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H Inui

Publications and source records attributed to H Inui.

At least 91 records · Page 5Linked to original sources
PubMed1992

Diacylglycerol formation from phosphatidylcholine in angiotensin II-stimulated vascular smooth muscle cells.

In cultured vascular smooth muscle cells (VSMC), angiotensin II (Ang II) induces a biphasic diacylglycerol (DAG) formation peaking at 15 sec and 5 min. Although it has been well established that the first peak is produced by the hydrolysis of inositol 4,5-bisphosphate (PIP2), the origin of the second DAG peak has never been examined in detail. In the present paper, we provide evidence that the second peak of DAG formation in Ang II-stimulated VSMC originates mainly from PC.

Angiotensin II↗
PubMed1992

[Three-dimensional analysis of arteriography in human posterior circulation (preliminary report)].

In earlier articles it was suggested that there is a relation between vertigo and the posterior circulation. This study was designed to ascertain the course of the branches of the vertebral artery and the basilar artery, as well as the principal blood vessels of the vestibular nucleus by using radiographic three-dimensional observation. We studied 27 human brains (17 males, 10 females) fixed with the arterial embalming method at the Department of Anatomy of Kawasaki Medical School. The results were as follows: 1. Many variations in the course of the anterior inferior cerebellar artery and the posterior inferior cerebellar artery were observed, but the most frequent pattern, observed in 56% of our subjects, was the anterior inferior cerebellar arteries originating from the basilar artery and the posterior inferior cerebellar arteries from the vertebral artery. 2. Measurement of the inside diameter of both vertebral arteries showed the diameter of the left side to be thicker than that of the right side. 3. Perforating branches in the brain stem consisted of the pontine branches from the basilar artery and small branches from the anterior inferior cerebellar artery. Moreover, the transverse section showed a large number of them to originate from the ventral part of the brain stem.

Aged↗
PubMed1992

[A case of plasmacytoma of the ribs with intrathoracic tumors].

A 75-year-old male was admitted because of two tumors, one in the left middle lung field and one in the right upper lung field. Chest CT revealed intrathoracic tumors extending from destroyed ribs. Biopsy specimens of both tumors showed well-differentiated plasmacytoma. Retrospective investigation suggested that solitary plasmacytoma of bone (SPB) originating in the left fourth rib had developed into multiple myeloma (MM). Both tumors were treated with doses of 50 Gy irradiation and responded very well. Intrathoracic plasmacytomas have rarely been observed, so we have no established classification or therapy. According to reported cases, we classified intrathoracic plasmacytomas into 5 groups, and consider that treatment with doses of over 40 Gy irradiation was adequate for local control.

Aged↗
PubMed1991

Pyruvate:NADP+ oxidoreductase from Euglena gracilis: limited proteolysis of the enzyme with trypsin.

Pyruvate:NADP+ oxidoreductase from Euglena gracilis, a homodimeric protein with a molecular weight of 309 kDa, is an iron-sulfur flavoenzyme that contains thiamin pyrophosphate (TPP). The functional structure of the enzyme was studied by a limited proteolysis experiment using trypsin. The evidence obtained shows that the enzyme consists of two functional domains, one of which contains an iron-sulfur cluster, which can be isolated as a homodimeric fragment of approximately 220 kDa by proteolysis. The other domain that contains FAD is released as a monomeric fragment of approximately 55 kDa. The pyruvate dehydrogenase reaction is still catalyzed by the large fragment when NADP+ is substituted by methyl viologen, while the small fragment retains a diaphorase-like electron-transfer activity from NADPH to MV. It is thus shown that pyruvate is oxidized in a CoA-dependent reaction to form CO2 and acetyl-CoA in the iron-sulfur domain, and that the two electrons formed are transferred to the FAD domain in which NADP+ is reduced. TPP is considered to be associated in the iron-sulfur domain. The NH2-terminal sequences of the enzyme and its proteolytic fragments reveal that the iron-sulfur domain occurs in the NH2-terminal side of the enzyme. For elucidation of the O2 instability of the enzyme, limited proteolysis was attempted in air. The tryptic fragment derived from the iron-sulfur domain, similar to the native enzyme, appears to be inactivated by direct contact with O2. In contrast, the FAD domain, when separated from the other domain, is quite stable in air, although the diaphorase activity decays when the native enzyme is exposed to O2.

Amino Acid Sequence↗
PubMed1990

Pyruvate:NADP+ oxidoreductase from Euglena gracilis: mechanism of O2-inactivation of the enzyme and its stability in the aerobe.

O2-inactivation of pyruvate:NADP+ oxidoreductase from mitochondria of Euglena gracilis was studied in vitro, and a mechanism which consists of two sequential stages was proposed. Initially, the enzyme is inactivated by the direct action of O2 in a process obeying second-order kinetics. Although the catalytic activity for pyruvate oxidation is lost by this initial inactivation, NADPH oxidation with artificial electron acceptors still occurs. Subsequently, a secondary, O2-independent inactivation occurs, rendering the enzyme completely inactive. Pyruvate stimulates the O2-inactivation while CoA and NADP+ protect the enzyme from O2. The O2-inactivation is accelerated by reduction of the enzyme with pyruvate and CoA. Reactivation of the O2-inactivated enzyme was studied in Ar by incubation with Fe2+ in the presence of some other reducing reagent such as dithiothreitol. The evidence obtained indicates that the partially inactivated enzyme, which retains catalytic activity for NADPH oxidation, can be reactivated, but the completely inactivated enzyme is not. When Euglena cells were exposed to 100% O2 the enzyme in the cells was inactivated by O2, but the rate was quite slow compared with that observed in vitro. The enzyme inactivated by O2 in the cells was almost completely reactivated in vitro by incubation with Fe2+ and other reducing reagents in Ar, suggesting that the secondary, O2-independent inactivation does not occur in situ. When the cells were returned to air, reactivation of the O2-inactivated enzyme in the cells began immediately. The enzyme, kept in isolated, intact mitochondria, was stable in air; however, the enzyme was inactivated by O2 when the mitochondria were incubated with a high concentration of pyruvate.

Animals↗
PubMed1990

[Studies on porphyrin related compounds and tumor tissue affinities. I. Synthesis of a carrier for tumor imaging agent, bifunctional chelating agent coupled porphyrin (ATN-2)].

A carrier for a new tumor imaging agent, a bifunctional chelating agent (BCA)-coupled porphyrin (ATN-2), has been synthesized from protoporphyrin dimethyl ester in 4 steps. At first, the hydrobromination of protoporphyrin dimethyl ester is carried out to obtain a monobromo derivative. The derivative is treated with ethylene glycol. The resulting porphyrin has an ether group at the either 7- or 12-position of the ring. Metallation with GaCl3 of the porphyrin having a ethylene glycol residue affords Ga-metalloporphyrin. Final condensation of the metalloporphyrin with diethylenetriaminepentaacetic acid (DT-PA) gave BCA-coupled porphyrin (ATN-2). The chelation of ATN-2 with 111InCl3 easily afforded [111In]ATN-2. This agent was used for imaging transplantable pancreatic carcinoma in Syrian golden hamster at 72 h after postinjection. The efficacy of the new agent was compared with that of [67Ga]citrate. The images with [111In]ATN-2 were found to be clearer than those with [67Ga]citrate. Therefore, ATN-2, a carrier for 111InCl3, seems to be more useful for tumor imaging agents.

Animals↗
PubMed1989

Pyruvate:NADP+ oxidoreductase from Euglena gracilis: the kinetic properties of the enzyme.

The kinetic properties for the native forward reaction of pyruvate:NADP+ oxidoreductase from Euglena gracilis were determined. The substrate kinetics gave a pattern of a ping-pong mechanism involving a competitive substrate inhibition of CoA against pyruvate. The Km values for pyruvate, CoA, and NADP+ were estimated to be 27, 6.6, and 28 microM, respectively, and the Ki value of CoA against pyruvate was 28 microM. CO2 inhibited noncompetitively against pyruvate and NADP+, and uncompetitively against CoA. Acetyl-CoA showed a competitive inhibition with respect to pyruvate and an uncompetitive inhibition with respect to NADP+. NADPH inhibited competitively versus NADP+, noncompetitively versus CoA, and uncompetitively versus pyruvate. The kinetic behavior is consistent with a two-site ping-pong mechanism involving the substrate inhibition. From the kinetic mechanism, it is proposed that the enzyme has two catalytic sites linked by an intramolecular electron-transport chain. One of these is a thiamine pyrophosphate-containing catalytic site which reacts with pyruvate and CoA to form CO2 and acetyl-CoA, and the other site functions in the reduction of NADP+. In contrast, when methyl viologen was used as an artificial one-electron acceptor substituting for NADP+, the reaction gave a pattern characteristic of an octa uni ping-pong mechanism involving a competitive substrate inhibition of CoA against pyruvate.

Animals↗
PubMed1987

Purification and characterization of pyruvate:NADP+ oxidoreductase in Euglena gracilis.

Pyruvate:NADP+ oxidoreductase was homogeneously purified from crude extract of Euglena gracilis. The Mr of the enzyme was estimated to be 309,000 by gel filtration. The enzyme migrated as a single protein band with Mr of 166,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, suggesting that the enzyme consists of two identical polypeptides. The absorption spectrum of the native enzyme exhibited maxima at 278, 380, and 430 nm, and a broad shoulder was observed around 480 nm; the maximum at 430 nm was eliminated by reduction of the enzyme with dithionite. Reduction of the enzyme with pyruvate and CoA and reoxidation with NADP+ were proved from changes of absorption spectra. The enzyme contained 2 molecules of FAD and 8 molecules of iron. It was also indicated that the enzyme was thiamine pyrophosphate-dependent. The enzyme was oxygen-sensitive, and the reaction was affected by the presence of oxygen. Pyruvate was the most active substrate, but the enzyme was slightly active for 2-oxobutyrate, 3-hydroxypyruvate, and oxalacetate, but not for glyoxylate and 2-oxoglutarate. The native electron acceptor was NADP+, whereas NAD+ was completely inactive. Methyl viologen, benzyl viologen, FAD, and FMN were utilized as artificial electron acceptors, whereas spinach and Clostridium ferredoxins were inactive. Pyruvate synthesis by reductive carboxylation of acetyl-CoA with NADPH as the electron donor occurred by the reverse reaction of the enzyme. The enzyme also catalyzed a pyruvate-CO2 exchange reaction and electron-transfer reaction from NADPH to other electron acceptors like methyl viologen. These results indicate that pyruvate:NADP+ oxidoreductase in E. gracilis is clearly distinct from either the pyruvate dehydrogenase multienzyme complex or pyruvate:ferredoxin oxidoreductase.

Acetyl Coenzyme A↗
PubMed1986

Purification and some properties of short chain-length specific trans-2-enoyl-CoA reductase in mitochondria of Euglena gracilis.

Short chain-length specific trans-2-enoyl-CoA reductase (reductase I), which contributed to mitochondrial fatty acid synthesis, was purified about 200-fold from crude extract of mitochondria in Euglena gracilis. It had a molecular weight of 39,000, and consisted of two dissimilar subunits with molecular weights of 15,000 and 25,000. The enzyme utilized crotonyl-CoA as the most active substrate and showed negative cooperativity in the reaction with the substrate. NADH was the sole electron donor. Some divalent cations were inhibitory to the enzyme when incubated with the enzyme prior to the start of the reaction. The reductase apparently contained loosely bound FAD.

Cations↗
PubMed1986

[Biochemical activity in peritoneal effusion of ovarian malignancy].

This study was provided biochemical findings on ascitic fluid following the treatment of patients with ovarian tumors. The results were as follows: LDH and LDH isozyme. The ascitic fluid from patients with germ cell tumors showed an LDH1 value of 38.8% with an H/M ratio of 2.82, which were significantly higher than those found in the benign tumor group (LDH1, 15.2%: H/M ratio, 1.05). In cases of adenocarcinomas, the LDH5 value was 27.2%, compared to 15.7% in cases of benign tumors. Of 28 patients with adenocarcinoma, 15 patients (53.6%) were positive for this elevation. The decline in total LDH activity and elevation of H/M ratio were observed as a general tendency in patients satisfactorily responding to treatment. ALP and ALP isozyme. The malignant tumor group displayed higher values for both total ALP activity and HSAP in ascitic fluid, as compared with the benign tumor group. In the malignant tumor group, alpha 2 and alpha 2-beta regions were prominent in the isozyme pattern and the isozymes of the same regions remained even after inactivation by heat. The total activity decreased significantly in the responders to treatment. TP, alpha 1-AT, alpha 1-AG, alpha 2-M and IgG. The ascitic fluid levels of alpha 1-AT, alpha 2-M and IgG did not significantly differ among the group of patients with germ cell tumors, the group of patients with ovarian gonadal stroma and the group of patients with benign tumors. In the adenocarcinoma group the alpha 1-AT and alpha 2-M levels were higher than those in the benign tumor group. The ascitic fluid alpha 1-AG level and alpha 1-AG/TP ratio were elevated in tumors of germ cell origin and in adenocarcinomas; they tended to correlate with the degree of malignancy of the tumor. The results of the present study suggest that simultaneous measurement of the ascitic fluid levels of LDH isozymes, ALP isozymes, alpha 1-AG, alpha 1-AT, alpha 2-M and IgG may play a potential adjunctive role in providing information for diagnostic differentiation between benign and malignancy, estimation of the histologic type and extent of neoplastic growth, evaluation of the therapeutic response and prediction of the clinical progress.

Adenocarcinoma↗
PubMed1986

[Experimental chemotherapy of germ cell tumor heterotransplanted to nude mice].

While the treatment of ovarian cancer has made remarkable progress in recent years, the chemotherapy of ovarian germ cell tumor has not as yet been fully established and remains to be improved. We investigated the effectiveness of a single-agent therapy with Vincristine (VCR), Actinomycin D (ACD), and Cyclophosphamide (CPM) against a human undifferentiated dysgerminoma's cell line (JOHYL-1) with the following results. The ratio of the number of viable cells to the total cell population treated for JOHYL-1 cells of ascitic type was 70% with VCR, 58% with CPM and 25% with ACD; hence the efficacy on this malignant cell line was the greatest with ACD followed by VCR and CPM in that descending order. Notably with CPM, a striking antitumor effect was observed from 48 to 24 hours after treatment. The L.I. attained a peak at 24, 18 and 30 hours, respectively, after treatment with VCR, ACD and CPM. The M.I. was as high as a little more than 6% at 36 hours after treatment with VCR. There also was noted a shift in the cell cycle with any of the test drugs. Morphological changes observed in the cell were most obvious with ACD followed in order by VCR and CPM. LDH & isozyme pattern: In these respects there were no striking differences among the three drugs, even though the total enzyme activity was somewhat higher with VCR.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

The physiological role of oxygen-sensitive pyruvate dehydrogenase in mitochondrial fatty acid synthesis in Euglena gracilis.

In Euglena gracilis a malonyl-CoA-independent fatty acid-synthetic system, in which fatty acids are synthesized directly from acetyl-CoA as both primer and C2 donor, occurs in mitochondria, and the system contributes to the wax ester fermentation. The activity of fatty acid synthesis in the mitochondrial system was enhanced about six times when an artificial acetyl-CoA-regenerating system was present, indicating that the fatty acid-synthetic activity is controlled by the ratio of acetyl-CoA against CoA. When fatty acids were synthesized using pyruvate instead of acetyl-CoA as substrate, a high activity, about 30 times higher than that from acetyl-CoA, was found under anaerobic conditions (below 10(-5) M oxygen), while in aerobiosis fatty acids were not synthesized at all. CoA, NADH, and NADP+ were required as cofactors for fatty acid synthesis from pyruvate. It was indicated that high activity of fatty acid synthesis from pyruvate due to the high ratio of acetyl-CoA against CoA was maintained by the action of the oxygen-sensitive pyruvate dehydrogenase found in Euglena mitochondria. When [2-14C]pyruvate was fed into intact mitochondria under anaerobic conditions, radioactive fatty acids were formed in the presence of malate, which provided reducing power for the matrix.

Acetyl Coenzyme A↗
PubMed1985

Factors predisposing to exercise-induced late asthmatic responses.

Seventeen children developed reproducible early and late asthmatic responses (dual reactions) after cycle ergometer exercise. There was a significant correlation between the magnitude of their early and late reactions, emphasizing the direct relationship of these events. No significant differences were observed in the clinical severity of asthma, diurnal variations in FEV1, and extent of the early reaction after exercise between children with dual responses and 19 children with single reactions. These findings suggest that the occurrence of late reactions after exercise is not determined by differences in severity of disease or baseline airway reactivity in the asthmatic subjects. This view is supported by the finding that there was no significant difference in the dose of acetylcholine necessary to elicit a 20% decrease in FEV1 between eight children with dual response and seven children with single early response after exercise. The rate of spontaneous recovery from early reactions was slower in children with dual responses, suggesting that this variable may predict development of late-phase reactions in exercise-induced asthma.

Acetylcholine↗
PubMed1984

Fatty acid synthesis in mitochondria of Euglena gracilis.

A malonyl-CoA-independent fatty acid synthetic system, different from the systems in other subcellular fractions, occurred in mitochondria of Euglena gracilis. The system had ability to synthesize fatty acids directly from acetyl-CoA as both primer and C2 donor using NADH as an electron donor. Fatty acids were synthesized by reversal of beta-oxidation with the exception that enoyl-CoA reductase functioned instead of acyl-CoA dehydrogenase in degradation system. A fairly high activity of enoyl-CoA reductase was found on various enoyl-CoA substrates (C4-C12) with NADH or NADPH. Three species of enoyl-CoA reductase, distinct from each other by their chain-length specificity, were found in Euglena mitochondria, and one of them was highly specific for crotonyl-CoA. It is also discussed that the mitochondrial fatty-acid synthetic system contributes to wax ester fermentation, the anaerobic energy-generating system found in the organism.

Acetyl Coenzyme A↗