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Biomedical subjects

T Aoki

Publications and source records attributed to T Aoki.

At least 73 records · Page 4Linked to original sources
PubMed2001

Isolation, characterization, and transplantation of bone marrow-derived hepatocyte stem cells.

Recently it was shown that a population of cells in the bone marrow-expressing hematopoietic stem cell antigens could differentiate into hepatocytes. However, explicitly committed hepatocyte progenitors, which exhibit highly differentiated liver functions, immediately upon isolation, have not yet been isolated from bone marrow. After studying common antigens on blast-like cells in fetal and adult regenerating cholestatic rat livers and human regenerating and malignant livers, we hypothesized that beta-2-microglobulin-negative (beta(2)m(-)) cells might represent dedifferentiated hepatocytes and/or their progenitors. Utilizing a two-step magnetic bead cell-sorting procedure, we show that in bone marrow from rat and human, beta(2)m(-)/Thy-1(+) cells consistently express liver-specific genes and functions. After intraportal infusion into rat livers, bone marrow-derived hepatocyte stem cells (BDHSC) integrated with hepatic cell plates and differentiated into mature hepatocytes. In a culture system simulating liver regeneration and containing cholestatic serum, these cells differentiated into mature hepatocytes and metabolized ammonia into urea. This differentiation was dependent on a yet nondescript humoral signal existing in the cholestatic serum. Transmission electron microscopy and three-dimensional digital reconstruction confirmed hepatocyte ultrastructure of cultured BDHSC.

Albumins↗
PubMed2001

Is frozen section effective for diagnosis of unsuspected gallbladder cancer during laparoscopic cholecystectomy?

BACKGROUND: Although frozen section is recommended to prevent tumor dissemination following laparoscopic cholecystectomy (LC) for unsuspected gallbladder cancer, there are no reports concretely demonstrating its effectiveness and outcome. METHODS: Frozen section during LC was performed in 990 patients with gallstones. The sensitivity, specificity of frozen section, and false-negative cases were evaluated in comparison with postoperative entire cross sections. RESULTS: In frozen section, 983 cases were diagnosed as benign and 7 cases as malignant. Of the benign cases, cancer was discovered in 4 patients postoperatively in which frozen section was diagnosed as regenerative epithelial severe atypia. Sensitivity was 64% and specificity was 100%. Concerning the results of frozen section by p-TNM classification, cancer was diagnosed in 40% of Tis lesions, whereas it was found in 83% of T2 or T3 lesions. CONCLUSION: Frozen section is effective in cases with T2 or greater lesions for which conversion to radical surgery should be required.

Adult↗
PubMed2001

Angiogenesis in pancreatic carcinoma: thymidine phosphorylase expression in stromal cells and intratumoral microvessel density as independent predictors of overall and relapse-free survival.

BACKGROUND: Recently, the usefulness of intratumoral microvessel density (IMD) and expression of several angiogenic factors as prognostic indicators have been demonstrated in several human solid tumors. METHODS: One hundred four patients with pancreatic ductal adenocarcinoma were examined retrospectively. The investigated clinicopathologic and immunohistologic data included staining for vascular endothelial growth factor (VEGF), thymidine phosphorylase (TP), basic fibroblast growth factor (bFGF), CD34 (for calculating IMD), p53, and Ki-67. RESULTS: Multivariate analysis for both overall and relapse-free survival revealed two independent variables, IMD and TP staining in stromal cells (TPs, P < 0.02). Whereas the frequency of hepatic metastasis was correlated significantly with cytoplasmic expression of TP or bFGF in tumor cells (TPc, bFGFc), IMD, and p53 status, local recurrence was significantly more common in patients with positive staining for TPs, bFGF in stromal cells (bFGFs), and for the pM category (P < 0.05). TPc, bFGFc, VEGF, and p53 expression correlated with IMD (P < 0.01), although TPs and bFGFs expression did not. VEGF and IMD status correlated with p53 expression (P < 0.001), although TP, bFGF, and Ki-67 status did not. CONCLUSIONS: TPs expression and IMD were revealed to be valuable tools for predicting overall and relapse-free survival in patients with pancreatic adenocarcinoma. Whereas TPc and bFGFc are likely to participate in hepatic metastasis by means of their angiogenic properties, TPs and bFGFs may be related to local tumor progression. Angiogenesis in human pancreatic carcinoma may be dependent on VEGF, TP, and bFGF. p53 abnormality is likely to take part in VEGF-related angiogenesis.

Adenocarcinoma↗
PubMed2001

Genetic evidence that antibacterial activity of lysozyme is independent of its catalytic function.

A catalytically inactive mutant of hen egg white lysozyme was constructed by site-directed mutagenesis to elucidate the role of enzymatic activity on its antimicrobial activity against Gram-positive bacteria. The catalytic residue aspartic acid at position 52 of lysozyme was substituted with serine (D52S-Lz) and the mutant cDNA was inserted into a yeast expression vector, pYES-2. Western blot analysis indicated that the mutation did not affect secretion of the D52S-Lz lysozyme into the medium of the expressing Saccharomyces cerevisiae, INVSC1. In addition, circular dichroism and fluorescence spectral analysis revealed no change in the structure of D52S-Lz compared to that of wild-type (Wt-Lz) lysozyme. The mutation (D52S) abolished the catalytic activity of lysozyme. Antimicrobial tests against Staphylococcus aureus and Bacillus subtilis revealed that the catalytically inactive D52S-Lz was as bactericidal as the Wt-Lz lysozyme. Heat treatment leading to enzyme inactivation had no effect on the bactericidal activity of either wild-type or the mutant D52S-Lz lysozyme. The binding affinity of D52S-Lz to the isolated peptidoglycan of S. aureus was unaffected. Our results provide the first demonstration of direct genetic evidence that the antimicrobial activity of lysozyme is operationally independent of its muramidase activity, and strongly suggest the antimicrobial action of lysozyme is due to structural factors.

Anti-Bacterial Agents↗
PubMed2001

Synthesis and bioactivities of novel 5,6-bis(4-methoxyphenyl)-2H-pyridazin-3-one derivatives: inhibitors of interleukin-1 beta (IL-1beta) production.

New 5,6-bis(4-methoxyphenyl)-2H-pyridazin-3-one derivatives were prepared, and their abilities to inhibit IL-1beta production were evaluated. Some compounds showed potent inhibitory activity against IL-1beta production in HL-60 cells stimulated with lipopolysaccharide (LPS). The synthesis and structure-activity relationships of these compounds are described.

Administration, Oral↗
PubMed2001

Homophilic complex formation of MT1-MMP facilitates proMMP-2 activation on the cell surface and promotes tumor cell invasion.

Activation of proMMP-2 by MT1-MMP is considered to be a critical event in cancer cell invasion. In the activation step, TIMP-2 bound to MT1-MMP on the cell surface acts as a receptor for proMMP-2. Subsequently, adjacent TIMP-2-free MT1-MMP activates the proMMP-2 in the ternary complex. In this study, we demonstrate that MT1-MMP forms a homophilic complex through the hemopexin-like (PEX) domain that acts as a mechanism to keep MT1-MMP molecules close together to facilitate proMMP-2 activation. Deletion of the PEX domain in MT1-MMP, or swapping the domain with the one derived from MT4-MMP, abolished the ability to activate proMMP-2 on the cell surface without affecting the proteolytic activities. In addition, expression of the mutant MT1-MMP lacking the catalytic domain (MT1PEX-F) efficiently inhibited complex formation of the full-length enzymes and activation of pro MMP-2. Furthermore, expression of MT1PEX-F inhibited proMMP-2 activation and Matrigel invasion activity of invasive human fibrosarcoma HT1080 cells. These findings elucidate a new function of the PEX domain: regulating MT1-MMP activity on the cell surface, which accelerates cellular invasiveness in the tissue.

Animals↗
PubMed2001

Molecular cloning, expression and evolution of the Japanese flounder goose-type lysozyme gene, and the lytic activity of its recombinant protein.

In this study, we cloned the goose-type (g-type) lysozyme gene from the Japanese flounder genomic DNA library, the first such data in fish and only the second after the chicken g-type lysozyme gene. The Japanese flounder g-type lysozyme gene was 1252 bp in length from the transcription site to the polyadenylation site, coded for 758 bp of mRNA and 195 deduced amino acids, which contain five exons and four introns. A phylogenetic analysis based on amino acid sequences showed that the flounder gene was closer to g-type lysozyme, followed by phage-type lysozyme and then chicken-type (c-type) lysozyme. Although exon 1 of the flounder gene differs from exons 1 and 2 of the chicken g-type lysozyme gene, three catalytic residues, as well as their neighboring amino acids were conserved between the Japanese flounder and the four avian g-type lysozymes. In a Southern blot analysis using the genomic DNA of homo-cloned Japanese flounder, the flounder g-type lysozyme gene showed a simple pattern, suggesting that it is encoded by a single copy gene. A Northern blot analysis showed that this gene was expressed in all tissues of Japanese flounder that we examined in this study and showed major differences from those expressed tissues of the chicken g-type gene. Japanese flounder g-type lysozyme mRNA levels in the intestine, heart and whole blood increased after injecting the fish with Edwardsiella tarda. Recombinant flounder g-type lysozyme, which has an optimal pH and temperature of pH 6.0 and 25 degrees C, possessed lytic activity against Micrococcus lysodeikticus and several fish pathogenic bacteria. This is the first report of a g-type lysozyme gene other than for reported avian species.

Animals↗
PubMed2001

Conservation of the biochemical mechanisms of signal transduction among mammalian Notch family members.

Mouse Notch1, which plays an important role in cell fate determination in development, is proteolytically processed within its transmembrane domain by unidentified gamma-secretase-like activity that depends on presenilin. To study this proteolytic event, we established a cell-free Notch cleavage assay system using the membrane fraction of fibroblast transfectants of various Notch constructs with deletion of the extracellular portion (Notch DeltaE). The cytoplasmic portion of Notch1 DeltaE was released from the membrane upon incubation at 37 degrees C, which was inhibited by the specific gamma-secretase inhibitor, MW167, or by overexpression of dominant negative presenilin1. Likewise, other members of mouse Notch family were proteolytically cleaved in a presenilin-dependent, MW167-sensitive manner in vivo as well as in the cell-free Notch DeltaE cleavage assay system. All four members of the mouse Notch family migrated to the nucleus and activated the transcription from the promoter carrying the RBP-J consensus sequences after they were released from the membrane. These results demonstrate the conserved biochemical mechanism of signal transduction among mammalian Notch family members.

Amino Acid Sequence↗
PubMed2001

The effectiveness of an immobilization device in conformal radiotherapy for lung tumor: reduction of respiratory tumor movement and evaluation of the daily setup accuracy.

PURPOSE: To evaluate the daily setup accuracy and the reduction of respiratory tumor movement using a body frame in conformal therapy for solitary lung tumor. METHODS AND MATERIALS: Eighteen patients with a solitary lung tumor underwent conformal therapy using a body frame. The body shell of the frame was shaped to the patient's body contour. The respiratory tumor movement was estimated using fluoroscopy, and if it was greater than 5 mm, pressure was applied to the patient's abdomen with the goal of minimizing tumor movement. CT images were then obtained, and a treatment planning was made. A total dose of 40 or 48 Gy was delivered in 4 fractions. Portal films were obtained at each treatment, and the field displacements between them and the simulation films were measured for daily setup errors. The patients were repositioned if the setup error was greater than 3 mm. Correlations were analyzed between patient characteristics and the tumor movement, or the tumor movement reduction and the daily setup errors. RESULTS: Respiratory tumor movement ranged from 0 to 20 mm (mean 7.7 mm). The abdominal press reduced the tumor movement significantly from a range of 8 to 20 mm to a range of 2 to 11 mm (p = 0.0002). Daily setup errors were within 5 mm in 90%, 100%, and 93% of all verifications in left-right, anterior-posterior, and cranio-caudal directions, respectively. Patient repositioning was performed in 25% of all treatments. No significant correlation was detected between patient characteristics and tumor movement, tumor movement reduction, and the daily setup errors. CONCLUSIONS: The abdominal press was successful in reducing the respiratory tumor movement. Daily setup accuracy using the body frame was acceptable. Verification should be performed at each treatment in hypofractionated conformal therapy.

Adolescent↗
PubMed2001

Probable Langevin-like director reorientation in an interface-induced disordered SmC*-like state of liquid crystals characterized by frustration between ferro- and antiferroelectricity.

To clarify the thresholdless, hysteresis free V-shaped switching due to frustration between ferro- and antiferroelectricity, we have studied a prototype binary mixture system. The apparent orientational order parameters, and , obtained from polarized Raman scattering in thin homogeneous cells indicate that substrate interfaces induce some randomization of local in-plane directors at the tip of the V. Their correlation lengths, xi( parallel) approximately 3.5 nm and xi( perpendicular) approximately 75 nm, have been estimated by assuming the Langevin-like reorientation. Because of the much shorter xi(parallel) and xi(perpendicular) than the visible light wavelength, the switching process looks uniform.

Journal Article↗
PubMed2001

Protection from drug-induced hepatocellular changes by pretreatment with conjugating enzyme inhibitors in rats.

The present paper describes the role of conjugating enzymes in the development of hepatotoxicity after administration of repeated doses of a novel monoamine oxidase type-A (MAO-A) inhibitor, (5R)-3-[2-(( 1S)-3-cyano-1-hydroxypropyl)benzothiazol-6-yl]-5-methoxymethyl-2-oxazolidinone (E2011). The effects of pretreatment with three kinds of conjugating enzyme inhibitors on hepatic lesions induced by E2011 were evaluated in female Sprague-Dawley rats. The inhibitors used were 2,6-dichloro-4-nitrophenol (DCNP; inhibitor of sulfotransferase (ST)), pentachlorophenol (PCP; inhibitor of both ST and acetyltransferase (AT)) or ranitidine (inhibitor of UDP-glucuronosyltransferase (UDP-GT)). Two weeks treatment of E2011 alone at an oral dosage of 150 mg/kg induced hepatocellular changes characterized by nuclear enlargement. Daily pretreatment with DCNP (10 mg/kg, i.p.) enhanced the E2011-induced hepatocellular changes accompanied by single cell necrosis. On the other hand, the hepatotoxicity was clearly diminished by PCP (5 mg/kg, i.p.). Ranitidine pretreatment had no effect. Protection by PCP was attributed to the inhibitory effects of AT in addition to ST; it was considered that the hepatocellular changes caused by E2011 were largely dependent on the formation of acetyl conjugate(s).

Acetyltransferases↗
PubMed2001

Correlation between the age of pinealectomy and the development of scoliosis in chickens.

STUDY DESIGN: Pinealectomy induces experimental scoliosis in chickens. This study analyzed the correlation between the age at which pinealectomy was performed and the development of scoliosis in chickens. OBJECTIVE: To investigate the differences in the rate or magnitude of scoliosis and the type of curvature in chickens pinealectomized at different times after hatching. SUMMARY OF BACKGROUND DATA: Scoliosis develops in almost all chickens pinealectomized within 3 days after hatching, but there are no data on whether the condition will develop in chickens pinealectomized earlier or later after hatching. METHODS: In this study, 106 female white leghorn chickens were divided into six groups: four pinealectomy groups (pinealectomy was performed 2, 4, 11, or 18 days after hatching in Groups P-2, P-4, P-11, and P-18, respectively), a control group (Group C), and a sham operation group (Group S). Ventrodorsal radiographs of the spine were taken at 4-week intervals until the age of 12 weeks. At 12 weeks, a 1-mL sample of blood was taken from the heart at the middle of the dark cycle, and the serum melatonin concentration was measured by radioimmunoassay. RESULTS: At the age of 12 weeks, scoliosis was present in 63.6% of the chickens in Group P-2, 72.7% in Group P-4, 81% in Group P-11, and 70% in Group P-18, and the Cobb angles in the scoliotic chickens averaged 32.6, 29.8, 23.8, and 22.3 degrees in the respective groups. There were no significant differences in the rate or magnitude of scoliosis and the type of curvature among the pinealectomy groups at the age of 12 weeks. At the age of 12 weeks, the serum melatonin levels at the middle of the dark cycle in the pinealectomized chickens were significantly lower than those of chickens in Groups C and S. However, there were no differences in the serum melatonin levels between scoliotic and nonscoliotic pinealectomized chickens. CONCLUSIONS: Findings from this study show that scoliosis develops in 60% to 80% of chickens pinealectomized within 18 days after hatching, and that scoliotic development is not influenced by the age at which pinealectomy is performed. However, this study suggests that melatonin plays a complicated role in spinal development, inasmuch as the serum melatonin levels after pinealectomy approximated zero. Yet scoliosis did not develop in all pinealectomized chickens.

Aging↗
PubMed2001

Inhibition of ADAMTS4 (aggrecanase-1) by tissue inhibitors of metalloproteinases (TIMP-1, 2, 3 and 4).

ADAMTS4 (aggrecanase-1) is considered to play a key role in the degradation of aggrecan in arthritides. The inhibitory activity of tissue inhibitors of metalloproteinases (TIMPs) to ADAMTS4 was examined in an assay using aggrecan substrate. Among the four TIMPs, TIMP-3 inhibited the activity most efficiently with an IC(50) value of 7.9 nM, which was at least 44-fold lower than that of TIMP-1 (350 nM) and TIMP-2 (420 nM) and >250-fold less than that of TIMP-4 (2 microM for 35% inhibition). These results suggest that TIMP-3 is a potent inhibitor against the aggrecanase activity of ADAMTS4 in vivo.

ADAM Proteins↗
PubMed2001

Occurrence of ovalbumin in ovarian yolk of chicken during oogenesis.

Yolk specimens from chicken ovaries during oogenesis gave a positive signal for ovalbumin as analyzed by Western blotting, indicating that the ovarian yolk contains ovalbumin. Northern blotting and reverse transcriptase-polymerase chain reaction gave a negative signal for ovalbumin mRNA in the liver and other organs except oviduct, whereas the laying hen serum was found to indicate immunologically the presence of ovalbumin. It was therefore assumed that ovalbumin synthesized in the oviduct might partly be secreted into the blood circular system, from which it is taken up into the oocyte.

Animals↗
PubMed2001

The N- and C-terminal regions of RBP-J interact with the ankyrin repeats of Notch1 RAMIC to activate transcription.

The evolutionarily-conserved DNA-binding protein RBP-J directly interacts with the RAM domain and the ankyrin (ANK) repeats of the Notch intracellular region (RAMIC), and activates transcription of downstream target genes that regulate cell differentiation. In vitro binding assays demonstrate that the truncated N- and C-terminal regions of RBP-J bind to the ANK repeats but not to the RAM domain. Using an OT11 mouse cell line, in which the RBP-J locus is disrupted, we showed that RBP-J constructs mutated in the N- and C-terminal regions were defective in their transcriptional activation induced by either RAMIC or IC (the Notch intracellular region without the RAM domain) although they had normal levels of binding activity to DNA and the RAM domain. The studies using chimeric molecules between RBP-J and its homolog RBP-L showed that the N- and C-terminal regions of RBP-J conferred the IC- as well as RAMIC-induced transactivation potential on RBP-L, which binds to the same DNA sequence as RBP-J but fails to interact with RAMIC. Taken together, these results indicate that the interactions between the N- and C-terminal regions of RBP-J and the ANK repeats of RAMIC are important for transactivation of RBP-J by RAMIC.

Animals↗
PubMed2001

Functional pleiotropy of an intramolecular triplex-forming fragment from the 3'-UTR of the rat Pigr gene.

A microsatellite-containing 359-bp restriction fragment, isolated from the rat Pigr gene (murine polymeric immunoglobulin receptor gene) 3'-untranslated region (3'-UTR) and inserted into 3'-UTR or 3' flanking positions in transcription units of supercoiled plasmids, attenuates luciferase reporter gene expression in orientation- and position-dependent ways following transient transfection of human 293 cells. The same fragment stimulates orientation-dependent gene expression in a 5' flanking position. Plasmid linearization abrogates both orientation- and position-dependent responses. Cell-free translation reveals that 5' and 3' flanking expression responses are proportional to increased and decreased luciferase mRNA levels, whereas 3'-UTR expression is associated with control mRNA levels. Hypersensitivity to nucleases S1 and P1, gel mobility differences between supercoiled plasmids carrying opposing microsatellite orientations, and anomalous melting profiles of this fragment are also observed. These results suggest that functional pleiotropy of this fragment depends on the DNA context of its purine-rich microsatellite strand and on DNA supercoiling. Intramolecular triplexes stabilized by supercoiling and secondary structures of purine repeat-rich mRNAs may also confer regulatory properties to similar genomic elements.

3' Untranslated Regions↗
PubMed2001

Effects of fluvoxamine on morphine-induced inhibition of gastrointestinal transit, antinociception and hyperlocomotion in mice.

In the present study, the effects of fluvoxamine on the inhibition of gastrointestinal transit, antinociception and hyperlocomotion induced by morphine were investigated in mice. Treatment with morphine (10 mg/kg, subcutaneously (s.c.)) inhibited gastrointestinal transit and hyperlocomotion. These effects were attenuated by fluvoxamine in a dose-dependent manner. On the other hand, morphine (1 mg/kg, s.c.)-induced antinociception was significantly potentiated by fluvoxamine. These results suggest that fluvoxamine combined with morphine may be useful for the treatment of not only depression but also pain in cancer patients without constipation or activation of the mesolimbic dopaminergic system. However, further understanding and clinical studies will be required to confirm this possibility.

Analgesics, Opioid↗