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Biomedical subjects

H Kotani

Publications and source records attributed to H Kotani.

At least 73 records · Page 4Linked to original sources
PubMed1996

Sequence analysis of the genome of the unicellular cyanobacterium Synechocystis sp. strain PCC6803. II. Sequence determination of the entire genome and assignment of potential protein-coding regions.

The sequence determination of the entire genome of the Synechocystis sp. strain PCC6803 was completed. The total length of the genome finally confirmed was 3,573,470 bp, including the previously reported sequence of 1,003,450 bp from map position 64% to 92% of the genome. The entire sequence was assembled from the sequences of the physical map-based contigs of cosmid clones and of lambda clones and long PCR products which were used for gap-filling. The accuracy of the sequence was guaranteed by analysis of both strands of DNA through the entire genome. The authenticity of the assembled sequence was supported by restriction analysis of long PCR products, which were directly amplified from the genomic DNA using the assembled sequence data. To predict the potential protein-coding regions, analysis of open reading frames (ORFs), analysis by the GeneMark program and similarity search to databases were performed. As a result, a total of 3,168 potential protein genes were assigned on the genome, in which 145 (4.6%) were identical to reported genes and 1,257 (39.6%) and 340 (10.8%) showed similarity to reported and hypothetical genes, respectively. The remaining 1,426 (45.0%) had no apparent similarity to any genes in databases. Among the potential protein genes assigned, 128 were related to the genes participating in photosynthetic reactions. The sum of the sequences coding for potential protein genes occupies 87% of the genome length. By adding rRNA and tRNA genes, therefore, the genome has a very compact arrangement of protein- and RNA-coding regions. A notable feature on the gene organization of the genome was that 99 ORFs, which showed similarity to transposase genes and could be classified into 6 groups, were found spread all over the genome, and at least 26 of them appeared to remain intact. The result implies that rearrangement of the genome occurred frequently during and after establishment of this species.

Bacterial Proteins↗
PubMed1996

Phosphorylation of Munc-18/n-Sec1/rbSec1 by protein kinase C: its implication in regulating the interaction of Munc-18/n-Sec1/rbSec1 with syntaxin.

Munc-18/n-Sec1/rbSec1 interacts with syntaxin and this interaction inhibits the association of vesicle-associated membrane protein (VAMP)/synaptobrevin and synaptosomal-associated protein of 25 kDa (SNAP-25) with syntaxin. Syntaxin, VAMP, and SNAP-25 serve as soluble N-ethylmaleimide-sensitive fusion protein attachment protein (SNAP) receptors essential for docking and/or fusion of synaptic vesicles with the presynaptic plasma membrane. Genetic analyses in yeast, Caenorhabditis elegans, and Drosophila suggest that Munc-18 is essential for vesicle transport. On the other hand, protein kinase C (PKC) stimulates Ca2+-dependent exocytosis in various types of secretory cells. However, the modes of action of Munc-18 and PKC in vesicle transport have not been clarified. Here, we show that recombinant Munc-18 is phosphorylated by conventional PKC in a Ca2+- and phospholipid-dependent manner in a cell-free system. About 1 mol of phosphate is maximally incorporated into 1 mol of Munc-18. The major phosphorylation sites are Ser306 and Ser313. The Munc-18 complexed with syntaxin is not phosphorylated. The PKC-catalyzed phosphorylation of Munc-18 inhibits its interaction with syntaxin. These results suggest that the PKC-catalyzed phosphorylation of Munc-18 plays an important role in regulating the interaction of Munc-18 with syntaxin and thereby the docking and/or the fusion of synaptic vesicles with the presynaptic plasma membrane.

Amino Acid Sequence↗
PubMed1996

RNA facilitates RecA-mediated DNA pairing and strand transfer between molecules bearing limited regions of homology.

The RecA protein of Escherichia coli catalyzes homologous pairing and strand exchange between a wide range of molecules showing nucleotide sequence complementarity, including a linear duplex and a single-stranded DNA molecule. We demonstrate that RecA can promote formation of joint molecules when the duplex contains an RNA/DNA hairpin and a single-stranded circle serves as the pairing partner. A chimeric RNA/DNA hairpin can be used to form stable joint molecules with as little as 15 bases of shared homology as long as the RNA stretch contains complementarity to the circle. The joint molecule bears some resemblance to a triple helical structure composed of RNA residues surrounded by two DNA strands which are in a parallel orientation. Evidence is presented that supports the notion that short stretches of RNA can be used in homologous pairing reactions at lengths below that required for DNA-DNA heteroduplex formation.

Bacteriophage M13↗
PubMed1996

Effect of low-power laser irradiation on impulse conduction in anesthetized rabbits.

Low-power laser analgesic effect was generally accepted in clinical cases, whereas there was no direct evidence to indicate that low-power laser irradiation suppressed an impulse conduction within a peripheral nerve. The effect of low-power laser irradiation on electrically evoked responses within the sural nerve was electrophysiologically analyzed in anesthetized rabbits. High threshold evoked responses (conduction velocity was about 11 m/sec, unmyelinated A delta), which were induced by an electrical stimulation to the peripheral stump of the nerve, were significantly suppressed (9 to 19% inhibition) during low-power laser irradiation, which applied to the exposed sural nerve between the stimulus site and the recording site. The suppressive effect was reversible and recovered to the control level after the irradiation. Experimental evidence indicated that low-power laser irradiation suppressed the impulse conduction of unmyelinated A delta afferents in peripheral sensory nerve, which caused a pain sensation. Our data suggest that low-power laser acts as a reversible direct suppressor of neuronal activity.

Animals↗
PubMed1996

Effect of low-power laser irradiation on procollagen synthesis in human fibroblasts.

The conflicting views of the effect of low-power laser (LPL) irradiation on procollagen synthesis have existed at the present time, whereas many clinical studies have tested usefulness of LPL irradiation for the wound healing. To evaluate the effect of LPL irradiation on the procollagen synthesis of human fibroblasts in vitro, LPL irradiation on human fibroblast was carried out using two different culture medium, serum-starved medium and fetal calf serum (FCS)-contained medium. In addition, to investigate the mechanism of the LPL on the procollagen synthesis of human fibroblasts, dexamethasone and methylene blue contained medium were used for inhibition of procollagen product at the pretranslational level and cGMP-mediated processes, respectively. Enhanced effect of LPL was consistently observed in the serum-starved medium (50% increase by a 3 min irradiation), not in the FCS-contained medium. The LPL enhanced effect was not blocked by dexamethasone (3% inhibition) but methylene blue (40% inhibition). Our data suggest that some factors in FCS might interfere with the enhanced effect of LPL on procollagen synthesis and the LPL might act as a direct stimulator of the procollagen synthesis. It seems probable that the LPL enhanced effects might be occurred at the translational level or at the pretranslational level, which is not affected by dexamethasone and cGMP, might be involved in the LPL enhanced effect of the procollagen synthesis in fibroblast.

Cells, Cultured↗
PubMed1996

Retroviral transduction of CD34-enriched hematopoietic progenitor cells under serum-free conditions.

The use of defined or serum-free culture conditions during retroviral transduction of hematopoietic cells would be desirable for standardization and safety reasons, as well as potentially allowing greater expansion of progenitor cells. Retroviral vector supernatants were concentrated and purified via tangential flow filtration polyethylene glycol (PEG)-precipitation, and ultracentrifugation, allowing serum-free transductions at standard multiplicities of infection (moi). Protein content of transductions using these concentrated vectors was 5-6 logs lower than in standard transductions. Transduction efficiencies of these concentrated vector preparations added back to serum-free or serum-containing media were equivalent to standard retroviral supernatant transductions of CD34-enriched progenitors. Absolute progenitor (CFU-C) numbers at the end of transduction were higher in serum-free + concentrated virus transductions, as opposed to transductions in standard vector supernatants containing fetal calf serum.

Antigens, CD34↗
PubMed1995

Sequence analysis of the genome of the unicellular cyanobacterium Synechocystis sp. strain PCC6803. I. Sequence features in the 1 Mb region from map positions 64% to 92% of the genome.

The contiguous sequence of 1,003,450 bp spanning map positions 64% to 92% of the genome of Synechocystis sp. strain PCC6803 has been deduced. Computer analysis of the sequence predicts that this region contains at least 818 potential ORFs, in which 255 (31%) were either genes that had already been identified or their homologues, 84 (10%) were homologues to registered hypothetical genes, and 149 (18%) showed weak similarities to reported genes. The remaining 330 ORFs showed no apparent similarity to any reported genes or carried no significant protein motifs. The potential ORFs as a whole occupied 86% of the sequenced region, implying compact arrangement of genes in the genome. As to the structural RNA genes, one rRNA operon consisting of 5,028 bp and at least 11 species of tRNA genes were identified. It is noteworthy that 10 out of the 11 tRNA species showed significant sequence similarities to tRNAs reported in plant chloroplasts. As other notable unique sequences, three classes of IS-like elements each with characteristics typical of IS elements were identified, and a typical unit of WD(Trp-Asp)-repeats which have only been detected in the regulatory proteins of eukaryotes was identified within the large 5,079-bp ORF located at map position 69%.

Base Sequence↗
PubMed1995

Assignment of 82 known genes and gene clusters on the genome of the unicellular cyanobacterium Synechocystis sp. strain PCC6803.

We have previously constructed the physical map of a cyanobacterium, Synechoystis sp. strain PCC6803 on the basis of restriction and linking clone analysis. Since a total of 82 genes and gene clusters have been isolated from this strain, most of which are involved in oxygenic photosynthesis, portions of their sequences were amplified by the PCR method and assigned on the physical map of the genome by hybridization with restriction fragments, ordered clones, which were obtained from cosmid and lambda libraries, and long PCR-products. An exception was the gene psbG2 which was mapped on an extra-chromosomal unit of 45 kb. Since genetic maps of some of genes assigned above, especially those for photosynthesis, have been reported for two other cyanobacterial strains, Anabaena sp. PCC7120 and Synechococcus sp. PCC7002, gene organizations were compared among the three strains. However, no significant correlation was observed, suggesting that rearrangement of genes occurred in the respective strains during or after establishment of the species.

Bacteriophage lambda↗
PubMed1995

Electron-microscopic and immunohistochemical studies of Langerhans cells and Thy-1-positive cells in mouse tongue epithelium subjected to local hyperthermia.

Local hyperthermia via skin has been used to treat cancer but may suppress local immune responses as a side-effect. To examine effects of heat on immunologically responsive cells in oral mucosa, mouse tongues were heated by an implant system at 43 degrees C for 20 min. The densities of Langerhans cells and Thy-1-positive cells rapidly increased within 3 h after the treatment, then returned to a normal level after 7 days. Electron microscopy confirmed that Langerhans cells in the tongue epithelium formed clusters with lymphocytic cells, suggesting an active response to the hyperthermia.

Adenosine Triphosphatases↗
PubMed1995

Posterior interosseous nerve paralysis with multiple constrictions.

We report four cases of posterior interosseous nerve paralysis with multiple constrictions. At surgery the constrictions were found between the arcade of Frohse and a point of bifurcation of the supinator motor branch. External neurolysis with epineurotomy using the microscope was performed in all cases, and full recovery was obtained.

Adult↗
PubMed1995

Prediction of the coding sequences of unidentified human genes. III. The coding sequences of 40 new genes (KIAA0081-KIAA0120) deduced by analysis of cDNA clones from human cell line KG-1.

We isolated full-length cDNA clones from size-fractionated cDNA libraries of human immature myeloid cell line KG-1, and the coding sequences of 40 genes were newly predicted. A computer search of the GenBank/EMBL databases indicated that the sequences of 14 genes were unrelated to any reported genes, while the remaining 26 genes carried some sequences with similarities to known genes. Significant transmembrane domains were identified in 17 genes, and protein motifs that matched those in the PROSITE motif database were identified in 11 genes. Northern hybridization analysis with 18 different cells and tissues demonstrated that 10 genes were apparently expressed in a cell-specific or tissue-specific manner. Among the genes predicted, half were isolated from the medium-sized cDNA library and the other half from the small-sized cDNA library, and their average sizes were 4 kb and 1.4 kb, respectively. As judged by Northern hybridization profiles, small-sized cDNAs appeared to be expressed more ubiquitously and abundantly in various tissues, compared with that of medium-sized cDNAs.

Cell Line↗
PubMed1995

Effects of occlusal splints on the asymmetry of masticatory muscle activity during maximal clenching.

The effects of stabilization splints on the electromyographic activity patterns of the masseter and anterior temporal muscles during maximal clenching in healthy subjects and subjects with different types of stomatognathic dysfunction syndrome were investigated. No marked effect of splints on the asymmetry of muscle activity during bilateral clenching was revealed immediately after splint insertion. During unilateral clenching in the intercuspal position (ICP), the relative asymmetry index (rAI) of the masseter muscles, detecting the imbalance of left and right muscular activity, was significantly increased. The use of splints suppressed the asymmetry of masseter muscle activity during unilateral clenching. This result suggests that the use of a splint is a method of suppressing clench-caused aggravation of stomatognathic dysfunction in the presence of an imbalance between left and right muscle activities.

Adult↗
PubMed1995

Asymmetry of masticatory muscle activity during intercuspal maximal clenching in healthy subjects and subjects with stomatognathic dysfunction syndrome.

The present study investigated the asymmetry of masticatory muscle activity during maximal intercuspal clenching in healthy subjects and subjects with stomatognathic dysfunction syndrome. Stomatognathic dysfunction syndrome, unilateral mastication and the asymmetry of masticatory muscle activity appear to be related to each other. The asymmetry of masseter muscle activity was greater as stomatognathic dysfunction became increasingly severe. Because fatigue and pain are produced more quickly by unilateral clenching than bilateral clenching, clenching under conditions of left and right muscular imbalance can further aggravate stomatognathic dysfunction. It is suggested the asymmetry of masseter muscle activity during maximal clenching correlates with the onset of the stomatognathic dysfunction syndrome. Stomatognathic dysfunction syndrome is closely related to the asymmetry of masseter muscle activity and only slightly related to the asymmetry of temporal muscle activity. The asymmetry of anterior temporal muscle activity appears to have little clinical significance.

Adolescent↗
PubMed1994

[Recurrent dislocation of the elbow].

A case of a recurrent dislocation of the elbow joint in a 13-year-old female is described. The patient sustained a medial epicondylar fracture of the humerus and consulted us four months later. There was no deformity but marked lateral instability of the elbow was recognized. It could be fully flexed and hyperextended ca 20 degrees. The elbow joint could be easily dislocated by pronation of the hyperextended elbow. Roentgenogram demonstrated an apparent non-union of the medial epicondylar fracture. The fragment was repositioned so that the medial collateral ligament became taut. There was no recurrence of the dislocation ten months postoperatively.

Adolescent↗
PubMed1994

Genetic recombination of nucleosomal templates is mediated by transcription.

An in vitro system has been developed to examine the influence of transcription on genetic rearrangement. Using a homologous pairing assay, the transfer of one strand of a nucleosomal template onto a recipient DNA molecule was monitored as a function of RNA polymerase activity. Transcriptionally inactive nucleosomal DNA was refractory to homologous pairing. Homologous pairing was catalyzed, however, by the eukaryotic recombinase, rec1, when the nucleosomal template was being transcribed. The reaction was found to be dependent on the presence of rec1, RNA polymerase, NTPs and RNA synthesis. Heteroduplex formation between a short DNA duplex fragment assembled into a nucleosome and a single-stranded circle relied also on the presence of sequence homology between the duplex and the circle. The results of this study lend support to the notion that transcriptionally active regions within a chromosome are more apt to serve as sites of genetic recombination.

Cell-Free System↗