川芎嗪大鼠在体肠吸收动力学

目的:探讨川芎嗪在大鼠各肠段的吸收动力学特征.方法:采用大鼠在体小肠回流装置,以UV法和HPLC法分别测定酚红和川芎嗪的含量.结果:川芎嗪在小肠的吸收速率常数(Ka)于不同药物浓度2.5,5,10,25 mg·L-1时分别为0.360 8,0.388 1,0.444 6,0.385 9 h-1;不同pH值7.8,6.8,5.4时分别为0.466 4,0.413 9,0.270 5 h-1;在十二指肠,空肠,回肠和结肠时分别为0.291 3,0.220 9,0.172 8,0.133 3 h-1.结论:药物浓度对Ka无影响;在pH 7.8～5.4范围内,随药液pH值的增大,药物的Ka显著增加;药物在十二指肠、空肠和回肠的吸收较好,在结肠的吸收较差;川芎嗪在肠道的吸收呈一级动力学过程,吸收机制为被动扩散.     

在体小肠对氧氟沙星的吸收动力学研究

目的:研究氧氟沙星在肠道各区段的吸收动力学特征、吸收部位及吸收机制,对氧氟沙星缓释制剂的设计提供重要依据.方法:采用大鼠在体循环方法研究氧氟沙星的肠吸收.结果:在2.0～10.0 mg·L-1浓度范围内吸收量与浓度呈线性关系,无高浓度饱和现象,Ka值基本保持不变;在pH 5.5～7.4范围内吸收受pH影响;各肠段的吸收速度常数差异有显著性,十二指肠、空肠、回肠的吸收速率常数分别为0.054 h-1,0.037 h-1,0.0032 h-1,在结肠几乎末检测到吸收.结论:氧氟沙星吸收机制为被动转运,在小肠内的吸收呈现吸收一级动力学特征.最佳吸收部位在十二指肠和空肠.     

盐酸去氢骆驼蓬碱大鼠肠吸收动力学的研究

目的　研究盐酸去氢骆驼蓬碱在大鼠胃肠道各段的吸收动力学特征 ,为其剂型设计提供生物药剂学依据。方法　采用大鼠在体肠循环法分别研究盐酸去氢骆驼蓬碱在大鼠十二指肠、空肠、回肠及结肠中的吸收动力学特征。采用反相高效液相色谱法测定循环液中的药物浓度。结果　盐酸去氢骆驼蓬碱在十二指肠、空肠、回肠及结肠中的吸收速度常数Ka分别为 :( 0 .30 92± 0 .0 5 9) ,( 0 .2 0 6 4± 0 .0 4 4 ) ,( 0 .2 85 8± 0 .0 81) ,( 0 .2 0 0 9± 0 .0 80 )h-1。结论　盐酸去氢骆驼蓬碱在十二指肠、空肠、回肠及结肠中均能较好地吸收     

石杉碱甲大鼠在体肠吸收动力学研究

目的研究石杉碱甲在大鼠小肠及各肠段的吸收动力学特征.方法采用大鼠在体方式对石杉碱甲进行了大鼠小肠及各肠段的吸收动力学研究;采用HPLC法测定石杉碱甲在大鼠体内肠吸收循环液中的药物浓度;采用UV法测定循环液中酚红浓度.结果石杉碱甲在小肠中吸收较好且没有特定吸收部位,各肠段吸收速率按十二指肠、空肠、回肠、结肠依次为0.001 0、0.000 9、0.001 1、0.000 9 h-1.结论结肠的吸收速率常数与小肠段相近,药物在肠道的吸收呈现一级吸收动力学,吸收机制为被动吸收,提示适于制备日服一次(24 h)缓释给药制剂.     

左羟丙哌嗪的大鼠在体肠吸收特性

目的研究左羟丙哌嗪大鼠的在体肠吸收特性。方法采用大鼠在体小肠循环灌注模型,用HPLC同时测定灌注液中酚红和左羟丙哌嗪的含量。结果左羟丙哌嗪12.8~80.0μg.ml-1与小肠吸收量呈线性关系,吸收速率常数Ka几乎不变;各肠道间Ka值无显著性差异(P>0.05),十二指肠、空肠、回肠和结肠的Ka值分别为0.039±0.004、0.042±0.010、0.037±0.003、0.034±0.004 h-1。结论左羟丙哌嗪浓度12.8~80.0μg.ml-1在小肠段的吸收呈一级动力学过程,吸收机制为被动扩散,主要吸收部位在小肠段,且无特定的吸收窗。     

芒果苷大鼠在体肠道吸收机制研究

目的:研究芒果苷大鼠在体肠道吸收机制。方法:采用大鼠在体肠段灌流模型,建立高效液相色谱/紫外分光光度法测定肠循环液中芒果苷的浓度,研究不同芒果苷浓度、胆汁及吸收部位对芒果苷吸收参数的影响。结果:芒果苷在5.0~25.0μg.mL-1浓度范围内对小肠吸收速率常数(Ka)无影响;在12.5μg.mL-1浓度下对结扎胆管大鼠的小肠Ka有影响;各肠段的Ka回肠>空肠>结肠>十二指肠,分别为0.164、0.132、0.125、0.107h-1。结论:芒果苷的吸收符合一级动力学特征,吸收机制为被动扩散;芒果苷在各肠段均有较好的吸收,胆汁使芒果苷在小肠的透过系数增大。     

香青兰黄酮类化合物的大鼠在体肠吸收

目的:研究香青兰总黄酮在大鼠各肠段的吸收动力学特征。方法:采用大鼠在体肠灌流模型,利用HPLC法测定灌流液中田蓟苷的浓度,研究田蓟苷和香青兰总黄酮在大鼠各肠段的吸收特性。结果:香青兰总黄酮中田蓟苷在大鼠各肠段的吸收速率常数Ka值按结肠、空肠、十二指肠、回肠顺序依次分别为5.7651×10-2,4.4081×10-2,4.3873×10-2,3.9899×10-2;田蓟苷在大鼠各肠段的吸收速率常数Ka值按十二指肠、回肠、空肠、结肠顺序依次分别为6.7897×10-2,6.3018×10-2,5.8011×10-2,5.6765×10-2。结论:田蓟苷单体与香青兰总黄酮中田蓟苷在大鼠各肠段的吸收特征相一致,二者在大鼠小肠段不同部位的吸收均不存在差异。     

普拉克索的大鼠在体肠吸收

采用大鼠在体灌流法,以灌流液中剩余药物浓度为指标,考察普拉克索(1)在不同吸收部位的吸收动力学特征以及不同pH、不同药物浓度对1全肠段吸收的影响.结果显示,1在不同肠段的吸收速率常数(h-1)分别为:十二指肠0.295、结肠0.513、回肠0.480 h和空肠0.808 h.药物在大鼠全肠道内的吸收量随药物浓度的增大而升高,药物浓度和pH对吸收速率常数无显著性影响.1在肠道的吸收符合一级动力学特征,吸收机制为被动吸收.采用大鼠在体胃灌注法,以胃灌注液中药物前后浓度变化计算1在胃部吸收情况.结果表明1几乎不吸收.     

芒果苷大鼠在体肠吸收动力学研究

目的研究芒果苷在大鼠小肠内的吸收情况及动力学特征。方法采用大鼠在体单向灌流法进行肠吸收实验,利用HPLC法测定灌流流出液中芒果苷的浓度,按重量法计算动力学参数。结果芒果苷在小肠内吸收存在差异,在十二指肠、空肠、回肠和结肠的Ka分别为（1.4±0.1）、（1.6±0.2）、（0.9±0.1）、（1.0±0.2）×10-2.min-1;与0.32mg.L-1浓度相比,7.0mg.L-1浓度的Ka和Papp值显著降低。结论芒果苷在小肠内吸收存在高浓度饱和现象,且存在特定的吸收部位,主要在十二指肠和空肠。     

银杏总黄酮苷在大鼠体内的肠吸收动力学特征

目的　考察银杏总黄酮苷(TFG)在大鼠体内的肠吸收动力学特征。方法　对大鼠的十二指肠、空肠、回肠和结肠4个部位分别进行在体肠吸收实验,计算和比较TFG在各部位的吸收速率常数(Ka)和2h的累积吸收量。结果　TFG在大鼠肠道各部位的Ka 按十二指肠、空肠、回肠、结肠依次下降;在10 0～4 0 0mg·L-1浓度范围内,各肠段TFG的吸收量与浓度有良好线性关系(r>0 .994 4 ) ,Ka 值基本不变。结论　TFG在大鼠肠道内的吸收呈现一级吸收动力学特征,其吸收机制为被动扩散     

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.

     

In vitro studies on sterically stabilized liposomes (SL) as enzyme carriers in organophosphorus (OP) antagonism

This study describes a new approach for organophosphorous (OP) antidotal treatment by encapsulating an OP hydrolyzing enzyme, OPA anhydrolase (OPAA), within sterically stabilized liposomes. The recombinant OPAA enzyme was derived from Alteromonas strain JD6. It has broad substrate specificity to a wide range of OP compounds: DFP and the nerve agents, soman and sarin. Liposomes encapsulating OPAA (SL)* were made by mechanical dispersion method. Hydrolysis of DFP by (SL)* was measured by following an increase of fluoride ion concentration using a fluoride ion selective electrode. OPAA entrapped in the carrier liposomes rapidly hydrolyze DFP, with the rate of DFP hydrolysis directly proportional to the amount of (SL)* added to the solution. Liposomal carriers containing no enzyme did not hydrolyze DFP. The reaction was linear and the rate of hydrolysis was first order in the substrate. This enzyme carrier system serves as a biodegradable protective environment for the recombinant OP-metabolizing enzyme, OPAA, resulting in prolongation of enzymatic concentration in the body. These studies suggest that the protection of OP intoxication can be strikingly enhanced by adding OPAA encapsulated within (SL)* to pralidoxime and atropine.     

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.     

Pharmacological treatment of COVID-19: an opinion paper

The precocity and efficacy of the vaccines developed so far against COVID-19 has been the most significant and saving advance against the pandemic. The development of vaccines has not prevented, during the whole period of the pandemic, the constant search for therapeutic medicines, both among existing drugs with different indications and in the development of new drugs. The Scientific Committee of the COVID-19 of the Illustrious College of Physicians of Madrid wanted to offer an early, simplified and critical approach to these new drugs, to new developments in immunotherapy and to what has been learned from the immune response modulators already known and which have proven effective against the virus, in order to help understand the current situation.     

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.     

Steroidal sapogenin contents in some domestic plants

In order to find out the values of the steroid resources for the future use. the compositions and contents of steroidal sapogenins from 13 domestic plants have been investigated. As a result,Dioscorea nipponica, D. quinqueloba andSmilax china were found to have large amount of diosgenin. And pennogenin inTrillium kamtschaticum andParis verticillata, yuccagenin inAllium fistulosum, hecogenin inAgave americana and neochlorogenin inSolanum nigum were appeared to be major steroidal sapogenins.