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Biomedical subjects

M Yamazaki

Publications and source records attributed to M Yamazaki.

At least 55 records · Page 3Linked to original sources
PubMed2002

Postnatal changes in ghrelin mRNA expression and in ghrelin-producing cells in the rat stomach.

Ghrelin was recently isolated from the rat stomach as an endogenous ligand for the GH secretagogue receptor. Although it is well known that a large amount of ghrelin is produced in the gastrointestinal tract, developmental changes in ghrelin mRNA expression and differentiation of ghrelin-immunopositive (ghrelin-ip) and mRNA-expressing (ghrelin-ex) cells in the stomach have not been elucidated. In this study, we therefore investigated the changes in ghrelin mRNA expression levels and in the numbers of ghrelin-ip and -ex cells in the stomachs of 1- to 8-week-old male and female rats by Northern blot analysis, immunohistochemistry and in situ hybridization. Northern blot analysis showed that the level of weak ghrelin mRNA expression was low in the postnatal period but then increased in a dimorphic pattern, i.e. transient stagnation at 4 weeks in the male rats and at 5 weeks in the female rats. The number of ghrelin-ip and ghrelin-ex cells also increased after birth, and more numerous ghrelin cells were found in female rats than in male rats, and this finding was confirmed by Northern blot analysis. Ghrelin-ip and -ex cells first appeared in the glandular base of the fundic gland and then they were found in the glandular base and the glandular neck at 3 weeks of age, suggesting that the distribution of ghrelin cells is extended from the glandular base to the glandular neck during the postneonatal development period. This is the first report on detailed changes in postneonatal ghrelin expression level and in the number of ghrelin cells in the rat stomach. The sexual dimorphism of ghrelin expression and ghrelin cell differentiation suggest that ghrelin plays an important physiological role in the stomach.

Animals↗
PubMed2002

Simultaneous removal of nitrogen and phosphorus with A2/O process using immobilized media.

It is necessary to introduce nitrogen and phosphorus removal processes in the existing wastewater treatment plants of Fukuoka City to improve the water quality of Hakata Bay. An A2/O (anaerobic-anoxic-oxic) process using immobilized media is proposed here, as a high-end technology to meet stricter discharge standards when faced with treatment space limitations. In order to investigate the applicability of the process, a pilot-scale study using municipal wastewater was conducted. Fluidized immobilization media were added to the aerobic reactor to maintain a high concentration of nitrifying bacteria and nitrification rate. Relationships between nutrient removal performance and varied operating conditions were examined. The results of the pilot plant test indicated that the process performs well for removal of nitrogen and phosphorus. Under the condition of HRT = 8 hr, it was possible to obtain an effluent water quality as follows: T-N<8.0 mg/L; T-P<1.0 mg/L. It was observed that reaction time needed for a complete nitrification was shortened by the addition of immobilized media to the aerobic reactor, and longer reaction time would be needed for a completed phosphorus uptake process other than complete nitrification in an aerobic tank. Therefore, the phosphorus uptake rate, as well as nitrification process, should be considered as one of the important factors affecting the design parameters of an aerobic reactor.

Bacteria, Aerobic↗
PubMed2001

La(3+) stabilizes the hexagonal II (H(II)) phase in phosphatidylethanolamine membranes.

The mechanism of the effects of the lanthanum ion (La(3+)) and the gadolinium ion (Gd(3+)), which are lanthanides, on the function of membrane proteins and the stability of the membrane structure is not well understood. We investigated the effects of La(3+) on the stability of the hexagonal II (H(II)) phase of the phosphatidylethanolamine (PE) membrane at 20 degrees C by small-angle X-ray scattering. As PE membrane we used DPOPE (dipalmitoleoylphosphatidylethanolamine) membrane, which was in the L(alpha) phase in 10 mM PIPES buffer (pH 7.4) at 20 degrees C. An L(alpha) to H(II) phase transition occurred in the DPOPE membrane at 1.4 mM La(3+) in 0 M KCl, and at 0.4 mM La(3+) in 0.5 M KCl and above the critical concentrations the membranes were in the H(II) phase, indicating that La(3+) stabilizes the H(II) phase rather than the L(alpha) phase. The basis vector length, d, of DPOPE and DOPE (dioleoylphosphatidylethanolamine) membranes containing 16 wt% tetradecane in excess water condition did not change with an increase in La(3+) concentration, suggesting that La(3+) did not change the spontaneous curvature of these PE monolayer membranes. The chain-melting transition temperature of the dielaidoylphosphatidylethanolamine membrane increased with an increase in La(3+) concentration, indicating that the lateral compression pressure increased. To elucidate the effects of a small percentage of 'guest' lipids with longer acyl chains than the average length of 'host' lipids on the stability of the H(II) phase, we investigated the effects of the concentration of a guest lipid (DOPE) in a host lipid (DPOPE) membrane on their phase behavior and structure. 12 mol% DOPE induced an L(alpha) to H(II) phase transition in DOPE/DPOPE membrane, without changing the spontaneous curvature of the monolayer membrane. We found that Ca(2+) also induced an L(alpha) to H(II) phase transition in the DPOPE membrane, and compared the effects of Ca(2+) on PE membranes with those of La(3+). Based on these results, we have proposed a new model for the mechanism of the L(alpha) to H(II) phase transition and the stabilization of the H(II) phase by La(3+).

Calcium↗
PubMed2001

Identification and antioxidant activity of several pigments from the residual green tea (Camellia sinensis) after hot water extraction.

Antioxidant activity of green tea extract or tea-derived polyphenols has been extensively studied. However, antioxidant activity in the non-polyphenolic fraction of green tea has been poorly analyzed. In the present study, we analyzed the antioxidant activity of the non-polyphenolic fraction of the residual green tea (Camellia sinensis) after hot water extraction using the aluminum chloride method. The non-polyphenolic fraction of residual green tea caused a significant suppression against hydroperoxide generation from oxidized linoleic acid in a dose-dependent manner. When the concentrate of the non-polyphenolic fraction was applied to a silica gel TLC plate and developed, six color spots were observed, which were considered to be chlorophylls a and b, pheophytins a and b, carotenoids, such as beta-carotene and lutein according to their specific colors, Rf values of silica gel TLC and spectrophotometric properties. Among these pigments, pheophytins a and b showed relatively abundant amounts, and the second major group of the pigment was chlorophylls a and b, and carotenoids such as beta-carotene and lutein indicated lower concentrations. Although all these pigments exhibited significant antioxidant activities, the ranks of suppressive activity against hydroperoxide generation were chlorophyll a > lutein > pheophytin a > chlorophyll b > beta-carotene > pheophytin b. These results suggest that the non-polyphenolic fraction of residual green tea has a potent suppressive activity against hydroperoxide generation from oxidized linoleic acid, which is derived from the antioxidant activities of chlorophylls a and b, pheophytins a and b, beta-carotene and lutein. This finding also implies that the combined intake of polyphenols in water-soluble fraction and antioxidative pigments in the non-polyphenolic fraction of green tea will be more efficient to prevent life style-related chronic diseases.

Acetone↗
PubMed2001

Measurement of platelet fibrinogen binding and p-selectin expression by flow cytometry in patients with cerebral infarction.

We determined the percentages of fibrinogen-bound and P-selectin-expressed platelets in whole blood using flow cytometry in 254 patients with various cerebral infarction subtypes, as well as in 30 age-matched controls. Patients with atherothrombotic stroke showed significant increases in both fibrinogen-bound and P-selectin-expressed platelets. Patients with lacunar stroke also showed significant increases in both of them, but the percentage of P-selectin expression was significantly lower than that in atherothrombotic stroke. Patients with cardioembolic stroke showed a significant increase in P-selectin-expressed platelets without any increase in fibrinogen-bound platelets. Platelet fibrinogen binding and P-selectin expression were significantly lower in patients treated with ticlopidine but not with aspirin than in those not treated with any antiplatelet agent, and were lowest in those treated with both ticlopidine and aspirin. Our findings suggest that expression of adhesion molecules on platelet membrane surface differs among the patients with subtypes of ischemic stroke and differs among the types of antiplatelet regimens.

Adult↗
PubMed2001

Immunohistochemical analyses of thyroid-specific enhancer-binding protein in the fetal and adult rat hypothalami and pituitary glands.

Thyroid-specific enhancer-binding protein (T/EBP), also known as NKX2.1 or TTF-1, regulates the expression of thyroid- and lung-specific genes. The t/ebp/Nkx2.1-null mutant mouse was stillborn but lacked the thyroid gland, pituitary gland, ventral region of the forebrain and normal lungs. These data demonstrated that T/EBP/NKX2.1 plays an important role not only in tissue-specific gene expressions in adults but also in genesis of these organs during development. Although the expression of t/ebp/Nkx2.1 in the brain has been reported, its function in the brain remains unknown. The present study was designed to determine the localization of T/EBP/NKX2.1 in the hypothalamus and pituitary gland of fetal and adult rats by immunohistochemistry as the first step toward understanding the function of T/EBP/NKX2.1 in the rat brain. In the fetal rat hypothalamus, T/EBP/NKX2.1 was localized widely in the ventral hypothalamic areas. In the adult rat brain, T/EBP/NKX2.1 was localized in the ventromedial hypothalamic nucleus, medial tuberal nucleus, arcuate nucleus and mammillary body. No T/EBP/NKX2.1 immunoreactivity was observed in the anterior or intermediate lobe of the pituitary gland in either fetal or adult rats. On the other hand, immunoreactive T/EBP/NKX2.1 was found in the posterior lobe of the pituitary gland. This paper presents results of detailed analyses of the distributions of T/EBP/NKX2.1 protein in the fetal and adult rat hypothalami and pituitary glands, and these results should provide important information for understanding the function of T/EBP/NKX2.1 in the brain.

Age Factors↗
PubMed2001

The opioid peptide analogue biphalin induces less physical dependence than morphine.

We compared the physical dependence liability of biphalin, a dimeric enkephalin analogue that possesses high antinociceptive activity, with that of morphine in equipotent intravenous doses. Naloxone challenge produced severe withdrawal signs after a 5-day infusion of morphine but only minor withdrawal signs after a 5-day biphalin infusion. In a cross-dependence study, biphalin did not suppress body weight loss after morphine withdrawal, but successfully suppressed weight loss after pentazocine withdrawal. These data support consideration of biphalin as a new analgesic with a novel pharmacological profile and minimum dependence liability.

Analgesics, Opioid↗
PubMed2001

Construction of regulated nanospace around a porphyrin core.

A series of 1,3,5-phenylene-based rigid dendritic porphyrins were synthesized by Suzuki coupling between a porphyrin core and dendron units. The intramolecular energy transfer was studied by absorption and fluorescence spectroscopies. The encapsulation of the porphyrin core within the 1,3,5-phenylene dendron units was found to provide highly efficient energy transfer from the dendron units to the porphyrin core. The dendritic wedge structure affected the energy transfer efficiency. The 1,3,5-phenylene-based rigid dendron units act as highly efficient light-harvesting antennae. These dendritic porphyrins have also been examined as C(60) hosts and substrate-selective oxidation catalysts. The attachment of the second generation of 1,3,5-phenylene-based dendron units with the porphyrin core enabled a stable inclusion of C(60) in toluene. Furthermore, the size and shape of the nanospace in the rigid dendritic porphyrins were found to affect the selectivity of substrates in the catalytic olefin oxidations.

Energy Transfer↗
PubMed2001

Isolation and characterization of vascular smooth muscle cell growth promoting factor from bovine ovarian follicular fluid and its cDNA cloning from bovine and human ovary.

A protein possessing vascular smooth muscle cell (SMC) growth-promoting activity (VSGP) was purified from bovine ovarian follicular fluid. The purified protein showed a broad band on SDS-PAGE with an apparent molecular mass of 90-100 kDa. The purified protein was characterized by amino acid sequence analysis of its N-terminal and internal peptides. Based on the information of the peptide sequences, bovine ovarian cDNA library was screened and cDNA clones encoding the protein were isolated. Human homolog of the protein was also cloned from human ovarian cDNA library. Nucleotide sequence analysis revealed that bovine VSGP transcript has a 2421-bp open reading frame, which encodes a protein of 807 amino acid residues. A homology search indicated that bovine and human VSGP are counterparts of rat F-spondin, which has been previously identified as a promoter molecule of neurite extension in rat fetal floor plate. RNA blot analysis showed wide distribution of VSGP/F-spondin transcripts in fetal and adult human tissues. Especially the expression was highest in the adult human ovary. The purified bovine VSGP/F-spondin showed vascular SMC growth promoting activity with an ED(50) value of 10(-8) M. Together with these findings, we demonstrated here that VSGP/F-spondin is a major factor for vascular SMC proliferation in the ovary. In conclusion, our present study provides a distinct and important function of VSGP/F-spondin as a strong VSMC proliferation promoting factor, in addition to the previously proposed function in neuronal system, and also provides insight into mechanisms underlying vascular SMC proliferation during ovarian folliculogenesis.

Amino Acid Sequence↗
PubMed2001

Mechanical unfolding of single filamin A (ABP-280) molecules detected by atomic force microscopy.

Filamin A (ABP-280), which is an actin-binding protein of 560 kDa as a dimer, can, together with actin filaments, produce an isotropic cross-linked three-dimensional network (actin/filamin A gel) that plays an important role in mechanical responses of cells in processes such as maintenance of membrane stability and translational locomotion. In this study, we investigated the mechanical properties of single filamin A molecules using atomic force microscopy. In force-extension curves, we observed sawtooth patterns corresponding to the unfolding of individual immunoglobulin (Ig)-fold domains of filamin A. At a pulling speed of 0.37 microm/s, the unfolding interval was sharply distributed around 30 nm, while the unfolding force ranged from 50 to 220 pN. This wide distribution of the unfolding force can be explained by variation in values of activation energy and the width of activation barrier of 24 Ig-fold domains of the filamin A at the unfolding transition. This unfolding can endow filamin A with great extensibility. The refolding of the unfolded chain of filamin A occurred when the force applied to the protein was reduced to near zero, indicating that its unfolding is reversible. Based on these results, we discuss here the physiological implications of the mechanical properties of single filamin A molecules.

Contractile Proteins↗
PubMed2001

Differential palmitoylation of two mouse glutamate receptor interacting protein 1 forms with different N-terminal sequences.

Glutamate receptor interacting protein (GRIP) is a member of the PDZ domain-containing protein family that is localized in the postsynaptic density area. This protein has been reported to interact specifically with the C-termini of AMPA-selective glutamate receptor channel subunits, GluRalpha2 and GluRalpha3 through its PDZ domains. To clarify the physiological functions of GRIP, we cloned mouse GRIP1, and found that there are three sites for alternative splicing and two putative translational start codons by characterizing GRIP1 cDNA clones and reverse transcription-polymerase chain reaction products. Metabolic labeling of COS-7 cells expressing two N-terminal GRIP1 proteins demonstrated that these proteins differed in their pattern of palmitoylation. These findings suggested that the molecular diversity of GRIP1 underlies the localization and functional heterogeneity of this protein.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Reaction mechanism from leucoanthocyanidin to anthocyanidin 3-glucoside, a key reaction for coloring in anthocyanin biosynthesis.

In the conversion from colorless leucoanthocyanidin to colored anthocyanidin 3-glucoside, at least two enzymes, anthocyanidin synthase (ANS) and UDP-glucose:flavonoid 3-O-glucosyltransferase (3-GT), are postulated to be involved. Despite the importance of this reaction sequence for coloring in anthocyanin biosynthesis, the biochemical reaction mechanism has not been clarified, and the possible involvement of a dehydratase has not been excluded. Here we show that recombinant ANSs from several model plant species, snapdragon, petunia, torenia, and maize, catalyze the formation of anthocyanidin in vitro through a 2-oxoglutarate-dependent oxidation of leucoanthocyanidin. Crude extracts of Escherichia coli, expressing recombinant ANSs from these plant species, and purified recombinant enzymes of petunia and maize catalyzed the formation of anthocyanidin in the presence of ferrous ion, 2-oxoglutarate, and ascorbate. The in vitro formation of colored cyanidin 3-glucoside from leucocyanidin, via a cyanidin intermediate, was demonstrated using petunia ANS and 3-GT. The entire reaction sequence did not require any additional dehydratase but was dependent on moderate acidic pH conditions following the enzymatic steps. The present study indicated that the in vivo cytosolic reaction sequence involves an ANS-catalyzed 2-oxoglutarate-dependent conversion of leucoanthocyanidin (flavan-3,4-cis-diol) to 3-flaven-2,3-diol (pseudobase), most probably through 2,3-desaturation and isomerization, followed by glucosylation at the C-3 position by 3-GT.

Anthocyanins↗
PubMed2001

Physical and transcriptional map of a 311-kb segment of chromosome 18q21, a candidate lung tumor suppressor locus.

Here, we report the complete genomic sequence and the characterization of the 311-kb region of 18q21, a candidate tumor suppressor locus containing a region of homozygous deletion in a lung cancer cell line, Ma29. This region contained two known genes, SMAD4 and ME2 (mitochondrial malate oxydoreductase), and two novel genes, D29 (deleted in Ma29 HGMW-approved symbol ELAC1), encoding an evolutionarily conserved protein, and B29 (beside the Ma29 deletion HGMW-approved symbol C18orf3), with no significant homology to any known genes. The deleted DNA segment in Ma29, which was estimated to be 195 kb in size, included all the coding exons of ME2 and D29, but not the coding exons of SMAD4 and B29. The deleted region also included exon 0, a 5'-noncoding exon, of SMAD4, and the expression of SMAD4 was greatly reduced in Ma29 cells. Mutations of SMAD4 and D29 were detected in 1 of 45 lung cancer cell lines examined, while those of ME2 and B29 were not detected, indicating that these four genes are not major targets for 18q21 deletions. The physical and transcriptional map constructed in this study will provide basic information for the identification of a tumor suppressor gene(s) at 18q21 involved in lung carcinogenesis.

Antigens, CD↗
PubMed2001

Receptor activator of nuclear factor kappaB ligand (RANKL) is a key molecule of osteoclast formation for bone metastasis in a newly developed model of human neuroblastoma.

Neuroblastoma originates from neural crest cells and is the most common extracranial solid tumor in childhood. Bone metastasis in neuroblastoma is an unfavorable prognostic factor even with intensive therapy. In the present study, we screened four cell lines of human neuroblastoma (NB-1, NB-16, NB-19, and NH-6) for tumorigenicity and metastatic capacity in nude mice and found that NB-19 cells caused osteolytic lesions after s.c. injection into mice. To detect micrometastases in the host tissue, we performed two kinds of PCR-based metastasis assays: (a) genomic PCR assay using the primers for human genome-specific Alu sequence; and (b) reverse transcription-nested PCR assay that detects the expression of tyrosine hydroxylase, a marker specific for neuroblastoma. The results of these PCR assays revealed the colonization of human neuroblastoma cells in the bone marrow of the mice that had received the s.c. injection of NB-19 cells. Because osteoclastic bone resorption has been reported to play important roles in osteolysis in some cancers such as breast cancer, we next examined the osteoclast (OC)-inducing activity of NB-19 cells using a coculture system in which NB-19 cells were cultured with murine bone marrow cells containing OC precursors and stromal cells. NB-19 cells induced tartrate-resistant acid phosphatase-positive multinucleated OC-like cells without requirement of 1,25-dihydroxyvitamin D3 or other osteoclastogenic stimulators. To investigate the factors involved in the osteoclastogenesis in the coculture of mouse marrow cells and NB-19 cells, we performed reverse transcription-PCR analysis and revealed the increased expression of receptor activator of nuclear factor kappaB ligand (RANKL) in the coculture compared with the culture of bone marrow cells alone. Interleukin-1alpha and cyclooxygenase-2 expression in the murine marrow cells was also increased in the presence of NB-19 cells. To further study the role of RANKL in the OC-like cell formation in the coculture of NB-19 cells and murine marrow cells, an expression vector encoding the active portion of the murine osteoprotegerin, which is the native inhibitor of RANKL action, was constructed and introduced into COS-7 cells. The conditioned media of the COS-7 cells transfected with the osteoprotegerin expression vector effectively blocked OC-like cell formation in the coculture of the bone marrow cells and NB-19 cells. These results suggested that in the bone microenvironment of NB-19-bearing mice, the stimulated expression of RANKL plays an important role in OC formation, leading to osteolytic bone metastasis.

Acid Phosphatase↗
PubMed2001

Securiosides A and B, novel acylated triterpene bisdesmosides with selective cytotoxic activity against M-CSF-stimulated macrophages.

We report the discovery of securiosides A (1) and B (2), novel acylated triterpene bisdesmosides, isolated from the roots of Securidaca inappendiculata. Securiosides A and B showed potent selective cytotoxic activity against M-CSF-stimulated macrophages and were suggested to have potential as new agents for the treatment of inflammatory diseases such as RA and atherosclerosis.

Animals↗
PubMed2001

Alpha-synuclein-positive structures in cases with sporadic Alzheimer's disease: morphology and its relationship to tau aggregation.

Alzheimer's disease (AD) and Parkinson's disease share common clinical and pathological features. In this study, we examined the relationship between AD pathology and alpha-synuclein aggregation. The frequency and distribution of alpha-synuclein-positive structures were systematically investigated in 27 cases with sporadic AD by alpha-synuclein immuno-histochemistry. Thirteen (48.2%) of 27 cases had various alpha-synuclein-positive structures as well as Lewy bodies. The frequency and density of senile plaques and neurofibrillary tangles were not significantly different between cases with alpha-synuclein structures and those without. alpha-Synuclein-positive structures were found most frequently in the amygdala. The alpha-synuclein-positive inclusions that are different from Lewy bodies were observed at the highest rate in the hippocampus. The discovery of alpha-synuclein as the constituent of Lewy bodies facilitated the detection of Lewy-related structures even in AD cases with widespread and numerous neurofibrillary tangles. alpha-Synuclein-positive inclusions except for Lewy bodies are exposed, and the distribution of them indicates that Lewy body formation may be influenced by the degree of tau aggregation. This study also supports the suggestion that cases with AD pathology can be classified into two groups according to the existence or absence of alpha-synuclein aggregation.

Aged↗
PubMed2001

One missense mutation in the factor X gene causing factor X deficiency--factor X Kanazawa.

We investigated the molecular basis of factor X deficiency in a Japanese patient whose factor X activity and antigen level were 45% and 50% of normal control values, respectively. All exons and intron/exon junctions of the factor X gene were studied using a strategy combining polymerase chain reaction (PCR) amplification and nonradioactive single-strand conformational polymorphism (SSCP) analysis. Exon 5, containing the DNA fragment of the proband, showed aberrant migration by SSCP analysis. All exon-containing DNA fragments amplified by PCR were sequenced, and it was revealed that the proband was a heterozygote for a G --> A substitution in exon 5 of the factor X gene of the proband. This mutation predicts an amino acid replacement of arginine (Arg) for glycine (Gly) at codon 114 in the second EGF-like domain.

Aged↗