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81.
Neoheterocotyle darwinensis n. sp. is described from between the secondary gill lamellae of the dwarf sawfish Pristis clavata Garman (Pristidae) collected at the mouth of Buffalo Creek near Darwin, Northern Territory, Australia. This is only the second monocotylid species to be described from northern Australia. N. darwinensis is distinguished from the other seven valid species in the genus by the morphology of the hamuli, the dorsal haptoral accessory sclerites and the male copulatory organ. The similarities between N. darwinensis and Nonacotyle pristis Ogawa, 1991 from the gills of the freshwater sawfish Pristis microdon Latham collected in Papua New Guinea are discussed. 相似文献
82.
In a previous longitudinal study, Mycobacterium avium subsp. paratuberculosis survived for 55 weeks in fecal material in the shade, but for much shorter periods in exposed locations. In this experiment, the survival of the organism was studied in 250 liters of dam water and sediment in large water troughs that were placed in either a semiexposed location or in a shaded location and compared to survival in fecal material and soil in the shaded location. Survival in water and/or sediment in the shade was for up to 48 weeks compared to 36 weeks in the semiexposed location. Survival in sediment was 12 to 26 weeks longer than survival in the water column. Survival in soil and fecal material in the terrestrial environment in the shaded location was only 12 weeks. Although disturbance to sediment could not be ruled out as a factor, there was evidence of dormancy in both the water column and the sediment, since the organism could not be recovered for several months before again becoming detectable. The results suggest that water may be a significant reservoir of M. avium subsp. paratuberculosis infection. Further research on the biology of the organism in aquatic environments is warranted. Animal health authorities will need to provide appropriate advice to farmers to minimize exposure of livestock to potentially infected water sources. Survival of the organism in water destined for human consumption will need to be addressed if the organism is found to be involved in the etiology of Crohn's disease. 相似文献
83.
Moaddel R Jozwiak K Yamaguchi R Cobello C Whittington K Sarkar TK Basak S Wainer IW 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2004,813(1-2):235-240
Liquid chromatography columns containing stationary phases based upon immobilized nicotinic acetylcholine receptors (nAChRs) were used to screen a series of conformationally constrained nicotine and anabasine derivatives for agonist activity. The alpha3beta4 nAChR and alpha4beta2 nAChR subtypes were used to prepare the chromatographic columns and [(3)H] epibatidine dihydrochloride ([(3)H] EB) was used as the marker ligand. Single displacement experiments were conducted with the test ligands and with nicotine and carbachol. Nicotine was used as an internal control for compounds with agonist activity and carbachol was used as an internal control for compounds with very weak agonistic activity (K(d) > 4700 nM for alpha3beta4). The displacement of [(3)H] EB by each of the test compounds and internal controls was calculated and expressed as Deltaml. Functional studies were then conducted using a stably transfected cell line that expresses the alpha3beta4 nAChR and EC(50) values were determined for the test compounds and the internal controls. A comparison of the Deltaml and EC(50) values indicated that 9/11 compounds had been correctly identified as agonists or non-agonists of the alpha3beta4 nAChR. A similar comparison could not be made for the alpha4beta2 nAChR, since the intact cell line was not available for testing. The results of the study suggest that the immobilized nAChR columns can be used for the rapid on-line screening of compounds for their relative affinities for the immobilized receptor and as an initial determination of qualitative functional activities. 相似文献
84.
Background
Cerebellar granule cell precursors are specifically generated within the hindbrain segment, rhombomere 1, which is bounded rostrally by the midbrain/hindbrain isthmus and caudally by the boundary of the Hoxa2 expression domain. While graded signals from the isthmus have a demonstrable patterning role within this region, the significance of segmental identity for neuronal specification within rhombomere 1 is unexplored. We examined the response of granule cell precursors to the overexpression of Hoxa2, which normally determines patterns of development specific to the hindbrain. How much does the development of the cerebellum, a midbrain/hindbrain structure, reflect its neuromeric origin as a hindbrain segment? 相似文献85.
Skatole, a derivative of tryptophan, is produced in the hind-gut of pigs and is metabolised via hepatic cytochrome P4502E1 (CYP2E1). Excessive accumulation of skatole together with androstenone, a metabolite of testosterone, in adipose tissue in some pigs is a major cause of 'boar taint' and is associated with defective expression of CYP2E1. This phenomenon is not understood because factors regulating CYP2E1 expression in pig liver have not yet been characterised. Therefore effects of skatole and androstenone on CYP2E1 expression were studied using isolated pig hepatocytes as a model system. Skatole induced CYP2E1 protein expression to the same degree as did acetone, a known CYP2E1 inducer. Induction by skatole was maximum between 20 and 28 h and a half-maximum effect was obtained at a skatole concentration of 0.2 mM. Induction of CYP2E1 by skatole was protein-synthesis dependent. Androstenone antagonised the effect of skatole on CYP2E1 expression but did not affect the CYP2E1 protein level when added alone. These results suggest that defective expression of CYP2E1 in some pigs is due to excessive concentrations of androstenone which prevent CYP2E1 induction by its substrate skatole. As a result, skatole metabolism is reduced and skatole is accumulated in adipose tissue. 相似文献
86.
Using circulant symmetry to model featureless objects 总被引:1,自引:0,他引:1
87.
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89.
Temporal lobe epilepsy is the most common form of partial-onset epilepsy and accounts for the majority of adult epilepsy cases in most countries. A critical role for the hippocampus (and to some extent amygdala) in the pathology of these epilepsies is clear, with selective removal of these regions almost as effective as temporal lobectomy in reducing subsequent seizure risk. However, there is debate about whether hippocampus is ‘victim’ or ‘perpetrator’: The structure is ideally placed to ‘broadcast’ epileptiform activity to a great many other brain regions, but removal often leaves epileptiform events still occurring in cortex, particularly in adjacent areas, and recruitment of the hippocampus into seizure-like activity has been shown to be difficult in clinically-relevant models. Using a very simple model of acute epileptiform activity with known, single primary pathology (GABAA Receptor partial blockade), we track the onset and propagation of epileptiform events in hippocampus, parahippocampal areas and neocortex. In this model the hippocampus acts as a potential seizure focus for the majority of observed events. Events with hippocampal focus were far more readily propagated throughout parahippocampal areas and into neocortex than vice versa. The electrographic signature of events of hippocampal origin was significantly different to those of primary neocortical origin – a consequence of differential laminar activation. These data confirm the critical role of the hippocampus in epileptiform activity generation in the temporal lobe and suggest the morphology of non-invasive electrical recording of neocortical interictal events may be useful in confirming this role. 相似文献
90.
Alexis Llewellyn Craig Whittington Gavin Stewart Julian PT Higgins Nick Meader 《PloS one》2015,10(12)