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Biomedical subjects

S Shibata

Publications and source records attributed to S Shibata.

At least 487 records · Page 27Linked to original sources
PubMed1991

Immunological and virological characterization of improved construction of recombinant vaccinia virus expressing rinderpest virus hemagglutinin.

We constructed a recombinant vaccinia virus (RVV) expressing rinderpest virus (RPV) hemagglutinin (H) by modifying the promoter region of the original RVV. The promotor region was modified at three points, i.e., an outframe ATG was eliminated, the sequence between the promoter and initiation codon was shortened and the base sequence just upstream of the initiation codon was changed. As compared with the original RVV, the modified RVV was found to produce a remarkably large amount of H protein in infected rabbit kidney cells cultured in vitro and to induce high titers of anti-RPV-H antibodies in rabbits. The median protective doses in rabbits of the modified and of the original RVVs were 10(2) pfu and 10(3.5) pfu, respectively, indicating that the modified RVV was at least 10-times more effective in protection than the original. The neurovirulence of the modified RVV and the parental LC16mO strain was roughly at the same level, and was much lower than that of WR strain. The modified RVV was as heat-stable as the original one. These results indicate that the modified RVV could be a candidate rinderpest vaccine for further examinations including cattle.

Animals↗
PubMed1991

Detection of a heat-labile enterotoxin gene in enterotoxigenic Escherichia coli by densitometric evaluation using highly specific enzyme-linked oligonucleotide probes.

Two alkaline phosphatase-conjugated 24-mer oligonucleotide probes were developed to detect the heat-labile enterotoxin gene in enterotoxigenic Escherichia coli. Probes were antisense codon sequences, which are transcribed into mRNA, of the heat-labile enterotoxin gene of enterotoxigenic Escherichia coli of human origin. Using dot-blot hybridization, probes were tested with 100 clinical isolates and evaluated by a reflectance-type densitometer. Results agreed very well with those of an immunological test, the Biken test, and a 32P-labelled recombinant DNA probe. The oligonucleotide probes did not react with nucleic acids prepared from other diarrhoeagenic bacterial pathogens. Thus, the alkaline phosphatase-conjugated oligonucleotide probes seem to be highly sensitive and specific for detection of heat-labile enterotoxin-producing enterotoxigenic Escherichia coli. Moreover, the results indicate a potential usefulness for densitometric evaluation of DNA hybridization.

Alkaline Phosphatase↗
PubMed1991

Characterization of the vasoinhibitory actions of KT2-230, a new benzothiazepine vasodilator derivative on isolated rabbit vascular smooth muscles: an alpha-adrenergic- and serotonergic-receptor antagonist.

1. Pharmacological properties of KT2-230 (benzothiazepine derivative), a newly synthesized vasorelaxing agent, were studied. 2. In the anesthetized dogs, KT2-230 increased the femoral and vertebral blood flow without effect on systemic blood pressure. 3. In rabbit aorta, KT2-230, methysergide and phentolamine inhibited contractile responses to 5-hydroxytryptamine. 4. The response to norepinephrine was also inhibited by KT2-230 and phentolamine. Responses to histamine were not affected by KT2-230. 5. Responses to KCl and Ca2+ in K+ depolarized aorta in Ca2(+)-free medium were inhibited by a high concentration of KT2-230. 6. In rabbit iliac artery, KT2-230 inhibited the response to caffeine in Ca2(+)-free medium. 7. KT2-230 decreased total La3(+)-resistant Ca2(+)-binding at high affinity sites. 8. These results indicate that KT2-230 inhibits alpha 1-adrenoceptors and 5-HT-receptors and at high concentrations it inhibits slow Ca2(+)-channels. KT2-230 may inhibit the Ca2(+) release from caffeine- and agonist-sensitive Ca2+ stores.

Adrenergic alpha-Antagonists↗
PubMed1991

The mode of vasorelaxing action of melatonin in rabbit aorta.

1. The vasorelaxing effect of melatonin on the contractile response to 5-hydroxytryptamine (5-HT) was investigated in rabbit isolated aorta. 2. Melatonin (10(-5)-10(-3) M) caused relaxation of the 5-HT (10 M) response in a concentration-dependent manner. Nifedipine (10(-6) M) did not affect the relaxing action of melatonin. 3. Pretreatment with methylene blue (10(-5) M) or nitroglycerin (3 x 10(-8) M) inhibited or potentiated, respectively, the relaxing action of melatonin. 4. Pretreatment with melatonin (10(-3) M) or M&B 22.948 (10(-3) M) potentiated the relaxing effect of nitroglycerin (10(-9)-10(-5) M) on the contraction induced by PGF2 alpha (4 x 10(-6) M). The effect of a combined treatment with melatonin and M&B 22.948 was not significantly different from that of a single treatment with M&B 22.948. 5. Melatonin (10(-5)-10(-3) M) inhibited the activity of cGMP-phosphodiesterase, in a concentration-dependent manner. 6. These results suggest that the vasorelaxing action of melatonin may be due to an increase in the level of cGMP.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1991

Vasorelaxing action of melatonin in rat isolated aorta; possible endothelium dependent relaxation.

1. Melatonin (10(-4)-10(-3) M) inhibited contractile response to 5-hydroxytryptamine (5-HT) and KCl in rat isolated aorta. 2. In the presence of verapamil but not nifedipine, melatonin failed to inhibit residual response to KCl. 3. In the aorta precontracted with 5-HT, PGF2 alpha, or KCl, melatonin (10(-6)-10(3) M) caused relaxation. Removal of endothelium only inhibited the melatonin relaxation on the 5-HT response. Methylene blue also inhibited the melatonin relaxation. 4. Nifedipine and verapamil partly inhibited the melatonin relaxation on the 5-HT response. In the absence of endothelium, verapamil but not nifedipine further inhibited the melatonin relaxation. 5. M & B 22,948 inhibited the melatonin relaxation. Melatonin potentiated the nitroglycerin relaxation. In the absence of endothelium, nitroglycerin and melatonin potentiated the relaxation by melatonin and nitroglycerin, respectively. 6. These results suggest that the mode of inhibitory action of melatonin is somewhat similar to that of verapamil. In addition, the vasorelaxing effect of melatonin on the 5-HT response is endothelium dependent and also may be related to the inhibition of cGMP metabolism.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1991

Aicardi syndrome accompanied by auditory disturbance and multiple brain tumors.

We described a 5-month-old girl with Aicardi syndrome accompanied by auditory disturbance and multiple brain tumors. She was admitted to our hospital because she suffered from intractable flexor spasms. Physical examination revealed craniofacial asymmetry, left auricular deformity, scoliosis, and remarkable hypotonia with psychomotor retardation. Abnormal ophthalmological findings included chorioretinopathy with pale and round-shaped peripapillary lacunae, and there was modified hypsarrhythmia in her EEG. MRI revealed multiple brain tumors in the 3rd and the lateral ventricles which are considered to be choroid plexus papilloma with agenesis of the corpus callosum. ACTH therapy was administered because of the intractable seizures. After ACTH therapy, the thresholds of waves I and V were much improved. The interpeak latency of waves I-V of the left ear and the peak latency of wave I of the right ear had been lengthened. Acoustic reflex with contralateral stimulation showed no response in the left ear. These findings indicate that the auditory system is also involved in the Aicardi syndrome and that ACTH is effective for its dysfunction.

Acoustic Impedance Tests↗
PubMed1991

Heterogeneity of immune complex-derived anti-DNA antibodies associated with lupus nephritis.

The mechanisms responsible for the tissue injuries associated with lupus nephritis have not yet been well explained. We have investigated the characteristics of anti-DNA antibodies in circulating immune complexes (CIC) and in the deposits of renal glomeruli in patients with active lupus nephritis. The CIC-derived antibodies expressed anti-DNA idiotypes (Id) designated as 0-81 Id and NE-1 Id, and bound mainly to single-stranded DNA but never to glomerular basement membrane (GBM) antigens. On the other hand, the immunoglobulins (Ig) eluted from renal glomeruli of lupus patients reacted not only with DNA but also with GBM, proteoglycan, and heparan sulfate. The binding of glomeruli-deposited Ig was markedly low when GBM antigens were used after treatment with heparitinase, suggesting that some anti-DNA antibodies may bind directly to GBM antigens associated with heparan sulfate, and form in situ IC in renal glomeruli. It was also revealed that the renal eluates obtained after passing through GBM antigen-coupled Sepharose lost the binding ability with GBM but still retained DNA-binding and 0-81 Id activity, showing the participation of circulating IC-derived anti-DNA antibodies in the glomerular deposits. Theoretically there may be two mechanisms in the pathogenesis of lupus nephritis through the deposition of circulating IC and through in situ formation of anti-DNA IC in renal glomeruli. The diversity of histological features in lupus kidneys may be attributed to the heterogeneity of the mechanisms.

Antibodies, Antinuclear↗
PubMed1991

Inhibitory effects of licochalcone A isolated from Glycyrrhiza inflata root on inflammatory ear edema and tumour promotion in mice.

Licochalcone A, 3-a,a-dimethylallyl-4,4'-dihydroxy-6-methoxychalcone, from the root of Glycyrrhiza inflata Beta (Leguminosae) (Xin-jiang liquorice) showed anti-inflammatory action towards mouse ear edema induced by arachidonic acid (AA) and 12-O-tetradecanoylphorbol 13-acetate (TPA) by topical application. Anti-tumour promoting action of licochalcone A was also observed in vivo for mouse skin papilloma initiated by dimethylbenz[a]anthracene (DMBA) and promoted by TPA. It inhibited in vitro 32Pi-incorporation to phospholipids in HeLa cells promoted by TPA. A competitive interaction of licochalcone A with the TPA-receptors in the cell membrane has been suggested.

Animals↗
PubMed1991

Characteristics of the vasorelaxing action of (3E)-4-ethyl-2-hydroximino-5-nitro-3-hexamide FK409, a new vasodilator isolated from microbial sources, in isolated rabbit arteries.

We examined the vasoinhibitory effect of (3E)-4-ethyl-2-hydroximino-5-nitro-3-hexamide FK409, a new vasodilator, on contractile responses in isolated rabbit arteries. FK409 (10(-8)-10(-5) M) inhibited contractile responses to norepinephrine (NE), histamine (His), and 5-hydroxytryptamine (5-HT) in rabbit aorta. The pattern of inhibition by FK409 was not competitive. The inhibitory effect of FK409 on the 5-HT response was much greater than that of nitroglycerin (NG). A high concentration of FK409 (10(-5) M) was necessary to inhibit the response to KCl (10-70 mM). The effect of combined treatment with FK409 (10(-5) M) and a subthreshold concentration of nifedipine (10(-9) M) on the KCl response was much greater than a single treatment with either agent. In addition, 3 x 10(-6) M D600, but not FK409 (10(-6) or 10(-5) M), inhibited the increase in the rate of 45Ca influx stimulated by a 40-mM KCl substituted solution. In a Ca2(+)-free medium containing EGTA and nifedipine, FK409 (10(-9)-10(-5) M) inhibited phasic responses to NE, His, and 5-HT, and subsequent sustained responses owing to addition of Ca2+. The response to caffeine in rabbit iliac arteries incubated in Ca2(+)-free medium was also inhibited by FK409 (10(-6) and 10(-5) M). In rabbit aorta precontracted with NE (10(-5) M) and partially inhibited by prior exposure to NG (10(-5) M), the relaxing effect of FK409 was slightly attenuated. Pretreatment of tissues with FK409 (10(-6) M) inhibited the relaxing action of NG much more than prior NG inhibited the relaxing action of FK409. Methylene blue (10(-5) M), but not hemoglobin (10(-6) M), inhibited the relaxing action of FK409, whereas M&B 22,948 (3 x 10(-4) M) potentiated it. FK409 caused a relaxation of precontracted aorta without endothelium that was inhibited by methylene blue. In rabbit aorta precontracted with NE, FK409 (10(-6) M) increased cyclic GMP but not cyclic AMP content. FK409 (10(-5) M) had no effect on the NE-mediated increase in tissue inositol monophosphate (IP). These results suggest that FK409 inhibits the responses attributed to both intracellular Ca2+ release and Ca2+ influx through receptor-operated channels. The inhibitory effect of FK409 on both the KCl contractile response and KCl-stimulated 45Ca influx appears to be different from that of nifedipine or D600. Furthermore, the inhibitory action of FK409 may be partially mediated by cyclic GMP.

Animals↗
PubMed1991

Sensitive detection of viral antigens with a new method, "laser magnet immunoassay".

A new method, "laser magnet immunoassay" (LMIA), has been developed for sensitive detection of viral antigens. Target viruses captured on microbeads were made to react with antibodies labeled with magnetite particles. In a magnetic field, magnetically labeled antigens dispersed in water were attracted to and concentrated at one point on the surface, resulting in the lifting up of a small surface area. A laser beam which was incident on the point reflected, making an interference fringe. The intensity of the fringe indicates the amount of the magnetite conjugated with antigen. A very low concentration of antigens, such as 5 particles of influenza virus and 0.1 pg/ml of human immunodeficiency virus (HIV) p24 antigen in human serum, could be detected by this method. Application of this method to diagnoses of viral diseases in early stages is discussed.

Antigens, Viral↗
PubMed1991

Positive inotropic action of veratridine in rat atria: possible involvement of prostanoids.

Veratridine caused a positive inotropic action in the electrically driven left atria of rats. Quinacrine (a phospholipase A2 inhibitor), indomethacin (a cyclooxygenase inhibitor) and aspirin (a cyclooxygenase inhibitor), but not nordihydroguaiaretic acid (a lipoxygenase inhibitor), inhibited the response to veratridine. Verapamil and nifedipine also inhibited the response to veratridine. The positive inotropic effect of arachidonic acid was abolished by aspirin and indomethacin. However, the positive inotropic effect of PGF2 alpha was not affected by indomethacin, quinacrine or aspirin. PGE2, but not STA2 and PGI2, also caused the positive inotropic effect. However, the negative inotropic effect was observed in the presence of PGE1 and PGD2. Veratridine shifted the concentration-response curve of Ca2+ to the left in a Ca(2+)-free medium. Indomethacin only inhibited the veratridine-induced potentiation of Ca2+ responses. Veratridine increased the level of PGF2 alpha in the left atria and this action was completely inhibited by indomethacin, aspirin and quinacrine. Veratridine also increased the level of PGE2. These results imply that the positive inotropic action of veratridine is partly due to stimulation of the release of arachidonic acid leading to the increase in prostaglandins in rat atria.

Animals↗
PubMed1991

Antiviral activities of glycyrrhizin and its modified compounds against human immunodeficiency virus type 1 (HIV-1) and herpes simplex virus type 1 (HSV-1) in vitro.

Chemically modified compounds of glycyrrhizin have been synthesized and evaluated for their inhibitory effect on the replication of human immunodeficiency virus type 1 (HIV-1) and herpes simplex virus type 1 (HSV-1). Among them, the 11-deoxo compound having a heteroannular diene structure at the C and D rings proved as active against HIV-1 as glycyrrhizin in MT-4 and MOLT-4 cells. It completely inhibited HIV-1-induced cytopathogenicity in both cell lines at a concentration of 0.16 mM. The compound was also effective against HSV-1 with a 50% inhibitory concentration of 0.5 mM [corrected].

Antiviral Agents↗
PubMed1991

[Brain neuronal mechanisms of circadian rhythms in mammalians].

It is now widely accepted that the suprachiasmatic nucleus (SCN) of the hypothalamus is a circadian pacemaker in the mammalians. This conclusion is based on three principal lines of the following evidence. First, ablation of the SCN results in a loss of circadian rhythms in rodents. Second, the SCN exhibits rhythms in neuronal activity and glucose metabolism both in vivo and in vitro experiments. Third, the transplantation of fetal SCN to the third ventricle of animals rendered arrhythmic++ by SCN ablation restores circadian function. In this review the anatomical, physiological and pharmacological characteristics of SCN neurons in vitro are discussed by focusing especially upon the roles of various neurotransmitters and modulators in the circadian system of mammals, in relation to the function of SCN.

Action Potentials↗
PubMed1991

[Behavioral pharmacological and electroencephalographic effects of the 5-HT1A partial agonist ipsapirone].

The behavioral and EEG effects of the 5-HT1A partial agonist ipsapirone were investigated to determine its pharmacological characteristics as an anxiolytic drug in rats, mice and rabbits, as compared with those of buspirone and diazepam. 1) The anticonflict effect of ipsapirone was almost equipotent as that of buspirone and less potent than that of diazepam in rats. Ro15-1788 antagonized the anticonflict effect of diazepam, but did not that of ipsapirone. 2) Muricide in midbrain raphe-lesioned and olfactory bulbectomized rats was inhibited by ipsapirone. However, the inhibition of muricide by ipsapirone was attenuated by its repeated administration. 3) The muscle relaxant effects of ipsapirone and buspirone on rotarod performance were less potent than that of diazepam. Ethanol-induced muscle relaxation was markedly potentiated by diazepam, but less potently by ipsapirone and buspirone. 4) The pentetrazol-induced convulsion was dose-dependently antagonized by diazepam, while it was weakly potentiated by ipsapirone and buspirone. 5) The limbic afterdischarges induced by either hippocampal or amygdaloid stimulation in rabbits were markedly inhibited by diazepam. Conversely, ipsapirone and buspirone slightly potentiated afterdischarges. In conclusion, it is suggested that ipsapirone has anxiolytic activities similar to that of buspirone and moderate antimuricidal action. In addition, ipsapirone, like buspirone, is also characterized by its less potent muscle relaxant, alcohol-potentiating and anticonvulsant actions.

Animals↗
PubMed1991

Subarachnoid and intracerebral hemorrhage associated with necrotizing angiitis due to methamphetamine abuse--an autopsy case.

The authors report an autopsy case of methamphetamine-related intracranial hemorrhage and vasculitis. A 22-year-old female was comatose after an intravenous injection of an unknown dose of methamphetamine. Computed tomographic scans demonstrated massive subarachnoid hemorrhage and hematoma in the corpus callosum. Cerebral angiography revealed nonfilling of bilateral intracranial carotid arteries and extravasation of contrast medium from the right pericallosal artery which was visualized retrogradely via the vertebral artery. Postmortem studies found cerebral edema, subarachnoid, intraventricular, and intracerebral hemorrhage, and intracranial vasculitis, but no aneurysm or arteriovenous malformation. Necrosis of vessel walls with destruction of the smooth muscle layer, but no leukocytotic infiltration of the vessel walls were observed in all major cerebral arteries. The hemorrhage probably resulted from medial necrosis in the large intracerebral vessels, and a sudden drug-induced rise in blood pressure.

Adult↗
PubMed1991

Imprints of the tectorial membrane following acoustic overstimulation and kanamycin treatment.

Normal imprints in guinea pigs were examined mainly using a scanning electron microscope (SEM). Morphological changes in imprints after loading of the conditions mentioned below were also investigated. Imprints observed on the normal tectorial membrane were composed of small concavities lined on a W-shaped line and the W-type was of a V-type in proportion to ascend to the upper turn. The imprints occurred at the rate of one for every outer hair cell and in 3-4 lines corresponding to the outer hair cell hairs. With exposure to a high intensity of sound, small concavities of the imprints were deformed and remnant sensory hairs were observed, sporadically. Another line of new imprints was sometimes evident in the lower turn of the cochlea, in addition to the original imprints. In case of inner ear disturbances due to kanamycin (KM) loading, the imprints were little deformed, but the remnant sensory hairs were numerous and their time-course revealed a gradual decrease and the disposal required a longer time than seen in the degenerated cell fractions on the reticular membrane. With exposure to high intensity sound after KM loading, KM-type changes or high intensity sound-type changes were observed and depended on severity of the KM-induced disturbance. The imprints existed for a considerably long time even when the lower region sensory cells degenerated or disappeared in the presence of various conditions.

Animals↗
PubMed1991

Ultrastructural observation on matrix fibers in the condylar cartilage of the adult rat mandible.

In this study, ultrastructural and immunohistochemical studies were performed on the adult rat (15 weeks old) mandibular condyle, with particular attention to the matrix fibers in the condylar cartilage. The fibrous zone had thick collagen fibrils which formed fibril bundles. These collagen fibrils consisted mainly of Type I collagen. From the proliferative zone to the mature zone, the density of the collagen fibrils became higher. In the hypertrophic zone, thick collagen fibrils were formed around the chondrocytes. Immunohistochemical study indicated that these collagen fibrils consisted mainly of Type I collagen. Therefore, it was confirmed that the hypertrophic chondrocytes in this tissue had one of the osteoblastic phenotypes.

Animals↗