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Biomedical subjects

T Chiba

Publications and source records attributed to T Chiba.

At least 559 records · Page 31Linked to original sources
PubMed1987

Synaptic structure of the monoamine and peptide nerve terminals in the intermediolateral nucleus of the guinea pig thoracic spinal cord.

Synaptic organization of the intermediolateral nucleus of the guinea pig thoracic spinal cord was examined with particular focus on monoamine- and peptide-containing nerve terminals. Axon varicosities having flat synaptic vesicles constituted 17% of all axons in the nucleus and formed exclusively symmetric synapses. Enkephalin-, substance P-, somatostatin-, 5-hydroxytryptamine-, and catecholamine-immunoreactive nerve terminals were densely distributed, while neurotensin, vasoactive intestinal polypeptide-, oxytocin-, and cholecystokinin-8-immunoreactive nerves were sparse in the nucleus. Coexistence of 5-hydroxytryptamine and enkephalin was demonstrated, and coexistence of somatostatin and enkephalin as well as somatostatin and 5-hydroxytryptamine in the same axons was also shown by serial semithin sections. Catecholamine axons labelled by 5-hydroxydopamine formed axodendritic and axosomatic synapses and made direct synaptic contacts on the preganglionic sympathetic neurons identified by retrograde transport of horseradish peroxidase. Direct synaptic contacts from enkephalin- and substance P-immunoreactive axons to preganglionic sympathetic neurons were also revealed. Enkephalin-, substance P-, and 5-hydroxytryptamine-immunoreactive axons formed axodendritic and axosomatic synapses. Catecholamine axon varicosities constituted 19% of all axon varicosities in the nucleus and 30% of them showed synaptic specializations in a sectional plane. Axon varicosities immunoreactive to enkephalin, 5-hydroxytryptamine, and substance P constituted approximately 35, 19, and 13% of all axon varicosities, respectively, while those with synaptic contacts made up 27, 30, and 26%, respectively, in a sectional plane. Enkephalin-, 5-hydroxytryptamine-, and noradrenaline-immunoreactive axons showed mainly symmetric synaptic contacts.

Animals↗
PubMed1987

Divergent stimulatory and inhibitory actions of carbamoylcholine on gastric D-cells.

Carbamoylcholine (carbachol) has been shown to inhibit somatostatin release from gastric D-cells. We observed that this dose-dependent inhibitory effect was accompanied by decreases in cellular cyclic adenosine 3':5'-monophosphate (cAMP) production and increases in parameters of membrane inositol phospholipid turnover. However, after pretreatment of D-cells with pertussis toxin (200 ng/ml), carbachol paradoxically stimulated basal somatostatin release and potentiated the secretagogue action of forskolin. Pertussis toxin pretreatment blocked the ability of carbachol to decrease cAMP production but changes in inositol phospholipid turnover were unaffected. Atropine reversed all of the observed changes induced by carbachol. These data suggest that muscarinic cholinergic receptors mediate both stimulatory and inhibitory regulation of D-cells. The inhibitory effect may involve pertussis toxin-sensitive inhibitory guanine nucleotide binding proteins while the stimulatory effect may result from the consequences of membrane phosphoinositide turnover.

Animals↗
PubMed1987

Glucose stimulates insulin release without altering cyclic AMP production or inositolphospholipid turnover in freshly obtained human insulinoma cells.

Glucose, forskolin, IBMX and carbachol all stimulated insulin release from freshly obtained human insulinoma cells. In these same cells, cellular cyclic AMP levels were raised by forskolin and IBMX but not by glucose and carbachol. On the other hand, of all the insulin secretagogues examined, only carbachol stimulated the formation of 3H-inositol trisphosphate in these cells. Thus, in these insulinoma cells, glucose apparently induces insulin secretion without altering cyclic AMP production or inositolphospholipid turnover.

1-Methyl-3-isobutylxanthine↗
PubMed1987

Possible involvement of inositol phosphates and calmodulin in calcitonin-induced stimulation of phosphate transport in LLC-PK1 cells.

The present study investigated the possible involvement of phosphatidylinositol breakdown and Ca2+-calmodulin complex in the calcitonin-induced stimulation of phosphate transport in LLC-PK1 cells. This cell line with calcitonin receptors possesses Na+-dependent phosphate transport and has been employed as a model for studying the mechanism of renal tubular phosphate transport. (Asu1,7) eel calcitonin stimulated the phosphate transport in LLC-PK1 cells in a dose-dependent fashion with accompanying increase of inositol triphosphate (IP3) production. When the cells were preincubated with the potent calmodulin antagonist, w-7 or w-13, the stimulatory effect of calcitonin on phosphate transport was significantly inhibited. These findings indicate that Ca2+-calmodulin complex formed by increased cytosolic Ca2+, which is mobilized from intracellular pools by IP3, may be involved in the signal transduction of calcitonin in these cells.

Animals↗
PubMed1987

ESR signals from stimulated and resting porcine blood neutrophils.

The NADPH oxidase in neutrophils was specifically solubilized from membrane vesicles of porcine blood neutrophils and rapidly concentrated by immunoprecipitation with cross-reacting anti-P-450 reductase IgG. The precipitates from both myristic acid-stimulated and resting cells contained one third of the cytochrome b-558 and were slightly contaminated with myeloperoxidase. The immunoprecipitate from stimulated cells gave rhombic high-spin ESR signals of a heme at g = 6.47 and 5.49, which were insensitive to KCN, whereas the preparation from resting cells did not give these signals. The rhombic high-spin signals are discussed in view of the participation of cytochrome b-558 in the NADPH oxidase system.

Animals↗
PubMed1987

Characterization of eosin 5-isothiocyanate binding site in band 3 protein of the human erythrocyte.

The characteristics of the anion transport system in human erythrocyte, which can be modified by eosin 5-isothiocyanate (EITC), were studied using the pH titration method and by measuring the sulfate efflux. Based on the pH dependence of EITC binding to the erythrocyte ghosts, it was found that the reaction rate was maximal at about pH 6.4, and that the pH profile of EITC binding was similar to that of divalent anion transport. The interaction between EITC and ghosts was interpreted by a two-step reaction, a fast ionic-binding reaction and a slow covalent-binding reaction. The induced CD spectrum of the EITC-ghost system was also dependent on pH. The intensity of the CD band at 530 nm was decreased in acidic pH region, and the inflection point was observed at about pH 6.3, indicating a participation of the histidine residue in the interaction of EITC with band 3. In order to characterize the EITC-binding site, the kinetics of sulfate efflux in intact and EITC-modified cells were examined at various pH values. The inhibitory effect of EITC was dependent on pH. From the experimental results, the followings are suggested. The rate of ionic interaction in the early stage is much slower than that in a general ionic reaction. A conformational change may participate in the reaction. The conformation of the EITC-binding site depends on pH, relating to the dissociation of the histidine residues. The EITC molecules act also as a competitive inhibitor to the sulfate efflux after binding covalently to band 3 protein.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1987

Partial ornithine transcarbamylase deficiency in females: diagnosis by an immunohistochemical method.

Females heterozygous for the X-linked urea cycle disorder, ornithine transcarbamylase (OTC) deficiency have a significant risk of developing hyperammonaemia. Diagnosis of this genetic defect in a proband is the essential starting point for family studies. By an immunohistochemical analysis of the liver specimens fixed in 10% formalin, we confirmed heterozygous status for OTC deficiency in two female patients, a 15-year-old girl and a 2-year-old girl, who died of hyperammonaemia. Since most affected males lack cross reactive materials (CRM), an immunochemical analysis should be useful for the diagnosis of most heterozygous females.

Adolescent↗
PubMed1987

Variation in the course of vessels in the vicinity of the hepatic port in biliary atresia.

Among 114 patients with biliary atresia, the type of obstruction of the extrahepatic bile duct and the course of the hepatic artery, cystic artery, and portal vein were determined and analyzed from the view point of their mutual relationships and in comparison with postoperative bile excretion. As a result, the following findings characteristic of biliary atresia were obtained: (1) The course and location of the extrahepatic bile duct did not deviate greatly from normal conditions, excluding some exceptional cases, but the site of the origin of the cystic artery differed from that in normal cases. (2) The pattern of the course of the vessels varied among different types of obstruction of the extrahepatic bile duct. (3) There was a difference in postoperative bile excretion in relation to the type of obstruction of the extrahepatic bile duct, the course of the vessels, and their combinations.

Bile Ducts↗
PubMed1987

Three cases of chronic bromisoval intoxication: clinical symptoms and application of energy dispersive X-ray analysis (EDX) to detect bromine in serum, urine and cerebrospinal fluid.

Bromisoval has been used as a hypnotic for the past several decades, and its abuse was known to cause various neurological as well as psychiatric symptoms. Three patients showed a variety of symptoms which could not be explained neuroanatomically: nystagmus, gait disturbance and hyperreflexia of the limbs in all the cases, dysarthria, double vision, hypotonia, ataxic gait and disturbance of consciousness occasionally and auditory agnosia in one case. For the purpose of determining the diagnosis, an energy dispersive X-ray microanalysis (EDX) was used to detect bromine. Five microliters of specimens were placed on the carbon-coated mesh, and using a TN-2000 analyzer, characteristic X-ray peaks of bromine were detected in the serum, urine and cerebrospinal fluid. The sensitivity to detect bromine in the serum was 30 micrograms/ml.

Adult↗
PubMed1987

Potential mediation of somatostatin secretion from canine fundic D-cells by protein kinase c.

We examined the possible importance of protein kinase c-dependent mechanisms in mediating the stimulatory effects of gastrin and cholecystokinin (CCK) on the release of somatostatin-like immunoreactivity (SLI) from isolated canine fundic D-cells. Diacylglycerides, presumably the products of phosphoinositide breakdown that activate protein kinase c, and phospholipase C, which catalyzes the production of endogenous diacylglycerides from membrane phospholipids, both stimulated SLI secretion in a dose-dependent fashion. Both classes of agents potentiated the actions of adenosine 3',5'-cyclic monophosphate-dependent agonists but not those of gastrin and CCK. The stimulatory effects of gastrin and CCK correlated with their abilities to enhance the incorporation of 32P into membrane phosphatidyl inositol and phosphatidic acid and promote the release of [3H]inositol trisphosphate from prelabeled D-cells, two parameters of phosphoinositide turnover. These data suggest that protein kinase c may serve to transduce the signals activated by gastrin and CCK in D-cells.

Animals↗
PubMed1987

Hypocalcemic crisis in alcoholic fatty liver: transient hypoparathyroidism due to magnesium deficiency.

Hypocalcemic crisis developed in a patient with acute alcoholic fatty liver. In addition to jaundice and marked hepatomegaly, the patient presented with hypocalcemic crisis associated with hypomagnesemia, low plasma 1,25(OH)2-vitamin D and undetectable plasma parathyroid hormone (PTH) concentration. Subsequent computerized tomographic scan and liver biopsy showed the presence of severe fatty liver. With the improvement of liver function, the serum calcium level increased, and was accompanied by normalization of plasma PTH, serum magnesium, and plasma 1,25(OH)2-vitamin D levels. Serial ethylenediaminetetraacetic acid infusion tests demonstrated the reversal of the impaired PTH secretion. Thus, hypocalcemic crisis in this patient appeared to result from transient hypoparathyroidism induced by magnesium deficiency.

Acute Disease↗
PubMed1987

[A case of immunohistochemically carcinoembryonic antigen producing cervical cancer--the evaluation of plasma CEA levels in 201 patients with uterine cancer].

A case of a cervical cancer in a 40-year-old woman with a plasma carcinoembryonic antigen (CEA) level of 29.4 ng/ml was investigated using light and electron microscopy. In addition, the plasma CEA levels before treatment were determined in 168 patients with cervical cancer and in 33 patients with endometrial cancer. CEA was found to be elevated in the plasma of 19% of those with cervical cancer and in 6% of those with endometrial cancer. Effective serial plasma CEA determinations following therapy, in patients whose plasma or tumors initially contain elevated amounts of antigen, might be useful as an adjunctive method in the earlier detection of a recurrent cancer.

Adult↗
PubMed1987

[An endometrial carcinoma occurring in both horns of a uterus bicornis unicollis--a case report].

A case of an endometrial carcinoma occurring in both horns of a uterus bicornis unicollis in a 50-year-old women is described. This diagnosis can be easily missed unless both endometrial cavities are curetted simultaneously in cases of an either right or left affected fundus of a divided uterus. The correct diagnosis and a prompt definite treatment in this rare combination are emphasized.

Adenocarcinoma↗
PubMed1986

Regional distribution of gastrin-releasing peptide- and somatostatin-like immunoreactivity in the rabbit hypothalamus.

Regional distribution of gastrin-releasing peptide- (GRP) and somatostatin (SRIF)-like immunoreactivity in the discrete nuclei of the hypothalamus was examined in the rabbit according to Palkovits' microdissection method. GRP-like immunoreactivity (LI) was detected abundantly in the hypothalamus as compared with the cerebral cortex when measured by radioimmunoassay using the antiserum recognizing the C-terminal portion of synthetic porcine GRP. On gel-filtration chromatography of the hypothalamic extracts, two major peaks of GRP-LI were eluted; the peak with larger molecular size corresponded to synthetic porcine GRP1-27 and the smaller size to porcine GRP14-27. A concentration of GRP-LI was highest in the infundibular nuclei (IFN) as well as the ventromedial nuclei (VMN), and next high in the paraventricular nuclei (PVN), suprachiasmatic nuclei (SCN) and periventricular nuclei (PEV). The content of GRP-LI in the median eminence was not so much when compared with them. On the other hand, SRIF was localized in the highest concentration in the ME, followed by the VMN and IFN, as well as the PEV. The findings indicate that porcine GRP-LI exists in the hypothalamus of rabbits with characteristic regional distribution. Concurrent localization of GRP-LI and SRIF in some parts of the hypothalamus may suggest the interaction of both peptides in these areas under various physiological and pathological status.

Animals↗