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Biomedical subjects

Y Umeda

Publications and source records attributed to Y Umeda.

At least 91 records · Page 5Linked to original sources
PubMed1990

[Double filtration plasmapheresis in case of Goodpasture's syndrome].

This article describes a case of Goodpasture's syndrome controlled by double filtration plasmapheresis (DFPP) combined with steroid and immunosuppressant therapy. A 48-year-old male, clerk, complaining of fever, dry cough and macroscopic hematuria, was admitted to our hospital. Microscopic hematuria was first pointed out at age 40 on an annual check up. His laboratory data on admission revealed severe anemia, azothemia, macroscopic hematuria and proteinuria. His chest radiograph and CT revealed diffuse nodular densities in bilateral lung fields. Specimens obtained by transbronchial lung biopsy and open renal biopsy revealed linear deposition of IgG by direct immunofluorescent antibody methods. Circulating antiglomerular basement membrane antibody level determined with radioimmunoassay was 1.8% on admission, but one week later it elevated to 5.6% with progression of dyspnea, hypoxemia, and renal failure. Steroid pulse therapy and a total of 6 double filtration plasmaphereses were performed in the first month. Subsequently hypoxemia and dyspnea disappeared, and the chest radiograph of the 40th hospital day showed no abnormal shadows. Two months later recurrence of pulmonary hemorrhage was noticed. Immunosuppressant administration (Cyclophosphamide 100 mg/day) and a total of 10 DFPP procedures were performed with success. By DFPP, circulating anti-GBM antibody fell rapidly to within normal ranges, and anti-GBM antibody level elevated in removed plasma. We think DFPP is effective to remove circulating anti-GBM antibody in Goodpasture's syndrome.

Anti-Glomerular Basement Membrane Disease↗
PubMed1989

Evoked release of endogenous amino acids from rat striatal slices and its modulation.

The release of endogenous gamma-aminobutyric acid (GABA), glutamate and aspartate stimulated by high K+ was studied by superfusing rat striatal slices. Stimulation with 5 min of 30 mM K+ was applied twice (S1 and S2) at a 20 min interval. The maximum release of GABA following stimulation was 40 (at S1) and 26 (at S2) times greater than the basal release. S1 and S2 each produced a maximum release of almost same magnitude for both glutamate and aspartate (about 2.5 times basal release). The removal of Ca2+ from the perfusion medium reduced the maximum release of these amino acids by more than 80% without affecting basal release significantly. Striatal slices were next stimulated in the same way after the addition of apomorphine or haloperidol to the perfusion medium. Apomorphine, 10 or 100 microM, reduced the K+-evoked release of GABA (by 24% at S1 and 35% at S2 with 10 microM; by 37% at S1 and 47% at S2 with 100 microM) but failed to affect the simultaneous release of glutamate and aspartate. Haloperidol (1 microM) reduced the S1-induced release of GABA but had no significant effect on the subsequent S2-induced release. The evoked release of aspartate or glutamate did not respond significantly to haloperidol, but there was a tendency to a decrease in aspartate release similar to the decrease seen for GABA release, particularly with S1. Based on these results, we discuss the property of GABA, aspartate and glutamate as neurotransmitters and the possible dopaminergic regulation of the release of these amino acids.

Amino Acids↗
PubMed1989

Role of atrial natriuretic peptide in the diuresis of a newborn infant with the syndrome of inappropriate antidiuretic hormone secretion.

A fullterm infant had fetal distress and stained amnion. He underwent an exchange blood transfusion at 12 hours after birth because of hyperbilirubinemia. He developed oliguria combined with high urine osmolality during the first 27 hours of life despite normal creatinine clearance. The diagnosis of the syndrome of inappropriate antidiuretic hormone secretion (SIADH) was made on the basis of high urine osmolality, low plasma osmolality and elevated plasma arginine vasopressin (AVP) concentration. We determined the plasma atrial natriuretic peptide (ANP) concentration for the first 4 days of life. After 27 hours after birth, urine volume increased while plasma AVP concentration remained high. On the other hand, plasma ANP concentration gradually increased after 27 hours of life. We speculate that ANP may play an important role in producing the spontaneous diuresis in the newborn infant with SIADH.

Atrial Natriuretic Factor↗
PubMed1989

Absent effect of plasma vasopressin on rat brain blood flow during hemorrhage.

We investigated whether a reflex increase in plasma vasopressin level due to hemorrhagic hypotension affects brain blood flow. In 60 lightly anesthetized, artificially ventilated rats, the flow was determined with radiolabeled microspheres. We found excellent maintenance of blood flow throughout all brain regions during the hypotensive state (71 mmHg on average), and such maintenance of flow was not modulated at all by a supramaximal intravenous dose of the selective vasopressin V1-receptor antagonist [d(CH2)5 Tyr-(Me)]AVP. The latter finding also implies that the V1 antagonist failed to unmask the vasodilator type actions of V2 receptors on the maintenance of flow during hemorrhagic hypotension. These were true also when the cervical sympathetic bundles were severed bilaterally. The plasma level of endogenous vasopressin was increased during hypotension, ranging from 118 to 973 pg/ml. Despite this increase, the brain blood flow was entirely independent of the plasma vasopressin level in all the brain regions studied. We conclude that the brain circulation of rats can maintain its blood flow during hemorrhagic hypotension without any apparent contribution from a concomitant reflex increase in plasma vasopressin. Despite our negative results for the brain blood flow, the possible segmental effects of circulating vasopressin on the brain arterial caliber remain to be clarified under conditions of hemorrhagic hypotension.

Animals↗
PubMed1989

Characterization of calcitonin gene-related peptide (CGRP) receptors in guinea pig lung.

Receptors for calcitonin gene-related peptide (CGRP) in the lung membranes of guinea pig were characterized by using a millititer plate precoated with polyethylenimine. Specific binding of 125I-CGRP was time-dependent, rapid, and reversible, and the binding increased linearly with increasing concentrations of membrane protein. Scatchard analysis revealed two classes of CGRP binding sites: high affinity sites with a KD value of 7.17 x 10(-11) M and a Bmax of 364 fmol/mg protein and low affinity sites with a KD value of 1.7 x 10(-8) M and a Bmax of 39594 fmol/mg protein. Furthermore, the specific binding of 125I-CGRP was dissociated in the presence of GTP or Gpp(NH)p, suggesting that CGRP receptors in guinea pig lung membranes were coupled to the guanine nucleotide regulatory protein. Scatchard analysis of CGRP binding in the presence of GTP revealed selective inhibition of the binding to high affinity binding sites. Unlabeled CGRP displaced the binding of 125I-CGRP to guinea pig lung membranes with an IC50 value of 3.1 x 10(-10) M. In contrast, salmon calcitonin and human calcitonin displaced the binding at 600-fold higher concentrations. We suggest that both low and high affinity binding sites for CGRP exist in the lung membranes of the guinea pig, and the high affinity binding sites for CGRP may be coupled to GTP binding regulatory protein.

Animals↗
PubMed1989

Surfer's ear in Japan.

Fifty-one Japanese professional surfers were examined in order to analyze surfer's ear. Forty-one cases (80%), 71 ears, were diagnosed as surfer's ear. In 19 cases (37%), 30 ears, the external auditory canals had stenosed by more than 50%. In general, surfer's ear begins to appear after 5 years and is further aggravated by continued surfing. The age at which surfing is taken up has no influence on the appearance of surfer's ear. Surfers who surf on northern (colder) coasts have severer surfer's ear than those who frequent the southern (warmer) coasts.

Adolescent↗
PubMed1989

Inhibition of natural killer activity by calcitonin gene-related peptide.

The effect of calcitonin gene-related peptide (CGRP) on natural killer (NK) cell activity in spleen cells from Balb/c mice and nude mice was studied. CGRP dose-dependently (10(-9) to 10(-7) M) inhibited NK activity of spleen cells from both strains of mice. This inhibitory effect was observed at the effector to target ratios of 12.5:1 to 100:1. Maximum inhibition by 10(-7) M CGRP was about 60%. The inhibition of NK activity by CGRP was also observed in anti-Thy 1.2 plus complement treated Balb/c spleen cells. Furthermore, when cells were treated with 10(-9) to 10(-7) M CGRP the concentration of intracellular cyclic AMP increased in spleen cells of nude mice. The characteristics of these cells were similar to those of NK cells, (1) being petri dish and nylon wool nonadherent, (2) expressing asialo GM1 antigen, and (3) lacking readily detectable Thy 1 antigen and immunoglobulin. In addition, the intravenous injection of asialo GM1 completely abolished NK activity in spleen cells from nude mice and the increase in intracellular cyclic AMP in spleen cells by CGRP was less in spleen cells from mice given an anti-asialo GM1 injection. Our present study suggests that CGRP inhibits NK cell activity by increasing the intracellular cyclic AMP concentration. CGRP may be implicated in the regulation of NK function.

Animals↗
PubMed1989

Platelet vasopressin receptor in patients with chronic renal failure.

The vasopressin binding to intact platelet from patients with chronic renal failure (CRF) was investigated in relation to the abnormalities in platelet aggregation. The immunoreactive arginine vasopressin (AVP) in platelet-free plasma (PFP) but not in platelets was significantly higher in non-dialyzed patients with CRF than in normal subjects. Binding studies using [3H]AVP demonstrated a decreased number of binding sites (Bmax) on platelets from patients with CRF compared to normal controls with no significant difference in affinity (Ka). A significant diminution of the maximal percentage aggregation with AVP was found in patients with CRF. An inverse relation between Bmax and the PFP AVP levels and a highly significant relation between Bmax and the maximal percentage aggregation with AVP in patients with CRF and normal controls were observed. At 4 weeks after the introduction of hemodialysis in patients with CRF, the PFP AVP levels decreased and Bmax increased significantly, and the maximal percentage aggregation tended to increase. The present findings suggest that a reduced number of AVP receptors on platelets might account for decreased platelet aggregation with AVP, and the elevated plasma AVP levels might induce a down-regulation of the AVP receptor number on platelets in patients with CRF.

Adult↗
PubMed1989

[A case of sarcoidosis presenting ataxic hemiparesis as an initial clinical manifestation].

A case of sarcoidosis presenting ataxic hemiparesis was reported. A 25-year-old man was admitted to Kanto Teishin Hospital because of slight weakness and dysesthesia in the right side of his body. His physical findings were normal. Neurological findings disclosed mild right hemiparesis (MMT 4+), cerebellar signs and mild dysesthesia in the same side. Laboratory findings were within normal limits except for elevated serum ACE and lysozyme. Chest roentgenogram showed bilateral hilar lymphadenopathy and TBLB disclosed sarcoid granuloma. Though brain CT, brain MRI and cerebral angiography were within normal limits, the neurological features were thought to be due to sarcoidosis. They disappeared along with the decrease of ACE and lysozyme. This is the first report of ataxic hemiparesis due to sarcoidosis, and it is interesting in that ataxic hemiparesis, which is one of signs of diseases in central nervous system, is the first manifest clinical feature of sarcoidosis.

Adult↗
PubMed1988

Atrial natriuretic peptide gene expression and its secretion by pneumocytes derived from neonatal rat lungs.

Using a primary culture of pneumocytes derived from neonatal rat lungs, we investigated the synthesis and secretion at transcriptional and peptide levels of pulmonary rat(r) atrial natriuretic peptide (ANP). Total RNA extracted from pneumocytes contained a hybridizing RNA band of the same size as atrial rANP mRNA. Immunoreactive (IR)-rANP content in pneumocytes was 0.5% of that in atrial myocytes, and 8.6% of that in ventricular myocytes, while the secretory rate from pneumocytes was about 7% of atrial and ventricular myocytes. Triiodothyronine (T3, 5 x 10(-10) to 5 x 10(-8) M), dexamethasone and testosterone (5 x 10(-9) to 5 x 10(-8) M) significantly stimulated the synthesis of IR-rANP by pneumocytes in a dose-dependent manner. However, the stimulatory effect exerted by T3 on rANP synthesis, unlike in the case of cardiocytes, was much more potent than that of dexamethasone, as evidenced by the significant difference in potency at both transcriptional and peptide levels. The present study suggests that ANP secreted from lungs may at least in part contribute to circulating ANP pool, and that the tissue-dependent difference of sensitivity to thyroid hormone may play an important role in the regulation of developmental ANP gene expression in mammalian lungs.

Animals↗
PubMed1988

Inhibition of mitogen-stimulated T lymphocyte proliferation by calcitonin gene-related peptide.

The effect of calcitonin gene-related peptide (CGRP) on mouse lymphocyte proliferation stimulated by mitogens was studied. CGRP (10(-10)-10(-7) M) dose-dependently inhibited the proliferative response of mouse lymph node cells and spleen cells stimulated by T cell mitogens concanavalin A (Con A) and phytohemagglutinin (PHA), whereas a B cell mitogen lipopolysaccharide (LPS) did not inhibit this response. The maximal inhibition by this peptide was 50% to 80% at 10(-8) and 10(-7) M. The addition of 10(-8) and 10(-7) M CGRP to lymph node cell cultures 24 hr after stimulation with Con A or PHA also had a significant inhibitory effect on the proliferative response. Furthermore, in the same concentration range (10(-10)-10(-7) M) CGRP increased intracellular cyclic AMP concentration in nylon wool nonadherent cells, but not in nylon wool adherent cells. CGRP had no significant effect on intracellular cyclic GMP concentration. In addition, specific binding of CGRP was observed in mouse spleen cells. Our present study suggests that CGRP inhibits the proliferative response of T lymphocytes to the mitogens by interacting with cell receptors coupled with adenylate cyclase. CGRP may be implicated in the regulation of T cell function.

Animals↗
PubMed1988

Heart with circulatory failure secretes and processes atrial natriuretic peptide in a manner different from normal heart.

The role of catecholamine in atrial natriuretic peptide (ANP) secretion and its secretory mechanism in normal humans is not well defined; therefore, we studied the relationship among ANP, catecholamine, and atrial pressures in 25 patients without cardiovascular disease and in 35 patients with chronic congestive heart failure (CHF, 20 in mitral valve disease and 15 in dilated cardiomyopathy). In patients without cardiovascular disease, right atrial pressure at rest showed a positive correlation (r = 0.80, p less than 0.001) with ANP concentration, whereas left atrial pressure did not. The relation narrowed (r = 0.82) when the bicycle ergometer exercise in the supine position was conducted. Neither adrenalin nor noradrenalin significantly correlated with ANP concentration. In patients with mitral valve disease and dilated cardiomyopathy, the significant relations (r = 0.56 p less than 0.001, r = 0.85 p less than 0.001, respectively) between left atrial pressures and ANP concentrations at rest were observed, and following exercise, induced more significant relations. Right atrial pressures did not correlate positively with ANP concentrations. The increments of ANP concentrations induced by exercise load were markedly reduced compared with those of patients without cardiovascular disease. Although concentrations of both noradrenalin and adrenalin in patients with mitral valve disease and dilated cardiomyopathy at rest were much higher than those without cardiovascular disease, only noradrenalin had a highly positive correlation with ANP concentrations (r = 0.88 p less than 0.001, r = 0.78 p less than 0.001, respectively). Furthermore, the circulating ANP molecular weight forms in all patients studied were analyzed by gel chromatography coupled with radioimmunoassay.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Platelet vasopressin receptor in essential hypertension.

The specific vasopressin receptor of V1 vascular subtype, which mediates platelet aggregation, has been found on human platelets. We investigated the binding characteristics using tritiated arginine vasopressin [3H]-AVP and platelet aggregation with AVP turbidometrically in normal subjects, patients with WHO class II essential hypertension and patients with malignant-phase hypertension. In essential hypertensives Bmax was significantly higher than that in normal subjects, but there were no differences in affinity and the maximal percentage aggregation between them. In malignant-phase hypertensives Bmax and maximal percentage aggregation were significantly lower than those in normals and essential hypertensives, although there was no difference in the affinity between them. With radio-immunoassay, the mean platelet-free plasma AVP level was significantly higher in malignant-phase hypertensives than those in normals and essential hypertensives, whereas there was no difference in mean platelet AVP levels between them. In essential hypertensives Bmax and maximal percentage aggregation did not change, but in malignant-phase hypertensives Bmax increased significantly and maximal percentage aggregation tended to normalize after treatment.

Arginine Vasopressin↗
PubMed1988

Characterization of human platelet vasopressin receptor and the relation between vasopressin-induced platelet aggregation and vasopressin binding to platelets.

Immunoreactive AVP was found to be much higher in platelets than in platelet-free plasma (PFP) in normal subjects (12.8 +/- 6.3 versus 1.7 +/- 0.8 fmol/ml). AVP levels in PFP were appreciably elevated in parallel with the elevation of plasma osmolality induced by the acute osmotic stimulation, while the AVP levels in platelets did not change before and after the stimulation. Binding studies on intact platelets demonstrated specific binding sites for [3H]AVP. The specific binding was time, temperature and concentration-dependent, saturable and reversible, with the maximal binding capacity (Bmax) of 169.9 +/- 14.4 sites/platelet and affinity of 4.84 +/- 1.15 x 10(8)M-1. The affinity constants for unlabelled AVP, lysine vasopressin (LVP), oxytocin (OT) and dDAVP were 9.0, 8.5, 7.4 and 6.6, respectively, and the inhibition constant for d(CH2)5Tyr(Me)AVP (V1-antagonist) was 7.7. There was a highly significant correlation between the affinity constants of AVP analogues and their relative vasopressor activities in vivo, whereas no such correlation was found between the affinity constants and antidiuretic activities. AVP caused platelet aggregation with the maximal aggregation of 48.0 +/- 25.1% at 230 nM of AVP. A significant correlation was observed between the maximal percentage aggregation and Bmax of [3H]AVP to intact platelets. These results suggest that the platelet vasopressin receptor belongs to the V1 vascular subtype and mediates platelet aggregation.

Adult↗
PubMed1988

Role of calcium and protein kinase C in ANP secretion by cultured rat cardiocytes.

The secretory mechanism of rat atrial natriuretic peptide (rANP) was studied in vitro with the use of primary culture of atrial myocytes from neonatal rats. Norepinephrine, phenylephrine, and carbamylcholine stimulated immunoreactive (IR) rANP secretion, whereas neither angiotensin II, arginine vasopressin, nor isoproterenol affected its secretion. The stimulatory effects of carbamylcholine and phenylephrine were blocked by atropine and prazosin, respectively. 12-O-tetradecanoylphorbol-beta-acetate (TPA), protein kinase C activator, induced a dose-dependent increase in IR rANP secretion, and TPA combined with Ca2+ ionophore ionomycin produced a synergistic effect. Ca2+-channel agonist BAY K 8644 also stimulated IR rANP secretion, the effect of which was blocked by Ca2+-channel antagonist nifedipine. These data suggest that alpha 1-adrenergic and muscarinic cholinergic agonists have direct action on rat cardiocytes to stimulate ANP secretion that involves receptor-mediated mobilization of intracellular Ca2+ and activation of protein kinase C.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1988

Synthesis of histargin and related compounds and their inhibition of enzymes.

A novel method for the synthesis of histargin and its analogs is described. It includes two kinds of N-alkylation reactions that prevent the formation of side products. The inhibition of enzymes by these compounds was also measured. Some of the compounds strongly inhibited carboxypeptidase B, carboxypeptidase A, carboxypeptidase N (kininase I), and angiotensin converting enzyme.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1987

Ventricular myocytes from neonatal rats are more responsive to dexamethasone than atrial myocytes in synthesis of atrial natriuretic peptide.

Using the primary culture of neonatal rat ventricular myocytes, synthesis and secretion of rat atrial natriuretic peptide (rANP) were studied. Ventricular myocytes in culture, although contained less amounts of cellular immunoreactive (IR)-rANP, secreted substantial amounts of IR-rANP at a rate comparable to that of atrial myocytes. Dexamethasone markedly stimulated synthesis and secretion of IR-rANP by cultured ventricular myocytes in a dose-dependent manner (10(-10)-10(-6) M), of which effect was far more potent than that in atrial myocytes. Testosterone and triiodothyronine also stimulated synthesis and secretion of ventricular IR-rANP to the extent comparable to that of atrial IR-rANP. The present study suggests that tissue-dependent difference in glucocorticoids sensitivity plays an important role in the regulation of developmental ANP gene expression in mammalian heart.

Age Factors↗