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H Nakazawa

Publications and source records attributed to H Nakazawa.

At least 73 records · Page 4Linked to original sources
PubMed2001

[Cause of bisphenol A migration from cans for drinks and assessment of improved cans].

In the previous investigation, we found that some cans for coffee and black tea drinks released large amounts of bisphenol A (BPA) into their contents. Equivalent cans were obtained and the cause of BPA migration was investigated. Equivalent cans A, B and D contained high levels of BPA in the side seam, in the bottom, and in the bottom and the side seam, respectively, while can C contained some level of BPA in the body, which has a large area, therefore, all of them contained high amounts of BPA in their coatings. In the migration test, there was no BPA migration from the cans into water at 60 and 95 degrees C for 30 min, into 20% ethanol at 60 degrees C for 30 min, or into n-heptane at 25 degrees C for 60 min. However, at 120 degrees C for 30 min, equivalent cans released 35-124 ng/mL BPA into the water. The total migration was similar to the total residues of BPA in the can coating and was close to the total amount of BPA in the drinks. Thus, BPA migration from the can coating requires heating to more than 105 degrees C, which is the glass transition temperature of the epoxy resin. Improved cans which contained less than 1/10 as much BPA as the equivalent cans showed very low migration levels, i.e., 3-6 ng/mL.

Benzhydryl Compounds↗
PubMed2001

[Detection of O,O,S-trimethyl phosphorodithioate, an impurity in phenthoate (PAP), in komatsuna].

An unknown peak (peak A) was detected in a mass chromatogram of komatsuna extract containing a high concentration of phenthoate (PAP), and it was considered to be O,O,S-trimethyl phosphorodithioate (OOS). Although it is generally known that OOS exists as an impurity in technical malathion and PAP, it has not been reported that OOS is present in crops. Since an OOS standard is not commercially available, OOS was separated and purified from commercial emulsifiable malathion. Peak A was confirmed to be OOS by GC/MS using the purified OOS. The concentration of OOS was estimated to be 0.02 microgram/g. It is supposed that OOS was detected in crops because they contained a high concentration of PAP residue.

Chromatography, Gas↗
PubMed2001

[Determination of streptomycin and dihydrostreptomycin in meat by liquid chromatography/mass spectrometry].

A sensitive and selective method using liquid chromatography-electrospray mass spectrometry (LC-ESI-MS) for the determination of aminoglycoside antibiotics, streptomycin and dihydrostreptomycin, in meat has been developed. The LC separation was performed on a TSK-gel Super ODS column (10 cm x 2 mm i.d.) using 5 mmol/L heptafluoro-n-butyric acid (HFBA)-acetonitrile (88:12) as the mobile phase at a flow rate of 0.18 mL/min. The positive ionization produced typical [M + H]+ molecular ions of both drugs (streptomycin m/z 582; dihydrostreptomycin m/z 584). The calibration graphs for streptomycin and dihydrostreptomycin were rectilinear from 0.25 to 25 ng with selected ion monitoring (SIM). The drugs were extracted with 1% metaphosphoric acid, and the extracts were added to 2 mL of 0.1 mol/L heptanesulfonic acid. The solution was cleaned up on a Bond Elut C18 (500 mg) cartridge. The recoveries of streptomycin and dihydrostreptomycin from swine and bovine muscle fortified at 0.2 microgram/g were 73.2-82.6%, and the detection limits were 0.01 microgram/g for both drugs.

Animals↗
PubMed2000

Determination of bisphenol A in human serum by high-performance liquid chromatography with multi-electrode electrochemical detection.

A simple and sensitive method using high-performance liquid chromatography with multi-electrode electrochemical detection (HPLC-ED) including a coulometric array of four electrochemical sensors has been developed for the determination of bisphenol A in water and human serum. For good separation and detection of bisphenol A, a CAPCELL PAK UG 120 C18 reversed-phase column and a mobile phase consisting of 0.3% phosphoric acid-acetonitrile (60:40) were used. The detection limit obtained by the HPLC-ED method was 0.01 ng/ml (0.5 pg), which was more than 3000-times higher than the detection limit obtained by the ultraviolet (UV) method, and more than 200-times higher than the detection limit obtained by the fluorescence (FL) method. Bisphenol A in water and serum samples was pretreated by solid-phase extraction (SPE) after removing possible contamination derived from a plastic SPE cartridges and water used for the pretreatment. A trace amount (ND approximately 0.013 ng/ml) of bisphenol A was detected from the parts of cartridges (filtration column, sorbent bed and frits) by extraction with methanol, and it was completely removed by washing with at least 15 ml of methanol in the operation process. The concentrations of bisphenol A in tap water and Milli-Q-purified water were found to be 0.01 and 0.02 ng/ml, respectively. For that reason, bisphenol A-free water was made to trap bisphenol A in water using an Empore disk. In every pretreatment, SPE methods using bisphenol A-free water and washing with 15 ml of methanol were done in water and serum samples. The yields obtained from the recovery tests using water to which 0.5 or 0.05 ng/ml of bisphenol A was added were 83.8 to 98.2%, and the RSDs were 3.4 to 6.1%, respectively. The yields obtained from the recovery tests by OASIS HLB using serum to which 1.0 ng/ml or 0.1 ng/ml of bisphenol A was added were 79.0% and 87.3%, and the RSDs were 5.1% and 13.5%, respectively. The limits of quantification in water and serum sample were 0.01 ng/ml and 0.05 ng/ml, respectively. The method was applied to the determination of bisphenol A in healthy human serum sample, and the obtained detection was 0.32 ng/ml. From these results, the HPLC-ED method should be the most useful in the determination of bisphenol A at low concentration levels in water and biological samples.

Benzhydryl Compounds↗
PubMed2000

High-performance liquid chromatography with peroxyoxalate chemiluminescence detection of bisphenol A migrated from polycarbonate baby bottles using 4-(4,5-diphenyl-1H-imidazol-2-yl)benzoyl chloride as a label.

A highly sensitive and selective high-performance liquid chromatographic method with peroxyoxalate chemiluminescence detection for the determination of bisphenol A at sub-ppb levels is described. Bisphenol A was derivatized with 4-(4,5-diphenyl-1H-imidazol-2-yl)benzoyl chloride and the excess unreacted reagent was removed by a simple solid-phase extraction procedure with recoveries of approximately 60%. The separation was carried out isocratically on an ODS column and the derivatized bisphenol A was detected by peroxyoxalate chemiluminescence. A mixture of bis[2-(3,6,9-trioxadecanyloxycarbonyl)-4-nitrophenyl]oxalate (0.6 mM) and hydrogen peroxide (25.0 mM) dissolved in acetonitrile was used as a chemiluminescence reagent solution with a mixture of imidazole-HNO3 buffer (40.0 mM, pH 7.0): acetonitrile (17:83, v/v) as a mobile phase. The linear standard curve was obtained over the range from 0.57 (2.5) to 22.8 (100) ppb (nM) (r=0.996) with a detection limit of 0.38 ppb (2.8 fmol on column) at a signal-to-noise ratio of 3. The method was successfully applied to the determination of bisphenol A in hot water in contact with commercially available baby bottle samples.

Benzhydryl Compounds↗
PubMed2000

Decreased protein kinase C-epsilon expression in hypertrophied cardiac ventricles induced by triiodothyronine treatment in the rat.

To examine the effect of thyroid hormone-induced cardiac hypertrophy on PKC expression, changes in the expression of PKC isoforms were studied in hypertrophied cardiac ventricles induced by triiodothyronine (T3) injection in the rat. Injection with T3 for 8 days induced 49% increase in cardiac weight compared to controls. Immunoblot analysis of cardiac ventricular extracts showed the expression of PKC-delta, -epsilon, and -zeta in both control and T3-treated groups. The expression of PKC-epsilon decreased by 40% in hyperthyroid rat cardiac ventricles, while PKC-delta and -zeta expressions were barely affected. PKC-epsilon immunoreactivity decreased in both cytosol and membrane fractions. On the contrary, PKC-epsilon expression did not decrease in the extract of hypertrophied cardiac ventricles produced by aortic banding or aortocaval shunt. These results indicate that thyroid hormone down regulates PKC-epsilon expression in the hyperthyroid-mediated cardiac hypertrophy.

Animals↗
PubMed2000

Simultaneous determination of triclabendazole and its sulphoxide and sulphone metabolites in bovine milk by high-performance liquid chromatography.

A simple method has been developed for the simultaneous determination of triclabendazole and its metabolites (sulphoxide and sulphone) in bovine milk by reversed-phase high-performance liquid chromatography (HPLC). A milk sample was homogenized with sodium sulfate anhydrous and acetonitrile, and centrifuged. The supernatant was isolated, rinsed with n-hexane saturated with acetonitrile, and evaporated. The residue was dissolved with 0.1 M potassium dihydrogenphosphate, and 0.1 M sodium hydrogencarbonate, and then cleaned up on a Bond Elut C18 cartridge. The three compounds were separated on a Capcell Pak C18 UG 120 (5 microm, 150x4.6 mm I.D.) column and determined by UV detection at 295 nm. The mobile phase was acetonitrile-0.05 M ammonium acetate (50:50), and the flow-rate was 0.8 ml/min at 40 degrees C. The mean recoveries (n=4) were 89.1-95.0% with a relative standard deviation of 1.1-2.6%. The detection limits were 0.004-0.006 microg/g in milk. The proposed method was used to monitor raw milk samples for the market, and applied to the analysis of milk samples from 10 cows which had been administered with triclabendazole to control the liver fluke. The confirmation of the triclabendazole and its metabolites in the above milk sample has been achieved by electrospray LC-MS for the first time.

Animals↗
PubMed2000

Determination of trenbolone and zeranol in bovine muscle and liver by liquid chromatography-electrospray mass spectrometry.

A sensitive and selective method using liquid chromatography (LC)-electrospray mass spectrometry for the determination of growth promoters, trenbolone and zeranol, in bovine muscle and liver has been developed. The LC separation was performed on a Zorbax XDB-C18 column (150x2.1 mm I.D.) using 0.005% acetic acid-acetonitrile (60:40, v/v) as the mobile phase at a flow-rate of 0.2 ml/min. The positive ionization produced typical (M+H)+ molecular ions of alpha-trenbolone and beta-trenbolone. On the other hand, the negative mode produced (M-H)- ion of zeranol. The calibration graphs for alpha-trenbolone, beta-trenbolone and zeranol were rectilinear from 2.5 pg to 1.0 ng with selected ion monitoring. The drugs were extracted with 0.2% metaphosphoric acid-acetonitrile (6:4, v/v), and the extracts were cleaned up on a OASIS HLB (60 mg) cartridge. The recoveries of the hormones from bovine muscle fortified at 2 ng/g were 82.3-85.1%, and detection limits were 0.5 ng/g for each drug.

Animals↗
PubMed2000

Synthesis and antiviral activity of novel anti-VZV 5-substituted uracil nucleosides with a cyclopropane sugar moiety.

A series of 5-substituted uracil nucleoside derivatives with a 1(1'S, 2'R)-[1',2'-bis(hydroxymethyl)cyclopropyl]methyl group as an acyclosugar moiety were synthesized and evaluated for their anti-herpetic activities. Among the compounds synthesized, (E)-5-halovinyluracil derivatives showed superior anti-varicella zoster virus (VZV) activity over acyclovir (ACV) but were less potent than ACV against herpes symplex virus type-1 (HSV-1). IC(50) values for the VZV Kawaguchi strain were 0.027 for Br, 0.070 for Cl, and 0.054 microg/mL for I derivatives and 3.4 microg/mL for ACV. The most potent compound, (1'S,2'R)-5-[(E)-2-bromoethenyl]-1-[[1', 2'-bis(hydroxymethyl)cycloprop-1'-yl]methyl]-2,4-(1H, 3H)-pyrimidinedione (3a), was 40-60-fold more potent than ACV against clinical isolates of VZV. It showed good oral bioavailability in rats (68.5%) and, unlike (E)-5-(2-bromovinyl)-1-beta-D-arabinofuranosyluracil (BVaraU), did not result in the release of (E)-5-(2-bromovinyl)uracil (BVU), a potent dihydropyrimidine dehydrogenase inhibitor, in plasma after oral administration.

Animals↗
PubMed2000

Nitrotyrosine generation via inducible nitric oxide synthase in vascular wall in focal ischemia-reperfusion.

Nitrotyrosine produced by NO-mediated reaction is a possible marker for cytotoxicity in brain ischemia. In this study, we aimed to determine whether iNOS is responsible for the nitrotyrosine formation and which type of cell is predominantly nitrated. Fifty-eight wild-type and 28 iNOS knockout male mice were used. Under halothane anesthesia the left middle cerebral artery was occluded for 2 h and reperfused for 0.5 or 15 h. The ratio of nitrotyrosine to total tyrosine (%NO2-Tyr) was measured by means of a hydrolysis/HPLC. After 0.5-h reperfusion, %NO2-Tyr in the ischemic cortex of wild-type and knockout mice amounted to 0.037 +/- 0.040% (n = 8) and 0.064 +/- 0.035% (n = 6), respectively, being significantly higher than that in the sham operation group (n = 7) (P < 0.05). After 15-h reperfusion, nitrotyrosine was detected only in wild-type mice (0.039 +/- 0.025%, n = 7), not in knockout or sham-operated mice (P < 0.05). Immunohistochemical reaction for nitrotyrosine was seen predominantly in the vascular wall in the peri-infarct region of the cerebral cortex in wild-type mice after 15-h reperfusion, but not in corresponding knockout mice. Our data suggest that iNOS is responsible for nitrotyrosine formation in the later phase of reperfusion, and that vascular endothelium is the major site of this reaction, at least in the case of 15-h reperfusion.

Acidosis↗
PubMed2000

Inducible nitric oxide synthase knockout mouse macrophages disclose prooxidant effect of interferon-gamma on low-density lipoprotein oxidation.

To test our hypothesis that interferon-gamma (IFN-gamma) has a direct prooxidant effect on macrophage-mediated LDL oxidation behind its antioxidant effect via induction of inducible nitric oxide synthase (iNOS), we incubated LDL with wild-type (iNOS(+/+)) or iNOS knockout mouse (iNOS(-/-)) macrophages preincubated with IFN-gamma or IFN-gamma plus lipopolysaccharide (IFN-gamma/LPS) for 24 h. LDL oxidation was measured in terms of formation of thiobarbituric acid reactive substances (TBARS) and electrophoretic mobility. Thiol production, nitrite production, and superoxide production from macrophages were measured by using Ellman's assay, the Griess reagent, and the SOD-inhibitable cytochrome c reduction method, respectively. IFN-gamma alone or combined with LPS induced iNOS expression and increased nitrite production in iNOS(+/+) macrophages, but not in iNOS(-/-) macrophages. TBARS formation from LDL was suppressed in IFN-gamma- and IFN-gamma/LPS-treated iNOS(+/+) macrophages but was increased in IFN-gamma-treated iNOS(-/-) macrophages. In the presence of N(G)-monomethyl-l-arginine (l-NMMA), a NOS inhibitor, the suppressive effect of IFN-gamma and IFN-gamma/LPS was abolished and TBARS formation was even increased to a level above that of untreated iNOS(+/+) macrophage. NOC 18, an NO donor, dose dependently inhibited macrophage-mediated LDL oxidation. IFN-gamma increased superoxide and thiol productions in both types of macrophages. We conclude that IFN-gamma promotes macrophage-mediated LDL oxidation by stimulating superoxide and thiol production under conditions where iNOS-catalyzed NO release is restricted.

Animals↗
PubMed2000

Successful treatment of a case of electrical burn with visceral injury and full-thickness loss of the abdominal wall.

A 13-year-old male received high-voltage electrical burns with a resultant large direct wound on the upper abdomen involving the full-thickness of the abdominal wall, including the peritoneum. Early debridement, exploratory laparotomy and temporary restoration of the excised abdominal wall with a fascial prosthesis were carried out at 6 h post-burn. The bilateral upper and right lower limbs were amputated on the 10th post-burn day. The patient developed a 4x4 cm duodenocutaneous fistula on the 28th post-burn day, but was free of peritonitis. After 5 months of the conservative treatment, the fistula closed, and the abdominal wall defect was reconstructed with a free latissimus dorsi musculocutaneous flap. One month later, the patient was discharged following an uneventful recovery.

Abdominal Muscles↗