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1.
RD Jolly AC Johnstone SD Williams K Zhang TW Jordan 《New Zealand veterinary journal》2013,61(5):210-217
AIM: To investigate an axonopathy of Merino sheep that caused progressive hindlimb ataxia and slight to moderate paresis, with the purpose of understanding its pathogenesis. METHODS: Tissues were fixed in buffered paraformaldehyde or paraformaldehyde and glutaraldehyde, processed into wax and epoxy resin, respectively, and examined by light and electron microscopy. Fresh frozen spinal cord and trigeminal nerve roots were subjected to homogenisation, centrifugation and two-dimensional electrophoresis. Selected protein spots were identified using matrix-assisted laser desorption ionisation (MALDI) mass spectrometry. RESULTS. By light microscopy, there were large pale foamy spheroidal axonal swellings affecting peripheral as well as central axons. By electron microscopy, these were shown to contain many membrane-bound vesicles. The main abnormalities in expressed proteins involved cytoskeletal elements and myosin heavy chain, the latter interpreted as associated with the molecular motor myosin Va. CONCLUSIONS: The disorder is the same as that described in Merinos in Australia as segmental axonopathy, and believed to have an inherited aetiology. The lesions and protein changes indicate abnormalities of the cytoskeleton, its relationship with the myelin sheath, and myosin Va molecular motor. The consequence appears to be abnormal axonal transport and inability to maintain the integrity of axons and their myelin sheaths. 相似文献
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Lizard and spider populations were censused immediately before and after Hurricane Lili on islands differentially affected by the storm surge. The results support three general propositions. First, the larger organisms, lizards, are more resistant to the immediate impact of moderate disturbance, whereas the more prolific spiders recover faster. Second, extinction risk is related to population size when disturbance is moderate but not when it is catastrophic. Third, after catastrophic disturbance, the recovery rate among different types of organisms is related to dispersal ability. The absence of the poorer dispersers, lizards, from many suitable islands is probably the result of long-lasting effects of catastrophes. 相似文献
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Self-oriented regular arrays of carbon nanotubes and their field emission properties 总被引：4，自引：0，他引：4
S Fan MG Chapline NR Franklin TW Tombler AM Cassell H Dai 《Science (New York, N.Y.)》1999,283(5401):512-514
The synthesis of massive arrays of monodispersed carbon nanotubes that are self-oriented on patterned porous silicon and plain silicon substrates is reported. The approach involves chemical vapor deposition, catalytic particle size control by substrate design, nanotube positioning by patterning, and nanotube self-assembly for orientation. The mechanisms of nanotube growth and self-orientation are elucidated. The well-ordered nanotubes can be used as electron field emission arrays. Scaling up of the synthesis process should be entirely compatible with the existing semiconductor processes, and should allow the development of nanotube devices integrated into silicon technology. 相似文献
4.
D. Van Der Kooij 《Water, air, and soil pollution》2000,123(1-4):25-34
Regrowth processes in drinking water distribution systems may lead to hygienic, aesthetic and technical problems. These complex processes depend on interactions between micro-organisms and (i), compounds serving as energy sources; (ii), environmental conditions (temperature, hydraulics) and (iii), physico-chemical processes (sedimentation, corrosion, disinfection), respectively. The concentration of growth-promoting compounds is considered as the main driving force for regrowth and a large variety of tests has been developed to assess the growth-promoting properties of treated water. These methods range from determining the decrease of the concentration of dissolved organic carbon in a batch test to the assessment of the Biofilm Formation Rate (BFR) in a flow-through test. Biostability assessment of treated water in the Netherlands includes the AOC test in combination with the BFR test. The growth-promoting properties of synthetic materials in contact with treated water are determined with the Biofilm Formation Potential (BFP) test. A complete understanding of regrowth processes enabling to define appropriate control measures requires further research including: (i), the effect of reactive surfaces on the availability of slowly degradable compounds, and (ii), improvement of mathematical models describing regrowth processes. 相似文献
5.
Hall N Karras M Raine JD Carlton JM Kooij TW Berriman M Florens L Janssen CS Pain A Christophides GK James K Rutherford K Harris B Harris D Churcher C Quail MA Ormond D Doggett J Trueman HE Mendoza J Bidwell SL Rajandream MA Carucci DJ Yates JR Kafatos FC Janse CJ Barrell B Turner CM Waters AP Sinden RE 《Science (New York, N.Y.)》2005,307(5706):82-86
6.
Superovulation is one important step in embryo transfer. By administration of gonadotropins a multiple ovulation is induced. Several FSH-preparations for superovulation are commercially available. Most of these consist of extracts from pituitary glands from slaughtered farm animals. According to some studies (Yagoda et al. 1990a,b), drugs can easily be contaminated with endotoxins. Endotoxins are commonly found in the environment, for example in water and silage, and in medical preparations (Yagoda et al. 1990b). Endotoxins can have several effects on animals and on human beings. They can cause endotoxaemia with effects like fever, ruminai stasis, release of prostaglandins, leukopenia and decrease of the plasma levels of calcium, zinc, iron and bile acids (Aiumlamai 1991). The severity and range of the effects caused by endotoxin are very dose-dependent. Animals receiving a low dose of endotoxin may not show the clinical signs of endotoxaemia, but can still have subclinical changes like leukopenia, prostaglandin release, mild hypocalcaemia and decreases in the plasma levels of zinc and iron (Yagoda et al. 1990b, Kindahl & Aiumlamai 1991). For humans, 5 EU/kg bodyweight is considered to be the threshold dose for appearance of clinical effects. (Anon. 1987). 相似文献
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Phloroglucinol has a long history of use for the determination of pentose monomer content. Its application to cereal chemistry has been developed over several decades; however, no studies on the potential influence of hydrolysis temperature have yet been reported. We demonstrate the effect of hydrolysis temperature on the phloroglucinol assay for the measurement of pentosans in both refined and wholemeal wheat flours. In refined flour, monosaccharide degradation and interfering reactions from starch appear to effectively reduce the absorbance difference used to determine pentosan content. The presence of glucose in the reaction is also shown to provide stability to the reaction products. The potential impact of these factors on the determination of pentosan content needs to be considered when interpreting the results obtained using phloroglucinol‐based methods. 相似文献
9.
TW Jordan 《New Zealand veterinary journal》2020,68(4):203-213
ABSTRACTThe fungal metabolite sporidesmin is responsible for the hepatogenous photosensitising disease facial eczema in livestock. Toxicity is due to a sulfur-bridged epidithiodioxopiperazine ring that has wide biological reactivity. The ways in which the toxin causes hepatobiliary and other tissue damage have not been established. Hypotheses include direct interaction with cellular thiols including protein cysteine residues or production of reactive oxygen species resulting in oxidative stress. Comparison with the cellular effects of the structurally related compound gliotoxin suggests additional mechanisms including interaction with cell adhesion complexes and possible downstream consequences for regulated necrosis as a response to tissue injury. Revision of hypotheses of how sporidesmin affects cells has the potential to generate new strategies for control of facial eczema including through identification of proteins and genes that are associated with resistance to the disease. 相似文献
10.
JW Schlipf Jr K Eaton P Fulkerson TW Riebold C Cebra 《Veterinary anaesthesia and analgesia》2005,32(4):7-8
Ketamine is a rapid acting, potent, nonspecific, noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist commonly used for inducing general anesthesia and for providing post-operative pain management and may possibly lessen the need for other potentially harmful or contraindicated analgesics in camelids, such as nonsteroidal anti-inflammatory drugs. Prior to determining the effectiveness of CRI ketamine for analgesia, a safe, sub-anesthetic dose was established that did not produce untoward side effects, sedation or alter normal behavior. Six healthy male alpacas (40–90 kg) were used for the trial and each acted as its own control. Each alpaca was randomly assigned to receive ketamine at 20 and 40 μg kg–1 minute–1 in 500 mL saline. A blinded observer recorded heart rate, respiratory rate, and body temperature hourly, and behavior for 8 hours. There was a 72-hour washout period between each dosing regime. An equal volume saline CRI without ketamine was used as a control. Each alpaca was allowed a one-week washout prior to being anesthetized with isoflurane using mask induction. After achieving a stable plane of anesthesia, the MAC value for isoflurane was determined. Ketamine was infused at 40 μg kg–1 pre-existing pain is unknown, but for elective procedures, preemptive analgesia using ketamine CRI in alpacas may be beneficial. 相似文献