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Biomedical subjects

H Urabe

Publications and source records attributed to H Urabe.

At least 37 records · Page 2Linked to original sources
PubMed1998

Adherent bacteria cells in five dental materials: sonication effect.

Adherent bacterial cells on the surfaces of two dental porcelain ceramics, three composite resins and human enamel were examined using four types of bacteria strains. Their adherent cells were counted on saliva-coated and uncoated material surfaces after sonication, and contact angle and zeta potential were measured for each adherent cell tested. A correlation between contact angle and bacterial cells on an uncoated surface was found to be higher in two Streptococcus sanguis cells than in S. mutans Ingbritt and S. sobrinus OMZ 176, whereas there appeared to be a higher correlation between S. mutans Ingbritt or S. sobrinus OMZ 176 and zeta potential on the uncoated surface. On the saliva-coated surface, a significantly high correlation was found between the adherent cells, with the exception of S. sanguis ATCC 10 557, and the zeta potential. Contact angle and zeta potential values were small when the surfaces of the materials were coated with saliva, as compared with those on the uncoated surface. The sonication condition (120 s) of adherent cells on the surface of the material significantly depended on the types of bacteria cells, showing that S. mutans Ingbritt (>50-60%) had a greater removal percentage than the others (<50%).

Journal Article↗
PubMed1995

Cloning, sequencing and expression of serine/threonine kinase-encoding genes from Streptomyces coelicolor A3(2).

A 6.3-kb DNA fragment encoding two eukaryotic-type serine/threonine protein kinases (Ser/Thr PK) was cloned from Streptomyces coelicolor A3(2) by using a PCR product obtained with primers based on highly conserved regions of eukaryotic Ser/Thr PK. The nucleotide (nt) sequence of the essential 4.4-kb fragment contained two possible ORFs. One ORF (PkaA) contained 543 amino acids (aa), while another (PkaB) consisted of 417 aa. The N-terminal half of both proteins showed significant similarity with the catalytic domain of eukaryotic Ser/Thr PK. On the other hand, the C-terminal region of PkaA, but not of PkaB, is rich in Pro and Gln residues, indicating that PkaA works as a PK as well as a transcription factor. The pkaB gene was overexpressed in Escherichia coli, and the gene product (PkaB) was found to be phosphorylated mainly at Thr. The pkaA gene was also overexpressed in E. coli, and the gene product (PkaA) was found to be phosphorylated mainly at Thr and slightly at Ser. In the case of PkaA, at least 100 aa residues from the C terminus were not essential for the PK activity. When the PCR product was used as a probe, it hybridized to DNA fragments from all the Streptomyces species tested, indicating that these types of Ser/Thr PK are distributed ubiquitously and play significant physiological roles in the various species of Streptomyces.

Amino Acid Sequence↗
PubMed1995

Cloning, sequencing, and site-directed mutagenesis of beta-lactamase gene from Streptomyces fradiae Y59.

The beta-lactamase gene from Streptomyces fradiae Y59 was cloned and sequenced. To determine which amino acid residues are critical in binding activity to blue dextran, chimera beta-lactamases were constructed and their binding abilities were determined. The results suggested that blue dextran binding may depend more on overall conformation of about two-thirds of the beta-lactamase molecule from the N terminus than on the primary structure.

Amino Acid Sequence↗
PubMed1995

Properties of peptide chain release factor 2 from Streptomyces coelicolor A3(2): conserved primary structure but no frameshift regulation.

A gene was cloned from Streptomyces coelicolor A3(2). It encodes a protein of 368 amino acid residues with a high degree of similarity to prokaryotic release factor 2. However, it has neither an internal stop codon nor the Shine-Dalgarno-like sequence immediately upstream of the assumed frameshift position. The gene is expressed and functional in Escherichia coli as peptide chain release factor 2. The transcription start site is at or adjacent to the translational start site. The size of the mRNA detected by hybridization suggests that the gene (prfB) is monocistronic in S. coelicolor A3(2). However, about 80 bp upstream of the gene there is an operon which is composed of two genes encoding eukaryotic-type serine/threonine kinases.

Amino Acid Sequence↗
PubMed1994

Reversible crystal transition of guanosine between the dihydrate and anhydrous states coupled with adsorption-desorption process.

Relative humidity induces the reversible crystal transition of guanosine between the dihydrate and the anhydrous state. The characteristics of the transition was investigated by means of X-ray powder diffraction analysis and high-resolution solid-state 13C NMR spectroscopy. Adsorption-desorption hysteresis was observed. Guanosine dihydrate (the H-state) which is crystallized from an aqueous solution rapidly loses crystal water below 10% relative humidity (rh), and is anhydrous at 0% rh (the A-state). The crystals gradually recover the H-state at approximate 20% rh. In the adsorption process between 10-20% rh, there exists one intermediate state, M, with 1.2-1.3 moles water per mole guanosine. The lattice of the M-state was determined to be orthorhombic with the cell parameters of a = 16.248(1), b = 11.603(1), and c = 13.643(2) A. The base-stacking structure is retained throughout the transition. On the other hand, conformational changes of the riboses and break of the hydrogen-bonding network between the bases would be induced in the A-state in conformity with lack of crystal water.

Adsorption↗
PubMed1993

Cloning, nucleotide sequence and expression of a beta-lactamase gene from Streptomyces lavendulae.

A hybridized DNA fragment was cloned as a 7.6-kb fragment from Streptomyces lavendulae KCCS0263 using a 1.9-kb SacI-XbaI DNA fragment from S. cellulosae as a probe. The latter fragment encoded a beta-lactamase which can bind blue dextran. The hybridized region was reduced to a 2.8-kb KpnI-BclI fragment and the nucleotide sequence was determined. The nucleotide sequence indicated one open reading frame whose amino acid sequence is very similar to that of the beta-lactamase from S. cellulosae. The gene produced beta-lactamase enzyme at a low but significant amount.

Amino Acid Sequence↗
PubMed1993

Cloning, sequence and expression of the argG gene from Streptomyces lavendulae.

The argG gene, encoding argininosuccinate synthetase, was cloned from Streptomyces lavendulae KCCS0055 by colony hybridization using the argG-carrying 2.1-kb fragment of S. coelicolor DNA as a probe. The restriction map of the cloned DNA fragment was very similar to that of S. coelicolor. This DNA fragment could complement the argG mutation of both S. lividans 1326 I10 and Escherichia coli K-12 JE5694, suggesting that the fragment contained a promoter for both E. coli and S. lividans. The subcloning experiment using E. coli K-12 JE5694 as a host has indicated that the essential region for argG is contained in the 2.5-kb DNA fragment. The translational product was identified as a 56-kDa kDa protein in minicells and by conventional gel electrophoresis. Determination of the nucleotide (nt) sequence of the 2.5-kb DNA fragment revealed one open reading frame of 1449 bp. The amino acid (aa) sequence analysis showed that the N-terminus was Ser, and 9 aa from the N terminus were completely identical with those deduced from the nt sequence. Nuclease S1 mapping indicated that the transcription start point is located near the start codon.

Amino Acid Sequence↗
PubMed1992

Nucleotide sequence and transcriptional analysis of activator-regulator proteins for beta-lactamase in Streptomyces cacaoi.

The nucleotide sequence of the 2.7-kb DNA fragment upstream of the structural gene of beta-lactamase in Streptomyces cacaoi was determined. Computer-aided "FRAME" analysis revealed four possible open reading frames (ORFs), three in one direction and one in the opposite direction. One of them (ORF1, BlaA) encoded an activator-regulator protein whose deduced amino acid sequence was similar to that of other activator-regulator proteins in bacteria. Insertion of an 8-bp BamHI linker into the BlaA region decreased the beta-lactamase activity sharply, from 50 U to 1 U/ml. This protein (BlaA) was found to bind to the nucleotide sequence between the bla (beta-lactamase structural gene) and blaA genes. Another ORF (ORF2, BlaB) in the same orientation had a couple of amino acid sequences similar to that of pBR322 beta-lactamase. However, insertion of the 8-bp BamHI linker indicated that this ORF was functional as an activator-regulator but not as a beta-lactamase. Therefore, there were two activator-regulator proteins in the upstream region of the structural gene of the beta-lactamase. Nuclease S1 mapping predicted that transcription for the activator proteins commenced at the translational initiation codon or within a few nucleotides from the translational start site. Transcription was in the opposite direction to that of the beta-lactamase structural gene.

Amino Acid Sequence↗
PubMed1992

Malignant Triton tumor. A case with protean histopathological patterns.

A case of malignant Triton tumor occurring in the leg of a 48-year-old woman with neurofibromatosis (von Recklinghausen's disease) is presented. The neoplasm was composed mainly of spindle-shaped cells forming interlacing fascicles with areas of massive necrosis. The important feature in this neoplasm was the presence of rhabdomyoblastic cells admixed with other cellular components. In addition, variable histologic features including solid, myxomatous, hemangiomatous, hemangiopericytomatous, epithelioid, and lymphomatous areas were identified. This variety has been recognized in malignant schwannomas, but not in malignant Triton tumors. There were discrete foci with each predominant histologic feature shown in a map of the neoplasm in which the distribution of those components is demonstrated based on the histology and immunohistochemistry. Satisfactory biopsy specimens are necessary for accurate diagnosis of malignant Triton tumor.

Actins↗
PubMed1990

A new apparatus for hair regrowth in male-pattern baldness.

A newly devised apparatus (Scalp-Tension-Relaxer, STR) can efficiently promote hair regrowth in patients with male-pattern baldness. When this apparatus is applied, the scalp is pushed up to relieve tension on the vertex. The efficacy rate of hair regrowth in alopecia patients was 40%. An investigation into the basis for the hair regrowth caused by this apparatus was directed toward the changes in hemodynamics and skin temperature of the scalp. During and after use of this apparatus, subjects exhibited an increase both in the cutaneous blood flow rate (as determined by laser Doppler flowmetry) and in the cutaneous temperature (as determined by thermography).

Adult↗
PubMed1990

Beta-lactamase expression in Streptomyces cacaoi.

Plasmids were prepared by inserting genomic DNA fragments from Streptomyces cacaoi within the mel gene of plasmid pIJ702. The inserted DNA fragments contain the beta-lactamase-encoding bla gene and upstream nucleotide sequences of various lengths. The transcription start point of bla was identified by nuclease S1 mapping. Upstream nucleotide sequences of sufficient lengths had an enhancing effect on beta-lactamase production by the Streptomyces host. The dot blot hybridization assay revealed that this effect was exerted at the transcriptional level. Experimental evidence strongly suggests that the underlying mechanism involves, at least in part, one or several trans-acting elements. In one of the constructs, in which the upstream nucleotide sequence was reduced to 0.3 kb, the bla promoter was present but the bla gene was expressed by readthrough from a promoter, possibly the mel promoter, of the pIJ702 vector.

Amino Acid Sequence↗
PubMed1990

Cloning from Streptomyces cellulosae of the gene encoding beta-lactamase, a blue-dextran binding protein.

A beta-lactamase gene was cloned from Streptomyces cellulosae as a 2.3-kb DNA fragment using Streptomyces lividans 1326 and PIJ385 as a host-vector system. During the course of cloning, a part of the chromosomal DNA fragment cloned together with a part of the vector plasmid were deleted, indicating instability of this contiguous DNA region. The enzyme from the clone showed similar properties with respect to binding of blue dextran and isoelectric point to the enzyme from S. cellulosae. The cloned gene hybridized not only to DNA of S. cellulosae, the source of DNA, but also to DNAs of several Streptomyces species, irrespective of their formation of beta-lactamase. These results suggest that this gene may have homology to genes other than the one for beta-lactamase.

Blotting, Southern↗
PubMed1989

Orientation of retinal in purple membrane determined by polarized Raman spectroscopy.

The orientation of the retinal molecule in the purple membrane was determined by polarized Raman spectroscopy for stacked purple membranes. The depolarization ratios of C = C stretching vibration mode were measured for three scattering geometries of purple membrane films. From the depolarization ratios we estimated the tilt angle of the transition dipole moment of retinal to the membrane normal and the rotational angle of the molecular plane along the transition dipole moment of retinal. The molecular plane of M intermediate was found to be almost perpendicular to the membrane plane. We confirmed that the tilt angle was 65 +/- 2 degrees for both bR and M intermediates.

Bacteriorhodopsins↗
PubMed1988

Analysis of photo-initiators in visible-light-cured dental composite resins.

Seven commercial visible-light-cured (VL) dental composite resins were analytically studied for identification of the photo-initiator consisting of photo-sensitizer and reducing agent. Gas-liquid chromatography (GC) was used for the determination of the dilute components extracted from the composite resin. Mass spectroscopy (GC-MS) was used for confirmation of the qualitative data obtained by GC. The results showed that all composite resins examined included camphorquinone (CQ) as a photo-sensitizer. The concentration of CQ in the resin phase, however, ranged from 0.17 to 1.03% w/w. The composite resin with hybrid-sized filler tended to have a higher concentration of CQ than did the micro-filled composite resin. As for the reducing agent, two out of seven brands contained dimethylaminoethyl methacrylate (DMAEMA), and one included dimethyl-p-toluidine (DMPTI). The mixing ratio between CQ and the amine in these three composite resins also varied. Another four brands did not contain either DMAEMA or DMPTI, and would utilize different reducing agents.

Chromatography, Gas↗