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201.
We have synthesized and evaluated a series of novel HCV NS3 protease inhibitors with various P4 capping groups, which include urea, carbamate, methoxy-carboxamide, cyclic carbamate and amide, pyruvic amide, oxamate, oxalamide and cyanoguanidine. Most of these compounds are remarkably potent, exhibiting single-digit to sub-nanomolar activity in the enzyme assay and cell-based replicon assay. Selected compounds were also evaluated in the protease-inhibitor-resistant mutant transient replicon assay, and they were found to show quite different potency profiles against a panel of HCV protease-inhibitor-resistant mutants.  相似文献   
202.
Paul E. Cooper 《CMAJ》1993,148(2):231-232
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203.
The importance of the cynomolgus monkey as a model for human reproductive medicine prompted this examination of epididymal sperm morphology. Computer-aided sperm morphological analysis was used for the first time to provide morphometric data on sperm heads as they traversed the epididymal duct of Macaca fascicularis. The duct was divided into six regions, starting close to the testis (proximal) and ending close to the vas deferens (distal). To determine the androgen-dependence of the changes, one group of animals received a GnRH-antagonist (Cetrorelix, Asta Medica, Frankfurt, Germany) to induce testicular regression and lower epididymal androgens, while a control group received only vehicle. Epididymides were removed 16 and 25 days after treatment, and sperm heads were analysed by a computer-assisted morphometric analyser. Cluster analysis revealed swollen sperm head cells in proximal regions 1 and 2 of the epididymis, but fewer such forms distally. Normal head shapes became the majority in region 4 and these underwent a gradual but statistically significant decrease in size (area, perimeter, length, width) and shape as they reached the distal regions. In the animals given Cetrorelix, sperm with swollen heads were found more distally than in the controls, although they were also never present in the distal cauda (region 6). Normal heads still became predominant in region 4 after 16 days treatment, and in region 6 after 25 days. The normal forms in the cauda epididymidis of treated animals were significantly larger than cells from control animals. We conclude that epididymal sperm maturation in the monkey is characterised by both a loss of sensitivity to distortion on air-drying, and by a decrease in sperm head size. The former, but not the latter, is attained by sperm in androgen-deficient epididymides from GnRH-antagonist-treated monkeys.  相似文献   
204.
The netrin family of axon guidance cues has been shown to play a pivotal role in the guidance of a variety of axon projections during embryonic development, both in the vertebrate and invertebrate. While the guidance potential of netrin-1 has been examined in depth in many regions of the developing mouse brain very little information is available on the expression and activity of netrin-3. Here we show that the netrin-3 protein is present on motor neurons and subpopulations of neurons within sensory and sympathetic ganglia. Moreover, significant levels of netrin-3 protein were found to be associated with the axons projecting from these neurons suggesting a role for netrin-3 in axon pathfinding and fasciculation within the peripheral nervous system.  相似文献   
205.
Morphological dynamics and membrane transport within the living Golgi apparatus of astrocytes labeled with NBD-ceramide were imaged using both electronically enhanced fluorescence video and laser confocal microscopy. In time-lapse recordings, continuous tubulovesicular processes are observed to emerge from trans-Golgi elements and extend along microtubules at average rates of 0.4 microns/s. In addition, discrete fluorescent particles are observed to emerge from the trans-Golgi and subsequently migrate along microtubules at comparable velocities. Frequently, tubulovesicular processes form stable connections that interlink adjacent trans-Golgi elements into an extensive reticulum. Laser photobleaching-recovery experiments reveal that tubulovesicular processes can provide direct pathways for the diffusion of membrane lipids between joined trans-Golgi elements. These results suggest that microtubule-based transport and membrane fusion can operate to interconnect certain cisternal membranes of adjacent Golgi elements within the cell.  相似文献   
206.
Two candidate methods for the recovery and detection of viruses in soil were subjected to round robin comparative testing by members of the American Society for Testing and Materials D19:24:04:04 Subcommittee Task Group. Selection of the methods, designated "Berg" and "Goyal," was based on results of an initial screening which indicated that both met basic criteria considered essential by the task group. Both methods utilized beef extract solutions to achieve desorption and recovery of viruses from representative soils: a fine sand soil, an organic muck soil, a sandy loam soil, and a clay loam soil. One of the two methods, Goyal, also used a secondary concentration of resulting soil eluants via low-pH organic flocculation to achieve a smaller final assay volume. Evaluation of the two methods was simultaneously performed in replicate by nine different laboratories. Each of the produced samples was divided into portions, and these were respectively subjected to quantitative viral plaque assay by both the individual, termed independent, laboratory which had done the soil processing and a single common reference laboratory, using a single cell line and passage level. The Berg method seemed to produce slightly higher virus recovery values; however, the differences in virus assay titers for samples produced by the two methods were not statistically significant (P less than or equal to 0.05) for any one of the four soils. Despite this lack of a method effect, there was a statistically significant laboratory effect exhibited by assay titers from the independent versus reference laboratories for two of the soils, sandy loam and clay loam.  相似文献   
207.
208.
This report aims to facilitate the implementation of the Three Rs (reduction, refinement and replacement) in the testing of vaccines for regulatory and other purposes. The focus is predominantly on identification of reduction and refinement opportunities in batch potency testing but the principles described are widely applicable to other situations that involve experimental infections of animals. The report should also help to interpret the requirements of the European Pharmacopoeia with regard to the use of alternative tests, humane endpoints and other refinements. Two specific worked examples, for batch potency testing of Clostridium chauvoei and canine leptospira, with recommendations for harmonisation of international test requirements for these and other vaccines, are provided as appendices online.  相似文献   
209.

Introduction  

The present study was conducted to determine whether patients with polymyalgia rheumatica (PMR) are at an increased risk of peripheral arterial disease (PAD).  相似文献   
210.
Direct photocatalytic water splitting is an attractive strategy for clean energy production, but multicomponent nanostructured systems that mimic natural photosynthesis can be difficult to fabricate because of the insolubility of most photocatalysts. Here, a solution‐processable organic polymer is reported that is a good photocatalyst for hydrogen evolution from water, either as a powder or as a thin film, suggesting future applications for soluble conjugated organic polymers in multicomponent photocatalysts for overall water splitting.  相似文献   
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