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Biomedical subjects

M Yamazaki

Publications and source records attributed to M Yamazaki.

At least 451 records · Page 25Linked to original sources
PubMed1994

Determination of RAPD markers in rice and their conversion into sequence tagged sites (STSs) and STS-specific primers.

We produced 102 randomly amplified polymorphic DNA (RAPD) markers mapped on all 12 chromosomes of rice using DNAs of cultivars Nipponbare (japonica) and Kasalath (indica) and of F2 population generated by a single cross of these parents. Sixty random primers 10 nucleotides long were used both singly and in random pairs and about 1,400 primer-pairs were tested. Using both agarose gel and polyacrylamide gel electrophoresis enabled us to detect polymorphisms appearing in the range from < 100 bp to 2 kb. The loci of the RAPD markers were determined onto the framework of our RFLP linkage map and some of these markers were mapped to regions with few markers. Out of the 102 RAPD markers, 20 STSs (sequence-tagged sites) and STS-specific primer pairs were determined by cloning, identifying and sequencing of the mapped polymorphic fragments.

Base Composition↗
PubMed1994

Study of the balance between coagulation and fibrinolysis in disseminated intravascular coagulation using molecular markers.

Plasma levels of thrombin-antithrombin III complex (TAT), plasmin-alpha 2-plasmin inhibitor complex (PIC) and active plasminogen activator inhibitor (PAI) were assayed in 66 cases of disseminated intravascular coagulation (DIC). Significant elevation of both TAT and PIC was observed in all cases of DIC. Most elevated levels of TAT were seen in DIC with acute promyelocytic leukaemia (APL) and sepsis. The highest levels of PIC were seen in DIC with APL but were much lower in sepsis. A significant elevation in active PAI was observed in DIC due to acute leukaemia (apart from APL), chronic myeloid leukaemia and sepsis, but not in APL, non-Hodgkin lymphoma and cancer. Active PAI was higher in patients with multiple organ failure (MOF) than in those without MOF while PIC was lower in patients with this complication. Thus, the balance of coagulation and fibrinolysis varied according to the underlying cause of DIC; APL had more dominant activation of fibrinolysis, while sepsis had greater activation of coagulation. It is suggested that the inhibition of secondary fibrinolytic activation plays an important role in the progression of MOF by the disturbance of the microcirculation.

Antifibrinolytic Agents↗
PubMed1994

Characterization of immunological activity of a low toxicity antitumor lipopolysaccharide from Bordetella pertussis.

Immunological properties of a low toxicity lipopolysaccharide (BP-LPS) extracted from Bordetella pertussis (Tohama strain) which was reported to have high antitumor activity against murine tumors were examined and compared with those of LPS extracted from other enterobacteria. The activation or stimulation of murine macrophages and lymphocytes by these LPS, including TNF induction, was found to be similar. However, BP-LPS was clearly less active in its stimulation of murine and human neutrophils as estimated by neutrophil-adherence assay and by their TNF production than E. coli LPS. Furthermore, BP-LPS also suppressed the activation of human neutrophils by Escherichia coli LPS. A comparative study with 7 LPS preparations indicated that their toxicity in terms of animal body weight loss correlated with their ability to induce human neutrophil adherence. The inability of BP-LPS to activate neutrophils may thus have some bearing on its low toxicity.

Animals↗
PubMed1994

Mechanism of bacitracin resistance in gram-negative bacteria that synthesize exopolysaccharides.

Four representative species from three genera of gram-negative bacteria that secrete exopolysaccharides acquired resistance to the antibiotic bacitracin by stopping synthesis of the exopolysaccharide. Xanthomonas campestris, Sphingomonas strains S-88 and NW11, and Escherichia coli K-12 secrete xanthan gum, sphingans S-88 and NW11, and colanic acid, respectively. The gumD gene in X. campestris is required to attach glucose-P to C55-isoprenyl phosphate, the first step in the assembly of xanthan. A recombinant plasmid carrying the gumD gene of X. campestris restored polysaccharide synthesis to bacitracin-resistant exopolysaccharide-negative mutants of X. campestris and Sphingomonas strains. Similarly, a newly cloned gene (spsB) from strain S-88 restored xanthan synthesis to the same X. campestris mutants. However, the intergeneric complementation did not extend to mutants of E. coli that were both resistant to bacitracin and nonproducers of colanic acid. The genetic results also suggest mechanisms for assembling the sphingans which have commercial potential as gelling and viscosifying agents.

Bacitracin↗
PubMed1994

Shear-induced platelet aggregation in cerebral ischemia.

BACKGROUND AND PURPOSE: Recent evidence has suggested that shear-induced platelet aggregation is an important mechanism of thrombosis at arterial bifurcations or stenoses. We measured shear-induced platelet aggregation with a new apparatus in patients with cerebral ischemia and also studied correlations with other hemostatic parameters as well as the effect of antiplatelet agents. METHODS: The subjects were 75 patients with cerebral ischemia and 26 control subjects. Platelet aggregation was induced in citrated platelet-rich plasma by a high shear stress (108 dynes/cm2) that was applied by means of a cone-plate streaming chamber based on turbidimetry. We studied the correlation of test results with hemostatic parameters and also the effects of antiplatelet agents. RESULTS: Compared with the control subjects, an increase of shear-induced platelet aggregation was observed in 21 patients with atherothrombotic stroke and 12 with transient ischemic attacks, but not in 11 with cardioembolic stroke or 31 with lacunar stroke. There was no significant correlation of shear-induced platelet aggregation with platelet count, agonist-induced platelet aggregation, fibrinogen level, or beta-thromboglobulin level. The extent of shear-induced aggregation was not correlated with von Willebrand factor antigen levels but was significantly correlated with the amounts of larger von Willebrand factor multimers. Oral aspirin (81 mg/d) did not inhibit shear-induced platelet aggregation, whereas oral ticlopidine (200 mg/d) significantly inhibited it. CONCLUSIONS: These results indicate that shear-induced platelet aggregation is increased in patients with atherothrombotic stroke and transient ischemic attacks, is correlated with the increase of larger von Willebrand factor multimers, and is corrected by ticlopidine but not by low-dose aspirin.

Adult↗
PubMed1994

Biopolymers from marine invertebrates. XIV. Antifungal property of Dolabellanin A, a putative self-defense molecule of the sea hare, Dolabella auricularia.

Dolabellanin A (DAA), the antineoplastic and antibacterial glycoprotein purified from the albumen gland of Dolabella auricularia, showed an antifungal activity. DAA suppressed fungal growth completely at a concentration of over 2 micrograms/ml, and the colony forming ability of the fungus was significantly decreased after contact with DAA. These results indicate that DAA is an antifungal protein and its mode of antifungal activity is fungicidal.

Animals↗
PubMed1994

Genetic relationships among Glycyrrhiza plants determined by RAPD and RFLP analyses.

The genetic similarities of four species of Glycyrrhiza plants were determined by DNA analyses of random amplified polymorphic DNA (RAPD) and restriction fragment length polymorphism (RFLP). The phylogenic trees were constructed from the genetic similarities estimated from RAPD and RFLP profiles. These results indicated that G. glabra and G. uralensis, rich in glycyrrhizin, are more closely related to each other than to G. echinata or to G. pallidiflora.

DNA, Plant↗
PubMed1994

Promotion of neuronal differentiation of PC12h cells by natural lignans and iridoids.

We studied the effect of (+)- and (-)-syringaresinol, (+)-syringaresinol glucosides, syringin, aucubin and catalpol on neurite outgrowth of a cultured cell line of paraneuron, PC12h cells. Of these compounds, (+)-syringaresinol diglucoside and partly glucosidase-hydrolyzed aucubin were found to be the most potent in promotion of the neurite outgrowth and stimulated responses to a high concentration of KCl and to carbachol in the cells, as observed by increase of the concentration of cytosolic free calcium. It is suggested that some of these herb-derived compounds can induce neuronal differentiation in PC12h cells.

Animals↗
PubMed1994

Inhibition of the nerve growth factor-induced neurite outgrowth by specific tyrosine kinase and phospholipase inhibitors.

The effects of nerve growth factor (NGF) on PC12h cells have been studied with reference to the relationship between neurite outgrowth and the activities of the enzymes involved in signal transduction in the early stage of NGF action. Pretreatment of cells with selective inhibitors of tyrosine kinase (ST638 and genistein) and phospholipases C (neomycin B) and A2 (p-Bromophenacyl bromide; BPB and indomethacin) depress neurite outgrowth following 60 min treatment with NGF (0.1 microgram/ml). The inhibitor of intracellular calcium mobilization, TMB-8, also significantly depresses the NGF-induced neurite outgrowth. Arachidonic acid release, induced by NGF, from the cell lipids is reduced following previous inhibition of above mentioned enzymes. Based on these results, it is suggested that NGF requires tyrosine kinase in its early stage of action (within 60 min) in PC12h cells, phospholipases C and A2 to release Ca2+ from intracellular stores and arachidonate from cellular phospholipids, in order to induce neurite outgrowth.

Animals↗
PubMed1994

Preparation and antigenic properties of digitoxin-bovine serum albumin conjugates linked at the digitoxose C-3' and C-3" positions.

In order to obtain specific antisera to digitoxin, four new types of hapten-bovine serum albumin (BSA) conjugates were synthesized from digitoxin. The haptens were linked to the carrier protein through hemisuccinate and hemisuccinylglycine bridges at the C-3' and C-3" positions in the digitoxose chain. The antisera were prepared by immunizing rabbits with each digitoxin-BSA conjugate and the properties of the antisera were investigated by RIA with 3H-labeled digitoxin. Among these antisera, the antiserum raised against digitoxin 3'-hemisuccinate-BSA conjugate possessed high specificity for digitoxin, exhibiting only minor cross-reactions with digitoxigenin bisdigitoxoside (4.0%), dihydrodigitoxin (2.8%), digoxin (2.4%), digitoxigenin monodigitoxoside (0.23%) and digitoxigenin (< 0.05%).

Animals↗
PubMed1994

Transport mechanism of an H1-antagonist at the blood-brain barrier: transport mechanism of mepyramine using the carotid injection technique.

The blood-brain barrier (BBB) permeability of mepyramine was measured by the carotid injection technique to elucidate the transport mechanism of an H1-antagonist in the central nervous system. Mepyramine was found to enter the brain by saturable and carrier-mediated transport. The in vivo kinetic parameters were estimated as follows: the maximum uptake rate (Jmax) was 7.12 +/- 1.37 mumol/min/g of brain, the Michaelis constant (Kt) was 4.40 +/- 2.00 mM, and the nonsaturable first order rate (Kd) was 0.28 +/- 0.02 ml/min/g of brain. The mepyramine transport was not inhibited either by nutrients or by choline, hemicholinium-3, though it was inhibited by the classical H1-antagonists such as diphenhydramine, diphenylpyraline, and also by propranolol. The above inhibitory effects suggest that a transport system different from the amine transport system exists for the BBB transport of mepyramine, and that this transporter is common not only for H1-antagonists but also for basic drugs.

Animals↗
PubMed1994

Pharmacologically active components from a Peruvian medicinal plant, huira-huira (Culcitium canescens H. & B.).

The methanol extract of Huira-Huira (Culcitium canescens) showed analgesic effects in acetic acid-induced writhing and tail pressure tests, and it also produced potent prolongation of hypnosis induced by pentobarbital. The latter activity was used as an isolation-guide to determine the active components which were identified as dehydrocacalohastine, cacalohastine and cacalonol.

Analgesics↗
PubMed1994

Isolation and characterization of immunosuppressive components of three mushrooms, Pisolithus tinctorius, Microporus flabelliformis and Lenzites betulina.

Two components having an immunosuppressive activity were isolated together with non-active pisolactone from Pisolithus tinctorius, and they were deduced to the 24-methyllanosta-8,24(28)-diene-3 beta,22 zeta-diol and a mixture of two new compounds, (22S,24R)-24-methyllanosta-8-en-22,28-epoxy-3 beta,28 alpha-diol and (22S,24S)-24-methyllanosta-8-en-22,28-epoxy-3 beta,28 beta-diol, respectively. Among them, pisolactone and 24-methyllanosta-8,24(28)-diene-3 beta,22 zeta-diol have previously been isolated from the same mushroom. Ergosterol peroxide and 9(11)-dehydroergosterol peroxide were also isolated as active components from this mushroom in small amounts, and from Microporus flabelliformis and Lenzites betulina. The IC50 values of these components were evaluated against proliferation of mouse spleen lymphocytes stimulated with concanavalin A and lipopolysaccharide.

Animals↗
PubMed1994

A screening concept based on a hypothesis led to the development of a putative cognitive enhancer that stimulates penile erection.

Starting from the hypothesis that drugs which specifically activate the hippocampal cholinergic nerve activity may ameliorate memory impairments, we carried out a series of evaluations for a novel cognitive enhancer using enhancement of penile erection as a sign of cholinergic activation, and found FR64822. The compound facilitated penile erection in naive rats, and it ameliorated scopolamine-induced amnesia of rats in passive avoidance tasks with bell-shaped dose-response curves, while it dose-dependently reduced body weight gain in Zucker fatty rats. Pretreatment with sulpiride (32 mg/kg, p.o.) hardly affected the former two activities, but significantly reduced the anorectic activity in Zucker rats. Further evaluation of FR64822 derivatives characterized a second compound, FR121196, which induces penile erection and memory enhancement, but not body weight reduction. Memory enhancing and erection stimulating activities of FR121196 were abolished in rats treated with either cysteamine (200 mg/kg, s.c.), a somatostatin depletor, or lesioning of the serotonergic raphe nuclei. Thus, classic whole animal studies based on a hypothesis proved to be efficient for reaching our objective, the discovery of a new drug. They also gave us insight into the common somatostatinergic and serotonergic mechanisms underlying penile erection and memory improvement.

Animals↗
PubMed1994

The possible role of age-related increase in the plasma glucagon/insulin ratio in the enhanced hepatic gluconeogenesis and hyperglycemia in genetically diabetic (C57BL/KsJ-db/db) mice.

Genetically diabetic db/db mice and their normoglycemic littermates (+/+ mice) were studied to determine plasma levels of glucose, glucagon and insulin and hepatic gluconeogenic enzyme activities. Plasma glucose levels did not differ significantly between the 5-week-old db/db and +/+ mice, but increased with age in the former until the animals were 16-week-old. Similar age-associated changes were observed in the activities of the gluconeogenic enzymes, glucose-6-phosphatase (G-6-Pase) and fructose-1,6-diphosphatase (F-1,6-DPase). While the plasma levels of insulin and glucagon that peaked at 7 weeks of age did not parallel the hyperglycemia, the plasma glucagon/insulin (G/I) ratio roughly paralleled the hyperglycemia. Analysis of individual values for the db/db mice revealed statistically significant (P < 0.001) correlations between plasma glucose levels and hepatic G-6-Pase (r = 0.78) or F-1,6-DPase (r = 0.74) activity. There were also significant correlations between the G/I ratio and plasma glucose levels (P < 0.001, r = 0.66), hepatic G-6-Pase (P < 0.01, r = 0.48) or F-1,6-DPase (P < 0.01, r = 0.57) activity. It is thus concluded that the relative predominance of glucagon over insulin action plays an important role in the age-associated development of hyperglycemia in db/db mice. Glucagon presumably activates the hepatic gluconeogenic enzymes to enhance hepatic glucose output.

Age Factors↗
PubMed1994

Female siblings with Pendred's syndrome.

Female siblings with Pendred's syndrome were admitted to our clinic. The abnormality of the acoustic structure was examined by MRI. Bilateral enlargement of the vestibular aqueduct and a prominently marked endolymphatic sac were found on MRI. These findings seemed likely to represent a Mondini deformity. Acoustic structure in Pendred's syndrome was examined here by MRI for the first time. We examined their HLA-DR locus as a genetic marker using the affected sib-pair method preliminary. HLA typing might be a diagnostic criteria of Pendred's syndrome, although the present siblings possessed 2 HLA genes in common.

Adolescent↗
PubMed1994

Cavernous lymphangioma of the spleen in a patient with Klippel-Trenaunay-Weber syndrome.

A 31-year-old woman presented with hypertrophy of the left upper extremity and thrombocytopenia. Physical examination revealed splenomegaly, and laboratory investigation revealed thrombocytopenia, elevation of cross-linked fibrin degradation products (XDP), and thrombin-antithrombin III complex (TAT). A diagnosis of Klippel-Trenaunay-Weber (K-T-W) syndrome was established by the dermatologic findings and angiography of the extremities. A splenic cavernous lymphangioma was diagnosed by ultrasonography and angiography, and was confirmed by pathology following splenectomy. Post-operatively, the platelet count increased, and hemostatic parameters normalized. Cavernous lymphangioma is a rare complication of Klippel-Trenaunay-Weber syndrome. Splenectomy proved to be an effective therapy for both cavernous lymphangioma and consumptive coagulopathy in Klippel-Trenaunay-Weber syndrome.

Adult↗