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Biomedical subjects

S Hamano

Publications and source records attributed to S Hamano.

At least 109 records · Page 6Linked to original sources
PubMed1993

Effect of thiol compounds on in vitro development and intracellular glutathione content of bovine embryos.

The purpose of this investigation was to determine the effect of beta-mercaptoethanol (beta-ME) and cysteamine, low-molecular-weight thiol compounds, on the development and intracellular glutathione content of bovine embryos obtained by in vitro fertilization of in vitro-matured oocytes. Embryos developed to the 6-8-cell stage after in vitro fertilization were cultured without feeder cells in TCM-199 containing 10% fetal calf serum with or without beta-ME or cysteamine. The percentage of embryos that developed to the blastocyst and hatched blastocyst stages were significantly higher in medium containing beta-ME or cysteamine. Also, total intracellular glutathione levels were higher for embryos cultured in the medium with beta-ME or cysteamine than for those cultured in medium without thiol compounds. Moreover, when buthionine sulfoximine, a specific inhibitor of glutathione synthesis, was added to medium containing thiol compounds, there was a reduction both in the development of embryos to the blastocyst stage and in intracellular glutathione content. These results indicate that the inclusion of low-molecular-weight thiol compounds aids the in vitro development of bovine embryos without feeder cells and that the effect of thiol compounds is mediated through the increase of intracellular glutathione levels.

Animals↗
PubMed1993

Neurological manifestations of hemorrhagic colitis in the outbreak of Escherichia coli O157:H7 infection in Japan.

An outbreak of hemorrhagic colitis associated with Escherichia coli O157:H7 occurred in a kindergarten in Saitama, Japan from September to November, 1990. Seven patients admitted to our hospital showed neurological manifestations: generalized seizures, impaired consciousness, urinary incontinence, gaze nystagmus, phrenic nerve palsy, action tremor and vertigo. Two patients died. On the basis of the clinical courses and laboratory findings of the seven patients and postmortem findings of one case, these neurological symptoms were suspected to be induced by the verotoxin elaborated by Escherichia coli O157:H7.

Bacterial Toxins↗
PubMed1993

Intestinal brush-border transport of the oral cephalosporin antibiotic, cefdinir, mediated by dipeptide and monocarboxylic acid transport systems in rabbits.

Intestinal absorption of the orally active cephalosporin, cefdinir, was investigated using brush-border membrane vesicles prepared from rabbit small intestine. The initial uptake of cefdinir was pH-dependent, with increased uptake at acidic pH, and was not influenced by either sodium gradient or membrane potential difference. Cefdinir uptake was saturable with an apparent Michaelis constant of 8.1 mM. Initial uptake of cefdinir was inhibited by dipeptides (glycyl-L-proline and glycylsarcosine), beta-lactam antibiotics (cephradine, cefixime and penicillin V), and monocarboxylic acids (acetic acid and L-lactic acid), whereas the uptake of cephradine and cefixime was not inhibited by monocarboxylic acids. Cefdinir significantly inhibited the initial uptake of cephradine, cefixime and [3H]acetic acid. From these results, it was suggested that cefdinir was transported across brush-border membranes by both dipeptide and monocarboxylic acid carriers.

Acetates↗
PubMed1992

Study of low molecular weight heparin effect on the relation between anticoagulant activity and antithrombin III affinity.

Low molecular weight heparin (FR-860), and conventional unfractionated heparin (UF-heparin) were fractionated by rabbit antithrombin III (AT III)-Sepharose, and the effects of each affinity fraction on the coagulation and fibrinolytic activities were investigated. FR-860 was fractionated to no-affinity, low-affinity (LA) and high-affinity (HA) fractions, and UF-heparin to LA and HA fractions. The HA fractions showed higher activities regarding the prolongation of activated partial thromboplastin time, anti-factor Xa activity and antithrombin activity compared with those of LA. The HA and LA fractions exhibited the enhancement of heparin cofactor II (HC II) activity and fibrinolytic activity in a dose-dependent manner. These results suggest that the antithrombotic activity of FR-860 is exerted through AT III and other mechanism such as HC II-mediated system.

Animals↗
PubMed1992

Study of anticoagulant mechanism of low molecular weight heparin.

The binding ability of low molecular weight heparin (FR-860), and conventional unfractionated heparin (UF-heparin) to factor Xa (F.Xa), thrombin and AT III was investigated using FR-860- and UF-heparin-Sepharoses. FR-860 could not bind directly to F.Xa. FR-860 bound to thrombin and AT III with stronger affinity to AT III than to thrombin. On the other hand, UF-heparin bound to F.Xa, thrombin and AT III with the strongest affinity to AT III followed by thrombin and F.Xa. AT III mediated the binding between F.Xa and FR-860 and accelerated the reaction between F.Xa and UF-heparin. On the other hand, AT III did not affect the binding between thrombin and FR-860 or UF-heparin. Diisopropyl fluorophosphate-treated thrombin inhibited the binding between AT III and FR-860, but not that between AT III and UF-heparin. These results suggest that the anti-F.Xa activity of FR-860 is mediated by AT III. Furthermore, the difference of antithrombin activity between FR-860 and UF-heparin depends on the capability to form ternary complex of FR-860 or UF-heparin, AT III and thrombin.

Animals↗
PubMed1992

Developmental changes in the incidence of chromosome anomalies of bovine embryos fertilized in vitro.

In total, 196 two- to 32-cell bovine embryo and 104 blastocysts were obtained by the in vitro fertilization of follicular oocytes matured in vitro, and 15 blastocysts fertilized in vivo were used. Chromosomal anomalies in these embryos and the inner cell mass (ICM) separated immunologically were investigated. Chromosomal anomalies were observed in 12.1% (5/41) of 2-cell embryos, 20.0-36.4% of 4- to 16-cell embryos, 7.1% (1/14) of 17- to 32-cell embryos, 44.2% (15/34) of blastocysts, and 18.6% (13/70) of ICM cells derived from in vitro fertilization. These anomalies were mainly 3N and 4N at 2-cell stage, 1N and 1N/2N at 4- to 32-cell stages, and 2N/4N in blastocysts and in their ICM cells. Chromosomal anomalies of blastocysts from in vivo fertilization and their ICM were observed in 20.0% (1/5) of blastocysts and 33.3% (3/9) of ICM cells and these compositions were mainly 2N/4N. These results indicate that the abnormalities at early and blastocyst stages of embryos derived from in vitro fertilization were caused by abnormal fertilization in vitro and abnormal cleavage, respectively. Furthermore, a definite location of the chromosomal anomalies was observed in the trophectoderm of blastocysts derived from in vitro fertilization.

Animals↗
PubMed1992

Treatment of early recurrent medulloblastoma in children with cisplatin and etoposide: a preliminary report.

The prognosis of recurrent medulloblastoma remains extremely poor. Combination chemotherapy with cisplatin (CDDP) and etoposide (VP-16) was given to five children with early recurrent medulloblastoma. As a rule, CDDP 20 mg/m2 per day and VP-16 60 mg/m2 per day were administered intravenously for 5 days. This cycle was repeated three times at 4-week intervals. After this therapy, cerebellar signs improved in one case and were unchanged in four cases. Weakness and sensory disturbance, however, improved in three of four patients. Moreover, neck and/or back pain resolved in all these four. Radiological findings improved in three cases. Myelosuppression appeared in all patients, but receded rapidly. No other significant complications were noticed. Two patients died 5 and 6 months after this therapy. These results seem to suggest that this therapy has a use in improving neurological symptoms, particularly neck and/or back pain, although its efficacy is limited.

Adolescent↗
PubMed1992

Novel eosinophilic inclusion in astrocytes.

Intracytoplasmic and brightly eosinophilic inclusions within neuroglias are reported in a patient with Aicardi's syndrome. Most inclusion-bearing neuroglias were protoplasmic astrocytes in the cerebral cortex. Compared with similar eosinophilic and intracytoplasmic inclusions in other studies using both light and electron microscopy, the inclusions in this report are regarded as being novel and not previously described. Ultrastructurally, the inclusions were composed of electron-dense granules and amorphous substances, and were not surrounded by a limiting membrane. They were numerous in the cerebral cortex, especially in part of the microgyrus, but absent in the deep cerebral white matter, subcortical nuclei, brain stem and the cerebellum. Therefore, they may be closely associated with brain malformation and congenital astrocytic dysfunction. They also suggested a functional difference in protoplasmic astrocytes themselves, according to the differentiation of related gray matter.

Agenesis of Corpus Callosum↗
PubMed1992

Full-term development of in vitro-matured, vitrified and fertilized bovine oocytes.

In vitro-matured bovine oocytes were vitrified in a mixture of 2 M-dimethyl sulphoxide (DMSO), 1 M-acetamide and 3 M-propylene glycol dissolved in mTCM199. After vitrification and thawing, the oocytes were exposed to 2-0.1M-sucrose solution in 1 or 12 steps to remove the cryoprotectants. Then the oocytes were fertilized in vitro and co-cultured with a monolayer of cumulus cells for 7 days. Nine of 88 inseminated oocytes developed to the blastocyst stage. Three blastocysts were transferred to 3 recipients, resulting in 2 pregnancies.

Journal Article↗
PubMed1992

Further studies on the relationship between tyrosine supply and catecholamine production in cultured adrenal chromaffin cells.

To elucidate a possible role of tyrosine supply as a factor modulating catecholamine biosynthesis in the adrenergic cell, the transport of [14C]tyrosine into cultured bovine adrenal chromaffin cells was first examined, and the relationship between [14C]tyrosine transport and [14C]catecholamine formation was then investigated. Under the conditions which were routinely employed to determine the rate of catecholamine biosynthesis, tyrosine was taken up into the cells in a manner independent of extracellular Na+ and Ca2+, and this uptake was also insensitive to ouabain and various metabolic inhibitors. The stimulation of these cells with high K+ and other secretagogues caused no significant alteration in the uptake. While, tyrosine transport was markedly inhibited by tyrosine analogues and other L-aromatic amino acids, and this inhibition was accompanied by the reduction of [14C]catecholamine formation. In contrast, tyrosine transport was markedly enhanced by flavone, and this enhancement was also accompanied by the augmentation of catecholamine production under the same experimental conditions. These results seem to indicate that the transport of tyrosine into the cells may be closely related to catecholamine formation within the cells, thus providing an evidence for a possible role of tyrosine supply as one of the factors affecting catecholamine production in the adrenal chromaffin cell.

Adrenal Medulla↗
PubMed1992

Synthesis and cardiovascular activity of phenylalkylamine derivatives. I. Potential specific bradycardic agents.

A series of acyclic amide derivatives of N-(omega-aminoalkyl)-N-methylhomoveratrylamine was synthesized and evaluated for their bradycardic activity in isolated guinea pig right atria. Among these compounds, (E)-N-[3-[N'-[2-(3,4-dimethoxyphenyl)ethyl]-N'-methylamino]propyl]- 4-[3,4-(methylenedioxy)phenyl]-3-butenamide (35) was the most potent in vitro and was also found to show dose-dependent bradycardia without remarkable reduction of left ventricular dp/dtmax or mean aortic pressure in anesthetized dogs.

Animals↗
PubMed1992

[Effect of tranilast, an anti-allergic drug, on the human keloid tissues].

We studied the inhibitory effects of tranilast, an anti-allergic drug, on the human keloid tissues implanted into the dorsal skin of athymic nude mice and on the growth of keloid fibroblast in vitro. In the keloid tissue-implanted model, tranilast (50-200 mg/kg, p.o.) decreased the weight of the keloid tissue as triamcinolone (25 mg/kg, p.o.) did. Tranilast (200 mg/kg, p.o.) reduced the hydroxyproline content of implanted tissues. Tranilast (3-300 microM) also inhibited the collagen synthesis by keloid fibroblast in vitro. Only a high concentration of tranilast (300 microM) suppressed the glycosaminoglycan synthesis and cell proliferation of keloid fibroblasts. Moreover, tranilast scarcely affected the fibronectin production. Triamcinolone (10 microM) also inhibited glycosaminoglycan synthesis and cell proliferation. These results suggest that the inhibitory effect of tranilast on the keloid tissues is related to its inhibition of the collagen synthesis of fibroblasts. Tranilast would be useful as a therapeutic drug for the treatment of keloids.

Animals↗
PubMed1992

[Effect of tranilast, an anti-allergic drug, on carrageenin-induced granulation and capillary permeability in rats].

We studied the effect of tranilast on the growth of carrageenin-induced granulation and the increase in capillary permeability induced by inflammatory agents in rats. In the carrageenin-induced granulation model, tranilast (50 or 100-200 mg/kg, p.o.) decreased significantly and dose-dependently the weight and the hydroxyproline content of the granulation tissue. Tranilast, however, showed no effect on the healing day of locally wounded dorsal skin of rats. Triamcinolone (10 mg/kg, p.o.) also showed an inhibitory effect on the carrageenin-induced granulation model. Tranilast (50-400 mg/kg, p.o.) dose-dependently inhibited the enhancement of capillary permeability induced by the Ca ionophore A23187, bradykinin and xanthine oxidase. Moreover, tranilast (30 and 300 microM) suppressed superoxide production induced by FMLP in human neutrophils, but did not act as a superoxide scavenger. Considering that hypertrophic scar and keloid are conditions characterized by abnormal cell proliferation and excessive collagen accumulation accompanied with itch and pain, these results suggest that tranilast is useful as a therapeutic drug for hypertrophic scars and keloids.

Adult↗
PubMed1992

Vitrification of bovine blastocysts obtained by in vitro culture of oocytes matured and fertilized in vitro.

Two experiments were conducted to assess the viability of bovine blastocysts obtained by in vitro fertilization of oocytes matured in vitro (IVM-IVF) and cryopreserved by vitrification. In Expt 1, the optimal concentrations of glycerol and 1,2-propanediol in the basic medium (modified TCM199) for cooling and warming without formation of ice crystals were determined by plunging the solution into liquid nitrogen and then warming it in a water bath at 15 degrees C; when both glycerol and 1,2-propanediol were present in the solution (> 45% v/v), vitrification of the medium was observed. In Expt 2, IVM-IVF blastocysts were equilibrated to the mixture of glycerol and 1,2-propanediol (0% to 45%) at 15 degrees C in a stepwise manner as follows: (i) in one step, for 18 min to the final vitrification solution; (ii) in two steps, for 8 min in the first step and 10 min in the second step; (iii) in four steps, for 4 min in the first three steps and 6 min in the last step; (iv) in eight steps, for 2 min in each step, but 4 min in the last step; and (v) in 16 steps, for 1 min in each step, but 3 min in the last step. After removal of cryoprotectants, the blastocysts were cultured for 24 h in vitro. The survival rates for the embryos equilibrated in 1, 2, 4, 8 and 16 step(s) were 56, 89, 100, 100 and 100%, respectively. The blastocysts equilibrated in 1, 2, 4, 8 and 16 steps were vitrified by plunging the straws containing them into liquid N2, thawed and cultured in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Inhibition by amiloride of ouabain-evoked catecholamine secretion from cultured adrenal chromaffin cells: evidence for its blocking action on interaction between ouabain and Na+/K(+)-pump.

The effect of amiloride on ouabain-evoked catecholamine secretion was investigated in primary cultures of bovine adrenal chromaffin cells. Catecholamine secretion evoked by ouabain was inhibited markedly by amiloride, but the secretion evoked by Na+ removal was not affected by the drug. In contrast, adriamycin, a putative inhibitor of the Na(+)-Ca++ exchange, inhibited the secretion evoked by Na+ removal as well as that evoked by ouabain. The inhibitory action of amiloride on the ouabain-evoked secretion was therefore considered to be due to its action on other mechanism(s) than the Na(+)-Ca++ exchange process. Further studies showed that the uptake of 86Rb+ into the cells was slightly but significantly reduced by amiloride, and the inhibitory action of ouabain on 86Rb+ uptake was considerably blocked by this drug under the experimental conditions in which the inhibition of ouabain-evoked secretion was observed. The binding of [3H] ouabain to the intact cells was also inhibited by amiloride under the same conditions. These results suggest that amiloride may inhibit ouabain-evoked catecholamine secretion as a consequence of blocking the inhibitory action of ouabain on the plasma membrane Na+/K(+)-pump in adrenal chromaffin cells.

Adrenal Medulla↗
PubMed1992

[Proposal of a new classification of adult bronchial asthma--child onset asthma, adult onset asthma and adult relapse asthma. Project Team for Research into Adult Bronchial Asthma in Japan].

The first nationwide research into adult bronchial asthma in Japan proposed a new classification of adult asthma. Adult asthma was categorized into child onset asthma, adult onset asthma and adult relapse asthma. The frequency of child onset asthma, adult onset asthma and adult relapse asthma in adult asthma was 11.2%, 77.3% and 3.7%, respectively. The frequency of child onset asthma decreased markedly in the older age group. On the other hand, the frequency of adult onset asthma increased, and reached more than 90%, in the older age group. The frequency of the following factors: atopic asthma, complications with other atopic diseases, mild asthma, male patients, experience of mechanical ventilation, visits to night clinics and oxygen therapy on acute attack, was significantly higher in the child onset asthma group than in the adult onset asthma group. The frequency of infectious type, aspirin intolerance, steroid dependent asthma, severe asthma and regular medication was significantly higher in the adult onset asthma group. Adult relapse asthma seemed to fall between these two groups. Based on the above observations, we proposed a new classification of adult asthma which includes child onset asthma, adult onset asthma and adult relapse asthma.

Asthma↗
PubMed1992

[Neurological manifestations in hemorrhagic colitis associated with Escherichia coli O 157: H 7].

From September through November 1990, an outbreak of hemorrhagic colitis associated with Escherichia coli O 157: H 7, occurred in a kindergarten in Saitama, Japan. Some of the patients suffered from neurological symptoms such as stupor, deep coma and/or convulsions in the acute stage, and/or action tremors, nystagmus, incontinence, phrenic nerve palsy in the later stage. Serum complements decreased more in the patients with neurological symptoms than in the patients without them. The verotoxin elaborated by E. coli O 157: H 7 was considered to cause the neurological symptoms, on the basis of their clinical courses and laboratory findings, especially the cerebrospinal fluid findings.

Child↗