安可信银离子免洗手消毒液的效果及安全性

目的评价一种以乙醇和银离子为主要成分的免洗手消毒液(安可信)的效果及其安全性。方法采用悬液定量杀菌试验、消毒剂对手消毒现场试验、急性经口毒性试验和小鼠骨髓嗜多染红细胞微核试验等方法,研究该免洗手消毒液杀菌效果以及安全性。结果银离子浓度为41.6 mg/kg、乙醇含量为54.4%(w/w)的该免洗手消毒液作用1 min,对大肠埃希菌、金黄色葡萄球菌和铜绿假单胞菌平均杀灭对数值>3.00;对白假丝酵母菌的平均杀灭对数值>4.00。该免洗手消毒液原液经37 ℃恒温培养箱保存3个月后,样品乙醇含量下降率为0.37%,银离子含量无下降。该免洗手消毒液对小鼠急性经口毒性LD₅₀>5 000 mg/kg,对新西兰家兔皮肤无刺激性,小鼠骨髓嗜多染红细胞微核试验结果为阴性。结论安可信银离子免洗手消毒液对细菌和真菌具有较好消毒作用;对人体无皮肤刺激;各项指标均符合国家要求。     

The moral distinction between killing and letting die in medical cases

In some medical cases there is a moral distinction between killing and letting die, but in others there is not. In this paper I present an original and principled account of the moral distinction between killing and letting die. The account provides both an explanation of the moral distinction and an explanation for why the distinction does not always hold. If these explanations are correct, the moral distinction between killing and letting die must be taken seriously in medical contexts.
Defeasibly, when an agent kills she takes responsibility, but when an agent lets die she does not take responsibility. Therein lies the moral distinction between killing and letting die. The distinction, however, is defeated when an agent is already responsible for the surrounding situation. In such cases, killing does not involve taking any further responsibility and letting die does not avoid taking any responsibility. Medical examples are frequently complicated because patients' autonomous choices impact upon medical practitioners' surrounding responsibility.     

利用微生物及微生物农药杀灭钉螺的初步研究

从洞庭湖血吸虫疫区土壤中分离出两种微生物 :紫红链霉菌Streptomycesviolaceoruber和自养黄色杆菌Xan thobacterautotrophics,将两菌进行培养 ,用稀释 10 0 0倍的培养液杀螺 ,结果表明 :处理 72h后 ,对钉螺的杀螺率分别为90 %、85 % ;BT生物杀虫剂、科诺特杀螟 5 5 %杀苏可性湿粉剂、科诺蔬丹 1.5 %苏阿可湿性粉剂、科诺千胜BT杀虫剂、华戎号 1.5 %甲胺基阿维菌素苯甲酸乳液 ,均稀释 10 0 0倍进行杀螺实验 ,结果发现含阿维菌素的微生物农药杀螺效果较好 (95 %— 10 0 % ) ,华戎号在 4 8— 72h之间其杀螺率均为 10 0 % ,而含BT的微生物农药杀螺效果相对较差(70 %— 95 % )。将微生物农药喷洒土壤进行的杀螺实验。结果表明 ,华戎号的杀螺效果较好 ,处理 4 8h后 ,杀螺率为 10 0 % ,千分之一的五酚钠溶液为对照杀螺剂 ,其杀螺率为 10 0 %。清水对照液的杀螺率为 0 %。     

Cell selectivity, mechanism of action and LPS-neutralizing activity of bovine myeloid antimicrobial peptide-18 (BMAP-18) and its analogs

To develop novel antimicrobial peptides (AMPs) with improved cell selectivity and potent LPS-neutralizing activity, we synthesized an 18 N-terminal residues peptide (BAMP-18) of bovine myeloid antimicrobial peptide-27 (BMAP-27) and its analogs (BMAP-18-W, BMAP-18-L, BMAP-18-I and BMAP-18-f). BMAP-18 and its analogs displayed much higher cell selectivity (about 4-97-fold increased) as compared to parental BMAP-27 because of their decreased hemolytic activity and retained antimicrobial activity. BMAP-27 caused near-complete dye leakage from bacterial-membrane-mimicking vesicles even at very low concentration of 0.5 μM, whereas BMAP-18 and its analogs induced very little dye leakage (less than 40%) even at 16 μM. These peptides induced near-complete membrane depolarization of Staphylococcus aureus cells under their MIC (4 μM). These results suggests that BMAP-18 and its analogs exhibit lethality toward microbes due to their ability to form small channels that permit the transit of ions or protons, but not molecules as large as calcein, and not by the membrane-disruption/perturbation mode. BMAP-18 and its analogs significantly inhibited nitric oxide (NO) production or tumor necrosis factor-α (TNF-α) release in LPS-stimulated mouse macrophage RAW264.7 cells at 10 μM. In particular, BMAP-18-W showed LPS-neutralizing activity comparable to that of BMAP-27. There was a significant linear correlation between the increase in the hydrophobicity of peptides and LPS-neutralizing activity. Although BMAP-18-W has lower hydrophobicity than BMAP-18-L, it showed higher LPS-neutralizing activity as compared to BMAP-18-L. This result suggests other important parameters of AMPs may be involved in their LPS-neutralizing activity, as well as positive charge and hydrophobicity.     

Computational procedure for a weighted diallel analysis

Summary A diallel analysis is described for the case in which the values of the characteristic used in an inheritance study have unequal variances. Such a characteristic can be a mean, a slope of a regression line, or the estimates of some parameter of a linear or nonlinear model. Computational formulae are presented which incorporate the necessary weighting along with the statistics of the Hayman-Jinks method for diallel analysis. The method described can also be used to perform a weighted diallel analysis based on means when there are unequal numbers of replications per cross. A simple example demonstrates the computations necessary to complete a weighted diallel analysis.Journal paper no. 87-117-J of the Kansas Agricultural Experiment Station. This study was conducted by the senior author in partial fulfillment for the PhD degree in genetics     

The bacterial alkyltransferase-like (eATL) protein protects mammalian cells against methylating agent-induced toxicity

In both pro- and eukaryotes, the mutagenic and toxic DNA adduct O⁶-methylguanine (O⁶MeG) is subject to repair by alkyltransferase proteins via methyl group transfer. In addition, in prokaryotes, there are proteins with sequence homology to alkyltransferases, collectively designated as alkyltransferase-like (ATL) proteins, which bind to O⁶-alkylguanine adducts and mediate resistance to alkylating agents. Whether such proteins might enable similar protection in higher eukaryotes is unknown. Here we expressed the ATL protein of Escherichia coli (eATL) in mammalian cells and addressed the question whether it is able to protect them against the cytotoxic effects of alkylating agents. The Chinese hamster cell line CHO-9, the nucleotide excision repair (NER) deficient derivative 43-3B and the DNA mismatch repair (MMR) impaired derivative Tk22-C1 were transfected with eATL cloned in an expression plasmid and the sensitivity to N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) was determined in reproductive survival, DNA double-strand break (DSB) and apoptosis assays. The results indicate that eATL expression is tolerated in mammalian cells and conferes protection against killing by MNNG in both wild-type and 43-3B cells, but not in the MMR-impaired cell line. The protection effect was dependent on the expression level of eATL and was completely ablated in cells co-expressing the human O⁶-methylguanine-DNA methyltransferase (MGMT). eATL did not protect against cytotoxicity induced by the chloroethylating agent lomustine, suggesting that O⁶-chloroethylguanine adducts are not target of eATL. To investigate the mechanism of protection, we determined O⁶MeG levels in DNA after MNNG treatment and found that eATL did not cause removal of the adduct. However, eATL expression resulted in a significantly lower level of DSBs in MNNG-treated cells, and this was concomitant with attenuation of G2 blockage and a lower level of apoptosis. The results suggest that eATL confers protection against methylating agents by masking O⁶MeG/thymine mispaired adducts, preventing them from becoming a substrate for mismatch repair-mediated DSB formation and cell death.     

Elemental analysis of the Mycobacterium avium phagosome in Balb/c mouse macrophages

Using a hard X-ray microprobe, we showed recently that in unstimulated peritoneal macrophages from C57BL/6 mice, the phagosome of pathogenic mycobacteria (Mycobacterium tuberculosis and Mycobacterium avium) can accumulate iron. We expanded our studies to the M. avium infection of peritoneal macrophages of Balb/c mice that show a similar degree of M. tuberculosis and M. avium-related chronic disease, but a higher susceptibility towards other intracellular pathogens such as Listeria monocytogenes, Leishmania major, or Brucella abortus as compared to C57BL/6 mice. Similar to C57BL/6 macrophages, the iron concentration in Balb/c macrophages increased significantly after 24 h of infection. A significant increase of the chlorine and potassium concentrations was observed in the Balb/c phagosomes between 1 and 24 h, in contrast with macrophages from C57BL/6 mice. The absolute elemental concentrations of calcium and zinc were higher in the mycobacterial phagosomes of Balb/c mice. We hypothesize that a potassium channel is abundant in the phagosome in macrophages that may be related to microbiocidal killing, similar to the requirement of potassium channels for microbiocidal function in neutrophils.     

Killing rate curve and combination effects of surfactin C produced from Bacillus subtilis complex BC1212 against pathogenic Mycoplasma hyopneumoniae

This study evaluated the killing rate as well as the antimycoplasmal effect of surfactins isolated from Bacillus subtilis complex BC1212, either alone or in combination with various antibacterials against Mycoplasma hyopneumoniae. Prior to the killing rate and the combination effect studies of surfactins, the minimal inhibitory concentrations (MICs) of various antibacterials and surfactins (consisting of surfactins A, B, C, and D) against M. hyopneumoniae were investigated. The MIC of all surfactins was found to be 64 μg/ml. The MICs of colistin (COL), norfloxacin (NFX), oxytetracycline (OTC), streptomycin (SM) and tiamulin (TIA) were >256, 0.063, 0.025, 4, and 0.015 μg/ml, respectively. In the killing rate curve studies, surfactin C at 2× MIC and 4× MIC concentrations was found to reduce viability by >3 log₁₀ c.c.u./ml within 2–4 h of incubation. Combination of surfactin C with other antibacterials showed additive interaction from the viewpoint of fractional inhibitory concentration (FIC) index of >0.5 but ≤2 as a borderline. Taking all results into consideration, surfactin C may be useful as a preventive or therapeutic adjuvant in the pathogenesis of mycoplasmal infection.     

Interactions between killer yeasts and pathogenic fungi

Abstract A total of 17 presumptive killer yeast strains were tested in vitro for growth inhibitory and killing activity against a range of fungal pathogens of agronomic, environmental and clinical significance. Several yeasts were identified which displayed significant activity against important pathogenic fungi. For example, isolates of the opportunistic human pathogen, Candida albicans , were generally very sensitive to Williopsis mrakii killer yeast activity, whilst killer strains of Saccharomyces cerevisiae and Pichia anomala markedly inhibited the growth of certain wood decay basidiomycetes and plant pathogenic fungi. Results indicate that such yeasts, together with their killer toxins, may have potential as novel antimycotic biocontrol agents.     

刺五加种群生态学的研究 Ⅱ．刺五加的种群统计

在３种天然次生林类型中,以刺五加的无性系小株为统计单位,编制该种群的生命表,分析其种群动态．结果表明,刺五加种群有２个死亡率高峰,在不同的森林群落中其死亡强度有较明显差异．种群的总亏损度不同,这些都与群落生境有关．该种群的存活曲线趋近于ＤｅｅｖｅｙⅢ型．