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Biomedical subjects

H Yajima

Publications and source records attributed to H Yajima.

At least 307 records · Page 17Linked to original sources
PubMed1980

Hemodynamic response of the pancreas to synthetic chicken VIP in dogs.

The effects of synthetic chicken VIP (an octacosapeptide corresponding to the entire sequence of chicken VIP) on pancreatic blood flow and on systemic arterial pressure was examined in dogs. The relationship between pancreatic blood flow and systemic arterial pressure in response to synthetic chicken VIP was also investigated. Pancreatic blood flow increased promptly and significantly with exogenous synthetic chicken VIP. Synthetic chicken VIP administered in graded doses resulted in dose-dependent increases in both the peak rate of the pancreatic blood flow and the duration of the response of the pancreatic blood flow. Graded doses of synthetic chicken VIP also elicited both a graded increase in the systemic systolic pressure and a decrease in the systemic diastolic pressure. Therefore, synthetic chicken VIP given in graded doses resulted in a dose-dependent augmentation of the maximum pulse pressure. Pancreatic blood flow increased despite a fall in the systemic arterial pressure in response to synthetic chicken VIP. This increase in blood flow lasted significantly longer than the changes in the systemic arterial pressure. It was clarified in this study that synthetic chicken VIP has a biological effect on both the pancreatic blood flow and the systemic arterial pressure. The results of our experiments also suggest that synthetic chicken VIP itself may directly induced vasodilatation of the local vessels in the pancreas.

Animals↗
PubMed1980

Studies on peptides. LXXXVII. Synthesis of an octacosapeptide amide corresponding to the entire amino acid sequence of chicken vasoactive intestinal polypeptide (VIP).

The octacosapeptide amide corresponding to the entire amino acid sequence of chicken VIP was synthesized in a conventional manner, using a new arginine derivative, NG-mesitylene-2-sulfonylarginine, Arg(Mts). Treatment of a fragment, Z(OMe)-Thr-Asp-Asn-Tyr-NHNH2 with methanesulfonic acid or HBr was found to give a product with a low recovery of Asp, after aminopeptidase digestion. Ring closure of the Asp-Asn unit seemed to be responsible for this phenomenon. Deprotection with HF or TFA exhibited definitely less such a tendency. In the final step of the synthesis, all protecting groups, including the Mts group, were removed by HF in the presence of m-cresol and the deprotected peptide was purified by ion-exchange chromatography on CM-cellulose followed by isoelectric focusing in Ampholine pH 9--1. Synthetic peptide exhibited the identical Rf value with that of natural chicken VIP and was active as the natural peptide.

Amides↗
PubMed1979

Studies on peptides. LXXXI. Application of a new arginine derivative, NG-mesitylene-2-sulfonylarginine, to the synthesis of substance P and neurotensin.

A new devised arginine derivative, NG-mesitylene-2-sulfonylarginine, Arg(Mts), was employed for the synthesis of hypothalamic substance P and neurotensin. The former was obtained in 74% yield by treatment of the protected undecapeptide amide, Z - Arg(Mts) - Pro - Lys(Z) - Pro - Gln - Gln - Phe - Phe - Gly - Leu - Met(O)-NH2, with methanesulfonic acid in the presence of anisole followed by reduction of the sulfoxide with 2-mercaptoethanol. The latter was obtained in 54% yield by the similar treatment of the protected tridecapeptide ester, Z - Pyr - Leu - Tyr - Glu(OBzl) - Asn - Lys(Z) - Pro - Arg(Mts) - Arg(Mts) - Pro - Tyr - Ile - Leu - OBzl, with methanesulfonic acid. As scavenger, a mixture of anisole-thioanisole-o-cresol (1:1:1, by vol.) was employed to suppress the side reaction, O-mesitylene-2-sulfonation of the Tyr residue.

Amino Acid Sequence↗
PubMed1979

Radioimmunoassay of methionine enkephalin and interference by brain factor of immunoreactivity and opiate receptor binding activity.

We developed a radioimmunoassay of methionine-enkephalin (met-enk) which was found to be highly specific to the peptide and 1 pmol was the detection limit. Interference by the following peptides was practically negligible; leucine-enkephalin, LAP- or CNBr-treated met-end, alpha- and beta-endorphins. Morphine and its congeners were totally inert. Measurement of met-enk in rat brain P2 fraction revealed besides met-enk, the presence of the factor which cross-reacted with the antiserum and also appeared to bind with the brain opiate receptor. Though the nature of the factor has not yet been characterized, it is suggested that for qualitative assessment of the tissue level of met-enk, a method to selectively inactivate either the peptide or the factor should be developed first.

Animals↗
PubMed1978

Analgesia by enkephalins injected into the nucleus reticularis gigantocellularis of rat medulla oblongata.

Methionine-enkephalin (0.2--20 microgram/rat) and leucine-enkephalin (1--20 microgram/rat) produced a dose-related and naloxone-antagonizable analgesia in the tail-pinch test, when microinjected into the nucleus reticularis gigantocellularis (NRGC) and nucleus reticularis paragigantocellularis (NRPG) of the medulla oblongata of the rat. The median analgesic doses were 1.4 and 4.8 microgram/rat for methionine- leucine-enkephalin, respectively. The possibility that the endogenous enkephalins play a part as pain control substances or modulators in the NRGC and NRPG was discussed.

Analgesics↗
PubMed1978

Basic study of nasal provocative test. Second report: assessment method on provocative reaction.

Because no simple and precise method is available to test intensity of the reaction resulted from a nasal provocative test in diagnosis of nasal allergy, comparisons were made among the conventional test methods of rhinoscopy (RS), rhinomanometry (RM) and the carbon powder elimination test (CET) devised by the authors. The rhinoscopy shows high positive rates and has advantages being free from any special equipment, prolonged time or the patients' cooperation, but also had disadvantages such as requirement of skill of examiner and problems in objectivity. The carbon powder elimination test is a preferable method in that it is not only equipped with the advantages of the rhinoscopy but also makes up for its disadvantages, but a disadvantage of CET is requirement of longer time than RS. Rhinomanometry had lower positive rates and requires a special equipment, prolonged time and the skillful patients' cooperation. The disadvantage is that its impracticableness in many patients--26% impracticableness even in adult patients, but the method is fully objective. From these findings the value of Carbon Powder Elimination Test in judging provoked reactions is recognized.

Adolescent↗
PubMed1978

Effect of intravenous infusion of somatostatin on gastric, pancreatic and biliary secretion in the rat.

The effect of somatostatin (GH-RIH) on gastric, pancreatic and biliary secretion was examined in the anesthetized rats. Intravenous infusion of the hormone, in graded doses ranging from 1 to 16 microgram/kg/hr, produced a dose dependent inhibition of pentagastrin, 1.5 microgram/kg/hr, induced acid secretion, reaching about 54% of control level at the dose of 16 microgram/kg/hr. Somatostatin, 4, 16 and 64 microgram/kg/hr, inhibited the pancreatic juice volume stimulated by intravenous injection of secretin, 1 u/kg, as a bolus. Somatostastin, 2, 8, 32 and 128 microgram/kg/30 min, did not change the bile flow rate in control period. Somatostatin may play a physiological role in the regulation of the secretory process of the stomach and pancreas.

Animals↗