Biomedical subjects

Y Okabe

Publications and source records attributed to Y Okabe.

At least 37 records · Page 2Linked to original sources

PubMed2000

Mercury and cadmium in common cormorants (Phalacrocorax carbo).

Mercury (Hg) and cadmium (Cd) in common cormorants (Phalacrocorax carbo) collected in Lake Biwa, Japan and Tokyo, Japan, were investigated to elucidate the biological behaviors of these elements, and to assess exposure to these pollutants of wild, fish-eating birds. Hg and Cd concentrations were highest in the liver and kidneys, respectively. The lowest levels of both elements were observed in chicks. Hg concentrations in all tissues except brain increased significantly with growth from chicks to juveniles (p<0.05, U-test). Cd concentrations in the kidneys and liver also increased significantly during growth from juvenile to adult (p<0.005, U-test). When comparing hepatic Hg and Cd in adult birds between 10 samples from Lake Biwa and nine samples from Tokyo, the Cd concentrations in the Lake Biwa samples (1.4+/-0.37 microg/g dry wt) (mean+/-SD) were significantly higher than those from Tokyo (0.32+/-0.16 microg/g dry wt) (p<0.005, U-test), while no statistically significant difference was found in the Hg concentrations. Possible causes of these differences were discussed in relation to their prey.

Journal Article↗

PubMed2000

Chemical force microscopy of microcontact-printed self-assembled monolayers by pulsed-force-mode atomic force microscopy

A novel chemically sensitive imaging mode based on adhesive force detection by previously developed pulsed-force-mode atomic force microscopy (PFM-AFM) is presented. PFM-AFM enables simultaneous imaging of surface topography and adhesive force between tip and sample surfaces. Since the adhesive forces are directly related to interaction between chemical functional groups on tip and sample surfaces, we combined the adhesive force mapping by PFM-AFM with chemically modified tips to accomplish imaging of a sample surface with chemical sensitivity. The adhesive force mapping by PFM-AFM both in air and pure water with CH3- and COOH-modified tips clearly discriminated the chemical functional groups on the patterned self-assembled monolayers (SAMs) consisting of COOH- and CH3-terminated regions prepared by microcontact printing (microCP). These results indicate that the adhesive force mapping by PFM-AFM can be used to image distribution of different chemical functional groups on a sample surface. The discrimination mechanism based upon adhesive forces measured by PFM-AFM was compared with that based upon friction forces measured by friction force microscopy. The former is related to observed difference in interactions between tip and sample surfaces when the different interfaces are detached, while the latter depends on difference in periodic corrugated interfacial potentials due to Pauli repulsive forces between the outermost functional groups facing each other and also difference in shear moduli of elasticities between different SAMs.

Journal Article↗

PubMed2000

A novel cleaning method of gold-coated atomic force microscope tips for their chemical modification

For chemical modification of gold-coated AFM tips with thiol or sulfide compounds, a new two-step precleaning procedure was studied. The two-step cleaning procedure involves (i) oxidation of organic contaminants on the AFM tips with ozone treatment and (ii) reduction of the oxidized gold surface by immersing the oxidized tip into pure hot ethanol at ca. 65 degrees C. The chemically modified tips prepared from gold-coated AFM tips precleaned by the two-step procedure gave almost the same tip characteristics as those chemically modified immediately after gold vapor deposition in a factory. The present two-step cleaning procedure can be used widely for chemical modification of commercially available gold-coated AFM tips with thiol or disulfide compounds for chemical force microscopy.

Journal Article↗

PubMed2000

Associative memory retrieval induced by fluctuations in a pulsed neural network.

An associative memory retrieval in a pulsed neural network composed of the FitzHugh-Nagumo neurons is investigated. The memory is represented in the spatio-temporal firing pattern of the neurons, and the memory retrieval is accomplished using the fluctuations in the system. The storage capacity of the network is investigated numerically. It is demonstrated that this pulsed neural network is capable of an alternate retrieval of two patterns.

Action Potentials↗

PubMed2000

Human leukocyte antigen and season of birth in Japanese patients with schizophrenia.

OBJECTIVE: Five Japanese studies, to the authors' knowledge, without exception, have consistently shown an increased frequency of human leukocyte antigen (HLA)-DR1 in patients with schizophrenia. This suggests an association between HLA-DR1 and schizophrenia in the Japanese population. The mechanism of the association is unknown; however, prenatal infections may be involved. The present study explored factors, including winter birth, that might correlate with this mechanism. Age at onset and gender were also studied. METHOD: Factors were compared between Japanese patients with schizophrenia with and in those without HLA-DR1 (N=60 and N=307, respectively). RESULTS: A significantly higher incidence of births in February and March was observed in patients with (31.7%) than those without (15. 6%) HLA-DR1. No association was found between the presence of HLA-DR1 and other variables. CONCLUSIONS: Although this result is preliminary, it may suggest an interaction between HLA and winter birth in the development of schizophrenia in the Japanese population.

Adult↗

PubMed2000

Identification of the crude drug atractylodes rhizome (Byaku-jutsu) and atractylodes lancea rhizome (So-jutsu) using chloroplast TrnK sequence as a molecular marker.

Novel methods for molecular authentication of Atractylodes-derived crude drugs (Jutsu) were established based on PCR-restriction fragment length polymorphism (RFLP) and direct sequencing of chloroplast trnK. Two regions inside the chloroplast trnK were selected as molecular markers for identification and discrimination of Atractylodes Rhizome (Byaku-jutsu) and Atractylodes Lancea Rhizome (So-jutsu). The Region 1 fragment (260 bp) amplified from So-jutsu and Wa-byaku-jutsu (Atractylodes Rhizome derived from A. japonica) gave 2 bands of 180 bp and 80 bp on agarose gel electrophoresis after digestion with a restriction endonuclease HinfI, whereas the fragment amplified from Kara-byaku-jutsu (Atractylodes Rhizome derived from A. ovata) remained undigested, which allowed unambiguous identification of Kara-byaku-jutsu. By direct sequencing of Region 2 (436 bp) and comparison of the nucleotide sequence data sets we could not only discriminate Byaku-jutsu and So-jutsu but also identify the original plant species of each crude drug specimen. A simple and reliable protocol for rapid preparation of DNA suitable for PCR from as little as 1 mg of Atractylodes-derived crude drugs was also described.

Asteraceae↗

PubMed2000

Differential expression of the chemokine receptors by the Th1- and Th2-type effector populations within circulating CD4+ T cells.

The in vitro studies have proposed that human Th1 cells favor expression of CXCR3 or CCR5, whereas Th2 cells favor CCR3 and CCR4. In this study, the in vivo relevance of expression of these chemokine receptors on Th cells was investigated in patients with atopic dermatitis (AD) as the Th2-dominated disorder and nonatopic normal individuals. Flow-cytometric analysis using monoclonal antibodies against CXCR3, CCR5, CCR3, and CCR4 disclosed that a substantial proportion of memory (CD45RO+) CD4+ T cells in the blood of AD and normal patients expressed CXCR3, CCR5, or CCR4, but expression of CCR3 on these cells was negligible. Stimulation studies combined with intracellular cytokine staining revealed that the cells capable of producing Th2 cytokines, such as interleukin-4 (IL-4), IL-5, and IL-13, were restricted to the CCR4-expressing population within memory CD4+ T cells. Concerning Th1 cytokine production, interferon-gamma (IFN-gamma)-producing cells resided exclusively in CXCR3-expressing memory CD4+ T cells, although IFN-gamma production was found in both memory CD4+ T cells with and without CCR5 expression. We observed that CCR4-expressing memory CD4+ T cells in the blood were more increased in AD patients as compared with normal patients, whereas CXCR3-expressing memory CD4+ T cells were present in a lower frequency in AD than seen in normal patients. These results suggest that CXCR3 and CCR4, but not CCR5 or CCR3, appear to serve as the useful markers for identification of circulating Th1 and Th2 effector populations.

Adult↗

PubMed1999

Cluster analysis and finite-size scaling for Ising spin systems.

Based on the connection between the Ising model and a correlated percolation model, we calculate the distribution function for the fraction (c) of lattice sites in percolating clusters in subgraphs with n percolating clusters, f(n)(c), and the distribution function for magnetization (m) in subgraphs with n percolating clusters, p(n)(m). We find that f(n)(c) and p(n)(m) have very good finite-size scaling behavior and that they have universal finite-size scaling functions for the model on square, plane triangular, and honeycomb lattices when aspect ratios of these lattices have the proportions 1:square root[3]/2:square root[3]. The complex structure of the magnetization distribution function p(m) for the system with large aspect ratio could be understood from the independent orientations of two or more percolation clusters in such a system.

Journal Article↗

PubMed1999

A simple and rapid protocol for preparation of crude drug DNA suitable for PCR.

A protocol for rapid purification of DNA from a variety of herbal crude drugs, starting from samples as small as 1 mg, has been developed. Neither phenol extraction nor alcohol precipitation is involved in the procedure. Total nucleic acids are first extracted with the lysis buffer containing SDS. After CHCl3 extraction, DNA is bound to glass fiber fleece in the presence of guanidine thiocyanate, while unbound impurities are washed away. The entire procedure can be carried out in 1.5-ml microtubes. The purified DNA obtained serves as a template for PCR.

DNA, Plant↗

PubMed1999

Association between a focal spared area in the fatty liver and intrahepatic efferent blood flow from the gallbladder wall: evaluation with color Doppler sonography.

OBJECTIVE: The purpose of this study was to investigate whether fatty sparing adjacent to the gallbladder fossa is related to efferent blood flow from the gallbladder wall. SUBJECTS AND METHODS: Color and power Doppler sonography were performed in 80 patients with a fatty liver that appeared as a fine echogenic pattern with considerable deep attenuation on sonography. We analyzed whether color signal appeared around the spared area, the gallbladder wall, or both. Subsequently, when such signal was detected, pulse Doppler analysis of the signal was performed. RESULTS: Color signal indicating efferent blood flow from the gallbladder wall was detected in 25 (64%) of 39 patients with a focal spared area at the gallbladder fossa and in two (5%) of 41 patients without a focal spared area. This difference was statistically significant (p < .05). The waveform of efferent blood flow signals (n = 25) that were seen within spared areas was continuous in 23 (92%) of 25 patients and was pulsatile in the remaining two patients (8%). CONCLUSION: Blood flow from the gallbladder wall to areas of the spared liver was frequently revealed by color and power Doppler sonography; therefore, this blood flow may be associated with focal fatty sparing.

Adult↗

PubMed1998

Purification and characterization of an NAD-malic enzyme from Bradyrhizobium japonicum A1017.

An NAD-malic enzyme was purified to homogeneity from Bradyrhizobium japonicum A1017, and its molecular characteristics were surveyed. The enzyme exhibited native and subunit molecular masses of 388 and 85 kDa, respectively, suggesting that it exists as a homotetramer, and was activated by metabolic intermediates in glycolysis. The role of the enzyme in bacteroids' carbon metabolism is discussed.

Amino Acid Sequence↗

PubMed1998

Inflammatory bowel disease-like enteritis and caecitis in a senescence accelerated mouse P1/Yit strain.

BACKGROUND: A new subline of the senescence accelerated mouse (SAM) P1/Yit strain has been established which shows spontaneous enteric inflammation under specific pathogen free (SPF) conditions. AIMS: To elucidate the pathogenesis of enteric inflammation in this new subline. METHODS: The SPF and germ free (GF) SAMP1/Yit strains were used. Histological, immunological, and microbiological characterisation of the mice with enteric inflammation was performed. RESULTS: Histologically, enteritic inflammation developed as a discontinuous lesion in the terminal ileum and caecum with the infiltration of many inflammatory cells after 10 weeks of age. the activity of myeloperoxidase, and both immunolocalisation and mRNA expression of inducible nitric oxide synthase increased in the lesion. CD3-epsilon positive T cells, neutrophils, and macrophages were more numerous in the inflamed mucosa of the SAMP1/Yit strain. The GF SAMP1/Yit strain did not show any inflammation in the intestinal wall, by the age of 30 weeks, and the enteritis and caecitis developed 10 weeks after the conventionalisation of the GF SAMP1/Yit strain. CONCLUSION: Enteric inflammation in the ileum and caecum developed in the SAMP1/Yit strain. The pathophysiological characteristics of the disease in this mouse have some similarities to those of human inflammatory bowel disease (IBD). This mouse strain should be a useful model system for elucidating the interaction between the pathogenesis of IBD and the gut microflora.

Aging↗

PubMed1998

[Clinical diagnosis of pancreato-biliary lesions by ultrasound angiography with intra-arterial infusion of carbon dioxide microbubbles].

Ultrasound angiography (USAG), sonographic imaging of the blood flow with intra-arterial infusion of carbon dioxide (CO2) microbubbles, was applied to pancreato-biliary lesions. Hypervascular pattern was observed in all cases of gallbladder elevated lesions except for debris balls. However, the vascular pattern of CO2 inflow that many arterial vessels were branching off into the lesion was characteristic for gallbladder carcinomas. The hemodynamics of solid tumors of the pancreas with USAG were divided into three patterns. Most of hypovascular nodules were duct cell carcinomas, while inflammatory pancreatic masses always exhibited isovascular except for two cases of hypovascular pattern. Furthermore, islet cell tumors showed hypervascular. In cases of mucin-producing cystic tumors of the pancreas, excrescent nodules or thickened septa within the lesions were identified as hypervascular. Other cystic tumors of the pancreas also presented peculiar hemodynamics. Therefore USAG is potentially useful for detecting various vascular patterns of pancreato-biliary lesions, contributory as a diagnostic tool in this area.

Carbon Dioxide↗

PubMed1998

[MR cholangiopancreatography (MRCP) for the mucin producing pancreatic tumor (MPT)].

MRCP was performed for 17 patients with MPT (main duct type; 7 and branch duct type; 10) using HASTE and single shot RARE with a body phased array coil on a 1.5 T unit. The findings of MRCP were compared with those of endoscopic retrograde cholangiopancreatography (ERCP). In all cases, MRCP completely disclosed all dilated ducts and cysts, some of which were not seen by ERCP due to mucinous accumulation. In five of seven patients with main duct type, an excrescent nodle was more clearly visualized by ERCP than by MRCP. Mucinous accumulation was not confirmed by MRCP in all cases except one case, in which the dilated branch duct was revealed as lower intensity compared with the main duct using single shot RARE. Therefore MRCP and ERCP are complementary methods in diagnosis for the mucin producing pancreatic tumor.

Adenocarcinoma, Mucinous↗

PubMed1997

A robust reconstruction of sparse biomagnetic sources.

Inequalty constraints are introduced to a normalized minimum-L1-norm estimator, which gives a sparse solution of the biomagnetic inverse problem. The constraints have a numeric tolerance to take into account the measurement ambiguity caused by noise. Computer simulation and phantom-data analysis show how the solution is improved by the constraints with a moderate tolerance; the improvement is examined in noisy conditions such that signal-to-noise ratios (SNR's) are lower than 10 dB.

Computer Simulation↗

PubMed1997

Purification and characterization of the NADP-malic enzyme from Bradyrhizobium japonicum A1017.

An NADP-malic enzyme [EC 1.1.1.40] was purified to homogeneity from Bradyrhizobium japonicum A1017, and the molecular and physiological characteristics were surveyed. The molecular mass of one subunit of the purified enzyme was evaluated to be 77,600 Da by SDS-PAGE, and the native enzyme was a tetramer in pH 7.0 and dimer in pH 8.0 conditions, showing complex oligomeric characteristics corresponding to pH value.

Amino Acid Sequence↗

PubMed1996

Specific accumulation of tumor-derived adhesion factor in tumor blood vessels and in capillary tube-like structures of cultured vascular endothelial cells.

Tumor-derived adhesion factor (TAF) was previously identified as a cell adhesion molecule secreted by human bladder carcinoma cell line EJ-1. To elucidate the physiological function of TAF, we examined its distribution in human normal and tumor tissues. Immunochemical staining with an anti-TAF monoclonal antibody showed that TAF was specifically accumulated in small blood vessels and capillaries within and adjacent to tumor nests, but not in those in normal tissues. Tumor blood vessel-specific staining of TAF was observed in various human cancers, such as esophagus, brain, lung, and stomach cancers. Double immunofluorescent staining showed apparent colocalization of TAF and type IV collagen in the vascular basement membrane. In vitro experiments demonstrated that TAF preferentially bound to type IV collagen among various extracellular matrix components tested. In cell culture experiments, TAF promoted adhesion of human umbilical vein endothelial cells to type IV collagen substrate and induced their morphological change. Furthermore, when the endothelial cells were induced to form capillary tube-like structures by type I collagen, TAF and type IV collagen were exclusively detected on the tubular structures. The capillary tube formation in vitro was prevented by heparin, which inhibited the binding of TAF to the endothelial cells. These results strongly suggest that TAF contributes to the organization of new capillary vessels in tumor tissues by modulating the interaction of endothelial cells with type IV collagen.

Cell Adhesion↗

PubMed1996

Sequence of a Na+/glucose symporter gene and its flanking regions of Vibrio parahaemolyticus.

The nucleotide sequence of an approximately 6 kbp segment of chromosomal DNA of Vibrio parahaemolyticus was determined. The nucleotide sequence revealed four open reading frames (ORFs) in this region. Hydropathy profiles of the deduced amino acid sequence of the ORFs indicate that ORF1 encodes a hydrophobic polypeptide with typical characteristics of a membrane transport protein. All other ORFs encode hydrophilic polypeptides. ORF1 showed significant amino acid sequence similarity to proteins of the SGLT (Na+/glucose symporter) family, and the amino acid sequence of ORF4 showed very high similarity to several bacterial transcriptional repressor proteins (GalR-LacI family). We observed elevated glucose transport activity in cells harboring a plasmid carrying the DNA region corresponding to ORF1, and the glucose transport was greatly stimulated by Na+. Thus, we believe that ORF1 encodes a Na+/glucose symporter.

Amino Acid Sequence↗