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K Saeki

Publications and source records attributed to K Saeki.

At least 91 records · Page 5Linked to original sources
PubMed1999

Mutagenicity of 4-nitroquinoline 1-oxide in the MutaMouse.

As part of a collaborative study, the Mammalian Mutagenesis Study Group (MMS), a sub-organization of the Environmental Mutagen Society of Japan (JEMS) conducted mutagenicity tests in MutaMouse. Using a positive selection method, we studied the organ-specificity and time dependence of mutation induction by 4-nitroquinoline 1-oxide (4NQO). A single dose of 4NQO was administered intraperitoneally (7.5 or 15 mg/kg) or orally (200 mg/kg) to groups of male mice. On days 7, 14 and 28 after treatment, we isolated the liver, kidney, lung, spleen, bone marrow, testis and stomach in the intraperitoneal administration experiment and the liver, lung, bone marrow, testis and stomach in the oral administration experiment. In addition, we performed the peripheral blood micronucleus test to evaluate clastogenicity. In the mice treated intraperitoneally at 7.5 mg/kg, we found increased mutant frequency (MF) only in the lung, where the MF did not vary with expression time. In the mice treated at 15 mg/kg, we found increased MF in the liver, bone marrow and lung. In orally treated mice, the MF was high in the lung and liver and very high in the bone marrow and stomach while the increase in the testis was negligible. As the expression time was prolonged, the MF tended to increase in the liver, decrease in the bone marrow, and remain stable in the lung, testis and stomach. The incidence of micronucleus induction in peripheral blood cells was significantly increased (p<0.01) in the 4NQO groups when compared with the vehicle control group by intraperitoneal treatment. Thus, these assay systems appeared to be of use in detecting not only genetic mutation but also chromosomal aberration.

4-Nitroquinoline-1-oxide↗
PubMed1999

Substituent effect of a fluorine atom on the mutagenicity of nitroquinolines.

Some 16 nitroquinolines (NQs) and their fluorinated derivatives were tested for mutagenicity in Salmonella typhimurium TA100 without S9 mix to investigate the effect of fluorine-substitution on the mutagenicity. These NQs consist of 5-NQs, 5-nitroquinoline N-oxides (5-NQOs), N-methyl-5-nitroquinolinium methanesulfonates (N-Me-5-NQs) and 8-NQs, including three ortho-F-NQs, one meta-F-NQ, four para-F-NQs and four 3-F-NQs. For this purpose, eight F-NQs were newly synthesized. The data indicated that the ratio of the mutagenic activities (revertants/plate/nmol) of fluorinated NQs to those of the corresponding parent non-fluorinated compounds ranged from 0.6- to 119-fold. The fluorine atom located para to the nitro group markedly enhanced the mutagenicity (24-fold and more), while three ortho-fluorinated derivatives showed no significant increase in mutagenicity (enhancement ratio were 0.6, 0.8 and 1.7). With respect to 8-NQs, its meta-fluorinated derivative also had an enhanced mutagenicity over the parent compound (53-fold). In addition, although N-Me-5-NQ was less mutagenic than 5-NQ and 5-NQO, the mutagenicity of N-Me-5-NQ was most significantly enhanced by fluorine-substitution. These results suggest that introduction of a fluorine atom to the molecule in question may be a useful tool to modify their mutagenic potency and to better understand the mechanism of mutation.

Chromatography, Gel↗
PubMed1999

Multiple alternative transcripts of the human homologue of the mouse TRAD/R51H3/RAD51D gene, a member of the rec A/RAD51 gene family.

Yeast RAD51, a homologue of Escherichia coli recA, plays a crucial role in mitotic and/or meiotic recombination and in the repair of double-strand DNA breaks. We have identified unique multiple alternative transcripts of a human TRAD/R51H3/RAD51D gene, a member of the recA/RAD51 gene family. One of the transcripts encoded a 328-amino-acid protein with 83.0% overall amino acid identity and 98. 2% similarity with the mouse TRAD gene and had two nucleotide binding consensus sequences, motif A and motif B, conserved among members of this family. Other transcripts encoded truncated proteins with a partial N-terminal region of the orthologue or short proteins lacking internal sequences which contain nucleotide binding motifs. Northern blot analysis revealed that multiple transcripts of the human TRAD gene were expressed in various tissues and their distribution was not ubiquitous.

Alternative Splicing↗
PubMed1999

Effects of oligofluorine substitution on the mutagenicity of quinoline: a study with twelve fluoroquinoline derivatives.

A total of 12 variously fluorinated derivatives of quinoline (Q) were tested for their mutagenicity in Salmonella typhimurium TA100 in the presence of S9 mix to investigate the structure-mutagenicity relationship in oligofluorinated quinolines. Nine of them, 3,7-di-, 5,6-di-, 6,7-di-, 6,8-di-, 7,8-di-, 3,5,7-tri-, 5,6,8-tri-, 6,7, 8-tri-, and 5,6,7,8-tetrafluoroquinolines (FQs), were newly synthesized for this purpose. Those fluorinated at position 3 were all non-mutagenic. Mutagenicity was enhanced by fluorine-substitution at position 5 or 7, but not in 3-FQs (i.e., 3, 5-di-, 3,7-di-, and 3,5,7-triFQs). Some of the 6-fluorinated derivatives showed less maximum induced-revertants with more mutagenic potencies in terms of induced-revertants per dose than quinoline. No marked change occurred by fluorine-substitution at position 8. These results show that the effect of di- and trifluoro-substitution on mutagenicity is generally additive, while that of tetrafluorination approaches the deactivating effect of perfluorination. Our study suggests that 3-fluorine-substitution in the pyridine moiety may be a useful means of antimutagenic structural modification in pyridine-fused aromatic chemicals for medicinal and agricultural use.

Animals↗
PubMed1999

Cell-cycle-regulated phosphorylation of cAMP response element-binding protein: identification of novel phosphorylation sites.

We report that the cAMP response element binding protein (CREB) undergoes cell-cycle-regulated phosphorylation. In human amnion FL cells, CREB was expressed as two forms with different molecular masses, 45 and 45.5 kDa. Although asynchronous cells contained predominantly the 45 kDa forms, this form shifted to 45.5 kDa when the cells were synchronized with the early S-phase. Furthermore the expression of the 45.5 kDa band was increased when cells were treated with okadaic acid, confirming that the 45.5 kDa band was a phosphorylated form of the 45 kDa band. Mutation analysis indicated that neither Ser133, the target of cAMP-dependent protein kinase and calcium calmodulin kinase, nor Ser129, the target of glycogen synthetase kinase 3, was responsible for the expression of the 45.5 kDa band, but that Ser108, Ser111 and Ser114, located in a region matching the consensus sequence for the casein kinase II target, were required. A mutant in which Ser111 and Ser114 were each replaced by a glutamic residue, mimicking a phosphorylated state, had a higher activation potential in cAMP response element-mediated transcription. These results strongly suggest that the casein kinase II target region is involved in cell cycle-regulated phosphorylation of the CREB protein and also in transcriptional enhancement.

Amino Acid Sequence↗
PubMed1999

Influences of copper forms on the toxicity to microorganisms in soils.

Soil samples with wide ranges of pH (4.9 to 8.1), organic carbon (0.1 to 77%), and total Cu contents from 32 to 11700 mg kg(-1), collected near a copper mine, were used to investigate the relationships between microbial features and Cu speciation in order to clarify the form(s) of Cu adversely affecting microorganisms. The effects of Cu on soil microorganisms were evaluated by two indicators: the ratio of microbial biomass carbon to soil organic carbon (Cmic/Org-C) and Cu tolerance level of bacterial community (IC50). The sequential extraction scheme of McLaren and Crawford (1973) was used to quantify the different Cu forms (soluble and exchangeable, specifically adsorbed, and organically bound). These influences were investigated using simple correlation analysis, multiple regression analysis, and principal component analysis. The IC50 was positively correlated with the log concentration of soluble and exchangeable Cu (Ex-Cu) (r = 0.757, P<0.01). The IC50 value was also influenced by the amount of specifically adsorbed Cu. The Cmic/Org-C ratio was not significantly correlated with any Cu forms. Thus, other soil properties had more influence on the size of microbial biomass carbon in the soils used. The amount of Ex-Cu exerting high toxicity was affected by pH and the amount of total Cu.

Carbon↗
PubMed1999

Usefulness of the sensitivity-resistance index to estimate the toxicity of copper on bacteria in copper-contaminated soils.

Examination was made of the fluctuations of numbers of the total bacteria and copper (Cu)-resistant bacteria with soluble/exchangeable Cu (Ex-Cu) fraction in three types of soils spiked with Cu at four concentrations. Drastic increase in Cu-resistant bacteria was observed in three soils spiked with 20 mmol Cu kg(-1) after 2 weeks of incubation, indicating the strong selection of individuals originally resistant to Cu. Adaptation and proliferation of bacteria were also observed in the soil environment under the long-term exposure to extremely high concentration of Cu (800 mg kg(-1) soil of Ex-Cu), deriving from the development of Cu resistance. These bacterial fluctuations and the toxic effects of Cu depended on soil types, due to the chemical forms in which Cu occurs. It was also found that the ratio of Cu-resistant bacterial number to total bacteria was significantly correlated with the amount of Ex-Cu in the soils. This sensitivity-resistance index seems to be useful for evaluating the toxic effects of Cu on the soil bacterial community. Whereas the toxicity of Cu depended on the soil properties, they also changed with time. This phenomenon can be explained by the decrease in the most labile Cu phase, Ex-Cu, with time in the soils.

Adaptation, Physiological↗
PubMed1999

Increase in histidine decarboxylase activity in tissues of mice bearing Colon-26 tumor cells.

The changes in histidine decarboxylase (HDC) activity, histamine and tele-methylhistamine contents were examined in tissues of mice after the inoculation of Colon-26 tumor cells subcutaneously into the lower back. The HDC activity in the spleen of mice increased significantly 14 days after the inoculation of Colon-26 and the increase in HDC activity continued for up to 28 days. However, the histamine content in the spleen of tumor-bearing mice was not changed significantly during the observation period. In the following experiments, two subclones of the Colon-26 cell line, cachexia-inducing clone-20 and non cachexia-inducing clone-5, were used and the induction of HDC activity in mice was examined in four tissues, spleen, lung, liver and kidney. Both clone-20 and clone-5 induced the increase in HDC activity to the same extent in the spleen and lung, but not in the liver and kidney. As observed using the Colon-26 original cell line, the histamine contents in the four tissues of tumor-bearing mice were not different from those in the control mice. In contrast, the levels of tele-methylhistamine, one of the major catabolites of histamine, in the tumor-bearing mice increased significantly compared with the control mice in all four tissues examined. There was a correlation between the increase in tele-methylhistamine level and the increase in HDC activity in the tissues. A histological study indicated that the tissue mast cells were not increased in spleen and lung of tumor-bearing mice. These findings indicated that the increase in HDC activity in the spleen and lung occurred in parallel with the growth of inoculated tumor cells in mice and suggested that the cells other than mast cells may be involved in the increase in HDC activity. The tumor-bearing state produced histamine with a high turnover rate in the mouse tissues, especially in the spleen and lung.

Adenocarcinoma↗
PubMed1999

Vanadium accumulation in pinnipeds.

Vanadium in four species of pinnipeds (northern fur seals [Callorhinus ursinus], Steller sea lions [Eumetopias jubatus], harbor seals [Phoca vitulina], and ribbon seals [Phoca fasciata]) caught in the Northern Pacific was analyzed using ICP-MS to understand its accumulation and distribution. In northern fur seals, relatively high concentrations of vanadium were observed in the liver, hair, and bone. Ninety percent of the vanadium burden in the body was concentrated in these three tissues, which comprise <20% of total body weight. Hepatic vanadium concentrations in the four pinniped species were significantly correlated to age, although the levels varied with species. An increase in vanadium accumulation in the liver of northern fur seals was caused by an increase of retention in nuclei and mitochondria fraction in the cells. Vanadium concentrations in liver were significantly correlated with mercury, silver, and selenium concentrations in northern fur seals, Steller sea lions, and harbor seals.

Alaska↗
PubMed1999

Difference in Bgp-independent fusion activity among mouse hepatitis viruses.

Mouse hepatitis virus (MHV) utilizes a mouse biliary glycoprotein (Bgp) as a receptor. Co-cultivation of MHV-nonpermissive hamster BHK cells devoid of mouse Bgp with mouse DBT cells infected with MHV-A59 or JHMV induces syncytia formation on BHK cells (Bgp-independent fusion). This study shows the difference in Bgp-independent fusion activity among various MHV strains. Under a phase contrast microscopy, JHMV (cl-2, sp-4) induced the Bgp-independent syncytia on BHK cells similar to those observed on DBT cells, while such syncytia were not seen with the infection of other MHV strains (MHV-1, MHV-3, MHV-A59, MHV-S, srr7, srr11 and srr18). Tiny syncytia detectable only by immunofluorescence were produced with the latter MHV strains except for srr7 which failed to produce syncytia. MHVs except for srr7 grew in BHK cells after Bgp-independent infection. The Bgp-independent fusion by JHMV was inhibited either by anti-S1 or anti-S2 antibodies. These results showed that the JHMV spike protein had a remarkably high Bgp-independent fusion activity.

Animals↗
PubMed1999

Existence of acyl-CoA hydrolase-mediated pathway supplying arachidonic acid for prostaglandin synthesis in microsomes from rabbit kidney medulla.

We have previously shown that acyl-coenzyme A (CoA) hydrolase that hydrolyzes arachidonoyl-CoA (AA-CoA) to arachidonic acid (AA) and CoA is present in the cytosol of rabbit kidney medulla and that this enzyme can supply AA for prostaglandin (PG) synthesis in this region. In the present study, the existence of the acyl-CoA hydrolase-mediated pathway that supplies AA available for PG synthesis in microsomes from the kidney medulla was examined. AA-CoA (20 microM) was preincubated with the 105,000 g pellet (microsomes, 0.5 mg of protein) from the medulla for 5 min at 37 degrees C followed by incubation with the medulla microsomes (0.5 mg of protein) (the source of PG synthesizing enzymes) in the presence of hydroquinone and reduced glutathione for 5 min at 37 degrees C. The PGs formed were measured by high-pressure liquid chromatography using 9-anthryldiazomethane for derivatization. The addition of the microsomal fraction from the medulla in the preincubation mixture increased total PG formation from 3.86 to 8.70 nmol, and this stimulatory effect was somewhat weaker than that of the cytosolic fraction. On the other hand, the microsomal fraction in the kidney cortex has an extremely lower capacity to supply AA for PG synthesis than do medulla microsomes. These results suggest that, in kidney medulla, the microsomes as well as the cytosol have the potential route that supplies AA from AA-CoA for PG synthesis and that this pathway is mediated by acyl-CoA hydrolase.

Acyl Coenzyme A↗
PubMed1999

Signal transduction pathways in normal human monocytes stimulated by cytokines and mediators: comparative study with normal human neutrophils or transformed cells and the putative roles in functionality and cell biology.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL) -3 induced tyrosine phosphorylation of 92-kDa protein in normal human monocytes. We identified this 92-kDa protein as STAT5, but not as STATs1, 3, and 6 nor c-fes and vav protooncogene products, and demonstrated its translocation to the nucleus, enhancement of specific DNA binding capacity, and potentiation of trancriptional activity by GM-CSF. N-formyl-methionyl-leucyl-phenylalanine (FMLP) and phorbol myristate acetate (PMA) induced tyrosine phosphorylation of 42- and 44-kDa proteins, which were identified as extracellular signal-regulated kinase (ERK), in human monocytes. In marked contrast to neutrophils and MO7e cells, GM-CSF did not induce tyrosine phosphorylation and activation of ERK in monocytes. Among upstream signaling molecules of ERK, Shc was constitutively associated with Grb2 and was not tyrosine-phosphorylated by GM-CSF and FMLP, and Sos1 and c-Raf-1 were not phosphorylated by GM-CSF, IL-3, TNF, and FMLP in monocytes, whereas all these signaling molecules were affected and/or utilized by GM-CSF in MO7e cells. In contrast to neutrophils, p38 was constitutively phosphorylated and agonist-dependent phosphorylation and activation was not detected in human monocytes. Superoxide release stimulated by FMLP was inhibited partially by PD98059 or SB203580, a specific inhibitor of ERK or p38 pathway, and was almost completely inhibited by the combination of both inhibitors, whereas PMA-induced superoxide release was resistant to these two inhibitors in monocytes. PD98059 inhibited GM-CSF-dependent proliferation of MO7e cells. Present results indicate trancriptional roles of STAT5 and functional roles of ERK and/or p38 in normal human monocytes stimulated by physiological receptor-mediated agonists GM-CSF and FMLP. Possible roles of ERK in proliferation of transformed cells were also suggested.

Adult↗
PubMed1999

Pharmacokinetic differences between rat tumour and lung tissues following isolated lung perfusion with cisplatin.

Isolated lung perfusion has been performed for the treatment of unresectable lung tumours; however, the pharmacokinetics of this procedure remain unclear. This study was conducted to investigate the changes in antitumour drug concentrations in tumour and lung tissues after isolated lung perfusion, using different perfusion times and perfusate drug concentrations. Isolated left lungs were perfused for 20, 40 or 60 min with 25, 50 or 100 micrograms/ml of cisplatin after solitary lung tumour nodules were established in rats, and the total platinum concentrations in the perfused lung and tumour tissues were determined by flameless atomic absorption spectroscopy. The oedema in the perfused lung tissues was evaluated by histological examination and by the wet to dry weight ratios of the lungs. The total platinum concentration increased significantly with perfusion time and increasing perfusate cisplatin concentrations in the lung tissue, but it did not change in the tumour tissue. The wet to dry weight ratios of the lung tissues did not differ significantly among the perfusion groups. Oedema of the perfused lung tissue did not change significantly with the perfusion time or perfusate cisplatin concentration. The results of this study indicate the possibility that different pharmacokinetics exist between tumour and lung tissues following isolated lung perfusion with cisplatin, which could be used as a clinical guide for the selection of appropriate perfusion times and perfusate drug concentrations.

Animals↗
PubMed1999

Inhibitory effects of tetragalloylglucose and digalloylhamamelose on adhesion and in vitro invasion of mouse lung carcinoma cells.

Tetragalloylglucose (TgG) and digalloylhamamelose (DgH) were found to inhibit adhesion to and invasion through Matrigel of mouse Lewis lung carcinoma LL2-Lu3 cells, which are highly metastatic. TgG inhibited matrix metalloproteinases (MMPs) from the tumor cells like (-)-epigallocatechin gallate, whereas DgH did not. These results suggest that TgG and DgH inhibit tumor cell invasion by inhibiting MMPs and/or cell adhesion of the tumor cells.

Animals↗
PubMed1999

Effect of 13-hydroperoxyoctadecadienoic acid on the supply of arachidonic acid for prostaglandin synthesis from arachidonoyl-CoA mediated by the cytosolic or microsomal acyl-CoA hydrolase in rabbit kidney medulla.

The effects of 13-hydroperoxyoctadecadienoic acid (13-HPODE) on the cytosolic or microsomal acyl-CoA hydrolase (ACH) activity in rabbit kidney medulla and on the ACH-mediated prostaglandin (PG) formation from arachidonoyl-CoA (AA-CoA) were examined. 13-HPODE (10, 20, and 50 microM) had no effect on the cytosolic ACH activity but significantly inhibited the activity of the microsomal enzyme (43-57% inhibition). PG formation was measured as follows: AA-CoA (20 nmol) was preincubated with the cytosolic or microsomal fraction (as the source of ACH) in the presence or absence of 13-HPODE for 5 min at 37 degrees C, followed by incubation with the microsomal fraction (as the source of PG-synthesizing enzymes), hydroquinone and reduced glutathione for 5 min at 37 degrees C, and the PGs formed were measured by HPLC, with use of 9-anthryldiazomethane for derivatization. 13-HPODE reduced the PG formation when the microsomal fraction, but not the cytosolic fraction, was used as the source of ACH (10, 20, and 50 microM; 28-55% inhibition). These results suggest that 13-HPODE may modulate PG levels in rabbit kidney medulla by inhibiting the microsomal ACH activity.

Acyl Coenzyme A↗
PubMed1999

Hyperproduction of recombinant ferredoxins in escherichia coli by coexpression of the ORF1-ORF2-iscS-iscU-iscA-hscB-hs cA-fdx-ORF3 gene cluster.

Fe-S proteins acquire Fe-S clusters by an unknown post-translational mechanism. To study the in vivo synthesis of the Fe-S clusters, we constructed an experimental system to monitor the expressed ferredoxin (Fd) as a reporter of protein-bound Fe-S clusters assembled in Escherichia coli. Overexpression of five Fds in a T7 polymerase-based system led to the formation of soluble apoFds and mature holoFds, indicating that assembly of the Fe-S cluster into apoFd polypeptides is a rate-limiting step. We examined the coexpression of the E. coli ORF1-ORF2-iscS-iscU-iscA-hscB-hsc A-fdx-ORF3 gene cluster, which has recently been suggested to be involved in the formation or repair of Fe-S protein [Zheng, L., Cash, V.L., Flint, D.H., and Dean, D.R. (1998) J. Biol. Chem. 273, 13264-13272], with reporter Fds using compatible plasmids. The production of all five reporter holoFds examined was dramatically increased by the coexpression of the gene cluster, and apparent specificity to the polypeptides or to the type of Fe-S clusters was not observed. The increase in holoFd production was observed under the coexpression conditions in all culture media examined, with either 2 x YT medium or Terrific broth, and with or without supplemental cysteine or iron. These results indicate that the proteins encoded by the gene cluster are involved in the assembly of the Fe-S clusters in a wide variety of Fe-S proteins.

Carbon-Sulfur Lyases↗