次抑菌浓度的药物诱导细菌耐药与交叉耐药

铜绿假单胞菌接种于含次抑菌浓度的哌拉西林和阿米卡星的营养肉汤中，葡萄球菌接种于次抑菌浓度的氧氟沙星和环丙沙星的营养肉汤中，经传代培养可获得相对应的耐药菌株。哌拉西林诱导耐药的铜绿假单胞菌对头孢他啶亦耐药，但对阿米卡星、环丙沙星、亚胺培南／西司他丁不耐药；阿米卡星诱导耐药的铜绿假单胞菌对哌拉西林亦耐药，但对头孢他啶、环丙沙星、亚胺培南／西司他丁没有交叉耐药；氧氟沙星或环丙沙星诱导耐药的葡萄球菌对氟喹诺酮类药物都有交叉耐药，但对苯唑西林、阿米卡星、亚胺培南／西司他丁没有显著的交叉耐药性     

临床分离铜绿假单胞菌喹诺酮耐药株gyrA基因突变及其对β-内酰胺类药物敏感性研究

利用PCR、限制性片段多态性分析（RFLP）、DNA单链构像多态性分析（SSCP）和DNA测序等方法，对10株成都地区临床分离耐喹诺酮类药物铜绿假单孢菌gyrA基因进行研究。结果表明，成都地区耐喹诺酮类药物铜绿假单胞菌gyrA的喹诺酮耐药决定区编码等83位氨基酸密码子表现出高频单点突变（10株中有8株），其突变方式为ACC→ATC。gyrA的PCR扩增产物SacII酶切片段与测序结果一致。SSCP的带谱与测序结果比较，除1株（PSA2）的SSCP带谱与标准株相同，但测序结果有点突变外，其余菌株与测序结果一致。因此，利用PCR－SSCP－RFLP系统，可快速、准确的检测耐喹诺酮类药物的铜绿假单胞菌gyrA中至少一个碱基的差异。用二倍稀释法测定喹诺酮和β－内酰胺类药物对耐药突变株体外抗菌活性，结果表明，铜绿假单胞菌gyrA基因突变株对诺氟沙星、环丙沙星、左氧氟沙星、头孢他啶、亚胺培南和哌拉西林表现出不同的敏感性。试验所用8株突变株对诺氟沙星和环丙沙星表现出高水平抗性；3株对左氧氟沙星敏感；3株对头孢他啶和哌拉西林表现出耐药，2株对亚胺培南耐药。     

多黏菌素B与其他抗菌药物联用对泛耐药铜绿假单胞菌体外抗菌活性的研究

目的评价多黏菌素B与左氧氟沙星、亚胺培南、哌拉西林/三唑巴坦体外联合应用,对临床分离的30株泛耐药铜绿假单胞菌的抗菌效应。方法采用微量肉汤稀释法、棋盘设计法测定多黏菌素B与左氧氟沙星、亚胺培南及哌拉西林/三唑巴坦单用及联合应用对临床分离的30株泛耐药铜绿假单胞菌的最小抑菌浓度(MIC),并计算FIC指数,判定联合效应:FIC≤0.5为协同作用,0.52.0为拮抗作用。结果多黏菌素B与左氧氟沙星、亚胺培南及哌拉西林/三唑巴坦联用后,各种药物对泛耐药铜绿假单胞菌的MIC值均显著降低,FIC指数在0~0.5、0.5~1的百分率分别为:左氧氟沙星联合组66.67%、26.67%,亚胺培南联合组46.67%、40%,哌拉西林/三唑巴坦联合组60%、33.33%。结论多黏菌素B与左氧氟沙星、亚胺培南、哌拉西林/三唑巴坦联用,对临床分离的30株泛耐药铜绿假单胞菌抗菌作用以协同和相加为主,无拮抗作用。     

铜绿假单胞菌对环丙沙星耐药与喹诺酮类耐药基因的关系研究

目的:探讨喹诺酮耐药(QNR)基因介导的铜绿假单胞菌对环丙沙星的耐药性。方法:用K-B纸片法测定30株铜绿假单胞菌对环丙沙星、庆大霉素、哌拉西林、头孢噻肟4种抗菌药物的敏感性。PCR法检测(QNR)基因。结果:铜绿假单胞菌对环丙沙星的耐药率为26.70%,1株环丙沙星耐药性铜绿假单胞菌携带有QNR基因。结论:铜绿假单胞菌对环丙沙星的耐药性与QNR基因有密切相关性。     

铜绿假单胞菌环丙沙星耐药株Ⅱ类拓扑异构酶基因突变的研究

用PCR方法，扩增26株临床分离铜绿假单力环丙沙星耐药株、4株环丙沙星敏感菌株和PA01菌株的Ⅱ类拓扑异构酶gyrA、gyrB、parC和parE基因的喹诺酮类药物耐药决定区（QRDR）基因片断；并对铜绿假单胞菌Ⅱ类拓扑异构酶基因突变与耐药性关系进行研究。结果表明90％以上的铜绿假单胞菌耐药株表现出Ⅱ类拓扑异构酶基因突变（26株中有24株）。突变主要发生在gyrA基因（22株）和parC基因（14株）上，其中gyrA基因的第83位氨基酸密码子表现出高频突变（22株中有21株，ACC→ATC，占90％），parC基因第80位氨基酸密码子也表现出较高的突变率（14株中有12株，TCG→TTG，占60％），4株耐药株的gyrB和3株耐药株的parE基因发生单点突变，2株耐药株Ⅱ类拓扑异构酶基因朱检测到突变。用二倍稀释法，测定部分喹诺酮和β→内酰胺类药物对耐药突变株的体外抗菌活性。表明铜绿假单胞菌Ⅱ类拓扑异构酶基因突变株对诺氟沙星、左氧氟沙星、哌拉西林、头孢他啶和亚胺培南表现出不同的敏感性。试验所用24株突变株对诺氟沙星呈现100％的耐药；对左氧氟沙星65％的耐药；40％的菌株对哌拉西林表现出耐药；30％的菌株对头孢他啶耐药；75％的菌株对亚胺培南敏感。     

多重耐药泵抑制剂提高肠球菌对氟喹诺酮药物敏感性的研究

目的　研究临床分离肠球菌对诺氟沙星、环丙沙星、氧氟沙星等氟喹诺酮药物耐药的主动泵出机制。方法　收集临床分离肠球菌 ;用琼脂二倍稀释法测定多重耐药泵抑制剂利舍平或维拉帕米应用前后 ,菌株对氟喹诺酮药物 MIC的变化。结果　利舍平使所有被检测的 2 9株肠球菌对诺氟沙星的敏感性增加 (MIC下降至原值的 1/ 2或以下 ) ,使 2 3株肠球菌对环丙沙星的敏感性增加 ,但仅能增加 3株肠球菌对氧氟沙星的敏感性。应用利舍平以后 ,12株耐诺氟沙星粪肠球菌对诺氟沙星 MIC值均下降 ,11株耐环丙沙星粪肠球菌有7株对环丙沙星 MIC值下降。维拉帕米的抑制效果和利舍平相比略有差异。结论　诺氟沙星、环丙沙星的主动泵出机制普遍存在于临床分离肠球菌 ,并且是粪肠球菌对诺氟沙星、环丙沙星的耐药机制之一。     

羟基氰氯苯腙对铜绿假单胞菌喹诺酮类药物耐药的抑制作用

目的：探讨铜绿假单胞菌对喹诺酮类药物（ FQS）的耐药机制,对临床合理应用抗生素提供参考依据。方法应用琼脂稀释法检测铜绿假单胞菌耐药株和敏感株在加入主动外排泵抑制剂羟基氰氯苯腙（CCCP）后对环丙沙星的最低抑菌浓度（MIC）变化情况。结果 CCCP浓度为5 mg/L时能明显增强环丙沙星对铜绿假单胞菌的敏感性,环丙沙星的敏感率由62．36％→78．82％,CCCP 在体外能增强FQS抗菌活性,27株耐环丙沙星铜绿假单胞菌11株敏感性增加,53株对环丙沙星敏感性菌株有3株MIC值下降,CCCP能使部分耐药细菌的MIC逆转。结论外排泵机制可能是造成铜绿假单胞菌对环丙沙星耐药的主要原因之一,泵抑制剂可部分逆转这种耐药性。     

泵抑制剂对嗜麦芽寡养单胞菌临床分离株氟喹诺酮类敏感性的影响

目的 了解嗜麦芽寡养单胞菌临床分离株外排泵的分布以及不同泵抑制剂对该菌氟喹诺酮类敏感性的影响。方法 用琼脂二倍稀释法检测泵抑制剂存在时，嗜麦芽寡养单胞菌对环丙沙星、氧氟沙星和诺氟沙星的敏感性变化。结果 羰基氰氯苯腙(CCCP)和利舍平降低部分嗜麦芽寡养单胞菌株对氟喹诺酮的耐药性。维拉帕米无明显泵抑制作用。泵阳性株存在于耐药和非耐药菌株中，集中于耐药性较高的菌株。泵抑制剂对该菌外排氧氟沙星的抑制大于对诺氟沙星和环丙沙星的作用。结论 多重外排泵是嗜麦芽寡养单胞菌对氟喹诺酮类耐药的原因之一。泵抑制剂可部分逆转这种耐药性。     

革兰阴性杆菌对四种氟喹诺酮药物体外耐药监测

目的了解革兰阴性杆菌(G-)对环丙沙星,左氧氟沙星,氧氟沙星,罗美沙星体外抗菌活性,为临床用药提供依据。方法采用K-B纸片法,对分离出的256株菌株进行耐药性监测,并用标准菌株进行监控,以NCCLS标准进行结果判读。结果大肠埃希菌对4种氟喹诺酮类药物有55%以上的耐药率。除铜绿假单胞菌外革兰阴性杆菌对左氧氟沙星的耐药率均低于其他3种药物,克雷伯菌、铜绿假单胞菌、不动杆菌对环丙沙星耐药率在30.76%～33.33%。结论G-杆菌对氟喹诺酮类药物有交叉耐药现象,医生应不断参考本地区细菌耐药变化,最大限度发挥氟喹诺酮药物的作用。     

哌拉西林与环丙沙星对铜绿假单胞菌的联合药敏研究

目的评价哌拉西林与环丙沙星联合应用对铜绿假单胞菌的体外联合杀菌作用.方法采用棋盘法设计,微量肉汤稀释法测定其MIC值,计算抑菌指数(FIC).结果哌拉西林与环丙沙星联合应用后,哌拉西林对铜绿假单胞菌的MIC50值由8mg/L降至0.25mg/L,环丙沙星对铜绿假单胞菌的MIC50由1mg/L降至0.25mg/L,FIC指数范围主要在0～l.结论哌拉西林与环丙沙星药物联合应用,对铜绿假单胞菌的体外抗菌作用以协同和相加为主.     

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.     

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.