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Biomedical subjects

Y Tamai

Publications and source records attributed to Y Tamai.

At least 73 records · Page 4Linked to original sources
PubMed1998

Adsorption and enzyme (beta-galactosidase and alpha-chymotrypsin): immobilization properties of gel fiber prepared by the gel formation of cellulose acetate and titanium iso-propoxide

We prepared a new composite gel fiber by the gel formation of cellulose acetate and titanium iso-propoxide. The fiber is harder than alginate gel; it is also stable in common solvents, phosphate solution, and electrolyte solutions over a wide range of pH from 3 to 10. The fiber shows amphoretic adsorption properties depending on pH, namely, it acts anionic with decreasing pH and cationic with increasing pH. However, the fiber had no adsorption property for a pyrogen endotoxin. The beta-galactosidase and alpha-chymotrypsin not retained in alginate gel were immobilized on the fibers by this method. The pH, temperature, and repeated run stabilities of the immobilized enzyme were compared to those of the native one. Copyright 1998 John Wiley & Sons, Inc.

Journal Article↗
PubMed1998

Transcriptional co-regulation of Saccharomyces cerevisiae alcohol acetyltransferase gene, ATF1 and delta-9 fatty acid desaturase gene, OLE1 by unsaturated fatty acids.

The ATF1 gene encodes an alcohol acetyl transferase which catalyzes the synthesis of acetate esters from acetyl CoA and several kinds of alcohols. ATF1 expression is repressed by unsaturated fatty acids or oxygen. Analysis using ATF1-lacZ fusion plasmid revealed that ATF1 gene expression is widely repressed by a variety of unsaturated fatty acids, and the degree of ATF1 transcriptional repression varies according to the structure of the unsaturated fatty acids. Interestingly, it was noted that the degree of ATF1 transcriptional repression was related to the melting point of unsaturated fatty acids added to the medium. The OLE1 gene, which encodes delta-9 fatty acid desaturase, has been reported to be repressed by unsaturated fatty acids. Transcription of OLE1 was also repressed by a wide variety of unsaturated fatty acids under anaerobic conditions. The degree of transcriptional repression of OLE1 was also related to the melting point of the added unsaturated fatty acids. Therefore, it is considered that ATF1 and OLE1 transcription are regulated in response to cell membrane fluidity. As has been reported for OLE1, the repression of ATF1 by unsaturated fatty acids was relieved in a disruptant carrying a faa1 and faa4 double mutation, two fatty acid activation genes. However, the ATF1 transcript in this double gene disruptant was repressed by oxygen. These results suggested that ATF1 transcription was co-regulated by the same mechanism as the OLE1 gene and that unsaturated fatty acids and oxygen repressed the ATF1 transcript by a different regulation pathway.

Acetyltransferases↗
PubMed1998

Co-existence of two types of chromosome in the bottom fermenting yeast, Saccharomyces pastorianus.

The bottom fermenting yeasts in our collection were classified as Saccharomyces pastorianus on the basis of their DNA relatedness. The genomic organization of bottom fermenting yeast was analysed by Southern hybridization using eleven genes on chromosome IV, six genes on chromosome II and five genes on chromosome XV of S. cerevisiae as probes. Gene probes constructed from S. cerevisiae chromosomes II and IV hybridized strongly to the 820-kb chromosome and the 1500-kb chromosome of the bottom fermenting yeast, respectively. Five gene probes constructed from segments of chromosome XV hybridized strongly to the 1050-kb and the 1000-kb chromosomes. These chromosomes are thought to be S. cerevisiae-type chromosomes. In addition, these probes also hybridized weakly to the 1100-kb, 1350-kb, 850-kb and 700-kb chromosome. Gene probes constructed from segments including the left arm to TRP1 of chromosome IV and the right arm of chromosome II hybridized to the 1100-kb chromosomes of S. pastorianus. Gene probes constructed using the right arm of chromosome IV and the left arm of chromosome II hybridized to the 1350-kb chromosome of S. pastorianus. These results suggested that the 1100-kb and 1350-kb chromosomes were generated by reciprocal translocation between chromosome II and IV in S. pastorianus. Three gene probes constructed using the right arm of chromosome XV hybridized weakly to the 850-kb chromosome, and two gene probes from the left arm hybridized weakly to the 700-kb chromosome. These results suggested that chromosome XV of S. cerevisiae was rearranged into the 850-kb and 700-kb chromosomes in S. pastorianus. These weak hybridization patterns were identical to those obtained with S. bayanus. Therefore, two types of chromosome co-exist independently in bottom fermenting yeast: one set which originated from S. bayanus and another set from S. cerevisiae. This result supports the hypothesis that S. pastorianus is a hybrid of S. cerevisiae and S. bayanus.

Chimera↗
PubMed1998

Three-dimensional structure of a glycosphingolipid having a novel carbohydrate linkage, Galbeta1-4(Fucalpha1-3)Glcbeta1-3Galbeta, determined by theoretical calculations.

The novel glycosphingolipid, SEGLx (Galbeta1-4(Fucalpha1-3)Glcbeta1-3GalbetaCer), which was identified by us (Kawakami Y, et al. (1993) J Biochem 114: 677-83), shows a characteristic spectrum on 1H-NMR analysis, in which the anomeric proton resonances of a reducing end galactose and a glucose are split. To elucidate the structural characteristics of SEGLx, we determined its three-dimensional (3D) structure by means of computer simulation, involving such techniques as molecular mechanics (MM2), the semiempirical molecular orbital method (AM1), molecular dynamics (Amber), and computer 3D modelling. With the hypothesis that all OH group(s) of a ceramide participate in intramolecular hydrogen bonds, two kinds of stable conformers, horizontal and right-angled ones, were formed, depending on the ceramide species. The present findings suggest that the chemical species of both the long chain base and fatty acid moieties, mainly the occurrence of OH group(s), affect the chemical shifts of the anomeric proton resonances not only of the reducing terminal galactose but also the penultimate glucose through the formation of intramolecular hydrogen bonds. Computer simulation through theoretical calculation and 3D modelling was shown to be the best means of confirming the results obtained by experimental analysis.

Algorithms↗
PubMed1998

Combination chemotherapy in a patient with severe multiple systemic autoimmune disease.

We describe the occurrence of autoimmune haemolytic anaemia (AIHA) in a patient who had had both idiopathic thrombocytopenic purpura (ITP) and bullous pemphigoid (BP) for about 10 years. All of these diseases worsened rapidly, and the patient's clinical condition became critical after an episode of acute pneumonia. His AIHA, ITP and BP were responsive to combination chemotherapy consisting of cyclophosphamide, vincristine and prednisolone (CVP therapy).

Anemia, Hemolytic, Autoimmune↗
PubMed1998

Phospholipid deacylating activities included in yeast.

Yeast had been known to contain only one kind of phospholipid deacylating enzyme with an optimal pH in the acidic range. However, among 8 genera and 25 strains, 7 genera and 13 strains had phospholipid deacylating activity at pH 8.0, when screening of enzyme activity was done with micellar and liposomal substrates. The enzymatic properties of phospholipid deacylating enzyme existing in yeast was not related to genetic identity based on 18S rRNA gene sequence. The results suggest that yeast contains enzymes showing a variety of properties depending on the species of yeast, and further studies on this enzyme with more varieties of yeasts are necessary for understanding the physiological roles of the enzyme in yeast.

Fatty Acids, Nonesterified↗
PubMed1998

Hemiacetal dehydrogenation activity of alcohol dehydrogenases in Saccharomyces cerevisiae.

Some methylotrophic yeasts produce methyl formate from methanol and formaldehyde via hemiacetal formation. We investigated Saccharomyces cerevisiae to find whether this yeast has a carboxylate ester producing pathway that proceeds via hemiacetal dehydrogenation. We confirmed that the purified alcohol dehydrogenase (Adh) protein from S. cerevisiae can catalyze the production of esters. High specific activities were observed toward the hemiacetals corresponding to the primary alcohols when ether groups were substituted for methylene groups, resulting in the formation of formate esters. Both ADH and methyl formate synthesizing activities were sharply reduced in the delta adh1 delta adh2 mutant. The ADH1 and ADH2 genes encode the major Adh proteins in S. cerevisiae. Thus, it was concluded that the S. cerevisiae Adh protein catalyzes activities for the production of certain carboxylate esters.

Acetals↗
PubMed1998

Sustained improvement in anemia with low-dose recombinant human erythropoietin therapy in a patient with hypoplastic myelodysplastic syndrome and chromosomal abnormalities.

We present a case report of a 55-year-old male patient with hypoplastic myelodysplastic syndrome (MDS, refractory anemia) in which a good response to recombinant human erythropoietin (rhEPO) has been maintained for more than 60 months. There is with no evidence of progression to high risk MDS or acute leukemia, although he was predicted to be a low-responder to rhEPO therapy because of very high serum EPO levels (5,260 mU/ml), a history of multiple transfusions, chromosomal abnormalities (47,XY,+8) and severe thrombocytopenia. Since he received rhEPO with no adverse effects, it may be valuable to try rhEPO treatment at least one time for low-risk MDS patients, depending on red cell transfusion requirements.

Anemia, Refractory↗
PubMed1998

[Change in intraocular pressure after intraocular lens implant during a follow-up period of over 10 years].

Changes in intraocular pressure were studied in 141 eyes following intraocular lens implant. The average observational time was twelve years. We tried to fix both loops of the implant in the ciliary sulcus. The intraocular pressure increased over the ten year interval at 0.19 mmHg per year. Twenty-seven of the 141 eyes developed glaucoma. We studied the intraocular pressure of the cases with or without complications. Thirty-eight eyes had complications, fifteen eyes (39%) developed secondary glaucoma, and three eyes (8%) developed glaucomatous visual field defect. In twenty-three cases without secondary glaucoma, the intraocular pressure increased over a three-year interval after surgery and remained constant thereafter. 103 eyes had no complications to influence the intraocular pressure, twelve eyes (12%) developed secondary glaucoma, and four eyes (4%) developed glaucomatous visual field defect. In 91 cases without secondary glaucoma, the intraocular pressure increased over a five-year interval after surgery at 0.28 mmHg per year and remained constant thereafter. We recommend regular examination, especially during the initial five-year period when the intraocular pressure is apt to increase even if complications are not evident.

Adult↗
PubMed1998

Development and practical use of the new quantitative bleeding time test apparatus.

We have developed a new computerized system for measurement of quantitative bleeding time (QBT) to detect subtle abnormalities of primary hemostasis that are difficult to detect with the standard bleeding time determination. This new apparatus can simultaneously measure the bleeding time (BT; sec), amount of total blood loss (Tv; microl), maximum bleeding rate (Rmax; microl/sec) and bleeding pattern from the bleeding time incision. We have also developed a new holder for the Simplate that enables more consistent incisions and thus improves the reproducibility of the BT test. In this study, the newly developed QBT test was performed in 137 normal healthy volunteers and 10 patients having defined abnormalities of either primary or secondary hemostasis. Comparisons of the standard BT test and our QBT were made in 5 normal subjects and 7 thrombocytopenic patients. Additionally, 6 normal subjects were examined with both tests before and after administration of aspirin. Those results show that our QBT appears to be a more sensitive indicator of primary hemostasis than the standard BT method.

Adolescent↗
PubMed1997

A protein kinase Cdelta-binding protein SRBC whose expression is induced by serum starvation.

West-Western screening of a cDNA expression library using 32P-labeled, autophosphorylated protein kinase Cdelta (PKCdelta) as a probe, led us to identify cDNA clones encoding a PKCdelta-binding protein that contains a leucine zipper-like motif in its N-terminal region and two PEST sequences in its C-terminal region. This protein shows overall sequence similarity (43.3%) to the serum deprivation response (sdr) gene product, and we named it SRBC (sdr-related gene product that binds to c-kinase). PKCdelta binds to the C-terminal half of SRBC through the regulatory domain and phosphorylates it in vitro. In COS1 cells, the phosphorylation of over-expressed SRBC is stimulated by 12-O-tetradecanoylphorbol-13-acetate and further enhanced by the over-expression of PKCdelta. The mRNA for SRBC is detected in a wide variety of cultured cell lines and tissues and is strongly induced by serum starvation. Furthermore, SRBC mRNA is induced during retinoic acid-induced differentiation of P19 cells. These results suggest that SRBC serves as a substrate and/or receptor for PKC and might be involved in the control of cell growth mediated by PKC.

3T3 Cells↗
PubMed1997

Strategy for identification of sequence variants in COL7A1 and a novel 2-bp deletion mutation in recessive dystrophic epidermolysis bullosa.

The diagnostic hallmark of the dystrophic forms of epidermolysis bullosa (DEB), a group of heritable blistering skin diseases, is abnormalities in the anchoring fibrils at the dermal-epidermal basement membrane zone. Since type VII collagen is the major, if not the exclusive, component of the anchoring fibrils, the corresponding gene (COL7A1) is the candidate gene in DEB. Recent cloning of the type VII collagen cDNA and elucidation of the exon-intron organization of the gene have provided the basis for us to develop a novel strategy for identification of sequence variants in COL7A1. Optimization of 72 balanced primer pairs corresponding to flanking intronic sequences allowed PCR amplification of all 118 exons directly from genomic DNA. The PCR products were examined by heteroduplex analysis followed by comparative nucleotide sequencing. More than 100 sequence variants have been identified thus far in COL7A1 using this method, some of which are single base pair polymorphisms and many of which are pathogenetic mutations contributing to the blistering phenotype in DEB. The comprehensive method described is useful for rapid, reliable, and sensitive detection of sequence variants in COL7A1. We demonstrate the utility of this novel strategy in mutation detection and prenatal exclusion of RDEB in a consanguineous family at risk for recurrence.

Collagen↗
PubMed1997

Aspirin effects on colonic mucosal bleeding: implications for colonic biopsy and polypectomy.

BACKGROUND: Many patients who require endoscopic treatments such as biopsy and polypectomy are given antiplatelet agents reluctantly. We have studied the effects of aspirin on colonic mucosal hemostasis. METHODS AND PATIENTS: We developed a new endoscopic device to make a standard incision (7-mm length) on the colonic mucosa to study colon bleeding time. We measured the colon bleeding time of normal colonic mucosa in 47 cases. The colon bleeding time and skin bleeding time (Simplate method) were measured before and one hour after aspirin ingestion (990 mg) in ten healthy subjects. RESULTS: The bleeding time of normal colonic mucosa was 156 +/- 71 (mean +/- standard deviation) seconds. Significant prolongation was noted in both skin bleeding time (357 +/- 192 vs. 477 +/- 183 seconds; P < 0.05) and colon bleeding time (155 +/- 47 vs. 244 +/- 169 seconds; P < 0.05) after aspirin ingestion. CONCLUSIONS: Bleeding time was measured safely under direct colonoscopic visualization. Aspirin prolonged the colon bleeding time. Therefore, endoscopists should be aware of a risk of abnormal bleeding after endoscopic biopsy and polypectomy in patients with aspirin use. Two days were necessary for colon bleeding time to become normalized in patients with aspirin use.

Aspirin↗
PubMed1997

A case of congenital intraspinal neuroblastoma.

A case of congenital intraspinal neuroblastoma with paraplegia in a newborn is described, and a review of previously reported cases is presented. Calcification within the spinal canal and abdominal mass was noted. At age 75 days, the patient underwent a resection of almost the entire retroperitonial tumor. A magnetic resonance scan showed hepatic metastasis, and chemotherapy was changed to a more intensive regimen. The liver metastasis disappeared; however, neurological signs persisted. A literature review of 38 cases showed 26 patients had a laminectomy and 12 patients did not. Treatment with or without laminectomy was associated with a poor prognosis for neurological recovery, suggesting cord compression must occur antenatally, and irreversible damage occurs before birth. Congenital intraspinal neuroblastoma has a relatively good prognosis (survival rate, 91.9%), although complete neurological recovery is highly unusual. Based on these findings, the authors conclude that a laminectomy is not indicated for those patients.

Calcinosis↗
PubMed1997

Gangliosides of dogfish (Squalus acanthias) brain.

Eighteen gangliosides were isolated from dogfish (Squalus acanthias) brain, and their structures and compositions were determined by methylation analysis, enzymatic hydrolysis and partial hydrolysis with mild acid. Tetra- and pentasialogangliosides were also analysed by liquid secondary ion mass spectrometry. The dogfish brain gangliosides were characterized by a variety of molecular species. The most abundant ganglioside was GM2 (22.8% of the total sialic acid content), followed by GQ1c (16.0%), GP1c (13.4%), and GD2 (12.5%). The abundance of gangliosides containing a gangliotriaose core (GM2 and GD2), and c-series polysialogangliosides (GQ1c and GP1c) was a prominent feature of dogfish brain, differing from the brain gangliosides of teleosts and other vertebrates. A battery of trisialogangliosides was also found. A ganglioside which had an a- and alpha-series hybrid-structure (IV3NeuAc,III6NeuAc,II3NeuAc-Gg4Cer) comprised 1.4% of the total. The major fatty acids comprised 16:0, 18:0, 18:1, 22:1 and 24:1. The gangliosides with a gangliotriaose core predominantly contained 22:1. Sphinganine and 4-sphingenine comprised the long-chain bases.

Animals↗
PubMed1997

Display technique using time-dependent scatter diagrams for the study of changing relative timings of three spike trains: evaluation of functional connectivity in a local area of the nervous system.

The relative timings of impulses caused by two neurons can be studied using cross-correlation techniques or the related techniques of the joint peristimulus-time histogram and the time-dependent correlation function. Analysis of the relative timings of several related neurons is important to the study of the dynamics, since we consider functional connectivity to be partially related to the dynamics. Functional connectivity changes of short duration reflect physiological functions rather than changes of synaptic connections. The relative timings of impulses are considered to reflect functional connectivity. Using the joint impulse configuration scatter diagram (JICSD) proposed by Perkel, a time-dependent scatter diagram (TDSD) is calculated to analyze the change of functional connectivity. The JICSD displays the long-time average of relative timings of impulses or the functional connectivity of three interconnected neurons. We generated JICSDs for short durations and we subsequently generated TDSDs by arranging JICSDs in chronological order. The change of a "snowflake pattern" of each JICSD was interpreted in terms of change of the functional connectivity. We propose a method for analyzing the changing functional connectivity among three neurons.

Action Potentials↗
PubMed1997

A comparative study of 2',3'-cyclic-nucleotide 3'-phosphodiesterase in vertebrates: cDNA cloning and amino acid sequences for chicken and bullfrog enzymes.

In mammalian brain, two 2',3'-cyclic-nucleotide 3'-phosphodiesterase (EC 3.1.4.37) isoforms, CNP1 and CNP2, are translated, respectively, from the two mRNAs, which have been transcribed and processed by alternative use of the two transcription start points and by differential splicing. In the present study, the cDNAs encoding chicken CNP2 and bullfrog CNP1, respectively, were isolated, and the amino acid sequences of chicken CNP2 and bullfrog CNP1 were deduced. Western blot analysis showed that chicken brain contains a major CNP2-type protein together with a minor unidentified isoform, and bullfrog brain contains only a CNP1-type protein. All available amino acid sequences of vertebrate 2',3'-cyclic-nucleotide 3'-phosphodiesterases were aligned and compared. Three conserved motif sequences were noted: (a) an ATP-binding site near the amino terminus, (b) an isoprenylation site at the carboxyl terminus, and (c) a probable catalytic site resembling the active site of beta-ketoacyl synthase (EC 2.3.1.41). The second and the third motifs are conserved also in goldfish RICH (regeneration-induced 2',3'-cyclic-nucleotide 3'-phosphodiesterase homologue), which has been shown recently to have 2',3'-cyclic-nucleotide 3'-phosphodiesterase activity. The third motif (probably catalytic site) was assigned for the first time in the present report.

2',3'-Cyclic Nucleotide 3'-Phosphodiesterase↗