Biomedical subjects

Y Hirata

Publications and source records attributed to Y Hirata.

At least 109 records · Page 6Linked to original sources

PubMed2000

Cardiovascular pharmacological studies on JTV-506, a new potassium channel opener. 1st communication: effects on myocardium and vasculature.

The effects of JTV-506 ((-)-(3S,4R)-2,2-bis(methoxymethyl)-4-[(1,6-dihydro-1-methyl-6-oxo-3- pyridazinyl)amino]-3-hydroxychroman-6-carbonitrile hemihydrate, CAS 170148-29-5), a novel coronary vasodilator, on hemodynamics, cardiac function and cardiac oxygen consumption were evaluated in anesthetized dogs. In anesthetized, open-chest dogs, JTV-506 (0.3-10 micrograms/kg i.v.) induced a marked increase in coronary blood flow in a dose dependent manner, while at these doses it had smaller effects on vertebral and mesenteric blood flow and almost no effect on renal blood flow. JTV-506 (1-10 micrograms/kg i.v.) showed a tendency to decrease oxygen consumption of the heart and elevate myocardial oxygen pressure without cardiac suppression. Effects of JTV-506 on hemodynamics and the respiratory system following i.v. administration (0.3-300 micrograms/kg) were investigated in spontaneously breathing anesthetized dogs. The effective dose to induce hemodynamic changes was more than 3 micrograms/kg. JTV-506 did not have a crucial influence on electrocardiogram. JTV-506 caused marked increase in coronary blood flow and myocardial oxygen pressure with slight change in blood pressure. It is concluded that JTV-506 is a potent vasodilator, with particularly pronounced effect on vasculature of the heart. These results suggest that JTV-506 may be useful in the treatment of angina pectoris.

Anesthesia↗

PubMed2000

Cardiovascular pharmacological studies on JTV-506, a new potassium channel opener. 2nd communication: effects on blood pressure in conscious animals.

The effects of JTV-506 ((-)-(3S,4R)-2,2-bis(methoxymethyl)-4-[(1,6-dihydro-1-methyl-6-oxo-3- pyridazinyl)amino]-3-hydroxychroman-6-carbonitrile hemihydrate, CAS 170148-29-5), a novel coronary vasodilator, on blood pressure were evaluated in conscious dogs and rats. In conscious dogs, JTV-506 (0.01-1 mg/kg p.o.), levcromakalim (0.01-1 mg/kg p.o.) and nifedipine (3-30 mg/kg p.o.) elicited an increase in double product, whereas nicorandil (1-10 mg/kg p.o.) did not affect the double product. The JTV-506-induced increase in double product was abolished by a beta-blocker, propranolol, suggesting that this increase in double product may be due to augumentation of heart rate by sympathetic nerves which mediate the baroreflex. The doses at which JTV-506 increased coronary blood flow in a previous study were lower than the doses required to increase the double product. JTV-506 did not have a crucial influence on electrocardiogram. In conscious rats, orally administered JTV-506, levcromakalim, nicorandil and nifedipine reduced blood pressure and increased heart rate dose dependently. These effects were more remarkable in hypertensive rats than in normotensive rats. JTV-506, a new potassium channel opener, seems to be relatively free of any hemodynamic effects.

Animals↗

PubMed2000

Well-differentiated liposarcoma of the hand. Case report.

Malignant lipomatous tumours of the hands are extremely rare. A 62-year-old man complained of an enlarging, soft, painless mass in his left hand. Magnetic resonance imaging showed a fatty tumour with irregular septa, and an incisional biopsy showed it to be a well-differentiated liposarcoma. The tumour was resected en bloc and he had a course of external beam radiotherapy. Apart from a slight reduction in grip strength he was well 15 months later with no sign of recurrence.

Hand↗

PubMed2000

Peritoneal and peripheral B-1-cell populations in patients with endometriosis.

OBJECTIVE: The purpose of this study was to investigate the frequency of B-1 cells in the peritoneal cavity and peripheral blood of patients with endometriosis. MATERIALS AND METHODS: We examined 31 patients with endometriosis and 14 normal nonpregnant women. Peripheral blood cells and peritoneal exudate cells (PECs) were stained with FITC or PE-labeled anti-CD5/CD19 monoclonal antibodies. Immunofluorescence analysis was performed using a flow cytometer. The significance of differences between the patient and control groups was determined by the non-parametric Mann-Whitney test. RESULTS: There was no significant difference in the percentages of B-1 cells in the peripheral blood of women with and without endometriosis (median, 22.7%; range, 4.7-92.3% vs median, 20.05%; range, 11.1-12.6%, respectively). Endometriosis patients with antinuclear antibodies (ANAs) demonstrated significantly elevated B-1 cells compared to both endometriosis patients without ANAs and normal controls (p < 0.005 and p < 0.05, respectively). Endometriosis patients demonstrated significantly higher B-1 cell populations (B-1 cells/total B-cell ratio) in PECs than did non-endometriosis patients (p < 0.05). CONCLUSIONS: The peripheral B-1-cell population in patients with endometriosis is related to ANA production. B-1 cells might play important roles in the development of endometriosis through autoantibody production.

Adult↗

PubMed2000

Can PET data differentiate Alzheimer's disease from vascular dementia?

The present study endeavored to differentiate Alzheimer's disease (AD) from vascular dementia (VaD) by comparing the metabolic and hemodynamic parameters. Positron emission tomographic (PET) studies were carried out in 13 patients with probable AD and 20 patients with VaD. PET findings were not included in the diagnostic criteria of AD or VaD. Using oxygen-15 labeled compounds, cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO2), oxygen extraction fraction (OEF), cerebral blood volume, and vascular transit time (VTT) were measured quantitatively during the resting state. To evaluate vascular reactivity (VR), CBF was also measured during 7% CO2 inhalation. Regional CBF from the parietal cortex positively correlated with the neuropsychological scores in both AD and VaD groups. The typical parietotemporal pattern of hypoperfusion and hypometabolism was observed in the AD group, whereas the frontal lobe including the cingulate and superior frontal gyri were predominantly affected in the VaD group. The occipital cortex was preserved in both groups. A significant increase of the OEF was found in the parietotemporal areas in the AD group. No significant prolongation was seen with VTT. There was a marked difference in VR between the two groups: VR was depleted in the VaD group, whereas VR was normal in the AD group. The increased OEF with preserved vascular reserve seen in AD may implicate participation of a vascular factor in the pathogenesis of AD, possibly at the capillary level. Thus, PET provides important functional information in discriminating AD from VaD by comparing the patterns of hypoperfusion and/or hypometabolism, and in the understanding of the underlying hemodynamic pathophysiology.

Aged↗

PubMed2000

Dose calculation for asymmetric photon fields with independent jaws and multileaf collimators.

We have developed a simple method for dose calculation in dual asymmetric open and irregular fields with four independent jaws and multileaf collimators. Our calculation method extends the scatter correction method of Kwa et al. [Med. Phys. 21, 1599-1604 (1994)] based on the principle of Day's equivalent-field calculation. The scatter correction factor was determined by the ratio of the derived doses of a smaller asymmetric open field or irregular field to a larger symmetric field. The algorithm with the scatter correction method can be calculated from output factors, tissue maximum ratios, and off-axis ratios for conventional symmetric fields. The doses calculated by this method were compared with the measured doses for various asymmetric open and irregular fields. The agreement between the calculated and measured doses for 4 and 10 MV photon beams was within 0.5% at the geometric center of the asymmetric open fields. For the asymmetric irregular fields with the same geometrical center, agreement within 1% was found in most cases.

Mathematics↗

PubMed2000

Identification and analysis of the K5 gene of Kaposi's sarcoma-associated herpesvirus.

Kaposi's sarcoma-associated herpesvirus (KSHV), or human herpesvirus 8 (HHV-8), belongs to the gammaherpesvirus subfamily and encodes approximately 80 open reading frames (ORFs). Among them are a few candidates for immediate-early genes (e.g., K5). We developed a monoclonal antibody (MAb), 328C7, against the K5 antigen. This MAb reacted with the K5 gene product by immunoscreening of a cDNA library from BCBL-1 cells, and this result was confirmed by transfection of the K5 ORF into Cos-7 cells. After induction of lytic infection by treatment with 12-O-tetradecanoylphorbol-13-acetate, MAb 328C7 reacted with an antigen in the cytoplasm of BCBL-1 and BC-3 cells as early as after 4 h of induction. Immunoelectron microscopy showed that the K5 antigen was situated mainly in the endoplasmic reticulum but was not present on the virion or in the nucleus. Northern blotting with a K5-specific probe revealed a single transcript of 1.2 kb, while Western blotting showed the antigen to be a 36-kDa polypeptide. The 5' and 3' ends were then determined by rapid amplification of cDNA, followed by sequencing of RACE products, and a splice was revealed upstream of the K5 ORF. K5 expression was unaffected by the respective DNA and protein synthesis inhibitors phosphonoformic acid and cycloheximide plus actinomycin D, confirming its immediate-early nature. Transient-transfection assays showed that the K5 promoter was transactivated by ORF 50 (KSHV Rta), a homolog of Epstein-Barr virus Rta, but the K5 gene product exhibited no transregulation of its own promoter or those of DNA polymerase and the human immunodeficiency virus type 1 long terminal repeat. This is the first such analysis of an immediate-early gene product; determination of its specific biological function requires further investigation.

Animals↗

PubMed2000

Yeast glycogen synthase kinase 3 is involved in protein degradation in cooperation with Bul1, Bul2, and Rsp5.

The yeast Saccharomyces cerevisiae has four genes, MCK1, MDS1 (RIM11), MRK1, and YOL128c, that encode glycogen synthase kinase 3 (GSK-3) homologs. The gsk-3 null mutant, in which these four genes are disrupted, shows temperature sensitivity, which is suppressed by the expression of mammalian GSK-3beta and by an osmotic stabilizer. Suppression of temperature sensitivity by an osmotic stabilizer is also observed in the bul1 bul2 double null mutant, and the temperature sensitivity of the bul1 bul2 double null mutant is suppressed by multiple copies of MCK1. We have screened rog mutants (revertants of gsk-3) which suppress the temperature sensitivity of the mck1 mds1 double null mutant and found that two of them, rog1 and rog2, also suppress the temperature sensitivity of the bul1 bul2 double null mutant. Bul1 and Bul2 have been reported to bind to Rsp5, a hect (for homologous to E6-associated-protein carboxyl terminus)-type ubiquitin ligase, but involvement of Bul1 and Bul2 in protein degradation has not been demonstrated. We find that Rog1, but not Rog2, is stabilized in the gsk-3 null and the bul1 bul2 double null mutants. Rog1 binds directly to Rsp5, and their interaction is dependent on GSK-3. Furthermore, Rog1 is stabilized in the npi1 mutant, in which RSP5 expression levels are reduced. These results suggest that yeast GSK-3 regulates the stability of Rog1 in cooperation with Bul1, Bul2, and Rsp5.

Adaptor Proteins, Signal Transducing↗

PubMed2000

Mechanical stretch stimulates growth of vascular smooth muscle cells via epidermal growth factor receptor.

We have studied whether activation of epidermal growth factor receptor (EGFR) is involved in stretch-induced extracellular signal-regulated kinase 1/2 (ERK1/2) activation and protein synthesis in cultured rat vascular smooth muscle cells (VSMC). Cyclic stretch (1 Hz) induced a rapid (within 5 min) phosphorylation of ERK1/2, an effect that was time and strength dependent and inhibited by an EGFR kinase inhibitor (AG-1478) but not by a platelet-derived growth factor receptor kinase inhibitor (AG-1296). The stretch rapidly (within 2 min) induced tyrosine phosphorylation of several proteins, among which 180-kDa protein was shown to be EGFR as revealed by blockade with AG-1478 as well as immunoprecipitation with anti-EGFR antibody coupled with immunoblotting with anti-phosphotyrosine antibody. The stretch rapidly (within 2 min) induced association of tyrosine-phosphorylated EGFR with adaptor proteins (Shc/Grb2) as revealed by coprecipitation with glutathione-S-transferase-Grb2 fusion protein coupled with immunoblotting with anti-phosphotyrosine, anti-EGFR, and anti-Shc antibodies. Transfection of a dominant-negative mutant of H-Ras also inhibited stretch-induced ERK1/2 activation. Treatment with a stretch-activated ion channel blocker (Gd(3+)) and an intracellular Ca(2+) antagonist (TMB-8) inhibited stretch-induced phosphorylation of EGFR and ERK1/2. Treatment with AG-1478 and a mitogen-activated protein kinase kinase inhibitor (PD-98059), but not AG-1296, blocked [(3)H]leucine uptake stimulated by a high level of stretch. These data suggest that ERK1/2 activation by mechanical stretch requires Ca(2+)-sensitive EGFR activation mainly via stretch-activated ion channels, thereby leading to VSMC growth.

Adaptor Proteins, Signal Transducing↗

PubMed2000

Pontine atrophy in spinocerebellar ataxia type 6.

To investigate the clinical range of spinocerebellar ataxia type 6 (SCA6), we screened CAG repeat expansion in the voltage-dependent alpha 1A calcium channel gene (CACNL1A4) in 71 ataxic patients in 60 families; 54 patients in 43 families with hereditary ataxia and 17 sporadic patients. Thirteen patients with SCA6 were detected to have elongated CAG in CACNL1A4. Of these, 7 patients had been diagnosed as having hereditary cerebellar cortical atrophy, and 6 patients had been found to have sporadic occurrence. One patient showed distinct pontine atrophy with prominent horizontal or oblique gaze nystagmus which is an unusual feature in sporadic olivopontocerebellar atrophy. For the efficient screening of SCA6, we would propose testing CAG repeat expansion in CACNL1A4, in patients with one of two markers: (1) horizontal or oblique gaze nystagmus without other eye movement disorders, (2) pure cerebellar atrophy, even if occurrence is sporadic. We should note that the pontine atrophy could also be caused by CAG repeat expansion in CACNL1A4.

Adult↗

PubMed2000

Endothelin-1 inhibits apoptosis of vascular smooth muscle cells induced by nitric oxide and serum deprivation via MAP kinase pathway.

Endothelin (ET)-1, an endothelium-derived vasoconstrictor and mitogen, acts as an antiapoptotic factor against serum deprivation-induced apoptosis of endothelial cells and fibroblasts but enhances apoptosis of some cancer cells. In the present study, we examined whether nitric oxide (NO) and ET-1 modulate apoptosis of rat vascular smooth muscle cells (VSMCs) via the mitogen-activated protein (MAP) kinase pathway. Both serum deprivation and NO donors (FK409 and SNAP) caused apoptosis of VSMCs, as demonstrated by TdT-mediated dUTP-biotin nick end-labeling, appearance of fragmented DNA, and induction of caspase-3 activity. ET-1 dose-dependently antagonized apoptosis induced by serum deprivation and NO donors. A selective ET(A) receptor antagonist (BQ123) and a nonselective ET(A/B) receptor antagonist (TAK044), but not a selective ET(B) receptor antagonist (BQ788), inhibited the antiapoptotic effect of ET-1, indicating that the antiapoptotic effect of ET-1 is mediated via the ET(A) receptor. ET-1 activated MAP kinase, whose effect was inhibited by FK409. Transfection with an unphosphorylated wild-type MAP kinase kinase-1 (MAPKK-1) or its constitutively activated mutant protected VSMCs against apoptosis induced by serum deprivation and NO donors. Inhibition of MAP kinase activity with PD98059, a specific inhibitor of MAPKK-1, or by transfection of a dominant-negative MAPKK-1 mutant antagonized the antiapoptotic effect of ET-1, suggesting the involvement of MAP kinase in the antiapoptotic effect. The potent inhibitory effect of ET-1 on apoptosis of VSMCs induced by serum deprivation and NO suggests that the counterbalance between the 2 endothelium-derived factors contributes to the process of vascular remodeling by determining VSMC survival and death, respectively, via a common MAP kinase pathway.

Animals↗

PubMed2000

Adrenomedullin and nitric oxide inhibit human endothelial cell apoptosis via a cyclic GMP-independent mechanism.

Adrenomedullin, which was discovered as a vasodilating peptide, has been reported to be produced in various organs, in which adrenomedullin regulates not only vascular tone but also cell proliferation and differentiation in an autocrine/paracrine manner. We evaluated the effect of adrenomedullin on endothelial cell apoptosis. Human umbilical vein endothelial cells underwent apoptosis when cultured in serum-free medium. Treatment with adrenomedullin reduced the number of cells with pyknotic nuclei (Hoechst 33258 staining) and inhibited cell death (dimethylthiazol-diphenyltetrazolium bromide assay) in a dose-dependent manner. The administration of adrenomedullin did not alter the expression levels of Bcl-2 family proteins. Experiments with analogs of cAMP or a cAMP-elevating agonist demonstrated that elevation of the intracellular cAMP concentration does not mediate the antiapoptotic effect of adrenomedullin. The coadministration of N-nitro-L-arginine methyl ester (2 mmol/L), an inhibitor of nitric oxide synthase, abrogated the effect of adrenomedullin. Lower doses of sodium nitroprusside (1 to 10 micromol/L), a nitric oxide donor, mimicked the antiapoptotic effect of adrenomedullin. The antiapoptotic effect of sodium nitroprusside was not attenuated by the inhibition of soluble guanylyl cyclase with 1 micromol/L oxadiazolo-quinoxalin-1-one nor could apoptosis be inhibited by the incubation of human umbilical vein endothelial cells with 1 mmol/L 8-bromo-cGMP, a cell-permeant cGMP analog. These results indicate that adrenomedullin and nitric oxide inhibit endothelial cell apoptosis via a cGMP-independent mechanism.

Adrenomedullin↗

PubMed2000

Modulation of neural activities during visual processing in the human extrastriate visual cortex.

Magnetoencephalographic responses to single letters (Japanese monosyllabic characters) presented in the left visual field were measured during visual cognition tasks, in which subjects judged matching of characters in two different processes based on phonological and graphical cues. Equivalent current dipoles, which represent focal neural activities, were localized in the extrastriate visual cortex of the occipital to occipitotemporal regions. The main activities were observed in the right lateral area when the subjects detected shape, and also in the medial and inferior areas of both hemispheres when they detected rhyme. These results suggest that the neural activities in the extrastriate cortex, which are related to early processing of familiar visual forms, can be modified by the top-down control.

Adult↗

PubMed2000

Effects of vasodilatory antihypertensive agents on endothelial dysfunction in rats with ischemic acute renal failure.

Ischemic acute renal failure is associated with vascular endothelial dysfunction. We examined whether vasodilatory antihypertensive agents would improve endothelial function in rats with ischemia/reperfusion renal injury. Rat kidneys were isolated and perfused after clipping of the bilateral renal arteries for 45 min and reperfusion for 24 h, and renal perfusion pressure and nitric oxide concentration in the venous effluent (chemiluminescence assay) were monitored. Preischemic administration of celiprolol (a beta-blocker; 100 mg/kg p.o.), benidipine (a calcium channel blocker; 1 mg/kg p.o.), or imidapril (an angiotensin converting-enzyme inhibitor; 3 mg/kg p.o.) restored endothelial function in rats subjected to acute renal ischemia (deltarenal perfusion pressure [10(-8) M acetylcholine]: sham -42+/-3%, ischemia -31+/-1%, ischemia +celiprolol -39+/-1%*, ischemia+benidipine -38+/-2%*, ischemia+imidapril -42+/-2%*; *p<0.05 vs. ischemia). Serum urea nitrogen and creatinine levels were also lower in the treated groups. Furthermore, ischemia-induced decreases in the response to acetylcholine and renal excretory function were smaller in SHR than in deoxycorticosterone-salt hypertensive rats, in which endothelial damage was marked. These results suggest that preischemic endothelial function may influence the degree of ischemic renal injury. Calcium channel blockers, converting-enzyme inhibitors, and endothelial NO synthase-activating beta-blockers had beneficial effects on renovascular endothelial dysfunction due to ischemia.

Acetylcholine↗

PubMed2000

Suppression of integrin alpha(v) expression by endothelin-1 in vascular smooth muscle cells.

Both integrins and endothelins (ETs) are known to play important roles in vascular remodeling via proliferation, apoptosis, and migration of vascular smooth muscle cells (VSMCs), whose dysfunctions have been implicated in the pathogenesis of end-organ damage associated with hypertension and arteriosclerosis. However, whether there is any interaction between endothelin-1 (ET-1) and integrins remains unknown. Therefore, the aim of the present study was to elucidate whether ET-1 regulates the expression of integrin alpha(v) in rat VSMCs. ET-1 dose- and time-dependently suppressed the integrin alpha(v) messenger RNA (mRNA) transcripts, as quantified by a real-time quantitative polymerase chain reaction (PCR) method, and decreased the transcriptional activity of integrin alpha(v) gene, as demonstrated by integrin alpha(v)-luciferase assay. The inhibitory effect of ET-1 on integrin alpha(v) gene expression was abrogated by an ETA receptor antagonist (BQ123) but not by an ET(B) receptor antagonist (BQ788). ET-1 also suppressed the cell surface expression of integrin alpha(v)beta5 and the adhesion to vitronectin, but not to fibronectin. These results demonstrate that the adhesion of vitronectin to rat VSMCs is inhibited by ET-1 via the ET(A) receptors by suppressing integrin alpha(v) gene transcription, suggesting that ET-1 is involved in regulation of vascular integrin alpha(v) gene expression.

Animals↗

PubMed2000

Cytokine-activated p42/p44 MAP kinase is involved in inducible nitric oxide synthase gene expression independent from NF-kappaB activation in vascular smooth muscle cells.

Recent evidence suggests the possible involvement of inducible nitric oxide synthase (iNOS) in the development and maintenance of hypertension in certain animal models. Inflammatory cytokines activate nuclear factor (NF)-kappaB, which plays a major role in transactivation of the inducible nitric oxide synthase (iNOS) gene. However, it remains unknown whether cytokine-mediated iNOS expression in vascular smooth muscle cells (VSMCs) requires signaling pathway(s) other than NF-kappaB activation. The purpose of this study was to determine whether the p42/p44 MAP kinase pathway is involved in cytokine-induced NF-kappaB activation and/or iNOS expression in cultured rat VSMCs. Nitrite/nitrate (NOx) production stimulated by interleukin (IL)-1beta or tumor necrosis factor (TNF)-alpha in VSMCs was markedly suppressed by inhibiting MAP kinase by pretreatment with a p42/p44 MAP kinase kinase (MAPKK)-1 inhibitor (PD98059) or by transfecting the dominant-interfering form of the nonphosphorylated MAPKK-1 expressing construct (MAPKK S222A). Inhibition of p42/p44 MAP kinase also antagonized the upregulation of iNOS mRNA and protein, as demonstrated by the quantitative RT-PCR method and Western blot analysis, respectively. Furthermore, rat iNOS promoter activity using an iNOS-luciferase construct stimulated by cytokines was inhibited by MAPKK-1 inhibition. However, kappaB-dependent transcription analysis revealed that cytokine-stimulated NF-kappaB activity was unaffected by MAP kinase inhibition. Western blot analysis using anti-IkappaB-alpha and anti-phospho-IkappaB-alpha antibodies showed that PD98059 had no effect on transient phosphorylation or degradation of IkappaB-alpha by cytokines. An electrophoretic mobility shift assay using synthetic oligonucleotide corresponding to the downstream NF-kappaB site of rat iNOS promoter as a probe showed that MAP kinase inhibition did not block cytokine-stimulated activation of NF-kappaB. These data suggest that the MAP kinase pathway is in part involved in cytokine-induced iNOS expression independent from NF-kappaB activation in rat VSMCs.

Animals↗

PubMed2000

Thymic hyperplasia as a source of ectopic ACTH production.

A 26 year-old man with suspected Cushing's disease underwent transsphenoidal exploration of the pituitary without any evidence of microadenoma or hyperplasia. Progressive hypercortisolism necessitated bilateral adrenalectomy. Postoperatively, skin pigmentation gradually developed with a marked elevation of plasma ACTH levels, and CT scanning uncovered a thymic mass. Following removal of the thymic mass, skin pigmentation disappeared and plasma ACTH levels fell to normal. The excised mass was found to be a benign thymic hyperplasia without epithelial or carcinoid tumor cells. However, gel chromatography showed that the thymic tissue extract contained high ACTH content comparable to that of ectopic ACTH-producing tumors with a major component corresponding to ACTH(1-39). Northern blot analysis and in situ hybridization revealed the expression of proopiomelanocortin transcripts in lymphocytes of thymic hyperplasia. This report suggests that lymphocytes in thymic hyperplasia are the most likely site of deregulated ACTH expression causing ectopic ACTH syndrome.

ACTH Syndrome, Ectopic↗

PubMed2000

Immunoreactive adrenomedullin (AM) concentration in maternal plasma during human pregnancy and AM expression in placenta.

Adrenomedullin (AM) is a novel vasorelaxant peptide, isolated from human pheochromocytoma. Although AM may be involved in the regulation of the cardiovascular system, a number of other mechanisms are also involved. The present study was undertaken to confirm the presence of AM in human maternal circulation and in placental function during pregnancy. Immunoreactive (ir) AM concentrations in maternal plasma were 3.4+/-0.7fmol/ml (mean+/-s.e. m.) in the first trimester, 3.3+/-1.1fmol/ml in the second trimester, 7.3+/-2.8fmol/ml in the third trimester, 4.1+/-1.9fmol/ml in early puerperium and 3.0+/-0.4fmol/ml in non-pregnant periods; the concentration in the third trimester was significantly greater than those in other periods. Plasma concentrations of estradiol (E(2)), progesterone, human placental lactogen (hPL) and human chorionic gonadotropin (hCG) were also measured, using RIA kits. Significant correlations have been demonstrated between the concentrations of irAM and those of E(2), progesterone and hPL. We therefore examined the expression of AM within the placental tissues using immunohistochemistry and northern blot analysis in order to demonstrate a correlation between the presence of AM in the placenta and maternal plasma. Using immunohistochemistry, we detected AM in the amnion at term and the expression of AM mRNA in human placental tissues using cloned human (h) AM complementary DNA as a probe. This study demonstrates the immunoreactivity of human hAM in maternal plasma during pregnancy, and suggests that hAM in maternal plasma is generated partly from placental tissue.

Adrenomedullin↗