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Biomedical subjects

A Miyata

Publications and source records attributed to A Miyata.

At least 145 records · Page 8Linked to original sources
PubMed1991

Tissue distribution of PACAP as determined by RIA: highly abundant in the rat brain and testes.

A heterologous RIA method for pituitary adenylate cyclase activating polypeptide with 38 residues (PACAP38) and a homologous RIA method for a shorter form of PACAP with 27 residues (PACAP27) were established to determine PACAP content in central and peripheral tissues in rats. The highest concentration of radioimmunoassayable PACAP38 was found in the hypothalamus, but other brain regions also contained considerable amounts of PACAP38. PACAP38 concentration in the posterior pituitary was comparable with that in the extrahypothalamic brain, but its concentration in the anterior pituitary was very low. Unexpectedly, the testis contained a high abundance of PACAP38, and the total amount of PACAP in both testes exceeded its content in the whole brain. Reverse phase HPLC suggested that the major testicular PACAP38 immunoreactivity represents PACAP38. Among peripheral tissues, adrenal gland contained the second highest concentration of PACAP. Smaller amounts of PACAP were widely distributed in the digestive tract and other peripheral tissues. The concentration of PACAP in stomach, duodenum and jejunum appeared to be greater than in other portions of the gut. In all tissues, PACAP27 represented only a minor portion of total PACAP immunoreactivity.

Animals↗
PubMed1991

[Three cases of non-traumatic acute subdural hematoma].

The authors present three cases of non-traumatic acute subdural hematoma showing interesting clinical features and operative findings. Case 1: A-50-year-old male was admitted because of sudden headache and epileptic seizure. Computed tomographic (CT) scan showed a right thin subdural hematoma, but cerebral angiography demonstrated no pathological findings, that might cause acute subdural hematoma on the follow-up CT scans. The hematoma changed to a chronic one within only 15 days, which was proved by the operation. Case 2: A 52-year-old male was hospitalized because of loss of consciousness. CT scan revealed a right subdural hematoma without subarachnoid hemorrhage and cerebral angiography demonstrated a right middle cerebral artery aneurysm. The hematoma was surgically proved to be due to rupture of the aneurysm. Case 3: A 52-year-old male was admitted because of headache, vomiting and left motor weakness. CT scan showed a thick right subdural hematoma and right carotid angiography revealed two internal carotid artery aneurysms. It was surgically certified that the subdural hematoma was caused by a tear in a cortical artery attached to the dura, not by the rupture of the aneurysms. Clinical cause and pathogenesis of so-called "non-traumatic" or "spontaneous" acute subdural hematomas were discussed, and the importance of emergency angiography for this condition is stressed.

Carotid Arteries↗
PubMed1990

Isolation of a neuropeptide corresponding to the N-terminal 27 residues of the pituitary adenylate cyclase activating polypeptide with 38 residues (PACAP38).

A novel neuropeptide with 38 residues (PACAP38) was isolated from ovine hypothalamic tissues using the pituitary adenylate cyclase activation in rat pituitary cell cultures as a parameter of the biological activity (Miyata et al, Biochem. Biophys. Res. Commun. 164, 567-574, 1989). From the side fractions obtained during the purification of PACAP38, a shorter form peptide with 27 residues corresponding to the N-terminal 27 amino acids of PACAP38 and amidated C-terminus was isolated and named as PACAP27. Synthetic PACAP27 showed a biological activity of adenylate cyclase stimulation comparable to PACAP38. Moreover PACAP27 which shows a considerable homology with vasoactive intestinal polypeptide (VIP) demonstrated a similar vasodepressor activity as VIP, but the adenylate cyclase stimulating activity was about 1000 times greater than VIP.

Adenylyl Cyclases↗
PubMed1990

Presence of highly selective receptors for PACAP (pituitary adenylate cyclase activating peptide) in membranes from the rat pancreatic acinar cell line AR 4-2J.

We characterized highly selective receptors for PACAP, the pituitary adenylate cyclase activating peptide, in the tumoral acinar cell line AR 4-2J derived from the rat pancreas. PACAP, a novel hypothalamic peptide related to vasoactive intestinal peptide (VIP), was tested as the full natural 38-residue peptide (PACAP-38) and as an N-terminal amidated 27-residue derivative (PACAP-27). The binding sites showed considerable affinity for [125I]PACAP-27 (Kd = 0.4 nM) and PACAP-38, while their affinity for VIP and the parent peptide helodermin was 1000-fold lower. These receptors were coupled to adenylate cyclase, the potency of PACAP-38 and PACAP-27 (Kact = 0.2 nM) being much higher than that of VIP (Kact = 100 nM) and helodermin (Kact = 30 nM). Chemical cross-linking of [125I]PACAP-27 followed by SDS-PAGE and autoradiography revealed a specifically cross-linked peptide with an Mr of 68,000 (including 3000 for one PACAP-27 molecule).

Adenylyl Cyclases↗
PubMed1990

A novel peptide which stimulates adenylate cyclase: molecular cloning and characterization of the ovine and human cDNAs.

A novel neuropeptide which remarkably stimulates adenylate cyclase in rat anterior pituitary cell cultures has been recently isolated from ovine hypothalami by A. Arimura and his collaborators (Biochem.Biophys.Res.Commun.164, 567-574(1989)). This peptide was designated as PACAP38(Pituitary Adenylate Cyclase Activating Polypeptide with 38 residues). In an attempt to investigate physiological implications of PACAP38, we have succeeded in cloning the cDNAs encoding the precursor of PACAP38 from ovine hypothalamus and human testis. An ovine cDNA encodes a protein of 176 amino acids in which PACAP38 is proceeded by a putative signal peptide and a "pro"-region (107 amino acids), and followed by a Gly-Arg-Arg sequence for proteolytic processing and amidation. Deduced amino-acid sequence of human PACAP38 was completely identical to that of the ovine isolated peptide. Cloning of PACAP38 cDNAs confirms the expression of the corresponding mRNAs and the presence of this neuropeptide in ovine hypothalamus and also in human testis.

Adenylyl Cyclases↗
PubMed1990

Oxytocin is the major prolactin releasing factor in the posterior pituitary.

Although the posterior pituitary is known to contain the PRL releasing activity or factor (PRF), its chemical identification has been a matter of dispute. In the present study, we purified PRF in porcine posterior pituitary extracts to chemically determine the primary structure. PRF activity was assessed during purification by the release of immunoreactive PRL from superfused rat pituitary cells. Two hundred seventy porcine posterior pituitaries were boiled, homogenized, and extracted with 2 M acetic acid. The acid extract was precipitated with 67% acetone, and the supernatant was absorbed onto a C18 column. The column was eluted step-wise with 10, 20, 30, 40, 50, and 60% acetonitrile (CH3CN) in 0.1% trifluoroacetic acid (TFA). The greatest PRF activity was recovered in the 30% CH3CN/0.1% TFA fraction and was further purified by ion-exchange chromatography on SP-Sephadex, followed by gel-filtration on Sephadex G-50. The Sephadex G-50 fractions with major PRF activity were finally purified by two cycles of reverse phase HPLC, yielding a single peak of PRF. Amino acid, as well as sequence analyses, indicated that the highly purified PRF was oxytocin. Authentic oxytocin showed the same chromatographic behavior and biological activity as those of the isolated peptide. In another experiment, desalted crude extracts of rat and porcine posterior pituitary tissues were directly chromatographed by reverse phase HPLC, and each fraction was assayed for PRF activity. Only two areas showed PRF activity; the largest activity coeluted with oxytocin and the smaller one co-eluted with vasopressin. The fractions which coeluted with oxytocin also showed oxytocin immunoreactivity, as examined by RIA. The results clearly indicated that the major PRF in these posterior pituitary extracts was oxytocin.

Amino Acid Sequence↗
PubMed1990

Characterization and distribution of binding sites for the hypothalamic peptide, pituitary adenylate cyclase-activating polypeptide.

A novel bioactive peptide was recently isolated from ovine hypothalamus and was named PACAP (pituitary adenylate cyclase-activating polypeptide). PACAP was present in two bioactive, amidated forms, PACAP27 and PACAP38 (27 and 38 amino acids, respectively), and showed a 68% sequence homology with vasoactive intestinal peptide (VIP) in the N-terminal 28 residues. PACAP38 was at least 1000 times more potent than VIP in stimulating adenylate cyclase in pituitary cells, but both peptides exhibited comparable vasodepressor activity. Thus, we sought to determine whether PACAP acts on specific binding sites in the anterior pituitary or other tissues and whether these binding sites are different from those of VIP. Binding of [125I] PACAP27 to freshly prepared rat anterior pituitary membranes in the presence and absence of 212 nM unlabeled PACAP27 was specific, saturable, and more rapid at 22 C than at 4 C. Scatchard analysis of this binding site using increasing doses of unlabeled PACAP27 revealed a single high affinity site with a Kd of 446 +/- 141 pM and a maximum number of sites of 1312 +/- 182 fmol/mg protein. These results do not exclude the possibility of a second pituitary binding site with significantly lower affinity. Unlabeled PACAP38 and PACAP38OH exhibited significantly higher affinity binding (3- to 5-fold) than PACAP27 with a similar number of pituitary sites. A variable distribution of binding sites was observed between PACAP27 and VIP when binding to different tissue membranes was measured with 125I-labeled peptides. Very high specific binding of both PACAP27 and VIP was observed in lung membranes. An almost identical relative magnitude of binding was observed between PACAP27 and VIP in lung, liver, duodenum, ovary, and thymus. However, whereas PACAP27 binding to hypothalamic and pituitary membranes was great, VIP binding to these tissues was almost absent. To determine if VIP and PACAP might share a binding site in peripheral tissues, displacement curves were generated using [125I]PACAP27 binding to lung membranes and VIP, PACAP27, and PACAP38 as unlabeled ligands. VIP was highly potent in displacing [125I] PACAP27 binding in lung membrane, and the IC50 values for all three of these peptides were between 1-10 nM. These results suggest that 1) a saturable, high affinity binding site for PACAP is present on anterior pituitary membranes; 2) PACAP27 and PACAP38, but not VIP, share this binding site in the anterior pituitary and possibly the hypothalamus; and 3) PACAP27, PACAP38, and VIP share a similar or identical binding site on lung membranes and possibly other peripheral tissues.

Animals↗
PubMed1990

[A case of rapidly developed constrictive pericarditis following acute non-specific pericarditis].

A case of constrictive pericarditis which developed within one month after the onset of acute pericarditis was presented. A 3-year-old boy was admitted to our hospital suffering from dyspnea. Pericardectomy was performed 3 weeks after the pericardial drainage. His echocardiograms revealed the progressive thickening of the pericardium, severely restricted ventricular motion in both systole and diastole and paradoxical motion of the interventricular septum. Echocardiography at close intervals is useful for making the diagnosis and decision of the surgical intervention of rapidly developed constrictive pericarditis.

Acute Disease↗
PubMed1989

Isolation of a novel 38 residue-hypothalamic polypeptide which stimulates adenylate cyclase in pituitary cells.

A novel neuropeptide which stimulates adenylate cyclase in rat anterior pituitary cell cultures was isolated from ovine hypothalamic tissues. Its amino acid sequence was revealed as: His-Ser-Asp-Gly-Ile-Phe-Thr-Asp-Ser-Tyr-Ser-Arg-Tyr-Arg-Lys-Gln- Met-Ala- Val-Lys-Lys-Tyr-Leu-Ala-Ala-Val-Leu-Gly-Lys-Arg-Tyr-Lys-Gln-Arg-Val-Lys-Asn-Lys - NH2. The N-terminal sequence shows 68% homology with vasoactive intestinal polypeptide (VIP) but its adenylate cyclase stimulating activity was at least 1000 times greater than that of VIP. It increased release of growth hormone (GH), prolactin (PRL), corticotropin (ACTH) and luteinizing hormone (LH) from superfused rat pituitary cells at as small a dose as 10(-10)M (GH, PRL, ACTH) or 10(-9)M (LH). Whether these hypophysiotropic effects are the primary actions of the peptide or what physiological action in the pituitary is linked with the stimulation of adenylate cyclase by this peptide remains to be determined.

Adenylyl Cyclases↗
PubMed1989

Effects of antiserum against alpha-rat atrial natriuretic polypeptide in spontaneously hypertensive rats.

To clarify the physiological role of endogenous atrial natriuretic polypeptide (ANP), we investigated the effects of specific rabbit antiserum against alpha-rat ANP (alpha-rANP) on hemodynamics, diuresis, and natriuresis in spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY). Intravenous administration of anti-alpha-rANP antiserum caused an obvious rise of mean blood pressure and cardiac output in both SHR and WKY compared with rats administered with normal rabbit serum. Although there was no significant difference in increments of mean blood pressure between SHR and WKY, the increment of cardiac output in SHR was significantly higher than that in WKY. On the other hand, significant reductions in urine output and urinary sodium and potassium excretion lasted for approximately 20 min after administration of the antiserum in both SHR and WKY compared with rats administered with normal rabbit serum. There was no significant difference in these initial maximal decrements between SHR and WKY. These results indicate that endogenous ANP has an important physiological role in the regulation of hemodynamics and water-electrolyte balance in both SHR and WKY. The greater increment of cardiac output in SHR in response to the antiserum suggests that endogenous ANP in SHR may have a stronger cardiosuppressive action that it does in WKY.

Animals↗
PubMed1989

The effects of atrial pacing and ballooning on the plasma concentration of atrial natriuretic peptide in anesthetized dogs with or without vagotomy.

To study the mechanisms of release of atrial natriuretic peptide (ANP), the plasma concentration of ANP, atrial pressure and urinary sodium excretion were determined in anesthetized dogs during balloon inflation in the left atrium or during rapid atrial pacing. The effects of bilateral cervical vagotomy on these variables were also examined. Balloon inflation which elevated the left atrial pressure by more than 4 mmHg increased the plasma concentration of ANP (+40%, p less than 0.05). This increase in ANP concentration was not altered by vagotomy. Rapid atrial pacing at rates of more than 160 beats/min also significantly increased the left atrial pressure (+2.3 mmHg, p less than 0.02), urinary sodium excretion (+45%, p less than 0.05) and plasma concentration of ANP (+130%, p less than 0.05). Vagotomy did not affect these changes. The degree of the increase in plasma ANP concentration was significantly greater during rapid atrial pacing than during intraatrial ballooning. These results suggest that the release of ANP is stimulated in part by elevating the left atrial pressure and in part by increasing the frequency of atrial contractions and that the increase in the plasma ANP concentration is possibly involved in the so-called atrial natriuresis. Furthermore, the release of ANP was proven to be independent of the vagal nerve reflex.

Anesthesia↗
PubMed1989

[Contents and molecular forms of human atrial natriuretic peptide in right and left auricle in patients with heart disease].

Contents and molecular forms of human atrial natriuretic peptide (hANP) in right and left auricle were analyzed by reverse phase high liquid chromatography (RP-HPLC), coupled with radioimmunoassay for hANP. Analyses were done with auricles taken from 4 autopsied cases without heart disease, and 13 patients with heart disease. Both right and left auricular hANP contents in patients with heart disease were higher than those obtained at autopsy. In patients with mitral stenosis (MS) or mitral regurgitation (MR) who have left atrial pressure and/or volume overload, hANP contents in left auricle were higher than those in right auricle. In addition, three types of molecular forms of hANP, (gamma) type, (alpha, beta, gamma) type, (beta, gamma) type, were observed in both right and left atrium. In patients with MS or MR, (beta, gamma) type or (alpha, beta, gamma) type which have beta-hANP immunoreactivity were observed in 8 out of 9 in patients in left auricle, however, in 4 out of 9 patients in right auricle. Our results suggested that the difference of contents and molecular forms of hANP may reflect the pathophysiological role in heart diseases.

Adult↗
PubMed1988

Identification of a 29-amino acid natriuretic peptide in chicken heart.

Morphological and pharmacological observations have suggested that chicken atrial natriuretic peptide (ANP) is different from mammalian ANP. The present survey for the as yet unidentified ANP in chicken heart was performed by monitoring the relaxant effect on chick rectum. From the low molecular weight component of rectum relaxant activity observed in acid extracts of chicken ventricle, a novel 29-amino acid peptide was purified. The identical peptide was also isolated from acid extracts of chicken atrium. The peptide elicited a pharmacological spectrum very similar to that of mammalian ANP, including diuretic-natriuretic and hypotensive activity. Thus, the peptide was designated "chicken alpha-ANP (alpha-chANP)". The complete amino acid sequence determined for the peptide showed remarkable homology with that of mammalian alpha-ANP. However, maximum homology was observed when the peptide was compared with a recently identified porcine brain natriuretic peptide (BNP).

Amino Acid Sequence↗
PubMed1988

Estimation of the secretion rate of atrial natriuretic peptide from the coronary sinus in coronary artery disease.

Although atrial natriuretic peptide (ANP) is known to be secreted through the coronary sinus into the systemic circulation, its actual secretion rate has not been thoroughly investigated. The immunoreactive ANP concentrations in plasma samples from the ascending aorta and coronary sinus in 11 patients with the coronary artery disease were measured and the coronary sinus flow rate using the continuous thermodilution method was simultaneously determined at the time of sampling. These variables were also determined during the intravenous infusion of synthetic alpha-human ANP at 0.025 microgram/kg.min in 7 of the 11 patients. In the basal state, the plasma concentration of ANP was 61 +/- 6 (standard error) pg/ml in the aorta and 541 +/- 40 pg/ml in the coronary sinus, and the coronary sinus flow index was 57.3 +/- 12.3 ml/min.m2. Thus, the secretion rate of ANP was determined to be 14.4 +/- 2.8 ng/min.m2. The secretion rate of ANP correlated significantly with the plasma concentration of ANP in the aorta (r = 0.65, p less than 0.05). The ANP infusion, which decreased pulmonary artery wedge pressure from 8.0 +/- 0.6 to 6.3 +/- 0.4 mm Hg (p less than 0.01), elevated the plasma concentrations of ANP in the aorta and coronary sinus by 701% (p less than 0.001) and 33% (p less than 0.05), respectively, and decreased the secretion rate of ANP by 40% (p less than 0.05). These results suggest that the circulating plasma concentration of ANP may reflect the secretion rate of ANP and that an increase in circulating ANP directly or indirectly reduces ANP secretion.

Aorta↗
PubMed1988

Plasma and right auricle concentrations of atrial natriuretic polypeptide in children with cardiac diseases.

To investigate the atrial natriuretic polypeptide (ANP) levels in congenital heart diseases, we measured plasma immunoreactive ANP (ir-ANP) in 29 patients with left-to-right shunt, and right auricle ir-ANP in 25 patients who underwent operation. The levels of ir-ANP in the pulmonary artery correlated with that in the femoral vein (r = 0.95, P less than 0.001), mean pulmonary arterial pressure (r = 0.74, P less than 0.001) and right atrial pressure (r = 0.53, P less than 0.01). The right auricle ir-ANP level was high in patients with heart failure combined with pressure or volume overload of the right atrium, as observed in tricuspid atresia, complete endocardial cushion defect, and total anomalous pulmonary venous drainage. These results suggest that the production of ANP in the atrium increases as a compensatory or secondary response to persistent release of ANP into the circulation in cardiac diseases.

Adolescent↗
PubMed1988

Responsiveness of the ANP providing system to volume load in conscious dogs.

We examined in detail changes in arterial plasma ANP concentration in response to volume load in conscious dogs. In a 5-min volume load experiment, 18 ml/kg of isosmotic and isooncotic 3% Dextran 40 in saline was infused over a period of 5 min. Mean left atrial pressure (MLAP) increased transiently by 7.6 +/- 0.9 mm Hg. Plasma ANP level (P-ANP) did not significantly increase. Assayed P-ANP levels were corrected for hemodilution. Corrected P-ANP (C-ANP) significantly increased from 206 +/- 17 to 348 +/- 34 pg/ml. However, the level of C-ANP did not reach a steady state. No significant linear correlation was found between increases in MLAP and normalized C-ANP. In a 45-min volume load experiment, the elevated level of MLAP caused by the 5-min volume load was maintained for 40 min by supplemental infusion. C-ANP significantly increased from 196 +/- 18 pg/ml to 435 +/- 73 ng/ml. The level of C-ANP reached a steady state. A close linear correlation was observed between increases in MLAP and normalized C-ANP. However, the peak time of C-ANP lagged 10 min behind MLAP. These results indicate that it takes 10 min for P-ANP to reach a steady state in fully responding to a volume load, and that the long-term volume load is a prerequisite to the response of the ANP providing system.

Animals↗