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Biomedical subjects

M Hasebe

Publications and source records attributed to M Hasebe.

At least 37 records · Page 2Linked to original sources
PubMed1997

Transcriptional activation of H+/K+-ATPase genes by gastric GATA binding proteins.

H+/K+-ATPase (composed of alpha and beta subunits) and histamine H2 receptor are specifically expressed in gastric parietal cells. The GATA binding proteins (GATA-GT1 and GATA-GT2, also called GATA-6 and GATA-4, respectively) originally found in the gastric mucosa recognized a sequence motif [gastric motif, (G/C)PuPu(G/C)NGAT(A/T)PuPy] in the upstream regions of the ATPase genes [Tamura, S., Wang, X.-H., Maeda, M., and Futai, M. (1993) Proc. Natl. Acad. Sci. USA 90, 10876-10880]. These proteins activated the transcription of the reporter gene ligated downstream of the control region of the rat ATPase alpha or beta subunit gene but had no effect on the same reporter ligated downstream of the H2 receptor gene. Deletion analyses suggested that the upstream 249 (alpha gene) and 323 (beta gene) base pair sequences from the first letter of the initiation codon are sufficient for activation by the GATA proteins. Interestingly, two and three gastric motifs are located near the TATA-boxes of the alpha and beta genes, respectively. Mutagenesis studies demonstrated that the two motifs proximal to the TATA-box sequences of the ATPase alpha and beta subunit genes were essential for the activation. These results suggest that both the alpha and beta subunit genes are regulated similarly by the GATA binding proteins. The expression system established in this study is a useful system for analyzing the roles of GATA proteins in transcriptional regulation of the H+/K+-ATPase gene.

Animals↗
PubMed1997

Identification of new chalcone synthase genes for flower pigmentation in the Japanese and common morning glories.

New cDNA sequences for chalcone synthase (CHS), a key enzyme in the flavonoid biosynthesis, were obtained from the Japanese and common morning glories; they are more closely related to other CHS sequences than the six previously described CHS genes from the same plants. The newly isolated CHS-D gene is abundantly expressed in the pigmented flower buds, while its expression is drastically reduced in the white flower buds. Thus CHS-D appears to produce major CHS transcripts for flower pigmentation.

Acyltransferases↗
PubMed1997

Effect of dietary fiber on bowel mucosal integrity and bacterial translocation in burned rats.

The response of the bowel mucosa to enteral formula supplemented with dietary fiber was examined in rats with 30% full-thickness burns. The rats were fed a standard enteral formula without fiber or with one of two types of fiber (insoluble soy fiber or soluble guar gum fiber). Seventy-two hours after burn injury, the mesenteric lymph nodes were excised aseptically for bacterial culturing. Samples of the jejunum, ileum and cecum were also collected for histological examination. There were significantly fewer bacterial colonies in the lymph node cultures from rats given soy fiber compared to those from rats fed no fiber. In rats given soy fiber, the integrity of the bowel mucosa was maintained in the jejunum, ileum and cecum. In rats given guar gum fiber, however, the repair of mucosal erosions was observed in the jejunum and ileum as well as flattening of the cecal mucosa. These findings indicate that soy fiber is superior to guar gum fiber for maintaining bowel mucosal integrity and preventing bacterial translocation in burned rats receiving enteral feeding.

Animals↗
PubMed1997

[Gene diagnosis with an affinity sensor, BIACORE--principle and applications].

We are developing new techniques for detecting point mutations by DNA-DNA hybridization and DNA-protein interaction analysis with an affinity sensor, BIACORE. To detect point mutations by the hybridization method using synthetic oligonucleotides, we already found that the length of the probe and the location of mismatches were important. The PCR products of the N-ras gene derived from Hep G2 cells, which have heterozygous point mutations at codon 61 in the gene, were analyzed and the point mutations were detected with 13-mer probes. We suggest that the detection method using DNA-DNA hybridization is useful for detecting known point mutations. However, detect unknown mutations, E. coli mismatch recognition protein, MutS, was employed. All mismatches in immobilized 20 base pairs of double-strand DNA could be detected by MutS binding. We have started to apply of the MutS to the detection of point mutations in PCR products.

Bacterial Proteins↗
PubMed1996

Inhibitory effects of natural carotenoids, alpha-carotene, beta-carotene, lycopene and lutein, on colonic aberrant crypt foci formation in rats.

Inhibitory effect of four carotenoids prevalent in human blood and tissues against the formation of colonic aberrant crypt foci was examined in Sprague-Dawley rats. They received three intrarectal doses of N-methylnitrosourea in weak 1, and a daily gavage of de-escalated doses of carotenoids during weeks 2 and 5. Lycopene, lutein, alpha-carotene and palm carotenes (a mixture of alpha-carotene, beta-carotene and lycopene) inhibited the development of aberrant crypt foci quantitated at week 6, but beta-carotene did not. The results suggested that lycopene and lutein in small doses may potentially prevent colon carcinogenesis.

Animals↗
PubMed1996

Bifunctional labeling reagent for oligosaccharides to incorporate both chromophore and biotin groups.

We have developed a convenient and effective method for biotinylation of oligosaccharides at their reducing ends. A novel biotin hydrazide having a phenyl group produced the biotin adduct of N-acetyllactosamine (LacNAc) by simple incubation at 90 degrees C for 1 h. Although the biotin adduct was obtained as a mixture of several stereoisomers, one of the isomers, cyclic beta-glycoside, became predominant upon letting the reaction mixture stand in a weakly acidic state (pH 3.5). This conversion may be very advantageous for functional analysis of oligosaccharides because natural N-linked oligosaccharides exist in the cyclic beta form. The limit of detection of labeled LacNAc in reversed-phase chromatography was 330 fmol and showed good linearity in the range from 330 fmol to 261 pmol. When this procedure was applied to complex type and high mannose type N-linked oligosaccharides, the labeled oligosaccharides were easily detected and separated by reversed-phase, gel filtration, and anion exchange chromatographies. Furthermore, these labeled oligosaccharides were able to be immobilized onto the solid phase using avidin-biotin technology and were stable enough to allow the binding assay to be performed repeatedly and under the conditions for in situ exoglycosidase digestion. These results suggest that this derivatization technique might be useful for both separation and functional analysis of oligosaccharides.

Biosensing Techniques↗
PubMed1996

A comparative study on the effect of pure-tone exposure of the guinea pig cochlea.

Electrophysiological methods were applied to 160 healthy adult male guinea pigs in order to investigate the effects of pure-tone exposure for 24 h on the inner ear. A reduction in cochlear microphonics (CM), action potential (AP) and endocochlear potential was observed following exposure to 110 dB at 100 Hz, 100 dB at 200 and 600 Hz and 95 dB at 2 kHz. The observed K+ endolymphatic concentration during 40 min anoxia remained unchanged. In contrast K+ decreased in control animals and following exposure to pure tones varying from 110 dB at 60 Hz to 85 dB at 2 kHz. These findings indicate that high frequency tones have a greater effect on inner ear functions than those of lower frequency, decreasing the maximum output voltage of CM and AP but not changing K+ endolymphatic concentration.

Acoustic Stimulation↗
PubMed1996

Chemoprevention by pravastatin, a 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor, of N-methyl-N-nitrosourea-induced colon carcinogenesis in F344 rats.

A potential chemopreventive action of pravastatin (Pr), a 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor, on colon carcinogenesis was evaluated in F344 rats. All rats at 7 weeks of age received an intrarectal dose of 2 mg of N-methyl-N-nitrosourea 3 times weekly for 2 weeks in experiment I (2 groups of 16 rats each), and for 3 weeks in experiment II (4 groups of 30 rats each). They were given drinking water containing 0 ppm (control) or 200 ppm Pr during weeks 1 to 40 in experiment I, and containing 0 ppm (control), 25 ppm, 5 ppm and 1 ppm Pr during weeks 4 to 40 in experiment II. The body weight gains, and food and water intakes were similar in all the groups. The incidence of colon carcinomas at termination of the experiment at week 40 was not different in the 200 ppm Pr and control groups in experiment I (63% vs. 69%), while it was significantly lower in the 25 ppm and 5 ppm groups, but not in the 1 ppm Pr group, compared with the control group in experiment II (50%, 48%, and 77% vs. 80%). This inhibitory effect of Pr against colon carcinogenesis was not related to the cholesterol-lowering effect of this agent. We postulate that Pr inhibits the promotion stage of colon carcinogenesis, perhaps through modulation of cholesterol synthesis in situ in the colonic mucosa, thereby suppressing farnesyl isoprenylation of growth-regulating proteins such as p21 ras.

Animals↗
PubMed1996

Chemopreventive efficacy of low dose of pravastatin, an HMG-CoA reductase inhibitor, on 1,2-dimethylhydrazine-induced colon carcinogenesis in ICR mice.

Potential chemopreventive action of de-escalated doses of pravastatin (Pr), an HMG-CoA reductase inhibitor, on 1,2-dimethylhydrazine.2HCl (DMH)-induced colon tumorigenesis was evaluated in ICR mice. Thirty mice each in 4 groups received an intraperitoneal injection of 20 mg DMH/kg body weight once weekly for 10 weeks, and were given drinking water dissolved Pr at the concentration of 10 ppm, 5 ppm, or 0 ppm (control) throughout the experiment. The incidence of colon tumors examined at week 35 was significantly lower in the Pr-treated groups than the control group: 20%. 21% and 23% vs. 55%. However, the tumor multiplicity/tumor-bearing animal was increased in the Pr-treated groups compared to the control group. Of all the tumors, 66 were adenocarcinomas in the distal colon and 5 were squamous cell carcinomas at the anus. The Pr treatment showed no hypocholesterolemic effect but did significant decrease of colonic mucosal cholesterol. The results seems to suggest that a small dose of Pr may reduce the incidence of colon cancers, perhaps being related, at least in part, to modulation of cholesterol synthesis in situ at the colonic mucosa.

1,2-Dimethylhydrazine↗
PubMed1995

Mutations causing high basal level transcription that is independent of transcriptional activators but dependent on chromosomal position in Saccharomyces cerevisiae.

Two single (bel2 and bel4) and two double (bel3 bel7 and bel5 be16) mutations causing enhanced transcription of a gene fusion, consisting of the open reading frame of PHO5 connected to the HIS5 promoter (HIS5p) integrated at the ura3 or leu2 locus, were isolated from a gcn4-disrupted mutant of Saccharomyces cerevisiae. The PHO5 gene, encoding repressible acid phosphatase, in the HIS5p-PHO5 construct was derepressed under amino acid starved conditions by the action of the transcriptional activator Gcn4p. The bel mutants showed temperature-sensitive cell growth and/or cell aggregation. All the mutants except bel4 also showed high levels of transcription of an intact PHO5 DNA integrated at the URA3 locus in the absence of the cognate transcriptional activator, Pho4p, and in the absence of upstream activating sequences of PHO5. The HIS5 and PHO5 genes at their original chromosomal positions were, however, not affected by the bel2 mutation. The BEL2 gene was found to be identical with SIN4/TSF3, mutations in which cause high levels of transcription of the HO and GAL genes in the absence of their respective transcriptional activators, Swi5p and Gal4p. The effect of the bel2/sin4/tsf3 mutation on PHO5 transcription was additive with the Pho4p function. Thus the effect of the bel2/sin4/tsf3 mutation is dependent on the position of PHO5 in the chromosome and independent of Pho4p and Gen4p activation.

Alleles↗
PubMed1994

rbcL gene sequences provide evidence for the evolutionary lineages of leptosporangiate ferns.

Pteriodophytes have a longer evolutionary history than any other vascular land plant and, therefore, have endured greater loss of phylogenetically informative information. This factor has resulted in substantial disagreements in evaluating characters and, thus, controversy in establishing a stable classification. To compare competing classifications, we obtained DNA sequences of a chloroplast gene. The sequence of 1206 nt of the large subunit of the ribulose-bisphosphate carboxylase gene (rbcL) was determined from 58 species, representing almost all families of leptosporangiate ferns. Phlogenetic trees were inferred by the neighbor-joining and the parsimony methods. The two methods produced almost identical phylogenetic trees that provided insights concerning major general evolutionary trends in the leptosporangiate ferns. Interesting findings were as follows: (i) two morphologically distinct heterosporous water ferns, Marsilea and Salvinia, are sister genera; (ii) the tree ferns (Cyatheaceae, Dicksoniaceae, and Metaxyaceae) are monophyletic; and (iii) polypodioids are distantly related to the gleichenioids in spite of the similarity of their exindusiate soral morphology and are close to the higher indusiate ferns. In addition, the affinities of several "problematic genera" were assessed.

Base Sequence↗
PubMed1994

Genes for members of the GATA-binding protein family (GATA-GT1 and GATA-GT2) together with H+/K(+)-ATPase are specifically transcribed in gastric parietal cells.

mRNAs for novel DNA-binding proteins (GATA-GT1 and GATA-GT2) recognizing the (G/C)PuPu(G/C)NGAT(A/T)PuPy sequence and H+/K(+)-ATPase (proton pump) alpha subunit were detected in parietal cells of the rat gastric body mucosa by in situ hybridization. These results suggest that GATA-GT1 and GATA-GT2 together with H+/K(+)-ATPase are transcribed specifically in gastric parietal cells and that the two DNA-binding proteins may have important roles in cell specific gene regulation. Furthermore, we could detect parietal cells in different states of gene expression.

Animals↗
PubMed1993

Effects of sodium bicarbonate and ammonium chloride on the incidence of furosemide-induced fetal skeletal anomaly, wavy rib, in rats.

Furosemide produces fetal wavy ribs when administered to pregnant rats during late gestation. The compound is also known to produce metabolic alkalosis in laboratory animals and man. In order to evaluate the effect of furosemide on maternal blood pH, Crj:CD(SD) female rats received an oral administration of 150 or 200 mg/kg of furosemide by gavage on day 16 of gestation and were bled at 4 hr post-dose. Compared to an average pH of 7.39 in control females, there was a significant elevation in blood pH in these furosemide-treated females (average pH of 7.44 to 7.48). When 2% sodium bicarbonate was provided in the drinking water for females treated with 150 mg/kg of furosemide, there was a further rise in maternal blood pH (7.52) compared to females treated with furosemide alone. Associated with this elevation in maternal blood pH was a marked increase in the incidence of fetal wavy ribs (87.6% compared to 27.6%). When females treated with 200 mg/kg of furosemide were provided with 0.5% ammonium chloride, furosemide-induced maternal alkalosis was corrected (pH decreased to 7.35) and there was a reduction in the incidence of fetal wavy ribs (7.0% compared to 37.2%). In addition, maternal blood pH among individual females was positively correlated with the incidence of fetal wavy ribs (r = 0.714). These results suggest that maternal metabolic alkalosis is involved in the pathogenesis of furosemide-induced wavy ribs.

Alkalosis↗
PubMed1993

Phylogenetic relationships of ferns deduced from rbcL gene sequence.

Part of the large subunit of the ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) gene (rbcL) was sequenced from three fern species: Adiantum capillus-veneris, Botrypus strictus, and Osmunda cinnamomea var. fokiensis. This region included 1,333 base pairs, about 90% of the gene. Maximum likelihood analysis of the deduced amino acid sequences indicated that (1) Botrypus (Ophioglossaceae) clustered monophyletically with other ferns (Adiantum, Angiopteris, Osmunda); the closest relative to Botrypus among the three species was Osmunda, which did not support the hypothesis that the Ophioglossaceae are linked to the progymnosperm-seed plant lineage. (2) Eusporangiate ferns containing Botrypus (Ophioglossaceae) and Angiopteris (Marattiaceae) were a paraphyletic group. (3) Seed plants and the four fern species examined formed a monophyletic group, but ferns and bryophytes (liverwort) did not. Variations in rates of substitution for synonymous and nonsynonymous codons were found in fern lineages.

Amino Acid Sequence↗
PubMed1992

Vacuolar type H(+)-ATPase genes: presence of four genes including pseudogenes for the 16-kDa proteolipid subunit in the human genome.

Genes for the human vacuolar type H(+)-ATPase proteolipid (16-kDa) subunit were cloned and their nucleotide sequences were determined. Comparison of the deduced sequences indicated that at least four genes including pseudogenes are present in the human genome. One of them corresponded to that for the 16-kDa subunit expressed in HeLa cells. The coding sequence was separated by two introns. The second intron was located in the DNA segment giving a loop between the second and third transmembrane helices, supporting the idea that the 16-kDa subunit was evolved by gene duplication. The primary sequence determined from the second clone had a termination codon behind the third transmembrane helix. Possible translation products from the other two clones had no putative acidic residues essential for proton transport function of the 16-kDa subunit. Thus, it is interesting to know whether these genes are transcribed, since they may have unique cellular functions.

Base Sequence↗
PubMed1992

Structural rearrangements of the chloroplast genome provide an important phylogenetic link in ferns.

The chloroplast genome of most land plants is highly conserved. In contrast, physical and gene mapping studies have revealed a highly rearranged chloroplast genome in species representing four families of ferns. In all four, there has been a rare duplication of the psbA gene and the order of the psbA, 16S, and 23S rRNA genes has been inverted. Our analysis shows that the described rearrangement results from a minimum of two inversions within the inverted repeat. This chloroplast DNA structure provides unambiguous evidence that phylogenetically links families of ferns once thought to belong to different major evolutionary lineages.

Chloroplasts↗
PubMed1992

Alterations in levels of plasma phenylalanine and its catabolism in the liver of stressed rats.

This study examined the relationship between elevation of blood phenylalanine (Phe) concentrations often observed in trauma or infected patients without hepatic dysfunction and alterations of liver Phe catabolism. Rats underwent pathophysiologically different stresses, either sepsis or scald injury. The catalytic activity of hepatic Phe hydroxylase (PH) in the septic rats, as measured after preincubation with Phe, decreased to 60% of the control values; this in vitro result suggests a reduction of enzyme species activated by its substrate. Phe was degraded in the septic rats to a similar extent to that in controls, when measured by pulse administration of [1-14C]-Phe. In the scalded rats whose plasma Phe level showed a comparable but transient increase, no significant alterations occurred in Phe catabolism and enzyme activities. The changes in plasma glucagon and catecholamine levels were consistent with those of the enzyme activities involved in Phe and tyrosine (Tyr) catabolism in the stressed groups. These results indicate that inadequate activation of native PH by regulatory mechanisms involving Phe in vivo was also associated with the accumulation of plasma Phe in infected rats during massive mobilization of amino acids from muscles under conditions of enhanced and sustained catabolism.

Animals↗