Control of the catalytic mechanism of an enzyme by amino acid substitution.
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Bacteriophage T4↗
Biomedical subjects
K Morimoto
Publications and source records attributed to K Morimoto.
Association between genetic variants of mast-cell chymase and eczema.
BACKGROUND: Atopy is a common syndrome underlying asthma, rhinitis, and eczema, and is characterised by high immunoglobulin E (IgE) responses to common antigens. IgE and mast-cell chymase (MCC-a serine protease secreted by skin mast cells) have a key role in atopic or allergic inflammation of the skin. The gene for MCC is located within a cluster of genes for cellular proteases on chromosome 14q11.2. We aimed to identify variants of MCC and another gene within this complex, and assess whether there is a genetic association between variants of MCC and atopic disorders-particularly eczema. METHODS: We randomly selected 100 controls and recruited patients-100 in each group-with atopic asthma, non-atopic asthma, atopic rhinitis, and atopic eczema. PCR amplification was used to test genomic DNA for an association between allelic polymorphisms in MCC and a flanking gene (CGL1, for the cathepsin-G-like protein) on chromosome 14q11 and asthma, rhinitis, and eczema. FINDINGS: We found a significant association between a BstXI polymorphism in MCC and eczema (odds ratio 2.17 [95% CI 1.21-3.88], p = 0.009), but no association with atopic asthma, rhinitis, or non-atopic asthma. There was no association between an Mboll polymorphism in CGL1 and any of the atopic disorders. INTERPRETATION: These findings suggest that variants of MCC may be one source of genetic risk for eczema.
Adolescent↗
Adenosine transport inhibitors enhance high K(+)-evoked taurine release from rat hippocampus.
We examined the effects of Ca(2+)-free medium containing 20 mM Mg2+, a non-selective adenosine receptor antagonist, theophylline, and adenosine transport inhibitors, dipyridamole and nitrobenzylthioinosine, on high K(+)-evoked spreading depression, glutamate, and taurine release from the rat hippocampus using brain microdialysis. High K+ alone perfusion evoked spreading depression and increased glutamate release followed by taurine efflux. Perfusion of Ca(2+)-free medium with high K+ never evoked spreading depression and decreased the high K(+)-evoked taurine release. Perfusion of theophylline (1 mM) increased the occurrence of high K(+)-evoked spreading depression and glutamate release, but did not modify taurine release. In contrast, simultaneous perfusion of dipyridamole (100 microM) and nitrobenzylthioinosine (50 microM) reduced the occurrence of spreading depression and the high K(+)-evoked glutamate release, but enhanced significantly the taurine efflux. These findings suggest that endogenous taurine with adenosine may have neuroprotective actions against high K(+)-evoked glutamate release and spreading depression in the rat hippocampus, in addition to its osmoregulatory action.
Adenosine↗
Characterization of a unique variant of bat rabies virus responsible for newly emerging human cases in North America.
The silver-haired bat variant of rabies virus (SHBRV) has been identified as the etiological agent of a number of recent human rabies cases in the United States that are unusual in not having been associated with any known history of conventional exposure. Comparison of the different biological and biochemical properties of isolates of this virus with those of a coyote street rabies virus (COSRV) revealed that there are unique features associated with SHBRV. In vitro studies showed that, while the susceptibility of neuroblastoma cells to infection by both viruses was similar, the infectivity of SHBRV was much higher than that of COSRV in fibroblasts (BHK-21) and epithelial cells (MA-104), particularly when these cells were kept at 34 degrees C. At this temperature, low pH-dependent fusion and cell-to-cell spread of virus is seen in BHK-21 cells infected with SHBRV but not with COSRV. It appears that SHBRV may possess an unique cellular tropism and the ability to replicate at lower temperature, allowing a more effective local replication in the dermis. This hypothesis is supported by in vivo results which showed that while SHBRV is less neurovirulent than COSRV when administered via the intramuscular or intranasal routes, both viruses are equally neuroinvasive if injected intracranially or intradermally. Consistent with the above findings, the amino acid sequences of the glycoproteins of SHBRV and COSRV were found to have substantial differences, particularly in the region that contains the putative toxic loop, which are reflected in marked differences in their antigenic composition. Nevertheless, an experimental rabies vaccine based on the Pittman Moore vaccine strain protected mice equally well from lethal doses of SHBRV and COSRV, suggesting that currently used vaccines should be effective in the postexposure prophylaxis of rabies due to SHBRV.
Animals↗
Control of hemoglobin synthesis in erythroid differentiating K562 cells. I. Role of iron in erythroid cell heme synthesis.
K562 cells were used to investigate the factors that control hemoglobin (Hb) synthesis. Treatment with sodium butyrate enhanced Hb synthesis and glycophorin A expression. delta-Aminolevulinate synthase (ALAS) activity and Hb levels simultaneously increased to a similar extent and with a similar time course, and the increases were dependent on the concentration of diferric transferrin (FeTf) in the culture medium. Addition of exogenous delta-aminolevulinic acid (ALA) resulted in a dose-dependent increase in Hb content. Hb synthesis was inhibited 50% after addition of succinylacetone (SA), a potent inhibitor of delta-aminolevulinate dehydratase. These findings suggest that ALAS is a key enzyme in the eight steps of de novo heme synthesis and that iron, including FeTf, plays a central role in Hb synthesis through control of ALAS activity in erythroid differentiating cells. On the other hand, erythropoietin (EPO) treatment had no effect on Hb synthesis and slightly suppressed glycophorin A expression. Hemin enhanced Hb synthesis in the K562 cells but not glycophorin A expression. The addition of ALA, SA, or FeTf to hemin-treated cells caused no significant changes in Hb synthesis. Butyrate, EPO, and hemin acted on the K562 cells in different ways and caused different biochemical changes in the Hb synthesis process.
5-Aminolevulinate Synthetase↗
Association between Fc epsilon RI beta and atopic disorder in a Japanese population.
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Adult↗
Biological and physicochemical characterization of recombinant human erythropoietins fractionated by Mono Q column chromatography and their modification with sialyltransferase.
Ten erythropoietin (EPO) fractions differing in sialic acid content, ranging from 9.5 to 13.8 mol mol-1 of EPO, were obtained from baby hamster kidney cell-derived recombinant human EPO by Mono Q column chromatography. The mean pI values of the EPO fractions determined by IEF-gel electrophoresis systematically shifted from 4.11 to 3.31, coinciding with the sialic acid content, without a change in the constitution of asialo N-linked oligosaccharides of each fraction. Although a linear relationship between the in vivo bioactivity and the sialic acid content of the fractionated samples was observed until 12.1 mol mol-1 of EPO, there was no further increase in their activity over 12.4 mol mol-1 of EPO. On the other hand, an inverse relationship between the in vitro bioactivity and sialic acid content of EPO was observed. Also, we showed that the in vivo bioactivity of some fractions with low sialic acid contents was increased after treatment with alpha 2,6-sialyltransferase, but the in vivo bioactivity of the other fractions with high sialic acid contents was either decreased or not affected.
Animals↗
The contribution of polymorphism in the alcohol dehydrogenase beta subunit to alcohol sensitivity in a Japanese population.
In humans, ingested alcohol is mainly metabolized by the combination of class I alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH). In Orientals, there are highly frequent polymorphisms both in the class I ADH beta subunit (ADH2) and in the low Km ALDH (ALDH2). We characterized the three genotypes of ALDH2 in a Japanese population. In the present study, we evaluated the effects of the ADH2 polymorphism in the same population (424 males and 100 females) controlling for the effects of the ALDH2 polymorphism. In the ALDH2(1)/ALDH2(2) group, the frequency of facial flushing with one glass of beer was significantly higher in the ADH2(1)/ADH2(2) and ADH2(2)/ADH2(2) genotype than in the ADH2(1)/ADH2(1) genotype. Likewise, the proportion of persons with positive results for ethanol-induced cutaneous erythema differed significantly depending on the ADH2 genotype in both the ALDH2(1)/ALDH2(1) and ALDH2(1)/ALDH2(2) genotypes. However, drinking habits were not significantly associated with the ADH2 genotype, suggesting that the ADH2 genotype influences the metabolism of ethanol only in the peripheral tissues.
Adult↗
Association of life style with high risk of hyperimmunity and of immunosuppression mediated by IgE.
To test the hypothesis that the increase in allergic prevalence is related not only to environmental allergens, but also to comprehensive life style, we administered to 733 workers at a hard metal plant a questionnaire that included 17 physical and mental health practices. We have shown that eight practices are associated with increases or decreases of total and specific IgE levels, serving to keep them within the normal range (5-400 IU/ml), after controlling for age, sex, and environmental factors. Further confirmation of the definite effect of life style on allergic reactions comes from higher heritability among younger pairs of identical twins of total IgE levels and allergic disorders than among older pairs of identical twins. A marked synergism was found among Undesirable life-style factors as bipolar high-risk factors for the development of allergic diseases or immunosuppression characterized by low natural killer (NK) cell activity through which soluble low-affinity IgE receptor is kept low. An effort to practice Desirable life styles, therefore, may be of benefit in reducing the risk of immunoallergic disorders.
Female↗
Superoxide dismutase activity as a predictor of myocardial reperfusion and salvage in acute myocardial infarction.
We attempted to predict successful myocardial reperfusion and salvage in acute myocardial infarction (AMI) by using measurements of plasma superoxide dismutase (SOD), a plasma free-radical scavenger, activity. Forty-nine patients with AMI were studied within 6 hours of symptoms onset. In group 1 (n = 26), primary percutaneous transluminal coronary angioplasty (PTCA) was undertaken, and plasma SOD activity was measured for 8 hours by the nitrite method. Left ventricular (LV) angiography was assessed before and 3 months after PTCA by computer LV contraction analysis. In group 2 (n = 23), TPA was infused intravenously over a 60-minute period, and plasma SOD activity was measured before and immediately after TPA infusion. In group 1, occluded coronary arteries were successfully dilated in 24 of 26 patients, and plasma SOD activity increased from 3.20 +/- 0.17 microns/ml to 4.66 +/- 0.29 microns/ml at 1 hour after PTCA (p < 0.001), returning to the basal level by 8 hours after PTCA. Plasma SOD activity did not significantly change patients with unsuccessful PTCA or those with the no-reflow phenomenon. The maximal increase in plasma SOD activity was significantly correlated with the grade of improvement in LV contraction (r = 0.852, p < 0.001). In group 2, the sensitivity and specificity of predicting coronary recanalization was 86% and 89%, respectively. In conclusion, myocardial reperfusion and salvage in AMI can be predicted by changes in plasma SOD activity.
Aged↗
A comparison of the 8-hydroxydeoxyguanosine, chromosome aberrations and micronucleus techniques for the assessment of the genotoxicity of mercury compounds in human blood lymphocytes.
We compared the mechanism of action of micronuclei (MN), unstable chromosome aberrations, and 8-hydroxydeoxyguanosine (8-OHdG) levels to evaluate the genotoxicity of methyl mercuric chloride (CH3HgCl) and mercuric chloride (HgCl2) in human peripheral lymphocytes. The chromosome aberrations in human peripheral lymphocytes exposed to various concentrations of CH3HgCl or HgCl2 increased in a concentration-dependent manner and were significantly higher than the control when the cells were incubated with 1 x 10(-5) M (HgCl2) or 2 x 10(-6) M (CH3HgCl). The increase in the incidence of micronucleated lymphocytes was significant among the exposed groups, being 2 x 10(-5) M (HgCl2) and 5 x 10(-6) M (CH3HgCl) compared with the control. CH3HgCl was about 4-fold more potent than HgCl2. We determined the 8-OHdG levels in human peripheral blood mononuclear cells(PBMC) and found that they were significantly higher in the exposed groups at 1 x 10(-5) M (HgCl2) and 5 x 10(-6) M (CH3HgCl) compared with the control. A detectable (p < 0.05) increase in the level of 8-OHdG was induced by CH3HgCl at a concentration that was about 50% of the amount of HgCl2 required to produce a similar response. The data confirmed the value of the MN and/or chromosome aberration assays for assessing of HgCl2- and/or CH3HgCl-induced genotoxicity, and indicated that they are about the same concentration as the 8-OHdG assay. The presence of genotoxic effects in peripheral blood lymphocytes exposed to the mercuric compounds indicated by the chromosome aberrations and the MN assays could be partly due either to the disturbance of the spindle mechanism, or to the elevated level of 8-OHdG brought by the generation of reactive oxygen species.
8-Hydroxy-2'-Deoxyguanosine↗
Photosensitivity from pyridoxine hydrochloride (vitamin B6).
We describe a 35-year-old female patient with photosensitivity due to pyridoxine hydrochloride (vitamin B6) in a multivitamin over-the-counter preparation. Photopatch and oral photochallenge tests using pyridoxine hydrochloride and UVA irradiation were positive. Larger doses for therapeutic use could cause photosensitivity.
Administration, Oral↗
Determination of 8-hydroxydeoxyguanosine in human cells under oxygen-free conditions.
To establish an accurate 8-hydroxydeoxyguanosine (8OHdG) determination system, we examined two potential factors causing experimental error in 8OHdG determination. First, we examined the efficiency of the enzymatic digestion of DNA, that could cause misestimation of 8OHdG. Second, since we considered that the oxygen molecules in atmosphere and in reagents were the main factor contributing to the experimental errors, we carried out the 8OHdG determination under oxygen-free conditions and compared the 8OHdG value with that determined by the methods under ambient atmosphere. The calf thymus DNA was sufficiently digested in the condition we used and the yields of dG were constant, even when the DNA was damaged with H2O2 (80 mM) and UV irradiation. By carrying out the DNA extraction manually, instead of using the DNA extractor, we could reduce the additional 8OHdG formation during sample processing. No trend was found in the difference between the 8OHdG values determined under oxygen-free conditions and under ambient atmosphere. However, when the 8OHdG values were compared in samples with asbestos, the value determined under oxygen-free conditions was significantly lower than that determined under ambient atmosphere. These findings suggest that the removal of oxygen molecules was effective in reducing accidental ROS generation by impurities in the sample, which could cause the additional 8OHdG formation, and that the oxygen-free system made the determination of 8OHdG reproducible and more accurate than before. When the oxygen-free system was applied to human leukocytes, the system showed good reproducibility (r = 0.535, P < 0.001), even though the 8OHdG level was low. With the system, we could detect a significant difference between 8OHdG in polymorphonuclear leukocytes (0.241 +/- 0.129) and mononuclear leukocytes (0.188 +/- 0.126, P < 0.01).
8-Hydroxy-2'-Deoxyguanosine↗
Relationship between the intracellular reactive oxygen species and the induction of oxidative DNA damage in human neutrophil-like cells.
To clarify the mechanisms of intracellular induction of oxidative DNA damage, we have investigated the concentrations of intracellular reactive oxygen species and the amounts of 8-hydroxydeoxyguanosine (8OHdG), a mutagenic oxidative DNA damage, in human neutrophil-like cells, dimethylsulfoxide-differentiated HL60 (DMSO-HL60). We determined intracellular concentrations of hydrogen peroxide and superoxide by flow cytometry with dichlorofluorescein diacetate and hydroethidine, respectively. We determined the 8OHdG amounts with an electrochemical detector connected to HPLC after anaerobic sample processing. DMSO-HL60 releases superoxide upon stimulation with phorbol myristate acetate, and the released superoxide dismutates to hydrogen peroxide. Stimulation of DMSO-HL60 with 100 nM phorbol myristate acetate increased intracellular hydrogen peroxide, superoxide and 8OHdG (control). Addition of 1000 U/ml catalase decreased hydrogen peroxide (31.3% of control) and 8OHdG (20.3%). Addition of 100 U/ml SOD decreased superoxide (18.7%) and 8OHdG (41.6%). Addition of 1 mM deferoxamine decreased 8OHdG (30.4%), but increased hydrogen peroxide (129.6%). Addition of 200 microM 4-acetamido-4'- isothiocyanostilbene-2,2'-disulfonic acid decreased superoxide (59.9%) and 8OHdG (42.0%). Addition of 0.4% ethanol had no effect on superoxide concentration (102.2%), but tended to decrease hydrogen peroxide (83.5%) and 8OHdG (84.3%). Pretreatment of DMSO-HL60 with 0.1 mM FeSO4 increased 8OHdG (117.3%), but decreased hydrogen peroxide (75.8%). These findings indicate that the extracellularly released superoxide and hydrogen peroxide diffuse into the cell, but that such reactive oxygen species are not the direct molecules to induce 8OHdG. Our results suggest that 8OHdG is induced by the hydroxyl radical which is generated from intracellular hydrogen peroxide and superoxide-reduced Fe.
8-Hydroxy-2'-Deoxyguanosine↗
Association between atopic asthma and a coding variant of Fc epsilon RI beta in a Japanese population.
A genetic association study was performed with coding variants of Fc epsilon RI beta in relation to atopic and non-atopic asthma in a Japanese population (n = 400). A coding variant of Gly237Glu in exon 7 of Fc epsilon RI beta gene showed association with atopic asthma (OR = 3.00, chi 2 = 5.10, p < 0.03), but not with non-atopic asthma; this was seen particularly in childhood asthma (OR = 3.92, chi 2 = 8.66, p < 0.005). This variant is also associated with very high total serum IgE levels (> mean + 3 SD, OR = 8.56, chi 2 = 46.2, p < 0.0001), but not any allergen specific IgE. However, Leu181lle, another variant of Fc epsilon RI beta related to atopy in British and Australian populations, was not found in this Japanese population. These results suggest that variants of Fc epsilon RI beta may be an important genetic cause of the atopic asthma.
Adult↗
Studies on unusual cytoplasmic structures which contain rabies virus envelope proteins.
We investigated unusual structures produced in BHK-21 cells infected with rabies virus (HEP-Flury strain). Sellers' staining of the cells revealed, in addition to Negri body-like structures (inclusion bodies), production of a fuchsin-stained cytoplasmic structure (FCPS) which encircled the nucleus. The frequency of the FCPS-forming cells increased as replication progressed. The FCPS was different from the inclusion body because the former contained the viral glycoprotein (G) and matrix protein (M2) antigens, while the latter contained nucleocapsid antigens. In the early phase of infection, we observed accumulation of viral envelope antigens in a cytoplasmic structure that was considered to be expanded rough endoplasmic reticulum (rER) because of its concomitant increase in BiP content. Time-course studies suggested that the envelope antigen-containing structure, which was not stained with basic fuchsin, translocated to the perinuclear region to form the FCPS. FCPS formation was dependent on incubation temperature and was decreased at 30 degrees C, while the development of virus-induced cytopathic effect (CPE) was delayed. When the incubation temperature was shifted up to 37 degrees C, FCPS formation was induced again and progression of CPE was accelerated in approximate proportion to the increasing number of FCPS-positive cells. From these studies, we conclude that viral G proteins gradually accumulate in the rER with M2 protein and the expanded rER converts eventually into the FCPS, which may be closely related to accelerated host cell death.
Animals↗
Regional increases in brain-derived neurotrophic factor and nerve growth factor mRNAs during amygdaloid kindling, but not in acidic and basist growth factor mRNAs.
We studied mRNA levels for neurotrophic factors using the amygdaloid k indling model of epilepsy. One hour after stage 5 kindled seizures, there were four-to fivefold increases in brain-derived neurotrophic factor (BDNF) mRNA in rat dentate gyrus and perirhinal cortex. Nerve growth factor (NGF) mRNA levels were increased bilaterally in some (but not all) limbic areas. There were no detectable changes in acidic fibroblast GF (aFGF) mRNA or basic fibroblast GF (bFGF) mRNA for 24 h after the kindled seizures. During kindling, levels of BDNF mRNA in the dentate gyrus correlated with projection to generalized seizures, whereas NGF mRNA in the limbic regions continued to increase during seizure development. These results indicate that the induction of mRNAs for neurotrophic factors, especially for BDNF mRNA in the dentate gyrus, corresponds to the increases in metabolic and electrical ictal discharge associated with kindled seizures. The persistent increase observed in NGF mRNA may be related to enhanced synaptic efficacy during kindling, but aFGF and bFGF are presumed to have little relation to the kindling process.
Amygdala↗
Enhancing effects of unsaturated fatty acids with various structures on the permeation of indomethacin through rat skin.
Effects of straight-chain, cis-type, unsaturated fatty acids with various structures (alkyl chain lengths, numbers of double bonds, position of double bonds, and cis- and trans-positional isomers) on the skin permeation of indomethacin were examined by using rat skins in-vitro. Furthermore, the disordering degrees of the intercellular lipid domain in the stratum corneum, which were treated with preparations of unsaturated fatty acids, were measured by the Fourier transform infrared (FT-IR) method using excised rabbit ear skins. Unsaturated fatty acids enhanced the permeation of indomethacin through rat skins. These permeation-enhancing effects by unsaturated fatty acids were affected by changes of their alkyl chain length from C14 to C22. The lag-times on the permeation of indomethacin were shortened by unsaturated fatty acids in the following order: C20 = C18 = C22 < C16 < C14. These fluxes were increased by unsaturated fatty acids in the following order: C20 > C22 = C18 = C16 > C14. Therefore, gondoic acid (cis-11-eicosenoic acid; C20H38O2) mostly enhanced the skin permeation of indomethacin. However, the enhancing effects of unsaturated fatty acids (C18 chain) were not affected by their differences of position and numbers of double bonds. These permeation-enhancing effects which were evaluated by flux were related to the degrees of wave-number shift in the frequency of the antisymmetric CH bond stretching absorbance (near 2920 cm-1) on FT-IR spectra of the fatty acid-treated stratum corneum. Therefore, the perturbation increase of lipid domain in the stratum corneum by these fatty acids probably was the cause of the enhancing effects of permeation of indomethacin.
Animals↗