Biomedical subjects

S Ito

Publications and source records attributed to S Ito.

At least 19 recordsLinked to original sources

PubMed1992

Prostaglandin E2-induced arachidonic acid release and catecholamine secretion from cultured bovine adrenal chromaffin cells.

We recently reported that prostaglandin E2 (PGE2) and arachidonic acid (AA) each induced a gradual secretion of catecholamines from cultured bovine adrenal chromaffin cells in the presence of ouabain by stimulation of phosphoinositide metabolism. In the present study, we examined the relationship between phospholipase A2 and C activation and catecholamine secretion by PGE2 in chromaffin cells. The phospholipase A2 inhibitors p-bromophenacyl bromide and mepacrine did not affect the basal and ouabain-induced release, but dose-dependently blocked PGE2-evoked phosphoinositide metabolism and the consequent catecholamine release at an IC50 value of 3 microM. PGE2 induced rapid hydrolysis of [3H]AA from prelabeled phospholipid pools: the release of [3H]AA could be detected at as early as 15 sec and reached a plateau after 1 min. While the phospholipase C inhibitor neomycin did not inhibit PGE2-induced AA release, phospholipase A2 inhibitors dose-dependently inhibited it at IC50 values comparable to those for catecholamine release. Pretreatment of intact cells with the phorbol ester 12-O-tetradecanoylphorbol 13-acetate, but not with pertussis toxin, prevented AA release by PGE2. These results demonstrate that PGE2 activates phospholipase A2 as well as phospholipase C in a pertussis toxin-insensitive manner and suggest that the released arachidonic acid may be involved in PGE2-induced catecholamine release from chromaffin cells.

Adrenal Medulla↗

PubMed1992

Multiple projection of vagal non-myelinated afferents to the anterior insular cortex in rats.

Projection of the vagal C-afferent to the insular cortex was examined in rats. Electrical activation of the C-afferent resulted in two cortical field potentials in the anterior insula. They were independent of each other and neither of them was attributed to the specific thalamic projection. These results imply that vagal information is conveyed to the cerebral cortex by more than one pathways.

Afferent Pathways↗

PubMed1992

Identification of the prostacyclin receptor by use of [15-3H1]19-(3-azidophenyl)-20-norisocarbacyclin, an irreversible specific photoaffinity probe.

The prostaglandin I (PGI2) receptor of mouse mastocytoma P-815 cells was characterized by photo-affinity labeling with the stable PGI2 analogue [15-3H1]-19-(3-azidophenyl)-20-norisocarbacyclin ([3H] APNIC) used as a potential photoaffinity probe for the receptor. [3H]APNIC bound to the mastocytoma membrane with high affinity and in a saturable manner. Scatchard plot analysis indicated a single binding site with a Kd of 4.7 nM and a Bmax of 0.58 pmol/mg protein. The binding of [3H]APNIC was dose dependently inhibited by APNIC and iloprost, another stable PGI2 agonist, and to a much lesser extent by PGE2. The binding of the radioligand showed sensitivity to the guanine nucleotide guanosine 5'-O-(3-thio-triphosphate) (GTP gamma S). Photolysis of [3H]APNIC-prelabeled membranes resulted in incorporation of radiolabel into a protein of approximately 43 kDa. Photolabeling was inhibited by PGI2 agonists and other prostaglandins with specificity for the PGI2 receptor and was modulated by GTP gamma S. A protein of approximately 45 kDa was also labeled by [3H]APNIC in the membrane of porcine platelets, membranes that are known to be abundant in PGI2 receptors. These results demonstrate that [3H]APNIC specifically labels a protein that may represent the PGI2 receptor and that this radioprobe will be a useful reagent for further characterization and purification of the PGI2 receptor.

Affinity Labels↗

PubMed1992

Cell kinetics of medulloblastomas.

BACKGROUND: Cell kinetics and clinical behavior were correlated for 22 primary and 10 recurrent or metastatic medulloblastomas from 30 patients. METHODS: Twenty-six patients received bromodeoxyuridine (BUdR) intravenously during craniotomy; excised specimens were stained by the immunoperoxidase method. The BUdR labeling index (LI) was calculated. Four patients received a pulse of tritiated thymidine; LI was calculated autoradiographically. RESULTS: The mean LI for 32 tumors (11.7 +/- 1.3% standard error) indicated high proliferative potential. LI appeared higher in tumors from younger patients and those in the cerebellar hemisphere as compared with those in the cerebellar vermis. LI did not correlate with survival time. In six BUdR-labeled tumors labeled with iododeoxyuridine, the S-phase duration was 6.1-11.3 hours (mean, 8.0 +/- 0.8 hours); the potential doubling time was 25-82 hours. The actual doubling time, estimated in three cases from serial imaging, was 20-24 days. A cell loss factor of approximately 0.90 was assumed. CONCLUSION: A high LI may reflect rapid medulloblastoma growth, but survival seemed more dependent on sensitivity to radiation therapy.

Adolescent↗

PubMed1992

Genetic changes of both p53 alleles associated with the conversion from colorectal adenoma to early carcinoma in familial adenomatous polyposis and non-familial adenomatous polyposis patients.

Mutation and loss of heterozygosity (LOH) in the p53 gene were analyzed in 274 colorectal tumors of 4 histopathological grades. Among 160 tumors from 40 familial adenomatous polyposis patients, none of 58 adenomas with moderate dysplasia had p53 mutations, whereas 8% (3 of 37) of severe adenomas, 15% (6 of 40) of intramucosal carcinomas, and 40% (10 of 25) of invasive carcinomas had p53 mutations. Only 3% (1 of 33) of severe adenomas showed both mutation and LOH, while 25% (6 of 24) of intramucosal carcinomas and 40% (10 of 25) of invasive carcinomas had both mutation and LOH. All intramucosal and invasive carcinomas that had mutations lost the other allele of the p53 gene. In 114 tumors from 86 non-familial adenomatous polyposis patients, similar results were obtained; no adenoma showed both mutation and LOH, but both alterations occurred in intramucosal and invasive carcinoma. As regards specificity in 56 mutations detected in the present study, the frequently affected codons were codons 175, 238, 245, 248, 273, and 282, 4 of these amino acids being arginine, and 72% (39 of 54) of all mutations were GC to AT transition. Although expression into p53 polyadenylated RNA was high in every invasive carcinoma irrespective of the presence of mutation or LOH, there was a correlation between mutation and protein level; immunostaining of p53 protein was negative in almost all adenomas, but it was positive in 86% of invasive carcinomas exhibiting p53 mutation. These data suggest that genetic changes on both alleles of the p53 gene through mutation and LOH, which result in abnormal protein accumulation, are involved in the conversion of adenoma to early carcinoma. Also, carcinoma cells with p53 mutations existing within adenoma tissues are detectable by immunostaining, even in formalin-fixed, paraffin-embedded specimens.

Adenoma↗

PubMed1992

Neuropeptide-induced cytosolic Ca2+ transients and phosphatidylinositol turnover in cultured human retinal pigment epithelial cells.

Neuropeptide-induced mobilization of cytosolic free Ca2+ concentration ([Ca2+]i) and phosphatidylinositol (PI) turnover in cultured human retinal pigment epithelial (RPE) cells were studied and their temporal relationship was compared. After RPE cells were loaded with fura-2/AM, [Ca2+]i was analyzed using a digital imaging microscopy system. Bombesin-related peptides which include bombesin, neuromedin B, and neuromedin C induced significant [Ca2+]i transients in RPE cells, whereas other neuropeptides, neuropeptide Y, vasoactive intestinal polypeptide (VIP), and substance P were not effective to produce [Ca2+]i transients. The percentage of reactive cells which showed positive [Ca2+]i transients induced by bombesin-related peptides was around 50%. Bombesin (1 microM) showed a peak concentration of 663 +/- 27.0 nM (mean +/- S.E.M., n = 61), neuromedin B (1 microM), 327 +/- 28.7 nM (mean +/- S.E.M., n = 38), and neuromedin C (1 microM), 357 +/- 22.7 nM (mean +/- S.E.M., n = 32). Ca2+ transients occurred within 30 s and lasted less than 5 min after the application of the neuropeptides. Chelation of the extracellular Ca2+ by EGTA significantly shortened the total time of [Ca2+]i transients induced by the above. The measurements of phosphoinositides in RPE cells revealed that neuropeptide-induced PI turnover was as quick as [Ca2+]i transients. Inositol biphosphate (IP2) and inositol triphosphate (IP3) in RPE cells showed transient increases at 15 s after the stimulation by bombesin-related peptides. These data show that changes in [Ca2+]i and PI turnover are directly linked and both are important in the signal transduction system of bombesin-related peptides in RPE cells. The data also suggest that bombesin-related peptides may play some possible roles in RPE cells.

Calcium↗

PubMed1992

[Simultaneous pseudodynamic MR evaluation of bilateral temporomandibular joints].

Coordination of bilateral temporomandibular joints (TMJs) was evaluated using bilateral simultaneous pseudodynamic magnetic resonance (MR) imaging. Seven patients (6 patients with internal derangement and one with osteoarthritis) were examined by multiplanar gradient echo technique in closed-loop cine fashion on both sagittal and coronal planes. Incoordination of bilateral TMJ motion was observed in 2 of 7 patients. This technique might be suitable for evaluation of TMJ disorders.

Humans↗

PubMed1992

Endothelin stimulates both cAMP formation and phosphatidylinositol hydrolysis in cultured embryonic bovine tracheal cells.

Embryonic bovine tracheal (EBTr) cells were found to possess receptors for endothelin (ET) of ET-1-selective (ETA) subtype with a Kd for ET-1 of 114 pM and a Bmax of 12.9 fmol/10(5) cells. Stimulation of EBTr cells with 100 pM to 100 nM ET-1 increased the contents of both inositol phosphates and cAMP in a concentration-dependent manner, indicating that the receptors are coupled to both phosphatidylinositol hydrolysis and cAMP formation in EBTr cells.

Animals↗

PubMed1992

Direct linkage of three tachykinin receptors to stimulation of both phosphatidylinositol hydrolysis and cyclic AMP cascades in transfected Chinese hamster ovary cells.

The mammalian tachykinin system consists of three distinct peptides, substance P, substance K, and neuromedin K, and possesses three corresponding receptors. In this investigation we examined intracellular signal transduction of the individual tachykinin receptors by transfection and stable expression of these receptor cDNAs in Chinese hamster ovary cells. The three receptors commonly showed a rapid and marked stimulation in both phosphatidylinositol (PI) hydrolysis and cyclic AMP formation in response to tachykinin interaction. Direct linkage of the three receptors to both phospholipase C and adenylate cyclase was evidenced by the finding that tachykinin, added together with GTP, activated these enzyme activities in membrane preparations derived from tachykinin receptor-expressing cells. The stimulation of cyclic AMP formation was less efficient than that of PI hydrolysis in receptor-expressing cells as well as their membrane preparations (about 1 order of magnitude difference in the effective peptide concentrations). However, the stimulatory responses of the PI hydrolysis and cyclic AMP formation in both receptor-expressing cells and their membrane preparations were induced in complete agreement with the tachykinin binding selectivity of each subtype of the receptors. This investigation demonstrated unequivocally that the tachykinin receptors have the potential to couple directly to both phospholipase C and adenylate cyclase and to stimulate PI hydrolysis and cyclic AMP formation.

Adenylyl Cyclases↗

PubMed1992

Cell kinetic analysis of human brain tumors by in situ double labelling with bromodeoxyuridine and iododeoxyuridine.

Fifty-seven patients with brain tumors (29 gliomas, 23 meningiomas, 5 miscellaneous) received infusions of intravenous iododeoxyuridine (IUdR) and bromodeoxyuridine (BUdR) 1-5 hr apart shortly before tumor removal. Excised tumor specimens were stained sequentially for BUdR and IUdR. The percentage of BUdR-labelled cells was determined to establish the labelling index (LI), or S-phase fraction, and the ratio of cells labelled only with IUdR to cells labelled with BUdR or with BUdR and IUdR was determined to calculate the duration of S-phase (Ts) and the potential doubling time (Tp) of each tumor. The BUdR LIs varied from less than 1% to 20%, reflecting the malignancy of each tumor. Despite the difference in LIs, however, Ts was fairly uniform (mean +/- SD, 8.7 +/- 2.0 hr). Tp varied from 2 days to more than 1 month and correlated closely with the BUdR LIs (Tp = 23/LI0.93; r2 = 0.91). Double-labelling studies with IUdR and BUdR allow the S-phase fraction, Ts and Tp to be determined from a single biopsy specimen and thus provide more useful information on the growth characteristics of individual tumors than can be obtained by single-labelling studies with BUdR.

Brain Neoplasms↗

PubMed1992

Circulating thrombomodulin as a novel endothelial cell marker: comparison of its behavior with von Willebrand factor and tissue-type plasminogen activator.

Circulating thrombomodulin is a novel endothelial cell marker, which may reflect the endothelial injury. Plasma levels of thrombomodulin were quantitated by an enzyme-linked immunosorbent assay (ELISA) in patients with hematological malignancies, liver disease, diabetes mellitus, collagen disease, thrombotic disease, and disseminated intravascular coagulation (DIC), and the thrombomodulin values were compared with those of von Willebrand factor antigen (vWf:Ag) and tissue-type plasminogen activator (t-PA) which are released from stimulated or damaged endothelial cells. The mean plasma concentrations of thrombomodulin in these disease states were elevated as compared with healthy subjects. A relatively high mean thrombomodulin level was observed in DIC, liver disease, and collagen disease. Abnormally high thrombomodulin values (greater than normal mean value + 3 SD) were found in 32.3% of patients with hematological malignancies, 57.7% of patients with liver disease, 39.3% of patients with diabetes mellitus, 30.0% of patients with collagen disease, 23.1% of patients with thrombotic disease, and 69.0% of patients with DIC. Plasma concentrations of both vWf:Ag and t-PA were also elevated in these patients. On the whole, the plasma thrombomodulin concentration was positively correlated with vWf:Ag (r = 0.441, P less than 0.001) and t-PA (r = 0.398, P less than 0.001). These findings indicate that the elevation of plasma thrombomodulin is frequently seen in a variety of diseases and circulating thrombomodulin is possibly useful for evaluating the endothelial damage in selected disease states.

Biomarkers↗

PubMed1992

Single moving dipole obtained from magnetic field of the heart in patients with left ventricular hypertrophy.

Magnetocardiograms (MCGs) were recorded by means of a second-derivative SQUID (superconducting quantum interference device) magnetometer in 20 normal subjects and 28 patients with left ventricular overload to analyze the activation sequence of the heart and amplitude of estimated current source. In the normal subjects, the dipole was directed to the left and gradually superiorly 40 ms after the beginning of the QRS wave mainly due to the activation of the left ventricle. In the patients with hypertension, the direction and location of the dipoles were similar to those of the normal subjects, but their dipole moments were increased. In the patients with mitral regurgitation, the dipoles of late QRS were directed more inferiorly than in the normal subjects and their amplitude was increased. In the patients with aortic valve disease, the amplitude of the dipoles was increased markedly and their location was deviated more to the left than the dipoles of the normal subjects. We established the criterion for diagnosis of LVO from the dipole moment of 50 ms of 3.13 x 10(-3) A or more. The sensitivity of this criterion is significantly higher in the diagnosis of left ventricular overload than the electrocardiogram (ECG). The present study shows that the moving dipole method is useful to determine the increased electromotive force in patients with left ventricular overload and that sensitivity in diagnosis of left ventricular overload is increased.

Aortic Valve Insufficiency↗

PubMed1992

Type-1 and type-2 astrocytes are distinct targets for prostaglandins D2, E2, and F2 alpha.

Accumulating evidence has revealed that astrocytes are potential targets for various neurotransmitters. Here we investigated the effects of prostaglandins (PGs) on signal transduction in purified primary cultures of rat type-1 and type-2 astrocytes. PGF2 alpha, PGD2, and 9 alpha,11 beta-PGF2, a metabolite of PGD2 and a stereoisomer of PGF2 alpha, evoked a rapid rise in the intracellular Ca2+ concentration ([Ca2+]i) in type-1, but not in type-2, astrocytes. STA2, a stable analogue of thromboxane A2, was less effective, and PGE2 showed little effect. The PG-induced rise in [Ca2+]i was not blocked by an antagonist of either PGD2 receptor or thromboxane A2 receptor. PGF2 alpha and 9 alpha,11 beta-PGF2 stimulated rapid formation of inositol trisphosphate followed by inositol bisphosphate and inositol monophosphate. On the other hand, PGE2 increased the intracellular level of cyclic AMP in type-2 astrocytes, rather than in type-1 astrocytes. The potency of PGs for cyclic AMP formation was in the following order: PGE2 greater than PGE1 greater than or equal to STA2 much greater than iloprost, a stable analogue of PGI2. PGD2 and PGF2 alpha had no effect on cyclic AMP formation. These results demonstrate that type-1 astrocytes preferentially express PGF2 alpha receptors, the activation of which leads to phosphoinositide metabolism and [Ca2+]i elevation, whereas type-2 astrocytes possess PGE receptors that are linked to cyclic AMP formation.

Animals↗

PubMed1992

Evolving pathogens in vulvovaginal candidiasis: implications for patient care.

Over the past two decades, an increasing trend in the number of vaginal infections attributable to yeasts other than Candida albicans has emerged. Of these non-albicans species, C. tropicalis and C. glabrata appear to be the most important. The change in incidence pattern of yeast vaginitis can be expected to impact greatly on the treatment of this condition, because many currently used drug therapies (e.g., imidazoles) for C. albicans vaginitis do not adequately eradicate non-albicans species. A possible explanation for the recent increased selection of these species may be the shortened antifungal therapies that have been introduced during the past decade. These 1- to 3-day regimens with the older imidazoles may suppress C. albicans, but create an imbalance of flora that facilitate an overgrowth of non-albicans species. The recognition of yeast speciation and the need for use of a broad-spectrum antifungal preparation that covers these organisms is now apparent.

Antifungal Agents↗

PubMed1992

Babesia ovata: isolation from erythrocytes and development of an enzyme-linked immunosorbent assay for detection of antibodies.

A method of isolating Babesia ovata merozoites from infected erythrocytes and an enzyme-linked immunosorbent assay (ELISA) for the detection of anti-B. ovata antibodies were developed. After B. ovata-infected erythrocytes had been lysed using the nitrogen cavitation method, the merozoites were separated from erythrocyte components by differential centrifugation and density-gradient centrifugation. The light microscopic examination showed that the purified merozoites were morphologically intact and contained few contaminants. Sodium dodecyl sulfate-polyacrylamide electrophoretic (SDS-PAGE) analysis revealed that the merozoite fraction contained very little contamination with erythrocyte components. The merozoites thus obtained were sonicated and treated with Triton X-100 and then used as an antigen to measure anti-B. ovata antibodies in ELISA. The ELISA was more sensitive in detecting anti-B. ovata antibodies than was either the indirect fluorescent antibody test or the complement fixation test on sera from cattle infected with B. ovata.

Animals↗

PubMed1992

Functional expression of VIP receptors in normal, immortalized and transformed mammary epithelial cells.

The effect of VIP and its related peptides on cAMP production has been characterized: 1) in long term culture of normal human mammary epithelial cells (HMEC); 2) in immortalized and transformed ST cell lines established from normal HMEC after genomic insertion of the large T oncogene of SV40; 3) in the spontaneously immortalized HC-11 cells, a clone isolated from the mouse mammary epithelial cells COMMA-1D, described to exhibit normal morphogenesis in vivo and functional differentiation in vitro. Basal cAMP levels were increased 1.5- to 8.7-fold in mammary epithelial cells (p less than 0.001-0.05), with a potency EC50 = 0.02-0.6 nM VIP. The pharmacological specificity of the VIP receptors coupled to cAMP generation was established according to the following potency sequence: VIP greater than PACAP-38 greater than helodermin greater than PHM, PHV greater than helospectin 1 much greater than hpGRF, secretin in HMEC, VIP greater than PACAP-38 greater than helodermin greater than helospectin 1, PHM, PHV greater than hpGRF greater than secretin in S1T3 cells, and VIP, PHI, helodermin greater than PHV greater than rhGRF greater than secretin in HC-11 cells. Our data demonstrate the presence of functional, highly sensitive and specific VIP receptors in normal, immortalized and transformed mammary epithelial cells, suggesting a regulatory role for this neuropeptide on the growth, differentiation and function in normal and neoplastic breast tissue.

Animals↗

PubMed1992

Female sex steroid residues in the tissues of steers treated with progesterone and oestradiol-17 beta.

Progesterone, oestrone and oestradiol-17 beta levels in the muscle, fat, liver, kidney and plasma of steers treated with Synovex S, untreated steers, and cows during the normal oestrous cycle, were examined. Progesterone levels in female tissues reached a maximum in the luteal phase and fell to a minimum in the follicular phase. Oestrogen levels (oestrone and oestradiol-17 beta) did not change during the cycle. Progesterone and oestrogen levels in the tissues of steers treated with Synovex S and untreated steers were not statistically different. Tissue progesterone levels in steers were much lower than those in cows during the luteal phase. The highest oestrogen levels were found in the fat of female animals. These results indicate that residue levels of progesterone and oestrogen in the muscle and fat of steers treated with Synovex S were within the physiological range, and lower than those of cows.

Adipose Tissue↗

PubMed1992

Enterogenous cyst at the cerebellopontine angle: case report.

A case of enterogenous cyst at the cerebellopontine (CP) angle is reported. A review of the literature yielded only seven cases of intracranial enterogenous cysts, and our case is the first one arising at the CP angle. The histological features, pathogenesis, and radiological and auditory brain stem response findings are discussed.

Adult↗