Biomedical subjects

S Miyazaki

Publications and source records attributed to S Miyazaki.

At least 19 recordsLinked to original sources

PubMed1999

Influence of warfarin therapy on left atrial spontaneous echo contrast in nonvalvular atrial fibrillation.

To examine whether warfarin therapy had any influence on left atrial spontaneous echo contrast, we performed serial transesophageal echocardiography with integrated backscatter analysis in 12 patients with non-valvular atrial fibrillation. We found that the integrated backscatter intensity of the left atrial cavity did not change after 1 to 2 months of warfarin therapy, and concluded that this therapy does not influence spontaneous echo contrast.

Aged↗

PubMed1999

Clonal expansion of alphabeta-T lymphocytes with inverted Jbeta1 bias in familial hemophagocytic lymphohistiocytosis.

Familial hemophagocytic lymphohistiocytosis (FHL) is a rare but fatal disease in infancy. There are no previous reports on the clonality of T cells in FHL patients. We analyzed here the clonality of alphabeta-T cells in 5 FHL patients using an inverse reverse transcriptase-polymerase chain reaction (RT-PCR) of the T-cell receptor variable region gene (TCR V), a joining region gene of the beta chain (Jbeta)-PCR, a single-strand conformation polymorphism (SSCP), and sequence analysis. A high frequency (15%) of Vbeta and Valpha families was observed in 3 of 5 and 4 of 4 patients examined, respectively. In 19 Vbeta repertoires, including all highly frequent Vbeta, the Jbeta-PCR analysis showed restricted usage of the Jbeta family, indicating a marked bias to Jbeta1 subsets (the mean rate of Jbeta1:Jbeta2 was 87:13 in 65% of the alphabeta-T cells) in widespread alphabeta-T cells (in all patients but 1). In all patients, the clonality of specific Vbeta-Jbeta fragment expanded was confirmed by SSCP and sequence analysis. These results suggest that the existence of clonal expansion and restricted Jbeta1 usage of T cells in FHL is genetically associated with the pathogenesis and the immunodysfunction of the disease. These results help to explain some of the abnormal functional behaviors of T cells in FHL and raise new questions regarding the mechanisms responsible for the restricted clonal diversity.

Amino Acid Sequence↗

PubMed1999

In situ-gelling gellan formulations as vehicles for oral drug delivery.

Gels formed in situ following oral administration of 1% (w/v) aqueous solutions of gellan to rats and rabbits were evaluated as sustained-release vehicles. The formulation contained calcium ions in complexed form, the release of which in the acidic environment of the stomach caused gelation of the gellan gum. The in vitro release of theophylline from the rigid gellan gels followed root-time kinetics over a period of 6 h. Plasma levels of theophylline after oral administration of gellan solutions and a commercial oral sustained-release liquid dosage form containing an identical drug concentration were compared in both rats and rabbits. Bioavailability of theophylline from gellan gels formed by in situ gelation in the animal stomach was increased by four-fivefold in rats and threefold in rabbits compared with that from the commercial oral formulation. There was no significant difference in the mean residence times of theophylline when administered by these two vehicles.

Administration, Oral↗

PubMed1999

Characterization of the Drosophila ortholog of mouse eIF-3p48/INT-6.

The mouse mammary tumor virus (MMTV) has been shown to integrate frequently into INT-6 in MMTV-induced mouse mammary tumors. The INT6 gene has been highly conserved through evolution and has recently been shown to encode the p48 component of the eucaryotic translation initiation factor 3 (eIF-3) complex. We report here the isolation of the Drosophila eIF-3p48/INT-6. The gene comprises three exons within 1.8kb of genomic DNA located at cytogenetic position 73C2 in the Drosophila genome. The 1.5kb eIF-3p48/INT-6 RNA species encodes a protein composed of 364 amino-acid residues whose sequence is 71% similar to that of the mouse/human eIF-3/INT-6 amino-acid sequence. eIF-3p48/INT-6 RNA is expressed throughout development in Drosophila and the encoded protein is associated with the microsomal subcellular fraction.

Amino Acid Sequence↗

PubMed1999

Spatiotemporal dynamics of the [Ca2+]i rise induced by microinjection of sperm extract into mouse eggs: preferential induction of a Ca2+ wave from the cortex mediated by the inositol 1,4,5-trisphosphate receptor.

Hamster sperm extract (SE) possessing Ca2+ oscillation-inducing activity was microinjected into the peripheral or central region of mouse eggs, and the first increase in intracellular Ca2+ concentration ([Ca2+]i), together with the spread of fluorescence-labeled SE in the ooplasm, was investigated by imaging with confocal microscopy. Injection into the periphery always induced a Ca2+ wave that started from the injection site after a delay of 5 to 30 s depending on the concentration of SE. The diluted SE caused a wave of two-step [Ca2+]i rises, which was always observed at fertilization. Injection into the center could induce a radial Ca2+ wave with relatively high dose of SE, but lower dose of SE caused a [Ca2+]i rise after a longer delay which was initiated synchronously over the ooplasm or was preceded in a peripheral area. Injection of diluted SE remarkably prolonged the delay time and reduced the rate of [Ca2+]i rise. The critical concentration of SE needed to induce [Ca2+]i rise was significantly lower in the periphery. These results indicate that the sensitivity to SE is higher in the cortex. SE-induced [Ca2+]i rises were blocked by an antibody against the type 1 inositol 1,4,5-trisphosphate receptor (InsP3R). The cortex was substantially more sensitive to injected InsP3 induction of Ca2+ release than the center. It is suggested that the cortex of mouse eggs may involve a functionally specialized organization of InsP3Rs and Ca2+ pools in which a cytosolic sperm factor(s) could act upon sperm-egg fusion to cause Ca2+ release, leading to the Ca2+ wave at fertilization.

Animals↗

PubMed1999

Effects of aspirin and trapidil on cardiovascular events after acute myocardial infarction. Japanese Antiplatelets Myocardial Infarction Study (JAMIS) Investigators.

Aspirin therapy confers conclusive net benefits in the acute phase of evolving myocardial infarction, but no clear evidence of benefit from the long-term use of aspirin after acute myocardial infarction (AMI) has been shown in any single study. This multicenter study, the Japanese Antiplatelets Myocardial Infarction Study, was performed to find out whether aspirin or trapidil would improve clinical outcome compared with no antiplatelets in postinfarction patients. The study was a multicenter, open-label, randomized controlled trial of aspirin 81 mg/day, trapidil 300 mg/day, and no antiplatelets in patients with AMI admitted within 1 month from the onset of symptoms. Seven hundred twenty-three patients were enrolled at 70 hospitals in 18 prefectures of Japan; 250 were randomly assigned to treatment with 81 mg aspirin (aspirin group), 243 to that with trapidil (trapidil group), and 230 were not given antiplatelet agents. The mean follow-up period was 475 days. This study demonstrated that long-term use of aspirin at the dose of 81 mg/day reduced the incidence of recurrent AMI compared with the group receiving no antiplatelets after AMI (p = 0.0045) and that trapidil also reduced the occurrence of reinfarction compared with the group receiving no antiplatelets, but the difference was not significant (p = 0.0810). The incidence of cardiovascular events including cardiovascular death, reinfarction, uncontrolled unstable angina requiring admission to hospital, and nonfatal ischemic stroke was reduced in the group receiving 300 mg trapidil daily compared with the group receiving no antiplatelets (p = 0.0039). The use of aspirin 81 mg/day provided almost no benefit over no antiplatelets therapy in the incidence of cardiovascular events. In conclusion, low-dose aspirin (81 mg) effectively prevented recurrent AMI in postinfarction patients after thrombolysis or coronary angioplasty when used over a long term. Furthermore, the long-term use of trapidil resulted in a significant reduction in the incidence of cardiovascular events.

Aged↗

PubMed1999

Thermally reversible xyloglucan gels as vehicles for oral drug delivery.

The potential, as sustained release vehicles, of gels formed in situ following the oral administration of dilute aqueous solutions of a xyloglucan polysaccharide derived from tamarind seed has been assessed by in vitro and in vivo studies. Aqueous solutions of xyloglucan that had been partially degraded by beta-galactosidase to eliminate 44% of galactose residues formed rigid gels at concentrations of 1.0 and 1.5% w/w at 37 degrees C. The in vitro release of indomethacin and diltiazem from the enzyme-degraded xyloglucan gels followed root-time kinetics over a period of 5 h at 37 degrees C at pH 6.8. Plasma concentrations of indomethacin and diltiazem, after oral administration to rats of chilled 1% w/w aqueous solutions of the enzyme-degraded xyloglucan containing dissolved drug, and a suspension of indomethacin of the same concentration were compared. Constant indomethacin plasma concentrations were noted from both formulations after 2 h and were maintained over a period of at least 7 h. Bioavailability of indomethacin from xyloglucan gels formed in situ was increased approximately threefold compared with that from the suspension. The results of this study suggest the potential of the enzyme-degraded xyloglucan gels as vehicles for oral delivery of drugs.

Administration, Oral↗

PubMed1999

Spatiotemporal characterization of intracellular Ca2+ rise during the acrosome reaction of mammalian spermatozoa induced by zona pellucida.

The mammalian sperm acrosome reaction (AR) is an essential event prior to sperm-egg fusion at fertilization, and it is primarily dependent on an increase in intracellular Ca2+ concentration ([Ca2+]i). Spatiotemporal aspects of the [Ca2+]i increase during the AR induced by solubilized zona pellucida (ZP) in hamster spermatozoa were precisely investigated with a Ca2+ imaging technique using confocal laser scanning microscopy with two fluorescent Ca2+ indicators. A rapid rise in [Ca2+]i occurred immediately after the application of ZP solution through a micropipette. The rise was always initiated in the sperm head, even when the application was directed toward the tail. The elevated [Ca2+]i was little attenuated during measurement for 30-40 s. Acrosomal exocytosis was detected as a sudden decrease of fluorescence in the acrosomal vesicle approximately 20 s after the onset of the [Ca2+]i rise. High-resolution imaging revealed that the [Ca2+]i rise in the sperm head began at the region around the equatorial segment and spread over the posterior region of the head within 0.6 s, whereas Ca2+ concentration in the acrosomal vesicle appeared to be unaltered. The [Ca2+]i rise was completely abolished under Ca2+-free extracellular conditions, indicating that it is totally attributable to Ca2+ influx. Nifedipine, an inhibitor of L-type Ca2+ channels, did not affect the rising phase of the ZP-induced Ca2+ response, but accelerated the decline of the [Ca2+]i rise and inhibited acrosomal exocytosis. The present study provides implicative information about the spatial organization of functional molecules involved in the signal transduction in mammalian AR.

Acrosome↗

PubMed1999

A novel role of IL-15 in the development of osteoclasts: inability to replace its activity with IL-2.

IL-15 shares many activities with IL-2 on stimulating lymphocytes, hematopoietic progenitor cells, and macrophages. However, the role of IL-15 in osteoclastogenesis has not been elucidated. The recent finding of abundant IL-15 in rheumatoid arthritis synovial fluids suggested a possible role for this cytokine in the pathological destruction of bone and prompted us to determine whether IL-15 stimulates osteoclast formation. IL-15 stimulated the formation of multinucleated osteoclast-like cells in rat bone marrow cultures. In stroma-free cultures, IL-15 increased the number of mononuclear preosteoclast-like cells in the early stage of osteoclast formation. The stimulation was observed even after treatment with IL-15 for only 24 or 48 h of culture. Moreover, low IL-15 concentration (0.1 ng/ml) strongly increased the level of calcitonin receptor mRNA of mononuclear preosteoclast-like cells. Although IL-15 is known as a potent stimulator of TNF-alpha, its activity was not abolished by addition of anti-TNF-alpha Ab. Interestingly, IL-2 and IL-7, which utilize some IL-15R components, had no effect on osteoclast differentiation, but pretreatment with IL-2 or IL-7 of bone marrow cells before the addition of IL-15 inhibited the enhancing activity of IL-15. In summary, IL-15 has a novel activity to stimulate the differentiation of osteoclast progenitors into preosteoclasts, which cannot be replaced by IL-2 but may use components in common with IL-2R to mediate its effects.

Animals↗

PubMed1999

DNA Data Bank of Japan dealing with large-scale data submission.

The DNA Data Bank of Japan (DDBJ) (http//:www.ddbj.nig.ac.jp) has developed a software system for mass submissions to cope with a recent expansion of EST and genome data submissions. The system is composed of four parts, the WWW data submission, large-scale submission, submission management and storing. Using this system one can submit data on a large number of sequences or a very long sequence while checking the consistency between the annotation and sequence without much effort. DDBJ has received large scale data of Homo sapiens, Arabidopsis and Pyrococcus from Japanese researchers who made full use of the new submission system.

Animals↗

PubMed1999

Clonal dissemination of T-lymphocytes in scid mice from familial hemophagocytic lymphohistiocytosis.

BACKGROUND: Although familial hemophagocytic lymphohistiocytosis (FHL) has been considered a disorder of T-cell dysfunction, there is no evidence of the clonal origin of T-cells in this disease. PROCEDURE: We engrafted mononuclear cells (MNCs) from five FHL patients into scid mice and examined the infiltration of human cells in mouse organs. The characterization of human cells that infiltrated in the mouse organs was then performed. RESULTS: A diffuse infiltration of human lymphoid cells was detected in scid mice treated with 1 x 10(6) MNCs from one of the five patients. These cells were positive for HLA-DR and CD3, but negative for CD4, CD8, CD20, and CD68, suggesting the infiltration of double negative (DN) T-cells. The MNCs from the other four patients induced murine lymphoma-like disease; T-cell lymphoma in one and lymphoma of unknown origin in three. The characterization of these human DN T-cells was performed. The analysis of the Vbeta repertoire showed no preferential usage of the Vbeta family in MNCs, while the dominant expression of Vbeta13 was detected in T-cells infiltrating in the spleen and lung. A Jbeta analysis showed the restricted usage of Jbeta1.2 for Vbeta13 in these cells, and the clonality of Vbeta13-Jbeta1.2 fragment was confirmed by a single-strand confirmation polymorphism analysis. The analysis of the Valpha repertoire showed that Valpha24 was exclusively used in these DN T-cells, but no usage of JalphaQ for Valpha24 was observed. CONCLUSIONS: A clonal expansion of T-cells was induced in scid mice by the engraftment of MNCs from an FHL patient. The infiltration of DN alphabeta T-cells bearing invariant Valpha24 T-cell receptor in mouse organs may provide a useful clue to the pathogenesis of FHL. In the patients whose MNCs induced murine lymphoma-like disease, some cytokines or unknown factors that stimulate the growth and the tumorigenicity of murine lymphocytes might be produced by the MNCs engrafted in scid mice. Further study is needed to confirm the validity of our experimental approach and the findings observed in scid mice by using more FHL samples.

Animals↗

PubMed1999

Paradoxical synergistic effects of tumour necrosis factor and interleukin 1 in murine gut-derived sepsis with Pseudomonas aeruginosa.

The authors evaluated the synergistic effect of tumour necrosis factor (TNF) and interleukin 1 (IL-1) in gut-derived sepsis in mice. After colonization of Pseudomonas aeruginosa strain D4 in the gastrointestinal tract, cyclophosphamide was administered to induce bacterial translocation of the P. aeruginosa and thereby to cause gut-derived sepsis. In this model, treatment either with 8 microg/kg of recombinant human TNF-alpha (rhTNF-alpha) or 2 microg/kg of recombinant human interleukin 1alpha (rhIL-1alpha) solely did not affect the mortality, whereas combined administration of the same doses of rhTNF-alpha and rhIL-1alpha significantly increased the mortality rate in comparison with saline-treated mice. Bacterial counts in liver and blood were significantly higher in rhTNF-alpha and rhIL-1alpha treated mice than in saline-treated mice. Endogenous TNF-alpha and IL-1beta productions were stimulated after combined treatment with rhTNF-alpha and rhIL-1alpha. On the contrary to these adverse effects, combined treatment with 500 microg/kg of rhTNF-alpha and 50 microg/kg of rhIL-1alpha on the day before the administration of cyclophosphamide significantly reduced the mortality from septic infection. We conclude that TNF and IL-1 synergistically affect the mortality of mice after gut-derived sepsis due to P. aeruginosa in mice and the timing of treatment with these cytokines causes both extremes in their effects.

Animals↗

PubMed1999

Biological functions of recombinant bovine interleukin 6 expressed in a baculovirus system.

The cDNA encoding bovine interleukin 6 (IL-6) was obtained from messenger RNA extracted from lipopolysaccharide-stimulated bovine Kupffer cells by the reverse transcription polymerase chain reaction (RT/PCR), and cloned into the baculovirus vector pVL 1392. Insect cells (Sf21AE derived from Spodoptera frugiperda) infected with the recombinant baculovirus secreted a large amount of 23.7 kD protein into the culture medium. This protein was capable of causing increased haptoglobin production and decreased albumin production in primary cultured bovine hepatocytes. The swine and human IL-6s were also able to decrease albumin production in bovine hepatocytes. This recombinant IL-6 did not stimulate the proliferation of 7TD1 cells (a murine IL-6-dependent cell line), whereas the recombinant swine IL-6 which was expressed in the same baculovirus system, and recombinant human IL-6 derived from Escherichia coli were each capable of stimulating proliferation of 7TD1 cells, respectively. This suggests a species restriction between bovine IL-6 and murine IL-6 dependent cell lines.

Acute-Phase Proteins↗

PubMed1999

Tissue- and environmental response-specific expression of 10 PP2C transcripts in Mesembryanthemum crystallinum.

Ten transcripts (Mpc1-10) homologous to protein phosphatases of the 2C family have been isolated from the halophyte Mesembryanthemum crystallinum (common ice plant). Transcripts range in size from 1.6 to 2.6 kb, and encode proteins whose catalytic domains are between 24% and 62% identical to that of the Arabidopsis PP2C, ABI1. Transcript expression is tissue specific. Two isoforms are present only in roots (Mpc1 and Mpc5), three in young leaves (Mpc6, 8 and 9), two in old leaves (Mpc6 and Mpc8), and two in post-flowering leaves (Mpc8 and Mpc9). Mpc2 is strongly expressed in roots and also in seeds, meristematic tissues and mature flowers. Mpc3 is specific for leaf meristems, and Mpc4 is found in root and leaf meristems. Mpc7 is restricted to meristematic tissues. Mpc10 is only present in mature flowers. Mpc2 (in roots and leaves), Mpc5 (in roots) and Mpc8 (weakly in leaves) are induced by salinity stress and drought conditions with different kinetics in different tissues, but other Mpcs are downregulated by stress. Cold stress (4 degrees C) leads to a decline in Mpc5 and Mp6, but low temperature provoked a long-term (days) increase in Mpc2 levels in leaves and a transient increase (less than 24 h) in roots. Four full-length transcripts have been obtained. In each case, after over-expression in E. coli, the isolated proteins exhibited (Mg2+-dependent, okadeic acid-insensitive) protein phosphatase activity, although activity against 32P-phosphocasein varied among different PP2Cs. Determination of tissue developmental and stress response specificity of PP2C will facilitate functional studies of signal-transducing enzymes in this halophytic organism.

Base Sequence↗

PubMed1999

Effects of nucleotides on learning and memory in a Morris water maze test in normal and basal forebrain-lesioned rats.

The effects of nucleotides on learning and memory were studied in normal and basal forebrain-lesioned rats using a Morris water maze test. Chronic oral administration of a nucleotide mixture (500 mg/kg), containing an equal weight of the disodium salts of adenosine 5'-monophosphate, guanosine 5'-monophosphate, inosine 5'-monophosphate, cytidine 5'-monophosphate, and uridine 5'-monophosphate facilitated learning acquisition in normal rats. In basal forebrain-lesioned rats, administration of the nucleotide mixture showed a tendency to improve learning acquisition and memory retrieval. In the biochemical studies, no significant changes were observed in brain choline and acetylcholine levels by treatment with the nucleotide mixture at the doses tested in both normal and basal forebrain-lesioned rats. The nucleotides did not affect the monoaminergic systems in normal rats, but did cause some changes in these systems in basal forebrain-lesioned rats. The present studies indicate that nucleotides ameliorate learning and memory processes in normal rats, but not in basal forebrain-lesioned rats, and they also modulate the activity of the central monoaminergic systems under certain conditions.

Acetylcholine↗

PubMed1999

Cerebrospinal fluid cytokine levels and dexamethasone therapy in bacterial meningitis.

OBJECTIVES: cerebrospinal fluid (CSF) levels of interleukin (IL)-1 beta and tumor necrosis factor (TNF) alpha were measured to assess the effect and application of dexamethasone (Dex) therapy for bacterial meningitis. METHODS: associations between clinical findings and CSF parameters were first investigated, and prognosis was compared between 25 patients with Dex and 12 without Dex therapy. RESULTS: patients with the presence of disturbed consciousness showed higher CSF levels of TNF alpha (mean: 3015 pg/ml) or protein (mean: 215 mg/dl) than those without it (both, P < 0.O5). Simultaneous increase of TNF alpha (> 1000 pg/ml) and protein (> 100 g/dl) was observed in 80%, of patients with profoundly disturbed consciousness. Patients with Dex therapy presented higher TNF alpha/protein levels at diagnosis than those without Dex therapy (P < 0.05). Despite worse conditions at diagnosis, only one of 14 Dex-treated patients whose initial CSF TNF alpha levels exceeded 1000 pg/ml developed deafness. On the other hand, two of four patients without Dex therapy who had the same TNF alpha level suffered from psychomotor retardation. The differences in the frequency of sequelae between those with and without Dex therapy were significant in patients showing high TNF alpha level (P < O.05), but not in those showing high CSF levels of IL-1 beta or protein. The logistic regression analysis indicated that high CSF protein level (P < O.0001), or no Dex therapy (P=0.0001) was the independent risk factor for sequelae. CONCLUSIONS: although the study number was small, our observations suggested that CSF TNF alpha/protein levels reflected the neurologic severity, and implied that early Dex therapy might be beneficial for patients with prominently high TNF alpha levels.

Adolescent↗

PubMed1999

The laminin-derived peptide YIGSR (Tyr-Ile-Gly-Ser-Arg) inhibits human pre-B leukaemic cell growth and dissemination to organs in SCID mice.

The YIGSR (Tyr-Ile-Gly-Ser-Arg) laminin beta1 chain sequence has an inhibitory effect on tumour growth and the metastasis of melanoma and fibrosarcoma cells. In the present study, we investigated whether the multimeric YIGSR peptide (Ac-Y16) has an antiproliferative effect and/or prevents the metastasis of human pre-B acute lymphoblastic leukaemia cells (NALM6) in severe combined immune deficient (SCID) mice. In in vitro studies, Ac-Y16 significantly inhibited leukaemic cell colony formation and the invasion of NALM6 cells in a Matrigel-based assay. The tumour growth and leukaemic infiltration in peripheral tissues were also analysed in SCID mice 9 weeks after NALM6, Matrigel and Ac-Y16 were subcutaneously co-injected. The weight of the subcutaneous tumours was significantly suppressed by Ac-Y16 in a dose-dependent manner. Flow cytometry analysis showed that the leukaemic infiltration was significantly inhibited in all organs with 1.5-2.0 mg of Ac-Y16. Leukaemic infiltrations in the brain were inhibited with 0.5 mg of Ac-Y16, and those in brain and bone marrow were also inhibited with 1.0 mg of Ac-Y16. With Ac-S16, a control-scrambled peptide, the only significant inhibition of the leukaemic infiltration was observed in bone marrow at a much higher dose. These data suggest that the multimeric YIGSR peptide can inhibit the tumour growth and metastasis of leukaemic cells and may be useful as a potential therapeutic reagent for leukaemic infiltrations.

Actins↗

PubMed1999

Chronic radiodermatitis following repeated percutaneous transluminal coronary angioplasty.

We review three patients who developed chronic radiodermatitis subsequent to undergoing multiple percutaneous transluminal coronary angioplasties (PTCAs). All patients had had chronic ischaemic heart disease (IHD) and had undergone lengthy PTCA on several occasions. The skin eruption was characterized by an atrophic rectangular plaque on the left upper back, presenting as mottled hyper- and hypopigmentation with reticulate telangiectasia. Histologically, the eruption demonstrated epidermal atrophy, hyalinized and irregularly stained collagen, and telangiectasia of superficial vessels in the dermis. Although the risk of radiation injury in most patients undergoing cardiac catheterization is low, this danger should not be ignored. In particular, patients with long-standing IHD and numerous repeated catheterizations to only one or two occluded coronary arteries should be considered at high risk.

Angioplasty, Balloon, Coronary↗