression of TGF-beta Types I and II receptors in malignant glioma cells. The effect of TGF-beta on the expression of a p27Kip1 cyclin-dependent kinase inhibitor was also investigated to assess the downstream signal transmission from TGF-beta receptors. All malignant glioma cell lines were insensitive to growth inhibition by TGF-beta1 and TGF-beta2. Analyses of TGF-beta receptors by means of affinity labeling in which 125I-TGF-beta1 was used showed that six glioma lines had both TGF-beta Types I and II receptors on their cell surfaces, whereas two lines had very small amounts of TGF-beta Type I and/or Type II receptors. Northern blot analysis showed that all tumor lines expressed variable levels of messenger RNAs for both TGF-beta Types I and II receptors. Flow cytometric analyses revealed that treatment of malignant glioma cells with TGF-beta1 significantly downregulated the expression of p27Kip1 protein in all malignant glioma cell lines except one. CONCLUSIONS: The authors suggest that most malignant glioma cells express TGF-beta Types I and II receptors, which can transmit some signals downstream and that the loss of response to TGF-beta growth inhibition may not be caused by an abnormality of the TGF-beta receptors.