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M Ikeuchi

Publications and source records attributed to M Ikeuchi.

At least 37 records · Page 2Linked to original sources
PubMed2000

Dome-shaped proximal tibial osteotomy using percutaneous drilling for osteoarthritis of the knee.

We have improved a surgical technique for proximal tibial osteotomy that involves percutaneous drillings. We performed the modified dome-shaped proximal tibial osteotomy on 44 knees in 42 patients (8 men and 34 women) with an average age of 66 years (range 50-78 years) for osteoarthritis of the knee. The mean follow-up period was 39 months (range 24-63 months). The varus angle was 4 degrees +/- 3.6 degrees (mean +/- SD) preoperatively, and the valgus angle was 12 degrees +/- 3.3 degrees postoperatively. Pain relief was obtained in all cases postoperatively. Transient pin tract infection occurred in one case, but it resolved completely following local irrigation. Intercondylar fracture of the upper fragment with no displacement was noted in two patients. They were treated with AO cancellous screw fixation, and improvement of pain was obtained in both cases. Osteotomy drill guide instruments are useful for accurately performing dome-shaped osteotomy. Our proximal tibial dome osteotomy with an external fixator allowed early motion and accurately maintained the angle of correction.

Aged↗
PubMed2000

Novel putative photoreceptor and regulatory genes Required for the positive phototactic movement of the unicellular motile cyanobacterium Synechocystis sp. PCC 6803.

Synechocystis: sp. PCC 6803 is a unicellular motile cyanobacterium, which shows positive or negative phototaxis on agar plates under lateral illumination. By gene disruption in a substrain showing of positive phototaxis, it was demonstrated that mutants defective in sll0038, sll0039, sll0041, sll0042 or sll0043 lost positive phototaxis but showed negative phototaxis away from the light source. Mutants of sll0040, which is located within the cluster of these genes, retained the capacity of positive phototaxis but to a lesser extent than the parent cells. These genes are homologous to che genes, which are involved in flagellar switching for bacterial chemotaxis. Interestingly, sll0041 (designated pisJ1) is predicted to have a chromophore-binding motif of phytochrome-like proteins and a signaling motif of chemoreceptors for bacterial chemotaxis. It is strongly suggested that the positive phototactic response was mediated by a phytochrome-like photoreceptor and CheA/CheY-type signal transduction system.

Amino Acid Sequence↗
PubMed1999

Experimental analysis of recently transposed insertion sequences in the cyanobacterium Synechocystis sp. PCC 6803.

The genome DNA of the cyanobacterium Synechocystis sp. PCC 6803 carries a number of insertion sequences (Kaneko, T. et al. 1996, DNA Res., 3, 109-136). We analyzed one of the abundant ISs (ISY203 group of IS4 family) in the common three substrains of Synechocystis and found that the four ISs with identical nucleotide sequences were present only in the "Kazusa" strain, whose complete genome sequence had been determined, while absent in ancestral strains (the original strain from Pasteur Culture Collection and its glucose-tolerant derivative). Three of these ISs were found in the genomic sequence as transposase genes of sll1474, sll1780 and slr1635. The fourth was on the plasmid, pSYSM. On the other hand, all three strains had a novel IS (denoted ISY203x), of which the nucleotide sequence was totally identical to the four ISs found only in the Kazusa strain. Since the flanking regions of ISY203x did not match any part of the genome or of the known plasmids of Synechocystis, it is presumably located on a yet uncharacterized plasmid. These suggest that the four ISs in Kazusa strain were recently transposed from ISY203x. Apparently, the transposition inactivated four preexisting genes, of which modified forms are presented as putative genes (sll1473, sll1475, slr1862, slr1863, slr1635 and ssl2982) in the list of the complete genome (CyanoBase: http://www.kazusa.or.jp/cyano/cyano.html). The possible effects of transposition of ISs in Synechocystis are discussed in relation to phenotypic mutations and microevolution.

Amino Acid Sequence↗
PubMed1999

Cloning of cellulose synthase genes from Acetobacter xylinum JCM 7664: implication of a novel set of cellulose synthase genes.

Three sets of cellulose synthase genes were cloned from a cellulose-producing bacterium Acetobacter xylinum JCM 7664. One set of genes (bcsAI/bcsBI/bcsCI/bcsDI) were highly conserved with the well-established type I genes in other strains of A. xylinum, while the other two (bcsABII-A, bcsABII-B) were homologous to the known type II (acsAII). Unexpectedly, they were immediately followed by a gene cluster of bcsX/bcsY/bcsCII/ORF569, likely forming an operon. Western blotting demonstrated that the BcsY protein accumulated in cells. Since BcsY showed striking similarities to a number of membrane-bound transacylases, it was hypothesized that the type II cellulose synthase produces acylated cellulose, which might be anchored on the cytoplasmic membrane. An insertion sequence of IS1380-type was found just upstream of the one type II gene (bcsABII-B), suggestive of nonfunctioning.

Amino Acid Sequence↗
PubMed1999

A patient who was found to be pregnant unexpectedly during hysteromyomectomy.

We present a case of an unexpected pregnancy and an ultimately successful obstetric outcome. The patient underwent abdominal myomectomy under spinal anaesthesia for a uterine leiomyoma with menorrhagia and infertility. Later, she was found to have been in the 7th gestational day at the time of surgery. The blastocyst survived the surgical manipulation and anaesthesia, resulting in a successful pregnancy. The literature on the endocrinological stress response during anaesthesia and surgery suggests that spinal anaesthesia administered in this case was potentially helpful in maintaining progesterone levels and avoiding increased prolactin levels; increased prolactin levels might be deleterious to implantation of the blastocyst.

Journal Article↗
PubMed1998

Oxygen-evolving diatom thylakoid membranes.

Two protocols were developed that yielded purified oxygen-evolving thylakoid membranes from the diatom Cylindrotheca fusiformis. One protocol employed sonication, while the second involved French press lysis of protoplasts formed by brief culture of cells in a cation-depleted medium. Regardless of the method of cell breakage, some damage to electron transport components occurred. For preservation of both light-dependent electron transport activity and in vivo fluorescence properties, 2 M sorbitol proved to be more effective than 1 M sorbitol, regardless of the method used for cell lysis. Thylakoids purified in 2 M sorbitol using the protoplast/French press method showed the best preservation of in vivo fluorescence emission signals and Photosystem II activity with ferricyanide was completely inhibited by DCMU. Thylakoids purified in 2 M sorbitol using sonication had higher rates of Photosystem II activity with ferricyanide, but this activity was less sensitive to DCMU. Whole-chain electron transport activity was low in all preparations. This is the first report of O2 evolution and of long-wavelength fluorescence in purified thylakoids of any chromophytic alga.

Diatoms↗
PubMed1998

A novel gene, pmgA, specifically regulates photosystem stoichiometry in the cyanobacterium Synechocystis species PCC 6803 in response to high light.

Previously, we identified a novel gene, pmgA, as an essential factor to support photomixotrophic growth of Synechocystis species PCC 6803 and reported that a strain in which pmgA was deleted grew better than the wild type under photoautotrophic conditions. To gain insight into the role of pmgA, we investigated the mutant phenotype of pmgA in detail. When low-light-grown (20 microE m(-2) s(-1)) cells were transferred to high light (HL [200 microE m(-2) s(-1)]), pmgA mutants failed to respond in the manner typically associated with Synechocystis. Specifically, mutants lost their ability to suppress accumulation of chlorophyll and photosystem I and, consequently, could not modulate photosystem stoichiometry. These phenotypes seem to result in enhanced rates of photosynthesis and growth during short-term exposure to HL. Moreover, mixed-culture experiments clearly demonstrated that loss of pmgA function was selected against during longer-term exposure to HL, suggesting that pmgA is involved in acquisition of resistance to HL stress. Finally, early induction of pmgA expression detected by reverse transcriptase-PCR upon the shift to HL led us to conclude that pmgA is the first gene identified, to our knowledge, as a specific regulatory factor for HL acclimation.

Base Sequence↗
PubMed1997

Analysis of the psbU gene encoding the 12-kDa extrinsic protein of photosystem II and studies on its role by deletion mutagenesis in Synechocystis sp. PCC 6803.

The gene encoding the 12-kDa extrinsic protein of photosystem II from Synechocystis sp. PCC 6803 was cloned based on N-terminal sequence of the mature protein. This gene, named psbU, encodes a polypeptide of 131 residues, the first 36 residues of which were absent in the mature protein and thus served as a transit peptide required for its transport into the thylakoid lumen. A psbU gene deletion mutant grew photoautotrophically in normal BG11 medium at almost the same rate as that of the wild type strain. This mutant, however, grew apparently slower than the wild type did upon depletion of Ca2+ or Cl- from the growth medium. Photosystem II oxygen evolution decreased to 81% in the mutant as compared with that in the wild type, and the thermoluminescence B- and Q-bands shifted to higher temperatures accompanied by an increase in the Q-band intensity. These results indicate that the 12-kDa protein is not essential for oxygen evolution but may play a role in optimizing the ion (Ca2+ and Cl-) environment and maintaining a functional structure of the cyanobacterial oxygen-evolving complex. In addition, a double deletion mutant lacking cytochrome c-550 and the 12-kDa protein grew photoautotrophically with a phenotype identical to that of the single deletion mutant of cytochrome c-550. This supports our previous biochemical results that the 12-kDa protein cannot bind to photosystem II in the absence of cytochrome c-550 (Shen, J.-R., and Inoue, Y. (1993) Biochemistry 32, 1825-1832).

Amino Acid Sequence↗
PubMed1997

Analysis of cancer mortality among atomic bomb survivors registered at Hiroshima University.

The aim of this study was to investigate the late effect on cancer mortality risk of the radiation exposure of atomic bomb survivors who comprised a study population different from that previously studied by the Radiation Effects Research Foundation (RERF). We examined survivors residing in Hiroshima Prefecture, who were followed up between 1968 and 1989 by the Research Institute for Radiation Biology and Medicine (RIRBM) at Hiroshima University. We used the dose-evaluation system known as Atomic Bomb Survivors 1993 Dose (ABS93D), which was based on the Dosimetry System 1986 for the survivors registered with RERF. The dose estimation was applied in a total of 35,123 subjects. Among survivors who had been alive for > 20 years after the bombing, the relative mortality risk of leukaemia at 1 Gy of organ dose was 2.37 (90% confidence interval: 1.36-3.39), which was significantly higher than the zero dose control group. Similarly, significantly higher risks were observed for all cancers except leukaemia, including cancers of the lung, colon and female breast. Comparison is made with RERF results regarding temporal changes in the relative risk. Although we observed slightly lower relative risks than RERF values for the cancer of the stomach and lung, and for all cancer except leukaemia, no marked trends for any cancer were observed in this study. Though there were some differences in population between RERF and RIRBM, no marked discrepancies were observed.

Adolescent↗
PubMed1997

Synthesis and biological evaluation of 7-hydroxy-3,4-diphenyl-1,2-dihydroisoquinolines as new 4-hydroxytamoxifen analogues.

A phenolic 3,4-diphenyl-1,2-dihydroisoquinoline derivative (4a) as a new 4-hydroxytamoxifen analogue and a related compound (4c) were synthesized from 3,4-diphenyl-1,2,3,4-tetrahydroisoquinolin-4-ols (5a, c), which were prepared by intramolecular Barbier reaction of N-(2-iodobenzyl)phenacylamines. Anti-proliferative activities of 4a,c and 5a,c, as well as 4b and 5b prepared previously, against human mammary carcinoma MCF-7 cell line and human nasopharyngeal carcinoma KB cell line were evaluated. The 3,4-diphenyl-1,2-dihydroisoquinoline derivatives (4a,c) and isoquinolin-4-ols (5a,b) were active against MCF-7 cells and were nearly equipotent to the corresponding nonphenolic compound (1a). The mechanism of the anti-proliferative activity of 4a-c against MCF-7 cells is discussed.

Animals↗
PubMed1995

Directed inactivation of the psbI gene does not affect photosystem II in the cyanobacterium Synechocystis sp. PCC 6803.

PsbI is a small, integral membrane protein component of photosystem II (PSII), a pigment-protein complex in cyanobacteria, algae and higher plants. To understand the function of this protein, we have isolated the psbI gene from the unicellular cyanobacterium Synechocystis sp. PCC 6803 and determined its nucleotide sequence. Using an antibiotic-resistance cartridge to disrupt and replace the psbI gene, we have created mutants of Synechocystis 6803 that lack the PsbI protein. Analysis of these mutants revealed that absence of the PsbI protein results in a 25-30% loss of PSII activity. However, other PSII polypeptides are present in near wild-type amounts, indicating that no significant destabilization of the PSII complex has occurred. These results contrast with recently reported data indicating that PsbI-deficient mutants of the eukaryotic alga Chlamydomonas reinhardtii are highly light-sensitive and have a significantly lower (80-90%) titer of the PSII complex. In Synechocystis 6803, PsbI-deficient cells appear to be slightly more photosensitive than wild-type cells, suggesting that this protein, while not essential for PSII biogenesis or function, plays a role in the optimization of PSII activity.

Amino Acid Sequence↗
PubMed1995

Specific degradation of the D1 protein of photosystem II by treatment with hydrogen peroxide in darkness: implications for the mechanism of degradation of the D1 protein under illumination.

The D1 protein of the photosystem II (PSII) reaction center has a rapid turnover and is specifically degraded under illumination in vivo. When isolated PSII membranes were treated in darkness with 10 mM hydrogen peroxide (H2O2), an active form of oxygen that is generated at the acceptor side of PSII under illumination, proteins of the PSII reaction center were specifically damaged in almost the same way as observed under illumination with strong light. The D1 protein and, to a lesser extent, the D2 protein were degraded to specific fragments, and cross-linked products (the covalently linked adduct of the D1 protein and the alpha subunit of cytochrome b559 and the heterodimer of the D1 and D2 proteins) were generated concomitantly. The site of cleavage of the D1 protein that gave rise to a major fragment of 22 kDa was located in the loop that connects membrane-spanning helixes IV and V. Treatment with H2O2 caused the same damage to proteins in isolated thylakoids and in core complexes that contained the non-heme iron at the acceptor side, but not in isolated reaction centers depleted of the iron. From these observations and the effects of reagents that are known to interact with the non-heme iron, it is suggested that the damage to proteins is caused by oxygen radicals generated by the non-heme iron in the Fe(II) state in a reaction with H2O2. It is proposed, moreover, that a similar mechanism is operative during the selective and specific degradation of the D1 protein under illumination.

Chloroplasts↗
PubMed1995

Synthesis and enantioselectivity of optically active 1- and 3-substituted 4-phenyl-1,2,3,4-tetrahydroisoquinolin-4-ols and related compounds as norepinephrine potentiators.

Optically active 1,2-dimethyl-4-phenyl-1,2,3,4-tetrahydroisoquinolin-4-ols (1R,4R-3a and 1S,4S-3b, 1S,4R-4a, and 1R,4S-4b) and 2-methyl-4-phenyl-1,2,3,4-tetrahydroisoquinolines (4S-5a and 4R-5b) were prepared in order to examine the effects of the 1-, 3-, and 4-substituents of 2-methyl-4-phenyl- 1,2,3,4-tetrahydroisoquinolin-4-ol (PI-OH) (1) on the enantioselectivity for norepinephrine (NE) potentiating activity. The conformations and absolute configurations of 3-5 were determined from their 1H-NMR and circular dichroism (CD) spectra and by single-crystal X-ray diffractometric analysis. The NE potentiating activity of the optically active 3-5 and previously prepared 3-methyl derivatives (3R,4R-6a and 3S,4S-6b) of PI-OH were tested. The results show that compounds 3, 4, and 6 had high enantioselectivity for NE potentiation: the 4R series of the enantiomers exhibited activity but not the 4S-enantiomers. The activity of the 4-desoxy compound 5 also resided exclusively in the 4S-enantiomer. These findings suggest the presence of a specific receptor for NE uptake, and the enantiomers 3a, 4a, 5a, and 6a may be antagonistic at this NE uptake receptor.

Adrenergic Uptake Inhibitors↗
PubMed1995

Synthesis and biological evaluation of 3,4-diphenyl-1,2-dihydroisoquinolines as a new tamoxifen analogue.

3,4-Diphenyl-1,2-dihydroisoquinoline derivatives (1) as a new tamoxifen analogue were synthesized with trifluoromethanesulfonic acid from 3,4-diphenyl-1,2,3,4-tetrahydroisoquinolin-4-ols (2), which were prepared by intramolecular Barbier reaction of N-(2-iodobenzyl)phenacylamines. Anti-proliferative activities of 1 and 2, and 3,4-diphenyl-1,2,3,4-tetrahydroisoquinolines (3) prepared by NaBH4 reduction of 1 against human mammary carcinoma MCF-7 cell line and human nasopharyngeal carcinoma KB cell line were evaluated. 1,2-Dihydroisoquinoline (1a) was the most active against MCF-7 cells in the compounds tested and the activity [IC50(micrograms/mL) 0.94] was nearly equipotent to that of tamoxifen. The structure-activity relationships of the compounds 1,2 and 3 were discussed.

Antineoplastic Agents↗
PubMed1994

Chemical crosslinking studies of extrinsic proteins in cyanobacterial photosystem II.

Chemical crosslinking with a zero-length crosslinker, 1-ethyl-3-(3-dimethylaminopropyl) carbodimide hydrochloride, was applied to a cyanobacterial photosystem II complex retaining three extrinsic proteins, the 33 kDa manganese-stabilizing protein, cytochrome (cyt) c-550 and the 12 kDa protein. Three major crosslinked products were obtained in addition to the crosslinked product between the extrinsic 33 kDa and the intrinsic CP47 proteins. They were identified to be: cyt c-550-12 kDa; cyt c-550-12 kDa-33 kDa; D2-cyt c-550-12 kDa. These results indicate that the three extrinsic proteins are closely located with each other in cyanobacterial PSII, supporting the previous proposal that, like the 33 kDa protein; cyt c-550 and the 12 kDa protein are associated with PSII at the lumenal side of thylakoids. The results also suggested that the D2 reaction center protein provides a direct binding site for the extrinsic cyt c-550.

Binding Sites↗
PubMed1994

Synthesis and pharmacological evaluation of phenolic 2-methyl-4-phenyl-1,2,3,4-tetrahydroisoquinolin-4-ols as a new norepinephrine potentiator.

2-Methyl-4-phenyl-1,2,3,4-tetrahydroisoquinoline-4-ol(PI-OH) (2a) and its derivatives form a new class of compounds possessing norepinephrine (NE) potentiating activity. As a new series of compounds, the isomeric 4-(4-hydroxyphenyl)- and 4-(3-hydroxyphenyl)-2-methyl-1,2,3,4- tetrahydroisoquinolin-4-ols (3a and 3b), and 4-(3,4-dihydroxyphenyl)-1,2,3,4-tetrahydroisoquinolin-4-ol (3c) were prepared and their NE potentiating activities were evaluated. The 4-(4-hydroxyphenyl) analogue (3a) had only moderate activity and the 4-(3-hydroxyphenyl) analogue (3b) possessed a slightly higher activity than PI-OH. The 4-(3,4-dihydroxyphenyl) analogue (3c) was the most active compound and the pD2 value was 7.71 +/- 0.06 (activity ratio; 26.9 fold) at a concentration of 3 x 10(-6) M. These results indicate the importance of dihydroxyphenylethanolamine moiety of 3c for the inhibition of NE uptake.

Animals↗
PubMed1994

[Two siblings with congenital adrenocortical unresponsiveness to ACTH showing peripheral neuropathy--morphometric evaluation of the sural nerve].

A 13-year-old boy, with the diagnosis of congenital adrenocortical unresponsiveness to ACTH (ACTH insensitivity) at age 7, developed a steppage gait, when under glucocorticoid replacement therapy at age 13. The parents were healthy and not consanguinous. On general physical examination, a mild diffuse skin hyperpigmentation was noted. Neurological examinations revealed that all the muscle stretch reflexes of both limbs were absent without pathologic reflexes. Pes cavus was found bilaterally. A slight decrease of tactile sensation was noted distal to the ankle joints. Pain sensation was slightly decreased in the toes. On laboratory examination, the conduction velocities of the left ulnar and median motor nerves were 51 and 45 m/sec, respectively, which are normal. No M-wave responses were obtained by electrical stimulation of the tibial and peroneal nerves. The coefficient of the variation of the R-R interval from ECG recordings was normal. Orthostatic hypotension was not observed. Achalasia was negative on the barium swallow esophagram. Therefore, it was concluded that he had motor and sensory polyneuropathy, and a right sural nerve biopsy was performed. A 12-year-old girl, a sister of the boy described above, with the diagnosis of ACTH insensitivity at age 5, noted a pain on the medial aspect of the left sole after skating. On general physical examination, a mild diffuse skin hyperpigmentation was discovered. On neurological examination, a spontaneous pain with dysesthesia was noted on the plantar aspect of the 1st, 2nd and 3rd left toes and on the anterior and medial aspect of the sole. Otherwise she was normal. A diagnosis of the left tarsal tunnel syndrome was made.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗