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Biomedical subjects

N Murata

Publications and source records attributed to N Murata.

At least 37 records · Page 2Linked to original sources
PubMed2001

Elevated expression of transforming growth factor betas and the tumor necrosis factor family in lung adenocarcinomas induced by N-nitrosobis(2-hydroxypropyl)amine in rats.

Expression of transforming growth factor betas (TGF betas), tumor necrosis factor (TNF) family members, interferons (IFNs), macrophage migration inhibitory factor (MIF) and granulocyte macrophage colony stimulating factor (GM-CSF) in lung adenocarcinomas induced by N-nitrosobis(2-hydroxypropyl)amine (BHP) in rats was investigated using a multiprobe RNase protection assay (RPA) followed by densitometric quantification. Male Wistar rats, 6 weeks of age, were given 2,000 ppm BHP in their drinking water for 12 weeks and maintained without further treatment until killed at week 25. Total RNAs were extracted from 15 adenocarcinomas. Four samples of normal lung tissue from untreated rats served as controls. The expression of TGFbeta1, TGFbeta2, TGFbeta3, TNFalpha, TNFbeta and lymphotoxin beta (Ltbeta) was significantly higher in adenocarcinomas than in normal lung tissues. In contrast, MIF was expressed at the same level in neoplasms and normal tissue and no expression of IFNbeta, IFNgamma and GM-CSF was apparent in either adenocarcinomas or normal lung tissues. These results suggest that elevated expression of TGFbetas and TNF family members may contribute to the development and progression of lung adenocarcinomas induced by BHP in rats.

Adenocarcinoma↗
PubMed2001

Optical study of cytochrome cM formation in Synechocystis.

The expression of the cytM gene, which encodes cytochrome cM in Synechocystis sp. PCC 6803, is induced under stress conditions such as low temperature. Results of spectrophotometric studies revealed that cytochrome cM was oxidized by light absorbed by photosystem I in cells that had acclimatized to a low temperature. However, no similar light-induced oxidation of cytochrome cM was observed in delta cytM mutant cells. The kinetics of the oxidation and reduction of P700 before and after acclimation of Synechocystis cells to low temperature suggested that cytochrome cM might donate electrons to photooxidized P700. Our observations indicate that cytochrome cM is synthesized under low-temperature stress and that it might carry electrons directly to P700+ in photosystem I.

Bacterial Proteins↗
PubMed2001

FHIT alterations in lung adenocarcinomas induced by N-nitrosobis(2-hydroxypropyl)amine in rats.

Alteration of the FHIT gene was investigated in lung adenocarcinomas induced by N-nitrosobis(2-hydroxypropyl) amine (BHP) in male Wistar rats. Animals at 6 weeks of age were given 2000 p.p.m. of BHP in drinking water for 12 weeks, then maintained without further treatment until killed at the end of week 25. A total of 25 lung adenocarcinomas were obtained and total RNAs were extracted from each for assessment of aberrant transcription of the FHIT gene by reverse transcription (RT)-polymerase chain reaction (PCR) analysis. Aberrant transcripts were detected in 15 adenocarcinomas (60%) as absence in the regions of nucleotides (nt) -9 to 279, -98 to 279, -98 to 348 or -98 to 447. Genomic DNAs were also extracted from all 25 adenocarcinomas and exons 5-9 were examined for mutations, using PCR-single strand conformation polymorphism (SSCP) analysis and sequencing. A mutation was detected in only one adenocarcinoma (4%), an ACC to ATC (Thr to IIe) transition at codon 76. Southern blot analysis of eight tumors did not show any evidence of gross rearrangement or deletion of the FHIT gene. Western blot analysis revealed reduced expression of Fhit protein in six out of 10 adenocarcinomas (60%). These results suggest that alteration of the FHIT gene may be involved in the development of lung adenocarcinomas induced by BHP in rats.

Acid Anhydride Hydrolases↗
PubMed2001

Unsaturated fatty acids in membrane lipids protect the photosynthetic machinery against salt-induced damage in Synechococcus.

In this study, the tolerance to salt stress of the photosynthetic machinery was examined in relation to the effects of the genetic enhancement of the unsaturation of fatty acids in membrane lipids in wild-type and desA+ cells of Synechococcus sp. PCC 7942. Wild-type cells synthesized saturated and mono-unsaturated fatty acids, whereas desA+ cells, which had been transformed with the desA gene for the Delta12 acyl-lipid desaturase of Synechocystis sp. PCC 6803, also synthesized di-unsaturated fatty acids. Incubation of wild-type and desA+ cells with 0.5 M NaCl resulted in the rapid loss of the activities of photosystem I, photosystem II, and the Na+/H+ antiport system both in light and in darkness. However, desA+ cells were more tolerant to salt stress and osmotic stress than the wild-type cells. The extent of the recovery of the various photosynthetic activities from the effects of 0.5 M NaCl was much greater in desA+ cells than in wild-type cells. The photosystem II activity of thylakoid membranes from desA+ cells was more resistant to 0.5 M NaCl than that of membranes from wild-type cells. These results demonstrated that the genetically engineered increase in unsaturation of fatty acids in membrane lipids significantly enhanced the tolerance of the photosynthetic machinery to salt stress. The enhanced tolerance was due both to the increased resistance of the photosynthetic machinery to the salt-induced damage and to the increased ability of desA+ cells to repair the photosynthetic and Na+/H+ antiport systems.

Cyanobacteria↗
PubMed2001

Crystallization and preliminary X-ray analysis of the glycerol-3-phosphate 1-acyltransferase from squash (Cucurbita moschata).

Glycerol-3-phosphate 1-acyltransferase (E.C. 2.3.1.15; G3PAT) catalyses the incorporation of an acyl group from either acyl-acyl carrier proteins (acylACPs) or acylCoAs into the sn-1 position of glycerol 3-phosphate to yield 1-acylglycerol 3-phosphate. Crystals of squash G3PAT have been obtained by the hanging-drop method of vapour diffusion using PEG 4000 as the precipitant. These crystals are most likely to belong to space group P2(1)2(1)2(1), with approximate unit-cell parameters a = 61.1, b = 65.1, c = 103.3 A, alpha = beta = gamma = 90 degrees and a monomer in the asymmetric unit. X-ray diffraction data to 1.9 A resolution have been collected in-house using a MAR 345 imaging-plate system.

Acyltransferases↗
PubMed2001

Alterations of the transforming growth factor-beta signaling pathway in hepatocellular carcinomas induced endogenously and exogenously in rats.

To elucidate involvement of the transforming growth factor-beta (TGF-beta) signaling pathway in endogenous and exogenous liver carcinogenesis, we investigated mutations of TGF-beta receptor type II (TGF-betaRII), Smad2 and Smad4 genes, and expression of TGF-betaRII in hepatocellular carcinomas (HCCs) induced by a choline-deficient L-amino acid-defined (CDAA) diet and by N-nitrosodiethylamine (DEN). Male Fischer 344 rats received a CDAA diet continuously and HCCs were sampled after 75 weeks. Administration of DEN was followed by partial hepatectomy (PH), with colchicine to induce cell cycle disturbance and a selection pressure regimen, HCCs being obtained after 42 weeks. Total RNAs were extracted from individual HCCs and mutations in TGF-betaRII, Smad2 and Smad4 were investigated by reverse transcription (RT)-polymerase chain reaction (PCR)-restriction-single-strand conformation polymorphism (SSCP) analysis followed by sequencing analysis. Mutations of Smad2 were detected in 2 out of 12 HCCs (16.7%) induced by the CDAA diet, a GGT-to-GGC transition (Gly to Gly) at codon 30 and a TCT-to-GCT (Ser to Ala) transversion at codon 118, without any TGF-betaRII or Smad4 alterations. No mutations of TGF-betaRII, Smad2 and Smad4 were encountered in eleven HCCs induced by the exogenous carcinogen. Semi-quantitative RT-PCR revealed reduced expression of TGF-betaRII in 2 HCCs (16.7%) without Smad2 mutations out of 12 HCCs induced by the CDAA diet and none of 11 induced by DEN. These results suggest that the TGF-beta signaling pathway may be disturbed in endogenous liver carcinogenesis in rats.

Alkylating Agents↗
PubMed2001

Functional expression in Escherichia coli of low-affinity and high-affinity Na(+)(Li(+))/H(+) antiporters of Synechocystis.

Synechocystis sp. strain PCC 6803 has five genes for putative Na(+)/H(+) antiporters (designated nhaS1, nhaS2, nhaS3, nhaS4, and nhaS5). The deduced amino acid sequences of NhaS1 and NhaS2 are similar to that of NhaP, the Na(+)/H(+) antiporter of Pseudomonas aeruginosa, whereas those of NhaS3, NhaS4, and NhaS5 resemble that of NapA, the Na(+)/H(+) antiporter of Enterococcus hirae. We successfully induced the expression of nhaS1, nhaS3, and nhaS4 under control of an Na(+)-dependent promoter in Escherichia coli TO114, a strain that is deficient in Na(+)/H(+) antiport activity. Inverted membrane vesicles prepared from TO114 nhaS1 and TO114 nhaS3 cells exhibited Na(+)(Li(+))/H(+) antiport activity. Kinetic analysis of this activity revealed that nhaS1 encodes a low-affinity Na(+)/H(+) antiporter with a K(m) of 7.7 mM for Na(+) ions and a K(m) of 2.5 mM for Li(+) ions, while nhaS3 encodes a high-affinity Na(+)/H(+) antiporter with a K(m) of 0.7 mM for Na(+) ions and a K(m) of 0.01 mM for Li(+) ions. Transformation of E. coli TO114 with the nhaS1 and nhaS3 genes increased cellular tolerance to high concentrations of Na(+) and Li(+) ions, as well as to depletion of K(+) ions during cell growth. To our knowledge, this is the first functional characterization of Na(+)/H(+) antiporters from a cyanobacterium. Inverted membrane vesicles prepared from TO114 nhaS4 cells did not have Na(+)/H(+) antiport activity, and the cells themselves were as sensitive to Na(+) and Li(+) ions as the original TO114 cells. However, the TO114 nhaS4 cells were tolerant to depletion of K(+) ions. Taking into account these results and the growth characteristics of Synechocystis mutants in which nhaS genes had been inactivated by targeted disruption, we discuss possible roles of NhaS1, NhaS3, and NhaS4 in Synechocystis.

Amino Acid Sequence↗
PubMed2001

[Tumoral levels of thymidine phosphorylase and dihydropyrimidine dehydrogenase in elderly colorectal cancer patients].

Fluoropyrimidine therapy for elderly colorectal cancer patients remains controversial. Tumoral levels of thymidine phosphorylase (TP), dihydropyrimidine dehydrogenase (DPD), and the ratio of TP to DPD determined by an enzyme-linked immunosorbent assay were compared between colorectal cancer patients aged 75 or over (elderly group, n = 25) and those 74 years or less (control group, n = 87), in order to examine the characteristics of colorectal cancers in the elderly from the viewpoint of metabolic and anabolic pathways of fluoropyrimidines. The level of TP was 78.4 +/- 47.0 unit/mg protein in the elderly group and 82.4 +/- 70.9 unit/mg protein in the control group (p = 0.86). The level of DPD was 53.7 +/- 43.1 unit/mg protein in the elderly group and 52.6 +/- 37.7 unit/mg protein in the control group (p = 0.73). The ratio of TP to DPD was 2.0 +/- 1.2 in the elderly group and 1.8 +/- 0.9 in the control group (p = 0.44). These three parameters did not differ between the groups when divided according to Dukes' stage (Dukes' A.B versus Dukes' C.D). These results suggest that there are no age-specific characteristics in relation to conversion of fluoropyrimidines such as capecitabine and doxifluridine to 5-fluorouracil (FU) and degradation of 5-FU in colorectal cancers.

Age Factors↗
PubMed2001

Preferential and persistent activation of the STAT1 pathway in rheumatoid synovial fluid cells.

OBJECTIVE: Inflammatory cytokines such as interleukin 1 (IL-1), IL-6, and tumor necrosis factor-alpha are produced in great quantities in inflamed rheumatoid joints. However, little is known about the pathogenic significance of each cytokine in the proliferative synovitis and destruction of bone and joint. We investigated the role of cytokine receptor signals transduced into cells at the foci of rheumatoid inflammation. METHODS: Synovial fluid (SF) cells from patients with rheumatoid arthritis (RA) and osteoarthritis (OA) were examined for the activation of a group of cytokine receptor signaling molecules, signal transducers and activators of transcription (STAT). RESULTS: DNA binding of STAT1 in SF cells was observed in 8 out of 14 patients with RA, but in none of the 10 patients with OA studied, and this was prevented by preincubation of these cells with neutralizing anti-IL-6 antibody. IL-6 activated both STAT1 and STAT3 in normal peripheral blood (PB) leukocytes, and preferentially STAT1 in rheumatoid SF cells. Moreover, STAT1 activation in rheumatoid SF cells appeared to be continuous, in contrast to the transient activation in normal PB leukocytes. CONCLUSION: STAT1 and STAT3 are differentially regulated in response to IL-6 in different cell types. The continuous STAT1 activation may be of pathogenic significance in the progression and persistence of RA.

Adult↗
PubMed2001

[Effect of peroral doxifluridine plus hepatic arterial infusion for synchronous liver metastasis of colorectal cancer--correlation with the expression of thymidine phosphorylase and dihydropyrimidine dehydrogenase in primary colorectal cancer lesions].

We investigated whether the efficacy of peroral doxifluridine and hepatic arterial 5-FU infusion on synchronous liver metastasis of colorectal cancer could be predicted based on the expression of thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD) in the primary colorectal lesions. Ten patients with synchronous liver metastasis of colorectal cancer were given doxifluridine (600-800 mg/body/day) orally and 5-FU (500 mg/body, once or twice a week) through the hepatic artery following resection of the primary lesions between June 1996 and July 2001. The levels of TP and DPD in the primary lesions were determined by an enzyme-linked immunosorbent assay. The level of TP, DPD, and the ratio of TP/DPD in patients with partial response (n = 4) were 89.8 +/- 30.0 U/mg protein, 23.5 +/- 25.7 U/mg protein, and 3.8 +/- 1.4, respectively, while those in patients with no response or progressive disease (n = 6) were 41.8 +/- 9.7 U/mg protein, 25.8 +/- 15.8 U/mg protein, and 2.2 +/- 1.6, showing significant difference (p < 0.01) in the level of TP between the groups. These results indicate that determining the level of TS in primary colorectal lesions may be useful for predicting the efficacy of this regimen for patients with synchronous liver metastasis of colorectal cancer.

Aged↗
PubMed2001

[A case of pseudomyxoma peritonei with a pancreatic cancer treated by the intraperitoneal administration of cisplatinum].

A 55-year-old woman underwent laparotomy with a diagnosis of pseudomyxoma peritonei associated with a pancreatic cancer. The peritoneal cavity was filled with much gelatinous material, which was removed as much as possible by suction and by hand. Distal pancreatectomy, appendectomy and bilateral oophorectomy were performed. The peritoneal cavity was washed by saline and 5% glucose solution followed by dispersion of 100 mg of cisplatinum. The intraperitoneal chemotherapy was performed once every two weeks after the operation through an indwelling catheter. Histological examination revealed a mucinous cystadenocarcinoma of the pancreas, causing pseudomyxoma peritonei. The patient is in a good health 4 years after the operation.

Adenocarcinoma↗
PubMed2001

[Histological evaluation of liver metastasis of colorectal cancer following hepatic arterial infusion with degradable starch microspheres and adriamycin/mitomycin C].

Little is known about the histological effect of hepatic arterial infusion with degradable starch microspheres (DSM), adriamycin (ADM), and mitomycin C (MMC) on liver metastasis of colorectal cancer. We histologically examined hepatic metastases resected following this therapy and investigated their relation to macroscopic changes in size. Neither a histological nor macroscopic effect was found in 2 patients receiving this therapy only one time. A 57-year-old woman with a solitary liver metastasis who received this therapy repeatedly (five times every 3 to 4 weeks) subsequently showed a partial response. She underwent hepatic metastasectomy 5 months after the end of the therapy. Histological examination showed that the greater part of the metastatic lesion was composed of fibrous tissues without any viable cancer cells. In conclusion, it should be noted that repeated infusions of DSM.ADM.MMC for liver metastases of colorectal cancer can have a marked histological effect even though the lesion does not show a complete response.

Aged↗
PubMed2000

Membrane dynamics as seen by fourier transform infrared spectroscopy in a cyanobacterium, Synechocystis PCC 6803. The effects of lipid unsaturation and the protein-to-lipid ratio.

The roles of lipid unsaturation and lipid-protein interactions in maintaining the physiologically required membrane dynamics were investigated in a cyanobacterium strain, Synechocystis PCC 6803. The specific effects of lipid unsaturation on the membrane structure were addressed by the use of desaturase-deficient (desA(-)/desD(-)) mutant cells (which contain only oleic acid as unsaturated fatty acid species) of Synechocystis PCC 6803. The dynamic properties of the membranes were determined from the temperature dependence of the symmetric CH(2) stretching vibration frequency, which is indicative of the lipid fatty acyl chain disorder. It was found that a similar membrane dynamics is maintained at any growth temperature, in both the wild-type and the mutant cell membranes, with the exception of mutant cells grown at the lower physiological temperature limit. It seems that in the physiological temperature range the desaturase system of the cells can modulate the level of lipid desaturation sufficiently to maintain similar membrane dynamics. Below the range of normal growth temperatures, however, the extent of lipid disorder was always higher in the thylakoid than in the cytoplasmic membranes prepared from the same cells. This difference was attributed to the considerable difference in protein-to-lipid ratio in the two kinds of membranes, as determined from the ratio of the intensities of the protein amide I band and the lipid ester C&z.dbnd6;O vibration. The contributions to the membrane dynamics of an ab ovo present 'structural' lipid disorder due to the protein-lipid interactions and of a thermally induced 'dynamic' lipid disorder could be distinguished.

Cell Membrane↗
PubMed2000

Interaction of sphingosine 1-phosphate with plasma components, including lipoproteins, regulates the lipid receptor-mediated actions.

The concentration of sphingosine 1-phosphate (S1P) in plasma or serum is much higher than the half-maximal concentration of the sphingolipid needed to stimulate its receptors. Nevertheless, the inositol phosphate response to plasma or serum mediated by Edg-3, one of the S1P receptors, which was overexpressed in Chinese hamster ovary cells, was much smaller than the response expected from the total amount of S1P in these samples. The inositol phosphate response to exogenous S1P was markedly attenuated in the presence of charcoal-treated low-S1P serum. The inhibitory effect was lost by boiling but not by dialysis of the serum. The inhibitory action of the serum was specific to S1P and was associated with the trapping of exogenous S1P; the inositol phosphate response to P(2)-purinergic agonists was somewhat enhanced by the charcoal-treated serum. Among the components of plasma or serum, lipoproteins such as low-density and high-density lipoproteins showed a stronger activity for trapping S1P than lipoprotein-deficient serum. Consistent with this observation, we detected a 15-100-fold higher amount of S1P per unit amount of protein in lipoproteins than in the lipoprotein-deficient serum. Thus even though the protein content of the lipoprotein fraction contributes to only 4% of the total protein content of plasma or serum, more than 60% of S1P is distributed in this fraction. These results suggest that the tight binding of S1P to the components of serum or plasma, including lipoproteins, may interfere with the S1P binding to its receptors and thereby attenuate the lipid-receptor-mediated actions in the cells.

Animals↗
PubMed2000

Regulation of enzymatic activity and gene expression by membrane fluidity.

Changes in the cellular environment can lead to alterations in the fluidity of the membranes of prokaryotes and eukaryotes. Changes in temperature and osmotic conditions are two of the best-studied stresses that can affect membrane fluidity. Los and Murata discuss the types of sensors that detect these changes in membrane fluidity and the types of signals that are generated.

Animals↗
PubMed2000

Mutations of adenomatous polyposis coli and beta-catenin genes during progression of lung tumors induced by N-nitrosobis(2-hydroxypropyl)amine in rats.

In the present study, we investigated mutations of the adenomatous polyposis coli (APC) and beta-catenin genes to clarify possible molecular mechanisms underlying development of lung tumors induced by N-nitrosobis(2-hydroxypropyl)amine (BHP) in rats. Male Wistar rats, 6 weeks of age, were given 2000 ppm BHP in drinking water for 12 weeks and then maintained without further treatment until sacrifice at week 25 DNA was extracted from paraffin-embedded tissues, and PCR-single-strand conformation polymorphism analysis, followed by nucleotide sequencing, was performed. No APC mutations were detected in 17 hyperplasias, but 2 of 15 adenomas (13.3%) and 8 of 20 adenocarcinomas (40.0%) showed changes within exon 1 to the mutation cluster region in exon 15. For beta-catenin, no mutations were detected in 17 hyperplasias, but 3 of 15 adenomas (20.0%) and 5 of 20 adenocarcinomas (25.0%) had alterations within or flanking codons corresponding to important phosphorylation sites. Immunohistochemical staining showed beta-catenin protein localized in the cell membranes in the surrounding normal-appearing lung and 216 hyperplasias and localized mainly in the cytoplasm and/or nucleus in 10 of 37 adenomas (27.0%) and 21 of 40 adenocarcinomas (52.5%). These results suggest that the APC-beta-catenin-T-cell factor signaling pathway is involved in the acquisition of growth advantage from adenomas to adenocarcinomas in BHP-induced rat lung carcinogenesis.

Adenocarcinoma↗