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Biomedical subjects

Y Tamai

Publications and source records attributed to Y Tamai.

At least 91 records · Page 5Linked to original sources
PubMed1997

Genomic organization and alternative splicing of human PACE4 (SPC4), kexin-like processing endoprotease.

PACE4 (paired basic amino acid cleaving enzyme) is a member of a family of the mammalian kexin-like proprotein convertases containing a subtilisin-like catalytic domain. Previously we reported seven isoform mRNAs of PACE4 that vary in size and 3'-coding sequence [A. Tsuji et al. (1994) Biochem. Biophys. Res. Commun. 200, 943-950; K. Mori et al. (1997) J. Biochem. 121, 941-948]. To determine the origin of these isoforms, the entire human PACE4 gene has been isolated as a set of overlapping genomic DNA fragments, and analyzed by restriction enzyme digestion and nucleotide sequence determination. The human PACE4 gene spans at least 250 kb and is distributed over 25 exons that range in size from 39 to 1,422 base pairs. Human PACE4 gene is the largest kexin-like proprotein convertase gene reported to date. The most striking feature of its genomic structure is the size of the introns and the number of exons, although the general organization of signal peptide, propeptide, and catalytic domains, which are conserved in this family, is very similar to that reported for other kexin-like protease genes. The structural analysis of PACE4 genomic DNA indicates that multiple PACE4 transcripts are produced as a consequence of alternative RNA splicing events, including exon skipping, and differences in the usage of the inner 5'-splicing donor and polyadenylation sites. A major transcriptional start site was detected 314 bp upstream from the ATG translational start site by primer extension analysis. Sequence analysis of the 5'-flanking region revealed that PACE4 gene lacks TATA and CCAAT boxes in the proximal upstream region of the start site, although potential binding sites for several transcription factors including SP1, AP1, AP2, PEA3, Ets-1, GHF (growth hormone factor)-1, CREB (cyclic AMP response element binding protein), and basic helix-loop-helix proteins, were present. An unusual sequence of six tandem repeats of a nonadecamer (GGCCTGGGGGTTCACCTGC) containing an E box is found in the 5'-flanking region. These results suggest that PACE4 is not a constitutive gene product and its expression is regulated by various transcription factors.

Alternative Splicing↗
PubMed1997

Effect of aeration and unsaturated fatty acids on expression of the Saccharomyces cerevisiae alcohol acetyltransferase gene.

The reduction of acetate ester synthesis by aeration and the addition of unsaturated fatty acids to the medium has been reported to be the result of the reduction in alcohol acetyltransferase (AATase) activity induced by inhibition of this enzyme. However, regulation of the AATase gene ATF1 has not been reported. In this study, ATF1 gene expression was studied by Northern analysis, and the results showed that the ATF1 gene was repressed both by aeration and by unsaturated fatty acids. The results also showed that the reduction of AATase activity is closely related to the degree of repression of ATF1 mRNA, which suggested that the gene repression is the primary means of reducing AATase activity in vivo. Using the Escherichia coli lacZ gene as a reporter gene, it was shown that a 150-bp fragment of the 5' flanking sequence played a major role in the repression by aeration and unsaturated fatty acid addition.

Acetyltransferases↗
PubMed1997

[Hematological characteristics of hypoplastic MDS patients with chromosomal abnormalities, who had been followed for aplastic anemia with normal karyotypes].

During 1990 to 1993, five patients who had been treated in our hospital for aplastic anemia (AA) with a normal karyotype, were found to have hypoplastic myelodysplastic syndromes (hMDS); three patients with RA, one RAEB, and one RAEB-T, and all of them have chromosomal abnormalities. The mean age of the hMDS patients (4 men, 1 woman) was 51.0 years (range 31-61). We retrospectively studied the hematological features of the 5 cases in the early stage without chromosomal abnormalities. They showed, 1) appearance of erythroblasts (3/5), 2) more reticulocyte counts than typical AA (mean 7.8 x 10(4)/microliter), 3) macrocytic anemia (mean MCV 106fl) in peripheral blood, 4) relative erythroid hyperplasia (M/E ratio 0.2-1.5), and 5) low lymphocyte counts (mean percentage of lymphocytes 32, 8%) in bone marrow. Considering about the differences or transformation between AA and hMDS, it is interesting that all five patients have initially had a normal karyotype and subsequently developed chromosomal abnormalities.

Adult↗
PubMed1996

Disruption of phospholipase B gene, PLB1, increases the survival of baker's yeast Torulaspora delbrueckii.

An uracil auxotrophic mutant of baker's yeast Torulaspora delbrueckii, which is resistant to 5-fluoro-orotic acid, was complemented by transformation with YEp24 which harbors 2 microns origin and URA3 derived from Saccharomyces cerevisiae. The phospholipase B in T. delbrueckii cells is active in both acidic and alkaline conditions. However, activity of phospholipase B gene (PLB1) in cells of disruption mutant (plb1:: URA3) was lost in both conditions, which indicates that all phospholipase B activity is encoded by a single gene (or a single polypeptide) in these yeast cells. Over-expression of PLB1 with YEp plasmid vector in T. delbrueckii cells showed approximately 2.5-fold increase in phospholipase B activity, comparing with that in wild-type cells. Cells of plb1 delta mutant showed increased survival when cells of plb1 delta mutant and wild-type strain were incubated in water at 30 degrees C. Cells of PLB1-over-expressed strain died rapidly even during the cultivation period, indicating that phospholipase B activity may be a determinant for the survival of this yeast.

Bread↗
PubMed1996

Multiple integration of input and output in the cortex.

We inserted microelectrodes in eye movement-evoking cortices (EMECs) of cats and examined whether neurones in the EMECs received sensory input from guide signals and fired prior to saccades. The five EMECs were the medial wall of the hemisphere under the cruciate sulcus, the medical and lateral bank of the presylvian sulcus, the fundus of the coronal sulcus and ventral bank of the anterior ectosylvian sulcus. Neurones in all EMECs responded to input guide signals and discharged prior to the saccades. The neurones, however, did not always respond to all saccades, but responded cooperatively or alternatively among the EMECs. These results suggest that input information is projected to a broad area of the cortex and is integrated with output signals in the same cortex to which the input information was projected.

Animals↗
PubMed1996

A novel fucosyltetrahexosylceramide in plerocercoids of the parasite Spirometra erinacei.

This glycosphingolipid was tentatively designated as GalSEGLx, in which the carbohydrate structure is characterized by an additional galactose molecule attached to the reducing-end galactose of SEGLx [Gal beta-4 (Fuc alpha-3) Glc beta-3 Gal beta Cer], which was previously determined by us [Kawakami, Y., Nakamura, K., Kojima, H., Suzuki, M., Inagaki, F., Suzuki, A., Sonoki, S., Uchida, A., Murata, Y. & Tamai, Y. (1993) J. Biochem. 114, 677-683], through a beta 1-6 linkage. The ceramide contained sphinganine and 4D-hydroxysphinganine in an about equimolar ratio, and a non-hydroxy fatty acid with carbon atoms ranging from 16 to 28, 26:0, 28:0 and 28:1 being major components. Based on the finding that a novel carbohydrate structure. Gal beta-4 Glc beta-3 Gal, was commonly found in glycosphingolipids from the parasite, S. erinacei, we here propose the terms, spirometo series, for this core structure series, and spirometosides, for glycosphingolipids having this carbohydrate structure.

Animals↗
PubMed1996

Mapping of the genes encoding mouse prostaglandin D, E, and F and prostacyclin receptors.

Prostaglandins and prostacyclin are metabolites of arachidonic acid and exert a variety of actions to maintain local homeostasis in the body. Their actions are mediated by cell surface receptors specific to the respective ligands. Using a panel of interspecific back-cross mice, we have mapped the prostaglandin D receptor gene (Ptgdr), prostaglandin E receptor subtype EP(1) gene (Ptgerepl), prostaglandin F receptor gene (Ptgfr), and prostacyclin receptor gene (Ptgir). Ptgdr mapped to proximal Chr 14, Ptgfr mapped to distal Chr 3, Ptgerepl mapped to middle Chr 8, and Ptgir mapped to proximal Chr 7.

Animals↗
PubMed1996

Nucleotide sequences of alcohol acetyltransferase genes from lager brewing yeast, Saccharomyces carlsbergensis.

The nucleotide sequences of alcohol acetyltransferase genes isolated from lager brewing yeast, Saccharomyces carlsbergensis have been determined. S. carlsbergensis has one ATF1 gene and another homologous gene, the Lg-ATF1 gene. There was a high degree of homology between the amino acid sequences deduced for the ATF1 protein and the Lg-ATF1 protein (75.7%), but the N-terminal region has a relatively low degree of homology. Southern analysis and contour-clamped homogeneous electric field analysis of Saccharomyces strains suggest that the ATF1 gene is located on chromosome XV in S. cerevisiae and that the Lg-ATF1 gene might originate from the "non-S. cerevisiae' genome of S. carlsbergensis, which is similar to that of S. bayanus and S. pastorianus.

Acetyltransferases↗
PubMed1996

Ganglioside alterations in the central and peripheral nervous systems of patients with Creutzfeldt-Jakob disease.

We have examined the distribution and composition of gangliosides in central and peripheral nervous tissues from two patients with Creutzfeldt-Jakob disease (CJD). There were marked decreases in total ganglioside levels in CJD, with reductions in the cerebral cortex and cerebellum in the order of 20-30% and 50% of control values, respectively, though in spinal cord and sciatic nerve total gangliosides were not significantly altered. The percentage distribution of individual gangliosides was characterized by marked increases in GD3 and GD2, contrasting with severe decreases in GD1a, GD1b, GT1b and GQ1b; such changes were found throughout the patients' nervous tissues. An abnormal long-chain base composition was detected with the d20:1 component being decreased to less than 50% of control values, in the cerebrum, cerebellum and spinal cord. Changes in gangliosides occurred even in those tissues not severely affected neuropathologically. These ganglioside abnormalities are discussed in relationship to the pathogenesis of CJD.

Aged↗
PubMed1996

Biosynthesis of a blood group H1 antigen by alpha 1, 2-fucosyltransferase in PC12 cells.

We have examined the expression of GDP-fucose: glycosphingolipid fucosyltransferase activity in PC12 cells and PC12 sublines in relation to the neuronal differentiation induced by nerve growth factor (NGF) or dexamethasone. Transfer of fucose to paragloboside (nLc4Cer) yielded a product which was determined to be a blood group H1 antigen (Fuc alpha 1-2Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc-Cer) by gas chromatography/mass spectrometry analysis and enzymatic hydrolysis, suggesting that PC12 cells have an alpha 1,2-fucosyltransferase. Lactosylceramide was also fucosylated at a reduced rate. When the differentiation of PC12 cells and PC12 subline cells, PC12D and MR31, was induced by exposure to either NGF or dexamethasone, the fucosyltransferase activity for nLc4Cer was found to decrease in both cell lines, suggesting the association with cell differentiation. This is the first report of the presence of an alpha 1,2-fucosyltransferase in cultured neuronal cell lines which catalyses the in vitro biosynthesis from nLc4Cer of a type-2 chain glycosphingolipid having the blood group H1 determinant. The disaccharides, beta-lactose and N-acetyllactosamine, were also fucosylated by PC12 cell enzyme, although the specificity for the carbohydrate structure was different from that for glycosphingolipids.

ABO Blood-Group System↗
PubMed1996

Association of anti-GM2 antibodies in Guillain-Barré syndrome with acute cytomegalovirus infection.

We examined serum anti-cytomegalovirus (CMV) and anti-ganglioside antibodies by ELISA in 51 patients with Guillain-Barré syndrome (GBS), and titers were compared with those from 47 normal and 74 disease controls. Three GBS patients with IgM anti-CMV antibodies had high titers of IgM and IgG anti-GM2 antibodies. The other GBS patients without IgM anti-CMV antibodies, and the normal and disease controls except one of 6 non-GBS patients with acute CMV infections had no anti-GM2 antibodies. The titers of anti-GM2 antibodies decreased on absorption with CMV-infected cells. These findings suggest that anti-GM2 antibodies are associated with acute CMV infections in GBS patients.

Adult↗
PubMed1996

A proposed reorganization of the cortical input-output system.

This paper proposes a new concept for interpretation of the cerebral cortex. In this schema, the cortex is an 'imaging system' which plays an integral part in the 'functional circuit' of the living body. This functional circuit is made up of five components: the 'imaging system' of the cortex, the 'image forming system' of the basal ganglia, thalamus and cerebellum, the 'image-acting system' of the brainstem and spinal cord, the 'sensory system' of the sense organs and the 'external words.' An image constructed in the cortex yields a purposeful movement by way of its outputs through the image-acting system. The image to drive the purposeful movement is formed and accumulated in the cortex by trial and error under the control of the image-forming system. In the proposed organization outlined here, the cortex can be divided into two components, both of which have their own input and output for forming and realizing the image. One is comprised of specific areas for analyzing proper sensations from the sense organs through a specific area of the thalamus (e.g., retinal to lateral geniculate to primary visual cortex). The other system is composed of non-specific areas analyzing more diffuse input from various sensory organs through non-specific areas of the thalamus. These two systems work in concert to form fundamental and detailed images for purposeful movements through tight intercortical connections. Whereas the outputs from non-specific areas yield common behaviors regardless of sensory modality, outputs from the specific areas controls movements related to a specific sensation. Thus, it is proposed that these two systems work cooperatively: the former constructs the image and causes the initial movements, and the latter controls the movements to realize the image from the changing information of transient conditions. This model differs from other models of cortical organization which segregate cortex on the basis of sensory-related input regions and motor-related output regions. Existing data is consistent with the proposed organizational scheme. Although it may be difficult to prove specific aspects of this new model. I believe that the hypotheses contained within it will serve as an important foundation for driving future research.

Afferent Pathways↗
PubMed1996

Sensory response properties of cortical neurons in the anterior ectosylvian sulcus of cats: intracellular recording and labeling.

Visual and auditory sensory responses of cortical neurons in the caudal half of the anterior ectosylvian sulcus (AES) of cats were examined under alpha-chloralose anesthesia, using intracellular recording and labeling techniques. Stable intracellular recordings were obtained from 155 neurons, and 141 neurons exhibited responses to sensory stimuli. Of 141 sensory neurons, 74 (52%) were bimodal neurons that responded to both visual and auditory stimuli, and 67 (48%) were unimodal showing sensory responses only to visual (25) or auditory stimulation (42). Forty-five neurons (35 pyramidal neurons, 5 non-pyramidal neurons, 5 not classified) responsive to sensory stimuli were labeled with biocytin. The percentage of bimodal neurons of the biocytin-labeled neurons was 40% (4/10) in layer II, 50% (10/20) in layer III-IV, 70% (7/10) in layer V and 60% (3/5) in layer VI. Thus the convergence of visual and auditory inputs on single neurons was most intense in layer V. Auditory response latencies were in a narrow range from 10 to 40 ms, whereas visual response latencies were in a wide range from 15 to 100 ms. Late visual responses (> 60 ms) were more commonly elicited in biomodal neurons than in visual unimodal neurons. Visual responses in layer II were all elicited over 40 ms, whereas early visual responses within 40 ms were observed in the other cortical layers. A subgroup of neurons (22/141) had a propensity to exhibit a burst discharge, a train of three to seven action potentials on a depolarizing envelope in response to sensory stimuli. Their specific distribution in cortical tissue was suggested by the result that six out of nine biocytin-labeled neurons (seven pyramidal neurons, two non-pyramidal neurons) showing burst discharges to sensory stimuli were observed in layer V. These results are considered to signify some aspects of intracortical organization related to the cross-modal integration of sensory inputs.

Animals↗
PubMed1996

Purification and some properties of phospholipase B from Schizosaccharomyces pombe.

Phospholipase B from Schizosaccharomyces pombe was purified by ammonium sulfate fractionation and chromatographed on phenyl-Sepharose CL-4B, DEAE-Toyopearl 650M, and TSK gel G4000SW columns. The purified enzyme was a glycoprotein with molecular weight of approximately 300,000 and 100,000-150,000 by gel filtration and SDS-polyacrylamide gel electrophoresis, respectively. The isoelectric point was pH 4.7. The optimum pH of the enzyme was 2.5 and no activity was detected at neutral and alkaline pHs. The enzyme was not heat-stable. Enzyme activity was slightly stimulated by divalent ions except Fe2+ and 0.1% sodium deoxycholate, and inhibited by Fe2+, Fe3+, 0.1% sodium dodecyl sulfate, and 0.01% cetyltrimethylammonium bromide. The enzyme hydrolyzed mono- and diacylphospholipids, and phosphatidylinositol was hydrolyzed most preferentially. Triglyceride was not hydrolyzed. The enzyme also had acyltransferase activity on lysophosphatidylcholine, forming the corresponding diacylphosphatidylcholine.

Acyltransferases↗
PubMed1996

Enzymes in intestinal juice from patients with liver diseases and colon polyps: measurement of bilirubin, alkaline phosphatase, aspartate aminotransferase and lactate dehydrogenase.

Since the amounts of hepatogenous enzymes discharged into the intestinal tract remain unknown, this study was initiated to evaluate the amounts of the enzymes in the intestinal tract. Whole gut lavage fluid (polyethyleneglycol electrolyte solution) was administered orally to 42 subjects, consisting of 5 patients with hepatoma, 10 with chronic hepatitis, 10 with colon polyps, and 17 control subjects without liver disease. Two hr after the large intestinal lavage, the digestive tract juice was aspirated by colonoscopy, and the bilirubin (Bil), alkaline phosphatase (ALP), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) in the aspirates were measured. A positive correlation between the AST and LDH values was found, and a significant difference in these values between the hepatic disorders and the normal controls was noticed. A significant positive correlation between the ALP and Bil values was found, and a statistical difference in these values between the group of colon polyps and the controls and other groups was observed. This lavage fluid technique enables to estimate the amounts of hepatic enzymes discharged into the intestinal tract, thereby opening a new avenue for future enzyme research.

Adult↗
PubMed1996

Epinephrine or peplomycin combined with hyperthermia in irradiated Lewis lung carcinoma: effects on tumor growth, skin reaction, and lung metastasis.

Although hyperthermia potentiates the effect of radiation, the combined effect decreases as the time between irradiation and hyperthermia increases. The purpose of this study was to prevent the rapid loss of efficacy by the local injection of epinephrine or peplomycin(PEP), two agents known as hyperthermic potentiators. In this study, Lewis lung carcinoma implanted in the foot of BDF1 mice was used for the assessment of tumor growth, skin reactions, and lung metastasis. The tumors were irradiated, then warmed in a water bath for 45 min. The retarding effects of hyperthermia on tumor growth and skin reactions were lost 2 days after irradiation. However, when PEP or epinephrine was injected before hyperthermia, tumor growth was distinctly delayed. The effect of epinephrine was greater than PEP and still showed enhancement 8 days after irradiation. For skin reactions, no significant enhancing effect was observed. Lung metastasis was significantly inhibited by the addition of epinephrine either 0 or 2 days after irradiation. In conclusion, the local administration of epinephrine combined with hyperthermia significantly retarded tumor growth without an increase in skin reactions or lung metastases. Possible mechanism underlying this phenomenon was discussed.

Animals↗