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K Ishizaki

Publications and source records attributed to K Ishizaki.

At least 19 recordsLinked to original sources
PubMed2006

Effect of palate covering on bolus-propulsion time and its contributory factors.

The aim of this study was first to investigate whether the covering of the palatal mucosa with a denture base affects or not the bolus-propulsion time, and second if there was such an effect then investigate the possible contributory factors which have influence on the propulsion time. The propulsion time was measured in 21 young normal edentulous subjects under five different conditions: a complete palatal covering, non-covered palate, anterior palatal covering, posterior palatal covering and surface anaesthetized palate. As possible contributory factors palatal morphometric parameters, as well as tongue pressure were also measured. The data were analysed on the following way: changes when the palate was complete covered and non-covered, effects of sensation reduction after topic anaesthesia, effects of differences in the covering site, effects of palatal morphometric parameters and effects of tongue pressure. Ten subjects exhibited significant differences in the propulsion time when comparing the data between the complete palatal covering and the non-covered palate condition (change group). Eleven subjects did not show changes (unchanged group). Effects in the propulsion time were also recognized with posterior palatal covering-palate and superficially anaesthetized palate. With regard to the tongue pressure, significant differences during swallowing were observed. These results indicated that the bolus propulsion time into the oropharynx was affected by the palatal covering in some subjects. Moreover, the sensation in the posterior region of the hard palate, as well as the tongue pressure were also factors which affected the propulsion time during swallowing.

Adult↗
PubMed2003

Glutathione S-transferase polymorphisms: susceptibility to migraine without aura.

Migraine is considered to be a polygenic multifactorial disease with various environmental and genetic etiologies. We investigated glutathione S-transferase (GST) P1 Ile(105)Val, T1 and M1 polymorphisms in 174 Japanese headache sufferers and 372 Japanese controls. The headache group consisted of 38 cases of migraine with aura, 95 migraine without aura (MWOA) and 41 tension-type headache sufferers. The M1 homozygous deletion genotype was significantly higher in MWOA (64%) compared with controls (46%; p < 0.01; odds ratio = 2.18, 95% confidence interval: 1.32-3.61, adjusted for age and gender). In a comparison of the current smokers, the M1 null frequencies in MWOA were further increased. GSTM1 may be one of the genetic risk factors for MWOA in the Japanese population.

Adult↗
PubMed2001

The Y chromosome in the liverwort Marchantia polymorpha has accumulated unique repeat sequences harboring a male-specific gene.

The haploid liverwort Marchantia polymorpha has heteromorphic sex chromosomes, an X chromosome in the female and a Y chromosome in the male. We here report on the repetitive structure of the liverwort Y chromosome through the analysis of male-specific P1-derived artificial chromosome (PAC) clones, pMM4G7 and pMM23-130F12. Several chromosome-specific sequence elements of approximately 70 to 400 nt are combined into larger arrangements, which in turn are assembled into extensive Y chromosome-specific stretches. These repeat sequences contribute 2-3 Mb to the Y chromosome based on the observations of three different approaches: fluorescence in situ hybridization, dot blot hybridization, and the frequency of clones containing the repeat sequences in the genomic library. A novel Y chromosome-specific gene family was found embedded among these repeat sequences. This gene family encodes a putative protein with a RING finger motif and is expressed specifically in male sexual organs. To our knowledge, there have been no other reports for an active Y chromosome-specific gene in plants. The chromosome-specific repeat sequences possibly contribute to determining the identity of the Y chromosome in M. polymorpha as well as to maintaining genes required for male functions, as in mammals such as human.

Amino Acid Sequence↗
PubMed2001

Effects of 5-HT2 and 5-HT3 receptors on the modulation of nociceptive transmission in rat spinal cord according to the formalin test.

We used the formalin test to clarify the 5-hydroxytryptamine (5-HT) receptor subtypes involved in the modulation of spinal nociceptive transmission in rats. Intrathecal administration of a 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino)-tetraline (8-OH-DPAT; 1, 10, and 30 microg), or a 5-HT1B receptor agonist, 1, 4-dihydro-3-(1, 2, 3, 6-tetrahydro-4-pyridinyl)-5H-pyrrol (3, 2-b) pyridin-5-one (CP 93129; 1 and 10 microg), produced no significant change in the number of flinches. A 5-HT(2) receptor agonist, (+/-)-2, 5-dimethoxy-4-iodoamphetamine (DOI; 10, 30, and 100 microg), and a 5-HT3 receptor agonist, 2-methyl-5-HT (100 and 300 microg), produced dose-dependent decreases in the number of flinches in phases 1 (1 to 6 min) and 2 (10 to 61 min) of the test. The antinociceptive effects of DOI and 2-methyl-5-HT were antagonized by intrathecal pretreatment with a 5-HT2 receptor antagonist, ketanserin, and a 5-HT3 receptor antagonist, 3-tropanyl-3, 5-dichlorobenzoate (MDL-72222), respectively. These results suggest that 5-HT2 and 5-HT3 receptors in the spinal cord mediate antinociception to chemical stimuli.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed2001

Effect of sodium tauroursodeoxycholate on phalloidin-induced cholestasis in rats.

We investigated the therapeutic effect of tauroursodeoxycholate on phalloidin-induced cholestasis in rats. Intrahepatic cholestasis was induced by administration of phalloidin (500 microg/kg, i.p.) for 7 days. From the day of the last phalloidin injection, tauroursodeoxycholate (60-360 micromol/kg) was given intravenously twice a day for 4 days. On the next day after the last tauroursodeoxycholate administration, bile flow, serum biochemical parameters and biliary lipid excretion rates were determined. Tauroursodeoxycholate significantly suppressed the decrease in bile flow and increases in serum alkaline phosphatase, leucine aminopeptidase and glutamic pyruvic transaminase activities, cholesterol, phospholipid and bile acid concentrations observed in phalloidin-induced cholestasis in rats. Furthermore, tauroursodeoxycholate significantly improved the biliary cholesterol and phospholipid excretion rates in phalloidin-induced cholestasis in rats. These results demonstrate the usefulness of tauroursodeoxycholate as a therapeutic agent in intrahepatic cholestasis.

Alanine Transaminase↗
PubMed2001

Ccm1, a regulatory gene controlling the induction of a carbon-concentrating mechanism in Chlamydomonas reinhardtii by sensing CO2 availability.

Aquatic photosynthetic organisms, including the green alga Chlamydomonas reinhardtii, induce a set of genes for a carbon-concentrating mechanism (CCM) to acclimate to CO2-limiting conditions. This acclimation is modulated by some mechanisms in the cell to sense CO2 availability. Previously, a high-CO2-requiring mutant C16 defective in an induction of the CCM was isolated from C. reinhardtii by gene tagging. By using this pleiotropic mutant, we isolated a nuclear regulatory gene, Ccm1, encoding a 699-aa hydrophilic protein with a putative zinc-finger motif in its N-terminal region and a Gln repeat characteristic of transcriptional activators. Introduction of Ccm1 into this mutant restored an active carbon transport through the CCM, development of a pyrenoid structure in the chloroplast, and induction of a set of CCM-related genes. That a 5,128-base Ccm1 transcript and also the translation product of 76 kDa were detected in both high- and low-CO2 conditions suggests that CCM1 might be modified posttranslationally. These data indicate that Ccm1 is essential to control the induction of CCM by sensing CO2 availability in Chlamydomonas cells. In addition, complementation assay and identification of the mutation site of another pleiotropic mutant, cia5, revealed that His-54 within the putative zinc-finger motif of the CCM1 is crucial to its regulatory function.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Mismatch repair and microsatellite instability in esophageal cancer cells.

Using in vitro mismatch repair (MMR) assay, we have identified 3 of 22 esophageal cancer cell lines exhibiting reduced MMR activity. By means of gel-shift assay, decreased binding ability to GT mismatch and CA loop was observed in these 3 cell lines. However, we could not find any mutations in the hMSH2, hMSH3 and hMSH6 genes, the protein products of which exhibit mismatch binding activity in human cells. In addition, when using antibodies against 5 MMR-related proteins (hMSH2, hMSH3, hMSH6, hPMS2 and hMLH1), no aberrant expression was detected in any of them. When we examined 9 microsatellite loci in endogenous genomic DNA, these 3 esophageal cancer cell lines, deficient in MMR, did not exhibit microsatellite instability. However, when we examined the repetitious sequence on exogenous plasmid DNA which was introduced into these 3 esophageal cancer cells, the results suggested that MMR deficiency in esophageal cancer cells could result in moderate instability of the exogenous sequence.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Antiallodynic effect of intrathecally administered 5-HT(2) agonists in rats with nerve ligation.

We examined the antiallodynic effect of intrathecally administered serotonin receptor agonists including 5-HT(1A), 5-HT(1B), 5-HT(2) and 5-HT(3) receptor subtypes in a rat model using spinal nerve ligation at L5 and L6. Administration of the 5-HT(2) receptor agonist, alpha-methyl-5-hydroxytryptamine maleate (alpha-m-5-HT; 3-100 microg) or (+/-)-1-(4-iodo-2,5-dimethoxyphenyl)-2-aminopropane hydrochloride (DOI; 10-100 microg), showed dose-dependent antiallodynic actions with no associated motor weakness. The antiallodynic action of alpha-m-5-HT was more potent than that of DOI. The effects of 5-HT(2) agonists on tactile allodynia were reversed by intrathecal pretreatment with the selective 5-HT(2) antagonist ketanserin and with the mixed 5-HT(1) and 5-HT(2) antagonist methysergide. Neither the mixed 5-HT(1A) and 5-HT(1B) antagonist cyanopindolol nor the selective 5-HT(3) antagonist MDL72222 attenuated antiallodynic effects induced by 5-HT(2) agonists. In contrast, the selective 5-HT(1A) agonist 8-hydroxy-2-(di-n-propylamino)-tetralin hydrobromide (8-OH-DPAT; 1-50 microg), the 5-HT(1B) agonist 5-methoxy-3-(1,2,5,6-tetrahydro-4-pyridinil)-1H-indol (RU-24969; 10-100 microg) and the 5-HT(3) agonist 2-methyl-5-hydroxytryptamine maleate (2-m-5-HT; 30-300 microg) all lacked significant antiallodynic action with intrathecal administration. These results indicate that the 5-HT(2) receptor plays an essential role in spinal suppression of neuropathic pain by 5-HT.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed2001

Leukocyte mitochondrial DNA A to G polymorphism at 11084 is not a risk factor for Japanese migraineurs.

Mitochondrial dysfunction has been reported in patients with migraine. We investigated leukocyte mitochondrial DNA 11084 A to G polymorphism in 166 Japanese migraineurs and 483 Japanese controls. The migraine group consisted of 43 patients suffering from migraine with aura (MWA) and 123 from migraine without aura (MOA). The frequency of the transition was 7.2% (12/166) in the migraine group and 7.3% (35/483) in the controls. The frequency of the transition was 4.7% in MWA and 8.1% in MOA. There was no significant difference among the groups (chi-square test). The mitochondrial DNA 11084 A to G transition was more common in Japanese subjects than reported in Caucasians; however, this polymorphism is not a genetic risk factor for migraine in Japanese patients.

Adult↗
PubMed2001

Cold-stimulated increase in a regulatory subunit of cAMP-dependent protein kinase in human hepatoblastoma cells.

Although cold-stress responses in bacteria and plants have been well studied and hypothermic conditions are used in clinical treatments, there has been little investigation of cold-stress responses in human cells, and there has been no report on the involvement of signal transduction modulators in the cold-stress response in human cells. We therefore investigated alterations in the expression of genes involved in the signal transduction system and the mechanisms of cold-stimulated increases in the expression of genes in human hepatoblastoma (HepG2) cells. Using a cDNA expression array method, we found that a transcript encoding a regulatory subunit Ibeta (RIbeta) of cyclic AMP-dependent protein kinase (PKA) was increased in cold-stressed cells. Western blot analysis revealed that the amount of PKA RIbeta protein was increased by cold treatment, while that of a PKA catalytic subunit (C) was unchanged. The protein level of PKA RIbeta was increased in cells treated with low concentrations of actinomycin D, whereas that of PKA C was not, implying that the increase was caused by the suppression of transcription at low temperatures. In addition, degradation of the PKA RIbeta protein was not stimulated by cold treatment, unlike that of the PKA C protein. The results suggest that signal transduction through PKA also participates in cold-stress responses in human cells and that multiple mechanisms are involved in the increase in the level of the PKA RIbeta protein.

Carcinoma, Hepatocellular↗
PubMed2001

Different susceptibility of each L-myc genotype to esophageal cancer risk factors.

To understand the relationship between the L-myc genotypes and esophageal cancer risk, a polymerase chain reaction-based restriction fragment length polymorphism analysis was performed on 91 Japanese patients with esophageal cancer and 241 non-cancer outpatients. No significant difference in the distribution of genotypes was observed between patients and controls; 18.7% LL genotype, 56.0% LS and 25.3% SS among patients, and 24.5%, 55.6% and 19.9%, respectively, among controls. Frequency of the s-allele in patients (0.533) was slightly higher than in controls (0.477), but the difference was not statistically significant. However, the odds ratios (ORs) for smoking or heavy drinking were markedly higher in SS and LS genotypes than in LL genotype; age-sex-adjusted ORs for smoking was 7.57 in the SS genotype, 6.40 in the LS genotype and 1.77 in the LL genotype. Age-sex-adjusted ORs for heavy drinking were 19.78, 18.20 and 7.40, respectively. The age-sex-adjusted ORs for both factors combined were 12.77, 18.45 and 1.44, respectively. These results suggested that the L-myc polymorphism might modify the effects of lifestyle factors on esophageal cancer risk.

Aged↗
PubMed2001

Polymorphism and allelic loss at the AS3 locus on 13q12-13 in esophageal squamous cell carcinoma.

Our previous studies of esophageal squamous cell carcinoma (ESC) revealed that frequent loss of heterozygosity (LOH) on 13q12-13 was associated with lymph node metastasis. These results suggest that 13q12-13 may harbor a tumor suppressor gene which regulates lymph node metastasis. Recently, a new tumor suppressor candidate, AS3, was identified in this region. We therefore examined AS3 alterations by PCR-SSCP and RT-PCR. Although polymorphisms were found in exon 10 and introns 21, 23, 25 and 29, a possible tumor specific mutation in exon 6 was identified in only one of 31 ESC-derived cell lines, indicating that the remaining allele of AS3 was rarely inactivated by mutational events. Interestingly, ESC patients with rare alleles frequently exhibited lymph node metastasis. These results suggest that polymorphic variation and LOH at the AS3 locus might be associated with lymph node involvement in ESC.

Alleles↗
PubMed2001

Genetic changes induced in human cells in Space Shuttle experiment (STS-95).

BACKGROUND: Results of past space experiments suggest that the biological effect of space radiation could be enhanced under microgravity. To assess the radiation risk for humans during long-term spaceflight, it is very important to clarify whether human cells exhibit a synergistic effect of radiation and microgravity. HYPOTHESIS: If significant synergism occurs in human cells, genetic changes induced during spaceflight may be detected by using human tumor HCT-116 cells which are hypermutable due to a defect in the DNA mismatch repair system. METHODS: Cultured HCT-116 cells were loaded on the Space Shuttle Discovery (STS-95) and grown during the 9-d mission. After landing, many single-cell clones were isolated, microsatellite repetitive sequences in each clone were amplified by PCR, and mutations in the microsatellite loci were detected as changes in the length of PCR fragments. Mutation frequencies of ouabain-resistant phenotype were also analyzed. RESULTS: The frequencies of microsatellite mutations as well as ouabain-resistant mutations in the flight sample were similar to those of the ground control samples. Some cells were treated in space with bleomycin which mimics the action of radiation, but the frequencies of microsatellite mutations were not significantly different between the flight and the ground control samples. CONCLUSION: Under the present flight conditions, neither space radiation (about 20 mSv during this mission) nor microgravity caused excess mutations in human cells.

Bleomycin↗
PubMed2000

Antinociception in rat by sarpogrelate, a selective 5-HT(2A) receptor antagonist, is peripheral.

The antinociceptive effect of sarpogrelate, a new selective 5-hydroxytriptamine (5-HT)(2A) receptor antagonist, in the formalin test was examined in rats. Sarpogrelate was administered intraperitoneally, locally (subcutaneously at the formalin test site) or intrathecally 10 min before formalin injection. Intraperitoneal (1-100 mg/kg) and local (0.01-1 mg) administration of sarpogrelate suppressed flinching behavior in both phases 1 (0-9 min) and 2 (10-60 min) in a dose-dependent manner. Intraperitoneal (100 mg/kg) and local (1 mg) injection 7 min after formalin injection reduced phase 2 flinches to the same degree as with the pre-treatment. Intrathecal administration (1-100 microg) showed no antinociceptive action, and facilitated phase 2 flinches at 10 microg. The plasma concentration of sarpogrelate after local administration of 1 mg was lower than after intraperitoneal administration of 10 mg/kg, although local administration produced more potent antinociception. The data imply that the antinociceptive effect of sarpogrelate results mainly from an action at peripheral sites.

Analgesics↗
PubMed2000

Fine mapping of smallest common regions of deletion on chromosome 12 in liver epithelial and hepatocellular carcinoma cell lines from B6C3F(1) and C3B6F(1) mice.

Loss of chromosomes frequently accompanies the establishment of hepatic cell lines in mice. Previous cytogenetic and allelotype studies have revealed that loss of chromosomes 4 and 12 is particularly common. In the present study, fine-deletion mapping was performed for chromosome 12 using 44 liver epithelial (LE) and hepatocellular carcinoma (HCC) cell lines derived from a hybrid between C3H/HeJ (C3H) and C57BL/6J (B6) mice with a high density of polymorphic microsatellite markers. Examination using 15 markers demonstrated that, although 19 of 44 cell lines showed deletion of the whole or large segments of chromosome 12, 3 had very small-range loss. Analysis of the latter using additional markers detected the 2 smallest common regions of deletion (Scrd1 and -2) in the centromeric and telomeric portions. Scrd1 is syntenic to human chromosome 2p and Scrd2 to human chromosome 14q, a region frequently deleted in various types of tumor. Of the 22 cases with loss of heterozygosity, 19 showed loss of B6 alleles. Our results demonstrate that mouse chromosome 12 contains at least 2 independent suppressor loci and that loss of B6 genes may be more advantageous than C3H gene deletion for establishment of hepatic cell lines.

Alleles↗
PubMed2000

Mutation spectrum of MSH3-deficient HHUA/chr.2 cells reflects in vivo activity of the MSH3 gene product in mismatch repair.

The endometrial tumor cell line HHUA carries mutations in two mismatch repair (MMR) genes MSH3 and MSH6. We have established an MSH3-deficient HHUA/chr.2 cell line by introducing human chromosome 2, which carries wild-type MSH6 and MSH2 genes, to HHUA cells. Introduction of chromosome 2 to HHUA cells partially restored G:G MMR activity to the cell extract and reduced the frequency of mutation at the hypoxanthine-guanine phosphoribosyltransferase (hprt*) locus to about 3% that of the parental HHUA cells, which is five-fold the frequency in MMR-proficient cells, indicating that the residual mutator activity in HHUA/chr.2 is due to an MSH3-deficiency in these cells. The spectrum of mutations occurring at the HPRT locus of HHUA/chr.2 was determined with 71 spontaneous 6TG(r) clones. Base substitutions and +/-1 bp frameshifts were the major mutational events constituting, respectively, 54% and 42% of the total mutations, and more than 70% of them occurred at A:T sites. A possible explanation for the apparent bias of mutations to A:T sites in HHUA/chr.2 is haploinsufficiency of the MSH6 gene on the transferred chromosome 2. Comparison of the mutation spectra of HHUA/chr.2 with that of the MSH6-deficient HCT-15 cell line [S. Ohzeki, A. Tachibana, K. Tatsumi, T. Kato, Carcinogenesis 18 (1997) 1127-1133.] suggests that in vivo the MutSalpha (MSH2:MSH6) efficiently repairs both mismatch and unpaired extrahelical bases, whereas MutSbeta (MSH2:MSH3) efficiently repairs extrahelical bases and repairs mismatch bases to a limited extent.

Amino Acid Substitution↗
PubMed2000

Mitochondrial genome-encoded ATPase subunit 6+8 mRNA increases in human hepatoblastoma cells in response to nonfatal cold stress.

Cellular responses to cold stress have not been well clarified, compared with heat shock responses, especially in mammalian cells. We investigated cold-stress responses in human hepatoblastoma cells (HepG2) exposed to a nonfatal temperature of 17 degrees C. Under the condition, RNA and protein syntheses in the cells were highly, but incompletely, depressed and cell growth was impaired. A cDNA subtraction method was used to isolate mRNAs for which the levels were increased in cold-stressed cells compared with cells cultured at 37 degrees C. A transcript isolated by the screening was identified as ATPase subunit 6+8 mRNA that encodes components of a mitochondrial ATPase complex and that is transcribed from a mitochondrial genome. The copy number of the mitochondrial genome in cells was not changed by cold stress. Thus, HepG2 cells were treated with various concentrations of actinomycin D and chloramphenicol to assess the effects of transcriptional and translational reduction on the increased level of the ATPase subunit 6+8 mRNA. The mRNA level was increased in cells treated with low concentrations of the RNA or protein synthesis inhibitors. These results indicate that the increase in ATPase subunit 6+8 mRNA stimulated by cold stress could be mediated by a partial decline of transcription and/or translation in the cells. In addition, the degradation of ATPase subunit 6+8 mRNA was suppressed in cold-stressed cells compared with that in 37 degrees C-cultured cells. This result implies that posttranscriptional regulation is also involved in the cold-stimulated increase in ATPase subunit 6+8 mRNA in HepG2 cells.

Apoptosis↗