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Biomedical subjects

T Yoshimura

Publications and source records attributed to T Yoshimura.

At least 109 records · Page 6Linked to original sources
PubMed1997

In vivo ESR-CT imaging of the liver in mice receiving subcutaneous injection of nitric oxide-bound iron complex.

ESR measurements and ESR-CT imaging of subcutaneously (SC) injected nitric oxide (NO)-bound iron complexes were conducted on the upper abdomen of live mice. The use of NO-bound iron complex with N-(dithiocarboxy)sarcosine resulted in a clear ESR-CT image showing high intensity areas in the ventral regions, while other NO-bound iron complexes with N-methyl-D-glucamine dithiocarbamate or N,N-diethyl-dithiocarbamate were inappropriate because of low S/N ratios. To investigate the distributions of SC injected NO-bound iron complexes in the abdomens of mice, we measured ESR signals in resected abdominal organs. The signal amplitude was higher in the resected liver than in the resected gastrointestinal organs or the blood samples. The findings suggest that the high intensity areas in the ESR-CT images thus obtained correspond to the liver.

Animals↗
PubMed1997

Chemokine production by human vascular smooth muscle cells: modulation by IL-13.

1. The production of chemokines by vascular smooth muscle cells (SMC) is implicated in the pathogenesis of atherosclerosis, although the factors regulating chemokine production by these cells are incompletely characterized. 2. We describe the differential stimulation of interleukin-(IL)-8, monocyte chemoattractant protein (MCP)-1 and regulated on activation normal T-cell expressed and secreted (RANTES) synthesis following treatment of human vascular SMC with IL-1alpha or tumour necrosis factor alpha (TNFalpha). Under basal conditions, cultured SMC release very low amounts of IL-8, MCP-1 and RANTES as assessed by specific ELISA. Concentration-response studies with IL-1alpha or TNFalpha revealed that each stimulus induced a similar amount of MCP-1. In contrast approximately three fold more IL-8 was induced by IL-1alpha than by TNFalpha whereas significant RANTES production was induced only by TNFalpha. These findings point to a divergence in the regulation of synthesis of the different chemokines in response to IL-1alpha or TNFalpha stimulation. 3. The T-cell derived cytokines IL-10 and IL-13 were also found to have differential effects on chemokine production by SMC. IL-13, but not IL-10, significantly enhanced IL-8 and MCP-1 release in response to IL-1alpha or TNFalpha. This increase in chemokine release appeared to be accounted for by increased mRNA expression. 4. These findings provide support for the concept that smooth muscle cells can have an active role in a local immune response via the production of chemokines which can be selectively modulated by T-cell derived cytokines.

Cells, Cultured↗
PubMed1997

Structure and function of the recombinant fifth domain of human beta 2-glycoprotein I: effects of specific cleavage between Lys77 and Thr78.

In order to elucidate the mechanism of binding of beta 2-glycoprotein I (beta 2-GPI) to cardiolipin (CL), we constructed a high-level expression system for the C-terminal domain (Domain V) of beta 2-GPI using Pichia pastoris and studied its conformation and liposome-binding activity. Purified Domain V was found to have the native disulfide bonds. It had a compactly folded conformation, judging from the circular dichroism spectrum, and exhibited a cooperative unfolding transition induced by pH or urea. Also, it bound liposomes containing CL. Commercially available human beta 2-GPI is known to be selectively cleaved between Lys 317 and Thr 318. We found that bovine factor Xa weakly but specifically cleaves the corresponding site of recombinant Domain V, i.e., the peptide bond between Lys 77 and Thr 78. The conformation of the "nicked" Domain V, which was cleaved at this site, was examined by circular dichroism and fluorescence measurements, and concluded to be similar to that of the intact protein. The stability of the nicked Domain V to urea was slightly lower than that of the intact protein. Although both Domains V bound to liposomes containing CL, the affinity of the nicked Domain V was greatly reduced in comparison with the intact protein, indicating that the cleavage of the peptide bond between Lys 77 and Thr 78 controls the binding to CL. In addition, analysis of the fluorescence spectra in the presence and absence of CL liposomes indicated that Trp 76 is involved in the binding site. These results suggest that the region including Trp 76, Lys 77, and Thr 78 has a critical role in binding to CL.

Amino Acid Sequence↗
PubMed1997

Cloning and expression of the glutamate racemase gene of Bacillus pumilus.

A glutamate racemase gene (murI) was found in Bacillus pumilus cells and cloned into Escherichia coli WM335, a D-glutamate auxotroph, by means of a genetic complement method. MurI of B. pumilus encodes a 272-amino acid protein with an unusual initiation codon, TTG. The deduced amino acid sequence shows significant similarity with those of glutamate racemases from E. coli (ratio of identical residues, 28%), Pediococcus pentosaceus (44%), and Staphylococcus haemolyticus (49%). B. pumilus MurI was expressed as a fusion protein connected to the N-terminal 12 residues of beta-galactosidase; the fusion protein showed glutamate racemase activity, and resembled the enzyme of P. pentosaceus in physicochemical and enzymological properties.

Amino Acid Isomerases↗
PubMed1997

Mutation of arginine 98, which serves as a substrate-recognition site of D-amino acid aminotransferase, can be partly compensated for by mutation of tyrosine 88 to an arginyl residue.

D-Amino acid aminotransferase is the only aminotransferase that catalyzes the transamination of D-amino acids. We studied the role of the binding site for the alpha-carboxyl group of substrates, which is presumably crucial for the unique stereospecificity of the enzyme. The site-directed mutagenesis of Arg98, which is the putative carboxyl-binding site, as judged on the basis of X-ray crystallographic studies [Sugio, S., Petsko, G.A., Manning, J.M., Soda, K., and Ringe, D. (1995) Biochemistry 34, 9661-9669], by replacement with methionine and lysine, resulted in decreases in the kmax values and increases in the Kd values for both amino donors and amino acceptors. The introduction of another mutation, that of Tyr88, which is located near Arg98 in the spacial structure, by replacement with arginine, in addition to the above Arg98 mutation, resulted in increases in the kmax values but little change in the Kd values. These results suggest that Arg98 constitutes the carboxyl-binding site for the substrate, efficient catalysis by the enzyme being facilitated upon binding. The mutant enzymes are also relieved from inhibition by high concentrations of alpha-ketoglutarate, which is an inherent character of the wild-type enzyme. Therefore, Arg98 is also responsible for the inhibition by alpha-ketoglutarate.

Arginine↗
PubMed1997

The chemokine repertoire of human dermal microvascular endothelial cells and its regulation by inflammatory cytokines.

Activation of endothelium is a critical event during the initiation of inflammatory processes and is associated with the induction of cell adhesion molecules and cytokines. The latter include chemotactically active cytokines (chemokines) that promote leukocyte diapedesis from the circulation to sites of evolving inflammation. In this study we evaluated the chemokine repertoire of human endothelial cells derived from the skin (HDMECs) and regulation of these chemokines by cytokines. HDMECs and an immortalized human dermal microvascular endothelial cell line, HMEC-1, were investigated for the expression of C-X-C and C-C chemokines at mRNA and protein levels. Upon stimulation with interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha), both HDMECs and HMEC-1 expressed high levels of IL-8, GRO, and monocyte chemoattractant protein-1 (MCP-1). RANTES was only weakly induced; however, concomitant treatment with TNF-alpha and interferon-gamma (IFN-gamma) led to upregulation of RANTES, indicating a synergy between these two cytokines. The C-X-C chemokine IFN-inducible protein-10 was upregulated by IFN-gamma but not by other cytokines studied. Macrophage inflammatory protein-1alpha and beta, 1-309, and ENA-78 could not be induced. The chemokine repertoires of HDMECs and HMEC-1 were compared to those of human umbilical vein endothelium and found to be rather similar with the important exception that IFN-gamma and IL-4 up-regulated MCP-1 only in macrovascular endothelium. Our data indicate that HDMECs contribute to the dermal cytokine network by selective production of MCP-1, IL-8, GRO, RANTES, and IP-10, which may critically influence the site-specific recruitment of leukocyte subsets.

Cells, Cultured↗
PubMed1997

Synthesis of optically active amino acids from alpha-keto acids with Escherichia coli cells expressing heterologous genes.

We describe a simple method for enzymatic synthesis of L and D amino acids from alpha-keto acids with Escherichia coli cells which express heterologous genes. L-amino acids were produced with thermostable L-amino acid dehydrogenase and formate dehydrogenase (FDH) from alpha-keto acids and ammonium formate with only an intracellular pool of NAD+ for the regeneration of NADH. We constructed plasmids containing, in addition to the FDH gene, the genes for amino acid dehydrogenases, including i.e., leucine dehydrogenase, alanine dehydrogenase, and phenylalanine dehydrogenase. L-Leucine, L-valine, L-norvaline, L-methionine, L-phenylalanine, and L-tyrosine were synthesized with the recombinant E. coli cells with high chemical yields (> 80%) and high optical yields (up to 100% enantiomeric excess). Stereospecific conversion of various alpha-keto acids to D amino acids was also examined with recombinant E. coli cells containing a plasmid coding for the four heterologous genes of the thermostable enzymes D-amino acid aminotransferase, alanine racemase, L-alanine dehydrogenase, and FDH. Optically pure D enantiomers of glutamate and leucine were obtained.

Alanine Dehydrogenase↗
PubMed1997

Airway inflammation induced by recombinant guinea pig tumor necrosis factor-alpha.

We have cloned and expressed recombinant guinea pig tumor necrosis factor-alpha (gpTNF-alpha) and examined its inflammatory activities after tracheal instillation in guinea pigs. A 1,071-bp cDNA, including the region encoding the full-length 234-amino acid gpTNF-alpha protein, was cloned from concanavalin A-stimulated guinea pig splenocytes. The 154-amino acid protein corresponding to secreted gpTNF-alpha was expressed as a fusion protein in Escherichia coli, purified by affinity chromatography, and cleaved to yield a 17-kDa protein. gpTNF-alpha had a cytotoxic effect on WEHI 164 cells and was detected by goat anti-murine tumor necrosis factor-alpha (TNF-alpha) antibody in Western blots. Intratracheal instillation of gpTNF-alpha (50-150 ng) caused pronounced and dose-dependent airway eosinophilia. Incubation of gpTNF-alpha with rabbit anti-murine TNF-alpha sera or heating the gpTNF-alpha before instillation reduced bronchoalveolar lavage (BAL) eosinophils to near control levels. Maximum BAL eosinophilia was observed at 24 h, but eosinophil numbers remained significantly above vehicle-treated animals for 72 h. Hence, gpTNF-alpha elicits a pronounced and protracted eosinophil accumulation in the guinea pig lung.

Amino Acid Sequence↗
PubMed1997

Connexin32 gene expression in rat sciatic nerves and cultured Schwann cells.

A Western blot analysis showed connexin32 (Cx32) to be present in the myelin membrane. Cx32 mRNA rapidly decreased in the distal segments of crushed sciatic nerves and thereafter returned to normal, as did P0 mRNA. Both Cx32 and P0 mRNAs were detectable in cultured Schwann cells and were enhanced by the addition of forskolin. The developmental profile showed that Cx32 mRNA had thus markedly increased by the time that myelination had become most active, and thereafter only slowly increased unlike P0. Cx32 mRNA seems to parallel myelin size, which thus suggests that Cx32 supports myelin maintenance as a gap junction protein that facilitates the intramyelin exchange of small molecules.

Aging↗
PubMed1997

Chromosomal mapping of the gene encoding serotonin N-acetyltransferase to rat chromosome 10q32.3 and mouse chromosome 11E2.

Pineal melatonin is produced during the night. Its nocturnal increase regulates circadian rhythms and the photoperiodic reproductive response. Serotonin is acetylated to N-acetylserotonin by serotonin N-acetyltransferase (SNAT) and then methylated to form melatonin by hydroxyindole-O-methyltransferase (HIOMT). The rhythmicity of melatonin synthesis is regulated by the rhythmic activity of SNAT. Most laboratory mice do not have melatonin because of a genetic defect in the activity of SNAT and/or HIOMT. In a previous study using a recombinant inbred strain, we have found that the locus controlling pineal SNAT activity (Nat4) is located on mouse Chromosome 11. Recently, SNAT has been cloned in the rat. In the present study, the gene encoding SNAT was localized, using a rat cDNA fragment, on rat and mouse chromosomes by direct R-banding fluorescence in situ hybridization (FISH). In addition, using molecular linkage analysis with interspecific backcross mice, a gene encoding SNAT was mapped on a mouse chromosome. The gene encoding SNAT was localized to rat chromosome 10q32.3 and mouse Chromosome 11E2 by FISH. The molecular linkage analysis demonstrated that the gene encoding SNAT maps 1.5 cM distal to D11Mit11. The data suggest that Nat4 encodes SNAT. These chromosomal locations are in a region of conserved linkage homology between the two species.

Animals↗
PubMed1997

Inhibition of tumor necrosis factor-alpha and interleukin-1-beta production by beta-adrenoceptor agonists from lipopolysaccharide-stimulated human peripheral blood mononuclear cells.

The effects of beta-adrenoceptor agonists (beta-agonists) on the production of tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta) and interleukin-8 (IL-8) by lipopolysaccharide (LPS)-stimulated human peripheral blood mononuclear cells (PBMCs) were investigated. The beta-agonists, procaterol, clenbuterol, fenoterol and terbutaline, inhibited TNF-alpha and IL-1 beta production in a concentration-dependent manner, whereas they had no effect on IL-8 production. TNF-alpha production was inhibited more potently than IL-1 beta. Dibutyryl cyclic AMP (dbcAMP) also inhibited the production of TNF-alpha and IL-1 beta, but not IL-8. TNF-alpha production was almost completely inhibited by dbcAMP, whereas IL-1 beta production appeared to be partially refractory even at the highest concentration examined. Both procaterol and theophylline elevated cAMP levels in LPS-stimulated PBMCs, but the effect of procaterol was limited. The inhibition of TNF-alpha and IL-1 beta production by procaterol was additively potentiated with theophylline. dl-Propranolol, a beta-adrenoceptor antagonist, abrogated the inhibition of TNF-alpha and IL-1 beta production by procaterol. These results indicate that beta-agonists inhibit the production of proinflammatory cytokines, such as TNF-alpha and IL-1 beta, by elevating intracellular cAMP levels. These properties of beta-agonists might be beneficial in the treatment of allergic inflammation.

Adrenergic beta-Agonists↗
PubMed1997

Setting Priorities in Occupational Health Research in Vietnam.

To set priorities for occupational health research in Vietnam, the authors developed a questionnaire, using a consensus-conference approach. The questionnaire, which was composed of two parts (five main categories with subgroups), was distributed to 51 specialists in occupational safety and health (OSH) in Vietnam. The responses from 50 persons were analyzed. Among the main categories, the environmental impact of industrial activity was rated the most important, followed by ergonomics and engineering of OSH, incidence/prevalence of work-related diseases and identification of susceptible groups, social impact of industrial activity, and OSH problems of agricultural workers. Among the three problems in the subgroup "environmental impact of industrial activity," individual health effects was considered the most important. These results were evaluated to arrive at an understanding of the actual situation of OSH problems in Vietnam.

Journal Article↗
PubMed1997

Stereospecific formation of (24R,25R)-3 alpha,7 alpha,12 alpha,24-tetrahydroxy-5 beta-cholestan-26-oic acid catalyzed with a peroxisomal bifunctional D-3-hydroxyacyl-CoA dehydratase/D-3-hydroxyacyl-CoA dehydrogenase.

The absolute configuration of 3 alpha,7 alpha,12 alpha, 24-tetrahydroxy-5 beta-cholestan-26-oic acid CoA ester (V-CoA) produced by the incubation of (24E)-3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholest-24-en-26-oic acid CoA ester (24E-THC-CoA) with D-3-hydroxyacyl-CoA dehydratase/D-3-hydroxyacyl-CoA dehydrogenase (D-bifunctional protein) was investigated. When 24E-THC-CoA was incubated with D-bifunctional protein the formation of only one isomer (24R,25R-isomer) of four possible stereoisomers of V-CoA was observed, which suggested the cis-addition of water to a side chain double bond of 24E-THC-CoA. The dehydration reaction of V-CoA catalyzed by D-bifunctional protein was also observed when (24R,25R)-V-CoA was used as a substrate. The other three isomers (24R,25S-, 24S,25R- and 24S,25S-isomers) were not dehydrated with D-bifunctional protein. These results showed that D-bifunctional protein catalyzes stereospecifically the hydration and dehydration step in bile acid biosynthesis.

17-Hydroxysteroid Dehydrogenases↗
PubMed1997

Inhibition by hop bract polyphenols of cellular adherence and water-insoluble glucan synthesis of mutans streptococci.

The inhibitory effect of hop bract polyphenols (HBP) on cariogenic streptococci was investigated. It was found that the high molecular weight polyphenol (estimated about 36,000-40,000) inhibited the cellular adherence of Streptococcus mutans MT8148 (serotype C) and Streptococcus sobrinus ATCC 33478 (serotype g) at much small concentrations than the polyphenols extracted from oolong tea or green tea leaves. Furthermore, HBP also inhibited the action of glucosyltransferase, which was involved in the water-insoluble glucan synthesis, but did not suppress the growth and the acid production of the bacteria. These results suggest that HBP would be a candidate to act against dental caries caused by Mutans Streptococci.

Bacterial Adhesion↗
PubMed1997

Association between self-reported stressful feeling by SACL and mortality in a Japanese community.

A cohort study consisting of 4,291 residents of a Japanese community has been conducted since 1987. The associations between stressful feelings measured by Stress Arousal Checklist (SACL) and mortality of all causes and cancer were examined. The relative risks (RRs) for mortality for 7 years for high stressful state (SACL score: 7-17) and moderate stressful state (3-6) subjects compared with low stressful state subjects (0-2) were 1.1 (95% CI = 0.69-1.68), 1.3 (95% CI = 0.85-2.00) for all causes and 1.5 (95% CI = 0.80-2.99), 1.3 (95% CI = 0.67-2.61) for cancer respectively, after being adjusted for sex, age, smoking, drinking, exercise and medical-care use. When each item of the SACL was examined independently, six out of 17 items of SACL which were "not comfortable", "not contented", "not cheerful", "dejected", "nervous", "not pleasant" showed elevated RRs for all causes of mortality with statistical significance (RRs: 1.4, 1.4, 1.7, 1.7, 1.5, 1.5, respectively), after being adjusted for the possible confounding factors stated above. Especially, the adjusted RRs of "not cheerful" and "dejected" for all causes was 1.7 (95% CI = 1.20-2.33), 1.7 (95% CI = 1.17-2.46), respectively. The results suggested that stressful feelings of "not cheerful" and "dejected" might increase mortality.

Adult↗
PubMed1997

[Effect of worksite dental health program on periodontal status--evaluation by CPITN and bleeding on probing at each tooth].

A dental health promotion program which aimed to prevent periodontal disease was carried out at a shipyard in Nagasaki Prefecture. Repeated tooth cleaning instruction and prophylaxis were conducted in order to adopt proper oral hygiene habits. The first 3 months of this program included 'Initial instruction,' and 'Regular instruction' were given every 6 months in following 2 years. The oral examination was carried out before and after Initial instruction, and at each Regular instruction. The effect of this program was evaluated by 2 measures: CPITN and Bleeding on probing. After this program, the rate of teeth with pockets 4 -5 mm deep or deeper (CPITN 3, 4) was decreased. In contrast, the rate of teeth with no sign of periodontal disease (CPITN 0) was increased remarkably: the percentage increased from 8% preinitial instruction to 40% with regular instruction. Both the rate and grade of teeth with bleeding on probing were decreased. These results indicated that this program was helpful in improving the periodontal status. CPITN and Bleeding on probing at each tooth as an evaluation measure made our analysis more detailed.

Health Education, Dental↗