细胞色素P450 3A在胎肾上腺和胎肝中的表达

采用酶学和逆转录聚合酶链式反应 ( RT-PCR)技术 ,研究与药物代谢密切相关的细胞色素P450 3A( CYP3A)在胎肾上腺和胎肝中的表达 .结果表明 ,胎肾上腺微粒体中苄非他明 ,氨基比林 ,红霉素 N-脱甲基酶和睾酮 6β-羟化酶活性分别为胎肝微粒体的 2 1 % ,2 60 % ,1 0 5%和 33% .CYP诱导剂苯巴比妥能显著增加体外培养胎肾上腺细胞中苄非他明和氨基比林 N-脱甲基酶活性 ,诱导剂地塞米松也能明显诱导红霉素 N-脱甲基酶活性 .RT- PCR表明胎肾上腺和胎肝中存在 CYP3A7m RNA表达 .说明胎肾上腺和胎肝中存在 CYP3A亚族 .上述结果提示处于发育时期的肾上腺具有与胎肝能力相当的药物代谢功能 .     

Glutathione-related enzyme activities in human fetal adrenal,liver,and kidney

目的：通过测定谷胱甘肽相关酶活性及其在亚细胞分布，了解胎肾上腺在发育期间对活性代谢产物的解毒处理能力．方法：制备肾上腺、肝亚细胞组分．测定谷胱甘肽转移酶（ＧＳＴ）、还原酶、过氧化物酶．结果：ＧＳＴ在胎肾上腺微粒体、线粒体、胞浆中含量分别是肝各亚细胞组分中的３７３％、２７０％和１６７％．肾上腺微粒体ＧＳＴ活性与细胞色素Ｐ４５０、与氨基比林脱甲基酶活性皆呈正相关．肾上腺线粒体谷胱甘肽还原酶、过氧化物酶分别是肝线粒体中的５０６％和４８２％．结论：胎肾上腺有比胎肝更大的解毒能力．提示胎肾上腺兼有药物代谢器官的功能．     

人胎肾上腺,肝和肾内谷胱甘肽相关酶活性

目的：通过谷胱甘肽相关酶活性及其在亚细胞分布，了解胎肾上腺在发育期间对活性代谢产物的解毒处理能力。方法：制备肾上腺、肝亚细胞组分。测定谷胱甘肽转移酶（ＧＳＴ）、还原酶、过氧化物酶。结果：ＧＳＴ在胎肾上腺微粒体、线粒体、胞浆中含量分别是肝各亚细胞组分中的３７３％、２７０％和民６７％、肾上腺微粒体ＧＳＴ活性与细胞色素Ｐ－４５０、与氨基比林脱甲基酶活性皆呈正相关，肾上腺线粒体谷胱甘肽还原酶、过氧化物分别     

对氨基二苯醚类似物抑制细胞色素P-450的定量构效关系

测定了一组对氨基二苯醚类似物延长小鼠戊巴比妥睡眠时间和体外抑制未经处理的小鼠肝微粒体催化氧化对硝基茴香醚脱甲基的活性。用逐步多元回归分析法导出了这些类似物体内和体外抑制细胞色素P-450(P-450)的活性与量化指数的定量构效关系(QSAR)。结果表明:对氨基二苯醚类似物体内和体外抑制P-450的活性均与最低未占据分子轨道能级(E_LUMO)、氨基氮原子的亲核超离域度(S_N(N))和醚氧原子的亲核超离域度(S_N(O))相关。这些类似物的代谢中间体(MI)与P-450形成P-450代谢中间体络合物(P-450-MI)可能是它们能够抑制P-450的主要原因。     

蒿甲醚经大鼠肝微粒体酶脱甲基代谢和氘代同位素效应

经苯巴比妥钠诱导前后的大鼠肝微粒体酶对蒿甲醚脱甲基代谢的Km分别为0.12和0.19mmol/L,Vm分别为0.42和3.97nmol·min~(-1)·mg~(-1)蒿甲醚经诱导酶代谢,证明有氘代同位素效应(DIE)。测定甲醛生成DIE值为2.37±0.08;测定蒿甲醚消失DIE值为1.66±0.08。估算氘代和非氘代蒿甲醚脱甲基率分别为37和53％。提示蒿甲醚的代谢与NADPH-细胞色素P450系统密切相关,O-脱甲基是其主要代谢途径。     

灯盏细辛注射液对小鼠肝微粒体细胞色素P450含量的影响

目的:研究灯盏细辛注射液对小鼠肝微粒体细胞色素P450含量的影响。方法:小鼠分为空白对照组、阳性对照组(苯巴比妥钠80mg/kg,i.p.,共7d)、灯盏细辛注射液正常剂量组、高剂量组(10、30mg/kg,i.p.,共14d)。用紫外分光光度法测定细胞色素P450及其同工酶的活性。结果:灯盏细辛注射液两剂量组小鼠肝微粒体的蛋白含量和细胞色素P450含量较空白对照组增高,对肝重指数基本无影响;可抑制红霉素-N-脱甲基酶(ERD)的活性(P<0.01),而对氨基比林-N-脱甲基酶(AMD)基本无影响(P>0.05);苯巴比妥钠组肝重指数、蛋白含量和细胞色素P450含量与其他各组比较均升高(P<0.05),对氨基比林-N-脱甲基酶、红霉素-N-脱甲基酶活性均有诱导作用(P<0.01)。结论:灯盏细辛注射液对小鼠肝微粒体蛋白、细胞色素P450含量有一定影响,对CYP3A可能有抑制作用,对氨基比林-N-脱甲基酶活性基本无影响。     

地高辛联合氨氯地平对大鼠肝微粒体细胞色素P450的影响

目的研究地高辛合用氨氯地平对大鼠肝脏组织药物代谢酶活性的影响,探讨两药合用后对药物代谢的影响,为临床合理用药提供理论依据。方法雄性大鼠40只,随机均分为空白对照、地高辛、氨氯地平、地高辛+氨氯地平组,每天给药1次,7d后处死。分别测定细胞色素P450和细胞色素b5含量,丙氨酸氨基转移酶、红霉素N-脱甲基酶、氨基比林N-脱甲基酶和7-乙氧基香豆素脱烃酶的活性。结果灌胃给药7d,地高辛、氨氯地平及联合用药对红霉素N-脱甲基酶活性均有明显抑制作用,联合用药的抑制作用未见增强。结论地高辛与氨氯地平合用对细胞色素P450酶系抑制作用未见增强。     

琥乙红霉素和阿司匹林合用对大鼠肝脏细胞色素P450酶的影响

目的：阐明基于药物代谢酶的药物相互作用机制，选择临床常用抗菌药物琥乙红霉素和预防心脑血管疾病的药物阿司匹林作为研究对象，研究两者合用对大鼠肝细胞色素P450（CYP450）含量、氨基比林N-脱甲基酶（ADM）、红霉素N-脱甲基酶（ERD）、谷胱甘肽S-转移酶（GST）活性的影响。方法：体内实验分空白对照组、琥乙红霉素组、阿司匹林组、琥乙红霉素和阿司匹林合用组，每日灌胃给药一次，连续7d。制备大鼠肝微粒体，采用紫外-可见分光光度法测定CYP450含量及ADM、ERD、GST活性。结果：琥乙红霉素、阿司匹林合用后CYP450酶活性均有不同程度的降低，与对照组比较有显著性差异（P〈0．05）。结论：两药合用对药物代谢酶有影响，可能使药物的体内代谢特征发生改变，产生药物代谢性相互作用，从而影响药物疗效。     

N-甲基(3,4-亚甲二氧基苯甲酰)甲基-乙酰胺(SY-640)对化学致癌剂苯并芘与小鼠肝细胞核DNA共价结合的抑制作用

用小鼠肝细胞核制备和肝微粒体制备,研究了化合物SY-640对致癌剂苯并芘(BP)损伤肝细胞核的保护作用及与P-450的关系。结果表明,SY-640可显著抑制³H-BP与小鼠肝细胞核的DNA共价结合。SY-640连续po 3 d,可显著诱导小鼠肝微粒体细胞色素P-450含量及氨基比林脱甲基酶活性;给药1次2h内却只抑制氨基比林脱甲基酶活性。体外温孵实验表明,SY-640对小鼠肝微粒体氨基比林脱甲基酶活性也具有明显的抑制作用。差示光谱分析表明,SY-640可与细胞色素P-450形成络合物。提示该化合物对肝微粒体细胞色素P-450酶系的影响与其对化学致癌剂BP所致肝细胞毒性的保护作用有关。     

大鼠肝微粒体细胞色素P4503A参与吡喹酮A环羟化代谢

三乙酰竹桃霉素(TAO)可使地塞米松(DEX)诱导的大鼠肝微粒体内未结合细胞色素P450(P450)含量降低,红霉素(ERY)和乙基吗啡(EMP)N-脱甲基酶活性降低和吡喹酮(PZQ)A环一羟化物生成速率降低。TAO和ERY对PZQA环一羟化物的生成表现为竟争性抑制,且PZQA环一羟化物生成速率与ERY,EMPN-脱甲基酶活性高度相关。结果表明,P4503A(CYP3A)参与了PZQA环的羟化。     

Efficacy of gut lavage,hemodialysis, and hemoperfusion in the therapy of paraquat or diquat intoxication

Clinical and in vitro investigations were carried out to test the efficacy of gut lavage, hemodialysis, and hemoperfusion in the treatment of poisoning with paraquat or diquat. In a patient suffering from diquat intoxication 130 times more diquat was removed by gut lavage 30 h after ingestion than was removed by complete aspiration of the gastric contents.Determination of in vitro clearances for paraquat and diquat by hemodialysis showed that, at serum concentrations of 1–2 ppm, such as are frequently encountered in poisoning in man, toxicologically relevant quantities of herbicide cannot be removed from the body. At a concentration of 20 ppm, on the other hand, hemodialysis proved to be effective, the clearance being 70 ml/min at a blood flow rate of 100 ml/min. The efficacy of hemoperfusion with coated activated charcoal was on the whole better. Especially at concentrations around 1–2 ppm, the clearance values for hemoperfusion were some 5–7 times higher than those for hemodialysis.In a patient suffering from paraquat poisoning, both hemodialysis as well as hemoperfusion were carried out. The in vitro results could be confirmed: At serum concentrations of paraquat less than 1 ppm no clearance could be obtained by hemodialysis while by hemoperfusion with activated charcoal quite high clearance values were measured and the serum level dropped down to zero.

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Zusammenfassung Klinische Untersuchungen und Laboratoriumsversuche wurden durchgeführt, um die Wirksamkeit von Darmspülung, Hämodialyse und Hämoperfusion bei Paraquat- und Deiquat-Vergiftungen zu prüfen.Bei einem Patienten wurde 30 Std nach Deiquat-Aufnahme durch Darmspülung 130mal mehr Deiquat entfernt als durch vollständige Aspiration des Mageninhaltes. In vitro-Versuche ergaben, daß bei Blutserumkonzentrationen von 1–2 ppm, die bei Vergiftungen oft gemessen werden, durch Hämodialyse keine toxikologisch relevanten Paraquat- oder Deiquat-Mengen entfernt werden können. Dagegen erwies sich die Hämodialyse bei 20 ppm und einer Blutumlaufgeschwindigkeit von 100 ml/min mit einer Clearance von 70 ml/min als wirksam. Die Hämoperfusion mit beschicheter Aktivkohle war in diesen Versuchen aber eindeutig überlegen, denn insbesondere bei Konzentrationen um 1–2 ppm waren die Clearance-Werte 5–7mal höher als bei der Hämodialyse.Die in vitro-Ergebnisse wurden bei einem Patienten mit einer Paraquat-Vergiftung bestätigt: Bei Konzentrationen unter 1 ppm war die Hämodialyse wirkungslos, während durch Hämoperfusion relativ hohe Clearance-Werte erreicht wurden, so daß der Serumspiegel rasch unter die Nachweisgrenze abfiel.

     

Aquatic Insects and Trace Metals: Bioavailability,Bioaccumulation, and Toxicity

Abstract

The uptake of metals from food and water sources by insects is thought to be additive. For a given metal, the proportions taken up from water and food will depend both on the bioavailable concentration of the metal associated with each source and the mechanism and rate by which the metal enters the insect. Attempts to correlate insect trace metal concentrations with the trophic level of insects should be made with a knowledge of the feeding relationships of the individual taxa concerned. Pathways for the uptake of essential metals, such as copper and zinc, exist at the cellular level, and other nonessential metals, such as cadmium, also appear to enter via these routes. Within cells, trace metals can be bound to proteins or stored in granules. The internal distribution of metals among body tissues is very heterogeneous, and distribution patterns tend to be both metal and taxon specific. Trace metals associated with insects can be both bound on the surface of their chitinous exoskeleton and incorporated into body tissues. The quantities of trace meals accumulated by an individual reflect the net balance between the rate of metal influx from both dissolved and particulate sources and the rate of metal efflux from the organism. The toxicity of metals has been demonstrated at all levels of biological organization: cell, tissue, individual, population, and community. Much of the literature pertaining to the toxic effects of metals on aquatic insects is based on laboratory observations and, as such, it is difficult to extrapolate the data to insects in nature. The few experimental studies in nature suggest that trace metal contaminants can affect both the distribution and the abundance of aquatic insects. Insects have a largely unexploited potential as biomonitors of metal contamination in nature. A better understanding of the physico-chemical and biological mechanisms mediating trace metal bioavailability and exchange will facilitate the development of general predictive models relating trace metal concentrations in insects to those in their environment. Such models will facilitate the use of insects as contaminant biomonitors.     

Alzheimer’s disease – current trends in basic and clinical research. Highlights from the 16th ECNP

Advances in the molecular biological knowledge of neuronal nicotinic acetylcholine receptors (nAChRs) have led to a growing interest by the pharmaceutical industry in the development of novel compounds that selectively modulate nAChR function. The ability of (-)-nicotine, an activator of nAChRs, to enhance attentional aspects of cognition in animals and humans, to exert neuroprotective and anxiolytic-like effects, and presumably to mediate the negative correlation between smoking and Alzheimer's (and Parkinson's) Disease, has focused interest on the potential therapeutic utility of modulators of nAChR function for treatment of some of the deficits associated with these progressive, neurodegenerative conditions. Numerous compounds are known which activate nAChRs and which might serve as lead compounds toward the development of such agents. The pharmacologic diversity of neuronal nAChR subtypes suggests the possibility of developing selective compounds which would have more favourable side-effect profiles than existing agents. This broader class of agents, collectively called cholinergic channel modulators (ChCMs), is anticipated to encompass compounds which would have more favourable side-effect profiles than existing agents, which generally exhibit low selectivity. This selectivity may be achieved by preferentially activating some subtypes of nAChRs (i.e., Cholinergic Channel Activators, ChCAs) or inhibiting the function of other subtypes (Cholinergic Channel Inhibitors, ChCIs). An overview of the biology of nAChRs and the rationale for the use of ChCMs for the treatment of dementia related to neurodegenerative diseases are presented, followed by a discussion of lead compounds and compounds under consideration for clinical evaluation.     

2-(Acetoxyphenyl)-(Z)-styryl sulfides as cyclooxygenase inhibitors

2-(Acetoxyphenyl)-(Z)-styryl sulfides are described as selective cyclooxygenase-2 (COX-2) inhibitors, useful for treating inflammation and COX-2-mediated disorders including neoplasia. 2-(Acetoxyphenyl)-(Z)-styryl sulfide is claimed to be the most potent COX inhibitor in the series with a COX-2 selectivity ratio of 33. This compound is also claimed to be superior to celecoxib (Celebrex^®, Pfizer) in inhibiting cell growth of colorectal carcinoma cells. In this evaluation, the COX inhibitory activity of this compound is compared to that previously disclosed for diarylheterocycles and 2-(acetoxyphenyl)alkyl sulfides. The validity of the DLD-1 cell line in the growth inhibition studies is questioned based on recent literature reports indicating the lack of COX-2 expression in this cell line.     

Sleep-disordered breathing with chronic opioid use

Chronic opioid use for pain relief or as substitution therapy for illicit drug abuse is prevalent in our societies. In the US, retail distribution of methadone and oxycodone has increased by 824 and 660%, respectively, between 1997 and 2003. μ-Opioids depress respiration and deaths related to illicit and non illicit chronic opioid use are not uncommon. Since 2001 there has been an emerging literature that suggests that chronic opioid use is related to central sleep apnoea of both periodic and non-periodic breathing types, and occurs in ～ 30% of these subjects. The clinical significance of these sleep-related abnormalities are unknown. This review addresses the present knowledge of control of ventilation mechanisms during wakefulness and sleep, the effects of opioids on ventilatory control mechanisms, the sleep-disordered breathing found with chronic opioid use and a discussion regarding the future research directions in this area.     

Drug targets for cognitive enhancement in neuropsychiatric disorders

The investigation of novel drug targets for treating cognitive impairments associated with neurological and psychiatric disorders remains a primary focus of study in central nervous system (CNS) research. Many promising new therapies are progressing through preclinical and clinical development, and offer the potential of improved treatment options for neurodegenerative diseases such as Alzheimer's disease (AD) as well as other disorders that have not been particularly well treated to date like the cognitive impairments associated with schizophrenia (CIAS). Among targets under investigation, cholinergic receptors have received much attention with several nicotinic agonists (α7 and α4β2) actively in clinical trials for the treatment of AD, CIAS and attention deficit hyperactivity disorder (ADHD). Both glutamatergic and serotonergic (5-HT) agonists and antagonists have profound effects on neurotransmission and improve cognitive function in preclinical experiments with animals; some of these compounds are now in proof-of-concept studies in humans. Several histamine H3 receptor antagonists are in clinical development not only for cognitive enhancement, but also for the treatment of narcolepsy and cognitive deficits due to sleep deprivation because of their expression in brain sleep centers. Compounds that dampen inhibitory tone (e.g., GABA_A α5 inverse agonists) or elevate excitatory tone (e.g., glycine transporter inhibitors) offer novel approaches for treating diseases such as schizophrenia, AD and Down syndrome. In addition to cell surface receptors, intracellular drug targets such as the phosphodiesterases (PDEs) are known to impact signaling pathways that affect long-term memory formation and working memory. Overall, there is a genuine need to treat cognitive deficits associated with many neuropsychiatric conditions as well as an increasingly aging population.