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T Nagakura

Publications and source records attributed to T Nagakura.

At least 19 recordsLinked to original sources
PubMed2001

Improved glucose tolerance via enhanced glucose-dependent insulin secretion in dipeptidyl peptidase IV-deficient Fischer rats.

Glucagon-like peptide-1 (GLP-1) is an incretin, which induces glucose-dependent insulin secretion. GLP-1 is rapidly degraded by dipeptidyl peptidase IV (DPPIV) after its release. We investigated whether DPPIV-deficient F344/DuCrj rats show improved glucose tolerance when compared with DPPIV-positive F344/Jcl rats. Oral glucose tolerance test indicated improved glucose tolerance in F344/DuCrj rats, but blood glucose levels of the two strains were almost the same 120 min after the glucose bolus. Valine-pyrrolidide, a DPPIV inhibitor, had no effect on the glucose tolerance of F344/DuCrj rats, but improved that of F344/Jcl rats. Enhanced insulin secretion and high plasma active GLP-1 levels were detected in an intraduodenal glucose tolerance test. Glucose tolerance is improved in DPPIV-deficient F344/DuCrj rats via enhanced insulin release mediated by high active GLP-1 levels. Our results suggest that DPPIV inhibition is a rational strategy to treat diabetic patients by improving glucose tolerance with low risk of hypoglycemia.

Animals↗
PubMed2000

Smoking and oxidant stress: assay of isoprostane in human urine by gas chromatography-mass spectrometry.

Isoprostane (8-epi-prostaglandin F2alpha) is synthesized non-enzymatically from arachidonate and active oxygen. We examined the relationship of smoking and excretion of isoprostane in urine with gas chromatography-mass spectrometry selected ion monitoring assay and the stable isotope dilution method. Urine isoprostane concentrations were significantly higher in smokers (n=81, 605.24+/-59.01 ng/mg creatinine) than in non-smokers (n=39, 424.07+/-70.37 ng/mg creatinine), but concentrations in ex-smokers (n=21, 487.27+/-98.48 ng/mg creatinine) did not differ significantly from those in the other groups. In smokers, age, the duration of smoking, and the number of cigarettes per day were not correlated with urine isoprostane concentrations. However, urine isoprostane concentrations were negatively correlated with time since quitting in ex-smokers and with age in non-smokers. These results indicate that smoking increases isoprostane concentration in urine and suggest that smoking causes lipid peroxidation by oxidant stress.

Adult↗
PubMed2000

Vasorelaxant effect of a phosphodiesterase 3 inhibitor, olprinone, on isolated human radial artery.

The radial artery is currently used as a viable arterial conduit for myocardial revascularization. The aims of this study were to identify phosphodiesterase 3 isoenzyme in the human radial artery isolated for coronary artery bypass grafting, and to examine the vasorelaxant effect of a cardiotonic and vasodilating phosphodiesterase 3 inhibitor, 1, 2-dihydro-6-methyl-2-oxo-5-(imidazo[1,2-a]pyridin-6-yl)-3-pyridine carbonitrile hydrochloride monohydrate (olprinone). The phosphodiesterase 3 isoenzyme was separated from the radial artery by DEAE-Sepharose chromatography. Olprinone inhibited the phosphodiesterase 3 activity with an IC(50) value of 1.25 microM. Olprinone relaxed the phenylephrine-induced contractions of endothelium-denuded arterial strips with an EC(50) value of 0. 107+/-0.029 microM (n=5). These findings indicate that the human radial artery possesses phosphodiesterase 3 isoenzyme activity and olprinone causes potent relaxation of the arterial strip in vitro through inhibition of phosphodiesterase 3 isozyme activity.

Endothelium, Vascular↗
PubMed2000

Dietary supplementation with fish oil rich in omega-3 polyunsaturated fatty acids in children with bronchial asthma.

Omega-3 polyunsaturated fatty acids have anti-inflammatory effects in vitro, and high dietary levels are associated with a lower incidence of inflammatory diseases. However, only limited effects have been demonstrated in asthma. The effects of dietary supplementation with fish oil for 10 months in 29 children with bronchial asthma was investigated in a randomized controlled fashion. In order to minimize the effects of environmental inhaled allergens and diet, this study was performed in a long-term treatment hospital. Subjects received fish oil capsules containing 84 mg eicosapentaenoic acid (EPA) and 36 mg docosahexaenoic acid (DHA) or control capsules containing 300 mg olive oil. The daily dosages of EPA and DHA were 17.0-26.8 and 7.3-11.5 mg x kg body weight(-1), respectively. Asthma symptom scores decreased and responsiveness to acetylcholine decreased in the fish oil group but not in the control group. In addition, plasma EPA levels increased significantly only in the fish oil group (p<0.0088). No significant side-effects were observed. The present results suggest that dietary supplementation with fish oil rich in the omega-3 polyunsaturated fatty acids eicosapentaenoic acid and docosahexaenoic acid is beneficial for children with bronchial asthma in a strictly controlled environment in terms of inhalant allergens and diet.

Acetylcholine↗
PubMed2000

Attachment-inducing capacities of fish tissue extracts on oncomiracidia of Neobenedenia girellae (Monogenea, Capsalidae).

When oncomiracidia of Neobenedenia girellae (Monogenea, Capsalidae) were incubated in wells with lyophilized extracts of fish skin epithelia on the bottom, some attached to the well bottom with the haptor unfolded and shed the ciliated epidermal cells. Based on these morphological changes in oncomiracidia, we developed a new assay method to examine the attachment-inducing capacities of various fish extracts for oncomiracidia. Attachment-inducing capacities were found only in extracts of fish skin epithelium and not in other fish extracts. No significant difference in capacities was observed among extracts of skin epithelia of 4 fish species. Wheat germ lectin and concanavalin A suppressed capacities in extracts of skin epithelia of Japanese flounder and yellowtail, respectively. Suppressed capacities were recovered by adding sugars that bound specifically to these lectins. These results indicate that some sugar-related chemical substances that exist specifically in fish epithelium induce the attachment of N. girellae oncomiracidia.

Adhesiveness↗
PubMed1999

Simultaneous assay of prostaglandins and thromboxane in the cerebrospinal fluid by gas chromatography-mass spectrometry-selected ion monitoring.

A method of simultaneous analysis of prostaglandins (PGs) and thromboxane (TX) B2 in cerebrospinal fluid (CSF) with GC-MS-SIM was established. Deuterated PGs and TXB2 were used as internal standards: tetra-deuterated PGE2 (d4-PGE2) for PGE2, PGE1 and PGD2; d5-PGF2alpha for PGF2alpha and 9alpha,11beta-PGF2 and 8-epi PGF2alpha; d4-TXB2 for TXB2; and d4-6-keto PGF1alpha for 6-keto PGF1alpha. The PGs and TXB2 were derivatized to the methyl ester of the methoxim dimethyisopropylsilyl (DMiPSi) ether form or the methyl ester of the DMiPSi ether form with simultaneous preparation. Samples were extracted with octadecyl silica gel and purified in two steps with silisic acid gel chromatography between derivatization steps. The calibration curve of each PG and TXB2 was linear from 10 pg to 10 ng with the isotope dilution method. The levels of the seven types of PG and of TXB2 were assayed simultaneously in the cerebrospinal fluid (CSF) from patients with aseptic meningitis. The CSF pattern of the PG and TXB2 concentrations in mumps meningitis differed from those in other types of aseptic meningitis and in disease controls.

Calibration↗
PubMed1999

Eicosapentaenoic acid inhibits prostaglandin D2 generation by inhibiting cyclo-oxygenase-2 in cultured human mast cells.

BACKGROUND: Eicosapentaenoic acid (EPA) is catalysed by cyclo-oxygenase (COX), as is arachidonic acid, and is a competitive inhibitor of arachidonate metabolism. OBJECTIVES: We examined the effect of EPA on prostaglandin (PG) D2 generation in the cultured human mast cells with IgE-anti-IgE challenge incubation. METHODS: Cultured human mast cells were incubated with EPA (1 micromol/L) for 20 h, then challenged with anti-IgE incubation after treatment with IgE. At the same time, COX inhibitors were tested to identify COX-1 and COX-2 activity. PGD2 synthetic activity was also assayed in a cell-free homogenate of cultured mast cells with COX inhibitors and EPA. Histamine in the culture medium and in cells was assayed with the HPLC-fluorescent method. PGD2 and PGD3 were assayed with gas chromatography-mass spectrometry and the stable isotope dilution method. RESULTS: Although EPA incubation did not affect histamine release by cultured human mast cells in response to IgE-anti-IgE challenge incubation, it did decrease PGD2 generation by inhibiting the COX-2 pathway. In contrast, in the cell-free homogenate of cultured human mast cells, EPA inhibited both COX-1 and COX-2 activities. CONCLUSION: Pre-incubation with EPA primarily affects the COX-2 pathway in cultured human mast cells and reduces PGD2 generation in response to IgE-anti-IgE challenge incubation. These findings suggest that COX-1 and COX-2 have different substrate flow systems in mast cells. They also suggest that endogenous EPA diet supplementation would reduce PGD2 production and could serve as an anti-inflammatory substrate in human mast cells.

Antibodies↗
PubMed1998

GC/MS analysis of urinary excretion of 9alpha,11beta-PGF2 in acute and exercise-induced asthma in children.

BACKGROUND: 9Alpha,11beta-prostaglandin (PG) F2 is an initial metabolite of PGD2 which has a potent bronchoconstrictive activity. OBJECTIVES: We measured the urinary levels of 9alpha,11beta-PGF2 in asthmatic children to investigate its role in not only acute asthmatic attack in a time course study but also in exercise-induced asthma (EIA). METHODS: In the acute asthma study, 30 asthmatic children were examined. Urine samples were collected on the first, third, and sixth days. Urinary levels of 9alpha,11beta-PGF2 were measured with gas chromatography mass spectrometry using the electron impact method. In the exercise challenge study, 14 children with EIA and 14 children without EIA were studied. Urine samples were collected before exercise challenge, and at 1 h, and 5 h after exercise challenge. Urinary levels of 9alpha,11beta-PGF2 were measured. RESULTS: Elevated urinary levels of 9alpha,11beta-PGF2, which were observed on the first day when treatment was started in the hospital, were gradually decreased on the third day (P < 0.05), and on the sixth day (P < 0.01). A significant correlation between urinary levels of 9alpha,11beta-PGF2 and symptom scores (P < 0.005) was observed on the first day. In EIA, there was a significant increase in urinary levels of 9alpha,11beta-PGF2 at 1 h (P < 0.01) and at 5 h (P < 0.01) after exercise challenge, but not in the children without EIA. CONCLUSION: 9Alpha,11beta-PGF2 may be involved in the pathogenesis of acute and exercise-induced asthma in children.

Acute Disease↗
PubMed1997

Catalytic and structural importance of Gly-454, Tyr-455, and Leu-456 in the carboxy-terminal region of Escherichia coli F1-ATPase alpha subunit.

Monoclonal antibody alpha110 recognizes Leu-456 in the alpha subunit of the Escherichia coli F1-ATPase. Binding of this antibody to the alpha subunit or mutation of this residue to Pro caused enhancement of the ATPase activity, suggesting that this residue is involved in the catalytic mechanism of this molecule (H. Kanazawa et al. (1995) Arch. Biochem. Biophys. 317, 348-356). Leu-456 together with Gly-454 and Tyr-455 are the only residues in the carboxy-terminal 75 amino acids conserved among various species, suggesting that these three residues play important roles in catalysis by the ATPase. Here, we introduced site-directed mutations into these residues. Not only L456P but also G454L, Y455K, Y455L, and L456N mutations caused enhancement of the ATPase activity. Surprisingly, Y455V, L456H, and L456S caused assembly defects of F1 subunits on the membrane. Reconstitution of the alpha betagamma complex from the wild-type beta and gamma subunits with the mutant alpha subunit (L4gamma6P) exhibited enhanced ATPase activity. Addition of delta or epsilon fused to glutathione S-transferase which are functionally similar to the delta and epsilon subunits, respectively, to the reconstituted F1-ATPase did not cause significant enhancement of its activity. Decreased interaction between alpha and beta subunits with the L456P mutation was detected by the yeast two-hybrid system. According to the deduced three-dimensional structure of the bovine a subunit, Leu-456, Gly-454, and Tyr-455 are included in a small alpha helix. These results suggest that this alpha helix affects interaction of the alpha subunit with the beta subunit but not with delta or epsilon, which may be important for the catalytic mechanism and F1 assembly.

Amino Acid Sequence↗
PubMed1996

IgE-anti-IgE-induced prostaglandin D2 release from cultured human mast cells.

To elucidate the characterization of cultured human mast cells, the generation of prostaglandin D2 (PGD2) upon stimulation with IgE-anti IgE challenge was determined by using gas chromatography/mass spectrometry/selected ion monitoring (GC/MS/SIM) assay. Mononuclear cells obtained from human umbilical cord blood were cultured in the presence of Steel Factor, IL-6, and PGE2. After 8 weeks of culture, approximately 90 to 95% of cultured cells became tryptase-positive and included basophilic granules. At 12 weeks of culture, cells were harvested and incubated with 1 microgram/ml of human IgE for 1 hr and then challenged with 10 micrograms/ml of anti-IgE. The level of PGD2 release into the supernatant was measured by GC/MS/SIM with the stable isotope dilution method. Cyclooxygenase inhibitors affected the PGD2 release from the cell by IgE-anti IgE challenge incubation. Indomethacin inhibited 98% of PGD2 release. Acetylsalicylic acid (aspirin) and NS-398 (potent COX-2 inhibitor) also inhibited PGD2 release by 85 and 45% respectively.

Antibodies, Anti-Idiotypic↗
PubMed1996

Reconstitution of the F1-ATPase activity from purified alpha, beta, gamma and delta or epsilon subunits with glutathione S-transferase fused at their amino termini.

Systems for overexpression and purification of active alpha, beta and gamma subunits of Escherichia coli H(+)-ATPase were established. The alpha and beta subunits recovered as soluble form were purified by hydroxyapatite column chromatography. Since the gamma subunit was overexpressed as the insoluble form, this subunit was purified by polyacrylamide gel-electrophoresis containing sodium dodecyl sulfate. By subsequent denaturation of this subunit with guanidine hydrochloride and renaturation, the active gamma subunit for reconstitution of the F1-ATPase activity with the purified alpha and beta subunit was obtained. The delta and epsilon subunits which were fused to the carboxy terminus of glutathione S-transferase (GST) were overproduced and purified by affinity chromatography. These fused proteins (delta-GST and epsilon-GST) were incubated with the purified alpha, beta and gamma subunits and applied to affinity chromatography. The alpha beta gamma delta-GST and alpha beta gamma epsilon-GST complex were eluted specifically by addition of glutathione and exhibited high and low ATPase activity, respectively, with a subunit stoichiometry similar to that in the native F1-ATPase, indicating that active complexes could be reconstituted with the fused proteins. These results suggested that the amino-terminal ends of the delta and epsilon subunits are not involved in formation of the active complex. The fused epsilon-GST bound the gamma subunit strongly, and the alpha subunit weakly. The delta-GST bound the gamma subunit significantly, and the alpha and beta subunits very weakly.

Base Sequence↗
PubMed1996

Major Dermatophagoides mite allergen, Der 1, in soft toys.

BACKGROUND: Allergen avoidance is recommended when treating atopic asthma. OBJECTIVES: Soft toys are often kept in close proximity to children and may serve as a source of exposure. Due to the potential danger from the mite allergen content of these toys, Der 1 from toys was measured. METHODS: We quantified the level of Der 1 (Der p 1 + Der f 1) in both 30 new and 174 old soft toys (weight 216 +/- 2.5 g, height 26.5 +/- 3.4 cm), as well as in washed and in vacuumed soft toys. Dust was collected using an electric vacuum cleaner. Der 1 was measured by monoclonal antibody-based enzyme-linked immunosorbent assay (MoAb-ELISA). RESULTS: In brand new toys Der 1 was 0.1 microgram/g of dust, and in toys used for 1 year, 9.0; 2 year, 22.2; 3 year, 18.9; and more than 4 year, 22.7 micrograms/g of dust. Der 1 in new toys was measured every 4 months for 1 year. Der 1 rapidly increased 10- to 20-fold in the first 4 months, but there was no clear seasonal change. In toys washed using a chemical detergent or cleaned using a vacuum cleaner, there was a stastistically significant (P < 0.001) decrease in Der 1 in the washed group, but not in the vacuumed group. CONCLUSION: These results confirm that mite allergens accumulate rapidly in toys to form a potentially important source of allergens and that washing toys with a chemical detergent is effective in the reduction of allergens.

Allergens↗
PubMed1994

Determination of 9 alpha, 11 beta-prostaglandin F2 in human urine and plasma by gas chromatography-mass spectrometry.

Sensitive and specific assay methods for 9 alpha, 11 beta-prostaglandin F2 (9 alpha, 11 beta-PGF2) by gas chromatography-mass spectrometry with electron impact ionization are described. The mass spectrometric assay for 9 alpha, 11 beta-PGF2 was based on the use of the methyl ester-dimethylisopropylsilyl ether derivative, and pentadeuterated PGF2 alpha as a convenient internal standard. The calibration graph for 9 alpha, 11 beta-PGF2 was linear from 5 pg to 100 ng for both the standard and spiked biological samples. The limit of detection was 50 pg/ml for urine and 25 pg/ml for plasma (signal-to-noise ratio = 2.3). The method was applied to the determination of 9 alpha, 11 beta-PGF2 in urine and plasma samples from patients with bronchial asthma.

Adolescent↗
PubMed1992

[Clinical significance of IgG4 antibody determination in children against egg white, milk, soybean and Dermatophagoides farinae].

The measurement of IgE and IgG4 antibodies against egg white, milk, soybean and Dermatophagoides farinae was performed by FAST (fluorescence allergosorbent test) using 21 serum samples obtained from non-allergic children and 160 serum samples from atopic children with bronchial asthma and/or atopic dermatitis. Their antibody levels were evaluated for any association with disease severity and for clinical significance in establishing diagnosis. It was found that children with bronchial asthma showed lower levels of IgE antibodies against egg white, milk and soybean and higher levels of IgE antibodies against Dermatophagoides farinae compared with those of children with atopic dermatitis, while both groups showed higher levels of egg white and milk-specific IgG4 antibodies compared with non-allergic children. These IgE and IgG4 antibody levels revealed a tendency to correlate with disease severity in patients with atopic dermatitis, while this was not observed in patients with bronchial asthma. The contribution percentages of IgG4 antibody determination, together with IgE antibody determination, in retrieving causal allergens were 71% for egg white, 70% for milk and 48% for soybean allergy, implying their diagnostic value in establishing clinical diagnosis.

Adolescent↗
PubMed1992

[The effect of sustained-release theophylline granules in the inhibition of exercise-induced asthma].

We studied the protective effect of sustained-release theophylline granules on early or late response in exercise-induced asthma (EIA) in 16 patients ranging in age from 7 to 18 years. A standardized exercise test was examined 2 hours after administration of theophylline granules on one day and after no medication on another day. On both days, the lung functions and the serum theophylline and cortisol concentrations of the patients were examined before exercise and over a period of 8 hours after exercise. On days without medication, early response was seen in 16 patients and late response in 6. On days with medication, the theophylline granules inhibited early response in 13 of the 16 patients and late response in 5 of the 6 patients. This suggests that theophylline preparation is a useful drug for inhibiting the dual responses of EIA.

Adolescent↗