抛射剂四氟乙烷中杂质CFC115和HFC1243zf的吸入毒理安全性评价

目的：对抛射剂四氟乙烷中杂质五氟氯乙烷(CFC115)和3,3,3-三氟丙烯(HFC1243zf)进行吸入毒性和安全性评价。方法：用CFC115和HFC1243zf混合气体(体积比为7∶3)作为受试样品进行体外空气暴露的小鼠成纤维细胞(L929)细胞毒性及Ames试验,SD大鼠口鼻暴露4 h的急性吸入毒性、7 d重复吸入局部刺激性、21 d重复吸入亚慢毒性试验和Hartley豚鼠全身主动过敏性试验,为控制四氟乙烷中CFC115和HFC1243zf杂质限度提供依据。结果：大鼠急性吸入毒性半数致死浓度(LC₅₀) CFC115>3 115 g/m³,HFC1243zf >832 g/m³;未见重复吸入局部刺激性;未见豚鼠全身致敏反应;无细胞毒性作用;Ames试验未见致突变作用。大鼠21 d重复吸入CFC115(3 205 g/m³)和HFC1243zf (856 g/m³)混合气体后,与对照组相比,摄食量减少(P<0.05或P<0.01)、体质量增长缓慢(P<0.05),血液白细胞分类嗜碱性粒细胞(Bas)、单核细胞(Mon)百分数升高,血生化丙氨酸氨基转移酶(ALT)、天门冬氨酸氨基转移酶(AST)、尿素氮(UREA)、碱性磷酸酶(ALP)、总胆红素(TBil)平均值升高(P<0.05或P<0.01),尿液亚硝酸盐(NIT)、酮体(KET)、个别尿蛋白(PRO)和白细胞(LEU)平均值升高(P<0.05或P<0.01),脑系数升高和卵巢湿质量降低(P<0.05或P<0.01),组织病理学发现心内膜灶性或多灶性坏死、单核细胞浸润的改变,另外雄性大鼠肺脏湿质量和肺系数降低(P<0.01)。结论：CFC115和HFC1243zf混合气体的体外试验或短期动物试验在高浓度接触或吸入未见明显毒性,较长期反复高浓度吸入对大鼠存在多器官损伤,但产生毒性的浓度远高于临床最大暴露量。     

药物对映体含量测定的核磁共振法研究Ⅰ．非洛地平

本文报道了在位移试剂Ｅｕ（ＦＯＤ）３、Ｅｕ（ＴＦＣ）３和Ｅｕ（ＨＦＣ）３存在下非洛地平质子信号的镧诱导位移（ＬＩＳ）值，非洛地平的芳氢质子信号得到简化并解析；在手性位移试剂Ｅｕ（ＨＦＣ）３存在下，观察到甲酯的甲基明显的对映体位移差值（△△δ），据此，可对非洛地平直接进行对映体的含量分析。当Ｅｕ（ＨＦＣ）３：非洛地平为０．６２０（摩尔比）时，甲酯甲基的Ｒ和Ｓ对映体两峰的峰谷高度为峰高的３．８％，即当对映体之一的含量不低于３．８％时，可对非洛地平的对映体含量进行精确的直接测定。     

Blood and exhaled air can be used for biomonitoring of hydrofluorocarbon exposure

Various hydrofluorocarbons (HFCs) have replaced the ozone-depleting chlorofluorocarbons and hydrochlorofluorocarbons during the last decades. The objective of this study was to examine the usefulness of blood and breath for exposure biomonitoring of HFCs. We compared data on blood and exhaled air from a series of experiments where healthy volunteers were exposed to vapors of four commonly used HFCs; 1,1-difluoroethane, 1,1,1-trifluoroethane, 1,1,1,2-tetrafluoroethane, and 1,1,1,3,3-pentafluoropropane. All four HFCs had similar toxicokinetic profiles in blood with a rapid initial increase and an apparent steady-state reached within a few minutes. For all HFCs, the inhalation uptake during exposure was low (less than 6%), most of which was exhaled post-exposure. No metabolism could be detected and only minor amounts were excreted unchanged in urine. The observed time courses in blood and breath were well described by physiologically-based pharmacokinetic (PBPK) modeling. Simulations of 8-h exposures show that the HFC levels in both blood and breath drop rapidly during the first minutes post-exposure, whereafter the decline is considerably slower and mainly reflects washout from fat tissues. We conclude that blood and exhaled air can be used for biological exposure monitoring. Samples should not be taken immediately at the end of shift but rather 20–30 min later.     

Quaternary ammonium-linked glucuronidation of trans-4-hydroxytamoxifen, an active metabolite of tamoxifen, by human liver microsomes and UDP-glucuronosyltransferase 1A4

Tamoxifen (TAM), a nonsteroidal antiestrogen, is the most widely used drug for chemotherapy of hormone-dependent breast cancer in women. Trans-4-hydroxy-TAM (trans-4-HO-TAM), one of the TAM metabolites in humans, has been considered to be an active metabolite of TAM because of its higher affinity toward estrogen receptors (ERs) than the parent drug and other side-chain metabolites. In the present study, we found a new potential metabolic pathway of trans-4-HO-TAM and its geometrical isomer, cis-4-HO-TAM, via N-linked glucuronic acid conjugation for excretion in humans. N+-Glucuronides of 4-HO-TAM isomers were isolated along with O-glucuronides from a reaction mixture consisting of trans- or cis-4-HO-TAM and human liver microsomes fortified with UDP-glucuronic acid and identified with their respective synthetic specimens by high performance liquid chromatography-electrospray ionization time-of-flight mass spectrometry. Although N- and O-glucuronidating activities of human liver microsomes toward trans-4-HO-TAM were nearly comparable, O-glucuronidation was predominant for cis-4-HO-TAM conjugation. Only UGT1A4 catalyzed the N-linked glucuronidation of 4-HO-TAM among recombinant human UGT isoforms (UGT1A1, UGT1A3, UGT1A4, UGT1A6, UGT1A7, UGT1A8, UGT1A9, UGT1A10, UGT2B4, UGT2B7, UGT2B15, and UGT2B17) expressed in insect cells. In contrast, all UGT isoforms, except for UGT1A3 and UGT1A4, catalyzed O-glucuronidation of 4-HO-TAM. Although O-glucuronidation of 4-HO-TAM greatly decreased binding affinity for human ERs, 4-HO-TAM N+-glucuronide still had binding affinity similar to 4-HO-TAM itself, suggesting that N+-glucuronide might contribute to the biological activity of TAM in vivo.     

Quaternary ammonium-linked glucuronidation of tamoxifen by human liver microsomes and UDP-glucuronosyltransferase 1A4

Tamoxifen (TAM), a nonsteroidal antiestrogen, is the most widely used drug for chemotherapy of hormone-dependent breast cancer in women. In the present study, we found a new potential metabolic pathway of TAM via N-linked glucuronic acid conjugation for excretion in humans. TAM N(+)-glucuronide was isolated from a reaction mixture consisting of TAM and human liver microsomes fortified with UDP-glucuronic acid (UDPGA) and identified with a synthetic specimen by high-performance liquid chromatography-electrospray ionization-mass spectrometry. However, no TAM-glucuronidating activity was detected in microsomes from rat, mouse, monkey, dog, and guinea pig livers. A strong correlation (r(2) =0.92 ) was observed between N-glucuronidating activities toward TAM and trifluoperazine, a probe substrate for human UDP-glucuronosyltransferase (UGT) 1A4, in human liver microsomes from eight donors (five females, three males). However, no correlation ( (r(2) =0.02 )) was observed in the activities between 7-hydroxy-4-(trifluoromethyl)coumarin and TAM. Only UGT1A4 catalyzed the N-linked glucuronidation of TAM among recombinant UGTs (UGT1A1, UGT1A3, UGT1A4, UGT1A6, UGT1A9, UGT2B4, UGT2B7, UGT2B15, and UGT2B17) expressed in insect cells. Apparent K(m) values for TAM N-glucuronidation by human liver microsomes and recombinant UGT1A4 were 35.8 and 32.4 microM, respectively. These results strongly suggested that UGT1A4 could play a role in metabolism and excretion of TAM without Phase I metabolism in human liver. TAM N(+)-glucuronide still had binding affinity similar to TAM itself for human estrogen receptors, ERalpha and ERbeta, suggesting that TAM N(+)-glucuronide might contribute to the biological activity of TAM in vivo.     

四氢小檗碱对映体的核磁共振法研究

报道了位移试剂Eu(FOD)_3及Eu(HFC)_3存在下四氢小檗碱质子信号的镧诱导位移(LIS)值,四氢小檗碱的11-H和12-H信号得到确认;在手性位移试剂Eu(HFC)_3存在下,观察到9-OCH_3明显的对映体位移差值[△(△δ)],据此可对四氢小檗碱直接进行对映体的定量分析。当Eu(HFC)_3:THB≥0.722(摩尔比)时,9-OCH_3两对映体信号几乎达到完全分离,可直接对四氢小檗碱的对映体含量进行精确测定。     

Hepatitis C virus core protein, cytochrome P450 2E1, and alcohol produce combined mitochondrial injury and cytotoxicity in hepatoma cells

BACKGROUND & AIMS: Alcohol consumption exacerbates liver injury in chronic hepatitis C, and enhanced mitochondrial oxidative stress is one possible mechanism. The aim of this study was to determine whether hepatitis C virus core protein and alcohol-inducible cytochrome P450 2E1 contribute to reactive oxygen species production and cytotoxicity in human hepatoma cells. METHODS: Huh-7 cells expressing core protein, cytochrome P450 2E1, or both were exposed to 0.1 mmol/L tertiary butyl hydroperoxide, tumor necrosis factor alpha, and/or 25 mmol/L ethanol. Cytotoxicity, reactive oxygen species production, glutathione content, and mitochondrial membrane potential were measured. RESULTS: Expression of core/cytochrome P450 2E1 synergistically enhanced cell death induced by either tertiary butyl hydroperoxide or tumor necrosis factor alpha. After tertiary butyl hydroperoxide treatment, total reactive oxygen species production was increased more than 3-fold compared with cells that did not express core and cytochrome P450 2E1. Mitochondrial depolarization and reduced glutathione depletion occurred as well, and cell death was prevented by inhibition of mitochondrial permeability transition or caspase activity. Confocal microscopy showed that the mitochondria themselves were the origin of the reactive oxygen species. In the absence of core/cytochrome P450 2E1 expression, mitochondrial changes and cell death did not occur. Ethanol treatment further decreased mitochondrial reduced glutathione content and exacerbated mitochondrial reactive oxygen species production, depolarization, and cell death. All these effects were prevented by the antioxidant N -acetylcysteine. CONCLUSIONS: Mitochondrial reactive oxygen species production is induced by hepatitis C virus core and cytochrome P450 2E1, resulting in a reduction of mitochondrial antioxidant capacity and sensitivity to oxidants and tumor necrosis factor alpha. Alcohol further depletes mitochondrial reduced glutathione, which exacerbates depolarization and cell death. Sensitization of mitochondria to oxidative insults is thus a potential mechanism for alcohol-related exacerbation of liver injury in chronic hepatitis C.     

我国药用气雾剂CFC替代的现状和思考

氯氟烷烃(CFCs)破坏臭氧气层,世界各国政府鉴署了"蒙特利尔议定书",决定到2010年停止生产各种CFCs。本文介绍了发达国家、发展中国家以及我国在药用气雾剂领域中CFCs替代的现状,及我国药用气雾剂CFCs替代的进展。并从行政、技术、生产以及使用等角度对今后的工作进行了思考和展望,为各有关方面提供参考。     

Differences in sleep problems between Japanese and Chinese preschoolers: a cross-cultural comparison within the Asian region

Study objectivesPrevious studies have performed cross-cultural comparisons of differences in childhood sleep problems between Asian and Western countries. However, whether such differences can be observed among Asian countries remains unclear. The present study aimed to investigate differences in the pattern of sleep problems between Japanese and Chinese preschoolers.MethodsData were collected from one city in Japan and 10 cities in China. The present study recruited 438 Japanese and 1020 Chinese preschoolers aged four and five years. Sleep problems and patterns were assessed on the basis of parental reports using the Children's Sleep Habits Questionnaire (CSHQ).ResultsAnalysis of covariance revealed no significant difference in total CSHQ scores between Japanese and Chinese preschoolers, thus indicating that the total severity of sleep problems did not differ between the groups. Japanese preschoolers exhibited higher scores on the bedtime resistance subscale of the CSHQ than Chinese preschoolers. Conversely, Chinese preschoolers exhibited higher subscale scores for night wakings and sleep-disordered breathing. In addition, Japanese preschoolers exhibited earlier bedtimes and wake times and shorter total sleep times than Chinese preschoolers.ConclusionsOur findings indicate that the patterns of sleep problems in preschoolers differ between Japan and China and that such differences may be due to differences in cosleeping practices, bedtime routines, and/or environmental conditions. Thus, investigators studying sleep in preschoolers should consider regional differences in the pattern of sleep problems, even among Asian countries.