T-2毒素在大鼠胆汁中的分泌作用和肠-肝循环的研究

T-2毒素在不同动物体内的处置过程表明,原 形毒素和产物可大量随胆汁分泌。本文将T-2毒素经大鼠门静脉注射后引流胆汁,4h内平均胆汁分泌量为2ml。收集的胆汁用XAD-2柱提取分离;酶解后鉴定,确定胆汁中的结合产物主要是3’-O-HHT-2、HT-2和3’-OHT-2毒素的葡萄糖醛酸     

T2毒素在灌流大鼠肠肝中的首过效应和代谢动力学

建立并用大鼠在体肠-肝灌流标本研究了T2毒素在大鼠肠肝中的首过效应和代谢转化动力学,T2毒素在大鼠肠肝中的主要代谢产物是HT2,3′-OHHT2和其葡萄糖醛酸结合物,T2毒素具有显著的肠肝首过效应,当毒素(42μg·ml~(-1))由上肠系膜动脉恒速单次灌流(8 ml·min~(-1))肠-肝标本时,穗态肝、肠抽提率分别为0.978和0.454,总有效清除率为7.91 ml·min~(-1),T2毒素在循环灌流大鼠肠-肝标本中的消除半衰期为6.5min,主要代谢产物HT2,3′-OHHT2的生成半衰期分别为8.5和38.5 min,结果表明,T2毒素经消化道中毒后,在肠和肝的首过代谢下能很快地转化为产物,因此,毒素在体内的毒效作用主要由其代谢产物表现出来。     

T-2毒素在大鼠小肠中吸收和代谢转化的研究

T-2毒素是一种极易污染农作物和储存粮食的单端孢霉烯族毒素,可引起人、畜的各种急慢性中毒,并与人类肿瘤和某些地方病的发生有一定的关系。本文应用大鼠在体肠灌流标本研究了T-2毒素在小肠中的吸收和代谢。将T-2毒素加在灌流液中对小肠进行血管灌流时,主要代谢产物为HT-2毒     

联苯双酯代谢产物的分离和鉴定

给大鼠灌胃联苯双酯后,用TLC法分离尿中代谢产物。发现尿中的主要代谢物为葡萄糖醛酸结合物,将此结合物水解后,用TLC法分离到一种极性较葡萄糖醛酸结合物为弱的代谢物,经光谱分析测定其结构为4-羟基-4′-甲氧基-5,6,5′,6′-二次甲二氧基-2,2′-二甲氧羰基联苯(简称4-去甲联苯双酯)。此外还证实,大鼠灌胃后在肝、肾组织中均以葡萄糖醛酸结合物为主,仪有少量非结合形代谢物和原形药物。     

高效液相-电喷雾质谱分析7-羟基黄酮在大鼠体内的代谢产物

目的:研究7-羟基黄酮在大鼠体内的代谢。方法:应用高效液相-电喷雾质谱检测大鼠灌胃7-羟基黄酮后血浆、尿液、胆汁和粪便中的代谢产物。实验采用Zorbax C18色谱柱,二元线性梯度洗脱进行色谱分离,并与电喷雾质谱联用,根据负离子模式的分子离子峰获得化合物相对分子质量信息,推测化合物的可能结构。结果:在大鼠尿液、粪便、血浆、胆汁中检测到原形成分7-羟基黄酮和7-羟基黄酮葡萄糖醛酸结合物,在胆汁或尿中尚检测到7-羟基黄酮硫酸结合物。结论:7-羟基黄酮在大鼠体内主要以Ⅱ相代谢产物葡萄糖醛酸结合物和硫酸结合物的形式存在。     

HPLC-ESI/MS分析5-羟基黄酮在大鼠体内的代谢产物

目的 研究5-羟基黄酮在大鼠体内的代谢产物。方法 应用高效液相色谱-电喷雾质谱(HPLC-ESI/MS)检测大鼠灌胃5-羟基黄酮后血浆、尿液、胆汁和粪便中的代谢产物。实验采用Zorbax C18色谱柱,0.05%甲酸乙腈-0.05%甲酸水二元线性梯度洗脱进行色谱分离,并与电喷雾质谱联用,根据正离子模式的分子离子峰获得化合物分子量信息,推测化合物的可能结构。结果 仅在大鼠粪便中检测到原形成分,在大鼠尿液、粪便、血浆、胆汁中检测到5-羟基黄酮葡糖醛酸结合物。结论 5-羟基黄酮吸收差,在大鼠体内主要以II相代谢产物葡萄糖醛酸结合物的形式存在。     

用液相质谱法鉴定盐酸关附甲素在大鼠胆汁中Ⅰ相和Ⅱ相代谢产物(英文)

目的:研究盐酸关附甲素在大鼠胆汁中的代谢产物.方法:建立了液相质谱和串联质谱法(LC-MS)对关附甲素及其代谢产物鉴定的方法.大鼠静脉注射盐酸关附甲素后采集胆汁,通过与对照化合物的色谱保留时间、分子离子峰、碎片离子峰和紫外图谱对照从而鉴定Ⅰ相代谢物.胆汁经过葡萄糖醛酸酶或硫酸酯酶水解,鉴定其水解产物(苷元),从而确定Ⅱ相结合物,再通过LC-MS分离和确定分子离子峰,最后利用MS-MS寻找特征子离子和母离子的方法进行验证.结果:大鼠胆汁中存在Ⅰ相代谢物关附壬素;Ⅱ相结合物经葡萄糖醛酸酶和硫酸酯酶酶解后,出现关附甲素和关附壬素;LC-MS检测发现胆汁中m/z 606和 510两个准分子离子峰,推测分别为关附甲素葡萄糖醛酸苷和关附甲素硫酸酯:经MS-MS鉴定出m/z 606特征子离子m/z 177和m/z 430,进一步确证大鼠胆汁中存在关附甲素葡萄糖醛酸苷.结论:大鼠胆汁中存在Ⅰ相代谢产物关附壬素,以及Ⅱ相结合物关附甲素葡萄糖醛酸和硫酸结合物、关附壬素葡萄糖醛酸和硫酸结合物.     

用液相质谱法鉴定盐酸半附甲素在大鼠胆汁中I相和Ⅱ相代谢产物

目的：研究盐酸关附甲素在大鼠胆汁中的代谢产物。方法：建立了液相质谱和串联质谱法（LC－MS）对关附甲素及其代谢产物鉴定的方法。大鼠静脉注射盐酸关附甲素后采集胆汁，通过与对照化合物的色谱保留时间、分子离子峰、碎片离子峰和紫外图谱对照从而鉴定I相代谢物。胆汁经过葡萄糖醛酸酶或硫酸酯酶水解，鉴定其水解产物（苷元），从而确定Ⅱ相结合物，再通过LC－MS分离和确定分子离子峰，最后利用MS－MS寻找特征子离子和母离子的方法进行验证。结果：大鼠胆汁中存在I相代谢物关附壬素；Ⅱ相结合物经葡萄糖醛酸酶和硫酸酯酶酶解后，出现关附甲素和关附壬素；LC－MS检测发现胆汁中m/z 606和510两个准分子离子峰，推测分别为关附甲素葡萄糖醛酸苷和关附甲素硫酸酯；经MS－MS鉴定出m/z 606特征子离子m/z 177和m/z 430，进一步确证大鼠胆汁中存在关附甲素葡萄糖醛酸苷。结论：大鼠胆汁中存在I相代谢产物关附壬素，以及Ⅱ相结合物关附甲素葡萄糖醛酸和硫酸结合物、关附壬素葡萄糖醛酸和硫酸结合物。     

油酸盐对苯并[A]芘酚葡萄糖醛酸化抑制的作用机理

利用肝脏灌流模型及肝脏微粒体对油酸影响羟基苯并[a]芘葡萄糖醛酸化的机理进行了研究,结果表明,低剂量的油酰辅酶A可非竞争性地抑制大鼠肝微粒体UDP-葡萄醛酰转移酶的活性,使3-羟基苯并芘葡萄糖醛酰化作用受抑制,牛血清白蛋白与Triton X-100可促进油酰辅酶A对转移酶的抑制作用。 600 μmol·L~(-1)的油酸灌流肝脏,可使肝脏中UDPGA,UDPG及ATP分别下降44％,49％及44％,因此高剂量的油酸亦可通过改变辅因子供应而抑制羟基苯并芘的葡萄糖醛酸化过程。 250μmol·L~(-1)的油酸灌流缺乏β-葡萄糖醛酸酶的C_3H/He小鼠肝脏,可使流出液中游离羟基苯并芘增加136％,而与葡萄糖醛酸结合的羟基苯并芘减少了32％,同时肝脏中与葡萄糖醛酸结合的羟基苯并芘减少64％,以油酸灌流具有高β-葡萄糖醛酸酶的DBA/2小鼠肝脏可见同样改变,在肝脏微粒体的实验中亦未见油酰辅酶A对苯并芘-0-葡萄糖醛酸的水解作用有何影响,据此,油酸对羟基苯并芘葡萄醛酸化状态的影响与β-葡萄糖醛酸酶无关。     

基于高效液相色谱-串级质谱法研究肝微粒体中T-2毒素代谢的种属差异性

目的比较T-2毒素在不同种属动物肝微粒体中代谢的差异性。方法将T-2毒素与小鼠、大鼠、比格犬、猴和人肝微粒体37℃孵育不同时间,孵育液经蛋白沉淀后采用高效液相色谱-质谱法检测,比较T-2毒素在不同种属动物中代谢动力学参数及代谢产物生成量的差异。结果 T-2毒素在人肝微粒体中半衰期(t_(1/2))<1 mim,在小鼠和猴肝微粒体中为2~4 min,在比格犬肝微粒体中为13 min,在大鼠肝微粒体中为39 min。5种动物对T-2毒素的肝清除能力可分为3组,即人、比格犬和大鼠为1组;猴和小鼠各为1组其中小鼠组对T-2毒素的肝清除率是人、比格犬和大鼠组的3~4倍不同种属的肝微粒体对T-2毒素的亲和力存在显著差异,其中T-2毒素在小鼠肝微粒体中的亲和力最高,其余依次为人、比格犬、大鼠和猴。酶的转化速率以在猴肝微粒体中最大,大鼠和比格犬中略小,而人和小鼠肝微粒体中酶转化速率仅为猴肝微粒体中转化速率的1/10~6。T-2毒素在猴肝微粒体中主要代谢产物为3'-OH-T-2和新茄病镰刀菌烯醇,在人和大鼠肝微粒体中为T-2三醇和HT-2毒素,在比格犬肝微粒体中以HT-2毒素和3'-OH-T-2毒素为主,在小鼠中则以T-2三醇和3'-OH-T-2毒素为主。T-2毒素在小鼠、大鼠、比格犬和人肝微粒体中主要以水解代谢转化为主,而在猴肝微粒体中则以羟基化代谢为主。结论 T-2毒素的代谢参数、代谢产物及其生成量、代谢途径均存在种属差异性。     

Affective and Anxiety Disorders and Alcohol and Drug Dependence:

Depression and anxiety frequently coexist in patients with substance use disorders. This clinically-oriented article examiens the relationship between these conditions and emphasizes data showing that substances of abuse can cause signs and symptoms of both depression and anxiety. These substance-related syndromes appear to have a different course and prognosis than uncomplicated, independent anxiety and major depressive disorders, and clinicians should consider the role of alcohol and other drugs in all patients presenting with these complaints. The authors will also outline an approach for diagnosing and managing patients with the combination of a substance use and depressive or anxiety disorder.     

Synthesis and anti-nociceptive and anti-inflammatory effects of gaultherin and its analogs

The synthesis of gaultherin (1) and its analogs was carried out to provide 11 glycosides under phase-transfer catalytic conditions. The activities of all synthesized compounds were evaluated by nitric oxide production inhibitory assay in vitro. Methyl 2-O-(4-O-β-d-galactopyranosyl)-β-d-glucopyranosylbenzoate (5f) showed significantly anti-nociceptive and anti-inflammatory effects by the evaluation in vivo. Structure–activity relationships within these compounds were discussed.     

Modelling and simulation of variability and uncertainty in toxicokinetics and pharmacokinetics

Two important methodological issues within the framework of the variability and uncertainty analysis of toxicokinetic and pharmacokinetic systems are discussed: (i) modelling and simulation of the existing physiologic variability in a population; and (ii) modelling and simulation of variability and uncertainty when there is insufficient or not well defined (e.g. small sample, semiquantitative, qualitative and vague) information available. Physiologically based pharmacokinetic models are especially suited for separating and characterising the physiologic variability from the overall variability and uncertainty in the system. Monte Carlo sampling should draw from multivariate distributions, which reflect all levels of existing dependencies in the intact organism. The population characteristics should be taken into account. A fuzzy simulation approach is proposed to model variability and uncertainty when there is semiquantitative, qualitative and vague information about the model parameters and their statistical distributions cannot be defined reliably.     

成骨细胞的功能与损伤和骨质疏松的防治

骨质疏松是一种全身性骨骼疾病,导致骨折风险增加。成人的骨量通过破骨细胞的骨吸收和成骨细胞的骨形成作用来维持动态平衡,治疗骨质疏松症的理想策略是抑制破骨细胞的骨吸收和/或增强成骨细胞的骨形成功能。目前针对保护成骨细胞及增强其功能的骨质疏松疗法相对较少。因此,本文针对成骨细胞相关功能蛋白、各种细胞损伤机制（内质网应激、氧化应激、机械过载、微小RNA和长链非编码RNA的影响等）及骨质疏松的治疗与预防作一综述,以期为针对增强成骨细胞功能的骨质疏松治疗策略提供新思路。     

益生菌与肿瘤防治

益生菌广泛存在于自然界中,通过维持宿主体内菌群平衡、影响肠屏障功能和调节免疫应答等作用,提高宿主健康水平,被公认为"肠道健康卫士".一些益生菌可以增强机体的免疫功能,抑制致癌物质,影响肿瘤细胞的基因表达,对肿瘤具有拮抗作用.大量研究表明,益生菌在未来的肿瘤防治中有很好的应用和发展前景.     

Self-stimulation and amphetamine: Tolerance to d and l isomers and cross tolerance to cocaine and methylphenidate

The effects of the d and l isomers of amphetamine on self-stimulation responding were tested following acute and chronic administration. Tolerance and post-drug depression of responding occurred in tests with both isomers, indicating no role for p-hydroxynorephedrine (PHN) which is one of the metabolites of d-amphetamine. In the second experiment, d-amphetamine, methylphenidate and cocaine all produced quantitatively and qualitatively similar effects on self-stimulation responding following acute administration. Following chronic administration of d-amphetamine, animals showed tolerance to all three drugs, indicating cross-tolerance among them. These data are consistent with an hypothesis that tolerance and post-drug depression following chronic amphetamine treatment are the result of decreases in postsynaptic receptor sensitivity, which would lead to a decreased effectiveness of all three drugs, regardless of their pre-synaptic mechanisms.     

Acamprosate and naltrexone treatment effects on ethanol and sucrose seeking and intake in ethanol-dependent and nondependent rats

Rationale  Two pharmacotherapies are approved for treating alcohol craving (acamprosate and naltrexone), but both have shown mixed findings in animals and humans. Objectives  The present experiments utilized a “reinforcer blocking” approach (i.e., rats were able to consume ethanol during treatment) to better understand the efficacy of these treatments for ethanol seeking and drinking using ethanol-dependent and nondependent rats. Materials and methods  In “nondependent” experiments, drugs (acamprosate 50, 100, and 200 mg/kg; naltrexone 0.1, 0.3, and 1.0 mg/kg) were administered over 3-week periods prior to operant sessions with a low response requirement to gain access to reinforcers for 20 min. For “dependent” experiments, rats were made dependent in vapor/inhalation chambers. Results  Acamprosate and naltrexone had similar effects on intake in nondependent and dependent rats; neither drug was selective for ethanol over sucrose drinking. In nondependent animals, naltrexone was more efficacious at more doses than acamprosate, and acamprosate’s effects were limited to a dose that also had adverse effects on body weight. Both pharmacotherapies showed more selectivity when examining reinforcer seeking. In nondependent rats, acamprosate and naltrexone had response-attenuating effects in ethanol, but not sucrose, groups. In dependent animals, acamprosate had selective effects limited to a decrease in sucrose seeking. Naltrexone, however, selectively decreased ethanol-seeking in nondependent rats. Conclusions  The naltrexone-induced decreases in seeking suggested a change in incentive motivation which was selective for ethanol in nondependent rats. The “nondependent” paradigm may model early stages of “problem drinking” in humans, and the findings suggest that naltrexone could be a good intervention for this level of alcohol abuse and relapse prevention.     

Interaction of estrone and estradiol with DNA and protein of liver and kidney in rat and hamster in vivo and in vitro

[6,7-³H] Estrone (E) and [6,7-³H]estradiol-17 (E₂) have been synthesized by reduction of 6-dehydroestrone and 6-dehydroestradiol with tritium gas. Tritiated E and E₂ were administered by oral gavage to female rats and to male and female hamsters on a dose level of about 300 g/kg (54 mCi/kg). After 8 h, the liver was excised from the rats; liver and kidneys were taken from the hamsters. DNA was purified either directly from an organ homogenate or via chromatin. The radioactivity in the DNA was expressed in the units of the Covalent Binding Index, CBI = (mol chemical bound per mol DNA-P)/(mmol chemical administered per kg b.w.). Rat liver DNA isolated via chromatin exhibited the very low values of 0.08 and 0.09 for E and E₂, respectively. The respective figures in hamster liver were 0.08 and 0.11 in females and 0.21 and 0.18 in the males. DNA isolated from the kidney revealed a detectable radioactivity only in the female, with values of 0.03 and 0.05 for E and E₂, respectively. The values for male hamster kidney were < 0.01 for both hormones. The minute radioactivity detectable in the DNA samples does not represent covalent binding to DNA, however, as indicated by two sets of control experiments. (A) Analysis by HPLC of the nucleosides prepared by enzyme digest of liver DNA isolated directly or via chromatin did not reveal any consistent peak which could have been attributed to a nucleoside-steroid adduct. (B) All DNA radioactivity could be due to protein contaminations, because the specific activity of chromatin protein was determined to be more than 3,000 times higher than of DNA. The high affinity of the hormone to protein was also demonstrated by in vitro incubations, where it could be shown that the specific activity of DNA and protein was essentially proportional to the concentration of radiolabelled hormone in the organ homogenate, regardless of whether the animal was treated or whether the hormone was added in vitro to the homogenate.Carcinogens acting by covalent DNA binding can be classified according to potency on the basis of the Covalent Binding Index. Values of 10³–10⁴ have been found for potent, 10² for moderate, and 1–10 for weak carcinogens. Since estrone is moderately carcinogenic for the kidney of the male hamster, a CBI of about 100 would be expected. The actually measured limit of detection of 0.01 places covalent DNA binding among the highly unlikely mechanisms of action. Similar considerations can be made for the liver where any true covalent DNA binding must be below a level of 0.01. It is concluded that an observable tumor induction by estrone or estradiol is unlikely to be due to DNA binding.Paper presented at the Satellite Symposium of the European Society of Toxicology, Rome, March 29, 1983     

Antiinfective and encrustation-inhibiting materials--myth and facts

Catheters, urethral and ureteral stents and other urological implants are frequently affected by encrustration and infection due to their permanent contact with urine. Indwelling urinary catheters provide a haven for microorganisms and thus require extensive monitoring. Several surface modification techniques have been proposed to improve the performance of devices including the immobilization of biomolecules, the incorporation of hydrophilic grafts to reduce protein adsorption, the creation of hydrophobic surfaces, the creation of microdomains to regulate cellular and protein adhesion, new polymers and antimicrobial coatings. Physico-chemical explanation to elucidate the mechanism of such encrustation or infection inhibiting materials is still not available. Our series of experiments showed a marked decrease of silver-activity in biological fluids which corresponds with the controversial clinical results obtained with silver coated urinary catheters. Rifampicin/minocycline coated catheters had very low activity against Gram-negative rods, enterococci and Candida spp., the main causing organisms of urinary catheter infection. Surface engineered materials and antimicrobial drug delivery systems will be the next generation of sophisticated urinary catheters and stents, if both efficacy as well as efficiency has been proved clinically.