通过获得链霉素抗性基因(str)突变株筛选梅岭霉素高产菌株

本文通过链霉素对梅岭霉素（meilingmycin）产生菌南昌链霉菌NS－41－80菌株孢子致死浓度的测定，采用诱变剂EMS四种不同诱变剂量对菌株的孢子进行诱变处理，诱变处理的孢子涂布在含链霉素致死浓度的高氏平板上，获得了大量的链霉素抗性基因（str）突变株。然后从链霉素抗性基因突变株进一步筛选到梅岭霉素高产菌株80－5．11－221，在摇瓶条件下，只产梅岭霉素不产南昌霉素，梅岭霉素活性效价达1500μg/ml，比出发菌株NS－41－80的摇瓶发酵效价855μg/ml提高了77．9％，该菌株连续传代六代进行摇瓶发酵，其F2代和F3代梅岭霉素发酵效价稳定，F4代至F6代随着传代数增加，其梅岭霉素发酵效价急速下降。通过EMS诱变剂量分别与抗药性突变率和链霉素抗性基因突变株产梅岭霉素产量的产势统计分析表明，菌株抗药性突变与产抗生素突变密切相关，产抗生素突变的EMS诱变剂量高于链霉素抗性基因突变诱变剂量。在0．03mol/L的EMS剂量作用下，菌株致死率为99．43％，而抗药性突变率为0．0440％，建立了梅岭霉素产生菌链霉素抗性基因突变筛选方法，为南昌链霉菌高产菌种选育研究作了有益的尝试，并有助于其它链霉菌属的抗生素产生菌育种研究。     

组合庆大霉素和利福平二种抗性突变提高蜡状芽孢杆菌2045合成抗生素FR-900493的水平

组合庆大霉素和利福平二种抗性突变提高蜡状芽孢杆菌2045合成抗生素FR－900493的水平以蜡状芽孢杆菌2045为出发菌，首先筛选其对庆大霉素抗性的突变性，再以产量获得提高的庆大霉素对性突变株作为出发菌株，筛选其对利福平的抗性突变株。结果表明，庆大霉素能够有效地诱导野生菌过量合成抗生素FR－900493，有效突变频率为8％左右，利福平与庆大霉素无交叉耐药，进一步诱导耐庆大霉素，又耐利福平的突变株，FR－900493合成量较野生株提高5到6倍。表明组合抗生素的抗性为能够成为优化抗生素产生菌株的有效方法。     

链霉素抗性筛选法在选育博来霉素A2组分高产菌株中的应用

应用链霉素抗性筛选法提高博来霉素产生菌Streptomycin verticillus SIPI 7011产博来霉素A2组分的产量，将经紫外线诱变处理过的博来霉素产生菌孢子涂布在含有链霉素最小抑制浓度（180μg／ml）的培养基平板上，获得了151株链霉素抗性突变株。其中博来霉素A2产量高于出发菌株的有19株，产量阳性效率达到12．6％，并获得一株产抗生素能力为出发菌株约1．25倍的突变株。     

链霉素抗性突变理性筛选avermectin高产菌株

为提高菌株avermectin的产量，本文以链霉素抗性为选择压力，对除虫链霉菌Streptomyces avermi-tilis进行紫外诱变（253.7nm,30w，照射时间45s)，得到在摇瓶发酵水平比出发菌株产量提高25%以上的4株突变株，其中2株提高水平达30%以上，实验表明了链霉素抗性突变与产抗生素突变之间的密切联系。同时，对其机理和意义作了一些探讨。     

麦考酚酸高产菌株的选育

以短密青霉MA-4为出发菌株，应用紫外和亚硝基胍诱变，结合麦考酚酸与三氟乙酸抗性筛选，获得高产、稳定的突变株MA—H8。经过发酵培养基优化，突变株发酵水平为4500μg／ml。     

万古霉素产生菌的选育

以东方拟无枝酸菌（Amycolatopsisoriental）05—12为出发菌株,经紫外线（15W。253．7nm,距离18cm,照射5m）诱变处理,在含庆大霉素1000μg·mL^-1的浓度梯度平板上筛选庆大霉素抗性变株,得到一株万古霉素高产交株（Amyeolatopsisoriental）06-4。其摇瓶效价较出发菌株提高23％．对万古霉素的抗性提高200％。传代试验表明该变株的高产性能遗传特性较稳定。用正交试验法对万古霉素发酵培养基进行了优化,与原发酵培养基相比,万古霉素的摇瓶发酵效价提高了13．4%。     

纳他霉素高产菌株的链霉素抗性选育及其发酵工艺的优化

用紫外线对纳他霉素(Natamycin)产生菌褐黄孢链霉菌(Streptomyces gilvosporeus)ATCC13326菌株孢子进行诱变处理后，利用链霉素抗性突变选育得122株链霉素抗性突变株。其中纳他霉素产量高于出发菌株的有13株。突变株SG-56的生产能力达到出发菌株的146％，研究了其发酵性能，优化了培养基组成和发酵工艺条件，纳他霉素产量为2．81g／L，较出发菌株产量提高了170％。     

链霉素抗性突变-万古霉素高产菌株的选育研究

以东方拟无枝酸菌(Amycolatopsis orientalis)AO-4为出发菌株，经紫外线(15w，253．7nm，距离30cm)诱变处理，筛选链霉素抗性突变株(链霉素浓度1000μg／ml)，从中获得万古霉素高产变株Amycolatopsis orientalis AO-29，其发酵效价较出发菌株提高170%。传代实验表明该变株的高产性能遗传特性较稳定。     

ARTP诱变结合抗性筛选选育西索米星高产菌株

目的 利用等离子体诱变,结合抗生素抗性筛选,获得西索米星高产菌株。方法 首先通过链霉素抗性筛选,获得一株比出发菌株产抗能力高的S4;随后以S4为出发菌株,经等离子体处理40s,借助巴龙霉素抗性筛选,得到双重抗性菌株。最后对突变株进行再次诱变,并结合高浓度链霉素抗性筛选。结果 获得一株高产突变株M. inyoensis SAAP22,比出发菌株效价提高了38.18%,具有稳定的遗传性能。结论 通过等离子体诱变,结合抗生素抗性筛选,可有效提升伊尼奥小单孢菌的西索米星合成能力,所得高产菌株具有潜在应用价值。     

西罗莫司高产突变株FC904-33

西罗莫司是吸水链霉菌FC904产生的新型强效免疫抑制剂。为了获得高产西罗莫司突变株,采用UV、硝苯胍和甲基磺酸乙酯诱变剂诱变处理吸水链霉菌FC904的孢子悬液和发芽孢子,随后用西罗莫司对存活菌株进行自身代谢产物的耐受性试验,获得西罗莫司高产突变株FC904-33,其生物合成能力是原出发菌株的4.6倍。本文报道该突变株的培养特征、对抗生素的敏感性、西罗莫司生产能力和副产物等。     

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.

     

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.     

2-(Acetoxyphenyl)-(Z)-styryl sulfides as cyclooxygenase inhibitors

2-(Acetoxyphenyl)-(Z)-styryl sulfides are described as selective cyclooxygenase-2 (COX-2) inhibitors, useful for treating inflammation and COX-2-mediated disorders including neoplasia. 2-(Acetoxyphenyl)-(Z)-styryl sulfide is claimed to be the most potent COX inhibitor in the series with a COX-2 selectivity ratio of 33. This compound is also claimed to be superior to celecoxib (Celebrex^®, Pfizer) in inhibiting cell growth of colorectal carcinoma cells. In this evaluation, the COX inhibitory activity of this compound is compared to that previously disclosed for diarylheterocycles and 2-(acetoxyphenyl)alkyl sulfides. The validity of the DLD-1 cell line in the growth inhibition studies is questioned based on recent literature reports indicating the lack of COX-2 expression in this cell line.     

Sleep-disordered breathing with chronic opioid use

Chronic opioid use for pain relief or as substitution therapy for illicit drug abuse is prevalent in our societies. In the US, retail distribution of methadone and oxycodone has increased by 824 and 660%, respectively, between 1997 and 2003. μ-Opioids depress respiration and deaths related to illicit and non illicit chronic opioid use are not uncommon. Since 2001 there has been an emerging literature that suggests that chronic opioid use is related to central sleep apnoea of both periodic and non-periodic breathing types, and occurs in ～ 30% of these subjects. The clinical significance of these sleep-related abnormalities are unknown. This review addresses the present knowledge of control of ventilation mechanisms during wakefulness and sleep, the effects of opioids on ventilatory control mechanisms, the sleep-disordered breathing found with chronic opioid use and a discussion regarding the future research directions in this area.     

Drug targets for cognitive enhancement in neuropsychiatric disorders

The investigation of novel drug targets for treating cognitive impairments associated with neurological and psychiatric disorders remains a primary focus of study in central nervous system (CNS) research. Many promising new therapies are progressing through preclinical and clinical development, and offer the potential of improved treatment options for neurodegenerative diseases such as Alzheimer's disease (AD) as well as other disorders that have not been particularly well treated to date like the cognitive impairments associated with schizophrenia (CIAS). Among targets under investigation, cholinergic receptors have received much attention with several nicotinic agonists (α7 and α4β2) actively in clinical trials for the treatment of AD, CIAS and attention deficit hyperactivity disorder (ADHD). Both glutamatergic and serotonergic (5-HT) agonists and antagonists have profound effects on neurotransmission and improve cognitive function in preclinical experiments with animals; some of these compounds are now in proof-of-concept studies in humans. Several histamine H3 receptor antagonists are in clinical development not only for cognitive enhancement, but also for the treatment of narcolepsy and cognitive deficits due to sleep deprivation because of their expression in brain sleep centers. Compounds that dampen inhibitory tone (e.g., GABA_A α5 inverse agonists) or elevate excitatory tone (e.g., glycine transporter inhibitors) offer novel approaches for treating diseases such as schizophrenia, AD and Down syndrome. In addition to cell surface receptors, intracellular drug targets such as the phosphodiesterases (PDEs) are known to impact signaling pathways that affect long-term memory formation and working memory. Overall, there is a genuine need to treat cognitive deficits associated with many neuropsychiatric conditions as well as an increasingly aging population.