Biomedical subjects

N Yoshida

Publications and source records attributed to N Yoshida.

At least 415 records · Page 23Linked to original sources

PubMed1991

Replacement of P1 Leu18 by Glu18 in the reactive site of turkey ovomucoid third domain converts it into a strong inhibitor of Glu-specific Streptomyces griseus proteinase (GluSGP).

Turkey ovomucoid third domain with P1 Leu18 at its reactive site is an excellent inhibitor of chymotrypsin and elastase and of many other serine proteinases with related specificities. Semisynthetic replacement of P1 Leu18 by Lys18 causes the expected change into a trypsin inhibitor. Strikingly, semisynthetic replacement P1 Leu18 to Glu18 changes turkey ovomucoid third domain into a powerful inhibitor of Glu-specific Streptomyces griseus proteinase, GluSGP. Of the 131 natural avian ovomucoid third domains we have sequenced none have P1 Glu18, but several avian ovomucoid first domains have P1 Glu24. They are weak to moderate inhibitors of GluSGP.

Amino Acid Sequence↗

PubMed1991

A new congenital abnormal fibrinogen Ise characterized by the replacement of B beta glycine-15 by cysteine.

A new case of heterozygous dysfibrinogenemia characterized by the replacement of NH2-terminal amino acid of fibrin beta-chain was found in a 50-year-old man. Despite a prolonged thrombin time, the propositus' fibrinogen had a normal reptilase time with the normal release of fibrinopeptide A. Release of fibrinopeptide B by thrombin was strongly affected, but a very high concentration of thrombin almost completely released fibrinopeptide B with a normal elution pattern on reversed-phase high performance liquid chromatography (HPLC). Lysylendopeptidase-cleavage of purified B beta-chains analyzed on HPLC showed the decrease of one peptide compared with the normal and the appearance of an abnormal peptide peak. These peptides were treated with thrombin and further separated on HPLC. Amino acid sequence analysis of the abnormal peptide demonstrated that B beta glycine-15, NH2-terminus of the fibrin beta-chain, was replaced by cysteine. These findings will be of particular importance because they strongly support the hypothesis that the NH2-terminal portion of the fibrin beta-chain is involved in the polymerization reaction by thrombin. The propositus' daughter and two sisters had the same abnormal fibrinogen. This unique inherited abnormal fibrinogen was designated as fibrinogen Ise. During these studies, we found that a very high concentration of thrombin cleaves not only the A alpha Arg19-Val20 bond but also the COOH-terminal region of alpha-chains, which results in the generation of further degraded alpha-chains with apparent molecular weights of 44,000 or less.

Amino Acid Sequence↗

PubMed1991

Purification of human placental aromatase cytochrome P-450 with monoclonal antibody and its characterization.

A simple and efficient method is described for the purification of microsomal aromatase cytochrome P-450 from human placenta. The enzyme was solubilized with Emulgen 913 and sodium cholate and subjected to chromatography on a column of Sepharose 4B coupled with a specific monoclonal antibody, followed by hydroxyapatite column chromatography. The specific cytochrome P-450 content of purified aromatase was 13.1 (12-14.8) nmol/mg of protein. Aromatase assays were carried out with reconstituted systems of bovine liver P-450 reductase and dilauroyl-L-alpha-phosphatidylcholine with [1 beta-3H,4-14C]-androstenedione as substrate. The specific activity of purified aromatase was 65.0 (50.6-74.3) nmol.min-1.(mg of protein)-1 or a turnover rate of 5.0 (4.3-5.9) min-1. The total recovery of purified aromatase activity was 32.2%, and P-450 recovery was 17.6%. The Km of immunoaffinity-purified aromatase was 12, 210, 41, and 2830 nM for androstenedione, 16 alpha-hydroxyandrostenedione, testosterone, and 16 alpha-hydroxytestosterone, respectively. The very high Km value for 16 alpha-hydroxytestosterone aromatization gives a reasonable indication that estriol is not the directly aromatized product in the fetoplacental unit of human pregnancy. The aromatase P-450 was subjected to SDS-polyacrylamide gel electrophoresis in increasing quantities. Silver stain detection techniques indicated a single band having a molecular mass of 55 kDa with greater than 97% purity. The stability analysis showed a half-life of over 4 years on storage at -80 degrees C.

Animals↗

PubMed1991

A classification of acute leukaemia for the 1990s.

The need for reproducibility in the classification of acute leukaemia has made it necessary to incorporate information derived from new techniques which have become essential for the study of these disorders. In addition to classic morphology and cytochemistry (FAB proposals), it is necessary to add immunology and cytogenetics (MIC proposals), as well as to investigate further the biological and diagnostic significance of molecular events. As a result of these investigations a new group of leukaemias merit recognition as distinct entities. These include three types of ALL with specific chromosome abnormalities, namely, i) t (9;22), ii) t (4;11) and iii) t (1;19) and four subtypes of AML, i) with minimal differentiation or AML-M0, ii) with basophilic precursors or M2Baso, iii) AML (M4/M5) with t (8;16) and iv) AML with trilineage myelodysplasia. Biphenotypic acute leukaemia constitutes also a distinct entity with features of ALL and AML and represents a malignancy probably affecting multipotent stem cells. We propose an objective evaluation system for biphenotypic leukaemias based on a score in which the various lineage markers are graded according to their known specificity.

Humans↗

PubMed1991

Role of platelet-activating factor (PAF) in superoxide production by human polymorphonuclear leukocytes.

The effect of platelet-activating factor (PAF) in superoxide production by human polymorphonuclear leukocytes (PMN) was studied. Cypridina luciferin analog (CLA) dependent chemiluminescence was used to detect superoxide anion radicals. PAF induced superoxide generation in human PMN in a dose-dependent manner. Preincubation with a small amount of PAF (5 x 10(-9) M) enhanced PMN superoxide release induced by various stimuli, such as phorbol myristate acetate (PMA), opsonized zymosan (OZ), calcium ionophore (A23187) and N-formyl-methionyl-leucyl-phenylalanine (FMLP). The PAF antagonist, CV-6209, inhibited superoxide production induced by PAF, but not that induced by other stimuli. These findings would indicate that PAF may play an important role at inflammatory reaction sites and that CV-6209 may inhibit excessive inflammatory reaction.

Calcimycin↗

PubMed1991

Identification of epitopes within the circumsporozoite protein of Plasmodium vivax recognized by murine T lymphocytes.

The murine cellular immune response to the circumsporozoite (CS) protein of Plasmodium vivax was characterized using five synthetic peptides, some of which we identified as corresponding to T cell epitopes. The peptides P308-320, P344-355 and P353-364 were immunogenic, inducing a genetically restricted proliferative response, due to the activation of CD4+ T cells. The peptide P308-320 was recognized only by the lymphocytes of B10 (H-2b) mice. The other two peptides were recognized by primed lymphocytes of H-2a and H-2k mice. Of interest was the finding that one of these peptides, P353-364, induced a proliferative response of a large percentage of immune outbred Swiss mice. Our data provide evidence that, at least in mice, there is recognition of multiple T cell epitopes within the major surface antigen of P. vivax sporozoites.

Amino Acid Sequence↗

PubMed1991

Involvement of 5-hydroxytryptamine 3 receptors in regulation of interdigestive gastric contractions by motilin in the dog.

The effects of IV injection of 5-hydroxytryptamine 3 receptor antagonists (BRL 43694 and GR38032F) on gastrointestinal contractile activity were studied in dogs with vagally denervated fundic pouch in the conscious state by means of chronically implanted force transducers in the gastrointestinal tract and the pouch. In the interdigestive state, 5-hydroxytryptamine 3 receptor antagonists (0.01-0.1 mg/kg), if given during phase III contractions, instantly and dose-dependently inhibited the spontaneous and motilin-induced phase III contractions in the intact stomach and altered the duodenal phase III contractions to a pattern of continuous contractions, the contractile force which was 65% of the spontaneous phase III contractions in the duodenum and caused immediate caudad migration of phase III contractions along the small intestine. However, the spontaneous and motilin-induced phase III-like contractions in the denervated pouch were not affected at all by 5-hydroxytryptamine 3 receptor antagonists. When 5-hydroxytryptamine 3 receptor antagonists (0.1-3.0 mg/kg) were given during the phase I period, they did not directly stimulate gastrointestinal contractions. The cyclic fluctuation of the plasma motilin concentration with phase III activity in the stomach was also not influenced by 5-hydroxytryptamine 3 receptor antagonists, but the next phase III contractions in the stomach were inhibited. During the digestive state, however, 5-hydroxytryptamine 3 receptor antagonists (0.1-3.0 mg/kg) did not influence contractile activity in the gastrointestinal tract and in the vagally denervated fundic pouch. On the basis of recent pharmacological studies showing that the distribution of 5-hydroxytryptamine 3 receptors is recognized in the area postrema, peripheral neurons of vagal afferents, and the enteric nervous system, the results of the current study provide a basis for a hypothesis that 5-hydroxytryptamine 3 receptor antagonists are most likely to block motilin-induced signals at 5-hydroxytryptamine 3 receptors on the vagal afferents. In conclusion, the present findings suggest the possible involvement of 5-hydroxytryptamine 3 receptors on vagal afferents especially in terms of endogenous release of acetylcholine in the control of interdigestive phase III activity in the stomach by motilin.

Acetylcholine↗

PubMed1991

Novel benzamides as selective and potent gastrokinetic agents. 2. Synthesis and structure-activity relationships of 4-amino-5-chloro-2-ethoxy-N-[[4-(4-fluorobenzyl)-2- morpholinyl]methyl] benzamide citrate (AS-4370) and related compounds.

The title compounds (19-55) with a 4-substituted 2-(aminomethyl)morpholine group were prepared and evaluated for the gastrokinetic activity by determining their effect on gastric emptying of phenol red semisolid meal in rats. Introduction of chloro, fluoro, and trifluoromethyl groups to the benzyl group of the parent compounds 1a and 1b enhanced the activity. Among compounds tested, 4-amino-5-chloro-2-ethoxy-N-[[4-(4-fluorobenzyl)-2-morpholinyl] methyl] benzamide (23b) showed the most potent gastric emptying activity (effects on phenol red semisolid meal in rats and mice, and on resin pellets solid meal in rats). The gastrokinetic activity of 23b citrate (AS-4370) compared very favorably with that of cisapride and was higher than that of metoclopramide. In contrast to metoclopramide and cisapride, AS-4370 was free from dopamine D2 receptor antagonistic activity in both in vitro ([3H]spiperone binding) and in vivo (apomorphine-induced emesis in dogs) tests.

Animals↗

PubMed1991

Molecular cloning and expression in Escherichia coli of cDNA encoding the subunit of sweet potato beta-amylase.

Tuberous roots of the sweet potato are unusually rich in beta-amylase, and the beta-amylase polypeptides account for about 5% of the total soluble protein of the organ. Unlike beta-amylases from other origins, the sweet potato beta-amylase is a tetramer of identical subunits, and it also bears starch phosphorylase-inhibitor activity. A cDNA for the subunit of sweet potato beta-amylase was obtained by immunological screening of an expression cDNA library constructed by the vector-primer and linker method using a plasmid vector containing tac-SP6 promoters. The SP6 transcript of a 2,000 base-pair-long cDNA insert directed the synthesis in vitro of a precursor to the subunit of beta-amylase which was identical in size with the mature subunit, and the beta-amylase mRNA detected by Northern blot hybridization was identical in size with the SP6 transcript of the cDNA insert. The cDNA insert contained 1,494 base pairs of an open reading frame which codes for the 499-amino-acid-long precursor to the subunit of beta-amylase. An amino acid sequence identical to the N-terminal amino acid sequence of the mature subunit appeared immediately after the initiator methionine of the precursor, indicating that the subunit of beta-amylase is synthesized as a mature form. Comparison of the amino acid sequences of subunits of sweet potato beta-amylase and seed beta-amylases from barley and soybean indicated that these enzymes share about 68% amino acid identities among each other. Escherichia coli cells harboring the cDNA clone produced the mature-sized subunit of the beta-amylase, and the soluble extract exhibited amylolytic activity which migrated to the same position as the beta-amylase purified from the sweet potato in non-denaturing polyacrylamide gel containing soluble starch indicating that oligomerization of the subunit occurred properly in E. coli cells.

Amino Acid Sequence↗

PubMed1991

Subsite mapping of an acidic amino acid-specific endopeptidase from Streptomyces griseus, GluSGP, and protease V8.

The substrate specificities of an acidic amino acid-specific endopeptidase of Streptomyces griseus, GluSGP, and protease V8 [EC 3.4.21.19] were investigated with peptide p-nitroanilide substrates which have a Glu residue at the P1 position. GluSGP and protease V8 favored Pro and Leu residues at S2, respectively, while the S3 subsite of GluSGP preferred Phe over either Ala or Leu. The S3 subsite of protease V8 preferred Leu over either Ala or Phe. The best substrates for GluSGP and for protease V8 were Boc-Ala-Phe-Pro-Glu-pNA with a Km value of 0.41 mM (0.1 M Tris-HCl, pH 8.8) and Boc-Ala-Leu-Leu-Glu-pNA with a Km value of 0.25 mM (0.1 M phosphate, pH 7.8), respectively. The kcat/Km values for these substrates obtained with GluSGP were about one hundred to twenty thousand times larger than those obtained with protease V8. Protease V8 exhibited a single optimal pH of around 8 for the hydrolysis of Boc-Ala-Ala-Leu-Glu-pNA and Boc-Ala-Leu-Leu-Asp-pNA.

Amino Acid Sequence↗

PubMed1991

Sucrose-Induced Accumulation of beta-Amylase Occurs Concomitant with the Accumulation of Starch and Sporamin in Leaf-Petiole Cuttings of Sweet Potato.

beta-Amylase of sweet potato (Ipomoea batatas L.), which constitutes about 5% of the total soluble protein of the tuberous root, is absent or is present in only small amounts in organs other than the tuberous roots of the normal, field-grown plants. However, when leaf-petiole cuttings from such plants were supplied with a solution that contained sucrose, the accumulation of beta-amylase was induced in both leaf and petiole portions of the explants. The sucrose-induced accumulation of beta-amylase in leaf-petiole cuttings occurred concomitant with the accumulation of starch and of sporamin, the most abundant storage protein of the tuberous root. The accumulation of beta-amylase, of sporamin and of starch in the petioles showed similar dependence on the concentration of sucrose, and a 6% solution of sucrose gave the highest levels of induction when assayed after 7 days of treatment. The induction of mRNAs for beta-amylase and sporamin in the petiole could be detected after 6 hours of treatment with sucrose, and the accumulation of beta-amylase and sporamin polypeptides, as well as that of starch, continued for a further 3 weeks. In addition to sucrose, glucose or fructose, but not mannitol or sorbitol, also induced the accumulation of beta-amylase and sporamin, suggesting that metabolic effects of sucrose are important in the mechanism of this induction. Treatment of leaf-petiole cuttings with water under continuous light, but not in darkness, also caused the accumulation of small amounts of these components in the petioles, probably as a result of the endogenous supply of sucrose by photosynthesis. These results suggest that the expression of the gene for beta-amylase is under metabolic control which is coupled with the expression of sink function of cells in the sweet potato.

Journal Article↗

PubMed1991

Alloimmune neonatal neutropenia in monozygous twins. High-dose intravenous gammaglobulin therapy.

An indirect immunofluorescence test using a flow cytometer (FACS420) was useful for detection of antineutrophil antibodies (anti-NA2 antibodies) in a case of monozygous twins with alloimmune neonatal neutropenia. When high-dose intravenous gammaglobulin (300 mg/kg for five consecutive days) was given to one twin, the increase in neutrophils was not obvious. Although neutropenia persisted for about three months, no infections were observed in either of the twins.

Autoimmune Diseases↗

PubMed1991

Resistance to acute Trypanosoma cruzi infection resulting from immunization of mice with a 90-kilodalton antigen from metacyclic trypomastigotes.

The stage-specific 90-kDa surface antigen of Trypanosoma cruzi metacyclic trypomastigotes was affinity purified and used for immunization studies. Mice immunized with the 90-kDa antigen plus alum as an adjuvant were resistant to challenge with Tulahuen strain metacyclic forms, displaying either reduced or subpatent parasitemias. Mice immunized with the purified antigen without adjuvant or with antigen plus Freund adjuvant or glucan developed high parasitemias, comparable to those of nonimmunized controls, upon metacyclic challenge. Sera of mice immunized with the 90-kDa antigen plus alum showed complement-dependent trypanolytic activity and also greatly inhibited the invasion of Vero cells by metacyclic forms of G and Tulahuen strains in vitro. These sera were found by a competition binding assay to contain antibodies that recognized the same or topographically related sites as the monoclonal antibody 1G7, an antibody previously shown to reduce the infectivity of metacyclic forms in vivo and in vitro. In contrast, 1G7-related antibodies were poorly represented in sera with negative or low trypanolytic activity, such as those from mice immunized with purified antigen without adjuvant.

Acute Disease↗

PubMed1991

Development of a radioimmunoassay for human group-II phospholipase A2 and demonstration of postoperative elevation.

A radioimmunoassay (RIA) for the determination of human group-II phospholipase A2 (M-PLA2) has been developed. M-PLA2 was purified from human spleen. Monoclonal antibody (IgG) was prepared by fusion of splenic cells from immunized mice with M-PLA2 and the mouse myeloma cell line NS-1. The RIA was carried out by a single antibody method. The assay is sensitive (0.78 micrograms/l), reproducible and specific. In healthy individuals, the serum M-PLA2 concentration ranges from 1.4 to 4.2 micrograms/l, the average being 2.2 +/- 0.1 micrograms/l (mean +/- SE). Using the RIA, we found increased serum M-PLA2 in patients with various infections and malignant tumors. We also showed the postoperative transient elevation of serum M-PLA2 in cases without any infectious complications. The elevation was independent of the surgical procedure or site. The maximum serum M-PLA2 level was seen on the 2nd to 4th postoperative day. In these patients, the serum M-PLA2 and C-reactive protein levels were significantly correlated. The present study indicated that serum M-PLA2 is an acute phase reactant.

Acute-Phase Proteins↗

PubMed1991

Structures of two new steroidal glycosides, soladulcosides A and B from Solanum dulcamara.

The structures of two new steroidal glycosides named soladulcosides A and B, isolated from the aerial parts of Solanum dulcamara including new sapogenols, were elucidated as (22R, 25R)-3 beta, 15 alpha, 23 alpha-trihydroxy-5 alpha-spirostan-26-one 3-O-alpha-L-rhamnopyranosyl-(1----2)-beta-D-glucopyranoside and (22R, 25R)-3 beta,23 alpha-dihydroxy-5 alpha-spirostan-26-one 3-O-alpha-L-rhamnopyranosyl-(1----2)-[alpha-L-rhamnopyranosyl-(1----4)]- beta-D-glucopyranoside, respectively.

Glycosides↗

PubMed1991

[Influence of hepatitis C virus on the alcoholic liver diseases].

In order to know the influence of hepatitis C virus (HCV) on the alcoholic liver diseases (ALD), 124 patients with ALD were divided into two groups by positive or negative anti-HCV, and differences of histological findings, laboratory data, evolution of histopathology and liver disease of those who developed hepatocellular carcinoma (HCC) between both groups were investigated. There were 31 patients (25%) in the anti-HCV positive group and 93 patients (75%) in the negative group. Histologically, viral changes were seen in most patients (55%) of the positive group, whereas those were seen in a few patients (15%) of the negative group. The patients of the positive group showed higher serum adenosine deaminase levels compared with those of the negative group. However, as regards the evolution of histopathology, amount of alcohol consumed seemed to be more responsible than positive anti-HCV. Three out of 6 patients with HCC were anti-HCV positive cirrhotics, although there were three anti-HCV negative HCC patients: one with cirrhosis and two with hepatic fibrosis.

Adenosine Deaminase↗

PubMed1991

[Intraarterial injection of low molecular weight dextran and urokinase for acute cerebral infarction].

Strategic recanalization of the occluded cerebral vessels has shown promise as a therapy for embolism and thrombosis in the acute stage. A single-dose of urokinase (UK) administered by intravenous and intraarterial routes was usually designed to restore patency of the infarct-related arteries and reperfuse the area of infarction. However, thrombolytic agents which have been available to date may lack resoluvability, limiting the amount of doses, because overdosage may induce hemorrhagic complication. This newly-designed therapy, intraarterial injection of UK-low molecular dextran (LMWD) complex was introduced in order to overcome the danger shown in the previous study. A high-resolvent allows cut-down of urkinase doses. Patients with acute cerebral infarction were selected for treatment with the resolvent if they satisfied the following conditions: 1) up to 79 years old without serious systemic diseases, 2) less than 12 hours from the onset, 3) better than the score of 8 in GCS, 4) no abnormality in CT scan, 5) apparent neurological deficit and 6) responsible pathology in angiography. LMWD of 15ml, UK of 240000IU and 15ml saline-complex was injected as one course at 2.0-2.5ml/min for 11 cases. Recanalization was observed in seven cases of embolism, and lack of reperfusion in five cases of thrombosis. The minimum effective dose was determined as 480000IU of UK in two courses. In terms of time lag from the onset, six hours may be the inferior limit, within which five of six cases (83%) succeeded in the recanalization.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1991

[Pharmacokinetic, bacteriological and clinical studies on cefdinir fine granules in the field of pediatrics].

The Pharmacokinetics and clinical effectiveness of cefdinir (CFDN, FK482) were examined in pediatric patients. The results are summarized as follows. 1. Plasma concentrations and urinary excretions of CFDN after administration of 5% fine granules were investigated on 4 children at a dose level of 6 mg/kg. Average plasma concentrations peaked at 4 hours after administration at 0.99 micrograms/ml with a half-life of 2.12 hours. The first 24-hour urinary recovery rates of CFDN in 3 children averaged 22.0%. 2. CFDN was given to 24 children (11 with pharyngitis, 3 with tonsillitis, 8 with scarlet fever, 1 with urinary tract infection and 1 with enteritis due to Salmonella); 15 were treated with 5% fine granules and 9 with 10% fine granules at daily doses of about 10 mg/kg in 2 to 3 divided portions. Clinical effects were excellent in 16, good in 7 and not evaluable in 1, with an overall efficacy rate of 100%. 3. Identified causative organisms were 12 strains of Streptococcus pyogenes, 4 of Haemophilus influenzae, 5 of Haemophilus parainfluenzae, 1 of Escherichia coli, and 1 of Salmonella. Bacteriological effects were rated as "eradicated" for 19 strains, "unchanged" for 4 with an eradication rate of 82.6%. 4. No side effects were observed. As for abnormal laboratory test results, a transient decrease of white blood cells was observed in 1 patient. 5. The CFDN fine granule preparations were preferably accepted by the children. 6. The fine granular preparations of CFDN, a new oral antibiotic, were useful for the treatment of bacterial infections in pediatrics.

Administration, Oral↗