Bending property and phase transformation of Ti–Ni–Cu alloy dental castings for orthodontic application

Bending property of Ti–Ni–Cu alloy castings was investigated in a three-point bending test for orthodontic application in relation to the phase transformation. The compositions of the alloys were Ti–50.8Ni and Ti–40.8Ni–10.0Cu (mol %), and four cross-sectional shapes of the specimens were selected. Heat treatment was performed at 713, 753 or 793 K for 1.8 ks. The bending load changed by the cross-sectional size and shape mainly because of the difference in the moment of inertia of area, but the load–deflection relation did not differ proportionally in the unloading process. The difference between the load values in the loading and the unloading processes was relatively small for Ti–Ni–Cu alloy. With respect to the residual deflection, there was no significant difference between Ti–Ni and Ti–Ni–Cu alloys with the same treatment condition. The load values in the loading and the unloading processes decreased by each heat treatment for Ti–Ni alloy; however, the decrease in the load values for Ti–Ni–Cu alloy was not distinct. It is proved that Ti–Ni–Cu alloy castings produce effective orthodontic force as well as stable low residual deflection, which is likely to be caused by the high and sharp thermal peaks during phase transformation.     

Far-infrared laser oscillation due to cyclotron emission in p-type germanium

Far-infrared laser oscillation due to cyclotron emission in the light hole band of p-type germanium was observed under crossed electric and magnetic fields. The wavelength is inversely proportional to magnetic fields with a cyclotron mass ofm _c =0.048m _c . Numerical calculations based on Luttinger Hamiltonian show that mixing of wavefunctions between the light and heavy hole bands causes population inversion betweenn=0 andn=1 light-hole Landau levels. It is also shown that non-equidistant energy spacing of light-hole Landau levels is essential to yield net amplification.     

Requirement for activation of the serine-threonine kinase Akt (protein kinase B) in insulin stimulation of protein synthesis but not of glucose transport

A wide variety of biological activities including the major metabolic actions of insulin is regulated by phosphatidylinositol (PI) 3-kinase. However, the downstream effectors of the various signaling pathways that emanate from PI 3-kinase remain unclear. Akt (protein kinase B), a serine-threonine kinase with a pleckstrin homology domain, is thought to be one such downstream effector. A mutant Akt (Akt-AA) in which the phosphorylation sites (Thr308 and Ser473) targeted by growth factors are replaced by alanine has now been shown to lack protein kinase activity and, when overexpressed in CHO cells or 3T3-L1 adipocytes with the use of an adenovirus vector, to inhibit insulin-induced activation of endogenous Akt. Akt-AA thus acts in a dominant negative manner in intact cells. Insulin-stimulated protein synthesis, which is sensitive to wortmannin, a pharmacological inhibitor of PI 3-kinase, was abolished by overexpression of Akt-AA without an effect on amino acid transport into the cells, suggesting that Akt is required for insulin-stimulated protein synthesis. Insulin activation of p70 S6 kinase was inhibited by approximately 75% in CHO cells and approximately 30% in 3T3-L1 adipocytes, whereas insulin-induced activation of endogenous Akt was inhibited by 80 to 95%, by expression of Akt-AA. Thus, Akt activity appears to be required, at least in part, for insulin stimulation of p70 S6 kinase. However, insulin-stimulated glucose uptake in both CHO cells and 3T3-L1 adipocytes was not affected by overexpression of Akt-AA, suggesting that Akt is not required for this effect of insulin. These data indicate that Akt acts as a downstream effector in some, but not all, of the signaling pathways downstream of PI 3-kinase.     

A robust increase in expression of arc gene, an effector immediate early gene, in the rat brain after acute and chronic methamphetamine administration

The effect of acute and chronic administration of methamphetamine (METH) on the levels of activity-regulated cytoskeleton-associated protein (arc), an effector-immediate early gene, mRNA has been investigated in rat brain using in situ hybridization. Levels of arc mRNAs in the brain regions examined increased significantly from 0.5-1 h after an acute METH (4 mg/kg) administration compared with basal levels. The increase in arc mRNA continued by 3 h, and then subsided to basal levels by 6 h. The degree of increase in arc mRNA and the peak time after METH administration varied according to brain area. Arc mRNA in cerebral cortices showed robust increase 1 h after METH administration. In the striatum and hippocampus, it showed earlier and later increase, respectively, and its degree of both was less than in the cortices. Microscopic examination revealed that the METH-induced arc mRNAs in the parietal cortex were enriched in layers IV and VI, and those in the striatum existed mainly in the medium-sized neuron. Pretreatment with either 0.5 mg/kg SCH23390 or 0.25 mg/kg MK-801 almost completely blocked the enhanced striatal arc mRNA levels induced by acute METH administration, whereas such pretreatments only partially reduced the effect of METH in the cerebral cortical regions. In the chronic treatment experiment, the arc mRNA levels of the group that received chronic treatment with METH followed by a METH challenge showed an increase like seen after acute METH administration. Since previous studies proposed that arc is one of cytoskeleton-associated proteins and is selectively localized in neural dendrites, the results of the present study suggested that arc may play an important role in the synaptic plasticity underlying METH-induced adaptational changes including behavioral sensitization.     

Efficacy of dose-intensified MEC (methotrexate, epirubicin and cisplatin) chemotherapy for advanced urothelial carcinoma: a prospective randomized trial comparing MEC and M-VAC (methotrexate, vinblastine, doxorubicin and cisplatin). Japanese Urothelial Cancer Research Group

BACKGROUND: To evaluate the antitumor activity in patients with T3b, T4 or metastatic urothelial carcinoma treated with MEC or M-VAC chemotherapy, by performing a multi-center randomized prospective study. METHODS: From 1991 to 1995, 89 patients with T3b, T4 or metastatic urothelial carcinoma were randomly allocated to a methotrexate, epirubicin and cisplatin chemotherapy group (arm 1: S-MEC therapy; n = 29), a dose-intensified MEC therapy combined with G-CSF group (arm 2: I-MEC therapy; n = 30) or a methotrexate, vinblastine, doxorubicin and cisplatin chemotherapy (arm 3: M-VAC therapy; n = 30). At the registration center, the patients were stratified into previously untreated patients and patients with recurrence after radical operation and then randomly allocated to the treatment groups. In each arm, two or more courses of chemotherapy (4-week cycles) were performed. RESULTS: Of the 88 eligible patients, four treated with S-MEC therapy and two treated with I-MEC therapy showed CR. The response rates (CR + PR) were 52% (15/29) with S-MEC therapy, 76% (22/29) with I-MEC therapy and 47% (14/30) with M-VAC therapy. The response rate with I-MEC therapy was significantly higher than that with M-VAC therapy (P = 0.02). Although the incidence of leukopenia was low with I-MEC therapy, the incidence of thrombocytopenia was high with this therapy. CONCLUSION: MEC therapy used in this study is promising in terms of the antitumor effects.     

Axisymmetric elastodynamic response of a flat annular crack to normal impact waves

The axisymmetric response of a flat annular crack in an infinite medium subjected to normal impact load is investigated in this study. A step stress is applied to the crack surface. The singular solution is equivalent to solutions of the problem of diffraction of normally incident tension wave by a flat annular crack, and the problem of the sudden appearance of a flat annular crack in a uniform tensile stress field. Laplace and Hankel transforms are used to reduce the problem to the solution of a set of triple integral equations in the Laplace transform domain. These equations are solved by using a integral transform technique and the result is expressed in terms of a singular integral equation of the first kind with the kernel which is improved by means of a contour integration on the Riemann surface. A numerical Laplace inversion routine is used to recover the time dependence of the solution. Numerical results of the dynamic stress intensity factor are obtained to show the influence of inertia, the ratio of the inner radius to the outer one and Poisson's ratio on the load transmission to the crack tip.     

Recombinant modified vaccinia virus Ankara-simian immunodeficiency virus gag pol elicits cytotoxic T lymphocytes in rhesus monkeys detected by a major histocompatibility complex class I/peptide tetramer

The utility of modified vaccinia virus Ankara (MVA) as a vector for eliciting AIDS virus-specific cytotoxic T lymphocytes (CTL) was explored in the simian immunodeficiency virus (SIV)/rhesus monkey model. After two intramuscular immunizations with recombinant MVA-SIVSM gag pol, the monkeys developed a Gag epitope-specific CTL response readily detected in peripheral blood lymphocytes by using a functional killing assay. Moreover, those immunizations also elicited a population of CD8+ T lymphocytes in the peripheral blood that bound a specific major histocompatibility complex class I/peptide tetramer. These Gag epitope-specific CD8+ T lymphocytes also were demonstrated by using both functional and tetramer-binding assays in lymph nodes of the immunized monkeys. These observations suggest that MVA may prove a useful vector for an HIV-1 vaccine. They also suggest that tetramer staining may be a useful technology for monitoring CTL generation in vaccine trials in nonhuman primates and in humans.     

Modification of parallel activity elicited by propagating bursts in developing networks of rat cortical neurones

The fine specificity of the cellular immune response to Candida albicans (i.e., recognition of different antigenic components) between normal controls and human immunodeficiency virus-infected patients in various stages of disease was compared. C. albicans-specific T cells, enriched by antigen stimulation and interleukin-2 expansion, were challenged with antigenic fractions of different molecular weight obtained by SDS-gel fractionation of C. albicans extracts in the presence of autologous mononuclear cells as antigen-presenting cells. Proliferative responses showed similar patterns of reactivity between controls and category A and B seropositive subjects. Category C patients with concurrent C. albicans infections did not give rise to C. albicans-specific T cell lines, confirming the T cell defect. Patients without clinically evident C. albicans infection had a low but broad reactivity pattern of C. albicans-specific T cells. These results suggest that depletion of C. albicans-specific T cells, independent of their fine specificity, occurs along with disease progression.     

Synthesis of polyorganosiloxane retaining SiO4 framework from inosilicate mineral by trimethylsilylation

A polyorganosiloxane retaining a SiO₄ tetrahedral framework has been synthesized by the reaction of an inosilicate mineral (para-wollastonite) with a trimethylsilylating reagent. The glassy product dissolved in a wide range of organic solvents but was insoluble in water. The analyses of the product by means of infra-red spectroscopy, X-ray powder diffraction and elemental analysis indicated that trimethylsilyl side groups were linked to the SiO₄ framework. The thermal stability of the product was determined by thermal analysis.