Biomedical subjects

M Masuda

Publications and source records attributed to M Masuda.

At least 289 records · Page 16Linked to original sources

PubMed1995

Fluid flow and osmotic stress induce tyrosine phosphorylation of an endothelial cell 128 kDa surface glycoprotein.

To investigate the flow sensing and the early signaling events in vascular endothelial cells (ECs), we surveyed changes in phosphotyrosine levels of glycoproteins using immunoblot analyses. Cultured bovine arterial ECs were exposed to steady laminar flow by using a coneplate type flow apparatus and glycoprotein fractions were partially purified by lectin affinity column chromatography. A 128 kDa protein band in the Ricinus-communis-agglutinin-bound fraction showed a rapid and consistent augmentation of tyrosine phosphorylation by flow. Cell surface domain-restricted biotinylation revealed that the 128 kDa glycoprotein has extracellular domain(s). Tyrosine phosphorylation of the 128 kDa protein was also observed in ECs subjected to hyper- or hypo-osmotic shock but not in ECs stimulated by Ca2+ mobilizing agents.

Animals↗

PubMed1995

An animal model of congenital defect of gene expression of cholecystokinin (CCK)-A receptor.

Expressions of the CCK-A and B receptor genes in fetal and adult pancreas of OLETF rats were examined by the reverse transcriptase polymerase chain reaction followed by Southern blot hybridization. The pancreatic responses to various stimulants were examined in vitro and results were compared with those of control (LETO) rats. CCK-A receptor mRNA was not expressed in the fetal pancreas of either strain or in the adult pancreas of OLETF rats, but was expressed in the adult pancreas of LETO rats. CCK-B receptor mRNA was expressed in fetal and adult pancreas in both strains. Southern blot hybridization indicated a difference in gene structure in the two strains. The maximal effective concentrations of neuromedin C, carbachol, and secretin for amylase secretion and intracellular Ca2+ movement stimulated by carbachol and neuromedin C were similar in the two strains. CCK-8 and the non-sulfated form stimulated amylase secretion only in LETO rats. These results suggest that OLETF rats are a new model of a congenital defect of the CCK-A receptor gene and should be useful for determining CCK receptor function.

Amylases↗

PubMed1995

Purification and characterization of a form of cytochrome P450 from bear liver microsomes.

A form of P450 [termed P450(b-1)] was purified from male bear liver microsomes. The specific content of the final P450(b-1) preparation was 11.26 nmol/mg protein, and recovery was 0.20% of the microsomal P450. The apparent molecular weight of P450(b-1) was 54,000. The absorption spectrum of P450(b-1) indicated that this protein was a low- and high-spin mixed type P450 in the oxidized form. The carbon monoxide complex of reduced P450(b-1) showed an absorption peak at 450.5 nm. The reconstituted system containing P450(b-1) catalyzed the metabolism of aminopyrine, benzo[a]pyrene, 7-ethoxycoumarin, imipramine and propranolol, of which P450(b-1) most strongly catalyzed aminopyrine N-demethylation and imipramine N-demethylation. The N-terminal amino acid sequence of P450(b-1) was highly homologous to that of P450-D1 from liver microsomes of male beagle dogs. P450(b-1) showed similarities in spectral properties, N-terminal amino acid sequence, and catalytic activities to rat P450 2C11. P450(b-1) was immunochemically cross-reactive with anti-P450 2C11 antibody and very weakly cross-reactive with anti-P450 2E1 antibody, but did not react with anti P450 1A1 or 2B1 antibodies. On the basis of these results, we suggest that P450(b-1) belongs to the P450 2C subfamily.

Amino Acid Sequence↗

PubMed1995

Induction of sequence-specific DNA-binding factors by erythropoietin and the spleen focus-forming virus.

The signal transduction mechanism of erythropoietin (Epo), which regulates growth and differentiation of erythroid cells, is still unclear. Recent studies showing the activation by various ligands of a group of proteins called Stat (signal transducers and activators of transcription) proteins raised the possibility that such proteins may also be involved in the Epo signal transduction pathway. In this report, we show that Epo induces factors that specifically bind to the sis-inducible element and the gamma response region of the Fc gamma receptor factor I gene in the Epo-dependent mouse erythroleukemia cell line HCD-57. These factors contain phosphotyrosine and antibodies against Stat1 and Stat3 proteins reacted with them. In HCD-57 cells infected with Friend spleen focus-forming virus, which now grow in an Epo-independent manner, the DNA-binding factors were constitutively activated even in the absence of Epo. These results suggest that the factors induced by Epo contain components identical or related to known Stat proteins. It is also suggested that continuous activation of these DNA-binding factors may be responsible for the ability of spleen focus-forming virus to abrogate the Epo-dependence of HCD-57 cells and cause erythroleukemia in susceptible mice.

Animals↗

PubMed1995

Occurrence of enzymes involved in biosynthesis of indole-3-acetic acid from indole-3-acetonitrile in plant-associated bacteria, Agrobacterium and Rhizobium.

The occurrence of a hitherto unknown pathway involving the action of two enzymes, a nitrile hydratase and an amidase for the biosynthesis of indole-3-acetic acid was discovered in phytopathogenic bacteria Agrobacterium tumefaciens and in leguminous bacteria Rhizobium. The nitrile hydratase acting on indole-3-acetonitrile was purified to homogeneity through only two steps from the cell-free extract of A. tumefaciens. The molecular mass of the purified enzyme estimated by HPLC was about 102 kDa, and the enzyme consisted of four subunits identical in molecular mass. The enzyme exhibited a broad absorption spectrum in the visible range with absorption maxima at 408 nm and 705 nm, and it contained cobalt and iron. The enzyme stoichiometrically catalyzed the hydration of indole-3-acetonitrile into indole-3-acetamide with a specific activity of 13.7 mol per min per mg and a Km of 7.9 microM.

Journal Article↗

PubMed1995

Ultrastructural evidence of cell communication between epithelial dark cells and melanocytes in vestibular organs of the human inner ear.

BACKGROUND: The possibility of interaction between epithelial dark cells and melanocytes in the mammalian inner ear has been pointed out because of their morphological and biochemical characteristics, although very few studies have dealt directly with communication between these two types of cells. We investigated the dark cell area of human vestibular organs in order to clarify the ultrastructural evidence for cell interaction between epithelial dark cells and melanocytes. METHODS: All of the material was obtained from vestibular schwannoma operations. Paraffin sections were stained with hematoxylin and eosin (H&E) and by the Fontana-Masson technique. Other paraffin sections were also stained immunohistochemically for S-100 protein. Glutaraldehyde fixed specimens were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). RESULTS: Light microscopy revealed melanin pigment granules in the cytoplasm of epithelial dark cells. Melanocytes in the subepithelial layer stained positively for S-100 protein. The presence of intraepithelial melanocytes was confirmed by the presence of cell profiles with a large number of melanin pigment granules and S-100 protein in the cytoplasm. SEM showed that the dark cells had a pentagonal surface with microvilli on the apical surface edge. They had complicated structures at the basal portion of their cytoplasm. Melanocytes extending cytoplasmic processes to adjacent areas were observed under the dark cells. TEM showed that the dark cells were tightly linked by junctional complexes in the upper lateral portion of their cytoplasmic membrane and interdigitated by lateral infoldings. Compound melanosomes (phagosomes or secondary lysosomes) found in the cytoplasm of the dark cells contained poorly pigmented melanosomes with a periodic internal structure. Gap junctions were clearly showed between adjacent melanocytes in the subepithelial layer. CONCLUSIONS: The characteristic substructures of dark cells and melanocytes suggested the presence of intimate cell interaction between these two types of cells in the vestibular organs of the human inner ear, although it is not clear at this stage whether such cell interaction is specific only for patients with vestibular schwannoma. Dark cells and melanocytes form a cell community that serves to maintain homeostasis in vestibular organs through communication in which cell information obtained by both dark cells and melanocytes serves to facilitate the system.

Adult↗

PubMed1995

Focal adhesion proteins associated with apical stress fibers of human fibroblasts.

Human fibroblasts stained with fluorescently labeled phalloidin revealed many stress fibers within the apical cytoplasm in addition to those located along the basal plasma membrane and associated with focal adhesions. The staining patterns of these apical stress fibers with fluorescent phalloidin, anti-alpha-actinin, and antimyosin were identical to those of the basal stress fibers, suggesting the same macromolecular organization for both types of stress fibers. There were two types of apical stress fibers that clearly interacted with the apical plasma membrane, those extending between the basal and the apical plasma membrane and those having both ends on the basal membrane forming arches whose top interacted with the apical plasma membrane. By electron microscopy, we observed that apical stress fibers were associated with the apical plasma membrane via electron-dense plaques reminiscent of the focal adhesion. Since several proteins have been specifically localized to the focal adhesion site, we examined whether they were also present at the apical stress fiber-membrane association site by using immunocytochemical methods and image reconstruction techniques. We found that vinculin, talin, paxillin, a fibronectin receptor protein, several integrin subunits including beta 1, fibronectin, and proteins with phosphorylated tyrosine were also components of the apical plaque. These observations indicate that apical stress fibers are attached to the plasma membrane by using principally the same molecular assembly as the focal adhesion associated with the basal stress fiber. We suggest that the complex molecular organization of the focal adhesion is not demanded by cell adhesion, but rather it is needed for anchoring stress fibers to the plasma membrane. Apical plaques did not stain with the anti-integrin alpha v subunit or anti-focal adhesion associated kinase (FAK), although these antibodies stained focal adhesions. These results suggest that the apical stress fiber-membrane contact has some important functions different from those of the focal adhesion.

Antibody Specificity↗

PubMed1995

Paradoxical effect of Sudan III on the in vivo and in vitro genotoxicity elicited by 7,12-dimethylbenz(a)anthracene.

Effect of the induction of drug metabolizing enzymes by Sudan III on the in vivo and in vitro genotoxicity elicited by 7,12-dimethyl-benz(a)anthracene (DMBA) was investigated. A significant suppression of DMBA-induced micronucleated reticulocytes was observed in C57BL/6 mice treated with Sudan III intraperitoneally for 3 or 5 days before injection of the DMBA. However, the preincubation of DMBA with hepatic microsomes from Sudan III-treated rats caused a marked increase in the in vitro mutagenicity in the Ames assay, paradoxically. Sudan III was found to induce CYP 1A1, 7-ethoxycoumarin O-deethylase activity as well as both UDP-glucuronyl transferase and glutathione S-transferase activities. The increase of mutagenicity of DMBA observed in the Ames assay using hepatic microsomes from Sudan III-treated rats was inhibited by the addition of uridine 5'-diphosphoglucuronic acid or reduced glutathione with cytosol. Mutagenic metabolites of DMBA formed by CYP1A1 appeared to be effectively detoxified by these phase II enzymes. The results of this study suggest that Sudan III-induced prevention of in vivo mutagenesis is due to the induction of both CYP 1A1 and detoxifying phase II enzymes. The induced CYP1A1 may accelerate formation of active metabolic intermediates, but phase II enzymes are also induced and detoxify these intermediates to inactive metabolites. This would reduce residence time of the carcinogen in the body and the time of exposure to active metabolites for target organs.

7-Alkoxycoumarin O-Dealkylase↗

PubMed1995

A rare case of large ventricular septal defect with minimal pulmonary vascular obstructive changes in a 41-year-old woman.

We describe a case of large ventricular septal defect (VSD) with minimal obstructive changes in the small pulmonary arteries of a 41-year-old woman. Before cardiac catheterization, some laboratory findings led us to consider that surgical closure of the defect would not be possible. However, because hemodynamic examinations showed only mildly elevated pulmonary vascular resistance, we patch-closed the VSD successfully. The histology of lung specimens showed only minimal obstructive changes in the small pulmonary arteries. Considering the size of the VSD and the age at which we hemodynamically evaluated the patient, the mildness of the pulmonary vascular obstructive changes appeared to be atypical in the natural course of a VSD of this size.

Adult↗

PubMed1995

Preoperative autologous blood donations in pediatric cardiac surgery.

BACKGROUND: Preoperative autologous blood donation is one of the most effective methods to avoid homologous blood transfusion in cardiac operations. However, there have been few reports about the safety and efficacy of autologous blood donation in children. METHODS: Since 1986, we have instituted a blood conservation program including preoperative autologous blood donations in children. Eighty children as young as 3 years old (mean +/- SD, 8.6 +/- 3.9 years) and weighing as little as 12.3 kg (29.2 +/- 14.5 kg) were enrolled in the program, and 735 +/- 388 mL of blood was donated during an average of 3.1 +/- 1.5 phlebotomies before the operations. RESULTS: Two episodes of mild vasovagal reaction were observed in 2 patients as a complication of the phlebotomy. Seventy-six percent of the collected blood was stored by cryopreservation; the remaining 24% was preserved by liquid storage. Seventy-eight of these patients (97.5%) underwent operations using cardiopulmonary bypass. Seventy-five patients (94%) were operated on successfully without the need for a homologous blood transfusion. As for the other 5 patients, 2 received only platelet concentrate. CONCLUSION: Preoperative autologous blood donation is a safe and effective method to avoid homologous blood transfusion in pediatric cardiac operations.

Adolescent↗

PubMed1995

Rapid and gentle extraction, reconstitution and characterization of microfilament and glia filament from rat astrocytes.

We developed gentle and rapid methods for depolymerization and extraction of both microfilament and glia filament separately from a crude cytoskeletal fraction of rat astrocytes. Electron microscopy revealed that the filament reconstituted from the microfilament extract closely resembled F-actin that was formed from G-actin of rabbit skeletal muscle. It was found by immunoblotting analysis that even the reconstituted microfilament-like filaments, which had been purified by affinity chromatography with heavy meromyosin subfragment 1 (S1)-conjugated Sepharose, contained vimentin and glia fibrillary acidic protein (GFAP) besides actin, inferring the interaction between microfilament and glia filament. The filaments (9-10 nm thick) reconstituted from the glia filament extract were composed of actin and other minor components in addition to vimentin and GFAP. Actin, GFAP, 101, 34, 32.5, 30.5, 29.5 and 28 kDa proteins found in the reconstituted glia filament-like filaments were suggested to be glia filament-associated proteins.

Actin Cytoskeleton↗

PubMed1995

Nucleolar organizer regions: a new prognostic factor for upper tract urothelial cancer.

PURPOSE: The prognostic significance of argyrophilic staining in the nucleolar organizer regions was studied in 63 patients with primary urothelial tumors of the renal pelvis and ureter. MATERIALS AND METHODS: Silver staining of paraffin embedded sections was performed using a 1-step technique. RESULTS: The prognosis for patients with a mean number of argyrophilic nucleolar organizer region proteins per nucleus (argyrophilic nucleolar organizer region score) of 8 or greater was significantly worse than that for patients with a score of less than 8 (P <0.001). CONCLUSIONS: Argyrophilic nucleolar organizer region score is a new prognostic factor in primary urothelial tumors of the renal pelvis and ureter, and it is particularly useful for patients with invasive tumors.

Adult↗

PubMed1995

Maldistribution of the cerebral blood flow in retrograde cerebral perfusion.

Retrograde cerebral perfusion (RCP) through a superior vena caval (SVC) cannula has now become a useful alternative for brain protection during aortic arch operations. However, little is still known about its physiological effects, especially regarding the flow distribution in the brain. We studied the cerebral blood flow distribution under hypothermic conditions using mongrel dogs (n = 6, weighing 9.5 to 14 kg). We measured the cerebral tissue blood flow of the cortex with a laser Doppler flowmeter and cerebral tissue blood flow of the medulla using the hydrogen clearance method. The cerebral blood distribution at 28 degrees C with a whole body bypass flow of 100 ml/kg per min and aortic pressure of 88.3 +/- 20.4 mmHg was used as a control. Then the body temperature was decreased to 20 degrees C and the descending aorta was cross-clamped just distal to the origin of the left subclavian artery to establish antegrade cerebral perfusion (ACP). The perfusion flow was decreased to 54.8 +/- 12.4 ml/kg per min so as to make the aortic pressure similar to the control conditions. After measuring the cerebral blood flow distribution in ACP, the perfusion was then switched to RCP through the bilateral internal maxillary vein and the SVC pressure was kept at 40 mmHg. In RCP, the cerebral blood flow of the medulla was quite similar to that in ACP (12.4 ml/min per 100 g versus 15.2 ml/min per 100 g, NS). In contrast, the cerebral blood flow of the cortex significantly decreased to 16% of the flow in ACP (7.8 perfusion units versus 50 perfusion units, P < 0.01). Because of the maldistribution of the cerebral blood flow in RCP, careful attention should be paid to the clinical application of this method.

Animals↗

PubMed1995

Alterations in activation and deactivation of mutagens in aging rat liver.

Age-associated alternations in activation and deactivation of benzo[a]pyrene (BP), furylfuramide (AF2), and 2-nitrofluorene (NF) in rat liver were investigated. A modified Ames mutagenicity test system used liver 9000 g supernatant (S-9) from male Fischer 344 rats aged 3, 6, 12, and 24 months fortified with NADPH generating system alone or together with cofactors of conjugating enzymes. The numbers of revertant colonies due to mutagenic activation of BP during preincubation were markedly high in young rats and decreased with aging. They were decreased by the addition of UDP-glucuronic acid (15 mM) or glutathione (30 mM), the cofactors of UDP-glucuronyl transferase and glutathione S-transferase, respectively, in the preincubation mixture. The difference in the BP activation by liver S-9 from different age groups almost disappeared by the addition of reduced glutathione. A direct mutagen, AF2, was not metabolized during preincubation in the absence of cofactors of conjugating enzymes, but detoxified up to about 50% by the addition of glutathione to the preincubation mixture containing liver S-9 from rats of any age group. Another direct mutagen, NF, was partly detoxified during preincubation by liver S-9 from 3-month-old rats more than by that from 24-month-old rats. It is suggested that incidence of chemical carcinogenesis may increase along with aging due to the altered xenobiotics metabolism.

Aging↗

PubMed1995

Cholinergic stimulatory effect of intragastric administration of a prostaglandin E2 analogue on pancreatic exocrine secretion in conscious rats.

The effect of a long-acting, potent synthetic analogue of prostaglandin E2, enprostil, on pancreatic exocrine secretion was examined in conscious rats. Rats were prepared with cannulae draining bile and pancreatic juice separately. Pancreatic exocrine secretion was increased by intragastric administration of enprostil but inhibited by its intravenous administration. The pancreatic response to intragastric administration of enprostil was not inhibited by the administration of cholecystokinin antagonist or secretin antibody, or by bilateral vagotomy, but was completely abolished by atropine. Therefore, intragastric administration of enprostil seemed to stimulate pancreatic exocrine secretion via a peripheral gastro-(entero)-pancreatic reflex.

Amylases↗

PubMed1995

Primary cutaneous cryptococcosis and Cryptococcus neoformans serotype D.

We report a healthy, 73-year-old Japanese woman who presented with primary cryptococcosis on the skin of both cheeks. She had initially developed an erythematous, partly ulcerated lesion on the right cheek 2 weeks earlier following an injury. There was no regional lymphadenopathy, and chest X-rays were normal. Histopathological findings showed granulomatous cell infiltration. Periodic acid Schiff staining revealed spores that were identified by the indirect immunoperoxidase staining method as Cryptococcus neoformans. The isolate was identified as C. neoformans var. neoformans serotype D. The skin lesions healed in 1 month without antifungal therapy. A literature review indicates that this serotype tends to produce cutaneous lesions without systemic involvement.

Aged↗

PubMed1995

Evaluation of factor XIa-alpha 1-antitrypsin in plasma, a contact phase-activated coagulation factor-inhibitor complex, in patients with coronary artery disease.

Excess activated factor XI (FXIa) in plasma indicates increased activation during the contact phase of blood coagulation. To investigate the relationship between such elevations and coronary atherosclerosis, we examined FXIa values in patients with coronary artery disease (CAD) by an enzyme-linked immunosorbent assay method that we developed that detects FXIa in plasma samples as an FXIa-alpha 1-antitrypsin complex (FXIa-alpha 1AT). The presence and extent of CAD were documented by coronary angiography and assessed by a recently developed scoring system for semiquantitative estimation of coronary atherosclerosis. Plasma FXIa-alpha 1AT levels were significantly increased in patients with angiographically proven CAD (13.9 +/- 3.0 micrograms/L, n = 42) compared with age-matched, healthy control subjects (11.9 +/- 1.7 micrograms/L, n = 20) as well as patients with angiographically normal coronary arteries (12.0 +/- 2.3 micrograms/L, n = 25). Moreover, in the total patient population, the FXIa-alpha 1AT level was related to the number of significant coronary artery stenoses as well as to the total coronary score. FXIa-alpha 1AT showed a positive correlation with thrombin-antithrombin III complex, fibrinogen, and Lp(a) and an inverse correlation with apo A-I, as determined by multi-variate analysis. Our studies provide evidence that increased activation of the contact pathway occurs in patients with CAD and is related to the severity of the disease. Although it is unknown whether this abnormality is the cause or the result of the vascular lesion, it may be important for progression of the underlying atherosclerosis or for propagation of the atherosclerotic process itself.

Antithrombin III↗

PubMed1995

Solution-phase synthesis of an anti-human immunodeficiency virus peptide, T22 ([Tyr5,12,Lys7]-polyphemusin II), and the modification of Trp by the p-methoxybenzyl group of Cys during trimethylsilyl trifluoromethanesulfonate deprotection.

T22 ([Tyr5,12,Lys7]-polyphemusin II) was previously synthesized by a solid-phase method and was found to have a strong anti-human immunodeficiency virus (HIV) activity, comparable to that of 3'-azido-2',3'-dideoxy-thymidine (AZT). In the present study, the solution-phase synthesis of T22 was attempted in order to produce this peptide on a large scale. An 18-residue peptide amide corresponding to the entire amino acid sequence of T22 was synthesized by assembling four peptide fragments and two amino acid derivatives, followed by thioanisole-mediated deprotection with 1 M trimethylsilyl trifluoromethanesulfonate (TMSOTf) in trifluoroacetic acid followed by air-oxidation. During this deprotection, a significant by-product derived from the transfer of the p-methoxybenzyl (MBzI) group from the sulfhydryl group of the cysteine residue to the side chain of the tryptophan residue was formed. This side reaction was found to be efficiently suppressed by adopting a two-step deprotection procedure using silver trifluoromethanesulfonate (AgOTf)-TMSOTf or trimethylsilyl bromide (TMSBr)-TMSOTf.

Amino Acid Sequence↗