Biomedical subjects

T Arai

Publications and source records attributed to T Arai.

At least 145 records · Page 8Linked to original sources

PubMed2000

Endogenous AP-1 levels necessary for oncogenic activity are higher than those sufficient to support normal growth.

We investigated the role of endogenous AP-1 in human tumor cell lines by introducing SupJunD-1, a dominant-negative mutant of AP-1, using vesicular stomatitis virus G protein (VSV-G)-pseudotyped retrovirus vectors. Single inoculation of six human tumor cell lines, originating from osteosarcomas, non-small cell lung carcinomas or cervical carcinomas, with recombinant SupJunD-1 virus at a high multiplicity of infection readily inhibited colony formation in soft agar. We detected no significant changes in expression levels of AP-1 components c-Jun or Fra-1, adhesion molecules CD44 or E-cadherin, or cell cycle regulator p53, which are encoded by genes previously reported to be under the control of AP-1 in some mouse or human cell lines. By varying the dosage of VSV-G-pseudotyped retrovirus, we were able to change the proviral copy number of supjunD-1 from 1 to approximately 10 and monitor suppression of endogenous AP-1 function as assessed by growth characteristics of the tumor cell lines, we found a SupJunD-1 dosage which significantly suppressed anchorage-independent growth without affecting the cellular growth in monolayer cultures at all. We conclude that endogenous AP-1 levels necessary for oncogenic activity are much higher than those sufficient to support normal growth.

3T3 Cells↗

PubMed2000

Cloning of an auxin-responsive 1-aminocyclopropane-1-carboxylate synthase gene (CMe-ACS2) from melon and the expression of ACS genes in etiolated melon seedlings and melon fruits.

Two cDNA fragments (pCMe-ACS2 and 3) encoding auxin-responsive 1-aminocyclopropane-1-carboxylate synthase (ACS; EC.4.4.1.14) have been isolated from melon, and the expression patterns of the genes in etiolated melon seedlings and melon fruit have been determined by RT-PCR analysis. The deduced amino acid sequences of pCMe-ACS2 and 3 were homologous to those of AT-ACS6 and 4, which were auxin-responsive ACS genes of Arabidopsis. Both CMe-ACS2 and 3 were auxin-responsive ACS genes and their expressions in roots and hypocotyls were induced by treatment with indole acetic acid (IAA, 100 µM). The mRNA level of CMe-ACS2 in the fruit increased after pollination. Those of both CMe-ACS2 and 3 temporarily increased in the mesocarp tissues at the preclimacteric stage (from day 3 to day 5 after harvest) during ripening, while that of CMe-ACS3 was lower than that of CMe-ACS2. The increase in the mRNA level of CMe-ACS1 (wound- and ripening-induced gene, T. Miki, M. Yamamoto, N. Nakagawa, O. Ogura, H. Mori, H. Imaseki, T. Sato, Nucleotide sequence of a cDNA for 1-aminocyclopropane-1-carboxylate synthase from melon fruits, Plant Physiol. 107 (1995) 297-298.) in the mesocarp tissue was not observed until 5 days after harvest. A genomic DNA encoding CMe-ACS2 was isolated and its nucleotide sequence was determined. Nucleotide sequences resembling the auxin-responsive elements (AuxRE) D1 and D4 (the TGTCTC element) in the GH3 gene from soybean, and the auxin-responsive domain (AuxRD) B in PS-IAA4/5 from pea were found in the 5'-flanking region of the CMe-ACS2 gene.

Journal Article↗

PubMed2000

Correlation of telomere lengths in normal and cancers tissue in the large bowel.

The hypothesis that telomeres in colorectal cancer cells exhibit age-related shortening, as in normal cells of the colorectal epithelium, was tested with samples of non-cancerous mucosa and cancer tissue from 124 patients (aged 29-97 years). Shortening with aging could be demonstrated for both normal and cancer tissues; regression analysis showed rates for length reduction of 44 and 50 base pair/year, respectively. Straight, essentially parallel, lines were obtained for the two cases, normal tissue values being about 2 kilobase pairs (kbp) higher, with a significant correlation between data at the individual patient level.

Adult↗

PubMed2000

Historical trends in lake and river ice cover in the northern hemisphere

Freeze and breakup dates of ice on lakes and rivers provide consistent evidence of later freezing and earlier breakup around the Northern Hemisphere from 1846 to 1995. Over these 150 years, changes in freeze dates averaged 5.8 days per 100 years later, and changes in breakup dates averaged 6.5 days per 100 years earlier; these translate to increasing air temperatures of about 1.2 degrees C per 100 years. Interannual variability in both freeze and breakup dates has increased since 1950. A few longer time series reveal reduced ice cover (a warming trend) beginning as early as the 16th century, with increasing rates of change after about 1850.

Journal Article↗

PubMed2000

Geranylgeranylacetone enhances expression of thioredoxin and suppresses ethanol-induced cytotoxicity in cultured hepatocytes.

Geranylgeranylacetone (GGA) has been introduced into the clinical field as an anti-ulcer drug. In addition to protective effects on gastric mucosal cells, GGA also has anti-apoptotic effects against ischemia and reperfusion injury in hepatocytes and intestinal cells. However, the molecular mechanisms of the cytoprotective or anti-apoptotic effect of GGA are largely unknown. To explore the molecular mechanism of GGA action, we focused on thioredoxin (TRX), an endogenous-redox-acting molecule. We have demonstrated that GGA induces the messenger RNA and protein of TRX and affects the activation of transcription factors, AP-1 and NF-kappaB, and that GGA blunted ethanol-induced cytotoxicity of cultured hepatocytes. These results provide evidence suggesting that a possible novel molecular mechanism of GGA is to protect cells via the induction of TRX and the activation of transcription factors such as NF-kappaB and AP-1.

Animals↗

PubMed2000

Collateral sprouting from sensory and motor axons into an end to side attached nerve segment.

A nerve segment, sutured end-to-side (ETS) to an intact rat sciatic nerve, becomes invaded by regenerating axons. The origin of these fibres is controversial: it is debated whether or not they represent collateral sprouts from intact axons. Here we demonstrate by double retrograde tracing, using one tracer for the ETS attached segment and another for the sciatic nerve proper double-labelled sensory neurons in 67% of the rats receiving an ETS segments. Double-labelled motor neurons were observed in 11% of the rats. The results show that a nerve segment attached ETS to an intact nerve can induce collateral sprouting of both sensory and motor axons although the extent of such branching may vary with the experimental conditions.

Animals↗

PubMed2000

The cloning and nucleotide sequence of human ST2L cDNA.

The ST2 gene is a member of the IL-1 receptor family and is hypothesized to be involved in helper T cell function, but its functional ligand and physiological role remain unknown. We have cloned the human ST2L cDNA that encodes a distinct type of membrane-bound ST2 protein. The predicted 556-amino-acid sequence showed 67% identity to the mouse ST2L protein. The human ST2 gene (IL1RL1) contains 13 exons and spans 40 kb in length. Its exon-intron organization was elucidated from a registered human genomic sequence derived from chromosome 2q, which contains three other genes belonging to the IL-1 receptor family in an approximately 202-kb genomic region. The tissue distribution of ST2 expression was examined by RT-PCR, and the soluble form (ST2, IL1RL1-a) and ST2L (IL1RL1-b) appear to be expressed differentially. We also established stable transfectants of a human glioblastoma cell line, T98G, that express human ST2L constitutively, and we confirmed cell-surface expression of human ST2L protein on the transfectants.

Amino Acid Sequence↗

PubMed2000

Progesterone receptor is a favorable prognostic factor of radiation therapy for adenocarcinoma of the uterine cervix.

PURPOSE: The prognostic significance of the expression of estrogen receptors (ER) and progesterone receptors (PgR) in adenocarcinoma of the uterine cervix has been controversial. Hence, the relationship between the expression of the hormone receptors and clinical outcome was evaluated for patients with adenocarcinoma treated with radiation therapy alone. MATERIALS AND METHODS: This study involved 66 patients with cervical adenocarcinoma consisting of 44 adenocarcinomas and 22 adeno-squamous cell carcinomas. They received radiation therapy at the National Institute of Radiological Sciences Hospital between 1962 and 1993. The mean age of the patients was 62. 0 +/- 12.0 years (range, 36-82 years). The numbers of patients with Stage I, II, III, and IV diseases were 7, 17, 27, and 15, respectively. Their ER and PgR statuses were investigated immunohistochemically using biopsy specimens excised from the cervical tumors before radiation therapy. RESULTS: ER staining was positive in 12 patients (19%). ER status did not correlate with the 5-year cause-specific, local-control, and disease-free survivals. PgR staining was positive in 12 patients (19%). The disease-free survival rate of PgR-positive patients was significantly higher than that of PgR-negative patients (p = 0.044). Although PgR status did not reach statistical significance in relation to the 5-year cause-specific survival and local-control survival, the better survival was due to less local recurrence rather than to less distant metastasis. CONCLUSION: The present study suggested that PgR status was associated with prognosis after radiation therapy for adenocarcinoma of the uterine cervix.

Adenocarcinoma↗

PubMed2000

Different roles of neuronal and endothelial nitric oxide synthases on ischemic nitric oxide production in gerbil striatum.

The production of nitric oxide (NO) in gerbil striatum during ischemia and reperfusion was monitored by measuring total NO metabolites in dialysates, and the effects of 7-nitroindazole (7-NI), a selective inhibitor of neuronal NO synthase, and N(G)-nitro-L-arginine methyl ester (L-NAME), a non-selective inhibitor of NO synthase, were examined. The effects of these agents on ischemic neuronal damage were histologically evaluated 7 days after transient ischemia for 5 or 10 min. 7-NI and L-NAME decreased the NO production to similar extents in non-ischemic gerbils. 7-NI inhibited the increased NO production after 5 min of ischemia, and partly attenuated the increase in NO production after 10 min of ischemia, but had no effect on the increase after 15 min of ischemia. L-NAME completely abolished the increased NO production after different durations of ischemia. The extent of ischemic neuronal damage by 5-min ischemia was aggravated by either 7-NI or L-NAME, while damage by 10-min ischemia was marked in all groups. These results indicate that neuronal and endothelial NO synthases make different contributions to the post-ischemic NO production and the histological outcomes in gerbil striatum.

Animals↗

PubMed2000

Functional Fv fragment of an antibody specific for CD28: Fv-mediated co-stimulation of T cells.

The most predominant co-stimulation pathway, which is critical for T cell activation and proliferation, is the CD28-B7 pathway. The anti-CD28 monoclonal antibody (mAb) also provides a co-stimulatory signal to T cells. In order to construct a functional Fv fragment (complex of VH and VL domains) of anti-CD28 antibody using a bacterial expression system, cDNA encoding the variable regions of immunoglobulin from 15E8 hybridoma cells was cloned and expressed in Escherichia coli. The Fv fragment was obtained as a soluble protein from the periplasmic fraction and showed a binding pattern similar to parental IgG. The Fv fragment induced proliferation of peripheral blood mononuclear cells in the presence of anti-CD3 or anti-CD2 mAb and enhanced anti-tumor activity of anti-MUC1x(anti)-CD3 bispecific antibody when tested with lymphokine-activated killer cells with T cell phenotype. Thus, the anti-CD28 Fv fragment will be promising not only for the study of co-stimulation, but also for cancer immunotherapy.

Amino Acid Sequence↗

PubMed2000

Tumor thickness is a histopathologic predictive parameter of tumor metastasis and prognosis in patients with Dukes stage C ulcerative-type colorectal carcinoma. A two-hospital-based study.

BACKGROUND: Metastasis to the liver or lymph nodes is an important prognostic factor in patients with colorectal carcinoma. The purpose of the current study was to estimate the power of tumor thickness in predicting metachronous liver metastasis (MLM), lymph node metastasis (LNM), or overall survival (OS) in patients at two hospitals (the National Cancer Center Hospital [NCCH] and the National Cancer Center Hospital East [NCCHE]) to confirm the reproducibility of the study. METHODS: The subjects of this study were 74 and 186 consecutive patients with ulcerative-type colorectal carcinoma treated at the NCCH and NCCHE, respectively. Tumor thickness was measured in three areas: 1) the marginal elevated area (MEA), 2) the central depressed area (CDA), and 3) the most thickened area (MTA). Studies were performed with well known histologic parameters to compare the predictive power of tumor thickness on MLM, LNM, and OS using the Cox proportional hazards regression model or analysis of variance. RESULTS: A significant correlation between tumor thickness and MLM was observed only in the CDA in the NCCH patients (P = 0.005). The authors applied a tumor thickness cutoff value in the CDA of 10 mm (</= 10 mm and > 10 mm) for further study. Multivariate analyses demonstrated that a tumor CDA thickness > 10 mm was associated significantly with MLM, multiple LNMs, and OS in NCCH patients with Dukes Stage C disease (P = 0.002, P = 0.023, and P = 0.002, respectively). A significant predictive power for tumor CDA thickness for MLM, multiple LNMs, and OS was confirmed by multivariate analysis in NCCHE patients with Dukes Stage C disease (P = 0.008, P = 0.021, and P = 0.010, respectively). CONCLUSIONS: The CDA thickness of the tumor was found to be a useful predictive parameter for MLM, multiple LNMs, and OS in patients with Dukes Stage C ulcerative-type colorectal carcinoma who were being treated in two independent hospitals.

Aged↗

PubMed2000

Single low-dose administration of human recombinant hepatocyte growth factor attenuates intimal hyperplasia in a balloon-injured rabbit iliac artery model.

BACKGROUND: Previous studies have shown that repeated systemic administration of human recombinant hepatocyte growth factor (hrHGF) in mg/kg levels modulates the wound-healing process in various diseases. Recently, HGF has been characterized as one of the most potent endothelial-cell-specific growth factors. We tested our hypothesis that local delivery of hrHGF, even at low microg/kg levels (> or =2 orders of magnitude lower than systemically administered doses), might attenuate neointimal hyperplasia in response to vascular injury via accelerated reendothelialization. METHODS AND RESULTS: The iliac artery was denuded in 16 New Zealand White rabbits (3 kg), followed by administration, via a drug delivery catheter, of either hrHGF (10 microg; n = 11) or control vehicle (n=5) over 20 minutes. In pilot studies using this device, the drug permeated into the medial tissues, where it persisted for > or =24 hours. Four weeks after the local delivery of hrHGF, computer-assisted morphometric analysis revealed significant reduction in the intimal area (hrHGF, 0.37+/-0.21 versus control, 0.68+/-0.16 mm(2), mean +/- SD; P<0.05) but no change in the medial area (hrHGF, 1.03+/-0.21 versus control, 1.10+/-0.52 mm(2)). Scanning electron microscopy revealed extensive endothelialization with regular and confluent endothelial cell layer regeneration in the hrHGF-treated vessels. CONCLUSIONS: Accelerated endothelialization after local delivery of hrHGF, a novel and potent endothelial cell mitogen, effectively attenuates neointimal proliferation even after single low-dose administration. This observation could have potential therapeutic implications in the prevention of restenosis after angioplasty.

Animals↗

PubMed2000

Neurons containing Alz-50-immunoreactive granules around the cerebral infarction: evidence for the lysosomal degradation of altered tau in human brain?

Little is known about the metabolic process of tau and tau-derived substances. Alz-50- and tau 2-immunoreactivities in intracellular granules of neurons were observed in regions surrounding infarcted foci in the human cerebral cortex. Ultrastructurally, these granules in the fresh infarcted region exhibited primary lysosome-like structures, while those in old infarctions were lipofuscin. These findings indicate that tau is metabolized within lysosomes in neurons damaged by ischemic injury in human cortical penumbra. Alz-50-positive granules were more prominent in fresh infarction than in old infarction. After undergoing degradation and modification, altered tau might remain, at least partially, in secondary lysosomes.

Aged↗

PubMed2000

Synergism between the calmodulin-binding and autoinhibitory domains on calcineurin is essential for the induction of their phosphatase activity.

Elevation of the intracellular calcium concentration is necessary for cell growth and the activation of several lymphokine genes. The immunosuppressive drugs cyclosporin A and FK506 profoundly inhibit the calcium-dependent signaling pathway in T lymphocytes by interfering with the activity of the calcium/calmodulin (CaM)-dependent serine/threonine phosphatase, calcineurin (CN). Little is known, however, about how activation of CN enzyme activity or interaction with its substrate, nuclear factor of activated T cell (NF-AT), is regulated. We show here that the binding of CaM to CN may affect the conformation of CN at both the CaM-binding and the autoinhibitory (AI) domains and that this is critical for activation of CN to dephosphorylate NF-AT. Dissociation of the AI domain from the enzyme active site on CN leads to expose a binding site for NF-AT at the N terminus of CN and allows the CN binding to NF-AT. Since the cytoplasmic form of NF-AT can interact with CN mutants lacking enzyme activity, the interaction of the two molecules is independent of CN enzyme activity and occurs prior to the dephosphorylation of NF-AT. Dephosphorylation converts NF-AT from the cytoplasmic to the nuclear form by exposing the DNA-binding domain on NF-AT, and the nuclear form of NF-AT brings CN together into the nuclei. We therefore propose that the activation of CN by the CaM binding independently regulates the interaction with NF-AT and the dephosphorylation of NF-AT.

3T3 Cells↗

PubMed2000

New amphiphilic aminosaccharide derivatives as chiral selectors in capillary electrophoresis.

Two amphiphilic aminosaccharide derivatives were investigated as chiral selector additives in capillary electrophoresis. Each substance has a glucosamine backbone carrying three hydrocarbon chains as the hydrophobic region and three carboxylic groups as the hydrophilic region, which is an artificial biologically active compound. Using each compound as a chiral selector, the optical resolution of dansylated amino acids or new quinolone antibacterial agents (NQs) was observed. Increasing the concentration of the chiral selector or the ionic strength of running solution led to successful optical resolution. In consideration of the chemical structure of each selector and the migration behavior of the enantiomers, the resolution seemed to be based on micellar electrokinetic chromatography mode. Both selectors differed in their enantioselectivity for dansylated amino acids or NQs although the chemical structures were similar.

Amines↗

PubMed2000

Mmh/Ogg1 gene inactivation results in accumulation of 8-hydroxyguanine in mice.

The major mutagenic base lesion in DNA caused by exposure to reactive oxygen species is 8-hydroxyguanine or 7, 8-dihydro-8-oxoguanine (8-OH-G). Products of the human MMH/OGG1 gene are known to catalyze in vitro the reactions repairing this DNA lesion. To analyze the function of Mmh in vivo, we generated a mouse line carrying a mutant Mmh allele by targeted gene disruption. Mmh homozygous mutant mice were found to have a physically normal appearance, but to have lost nicking activity in liver extracts for substrate DNA containing 8-OH-G, exhibiting a 3-fold increased accumulation of this adduct at 9 weeks of age compared with wild-type or heterozygous mice. Further elevation to 7-fold was observed in 14-week-old animals. Substantial increase of spontaneous mutation frequencies was clearly identified in Mmh mutant mice bearing transgenic gpt genes. These results indicate that exposure of DNA to endogenous oxidative species continuously produces the mutagenic adduct 8-OH-G in mice, and Mmh plays an essential role in repair of this DNA damage.

Animals↗

PubMed2000

Effects of 6-formylpterin, a xanthine oxidase inhibitor and a superoxide scavenger, on production of nitric oxide in RAW 264.7 macrophages.

As well as superoxide generated from neutrophils, nitric oxide (NO) produced by inducible nitric oxide synthase (iNOS) in macrophages plays an important role in inflammation. We previously showed that 6-formylpterin, a xanthine oxidase inhibitor, has a superoxide scavenging activity. In the present study, to elucidate other pharmacological activities of 6-formylpterin, we investigated the effects of 6-formylpterin on production of nitric oxide (NO) in the murine macrophage cell line RAW 264.7 stimulated by lipopolysaccharide (LPS) and interferon-gamma (INF-gamma). 6-Formylpterin suppressed the expression of iNOS, and it also inhibited the catalytic activity of iNOS, which collectively resulted in the inhibition of NO production in the stimulated macrophages. However, 6-formylpterin did not scavenge the released NO from an NO donor, S-nitroso-N-acetylpenicillamine (SNAP). These results indicate that 6-formylpterin inhibits pathological NO generation from macrophages during inflammation, but that it does not disturb the physiological action of NO released from other sources.

Animals↗

PubMed2000

Distinct repair activities of human 7,8-dihydro-8-oxoguanine DNA glycosylase and formamidopyrimidine DNA glycosylase for formamidopyrimidine and 7,8-dihydro-8-oxoguanine.

7,8-dihydro-8-oxoguanine (8-oxoG) and 2,6-diamino-4-hydroxyformamidopyrimidine (Fapy) are major DNA lesions formed by reactive oxygen species and are involved in mutagenic and/or lethal events in cells. Both lesions are repaired by human 7, 8-dihydro-8-oxoguanine DNA glycosylase (hOGG1) and formamidopyrimidine DNA glycosylase (Fpg) in human and Escherichia coli cells, respectively. In the present study, the repair activities of hOGG1 and Fpg were compared using defined oligonucleotides containing 8-oxoG and a methylated analog of Fapy (me-Fapy) at the same site. The k(cat)/K(m) values of hOGG1 for 8-oxoG and me-Fapy were comparable, and this was also the case for Fpg. However, the k(cat)/K(m) values of hOGG1 for both lesions were approximately 80-fold lower than those of Fpg. Analysis of the Schiff base intermediate by NaBH(4) trapping implied that lower substrate affinity and slower hydrolysis of the intermediate for hOGG1 than Fpg accounted for the difference. hOGG1 and Fpg showed distinct preferences of the base opposite 8-oxoG, with the activity differences being 19.8- (hOGG1) and 12-fold (Fpg) between the most and least preferred bases. Surprisingly, such preferences were almost abolished and less than 2-fold for both enzymes when me-Fapy was a substrate, suggesting that, unlike 8-oxoG, me-Fapy is not subjected to paired base-dependent repair. The repair efficiency of me-Fapy randomly incorporated in M13 DNA varied at the sequence level, but orders of preferred and unpreferred repair sites were quite different for hOGG1 and Fpg. The distinctive activities of hOGG1 and Fpg including enzymatic parameters (k(cat)/K(m)), paired base, and sequence context effects may originate from the differences in the inherent architecture of the DNA binding domain and catalytic mechanism of the enzymes.

8-Hydroxy-2'-Deoxyguanosine↗