Classic lipid nutrition for the prevention of chronic, elderly-onset diseases was apparently established before 1960, assuming that hypercholesterolemia is the major risk factor and that raising the polyunsaturated/saturated (P/S) ratio of dietary fatty acids is hypocholesterolemic. However, the hypocholesterolemic effect of linoleic acid (LA) was found to be transient. Furthermore, hypercholesterolemia itself is unlikely to be a serious risk factor for diseases in the elderly because serum cholesterol level is positively correlated with longevity. Instead, a high n-6/n-3 ratio of dietary fatty acids was found to increase thrombotic tendency, decrease peripheral blood flow and lead to persistent inflammation, which was proposed to be the major risk factor for atherosclerosis and related diseases. Based on animal experiments and epidemiological studies, we recommend a reduction in the intake of LA from a current value of >6 en% to half, and a reduced n-6/n-3 ratio from the current value of >4 to 2. Simply decreasing LA intake would produce the recommended n-6 and n-3 fatty acid balance in Japan due to the typical Japanese diet, but both decreasing the intake of LA and increasing that of n-3 fatty acids, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), is necessary in Western industrialized countries for the effective prevention of atherosclerosis and related diseases, as well as of apoplexy, allergic hyper-reactivity and cancers typical in Western populations.
Two isoforms of brain ankyrin, 440kD and 220kD ankyrinB, are generated from the same gene by alternative splicing of pre-mRNA. The larger isoform shares the same NH2-terminal and COOH-terminal domains as the smaller isoform and contains, in addition, a unique inserted domain of about 220kD in size. Both isoforms were expressed in primary neurons in a manner similar to that in vivo ; the larger isoform appeared first when axogenesis is actively conducted and the smaller isoform appeared later. 440kD ankyrinB was localized in the axons of neurons both in vivo and in vitro, while the 220kD isoform was rather localized in the cell bodies and dendrites of neurons. The expression of 440kD ankyrinB is intimately associated not only with neurite outgrowth but also with neurite retraction in neuronal cells, and is regulated at the mRNA level. Therefore, 440kD ankyrinB is a specific and useful marker for neuritogenesis and is also a useful tool for investigating the effects of neurotoxic substances like methylmercury on the developing nervous system.
This review describes our studies on the toxic effects of methylmercury (MeHg) at cellular levels using neuroblastoma, PC12, glioma and HeLa cell lines. MeHg specifically disrupted microtubules and inhibited cell growth by halting the cell cycle at the M phase. Effects on DNA, RNA and protein syntheses were not associated with growth inhibition by MeHg. Microtubule disruption by MeHg led to specific inhibition of β-tubulin synthesis with little or no effect on total protein synthesis. This selective reduction in β-tubulin synthesis was caused by post-transcriptional regulation through increased an tubulin pool resulting from depolymerization of microtubules by MeHg. The cells exposed to MeHg proceeded to apoptotic cell death long after growth inhibition. Since the occurrence of apoptosis was preceded by the G2/M phase arrest after MeHg treatment, it is likely that this arrest is an important event in apoptosis induction by MeHg. This apoptosis was induced via a p53-independent pathway in neuronal and nonneuronal cell lines. The study using the MeHg resistant cell line established by us demonstrated that the ability to accumulate MeHg and a low level of intracellular glutathione(GSH) made cells to vulnerable to MeHg.The neuronal cell lines showed a tendency to have a lower GSH level and, consequently, a higher susceptibility to MeHg than nonneuronal cell lines.
The biodegrading ability of drainage water from research laboratories to dichloromethane (DCM) and chloroform (CF) was surveyed. When DCM was used as a sole carbon source in a synthetic mineral salt medium, some water samples showed ability to degrade DCM, and DCM-degrading bacteria were isolated from them, whereas no samples showed CF degradation activity. Two isolates, strain P3310, a Flavimonas sp., and strain G31, a Chryseobacterium sp., were used for further investigations. Both strains were able to use DCM as a carbon source for growth and also grow in complex media containing other carbon sources, suggesting they werefacultative methylotroph. Both strains needed 6 days at 30°C to completely degrade 200 mg/l of DCM with the first isolated cells, but this was shortened to 2 days with the first subculture, suggesting they were acclimatized. Although the DCM-degrading activity of strain G31 was inhibited by addition of other carbon sources such as peptone or glucose, that of strain P3310 was not affected. Thus, strain P3310 may be a useful candidate for bioremediation to eliminate DCM from drainage.
Tyrosine isomers produced by gamma radiation of aqueous phenylalanine solutions at mid dose levels (1-10kGy) were examined to obtain basic information for irradiated food detection using a new high performance liquid chromatography (HPLC) analytical procedure. The procedure was established using an automated pre-column derivatization with 4-fluoro-7-nitro 2, 1, 3-benzoxadiazole (NBD-F) followed by reverse phase HPLC and LASER fluorometric detection. The limit of detection (LOD) was 0.06ng on-column and the linear range for calibration was 0.06 to 50ng for the tyrosine derivatives. The relative standard deviation was 10% to 12%. The amounts of the tyrosine isomers increased with levels of irradiation. Irradiation at low temperature with reduced oxygen decreased the isomer yields. In the pH range of 5 to 7, the amount of product was not changed significantly by pH, outside this range, the pH did have an effect on product generation. At constant dose levels the yields of tyrosine isomers initially increased with phenylalanine concentration, although, with further increases in phenylalanine a reduction in the absolute amounts was observed. Dose rates varying from 0.5kGy/h to 10kGy/h had no significant effect on tyrosine isomer formation if a total of 10kGy was used in each case. In addition, demonstrating the usefulness of this new analytical technique for o-tyrosine determination, these studies suggest that the presence of o-tyrosine is another parameter indicative of gamma irradiation.
A p53-independent increase in p21/WAF1/Cip1 gene expression is induced by anti-cancer agents such as trichostatin, actinomycin D and butyrate, and the signaling cascade of this induction was examined in cells stably transformed with a luciferase reporter under transcriptional control of the p21/WAF1/Cip1 gene. An inhibitor of stress-activated protein kinase p38 (SB203580) efficiently inhibited the induction, while PD98059, an inhibitor of MEK1, showed weaker inhibition. The dominant negative form of MKK6 inhibited the transcriptional activation of p21/WAF1/Cip1 gene in transient assay, whereas the dominant negative form of MKK4 did not affect it. Western blotting using antibodies against activated MAP kinases showed that butyrate, trichostatin and actinomycin D activated p38 in p53-defective human osteoblastic cells, but ERK1/2 and JNK activities were not increased significantly by these treatments. These results indicate that p38 kinase is the principal signaling molecule involved in the induction of p21/WAF1/Cip1 gene expression by butyrate, trichostatin and actinomycin D.
Three strains of enterohemorrhagic Escherichia coli O157 : H7 derived from patients of outbreaks in Osaka, Japan 1996 were used to determine the antimicrobial effect of the chemical preservatives : sorbic acid, benzoic acid, p-hydroxybenzoic acid, and dehydroacetic acid. The pH of the media strictly limited the growth of the pathogenic strains; a pH of 5.5 or below completely inhibited growth of these strains. The minimum inhibitory concentration (MIC) value for sorbic acid, benzoic acid, and dehydroacetic acid was 4mg/ml and that of p-hydroxybenzoic acid was 16mg/ml for the three pathogenic strains. Under the MIC conditions, the action of sorbic acid was bactericidal, whereas the other three antimicrobial chemicals were bacteriostatic. In Japan, the maximum allowable dose level of sorbic acid in meat products is 2mg/g, which corresponds to half the MIC concentration. To determine if this concentration resulted in an antimicrobial effect, homogenized hamburger beef was experimentally contaminated with E. coli O157 : H7 at an initial level of 104 colony forming unit/g. After incubation for 7 days, this concentration of sorbic acid demonstrated a bacteriostatic effect in the meat.
The brain of rats injected intravenously with 65Zn-His or 65ZnCl2 was subjected to autoradiography to study the role of histidine on zinc transport into the brain. One hour after injection, the radioactivity from 65Zn-His was largely concentrated in the choroid plexus in the ventricles. Six days after injection, the radioactivity from 65Zn-His was relatively concentrated in the hippocampal CA3 and dentate gyrus and the amygdala. The relative distribution of 65Zn-His in the brain was similar to that of 65ZnCl2 group at both 1 h and 6 days, suggesting that histidine may participate in zinc uptake in the brain. Oh the other hand, the clearance of the 65Zn-His group from the blood was higher than that of the 65ZnCl2 group. Brain uptake of the former was lower than that of the latter both 1 h and 6 days after injection. These results suggest that zinc uptake in the brain is influenced by histidine levels in the bloodstream.
The mutagenic activity of the crude extract obtained from the reaction mixture of pyrene and sodium chloride in the presence of 2 metallic oxides [silicon dioxide : silicic anhydride form (SiO2) and titanium dioxide : anatase form (TiO2)] under xenon lamp irradiation was examined using Salmonella typhimurium tester strains (TA98 and TA100), and was compared with the mutagenic activity of 1-chloropyrene (1-CP), dichloropyrenes (DCP), 1-nitropyrene (1-NP) and dinitropyrenes (DNP) in the crude extract. In the presence of SiO2, the mutagenicity of 1-NP in the crude extract, and that of the crude extract increased with the progress of the irradiation time. Moreover, the crude extract and 1-NP levels of mutagenicity were considerably similar in each exposure time. Accordingly, it was presumed that the increase of the mutagenic activity of the crude extract was caused by the increase of the yields of 1-NP in the crude extract. In the presence of TiO2, the mutagenicity of 1-NP in the crude extract decreased for the extended irradiation time, but the mutagenicity of the crude extract increased in reverse. It was presumed that the increase of the mutagenic activity of the crude extract was due to increasing the yields of other strong mutagens other than 1-CP, DCP or 1-NP.
Glucose was determined using an apparatus containing an enzyme reactor in a flow line. The enzymes used for glucose assay were hexokinase and glucose-6-phosphate dehydrogenase. NADH formed by enzymatic reactions was fluorometrically detected. The calibration curve for glucose was linear within the range of 0.2-50μM (r=0.9996), and the detection limit was 0.1μM (S/N=3). This method was applied to the analysis of glucose in plasma. No influence of sodium fluoride on the activities of immobilized enzymes was observed. Recovery of glucose added to plasma or serum was found to be in the range of 98 to 106%. We investigated the correlation between the glucose content determined by other methods and that determined by the present method. A linear relationship was observed between that determined by the present method and that by both the glucose oxidase-electrode method (y=0.986x-4.6, r=0.9993) and the soluble enzyme method (y=1.004x+1.3, r=0.9982).
Although advanced glycation endproducts (AGEs) have been proved to be involved in the pathogenesis of vascular complications, such as atherosclerosis in diabetic patients, little is known about the functional damage to vascular cells caused by AGEs. In early and late atherosclerosis, excess proteoglycans (PGs) derived from vascular smooth muscle and endothelial cells deposit in the subendothelial extracellular matrix of the vascular wall. To address the question whether AGEs affect the synthesis of PGs in vascular cels or not, the effect of AGEs on steady-state levels of PG core mRNAs in cultured human aortic smooth muscle and endothelial cells was investigated. AGEs were prepared by incubation of bovine serum albumin with glucose and the mRNAs coding for the core proteins of heparan sulfate PGs (perlecan and syndecan-1) and chondroitin/dermatan sulfate PGs (versican, biglycan and decorin) were determined by quantitative reverse transcription-polymerase chain reactions. In vascular smooth muscle cells, the steady-state level of mRNAs coding for perlecan, syndecan-1, versican and biglycan core proteins was unchanged whereas that of mRNA coding for decorin core protein was increased by AGEs in a dose- and time-dependent manner. On the other hand, in vascular endothelial cells, mRNAs coding for perlecan, syndecan-1 and biglycan were observed, although their steady-state levels were unaffected by AGEs. The present data suggest that AGEs may be involved in the accumulation of decorin derived from vascular smooth muscle cells in the atherosclerotic vascular wall of diabetic patients.
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