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31.
Toxins of Clostridium botulinum (types A-G) are known as 'neurotoxins', causing the clinically well-known picture of flaccid muscular paralysis. The molecular biological background is the blocking of acetylcholine secretion in neuromuscular junctions by enzymatic cleavage of molecules forming the machinery of exocytosis. Two 'non-neurotoxins' (types C2, C3) are produced by some strains of C. botulinum types C and D. These affect the cytoskeleton by ribosylating actin filaments. All these toxins are used as cell biological tools for the study of specific actions and effects in different eukaryotic cells. Pharmaceutical and molecular biological research has shown their influence on several crucial organs (or cell cultures thereof) of humans and animals (brain and spinal cord, cerebellum, hippocampus, hypophysis, pancreas, adrenal glands, salivary glands and others). Under natural conditions, botulinum toxins may pass the intestinal barrier and circulate in the bloodstream for a certain time. Carriers occurring naturally in food, such as wheat germ agglutinin, digitonin or saponin, and bacterial toxins such as streptolysin O, perfringolysins, C2 toxin or botulinolysin may also form pores in cell walls. They facilitate the entry of botulinum toxins into cells that may not have natural binding receptors. It is concluded that in vivo actions of different botulinum toxins after their entry into the organism may contribute to the onset of different diseases of hitherto cryptogenic origin. Some examples are given and future problems are discussed.  相似文献   
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33.
Botulism is caused by different types of Clostridium botulinum, a soil bacterium. Equine grass sickness (equine dysautonomia) is suspected of being a clinical form of this disease. On a stud where this disease occurred twice within 8 months, grass and soil samples and necropsy specimens of one horse were tested for the presence of bacterial forms and toxin of C. botulinum. Different types and type mixtures (A-E) of C. botulinum and botulinum neurotoxin were found. For the first time, it has been shown that green grass blades contain botulinum toxin. The results support the hypothesis that equine grass sickness is a clinical form of botulism, a soil-borne disease.  相似文献   
34.
The cloning of equids was achieved in 2003, several years after the birth of Dolly the sheep and also after the cloning of numerous other laboratory and farm animal species. The delay was because of the limited development in the horse of more classical-assisted reproductive techniques required for successful cloning, such as oocyte maturation and in vitro embryo production. When these technologies were developed, the application of cloning also became possible and cloned horse offspring were obtained. This review summarizes the main technical procedures that are required for cloning equids and the present status of this technique. The first step is competent oocyte maturation, this is followed by oocyte enucleation and reconstruction, using either zona-enclosed or zona-free oocytes, by efficient activation to allow high cleavage rates and finally by a suitable in vitro embryo culture technique. Cloning of the first equid, a mule, was achieved using an in vivo -matured oocytes and immediate transfer of the reconstructed embryo, i.e. at the one cell stage, to the recipient oviduct. In contrast, the first horse offspring was obtained using a complete in vitro procedure from oocyte maturation to embryo culture to the blastocyst stage, followed by non-surgical transfer. Later studies on equine cloning report high efficiency relative to that for other species. Cloned equid offspring reported to date appear to be normal and those that have reached puberty have been confirmed to be fertile. In summary, horse cloning is now a reproducible technique that offers the opportunity to preserve valuable genetics and notably to generate copies of castrated champions and therefore, offspring from those champions that would be impossible to obtain otherwise.  相似文献   
35.
Since a case of a veterinarian was reported, who was likely to be infected/intoxicated by Clostridium botulinum during the handling of a diseased animal, tonsils in animals were tested for botulinum neurotoxin and bacterial forms of neurotoxic Clostridium botulinum during routine botulism laboratory examinations including standard samples (intestinal tract and liver) from 48 cattle, 11 horses, and 14 goats. Ten out of 60 samples from tonsils contained free botulinum toxin, and 12 out of 59 were positive for live toxin producing bacteria. In 32 out of 162 intestinal samples toxin was detected. Toxin producing bacteria were found in 37 samples. Eight of 56 liver samples contained free toxin, and 15 out of 43 toxigenic bacteria. Samples from 10 slaughter pigs were all negative, whereas from slaughter cattle tonsils had a high incidence of toxin (7 of 10) or toxigenic bacteria (2 of 8). The results are discussed in the context of effects on animal health and botulism as zoonosis.  相似文献   
36.
Posidonia oceanica (L.) Delile is traditionally used for its beneficial properties. Recently, promising antioxidant and anti-inflammatory biological properties emerged through studying the in vitro activity of the ethanolic leaves extract (POE). The present study aims to investigate the anti-inflammatory and analgesic role of POE in mice. Inflammatory pain was modeled in CD-1 mice by the intraplantar injection of carrageenan, interleukin IL-1β and formalin. Pain threshold was measured by von Frey and paw pressure tests. Nociceptive pain was studied by the hot-plate test. POE (10–100 mg kg−1) was administered per os. The paw soft tissue of carrageenan-treated animals was analyzed to measure anti-inflammatory and antioxidant effects. POE exerted a dose-dependent, acute anti-inflammatory effect able to counteract carrageenan-induced pain and paw oedema. Similar anti-hyperalgesic and anti-allodynic results were obtained when inflammation was induced by IL-1β. In the formalin test, the pre-treatment with POE significantly reduced the nocifensive behavior. Moreover, POE was able to evoke an analgesic effect in naïve animals. Ex vivo, POE reduced the myeloperoxidase activity as well as TNF-α and IL-1β levels; further antioxidant properties were highlighted as a reduction in NO concentration. POE is the candidate for a new valid strategy against inflammation and pain.  相似文献   
37.
Fusarium head blight, induced primarily by Fusarium graminearum, resulted in widespread damage to the Manitoba barley crops of 1993 and 1994, with contamination by deoxynivalenol (DON) and other 8-keto-trichothecenes. Visible Fusarium mold in samples of 1994 barley had little relationship to DON levels in the kernel as determined by gas chromatography-mass spectrometry (GC-MS). While samples of 1993 and 1994 barley showed a weak correlation between the logarithm of DON level and percentage of kernels infected by Fusarium graminearum (r = 0.79 and 0.71, respectively), the latter method is too lengthy and requires too much training for commercial application. A commercial enzyme immunoassay for DON gave results that correlated well with GC-MS methods (r = 0.95 and 0.89, respectively) in samples of 1993 and 1994 barley and afforded a rapid and convenient method for screening. In barley samples from 1994, DON, 15-acetylDON, 3-acetylDON and 3,15-diacetylDON were detected in the approximate ratio of 47:4:1:1. In view of the higher oral toxicities of 15-acetylDON and 3-acetylDON relative to DON, and the unknown oral toxicity of 3,15-diacetylDON, GC-MS assays might be advisable in samples positive for DON from enzyme immunoassay screening.  相似文献   
38.
Wet and dry deposition of atmospheric nitrogen (N) compounds into forest ecosystems and their effect on physical, chemical and microbial processes in the soil has attracted considerable attention for many years. Still the consequences of atmospheric N deposition on N metabolism of trees and its interaction with soil microbial processes has only recently been studied. Atmospheric N deposited to the leaves is thought to enter the general N metabolism of the leaves, but the processes involved, the interaction with different metabolic pathways, and the connection between injury by atmospheric N and its metabolic conversion are largely unknown. Laboratory and field experiments have shown that N of atmospheric NO2 and NH3, deposited to the leaves of trees, is subject to long-distance transport in the phloem to the roots. This allocation can result in considerable decline of N uptake by the roots. Apparently, the flux of N from the soil into the roots can be down-regulated to an extent that equals N influx into the leaves. This down-regulation is not mediated by generally enhanced amino-N contents, but by elevated levels of particular amino acids. Field experiments confirm these results from laboratory studies: Nitrate (NO3) uptake by the roots of trees at a field sites exposed to high loads of atmospheric N is negligible, provided concentrations of Gln in the roots are high. At the ecosystem level, consequences of reduced N uptake by the roots of trees exposed to high loads of atmospheric N are (1) an increased availability of N for soil microbial processes, (2) enhanced emission of gaseous N-oxides from the soil, and (3) elevated leaching of NO3 into the ground water. How recent forest management practices aimed at transforming uniform monocultures to more structured species-rich forests will interact with these processes remains to be seen. Possible implications of these forest management practices on N metabolism in trees and N conversion in the soil are discussed particularly in relation to atmospheric N deposition.  相似文献   
39.
Fire blight, caused by Erwinia amylovora, is a major disease threat to apple, pear and other pome fruit worldwide. The disease is widespread in Europe and has recently become established in Switzerland. Antibiotics are the most effective controls used in North America but these are not permitted for agricultural use in most European countries. A newly registered biological control product Biopro®, based on the antagonist Bacillus subtilis strain BD170, is being used as an alternative strategy for fire blight management. A specific molecular marker was developed for monitoring the spread of this agent on blossoms after Biopro® spray application in a Swiss apple orchard throughout the bloom period for 2years. Direct spraying resulted in efficient primary colonisation of pistils in flowers that were open at the time of treatment. Subsequent bacterial dissemination (secondary colonisation) of flowers that were closed or at bud stage at the time of treatment was observed but was found to be dependent on the timing of treatments relative to bloom stage in the orchard. Foraging honeybees were shown to be disseminators of Biopro®. We also report detection of the biocontrol agent in honey collected from hives where bees were exposed by placing Biopro® at the entrance or in the hatching nest and from hives that were simply placed in sprayed orchards.  相似文献   
40.
A simple and sensitive method for the confirmation of perfluidone residues in rice grains is described. The procedure involves extraction, purification on an anionexchange resin, chlorination, methylation and gas-chromatographic analysis with electron capture detection. The recoveries from fortified rice grains varied from 84.0 to 92.4% in the range 0.01–0.20 mg/kg. The sensitivity was such that perfluidone could be detected down to a level of 0.005 mg/kg. The method can be used for confirmation of perfluidone quantitatively as well as qualitatively.  相似文献   
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