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Biomedical subjects

M Yamazaki

Publications and source records attributed to M Yamazaki.

At least 685 records · Page 38Linked to original sources
PubMed1989

Purification and characterization of a cytolytic protein from purple fluid of the sea hare, Dolabella auricularia.

A novel cytolytic factor, dolabellanin P, was purified to apparent homogeneity from the purple fluid of the sea hare, Dolabella auricularia. Purified dolabellanin P is a single polypeptide of 60 kDa. The amino acid composition and the N-terminus of the factor were also determined. This factor nonspecifically lysed all the cells tested at 50-200 ng protein/ml. Dolabellanin P caused complete cytolysis within 2 h. The factor is distinct from antineoplastic glycoproteins previously isolated from eggs (aplysianin E) or albumen gland (aplysianin A) of Aplysia kurodai in terms of certain cytolytic properties. These results suggest that dolabellanin P, found in the sea hare, a marine invertebrate, is a new cytolytic factor.

Amino Acid Sequence↗
PubMed1989

Structure of a novel epidithiodioxopiperazine, emethallicin A, a potent inhibitor of histamine release from Emericella heterothallica.

A new epidithiodioxopiperazine derivative, emethallicin A (1), was isolated along with ergosterol from the mycelial extract of the heterothallic fungus, Emericella heterothallica (mating type A). The structure of emethallicin A (1) was established on the basis of chemical and spectroscopic investigations and finally by chemical transformation to apoaranotin (11). Emethallicin A (1) has the same basic skeleton as apoaranotin (11), with C6-C2 carboxylic acid (mandelic and phenylacetic acids) diester moieties, and showed a potent inhibitory activity on histamine release from mast cells.

Ascomycota↗
PubMed1989

Biopolymers from marine invertebrates. X. Mode of action of an antibacterial glycoprotein, aplysianin E, from eggs of a sea hare, Aplysia kurodai.

An antibacterial factor, aplysianin E, was purified from the eggs of a sea hare, Aplysia kurodai. Purified aplysianin E was a glycoprotein of 250 kilo daltons consisting of 3 subunits, and showed both antibacterial and antineoplastic activities. The two activities were lost in parallel on heating and at low and high pH. This factor was half-maximally active for gram-positive and -negative bacteria at 0.12-3.3 micrograms/ml and its action was not bactericidal but bacteriostatic. Aplysianin E did not induce morphological elongation of bacteria or their release of adenosine triphosphate (ATP), but it completely inhibited the syntheses of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) by E. coli within 10 min. These results suggest that aplysianin E, found in an invertebrate, the sea hare, is a new antibacterial protein and that it exerts its action by inhibiting nucleic acid synthesis, as a DNA-inhibiting chemotherapeutic drug does.

Animals↗
PubMed1989

Biopolymers from marine invertebrates. XI. Characterization of an antineoplastic glycoprotein, dolabellanin A, from the albumen gland of a sea hare, Dolabella auricularia.

An anti-neoplastic factor, dolabellanin A, inducing tumor lysis was purified from the albumen gland of a sea hare, Dolabella auricularia. Purified dolabellanin A was found to be a glycoprotein of 250 kilodaltons containing 4 subunits. This factor was half-maximally active towards a variety of tumor cells at 1-18 ng protein/ml and lysed tumor necrosis factor (TNF)-resistant tumor cells. Dolabellanin A was labile on heating, at low and high pH, and on treatment with urea, guanidine, sodium lauryl sulfate or trypsin, but not with 2-mercaptoethanol or periodate. Dolabellanin A completely inhibited the syntheses of deoxyribonucleic acid and ribonucleic acid by tumor cells within 1 h and caused their complete cytolysis within 18 h. Tumor lysis by dolabellanin A was not inhibited by anti-TNF antibody but was inhibited by certain sugars, suggesting that recognition of a sugar moiety is a key step in its induction of cytolysis. Dolabellanin A also prolonged the survival of mice bearing syngeneic MM46 ascitic tumors (p less than 0.001). These results suggest that dolabellanin A, found in an invertebrate, the sea hare, is a new antitumor factor.

Amino Acids↗
PubMed1989

[The effects of nicardipine on morphological changes and calcium accumulation during ischemic hypoxia in pyramidal nerve cells in the rat cerebral cortex].

The morphological changes and the calcium accumulation were studied in the rat pyramidal nerve cells which had undergone 5% oxygen inhalation and bilateral carotid artery clamping for 15 minutes, using combined methods of electron and the X-ray microanalytical microscopes. To study the protective effects of nicardipine on brain hypoxia, the same techniques were also used after the inhalation. In the 5% oxygen inhalation group, the chromatin clamping in the nucleus was observed, but calcium ions could not be detected in the neuron using the X-ray microanalytical techniques. In the carotid clamping groups under 5% oxygen inhalation, severe nuclear change and mitochondrial swelling were observed and calcium ions were detected in the mitochondrion. After administrations of nicardipine under 5% oxygen inhalation and under carotid clamping with 5% oxygen, similar morphological changes were recognized by the electron microscope as compared to the non-administration groups. The rate of calcium ion detection was not different significantly (P less than 0.05) between the nicardipine administration and the non-administration groups. It is, therefore, concluded that notable protective effects of nicardipine on ischemic hypoxia were not recognized in this experiment.

Animals↗
PubMed1989

[Changes in serum parathyroid hormone levels during pregnancy].

As pregnancy poses a significant challenge to maternal calcium homeostasis, it is interesting to investigate a change in serum parathyroid hormone (PTH) level throughout pregnancy. PTH metabolism in pregnancy has not been clearly defined. We have made an attempt to evaluate changes in serum intact PTH level during pregnancy. Compared with nonpregnant women, serum intact PTH concentrations were decreased significantly in pregnant women during the first and the second trimester, but not during the third trimester. Nephrogenous cyclic AMP excretion, index of parathyroid function has been reported to be decreased in pregnant women during the first and second trimester, but to be in normal range in pregnant women during third trimester. Our finding consisted with these facts.

Adult↗
PubMed1989

[Changes in catecholamines of the striatum during 5% oxygen administration and the alleviating effects of flunarizine in rats].

Five percent oxygen was administered to rats under controlled respiration. The concentrations of catecholamines and their metabolites (dopamine, HVA, DOPAC, norepinephrine) were measured during 5% oxygen administration and subsequent recovery period. Flunarizine, a calcium channel blocker, was administered and its effects on catecholamine fluctuations were studied. Results were as follows. Dopamine increased with 5% oxygen administration. DOPAC and norepinephrine decreased and no changes were seen in HVA. After 20 min of hypoxia, catecholamine contents returned to the control levels in another 2 hours of air breathing. When flunarizine was administered in advance, changes in catecholamine content appeared to be lower during 5% oxygen administration and subsequent recovery period.

Animals↗
PubMed1989

[Effects of ketamine on K+-contracture in isolated vascular smooth muscle from rabbit].

The effects of ketamine on contraction induced by depolarization of cell membrane (high K+-induced contracture) were studied in isolated vascular smooth muscle from rabbit portal vein. Ketamine in concentrations above 5 x 10(-4) M caused relaxation in phasic contraction, and above 10(-4) M caused relaxation in tonic contraction. These effects of ketamine at concentrations of between 10(-5) to 10(-3) M were dose dependent and reversible. In concentration above 10(-5) M, ketamine decreased the contractile response (tonic contraction) induced by 2.5 mM Ca2+ after the temporary contracture in Ca2+-free, high K+ solution. The contractile responses to norepinephrine (10(-6) M) or serotonin (10(-6) M) were also inhibited by ketamine. From these findings, it is concluded that ketamine decreases contractile responses due to transmembrane Ca2+ influx after depolarization of cell membrane and may decrease the contractile responses in concentration above 5 x 10(-4) due to Ca2+ release inhibition from sarcoplasmic reticulum.

Animals↗
PubMed1989

[Bacteriological, pharmacokinetic and clinical studies on cefteram pivoxil in the pediatric field].

Bacteriological, pharmacokinetic and clinical studies were done on the effect of cefteram pivoxil (CFTM-PI, T-2588) (10% granules), a new oral cephalosporin, in the field of pediatrics. The results are summarized below. 1. Antibacterial activities Antibacterial activities of CFTM against Staphylococcus aureus and Streptococcus pyogenes were studied comparatively with activities of cefaclor (CCL), cephalexin (CEX) and ampicillin (ABPC). MICs of CFTM against S. aureus were distributed in a range between 0.78 and 12.5 micrograms/ml, with a peak value of 3.13 micrograms/ml, which were similar to MIC ranges of CEX and CCL. MICs of CFTM against all strains of S. pyogenes were less than or equal to 0.025 microgram/ml, which were similar to MIC of ABPC. CFTM was approximately 2 to 3 folds more effective than CCL or CEX. 2. Absorption and excretion. Serum concentrations and urinary excretions of CFTM were determined in doses of 3 mg/kg (non-fasting) and 6 mg/kg (non-fasting and fasting). In non-fasting subjects, peak concentrations of CFTM in serum were dose-dependent and were 1.15-2.3 micrograms/ml and 1.8-3.6 micrograms/ml at 2-3 hours, 0.125-0.78 micrograms/ml and 0.245-0.97 micrograms/ml at 6 hours, respectively, for the 2 dose levels. Serum half-lives were 1.03-2.65 hours for the dose of 3 mg/kg and 1.07-1.83 hours for 6 mg/kg. In fasting subjects, the mean peak serum concentrations were 1.73 micrograms/ml at 2 hours and 1.13 micrograms/ml at 6 hours for the dose of 6 mg/kg. Urinary recovery rates in the first 6 hours varied 5.3-19.2%. 3. Clinical study Clinical efficacies were examined in a total of 41 cases including 9 cases of bacterial pneumonia, 10 cases of bronchitis, 11 cases of tonsillitis, 7 cases of urinary tract infections, 3 cases of scarlet fever and 1 case of otitis media. Clinical efficacies were excellent in 30 cases, good in 10 cases, poor in 1 case, hence the efficacy rate was 97.6%. All of the 28 bacteria identified in these cases were eradicated after CFTM-PI treatments. No noticeable abnormalities were found as side effects. An elevation of eosinophil, an increase of platelet count and elevations of GOT and GPT were observed in 3 patients.

Bacterial Infections↗
PubMed1988

Anti-bilirubin monoclonal antibody. I. Preparation and properties of monoclonal antibodies to covalently coupled bilirubin-albumin.

We have prepared 16 anti-bilirubin monoclonal antibodies and described their unique reactivity to bilirubin and related compounds. Using the modified mixed anhydride method, bilirubin was covalently coupled to bovine serum albumin. We performed somatic cell fusion between murine spleen cells immunized with this bilirubin-albumin complex and murine myeloma P3-X63-Ag8-U1 cells. After screening assays, 16 clones were identified which were producing antibodies not to albumin but to haptenic bilirubin. In inhibition analysis, the antibodies in the culture supernatants cross-reacted with bilirubin glucuronides to varying degrees, but rarely reacted with structurally related biliverdin, hemin, and azodipyrroles of bilirubin. Albumin, when present in the solution, much reduced the reactivity of several monoclonal antibodies to unconjugated bilirubin, and this effect was partly reversed by addition of salicylate which dissociates the binding between bilirubin and albumin.

Animals↗
PubMed1988

Anti-bilirubin monoclonal antibody. II. Enzyme-linked immunosorbent assay for bilirubin fractions by combination of two monoclonal antibodies.

Among 16 monoclonal antibodies raised against covalently coupled bilirubin-bovine serum albumin, we selected two antibodies: one (designated 24G7) reacted with unconjugated and conjugated bilirubin and the other (designated 25H17) reacted only with unconjugated bilirubin. Combination of these two antibodies enabled us to determine extremely low concentrations of unconjugated and conjugated bilirubin independently by enzyme-linked immunosorbent assay (ELISA). In the assay, samples were incubated with each anti-bilirubin IgG, and then free remaining IgG was allowed to bind to the immunotiter plates coated with bilirubin-bovine serum albumin. The bound fraction of the IgG was visualized with horseradish peroxidase-conjugated rabbit anti-mouse IgG and substrate. Bilirubin concentration was determined from the absorbance at 425 nm. In this system, we could measure 10(-7)-10(-5) M unconjugated and conjugated bilirubin in samples, which is 100-fold more sensitive than Michaëlsson's diazocoupling method. The assay results gave a good correlation coefficient (0.86) compared with those determined with high performance liquid chromatography.

Antibodies, Monoclonal↗
PubMed1988

RS-5186, a novel thromboxane synthetase inhibitor with a potent and extended duration of action.

RS-5186, sodium 6-[2-[1-(1H)-imidazolyl]methyl-4,5-dihydrobenzo[b]thiophene]- carboxylate, inhibited platelet thromboxane A2 (TXA2) synthetase with IC50 values of 6 nM and 13 nM for human and rabbit microsomes, respectively. It had a selectivity for TXA2 synthetase 10(5)-fold greater than that for cyclooxygenase, PGI2 synthetase, 5-lipoxygenase and phospholipase A2. When administered orally or intravenously to dogs at 1 mg/kg, RS-5186 suppressed serum TXB2 levels almost completely with sustained duration of action: the suppression during 0.5 hr to 8 hr after dosing was more than 90%, and was 70-80% at 24 hr. Similar suppression of serum TXB2 levels was observed in rats and rabbits. Such suppression by RS-5186 was more potent than that by OKY-046 and CV-4151. Serial administration of RS-5186 (0.1 mg/kg/day p.o.) to dogs for 7 days decreased the serum TXB2 levels constantly during the medication, and no rebound phenomenon was observed after the medication was stopped. In a thrombotic model induced by sodium arachidonate injection in rabbits, RS-5186 at 1 mg/kg p.o. completely protected against sudden death (ED50 = 0.12 mg/kg, 1 hr after dosing) and this protective effect extended over 8 hr. All these results show that RS-5186 is a potent and highly selective TXA2 synthetase inhibitor with a long duration of action, and suggest that the compound could be useful in diseases where TXA2 is involved.

Animals↗
PubMed1988

Micro high-performance liquid chromatographic determination of cardiac glycosides in beta-methyldigoxin and digoxin tablets.

A micro high-performance liquid chromatographic (micro-HPLC) method has been developed for the assay of beta-methyldigoxin and digoxin tablets. Quantitation of cardiac glycosides in tablets was carried out by the incorporation of dexamethasone as an internal standard. The procedure consisted of disintegration of tablets, extraction with acetone-ethanol (9:1) and injection for micro-HPLC on an ODS micro column, using acetonitrile-water (28:72) for beta-methyldigoxin tablets and methanol-water (1:1) for digoxin tablets; the effluent was monitored by UV detection at 220 nm. The average values of the contents in beta-methyldigoxin and digoxin tablets were 99.6 and 100.2% of the labelled amounts, respectively. The proposed method is sufficiently precise and sensitive to examine the content uniformity of tablets.

Cardiac Glycosides↗
PubMed1988

Augmentation of release of cytotoxin from murine bone marrow macrophages by gamma-interferon.

gamma-Interferon (IFN-gamma) was shown to amplify cytotoxin release from murine bone marrow-adherent macrophages in response to an animal lectin as a second stimulus. This stimulation of cytotoxin release was demonstrated both in vitro and in vivo and was maximal 2 h after treatment with IFN-gamma. No change in expression of surface antigens was detected on bone marrow-adherent cells treated with IFN-gamma. IFN-gamma also augmented production of cytotoxin from bone marrow-adherent cells that had been cultured for several days. This cytotoxin was inhibited by rabbit anti-tumor necrosis factor serum and had a molecular weight of 70,000. These findings showed that both freshly isolated and cultured bone marrow macrophages could release cytotoxin and that cytotoxin production in response to a second stimulus was augmented by IFN-gamma. The results also suggest that IFN-gamma can activate all macrophages in vivo, irrespective of their states of maturation and differentiation.

Animals↗