Biomedical subjects

N Murata

Publications and source records attributed to N Murata.

At least 127 records · Page 7Linked to original sources

PubMed1997

The action in vivo of glycine betaine in enhancement of tolerance of Synechococcus sp. strain PCC 7942 to low temperature.

The cyanobacterium Synechococcus sp. strain PCC 7942 was transformed with the codA gene for choline oxidase from Arthrobacter globiformis under the control of a constitutive promoter. This transformation allowed the cyanobacterial cells to accumulate glycine betaine at 60 to 80 mM in the cytoplasm. The transformed cells could grow at 20 degrees C, the temperature at which the growth of control cells was markedly suppressed. Photosynthesis of the transformed cells at 20 degrees C was more tolerant to light than that of the control cells. This was caused by the enhanced ability of the photosynthetic machinery in the transformed cells to recover from low-temperature photoinhibition. In darkness, photosynthesis of the transformed cells was more tolerant to low temperature such as 0 to 10 degrees C than that of the control cells. In parallel with the improvement in the ability of the transformed cells to tolerate low temperature, the lipid phase transition of plasma membranes from the liquid-crystalline state to the gel state shifted toward lower temperatures, although the level of unsaturation of the membrane lipids was unaffected by the transformation. These findings suggest that glycine betaine enhances the tolerance of photosynthesis to low temperature.

Alcohol Oxidoreductases↗

PubMed1997

Synthesis of a new potent anti-angiogenic agent, 17 alpha-acetoxy-9 alpha-fluoro-6 alpha-methylprogesterone (9 alpha-fluoromedroxyprogesterone acetate [FMPA]).

A new anti-angiogenic agent, 17 alpha-acetoxy-9 alpha-fluoro-6 alpha-methylprogesterone (9 alpha-fluoromedoroxyprogesterone acetate [FMPA, 9] was synthetized in a 10-step sequence. FMPA (9) had about two orders of magnitude stronger anti-angiogenic activity than medroxyprogesterone acetate (MPA), as estimated in a bioassay involving chorioallantoic membranes of growing chick embryos.

Animals↗

PubMed1997

Hydroxyapatite in revision of total hip replacements with massive acetabular defects: 4- to 10-year clinical results.

Hydroxyapatite (HA) granules of 100 to 300 microm, 0.9 to 1.2 mm and 3.0 to 5.0 mm were mixed in a ratio of 10:45:45 and packed into massive bone deficiencies in revision operations for total hip arthroplasty. We did not use additional graft or cup support for deficiencies of the lateral and medial wall. The procedure was carried out in 40 hips between 1986 and 1992. The radiographic spaces seen at the interface between HA and bone immediately after surgery disappeared within three months. Some spaces appeared between HA granules near the bone in the lateral part of two joints, and three sockets migrated in patients with severe segmental and cavitary deficiencies. Direct bonding of HA to bone was observed radiologically without morphological changes, except in the three joints with migration. All patients could walk without pain but the three with definite loosening needed crutches.

Acetabulum↗

PubMed1997

Autoimmune hepatitis triggered by administration of an herbal medicine.

Although herbal medicines are believed to be safe with few side effects, there are several reports on drug-induced liver injury caused by them. However, there are no reports of autoimmune hepatitis triggered by herbal medicines. We report here the case of a patient with autoimmune hepatitis that became clinically apparent after administration of Dai-saiko-to (Da-Chai-Hu-Tang), an herbal medicine that is used as a standard medicine in Japan.

Autoimmune Diseases↗

PubMed1997

[Idiopathic CD4+ T-lymphocytopenia terminating in Burkitt's lymphoma].

A 33-year-old male was admitted because of severe neutropenia (55/microliter) in 1985. A diagnosis of autoimmune neutropenia was not made. CD4+ T-lymphocyte count was 128/microliter and CD4/CD8, 0.1, though the titers of immunoglobulins were in normal range. Nine times examinations of CD4+ T-lymphocyte count resulted in 5 times lower counts than 300/microliter between 1985 and 1993. His HIV (type 1 and type 2) studies were negative. He suffered from EB virus infection in 1987. The titers of VCA-IgG and EA-IgG had been elevated for half a year after that. He was operated polyp-like tumors in bilateral nasal cavities on February in 1994. The diagnosis was Burkitt's lymphoma that was also demonstrated by in situ hybridization using EB virus RNA. He was treated with a modification of COPBLAM III, but he died on June in 1994. Autopsy revealed tumor cell infiltrations in multiple organs. We suspect that he developed Burkitt's lymphoma 82 months later, when he had complicated EB virus infection in condition of idiopathic CD4+ T-lymphocytopenia caused by unknown origin.

Adult↗

PubMed1996

Targeted mutagenesis of acyl-lipid desaturases in Synechocystis: evidence for the important roles of polyunsaturated membrane lipids in growth, respiration and photosynthesis.

Acyl-lipid desaturases introduce double bonds (unsaturated bonds) at specifically defined positions in fatty acids that are esterified to the glycerol backbone of membrane glycerolipids. The desA, desB and desD genes of Synechocystis sp. PCC 6803 encode acyl-lipid desaturases that introduce double bonds at the delta12, omega3 and delta6 positions of C18 fatty acids respectively. The mutation of each of these genes by insertion of an antibiotic resistance gene cartridge completely eliminated the corresponding desaturation reaction. This system allowed us to manipulate the number of unsaturated bonds in membrane glycerolipids in this organism in a step-wise manner. Comparisons of the variously mutated cells revealed that the replacement of all polyunsaturated fatty acids by a monounsaturated fatty acid suppressed growth of the cells at low temperature and, moreover, it decreased the tolerance of the cells to photoinhibition of photosynthesis at low temperature by suppressing recovery of the photosystem II protein complex from photoinhibitory damage. However, the replacement of tri- and tetraunsaturated fatty acids by a diunsaturated fatty acid did not have such effects. These findings indicate that polyunsaturated fatty acids are important in protecting the photosynthetic machinery from photoinhibition at low temperatures.

Calorimetry, Differential Scanning↗

PubMed1996

Immunocytochemical localization of acyl-lipid desaturases in cyanobacterial cells: evidence that both thylakoid membranes and cytoplasmic membranes are sites of lipid desaturation.

There are four acyl-lipid desaturases in the cyanobacterium Synechocystis sp. PCC 6803. Each of these desaturases introduces a double bond at a specific position, such as the Delta6, Delta9, Delta12, or omicron3 position, in C18 fatty acids. The localization of the desaturases in cyanobacterial cells was examined immunocytochemically with antibodies raised against synthetic oligopeptides that corresponded to the carboxyl-terminal regions of the desaturases. All four desaturases appeared to be located in the regions of both the cytoplasmic and the thylakoid membranes. These findings suggest that fatty acid desaturation of membrane lipids takes place in the thylakoid membranes as well as in the cytoplasmic membranes.

Journal Article↗

PubMed1996

A numerical study on learning curves in stochastic multilayer feedforward networks.

The universal asymptotic scaling laws proposed by Amari et al. are studied in large scale simulations using a CM5. Small stochastic multilayer feedforward networks trained with backpropagation are investigated. In the range of a large number of training patterns t, the asymptotic generalization error scales as 1/t as predicted. For a medium range t a faster 1/t2 scaling is observed. This effect is explained by using higher order corrections of the likelihood expansion. It is shown for small t that the scaling law changes drastically, when the network undergoes a transition from strong overfitting to effective learning.

Learning↗

PubMed1996

The coxD gene for heme O synthase in Synechocystis.

The cyanobacterial coxD gene for heme O synthase was cloned from Synechocystis sp. PCC 6803 and its nucleotide sequence was determined. The deduced amino-acid sequence of the gene was homologous to the amino-acid sequences of bacterial heme O synthesis. In contrast to the genes for heme O synthases in other prokaryotes, which are clustered together with genes for the structural subunit(s) of cytochrome oxidase, the coxD gene is not linked to such genes on the chromosome of Synechocystis.

Amino Acid Sequence↗

PubMed1996

Characterization of the Fad12 mutant of Synechocystis that is defective in delta 12 acyl-lipid desaturase activity.

The Fad12 mutant of Synechocystis sp. PCC 6803 has a defect in the desA gene for delta 12 acyl-lipid desaturase. We identified a change in the nucleotide sequence of the structural gene for the desaturase, in which a leucine codon has been converted to a stop codon. Western blot analysis revealed that the delta 12 acyl-lipid desaturase was localized in both plasma membranes and thylakoid membranes of wild-type cells but was absent from both types of membrane in Fad12 cells. These findings suggest that the desaturation of fatty acids takes place in both types of membrane in Synechocystis sp. PCC 6803. The mutation in the delta 12 desaturase did not affect the lipid composition of thylakoid and plasma membranes, but it changed the fatty acid composition of lipids in similar ways in both types of membrane.

Amino Acid Sequence↗

PubMed1996

Cloning of Brassica napus CTP: phosphocholine cytidylyltransferase cDNAs by complementation in a yeast cct mutant.

CTP:phosphocholine cytidylyltransferase is a rate-limiting enzyme in biosynthesis of phosphatidylcholine in plant cells. We have isolated four cDNAs for the cytidylyltransferase from a root cDNA library of Brassica napus by complementation in a yeast cct mutant. The deduced amino-acid sequences of the B. napus enzymes resembled rat and yeast enzymes in the central domain. Although all cytidylyltransferases ever cloned from B. napus and other organisms were predicted to be structurally hydrophilic, the yeast cct mutant transformed with one of the B. napus cDNA clones restored the cytidylyltransferase activity in the microsomal fraction as well as in the soluble fraction. These results are consistent with a recent view that yeast cells contained a machinery for targeting the yeast cytidylyltransferase to membranes, and may indicate that the B. napus enzyme was compatible with the machinery.

Amino Acid Sequence↗

PubMed1996

Low-temperature resistance of higher plants is significantly enhanced by a nonspecific cyanobacterial desaturase.

A broad-specificity delta 9 desaturase gene was cloned from the cyanobacterium Anacystis nidulans. The enzyme introduces a cis-double bond at the delta 9 position of both 16 and 18 carbon saturated fatty acids linked to many kinds of membrane lipids. The gene was stably introduced into tobacco plants under transcriptional control of the cauliflower mosaic virus 35S promoter, and the enzyme was targeted into plastids by the transit peptide of the pea RuBisCO small subunit. The transgenic plants had a highly reduced level of saturated fatty acid content in most membrane lipids and exhibited a significant increase in chilling resistance.

Adaptation, Physiological↗

PubMed1996

[Autoimmune hemolytic anemia with eosinophilia in elderly patient].

A 70-year-old woman was admitted to our hospital in November 1992 for evaluation of anemia. Physical examination revealed anemia, jaundice, swelling of axial and inguinal lymph nodes, and splenomegaly. Abnormal hematological findings were as follows: Hb of 3.9 g/dl, reticulocyte count of 58.2% (61.7 x 10(4)/microliters), hyperplasia of normal erythroblasts in bone marrow, and eosinophilia (21.0%, 2352/microliters) in peripheral blood. Routine laboratory examinations revealed polycolonal hypergammaglobulinemia 3.0 g/dl, a high level of serum LDH (797 IU/I) and a total bilirubin of 2.4 mg/dl (indirect, 1.6 mg/dl). The serum haptoglobin level was very low (< 5 mg/dl). Results of serological examinations were as follows: IgG of 3366 mg/dl, CH50 of 16.0 U/ml, positive Coombs test 2+, and positive tests for antinuclear antibody, rheumatoid factor, and cold agglutinin. CRP was negative. PHA-stimulated lymphocyte blast formation, NK activity, and ADCC activity were found to be suppressed, and the percentage of CD4-positive lymphocytes in peripheral blood was also low. An axillary lymph node biopsy revealed reactive lymphadenitis. No signs or history suggested allergy, collagen disease, or parasitic infection. Autoimmune hemolytic anemia (AIHA) complicated by immunologic abnormalities and eosinophilia was diagnosed. Oral prednisolone markedly reduced the hemolytic anemia, eosinophilia, lymph node swelling, and splenomegaly, but NK activity remained low.

Aged↗

PubMed1996

[Contingent negative variations associated with vocalization in humans].

We investigated the late negative components of the contingent negative variations (CNVs) in the verbalization task. Six subjects were instructed to perform three different motor tasks, jaw opening, vocalization of a meaningless sound and that of a word, in response to a sound stimulus following a visual warning stimulus with interstimulus interval of 4.0 sec. The electroencephalograms (EEGs) were recorded from the midline-central (Cz), left and right temporal areas (T3 and T4) and frontal areas (F7 and F8). EEGs were averaged 16 times using the visual stimulus pulse as a trigger to obtain the CNVs in each motor task. There was no significant difference between the tasks of the jaw opening and vocalization of the sound in the CNV amplitudes at bilateral electrodes. However, the amplitudes of the CNVs at the left frontal and temporal areas were significantly larger in the case of vocalization of the word than in that of jaw opening (p < 0.05). On the other hand, there was no significant difference between these two tasks in the CNV amplitudes at the right frontal and temporal areas. Our results suggested that the CNVs generated over the left hemisphere might reflect the brain activities involved in language production.

Adult↗

PubMed1996

[The shock patients with the cardiac tamponade resulting from acute type A aortic dissection].

Twelve patients with acute type A aortic dissection were admitted at Ohta-Nishinouti Hospital from Jan. 1991 to Mar. 1994. Three of these 12 cases were in shock with cardiac tamponade on arrival at the hospital. Immediate resuscitative management was necessary for these patients, but pericardiocentasis was fruitless in the first case and emergent thoracotomy had led to the aortic rupture. While the second case was the thrombosed type aortic dissection and successfully performed pericardiocentasis, CT findings showed recanalization of the pseudolumen after a day, then we performed the urgent operation. By means of these experiences, the third case was operated quickly in spite of the thrombosed type aortic dissection, and had good result. We concluded that immediate surgical intervention should be taken to the shock patients with cardiac tamponade resulted from acute type A aortic dissection.

Acute Disease↗

PubMed1996

[The history of the treatment for portal hypertension].

Until recently, the only effective treatment for bleeding esophageal varices was surgery, including portal-systemic shunts, nonshunting operations, and selective shunts. New operations were developed from the neccessity to find a better therapeutic modality for the treatment. This article describes the history of development of surgical treatment for portal hypertension as well as introducing the outline of several such procedures. The history of nonoperative treatments, especially endoscopic injection screlotherapy, is also described: Endoscopic sclerotherapy as a treatment for bleeding esophageal varices had been employed before many definitive surgical procedures. In accordance with the development of fiberoptic endoscopy, endoscopic sclerotherapy came into prominance. The less invasive treatment is appreciated and popularized even among surgeons today, who once believed that shunt operation (or nonshunting operation) was the best modality of treatment for esophageal varices. Finally, this article provides readers with a simplified guide to Japanese participation in the development of treatment for esophagogastric varices.

Esophageal and Gastric Varices↗

PubMed1996

Prevention of human T cell lymphotropic virus type I infection in Japanese macaques by passive immunization.

Prophylaxis against human T cell lymphotropic virus type I (HTLV-I) is of primary importance for the eradication of adult T cell leukemia and other diseases associated with this virus. Hyperimmune globulin (H-IgG) prepared from healthy blood donors with high antibody titers for HTLV-I was evaluated for its prophylactic effect against HTLV-I in Japanese macaques (Macaca fuscata). Normal IgG (N-IgG) prepared from seronegative healthy blood donors was used as control. Both preparations contained 50 mg/ml IgG and H-IgG had a neutralizing antibody titer of 1:7100 by vesicular stomatitis virus (HTLV-I) pseudotype neutralization assay. Two macaques were infused with 2 ml/kg N-IgG and three macaques were immunized with 2-0.5 ml/kg H-IgG. They were immediately challenged by inoculation of 8 x 10(6)/kg cells from an HTLV-I-producing rabbit lymphoid cell line (Ra-1). Another macaque was immunized with 1 ml/kg H-IgG 24h after inoculation of 8 x 10(6)/kg Ra-1 cells. HTLV-I infection, as determined by seroconversion and verified by polymerase chain reaction, occurred in both of the N-IgG-injected macaques but in none of the four H-IgG-injected macaques. These results demonstrate the protective efficacy of H-IgG against HTLV-I infection in a primate model and provide an experimental basis for passive immunization trials in humans.

Animals↗

PubMed1995

High avidity state of leukocyte function-associated antigen-1 on rheumatoid synovial fluid T lymphocytes.

The integrin LFA-1 (CD11a/CD18) is a cell surface adhesion molecule required for leukocyte extravasation and subsequent immune and inflammatory responses. Rapid transition between nonadherent and adherent states of LFA-1 is of key importance to Ag-specific recognition of T lymphocytes. In this paper, LFA-1-mediated adhesiveness of peripheral blood (PB) and synovial fluid (SF) T lymphocytes to affinity-purified ICAM-1-coated plates was studied in patients with rheumatoid arthritis (RA) and in patients with non-RA panels, including osteoarthritis, ankylosing spondylitis, erythema nodosum, pseudogout, and pustulosis. LFA-1-mediated adhesiveness of SF T lymphocytes was not observed in any of the 10 non-RA patients studied, although cross-linking of the TCR on lymphocytes from these patients rapidly converted LFA-1 to an adhesive state. In contrast, SF T lymphocytes from 10 of 12 RA patients exhibited LFA-1-mediated adhesiveness without a requirement for cross-linking of the TCR. No difference was seen in the cell surface density of LFA-1 between non-RA and RA T lymphocytes, suggesting that the difference in adhesiveness was due to a high avidity state of LFA-1 on SF T lymphocytes in RA. Furthermore, exposure of PB T lymphocytes, which showed a low avidity state of LFA-1, to whole SF from RA patients that was depleted of T lymphocytes could induce a high avidity state of LFA-1 in vitro. Cellfree SF from RA patients also could stimulate adhesiveness, although to a lesser extent. These data suggest the existence of a LFA-1-activating environment that is selectively found in SF from RA patients.

Adult↗