Showing papers by "Hokkaido University published in 1994"

Trust and commitment in the United States and Japan

Abstract: A distinction is proposed betweentrust as a cognitive bias in the evaluation of incomplete information about the (potential) interaction partner andassurance as a perception of the incentive structure that leads the interaction partner to act cooperatively. It is hypothesized that trust in this sense helps people to move out of mutually committed relations where the partner's cooperation is assured. Although commitment formation is a rather standard solution to the problems caused by social uncertainty, commitment becomes a liability rather than an asset as opportunity costs increase. Facing increasing opportunity costs, trust provides a springboard in the attempt to break psychological inertia that has been mobilized to maintain committed relations. In conjunction with an assumption that networks of mutually committed relations play a more prominent role in Japanese society than in American society, this hypothesis has been applied to predict a set of cross-national differences between the United States and Japan in the levels of trust and related factors. The results of a cross-national questionnaire survey (with 1,136 Japanese and 501 American respondents) support most of the predictions, and indicate that, in comparison to Japanese respondents, American respondents are more trusting of other people in general, consider reputation more important, and consider themselves more honest and fair. In contrast, Japanese respondents see more utility in dealing with others through personal relations.

Anticardiolipin antibodies recognize beta 2-glycoprotein I structure altered by interacting with an oxygen modified solid phase surface.

Abstract: Anticardiolipin antibodies (aCL) derived from the sera of individuals exhibiting the antiphospholipid syndrome (APS) directly bind to beta(2)-glycoprotein I (beta(2)-GPI), which is adsorbed to an oxidized polystyrene surface. Oxygen atoms were introduced on a polystyrene surface by irradiation with electron or gamma-ray radiation. X-ray photoelectron spectroscopy revealed the irradiated surfaces were oxidized to generate C-O and C=O moieties. aCL derived from either APS patients or (NZW x BXSB)F-1 mice bound to beta(2)-GPI coated on the irradiated plates, depending on the radiation dose. Antibody binding to beta(2)-GPI on the irradiated plates was competitively inhibited by simultaneous addition of cardiolipin (CL)-coated latex beads mixed together with beta(2)-GPI but were unaffected by addition of excess beta(2)-GPI, CL micelles, or CL-coated latex beads alone. There was a high correlation between binding values of aCL in sera from 40 APS patients obtained by the anti-beta(2)-GPI enzyme-linked immunosorbent assay (ELISA) using the irradiated plates and those by the beta(2)-GPI-dependent aCL ELISA. Therefore, aCL have specificity for an epitope on beta(2)-GPI. This epitope is expressed by a conformational change occurring when beta(2)-GPI interacts with an oxygen-substituted solid phase surface.

A truncated bone morphogenetic protein receptor affects dorsal-ventral patterning in the early Xenopus embryo

Abstract: Bone morphogenetic proteins (BMPs), which are members of the transforming growth factor beta (TGF-beta) superfamily, have been implicated in bone formation and the regulation of early development. To better understand the roles of BMPs in Xenopus laevis embryogenesis, we have cloned a cDNA coding for a serine/threonine kinase receptor that binds BMP-2 and BMP-4. To analyze its function, we attempted to block the BMP signaling pathway in Xenopus embryos by using a dominant-negative mutant of the BMP receptor. When the mutant receptor lacking the putative serine/threonine kinase domain was expressed in ventral blastomeres of Xenopus embryos, these blastomeres were respecified to dorsal mesoderm, eventually resulting in the formation of a secondary body axis. These findings suggest that endogenous BMP-2 and BMP-4 are involved in the dorsal-ventral specification in the embryo and that ventral fate requires induction rather than resulting from an absence of dorsal specification.

Gastric carcinoma : monoclonal epithelial malignant cells expressing epstein-barr virus latent infection protein

Abstract: In 1000 primary gastric carcinomas, 70 (7.0%) contained Epstein-Barr virus (EBV) genomic sequences detected by PCR and Southern blots. The positive tumors comprised 8 of 9 (89%) undifferentiated lymphoepithelioma-like carcinomas, 27 of 476 (5.7%) poorly differentiated adenocarcinomas, and 35 of 515 (6.8%) moderately to well-differentiated adenocarcinomas. In situ EBV-encoded small RNA 1 hybridization and hematoxylin/eosin staining in adjacent sections showed that the EBV was present in every carcinoma cell but was not significantly present in lymphoid stroma and in normal mucosa. Two-color immunofluorescence and hematoxylin/eosin staining in parallel sections revealed that every keratin-positive epithelial malignant cell expressed EBV-determined nuclear antigen 1 (EBNA1) but did not significantly express CD45+ infiltrating leukocytes. A single fused terminal fragment was detected in each of the EBNA1-expressing tumors, thereby suggesting that the EBV-carrying gastric carcinomas represent clonal proliferation of cells infected with EBV. The carcinoma cells had exclusively EBNA1 but not EBNA2, -3A, -3B, and -3C; leader protein; and latent membrane protein 1 because of methylation. The patients with EBV-carrying gastric carcinoma had elevated serum EBV-specific antibodies. The EBV-specific cellular immunity was not significantly reduced; however, the cytotoxic T-cell target antigens were not expressed. These findings strongly suggest a causal relation between a significant proportion of gastric carcinoma and EBV, and the virus-carrying carcinoma cells may evade immune surveillance.

Dynamical properties of fractal networks: Scaling, numerical simulations, and physical realizations

Abstract: This article describes the advances that have been made over the past ten years on the problem of fracton excitations in fractal structures. The relevant systems to this subject are so numerous that focus is limited to a specific structure, the percolating network. Recent progress has followed three directions: scaling, numerical simulations, and experiment. In a happy coincidence, large-scale computations, especially those involving array processors, have become possible in recent years. Experimental techniques such as light- and neutron-scattering experiments have also been developed. Together, they form the basis for a review article useful as a guide to understanding these developments and for charting future research directions. In addition, new numerical simulation results for the dynamical properties of diluted antiferromagnets are presented and interpreted in terms of scaling arguments. The authors hope this article will bring the major advances and future issues facing this field into clearer focus, and will stimulate further research on the dynamical properties of random systems.

Transpedicular screw fixation for traumatic lesions of the middle and lower cervical spine: Description of the techniques and preliminary report

Abstract: Summary:Thirteen patients with fractures and/or dislocations of the middle and lower cervical spine were treated by transpedicular screw fixation using the Steffee variable screw placement system. Postoperative immobilization was either not used or simplified to short-term use of a soft neck collar.

Potential for transmission of avian influenza viruses to pigs

Abstract: Pandemic strains of influenza A virus arise by genetic reassortment between avian and human viruses. Pigs have been suggested to generate such reassortants as intermediate hosts. In order for pigs to serve as ‘mixing vessels’ in genetic reassortment events, they must be susceptible to both human and avian influenza viruses. The ability of avian influenza viruses to replicate in pigs, however, has not been examined comprehensively. In this study, we assessed the growth potential of 42 strains of influenza virus in pigs. Of these, 38 were avian strains, including 27 with non-human-type haemagglutinins (HA; H4 to H13). At least one strain of each HA subtype replicated in the respiratory tract of pigs for 5 to 7 days to a level equivalent to that of swine and human viruses. These results indicate that avian influenza viruses with or without non-human-type HAs can be transmitted to pigs, thus raising the possibility of introduction of their genes into humans. Sera from pigs infected with avian viruses showed high titres of antibodies in ELISA and neutralization tests, but did not inhibit haemagglutination of homologous viruses, cautioning against the use of haemagglutination-inhibition tests to identify pigs infected with avian influenza viruses. Co-infection of pigs with a swine virus and with an avian virus unable to replicate in this animal generated reassortant viruses, whose polymerase and HA genes were entirely of avian origin, that could be passaged in pigs. This finding indicates that even avian viruses that do not replicate in pigs can contribute genes in the generation of reassortants.

C3G, a guanine nucleotide-releasing protein expressed ubiquitously, binds to the Src homology 3 domains of CRK and GRB2/ASH proteins.

Abstract: CRK protein, together with GRB2/ASH and Nck proteins, belongs to the adaptor-type Src homology (SH)2-containing molecules, which transduce signals from tyrosine kinases. Here another guanine nucleotide-releasing protein (GNRP), C3G, has been identified as a CRK SH3-binding protein. The nucleotide sequence of a 4.1-kb C3G cDNA contains a 3.2-kb open reading frame encoding a 121-kDa protein, and antibodies against C3G have been shown to detect a protein of 130-140 kDa. The carboxyl terminus of C3G has a peptide sequence homologous to GNRPs for Ras, and the expression of this carboxyl terminus region suppresses the loss of CDC25 function in the yeast Saccharomyces cerevisiae. The C3G protein expressed in Escherichia coli binds to CRK and GRB2/ASH proteins. Mutational analysis of C3G assigns the SH3 binding region to a 50-amino acid region containing a proline-rich sequence. The mRNAs of both the C3G and CRK proteins are expressed ubiquitously in human adult and fetal tissues. The results of these studies suggest that the complex of CRK and C3G, or GRB2/ASH and C3G, may transduce the signals from tyrosine kinases to Ras in a number of different tissues.

Regional changes in dopamine and serotonin activation with various intensity of physical and psychological stress in the rat brain.

Abstract: The present study examined whether regional patterns of brain dopamine (DA) and serotonin (5-HT) activation after physical and psychological stress depend on the intensity of that stress. Monoamine concentrations (DA, 5-HT, and their metabolites) were measured using high-performance liquid chromatography with electrochemical detection in eight brain regions of rats exposed to two different intensities of foot shock stress for 30 min (1.5 mA or 2.5 mA) or conditioned fear stress (CFS, after single or repeated foot shock). A low level of foot shock selectively increased the DA metabolism in the medial prefrontal cortex (mPFC), whereas a high level of foot shock increased it in most of the brain regions examined in the present study. A low level of foot shock did not increase the 5-HT metabolism in any regions, but a high-intensity shock increased the 5-HT metabolism in the mPFC, nucleus accumbens, and lateral hypothalamus. Rats that received high-intensity shock displayed more freezing than those that received low-intensity shock in a conditioned fear paradigm (24 h after receiving foot shock, the animals were placed in a shock chamber without being given shock), indicating an augmentation of conditioned fear. The increased DA and 5-HT metabolism were especially marked in the mPFC after CFS following a single foot shock session (2.5 mA). Rats that were repeatedly exposed to 2.5 mA foot shock for a period of 10 days displayed a greater degree of freezing induced by CFS than those given only one foot shock session, indicating an augmentation of fear and stress intensity. CFS after repeated foot shock, like foot shock per se, increased the DA metabolism in most of the brain regions except for the striatum and increased the 5-HT metabolism in the mPFC, nucleus accumbens, and amygdala. These results suggest that regional patterns of brain DA and 5-HT activation after physical and psychological stress depend on the intensity of that stress, although there are some differences between these stress; and that the more widespread activation of DA and 5-HT after more severe stress might relate to behavioral changes that reflect the augmentation of fear.

Inhibition of tumor angiogenesis and metastasis by a saponin of Panax ginseng, ginsenoside-Rb2

Abstract: We studied the effect of ginsenoside-Rb2 extracted from Panax ginseng on angiogenesis and metastasis produced by B16-BL6 melanoma cells in syngeneic mice. Intravenous administration of ginsenoside-Rb2 on day 1, 3 or 7 after tumor inoculation achieved a remarkable reduction in the number of vessels oriented toward the tumor mass, but did not cause a significant inhibition of tumor growth. The anti-angiogenic effect was dose-dependent ranging from 10 to 500 micrograms/mouse. In contrast, intra-tumoral or oral administration of ginsenoside-Rb2 caused a marked inhibition of both neovascularization and tumor growth. Ginsenoside-Rb2 did not affect the growth of rat lung endothelial (RLE) cells, B16-BL6 melanoma cells or various types of murine normal cells in vitro. The invasion of RLE cells into the reconstituted basement membrane (Matrigel), which is considered to be an essential event in tumor neovascularization, was inhibited by ginsenoside-Rb2 in a concentration-dependent fashion, while ginsenoside-Rb2 did not inhibit the haptotactic migration of endothelial cells to fibronectin-substrate. Multiple administrations of ginsenoside-Rb2 after the intravenous inoculation of B16-BL6 melanoma cells resulted in a significant inhibition of lung metastasis as compared with the untreated control. These results suggest that the inhibition of tumor-associated angiogenesis by ginsenoside-Rb2 may partly contribute to the inhibition of lung tumor metastasis.

Possible role of Helicobacter pylori infection in early gastric cancer development

Abstract: Background. Gastric cancer is the most frequently diagnosed malignancy in Japan. The possible relationship between Helicobacter pylori infection and gastric cancer in Japan was evaluated. Methods. H. pylori infection was identified by the presence of anti-H. pylori IgG. The frequency of H. pylori infection was compared in 213 patients with gastric cancer and the same number of asymptomatic control subjects matched for age and sex. Results. The presence of IgG antibody to H. pylori was significantly more prevalent (P > 0.001) in those with gastric cancer compared with asymptomatic control subjects (88.2% versus 74.6%). H. pylori positive rates were significantly greater in patients with the intestinal type (90.4%, P > 0.001) and diffuse type (86.4%, P > 0.05) of gastric cancer than in control subjects. Ninety-three percent of the patients with early gastric cancer tested positive for H. pylori (P > 0.001 compared with control subjects), whereas no significant difference was observed between those with advanced gastric cancer and control subjects. The intestinal type of early gastric cancer showed only the significantly increased frequency of high titer (optical density 0.001) compared with control subjects without cancer. Conclusions. These results suggest that H. pylori infection may be associated with the development of early gastric cancer in Japan. Cancer 1994; 73:2691–4.

Identification of an imprinted U2af binding protein related sequence on mouse chromosome 11 using the RLGS method

Abstract: A new imprinted gene has been discovered in mice using the technique of restriction landmark genomic scanning (RLGS) with methylation sensitive enzymes. Eight out of 3,100 strain-specific NotI and BssHII spots were identified as imprinted in reciprocal F1 hybrids. Subsequently, we isolated a genomic clone for one locus on proximal chromosome 11 near the Glns locus, an imprinted region in uniparental disomic mice, and its corresponding cDNA clone. Expression of this transcript from the paternal allele was established using RT-PCR of reciprocal F1-hybrid mice. The amino-acid sequence deduced from the cDNA showed significant homology to the U2 small nuclear ribonucleoprotein auxiliary factor 35 kDa subunit.

A Case-Control Study of Alzheimer's Disease in Japan – Significance of Life-Styles

Abstract: A case-control study of Alzheimer''s disease was conducted in Japan; it involved 60 cases matched for sex and age with two resident controls each. Life-style was particularly highlighted in this study

Magnetic properties and electronic conduction of superconducting La2-xSrxCuO4.

Abstract: Magnetic susceptibility \ensuremath{\chi} and resistivity were measured in ${\mathrm{La}}_{2\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Sr}}_{\mathit{x}}$${\mathrm{CuO}}_{4}$. Enhancement of \ensuremath{\chi} due to a ferromagnetic correlation, which is inherent in the orthorhombic phase at low Sr concentrations, disappears at around x=0.05, near the margin of the superconducting regime. In superconducting samples with 0.1\ensuremath{\lesssim}x\ensuremath{\lesssim}0.2, \ensuremath{\chi} exhibits a broad peak at a temperature ${\mathit{T}}_{\mathrm{max}}$. The T-dependent part of \ensuremath{\chi}, ${\mathrm{\ensuremath{\chi}}}^{\mathit{s}}$(T), follows a single curve F regardless of x when ${\mathrm{\ensuremath{\chi}}}^{\mathit{s}}$ and T are normalized with the peak value ${\mathrm{\ensuremath{\chi}}}_{\mathrm{max}}^{\mathit{s}}$ and ${\mathit{T}}_{\mathrm{max}}$, as has been reported. However, the present scaling curve F decreases much more at T\ensuremath{\ll}${\mathit{T}}_{\mathrm{max}}$ than the reported one. The resistivity exhibits a T-linear dependence above a temperature ${\mathit{T}}^{\mathrm{*}}$ and deviates downward from the T-linear dependence below ${\mathit{T}}^{\mathrm{*}}$. For xg0.1 the temperature ${\mathit{T}}^{\mathrm{*}}$ agrees well with ${\mathit{T}}_{\mathrm{max}}$, indicating that the deviation from a T-linear resistivity is related to the decrease of \ensuremath{\chi} below ${\mathit{T}}_{\mathrm{max}}$. On the other hand, for x0.1 a large reduction of \ensuremath{\chi} is seen below \ensuremath{\sim}${\mathit{T}}^{\mathrm{*}}$ in the data up to 1000 K by Yoshizaki et al., although no peak is seen in the \ensuremath{\chi}-T curve. The T dependence of \ensuremath{\chi} in ${\mathrm{La}}_{2\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Sr}}_{\mathit{x}}$${\mathrm{Cu}}_{1\mathrm{\ensuremath{-}}\mathit{y}}$${\mathrm{Zn}}_{\mathit{y}}$${\mathrm{O}}_{4}$ is also reported for x=0.16 and 0.22.

Global uniqueness for an inverse boundary value problem arising in elasticity

Abstract: We prove that we can determine the Lame parameters of an elastic, isotropic, inhomogeneous medium in dimensionsn≧3, by making measurements of the displacements and corresponding stresses at the boundary of the medium.

Soluble β-amyloid induction of Alzheimer's phenotype for human fibroblast K+ channels

Abstract: Although beta-amyloid is the main constituent of neurite plaques and may play a role in the pathophysiology of Alzheimer's disease, mechanisms by which soluble beta-amyloid might produce early symptoms such as memory loss before diffuse plaque deposition have not been implicated. Treatment of fibroblasts with beta-amyloid (10 nM) induced the same potassium channel dysfunction previously shown to occur specifically in fibroblasts from patients with Alzheimer's disease--namely, the absence of a 113-picosiemen potassium channel. A tetraethylammonium-induced increase of intracellular concentrations of calcium, [Ca2+]i, a response that depends on functional 113-picosiemen potassium channels, was also eliminated or markedly reduced by 10 nM beta-amyloid. Increased [Ca2+]i induced by high concentrations of extracellular potassium and 166-picosiemen potassium channels were unaffected by 10 nM beta-amyloid. In Alzheimer's disease, then, beta-amyloid might alter potassium channels and thus impair neuronal function to produce symptoms such as memory loss by a means other than plaque formation.

DNA polymerase alpha associated protein P1, a murine homolog of yeast MCM3, changes its intranuclear distribution during the DNA synthetic period.

Abstract: We isolated a murine gene for the DNA polymerase alpha associated protein P1, which shares high homology with the budding yeast MCM3 protein, which is a member of a protein family involved in the early event of DNA replication having a putative DNA-dependent ATPase motif. Using a polyclonal anti-P1 antibody raised against a beta-galactosidase-P1 fusion protein, we identified at least two forms of P1 protein in the nucleus of a mouse cell line, an underphosphorylated form that was associated with a particular nuclear structure and a hyperphosphorylated form loosely bound to the nucleus. During progression through S phase, P1 disappeared, first from the euchromatic region, then from the heterochromatic region, apparently in parallel with temporally ordered DNA replication. Thus, it is likely that the underphosphorylated P1 is dissociated from the nuclear structure after DNA replication by cell cycle-dependent phosphorylation. This is the first direct observation of a protein whose behavior is consistent with that of a hypothetical factor which restricts the chromatin to replicate once per cell cycle in higher eukaryotes.

Tumor angiogenesis in human lung adenocarcinoma.

Abstract: BACKGROUND Hematogenous metastasis requires angiogenesis within the tumor. Previous studies have shown that microvessel counts in histologic sections of the primary tumor, which reflect angiogenesis, are correlated with metastasis in breast, prostate and Stage I nonsmall cell lung carcinoma. In this study, the authors investigated the association between angiogenesis, hematogenous metastasis and lymph node metastasis in all stages of lung adenocarcinoma. METHODS Microvessels were highlighted by immunostaining endothelial cells for factor VIII. We counted microvessels within the tumors of 42 patients who had surgical resection (25 with relapse and 11 without relapse more than 5 years after surgical resection). Without knowledge of patient outcome, microvessels were counted on a 200x field (0.723 mm2) in the most active areas of neovascularization. RESULTS The microvessel counts from patients with relapse after surgical resection (mean +/- standard deviation, 75.4 +/- 64.3) were significantly higher than those without relapse more than 5 years after surgical resection (42.6 +/- 26.0) (P = 0.027). Analysis of regional lymph node metastases (factor N) revealed that the microvessel counts were 62.6 +/- 35.1 for N0 (no regional lymph node metastasis), 51.7 +/- 22.2 for N1 (metastasis in ipsilateral, peribronchial and/or ipsilateral hilar lymph nodes, including direct extension), 75.4 +/- 75.3 for N2 (metastasis in ipsilateral mediastinal and/or subcarinal lymph nodes), and 74.0 for N3 (metastasis in contralateral mediastinal, contralateral hilar, ipsilateral or contralateral scalene or supraclavicular lymph node[s]), and these values were not significantly different from each other. CONCLUSIONS Angiogenesis assessed by microvessel counts, correlated positively with relapse after surgical resection and hematogenous metastasis in all stages of lung adenocarcinoma; there was no correlation with lymph node metastasis in lung adenocarcinoma.

Effects of inflorescence size on visits from pollinators and seed set of Corydalis ambigua (Papaveraceae).

Abstract: Female reproductive success (seed set) of a spring ephemeral plant, Corydalis ambigua Cham. et schlecht (Papaveraceae) was investigated in relation to inflorescence size and foraging behavior (frequency and duration of visitations) by pollinators (namely, overwintered queens of Bombus hypocrita sapporensis) by detailed daily observations of a natural population. Pollination experiments indicated that C. ambigua is self-incompatible and that seed set was significantly affected by the behavior of the pollinating queens. Plants with larger inflorescences were visited more often than those with fewer flowers. Fecundity also increased with increasing size of inflorescences. Visitation time (duration of foraging) rather than the frequency of visitations (number of visits) was critical for higher fecundity. Seed production was strongly enhanced by a few long visits (of more than 60 s), and seemed to be independent of large numbers of short visits (of less than 60 s). Hence, plants with larger inflorescences, which provide a conspicuous signal to pollinators and offer greater rewards in terms of nectar, received longer visits by B. hypocrita sapporensis queens and those plants exhibited higher fecundity.

Distribution of two congeneric charrs in streams of Hokkaido Island, Japan : considering multiple factors across scales

Abstract: Salvelinus leucomaenis (white-spotted charr) and S. malma (Dolly Varden) are distributed throughout Hokkaido Island, Japan, but sites where they occur in sympatry are rare. In general, S. malma inhabit upstream reaches and S. leucomaenis extend downstream to the ocean. Factors influencing their distribution were analyzed at four spatial scales ranging from the whole island to individual stream pools. At the island scale, S. leucomaenis were found in the warmer south-west region and at lower altitudes elsewhere, whereas S. malma were found in the colder north-east and at higher altitudes. At a regional scale, the downstream limit of S. malma and upstream limit of S. leucomaenis shifted to lower altitude from south-west to north-east across the island, coincident with the decrease in temperature. Further analysis showed that transition points from S. leucomaenis or sympatry to S. malma in individual watersheds were closely related to an index of cumulative mean monthly temperatures exceeding 5°C. However, at the scale of a single watershed, the transition occurred at different altitudes, gradients, and temperatures in two tributaries, apparently because stream discharge, habitat, and disturbances from floods interacted with these abiotic factors to limit distribution. The two charr species developed interspecific dominance hierarchies in individual pools, and there was strong complementary density compensation among stream pools that could be explained by interspecific competition but not by differences in habitat. However, patterns at watershed and regional scales suggested that interspecific competition interacts with temperature in complex ways. We conclude that the importance of various abiotic and biotic factors in shaping Hokkaido charr distributions depends on the scale at which they are viewed.