Biomedical subjects

N Murata

Publications and source records attributed to N Murata.

At least 109 records · Page 6Linked to original sources

PubMed1998

Alteration of low-temperature susceptibility of the cyanobacterium Synechococcus sp. PCC 7002 by genetic manipulation of membrane lipid unsaturation.

Cyanobacteria acclimate to low temperature by desaturating their membrane lipids. Mutant strains of Synechococcus sp. PCC 7002 containing insertionally inactivated desA (Delta12 acyl-lipid desaturase) and desB (omega3 acyl-lipid desaturase) genes were produced, and their low-temperature susceptibility was characterized. The desA mutant synthesized no linoleic acid or alpha-linolenic acid, and the desB mutant did not produce alpha-linolenic acid. The desA mutant grew more slowly than the wild-type at 22 degrees C and could not grow at 15 degrees C. The desB mutant could not continuously grow at 15 degrees C, although no observable phenotype appeared at higher temperatures. It has been shown that expression of the desA gene occurs at 38 degrees C and is up-regulated at 22 degrees C, and that the desB gene is only expressed at 22 degrees C. These results indicate that the expression of the desA and desB genes occurs at higher temperatures than those at which a significant decline in physiological activities is caused by the absence of their products. The temperature dependency of photosynthesis was not affected by these mutations. Since chlorosis and inability to grow at 15 degrees C with nitrate was suppressed by the substitution of urea as a nitrogen source, it is very likely that the chilling susceptibility of the desaturase mutants is attributable to nutrient limitation.

Adaptation, Physiological↗

PubMed1998

Metabolic engineering of rice leading to biosynthesis of glycinebetaine and tolerance to salt and cold.

Genetically engineered rice (Oryza sativa L.) with the ability to synthesize glycinebetaine was established by introducing the codA gene for choline oxidase from the soil bacterium Arthrobacter globiformis. Levels of glycinebetaine were as high as 1 and 5 micromol per gram fresh weight of leaves in two types of transgenic plant in which choline oxidase was targeted to the chloroplasts (ChlCOD plants) and to the cytosol (CytCOD plants), respectively. Although treatment with 0.15 M NaCl [corrected] inhibited the growth of both wild-type and transgenic plants, the transgenic plants began to grow again at the normal rate after a significantly less time than the wild-type plants after elimination of the salt stress. Inactivation of photosynthesis, used as a measure of cellular damage, indicated that ChlCOD plants were more tolerant than CytCOD plants to photoinhibition under salt stress and low-temperature stress. These results indicated that the subcellular compartmentalization of the biosynthesis of glycinebetaine was a critical element in the efficient enhancement of tolerance to stress in the engineered plants.

Acclimatization↗

PubMed1998

The effects of polyethylene cup thickness on wear of total hip prostheses.

The wear rate of the ultrahigh molecular weight polyethylene cups in combination with a 28 mm alumina femoral head was measured on the radiographs of patients without any complications, and on cups retrieved due to slight loosening of the prosthesis or due to late infection between bone and components. The wear rate on the radiographs did not include the initial wear, but the wear rate on the retrieved cups did include the initial wear. The wear rate on the retrieved cups was higher, by 50%, than that measured on the radiographs. In both cases, the thicker the polyethylene cups, the lower was the wear rate measured. The average wear rate of the 7 and 8 mm thick cups was about twice that of cups 10 and 11 mm thick. From these results, we conclude that polyethylene cups more than 11 mm thick should be used.

Journal Article↗

PubMed1998

Enhancement of the tolerance of Arabidopsis to high temperatures by genetic engineering of the synthesis of glycinebetaine.

Arabidopsis thaliana was transformed with the codA gene for choline oxidase from Arthrobacter globiformis under control of the 35S RNA promoter of cauliflower mosaic virus. As a result, high levels of glycinebetaine accumulated in the seeds of transformed plants. Transformation with the codA gene significantly enhanced the tolerance to high temperatures during the imbibition and germination of seeds, as well as during growth of young seedlings. The extent of enhancement of the tolerance to high temperature was correlated with levels of choline oxidase expressed and of glycinebetine accumulated in the transformed plants. The induction of homologues of heat shock protein 70 at high temperature was less conspicuous in the transformed plants than in the wild-type plants, suggesting that the transformation alleviated the high-temperature stress.

Adaptation, Physiological↗

PubMed1998

An association between the natural course of shoulder joint destruction in rheumatoid arthritis and HLA-DRB1*0405 in Japanese patients.

To assess the association between HLA-DRB1 alleles and shoulder destruction due to rheumatoid arthritis (RA) in Japanese, we typed for HLA-DRB1 alleles in 100 Japanese RA patients who could be classified into 5 groups: non-progressive (N) with normal radiographs; erosive (E) showing marginal erosion but no collapse; collapse (C) showing subchondral cysts followed by collapse; arthrosis-like (A) showing osteoarthrotic features; and the mutilating (M) showing mutilating bone destruction. The HLA-DRB1*0405 antigen frequency in N, E, C, A, and M types was 55%, 61%, 33%, 71%, 100%, respectively. That in the M type (100%) was significantly higher than that in the others (the N, E, C, and A types; 57%). These findings suggest that the most severe shoulder joint destruction pattern in RA, the M type, is associated with HLA-DRB1*0405.

Adult↗

PubMed1998

The homozygote of HLA-DRB1*0901, not its heterozygote, is associated with rheumatoid arthritis in Japanese.

To assess the association between HLA-DRB1*0901 and Japanese rheumatoid arthritis (RA) patients, we analyzed the frequency of HLA-DRB1*0901 in 852 Japanese RA patients. We found that the homozygote of DRB1*0901 was associated with Japanese RA patients, while the heterozygote of DRB1*0901 was not. These findings suggest that DRB1*0901 is a weakly susceptible allele of RA, which in our investigation was not associated with RA by a single allele, but can be by a homozygote. DRB1*0901 does not have the shared epitope, and it is suggested that there may be some mechanism ofthe association between HLA-DRB1 and RA other than the shared epitope, which was not strong.

Alleles↗

PubMed1998

Characterization of delta 9 acyl-lipid desaturase homologues from Arabidopsis thaliana.

Two cDNAs, ADS1 and ADS2, were isolated from Arabidopsis. These cDNAs encoded proteins homologous to delta 9 acyl-lipid desaturases of cyanobacteria and acyl-CoA desaturases of yeast and mammals. The expression of ADS1 and ADS2 was organ-dependent. Cold temperature up-regulated the ADS2 expression, whereas it down-regulated the ADS1 expression.

Amino Acid Sequence↗

PubMed1998

Elderly-onset rheumatoid arthritis and its association with HLA-DRB1 alleles in Japanese.

To assess the association between HLA-DRB1 and elderly-onset rheumatoid arthritis (RA) (EORA) in Japanese people, we analysed the HLA-DRB1 antigen frequencies of EORA patients. The age at onset distribution of 852 Japanese RA patients was analysed, and EORA was defined as an age at onset of 60 yr or older. Among the 852 RA patients, 120 (14.1%) were EORA patients. Their HLA-DRB1 antigen frequencies were assessed for significant deviation from those of the control (n = 652) and adult-onset RA (AORA; disease onset between 16 and 59 yr; n = 732) groups. The Japanese EORA patients were positively associated with DRB1*0101, *0405 and *1502, and the relative risks were 2.7, 1.9 and 2.2, respectively. The frequency of DRB1*1502 was also significantly higher among the EORA patients than in the AORA patients. The EORA patients showed different trends from the AORA patients in their frequency of HLA-DRB1 alleles, which suggests that EORA may be a different subset from AORA in light of its immunogenetic background.

Adolescent↗

PubMed1998

[A case report of neoadjuvant intra-arterial injection chemotherapy combined with peripheral blood stem cell reinfusion in an advanced breast cancer patient].

A seventy-one year-old woman suffered from Stage IIIb advanced breast cancer complicated with direct thoracic invasion and skin eruption. An indwelling intra-arterial catheter was inserted into the subclavian artery for the administration of anti tumor agents. After three courses of neoadjuvant chemotherapy combined with G-CSF and/or PBSCT reinfusion, the breast cancer revealed a remarkable size reduction and was absent from direct thoracic and pectoral muscle, invasion within the physical status and visual analysis by CT scan. Thereafter, the patient underwent a radical mastectomy. In the pathological findings of the operation specimen, despite a remarkable tumor collapse, the microscopic invasion remained in the shallow layer of the pectoral muscle. Thus, the patient should be given additional postoperative irradiation. The patients has had six months of stable tumor-free survival since the mastectomy.

Aged↗

PubMed1998

[Adjuvant chemotherapy with UFT or UFT with OK-432 to patients with gastric and colorectal cancer. Kanto Adjuvant Study Group].

In Japan, long-term oral therapy with tegafur in combination with immunopotentiators is commonly used as adjuvant therapy after curative resection of gastric or colorectal can for gastric and colorectal cancer. When the outcome was analyzed in terms of the relative performance (R.P.) and the individual dose intensity (I.D.I.) of OK-432, gastric cancer patients with a R.P. of 0.5 or higher tended to have a better survival curve. There were no marked differences in lymphocytes subsets, except that the Leu 7 level at 3 months after gastric cancer resection was significantly higher (p < 0.05) in group B than in group A. Thus, no inhibition of the anticancer effect of UFT was noted during long term combination therapy with UFT and an immunopotentiator as postoperative adjuvant therapy for patients who underwent curative resection of gastric or colorectal cancer. The results suggest that UFT combined with long-term OK-432 maintenance therapy may contribute to improve survival rates in gastric cancer patients.

Adjuvants, Immunologic↗

PubMed1997

Glycerol-3-phosphate acyltransferase in plants.

Glycerol-3-phosphate acyltransferase (GPAT) catalyzes the transfer of an acyl group from an acyl donor to the sn-1 position of glycerol 3-phosphate. The plant cell contains three types of GPAT, which are located in the chloroplasts, mitochondria and cytoplasm, respectively. The enzyme in chloroplasts is soluble and uses acyl-(acyl-carrier protein) as the acyl donor, whereas the enzymes in the mitochondria and the cytoplasm are bound to membranes and use acyl-CoA as the acyl donor. cDNAs for GPAT of chloroplasts have been cloned from several plants, and the gene for the enzyme has been cloned from Arabidopsis thaliana. The amino acid sequences deduced from the nucleotide sequences of cDNAs indicate that the product of translation is a precursor of about 460 amino acid residues, which consists of a leader sequence of about 70 amino acid residues and a mature protein of about 400 residues, with a molecular mass of about 42 kDa. Genetic engineering of the unsaturation of fatty acids has been achieved by manipulation of the cDNA for the GPAT found in chloroplasts and has allowed modification of the ability of tobacco to tolerate chilling temperatures.

Amino Acid Sequence↗

PubMed1997

Low-temperature-induced desaturation of fatty acids and expression of desaturase genes in the cyanobacterium Synechococcus sp. PCC 7002.

Changes in response to temperature of lipid classes, fatty acid composition and mRNA levels for acyl-lipid desaturase genes were studied in the marine unicellular cyanobacterium, Synechococcus sp. PCC 7002. The degree of unsaturation of C18 fatty acids increased in cells grown at lower temperature for all lipid classes, and omega 3 desaturation occurred specifically in cells grown at low temperature. While the level of 18:1(9) fatty acids declined, desaturation at the omega 3 position of C18 fatty acids increased gradually during a 12-h period after a temperature shift-down to 22 degrees C. However, the mRNA levels of the desA (delta 12 desaturase), desB (omega 3 desaturase) and desC (delta 9 desaturase) genes increased within 15 min after a temperature shift-down to 22 degrees C; the desaturase gene mRNA levels also rapidly declined within 15 min after a temperature shift-up to 38 degrees C. Therefore, the elevation of mRNA levels for the desaturase genes is not the rate-limiting event for the increased desaturation of membrane lipids after a temperature shift-down. The rapid, low-temperature-induced changes in mRNA levels occurred even when cells were grown under light-limiting conditions for which the growth rates at 22 degrees C and 38 degrees C were identical. These studies indicate that the ambient growth temperature, and not some other growth rate-related process, regulates the expression of acyl lipid desaturation in this cyanobacterium.

Cold Temperature↗

PubMed1997

High serum levels of CA125 and interleukin-6 in a patient with Ki-1 lymphoma.

We report a 53-year-old-man with an aggressive Ki-1 lymphoma who had high serum CA125, a marker protein of the epithelial ovarian cancer, and interleukin-6 (IL-6) concentrations. Both CA125 and IL-6 levels decreased after chemotherapy and elevated with disease progression. The patient's lymphoma cells obtained before chemotherapy grew continuously in vitro, were IL-6 dependent and were found to secrete CA125 in culture medium. These results indicate that CA125 can be secreted by Ki-1 lymphoma cells and IL-6 may promote the growth of Ki-1 lymphoma cells.

Aged↗

PubMed1997

Differences in the control of the temperature-dependent expression of four genes for desaturases in Synechocystis sp. PCC 6803.

Cyanobacteria are capable of desaturating the fatty acids in their membrane lipids in response to decreases in temperature. The cyanobacterium, Synechocystis sp. PCC 6803, contains four desaturases, which specifically catalyse desaturation at the delta6, delta9, delta12 and omega3 positions of fatty acids. The levels of the mRNAs transcribed from the genes that encode the delta6, delta12 and omega3 desaturases increased about 10-fold, but at different rates, upon a decrease in temperature from 34 degrees C to 22 degrees C, whereas the level of the mRNA for the delta9 desaturase remained constant. The increases in the levels of mRNAs were caused both by the enhanced transcription and by the increased stability of the mRNAs at the low temperature. Western blotting analysis demonstrated that levels of the delta6, delta12 and omega3 desaturases increased at different rates at the low temperature, while that of the delta9 desaturase remained constant. These observations indicate that the expression of the genes for the four desaturases is regulated by temperature in different ways.

Animals↗

PubMed1997

Transformation of Arabidopsis thaliana with the codA gene for choline oxidase; accumulation of glycinebetaine and enhanced tolerance to salt and cold stress.

Glycinebetaine is one of the compatible solutes that accumulate in the chloroplasts of contain halotolerant plants when these plants are exposed to salt or cold stress. The codA gene for choline oxidase, the enzyme that converts choline into glycinebetaine, has previously been cloned from a soil bacterium, Arthrobacter globiformis. Transformation of Arabidopsis thaliana with the cloned codA gene under the control of the 35S promoter of cauliflower mosaic virus enabled the plant to accumulate glycinebetaine and enhanced its tolerance to salt and cold stress. At 300 mM NaCl, considerable proportions of seeds of transformed plants germinated well, whereas seeds of wild-type plants failed to germinate. At 100 mM NaCl, transformed plants grew well whereas wild-type plants did not do so. The transformed plants tolerated 200 mM NaCl, which was lethal to wild-type plants. After plants had been incubated with 400 mM NaCl for two days, the photosystem II activity of wild-type plants had almost completely disappeared, whereas that of transformed plants remained at more than 50% of the original level. When exposed to a low temperature in the light, leaves of wild-type plants exhibited symptoms of chlorosis, whereas those of transformed plants did not. These observations demonstrate that the genetic modification of Arabidopsis thaliana that allowed it to accumulate glycinebetaine enhanced its ability to tolerate salt and cold stress.

Acclimatization↗

PubMed1997

The relationship between HLA-DRB1 alleles and disease subsets of rheumatoid arthritis in Japanese.

To assess the association between HLA-DRB1 and the pathogenesis of rheumatoid arthritis (RA) in the Japanese population, we typed for HLA-DRB1 alleles in 852 Japanese patients. An analysis of HLA-DRB1 allele associations was performed on the overall group and in three disease subsets of adult-onset RA, classified according to the extent of joint destruction evident on plain radiograms, i.e. least erosive subset (LES), more erosive subset (MES) and most erosive subset with mutilating disease (MUD). The Japanese RA patients with positively associated with DRB1*0101 and *0405, and negatively associated with DRB1*0701, *0802, *1302 and *1405. DRB1*0101 was associated more strongly with a milder disease subset and the relative risk (RR) was 1.9, 1.5 and 1.2 for LES, MES and MUD, respectively. On the other hand, DRB1*0405 was associated more strongly with a more severe disease subset, the RR being 1.8, 4.0 and 4.3 for LES, MES and MUD, respectively. These findings suggest that RA is a heterogeneous disease, not only clinically, but also in terms of its immunogenetic background, and that HLA-DRB1 can be a useful prognostic factor for RA.

Adolescent↗

PubMed1997

Membrane lipid unsaturation modulates processing of the photosystem II reaction-center protein D1 at low temperatures.

The role of membrane lipid unsaturation in the restoration of photosystem II (PSII) function and in the synthesis of the D1 protein at different temperatures after photoinhibition was studied in wild-type cells and a mutant of Synechocystis sp. PCC 6803 with genetically inactivated desaturase genes. We show that posttranslational carboxyl-terminal processing of the precursor form of the D1 protein is an extremely sensitive reaction in the PSII repair cycle and is readily affected by low temperatures. Furthermore, the threshold temperature at which perturbations in D1-protein processing start to emerge is specifically dependent on the extent of thylakoid membrane lipid unsaturation, as indicated by comparison of wild-type cells with the mutant defective in desaturation of 18:1 fatty acids of thylakoid membranes. When the temperature was decreased from 33 degrees C (growth temperature) to 18 degrees C, the inability of the fatty acid mutant to recover from photoinhibition was accompanied by a failure to process the newly synthesized D1 protein, which accumulated in considerable amounts as an unprocessed precursor D1 protein. Precursor D1 integrated into PSII monomer and dimer complexes even at low temperatures, but no activation of oxygen evolution occurred in these complexes in mutant cells defective in fatty acid unsaturation.

Cyanobacteria↗

PubMed1997

Thermal protection of the oxygen-evolving machinery by PsbU, an extrinsic protein of photosystem II, in Synechococcus species PCC 7002.

The evolution of oxygen is the reaction that is the most susceptible to heat in photosynthesis. We showed previously that, in the cyanobacterium Synechococcus sp. PCC 7002, some protein factors located on the thylakoid membranes are involved in the stabilization of this reaction against heat-induced inactivation, and we identified cytochrome C550 as one such factor (Y. Nishiyama, H. Hayashi, T. Watanabe, N. Murata [1994] Plant Physiol 105: 1313-1319). In the present study we purified another protein that appears to be essential for the stabilization of the oxygen-evolving machinery. The purified protein had an apparent molecular mass of 13 kD, and the gene encoding the 13-kD protein was cloned from Synechococcus sp. PCC 7002 and sequenced. The deduced amino acid sequence revealed that the protein was homologous to PsbU, an extrinsic protein of the photosystem II complex, which has been found in thermophilic species of cyanobacteria. Western analysis showed that the level of PsbU in thylakoid membranes was constant, regardless of the growth temperature. Our studies indicate that PsbU, a constituent of the photosystem II complex, protects the oxygen-evolving machinery against heat-induced inactivation.

Amino Acid Sequence↗