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Biomedical subjects

H Yajima

Publications and source records attributed to H Yajima.

At least 289 records · Page 16Linked to original sources
PubMed1982

[Left ventricular hypertrophy in hypertensive and athlete's hearts: echocardiographic and vectorcardiographic characteristics].

The difference in the patterns of left ventricular hypertrophy (LVH) between the athlete's heart (Judo player: Judo-Ath group) and the hypertensive heart (HT group) was studied using vectorcardiography and echocardiography. The both groups were classified into two types based on the pattern of a QRS loop vector in the horizontal plane, respectively. One type (type II) satisfied the vectorcardiographic criteria of LVH by Upshaw, and the other (type I) did not satisfy it. The subjects composed of 12 Ath-I, 18 Ath-II, 10 HT-I and 16 HT-II. In the Ath-I, the characteristic vectorcardiogram was demonstrated in the horizontal plane, where an increased amplitude of an initial QRS vector was in the right and anterior direction. A mean ratio of the thickness of the interventricular septum to left ventricular posterior wall (IVSTd/PWTd) was 1.20 (p less than 0.001) in their echocardiograms. In HT-I, on the other hand, a decreased amplitude of an initial anterior vector and an increased amplitude of a posterior vector were observed in the horizontal plane. IVSTd and PWTd did not increase in these patients. These results indicated that an increased amplitude of an initial QRS vector in Ath-I is a reflection of the increased IVSTd. In type II, both IVSTd and PWTd were symmetrically increased. Concerning a spatial maximum QRS magnitude and left ventricular mass (LV mass), there was a significant correlation between the two only in HT-II (r = 0.75, p less than 0.01). It was concluded that there was some vectorcardiographic and echocardiographic differences between the left ventricular hypertrophic patterns of the athlete's heart and the hypertensive heart.

Adult↗
PubMed1982

Studies on peptides. CXI. Synthesis of chicken gastrin-releasing peptide.

The heptacosapeptide amide corresponding to the entire amino acid sequence of chicken gastrin-releasing peptide (cGRP) was synthesized similarly to the synthesis of porcine GRP by assembling six peptide fragments followed by deprotection with 1 M trifluoromethanesulfonic acid-thioanisole in TFA. A new carboxyl-activating reagent, thiazolidine-2-thione, was preferentially adopted for preparation of necessary fragments. The synthetic cGRP, purified by ion-exchange chromatography, followed by partition chromatography, was active as the synthetic porcine GRP, when plasma immunoreactive gastrin level was examined in rats. No obvious difference was observed when synthetic and natural cGRP preparations were compared by HPLC, immunochemical property and biological activity in dogs.

Amino Acid Sequence↗
PubMed1981

Motilin-antimotilin reaction reveals two antigenic determinants in motilin.

The reaction of motilin with four rabbit antimotilin sera raised by immunization with synthetic porcine motilin-bovine serum albumin conjugate was studied with respect to various binding parameters and specificity. All four antisera exhibited an extremely high degree of specificity and high affinity (K greater than 10(11) M-1) for porcine motilin. Studying the various synthetic motilin fragments. These antisera appeared to contain binding sites reacting strongly with the N-terminal sequence in which the first three amino acid residues are essential for high affinity binding. One of the antisera, R-3-6, appeared to contain approximately 20% of its binding sites with high affinity for C-terminus-containing fragments. These results suggest that motilin possesses two antigenic domains along its primary structure; one contains the N-terminal tripeptide and the other contains the C-terminal nanopeptide as essential parts. Thus, in addition to heterogeneity in affinity, a given antibody preparation may be heterogenous with respect to the specificity along the sequence of a peptide. Gel filtration studies of the methanol extracts of human and dog plasma indicated that an immunoreactive motilin-like material with a molecular size similar to natural porcine motilin was measured by our routine radioimmunoassay.

Animals↗
PubMed1981

Identification, characterization and distribution of motilin immunoreactivity in the rat central nervous system.

Motilin-immunoreactivity was evaluated in rat brain using 15 different antisera and by combining gel filtration, high pressure gel filtration and reverse phase high pressure liquid chromatography with radioimmunoassay. Gel filtration chromatography demonstrated a high molecular weight and low molecular weight form of immunoreactive motilin. The high molecular weight form predominated in brain while the low molecular weight peptide was the predominant form of duodenum. The low molecular weight immunoreactive motilin was indistinguishable from synthetic porcine motilin by gel filtration and high molecular weight gel filtration. Low molecular weight rat motilin could, however, be distinguished from synthetic porcine motilin by high pressure liquid chromatography and certain antisera. Immunological results suggest that the slight structural difference may be in the N-terminal portion of the molecule. Immunoreactivity was measured in grossly and microdissected regions of the rat brain. The peptide had quite a unique distribution as highest concentrations are observed in the cerebellum. High concentrations were also observed in hypothalamic nuclei. Particularly high concentrations were noted in the organum vasculosum lamina terminalis. Lowest motilin concentrations in the rat brain were in the pons and the medulla. The distribution of motilin in rat brain suggests that it may have roles in regulating both neuroendocrine and neurological processes.

Animals↗
PubMed1981

Active uptake of substance P carboxy-terminal heptapeptide (5-11) into rat brain and rabbit spinal cord slices.

We previously reported that nerve terminals and glial cells lack an active uptake system capable of terminating transmitter action of substance P (SP). In the present study, we demonstrated the existence of an active uptake system for SP carboxy-terminal heptapeptide, (5-11)SP. When the slices from either rat brain or rabbit spinal cord were incubated with [3H](5-11)SP, the uptake of (5-11)SP into slices was observed. The uptake system has the properties of an active transport mechanism: it is dependent on temperature and sensitive to hypoosmotic treatment and is inhibited by ouabain and dinitrophenol (DNP). In the brain, (5-11)SP was accumulated by means of a high-affinity and a low-affinity uptake system. The Km and the Vmax values for the high-affinity system were 4.20 x 10(-8) M and 7.59 fmol/10 mg wet weight/min, respectively, whereas these values for the low-affinity system were 1.00 x 10(-6) M and 100 fmol/10 mg wet weight/min, respectively. In the spinal cord, there was only one uptake system, with a Km value of 2.16 x 10(-7) M and Vmax value of 26.2 fmol/10 mg wet weight/min. These results suggest that when SP is released from nerve terminals, it is hydrolysed into (5-11)SP before or after acting as a neurotransmitter, which is in turn accumulated into nerve terminals. Therefore, the uptake system may represent a possible mechanism for the inactivation of SP.

Animals↗
PubMed1981

Possible mechanisms of the triphasic effects of neurotensin on the rat blood pressure.

Neurotensin administered intravenously in a dose of 1 nmole/kg produced triphasic blood pressure responses in anesthetized rats: the first depressor, second pressor and third depressor responses. The first depressor response was significantly suppressed by treatment of animals with a mixture of diphenhydramine and metiamide or chronic administration of compound 48/80, but was not modified by treatment with atropine, phentolamine, yohimbine, propranolol, sulpiride and adrenalectomy. The second pressor response was abolished by phentolamine, yohimbine and adrenalectomy. The second phase response was also markedly reduced by diphenhydramine in reserpinized rats and chronic administration of compound 48/80. The third depressor response was blocked by treatment of animals with diphenhydramine or chronic administration of compound 48/80. These results suggest that neurotensin may produce an immediate depressor response (the first phase) partly through a histamine-mediated process, and the second pressor response is produced by catecholamines released from the adrenal medulla through a histamine-mediated process. The third depressor response appears to be mediated mainly by histamine. The participation of mast cells as an origin of histamine which mediates these processes is suggested.

Adrenalectomy↗
PubMed1981

Specific binding of 125I-salmon calcitonin to rat brain: regional variation and calcitonin specificity.

Rat brain particulate fraction was found to contain binding sites for 125I-Salmon Calcitonin-I (125I-SCT). Maximum binding occurred in the physiological pH range of 7.25-7.5. The binding reaction proceeded in a temperature-dependent manner. Binding sites were broadly distributed among the various rat brain regions and considerable regional differences existed in the affinity and density as detected by Scatchard analysis. The highest affinity was recorded in the case of the hypothalamus and the lowest in the case of the cerebellum. The KD (nM) and Bmax (pmole/mg protein) estimated for the binding to four regions were as follows: hypothalamus: 1.4 and 0.19, midbrain, hippocampus plus striatum: 1.5 and 0.08, pons plus medulla oblongata: 3.0 and 0.15 and cerebellum: 8.3 and 0.20. Using a particulate fraction of rat brain void of cerebellum and cortices, a binding assay for calcitonins was developed. Binding of 125I-SCT was inhibited by unlabeled salmon, [Asu1,7]-eel and porcine calcitonins in a dose-dependent manner and the IC50s were 2.0, 8.0 and 30 nM, respectively. The IC50s were comparable to those estimated using a kidney particulate fraction. Human calcitonin, beta-endorphin and substance P were weak inhibitors of the binding. Other peptides, drugs and putative neurotransmitters tested (totally 23 substances) failed to inhibit the binding at concentrations of 1.0 microM. The physiological significance of brain binding sites for calcitonin, with the possibility that the brain may possess endogenous ligands for these sites are discussed.

Animals↗
PubMed1981

Mechanism of the excitatory action of motilin on isolated rabbit intestine.

Synthetic motilin caused a dose-dependent contraction on isolated rabbit intestinal segments, including the duodenum, ileum, and rectum. The contraction of duodenum was significantly greater than that in the ileum or rectum. In the duodenum, motilin was approximately 100 times as potent as acetylcholine on molar basis. The motilin-induced contractions were not influenced by atropine, chlorpheniramine, cimetidine, phentolamine, propranolol, cinanserin, 1-sar-8-ala-angiotensin II, or aspirin. Motilin did not affect the contraction induced by transmural electrical stimulation or acetylcholine. The response to motilin was unaffected by acetylcholine. Removal of Ca++ from bathing media or verapamil suppressed the motilin-induced contractions to a significantly greater extent than the contractions induced by acetylcholine. Thus, it may be concluded that motilin produces intestinal contractions by acting directly on smooth muscles, but not by acting on pharmacologically known drug receptors nor by releasing neurotransmitters such as endogenous acetylcholine. Motilin does not appear to modify autonomic nerve functions.

Acetylcholine↗
PubMed1981

Relationship between development of fibrosis and hemodynamic changes of the pancreas in dogs.

Studies were conducted to investigate the relationship between development of fibrosis and hemodynamic changes in the pancreas in dogs. The basal blood flow rate in the atrophied, fibrotic pancreas was preserved at almost the same level as in the normal pancreas. Fibrotic pancreas responded to VIP with increased blood flow, but not to administration of secretin. On the other hand, normal pancreas showed a brisk increase of blood flow in response to both of these agents. Our findings suggest that direct arterial acinar blood flow per gram of acini decreases prominently, whereas direct arterial flow to the islets per gram of islet is well maintained after the development of pancreatic fibrosis. It is also suggested that secretin acts indirectly by stimulating metabolic activity of the acinar cells with a secondary increase in blood flow, whereas VIP has a direct effect on the pancreatic vasculature.

Animals↗
PubMed1981

Studies on peptides. CII. Synthesis of a heptacosapeptide amide corresponding to the entire amino acid sequence of gastrin-releasing peptide.

The heptacosapeptide amide corresponding to the entire amino acid sequence of gastrin-releasing peptide (GRP) was synthesized by assembling seven peptide fragments followed by deprotection with a new reagent system, IM trifluoromethanesulfonic acid-thioanisole in TFA. The deprotected peptide was purified by ion-exchange chromatography on CM-cellulose followed by partition chromatography on Sephadex G-25. The latter was found to remove effectively the Met (O) derivative of GRP. The highly purified synthetic GRP was active as synthetic bombesin on the molar basis. A new carboxyl-activating reagent, thiazoline-2-thione, was employed for preparation of the necessary fragments.

Amino Acid Sequence↗
PubMed1980

Further characterization of the binding of substance P to a fraction from rabbit brain enriched in synaptic membranes.

1. The present experiments were designed to further characterize the specific [3H]substance P (SP) binding to membrane fractions from rabbit brain. 2. The specific binding was resistant to treatment with proteolytic enzymes whereas phospholipase A(0.7 unit/ml), C(0.025 unit/ml) and D(6.2 unit/ml) reduced the specific binding without decreasing total binding. Neuraminidase (0.01 unit/ml) decreased total binding as well as the specific binding. 3. High concentration of Triton X-100 reduced the specific binding whereas deoxycholate, at 0.05%, reduced both total and the specific binding. 4. Na+ (50--200 mM) reduced the specific binding, depending on the concentrations employed, whereas K+ decreased the specific binding at 10 and 100 mM. The binding was reduced considerably by 100 mmol/l of CaCl2. 5. From these results it is suggested that the specific [3H]SP binding sites in membrane fractions from rabbit brain could be phospholipids.

Animals↗
PubMed1980

Effect gamma-melanotropin (gamma-MSH) on the conditioned behavior.

Effects of a dodecapeptide containing the gamma-MSH sequence on two types of conditioned behaviors were investigated. This peptide enhanced the avoidance response in poorly-performing mice, while it suppressed the self-stimulation lever pressing in rats. At higher doses, the peptide induced slight convulsions of a myoclonic type. The significance of these behavioral changes has not been assessed, but the results suggest that gamma-MSH may have some physiological function in the central nervous system.

Amino Acid Sequence↗