Biomedical subjects

Ryoichi Kizu

Publications and source records attributed to Ryoichi Kizu.

25 records · Page 2Linked to original sources

PubMed2003

Quantification of 2-hydroxyfluorene in human urine by column-switching high performance liquid chromatography with fluorescence detection.

A high performance liquid chromatographic (HPLC) method for the quantification of 2-hydroxyfluorene (2-OHF) in normal human urine was established using deuterated 2-hydroxyfluorene (2-OHF-d9) as an internal standard with column-switching and fluorescence detection. The 2-OHF-d9 was synthesized by the metabolism of deuterated fluorene with cytochrome P450. The analytes were cleaned up on an ODS pre-column, via column-switching, and separated on an alkylamide-type reversed phase column. The internal standard eluted immediately prior to non-deuterated 2-OHF on the HPLC system and had nearly the same fluorescence characteristics as the non-deuterated 2-OHF. The detection limit was 0.03 nmol l(-1) (S/N = 3) and the calibration range of urine sample was from 0.2 to 50 nmol l(-1). The urine sample treatment involved enzymatic hydrolysis followed by solid phase extraction using a Sep-Pak C18 cartridge. 2-OHF was observed in the form of conjugates such as glucuronide and/or sulfate in human urine, and urinary metabolites were completely hydrolyzed for 2 h with beta-glucuronidase/aryl sulfatase. The proposed method was used to determine urinary 2-OHF in smokers and non-smokers, and showed that the urinary concentrations of 2-OHF in smokers were significantly higher than those in non-smokers (P < 0.01). Thus, the data suggest that urinary 2-OHF might be a sensitive and specific biological marker for the assessment of the exposure to polycyclic aromatic hydrocarbons.

Biomarkers↗

PubMed2003

Improvement of an automatic HPLC system for nitropolycyclic aromatic hydrocarbons: removal of an interfering peak and increase in the number of analytes.

An automatic HPLC system for analyzing nitropolycyclic aromatic hydrocarbons (NPAHs, nitroarenes) in airborne particulates was previously described (Anal. Chim. Acta, 2001, 445, 20). Some problems with this system were that it generated a peak originating from an ascorbic acid solution that elutes at a retention time close to that of 1,6-dinitropyrene (DNP), and that it was able to analyze only 1,3-, 1,6-, 1,8-DNPs and 1-nitropyrene (I-NP). Here, we describe an improved system that effectively removes the interfering peak by introducing an ODS column just after the pump for the ascorbic acid solution, and which is capable of analyzing several additional compounds (2-, 4-NPs, 2-nitrofluorene. 6-nitrochrysene, 7-nitrobenz[a]anthracene, 3-nitroperylene and 6-nitrobenzo[a]pyrene etc.). The improved sensitivities were achieved by concentrating the compounds in a benzene-ethanol extract from airborne particulates, by increasing the loading time of the sample solution from 20 to 38 min, and by increasing the flow rate of an ascorbic acid solution from 1.3 to 1.8 mL/min.

Air Pollutants↗

PubMed2002

Determination of 1-hydroxypyrene in human urine by high-performance liquid chromatography with fluorescence detection using a deuterated internal standard.

A high-performance liquid chromatographic method has been developed for the quantification of 1-hydroxypyrene (1-OHP) in human urine using deuterated 1-hydroxypyrene ([2H9]1-OHP) as an internal standard with fluorescence detection. [2H9]1-OHP was prepared enzymatically from deuterated pyrene ([2H10]Pyr) with cytochrome P450 1A1. It eluted immediately prior to non-deuterated 1-OHP on alkylamide-type reversed-phase columns and had nearly the same fluorescence characteristics as non-deuterated 1-OHP. The detection limit was 0.1 microg/L and the calibration range was from 1 to 100 nmol/L. Urine sample treatment involved enzymatic hydrolysis followed by solid-phase extraction using Sep-Pak C18 cartridges. The proposed method was used to determine urinary 1-OHP in smokers and non-smokers.

Adult↗

PubMed2002

Induction of CYP1A1, CYP1A2, and CYP1B1 mRNAs by nitropolycyclic aromatic hydrocarbons in various human tissue-derived cells: chemical-, cytochrome P450 isoform-, and cell-specific differences.

Nitropolycyclic aromatic hydrocarbons (NPAHs) are found in diesel exhaust and ambient air. NPAHs as well as polycyclic aromatic hydrocarbons (PAHs) are known to have mutagenicity, carcinogenicity, and endocrine-disruptive effects. In the present study, the inducibility of the human cytochrome P450-1 (CYP1) family by NPAHs was compared with those produced by their parent PAHs and some reductive metabolites, amino-PAHs. Furthermore, to investigate the differences in the inducibility of the CYP1 family in human tissues, various human tissue-derived cell lines, namely HepG2 (hepatocellular carcinoma), ACHN (renal carcinoma), A549 (lung carcinoma), MCF-7 (breast carcinoma), LS-180 (colon carcinoma), HT-1197 (bladder carcinoma), HeLa (cervix of uterus adenocarcinoma), OMC-3 (ovarian carcinoma), and NEC14 (testis embryonal carcinoma), were treated with NPAHs, PAHs, or amino-PAHs. The mRNA levels of CYP1A1, CYP1A2, and CYP1B1 were determined with reverse transcription-polymerase chain reaction (RT-PCR). The cell lines were classified into two groups: CYP1 inducible cell lines, comprising HepG2, MCF-7, LS-180, and OMC-3 cells, and CYP1 non-inducible cell lines, comprising ACHN, A549, HT-1197, HeLa, and NEC14 cells. In inducible cell lines, the induction profile of chemical specificity was similar for CYP1A1, CYP1A2, and CYP1B1, although the extent of induction differed among the cell lines and for the CYP isoforms. Pyrene, 1-nitropyrene, 1-aminopyrene, 1,3-, 1,6-, and 1,8-dinitropyrenes slightly induced CYP1 mRNAs, but 1,3-dinitropyrene produced a 6-fold induction of CYP1A1 mRNA in MCF-7 cells. 2-Nitrofluoranthene and 3-nitrofluoranthene exhibited stronger inducibility than fluoranthene in the inducible cell lines. 6-Nitrochrysene induced CYP1 mRNAs to the same extent or more potently than chrysene. The induction potencies of 6-nitrobenzo[ a]pyrene and 7-nitrobenz[ a]anthracene were weaker than those of their parents benzo[ a]pyrene and benz[ a]anthracene, respectively. This study demonstrated that NPAHs as well as PAHs induced human CYP1A1, CYP1A2, and CYP1B1 in a chemical-, CYP isoform-, and cell-specific manner. Furthermore, the cell-specific induction of the CYP1 family was not related to the expression levels of aryl hydrocarbon receptor, aryl hydrocarbon nuclear translocator, or estrogen receptors alpha and beta.

Aryl Hydrocarbon Hydroxylases↗

PubMed2002

Enantioseparation of vinclozolin by gamma-cyclodextrin-modified micellar electrokinetic chromatography.

Cyclodextrin-modified micellar electrokinetic chromatography was applied to the enantioseparation of vinclozolin, which has been used as a fungicide and has an anti-androgenic activity, using gamma-cyclodextrin together with sodium dodecyl sulfate. Factors affecting the chiral resolution and migration time of vinclozolin were studied. The optimum running conditions were found to be 20 mM phosphate-5 mM borate buffer (pH 8.5) containing 50 mM gamma-cyclodextrin and 100 mM sodium dodecyl sulfate with an effective voltage of 20 kV at 20 degrees C using direct detection at 203 nm. Under these conditions, the resolution (Rs) of racemic vinclozolin was approximately 2.1. The sample was concentrated by solid-phase extraction and was fractionated by HPLC. The peak area ratio of (+)- and (-)-vinclozolins in wine was found to be 2:3, namely, not racemic, suggesting that degradation rates were different between (+)- and (-)-vinclozolins. The anti-androgenic activities of (+)- and (-)-vinclozolins on dihydrotestosterone-induced transcription were also investigated. The anti-androgenic activity of (+)-vinclozolin tended to be stronger than that of (-)-vinclozolin, suggesting the possibility that vinclozolin can act as an enantioselective anti-androgen.

Chromatography, High Pressure Liquid↗

PubMed2002

Simultaneous detection of monohydroxybenzo[a]pyrene positional isomers by reversed-phase liquid chromatography coupled to electrospray ionization mass spectrometry.

A liquid chromatographic (LC) method has been developed for the separation of 11 monohydroxybenzo[a]pyrenes (OH BaPs) positional isomers, and for their detection using electrospray ionization mass spectrometry (ESI-MS). All OH BaPs isomers were separated on an octadecylsilyl (C(18))-bonded amorphous organosilica column utilizing gradient elution with acetonitrile-water and triethylamine (TEA) at pH 11.0 and determined by MS, except 2- and 8-OH BaPs which were coeluted. The lower detection limits were in the range from 1.6 micro g/L for 12-OH BaP to 12 micro g/L for 5-OH BaP without any sample enrichment. The relative standard deviations of area response were in the range from 1.8% (9-OH BaP) to 4.9% (12-OH BaP) except for 9.4% (7-OH BaP). The developed method was successfully applied to incubation mixtures of BaP and CYP1A1/epoxide hydrolase. This method identified 1-, 3- and 9-OH BaPs as the major metabolites, and 2- (and/or 8-) and 12-OH BaPs as the minor metabolites in the incubation mixture.

Benzo(a)pyrene↗

PubMedDate not supplied

Quantification of polycyclic aromatic hydrocarbons (PAHs) in human hair by HPLC with fluorescence detection: a biological monitoring method to evaluate the exposure to PAHs.

A high-performance liquid chromatographic (HPLC) method with fluorescence detection was developed for the quantification of polycyclic aromatic hydrocarbons (PAHs) in human hair. Fifteen kinds of PAHs classified as priority pollutants by the US EPA were quantified with four perdeuterated PAHs as internal standards. After 50 mg hair samples were washed with n-hexane to remove external contamination of PAHs, the samples were digested in 2.5 M sodium hydroxide. The digests were extracted with n-hexane and then analyzed by HPLC. Eleven kinds of PAHs were identified in hair samples of 20 subjects, and 10 kinds of PAHs were eventually quantified using the internal standards. For anthracene, chrysene and benzo[k]fluoranthene, significant differences were observed between smokers and non-smokers. Although benzo[b]fluoranthene, dibenz[a,h]anthracene, benzo[ghi]perylene and indeno[1,2,3-cd]pyrene were observed in the particulates of indoor and outdoor air, they were not detected in all hair samples. The analysis of PAHs in human hair should be useful as a new biomarker to evaluate the exposure to PAHs.

Chromatography, High Pressure Liquid↗