卡马西平增强γ-氨基丁酸对大鼠脑片的作用(英文)

目的:研究卡马西平(Car)对γ-氨基丁酸(GABA)在海马区域作用的影响.方法:在海马脑片(350μm)上刺激(0.5 Hz,50μs)Schaffer氏纤维,记录CA1区锥体细胞的诱发场电位.结果:Car 0.2mmol·L~(-1)对CA1区锥体细胞的诱发场电位没有明显影响,但Car 0.2 mmol·L~(-1)和GABA(0.1-1 mmol·L~(-1))同用抑制场电位作用比单用GABA时显著增强.Bicuculline不能翻转被Car加强的GABA的抑制作用.继而,左旋巴氯芬抑制场电位作用强于GABA.Car 0.2 mmol·L~(-1)和左旋巴氯芬(1-5μmol·L~(-1))同用抑制场电位作用比单用左旋巴氯芬时显著增强.结论:Car增强GABA对海马CA1区锥体细胞的抑制作用,其作用机制可能与GABA_B受体有关.     

牛磺酸对豚鼠乳头状肌慢反应动作电位的影响(英文)

目的:研究牛磺酸对豚鼠乳头状肌慢反应动作电位的影响.方法:高钾(24 mmol·L~(-1))或河豚毒素(40 μmol·L~(-1))诱发慢反应动作电位.哇巴因诱发振荡后电位.结果:牛磺酸(20mmol·L~(-1))减少V_(max),延长APD_(50)并拮抗氯化钙(3 mmol·L~(-1))增加APA和V_(max)及缩短APD的作用,增加哇巴因诱发OAP所需浓度并延长其发生时间.结论:牛磺酸有钙拮抗剂的性质     

未成年人心房肌细胞瞬间外向钾电流和内向整流钾电流的特性(英文)

目的:研究未成年人心房肌细胞瞬间外向钾电流(I_(to))和内向整流钾电流(I_(Kl))的特性。方法:膜片箝全细胞技术。结果:I_(to)是电压依赖性电流,快速激活,快速失活,被I_(to)的选择性阻断剂4-AP阻断。IC_(50)=0.64mmol·L~(-1)。4-AP1mmol·L~(-1)使I_(to)的半数激活电位增加;4-AP0.3mmol·L~(-1)使I_(to)的半数失活电位减少,对激活曲线没有明显影响并使I_(to)的恢复时间延长。I_(Kl)也表现出电压依赖的特性,其反转电位在-40mV。结论:在未成年人心房肌细胞上,I_(to)和I_(Kl)是两种重要的K~ 通道电流。4-AP0.3mmol·L~(-1)时对I_(to)的失活和失活后的恢复有明显影响,1mmol·L~(-1)时影响I_(to)的激活。     

戈那瑞林对大鼠脊神经节细胞GABA引起的去极化及GABA激活电流的调制作用(英文)

目的:探索戈那瑞林对大鼠初级感觉神经元膜GABA引起的去极化和GABA激活电流的调制作用。方法:应用细胞内记录和全细胞膜片钳技术分别在大鼠脊神经节(SG)标本和新鲜分离神经元进行实验。结果:GABA(10 μmol·L~(-1)—1mmol·L~(-1))在大多数神经元引起可为荷包牡丹碱(100μmol·L~(-1))所阻断的膜去极化。预加戈那瑞林(50μmol·L~(-1))可减少GABA引起的去极化,抑制率为79±22％(n=29),而戈那瑞林本身不产生膜反应或只引起轻微去极化。在11个细胞中有6个细胞GABA激活电流也为戈那瑞林的预处理所抑制,另5个细胞无改变或反应稍有增加。结论:戈那瑞林对初级感觉神经元GABA介导的去极化和GABA激活电流具有抑制作用。     

苄普地尔抑制大鼠海马CA1区锥体细胞钠电流(英文)

目的:研究苄普地尔对大鼠海马CA1区锥体细胞钠电流的影响。方法:膜片箝全细胞记录技术。结果:苄普地尔显著降低大鼠海马CA1区锥体细胞钠电流,作用呈时间及浓度依赖关系。苄普地尔10μmol·L~(-1)的半阻断时间约为10min。IC_(50)为2.6(2.3-2.9)μmol·L~(-1)。苄普地尔10μmol·L~(-1)右移最大电流的激活电位10mV,左移半失活膜电位18mV,表明其电压依赖地影响钠通道的激活和失活过程。结论:苄普地尔阻断大鼠海马CA1区锥体细胞钠电流,可能是其抗脑缺血机制之一。     

雌二醇抑制豚鼠心室肌细胞内向整流和延迟整流钾通道电流

目的:研究雌二醇(Estradiol,Est)对心室肌细胞动作电位(AP)、内向整流钾通道电流(I_(K1))及延迟整流钾通道电流(I_K)的影响。方法:全细胞膜片箝技术。结果:EST 10μmol·L~(-1)使豚鼠心室肌细胞AP时程明显缩短,APD_(50)由给药前(474±71)ms缩短至(330±75)ms(P<0.05),Est 100μmol·L~(-1)使APD_(50)缩短至(229±67)ms(P<0.01),使APD_(90)由(587±60)ms缩短至(418±79)ms(P<0.05)。Est浓度依赖性地抑制I_K尾电流(I_K·tail),10μmol·L~(-1)浓度下,I_K·tail减少53％(P<0.05),100μmol·L~(-1)浓度下,I_K·tail减少80％(P<0.05)。10μmol·L~(-1)以上浓度Est明显抑制I_(K1),在-100mV刺激电压下,内向电流最大抑制为49％(P<0.01);在-40mV刺激电压下,外向电流最大抑制为72％(P<0.01)。同时,Est使I_(K1)翻转电位向负电位方向移位(由-70mV变为-76mV)。结论:Est对豚鼠心室肌细胞I_(K1)和I_K通道具有明显的抑制作用。     

3-Morpholinosydnonimine-N-ethylcarbamide对缺氧诱发离体猪冠脉机械和电反应的影响(英文)

研究3-Morpholinosydnonimine-N-ethylcarbamide(SIN-1)对缺氧诱发离体猪冠脉机械和电反应的影响.方法:同步记录机械张力和膜电位.结果:缺氧可诱发离体猪冠脉平滑肌细胞膜去极化和收缩;SIN-1(100 μmol·L~(-1))和维拉帕米(Ver,10 μLmol·L~(-1))可使其复极化和松弛.SIN-1和Ver还可抑制左旋硝基精氨酸(NLA,0.2 mmol·L~(-1))和KCl(40mmol·L~(-1))诱发的离体猪冠脉去极化和收缩反应.结论:缺氧收缩离体猪冠脉是其抑制一氧化氮释放、增加Ca~(2 )内流的结果.     

烟碱诱导的海马脑片CA_1区长时程增强呈钙离子依赖性(英文)

目的:观察钙离子在烟碱诱导的大鼠海马脑片CA_1区长时程增强中的作用。方法:细胞外记录离体海马脑片CA_1区锥体细胞层群体峰电位。结果:至少烟碱1μmol·L~(-1)可诱导海马CA_1区长时程增强形成。移去脑脊液中的钙离子,烟碱不能诱导CA_1区长时程增强形成。硝苯地平1与10μmol·L~(-1)部分抑制而Tharpsigargin 1与10μmol·L~(-1)完全抑制烟碱诱导的长时程增强形成。结论:烟碱诱导的海马CA_1区长时程增强呈钙离子依赖性,胞外钙内流和胞内钙释放都参与了长时程增强形成。     

脑源性神经营养因子对大鼠海马神经元GABAA受体效应的影响

目的:观察不同浓度脑源性神经营养因子(BDNF)对大鼠海马神经元γ-氨基丁酸(GABA)A受体效应的影响。方法:原代培养海马神经元,应用BDNF(100、300及1000 ng/L)处理20 min后,施加GABA(终浓度为100μmol/L),5 min后应用流式细胞仪测定细胞内钙离子浓度。采用全细胞膜片钳记录模式,向锥体细胞施加BDNF(100、300及1000 ng/L)2 min,再施加GABA 100μmol/L并持续5 s,记录钳制电位为-60 mV时的GABAA受体电流。将神经元钳制电位从-100 mV至0 mV以10 mV递增,记录BDNF作用下GABAA受体电流的幅度和方向,并绘制电流电压曲线,计算GABAA受体电流的反转电位。结果:BDNF 100 ng/L和300 ng/L对GABA诱发的细胞内钙浓度、GABAA受体电流及反转电位均无影响,但在BDNF 1000 ng/L作用下,GABA诱发的细胞内钙浓度显著增加(P<0.05),GABAA受体电流在钳制电位-60 mV时变为外向电流,并且反转电位由对照的0 mV左移至-93 mV。结论:高浓度BDNF可使GABAA受体电流反转电位左移,导致GABA诱发锥体细胞内钙浓度增高而发挥兴奋效应。     

人参皂苷抗海马培养细胞缺氧损伤的作用(英文)

目的:观察人参皂苷抗脑细胞缺氧损伤的作用.方法:将12d培龄的海马细胞置于95％N_2 5％CO_2中4—24h,比较人参皂苷组和对照组细胞形态学.存活率及LDH和K~ 流出的变化.结果:缺氧24h后,对照细胞存活率从缺氧前92％±4％降至1.0％±2.0％;LDH和K~ 漏出量分别由2.3±0.6 U L~(-1)和5.56±0.16 mmol L~(-1)增至36±5 U L~(-1)和8.5±0.7 mmol L~(-1);此时,人参皂苷组细胞存活率为4％±4％;LDH漏出量为30 3 U L~(-1),K~ 含量为7.9士0.8 mmol L~(1).与对照组相比,人参皂苷组受损程度明显减轻.结论:人参皂苷具有抗海马细胞缺氧损伤的作用.     

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.     

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.     

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.     

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.