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T Chiba

Publications and source records attributed to T Chiba.

At least 145 records · Page 8Linked to original sources
PubMed2000

Expression of proliferating cell nuclear antigen (PCNA) in the adult and developing mouse nervous system.

Proliferating cell nuclear antigen (PCNA) is essential for the function of DNA polymerases delta and epsilon. Because proliferating cell nuclear antigen is required for DNA replication and repair, PCNA is abundantly expressed in proliferating cells. Interestingly, PCNA mRNA has also been detected in the adult mouse brain by Northern blot analysis. In this study, two monoclonal antibodies against PCNA, PC10 and 19F4, were used for Western blot analysis. Monoclonal antibody PC10, but not 19F4, detected a band in the adult mouse brain extract. This PC10-reactive protein in the brain displayed a more acidic isoelectric point than PCNA by two-dimensional gel electrophoresis. In situ hybridization showed that PCNA mRNA was abundantly expressed in the adult mouse subventricular zone. Additionally, relatively low levels of PCNA mRNA expression were also found in neurons throughout the central nervous system, however, no hybridization was observed in the white matter. Immunohistochemistry was also performed using 19F4 and PC10, and staining of progenitor cell nuclei in the subventricular zone was observed with both antibodies. Whereas 19F4 immunostaining was restricted to progenitor cells, PC10 immunostaining was also found in postmitotic nonproliferating cell nuclei. In the cortical neuroepithelium of developing mice, the distribution of PC10 immunoreactivity was wider than that of 19F4 immunoreactivity and PCNA mRNA expression. These results suggest that proliferating cell nuclear antigen mRNA is expressed not only in proliferating cells but also in nonproliferating cells such as neurons. The protein recognized only with PC10 may be a modified, most probably a phosphorylated PCNA.

Age Factors↗
PubMed2000

Inhibitory effect of intrathecally administered nociceptin on the expression of Fos-like immunoreactivity in the rat formalin test.

Nociceptin, an opioid receptor-like 1 receptor agonist, has been reported to produce an analgesic effect in the rat formalin test. The authors examined the effect of 17 nmol of nociceptin on the expression of Fos-like immunoreactivity (Fos-LI) in the spinal dorsal horn induced by paw formalin injection and compared the effect of 17 nmol of nociceptin with that of equiantinociceptive dose (3 nmol) of morphine. Nociceptin and morphine were administered intrathecally 10 min before the formalin injection and the expression of Fos-LI was examined 2.5 h after the formalin injection. Both 17 nmol of nociceptin and 3 nmol of morphine suppressed the expression of Fos-LI in laminae I-II, but not in laminae III-V, to the same extent. These data suggest that intratheally administered nociceptin and morphine suppress the nociceptive input into the laminae I-II and produce antinociceptive effect.

Analgesics↗
PubMed2000

Implication of vascular endothelial growth factor and p53 status for angiogenesis in noninvasive colorectal carcinoma.

BACKGROUND: It still is unclear when angiogenic potential, which is believed to be a prerequisite for tumor development, is acquired. The current study was designed 1) to clarify when the phenotypic change of angiogenicity occurs during the development of colon carcinoma and 2) to investigate the possible roles of vascular endothelial growth factor (VEGF) and p53 in angiogenesis. METHODS: Colon carcinomas were classified according to the following criteria: m carcinomas were tumors in which carcinoma cells were observed within the mucosa (excluding adenomas with severe atypia) according to the World Health Organization criteria. sm carcinomas were defined by invasion into the submucosa but not into the muscularis propria. Using 27 adenomas, 26 m carcinomas, and 20 sm carcinomas, VEGF expression was analyzed with reverse transcriptase-polymerase chain reaction and immunohistochemistry. Microvessel density, VEGF, and p53 status were evaluated by immunohistochemistry. RESULTS: Neither VEGF mRNA nor VEGF protein was detected in any of the mild-to-moderate dysplastic adenomas, whereas 16 of 26 m carcinomas (62%) and all sm carcinomas exhibited VEGF protein. The microvessel density in adenomas, m carcinomas, and sm carcinomas was 3 +/- 0.55, 6.1 +/- 1.12, and 12 +/- 1.35 (0.739 mm(2) per field), respectively. In m carcinomas, positive VEGF expression was coincident with the expression of p53, and stainability for both VEGF and p53 was similar with regard to spatial distribution in tumor tissues. In m and sm carcinomas, there was a statistically significant correlation between the intensity of VEGF expression and microvessel density. CONCLUSIONS: The results of the current study demonstrated that angiogenesis develops in association with tumor progression from adenoma to noninvasive colorectal carcinoma, at least in part due to VEGF, and suggested that VEGF in m carcinomas is induced by mutant p53, although alternative mechanisms of VEGF up-regulation may exist in sm carcinomas.

Adenoma↗
PubMed2000

Nonselective cation and BK channels in apical membrane of outer sulcus epithelial cells.

The outer sulcus epithelium was recently shown to absorb cations from the lumen of the gerbil cochlea. Patch clamp recordings of excised apical membrane were made to investigate ion channels that participate in this reabsorptive flux. Three types of channel were observed: (i) a nonselective cation (NSC) channel, (ii) a BK (large conductance, maxi K or K(Ca)) channel and (iii) a small K(+) channel which could not be fully characterized. The NSC channel found in excised insideout patch recordings displayed a linear current-voltage (I-V) relationship (27 pS) and was equally conductive for Na(+) and K(+), but not permeable to Cl(-) or N-methyl-d-glucamine. Channel activity required the presence of Ca(2+) at the cytosolic face, but was detected at Ca(2+) concentrations as low as 10(-7) m (open probability (P(o)) = 0.11 +/- 0.03, n = 8). Gadolinium decreased P(o) of the NSC channel from both the external and cytosolic side (IC(50) approximately 0.6 microm). NSC currents were decreased by amiloride (10 microm - 1 mm) and flufenamic acid (0.1 mm). The BK channel was also frequently (38%) observed in excised patches. In symmetrical 150 mm KCl conditions, the I-V relationship was linear with a conductance of 268 pS. The Goldman-Hodgkin-Katz equation for current carried solely by K(+) could be fitted to the I-V relationship in asymmetrical K(+) and Na(+) solutions. The channel was impermeable to Cl(-) and N-methyl-d-glucamine. P(o) of the BK channel increased with depolarization of the membrane potential and with increasing cytosolic Ca(2+). TEA (20 mm), charybdotoxin (100 nm) and Ba(2+) (1 mm) but not amiloride (1 mm) reduced P(o) from the extracellular side. In contrast, external flufenamic acid (100 microm) increased P(o) and this effect was inhibited by charybdotoxin (100 nm). Flufenamic acid inhibited the inward short-circuit current measured by the vibrating probe and caused a transient outward current. We conclude that the NSC channel is Ca(2+) activated, voltage-insensitive and involved in both constitutive K(+) and Na(+) reabsorption from endolymph while the BK channel might participate in the K(+) pathway under stimulated conditions that produce an elevated intracellular Ca(2+) or depolarized membrane potential.

Animals↗
PubMed2000

Toward a protein-protein interaction map of the budding yeast: A comprehensive system to examine two-hybrid interactions in all possible combinations between the yeast proteins.

Protein-protein interactions play pivotal roles in various aspects of the structural and functional organization of the cell, and their complete description is indispensable to thorough understanding of the cell. As an approach toward this goal, here we report a comprehensive system to examine two-hybrid interactions in all of the possible combinations between proteins of Saccharomyces cerevisiae. We cloned all of the yeast ORFs individually as a DNA-binding domain fusion ("bait") in a MATa strain and as an activation domain fusion ("prey") in a MATalpha strain, and subsequently divided them into pools, each containing 96 clones. These bait and prey clone pools were systematically mated with each other, and the transformants were subjected to strict selection for the activation of three reporter genes followed by sequence tagging. Our initial examination of approximately 4 x 10(6) different combinations, constituting approximately 10% of the total to be tested, has revealed 183 independent two-hybrid interactions, more than half of which are entirely novel. Notably, the obtained binary data allow us to extract more complex interaction networks, including the one that may explain a currently unsolved mechanism for the connection between distinct steps of vesicular transport. The approach described here thus will provide many leads for integration of various cellular functions and serve as a major driving force in the completion of the protein-protein interaction map.

DNA, Fungal↗
PubMed2000

Homodimer of two F-box proteins betaTrCP1 or betaTrCP2 binds to IkappaBalpha for signal-dependent ubiquitination.

We found previously that overexpression of an F-box protein betaTrCP1 and the structurally related betaTrCP2 augments ubiquitination of phosphorylated IkappaBalpha (pIkappaBalpha) induced by tumor necrosis factor-alpha (TNF-alpha), but the relationship of the two homologous betaTrCP proteins remains unknown. Herein we reveal that deletion mutants of betaTrCP1 and betaTrCP2 lacking the F-box domain suppressed ubiquitination and destruction of pIkappaBalpha as well as transcriptional activation of NF-kappaB. The ectopically expressed betaTrCP1 and betaTrCP2 formed both homodimer and heterodimer complexes without displaying the trimer complex. Dimerization of betaTrCP1 and/or betaTrCP2 takes place at their conserved NH(2)-terminal regions, termed a "D-domain" (for dimerization domain), located upstream of the F-box domain. The D-domain was necessary and sufficient for the dimer formation. Intriguingly, the betaTrCP homodimer, but not the heterodimer, was selectively recruited to pIkappaBalpha induced by TNF-alpha. These results indicate that not only betaTrCP1 but also betaTrCP2 participates in the ubiquitination-dependent destruction of IkappaBalpha by forming SCF(betaTrCP1-betaTrCP1) and SCF(betaTrCP2-betaTrCP2) ubiquitin-ligase complexes.

Base Sequence↗
PubMed2000

Identification of a novel alternative splicing of human FGF receptor 4: soluble-form splice variant expressed in human gastrointestinal epithelial cells.

Among four closely related members of the FGF receptor family, FGFR 1, 2, and 3 have alternative splicing forms encoded by different exons for the C-terminal half of the third Ig-like domain, but FGFR 4 has no such alternative exon. Furthermore, FGFR 1, 2, and 3 have another splice variant of nontransmembrane type; however, such a variant has not been reported for FGFR 4. While searching for a novel receptor-type tyrosine kinase by RT-PCR, we identified a non-transmembrane-type receptor of FGFR 4 in human intestinal epithelial cell lines (Intestine 407 and Caco-2). Sequence analysis of this receptor revealed that exon 9 coding the single transmembrane domain was displaced by intron 9. Consequently, this variant form was 120 bp shorter than the normal form and had no transmembrane portion. Moreover, the signal sequence in exon 2 was maintained, suggesting that this splice variant is a soluble receptor. This soluble receptor was detected in human gastrointestinal epithelial cells and pancreas, and also in gastric, colon, and pancreatic cancer cell lines. Single cell RT-PCR showed that this soluble receptor was expressed simultaneously with the transmembrane-type receptor in the same cell. Western blot analysis revealed that this receptor was secreted from the transfected COS7 cells. Thus, a soluble-form splice variant of FGFR 4 was identified in human gastrointestinal epithelial cells and cancer cells. This is the first report of alternative splicing of FGFR 4.

Alternative Splicing↗
PubMed2000

Latent hepatitis B virus infection in healthy individuals with antibodies to hepatitis B core antigen.

Several recent reports have shown that hepatitis B virus (HBV) could be frequently transmitted to the recipients from donors who have antibodies to hepatitis B core antigen (anti-HBc) through liver transplantation. We provide here the molecular evidence of latent HBV infection accompanied with ongoing viral replication in the liver tissue of anti-HBc-positive healthy individuals. HBV DNA was detectable in 13 of 14 healthy donors who were positive for both anti-HBc and antibodies to hepatitis B surface antigen (anti-HBs), but in none of 3 who were positive for anti-HBs alone. The detected HBV genomes from these subjects included covalently closed circular DNA and pregenomic RNA, the replication intermediate of HBV. Notably, 5 of 7 cases tested were predominantly infected with wild type HBV strains without any mutations in the precore and core promoter regions under the presence of circulating antibody to hepatitis B e antigen. Interestingly, a predominant clone detected in one donor showed a 63-nucleotide deletion in the precore region including an encapsidation signal sequence. Our findings indicate that the majority of healthy individuals positive for anti-HBc, which had been assumed to denote a past history of transient HBV infection, were latently infected with the episomal form of HBV accompanied by ongoing viral replication and few nucleotide mutations in the precore and core regions.

Adult↗
PubMed2000

Immunohistochemical localization of cathepsin D in colorectal tumors.

PURPOSE: Although it has been suggested that cathepsin D, a lysosomal protease, is involved in tumor invasion and metastasis in human colorectal cancers, conflicting studies have also been reported recently. In addition, this issue has been only rarely studied in human colorectal tumors by use of immunohistochemical methods. The aim of the study presented here was to clarify not only the correlation between cathepsin D expression and tumor invasion or metastasis but also the correlation between the intracellular immunostaining pattern of cathepsin D and tumor invasion and metastasis in human colorectal tumors. METHODS: Thirty-four primary colorectal adenocarcinomas and 24 adenomas were immunostained by use of an anticathepsin D antibody. Both the incidence and the immunostaining patterns of cathepsin D were investigated in all tissue samples. RESULTS: Three different immunostaining patterns, i.e., supranuclear, basal, and diffuse, were observed in samples containing cathepsin D. Although the incidence of cathepsin D-positive carcinomas was not correlated with tumor progression, invasion, or metastasis, the immunostaining pattern was significantly correlated with lymphatic invasion. CONCLUSIONS: The results of this study suggest that abnormal cathepsin D immunostaining patterns (basal or diffuse) can be used to predict a potential for lymphatic invasion in colorectal carcinoma.

Adenocarcinoma↗
PubMed2000

Effects of Helicobacter pylori infection on Zollinger-Ellison syndrome.

Both Zollinger-Ellison syndrome (ZES) and Helicobacter pylori infection are major etiologic factors for peptic ulcer. The aim of this study was to investigate the effect of H. pylori infection on ZES with special reference to acid secretion. Sixteen patients with ZES were selected (median age, 59 years; range, 39-66 years; M/F, 9/7), and H. pylori status, ulcer location, gastric acid secretion, serum pepsinogen (PG) I and II concentrations, and PG I/II ratio were determined. The seroprevalence of H. pylori infection was 50%, whereas active H. pylori infection was seen in only 25% of the patients. Thirteen patients had duodenal ulcer (DU), 1 had gastric ulcer (GU), and 2 had both GU and DU. DU was seen in both H. pylori-positive and H. pylori-negative patients, whereas GU was found only in H. pylori-positive patients. Both basal and maximal acid outputs were significantly lower in H. pylori-positive patients than in H. pylori-negative patients (P< 0.05). Moreover, both serum PG I and the PG I/II ratio were significantly lower in H. pylori-positive patients than in H. pylori-negative patients. These results indicate that ZES is an independent risk factor for DU, but H. pylori infection may play some role in the development of GU in ZES. In patients with ZES, H. pylori infection may reduce both hypersecretion from parietal cells and PG I secretion from chief cells, and hyperacidity of the stomach in ZES may have eradicated H. pylori in some patients.

Adult↗
PubMed2000

Autoimmune-related pancreatitis is associated with autoantibodies and a Th1/Th2-type cellular immune response.

BACKGROUND & AIMS: Although autoimmunity may be involved in some cases of pancreatitis, the mechanism is still unknown. To clarify this, we studied serum autoantibodies, subsets of lymphocytes, and the Th1/Th2 balance of cellular immune responses in patients with autoimmune-related pancreatitis (AIP). METHODS: Seventeen patients with AIP (8 men and 9 women; age, 53.2 +/- 13.0 years) were studied. Autoantibodies including antilactoferrin (ALF) or carbonic anhydrase II antibody (ACA-II) were examined using the enzyme-linked immunosorbent assay (ELISA) or the indirect fluorescein antibody method. Intracellular cytokines (interferon gamma and interleukin 4) and subtypes of peripheral blood lymphocytes were examined by flow cytometry and ELISA. RESULTS: More than one autoantibody was observed in all 17 patients. Serum antinuclear antibody was detected in 13 of 17 patients, ALF antibody in 13, ACA-II antibody in 10, rheumatoid factor in 5, and anti-smooth muscle antibody in 3, but antimitochondrial antibody in none. The serum levels of ACA-II and LF antibody were not correlated. HLA-DR(+)CD8(+) and HLA-DR(+)CD4(+) cells were significantly increased in peripheral blood (P < 0.05). CD4(+) cells producing interferon gamma and the secreted levels were significantly increased compared with those in controls (P < 0.05), but interleukin 4 was not increased. CONCLUSIONS: An autoimmune mechanism against CA-II or LF, and Th1-type immune response, may be involved in AIP.

Adult↗
PubMed2000

Neonatal capsaicin treatment decreased substance P receptor immunoreactivity in lamina III neurons of the dorsal horn.

Using immunohistochemistry and in situ hybridization technique, the distribution of substance P (SP) and SP receptors was studied in the dorsal horn of the rat spinal cord after neonatal capsaicin treatment. Sprague-Dawley rats administered 100 mg/kg of capsaicin subcutaneously within 24 h after birth were examined at 8 weeks of age. In the capsaicin administered rats, slight reduction of SP immunoreactivities in lamina I, and severe decrease in lamina II were observed. In the control group, SP receptor-mRNA was observed in all laminae, and SP receptor-immunoreactivities were seen to be intense in laminae I and III. In contrast, in the capsaicin administered rats, the SP receptor-mRNA expression was low in laminae II-V, and SP receptor immunoreactivities decreased in laminae III-V. Furthermore, the density of the SP receptor immunoreactivities was considerably decreased in the nerve cells of lamina III. We concluded that elevation of the threshold to painful stimulation in rats was as a result of the decrease in SP immunoreactive afferent fibers in laminae I and II, decrease of the SP receptor-mRNA in the laminae II-V, or the decrease in SP receptor immunoreactive neurons in laminae III-V.

Animals↗
PubMed2000

Collateral projection from the amygdalo--hippocampal transition area and CA1 to the hypothalamus and medial prefrontal cortex in the rat.

Amygdaloid and hippocampal neurons projecting to both the medial prefrontal cortex and hypothalamus by way of axon collaterals were examined in the rat by double labeling method using fluorescence retrograde tracers. Fluoro-gold was injected in the medial prefrontal cortex, while Fluoro-red was injected into the ventromedial and ventral premammillary nuclei of the hypothalamus. The results indicated that neurons which sent axon collaterals to both the medial prefrontal cortex and hypothalamus constituted 50 or 30% of populations of medial prefrontal cortex-projecting neurons in the amygdalo-hippocampal transition area or in CA1, respectively. Possible roles of the neurons with axon collaterals in sexually related aggressive and/or defensive behavior were discussed.

Amygdala↗
PubMed2000

Morphological change of substance P receptor immunoreactive dendrites of preganglionic sympathetic neurons.

Substance P (SP)-containing terminals and SP receptors (SPRs) are found on the dendrites of preganglionic sympathetic neurons (PSNs) in the intermedio-lateral nucleus (IML) of the spinal cord. The SP-containing fibers were thought to be of supraspinal origin. However, the primary sensory nerve fibers terminated around PSNs, and some of them directly on PSNs. We observed approximately 150 SPR-immunoreactive (ir) varicosities on the dendrites of PSNs in slices of the first thoracic segment (T1) in control rats. The number of varicosities decreased to 41% 14 days after hemisection of the spinal cord at the fourth cervical segment (C4), and to 55% 14 days after sectioning the spinal dorsal roots at the C8 and T1 levels. The number of varicosities decreased by 33% in 8-week-old rats which had been administered capsaicin subcutaneously within 24 hours after birth to eradicate unmyelinated sensory fibers. However, varicosities increased by 15% 15 minutes after injection of capsaicin into the plantar surface of the front paw to stimulate somatosensory nerve fibers in adult rats. The results demonstrate that SPR-ir varicosities on the dendrites of PSNs were modulated not only by the supraspinal nervous system but also directly by the primary sensory nerve terminals.

Animals↗
PubMed2000

Green tea polyphenols (flavan 3-ols) prevent oxidative modification of low density lipoproteins: an ex vivo study in humans.

Oxidation of low density lipoprotein (LDL) plays crucial roles in atherogenesis. We previously reported that green tea polyphenols (flavan 3-ols), especially epigallocatechingallate (EGCg) and epicatechingallate, exerted potent inhibitory effects on LDL oxidation in vitro. To examine whether intake of green tea polyphenols renders LDL resistant to ex vivo oxidation in humans, 22 male volunteers aged between 22 and 32 years were recruited and assigned the same dietary regimen for 2 weeks. After a 1-week baseline period, they were equally divided into two groups: control and tea. The tea group ingested 300 mg of green tea polyphenol extract twice daily for 1 week. Plasma EGCg concentration at the end of the experiment was 56 nmol/L on average (56% in free form) in the tea group; no EGCg was detected before the experiment. Plasma concentrations of lipids, ascorbate, alpha-tocopherol, and lipid peroxides did not change before and after the experiment in either group, but beta-carotene was higher in the tea group (P< 0.01 by paired Student'st-test). LDL (0.1 mg/mL) was incubated with 5 microM Cu(2+) and the oxidation was measured by absorbance at 234 nm. The lag time was significantly prolonged by 13.7 min in the tea group (P < 0.05 by paired Student'st-test, before versus after), whereas such a change was not observed in the control group. These results suggest that daily consumption of seven to eight cups (approximately 100 mL each cup) of green tea may increase resistance of LDL to in vivo oxidation, leading to reduction in the risk of cardiovascular diseases.

Journal Article↗
PubMed2000

Glycosylated human interleukin-1alpha, neoglyco IL-1alpha, coupled with N-acetylneuraminic acid exhibits selective activities in vivo and altered tissue distribution.

In order to study the effect of glycosylation on its biological activities and to develop IL-1 with less deleterious effects, N-acetylneuraminic acid (NeuAc) with C9 spacer was chemically coupled to human recombinant IL-1alpha. NeuAc-coupled IL-1alpha (NeuAc-IL-1alpha) exhibited reduced activities in vitro and receptor-binding affinities by about ten times compared to IL-1alpha. In this study, we examined a variety of IL-1 activities in vivo. NeuAc-IL-1alpha exhibited a marked reduction in the activity to up-regulate serum IL-6, moderate reduction in the activities to up-regulate serum amyloid A and NOx. However, it exhibited comparable activities as IL-1alpha to down-regulate serum glucose and to improve the recovery of peripheral white blood cells from myelosuppression in 5-fluorouracil-treated mice. In addition, tissue level of NeuAc-IL-1alpha was high compared to IL-1alpha. These results indicate that coupling with NeuAc enabled us to develop neo-IL-1 with selective activities in vivo and enhanced tissue level.

Animals↗
PubMed2000

Familial Parkinson disease gene product, parkin, is a ubiquitin-protein ligase.

Autosomal recessive juvenile parkinsonism (AR-JP), one of the most common familial forms of Parkinson disease, is characterized by selective dopaminergic neural cell death and the absence of the Lewy body, a cytoplasmic inclusion body consisting of aggregates of abnormally accumulated proteins. We previously cloned PARK2, mutations of which cause AR-JP (ref. 2), but the function of the gene product, parkin, remains unknown. We report here that parkin is involved in protein degradation as a ubiquitin-protein ligase collaborating with the ubiquitin-conjugating enzyme UbcH7, and that mutant parkins from AR-JP patients show loss of the ubiquitin-protein ligase activity. Our findings indicate that accumulation of proteins that have yet to be identified causes a selective neural cell death without formation of Lewy bodies. Our findings should enhance the exploration of the molecular mechanisms of neurodegeneration in Parkinson disease as well as in other neurodegenerative diseases that are characterized by involvement of abnormal protein ubiquitination, including Alzheimer disease, other tauopathies, CAG triplet repeat disorders and amyotrophic lateral sclerosis.

Humans↗