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Biomedical subjects

K Tsuda

Publications and source records attributed to K Tsuda.

At least 379 records · Page 21Linked to original sources
PubMed1982

Cloning of dihydrofolate reductase gene of Escherichia coli K12.

Resistant strains for trimethoprim, a potent inhibitor of dihydrofolate reductase, were obtained by transforming the ligated products of Escherichia coli K12 DNA and plasmid pBR322 BamH I fragments. The strains carry a 13.6 kbp plasmid, pTP1, which contains the trimethoprim- and ampicillin-resistance determinant genes. The trimethoprim-resistance determinant gene was estimated to consist of more than 500 nucleotides and less than 1,500 nucleotides and was restricted by EcoR I and Sal I. Trimethoprim-, ampicillin-, and tetracycline-resistant plasmids were made in the following way, and the resultant plasmids contained a unique EcoR I "insertional inactivation" site for trimethoprim resistance: the DNA sequences extraneous to the determinant gene of the trimethoprim resistance on BamH I fragment of pTP 1 were eliminated by digestion with a double-strand-specific exonuclease BAL 31, and the resultant fragments were ligated with pBR 322 which had been digested by EcoR I and a single-strand-specific nuclease S1. The strains carrying pTP 1 or trimethoprim-resistant plasmids produced about 10 times more dihydrofolate reductase than control strains. The enhancement of the enzyme production, which is due to an increase in the copy number of the enzyme gene, seems to be responsible for the trimethoprim resistance of the transformed cells.

Cloning, Molecular↗
PubMed1982

Isolation of DNA fragment containing phoS gene of Escherichia coli K-12.

The DNA fragment containing the phoS gene, a regulatory gene for alkaline phosphatase, has been isolated from Escherichia coli K-12 chromosomal DNA by cutting off the DNA with Hind III restriction enzyme and by cloning the gene with plasmid vector pTP 4 which was constructed in this study. The isolated fragment was of about 12.3 kbp and seemed to contain the phoT, glmS, and bgl genes. The 12.3 kbp Hind III fragment was subjected to restriction enzymes EcoR I, BamH I, Sal I, and Pst I, and was found to possess two EcoR I, no BamH I, a Sal I, and four Pst I sites. Partial deletion using these restriction enzymes suggested that the about 6 kbp Hind III-Pst I fragment contained the phoS and phoT genes. Further analysis with other restriction enzymes revealed that the 6 kbp Hind III-Pst I fragment contained a BstE II, two Mlu I and four Hpa I sites. The deletion of these restriction sites using single-strand-specific nuclease S1 suggested that the BstE II and one of Mlu I sites were in the phoT gene, and the BstE II and two Mlu I sites were not in the phoS gene.

Culture Media↗
PubMed1982

The role of endogenous gastric inhibitory polypeptide in the enteroinsular axis.

In order to elucidate the relationship between the release of gastric inhibitory polypeptide (GIP) and insulin, we compared plasma GIP and insulin concentration responses to meal ingestion in normal subjects and patients with various surgical modifications of the food pathway. Nine patients with Billroth I partial gastrectomy (BI), 7 patients with Billroth II partial gastrectomy (BII), and 6 patients with total gastrectomy (TG) were tested. In BI patients the increase in blood glucose was similar to that in normal subjects, but the response was significantly greater in BII and TG patients. In TG patients blood glucose rose significantly higher in response to a standard meal than in all other groups. In BI patients the mean peak GIP level after meal ingestion was significantly higher than in normal subjects. In BII and TG patients an extremely exaggerated GIP response after the meal was observed. The insulin response to feeding was increased only in the BII and TG patients. Since the insulin response was enhanced only when both the glucose and GIP responses were magnified, we conclude that endogenous GIP is a glucose-dependent insulinotropic factor. In addition, from the fact that meal-stimulated GIP release is most marked in patients with total gastrectomy, we conclude that the direct contact of food with the GIP-producing cells is a strong mechanical or chemical stimulus for GIP release.

Adult↗
PubMed1982

Prostaglandin E1: stimulation of somatostatin and insulin responses to glucose from the isolated perfused rat pancreas.

The effect of prostaglandin E1 (PGE1) on insulin and pancreatic somatostatin release was investigated using the isolated perfused rat pancreas. In the presence of 4.4 mM glucose, PGE1 produced a significant augmentation in somatostatin release, but not in insulin release, compared to the effect of glucose alone. PGE1 also augmented somatostatin and insulin secretion induced by 16.7 mM glucose. These results suggest that PGE1 plays a role in the regulation of not only insulin but also pancreatic somatostatin release.

Alprostadil↗
PubMed1981

Effect of truncal vagotomy on pancreatic polypeptide response after intravenous glucose administration.

Intravenous glucose infusion was performed in six dogs with and without truncal vagotomy, and plasma pancreatic polypeptide (PP) responses were compared before and after truncal vagotomy. Following truncal vagotomy, basal PP levels decreased significantly from 286 +/- 64 pg/ml (mean +/- S.E.) to 94 +/- 14 pg/ml (P less than 0.05). Basal plasma insulin and blood glucose levels also tended to be lower, but not significantly. During the infusion of glucose, blood glucose concentrations rose rapidly in both groups and after 15 min reached peak values which were not significantly different from each other. In the vagotomized group the plasma insulin response to intravenous glucose infusion was significantly lower than in the control group. Following intravenous glucose loading, plasma PP concentrations decreased rapidly in both groups, but the PP level in the vagotomized group was suppressed only to 77 +/- 4% of the basal level whereas in the control group it decreased by 45 +/- 8%, significantly lower than in the vagotomized group (P less than 0.01). These results suggest that basal PP is regulated by vagal tonus and that vagus controls, at least in part, suppression by intravenous glucose administration.

Animals↗
PubMed1981

Effects of antisomatostatin and antiglucagon sera on insulin release from isolated Langerhans' islets of rats.

Effects of antisomatostatin and antiglucagon sera on insulin secretion were studied in isolated pancreatic islets of rats. Addition of antisomatostatin or antiglucagon serum to the incubation medium containing 5.5 mM glucose significantly increased insulin secretion from the islets. In contrast, these effect were not apparent when the glucose concentration was elevated to 20 mM. In the presence of antiglucagon serum the free glucagon concentration in the medium was decreased, while the total glucagon was markedly increased, suggesting that the antiglucagon serum caused an increase in glucagon secretion. These results suggest that A- and D-cells may play an important role in regulating insulin release at physiologic glucose concentration.

Animals↗
PubMed1981

Somatostatin, insulin, and glucagon secretion from isolated perfused pancreas of obese rats.

A comparison of the somatostatin with the insulin and glucagon secretions in hypothalamic obesity and genetic obesity was made using the isolated perfused pancreas of rats. In our perfusion experiment, the somatostatin response to 19 mM arginine in the presence of 4.4 mM glucose was significantly greater in both ventromedial hypothalamus (VMH)-lesioned and Zucker fa/fa rats than in their controls, as was the perfusate insulin. The perfusate arginine-stimulated glucagon secretion appeared no different in obese and control rats. Because hyperinsulinemia in vivo and hyperresponses to arginine of perfusate insulin and somatostatin were observed in both VMH-lesioned and Zucker fa/fa rats, whereas the perfusate glucagon secretion in the presence of 4.4 mM glucose was unchanged by obesity, the secretory behavior of some pancreatic hormones seems similar in VMH-lesioned and Zucker fa/fa rats in certain conditions. These results suggest that some abnormalities of pancreatic hormone secretion may be caused by a mechanism common to obesity, whether caused experimentally or genetically.

Animals↗
PubMed1981

Cartilage of I-cell disease.

Biochemical analysis and morphologic observation of the iliac crest cartilage from 8-year-old girl with I-cell disease were performed. Instead of hypertrophic change of chondrocytes in the zone of cartilage-bone junction, there were small atrophic cells having many inclusion bodies accumulated with lamellar materials. Another characteristic finding in this zone was numerous cellular debris in the cartilage matrix. Significantly, a large amount of unsulfated chondroitin (21%) occurred in the cartilage with I-cell disease, and compensatory decrease of chondroitin 4-sulfate (14%) was observed. The percentage of chondroitin and chondroitin 4-sulfate on the control averaged 8.5 and 43%, respectively. The sedimentation profile of the proteoglycans closely resembled that of the normal cartilage.

Cartilage↗
PubMed1981

Hypersecretion of gastric inhibitory polypeptide induced by glucose ingestion in diabetes mellitus.

The response to plasma immunoreactive gastric inhibitory polypeptide (GIP) to oral glucose loading was determined in 10 normal subjects, 10 patients with mild diabetes mellitus, and 10 patients with moderate to severe diabetes mellitus. In normal subjects the mean fasting GIP was 167 +/- 17 pg/ml which rose significantly after glucose loading, reaching the peak value of 513 +/- 44 pg/ml at 30 min. In mild diabetic patients, fasting plasma GIP was not significantly different from that in normal subjects. However, the mean peak GIP level following glucose loading was 683 +/- 71 pg/ml, significantly higher than that in normal subjects (p less than 0.05). In moderate and severe diabetics, oral glucose loading caused an abrupt rise in plasma GIP from the basal level of 304 +/- 31 pg/ml to the peak of 870 +/- 63 pg/ml occurring at 30 min, both of which were significantly higher than the corresponding values in normal subjects (p less than 0.01). These results suggest that GIP response to oral glucose loading is enhanced in diabetic patients in proportion to the degree of their glucose intolerance.

Adolescent↗
PubMed1981

Mucosal secretion of the duodenum in peptic ulcer disease.

Mucosal secretin content of the duodenum was measured using bioptic specimen in healthy controls and patients of peptic ulcer. Immunoreactive secretin in the duodenal mucosa was found greater in healthy controls (7.73 +/- 2.71 ng/mg dry wt., mean +/- S.D.) than in gastric ulcer patients (5.76 +/- 3.51 ng/mg dry wt.) and duodenal ulcer patients (5.54 +/- 2.48 ng/mg dry wt.), but the difference was not significant. There was no significant relationship between mucosal secretin and acid output in these patients.

Adult↗
PubMed1981

Somatostatin-like immunoreactivity in human peripheral plasma measured by radioimmunoassay following affinity chromatography.

Somatostatin-like immunoreactivity (SLI) concentrations were determined in human peripheral plasma using affinity chromatography followed by radioimmunoassay. In normal subjects, fasting SLI ranged from 2.9 to 22.0 pg/ml with a mean +/- SE value of 10.2 +/- 2.1 pg/ml. In totally pancreatectomized or gastrectomized patients, fasting SLI levels were not different from the values in normal subjects. In patients with medullary thyroid carcinoma, fasting SLI ranged from 11.8 to 71.0 pg/ml with a mean of 29.3 +/- 12.3 pg/ml, which was significantly higher than normal values (P less than 0.01). Following meal ingestion, plasma SLI increased significantly in normal subjects from a basal level of 9.1 +/- 2.1 pg/ml to a peak value of 15.4 +/- 2.9 pg/ml (P less than 0.02). These results indicate that radioimmunoassay combined with affinity chromatography provides an accurate method of measuring SLI in human plasma.

Adult↗