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Biomedical subjects

S Shibata

Publications and source records attributed to S Shibata.

At least 307 records · Page 17Linked to original sources

A histological study of the developing condylar cartilage of the fetal mouse mandible using coronal sections.

The first indication of cartilage formation was detected on day 14.5 of pregnancy in close connection to the ossifying mandible. A separated blastema was never observed. Thus the findings support the concept that the condylar cartilage develops from already differentiated cells, not from primary undifferentiated mesenchymal cells. Moreover, endochondral bone formation started on day 16 of pregnancy. Although the condylar cartilage basically undergoes the same processes of endochondral bone formation as the long bone, many hypertrophic chondrocytes may survive and are released into the primary spongiosa.

Animals↗

Vasoinhibitory effect of leminoprazole, a H+,K(+)-ATPase inhibitor, on rat aortic rings.

1. In isolated rat aortic rings, leminoprazole (2-[2-N-methyl-N-(2-methylpropyl)amino]benzylsulfinyl benzimidazole) (10(-6) - 10(-4) M) inhibited contractile responses to phenylephrine (PE), KCl and Ca2+ in KCl-depolarized tissues in a Ca2+ free medium. Leminoprazole also relaxed the aorta contracted by PE and KCl. 2. The relaxing effect of leminoprazole was markedly inhibited by nifedipine and verapamil (inhibitors of voltage operated Ca2+ channels). Relaxation induced by verapamil, but not by nifedipine, was inhibited by pre-treatment by leminoprazole. 3. The relaxing effect of leminoprazole was also inhibited by NG-monomethyl-L-arginine (a nitric oxide synthase inhibitor), methylene blue (a guanylate cyclase inhibitor) or endothelium removal but not by indomethacin (a cyclooxygenase inhibitor), glyburide (a KATP channel inhibitor) or iberiotoxin (a KCa channel inhibitor). 4. Zaprinast (a cGMP-phosphodiesterase inhibitor) also inhibited the relaxing action of leminoprazole. In addition, relaxation induced by nitroglycerin was potentiated by leminoprazole. 5. Further, in the presence of methylene blue, residual relaxation induced by leminoprazole was still potentiated by verapamil. 6. These results suggest that the vasoinhibitory effect of leminoprazole in rat aortic rings is due to the increased level of cGMP through inhibition of cGMP-phosphodiesterase and also due to inhibition of voltage operated Ca2+ channels.

Animals↗

The potentiation of nitroglycerin-induced relaxation by PKG inhibition in rat aortic rings.

1. In rat aortic rings precontracted by phenylephrine, H7 (10(-5)M) and staurosporine (10(-7)M), which inhibit PKA, PKG and PKC, and H-89 (10(-6)M), which inhibits PKA and PKG, potentiated relaxations induced by nitroglycerin. Forskolin-induced relaxations were not affected by H7 (10(-5)M). 2. Nitroglycerin-induced relaxations were not affected by calphostin-C (10(-7)M), which inhibits PKC, H-89 (10(-7)M), which inhibits PKA, and staurosporine (2 x 10(-9)M), which inhibits PKC. 3. Iberiotoxin (3 x 10(-8)M), an inhibitor of large conductance Kca channels, partly inhibited the relaxation induced by nitroglycerin and completely inhibited the potentiating effect of H7 on nitroglycerin-induced relaxations. 4. The potentiating effect of zaprinast (10(-5)M), an inhibitor of cGMP-phosphodiesterase, on nitroglycerin-induced relaxation was not affected by iberiotoxin. In the presence of methylene blue (10(-5)M), an inhibitor of guanylate cyclase, the residual relaxing response to nitroglycerin was not affected by H7, but it was inhibited by iberiotoxin. 5. These results suggest that the potentiation of nitroglycerin-induced relaxation by H7, staurosporine and H-89 may be due to inhibition of PKG.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

Methamphetamine modifies the photic entraining responses in the rodent suprachiasmatic nucleus via serotonin release.

We examined whether methamphetamine modifies the photic entraining responses in the rat suprachiasmatic nucleus. Optic nerve stimulation increased vasoactive intestinal polypeptide release from rat suprachiasmatic nucleus slices, and methamphetamine inhibited this increase in a concentration-dependent manner. Optic nerve stimulation has been reported to evoke field potentials in rat suprachiasmatic nucleus slices. Methamphetamine attenuated this field potential, and maximal inhibition (75.5%) was achieved at a concentration of 100 microM. Systemic administration of methamphetamine (1-5 mg/kg) inhibited light (300 lux, 1h)-induced Fos expression in the suprachiasmatic nucleus; methamphetamine at a dose of 5 mg/kg, i.p. caused 40% inhibition of light-induced Fos expression. We examined whether the inhibitory effect of methamphetamine on photic entraining responses mediates serotonin release from the suprachiasmatic nucleus. High-performance liquid chromatographic analysis revealed that methamphetamine application increased serotonin release from rat suprachiasmatic nucleus slices in a concentration-dependent manner, but did not affect noradrenaline release. In addition, reduction of serotonin content attenuated the effect of methamphetamine on field potential induced by optic nerve stimulation in vitro and also light-induced phase advances of wheel running activity rhythm in vivo. The present results support the idea that methamphetamine produces an inhibitory effect on photic entrainment in the suprachiasmatic nucleus via serotonin release.

Animals↗

Positron-labeled antioxidant 6-deoxy-6-[18F]fluoro-L-ascorbic acid: increased uptake in transient global ischemic rat brain.

The in vivo uptake and distribution of 6-deoxy-6-[18F]fluoro-L-ascorbic acid (18F-DFA) were investigated in rat brains following postischemic reperfusion. Global cerebral ischemia was induced in male Wistar rats for 20 min by occlusion of four major arteries. Two time points were chosen for 18F-DFA injection to rats subjected to cerebral ischemia, at the start of recirculation and 5 days following recirculation. The rats were then killed at 2 h after tail-vein administration of 18F-DFA and tissue radioactivity concentration was determined. Increased uptake of radioactivity in particular brain regions, including the cerebral cortex, hypothalamus, and amygdala following injection of 18F-DFA, compared to the sham-operated control, was observed 5 days after reperfusion. Similar results were also obtained in in vitro experiments using brain slices. Abnormal in vivo accumulation of 45Ca, a marker of regional postischemic injury, was observed in these brain regions in tissue dissection experiments. Furthermore, metabolite analysis of nonradioactive DFA using 19F-NMR showed that DFA remained intact in the postischemic reperfusion brain. The present results indicate that 18F-DFA increasingly accumulates in damaged regions of postischemic reperfusion brain.

Animals↗

Narrow photon beam dosimetry for linear accelerator radiosurgery.

The dosimetric characteristics of linear accelerator radiosurgery for 10-MV X-ray were measured. Measurement of the relative output factor and tissue maximum ratio with a microchamber produced results equivalent to those of measurement with X-ray film. The 80% isodose level width measured with the microchamber was significantly smaller than that measured with the X-ray film. For the measurement of relative output factor and tissue maximum ratio, a microchamber seems to be the more appropriate choice. X-Ray film was found to be suitable for beam profile measurement.

Phantoms, Imaging↗

PC-2, linear homoglucan with alpha-linkages, peripherally enhances the hippocampal long-term potentiation.

PURPOSE: To investigate central effectiveness of PC-2, a glucan from lichen Parmelia caperata with alpha(1-3)(1-4) linkages in the ratio 3:2, with regard to the long-term potentiation (LTP) of evoked potential. METHODS: The extent of LTP, induced by high-frequency stimulation of medial perforant pathway, was evaluated as fractional increase in population spike amplitude in dentate gyrus in anesthetized rats. RESULTS: Oral and intravenous application of PC-2 resulted in significant enhancement of LTP elicited by a weak, but not by a strong, tetanic stimulation. No influence of PC-2 on basal evoked synaptic potential was found. Bilateral adrenalectomy profoundly suppressed the positive impact of the glucan on the formation of LTP, but showed no effect upon the magnitude and time-course of population spike enhancement in vehicle-treated subjects. Two related alpha-glucans with different chemical structures did not show any effect comparable to that of PC-2. CONCLUSIONS: Peripheral application of PC-2 significantly enhances LTP in dentate gyrus in rats. Results indicate that the effect of PC-2 might be peripherally mediated and that the specific higher structure of PC-2 is crucial for its biological activity.

Adrenalectomy↗

Localization of HIV-1 in human thymic implant in SCID-hu mice after intravenous inoculation.

Human immunodeficiency virus type 1 (HIV-1) was immunohistochemically and ultrastructurally localized in human thymus implants in SCID-hu mice 3 weeks after intravenous (i.v.) inoculation of the virus. A viral antigen (gp120) was predominantly distributed in and around the epithelial cells in Hassall's corpuscles as demonstrated by fluorescence immunohistochemistry. Occasional solitary round cells positive for the viral antigen but negative for cytokeratin were detected in the perivascular areas. Ultrastructural examinations clearly revealed a number of mature viral particles in the intercellular spaces of the Hassall's corpuscles. Thus the present study indicates the possibility that thymic epithelial cells in Hassall's corpuscles act as a target and/or reservoir in an early stage of HIV infection.

Animals↗

Characterization and biological significance of sialyl alpha 2-3galactosyl beta 1-4xylosyl beta 1-(4-methylumbelliferone) synthesized in cultured human skin fibroblasts.

Human skin fibroblasts were incubated in the presence of a fluorogenic xyloside, 4-methyl-umbelliferyl-beta-D-xyloside (Xyl-MU), then the cultured medium was recovered, concentrated with a lyophilizer, and dialyzed against distilled water. The structures of the Xyl-MU derivatives purified from the dialyzable fraction were investigated. In addition to established glycosaminoglycans-MU (GAGs-MU), Gal-Gal-Xyl-MU, Gal-Xyl-MU, sulphate-GlcA-Xyl-MU, GlcA-Xyl-MU, and Xyl-Xyl-MU, which were induced by Xyl-MU, an oligosaccharide having fluorescence was purified using a combination of gel filtration, ion-exchange chromatography and high-performance liquid chromatography, then subjected to carbohydrate composition analysis, enzyme digestion, Smith degradation, 1H-NMR, and ion-spray mass spectrometric analysis. From the data obtained, the oligosaccharide was considered to have the structure SA alpha 2-3Gal beta 1-4Xyl beta 1-MU. The amount of MU-oligosaccharide in the cell culture increased with time and was dependent on the amount of Xyl-MU added. Its production was also different from that of Gal-Gal-Xyl-MU and Gal-Xyl-MU, which are biosynthetic intermediates of GAG-MU. Addition of CDP, an inhibitor of sialytransferase, to the cell culture medium increased the secretion of GAG-MU. These results suggest that SA-Gal-Xyl-MU production may be related to the regulation of GAG-MU biosynthesis.

Carbohydrate Sequence↗

Impaired antigen specific responses and enhanced polyclonal stimulation in mice infected with Ehrlichia muris.

The immune status of BALB/c mice infected by intraperitoneal inoculation with Ehrlichia muris was examined. The level of E. muris infection in both peritoneal cavity and spleen was greatest at day 10 postinoculation (PI). Thereafter, the infection level was dramatically reduced while the organism persisted for up to 400 days PI. The greatest intraperitoneal infiltration of leukocytes, splenomegaly, and leukocytosis were observed on days 10, 15, and 20 PI, respectively. Infected mice developed marked hypergammaglobulinemia of IgG and IgM that peaked at day 20 PI; however, IgA plummeted at day 15 PI. Of IgG, G2a and G3 increased while G1 and G2b remained constant. Despite hypergammaglobulinemia, both IgG and IgM antibody titers against E. muris were very low throughout the 30-day study. Antibody development and plaque-forming cells against sheep red blood cells (SRBC) were abolished when the antigen was inoculated on day 10 PI. IgM antibody development against SRBC was more severely inhibited than IgG antibody development. However, when mice were immunized with SRBC prior to E. muris infection, antibody development against SRBC was not reduced. Delayed type hypersensitivity reaction to dinitrofluorobenzene was also maximally inhibited when the antigen was administered on day 10 PI. The IFN-gamma level in the blood was maximal at day 10 PI. These results indicate that although the vigorous polyclonal activation and protective IFN-gamma responses occurred by day 10 PI- which cleared most of the ehrlichial infection-antigen-specific immune stimulation was impaired primarily at the level of antigen-priming at peak parasitemia.

Animals↗

The inhibitory effects of iberiotoxin and 4-aminopyridine on the relaxation induced by beta 1- and beta 2-adrenoceptor activation in rat aortic rings.

1. In rat aortic rings contracted by phenylephrine, the relaxation induced by isoprenaline was partly inhibited by iberiotoxin, (ibTX), tetraethylammonium, 4-aminopyridine (4-AP) and 1,9-dideoxyforskolin, but not by glibenclamide. 2. In the presence of 4-AP, 1,9-dideoxyforskolin failed to inhibit further the relaxant response to isoprenaline. Cromakalim-induced relaxation was inhibited by glibenclamide. 3. In the absence of endothelium, ibTX and 4-AP still inhibited the relaxant response to isoprenaline. 4. The inhibitory effect of ibTX on the relaxant response to isoprenaline was eliminated by pretreatment with ICI-118,551, a beta 2-adrenoceptor antagonist, but not by atenolol, a beta 1-adrenoceptor antagonist. 5. The inhibitory effect of 4-AP on the relaxation induced by isoprenaline was abolished by atenolol, but not by ICI-118,551. 6. The inhibitory effect of ibTX on the isoprenaline-induced relaxation in the presence of atenolol was completely abolished by MDL 12,330A, an adenylate cyclase inhibitor. Further, the inhibitory effect of 4-AP on the isoprenaline-induced relaxation in the presence of ICI-118,551 was markedly reduced by MDL 12,330A. 7. The relaxation induced by dibutyryl cyclic AMP was partly inhibited by 4-AP but not by ibTX. However, in the presence of KT5720, an inhibitor of cyclic AMP-dependent protein kinase, ibTX failed to inhibit further the relaxation induced by isoprenaline. 8. These results suggest that, in rat aortic rings, KCa channels are involved in the relaxation induced by isoprenaline. In addition, KCa channels are mainly activated by beta 2-adrenoceptors through cyclic AMP-dependent pathways. Further, the inhibition of isoprenaline-relaxation by 4-AP may be related to the activation of beta 1-adrenoceptors and cyclic AMP formation.

4-Aminopyridine↗

Use of an alkaline phosphatase-conjugated oligonucleotide probe for the gene encoding the bundle-forming pilus of enteropathogenic Escherichia coli.

An alkaline phosphatase-conjugated 29-base oligonucleotide probe was developed to detect the gene encoding the bundle-forming pilus of enteropathogenic Escherichia coli. The sensitivity and specificity of the probe versus the results of localized adherence in the HEp-2 cell assay and fluorescent actin staining assay positivity were 95.7 and 100%, respectively.

Alkaline Phosphatase↗

Renal glomerular fibrosis in a cat.

Renal glomerular fibrosis was observed in a 1-year-old spayed female Japanese domestic cat that showed clinically advanced renal failure. In the glomeruli, increased homogeneous materials were stained strongly with aniline blue by Masson's trichrome and positive for anti-type III collagen antibody by immunohistochemical staining, causing mesangial sclerosis and capillary collapse. By electron microscopy, randomly arranged fibrils were observed in the expanded subendothelial and mesangial areas, and the fibrils showed periodicity characteristic of collagen fibers in longitudinal sections. These findings of glomerular lesions closely resemble those of human "collagenofibrotic glomerulonephropathy," which has recently been described as a new type of glomerulonephropathy.

Animals↗

Treatment of germ cell cancer with two cycles of high-dose ifosfamide, carboplatin, and etoposide with autologous stem-cell support.

PURPOSE: To evaluate the activity of two cycles of high-dose ifosfamide, carboplatin, and etoposide (ICE) with autologous hematopoietic progenitor cell support (aHPCS) in patients with poor-prognosis, chemotherapeutically sensitive germ cell cancer. PATIENTS AND METHODS: Twenty patients with germ cell tumor who had persistent disease or relapse from standard-risk or high-risk presentation were entered on this pilot study. The entry criteria included relapsed gonadal and extragonadal germ cell cancer unlikely to be cured by standard salvage therapy but without proven refractoriness to chemotherapy. Treatment consisted of two cycles of ICE chemotherapy with mesna uroprotection and aHPCS. On the first cycle, ifosfamide (IFX), 2 gm/m2; carboplatin, 400 mg/m2; and etoposide, 20 mg/kg, were administered on days -6, -5, and -4. On the second cycle, the doses and schedule of carboplatin and etoposide were identical, and patients with normal renal function received additional IFX, 2 g/m2 on day -3 and 1 g/ m2 on day -2. Mesna, 600 mg/m2 every 6 hours, was given until 24 hours following the final dose of IFX on each cycle, and autologous bone marrow and/or peripheral stem-cells were infused on day 0. RESULTS: All twenty patients are assessable for toxicity and current disease status. Two patients received only one cycle of therapy, one because of the development of active hepatitis C following cycle 1, and one because of renal insufficiency. No patient died as a result of protocol therapy, and no patient developed debilitating peripheral neuropathy, symptomatic hearing loss, or severe renal insufficiency requiring dialysis. The median time to recovery of > or = 500 neutrophils/microL and platelets > or = 50,000/microL was day +11 and day +15, respectively. The median maximum creatinine was 1.6 mg/dL on each treatment cycle, and there was no other significant organ toxicity. With a median follow-up of 45 months, nine patients are alive and disease-free following protocol chemotherapy. One patient with embryonal cancer developed progressive pulmonary metastases 3 months after completing high-dose therapy, underwent complete resection of lung metastases, and remains disease-free at 63+ months. Eight patients are continuously disease free at 23+ to 70+ months after protocol therapy. Eleven patients died of progressive disease between 4 and 23 months following completion of treatment. CONCLUSION: These results compare favorably to other studies in similarly selected patients undergoing salvage therapy with one or two cycles of chemotherapy containing high-dose carboplatin and etoposide with or without cyclophosphamide (CTX) or IFX. The excellent safety and tolerability profile of this regimen and its encouraging activity in poor-prognosis patients make it worthy of further study as part of initial therapy in randomized protocols for high-risk disease and early in the treatment of relapsed germ cell cancer.

Adult↗

Inhibitory effect of glycyrrhetinic acid derivatives on capsaicin-induced ear edema in mice.

We examined the effect of glycyrrhetinic acid (Ia) and its derivatives on ear edema induced by topical application of capsaicin in mice. Three dihemiphthalate compounds: di-sodium salt of 18 beta-olean-12-ene-3 beta,30-diol (deoxoglycyrrhetol, IIa) di-O-hemiphthalate (IIb); 18 beta-olean-9(11),12-diene-3 beta, 30-diol di-O-hemiphthalate (IIIa); and olean-11,13(18)-diene-3 beta,30-diol di-O-hemiphthalate (IVa) inhibited capsaicin-induced edema with ED50 values of 52.6, 41.0 and 51.8 mg/kg (p.o.), respectively. However, glycyrrhetinic acid and deoxoglycyrrhetol at a dose of 200 mg/kg (p.o.) had no effect. Compound IIIa (100 mg/kg, p.o.) also inhibited the edema response to capsaicin in mast cell-deficient mice. Furthermore, compounds IIb, IIIa and IVa (25-100 mg/kg, p.o.) prevented ear edema in response to intradermal injection of substance P (SP) and compound 48/80. In addition, these compounds at a high dose of 100 mg/kg (p.o.) produced a significant inhibition of the plasma extravasation in ear skin induced by i.v. administration of SP. The above results suggest that the effect of these compounds on capsaicin-induced ear edema is due at least in part to an inhibition of the increase of vascular permeability induced by vasoactive agents released from mast cells. Moreover, it seems likely that these compounds at a high dose can suppress vasodilatation and plasma extravasation induced by SP involved in capsaicin-induced edema.

Administration, Topical↗

Role of CD4+ and CD8+ T cells in mouse hepatitis virus infection in mice.

Viral growth and histopathological changes in the liver after intraperitoneal infection with mouse hepatitis virus, strain JHM were compared among normal C57BL/6 mice, those depleted of CD4+ T cells, CD8+ T cells and both T cell subsets. Viral growth in mice depleted of CD4+ T cells increased slightly, but pathological changes resembled those in normal mice. In contrast, the hepatitis was exacerbated in mice depleted of CD8+ T cells and those depleted of both T cell subsets. These results suggest that CD8+ T cells play a key role although both T cell subsets are involved in protection against mouse hepatitis virus infection in mice.

Animals↗

NG-nitro-L-arginine methyl ester attenuates the maintenance and expression of methamphetamine-induced behavioral sensitization and enhancement of striatal dopamine release.

We examined the roles of nitric oxide (NO) in methamphetamine (MAP)-induced behavioral sensitization and enhancement of striatal dopamine (DA) release using both in vivo and in vitro methods. Repeated administration of MAP produced augmentation of MAP-induced locomotor activity after 3-day withdrawal of MAP and an enhancement of MAP-evoked DA release from striatal slices after 6-day withdrawal. When the NO synthase (NOS) inhibitor NG-nitro-L-arginine methyl ester (L- NAME) was administered only during the period of MAP withdrawal, the behavioral sensitization and enhancement of DA release were attenuated significantly. In contrast, NG-nitro-D- arginine methyl ester, an inactive isomer of L-NAME, exhibited no such effect. When L-NAME was administered acutely before the challenge injection of MAP, behavioral sensitization was also attenuated only when the dose of L-NAME was high. Coadministration of L-NAME with MAP did not block the development of sensitization to MAP. We also examined whether MAP-induced behavioral sensitization and enhancement of DA release could be observed in vivo in a microdialysis experiment. Challenge injection of MAP caused marked enhancement of DA release in MAP-sensitized rats compared with saline-treated controls corresponding to robust augmentation of locomotor activity. When L-NAME was injected during the MAP withdrawal period, the enhancement of DA release and locomotor activity induced by challenge injection of MAP were attenuated. These results suggest that NO production plays a role in the maintenance (expression) of MAP-induced behavioral sensitization and enhancement of DA release but not in the development of these effects.

Animals↗