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Biomedical subjects

S Ohashi

Publications and source records attributed to S Ohashi.

At least 163 records · Page 9Linked to original sources
PubMed1990

Thermal stability of dihydrofolate reductase and its fused proteins with oligopeptides.

Two fused proteins of dihydrofolate reductase (DHFR) with oligopeptides were prepared by a recombinant DNA method. One of these, DHFR-IQI, has three (Ile-Gln-Ile) and the other, DHFR-lek, has eight (Ile-Arg-Met-Tyr-Gly-Gly-Phe-Leu) additional amino acid residues at the C terminals; in both proteins, Cys152 of wild DHFR is replaced by Glu. The thermal transition of the proteins was measured by CD and DSC at pH 7.0 and compared with that of wild DHFR. The results show that the thermal stability of DHFR-IQI is the same as that of the wild DHFR and that of DHFR-lek is less than that of the former two DHFRs. Analysis of the DSC data of DHFR-IQI indicates that the thermal transition is a three-state one. Data from both DSC and CD measurements suggest the association of DHFR-lek molecules.

Calorimetry, Differential Scanning↗
PubMed1990

Plasma growth hormone, insulin-like growth factor-I, and milk production responses to exogenous human growth hormone-releasing factor analogs in dairy cows.

Responses of plasma growth hormone (GH) and insulin-like growth factor-I (IGF-I), and milk production to subcutaneous (sc) injection(s) of two synthetic human growth hormone-releasing factor (hGRF) analogs were studied in dairy cows. Two mg of each hGRF analog dissolved in 5 ml saline per cow were injected into the shoulder area of each experimental animal, and jugular venous blood samples were collected via an indwelling catheter or by venipuncture. Plasma GH and IGF-I concentrations were measured by radioimmunoassay methods. In dry cows, the mean concentration of plasma GH after a single sc injection of hGRF analogs rose to 22.0-28.3 ng/ml at about 5 h from 1.4-1.7 ng/ml at 0 h (just before injection), and returned to the level before injection after 10-12 h. On the other hand, the plasma IGF-I began to increase after a lag of 4-6 h following a single injection of hGRF analogs, and reached maximum values of 71.1-89.4 ng/ml at 20 h from 43.7-46.4 ng/ml at 0 h. The IGF-I concentration at 24 h after a single injection of hGRF analogs was still higher than the value for the dry cows given saline. In lactating cows, the plasma concentration of GH at 2 h after daily sc injections of hGRF analogs during 14 consecutive days (an injection period) was higher than those for the lactating cows which received saline. Also, during the injection period, the concentration of IGF-I was higher in the lactating cows which received hGRF analog injections than in the cows which received saline injections. During the last 7 days of the injection period, the administration of hGRF analogs increased the mean milk yield by 11-19% in comparison with those for the saline injected cows. A positive correlation was observed between the mean plasma IGF-I concentration and the mean milk yield in the lactating cows treated with hGRF analogs throughout the injection and a postinjection (11 consecutive days after cessation of hGRF analog injection) periods. The results demonstrate that a single sc injection of hGRF analogs stimulates both GH release and the circulating level of IGF-I in dry cows, and that daily sc injections of hGRF analogs over 14 days enhance milk production, and plasma GH and IGF-I levels in lactating cows.

Animals↗
PubMed1990

Glucagon-like peptide-1(7-37) does not stimulate either hepatic glycogenolysis or ketogenesis.

Recent Studies have demonstrated that glucagon-like peptide-1 (GLP)(7-37) has more potent insulinotropic activity than glucagon. We therefore examined the effect of GLP-1(7-37) on liver metabolism using rat liver perfusion system. Ten nM GLP-1(7-37) did not affect glucose, ketone body and cAMP outputs from the perfused liver. Whereas, the same dose of glucagon stimulated these outputs significantly. When 10 nM GLP-1(7-37) perfused 5 min before the administration of 10 nM glucagon, the above stimulatory effects of glucagon were not affected. These results indicate that truncated GLP-1 has no effect on hepatic glycogenolysis and ketogenesis dissociating from its potent insulinotropic activity.

Animals↗
PubMed1990

Effects of truncated glucagon-like peptide-1 on pancreatic hormone release in normal conscious dogs.

The effects of truncated glucagon-like peptide-1 (GLP-1) on insulin and glucagon release were examined in unanesthetized normal dogs. A bolus injection of GLP-1(7-36)amide elicited a transient increase in the plasma insulin level, which brought about a decrease in the plasma glucose level. The degree of increase in plasma insulin levels with GLP-1(7-35)OH or GLP-1(7-37)OH was less than that induced by GLP-1(7-36)amide. The plasma glucagon level did not increase in spite of mild hypoglycemia. The infusion of graded doses of GLP-1(7-36)amide (6, 36, 120 ng.kg-1.min-1 every 30 min) did not change the plasma glucose, insulin or glucagon levels significantly. The degree of increase in the plasma glucose level induced by iv glucose infusion (12 mg.kg-1.min-1) was reduced by coinfusion of GLP-1(7-36)amide (6 ng.kg-1.min-1), although the degree of increase in the plasma insulin level was the same as that in a control experiment (coinfusion of the vehicle). Coinfusion of GLP-1(7-36)amide (60 ng.kg-1.min-1) caused an augmented increase in the plasma insulin level and a reduced increase in the plasma glucose level during iv glucose infusion (17 mg.kg-1.min-1) compared with the control experiment. The degree of decrease in the plasma glucagon level during iv glucose infusion was not affected by the coinfusion. The degree of increase in the plasma glucagon level induced by insulin hypoglycemia and the profile of the plasma glucose level at that time were not affected by the infusion of GLP-1(7-36)amide.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Reduced insulinotropic effects of glucagonlike peptide I-(7-36)-amide and gastric inhibitory polypeptide in isolated perfused diabetic rat pancreas.

The pathophysiological role of incretin in diabetes mellitus has not been established. We therefore examined the effects of glucagonlike peptide I-(7-36)-amide (truncated GLP-I) and gastric inhibitory polypeptide (GIP) on insulin and glucagon release from isolated perfused pancreases of diabetic rats (12-14 wk of age, mean +/- SE fasting plasma glucose 8.9 +/- 0.6 mM, n = 25) after an injection of 90 mg/kg streptozocin on the 2nd day after birth and compared the results with those of nondiabetic control rats. In diabetic rats, the infusion of 1 nM GLP-I or GIP in perfusates with varying glucose concentrations (2.8, 5.6, 8.3, 11.1, or 22.2 mM) caused a nearly equal degree of insulin stimulation from a similar basal insulin level. Meanwhile, basal and GLP-I- or GIP-stimulated insulin release increased in correlation with the ambient glucose concentration in nondiabetic rats. The degree of stimulation of insulin release at glucose concentrations of 5.6 mM in diabetic rats was approximately 33% that of nondiabetic rats. The stimulation potency was the same between GLP-I and GIP. The insulin treatment for diabetic rats (5 U/kg NPH insulin at 0900 and 2100 for 6 days) brought only a slight improvement in the glucose dependency of GLP-I-stimulated insulin release. The effects of GLP-I and GIP on glucagon release were completely opposite. GLP-I suppressed release; GIP stimulated it. In diabetic rats, the degree of suppression by GLP-I and stimulation by GIP were almost the same with similar basal glucagon levels in the perfusate with varying glucose concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Antitumor activity of polyanion and its application for drug delivery system of antitumor drugs].

Polyanionid copolymer of divinyl ether and maleic anhydride (DIVEMA) with narrow molecular weight distribution was synthesized and tested of its antitumor activity. DIVEMA showed a significant antitumor activity against colon 26 adenocarcinoma and FSaI fibrosarcoma transplanted in syngenic mice. Furthermore, DIVEMA was used as a polymeric drug carrier of antitumor drugs to reduce side effects and enhance the antitumor activity of the drugs. Adriamycin and neocarzinostatin were attached covalently to DIVEMA and the polymeric conjugates showed higher antitumor activity than the corresponding mother drugs against P 388 leukemic mice.

Adenocarcinoma↗
PubMed1990

[Endoscopic ultrasonography for assessing the horizontal spread of invasive gastric cancer].

The subjects were 64 cases of gastric cancer. In all 64 cases, resected specimens (formalin fixed) were subjected to endoscopic ultrasonographic examination by the water immersion method in order to assess the horizontal spread of the invasive gastric cancer. Ultrasonographic findings were compared with the histopathological findings of resected specimens. The tumor which invaded the submucosa or deeper layers was visualized as low echogenicity region in the third layer (corresponding to the submucosa) or deeper layers. The horizontal spread of the low echogenicity region represented that of the tumor or the associated fibrosis, but not the tumor itself. In the cases showing echo patterns which were characteristic of the peptic ulceration in the tumor focus (Type II-1, II-2, UL), the horizontal spread of cancer invasion in the submucosal layer or deeper layers (L Ca) was smaller than that of low echogenicity region depicted by ultrasonography (L U). In the other (Type II-3, III, A, B) cases, L Ca was almost comparable to L U.

Gastric Mucosa↗
PubMed1989

Tryptic digestion of NADH dehydrogenase from alkalophilic Bacillus.

The alkalophile NADH dehydrogenase (NADH: 2,6-dichlorophenolindophenol oxidoreductase) [EC 1.6.99.3] consists of two identical subunits of 65 kDa, and each subunit contains the catalytic and liposome-binding regions. On treatment with trypsin, the polypeptide exhibiting the liposome-binding property in one of the subunits was digested to form an enzymatically active hetero-dimer (40 and 65 kDa), and then the polypeptide in the other subunit was digested to form an active homo-dimer (40 and 40 kDa). The hetero-dimer bound to liposomes, but the homo-dimer did not. Kinetic analysis showed that removal of one or two of the polypeptides in the enzyme slightly affects its kinetic parameters. For all the enzyme species, NAD inhibited competitively with respect to NADH and non-competitively with respect to 2,6-dichlorophenolindophenol. The partially determined amino acid sequence of this alkalophile enzyme suggested that (i) a long random-coiled peptide (58 amino acid residues) or a portion of the peptide is located between the polypeptides with liposome-binding and catalytic properties, (ii) the polypeptide exhibiting liposome-binding property is in the amino terminal region of the enzyme, (iii) the amino acid sequences around the subtilisin and trypsin cleavage sites of the peptide are hydrophilic and on the surface of the protein molecule and therefore are susceptible to digestion, and (iv) the FAD-binding site is located near the amino terminal region of the catalytic region.

Amino Acid Sequence↗
PubMed1989

Comparison of the effects of glucagon-like peptide-1-(1-37) and -(7-37) and glucagon on islet hormone release from isolated perfused canine and rat pancreases.

Recently, it has been demonstrated that glucagon-like peptide-1 (GLP-1)-(7-37) possesses a potent insulinotropic activity. In this paper, we compared the effects of GLP-1-(1-37) and -(7-37) and glucagon on insulin, glucagon, and somatostatin release from isolated perfused canine and rat pancreases under the perfusate condition of 5.5 mM glucose plus arginine. With canine pancreas perfusion, 1 nM GLP-1-(7-37) was more potent in stimulating insulin and somatostatin release than was the same dose of glucagon [stimulation to 375 +/- 36% vs. 302 +/- 28% of the basal level for insulin (P less than 0.05); 724 +/- 129% vs. 311 +/- 33% of the basal level for somatostatin (P less than 0.01)]. GLP-1-(1-37) (1 nM) did not stimulate either insulin or somatostatin release. GLP-1-(7-37) (1 nM) decreased the glucagon level of the effluent perfusate to 67.2 +/- 3.4% of its basal level; but 1 nM GLP-1-(1-37) did not. Glucagon (1 nM) decreased GLP-1-like immunoreactivity to 64.0 +/- 5.2% of its basal level. With rat pancreatic perfusion, the minimal dose for stimulation of insulin release was 100 nM for GLP-1-(1-37), 0.1 nM for GLP-1-(7-37), and 1 nM for glucagon, respectively. Glucagon release was partially inhibited by 100 nM GLP-1-(1-37) and 1 and 10 nM GLP-1-(7-37). The present results indicate that 1) since GLP-1-(7-37) is released from the intestine, it might be an important incretin candidate along with gastric inhibitory peptide; and 2) the release of proglucagon-derived peptides from pancreatic A-cells is regulated by autofeedback through glucagon and GLP-1.

Animals↗
PubMed1989

Comparison of the effects of various C-terminal and N-terminal fragment peptides of glucagon-like peptide-1 on insulin and glucagon release from the isolated perfused rat pancreas.

Truncated glucagon-like peptide-1 (GLP-1) possesses a potent stimulatory activity for insulin secretion and a slight inhibiting activity for glucagon secretion. The aim of this paper is to examine the activities of N- and C-terminal fragments of GLP-1 using a rat pancreas perfusion system. Concerning the N-terminal portion, GLP-1(7-37) amide elicited a clear insulinotropic activity at 0.1 or 1 nM with the perfusate containing 5.5 mM glucose and 5 mM arginine, while 10 nM GLP-1-(1-37) amide, -(6-37) amide, and -(8-37) amide did not. Concerning the C-terminal portion, GLP-1-(7-37) amide, -(7-37), and -(7-36) amide had a similar potency of insulinotropic activity, and GLP-1-(7-35) was less potent; 0.1 nM GLP-1-(7-35) did not stimulate insulin release, nor did 10 nM GLP-1-(7-20). Glucagon release was significantly suppressed by 1 and 10 nM GLP-1-(7-37) amide, 10 nM GLP-1-(7-37), and 1 nM GLP-1-(7-36) amide. Other fragment peptides of GLP-1, including GLP-1-(7-35), had no effect. From these results it is concluded that histidine at position 7 of GLP-1 as a free N-terminal amino acid is very important in GLP-1's insulinotropic activity and probably in glucagon-inhibiting activity, and that C-terminal amidation and three C-terminal amino acids are less important for these activities.

Animals↗
PubMed1989

[Effectiveness of local delivery of ofloxacin using controlled-release strips (PT-01) in periodontal patients. Part 1. PT-01 application among treatment plans for periodontal disease].

Three different sites which have more than 5 mm pocket were randomly selected in each periodontal patient and were divided into three groups: PT-01 treated site, placebo treated site and control site. After application of either PT-01 or placebo twice for two weeks, subgingval scaling and root planing were performed. Then PT-01 and the placebo were applied weekly to the periodontal pocket for four weeks and clinical and microbiological evaluations were made. The results obtained were as follows: 1. On clinical evaluation, significant improvement was found in the PT-01 treated site in comparison with the placebo treated and/or control site. 2. On microbiological evaluation, slight improvement was found in the PT-01 treated site, whereas there was no significant difference among the three sites.

Delayed-Action Preparations↗
PubMed1989

Endoscopic ultrasonography in the assessment of invasive gastric cancer.

Endoscopic ultrasonographic (EUS) images of 174 cases of gastric cancer were examined to assess the depth of tumor invasion. Comparison was made between the depth of the changes shown in the multi-layered image produced by ultrasonography and the actual depth of invasion. Cases showing ultrasonographic changes extending deeper than the actual tumor were found to have fibrosis associated with peptic ulceration within the tumor focus. In such cases the echo images chiefly depicted the form and nature of the fibrosis, and the images were so characteristic that they could be classified into patterns. In the other cases the depth of tumor invasion could be almost precisely determined by detecting to which layer the changes shown by EUS extended.

Fibrosis↗
PubMed1989

[A study on gastric and small intestinal aberrant pancreas by endoscopic ultrasonography--with special reference to comparison with histological appearance].

To obtain characteristic findings of gastrointestinal aberrant pancreas by endoscopic ultrasonography (EUS), we made comparison between endoscopic ultrasonograms and histological findings in 5 cases (6 lesions) of resected gastric aberrant pancreas and 1 case (1 lesion) of small intestinal one. By EUS, gastrointestinal aberrant pancreases were delineated as hypoechoic masses with blurred boundary containing fine scattered hyperechoic spots, and also there were thickening of the fourth layer below the mass. Occasionally, there were some duct-like structures within the mass or marginal lobular structures. Moreover, the ultrasonographic patterns of aberrant pancreases were classified into 2 types, that is, M and S types. On histological examination, M type cases, in which the mass attached to the thickened fourth layer by EUS, were corresponded to acinar type and the pancreatic acinar cells penetrated into the proper muscle layer of the gastrointestinal wall, whereas S type cases, in which the mass was separated from the fourth layer, to ductal or mixed type. We conclude, therefore, that not only making the accurate diagnosis of aberrant pancreas but also drawing an inference of its histological type might become possible by EUS.

Adolescent↗
PubMed1987

[Clinicopathological study of colorectal cancer in young adults including a case of cancer family syndrome].

During the last 6 years, we examined 402 cases (including 5 cases in their 20's and 17 cases in their 30's) of colorectal cancer. We compared three groups (cases in their 20's, cases in their 30's, and cases over 40 years old), and had the following results. Cases in their 20's had a higher rate of familial history of colorectal cancer, and the cancer was located mainly in the proximal colon. Well differentiated and moderately differentiated adenocarcinoma was dominant in the cases in their 30's and in those over 40 years old. On the other hand mucinous adenocarcinoma and signet ring cell carcinoma was dominant in the cases in their 20's. A case of cancer family syndrome is also presented.

Adenocarcinoma↗
PubMed1986

Response of growth hormone release to human growth hormone-releasing factor and its analogs in the bovine.

Responses of growth hormone (GH) release to synthetic human growth hormone-releasing factor (hGRF)-44-NH2 analogs were determined, and the GH-releasing potency based on dose per kg of body weight (bw) was compared with that of hGRF-44-NH2 in female dairy calves. Four- and 12-month-old calves were injected intravenously with 0.25 microgram of hGRF-44-NH2 or its analogs per kg of bw. Blood samples were collected before, and during 180 min after each injection, and plasma GH concentrations were measured by radioimmunoassay. Areas under the GH response curves for 180 min after injection of hGRF-44-NH2 and its analogs were used as an index of the GH-releasing potency of each peptide. The GH-releasing potency of hGRF(1-26)-NH2 was significantly lower than that of hGRF-44-NH2 (P less than 0.05). On the other hand, hGRF(1-29)-NH2 possessed similar potency to hGRF-44-NH2. [D-Tyr1]-hGRF-44-NH2 showed prolonged GH-releasing activity, though its potency was similar to that of hGRF-44-NH2. Also, [D-Ala2]-hGRF(1-29)-NH2 exhibited prolonged GH-releasing activity, and its potency was 2.5 (P less than 0.05) and twice (P less than 0.05) as great as that of hGRF-44-NH2 and hGRF(1-29)-NH2, respectively. These results demonstrate that the N-terminal 29 amino acid residues of hGRF possess the activity site required for full GH release in vivo, and [D-Ala2]-hGRF(1-29)-NH2 has longer and greater activity, on a dose basis, than hGRF-44-NH2 in the calves.

Animals↗