Fabrication of a novel magnetic topological heterostructure and temperature evolution of its massive Dirac cone.

Materials that possess nontrivial topology and magnetism is known to exhibit exotic quantum phenomena such as the quantum anomalous Hall effect. Here, we fabricate a novel magnetic topological heterostructure Mn4Bi2Te7/Bi2Te3 where multiple magnetic layers are inserted into the topmost quintuple layer of the original topological insulator Bi2Te3. A massive Dirac cone (DC) with a gap of 40-75 meV at 16 K is observed. By tracing the temperature evolution, this gap is shown to gradually decrease with increasing temperature and a blunt transition from a massive to a massless DC occurs around 200-250 K. Structural analysis shows that the samples also contain MnBi2Te4/Bi2Te3. Magnetic measurements show that there are two distinct Mn components in the system that corresponds to the two heterostructures; MnBi2Te4/Bi2Te3 is paramagnetic at 6 K while Mn4Bi2Te7/Bi2Te3 is ferromagnetic with a negative hysteresis (critical temperature  ~20 K). This novel heterostructure is potentially important for future device applications.

Role of Quantum and Surface-State Effects in the Bulk Fermi-Level Position of Ultrathin Bi Films.

We performed high-resolution photon-energy and polarization-dependent ARPES measurements on ultrathin Bi(111) films [6-180 bilayers (BL), 2.5-70 nm thick] formed on Si(111). In addition to the extensively studied surface states (SSs), the edge of the bulk valence band was clearly measured by using S-polarized light. We found direct evidence that this valence band edge, which forms a hole pocket in the bulk Bi crystal, does not cross the Fermi level for the 180 BL thick film. This is consistent with the predicted semimetal-to-semiconductor transition due to the quantum-size effect [V.B. Sandomirskii, Sov. Phys. JETP 25, 101 (1967)]. However, it became metallic again when the film thickness was decreased (below 30 BL). A plausible explanation for this phenomenon is the modification of the charge neutrality condition due to the size effect of the SSs.

Hydrogen-induced surface metallization of SrTiO3(001).

Surface metallization of SrTiO3(001) by hydrogen adsorption is experimentally confirmed for the first time by photoemission spectroscopy and surface conductivity measurements. The metallic state is assigned to a quantized state in the space-charge layer induced by electron doping from hydrogen atoms. The measured two-dimensional (2D) conductivity is well above the 2D Ioffe-Regel limit indicating that the system is in a metallic conduction regime. The mean free path of the surface electron is estimated to be several nanometers at room temperature.

Long-term survival after liver transplantation in patients with familial amyloid polyneuropathy.

OBJECTIVE: Familial amyloid polyneuropathy (FAP), which is a fatal disorder inherited in an autosomal dominant fashion, is characterized by systemic accumulation of polymerized transthyretin (TTR) in the peripheral nerves and systemic organs. Liver transplantation has become an accepted treatment of this disorder because it stops the major production of amyloidogenic TTR. However, improved survival of transplant patients compared with that of nontransplant patients has not been sufficiently demonstrated. This study investigated whether transplantation improved the long-term outcome of patients by comparing the survival of patients who had transplantations with that of patients who had not had transplantations. METHODS: Eighty consecutive patients with FAP Val30Met who visited Kumamoto University Hospital between January 1990 and December 2010 were studied. The transplant group consisted of 37 patients who had a partial hepatic graft via living donor transplantation in Japan or who underwent liver transplantation in Sweden, Australia, or the United States. The nontransplant group consisted of 43 patients with FAP. Survival was evaluated by using Kaplan-Meier analysis, and the difference in survival was examined via the log-rank test. RESULTS: The transplant group had prolonged survival (p < 0.001) compared with the nontransplant group. The estimated probability of survival at 10 years was 56.1% for the nontransplant group vs 100% for the transplant group. CONCLUSION: Liver transplantation should be considered as an effective treatment in clinical management of patients with FAP Val30Met. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that liver transplantation prolongs survival in patients with FAP Val30Met.

Atomic and electronic structure of ultrathin Bi(111) films grown on Bi2Te3(111) substrates: evidence for a strain-induced topological phase transition.

We studied the atomic and electronic structures of ultrathin Bi(111) films grown on Bi(2)Te(3) by means of angle-resolved photoemission, first-principles calculations, and low-energy electron diffraction. These Bi films were found to be strained due to the influence of the substrate. Accordingly, the band structure is affected and Bi undergoes a topological phase transition; it is shown that the Z(2) topological invariant in three dimensions switches from +1 (trivial) to -1 (nontrivial or topological). This was clearly confirmed from the change in the surface-state dispersion near the Fermi level. Our discovery offers a method to produce novel topological systems from simple materials.

Effect of liver transplantation on transthyretin Tyr114Cys-related cerebral amyloid angiopathy.

OBJECTIVE: Patients with amyloidogenic transthyretin (ATTR) Tyr114Cys develop amyloid deposits in cerebral blood vessels, cerebral hemorrhage, and rapidly progressive dementia that presents with hereditary cerebral amyloid angiopathy (CAA). However, no treatment has been identified for CAA. Although liver transplantation has become an acceptable treatment of TTR-related amyloidosis, liver transplantation may not successfully treat CNS manifestations of the disorder. In this study, we examined the effect of liver transplantation on these manifestations of TTR-related CAA. METHODS: We compared clinical courses of three patients with CAA associated with ATTR Tyr114Cys who underwent liver transplantation with those of five patients with the disorder who did not undergo liver transplantation. RESULTS: The mortality and occurrence of cerebral hemorrhage and dementia in patients having transplantations were reduced compared with those in patients not having transplantations. The two groups did not differ with regard to the frequency of episodes of fluctuating consciousness and TIAs. The group undergoing transplantations had significantly smaller volumes of intracranial hemorrhage than did the no-transplantation group. CONCLUSION: Liver transplantation was effective for CNS manifestations of cerebral amyloid angiopathy associated with amyloidogenic transthyretin Tyr114Cys.

Role of spin-orbit coupling and hybridization effects in the electronic structure of ultrathin Bi films.

The electronic structure of Bi(001) ultrathin films (thickness > or =7 bilayers) on Si(111)-7x7 was studied by angle-resolved photoemission spectroscopy and first-principles calculations. In contrast with the semimetallic nature of bulk Bi, both the experiment and theory demonstrate the metallic character of the films with the Fermi surface formed by spin-orbit-split surface states (SSs) showing little thickness dependence. Below the Fermi level, we clearly detected quantum well states (QWSs) at the M point, which were surprisingly found to be non-spin-orbit split; the films are "electronically symmetric" despite the obvious structural nonequivalence of the top and bottom interfaces. We found that the SSs hybridize with the QWSs near M and lose their spin-orbit-split character.

Protective effects of clostridium sordellii LT and HT toxoids against challenge with spores in guinea pigs.

The protective effects of Clostridium sordellii lethal toxin (LT) and hemorrhagic toxin (HT) toxoids against challenge with spores in guinea pigs were investigated. Purified LT and partially purified HT were obtained from the culture supernatant of C. sordellii strain 3703, and then were treated with formalin to make toxoids. LT. HT and combined LT and HT (LT/HT) toxoid vaccines were prepared by mixing each toxoid with an aluminum phosphate gel as adjuvant. Guinea pigs immunized twice with the respective toxoid vaccines were challenged with spores of strains 3703 or KZ1047. The latter strain does not produce HT. LT toxoid vaccine conferred protection against challenge with strain KZ1047, but not strain 3703, in guinea pigs. All guinea pigs immunized with HT toxoid vaccine died after challenge with spores of either strain. LT/HT toxoid vaccine gave complete protection against challenge with spores of strains 3703 and KZ1047 to guinea pigs. These results suggest that not only LT toxoid, but also HT toxoid, are essential protective antigens of C. sordellii.

A mainstay of functional food science in Japan--history, present status, and future outlook.

The development of food science in the near future probably depends on the advance in functional food science, the concept of which was proposed first in Japan nearly 15 years ago. The new science has been internationally distributed and accepted as conceptually being beyond nutrition. In Japan, however, it traced a unique path of progress in the form of a product-driven rather than concept-driven science. Actually, a number of substances and products with potential for disease risk reduction rather than simply for health maintenance have been investigated for their body-modulating functions. Some of them have been applied in practice to the industrialization of functional foods in terms of "foods for specified health uses" legally defined by new legislation. A variety of sophisticated methods have been introduced as well, including the so-called "XYZ" evaluation system, database construction for assessment of the function, and even the DNA microarray technique. The Ministry of Agriculture, Forestry, and Fisheries (MAFF) and the Ministry of Health and Welfare (MHW) also commenced their scientific as well as political activity, with its spread to industries which almost simultaneously began to vigorously investigate functional food products for enlargement of the food market. With all of this as a background, the Japan Liaison of the International Union of Food Science and Technology (IUFoST) hold a function food science symposium on behalf of related scientific bodies including the Japan Section of the International Life Science Institute (ILSI). This paper is an overview compiled from 12 presentations made in the symposium, with the aim of internationally publicizing the activity of functional food science in Japan.

A novel enzyme, L-tryptophan oxidase, from a basidiomycete, Coprinus sp. SF-1: purification and characterization.

A basidiomycete, Coprinus sp. SF-1, was found to produce an L-Trp-oxidizing enzyme by screening from the culture collection of our laboratory. After solubilization by 1 M NaSCN from the particulate fraction of disrupted cells of the strain, the enzyme was purified about 76-fold to essential homogeneity. The enzyme had a molecular mass of about 420 kDa and the subunit molecular mass was 68 kDa. The enzyme contained 1 mol of non-covalently bound FAD per mol of the subunit. It catalyzed the simultaneous reactions of oxidative deamination and oxygenative decarboxylation of L-Trp to form indolepyruvic acid and indole-3-acetamide, the former of which was further oxidized to indole-3-acetic acid. The molar ratio of the respective reaction products was about 9:1. The enzyme specifically oxidized L-Trp, and slightly acted on L-Phe and L-Tyr. The Km for L-Trp was about 0.5 mM in both oxidase and oxygenase reactions. Thus, the enzyme is a novel one and was tentatively designated "L-Trp oxidase (deaminating and decarboxylating)". The optimum pHs of oxidase and oxygenase activities were 7.0 and 9.0, respectively. The optimum temperatures of both activities were 50 degrees C. The enzyme was stable at pH 6.0-10.5 and below 50 degrees C, and at 4 degrees C for 1 year.

Protection studies on winter dysentery caused by bovine coronavirus in cattle using antigens prepared from infected cell lysates.

Cells infected with bovine coronavirus (BCV) were solubilized with Triton X-100 to yield a cell lysate (CL) antigen having high hemagglutinating (HA) titers. The antigen gave high HA titers using rat erythrocytes, suggesting that it contained large amounts of hemagglutinin esterase (HE) antigen. The CL antigen, combined with an oil adjuvant, was tested for protective and antibody-inducing activities in cattle. Four groups (2 cattle/group) of cattle were inoculated with CL antigen having HA titers of 16 000, 4000, 1000, and 250. Another group served as untreated controls. Two intramuscular inoculations were given at an interval of 3 wk. The animals were challenged with virus 1 wk after the second inoculation. The groups immunized with the CL antigen having an HA titer of 4000 or 16 000 produced hemagglutination inhibition (HI) antibody titers of > 320 and serum neutralizing (SN) antibody titers of > 1280. These groups of animals showed no clinical abnormalities after challenge. In the groups immunized with CL antigen at an HA titer of 1000 or 250, HI antibody titers were 40 to 160 and SN titers were 80 to 640. The cattle with HI antibody titers of > or = 160 and the SN titers of > or = 640 showed no clinical signs, but the cattle with the HI antibody titer < 80 and the SN antibody titer < 160 developed watery diarrhea and fever after challenge. These results indicate that CL antigen with high HA titer induces antibody production in cattle that provides effective protection against winter dysentery.

On-line measurement of intracellular ATP of Saccharomyces cerevisiae and pyruvate during sake mashing.

The concentrations of intracellular ATP of Saccharomyces cerevisiae and pyruvate in a medium were instantaneously increased by pulse addition of glucose during starvation. They were reduced rapidly by alcohol fortification of the medium, accompanied by simultaneous increases of acetaldehyde concentration and inviability of yeast cells. These results were monitored during fermentation of sake mash by an on-line measuring method. Intracellular ATP and pyruvate concentrations were considered to be indicators of the physiological state of the yeast in sake mash. During sake mashing, it was observed that an increase in temperature enhanced the intracellular ATP concentration and the pyruvate production of the yeast. Since pyruvate production was not affected intensely by changes in temperature during cultivation in a glucose-limited chemostat, this effect was thought to be due to the enhanced rates of cell-growth and/or alcohol production. This suggests that the control of mashing temperature during cell growth until about 10% alcohol accumulation is achieved is important for the control of the pyruvate concentration in sake mash.

Influence of antigenic forms and adjuvants on the IgG subclass antibody response to Aujeszky's disease virus in mice.

The influence of antigenic forms of Aujeszky's disease virus (ADV) and adjuvant types on the production of IgG subclass antibodies in mice was investigated. Particulate antigen, inactivated ADV, alone induced IgG1 and lower IgG2a antibody production, while the antigen adsorbed onto aluminum phosphate gel (alum) enhanced IgG1 antibody production but suppressed IgG2a antibody production as well as solubilized ADV antigen adsorbed onto alum. QS21 saponin purified from Quillaja saponaria promoted the production of IgG1 and IgG2a antibodies in a large extent against the both particulate and soluble antigens, while this saponin has strong hemolytic activity. Lablaboside F saponin isolated from Dolichos lablab without hemolytic activity, also induced the production of large IgG1 and little IgG2a antibody against both antigens. Oil-based adjuvant, ISA70 of water-in-oil type and ISA25 of oil-in-water type, increased IgG1 and IgG2a antibodies against the both soluble and particulate antigens, whereas a combination of ISA25 and soluble antigen reduced IgG2a antibody response. These results indicate that IgG1 antibody production was not suppressed by a combination of antigenic form and adjuvant type, however, IgG2a antibody production was influenced.

Experimental infection of pigs with a parvovirus isolated from the diarrheic feces of a pig.

A parvovirus (the H-45 strain) isolated from an outbreak of epizootic diarrhea in swine was examined to observe the infectivity and pathogenecity in swine. The virus infection by intranasal route was demonstrated in each group of 2- and 5-day-old colostrum-deprived pigs, 30- and 100-day-old pigs by virus recovery from the nasal and rectal swabs, and detecting seroconversion. The virus was recovered from rectal swabs up to 14 days after inoculation and from nasal swabs up to 9 days. Uninoculated pigs were infected with the virus by contacting with the inoculated pigs. Between 1 and 5 days after inoculation, the inoculated pigs of 2, 5 and 30 days old developed diarrhea and then all the pigs of 2 days old died, resulting from dehydration. In the pigs died after intranasal inoculation, the virus was recovered mainly from the respiratory and gastrointestinal tracts. One hundred-day-old pigs showed no clinical signs. The pathological change was characterised by congestion and edema with hemorrhage in the epithelium of the small intestines exhibiting additional degeneration and desquamation of the epithelial cells.

The characteristics of another small DNA virus isolated from a pig with diarrhea.

A small DNA virus was newly isolated from the small intestines of a pig with diarrhea in 1987, in Japan. Concerning the physicochemical properties, hemagglutination and susceptibility of cell culture to the virus, the virus was identical to a formerly isolated small DNA virus, the H-45 strain and also physicochemically similar to the parvovirus group. In a serological test however, the virus was distinctly, antigenically different from the H-45 strain as well as each of porcine, bovine and canine parvoviruses.

Cloning, nucleotide sequence, and overexpression in Escherichia coli of the beta-tyrosinase gene from an obligately symbiotic thermophile, Symbiobacterium thermophilum.

Symbiobacterium thermophilum is an obligately symbiotic thermophile that can grow only in coculture with a specific Bacillus strain. The amino acid sequences of fragments obtained by cyanogen bromide decomposition of the thermostable beta-tyrosinase (tyrosine phenol-lyase, E.C. 4.1.99.2) from this organism resembled that of the tryptophanase produced by the same organism. DNA-probing with the tryptophanase gene as the hybridization probe led to cloning in Escherichia coli of the beta-tyrosinase (tpl) gene. The nucleotide sequence revealed that the beta-tyrosinase of 458 amino acids (relative molecular mass, 52269) showed significant similarity in amino acid sequence to the tryptophanase over the entire sequence. DNA manipulation of the cloned tpl gene in E. coli led to production of 375 times as much beta-tyrosinase as that produced by the original S. thermophilum strain.

Induction of mucosal disease in cattle persistently infected with noncytopathic bovine viral diarrhea-mucosal disease virus by superinfection with cytopathic bovine viral diarrhea-mucosal disease virus.

Three head of cattle persistently infected with noncytopathic bovine viral diarrhea-mucosal disease virus (ncBVD-MDV) were superinfected naturally or experimentally with cytopathic bovine viral diarrhea-mucosal disease virus (cBVD-MDV). In the naturally superinfected case, one animal manifested pyrexia and severe diarrhea, and died without developing antibodies to cBVD-MDV. However, another animal survived with only continual slight anorexia and pyrexia, and developed strong resistance to the superinfected strain. In the experimental cases, induction of MD was unsuccessful in two persistently infected cattle when superinfected with cBVD-MDV antigenically heterologous for persistently infected ncBVD-MDV. They also developed antibodies to the cBVD-MDV strain with which they had been infected. After 6 months, these cattle were infected again with a cBVD-MDV strain different from that used in the previous experiment. One animal infected with this strain, which was antigenically homologous to the persistently infected strain, died after developing MD symptoms without developing antibodies to the infecting strain. It is suggested that the antigenic relationship between the persistent ncBVD-MDV and the superinfected cBVD-MDV was an important factor in developing MD.

Protection against bovine leukemia virus infection by use of inactivated vaccines in cattle.

The protective effects of vaccines made from the viral materials of LK15 cell line (LK15 vaccine) or bat lung cell line (Bat2cl1; Bat vaccine) infected with bovine leukemia virus (BLV) were examined in cattle. Twelve cattle were vaccinated twice at 4-week interval then challenged 4 weeks after the second inoculation. Nine cattle vaccinated with the LK15 vaccine produced antibody to BLV-specific glycoprotein (gp), and the titers ranged from 1:16 to 1:64 by the agar gel immunodiffusion test. Four cattle challenged with 100 microliters (70 to 100 syncytia) of cow blood persistently infected with BLV were protected from infection. However, of the remaining 5 cattle challenged with 500 microliters of infected blood, only 2 were protected. Of the three cattle vaccinated with the Bat vaccine, gp antibody titers ranged from 1:8 to 1:64. Two of them were protected against the challenge with 100 microliters of infected blood. Two cattle protected against the challenge were rechallenged 32 weeks after the first vaccination and not protected. On the other hand, 2 animals protected against the challenge were revaccinated with the LK15 vaccine 32 weeks after the first vaccination. They protected against rechallenge. The results show that all cattle which had gp antibody titers of 1:16 or above were protective against challenge with 100 microliters of the infected blood.

Cloning, nucleotide sequences, and overexpression in Escherichia coli of tandem copies of a tryptophanase gene in an obligately symbiotic thermophile, Symbiobacterium thermophilum.

Symbiobacterium thermophilum, a thermophilic bacterium, is a thermostable tryptophanase producer that can grow only in coculture with a specific Bacillus strain. Two thermostable tryptophanase genes, tna-1 and tna-2, that are located close to each other were cloned into Escherichia coli from S. thermophilum by the DNA-probing method. The nucleotide and deduced amino acid sequences indicate that Tna1 and Tna2 share 92% identical amino acids in a total of 453 amino acids. By means of DNA manipulation with E. coli host-vector systems, Tna1 and Tna2 were produced in very large amounts in enzymatically active forms. Comparison of the NH2-terminal amino acid sequences and the enzymatic properties of the tryptophanases purified from the original S. thermophilum strain and these two tryptophanases from recombinant E. coli cells suggest that in S. thermophilum, only Tna2 is produced and tna-1 is silent. Notwithstanding the great similarity in amino acid sequence between Tna1 and Tna2, the two enzymes differ markedly in activation energy for catalysis and thermostability.

Pathological studies on local tissue reactions in guinea pigs and rats caused by four different adjuvants.

We investigated pathological changes at the injection site in guinea pigs and rats for 16 weeks following a single intramuscular injection of one of the following oil adjuvant emulsions; oil adjuvant ISA-70, Freund's incomplete adjuvant, Freund's complete adjuvant, and aluminium phosphate gel. In the animals injected with ISA-70 emulsion prepared by manual shaking, grossly, there was partial thickening of subcutaneous tissue, discoloration of inter-muscular connective tissue, and swelling of the inguinal lymph nodes at 2 and 4 weeks post injection (PI). Histopathologically, ISA-70 injected sites revealed acute inflammatory changes at 72 hrs PI, and peak reactions consisting of macrophage accumulation around oil cysts and fibrosis were observed at 4 weeks PI. These changes were less severe and of shorter duration than those in the other three adjuvants. Guinea pigs and rats injected with materials containing inactivated Newcastle disease virus (NDV) antigen similarly showed an infiltration of plasma cells and lymphocytes in addition to the changes described above. ISA-70 containing NDV antigen induced similar hemagglutination-inhibition titer to that induced by Freund's incomplete adjuvant.