Thiol-mediated redox regulation of apoptosis. Possible roles of cellular thiols other than glutathione in T cell apoptosis

Thiol redox status modulates various aspects of cellular function. We demonstrate that oxidation of cellular sulfhydryl (SH) groups induces apoptosis. In Jurkat T cells and human PBL blasts, the fraction of apoptotic nuclei increased after treatment with an SH-specific oxidant, diamide. Analysis of DNA fragmentation and nuclear morphology also indicated that SH oxidation could induce apoptosis. In the apoptosis induced by SH oxidation, the decrease of cellular glutathione was transient and the increase of glutathione disulfide was observed only after apoptotic changes had occurred. Depletion of cellular glutathione with buthionine sulfoximine failed to induce apoptosis, despite a marked decrease of cellular glutathione, which was greater than that observed in apoptosis induced by diamide. Thus, the changes of cellular glutathione or glutathione disulfide may not be the major cause of apoptosis induced by diamide. Intracellular adult T cell leukemia-derived factor/human thioredoxin, another thiol-related antioxidant protein, was oxidized by incubation with diamide. These results suggest that thiol redox status is one of the key factors of the apoptotic pathway in which thiols other than glutathione may play even more critical roles.     

STOICHIOMETRIC RELATIONS OF CHEMICAL OSCILLATION SYSTEMS AND STOICHIOMETRIC NUMBER THEORY

The stoichiometry of chemical oscillation systems, especially that of the Oregonator proposed by Field and Noyes (1974), is discussed with use of the generalized stoichiometric number theory by Horiuti and Nakamura (1957). The independent stoichiometric equations derived by Noyes (1976) are shown to correspond to Horiuti and Nakamura's reaction routes, each of which was expressed in terms of a set of stoichiometric numbers. It is found that the relations derived by Noyes are partly incorrect.     

Alpha 2-macroglobulin of rabbits inhibits the habutobin activity

We have investigated whether alpha 2-macroglobulin (alpha 2M) of rabbits inhibits the activity of habutobin, a thrombin-like enzyme from Trimeresurus flavoviridis venom. Rabbit alpha 2M was purified with ultracentrifugation, gel filtration on Sepharose 6B and ion exchange chromatography on DEAE-Sephacel. Inhibitory effects of rabbit alpha 2M on habutobin was determined by the fibrin forming activity, digestion of A alpha chain of fibrinogen, and the release of fibrinopeptide A from fibrinogen. As a results, purified alpha 2M showed a single band with high molecular weight, around 800,000 mol. wt by means of polyacrylamide gel electrophoresis using PhastSystem. Besides inhibiting amidolytic and caseinolytic activity of porcine trypsin, it has inhibited the activity of habutobin: that is, in the presence of rabbit alpha 2M, fibrin forming activity of habutobin was decreased and habutobin-induced digestion of A alpha chain was inhibited. In addition, rabbit alpha 2M reduced habutobin-induced release of fibrinopeptide A from rabbit fibrinogen.     

Two types of multi-moderator neutron spectrometers: Gamma-ray insensitive type and high-efficiency type

Two types of multi-moderator neutron spectrometers were developed; one is a gamma-ray insensitive type, and the other is a high-efficiency type. An indium activation detector is loaded in the former spectrometer, which can measure the photon-dominant pulsed neutron field such as in the primary photon beam of a high-energy medical electron accelerator. The latter, in which a ³He counter is loaded, is so sensitive that it can measure leakage neutrons from a well shielded facility or even the skyshine neutrons. The response functions of the spectrometers were measured by thermal and mono-energetic neutron standard fields, and were also calculated by the one-dimensional discrete ordinates transport code, ANISN. The measured and calculated responses showed generally good agreement. A benchmark measurement of ²⁵²Cf fission neutrons by using these two spectrometers agreed well with the calculated spectrum. The spectrometers were used in the measurements of neutrons produced by a medical electron accelerator and of skyshine neutrons from an intense 14 MeV neutron source facility.     

Characterization of aluminium nitride thin films

Aluminium nitride (AlN) thin films have been synthesized by evaporation of aluminium and simultaneous irradiation with nitrogen ions, ion-vapour deposition method, at the substrate temperature of room temperature or 473K. The kinetic energy of the incident nitrogen ion beam has been kept at 0.5 keV and the deposition rate has been varied from 0.075 to 0.28 nm/s. The structure of the synthesized films has been examined by X-ray diffraction (XRD) and the surface morphology has been characterized by atomic force microscopy (AFM). In the XRD patterns of both films synthesized at room temperature and 473K, the diffraction lines due to the AlN(10.0), (00.2) and (10.1) planes have been discerned. AFM observations reveal that the surface of the films synthesized at 473K becomes rough as compared with the films synthesized at room temperature. This may be attributed to growth of AlN particles on the substrate kept at 473K. Furthermore, in the films synthesized at the 473K substrate, several aggregated protrusions can be observed on the relatively smooth surface at the deposition rate of 0.28 nm/s, while the surface of the films is uniform on nanometre scale at the deposition rate of less than 0.12 nm/s. The present results suggest that the synthesis of the AlN films with uniform surface is feasible by controlling the substrate temperature and the deposition rate.     

Observation of the coherence peak of H-NMR-NMR relaxation rate in the superconducting state of (MDT-TTF)2Aul2

We have investigated the superconductivity in the organic conductor, (MDT-TTF)₂Aul₂ (T_c = 4.1 K) from the temperature dependence of H¹ nuclear relaxation rate, 1/T₁, measured by the field cycling method. The nuclear relaxation above 3 K is well characterized by a single relaxation time for nearly two decades. In the normal state, the standard Korringa relation holds. 1/T₁ just below T_c showed a clear enhancement, followed by a falling-oil at lower temperatures. This behavior is just as predicted in the BCS theory (coherence peak) and implies that this material is a conventional superconductor with an isotropic gap. The decay of the nuclear magnetization below 3 K appeared non-sinle exponential. This is explained as the effect of trapped vortices.     

Analysis on heterogeneity of squamous cell carcinoma antigen by two-dimensional electrophoresis

Squamous cell carcinoma (SCC) antigen was separated by two-dimensional electrophoresis combined with immunoblotting into four spots: spot 1 with pI 6.4 and 44.5 kDa, spot 2 with pI 6.3 and 44.5 kDa, spot 3 with pI 6.0 and 44.5 kDa, and spot 4 with pI 5.9 and 45 kDa. In cancer and noncancerous tissues, it was common that spot 1 was the largest spot. In noncancerous tissues, spot 3 was the smallest spot and spot 2 was stained as densely as spot 4. In cancer tissues, however, spot 4 was apparently smaller than spot 2 and 3. Also, spots 2 and 3 in cancer tissues were larger than those in noncancerous tissues. When SCC antigen was treated with alkaline phosphatase prior to isoelectric focusing (IEF), spot 4 disappeared from the immunoblotting pattern. When the SCC antigen was treated with alkaline phosphatase after IEF, spot 4 changed its molecular weight to the same weight as that of the other three spots. These results strongly suggest that spot 4 is phosphorylated SCC antigen.     

Malignant histiocytosis-like B-cell lymphoma, a distinct pathologic variant of intravascular lymphomatosis: a report of five cases and review of the literature

Malignant histiocytosis (MH)-like B-cell lymphoma (BCL) is a neoplastic proliferation of large B cells clinically characterized by fever, hepatosplenomegaly, haemophagocytosis and abnormal laboratory data, without lymphadenopathy or skin lesions. Interestingly, most cases have been reported in Asian patients, and it is unclear whether MH-like BCL is biologically distinct from conventional large B-cell lymphomas. We report five Japanese patients with MH-like BCL. Biopsied specimens of bone marrow, liver and/or spleen showed infiltration of neoplastic B cells accompanied by haemophagocytosing histiocytes. Lymphoma cells were positive for CD19, CD20 and HLA-DR surface antigens, and negative for CD5 and CD10. In four cases elevated serum levels of interleukin (IL)-6 and the soluble IL-2 receptor isoform were noted, but not IL-1beta, IL-2 or tumour necrosis factor-alpha. Autopsies of two cases were pathologically diagnosed as intravascular lymphomatosis (IVL). Based on these observations, the current and nine previous cases reported as MH-like BCL in Japan were re-evaluated. They appear to form a peculiar variant of IVL, characterized by bone marrow involvement at presentation, haemophagocytic syndrome, and a rapidly aggressive clinical course, but rarely neurological complications or skin lesions. This variant may merit separate consideration because of the problems posed in the initial diagnosis and therapeutic approaches.     

Construction of a BAC library of the rice blast fungus Magnaporthe grisea and finding specific genome regions in which its transposons tend to cluster

We have constructed a BAC library of the rice blast fungus Magnaporthe grisea consisting of 5760 clones. The insert size ranged from 35 to 175 kbp, with an average of 120 kbp. The library is about 18 genomes equivalent, therefore covering more than 99.999% of the genome. This library is the first to be constructed using a rice pathogenic wild type isolate. Improved high molecular weight DNA size fractionating helped to construct the library with high efficiency. Total library clones were arranged onto two nylon membranes for efficient screening. Test hybridization with a single-copy RFLP marker showed ten positive clones, of which restriction patterns indicated no chimerality or deletions. As a model case of application of this library, the distribution of the well-studied fungal retrotransposons MGSR1, MGR583, and MAGGY and DNA transposons MGR586 and Pot2 was analyzed. Of all the BAC clones, 10%, 13%, 18%, 12%, and 23% contained MGSR1, MGR583, MAGGY, MGR586 and Pot2, respectively. The percentage of clones possessing more than five kinds of transposons was 1.4%, 215 times greater than the expected number. The results show that these transposons were distributed in clusters in the M. grisea genome.