Biomedical subjects

M Minami

Publications and source records attributed to M Minami.

At least 91 records · Page 5Linked to original sources

PubMed2000

Molecular cloning of a novel scavenger receptor for oxidized low density lipoprotein, SR-PSOX, on macrophages.

Receptor-mediated endocytosis of oxidized low density lipoprotein (OxLDL) by macrophages has been implicated in foam cell transformation in the process of atherogenesis. Although several scavenger receptor molecules, including class A scavenger receptors and CD36, have been identified as OxLDL receptors on macrophages, additional molecules on macrophages may also be involved in the recognition of OxLDL. From a cDNA library of phorbol 12-myristate 13-acetate-stimulated THP-1 cells, we isolated a cDNA encoding a novel protein designated SR-PSOX (scavenger receptor that binds phosphatidylserine and oxidized lipoprotein), which acts as a receptor for OxLDL. SR-PSOX was a type I membrane protein consisting of 254 amino acids, expression of which was shown on human and murine macrophages with a molecular mass of 30 kDa. SR-PSOX could specifically bind with high affinity, internalize, and degrade OxLDL. The recognition of OxLDL was blocked by polyinosinic acid and dextran sulfate but not by acetylated low density lipoprotein. Taken together, SR-PSOX is a novel class of molecule belonging to the scavenger receptor family, which may play important roles in pathophysiology including atherogenesis.

Amino Acid Sequence↗

PubMed2000

Pathogenesis of vascular dementia in stroke-prone spontaneously hypertensive rats.

Stroke-prone spontaneously hypertensive rats (SHRSP) are the best model for essential hypertension and stroke. In this study, one investigated whether SHRSP might be a useful animal model for vascular dementia. An impairment of learning-memory function was found in SHRSP. A disturbance in circadian rhythm after stroke in SHRSP was clarified. Desynchronization of light and dark alternation cycles and abnormal rhythm were also demonstrated. These observations point to the possibility that the decreased passive avoidance response observed in SHRSP might be similar to the phenomenon of memory impairment in patients with vascular dementia. The behavioral changes in ambulation in SHRSP, including the desynchronization between light and dark alternation cycles and the abnormal rhythm before death, might correspond to the behavioral changes associated with the delirium-state observed in patients with dementia. Cerebral cortex levels of acetylcholine and choline in SHRSP decreased significantly as compared with the Wistar Kyoto rats (WKY) control group. Hippocampal levels of acetylcholine and choline in SHRSP decreased significantly as compared with those in WKY. Moreover, a correlation between passive avoidance response latency and hippocampal acetylcholine levels was observed. These findings suggest that decreased acetylcholine levels in both the cerebral cortex and the hippocampus may be related to the impairment of learning-memory function and abnormal behavior. In SHRSP, increases in blood viscosity, hematocrit and fibrinogen might produce the formation of thrombus and induce cerebral infarction. Some histopathological findings caused by cerebrovascular disorder in human brain very similar to those observed in the SHRSP brain. On the other hand, so called 'senile changes' were detected only in the human case, and not observed in the SHRSP.

Acetylcholine↗

PubMed2000

Neurochemistry and neuropharmacology of emesis - the role of serotonin.

Emesis is an instinctive defense reaction caused by the somato-autonomic nerve reflex which is integrated in the medulla oblongata. Emesis caused by cytotoxic drugs and radiation is associated with an increase in the concentration of 5-hydroxytryptamine (5-HT) in the intestinal mucosa and in the brainstem. 5-HT released from enterochromaffin (EC) cells, which synthesize and secrete 5-HT, stimulates the 5-HT(3) receptors on the adjacent vagal afferent nerves. This vagal afferent nerve depolarization may evoke the vomiting reflex. This review describes the role of 5-HT in anticancer drug-induced emesis from the viewpoint of 5-HT release from EC cells and afferent vagus nerve activity.

Animals↗

PubMed2000

Expression of inducible nitric oxide synthase mRNA and production of nitric oxide are induced by adenosine triphosphate in cultured rat microglia.

The effect of adenosine triphosphate (ATP) on the expression of the inducible nitric oxide synthase (iNOS) mRNA and production of nitric oxide in cultured rat microglia was examined. ATP induced iNOS mRNA dose-dependently (100-1,000 microM). The induction began within 1 h after addition of ATP (100 microM) with peak expression occurring at 6 h. The release of nitric oxide to culture medium was significantly increased by the treatment with ATP (100 and 1,000 microM) for 12 and 24 h. These results indicate that ATP is a potential mediator to induce iNOS mRNA expression and NO production in microglia.

Adenosine Triphosphate↗

PubMed2000

Immunotoxicity of N,N-diethylaniline in mice: effect on natural killer activity, cytotoxic T lymphocyte activity, lymphocyte proliferation response and cellular components of the spleen.

We previously found that N,N-diethylaniline increased the frequency of sister chromatid exchange (SCE) of human lymphocytes to about five times that of the control value, and was as toxic as cyclophosphamide used as a positive control for SCE. To explore whether N,N-diethylaniline affects the function of lymphocytes, we evaluated its immunotoxicity using CBA/N mice. The mice were divided into four groups and received 0, 100, 200, or 400 mg/kg body weight of N,N-diethylaniline by subcutaneous injection. The following items were investigated on days 3 and 7 after injection: body weight, weight of spleen, number of splenocytes, natural killer (NK) and cytotoxic T lymphocyte (CTL) activities, and concanavalin A (Con A)- and lipopolysaccharide (LPS)-stimulated lymphocyte proliferation using splenocytes. The following splenocyte phenotypes were also quantified by flow cytometry: (1) B cells; (2) total T cells; (3) CD4(+) and CD8(+) T cells; (4) NK; (5) macrophages and (6) nucleated erythrocytes. The splenic NK and CTL activities in exposed groups significantly decreased compared to the control in a dose-dependent manner and lymphocytes from the 200 and 400 mg/kg groups showed significantly higher spontaneous proliferation. The weight of the spleen and number of splenocytes were significantly higher in exposed groups than in the control. N,N-Diethylaniline also increased the percentages of macrophages, nucleated erythrocytes and B cells in the spleen. On the other hand, N,N-diethylaniline did not affect LPS-stimulated B cell and Con A-stimulated T cell proliferation, or the percentages of NK, total T, and CD4(+) and CD8(+) T cells in the spleen or the body weight of mice. The above findings indicated that N,N-diethylaniline selectively inhibited splenic NK and CTL activity and this inhibition was due to decreased NK and CTL functions, but not due to changes in the numbers of splenic NK and T cells.

Aniline Compounds↗

PubMed2000

Transforming growth factor-beta(1) increases the expression of lectin-like oxidized low-density lipoprotein receptor-1.

Lectin-like oxidized low-density lipoprotein (Ox-LDL) receptor-1 (LOX-1) is a novel cell-surface receptor for Ox-LDL, which can be expressed by vascular endothelial cells, smooth muscle cells, and macrophages. On the other hand, transforming growth factor (TGF)-beta(1), which plays crucial roles in vascular remodeling and the pathogenesis of atherosclerosis, has been shown to inhibit expression of class A scavenger receptors and CD36 in macrophages. Here we provide the evidence that TGF-beta(1) (0.1-10 ng/mL) induces LOX-1 protein and mRNA expression in both bovine aortic endothelial cells and smooth muscle cells in a dose- and time-dependent fashion, probably at the transcriptional level. TGF-beta(1) also upregulates LOX-1 mRNA expression in murine peritoneal macrophages. Thus TGF-beta(1) can highly induce LOX-1 expression in vascular endothelial cells, smooth muscle cells, and macrophages, suggesting that TGF-beta(1) appears one of the key regulators that modulates expression of scavenger receptors.

Animals↗

PubMed2000

Dopamine as a novel antioxidative agent for rat vascular smooth muscle cells through dopamine D(1)-like receptors.

BACKGROUND: To elucidate the roles of vascular D(1)-like receptors in atherosclerosis, the effects of the specific D(1)-like agonists on platelet-derived growth factor (PDGF)-BB-mediated oxidative stress in vascular smooth muscle cells (VSMCs) were studied. METHODS AND RESULTS: Immunohistochemical studies demonstrated the coexistence of D(1A) and D(1B) dopamine receptors in VSMCs. Western blotting revealed a band of approximately 70 kDa for D(1A) and D(1B) dopamine receptors. VSMCs stimulated by PDGF-BB exhibited increased oxidative stress directly measured by flow cytometry. These effects were prevented by dopamine, SKF 38393, or YM 435, and this prevention was reversed by Sch 23390. These effects were blocked by a specific protein kinase A (PKA) inhibitor, N-(2-[p-bromocinnamylamino]ethyl)-5-isoquinolinesulfonamide (H 89). The PDGF-BB-mediated increase in oxidative stress of VSMCs was significantly suppressed by the indirect phospholipase D (PLD) inhibitor suramin or the specific protein kinase C (PKC) inhibitor calphostin C. Both antisense but neither sense nor scrambled oligonucleotides to D(1A) and D(1B) receptors inhibited dopamine-induced suppression of increase in oxidative stress of VSMCs induced by PDGF-BB. CONCLUSIONS: These findings suggest that vascular D(1)-like receptors (D(1A) and D(1B) receptors) inhibit any increase in oxidative stress of VSMCs, possibly through activation of PKA and suppression of PLD and PKC.

Animals↗

PubMed2000

The by-products generated during sarin synthesis in the Tokyo sarin disaster induced inhibition of natural killer and cytotoxic T lymphocyte activity.

More than 5000 passengers on Tokyo subway trains were injured by the nerve gas, sarin and its by-products. Analysis of phosphor-carrying metabolites of sarin and its by-products in urine samples from the victims suggested that they were exposed not only to sarin, but also by-products generated during sarin synthesis, i.e. diisopropyl methylphosphonate (DIMP) and diethyl methylphosphonate (DEMP). We suspected genetic after-effects due to sarin by-products, thus, we checked the frequency of sister chromatid exchange (SCE) and found that SCE was significantly higher in the victims than in a control group, and that DIMP and DEMP significantly induced human lymphocyte SCE in vitro. In the present study, to explore whether DIMP and DEMP, which induced a high frequency of SCE of lymphocytes, also affected the lymphocyte functions, we examined the effect of DIMP and DEMP on splenic natural killer (NK) and splenic cytotoxic T lymphocyte (CTL) activity in mice, and NK activity of human lymphocytes in vitro. We found that DIMP and DEMP significantly inhibited NK and CTL activity in a dose-dependent manner. The inhibition induced by DIMP was stronger than that by DEMP. The effect of DIMP and DEMP on the splenic NK activity of mice was stronger than on the splenic CTL activity, and the human lymphocytes is more sensitive to DIMP and DEMP than the splenocytes of mice.

Animals↗

PubMed2000

In vivo gene gun-mediated DNA delivery into rodent brain tissue.

Various types of gene transfer into live tissues have been tried. However, in vivo gene transfer into brain tissue or neuronal cells without virus vector has required a great effort. Particle-mediated gene transfer into live brain tissue was thought to be impossible because of its fragility and the mechanical problem of a previous type of gene gun. In addition, particle-mediated DNA transfer into monolayer-cultured cells without mechanical damage has been difficult. We successfully transferred DNA into rodent live brain tissue and also into monolayer-cultured cells without mechanical damage by using a new type of gene gun and also confirmed gene expression in the brain. This new method represents another variation of gene transfer into the brain.

Animals↗

PubMed2000

A critical role for the proteasome activator PA28 in the Hsp90-dependent protein refolding.

The 90-kDa heat shock protein, Hsp90, was previously shown to capture firefly luciferase during thermal inactivation and prevent it from undergoing an irreversible off-pathway aggregation, thereby maintaining it in a folding-competent state. While Hsp90 by itself was not sufficient to refold the denatured luciferase, addition of rabbit reticulocyte lysate remarkably restored the luciferase activity. Here we demonstrate that Hsc70, Hsp40, and the 20 S proteasome activator PA28 are the effective components in reticulocyte lysate. Purified Hsc70, Hsp40, and PA28 were necessary and sufficient to fully reconstitute Hsp90-initiated refolding. Kinetics of substrate binding support the idea that PA28 acts as the molecular link between the Hsp90-dependent capture of unfolded proteins and the Hsc70- and ATP-dependent refolding process.

Amino Acid Sequence↗

PubMed2000

Localization of calcitonin receptor mRNA in the mouse brain: coexistence with serotonin transporter mRNA.

To elucidate the sites of and mechanisms of analgesic effect of centrally injected calcitonin, we examined expression of calcitonin receptor mRNA in the mouse brain by in situ hybridization techniques. Calcitonin receptor mRNA was expressed in various brain regions, including the preoptic area, dorsomedial hypothalamic nucleus, lateral hypothalamic area, periaqueductal gray, dorsal raphe nucleus, locus coeruleus, lateral parabrachial nucleus, gigantocellular reticular nucleus alpha part, lateral paragigantocellular nucleus, raphe magnus nucleus and solitary tract nucleus, which are known to play important roles in pain modulation. In addition, a double in situ hybridization technique demonstrated the intense expression of calcitonin receptor mRNA on serotonergic neurons in some raphe nuclei and the lateral paragigantocellular nucleus, suggesting the involvement of central serotonergic pathways in analgesic effect of calcitonin.

Animals↗

PubMed2000

Possible involvement of the locus coeruleus in inhibition by prostanoid EP(3) receptor-selective agonists of morphine withdrawal syndrome in rats.

We examined the mechanism of the inhibitory effect of prostanoid EP(3) receptor agonists on naloxone-precipitated withdrawal syndrome in morphine-dependent rats. Rats were rendered morphine dependent by subcutaneous (s.c.) implantation of two pellets containing 75 mg morphine for 5 days. Morphine withdrawal syndrome was precipitated by i.p. injection of naloxone (3 mg/kg). Intracerebroventricular (i.c.v.) administration of (+/-)-15alpha-hydroxy-9-oxo-16-phenoxy-17,18, 19,20-tetranorprost-13-trans-enoic acid (M&B28,767: prostanoid EP(3) receptor agonist) or sulprostone (prostanoid EP(1)/EP(3) receptor agonist) significantly suppressed many withdrawal signs. Northern blotting and in situ hybridization studies revealed that i.c.v. administration of M&B28,767 (1 pg/rat) attenuated the elevation of c-fos mRNA during naloxone-precipitated withdrawal in many brain regions, including the cerebral cortex, thalamus, hypothalamus and locus coeruleus. Double in situ hybridization analysis revealed that in the locus coeruleus most of the tyrosine hydroxylase mRNA-positive neurons expressed mu-opioid receptor mRNA and more than half of these neurons were positive for prostanoid EP(3) receptor mRNA. These results indicate that the suppression by prostanoid EP(3) receptor agonists of naloxone-precipitated morphine withdrawal syndrome can be attributed to the inhibition of neuronal activity in several brain regions, including the locus coeruleus, the largest source of central noradrenergic neurons.

Alprostadil↗

PubMed2000

Biosynthesis and post-translational processing of lectin-like oxidized low density lipoprotein receptor-1 (LOX-1). N-linked glycosylation affects cell-surface expression and ligand binding.

LOX-1 (lectin-like oxidized low density lipoprotein receptor-1) is a type II membrane protein belonging to the C-type lectin family that can act as a cell-surface receptor for atherogenic oxidized low density lipoprotein (Ox-LDL) and may play crucial roles in atherogenesis. In this study, we show, by pulse-chase labeling and glycosidase digestion, that LOX-1 is synthesized as a 40-kDa precursor protein with N-linked high mannose carbohydrate chains (pre-LOX-1), which is subsequently further glycosylated and processed into the 48-kDa mature form within 40 min. Furthermore, when treated with an N-glycosylation inhibitor, tunicamycin, both tumor necrosis factor-alpha-activated bovine aortic endothelial cells and CHO-K1 cells stably expressing bovine LOX-1 (BLOX-1-CHO) exclusively produced a 32-kDa deglycosylated form of LOX-1. Cell enzyme-linked immunosorbent assay, flow cytometry, and immunofluorescence confocal microscopy demonstrated that the deglycosylated form of LOX-1 is not efficiently transported to the cell surface, but is retained in the endoplasmic reticulum or Golgi apparatus in tumor necrosis factor-alpha-activated bovine aortic endothelial cells, but not in BLOX-1-CHO cells. Radiolabeled Ox-LDL binding studies revealed that the deglycosylated form of LOX-1 expressed on the cell surface of BLOX-1-CHO cells has a reduced affinity for Ox-LDL binding. Taken together, N-linked glycosylation appears to play key roles in the cell-surface expression and ligand binding of LOX-1.

Amidohydrolases↗

PubMed2000

Bcl-w expression is increased in brain regions affected by focal cerebral ischemia in the rat.

Proteins of the bcl-2 family are important regulators of apoptosis in many tissues of the embryo and adult and may play a role in cell death following stroke. The recently isolated bcl-w gene encodes a pro-survival member of the bcl-2 family, which is widely expressed. However, it is not known whether bcl-w plays a role in determining cell survival after cerebral ischemia. Using Western blot analysis and immunocytochemistry, regional bcl-w protein expression was studied in rat brain 2, 6, 24 and 72 h following 20 min temporary middle cerebral artery occlusion (MCAO). Focal cerebral ischemia increased bcl-w protein expression within the caudate putamen and parietal cortex, as well as causing milder increases within frontal cortex. Immunocytochemically bcl-w was expressed within neurons (frontal and parietal cortex) and glia (caudate putamen) 24 h after MCAO. These data suggest that bcl-w could play a role in determining cell survival after cerebral ischemia.

Animals↗

PubMed2000

S phase-specific DNA-binding proteins interacting with the Hex and Oct motifs in type I element of the wheat histone H3 promoter.

The type I element (CCACGTCANCGATCCGCG), consisting of the Hex motif (CCACGTCA) and the reverse-oriented Oct motif (GATCCGCG), is necessary and sufficient to confer the S phase-specific transcription of the wheat histone H3 (TH012) gene. The transcriptional regulation via the type I element is thought to occur through interactions between transcription factors which bind specifically to the Hex and Oct motifs. Here we report S phase-specific DNA-binding proteins interacting with the type I element in partially synchronized wheat cultured cells. Hex motif-binding proteins found here resembled HBP-1a, as reported previously in terms of DNA-binding specificity. DNA-binding activities of the HBP-1a-like proteins were modulated by phosphorylation/dephosphorylation. In the electrophoretic mobility shift assay of the wheat nuclear extract, we also found three Oct motif-specific binding proteins, named OBRF (octamer-binding regulatory factor)-1, -2 and -3. One of the HBP-1a-like proteins and OBRF-1 appeared predominantly at the S phase. Thus, it was supposed that these two factors play a crucial role in the S phase-specific regulation of wheat histone gene expression.

Binding Sites↗

PubMed2000

Ipsilateral recurrence frequency after video-assisted thoracoscopic surgery for primary spontaneous pneumothorax.

OBJECTIVE: We retrospectively evaluated the results of video-assisted thoracoscopic surgery for primary spontaneous pneumothorax and recurrence. METHODS: A series of 424 patients with primary spontaneous pneumothorax were treated by video-assisted thoracoscopic surgery-289 with an ipsilateral recurrent episode, 88 with persistent air leakage for 7 days or longer, 34 with a contralateral episode, 9 with hemopneumothorax, and 4 with tension pneumothorax. The commonest management was stapling of an identified bleb, undertaken in 375 patients (88.4%). Pleural abrasion was conducted in 250 (59.0%), but the abraded area was one-third or less of the thoracic cavity in 187 (74.8%). RESULTS: No operative deaths occurred. Revisional thoracotomy was required in 1 patient with postoperative bleeding and another with incomplete postoperative lung reexpansion; 26 had prolonged air leakage, but none required revisional thoracotomy. During a mean follow-up of 31.4 months, ipsilateral pneumothorax recurred in 40 patients (9.4%), with 26 (65.0%) having recurrence within 1 year postoperatively. A video-assisted thoracoscopic surgery was conducted again in 8, and thoracotomy in 14. CONCLUSIONS: The ipsilateral recurrence of primary spontaneous pneumothorax after video-assisted thoracoscopic surgery was high at 9.4%. If video-assisted thoracoscopic surgery is to be considered as a treatment for spontaneous pneumothorax, we must therefore reduce postoperative ipsilateral recurrence by training practitioners not to overlook blebs during the procedure and/or consider widening the area of pleurodesis.

Adolescent↗

PubMed2000

Impaired expression of MHC class I molecules on mouse testicular germ cells is mainly caused by the post-transcriptional mechanism.

In this study, we examined expression of the major histocompatibility complex (MHC) class I molecules and of the mRNAs for MHC class I-mediated antigen presentation machinery molecules in highly purified C57BL/6 mouse testicular germ cells. Although H2 class I molecules were not detected on the cell surface, small amounts of the molecules were detected inside the cells by flow cytometric and immunoprecipitation analyses. Interferon (IFN)gamma treatment did not affect expression of the molecules on the surface by flow cytometric analysis. In addition, expression of mRNAs for MHC class I-mediated antigen presentation machinery molecules in the germ cells was analyzed by reverse transcription-polymerase chain reaction analysis. The faint constitutive expression of mRNAs for H2-K, beta2-microglobulin (beta2m), tapasin, and calnexin was observed in the cells. IFNgamma treatment up-regulated expression of mRNAs for H2-K, beta2m, TAP1 (a peptide transporter), and LMP2 (a proteosomal subunit). These findings indicate that impaired expression of MHC class I molecules on the cell surface of mouse testicular germ cells is mainly caused by the post-transcriptional regulatory mechanism.

Animals↗

PubMed2000

Identification of 187 single nucleotide polymorphisms (SNPs) among 41 candidate genes for ischemic heart disease in the Japanese population.

To investigate whether common variants in the human genetic background are associated with pathogenesis of ischemic heart diseases, we systematically surveyed 41 possible candidate genes for single-nucleotide polymorphisms (SNPs) by directly sequencing 96 independent alleles at each locus, derived from 48 unrelated Japanese patients with myocardial infarction, including 25.8 kb 5' flanking regions, 56.8 kb exonic and 35.4 kb intronic sequences, and 1.8 kb 3' flanking regions. In this genomic DNA of nearly 120 kb, we identified 187 SNPs: 55 in 5' flanking regions, seven in 5' untranslated regions (UTRs), 52 in coding elements, 64 in introns, eight in 3' UTRs, and one in a 3' flanking region. Among the 52 coding SNPs, 26 were non-synonymous changes. Allelic frequencies of some of the polymorphisms were significantly different from those reported in European populations. For example, the Q506R substitution in the coagulation factor V gene, the so-called "Leiden mutation", has a reported frequency of 2.3% in Europeans, but we detected the Leiden mutation in none of the Japanese genomes that we investigated. The allelic frequencies of the -33A>G SNP in the thrombomodulin gene were also very different; this allele occurred at a 12% frequency in the Japanese patients that we examined, although it had been detected in none of 82 Caucasians reported previously. These data support the hypothesis that some SNPs are specific to particular ethnic groups.

3' Untranslated Regions↗