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T Tsukamoto

Publications and source records attributed to T Tsukamoto.

At least 253 records · Page 14Linked to original sources
PubMed1997

Tight junction proteins form large complexes and associate with the cytoskeleton in an ATP depletion model for reversible junction assembly.

A key feature of the ischemic epithelial cell phenotype is the disruption of tight junctions (TJ). In a Manin-Darby canine kidney cell model for ischemia-reperfusion/hypoxia-reoxygenation injury which employs inhibitors of glycolysis (2-deoxy-D-glucose) and oxidative phosphorylation (antimycin A), transepithelial electrical resistance, a measure of TJ integrity, dropped rapidly, correlating well with declining ATP levels. Although immunocytochemical studies revealed only subtle changes in the distribution of the TJ proteins, zonula occludens (ZO)-1, ZO-2, and cingulin, examination of the Triton X-100 solubilities of these proteins, an indicator of cytoskeletal association, revealed a striking shift of all three TJ proteins into the insoluble pool, consistent with increased cytoskeletal interaction during ATP depletion. In addition, rate-zonal centrifugation analysis of a detergent-soluble fraction showed an increase in the amount of ZO-1 and ZO-2 in high density fractions following ATP depletion, providing further evidence for association of TJ proteins into a large complex possibly involving the cytoskeleton. Analysis of immunoprecipitation data from [35S]methionine-labeled cells revealed that ATP depletion led to the association of a 240-kDa protein with the ZO-1-containing complex. Western blots of this protein immunoprecipitated with anti-ZO-1 antibodies confirmed its identity as fodrin, a protein believed to link membrane and other proteins to the actin-based cytoskeleton. Together, our data suggest that in the absence of major immunocytochemical changes, ATP depletion leads TJ proteins to form large insoluble complexes and associate with the cytoskeleton. We propose a model in which a key, potentially regulated, step in the generation of the ischemic epithelial cell phenotype is the interaction between TJ proteins and fodrin and/or other cytoskeletal proteins.

Adenosine Triphosphate↗
PubMed1997

An in vitro tubulogenesis system using cell lines derived from the embryonic kidney shows dependence on multiple soluble growth factors.

Interactions between the ureteric bud (UB) and metanephric mesenchyme are crucial for tubulogenesis during kidney development. Two immortalized cell lines derived from the day 11.5 embryonic kidney, UB cells, which appear to be epithelial (cytokeratin-positive, E-cadherin-positive, and ZO-1-positive by immunostaining) and BSN cells, which are largely mesenchymal (vimentin-positive, but negative for cytokeratin, cell surface E-cadherin, and cell surface ZO-1), were used to establish an in vitro tubulogenesis system. BSN cells expressed hepatocyte growth factor (HGF) and transforming growth factor-beta1 mRNAs, and its conditioned medium (BSN-CM) contained factors capable of activating the epidermal growth factor (EGF) receptor (EGFR). When UB cells were cultured in an extracellular matrix gel in the presence of the embryonic kidney or BSN-CM, the UB cells underwent morphogenetic changes characteristic of early in vitro branching tubulogenesis. These changes were largely inhibited by a combination of neutralizing anti-HGF antibodies and the EGFR inhibitor tyrphostin AG1478, suggesting that EGFR ligands, together with HGF, account for much of this early morphogenetic activity. Nevertheless, there was a significant fraction of tubulogenic activity that could not be inhibited, suggesting the existence of other soluble factors. Whereas HGF, EGF, transforming growth factor alpha, basic fibroblast growth factor (bFGF), and insulin-like growth factor 1 (IGF-1), or a mixture of these growth factors, induced epithelial processes for up to 3 days, only IGF-1, possibly bFGF, and the mixture were able to sustain morphogenesis for longer periods, though not nearly to the same degree as BSN-CM. Moreover, only BSN-CM induced branching tubular structures with clear lumens, consistent with the existence of other soluble factors crucial for the formation and/or maintenance of branching tubular structures with lumens in vitro.

Animals↗
PubMed1997

Isolation and characterization of peroxisome-deficient Chinese hamster ovary cell mutants representing human complementation group III.

We made use of the 9-(1'-pyrene)nonanol/ultraviolet (P9OH/UV) method and isolated peroxisome-deficient mutant cells. TKa cells, the wild-type Chinese hamster ovary (CHO) cells, CHO-K1, that had been stably transfected with cDNA encoding Pex2p (formerly peroxisome assembly factor-1, PAF-1) were used to avoid frequent isolation of the Z65-type, PEX2-defective mutants. P9OH/UV-resistant cell colonies were examined for the intracellular location of catalase, a peroxisomal matrix enzyme, by immunofluorescence microscopy and using anti-catalase antibody. As six mutant cell clones showed cytosolic catalase, there was likely to be a deficiency in peroxisome assembly. These mutants also showed the typical peroxisome assembly-defective phenotype, including significant decrease of dihydroxyacetonephosphate acyltransferase, the first step key enzyme in plasmalogen synthesis, and loss of resistance to 12-(1'-pyrene)dodecanoic acid/UV treatment. By transfection of Pex2p and Pex6p (formerly PAF-2) cDNAs and cell fusion analysis between the CHO cell mutants, two mutants, ZP104 and ZP109, were found to belong to a novel complementation group. Further complementation analysis using fibroblasts from patients with peroxisome biogenesis disorders revealed that the mutants belonged to human complementation group III. Taken together, ZP104 and ZP109 are in a newly identified fifth complementation group in CHO mutants reported to date and represent the human complementation group III.

ATPases Associated with Diverse Cellular Activitie↗
PubMed1997

Changes in responsiveness of freshly isolated longitudinal muscle cells from rat uterus towards oxytocin during gestation: contractility and calcium signaling.

Changes in responsiveness of freshly isolated longitudinal muscle cells from rat uterus to oxytocin during gestation were investigated through measuring contractility as well as intracellular free calcium concentration. We have demonstrated the pregnant stage-dependent contraction of freshly isolated myometrial cells in response to an extracellular hormone, oxytocin, in Ca2+-containing medium. The oxytocin effect appeared to be through oxytocin receptor since the effect could be blocked by a specific oxytocin antagonist. The magnitude of the contraction of the isolated cells in response to extracellular oxytocin was in the order of 21 day >> 18 day > 15 day pregnant rat longitudinal muscle cells. In a concentration dependent manner, oxytocin elicited a rapid increase in [Ca2+]i of longitudinal muscle cells isolated from different stages of the pregnant rat uterus, especially at the term of pregnancy. The time (4-5 s) required to reach a maximum increase in [Ca2+]i of the isolated longitudinal muscle cells in response to oxytocin was the shortest among all previously reported studies. The results also indicated that the freshly prepared longitudinal muscle cells maintained their functional calcium signaling system. The order of the responsiveness of the isolated longitudinal muscle cells to oxytocin was 21 day >> 18 day > 15 day pregnant rats in terms of rate, affinity and magnitude. Oxytocin appears to transmit its signal mainly through stimulating a voltage-dependent and/or receptor operated nonselective calcium channel. However, the possibility that a part of the oxytocin action occurs through stimulating the release of calcium from intracellular store sites of longitudinal muscle still remains.

Animals↗
PubMed1997

Association between cigarette smoking and prostatism in a Japanese community.

BACKGROUND: The purpose of this study was to examine the association between cigarette smoking and prostatism among Japanese men. METHODS: Male residents of Shimamaki-mura, Japan, aged 40-79 years old (n = 286), completed a self-administered questionnaire that included the international prostate symptom score (IPSS). A detailed cigarette smoking history was also obtained. All men had a transrectal ultrasonographic estimate of prostatic volume and a peak urinary flow rate measurement. RESULTS: Current cigarette smoking was inversely associated with an impaired peak urinary flow rate (< 15 mL/sec) (odd ratio [OR] = 0.39, 95% confidence interval [CI] = 0.18, 0.84), and with moderate to severe symptoms (IPSS > 7) (OR = 0.84, 95% CI = 0.48, 1.49), but was not significantly associated with prostatic volume. Smokers of 1 to 1.4 packs a day were less likely and smokers of less than a pack a day or 1.5 or more packs a day were more likely to have moderate to severe symptoms and a greater prostatic volume. CONCLUSION: These findings suggest that cigarette smoking may have a protective effect on prostatism at certain smoking intensities, but no effect or a deleterious effect at other intensities.

Adult↗
PubMed1997

Isolation of a new peroxisome-deficient CHO cell mutant defective in peroxisome targeting signal-1 receptor.

For the study of mechanism of peroxisome biogenesis, we attempted to isolate CHO cell mutants deficient in peroxisome biogenesis. We used as the parent strain a stable CHO transformant of rat PEX2 (formerly named peroxisome assembly factor-1) cDNA, to avoid unusually frequent isolation of Pex2 mutants. Among the three peroxisome-deficient mutants obtained, ZP102 was a new CHO mutant of complementation group 2, and was restored for peroxisome assembly by the transfection of human PEX5 (formerly called PXR1 or PTS1R) cDNA. This approach would facilitate the isolation of new complementation gorups of peroxisome-deficient CHO mutants and the identification of essential genes for peroxisome biogenesis.

Animals↗
PubMed1997

An orphan nuclear receptor lacking a zinc-finger DNA-binding domain: interaction with several nuclear receptors.

The yeast two-hybrid screening was applied to cloning cDNAs of proteins that interact with peroxisome proliferator-activated receptor alpha (PPAR alpha). We obtained from a rat liver cDNA library a clone encoding a protein related to the ligand-binding domain of the members of nuclear hormone receptor superfamily, whereas apparently lacking the zinc-finger DNA-binding domain. This protein interacted with the activated forms of several nuclear receptors, and thus is a novel type of heterodimer-forming nuclear receptor.

Amino Acid Sequence↗
PubMed1997

Ki-ras point mutation in different types of colorectal carcinomas in early stages.

PURPOSE: The aim of this study was to elucidate pathways of carcinogenesis in the colon and rectum by investigating Ki-ras point mutation in different types of colorectal carcinomas in the early stage. METHODS: We analyzed rates of Ki-ras codon 12 mutations in 34 small, polypoid-type carcinomas (Tis or T1), 21 superficial-type carcinomas (Tis or T1), and 42 advanced carcinomas (T2, T3, and T4). RESULTS: Frequency of Ki-ras mutations in superficial-type carcinomas was 14.3 percent (3/21), which was significantly lower than 50 percent (17/34) in small polypoid carcinomas and 40.5 percent (17/42) in advanced carcinomas. These data suggest that another pathway of colorectal carcinogenesis that does not involve Ki-ras point mutation might exist. Among the 17 small polypoid carcinomas with Ki-ras point mutation in which both adenomatous and carcinomatous tissue were examined, 12 showed a mutation of the same type in both carcinomatous and adenomatous tissues. In two cases, mutation was present only in carcinomatous tissue and not in adenomatous tissue; in the other three cases, Ki-ras point mutation was present only in adenomatous tissue but not in carcinomatous tissue. CONCLUSIONS: These data suggest that carcinoma in a small polypoid lesion does not always develop from pre-existing adenoma with Ki-ras point mutation; in a small number of the polypoid-type early carcinomas, polyclonal composition concerning the Ki-ras gene may exist.

Adenocarcinoma↗
PubMed1997

High malignancy of hepatocellular carcinoma in alcoholic patients with hepatitis C virus.

BACKGROUND: We investigated the relationships between alcohol consumption, the degree of malignancy evaluated histologically, and tumor-free survival rates. METHODS: In 80 male patients with the hepatitis C virus and small hepatocellular carcinomas (diameter of main tumor, 3.0 cm or less), 38 patients had drunk 86 gm or more of ethanol per day for at least 10 years until the detection of hepatocellular carcinoma (group 1), whereas the remaining 42 patients were nondrinkers or occasional drinkers (group 2). RESULTS: Differences in the results of liver function tests between the groups were not statistically significant. The operative methods used in the groups were comparable. The proportion of well-differentiated hepatocellular carcinoma was lower in group 1 than in group 2 (p < 0.0001). The prevalences of extracapsular invasion, portal tumor thrombi, and intrahepatic metastasis were higher in group 1 than in group 2 (p = 0.0085, p = 0.0319, and p = 0.0428, respectively). The tumor-free survival rate after operation was lower in group 1 than in group 2(p = 0.041 by the log-rank test; p = 0.032 by the generalized Wilcoxon test). CONCLUSIONS: These findings indicate that in group 1, even though tumors were small, the carcinomas were advanced and the outcomes after surgery were poor, suggesting that alcohol affects the grade of malignancy of this disease.

Aged↗
PubMed1997

Juvenile hemangioma of the testis: analysis of expression of angiogenic factors.

We present a case of juvenile hemangioma of the testis associated with hemangiomas of the liver and skin. The testicular hemangioma appeared to progress after therapy with interferon alpha-2a (IFN alpha-2a), whereas the liver and skin hemangiomas regressed. Analysis of growth factors responsible for proliferation of hemangioma revealed that the tumor expressed vascular endothelial growth factor but not basic fibroblast growth factor (bFGF), which is reported to be inhibited by IFN alpha-2a. This finding suggests that a possible explanation for the inadequate efficacy of IFN alpha-2a for testicular hemangioma is a lack of bFGF expression.

Angiogenesis Inducing Agents↗
PubMed1997

Poor association of GBV-C viremia with hepatocellular carcinoma.

BACKGROUND/AIMS: The role of the hepatitis GB virus C in chronic liver disease is unclear. The clinical findings, results of laboratory tests, pathological findings, and outcome after liver resection for hepatocellular carcinoma in patients infected or not infected with GB virus C were compared. METHODS: Serum samples from 213 patients were tested for hepatitis B virus, hepatitis C virus, and GB virus C. Of the 213 patients, 159 had hepatitis C viral RNA or antibodies (group 1), seven had both hepatitis C viral RNA or antibodies and hepatitis B surface antigen (group 2), 25 had hepatitis B surface antigen (group 3), and 22 did not have hepatitis C viral RNA, hepatitis C antibodies, or hepatitis B surface antigen (group 4). RESULTS: GB virus C RNA was detected in 12 of the 213 patients. Of the 12 patients, 11 were in group 1 and one was in group 4. There were no patients with hepatocellular carcinoma associated with GB virus C RNA alone. In groups 1 and 4, there were no differences in clinical findings, results of laboratory tests, pathological findings, or outcome after surgery in patients with and without GB virus C RNA. CONCLUSIONS: These results indicate a poor association of GB virus C viremia with hepatocellular carcinoma. We did not find clinically significant interaction between hepatitis C virus and GB virus C.

Adult↗
PubMed1997

Analysis of the 5'-flanking promoter region of the 5-HT2A receptor gene in schizophrenia.

We studied the 5'-flanking promoter region comprising positions -1441 to +128 of the 5-HT2A receptor gene in 95 schizophrenics and 100 unrelated normal control subjects. The genes encoding the 5-HT2A receptor exons and the adjoining introl regions had already been studied in these subjects, but no disease specific polymorphism was found (Ishigaki et al., 1996). The DNA fragments were amplified by means of the polymerase chain reaction (PCR), and then analyzed by the single-stranded conformation polymorphism (SSCP) and sequencing methods. One patient had a substitution, from A to G, at position -668, and a 5 nucleotide deletion of TACTT at positions -646 to -642, however, the patient also had a normal sequence on the other allele. SSCP analysis showed that the other schizophrenics and the control subjects did not have any polymorphism in the 5'-flanking promoter region of the 5-HT2A receptor gene.

Adult↗
PubMed1997

Three CAG trinucleotide repeats on chromosome 6 (D6S1014, D6S1015, and D6S1058) are not expanded in 30 families with schizophrenia.

Since 1991, more than five neuro-genetic disorders have been recognized to be caused by trinucleotide repeat expansions, and the list of such disease should grow. The diseases are characterized clinically by the phenomenon of anticipation, i.e., worsening of the disease phenotype in successive generations with increasing trinucleotide repeat expansion. The presence of anticipation in familial schizophrenia has been suggested. Several studies have provided supportive evidence that the suceptability locus for schizophrenia is on chromosome 6. Therefore, we analyzed three CAG trinucleotide repeat clones D6S1014, D6S1015, and D6S1058 on chromosome 6, which are polymolphic in 30 families with schizophrenia. No unusually, long alleles that would suggest abnormal expansion of more than 35 trinucleotide repeats were observed for these genes. Also, no statistically significant differences were found between the offspring and parental generations of affected subjects or between the affected and unaffected subjects in families with schizophrenia.

Adult↗
PubMed1997

Identification of an extended half-site motif required for the function of peroxisome proliferator-activated receptor alpha.

BACKGROUND: Peroxisome proliferator-activated receptors (PPARs) belong to the nuclear hormone receptor superfamily and regulate many genes of the proteins involved in lipid metabolism, including peroxisomal acyl-CoA oxidase (AOX). Through heterodimerization with retinoid X receptors (RXRs), PPAR was believed to recognize the sequence elements consisting of two directly repeating 6-bp half-sites spaced by one nucleotide (DR-1), located in the regulatory regions of these genes. RESULTS: Employing the peroxisome proliferator-responsive enhancer of the rat AOX gene, we analysed the minimal sequence requirements for enhancer activity and PPARalpha/RXRalpha binding. We found that the sequence just downstream of the DR-1 motif is indispensable for both functions. By a direct selection procedure of high-affinity binding sites from a random sequence pool, we identified a consensus sequence at the four positions next to DR-1. We also suggest that PPARalpha binds to the downstream half-site, whereas RXRalpha binds to the upstream half-site of the AOX DR-1. CONCLUSIONS: An extended half-site of 10-bp, but not a simple 6-bp half-site, is required for the PPARalpha binding, upon heterodimer formation with RXRalpha. The binding polarity of PPARalpha/RXRalpha seems to be opposite to that of other RXR-involving heterodimers.

Acyl-CoA Oxidase↗
PubMed1997

Effect of oral administration of prostaglandin E1 on erectile dysfunction.

OBJECTIVES: To investigate the effect of limaprost, an oral prostaglandin E1 (PGE1) derivative, on erectile dysfunction and to compare the effects of limaprost with a Chinese herbal drug, gosyajinki-gan. PATIENTS AND METHODS: The study comprised 50 consecutive patients with mild erectile dysfunction who showed a good erectile response to intracavernosal injection with 20 micrograms of PGE1. Limaprost was administered to the first 25 patients (30 micrograms three times daily) and gosyajinki-gan (7.5 g three times daily) to the next 25 patients, for 8 consecutive weeks. Patients were evaluated by their ability to achieve vaginal penetration and by a subjective assessment of erectile function (penile rigidity and maintenance of erection) before and after the treatment, using a self-administered questionnaire. Objective measurements (nocturnal penile tumescence, NPT, values) were also evaluated. RESULTS: Eleven of the 24 patients who received limaprost without interruption and four of the 24 taking gosyajinki-gan succeeded in vaginal penetration; the difference in the positive response rate was significant. The mean increment of NPT was significantly higher with limaprost treatment. However, all positive responders in both groups did not experience a full erection. There were no side-effects in any patient except one in the limaprost group who developed a facial flush. Thus the treatment was mild enough to be tolerated. CONCLUSION: Limaprost was more effective for mild erectile dysfunction than was gosyajinki-gan.

Administration, Oral↗
PubMed1997

Dose-dependent promoting effects of catechol on glandular stomach carcinogenesis in BALB/c mice initiated with N-methyl-N-nitrosourea.

The effects of catechol administration in the diet on stomach carcinogenesis in mice after initiation with N-methyl-N-nitrosourea (MNU) in the drinking water were investigated in a development trial for a new experimental protocol. Male 6-week-old BALB/c mice were given MNU in the drinking water intermittently for a total of three one-week periods, with one-week intervals, at the concentration of 120 ppm (groups 1 and 2). Groups 3 and 4 served as non initiated controls. From week 7, groups 1 and 3 were divided into three subgroups and the mice were fed on diet containing 0.05% (groups 1a and 3a), 0.2% (groups 1b and 3b), 08% (groups 1c and 3c) or 0% (groups 2 and 4) catechol for 29 weeks. At week 20, appreciably enhanced development of pepsinogen 1-altered pyloric glands was noted in all catechol-treated groups, in a partially dose-dependent manner (12.8 +/- 12.5, 13.8 +/- 11.7, and 24.0 +/- 12.7/100 pyloric glands respectively, for groups 1, 2 and 3). The incidences of adenomas (groups 1, 2 and 3) were also increased. At week 35, dose-dependent induction of adenocarcinomas in groups 1 (3/19), 2 (3/19) and 3 (14/20) was evident. In addition, the depth of invasion of the adenocarcinomas was enhanced by catechol in a dose-dependent manner, though the histological type was not influenced. Thus, the administration of catechol in the diet strongly enhanced the preneoplastic and neoplastic lesions in mouse glandular stomach induced by MNU in the drinking water, in a dose-dependent manner.

Adenocarcinoma↗