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Biomedical subjects

S Fujiwara

Publications and source records attributed to S Fujiwara.

At least 127 records · Page 7Linked to original sources
PubMed1999

[A case of surgical treatment for thymic Hodgkin's disease with tracheo-bronchial stenosis].

An 18-year-old female was introduced our hospital for facial swelling and subcutaneous tumor of anterior neck. Chest X-ray and CT films showed mediastinal mass with tracheo-bronchial stenosis. Incisional biopsy specimens of neck tumor revealed that the tumor was suggestive of malignant lymphoma. Because of progressive dyspnea after CHOP regimens the operation was performed and histopathological examinations revealed thymic Hodgkin's disease. After operation dyspnea was improved but dysphagia and hoarseness occurred. These symptoms were getting improved. She received 6 cycles of ABVD regimens and discharged after 5 months.

Adolescent↗
PubMed1999

[Two adult siblings with Chédiak-Higashi syndrome presenting as hyperpigmentation of the skin and the iris].

We report two adult siblings with Chédiak-Higashi syndrome presenting as hyperpigmentation of the skin and the iris. Patient 1 was a 30-year-old man who had generalized hyperpigmentation from one month of age, developed mental deterioration at age 9 years, and gait difficulty at age 20 years. On admission, he showed hyperpigmentation of the skin and the iris without partial albinism. Skin pigmentation was predominated at the face and the extremities. Neurologic examinations revealed mental dysfunction with IQ of 60 by WAIS, cerebellar ataxia, pyramidal signs, extrapyramidal signs, and polyneuropathy. Hematologic examination revealed peroxidase-positive giant granules in leukocytes and decreased activity of natural killer cells, leading to the diagnosis of Chédiak-Higashi syndrome. Patient 2, a younger brother of patient 1, was a 28 year-old man who also had hyperpigmentation of the skin and the iris with similar neurologic findings with patient 1. Both had no episodes of systemic infections. In Japanese cases of Chédiak-Higashi syndrome, more than 50% of them showed hyperpigmentation of the skin from the early stage of the disease. We pointed out that hyperpigmentation of the skin may be a good diagnostic help of Chédiak-Higashi syndrome in Japanese cases.

Adult↗
PubMed1999

[An autopsied case of subacute progressive dementia with flactuated disturbance of consciousness, myoclonus and periodic synchronous discharges on EEGs].

We present an autopsied case which developed progressive dementia at the age of 45. EEGs showed periodic synchronous discharges (PSD) when he showed fluctuated cloudy consciousness with myoclonus. Cerebrospinal fluid examination showed mild to moderate increase in protein and monocytes for duration of illness, but antivirotics and antibiotics were not effective. He was not apallic even at the terminal stage when computed tomography (CT) revealed marked cerebral atrophy, and died of pneumonia 27 months after onset. He was clinically diagnosed as having Creutzfeldt-Jakob disease (CJD) because of subacute progressive dementia, myoclonus and PSD. Neuropathological examination revealed marked brain atrophy with severe neuronal loss and gliosis in the cerebral cortex and subcortical nuclei, although no spongiform degeneration was found. Senile plaques, neurofibrillaly tangles, argyrophilic glial inclusions and glial nodules were not detected. Prion protein immunoreactivity was negative. Therefore, this case can not be neuropathologically diagnosed as having CJD, Alzheimer's disease, non-Alzheimer-type degenerative dementias or any encephalitis. This case might have suffered from an unknown new disease.

Brain↗
PubMed1999

Fatty acid imaging with 123I-15-(p-iodophenyl)-9-R,S-methylpentadecanoic acid in acute coronary syndrome.

UNLABELLED: 123I-15-(p-iodophenyl)-9-R,S-methylpentadecanoic acid (9-MPA) has recently been developed as a tracer for myocardial fatty acid uptake. The aim of this study, which was performed as part of a phase III clinical trial of 9-MPA, was to test the usefulness of 9-MPA for the assessment of myocardial viability in patients with acute coronary syndrome (ACS). METHODS: Fifteen patients with ACS who had undergone direct percutaneous transluminal coronary angioplasty were examined. Myocardial SPECT with 9-MPA and 99mTc-sestamibi and low-dose dobutamine echocardiography were performed within 2 wk after onset. The 9-MPA images were obtained 10 and 60 min after tracer administration, and sestamibi imaging was begun 60 min after the injection. The left ventricle was divided into 9 segments, and 9-MPA and sestamibi uptake were scored from 0 (normal) to 3 (no activity) in each segment. Lower uptake of 9-MPA than of sestamibi was defined as a mismatch. Myocardial segments showing improvement in wall motion during low-dose dobutamine infusion (5-10 microg/kg/ min) were considered viable. RESULTS: The 9-MPA images were of high quality for all patients. Myocardial uptake of 9-MPA was lower in ischemic myocardium than in nonischemic myocardium (58.2%+/-14.2% versus 91.9%+/-6.5%, P<0.0001). Clearance of 9-MPA from ischemic myocardium was slower than that from nonischemic myocardium (10.2%+/-11.7% versus 19.1%+/-5.9%, P<0.01). A mismatch was seen in 10 of 15 patients, and 18 of 20 (90%) mismatched segments were defined as viable by dobutamine echocardiography. Conversely, 18 of 20 (90%) matched segments did not show any improvement in function during dobutamine stimulation (P<0.0001). Uptake of 9-MPA in nonviable segments was lower than that in dysfunctional but viable segments (P<0.05), and 9-MPA clearance from nonviable segments was slower than that from viable segments (P<0.05). CONCLUSION: The imaging characteristics of 9-MPA for SPECT are excellent, allowing noninvasive assessment of myocardial fatty acid uptake. Myocardial imaging with 9-MPA may reveal impaired fatty acid uptake in dysfunctional but viable myocardium and thus provide useful information for clinical decision making in ACS.

Aged↗
PubMed1998

Suppressor of hairless activates brachyury expression in the Ciona embryo.

The Ciona Brachyury gene (Ci-Bra) is regulated, in part, by a 434-bp enhancer that mediates restricted expression in the notochord. Here we present evidence that a Ciona Suppressor of Hairless ¿Ci-Su(H)¿ protein functions as an activator of this enhancer. Point mutations that reduce the binding of a GST/Ci-Su(H) fusion protein in vitro diminish the expression of mutagenized Ci-Bra/lacZ transgenes in electroporated embryos. Overexpression of a Ci-Su(H) fusion protein containing the Drosophila Hairy repression domain interferes with notochord differentiation, producing mutant tadpoles with shortened tails. Expression of a constitutively activated Xotch receptor in the notochord, endoderm, and CNS also alters tail morphogenesis. These results suggest that a Notch-Su(H) pathway might participate in notochord differentiation in Ciona.

Amino Acid Sequence↗
PubMed1998

Crystallization and preliminary X-ray crystallographic analysis of archaeal O6-methylguanine-DNA methyltransferase.

Crystals of archaeal O6-methylguanine-DNA methyltransferase (MGMT) from hyperthermophilic archaeon Pyrococcus kodakaraensis strain KOD1 have been grown at room temperature using polyethylene glycol as a precipitant. The diffraction pattern of the crystal extends to 2.0 A resolution at room temperature upon exposure to Cu Kalpha radiation. The crystal belongs to the space group P212121 with unit-cell dimensions of a = 52.8, b = 86.6 and c = 39.9 A. The presence of one molecule per asymmetric unit gives a crystal volume per protein mass (Vm) of 2.3 A3 Da-1 and a solvent content of 48% by volume. A full set of X-ray diffraction data was collected to 2.0 A Bragg spacings from the native crystal.

Bacterial Proteins↗
PubMed1998

Characterization of two intein homing endonucleases encoded in the DNA polymerase gene of Pyrococcus kodakaraensis strain KOD1.

Two intein endonucleases, denoted PI- Pko I and PI- Pko II, in the DNA polymerase gene of the hyperthermophilic archaeon Pyrococcus kodakaraensis KOD1 were expressed in Escherichia coli and the recombinant endonucleases were characterized. Both endonucleases were thermostable and cleaved their intein-less DNA sequences leaving four base 3'-hydroxyl overhangs. PI-Pko I exhibited 22 times higher specific activity than PI-Pko II and the activity of PI-Pko II was enhanced at higher potassium ion concentrations (1 M). Recognition sequences were also determined using synthetic oligonucleotides inserted into plasmid pUC19. It was shown that DNA sequences of 19 and 16 bp are needed for cleavage by PI-Pko I and PI-Pko II, respectively. PI-Pko II could cleave the downstream junction region between intein-encoding and mature DNA polymerase regions and cleavage by PI-Pko II could be detected even when chromosomal DNA of P.kodakaraensis KOD1 was used as substrate. Therefore, it is suggested that these endonucleases are switching endonucleases whose function lies in the rearrangement of chromosomal DNA.

Archaeal Proteins↗
PubMed1998

In vitro heat effect on heterooligomeric subunit assembly of thermostable indolepyruvate ferredoxin oxidoreductase.

Indolepyruvate ferredoxin oxidoreductase (IOR) from hyperthermophilic archaeon Pyrococcus kodakaraensis KOD1 catalyzes the oxidative decarboxylation of arylpyruvates by forming a heterooligomeric complex (alpha2beta2). The genes iorA and iorB which encode respective alpha and beta subunits, were coexpressed heterologously in Escherichia coli cells under anaerobic conditions. IOR activity was detected from the cell extract containing both subunits and its activity was enhanced by in vitro heat treatment prior to the assay. The iorA and iorB were expressed individually and each subunit was examined for enzymatic activity with and without heat treatment. IOR activity was detected neither from the extract of alpha subunit nor beta subunit. The alpha and beta subunits were mixed and then IOR activity was examined. Weak IOR activity was detected without heat treatment, however, upon heat treatment its activity was enhanced. The mixture of individually heat treated alpha and beta subunits did not possess any IOR activity even though the mixed sample was heat treated again. IOR alpha and beta subunits were individually purified to homogeneity, mixed with or without heat treatment and subunit assembly was examined by determining molecular mass. Upon heat treatment, inactive alpha and beta were converted to an active high molecular weight complex (195 kDa) which corresponds to the alpha2beta2 structure. However, the active complex was not formed without heat treatment, suggesting that high temperature environments are important for the heterooligomerization of IOR subunits.

Base Sequence↗
PubMed1998

Crystal structure of aspartyl-tRNA synthetase from Pyrococcus kodakaraensis KOD: archaeon specificity and catalytic mechanism of adenylate formation.

The crystal structure of aspartyl-tRNA synthetase (AspRS) from Pyrococcus kodakaraensis was solved at 1.9 A resolution. The sequence and three-dimensional structure of the catalytic domain are highly homologous to those of eukaryotic AspRSs. In contrast, the N-terminal domain, whose function is to bind the tRNA anticodon, is more similar to that of eubacterial enzymes. Its structure explains the unique property of archaeal AspRSs of accommodating both tRNAAsp and tRNAAsn. Soaking the apo-enzyme crystals with ATP and aspartic acid both separately and together allows the adenylate formation to be followed. Due to the asymmetry of the dimeric enzyme in the crystalline state, different steps of the reaction could be visualized within the same crystal. Four different states of the aspartic acid activation reaction could thus be characterized, revealing the functional correlation of the observed conformational changes. The binding of the amino acid substrate induces movement of two invariant loops which secure the position of the peptidyl moiety for adenylate formation. An unambiguous spatial and functional assignment of three magnesium ion cofactors can be made. This study shows the important role of residues present in both archaeal and eukaryotic AspRSs, but absent from the eubacterial enzymes.

Acylation↗
PubMed1998

Ion pairs involved in maintaining a thermostable structure of glutamate dehydrogenase from a hyperthermophilic archaeon.

Intersubunit ion pairs are considered to be involved for maintaining a stable structure of the glutamate dehydrogenase (GDH) from hyperthermophiles. In order to demonstrate an effect of intersubunit ion pairs on the structural stability, two kinds of mutation (T138E, Thr at position 138 was replaced by Glu; E158Q, Glu at position 158 was replaced by Gln) which add and remove ion pairs, respectively, were introduced into Pk-gdhA gene encoding GDH from Pyrococcus kodakaraensis KOD1. Addition of one ion pair (Pk-GDHA-T138E) increased the optimum temperature and thermostability. In contrast, Pk-GDH-E158Q showed lower optimum temperature and less thermostability than wild type GDH. Structure analysis of GDHs was performed by circular dichroism (CD) and indicated that all recombinant enzymes (Pk-GDH, Pk-GDH-T138E, Pk-GDH-E158Q) possess different structures from that of natural GDH. Upon heat treatment (60 degrees C, 2 h), the structures of Pk-GDH and Pk-GDH-T138E were converted to another form close to the natural structure. However, no structural conversion by heat treatment was observed in Pk-GDH-E158Q. These results indicate that intersubunit ion pairs play an important role in forming thermostable structure of Pk-GDH.

Amino Acid Sequence↗
PubMed1998

Epstein-Barr-virus-infected human T-cell line with a unique pattern of viral-gene expression.

Epstein-Barr-virus(EBV)-gene expression was analyzed in clonal sub-lines of the human T-cell line MT-2 that are persistently infected by the virus with a positive selection marker. Immunoblot analyses showed the expression of EBV proteins associated with the latent viral cycle, including the EBV nuclear antigen 1 (EBNA1) and the latent membrane protein 1 (LMP1), whereas EBNA2 was not detected. RT-PCR further demonstrated the expression of LMP2A, EBV-encoded small RNA 1 (EBER1), and complementary-strand transcripts from the BamHI-A fragment. EBNA2 mRNA was detected at a very low level. In addition to these latent viral functions, the BZLF1 protein, a transcription factor that activates a cascade of replicative-gene expression in EBV-infected B cells, was detected in these MT-2 clones by immunoblot analysis and immuno-enzymatic staining. Moreover, mRNA from other genes of the early virus-replicative cycle, such as BRLF1, BSMLF1, and BALF2, as well as BZLF1 was detected by Northern-blot analysis. Since sub-lines of the human B-cell lines BJAB and Louckes infected with similar recombinant EBV did not express these early genes, these data suggest that MT-2 cells are relatively permissive for expression of early EBV-replicative functions.

Cell Line↗
PubMed1998

Combined system of synchrotron radiation and laser for solid-state research.

Two combined systems of synchrotron radiation and laser have been constructed for solid-state research. One is a laser-induced fluorescence system to observe synchrotron radiation-induced desorption of alkali atoms from ionic crystals, which consists of a laser diode with a high repetition rate and synchrotron radiation under a single-bunch operation. The other is a system of two-photon spectroscopy, which is based on the combination of synchrotron radiation pulses with a low intensity and high repetition rate and Nd:YAG laser pulses with a high intensity and low repetition rate. The experimental systems and the preliminary results are presented in this report.

Journal Article↗
PubMed1998

Rates of change in spinal bone density among Japanese women.

To determine the rates of change in bone mineral density (BMD) at the spine in healthy Japanese women, longitudinal measurements of spinal BMD using dual X-ray absorptiometry were collected from 984 women over 17 years of age (mean age 51.6) at eight medical research centers. They were followed up for 20.9 months on average without any treatment influencing bone and calcium metabolism. Measurements of BMD obtained by two different scanners were converted into standardized BMD (sBMD) values. The multiple linear regression model predicts that spinal sBMD increases up to about 23 years of age: the estimated average rates of increases were 0.13%/year for women aged 20 years. After the age of 23, the sBMD began decreasing: the rates of loss increased by 0.045%/year for each year increase in age among premenopausal women. In perimenopausal women, the rate of loss was 2. 1%/year. In postnatural menopausal women, the rates of loss decreased exponentially with increasing years since menopause. The rates of loss increased by 0.04%/year for 1 kg decrease in body weight or by 0.1%/year for 1 kg/m2 decrease in body mass index. No significant differences in changes in sBMD were found between scanners and between centers after multiple adjustment. We conclude that the rates of change in spinal sBMD are associated with age in premenopausal women, and with years since menopause and weight or BMI in postmenopausal women. Caution is needed, however, when using data from different densitometers to evaluate rates in bone loss in multicenter trials.

Adolescent↗
PubMed1998

Presence of the CO2-concentrating mechanism in some species of the pyrenoid-less free-living algal genus Chloromonas (Volvocales, Chlorophyta).

Physiological and morphological characteristics related to the CO2-concentrating mechanism (CCM) were examined in several species of the free-living, unicellular volvocalean genus Chloromonas (Chlorophyta), which differs morphologically from the genus Chlamydomonas only by lacking pyrenoids. The absence of pyrenoids in the chloroplasts of Chloromonas (Cr.) rosae UTEX 1337, Cr. serbinowii UTEX 492, Cr. clatharata UTEX 1970, Cr. rosae SAG 26.90, and Cr. palmelloides SAG 32.86 was confirmed by light and electron microscopy. In addition, immunogold electron microscopy demonstrated that ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco; EC 4.1.1.39) molecules were distributed almost evently throughout the chloroplasts in all five Chloromonas strains. However, Chloromonas exhibited two types of physiological characteristics related to the CCM depending on the species or strains examined. Chloromonas rosae UTEX 1337 and Cr. serbinowii had high photosynthetic affinities for CO2 in cells grown in culture medium bubbled with air (low-CO2 cells), compared with those grown in medium bubbled with 5% CO2 (high-CO2 cells), indicating the presence of the low-CO2-inducible CCM. In addition, these two Chloromonas strains exhibited low-CO2-inducible carbonic anhydrase (CA; EC 4.2.1.1) activity and seemed to have small intracellular inorganic carbon pools. Therefore, it appears that Cr. rosae UTEX 1337 and Cr. serbinowii possess the CCM as in pyrenoid-containing microalgae such as Chlamydomonas reinhardtii. By contrast, Cr. clatharata, Cr. rosae SAG 26.90 and Cr. palmelloides showed low photosynthetic affinities for CO2 when grown under both CO2 conditions. Moreover, these three strains exhibited an apparent absence of intracellular inorganic carbon pools and lacked low-CO2-inducible CA activity. Thus, Cr. clatharata, Cr. rosae SAG 26.90 and Cr. palmelloides, like other pyrenoid-less algae (lichen photobionts) reported previously, seem to lack the CCM. The present study is the first demonstration of the CCM in pyrenoid-less algae, indicating that pyrenoids or accumulation of Rubisco in the chloroplasts are not always essential for the CCM in algae. Focusing on this type of CCM in pyrenoid-less algae, the physiological and evolutionary significance of pyrenoid absence is discussed.

Carbon Dioxide↗
PubMed1998

Expression and function of a retinoic acid receptor in budding ascidians.

Retinoic acid is thought to induce transdifferentiation of multipotent epithelial stem cells in the developing buds of the ascidian Polyandrocarpa misakiensis. We isolated a cDNA clone from this species, named PmRAR, encoding a retinoic acid receptor (RAR) homologue. PmRAR clusters with other RARs on phylogenetic trees constructed by three different methods. Within the cluster, PmRAR is on a separate branch from all the subtypes of RARs, suggesting that RAR subtypes arose in the ancestral vertebrates after divergence of vertebrates and urochordates. The embryos of another ascidian species Ciona intestinalis were co-electroporated with a mixture of a PmRAR expression vector and a lacZ reporter plasmid containing vertebrate-type retinoic acid response elements. The expression of lacZ depended on the presence of both retinoic acid and PmRAR, suggesting that PmRAR is a functional receptor. PmRAR mRNA is expressed in the epidermis and mesenchyme cells of the Polyandrocarpa developing bud. The mRNA is not detectable in the mesenchyme cells in the adult body wall, but its expression can be induced by retinoic acid in vitro. These results suggest that the PmRAR is a mediator of retinoic acid signalling in transdifferentiation during asexual reproduction of protochordates.

Amino Acid Sequence↗
PubMed1998

Sequence analysis of glutamate dehydrogenase (GDH) from the hyperthermophilic archaeon Pyrococcus sp. KOD1 and comparison of the enzymatic characteristics of native and recombinant GDHs.

The gdhA gene encoding glutamate dehydrogenase (GDH) from the hyperthermophilic archaeon Pyrococcus sp. KOD1 was cloned and sequenced. Phylogenetic analysis was performed on an alignment of 25 GDH sequences including KOD1-GDH, and two protein families were distinguished, as previously reported. KOD1-GDH was classified as new member of the hexameric GDH Family II. The gdhA gene was expressed in Escherichia coli, and recombinant KOD1-GDH was purified. Its enzymatic characteristics were compared with those of the native KOD1-GDH. Both enzymes had a molecular mass of 47,300 Da and were shown to be functional in a hexameric form (284 kDa). The N-terminal amino acid sequences of native KOD1-GDH and the recombinant GDH were VEIDPFEMAV and MVEIDPFEMA, respectively, indicating that native KOD1-GDH does not retain the initial methionine at the N-terminus. The recombinant GDH displayed enzyme characteristics similar to those of the native GDH, except for a lower level of thermostability, with a half-life of 2 h at 100 degrees C, compared to 4 h for the native enzyme purified from KOD1. Kinetic studies suggested that the reaction is biased towards glutamate production. KOD1-GDH utilized both coenzymes NADH and NADPH, as do most eukaryal GDHs.

Amino Acid Sequence↗
PubMed1998

The O6-methylguanine-DNA methyltransferase from the hyperthermophilic archaeon Pyrococcus sp. KOD1: a thermostable repair enzyme.

The enzyme O6-methylguanine-DNA methyltransferase (MGMT) is the most common form of cellular defense against the biological effects of O6-methylguanine (O6-MeG) in DNA. Based on PCR amplification using primers derived from conserved amino acid sequences of MGMTs from 11 species, we isolated the DNA region coding for MGMT from the hyperthermophilic archaeon Pyrococcus sp. KOD1. The MGMT gene from KOD1 (mgtk) comprises 522 nucleotides, encoding 174 amino acid residues; its product shows considerable similarity to the corresponding mammalian, yeast and bacterial enzymes, especially around putative methyl acceptor sites. Phylogenetic analysis of MGMTs showed that archaeal MGMTs were grouped with their bacterial counterparts. The location of the MGMT gene on the KOD1 chromosome was also determined. The cloned KOD1 MGMT gene was overexpressed using the T7 RNA polymerase expression system, and the recombinant protein was purified by ammonium sulfate fractionation, heat treatment, ion-exchange chromatography and gel filtration chromatography. The purified recombinant protein was assayed for its enzyme activity by monitoring transfer of [3H]methyl groups from the substrate DNA to the MGMT protein; the activity was found to be stable at 90 degrees C for at least 30 min. When the mgtk gene was placed under the control of the lac promoter and expressed in the methyltransferase-deficient Escherichia coli strain KT233 (delta ada, delta ogt) cells, a MGMT was produced. The enzyme was functional in vivo and complemented the mutant phenotype, making the cells resistant to the cytotoxic properties of the alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine.

Amino Acid Sequence↗