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T Yoshimura

Publications and source records attributed to T Yoshimura.

At least 127 records · Page 7Linked to original sources
PubMed1999

Physicochemical Properties of 2-Vinylpyridine Telomers Possessing Multihydrocarbon Chains in Aqueous Solution and at the Silica/Aqueous Solution Interface.

Physicochemical properties of multialkylated surfactants of partially quaternized 2-vinylpyridine telomers having multihydrocarbon side chains (nRm-2VPQ: n, number of chains; m, alkyl chain length) in aqueous solutions were investigated. The critical micelle concentration (cmc) and surface tension at the cmc were 13 µmol dm(-3) and 52 mNm(-1) for 2.1R(8)-2VPQ, 7.1 µmol dm(-3) and 37 mNm(-1) for 2.5R(12)-2VPQ, and 4.7 µmol dm(-3) and 40.0 mNm(-1) for 3.4R(12)-2VPQ, respectively. The aggregation numbers at the cmc determined by the light scattering method were 4 +/- 1 for 2.1R(8)-2VPQ, 45 +/- 10 for 2.5R(12)-2VPQ, and 11 +/- 1 for 3.4R(12)-2VPQ. Thus, the number of chains and the alkyl chain length of the telomers affected the micellar properties in aqueous solutions. At the interface of the silica/aqueous solution, the adsorbed amounts of the telomers increased sharply at their low concentrations and reached a plateau by forming a monolayer and a subsequent bilayer. Silica suspensions also showed a dispersion-flocculation-redispersion sequence with the telomer concentration, where the maximum sedimentation rate was influenced by the number of chains and the alkyl chain length of the telomers. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

Workplace exposure to environmental tobacco smoke and high density lipoprotein cholesterol among nonsmokers.

There are few epidemiologic studies among adult nonsmokers on the effects of workplace environmental tobacco smoke on high density lipoprotein cholesterol (HDL-C). The authors investigated this relation, using data from health examinations conducted in 1995 on 3,062 Japanese nonsmokers in a total of 27 municipal offices with few smoking restrictions. Multiple regression analysis with adjustments for age, body mass index, alcohol drinking, and sports activities showed that in women, and in men lacking both alcohol consumption and sports activities characteristics, there were inverse linear relations between workplace smoking indices and HDL-C levels. Multivariate logistic regression showed that nonsmoking women in the upper two thirds of offices ranked by smoking intensity had an increased risk of low HDL-C levels (<45 mg), taking those in the lowest third of offices as reference (the medium third: odds ratio = 1.7; 95% confidence interval: 1.2, 2.5; the highest third: odds ratio = 1.6; 95% confidence interval: 1.1, 2.4). The results indicated that workplace environmental tobacco smoke exposure is associated with HDL-C among nonsmokers. However, the lack of data on home exposure limits causal inferences about the effects of workplace exposure.

Adult↗
PubMed1999

Nitrosothiol formation catalyzed by ceruloplasmin. Implication for cytoprotective mechanism in vivo.

Ceruloplasmin (CP) is a major multicopper-containing plasma protein that is not only involved in iron metabolism through its ferroxidase activity but also functions as an antioxidant. However, physiological substrates for CP have not been fully identified nor has the role of CP been fully understood. The reaction of nitric oxide (NO) with CP was investigated in view of nitrosothiol (RS-NO) formation. First, formation of heavy metal- or CP-catalyzed RS-NO was examined with physiologically relevant concentrations of NO and various thiol compounds (RSH) such as glutathione (GSH). Among the various heavy metal ions and copper-containing enzymes and proteins examined, only copper ion (Cu(2+)) and CP showed potent RS-NO (S-nitrosoglutathione)-producing activity. Also, RS-NO-forming catalytic activity was evident for CP added exogenously to RAW264 cells expressing inducible NO synthase in culture, but this was not the case for copper ion. Similarly, CP produced endogenously by HepG2 cells showed potent RS-NO-forming activity in the cell culture. One-electron oxidation of NO appears to be operative for RS-NO production via electron transfer from type 1 copper to a cluster of types 2 and 3 copper in CP. Neurological disorders are associated with aceruloplasminemia; besides RS-NO, S-nitrosoglutathione particularly has been shown to have neuroprotective effect against oxidative stress induced by iron overload. Thus, we suggest that CP plays an important catalytic role in RS-NO formation, which may contribute to its potent antioxidant and cytoprotective activities in vivo in mammalian biological systems.

Animals↗
PubMed1999

Simultaneous determination of donepezil (aricept) enantiomers in human plasma by liquid chromatography-electrospray tandem mass spectrometry.

A rapid, sensitive and enantioselective LC-MS-MS method using deuterium-labeled internal standard was developed and evaluated for the simultaneous quantitative determination of donepezil enantiomers in human plasma without interconversion during clean-up process and measurement. The use of an avidin column allowed the separation of donepezil enantiomers, which were specifically detected by MS-MS without interference from its metabolites and plasma constituents. Evaluation of this assay method shows that samples can be assayed with acceptable accuracy and precision within the range from 0.0206 ng/ml to 51.6 ng/ml for both R-donepezil and S-donepezil. This analytical method was applied to the simultaneous quantitation of donepezil enantiomers in human plasma.

Calibration↗
PubMed1999

Estrogen replacement therapy decreases platelet-activating factor-acetylhydrolase activity in post-menopausal women.

OBJECTIVE: To examine the effects of estrogen replacement therapy on plasma platelet-activating factor-acetylhydrolase (PAF-AH) activity and the lipoprotein profile in post-menopausal women. METHOD: Eight post-menopausal women received conjugated equine estrogen (0.625 mg/day) orally for a period of 10 weeks. PAF-AH activity and lipid levels were measured in plasma samples obtained from each subject prior to treatment and after 2, 6, and 10 weeks of estrogen therapy. RESULTS: Within 2 weeks of initiating estrogen treatment, a significant reduction in PAF-AH activity (-26%) was observed. Estrogen also caused significant decreases in total cholesterol (-8%), low-density lipoprotein-cholesterol (-24%), and the ratio of apolipoprotein B to A-II (-19%). On the other hand, levels of both high-density lipoprotein-cholesterol (18%) and triglyceride (31%) were elevated. CONCLUSION: Estrogen exerts a favorable effect on the lipoprotein profile, but decreased plasma PAF-AH activity may facilitate platelet aggregation thereby opposing protective effect of estrogen-replacement therapy with respect to thrombotic complications.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1999

Cloning and functional characterization of the 5'-flanking region of the human monocyte chemoattractant protein-1 receptor (CCR2) gene. Essential role of 5'-untranslated region in tissue-specific expression.

The human monocyte chemoattractant protein-1 receptor designated hCCR2 is an essential co-receptor in cell entry by the human immunodeficiency virus as well as a receptor for monocyte chemoattractant protein-1, a member of the family of C-C chemokines that mediate monocyte chemotaxis. To elucidate the molecular mechanisms underlying the transcriptional regulation of hCCR2, we cloned and sequenced the hCCR2 gene; it was approximately 8 kilobase pairs in length and consisted of three exons divided by two introns. In the 5'-flanking region, there were the typical mammalian promoter consensus elements, a CAAT box and a TATA box, resulting in a single transcription initiation site. In addition, we found clustered tissue-specific cis-regulatory elements such as GATA consensus sequences, Oct-1 binding sequences, and CAAT/enhancer-binding protein binding sequences. Luciferase assays with various promoter deletions and gel mobility shift assays indicated that three cis-regulatory elements located within the region from -89 to +118 are required for basal activity in THP-1 cells. One element is an octamer sequence 36-base pair upstream from the TATA box; it binds mainly to Oct-1 and is capable of increasing transcriptional activity. The other two elements, which are tandem recognition sites of the CAAT/enhancer-binding protein family, are located in the 5'-untranslated region and account for the transcriptional activation as well as the tissue specificity of hCCR2.

5' Untranslated Regions↗
PubMed1999

Role of lysine 39 of alanine racemase from Bacillus stearothermophilus that binds pyridoxal 5'-phosphate. Chemical rescue studies of Lys39 --> Ala mutant.

The lysine residue binding with the cofactor pyridoxal 5'-phosphate (PLP) plays an important role in catalysis, such as in the transaldimination and abstraction of alpha-hydrogen from a substrate amino acid in PLP-dependent enzymes. We studied the role of Lys39 of alanine racemase (EC 5.1.1.1) from Bacillus stearothermophilus, the PLP-binding residue of the enzyme, by replacing it site-specifically with alanine and characterizing the resultant K39A mutant enzyme. The mutant enzyme turned out to be inherently inactive, but gained an activity as high as about 0.1% of that of the wild-type enzyme upon addition of 0.2 M methylamine. The amine-assisted activity of the mutant enzyme depended on the pKa values and molecular volumes of the alkylamines used. A strong kinetic isotope effect was observed when alpha-deuterated D-alanine was used as a substrate in the methylamine-assisted reaction, but little effect was observed using its antipode. In marked contrast, only L-enantiomer of alanine showed a solvent isotope effect in deuterium oxide in the methylamine-assisted reaction. These results suggest that methylamine serves as a base not only to abstract the alpha-hydrogen from D-alanine but also to transfer a proton from water to the alpha-position of the deprotonated (achiral) intermediate to form D-alanine. Therefore, the exogenous amine can be regarded as a functional group fully representing Lys39 of the wild-type enzyme. Lys39 of the wild-type enzyme probably acts as the base catalyst specific to the D-enantiomer of alanine. Another residue specific to the L-enantiomer in the wild-type enzyme is kept intact in the K39A mutant.

Alanine↗
PubMed1999

The MKK6/p38 stress kinase cascade is critical for tumor necrosis factor-alpha-induced expression of monocyte-chemoattractant protein-1 in endothelial cells.

Monocyte chemoattractant protein-1 (MCP-1), a member of the C-C subfamily of chemokines, is important for the local recruitment of leukocytes to sites of inflammatory challenge. Here, we investigated endothelial signaling pathways involving members of the mitogen-activated protein (MAP) kinase superfamily and studied their role for MCP-1 expression in endothelium. We show that tumor necrosis factor-alpha (TNF-alpha), a potent inflammatory activator of endothelium, leads to activation of MAP kinases ERK, p38, and JNK in human umbilical vein endothelial cells (HUVEC). Contribution of MAP kinase pathways to TNF-alpha-induced synthesis of endothelial MCP-1 was then studied by pharmacologic inhibition and transient expression of dominant negative or constitutively active kinase mutants using flow cytometry, Northern blot, and luciferase reporter gene assays. Inhibition of Raf/MEK/ERK or SEK/JNK pathways had no significant effect on MCP-1 levels, whereas blocking the MKK6/p38 pathway by p38 inhibitors SB203580 or SB202190 or by a dominant negative mutant of MKK6, the upstream activator of p38, strongly inhibited TNF-alpha-induced expression of MCP-1. Consistent with that finding, expression of wild-type or constitutively active MKK6 significantly enhanced the effect of limiting TNF-alpha concentrations on MCP-1 synthesis. These data suggest a crucial role for the MKK6/p38 stress kinase cascade in TNF-alpha-mediated endothelial MCP-1 expression.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1999

Quantitative determination of E5880 in rat plasma by high-performance liquid chromatography/electrospray ionization tandem mass spectrometry.

A simple and sensitive method is described for the determination of E5880 in rat plasma. The method is based on high-performance liquid chromatography/electrospray ionization mass spectrometry, using deuterated E5880 as an internal standard. Selected reaction monitoring is employed for selectivity and sensitivity, this in turn enables quantification in a short period of time (within 7 minutes) over the extended range of 0.1-1000 ng/ml with acceptable precision and accuracy. The method demonstrated to be suitable for the quantitative analysis of E5880 in rat plasma. The pharmacokinetic profile of E5880 after a single intravenous administration of E5880 was elucidated.

Animals↗
PubMed1999

Allelic imbalance in chromosome band 18q21 and SMAD4 mutations in ovarian cancers.

Recently, three candidate tumor suppressor genes, SMAD2 (MADR2/JV18-1), SMAD4 (DPC4), and DCC, were identified in chromosome band 18q21. We examined allelic imbalance (AI) in 18q21 using six polymorphic microsatellite markers in 38 primary ovarian cancers and four ovarian borderline tumors. AI at one or more loci was detected in 15 of 37 (41%) informative ovarian cancers and in none of the four borderline tumors. Frequent AI was detected at the D18S46 (31%) and D18S474 (36%) loci, which were adjacent to the SMAD4 gene, and at the D18S69 (33%) locus, which was telomeric to the DCC gene. Therefore, we searched for mutations of the SMAD4 gene in 42 primary tumors and eight cell lines by PCR-SSCP and sequencing analyses. Missense mutations were detected in two ovarian tumors and three ovarian cancer cell lines, whereas silent mutation was detected in a primary ovarian cancer. These results suggest that there are at least two tumor suppressor genes on chromosome arm 18q and that SMAD4 is of importance in ovarian tumorigenesis.

Alleles↗
PubMed1999

MCP-1 is selectively expressed in the late phase by cytokine-stimulated human neutrophils: TNF-alpha plays a role in maximal MCP-1 mRNA expression.

Culture supernatants of phytohemagglutinin (PHA)-stimulated human peripheral blood mononuclear cells (PHA-sup) induced monocyte chemoattractant protein-1 (MCP-1) mRNA expression in human neutrophils. MCP-1 mRNA was first detected by Northern analysis at 8 h, and the peak level was detected at 16 h and sustained until 72 h. Cycloheximide and genistein, but not pertussis toxin, inhibited the expression of MCP-1 mRNA. Recombinant tumor necrosis factor alpha (TNF-alpha) induced a low level MCP-1 mRNA accumulation in neutrophils, and addition of anti-TNF-alpha IgG blocked 30-70% of MCP-1 mRNA expression induced with PHA-sup. PHA-sup-stimulated PMN synthesized and secreted 3.1+/-1.3 ng/5 x 10(6) PMN MCP-1 within the first 24 h. Hybridization of 32P-labeled cDNA preparations to an array of human cytokine cDNAs further indicated that MCP-1 mRNA was selectively up-regulated in the late phase after stimulation with the PHA-sup.

Chemokine CCL2↗
PubMed1999

Support for and observance of worksite smoking restriction policies--A study of municipal employees at a city office in Japan.

BACKGROUND: While various types of smoking restrictions have been introduced in Japanese workplaces, it is not clear what restriction policies workers find acceptable. This study examined the relationship between the extent of worksite smoking restriction and worker attitudes toward these policies. METHODS: Municipal employees randomly selected from a city office were surveyed using a self-administered questionnaire concerning support for and smokers' observance of their present smoking restriction. A total of 2857 (88. 6%) workers responded. RESULTS: More than 60% of respondents regarded a work-area ban with a designated smoking space as the most desirable policy. Among subjects who were aware of the current policies in their workplaces, positive support was highest for a total ban (73.9%) and decreased as the extent of the restriction became milder (P for trend <0.001). In contrast, an inverse relation was found for negative support (P for trend <0.001). These trends were observed among both nonsmokers and smokers. Smokers subject to a work-area ban observed the policy more faithfully than those subject to milder policies. CONCLUSIONS: Policies prohibiting smoking in work areas were favorably accepted by municipal employees, irrespective of smoking status. These results should encourage Japanese workplaces to adopt work-area bans, through which nonsmokers are effectively protected from environmental tobacco smoke.

Adult↗
PubMed1999

Specificity of omega-conotoxin MVIIC-binding and -blocking calcium channel antibodies in Lambert-Eaton myasthenic syndrome.

An immunoprecipitation assay was used to measure omega-conotoxin MVIIC (P/Q-type) binding and blocking calcium channel antibodies in 67 patients with Lambert-Eaton myasthenic syndrome (LEMS) and in a large control population. We first showed the presence of omega-conotoxin MVIIC-blocking antibody in LEMS patients. Binding antibodies were detected in 55 of 67 (82.1%) LEMS patients and in 2 of 296 (0.7%) controls. In contrast, blocking antibodies were positive in 14 of 67 (20.9%) LEMS patients and 8 of 171 (4.7%) controls. No LEMS patient had negative binding antibodies and positive blocking antibodies. The immunoprecipitation assay detected no antibodies against the whole P/Q-type calcium channel in either the paraneoplastic cerebellar degeneration or the amyotrophic lateral sclerosis sera. Neither the omega-conotoxin MVIIC-binding nor the -blocking calcium channel antibodies were correlated with clinical severity across the individuals, but longitudinal studies of some LEMS patients showed an inverse relation between binding antibody titre and disease severity. We concluded that the 125I-omega-conotoxin MVIIC assay for anti-P/Q-type voltage-gated calcium channel antibodies is highly specific for LEMS and that this sensitive binding antibody assay could be more valuable than the blocking antibody assay in the diagnosis of LEMS.

Antibodies↗
PubMed1999

Increased platelet-activating factor-acetylhydrolase activity in the umbilical venous plasma of growth-restricted fetuses.

OBJECTIVE: To determine whether platelet-activating factor-acetylhydrolase activity in fetal plasma obtained at birth from umbilical vessels is different from that in maternal plasma, and (2) to compare platelet-activating factor-acetylhydrolase activity in cord plasma from fetuses with fetal growth restriction (FGR) and those with appropriate growth for gestational age (AGA). METHODS: Platelet-activating factor-acetylhydrolase activity was measured in the plasma of 22 nonpregnant healthy women, 16 pregnant women at term during labor, 28 fetuses exhibiting AGA, and seven fetuses with FGR. RESULTS: Plasma platelet-activating factor-acetylhydrolase activity in normotensive pregnant women at 37-41 weeks' gestation was 28.1+/-16.6 nmol/mL per minute, which was not statistically different from the activity in nonpregnant women (30.8+/-11.1 nmol/mL per minute). Platelet-activating factor-acetylhydrolase activity in venous cord plasma from AGA fetuses was significantly (P < .01) lower than that in maternal plasma (6.3+/-2.6 nmol/mL per minute), and there was no difference between the activities found in arterial and venous cord samples. In FGR fetuses, venous cord platelet-activating factor-acetylhydrolase activity was significantly (P < .01) higher (12.1+/-1.4 nmol/mL per minute), than the activity seen in AGA fetuses, and when the data from AGA and FGR fetuses were considered together, there was a negative correlation between cord plasma platelet-activating factor-acetylhydrolase activity and neonatal body weight (r = .46, P = .006). CONCLUSION: Platelet-activating factor hydrolysis is significantly lower in fetuses than adults. Further, the comparatively high platelet-activating factor-acetylhydrolase activity in FGR fetuses suggests the existence of a compensatory mechanism to maintain microcirculation within the placenta.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1999

Unsuspected extra-adrenal pheochromocytoma simulating ovarian tumor.

We report on a case of an extraadrenal pheochromocytoma simulating an ovarian tumor. Before intervention, the patient exhibited no symptoms suggestive of pheochromocytoma. Nevertheless, during surgery she experienced marked blood pressure fluctuations, and an unsuspected extraadrenal pheochromocytoma was diagnosed. Thus, although rare, when preparing to remove a pelvic mass, the gynecologist should consider the possibility of an extraadrenal pheochromocytoma.

Blood Pressure↗
PubMed1999

Serum concentrations of carotenoids, alpha-tocopherol, fatty acids, and lipid peroxides among Japanese in Japan, and Japanese and Caucasians in the US.

Serum concentrations of carotenoids, alpha-tocopherol, fatty acids, and thiobarbituric acid-reactive substances (TBARS) were measured in 217 Japanese residents of Japan, and in 99 Japanese and 100 Caucasian residents of the US, aged from 50 y to 74 y. In females, serum values of carotenoids such as beta-carotene (BC) and zeaxanthin & lutein (ZL) were highest among Japanese in Japan, followed by Japanese in the US and Caucasians in the US. In males, these values, except for serum BC values, were also highest among Japanese in Japan. Moreover, serum values of n-3 polyunsaturated fatty acids (n-3PUFAs) such as eicosapentaenoic acid and docosahexaenoic acid were significantly higher among Japanese in Japan than among Japanese and Caucasians in the US in both sexes. In contrast, serum values of n-6 polyunsaturated fatty acids such as linoleic acid and arachidonic acid were lowest among Japanese in Japan. For women, serum levels of n-9 unsaturated fatty acids were lowest among Japanese living in Japan. Serum TBARS values were highest among Japanese in Japan, followed by Japanese in the US and Caucasians in the US. A significant positive correlation was observed between serum values of TBARS and n-3 PUFAs among Japanese both in Japan and in the US. Serum TBARS values showed a significant inverse relationship with the serum values of BC and ZL among Japanese in Japan and with those of BC among Japanese in the US. These relationships were not always observed among Caucasians in the US. The results of this study suggest that the high TBARS values among Japanese in Japan may depend in part on lipid peroxidation induced in vitro by n-3PUFAs, while high reduction of lipid peroxidation could be expected among Japanese in Japan with high antioxidants such as BC and ZL. In conclusion, serum levels of nonprovitamin A carotenoids such as ZL may be a useful intake marker of vegetables. Dietary intakes of dark green vegetables and fish rich in n-3PUFAs might be more important in the prevention of some sites of cancer and of ischemic heart disease.

Aged↗