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Biomedical subjects

T Chiba

Publications and source records attributed to T Chiba.

At least 397 records · Page 22Linked to original sources
PubMed1994

Finding of primitive polyamine toxins in the venom of a joro spider, Nephila clavata.

A series of joro spider toxins, novel polyamines sharing a common moiety of 2,4-dihydroxyphenylacetyl cadaverine, have been identified using various bioassays, such as inhibition of a glutamatergic transmission and insecticidal activity. In this paper, we tried to chemically find still unknown polyamine toxins in the venom of a joro spider, N. clavata, by several analytical methods based on the characteristics of the common moiety. An aqueous extract from 3000 venoms was separated by preparative high performance liquid chromatography (HPLC). The polyamine toxins were detected by monitoring the fluorescence produced in an on-line reaction of o-phthalaldehyde with amino groups and UV absorption of the phenol group. Two compounds in minute quantity were purified and analyzed by gas-liquid chromatography (GC) and HPLC, which we specifically developed for the simultaneous determination of amino acids and polyamines of the toxins. Judging from the constituents of the hydrolysate by GC and HPLC and the molecular weights determined by fast atom bombardment mass spectrometry, the two compounds were estimated to be N-(2,4-dihydroxyphenylacetyl-L-asparaginyl)-N'- (3-aminopropyl-beta-alanyl) cadaverine and N-(4-hydroxyphenylacetyl-L-asparaginyl)-N'-(3-aminopropyl-beta-ala nyl) cadaverine. These compounds were small in content and molecular weight compared with hitherto known toxins. Both were presumed to be biochemically primitive toxins and were named spidamine and joramine, respectively.

Animals↗
PubMed1994

Degradation of deltorphins and their analogs by rat brain synaptosomal peptidases.

To obtain metabolically stable peptide ligands with high affinity and selectivity for the delta-opioid receptor, the enzymatic stability of deltorphins and their analogs was examined by using a crude rat brain synaptosomal membrane fraction. It was found that deltorphin (DLT: Tyr-D-Met-Phe-His-Leu-Met-Asp-NH2) was easily degraded, producing DLT (1-4) and DLT (1-5) as the major degradation products, whereas [D-Ala2]deltorphin II (DL-II: Tyr-D-Ala-Phe-Glu-Val-Val-Gly-NH2) was very stable. Experiments with some enzyme inhibitors strongly suggested that the degradation of DLT was initiated by cleavage of the Leu5-Met6 bond by a metalloendopeptidase. On the other hand, stability experiments on DL-II analogs demonstrated that the presence of amino acids branched at the beta-carbon atom or with a bulky side chain as residue 5 is of importance for the enzymatic stability. Based on these lines of evidence, some enzyme-resistant DLT analogs were synthesized.

Amino Acid Sequence↗
PubMed1994

Sarcoidosis with hypercalcemia--successful treatment of renal insufficiency and renal calcification with prednisolone.

A case of muscular sarcoidosis accompanied by severe hypercalcemia (serum calcium 15.5 mg/dl), renal insufficiency and renal calcification is reported. Sarcoid granulomas were found in the biopsy specimens of the lung and the muscle. The administration of prednisolone effectively improved not only muscle weakness but also hypercalcemia, renal insufficiency and renal calcification. This is a rare case of sarcoidosis in which renal calcification remitted after treatment with prednisolone. It is thus suggested that prednisolone treatment should be considered not only for hypercalcemia, but also for renal insufficiency caused by renal calcification in patients with sarcoidosis.

Calcinosis↗
PubMed1994

Vestibular sensory epithelia in patients with acoustic neurinoma.

The human vestibular sensory epithelia of the macula utriculi were examined ultrastructurally in 13 cases with acoustic neurinoma. The sensory epithelia were fairly well preserved, with several morphological changes such as lipofuscin granules, intraepithelial cysts, pyknosis, vacuoles, laminated structures, banded structures and degeneration of subepithelial myelinated nerves evident. The pathological significance of these findings was discussed. There were thickened irregular membrane formations in spaces between the nerve calyces and type I hair cells which might be related to acoustic neurinoma. Some type I hair cells were incompletely surrounded by nerve calyces. The neck regions of these cells received direct contact from the efferent nerve endings.

Adolescent↗
PubMed1994

Distribution of phosphate-activated glutaminase-like immunoreactivity in the retina of rodents.

The distribution of phosphate-activated glutaminase-like immunoreactivity was examined in the retinas of rodents. Intense glutaminase immunoreactivity was observed in many neuronal perikarya in the ganglion cell layer and inner nuclear layer including those of ganglion, bipolar and amacrine cells and possibly horizontal cells. Almost all bipolar cells containing protein kinase C were immunoreactive for glutaminase, suggesting that the majority of glutaminase immunoreactive bipolar cells were of the ON type. Intense glutaminase immunoreactivity was also found in the neuropil of the inner and outer plexiform layers and around the outer limiting membrane. Weak to moderate immunoreactivity was seen in the outer nuclear layer and photoreceptor inner and outer segments. Under electron microscopy, glutaminase immunoreactivity was seen in bipolar cell axons and amacrine cell processes in the inner plexiform layer. In the outer plexiform layer, immunoreactivity was found in the Müller cell processes, but not in the photoreceptor cell terminals. These results indicate that ganglion cells and ON type bipolar cells use glutaminase to produce transmitter glutamate and suggest glutaminase has additional roles in Müller cells. A population of amacrine cells and horizontal cells showed immunoreactivity to glutaminase.

Animals↗
PubMed1994

Ultrastructural and immunocytochemical study of the subepithelial fiber component of the guinea pig inner ear.

The connective tissues of the lateral cochlear wall and semicircular canal of the guinea pig were investigated by transmission electron microscopy, intermediate voltage electron microscopy and immunocytochemistry. In the spiral ligament, numerous fibroblasts and fiber bundles were intermingled with each other. Fibroblasts and fibers were also observed in the semicircular canal. Ultrastructurally, immuno-gold particles, indicating the presence of type II collagen, were found on the fibers in the spiral ligament and the semicircular canals. The present results revealed that both stria vascularis and the membranous semicircular canal were supported by a network of fibroblasts and type II collagen fibers.

Animals↗
PubMed1994

[Comparison of the effects between standard doses of H2-blocker (famotidine 20mg b.d.) and proton pump inhibitor (omeprazole 20mg o.d.) in the treatment of refractory reflux esophagitis by ambulatory 24-hr intra-gastroesophageal pH monitoring].

Ambulatory 24-hour pH monitoring was conducted in 11 patients with H2-blocker resistant reflux esophagitis to compare the effects of standard doses of H2-blocker (famotidine 20mg twice daily) and proton pump inhibitor (omeprazole 20mg once daily) on the inhibition of intraesophageal acidity. Mean intraesophageal pH during PPI treatment was significantly higher than that during H2-blocker treatment. Proportion of abnormal intra-esophageal acidity in 24hr (%time pH < 4) during PPI treatment was significantly less than that during H2-blocker treatment (11.7 +/- 3.1% vs 31.6 +/- 4.8%). The difference of the effect was more apparent in day time (upright time) than in night time (supine time). Thus PPI is superior to H2-blocker in treatment for refractory reflux esophagitis, but proportion of abnormal intra-esophageal acidity in 24hr (%time pH < 4) could be normalized only in 4 out of 11 patients even by standard dose PPI treatment. Effects of not only long-term maintenance therapy but also high dose therapy with PPI should be examined in future studies.

Aged↗
PubMed1994

Development of glycosylated human interleukin-1 alpha, neoglyco IL-1 alpha, coupled with D-mannose dimer: synthesis and biological activities in vitro.

Interleukin 1 (IL-1) is a nonglycosylated cytokine with pleiotropic effects on various cell types. In order to investigate the effect of carbohydrate introduction on IL-1 activity and to develop IL-1 with less deleterious effects recombinant human IL-1 alpha was chemically coupled with mannose dimers, alpha-D-Man1-6-D-Man[Man2(alpha 1,6)] and alpha-D-Man1-4-D-Man[Man2(alpha 1,4)]. About 5 molecules of mannose dimers were introduced per molecule of IL-1. Anti-IL-1 alpha antibody reacted only weakly with the glycosylated IL-1s. Conversely, antibody against the mannose dimer reacted with only glycosylated IL-1. The effect of glycosylation on IL-1 activity was evaluated by measuring a variety of IL-1 activities in vitro, including proliferative effect on T cells, antiproliferative effect on melanoma cells, stimulatory effect on IL-6 synthesis by melanoma cells, and stimulatory effect on prostaglandin E2 synthesis by fibroblast cells. Glycosylated IL-1s exhibited reduced activities, which were 10-fold to more than several hundred-fold lower than those of the original IL-1 alpha depending upon different aspects of activities addressed. Man2(alpha 1,6)-introduced IL-1 exhibited lower activity than Man2(alpha 1,4)-introduced IL-1. The competitive binding of 125I-IL-1 alpha to mouse T cells with unlabeled IL-1s suggests that the reduced activity of glycosylated IL-1s is due, at least partially, to the decrease of their receptor binding abilities.

Animals↗
PubMed1994

Cholecystokinin-B/gastrin receptor signaling pathway involves tyrosine phosphorylations of p125FAK and p42MAP.

The neuro-intestinal peptide hormone cholecystokinin (CCK)/gastrin has been suggested to have a trophic effect on gastro-intestinal tract in vivo as well as in vitro. In the present study, the human CCK-B/gastrin receptor was expressed in mouse NIH3T3 fibroblasts to investigate the molecular basis of signal transduction pathway of the guanine nucleotide regulatory protein (G protein)-coupled receptor. Human CCK-B/gastrin receptor expressed in NIH3T3 cells coupled efficiently to phosphoinositide hydrolysis and mobilization of intracellular Ca2+, and transduced mitogenic signals assessed by [3H]thymidine incorporation in a dose-dependent manner. Moreover, CCK-8 or gastrin I alone promoted the cell growth in serum-free medium. CCK-8 induced tyrosine phosphorylation of several protein species. Among them, mitogen-activated protein (MAP) kinase was tyrosine phosphorylated and activated in response to CCK-8, as was induced by platelet-derived growth factor (PDGF). In contrast, tyrosine phosphorylation of p125FAK (focal adhesion kinase) was induced by CCK-8 but not by PDGF. CCK-8 as well as gastrin I induced the expression of early responsive genes such as c-fos and c-myc. These results suggest that CCK-B/gastrin receptors might transmit mitogenic signals by cross-talking with the tyrosine kinase cascades.

3T3 Cells↗
PubMed1994

Phenotype analysis of lymphocytes present in different stages of neoplasia induced by bovine leukemia virus.

Distribution of subpopulations of lymphocytes in the lymph nodes and tumor tissues from cattle with enzootic bovine leukosis (EBL) was examined by immunohistology using a panel of monoclonal antibodies against leukocyte differentiation molecules of bovine leukocytes and tumor-associated antigen (TAA) of EBL. As disease progressed in the lymph nodes, TAA positive cells increased in number and were strongly positive. The number of B-B2, IgM positive cells were reduced in frequency in the follicle and areas of neoplastic cell-proliferation. Alpha beta and gamma delta T cells positive for WC1 (workshop cluster designation) were reduced in frequency due to infiltration and proliferation of neoplastic cells. In tumor tissues which were thought to consist with monoclonal population of cells carrying BLV provirus, strongly TAA-positive cells were present throughout the section. Most of the neoplastic cells from five cattle with EBL appeared to be divided into four types, CD2-, CD4-, CD8-, WC1-, B2+ or B2-, IgM+ or IgM-, MHC II+ and strong TAA+. WC1+ cells played no apparent role in the development of lymphosarcoma of EBL. WC1+ cells were not observed in tumor tissues. However, the possibility of effect of T cell for tumor immunity was suggested, since TH/l and Tc/s cells were scattered in the tumor tissues.

Animals↗
PubMed1993

Induction of erythroid-specific gene expression in lymphoid cells.

Erythropoietin (Epo) is a cytokine which specifically regulates differentiation and proliferation of erythroid progenitor cells. We report here that Epo receptor expressed in interleukin 3-dependent lymphoid Ba/F3 cells transmits both differentiation and growth signals. Epo stimulation of these cells leads to activation of transcription and/or translation of the erythroid-specific transcription factors GATA-1 and SCL, followed by the accumulation of both alpha- and beta-globin chains. These results suggest that expression and activation of the Epo receptor regulates erythroid-specific gene expression and might play a role in determining a cell lineage in vivo and that GATA-1 and SCL may exert their effects after Epo binds to its receptor. It was further found that chimeric receptors composed of extracellular domains of Epo receptor and cytoplasmic domains of interleukin 2 or interleukin 3 receptors could also induce erythroid-specific gene expression in Ba/F3 cells. Taking these data together with previous observations, we conclude that interaction of the extracellular domains of the Epo receptor with other membrane components is essential for transmission of both the erythroid differentiation and the growth signals.

Animals↗
PubMed1993

Parathyroid hormone-related protein in gastric cancers with heterotopic ossification.

BACKGROUND: Parathyroid hormone-related protein (PTHrP) has been regarded as one of the substances causing humoral hypercalcemia of malignancy. METHODS: The immunohistochemical localization of PTHrP was investigated in 33 cases of gastric cancer (4 with heterotopic ossification and 29 without heterotopic ossification) to clarify the role of PTHrP in heterotopic ossification by using the anti-PTHrP monoclonal antibody, 4B3. RESULTS: The four cases with heterotopic ossification showed positive staining at primary or metastatic sites, and in one case fibroblasts in the stroma surrounding the heterotopic ossifying foci also showed positive. On the other hand, of the 29 cases without heterotopic ossification, only 5 showed positive staining. CONCLUSIONS: The presence of PTHrP in ossifying gastric carcinomas at a relatively high rate indicates that PTHrP also might be related to heterotopic ossification associated with malignancies. It is speculated that PTHrP would contribute to heterotopic ossification by facilitating the process of mineralization.

Adenocarcinoma↗
PubMed1993

Distribution of NADPH-diaphorase positive nerve fibers in the rat nasal mucosa.

Nasal mucosa was investigated by NADPH-diaphorase histochemistry. Positive fibers were distributed around blood vessels, seromucous glands and in the subepithelial layer. The pterygopalatine, trigeminal and superior cervical ganglia were also studied to examine the origin of these fibers. Many neurons in the pterygopalatine ganglion were labeled, and a few neurons were stained in the trigeminal ganglion. No perikarya were labeled in the superior cervical ganglion. Therefore, most of the labeled fibers must be originating from the pterygopalatine ganglion, and the rest of them may originate from the trigeminal ganglion. These results suggest that nitric oxide may have some role in the nervous control of the nasal mucosa.

Animals↗
PubMed1993

Functional characterization of a human brain cholecystokinin-B receptor. A trophic effect of cholecystokinin and gastrin.

We have cloned a human brain cholecystokinin (CCK)-B receptor cDNA and characterized its function by introducing it into Chinese hamster ovary (CHO) cells. The deduced amino acid sequence was highly conserved as compared with those of the gastrin receptors in Mastomys enterochromaffin-like cells (90%) and canine parietal cells (89%). Human brain CCK-B receptors possessed slightly but significantly higher affinities for CCK-8 than for gastrin I, while both ligands bound equally to Mastomys enterochromaffin-like cell-derived gastrin receptors. Both CCK-8 and gastrin I markedly augmented phosphoinositide hydrolysis and cytosolic free calcium levels in the CHO transfectants, indicating that the cloned CCK-B receptor could functionally couple with intracellular signaling molecules. Moreover, CCK-8 and gastrin I dose-dependently increased [3H]thymidine incorporation of the CHO transfectants in serum-free medium and promoted cell growth. The CCK-B receptor mRNA was abundantly expressed in particular areas of the human brain and stomach, such as the cerebral cortex and mucosa of the gastric fundus. This is the first demonstration of trophic effects of CCK and gastrin through the normal human brain CCK-B receptor. The availability of this receptor cDNA will help to clarify the precise role of CCK in the central nervous system as well as digestive organs.

Amino Acid Sequence↗
PubMed1993

Direct synaptic contacts of nitric oxide synthase-immunoreactive nerve terminals on the neurons of the intracardiac ganglia of the guinea pig.

Immunoelectron microscopy was performed to localize immunoreactivity for nitric oxide synthase (NOS) in guinea pig atria. Many round intracardiac ganglia, close to the openings of the pulmonary veins, contained NOS-immunoreactive neurons. A small number of neurons were immunoreactive, but most of the non-immunoreactive neurons were surrounded by immunoreactive axons. Direct axo-somatic or -spinic synapses from NOS-immunoreactive axon varicosities to intracardiac ganglionic neurons were observed. The present results raise the possibility that nitric oxide plays a role in the neural control of the heart through synapses in the cardiac ganglia.

Amino Acid Oxidoreductases↗
PubMed1993

p34cdc2 homologue is located in nucleoli of the nervous and endocrine systems.

p34cdc2 protein kinase is a component of M phase-promoting factor (MPF), which plays an important role in controlling the mitotic and meiotic cell cycle. p34cdc2 contains a unique 16 amino acid sequence (PSTAIR) that is conserved from fission yeast to human. Using polyclonal anti-PSTAIR antibody, we detected the p34cdc2 homologue in the central nervous system of adult mice by western blotting. By immunohistochemical technique, we found that the p34cdc2 homologue was located in the nucleoli of neurons and glia in the central and peripheral nervous systems. In the central nervous system, positive cells were widely distributed from the cerebral cortex to the spinal cord. Immunoreactive cells were also detected in retina and pituitary. The evidence that the p34cdc2 is present in neurons which have lost the ability of cell division predicts another function of p34cdc2 family proteins besides the one that has generally recognized.

Amino Acid Sequence↗