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Biomedical subjects

K Miki

Publications and source records attributed to K Miki.

At least 19 recordsLinked to original sources
PubMed1997

Substratum-dependent and region-specific control of attachment and proliferation of gastrointestinal epithelial cells in primary serum-free culture.

A system for the primary serum-free culture of fetal rat gastrointestinal epithelial cells was used to examine the role of the extracellular matrix (ECM) in the attachment and proliferation of these epithelial cells. Forestomach epithelial cells (FSEC) were able to attach to and proliferate on plastic dishes without a substratum, while glandular stomach epithelial cells (GSEC) and duodenal epithelial cells (DEC) were unable to do so. The presence of a substratum promoted the attachment and proliferation of these epithelial cells. The effects of various components of the ECM differed depending on the type of cell. FSEC attached most efficiently to a substratum of fibronectin, while GSEC did so to laminin. DEC attached more efficiently to type I collagen and fibronectin than to any other substratum. FSEC proliferated most rapidly on laminin, while GSEC and DEC did so on collagen gels. These substrata induced the most efficient attachment and proliferation of FSEC, and they were effective in promoting the attachment and proliferation of GSEC and DEC in decreasing order of efficiency, indicating the existence of a head-to-tail gradient in the response of epithelial cells to substrata. The expression of c-myc mRNA in these cells differed depending upon the substratum on which they were cultured and the mRNA level was well correlated with the extent of the cell proliferation, indicating that the cell proliferation is mediated by c-myc gene expression, which is regulated by cell-ECM interactions. The results of the present study demonstrate that proliferation of gastrointestinal epithelial cells is regulated region-specifically not only by soluble factors but also by insoluble components of the ECM.

Animals↗
PubMed1997

An increase in noradrenaline excretion during prolonged mental task load.

To investigate the effects of prolonged mental work, urinary excretion of catecholamines and cortisol was measured in 18 human subjects from 9:30 to 17:00. On the "task day,' the subjects performed mental tasks during the morning (10:20-11:45) and afternoon sessions (13:00-17:00), otherwise taking chair rest. On the "control day,' the subjects took chair rest in the afternoon after performing mental tasks in the morning. In the morning session, urinary excretion of adrenaline during mental work increased greatly compared to that before the mental work. Mental work in the afternoon session also caused a marked increase in adrenaline excretion compared to the rest level in the afternoon on the control day. Cortisol levels in the first hour of the afternoon mental work were significantly higher than those during the corresponding time on the control day. Urinary excretion of noradrenaline during mental work in the morning session only increased slightly compared to that before the mental work. In the afternoon session, however, noradrenaline excretion during mental work on the task day was markedly elevated compared to that during the rest condition at the corresponding time on the control day. These findings suggest that prolonged exposure to mental work, but not short-term mental work, produces a marked increase in noradrenaline excretion in human subjects.

Adult↗
PubMed1996

Early induction of the NGFI-B/Nur77 family genes in nephritis induced by anti-glomerular basement membrane antibody.

We recently isolated a novel nuclear receptor NOR-1, which is a member of the steroid/thyroid receptor superfamily, and belongs to the NGFI-B/Nur77 family. In the present study, we examined gene expression of NOR-1 and its closely related members in nephritis induced by anti-glomerular basement membrane (GBM) antibody. The mRNA levels for NOR-1, NGFI-B and RNR-1 increased 24 h after injection of anti-GBM antibody (day 1). Gene expression of NOR-1 and NGFI-B reached maximum levels on day 3, gradually decreased thereafter and returned to control levels on day 28. RNR-1 reached a peak on day 7, and then decreased. Renal injuries were most prominent on day 7 and persisted until day 28, indicating that NOR-1, NGFI-B and RNR-1 genes are induced during the early stage of glomerulonephritis and may be associated with the progression of glomerulonephritis. The induction of the NGFI-B gene was less remarkable than that of NOR-1 and RNR-1. In addition, administration of glucocorticoid hormone suppressed NOR-1 and RNR-1 gene expression to almost normal levels, whereas NGFI-B gene expression was not significantly repressed. These findings also suggest that the NGFI-B/Nur77 family may possess different biological roles and NGFI-B might act as a general transcription factor in cell function.

Animals↗
PubMed1996

Structure, mapping and expression of a human NOR-1 gene, the third member of the Nur77/NGFI-B family.

We identified a human homologue of NOR-1 (neuron-derived orphan receptor) from the fetal brain. There are two transcripts for human NOR-1, encoding 626 amino acid residues with a calculated molecular mass of 68 kDa. The high homology between hNOR-1, mNur77/rNGFI-B/hTR3, and mNurr1/rRNR-1/hNOT indicated that these three orphan receptors form a distinct subfamily within the steroid/thyroid receptor superfamily. Human NOR-1 mRNA was detected in the adult heart and skeletal muscle as well as in the fetal brain, indicating that its expression is not restricted to events that occur during neural development. The hNOR-1 gene is more than 35 kilobases long and interrupted by seven introns. The exon-intron structure of the gene is generally conserved when compared with the steroid/thyroid receptor superfamily and is remarkably similar to that of the Nur77/NGFI-B genes. This suggests that the Nur77/NGFI-B family has evolved from a common ancestral gene. Fluorescence in situ hybridization (FISH) revealed that the gene is located on chromosome 9q.

Amino Acid Sequence↗
PubMed1996

Ventral tegmental injection of nicotine induces locomotor activity and L-DOPA release from nucleus accumbens.

Effects of nicotine systemically or locally on locomotor activity and L-3,4-dihydroxyphenylalanine (L-DOPA) release were studied using microdialysis in the nucleus accumbens of freely moving rats. The basal L-DOPA release was Ca2(+)-dependent and tetrodotoxin-sensitive. Systemic nicotine (1 mg/kg s.c.) increased locomotor activity and L-DOPA release preferentially in the nucleus accumbens as compared with the striatum. Injection of nicotine (30 micrograms) into the ventral tegmental area increased locomotor activity and L-DOPA release from the nucleus accumbens. These increases were antagonized by prior injection of mecamylamine into the ventral tegmental area. Nicotine induces locomotor activity and L-DOPA release from the nucleus accumbens via nicotinic receptors in the ventral tegmental area. The release may be relevant to behavioral actions of nicotine.

Animals↗
PubMed1996

Potential sites for processing of the human invariant chain by cathepsins D and E.

Seven peptides of 15-30 amino acid residues were synthesized that covered almost the entire sequence of the lumenal domain of the human invariant chain (Ii), and their hydrolysis by cathepsins D and E was investigated. Two sites were identified that were very susceptible to such cleavage. One site, the Leu174-Phe175 bond, was cleaved by both cathepsins, and the other site, the Met99-Gln100 bond, was specifically cleaved by cathepsin E. These two sites could be the sites at which native Ii is cleaved by aspartic proteinases. The cleavage of the Met99-Gln100 bond by cathepsin E might be important in the inactivation of Ii and its functional derivatives.

Amino Acid Sequence↗
PubMed1996

Stage-specific elevated expression of the genes for hepatocyte growth factor, keratinocyte growth factor, and their receptors during the morphogenesis and differentiation of rat stomach mucosa.

Hepatocyte growth factor (HGF) and keratinocyte growth factor (KGF) are two factors considered to be involved in the morphogenesis of several organs. To understand the role of HGF and KGF in the stomach development, we analyzed changes in the levels of expression of the genes for the two growth factors and their receptors in the fetal rat stomach by competitive RT-PCR. Resembling our previous results for HGF, the expression of the genes for KGF and its receptor was observed in the mesenchyme and epithelium of 16.5 day fetal stomach, respectively, indicating the possibility that KGF mediates the epithelial-mesenchymal interaction in the early stage of stomach development. The developmental profile of the expression of the genes for the two growth factors and their receptors were different, indicating a difference in their roles; the genes for HGF and c-met, the receptor for HGF, are expressed mainly during the morphogenetic period, while the genes for KGF and its receptor mainly after the morphogenetic period. Thus, it is probable that HGF controls the proliferation of epithelial cells during the morphogenetic process. The expression of the genes for KGF and its receptor is not correlated with epithelial proliferation during morphogenesis, but it does appear to be linked with epithelial differentiation. These results, together with the absence of significant mitogenic effect of KGF on the epithelial cells of the fetal rat glandular stomach in vitro, suggest a role for KGF as a differentiation factor. In addition, the expression profile of the genes for KGF and its receptor towards the end of fetal period appears to be closely correlated with that of mesenchymal cell proliferation, suggesting another role for the growth factor that is not regulated by the epithelial-mesenchymal interaction.

Animals↗
PubMed1996

A water channel closely related to rat brain aquaporin 4 is expressed in acid- and pepsinogen-secretory cells of human stomach.

We isolated a cDNA clone encoding a water channel protein, aquaporin ( AQP), from human stomach. The encoded protein consisted of 323 amino acid residues, containing six putative transmembrane domains. The protein was designated human aquaporin 4 (hAQP4) because of its 94% sequence similarity to rat brain AQP4. Expression of hAQP4 cRNA in Xenopus oocytes resulted in a significant increase in osmotic water permeability, indicating that this protein functions as a water channel. Northern blot analysis demonstrated a strong signal of hAQP4 mRNA in brain, lung, and skeletal muscle as well as in stomach. Immunohistochemical experiments with human stomach tissues showed that hAQP4 as a protein is expressed mainly in cells located in the glandular portion of the fundic mucosa. These include chief cells which secrete pepsinogen and parietal cells which secrete hydrochloric acid. These results strongly indicate that hAQP4 is a principal factor involved in the osmotic regulation of pepsinogen and acid secretion in the stomach.

Amino Acid Sequence↗
PubMed1996

Complementary DNA cloning and sequencing of rat enteropeptidase and tissue distribution of its mRNA.

A cDNA clone encoding enteropeptidase (EC 3.4.21.9), a key enzyme for the conversion of trypsinogen to trypsin, was isolated from a rat duodenal mucosa cDNA library. Sequences of the 3585 base pair clone predicted that enteropeptidase is synthesized as a single-chain precursor form, proenteropeptidase, consisting of 1058 amino acid residues with an internal signal sequence (51 residues) and is then processed into the mature enzyme consisting of three different peptide chains, i.e., mini, light and heavy chains, not the previously reported two-chain enzyme. The structure of enteropeptidase is relatively conserved among different species and the rat enteropeptidase is 24 and 39 amino acids longer than the porcine and human ones, respectively. Northern blot analysis of rNAs from normal rat tissues revealed that the enteropeptidase mRNA of around 4.4 kb in size was expressed only in the duodenal mucosa, and high proteolytic activity of the enzyme was detected in the proximal small intestine. Additional analysis of the RNAs by RT-PCR revealed that a low level of the mRNA was also expressed in the other parts of the small intestine, i.e., jejunum and ileum. These results indicate that the biosynthesis of enteropeptidase takes place mainly in the proximal small intestine, the duodenum, and the importance of the region in the physiology of intestinal protein digestion regulated by the enzyme is suggested. Furthermore a faint signal of the mRNA was also detected in the stomach, colon and brain in which the existence of trypsin-like serine proteases were reported. The significance of the low level expression of the gene is unclear, but the potential peptide-processing function of the enzyme in these tissues is also suggested.

Amino Acid Sequence↗
PubMed1996

Measurements of oxidoreductase-like activity of intact bacterial cells by an amperometric method using a membrane-coated electrode.

The oxidation of D-glucose and nicotinic acid by intact cells of Gluconobacter industrious and Pseudomonas fluorescens, respectively, is successfully measured by an amperometric method using such compounds as Fe(CN)6(3-), p-benzoquinone, and dichlorophenolindophenol as electron acceptors. Analysis of the experimental results reveals that the intact cells behave like oxidoreductases whose kinetics follows a Michaelis-Mententype equation. The catalytic behavior is explained by a model which treats the bacterial cells as bags of enzymes and assumes distribution equilibrium in the concentrations of both the substrate and the electron acceptor between the test solution and the medium within the cells. The catalytic activity can be characterized by three quantities: the maximum reaction rate (vB) and the ratios of the Michaelis constant to the distribution constant for the substrate (Ks,cell/Ks,p) and to that for the electron acceptor (KM,cell/KM,p). Advanced modification of the model to involve the membrane permeability reveals that the three quantities are effective for explaining the catalytic behavior even when the permeability effect is significant. Thus, the three quantities should be regarded as the parameters which can reflect the permeability effect.

Electrochemistry↗
PubMed1996

Electrostatic properties deduced from refined structures of NADH-cytochrome b5 reductase and the other flavin-dependent reductases: pyridine nucleotide-binding and interaction with an electron-transfer partner.

Electrostatic properties on the protein surface were examined on the basis of the crystal structure of NADH-cytochrome b5 reductase refined to a crystallographic R factor of 0.223 at 2.1 A resolution and of the other three flavin-dependent reductases. A structural comparison of NADH-cytochrome b5 reductase with the other flavin-dependent reductases, ferredoxin-NADP+ reductase, phthalate dioxygenase reductase, and nitrate reductase, showed that the alpha/beta structure is the common motif for binding pyridine nucleotide. Although the amino acid residues associated with pyridine nucleotide-binding are not conserved, the electrostatic properties and the location of the pyridine nucleotide-binding pockets of NADH-requiring reductases were similar to each other. The electrostatic potential of the surface near the flavin-protruding side (dimethylbenzene end of the flavin ring) of NADH-cytochrome b5 reductase was positive over a wide area while that of the surface near the heme-binding site of cytochrome b5 was negative. This implied that the flavin-protruding side of NADH-cytochrome b5 reductase is suitable for interacting with its electron-transfer partner, cytochrome b5. This positive potential area is conserved among four flavin-dependent reductases. A comparison of the electron-transfer partners of four flavin-dependent reductases showed that there are significant differences in the distribution of electrostatic potential between inter-molecular and inter-domain electron-transfer reactions.

Binding Sites↗
PubMed1996

Immunohistochemically demonstrated variation in expression of cathepsin E between uracil-induced papillomatosis and N-butyl-N-(4-hydroxybutyl)nitrosamine-induced preneoplastic and neoplastic changes in rat urinary bladder.

Expression of rat urinary bladder cathepsin E in benign papillomatosis induced by uracil and various stages of N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN)-induced carcinogenesis was investigated immunohistochemically. Seven-week-old, male F344/DuCrj rats were used. In the normal urothelium of control rats, cathepsin E stained in all layers of cells, although in umbrella cells and some basal cells the reaction was relatively weak. In rats given a diet containing 3% uracil for 5 weeks immunoreactivity of cathepsin E in uracil-induced papillomatosis was consistently homogeneous in all layers, but weaker than in normal urothelium. In rats given 0.05% BBN in drinking water for 12 weeks and subsequently maintained without treatment for 48 weeks cells with little cathepsin E, never observed in normal urothelium, appeared at 5 weeks above the basement membrane in the earliest stage of BBN-induced urinary bladder cancer (simple hyperplasia). Throughout the neoplastic process, groups of cells with a little cathepsin E were randomly distributed, with expression in the urothelium being markedly unstable. Almost all areas of squamous cell proliferation in TCC were negative for cathepsin E. Instability of cathepsin E expression in rat urothelium therefore appears characteristic for carcinogenesis and offers the possibility of using this feature as an early biomarker for urinary bladder carcinogenesis.

Animals↗
PubMed1996

Enterobacter kobei sp. nov., a new species of the family Enterobacteriaceae resembling Enterobacter cloacae.

The name Enterobacter kobei sp. nov. is proposed for a group of organisms referred to as NIH Group 21 at the National Institute of Health, Tokyo. The members of this species are Gram-negative, motile rods conforming to the definition of the family Enterobacteriaceae. The DNA relatedness of 23 strains of NIH Group 21 to the representative proposed as the type strain of this species averaged 82% at 70 degrees C, whereas the relatedness to other species within the family Enterobacteriaceae was less than 42%. Because the phenotypic resemblance to Enterobacter cloacae is very close and the DNA relatedness (12-42%) is closer to species of the genus Enterobacter than to other species of the family, the members of NIH Group 21 were placed in the genus Enterobacter. Close phenotypic and genetic relationships were also found between NIH Group 21 and a member of a group of organisms referred to as Enteric Group 69 at the Centers for Disease Control and Prevention (CDC), Atlanta, Georgia, USA. It is suggested that the latter could be regarded as a subspecific rank of E. kobei, though this is subject to study of further strains. The majority of strains of E. kobei were isolated from clinical specimens. A culture of the type strain (NIH 1485-79) has been deposited in the Japan Collection of Microorganisms as JCM 8580.

Bacteriological Techniques↗
PubMed1996

Antisense oligonucleotide to NOR-1, a novel orphan nuclear receptor, induces migration and neurite extension of cultured forebrain cells.

We previously identified a novel orphan nuclear receptor referred to as NOR-1 from rat forebrain cells. This study examined the role of NOR-1 in primary cultured forebrain cells by selectively inhibiting NOR-1 expression by addition of antisense oligonucleotide to the culture media. Treating cells with the antisense oligomer resulted in the following dramatic morphological changes: (i) cell migration, (ii) extension of processes, and (iii) formation of cellular aggregates. Immunocytochemistry for microtubule-associated protein 2 revealed that the processes were filled with neurites growing from neuronal cells. These findings suggest that NOR-1 may be involved in the molecular mechanisms regulating neural differentiation.

Animals↗
PubMed1996

Increased risk of Helicobacter pylori associated with birth in wartime and post-war Japan.

BACKGROUND: Helicobacter pylori infection is now widely recognized as a cause of stomach cancer. We assessed trends in H. pylori infection in Japan, a population with high rates of gastric malignancy. METHODS: Using an enzyme-linked immunosorbent assay (ELISA), we tested sera collected between 1980 and 1993 from Tokyo University Hospital patients for anti-H. pylori IgG. Patients ranged in age from 0 to 94 years. Helicobacter pylori prevalence was then assessed for age and/or birth cohort effects. RESULTS: Of 1207 sera, 470 (38.9%) were positive for H. pylori IgG. By univariate analysis, both older age and birth in an earlier decade were associated with an increased risk of infection. Age-specific prevalence of H. pylori by birth cohort suggested increases in infection during the decades from 1900 to 1959, and age-specific decreases since 1960. In multivariate analysis, H. pylori infection increased with age and was most prevalent among those born in the 1940s and 1950s. CONCLUSION: Relative to other birth cohorts, people born in the 1940s and 1950s have a higher prevalence of H. pylori. This increased prevalence of infection among those born in wartime Japan likely attests to the impact of compromised living conditions on acquisition of H. pylori, and may portend continued high rates of gastric cancer in forthcoming years.

Adolescent↗
PubMed1996

Re-speciation of the original reference strains of serovars in the Citrobacter freundii (Bethesda-Ballerup group) antigenic scheme of West and edwards.

The antigenic scheme for the Bethesda-Ballerup group of bacteria established by West and Edwards in 1954 has continued to be applied as a serotyping scheme for Citrobacter freundii. In 1993, however, the classification of the Citrobacter was drastically revised and the species C. freundii redefined by Brenner et al. Accordingly, to judge the propriety to continuously use a single antigenic scheme for the C. freundii complex, the 90 reference strains listed in the antigenic scheme for C. freundii by West and Edwards were characterized phenotypically and specified based on the revised classification. Of these 90 strains, two strains of Hafnia alvei and one of Escherichia coli were found. Among the remaining 87 reference strains, Citrobacter youngae was the predominant species (40 strains), followed by Citrobacter braakii (25 strains), Citrobacter werkmanii (13 strains), and the unnamed Citrobacter genospecies 10 of Brenner et al (six strains). Citrobacter freundii, as redefined, accounted for only three strains and ranked behind the other four species. No overlapping with most of the 42 O-groups and 82 H-antigens was recognized between species with few exceptions. O-groups 1-9 inclusive, which were estimated to represent more than 90% of the former C.freundii strains, occurred in strains of C. youngae and C. braakii; and all nine strains of O-group 29, formerly known as the Ballerup group, were identified as C. braakii. These findings suggest that further study of the serotyping system is needed for all H2S-producing Citrobacter species.

Antigens, Bacterial↗
PubMed1996

Association between family history and gastric carcinoma among young adults.

The relationship between family history of gastric carcinoma and gastric carcinoma in Japanese under 40 years of age was analyzed. The subjects were 108 gastric carcinoma patients (86% were diffuse type) at 9 hospitals in the Kanto area of Japan. Firstly, incidence of gastric carcinoma among the parents of the subjects were compared with that in the general population. Observed/expected (O/E) ratios (P-value) were 1.8 (0.06) for all subjects, 1.3 (0.62) for male subjects, 2.1 (0.04) for female subjects, 0.5 (0.41) for early carcinoma, 2.6 (P<0.01) for advanced carcinoma, 2.3 (0.22) for intestinal-type carcinoma and 1.7 (0.13) for diffuse-type carcinoma. Association between gastric carcinoma and parents' history of gastric carcinoma was strong among women and regarding advanced carcinoma, and the difference in O/E ratios between early and advanced carcinoma was remarkable. Secondly, factors related to advanced-stage gastric carcinoma were analyzed. Histological type (diffuse and intestinal types) was not related, but family history of gastric carcinoma among parents and grandparents was related to advanced stage, and the relationship was independent of other factors. The odds ratio (95% confidence interval) was 3.3 (1.1-9.9). Family history may be related to stage of gastric carcinoma through its relationship to the manner or speed of the tumor's progression. We hypothesis that some genetic factor exists which is involved both in progression from early to advanced stage and in occurrence of gastric carcinoma.

Adolescent↗