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Biomedical subjects

C Shibata

Publications and source records attributed to C Shibata.

52 records · Page 3Linked to original sources
PubMed1991

[Role of bile and pancreatic juice in regulation of gut hormone secretion].

To elucidate the role of bile and pancreatic juice in regulation of gut hormone secretion, an experimental study was performed creating models of biliary and pancreatic juice diversion in conscious dogs with reference to gastric acid and pancreatic exocrine secretions. The results were obtained as follows. 1) Diversion of bile from the duodenum to the jejunum, the ileum and urinary bladder (UB) did not affect the postprandial gastric acid and gastrin secretion, except slight suppression of gastric acid in model of bile diversion to the ileum and UB. 2) Postprandial GIP secretion was completely diminished and total-GLI secretion was significantly increased after bile diversion to the ileum and UB, whereas the jejunal diversion did not affect both GIP and total-GLI secretion. 3) A marked hypertrophy of pancreatic acinar cells was seen in conventional histopathological investigation and hyperfunction indicated by microelectroscopical findings was observed after bile diversion to UB with significant hypersecretion of CCK. 4) In the model of bile diversion to UB, hypersecretion of insulin was observed after intravenous glucose infusion test. 5) Diversion of pancreatic juice from the duodenum to the jejunum induced significant postprandial hypersecretion of gastric acid and hyposecretion of GIP.

Animals↗
PubMed1981

Glomerulonephritis associated with arteritis in marmosets infected with hepatitis A virus.

Seven of 8 marmosets (Saguinus oedipus and Saguinus labiatus) injected i.v. with different inocula of hepatitis A virus isolated from patients in the acute phase of disease developed proliferative glomerulonephritis associated with arteritis. The glomerulonephritis was characterized by immunofluorescent and electron-dense deposits and hypercellularity. Although no antigenic component of the glomerular immune complex was detected, this glomerulonephritis and arteritis may be diagnosed morphologically as an immune complex disease. These findings show the possibility of the appearance of exohepatic disease as an immunologically mediated disease in human hepatitis A virus infection.

Animals↗
PubMed1981

Radiosensitizing effect of 2,4-dinitroimidazole-1-ethanol and its cytotoxicity in HeLa S3 cells.

Using cultured HeLa S3 cells, the radiosensitizing and cytotoxic effects of newly synthesized derivatives of dinitroimidazole were investigated and compared with those of misonidazole. 2,4-Dinitroimidazole-1-ethanol radiosensitized hypoxic cells selectively. At 5 mM misonidazole, the enhancement ratio was 1.95; with 0.5 mM 2,4-dinitroimidazole-1-ethanol, almost the same enhancement could be obtained. This indicates that the radiosensitizing effect of the latter agent was about 10 times greater than that of misonidazole. However, its cytotoxicity was twice that of misonidazole under hypoxic conditions and there was no apparent differential cytotoxicity to hypoxic and aerobic cells.

HeLa Cells↗
PubMed1981

An approach to the design and synthesis of mercaptoimidazole derivatives containing oxidized sulfur based on electron affinity sensitization.

New mercaptoimidazole derivatives containing oxidized sulfur were designed and synthesized for screening with hypoxic radioresistant cells in place of nitroimidazoles, which are well-known radiosensitizing agents. The electron affinities of various mercaptoimidazole derivatives such as the sulfoxide (4) and sulfone (5) were estimated on the basis of the lowest unoccupied molecular orbital (LUMO) by using the CDNO/2 method. Compounds (4) and (5) thus designed were synthesized from the sulfide (3) by metaperiodate oxidation in 72% and 89% yields, respectively. No appreciable activity was observed with these compounds upon in vitro screening, probably due to their low water-solubility. Nevertheless, this approach may be useful for the development of improved radiosensitizers provided that mercaptoimidazole derivatives with adequate water-solubility can be obtained.

Cell Survival↗
PubMed1981

Effect of prolonged exposure of HELA S3 cells to low concentrations of misonidazole.

The cytotoxic and radiosensitizing effects of low concentrations of misonidazole were examined by measurement of the colony-forming ability and growth of HeLa S3 cells. Under hypoxic conditions, cytotoxicity depended on the misonidazole concentration and the exposure time. After 24 hr exposure, the surviving fraction of cells treated with 0.1 mM misonidazole decreased to 0.2. The ability of cells to adhere to the growth surface of plastic dishes was reduced by 0.1 mM misonidazole upon 24 hr hypoxia and this effect persisted even during subsequent euoxia, irrespective of whether the drug was removed from the original growth medium. The growth of aerobic cells was not affected when 0.1 mM misonidazole containing medium, obtained from the hypoxia-treated dishes, was applied, nor when those cells were exposed for 72 hr to freshly prepared 1.0 mM misonidazole. Upon 24 hr exposure, 0.1 mM misonidazole exerted no obvious radiosensitizing effect on hypoxic cells. Based on these results, it is suggested that continuous administration of low doses of misonidazole may be efficacious as a specific chemotherapeutic in the treatment of hypoxic cells in tumor tissue.

Anaerobiosis↗
PubMed1980

Effect of hypoxia on the cytotoxicity of misonidazole in HELA S3 cells in vitro.

A simple method to establish hypoxic conditions in vitro is described and the cytotoxicity and radiation dose-modifying effect of misonidazole were investigated; using HeLa S3 cells. Under hypoxic conditions, 5-hr exposure to 50mM misonidazole resulted in severe cytotoxicity, though the toxicity at 1mM was low. The survival curves of cells exposed to 5 or 10mM misonidazole showed an initial exponential portion followed by a less steep decline. Under aerobic conditions, exposure to 1mM for 5 days showed no cytotoxicity, while the surviving fraction of cells exposed to 50mM for 10 hr was reduced to 0.3. Acute conversion from hypoxic to aerobic conditions revealed persistence of the cytotoxicity for 2 hr after the conversion. Under hypoxic conditions, a dose-modifying factor of 1.9 was achieved for cells irradiated with gamma rays.

Animals↗
PubMed1979

[In vivo distributions of 111In and/or 3H labeled lymphocyte in C3H/He mouse (author's transl)].

Although 99mTc and 51Cr have been used for lymphocyte labeling, these radionuclides have several disadvantages for study on immunological behaviour of lymphocyte; very high rate elution and low labeling efficiency for both radionuclides, and short half life for 99mTc. Indium-111 has quite suitable physical properties for clinical nuclear medicine, i.e. desirable photon energy (247,173 keV) and 2.8 day half life. 111In-oxine is lipid soluble and is known to pass through the cell membrane and attaches firmly to cytoplasmic component of the cell. On the other hand, 3H-thymidine is well known substance which incorporated to nucleic acid in the cell. In this study, distribution patterns of 111In-oxine and/or 3H-thymidine labeled lymphocyte in C3H/He mice were examined and the suitability of 111In-oxine labeled lymphocyte for radionuclide imaging in vivo was discussed. Thirty minutes after intravenous injection of 3H and/or 111In labeled lymphocyte, about 12% of lymphocyte were found in the lungs and rest of them were distributed mainly in the blood, kidneys and liver. After 24 hours the activity in the lung decreased markedly and the activity in the liver and kidneys increased with time. Between lymphocyte labeled with 111In-oxine and 3H-thymidine, there is not so much differences in terms of distribution patterns. From this study, it is concluded that the 111In-oxine labeled lymphocyte distributes in the same way as 3H labeled one, in spite of different labeling sites. This 111In-oxine labeling method can be used as a useful tool of radionuclide imaging in kinetic studies of lymphocyte in vivo.

Animals↗
PubMed1977

Cervical angiofollicular lymph node hyperplasia.

A three-and-a-half-year-old male with cervical angiofollicular lymph node hyperplasia is presented. Only 185 cases of this lesion have ever been described. The greater majority of these (80%) were located in the mediastinum. This case represents the youngest patient ever described as having such a lesion, especially located in the neck. The history, etiological theories, and pathology of this problem are discussed.

Child, Preschool↗
PubMedDate not supplied

Nitric oxide pathways in circular muscle of the rat jejunum before and after small bowel transplantation.

Previous studies suggest that nitric oxide synthase is upregulated after small bowel transplantation which may have implications in enteric dysfunction after small bowel transplantation. The aim of this study was to determine the role of nitric oxide in nonadrenergic, noncholinergic inhibitory function after small bowel transplantation in rat jejunal circular muscle. The following four groups of rats (n = >/=8 rats per group) were studied: Neurally intact control animals; 1 week after anesthesia and sham celiotomy, and either 1 week or 8 weeks after isogeneic, orthotopic small bowel transplantation. Full-thickness jejunal circular muscle strips were evaluated under isometric conditions for spontaneous contractile activity, response to electrical field stimulation, and effects of exogenous nitric oxide and nitric oxide antagonists. Spontaneous activity did not differ among groups. Electrical field stimulation inhibited activity similarly in all groups. Exogenous nitric oxide, NG-monomethyl L-arginine monoacetate salt (a nitric oxide synthase inhibitor), and methylene blue (cGMP antagonist) had no effect on spontaneous activity. Neither nitric oxide antagonist altered the inhibitory response to neural excitation by electrical field stimulation in any group. Nitric oxide, a known inhibitory neurotransmitter in other gut smooth muscle, has no apparent role in rat jejunal circular muscle before or after small bowel transplantation.

Animals↗
PubMedDate not supplied

Chronic diversion of bile to the urinary bladder induces pancreatic growth in dogs.

The aim of this study was to elucidate the mechanism of chronic biliary diversion and its effect on pancreatic growth. In the first part of the study, nine mongrel dogs underwent diversion of bile from the gastrointestinal tract by ligating the common bile duct and interposing a segment of jejunum between the gallbladder and the urinary bladder (cholecystojejunocystostomy [CJC]). Despite the loss of 7% of their body weight at 12 weeks after bilioenteric diversion, CJC dogs had significantly greater pancreatic wet weight than control dogs (51.2 +/- 2.2 g vs. 37.1 +/- 2.2 g). In the second part of the study, six other dogs underwent CJC. Twelve weeks later, bilioenteric continuity was restored by creating a cholecystojejunoduodenostomy (CJD). The dogs were given butter (3 g/kg) by mouth (prior to surgery, 12 weeks after CJC, and 4 weeks after CJD). Pancreatic excisional biopsy specimens were obtained at each operation and at autopsy. CJC induced more pancreatic RNA per milligram of weight (743 +/- 52, CJC; 579 +/- 44, prior to surgery, P <0.05 vs. CJC; 520 +/- 26 microg/100 mg tissue, CJD, P <0.01 vs. CJC), but not more DNA, and significantly higher basal plasma cholecystokinin levels and butter-stimulated cholecystokinin responses when compared with values prior to surgery or following CJD. We conclude that chronic biliary diversion induces pancreatic growth associated with hypersecretion of cholecystokinin in dogs.

Animals↗
PubMedDate not supplied

Mediators for fat-induced ileal brake are different between stomach and proximal small intestine in conscious dogs.

Our aim was to determine the mechanisms by which intraileal fat alters proximal gastrointestinal motility--the ileal brake. Five mongrel dogs with ileal Thiry-Vella fistulas were equipped with strain gauge force transducers on the upper gut to measure contractile activity. Ileal infusions of 115 mmol/L oleic acid and triglyceride were studied in dogs with extrinsically innervated and extrinsically denervated Thiry-Vella loops. Plasma concentrations of peptide YY and total glucagon-like immunoactivity were measured. Oleic acid but not triglyceride inhibited postprandial contractions in the gastric antrum in dogs with innervated and denervated Thiry-Vella loops. Postprandial duodenal and jejunal motility was inhibited by oleic acid regardless of extrinsic denervation to the loops (P <0.05), but triglyceride inhibited small intestinal motility only in dogs with innervated Thiry-Vella loops. Intraileal oleic acid but not triglyceride increased plasma concentrations of peptide YY and total glucagon-like immunoactivity in dogs with innervated and denervated Thiry-Vella loops. Intraileal oleic acid inhibits gastric and small intestinal motility possibly via increased plasma concentrations of peptide YY and enteroglucagon. Intact extrinsic innervation is necessary for intraileal triglyceride to inhibit small intestinal motility.

Animals↗
PubMedDate not supplied

Contractile activity of circular smooth muscle in rats one year after small bowel transplantation: differing adaptive response of the jejunum and ileum to denervation.

The aim of the present study was to determine the long-term effects of isogeneic small bowel transplantation (SBT) on jejunal and ileal circular smooth muscle contractile activity in the rat. Transmural strips of circular muscle were prepared from proximal jejunum and distal ileum of 1-year-old control rats and rats 1 year after SBT (SBT-1Y) to measure isometric force. Spontaneous contractile activity and the dose-responses to bethanechol and norepinephrine were studied. Electrical field stimulation (EFS) at varying frequencies (1 to 20 Hz) was evaluated under adrenergic and cholinergic blockade to investigate inhibitory nerves. Spontaneous activity both in the jejunum and ileum in SBT-1Y rats was not different compared to control rats. Sensitivity to bethanechol did not differ between control and SBT-1Y rats in the jejunum or ileum. Sensitivity to norepinephrine, however, was significantly increased after SBT in the ileum but not in the jejunum. During EFS, inhibition was seen at low frequencies, and contractions were induced at high frequencies in all groups. The degree of inhibition did not differ between control and SBT-1Y rats in the jejunum; however, it tended to be increased in the ileum after SBT. The long-term adaptive response of smooth muscle to the extrinsic denervation accompanying SBT differs between the jejunum and the ileum.

Adaptation, Physiological↗
PubMedDate not supplied

Effect of ileojejunal transposition on gastrointestinal motility, gastric emptying, and small intestinal transit in dogs.

There is speculation that enteroglucagon and peptide YY are responsible for mediating the < > known as a suppressive reaction of upper gastrointestinal motility and transit that is induced by the infusion of nutrients into the ileum. We studied changes in motility and transit in dogs with ileojejunal transposition in which the distal ileum is exposed to undigested nutrients. Nine adult mongrel dogs were equipped with strain gauge force transducers placed on the gastric body, antrum, duodenum, and proximal jejunum. Measurements of gastrointestinal motility, gastric emptying, and plasma levels of total glucagon-like immunoreactivity, immunoreactive glucagon, and peptide YY were obtained both before and after either ileojejunal transposition (5 dogs) or sham operation (4 dogs). Postprandial contractions in the gastric antrum and gastric emptying were significantly inhibited after ileojejunal transposition. The inhibitory effect of ileojejunal transposition on antral motor activity was found to correlate with the rise in plasma total glucagon-like immunoreactivity and peptide YY concentrations. However, plasma glucagon levels were unaffected by ileojejunal transposition. These results suggest that hypersecretion of enteroglucagon and peptide YY induced by ileojejunal transposition inhibits postprandial gastric motor function.

Animals↗