利福霉素B产生菌的推理选育

利福霉素B由地中海拟分枝酸菌产生，本文对工业生产菌株A.mediterraneiX1－02进行进一步筛选。采用推理选育的方法使产生菌减轻由芳香族氨基酸（色氨酸（tup）、苯丙氨酸、酪氨酸)和对羟基苯甲酸（PHBA，pbh）引起的对利福霉素B生成合成的反馈抑 制作用，并提高对前体丙酸（prp）的耐受量。通过UV诱变提高诱变株的耐受性，获得了高产菌株A.mediterraneiXC9－25（trp′，phb′，prp′），其生产能力达到10000u/ml，较原始出发菌株A.mediterraneiX1－02提高了1．385倍。动力学试验结果利用福霉素B的生物合成与菌体生长不同步，属于非生长偶联型。     

由地中海诺卡氏菌的一株重组体产生新利福霉素

在产生抗生素新衍生物的放线菌研究中,采用遗传操作创造新遗传型的有效法有三种,即突变、重组和质粒转移。已有研究指出,地中海诺卡氏菌(N.mediterranei)突变后得到许多生物合成障碍突变型菌株,这样的菌株只能合成利福霉素B的各种前体物利福霉素SV、W和I,而不能合成利福霉素B,这些前体物被认为是新的利福霉素。地中海诺卡氏菌遗传重组是用两株营养缺陷型进行的,一个亲株产生利福霉素B和另一株产生利福霉素W之间的种内重组,筛选     

低糖利福霉素产生菌S36-10^#的选育

利福霉素类抗生素是各国近年来研究较多的半合成抗生素。利福霉素SV(Rifamycin)是广谱抗生素之一，也是合成利福平、利福定等抗结核药的重要中间体。它是由地中海诺卡氏菌经液体发酵提取纯化而得。目前国内利福霉素发酵水平低，为了提高发酵水平和生产能力，就得降低成本。本文就是以S36做出发菌株，在选育过程中降低糖含量获得的生产所需的高产菌株S36 10^#用于生产。     

利福霉素产生菌的推理选育

用超声波处理利福霉素产生菌地中海诺卡氏菌所得的菌丝片断比石英砂处理所得菌丝片断的敏感性高。将超声波处理所得的菌丝片断,经UV诱变处理后,菌株分别经L—色氨酸、氯化铯等类似物做耐受性处理,获得利福霉素SV的高产菌株,产量提高10％左右。     

国产力复霉素注射剂的毒性与药理研究

力复霉素即利福霉素SV(Rifamycin SV),是一种新抗菌素。Sensi等首先发现从地中海链霉菌(S.mediterranei)产生利福霉素B。国外利福霉素SV生产初期主要是通过利福霉素B化学转化而得。我国四川抗菌素工业研究所1972年从桂林池塘泥土中分离得到了新的利福霉素产生菌——小单孢菌S—190(MicromonsporaS—190),它直     

利福平的临床应用——探讨对肺结核的治疗问题

利福霉素SV,利福霉素B二乙胺及利福平是利福霉素类抗菌素中评价最高的抗结核新药,也是抗菌、抗麻风新药,主要用于肺结核复治。1957年,意大利首先从法国土壤中分离出地中海链丝菌,在培养发酵液中发现利福霉素。后来,又从各国土壤中分离的链丝菌,选出产生菌,在发酵液中获得利福霉素A、B、C、D、E五种新抗菌素,从利福霉素B氧化获得利福霉素O,水解获得利福霉素S,再还原获得利福霉素SV(Rifamy     

埃博霉素高产菌株的诱变筛选

目的:探讨埃博霉素高产菌株的诱变筛选方法与效果.方法:选择原始菌株DES35 进行原始培养,在培养中进行硫酸二乙酯化学诱变筛选.结果:筛选到了6 株产量有所提高的突变株.高产菌株的埃博霉素A 与B 的平均产量与诱变前都有明显提高(P＜0.05).结论:埃博霉素高产菌株的硫酸二乙酯诱变筛选能使埃博霉素产量稳定提高,为埃博霉素生产提高了良好的菌株资源.     

新来源棘白霉素B脱酰基酶产生菌的筛选和转化条件优化

目的筛选放线菌来源的棘白霉素B脱酰基酶产生菌,并对其转化条件进行优化。方法根据菌株转化产物对白念珠菌的抑制活性进行初筛,再以HPLC、LC-MS检测确定目的菌株;对目的菌株转化棘白霉素B的培养基、转化温度和时间、缓冲液、甲醇含量等条件进行优化以提高转化率。结果筛选得到4株可产生脱酰基酶的阳性菌株,其中,N07W-.61为小单孢菌属菌株,其余3株为链霉菌属菌株;通过转化条件优化,菌株N07W-61对棘白霉素B的转化率从2.60%提高至61.24%。结论小单孢菌属菌株产生棘白霉素B脱酰基酶为首次报道;该属菌株N07W-61在优化转化条件下对棘白霉素B的转化率有了大幅提高。     

由地中海诺卡氏菌的一株重组体菌株 R21产生的3-羟基利福霉素 S 和其他新的安莎霉素类

3-羟基利福霉素S的结构和六种新的安莎霉素类是由地中海诺卡氏菌的一株重组体R21分离到的。三种构型区别:Ⅰ型:利福霉素S型的安莎霉素;Ⅱ型:利福霉素G型的安莎霉素;Ⅲ型:利福霉素W型的安莎霉素。地中海诺卡氏菌重组体R21菌株能产生许多新的安莎霉素,其中七种可用硅胶柱反复层析分离精制和制备TLC。这些新的安莎霉素类可分三种类型:Ⅰ.利福霉素S型的安莎霉素类:3-羟基利福霉素S;3,31-双羟基利福霉素S。Ⅱ.利福霉素G型的安莎霉素:16,17-去羟基利福霉素G。Ⅲ.利福霉素W型的安莎霉素类:利福霉素W-内酯;利福霉素     

利福霉素生物合成的进展

引言利福霉素产生菌于1957年首先由意大利米兰 Leptit 研究室从法国南部拉斐尔植物园的土壤中分离获得。该菌经鉴定为地中海诺卡氏菌(Nocardia mediterranea),在普通的培养基中至少可产生5个组份,称为利福霉素 A、B、C、D 和 E,其中仅 B 可被精制。它的活性较小,但通过化学方法使其“活化”,包括氧化利福霉素 B 为利福霉素 O,然后水解为活性高的利福霉素 S,并继续还原为利福霉素 SV,它们的结构见图1。     

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.