Determination of the biological activity of Clostridium difficile toxins in in vivo and in vitro experiments

The biological activity of the filtrates of 29 C. difficile strains was studied in vivo (suckling white mice) and in vitro (cell cultures of different species and origin). The action of the filtrates on the experimental models in vivo was evaluated from the cytotoxic effect index, while in vitro the intensity of the cytotoxic effect was evaluated from the percentage of dead cells in the monolayer. The results of the comparative determination of toxicity characteristics in vivo and in vitro demonstrated that cell cultures were more sensitive experimental models than suckling white mice. The use of cell cultures permitted the quantitative evaluation of the cytotoxic activity of the filtrates under study, as well as the detection of their cell-directed action at minimal concentrations.     

Effect of treatments of different modalities on the nucleoside phosphate kinase activity of normal and neoplastic cells

The activity of nucleoside phosphate kinases was studied in experimental transplantable tumours under chemotherapy, in the liver of normal rats treated with hepatocarcinogens, or in human lung tumours after irradiation. The above factors have been found to increase the activity of uridine phosphate kinase, reducing at the same time the activity of thymidine phosphate kinase. The data suggest the existence of an unknown regulatory mechanism responsible for the normal levels of uridylates and thymidylates, thymidine kinase and uridine kinase shunt.     

Effect of polyethylene glycols of linear structure and different molecular weights on rat liver lysosomes]

The action of nonionic detergents--polyethyleneglycols of the linear structure with various molecular weight (from 700 to 15 000) on the lysosomes of rat liver was studied. Triton X-100 activated the acid phosphatase of the sum total fraction of lysosomes to a greater degree than the rest of the polyethyleneglycols. The action of polyethyleneglycols on the activation of acid phosphatase in the lysosome subfractions was inconstant. The result obtained is explained from the aspect of the morphological and biochemical heterogeneity of lysosomes. On the basis of comparison of personal data and literature data a supposition is put forward that the resistance of lysosomes to the action of the polyethyleneglycols in vitro and in vivo was the same.     

华西银腊梅挥发油化学成分的研究

用水蒸气蒸馏法提取华西银腊梅挥发油,并用气相色谱-质谱(GC-MS)联用技术对其挥发油的化学成分进行分析,结果共鉴定了其中的39种成分,所鉴定成分含量约占总检出量的87.83%。其化学成分主要为(Z,Z)-9,12-十八碳二烯酸甲酯(9.00%),壬醛(5.83%),二十一烷(5.69%),二十烷(5.08%),辛炔酸(4.50%),2,6,10,15-四甲基十七烷(3.93%),(Z)-6-十八烯酸甲酯(3.65%),3,8-二甲基十一烷(3.52%),1-十六碳炔(3.31%),肉豆蔻酸(2.86%),月桂醛(2.81%),壬酸(2.23%),5,6,7,7α-四氢-4,4,7α三甲基-2(4H)-苯并呋喃酮(2.18%)等。     

European checkerspots (Melitaeini: Lepidoptera,Nymphalidae) are not aposematic – the point of view of great tits (Parus major)

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DNA barcoding of South Africa’s ornamental freshwater fish – are the names reliable?

Trade in freshwater ornamental fish in South Africa is currently regulated by a ‘blacklist’ to prevent potentially invasive taxa from establishing in the country. Because its effective implementation requires accurate identification, the aim of the present study was to test whether DNA barcoding is a useful tool to identify freshwater fishes in the South African pet trade. A total of 351 aquarium fish specimens, representing 185 traded taxa, were sequenced for the mitochondrial COI barcoding marker in 2011 and 2012. Lake Malawi cichlids were treated as a single group due to a lack of resolution in their COI marker, resulting in a data set of 137 successfully sequenced taxa. The Barcode Of Life Database (BOLD) and GenBank were used for taxonomic assignment comparisons. The genetic identification matched the scientific name inferred from the trade name for 60 taxa (43.8%) using BOLD, and for 67 taxa (48.9%) using GenBank. A genetic ID could not be assigned in 47 (34.3%) cases using BOLD and in 37 cases (27%) using GenBank. Whereas DNA barcoding can be a useful tool to help identify imported freshwater fishes, it requires further development of publicly available databases to become a reliable means of identification.     

苯肼对红细胞在体衰老过程中微观流变特性的影响

在Brunara等人用苯肼使动物造成急性溶血性贫血的方法基础上,建立一种由急性溶血性贫血后,而诱发家兔幼红细胞增多的非正常生理状态的红细胞在体衰老模型,继而研究新生红细胞从产生到死亡死亡过程,即衰老过程的流变学特性的变化规律。通过对新生红细胞的压积、变形、取向及与之相应的全血的粘度、血沉等指标的连续60多天的监测,发现红细胞在衰老过程中的微观流变学特性确实有明显改变。红细胞在体衰老过程中微观流变特性逐渐变差。     

Effects of citronella oil (Cymbopogon winterianus Jowitt ex Bor) on Spodoptera frugiperda (J. E. Smith) midgut and fat body

The armyworm, Spodoptera frugiperda, is the principal pest of corn in Brazil. Control is achieved primarily by synthetic insecticides, which cause problems for the agro-ecosystem. Alternative methods of control are under investigation and citronella (Cymbopogon winterianus) essential oil appears to be a promising agent. We investigated the effects of citronella oil using histological, histochemical and immunohistochemical methods. The midgut of larvae treated with citronella exhibited altered epithelium including cytoplasmic protrusions, columnar cell extrusion, pyknotic nuclei, and increased periodic acid-Schiff positive granules. Regenerative cells in the epithelium of the midgut increased in number, which facilitated subsequent regeneration of this tissue. After exposure to citronella, trophocytes, the principal cell type of the fat body, possessed enlarged vacuoles and mitotic bodies, and contained reduced amounts of glycogen, lipid, and protein. Citronella oil caused morphological changes of the midgut and reduction of stored resources in the fat body, which may adversely affect insect reproduction and survival.     

Total sleep deprivation does not significantly degrade semantic encoding

ABSTRACT

Sleep deprivation impairs performance on cognitive tasks, but it is unclear which cognitive processes it degrades. We administered a semantic matching task with variable stimulus onset asynchrony (SOA) and both speeded and self-paced trial blocks. The task was administered at the baseline and 24 hours later after 30.8 hours of total sleep deprivation (TSD) or matching well-rested control. After sleep deprivation, the 20% slowest response times (RTs) were significantly increased. However, the semantic encoding time component of the RTs remained at baseline level. Thus, the performance impairment induced by sleep deprivation on this task occurred in cognitive processes downstream of semantic encoding.