Biomedical subjects

H Matsubara

Publications and source records attributed to H Matsubara.

At least 235 records · Page 13Linked to original sources

PubMed1992

A synthetic analogue for the active site of plant-type ferredoxin: two different coordination isomers by a four-cys-containing [20]-peptide.

The (Fe2S2)2+ complex of an artificial 20-peptide ligand, Ac-Pro-Tyr-Ser-Cys-Arg-Ala-Gly-Ala-Cys-Ser-Thr-Cys-Ala-Gly-Pro-Leu-Leu-T hr-Cys- Val-NH2, containing an invariant Cys-A-B-C-D-Cys-X-Y-Cys (A, B, C, D, X, Y = amino acid residues) fragment of plant-type ferredoxins was synthesized by a ligand exchange method with [Fe2S2(S-t-Bu)4]2-. 1H-nmr spectroscopic and electrochemical data of the complex indicate the presence of two coordination isomers. One of them having a Cys-X-Y-Cys bridging coordination to the two Fe(III) ions, has the (Fe2S2)2+ core environment similar to those of the denatured plant-type ferredoxins and exhibits a positive shifted redox potential at -0.64 V vs saturated colonel electrode (SCE) in N,N-dimethylformamide (DMF). Another isomer with the Cys-A-B-C-D-Cys bridging coordination shows a negative redox potential at -0.96 V vs SCE in DMF.

Amino Acid Sequence↗

PubMed1992

Kinetic mechanism of beef heart ubiquinol:cytochrome c oxidoreductase.

The electron transfer from ubiquinol-2 to ferricytochrome c mediated by ubiquinol:cytochrome c oxidoreductase [E.C. 1.10.2.2] purified from beef heart mitochondria, which contained one equivalent of ubiquinone-10 (Q10), was investigated under initial steady-state conditions. The Q10-depleted enzyme was as active as the Q10-containing one. Double reciprocal plots for the initial steady-state rate versus one of the two substrates at various fixed levels of the other substrate gave parallel straight lines in the absence of any product. Intersecting straight lines were obtained in the presence of a constant level of one of the products, ferrocytochrome c. The other product, ubiquinone-2, did not show any significant effect on the enzymic reaction. Ferrocytochrome c non-competitively inhibited the enzymic reaction against either ubiquinol-2 or ferricytochrome c. These results indicate a Hexa-Uni ping-pong mechanism with one ubiquinol-2 and two ferricytochrome c molecules as the substrates, which involves the irreversible release of ubiquinone-2 as the first product and the irreversible isomerization between the release of the first ferrocytochrome c and the binding of the second ferricytochrome c. Considering the cyclic electron transfer reaction mechanism, this scheme suggests that the binding of quinone or quinol to the enzyme and electron transfer between the iron-sulfur center and cytochrome c1 are rigorously controlled by the electron distribution within the enzyme.

Animals↗

PubMed1992

[A clinical study of postinfarction angina (PIA): the significance of electrocardiographic ST segment changes during anginal attacks].

We studied the clinical significance of electrocardiographic ST segment changes during PIA attacks. Of 478 AMI patients admitted to the CCU of our hospital within 48 hours after onset, we evaluated 73 (15.3%) with PIA. According to electrocardiographic ST segment changes during PIA attacks, the patients were divided into three groups, namely ST elevation at the same infarction site (same site elevation group), ST depression at the same site (same site depression group), and ST depression at other sites (other site depression group), and their pathological condition was studied. There were 33 patients (45.2%) in the same site elevation group, 19 (26.0%) in the same site depression group, and 21 (28.8%) in the other site depression group. The predominant infarction areas were anteroseptal and inferior wall in the same site elevation group, NTMI in the same site depression group, and inferior wall in the other site depression group. PIA usually occurred within 4 days after the onset of infarction in the same site elevation group, and within 5-7 days in the other site depression group, but no uniform trend was observed in the same site depression group. With respect to the number of vessels showing disease, cases of single-vessel disease tended to predominate in the same site elevation group, while cases of three-vessel disease tended to predominate in the same site depression group and the other site depression group. Stenosis rates in the vessels responsible for infarction were high in the same site elevation group in the acute period. Prognoses were poorest in the same site depression group.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗

PubMed1992

Amino acid sequences of ferredoxins from Alocasia macrorrhiza Schott in Papua New Guinea.

The amino acid sequences of ferredoxin isoproteins (Fd A and Fd B) from Alocasia macrorrhiza Schott in Papua New Guinea were determined. They consisted of single polypeptide chains of 97 and 98 residues, respectively, and both Fds had a molecular mass of 10,800 Da. There was an 88% identity between the sequences of the isoproteins (Fd A and Fd B). These sequences were compared with those of the closely related plant Fds and their phylogenetic relationships are discussed.

Amino Acid Sequence↗

PubMed1992

[Signification of liver metastases of colorectal cancer with special reference to recurrence in the residual liver after hepatic resection].

In the patients with liver metastases of colorectal cancer, pre-and post operative intra-arterial infusion chemotherapy was evaluated for prevention of recurrence in the residual liver after hepatic resection. Materials are sixty-five hepatectomized patients from May 1981 to 1992. Therapies were subdivided into five groups. I: pre-and postoperative non-therapy (n = 3); II: postoperative chemotherapy (n = 22); III: postoperative intra-arterial infusion chemotherapy (n = 12); IV: pre-operative intra-arterial infusion chemotherapy + postoperative chemotherapy (n = 15); and V: pre-and postoperative intra-arterial infusion chemotherapy (n = 13). In recurrence rate in the residual liver, I to IV groups showed as high as 50-100%. However, the disease-free survival rate was 100% in V group, revealing a significant difference between the other four groups. Accordingly, in order to prevent recurrence in the residual liver of hepatectomized patients with liver metastases of colorectal cancer and prolong the disease-free interval, we consider that pre-and post-operative intra-arterial infusion chemotherapy can be effective, compared to pre-or postoperative intra-arterial infusion chemotherapy alone.

Administration, Oral↗

PubMed1992

[Complications and their management in intraarterial infusion chemotherapy].

Complications and its management were evaluated in intraarterial infusion chemotherapy for 188 patients with advanced carcinoma of the digestive organs from 1975 to Sept. 1991. Subjects were divided into four groups: Group I was 62 patients in whom the tip of the catheter without knots was established in the abdominal aorta via celiac axis, Group II consisted of 72 patients with the tip of the catheter without knots in the common hepatic artery. Group III had 35 patients with the tip of the catheter with knots (Anthron catheter) in the common hepatic artery. Group IV was 19 patients with the tip of the anthron catheter connected to the Infuse A-Port in the common hepatic artery. The most frequent complications seen among Group I, II and III were caused by catheter thrombosis (11.3%) in Group I, spontaneous dislodgement of catheter (26.4%) in Group II and extravasation (20%) in Group III. By using 16 gauge Toray Anthron catheter with Heparin coating on its inner and outer surfaces, the number of complications in Group I and II was kept smaller. Extravasation, on the other hand, has been less frequently seen in Group III by establishing the tip of the catheter at the branching site of the gastroduodenal artery from the common hepatic artery. Complications in Group IV (19 patients) were noted only in 3 patients, i.e., extravasation, subcutaneous necrosis and subcutaneous abscess, respectively. Therefore, we concluded that Group IV showed the most favorable intraarterial infusion chemotherapy with the most infrequent complications.

Aorta↗

PubMed1991

Transcriptional analysis of two Rhodobacter capsulatus ferredoxins by translational fusion to Escherichia coli lacZ.

Plasmids which contained the translational fusion of Escherichia coli lacZ to Rhodobacter capsulatus ferredoxin genes, fdxN and fdxA, were constructed. Effects of growth conditions on the expression of each ferredoxin were analyzed by measuring the beta-galactosidase activity in R. capsulatus which harbored a corresponding plasmid. Transcription of fdxN::lacZ, the ferredoxin I fusion gene, was regulated at least 100-fold by either NH4+ or O2 but not by illumination, confirming that fdxN belongs to the nif-gene family. Transcription of fdxA::lacZ, the ferredoxin II fusion gene, however, was constant under all the conditions surveyed, suggesting that the protein has some constitutive function(s).

Escherichia coli↗

PubMed1991

Crystallization and preliminary X-ray crystallographic studies of bovine heart mitochondrial cytochrome bc1 complex.

Cytochrome bc1 complex (ubiquinol:ferricytochrome c oxidoreductase, EC. 1.10.2.2) from bovine heart mitochondria was crystallized by a batchwise method from protein solution containing sucrose monolaurate using polyethylene glycol-4000 as a precipitant. The red parallelepiped crystals grew to a size of approximately 1 mm x 1 mm x 1 mm. The crystalline protein showed enzymic activity catalyzing electron transfer from ubiquinol-2 to cytochrome c. The subunit composition and absorption spectrum of the crystalline enzyme were identical to those reported previously for the enzyme in solution. The crystal diffracted X-rays to 7.5 A resolution. The diffraction pattern indicated a monoclinic form, space group P2(1), and unit-cell constants of a = 196 A, b = 179 A, c = 253 A and beta = 97 degrees. Most probably four functional units are present in an asymmetric unit.

Animals↗

PubMed1991

Pretranslational mechanisms determine the type of potassium channels expressed in the rat skeletal and cardiac muscles.

We have cloned a cDNA (RMK2) coding for a Shaker type delayed rectifier K+ channel from a rat skeletal muscle cDNA library. The clone encodes a putative protein of 602 amino acids, identical with a rat brain K+ channel Kv1 (Swanson, R., Marshall, R., Smith, J. S., Williams, J. B., Boyle, M. B., Folander, K., Luneau, C. J., Antanavage, J., Oliva, C., Burhow, S. A., Bennet, C., Stein, R. B., and Kaczmarek, L. K. (1990) Neuron 4, 929-939). Northern blot analysis showed that RMK2 is expressed in skeletal and cardiac muscle. RNase protection analysis showed that the 3'-noncoding regions of the brain, cardiac, and skeletal muscle RMK2 transcripts are identical. Cloning of the gene confirmed that the protein is encoded by a single exon (Swanson et al. (1990) Neuron 4, 929-939). We expressed RMK2 in Xenopus oocytes and showed that it encodes noninactivating delayed rectifier K+ channels, resistant to block by external tetraethylammonium, with a small unitary conductance of 8.0 picosiemens. Coinjection of RMK2 and RCK1 (RMK1) (Baumann, A., Grupe, A., Ackermann, A., and Pongs, O. (1988) EMBO J. 7, 2457-2463; Koren, G., Liman, E. R., Logothetis, D. E., Nadal-Ginard, B., and Hess, P. (1990) Neuron 4, 39-51) into Xenopus oocytes resulted in the expression of currents that have tetraethylammonium inhibition curves that differ from the linear combination of inhibition curves of the two types expressed individually. Thus, RMK2 and RCK1 (RMK1) can form heteromultimers. RNA blot hybridization analysis revealed that the RMK2 transcript is developmentally regulated in a different manner in the rat skeletal muscle, ventricle, and atrium.

Aging↗

PubMed1991

Genetic analysis of functional differences among distinct ferredoxins in Rhodobacter capsulatus.

Rhodobacter capsulatus has been known to possess two ferredoxins (I and II) with distinct physicochemical and structural properties: ferredoxin I is a 2[4Fe-4S] type and the other is a [3Fe-4S] [4Fe-4S] type. To analyze their possible functional differences, their genes (fdxN and fdxA) were cloned, sequenced, and subjected to interposon mutagenesis experiments. The former gene was adjacent to a gene encoding a chloroplast-type [2Fe-2S] ferredoxin (fdxC). Mutants with inactivated fdxN and/or fdxC were obtained, and they showed virtually no growth under nitrogen-fixing conditions. Complementation experiments confirmed that both fdxN and fdxC were required for nitrogen fixation. On the other hand, we have not been able to disrupt fdxA under the screening conditions surveyed, including conditions that do not require nitrogenase activity for growth, suggesting that ferredoxin II could have an unknown essential role(s). These indicate functional differences among multiple ferredoxins in one bacterium other than in cyanobacterial heterocysts and indispensability of certain ferredoxins in nitrogen fixation other than Rhizobium meliloti FdxN.

Amino Acid Sequence↗

PubMed1991

Role of glycosaminoglycans in the regulation of T cell proliferation induced by thymic stroma-derived T cell growth factor.

The present study investigates the regulatory effects of glycosaminoglycans such as heparin and heparan sulfate on T cell proliferation induced by thymic stromal cell monolayer or its derived T cell growth factor (TCGF). A thymic stromal cell clone (MRL104.8a) supported the growth of Ag-specific, IL-2-dependent Th cell clone (9-16) in the absence of Ag and IL-2 by producing a unique TCGF designated as thymic stroma-derived T cell growth factor (TSTGF). The addition of heparin to cultures in which the growth of 9-16 Th cells was otherwise stimulated by the MRL104.8a monolayer or a semipurified sample of the TSTGF resulted in heparin dose-dependent inhibition of 9-16 Th proliferation. The dose of heparin required for inducing 50% reduction of TSTGF-induced proliferation of Th at a given cell number was found to be proportional to the magnitude of the TSTGF added to cultures, suggesting that heparin exerted its inhibitory effect by binding to the TSTGF rather than by acting on Th cells. A similar growth-inhibiting effect of heparin was observed in IL-7-dependent proliferation of pre-B cell line or Th, but not in IL-2-dependent T cell proliferation or IL-3-dependent myeloid cell proliferation. A strong affinity of TSTGF and IL-7 for heparin was confirmed by the fact that both TSTGF and IL-7 adhered to columns of heparin-agarose and were eluted by salt. When various glycosaminoglycans were tested for the heparin-like Th growth-regulatory capacity, heparan sulfate exhibited Th growth-inhibiting ability comparable to that observed for heparin. These results indicate that the activity of thymic and/or bone marrow stroma-derived lymphocyte growth factor (TSTGF/IL-7) but not of Th-producing TCGF (IL-2) is negatively regulated by heparin or heparan sulfate, which would represent major glycosaminoglycans in the extra-cellular matrix of stromal cells.

Administration, Topical↗

PubMed1991

The nirSTBM region coding for cytochrome cd1-dependent nitrite respiration of Pseudomonas stutzeri consists of a cluster of mono-, di-, and tetraheme proteins.

Genes for respiratory nitrite reduction (denitrification) of Pseudomonas stutzeri are clustered within 7 kbp. A 4.6-kbp Hind III-Kpn I fragment carrying nirS, the structural gene for cytochrome cd1, was sequenced. An open reading frame immediately downstream of nirS codes for a 22.8-kDa protein with four heme c-binding motifs. Mutagenesis of this gene causes an apparent defect in electron donation to cytochrome cd1. Following this ORF are the structural genes for cytochrome c552, cytochrome c551, and ORF5 that codes for a 11.9-kDa monoheme protein. All cytochromes have a signal sequence for protein export.

Amino Acid Sequence↗

PubMed1991

The amino acid sequences of two 13 kDa polypeptides and partial amino acid sequence of 30 kDa polypeptide of complex I from bovine heart mitochondria: possible location of iron-sulfur clusters.

Mitochondrial NADH:ubiquinone oxidoreductase (complex I) is the most complicated system in the respiratory chain. It consists of many subunits, some of which hold iron-sulfur clusters, but structural information is still limited. The amino acid sequences of two 13 kDa polypeptides, 13 kDa-A and 13 kDa-B polypeptides, of iron-sulfur protein fraction (IP) of bovine heart mitochondrial complex I were determined by a combination of protease digestion, Edman degradation, and carboxypeptidase digestion. The 13 kDa-A polypeptide was composed of 96 amino acids with a molecular weight of 10,536. The 13 kDa-B polypeptide consisted of 114 amino acids and had an acetylated amino terminus. The molecular weight of this protein was calculated to be 13,130 including the acetyl group. These proteins had no obvious sequence similarity to other known proteins. The partial amino acid sequence of 30 kDa-B polypeptide of IP was also determined to reveal a characteristic arrangement of cysteine residues that could be involved in iron-sulfur cluster formation.

Amino Acid Sequence↗

PubMed1991

The amino acid sequence of the 9 kDa polypeptide and partial amino acid sequence of the 20 kDa polypeptide of mitochondrial NADH:ubiquinone oxidoreductase.

Mitochondrial NADH:ubiquinone oxidoreductase (complex I) is the most complicated enzyme in the respiratory chain and is composed of at least 26 distinct polypeptides. Two hydrophilic subfractions of bovine heart complex I were systematically resolved into individual polypeptides by chromatography. Three polypeptides (51, 24, and 9 kDa) were isolated from the flavoprotein fraction (FP) of complex I, and the complete amino acid sequence of the 9 kDa polypeptide was determined. The 9 kDa polypeptide is composed of 75 amino acids with a molecular weight of 8,437. This protein exhibits no obvious sequence similarity to other proteins. The iron-sulfur protein fraction (IP) of complex I was separated into eight polypeptides, 75, 49, 30, 20, 18, 15, 13 kDa-A, and 13 kDa-B. The 20 kDa polypeptide was recognized as a novel component of IP for the first time. The N-terminal and several peptide sequences of the 20 kDa polypeptide were determined. Comparison of the sequences revealed significant sequence similarities of the 20 kDa polypeptide to the psbG gene products encoded in the chloroplast genome. The conserved sequence in these proteins was also found in the small subunit of the nickel-containing hydrogenases. These results suggest that complex I is related to other redox enzyme complexes.

Amino Acid Sequence↗

PubMed1991

Crystallization and preliminary X-ray diffraction study of cytochrome c552 from Hydrogenobacter thermophilus.

Cytochrome c552 from a thermophilic hydrogen-oxidizing bacterium, Hydrogenobacter thermophilus, exhibits remarkable thermostability. The oxidized cytochrome c552 has been crystallized in an ethanol/water mixture by means of the vapor diffusion method. The crystals belong to the orthorhombic system, space group P2(1)2(1)2, with unit cell dimensions of a = 93.4 A, b = 52.9 A, and c = 32.4 A. Most probably the asymmetric unit contains two molecules of cytochrome c552. The crystals diffract X-rays to better than 2.5 A resolution and are stable to X-ray irradiation.

Bacteria, Aerobic↗

PubMed1991

Roles of ATP and NADPH in formation of the fe-s cluster of spinach ferredoxin.

Ferredoxin (Fd) in higher plants is encoded by a nuclear gene, synthesized in the cytoplasm as a larger precursor, and imported into the chloroplast, where it is proteolytically processed, and assembled with the [2Fe-2S] cluster. The final step in the biosynthetic pathway of Fd can be analyzed by a reconstitution system composed of isolated chloroplasts and [(35)S]cysteine, in which [(35)S]sulfide and iron are incorporated into Fd to build up the (35)S-labeled Fe-S cluster. Although a lysed chloroplast system shows obligate requirements for ATP and NADPH, in vitro chemical reconstitution of the Fe-S cluster is generally thought to be energy-independent. The present study investigated whether ATP and NADPH in the chloroplast system of spinach (Spinacia oleracea) are involved in the supply of [(35)S]sulfide or iron, or in Fe-S cluster formation itself. [(35)S]Sulfide was liberated from [(35)S] cysteine in an NADPH-dependent manner, whereas ATP was not necessary for this process. This desulfhydration of [(35)S]cysteine occurred before the formation of the (35)S-labeled Fe-S cluster, and the amount of radioactivity in [(35)S]sulfide was greater than that in (35)S-labeled holo-Fd by a factor of more than 20. Addition of nonradioactive sulfide (Na(2)S) inhibited competitively formation of the (35)S-labeled Fe-S cluster along with the addition of nonradioactive cysteine, indicating that some of the inorganic sulfide released from cysteine is incorporated into the Fe-S cluster of Fd. ATP hydrolysis was not involved in the production of inorganic sulfide or in the supply of iron for assembly into the Fe-S cluster. However, ATP-dependent Fe-S cluster formation was observed even in the presence of sufficient amounts of [(35)S]sulfide and iron. These results suggest a novel type of ATP-dependent in vivo Fe-S cluster formation that is distinct from in vitro chemical reconstitution. The implications of these results for the possible mechanisms of ATP-dependent Fe-S cluster formation are discussed.

Journal Article↗

PubMed1991

Formation of the fe-s cluster of ferredoxin in lysed spinach chloroplasts.

In vitro formation of the (35)S-labeled Fe-S cluster of ferredoxin (Fd) has been achieved by incubating apo-Fd and [(35)S]cysteine with osmotically lysed chloroplasts of spinach (Spinacia oleracea). Correct integration of the (35)S-labeled Fe-S cluster into Fd was verified on the basis of the following: (a) Under nondenaturing conditions, (35)S-labeled holo-Fd showed the same electrophoretic mobility as authentic holo-Fd; (b) (35)S-labeled holo-Fd showed an ability to bind Fd-NADP(+) reductase; (c) the (35)S-labeled moiety was removed from the Fd polypeptide by TCA treatment but not by 2-mercaptoethanol treatment; (d) externally added pea II apo-Fd was converted to (35)S-labeled holo-Fd. This reconstitution was dependent on both ATP and light, and formation of the (35)S-labeled Fe-S cluster was observed upon addition of ATP or when an ATP generation-system was constructed in the light. In contrast, ATP-consuming systems abolished the Fe-S cluster formation. A non-hydrolyzable ATP analog was unable to serve as an ATP substitute, indicating the requirement of ATP hydrolysis for cluster formation. GTP was able to substitute for ATP, but CTP and UTP were less effective. Fe-S cluster formation in lysed chloroplasts was stimulated by light even in the presence of added ATP. Light stimulation was inhibited by DCMU or methyl viologen but not by NH(4) (+). NADPH was able to substitute for light, indicating that light energy is required for the production of reducing compounds such as NADPH in addition to the generation of ATP. These results confirm the requirement of light for the Fe-S cluster formation observed previously in intact chloroplasts.

Journal Article↗

PubMed1991

Iodothyronine 5'-deiodinase activity in cultured rat myocardial cells: characteristics and effects of triiodothyronine and angiotensin II.

Using a primary culture of neonatal rat heart, we investigated the properties of iodothyronine 5'-deiodinating activity in the heart. 125I- release from [125I] reverse T3 incubated with cell homogenates depended on the concentrations of protein and dithiothreitol, pH, incubation time, and temperature of the incubation mixture. The activity was almost completely inhibited by 10(-3)-10(-5) M propylthiouracil and had the higher affinity for reverse T3 than T4. These findings indicate that type I iodothyronine 5'-deiodinase(I-5'-D) exists in cultured neonatal rat myocardial cells. Then, we studied the direct effects of T3, insulin, glucocorticoid, and angiotensin II (AII) on myocardial I-5'-D. The addition of 10(-9)-10(-7) M T3 or 10(-9)-10(-6) M AII to the culture medium increased I-5'-D activity in a dose-dependent manner. Insulin and dexamethasone, however, had no significant effects. Kinetic studies revealed that maximum velocities in T3- and AII-treated cells were 2.1- and 1.8-fold above the control value, respectively, whereas the apparent Michaelis-Menten constant did not alter significantly both in T3- and AII-treated cells. Moreover, the treatment of cyclohexamide combined with T3 or AII completely abolished the stimulating effect of these agents on I-5'-D activity. From these data, it is suggested that both T3 and AII increase the activity of myocardial I-5'-D by their direct actions to the heart, probably through the new synthesis of I-5'-D.

Angiotensin II↗