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Biomedical subjects

N Kobayashi

Publications and source records attributed to N Kobayashi.

At least 181 records · Page 10Linked to original sources
PubMed2000

Transplantation of highly differentiated immortalized human hepatocytes to treat acute liver failure.

BACKGROUND: Temporary support of a damaged liver by a bioartificial liver (BAL) devise is a promising approach for the treatment of acute liver failure. Although human primary hepatocytes are an ideal source of hepatic function in BAL, shortage of human livers available for hepatocyte isolation is the limiting factor for the use of this modality. A clonal human hepatocyte cell line that can grow economically in culture and exhibit liver-specific functions should be an attractive solution to this problem. METHODS: To test this alternative, primary human fetal hepatocytes were immortalized using Simian virus 40 large T antigen. To investigate the potential of the immortalized cells for BAL, we transplanted the cells into the spleen of adult rats and performed a 90% hepatectomy 12 hr later. RESULTS: One of the cloned human liver cell lines, OUMS-29, showed highly differentiated liver functions. Intrasplenic transplanting of 20x10(6) OUMS-29 cells protected the animals from hyperammonemia and the associated hepatic encephalopathy. Survival was significantly prolonged in 90% of hepatectomized rats receiving OUMS-29 cells. CONCLUSIONS: A highly differentiated immortalized human hepatocyte cell line, OUMS-29, was able to provide metabolic support during acute liver failure induced by 90% hepatectomy in rats. Essentially unlimited availability of OUMS-29 cells may be clinically useful for BAL treatment.

Ammonia↗
PubMed2000

Sound-induced laryngeal and respiratory reflexes originate from vestibular afferents.

To determine whether the auditory or vestibular system causes the sound-induced laryngeal reflex, which has been considered to participate in the auditory feedback control of vocalization, click-induced laryngeal responses were compared before and after sectioning of the cochlear and/or vestibular nerves in cats. The sound-induced reflex modulation of respiratory muscle activity was also investigated, because respiratory movement is important for vocal control. Sectioning of the cochlear nerves had little influence on these responses. In contrast, sectioning of the vestibular nerves abolished these responses. It was concluded that the sound-induced laryngeal and respiratory reflexes are attributed to the vestibular system.

Acoustic Stimulation↗
PubMed2000

Thermodynamics of a beta-hairpin structure: evidence for cooperative formation of folding nucleus.

To elucidate early nucleation stages in protein folding, multi-probed thermodynamic characterization was applied to the beta-hairpin structural formation of G-peptide, which is a C-terminal fragment of the B1 domain of streptococcal protein G. The segment corresponding to the sequence of G-peptide is believed to act as a nucleus during the folding process of the B1 domain. In spite of the broad thermal transition of G-peptide, nuclear magnetic resonance (NMR) melting measurements combined with our original analytical theory enabled us to obtain the thermodynamic properties of the beta-hairpin formation with considerable accuracy. Additionally, all the thermodynamic properties determined by every NMR probe on both the main-chain and the side-chains were quite similar, and also comparable to the values that were independently determined by calorimetric analysis of G-peptide. These results demonstrate that G-peptide folds cooperatively throughout the molecule. In other words, the formation of the beta-hairpin is interpreted as the fashion of a first-order phase transition between two states without any distinguishable intermediates. This cooperative formation of the short linear peptide consisting of only 16 residues provides insight into not only the first folding events of the B1 domain, but also the general principles of proteins in terms of structural hierarchy, stability and folding mechanism.

Bacterial Proteins↗
PubMed2000

Comparative spectroscopic and electrochemical properties of bis(octakis(dodecylthio)naphthalocyaninato)europium(III) and bis(tetra-tert-butylnaphthalocyaninato)europium(III) complexes.

Bis(substituted-2,3-naphthalocyaninato)europium(III) complexes: bis(octakis(dodecylthio)-2,3-naphthalocyaninato)europium(III) (Eu[2,3-Nc(SC12H25)8]2, 1) and bis(tetra-tert-butyl-2,3- naphthalocyaninato)europium(III) (Eu[2,3-Nc(t-Bu)4]2, 2) have been synthesized by cyclic tetramerization of naphthalonitriles with Eu(acac)3.H2O in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in refluxing n-octanol. These compounds were characterized by UV-visible, magnetic circular dichroism (MCD), near-IR, IR, EPR, and mass spectroscopies. The absorption and MCD spectra of 1 showed splitting of the Q band, with peaks at 700 and 784 nm, red shifted from the Q band of 2 at 763 nm. The absorption and MCD spectral band deconvolution calculations of complex 1 gave two A terms in the Q-band region. The A terms are assigned to 2A2-->2E1 transitions. Cyclic voltammograms of 1 and 2 showed reversible oxidation couples at E1/2 = -0.28 V (for 2) and -0.25 V (for 1) vs ferrocenium/ferrocene (Fc+/Fc). The second oxidation exhibited a complicated behavior for both complexes. The reduction couples for 2 were observed at E1/2 = -0.61, -1.64, -1.97, and -2.42 V, and for 1 they were observed at E1/2 = -0.62, -1.60, -1.86, and -2.27 V vs Fc+/Fc. Spectral changes observed on chemical oxidation and reduction of the complexes are presented, and the behaviors of 1 and 2 are compared.

Journal Article↗
PubMed2000

Psychometric properties of the State-Trait Anxiety Inventory among Japanese clinical outpatients.

The factor structure and internal consistency of the Japanese adaptation of the State-Trait Anxiety Inventory Form Y (STAI-JY) were examined for 218 Japanese clinical outpatients (86 males, 132 females) with psychiatric and/or psychosomatic complaints. An initial principal-component analysis revealed that the first three components were considered to reflect the "overall anxiety" component, the "presence-absence of anxiety (positive-negative)" component, and the "state-trait anxiety" component. The component related to presence or absence of anxiety was larger than the state-trait anxiety component. Factors followed by an oblique (promax) rotation were labeled "Anxiety-absent" and "Anxiety-present" factors for a two-factor structure, and "Anxiety-present," "Anxiety-absent/state," and "Anxiety-absent/trait" factors for a three-factor structure that was suggested by the scree test. The internal consistencies for both the state and trait anxiety subscales of the STAI-JY were at a satisfactory level, whereas slightly higher Cronbach's as were obtained from separate calculation for anxiety-present and anxiety-absent items. Similarities and differences in the factor structure of the STAI-JY were discussed in comparison with those reported earlier for the general population in Japan and for individuals in Western countries.

Adolescent↗
PubMed2000

Expression of the E-cadherin/catenin (alpha-, beta-, and gamma-) complex correlates with the macroscopic appearance of early gastric cancer.

E-cadherin and its associated cytoplasmic proteins, alpha-, beta-, and gamma-catenins, play an essential role in the control of epithelial differentiation. We have previously shown that loss or down-regulation of E-cadherin/catenin correlates with poor survival in advanced gastric adenocarcinoma. The aim of this study was to assess the expression of E-cadherin and catenins in early gastric cancers (EGCs). Immunohistochemical staining for E-cadherin and alpha-, beta-, and gamma-catenins was performed on 41 paraffin-embedded gastrectomy specimens of EGC using an indirect immunoperoxidase technique. The pattern of expression and cellular localization of the E-cadherin/catenin complex in tumour cells were correlated with the macroscopic appearance of the tumour according to the Japanese Endoscopic Society classification. The tumours were classified as follows: three type I (protruding) and 38 type II (superficial), of which ten were type IIa (elevated), one was type IIb (flat), and 27 were type IIc (depressed). E-cadherin and alpha-, beta-, and gamma-catenins were expressed at the cell-cell junctions in normal mucosa. Forty out of 41 tumours showed abnormal expression (loss of membranous immunoreactivity and/or nuclear staining) of at least one component of the E-cadherin catenin complex. Loss of E-cadherin immunoreactivity was more frequently seen in type IIb (1/1, 100%) and type IIc (27/27, 100%) than in type I (1/3, 33%) and type IIa (1/10, 10%) (p<0.01). Abnormal expression of E-cadherin and alpha-catenin was more frequently seen in diffuse-type than in intestinal type tumours (p<0.05). Abnormal immunoreactivity of beta- and gamma-catenin, including nuclear localization, was observed in 34% and 7.3% of tumours, respectively, but there was no significant correlation with tumour type or endoscopic appearance. In conclusion, abnormal expression of the E-cadherin/catenin complex occurs in EGC and seems to correlate with macroscopic appearances.

Adenocarcinoma↗
PubMed2000

TNF-alpha induced p21(WAF1) but not Bax in colon cancer cells WiDr with mutated p53: important role of protein stabilization.

The p21(WAF1)induces cell cycle arrest at G(1)and its expression is regulated by the functional p53. TNF-alpha induced expression of p21(WAF1)at protein and mRNA levels in a dose-dependent fashion with an association with G(1)-arrest in human colon cancer cells WiDr that carry mutated p53 at codon 273 (His(273)). However, TNF-alpha did not affect the levels of the Bax protein, which also has p53-binding sites on its promoter and causes apoptosis. Further experiments suggested that cycloheximide (CHX), a protein synthesis inhibitor, increased the levels of p21(WAF1)mRNA and the induction of p21(WAF1)mRNA by TNF-alpha did not require new protein synthesis. Co-transfection of the p53 His(273)expression construct with a luciferase gene controlled by the p21(WAF1)promoter showed that the p53 His(273)was inactive, although TNF-alpha increased the transcriptional rate of p21(WAF1)in these cells. Further study found that TNF-alpha markedly stabilized the p21(WAF1)protein. These findings suggest that TNF-alpha induces expression of p21(WAF1)through a distinct pathway from Bax and that protein stabilization is an important mechanism in the expression of p21(WAF1)independent of p53.

Apoptosis↗
PubMed2000

Transforming growth factor-beta 1 derived from biliary epithelial cells may attenuate alloantigen-specific immune responses.

Immune response to liver allografts may be different from that to other organ transplants since immunological manipulation easily attenuates immune-response to liver allografts. Numerous studies on the alloantigen-specific immune response have been carried out, however, the precise mechanisms involved in this attenuation are not clear yet. Here we suggest the attenuation of alloantigen-specific immune response by TGF-beta 1 derived from biliary epithelial cells. The transforming growth factor-beta 1 (TGF-beta 1) expression in rat liver was examined immunohistologically. Rat biliary epithelial cells (BEC) were purified from the perfused liver and added to allogeneic mixed lymphocyte reaction (allo-MLR) to assess their attenuating potential on allo-MLR and alloantigen-specific cytotoxic T lymphocyte (allo-CTL) induction. Immunohistological investigation revealed the expression of TGF-beta 1 in biliary epithelial cells. Both purified biliary epithelial cells and TGF-beta 1 attenuated allo-MLR and allo-CTL induction in a dose-dependent manner, and anti-TGF-beta 1 antibody partially relieved this attenuation. This study reveals that biliary epithelial cells, the major target cells of allo-antigen specific immune response, contain TGF-beta 1 and that they have a capacity to attenuate allo-MLR and allo-CTL induction.

Animals↗
PubMed2000

Benign esophageal schwannoma: report of a case.

We report herein the case of an otherwise asymptomatic 62-year-old woman who was found to have an incidental esophageal lesion during endoscopic follow-up of an unrelated disorder. An esophageal submucosal tumor was diagnosed, and the patient was subsequently monitored on a regular yearly basis. As the diameter of the tumor doubled over a 4-year period, the possibility of a malignant lesion could not be excluded, and she was admitted to our hospital for further investigations. Esophagography, endoscopy, endoscopic ultrasonography, and computed tomography confirmed a submucosal tumor, 35 mm in length, in the thoracic midesophagus. A leiomyoma or leiomyosarcoma was suspected based on the known incidence of such tumors, and tumor enucleation was performed. Gross inspection revealed a solid tumor arising from the wall of the esophagus. Histopathologic examination showed intertwined bundles of spindle cells with spiral-like proliferation, and immunohistochemical studies were positive for S-100 protein, whereby a diagnosis of esophageal schwannoma was established. The patient experienced no postoperative complications, and her clinical course to date has been satisfactory. To date, 2 years 8 months after surgery, she has shown no sign of tumor recurrence and remains in good health.

Esophageal Neoplasms↗
PubMed2000

Endoscopic mucosal resection using a partial transparent hood for lesions located tangentially to the endoscope.

BACKGROUND: Numerous methods have been developed to resect early-stage gastric and esophageal cancers, but it is difficult to resect lesions viewed tangentially with the endoscope. METHODS: We have designed and developed an original method of endoscopic mucosal resection using a partial transparent hood to treat difficult cases in which the lesions are located tangentially to the endoscope. The hood was attached on the right side of the endoscope and, after insertion into the stomach or the esophagus, was lightly pressed on the orad side of the lesion. Then the lesion was resected using grasping forceps and electrosurgical current snare. RESULTS: The average diameter of specimens was 26 +/- 8 mm in gastric lesions and 20 +/- 3 mm in esophageal lesions, both 6 mm larger than those obtained by previous methods. CONCLUSION: This device and technique were extremely useful for mucosal resection of lesions located tangentially to the endoscope.

Electrosurgery↗
PubMed2000

Betalains from Christmas cactus.

The presence of 14 betalain pigments have been detected by their characteristic spectral properties in flower petals of Christmas cactus (Schlumbergera x buckleyi). Along with the known vulgaxanthin I, betalamic acid, betanin and phyllocactin (6'-O-malonylbetanin), the structure of a new phyllocactin-derived betacyanin was elucidated by various spectroscopic techniques and carbohydrate analyses as betanidin 5-O-(2'-O-beta-D-apiofuranosyl-6'-O-malonyl)-beta-D-glucopyranosid e. Among the more complex betacyanins occurring in trace amounts, the presence of a new diacylated betacyanin ¿betanidin 5-O-[(5"-O-E-feruloyl)-2'-O-beta-D- apiofuranosyl-6'-O-malonyl)]-beta-D-glucopyranoside¿ has been ascertained. Furthermore, the accumulation of betalains during flower development and their pattern in different organs of the flower has been examined.

Betalains↗