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M Inui

Publications and source records attributed to M Inui.

At least 19 recordsLinked to original sources
PubMed1992

Molecular mechanism of regulation of Ca2+ pump ATPase by phospholamban in cardiac sarcoplasmic reticulum. Effects of synthetic phospholamban peptides on Ca2+ pump ATPase.

The molecular mechanism of the regulation of Ca2+ pump ATPase by phospholamban in cardiac sarcoplasmic reticulum was examined using synthetic peptides of phospholamban and purified Ca2+ pump ATPase from cardiac sarcoplasmic reticulum. The phospholamban monomer of 52 amino acid residues contains two distinct domains, the cytoplasmic (amino acids 1-30) and the transmembrane (amino acids 31-52) domains. The peptide corresponding to the amino acids 1-31 of phospholamban (PLN 1-31) decreased the Vmax of the Ca(2+)-dependent ATPase activity in dose-dependent manner, while it had no effect on the affinity of the ATPase for Ca2+ (KCa). On the other hand, the peptide corresponding to the amino acids 28-47 of phospholamban (PLN 28-47) increased the KCa from 0.52 to 1.33 microM without significant change in the Vmax value when reconstituted into vesicles with the ATPase. Essentially the same results as PLN 28-47 were obtained with the peptide corresponding to the amino acids 8-47 of phospholamban (PLN 8-47). The inhibitory effects of PLN 1-31 and PLN 8-47 on the ATPase were reversed by cAMP-dependent phosphorylation of the peptides (Ser16). These results indicate that phospholamban suppresses Ca2+ pump ATPase at two different sites, the cytoplasmic domain for Vmax and the transmembrane domain for KCa, and that cAMP-dependent phosphorylation de-suppresses these inhibitory effects on the ATPase.

Amino Acid Sequence↗
PubMed1992

The effect of intralesional 5-fluorouracil therapeutic implant (MPI 5003) for treatment of basal cell carcinoma.

BACKGROUND: Basal cell carcinomas (BCCs) are usually treated with ablative procedures. A nonsurgical treatment alternative would be of value in selected patients. OBJECTIVE: We evaluated the safety and efficacy of a new preparation for intralesional sustained-release chemotherapy with MPI 5003, 5-Fluorouracil Therapeutic Implant, for treatment of BCCs. METHODS: Two doses of intralesional MPI 5003 (0.25 and 0.5 ml) were compared in a double-blind study of 20 patients with biopsy-proven BCC. One BCC per patient was treated weekly for up to 6 weeks and followed up monthly for 3 months until excisional biopsy for histologic examination. Before excision the cosmetic appearance of the test site was graded. RESULTS: Eighty percent of 10 BCCs treated with 0.5 ml of MPI 5003 had histologically confirmed cures as compared with 60% of 10 tumors treated with the lower dose (0.25 ml). Cosmetic assessments before excision were typically good to excellent. No systemic side effects occurred. CONCLUSION: Results indicate the potential of MPI 5003 for targeted local chemotherapy for BCC.

Adult↗
PubMed1992

Cryo-EM of the native structure of the calcium release channel/ryanodine receptor from sarcoplasmic reticulum.

The native structure of the calcium release channel (ryanodine receptor) from rabbit skeletal muscle has been analyzed in two dimensions from electron micrographs of frozen hydrated specimens. Within a resolution of 3.0 nm there is excellent agreement between the structure as seen in vitreous water and in negative stained specimens. Features seen in the three-dimensional reconstruction of the negatively stained channel can be identified in the projection of the unstained receptor.

Animals↗
PubMed1992

[Molecular size heterogeneity of SPan-1 antigen and co-expression with Lewis phenotype determinants in sera from gastrointestinal malignant diseases].

Molecular size of SPan-1 antigen and co-expression between SPan-1 epitope and Lewis phenotype determinants (LPD) on the same molecule in sera from patients with pancreatic, gastric and colon cancer and in culture medium from cancer cell line were studied. Column chromatography study on culture medium and sera showed that SPan-1 immunoreactivity was found in the void volume region as single major peak, or followed by one or two minor peak in the included volume. All of 4 pancreatic cancer cell lines showed molecular size heterogeneity. Co-expression between SPan-1 epitope and LPD on the same molecule was recognized in sera from cancer patients with Lewis a or Lewis b positive, but not in patients with Lewis a-, b-. Molecular carrying SPan-1 epitope had more frequently SPan-1 epitope than LPD in sera from cancer patients. These findings suggest that molecular size heterogeneity of SPan-1 antigen was more often in pancreatic cancer cells and overexpression of SPan-1 epitope on the same molecule seems to be specific for cancer.

Antigens, Neoplasm↗
PubMed1992

[Gonadal function in young female affective illness associated with the menstrual cycle--in relation to the polycystic ovary syndrome].

The hypothalamo-pituitary-gonadal axis was studied in 10 young manic-depressive or psychotic women whose symptoms obviously fluctuated in association with the menstrual cycle. The common clinical features of these cases were (1) young female aged between 15 and 25, (2) the symptoms fluctuated obviously in association with the menstrual cycle, and (3) severe manic-depressive, or psychotic symptoms. While, in two cases, the depressive or psychotic phases had repeated many times for several years, the rest eight cases did not have a long psychiatric past history. The common hormonal features among these 10 cases were elevated basal LH (7 of 10 cases), decreased basal FSH (6 of 10), greater response of LH and normal response of FSH to LHRH (8 of 8), lack of or insufficient increase of progesterone in the luteal phase (7 of 8), and elevated serum testosterone (5 of 10), androstenedione (4 of 10) and DHEA-S (3 of 9). These abnormalities resemble those of polycystic ovary syndrome (PCOS). Five of the 10 cases showed mild hirsute signs such as mustache, acne, and/or well-developed musculo-skeletal system. An ultrasonographical study revealed polycystic changes in 7 of 10 cases. Ordinary psychotropic pharmacotherapy was not effective sufficiently and hormonal therapy was tried in these 10 cases. Clomiphene citrate was administered on Day 5-9 of the menstrual cycle at a daily dose of 50mg orally in 9 cases, and it was effective to prevent recurrence of manic episode in one case, and to improve manic-depressive or psychotic symptoms in 6 cases. In these 6 cases, the effects were commonly observed within 1 or 2 weeks subsequent to the administration being completed. Daily dexamethasone administration was effective in one case with high serum DHEA-S level in whom clomiphene citrate worsened the psychotic symptoms, and thyroid hormone was effective in one case. In comparison with the pathophysiology of PCOS, a possible relationship was suggested between psychiatric problems and the PCOS-like hormonal abnormalities in these cases.

Adolescent↗
PubMed1992

[Influences of magnesium sulfate on maternal calcium metabolism in preterm labor].

The effects of intravenous magnesium sulfate tocolysis on calcium metabolism were studied in 10 patients with preterm labor. A loading dose of magnesium sulfate (4g) was administered intravenously maintenance intravenous infusion of magnesium sulfate (1g per hour). All patients simultaneously received 50 micrograms ritodrin per minutes by intravenous infusion. Serum magnesium increased from 1.91 +/- 0.06mg/dl to 4.6 +/- 0.71mg/dl at 30 minutes (p < 0.01) and it remained relatively high. The fall in serum calcium corrected by serum total protein was most rapid during the first 30 minutes, from 9.04 +/- 0.47mg/dl to 8.3 +/- 0.27mg/dl (p < 0.01). Urinary excretion of magnesium, represented as the calcium/creatinine ratio, rose markedly from 0.05 +/- 0.01 to 3.18 +/- 0.8 at an hour (p < 0.01) and thereafter remained higher than the baseline level. Changes in urinary excretion of calcium paralleled those of urinary evcretion of magnesium. Serum parathyroid hormone rose from 118 +/- 42.2pg/ml to 294 +/- 121pg/ml at 6 hours (p < 0.05). Serum 1 alpha,25-(OH)2D3-rose from 89.3 +/- 44.2pg/ml to 126 +/- 38.7pg/ml (p < 0.05). Serum calcitonin showed no significant change. These findings indicate that correction of hypocalcemia mainly depends on secretion of parathyroid hormone in the early stage, and thereafter depends on the cooperative action of parathyroid hormone and 1 alpha,25-(OH)2D3.

Adult↗
PubMed1991

Application of the tryptophanase promoter to high expression of the tryptophan synthase gene in Escherichia coli.

The application of an inducible regulation system using the tryptophanase operon promoter (TPase promoter; Ptna) was examined for its high expression of the tryptophan synthase (TS) gene in Escherichia coli. The main problem in the application of Ptna for industrial purposes is catabolite repression by glucose, since glucose is the most abundant carbon source. However, this problem could be avoided by changing glucose to an organic acid, such as succinate, fumarate, malate and acetate, in the course of cultivation after glucose initially added was completely consumed. Under these conditions, L-tryptophan was also used to induce tryptophan synthase. Thus, the specific activity of TS in E. coli strain no. 168 harbouring pBR322F-Ptna TS was increased 500-fold compared to that of the cultured host strain. About 1 mol L-tryptophan/l reaction mixture was formed from indole and L-serine at 37 degrees C for 3.5 h.

Carbon↗
PubMed1991

Effects of monoclonal antibody against phospholamban on calcium pump ATPase of cardiac sarcoplasmic reticulum.

A monoclonal antibody against phospholamban has been reported to increase Ca2+ uptake by cardiac sarcoplasmic reticulum. We compared the effect of this antibody on Ca2+ pump ATPase activity of cardiac sarcoplasmic reticulum vesicles to the effect of cAMP-dependent phosphorylation of phospholamban. The antibody markedly stimulated the Ca(2+)-dependent ATPase activity in parallel to the increase in Ca2+ uptake by cardiac sarcoplasmic reticulum. When the Ca(2+)-dependent profile of the ATPase activity was compared, the KCa was shifted from 1.24 to 0.62 microM by the antibody, whereas cAMP-dependent phosphorylation of phospholamban shifted the KCa to 0.84 microM. When cardiac sarcoplasmic reticulum vesicles were treated with both cAMP-dependent protein kinase and the antibody, the stimulation was the same as that with the antibody alone. Thus, the Ca2+ pump ATPase seems to be fully activated by the antibody. The stoichiometry between Ca2+ uptake and ATPase rate was around 1 and no significant change was observed by the treatment with the antibody. Therefore, the stimulation of Ca2+ uptake of cardiac sarcoplasmic reticulum by the antibody occurred by the stimulation of Ca2+ pump ATPase, not by other mechanisms such as channel activity of phospholamban. These results indicate that the binding of the antibody to phospholamban produces essentially the same mode of action on Ca2+ pump ATPase as that of phospholamban phosphorylation. The antibody and phospholamban phosphorylation appear to release the inhibitory action of phospholamban on Ca2+ pump ATPase, resulting in the stimulation of Ca2+ pump.

Animals↗
PubMed1991

Identification of plasmid partition function in coryneform bacteria.

We have identified and characterized a partition function that is required for stable maintenance of plasmids in the coryneform bacteria Brevibacterium flavum MJ233 and Corynebacterium glutamicum ATCC 31831. This function is localized to a HindIII-NspV fragment (673 bp) adjacent to the replication region of the plasmid, named pBY503, from Brevibacterium stationis IFO 12144. The function was independent of copy number control and was not associated directly with plasmid replication functions. This fragment was able to stabilize the unstable plasmids in cis but not in trans.

Base Sequence↗
PubMed1990

Comparative sequential changes in serum and biliary levels of bile acid components after a single dose of D-galactosamine or partial hepatectomy in the rat.

In order to characterize changes in bile acid profile during liver cell damage and regeneration, levels of bile acids in serum and bile were determined by high performance liquid chromatography (HPLC) in F344 rats treated with a single dose of D-galactosamine (galactosamine, 300 mg/kg, i.p.) or subjected to two-thirds partial hepatectomy (PH). In the serum, galactosamine caused elevation of conjugated bile acids such as taurocholic acid (TCA) and tauro-beta-muricholic acid (T beta MCA) at the 24 and 48-h time points, whereas unconjugated bile acids including cholic acid (CA) at 24 h and hyodeoxycholic acid (HDCA) at 48 h were increased after PH. In the bile, elevation of TCA showed most remarkable elevation at the 24-h time point in the galactosamine-treated group. All components of biliary bile acids showed rapid decreases from 24 to 48 h. The results demonstrated that while liver tissue damaged by galactosamine is able to conjugate bile acids it allows leakage into the blood stream. In contrast, the results for rats subjected to PH indicated that liver cells during DNA synthesis are not capable of conjugating all free bile acids with taurine although a similar leakage occurs. It is concluded that obvious elevation of serum TCA or CA and biliary T beta MCA could be a useful indicator of hepatocellular proliferation.

Animals↗
PubMed1990

Molecular mechanism of calcium uptake and release by cardiac sarcoplasmic reticulum.

Cardiac sarcoplasmic reticulum (SR) plays a special role in controlling free calcium ions (Ca) in heart muscle cells. Ca stored in the SR is released through the Ca release channels when the sarcolemmal membrane is depolarized, thereby inducing contraction, while Ca is reaccumulated by the Ca pump to induce relaxation. In the latter process, the Ca pump of cardiac SR has a regulatory system by cAMP-dependent phosphorylation of a SR protein, phospholamban. Recently, significant progress has been achieved in understanding the molecular mechanisms of Ca release and uptake and its regulation. The structures of the Ca pump and phospholamban have been defined at molecular levels. A direct interaction between these two proteins was demonstrated. The Ca release channel was identified, and turned out to be the foot structure which in situ connects the SR to the sarcolemma/transverse tubule.

Amino Acid Sequence↗
PubMed1990

Electroporation-transformation system for coryneform bacteria by auxotrophic complementation.

We evaluated electroporation as an alternative system for genetic exchange for one of the coryneform bacteria, Brevibacterium flavum MJ233. The maximum number of transformants, 6 x 10(4) cells, was obtained when cells were cultured with Penicillin G (1 U/ml) and harvested at the middle-log phase. Electroporation was done using 12.5 kV/cm of pulse field strength, 1 x 10(10) cells, and 1 microgram of plasmid DNA. Other coryneform bacteria, Brevibacterium lactofermentum ATCC 13869, Corynebacterium glutamicum ATCC 31830, and B. stationis IFO 12144 were also transformed by electroporation. Electroporation has the advantage that intact cells can be used as host cells without the need for protoplast formation and regeneration. Moreover, minimal medium can be used, so auxotrophic complementation of the transformants is possible.

Brevibacterium↗
PubMed1990

[Gallium-67 myocardial imaging for the detection of adriamycin cardiomyopathy].

To detect Adriamycin cardiomyopathy, radionuclide myocardial imagings with Tl-201, Tc-99m pyrophosphate, I-123 metaiodobenzylguanidine and Ga-67 were performed in a 49 year-old-woman receiving Adriamycin (a total dose of 230 mg/m2) for the treatment of breast cancer. This patient demonstrated symptoms of congestive heart failure 2 months after the last intravenous administration. At the period of performing the radionuclide studies, echocardiographic LV ejection fraction (EF) was 22%. Despite severe deterioration of cardiac function, Tl-201 SPECT demonstrated no defect and Tc-99m pyrophosphate (PYP) SPECT demonstrated no positive finding. I-123 metaiodobenzylguanidine (MIBG) scintigraphy demonstrated no regional defect. However, I-123 MIBG washout rate during 4 hours was markedly enhanced, probably reflecting abnormalities of norepinephrine kinetics due to the progression of heart failure. Compared to these pharmaceuticals, Ga-67 was diffusely accumulated in the heart. Then, 5 months after the first study, when LV EF improved to 30% and congestive symptoms disappeared probably owing to beta-blockade therapy, myocardial accumulation of Ga-67 markedly reduced. It has been reported that Ga-67 accumulates in malignant tumor cells and leukocytes. Since, in Adriamycin cardiomyopathy, myocardial accumulation of leukocytes with myocardial fibrotic changes have been histologically demonstrated, the results of Ga-67 scintigraphy may reflect the accumulation of leukocytes. Thus, this case indicates that Ga-67 scintigraphy is advantageous for detecting Adriamycin cardiomyopathy and may be more useful than Tl-201 and Tc-99m PYP scintigraphies.

Doxorubicin↗
PubMed1989

Nature and site of phospholamban regulation of the Ca2+ pump of sarcoplasmic reticulum.

The rapid removal of Ca2+ ions from the cytosol, necessary for the efficient relaxation of cardiac muscle cells, is performed by the Ca2+-pumping ATPase of the sarcoplasmic reticulum. The calcium pump is activated by cyclic AMP- and calmodulin-dependent phosphorylation of phospholamban, an integral membrane protein of the sarcoplasmic reticulum. Using a heterobifunctional crosslinking agent which can be cleaved and photoactivated, we provide evidence for a direct interaction between the two proteins. Only the non-phosphorylated form of phospholamban interacts with the ATPase, demonstrating that phospholamban is an endogenous inhibitor that is removed from the ATPase by phosphorylation. Non-phosphorylated phospholamban interacts only with the calcium-free conformation of the ATPase and is released when it is converted to the calcium-bound state. We localized the site of interaction to a single peptide isolated after cyanogen bromide cleavage of the ATPase. The peptide derives from a domain just C-terminal to the aspartyl phosphate of the active site. This domain is unique to ATPases of the sarcoplasmic reticulum in that it has no homology with any other phosphorylation-type ion pump. The domain occurs in both slow- and fast-twitch isoforms of the ATPase, even though phospholamban is not expressed in fast-twitch muscles.

Adenosine Triphosphatases↗
PubMed1989

Three-dimensional architecture of the calcium channel/foot structure of sarcoplasmic reticulum.

The calcium channel responsible for the release of Ca2+ from the sarcoplasmic reticulum of skeletal muscle during excitation-contraction coupling has recently been identified and purified. The isolated calcium channel has been identified morphologically with the 'foot' structures which are associated with the junctional face membrane of the terminal cisternae of sarcoplasmic reticulum. In situ, the foot structure extends across the gap of the triad junction from the terminal cisternae of the reticulum to the transverse tubule. We describe here the three-dimensional architecture (3.7 nm resolution) of the calcium channel/foot structure from fast-twitch rabbit skeletal muscle, which we determined from electron micrographs of isolated, non-crystalline structures that had been tilted in the electron microscope. The reconstruction reveals two different faces and an internal structure in which stain accumulates at several interconnected locations, which could empty into the junctional gap of the triad junction. The detailed architecture of the channel complex is relevant to understanding both the physical path followed by calcium ions during excitation-contraction coupling and the association of the terminal cisternae and the transverse tubules in the triad junction.

Animals↗
PubMed1989

Positive cooperativity of ryanodine binding to the calcium release channel of sarcoplasmic reticulum from heart and skeletal muscle.

Ryanodine is a specific ligand for the calcium release channel which mediates calcium release in excitation-contraction coupling in muscle. In this study, ryanodine binding in sarcoplasmic reticulum from heart muscle and skeletal muscle is further compared and correlated with function. The new findings include the following: (1) Two types of binding, high affinity (KD1 approximately 5-10 nM) and low affinity (KD2 approximately 3 microM), can now be discerned for the skeletal muscle receptor. KD1 is approximately the same as and KD2 of similar magnitude to that previously reported for heart. (2) The dissociation rates for the high-affinity binding have been directly measured for both heart and skeletal muscle (t1/2 approximately 30-40 min). These rates are more rapid than previously reported (t1/2 approximately 14 h). (3) KD1's obtained from the ratio of the dissociation and association rate constants agree with the dissociation constant measured by equilibrium binding Scatchard analysis. (4) Ryanodine binding to the low-affinity site can be correlated with a decrease in the dissociation rate constant (k-1) of the high-affinity site, and thereby in the apparent dissociation constant (KD1). The inhibition constant (KI) for inhibiting the high-affinity off rate obtained from a double-reciprocal plot of the change in off rate vs [ryanodine] is practically the same in heart (0.66 microM) and skeletal muscle (0.64 microM) and in the range of the KD2. The binding of cold ryanodine to the low-affinity site appears to lock the bound [3H]ryanodine onto the high-affinity site rather than to exchange with it. Thus, in this sense, the ryanodine receptor exhibits "positive cooperativity".(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaloids↗
PubMed1989

Comparison of the calcium release channel of cardiac and skeletal muscle sarcoplasmic reticulum by target inactivation analysis.

The calcium release channel of sarcoplasmic reticulum which triggers muscle contraction in excitation-contraction coupling has recently been isolated. The channel has been found to be morphologically identical with the feet structures of the junctional face membrane of terminal cisternae and consists of an oligomer of a unique high molecular weight polypeptide. In this study, we compare the target size of the calcium release channel from heart and skeletal muscle using target inactivation analysis. The target molecular weights of the calcium release channel estimated by measuring ryanodine binding after irradiation are similar for heart (139,000) and skeletal muscle (143,000) and are smaller than the monomeric unit (estimated to be about 360,000). The target size, estimated by measuring polypeptide remaining after irradiation, was essentially the same for heart and skeletal muscle, 1,061,000 and 1,070,000, respectively, indicating an oligomeric association of protomers. Thus, the calcium release channel of both cardiac and skeletal muscle reacts uniquely with regard to target inactivation analysis in that (1) the size by ryanodine binding is smaller than the monomeric unit and (2) a single hit leads to destruction of more than one polypeptide, by measuring polypeptide remaining. Our target inactivation analysis studies indicate that heart and skeletal muscle receptors are structurally very similar.

Alkaloids↗