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Illicit trade carries the potential to magnify existing tobacco-related health care costs through increased availability of untaxed and inexpensive cigarettes. What is known with respect to the magnitude of illicit trade for Vietnam is produced primarily by the industry, and methodologies are typically opaque. Independent assessment of the illicit cigarette trade in Vietnam is vital to tobacco control policy. This paper measures the magnitude of illicit cigarette trade for Vietnam between 1998 and 2010 using two methods, discrepancies between legitimate domestic cigarette sales and domestic tobacco consumption estimated from surveys, and trade discrepancies as recorded by Vietnam and trade partners. The results indicate that Vietnam likely experienced net smuggling in during the period studied. With the inclusion of adjustments for survey respondent under-reporting, inward illicit trade likely occurred in three of the four years for which surveys were available. Discrepancies in trade records indicate that the value of smuggled cigarettes into Vietnam ranges from $100 million to $300 million between 2000 and 2010 and that these cigarettes primarily originate in Singapore, Hong Kong, Macao, Malaysia, and Australia. Notable differences in trends over time exist between the two methods, but by comparison, the industry estimates consistently place the magnitude of illicit trade at the upper bounds of what this study shows. The unavailability of annual, survey-based estimates of consumption may obscure the true, annual trend over time. Second, as surveys changed over time, estimates relying on them may be inconsistent with one another. Finally, these two methods measure different components of illicit trade, specifically consumption of illicit cigarettes regardless of origin and smuggling of cigarettes into a particular market. However, absent a gold standard, comparisons of different approaches to illicit trade measurement serve efforts to refine and improve measurement approaches and estimates.  相似文献   
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During spermatogenesis, germ cells undergo mitotic and meiotic divisions to form haploid round spermatids which mature to functional elongated spermatozoa. During this process there occurs remodeling of cell structure and loss of most of the cytoplasm and a large fraction of cellular proteins. To evaluate the role of the ubiquitin proteolytic system in this protein loss, we measured levels of ubiquitinated proteins and rates of ubiquitin conjugation in extracts of testes from rats of different ages. Endogenous ubiquitin-protein conjugates increased till day 30 and then reached a plateau. In parallel, there was a progressive increase in the rate of conjugation of ubiquitin to proteins in testis extracts from these animals. To test the importance of two major ubiquitin conjugating enzyme families in the conjugation, immunoprecipitation of UBC2 or UBC4 from 10- and 30-day-old testis extracts was carried out and the remaining conjugation activity in supernatants was assayed. Depletion of either enzyme family resulted in decreased conjugation. However, most of the conjugation activity and, more importantly, the increased conjugation during development were UBC4-dependent. Immunocytochemistry demonstrated a marked increase in expression of UBC4 in spermatids, consistent with the UBC4-dependent activation of conjugation seen in vitro. In situ hybridization studies evaluated the contribution of various UBC4 isoforms to this induction. UBC4-1 mRNA was expressed in most cells. UBC4-2 mRNA was restricted to germ cells with high levels of expression in round and elongated spermatids. UBC4-testis had previously been shown to be expressed only in spermatids. Our data suggest that induction of various UBC4 isoforms activates overall conjugation and plays an important role in the cellular remodeling and protein loss occurring during spermatogenesis.  相似文献   
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High-resolution microscopy methods based on different nonlinear optical (NLO) contrast mechanisms are finding numerous applications in biology and medicine. While the basic implementations of these microscopy methods are relatively mature, an important direction of continuing technological innovation lies in improving the throughput of these systems. Throughput improvement is expected to be important for studying fast kinetic processes, for enabling clinical diagnosis and treatment, and for extending the field of image informatics. This review will provide an overview of the fundamental limitations on NLO microscopy throughput. We will further cover several important classes of high-throughput NLO microscope designs with discussions on their strengths and weaknesses and their key biomedical applications. Finally, this review will close with a perspective of potential future technological improvements in this field.  相似文献   
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Recent observations have indicated that eukaryotic initiation factor (eIF)-2 and GTP or GDP normally bind to 60 S ribosomal subunits in rabbit reticulocyte lysate and that when eIF-2 alpha is phosphorylated and polypeptide chain initiation is inhibited, eIF-2 X GDP accumulates on 60 S subunits due to impaired dissociation that is normally mediated by the reversing factor (eIF-2B). Current findings now indicate that inhibition due to phosphorylation of eIF-2 alpha is mediated, at least in part, by the inability to dissociate eIF-2 X GDP from the 60 S subunit of complete initiation complexes. At the onset of inhibition, there is an accumulation of Met-tRNA(f) and eIF-2 on the polysomes, despite a marked reduction in Met-tRNA(f) bound to 40 S subunits and Met-peptidyl-tRNA bound to the polysomes. This initial effect is not associated with the formation of "half-mers" (polysomes containing an extra unpaired 40 S subunit), and the 40 S X Met-tRNA(f) complexes, though reduced, still sediment at 43 S. When inhibition is maximal and the polysomes are largely disaggregated, there is an accumulation of 48 S complexes consisting of a 40 S subunit and Met-tRNA(f) bound to globin mRNA as well as small polysomal half-mers, such that residual protein synthesis occurs to about the same degree on "1 1/2"s and "2 1/2"s as on mono-, di-, and triribosomes. Exogenous eIF-2B increases protein synthesis on mono-, di-, and triribosomes and decreases that on half-mers. This is associated with reduced binding of Met-tRNA(f) and eIF-2 to ribosomal particles sedimenting at 80 S and greater and a shift from 48 S to 43 S complexes. These results suggest that eIF-2B must normally promote dissociation of eIF-2 X GDP from the 60 S subunit of complete initiation complexes before they can elongate but cannot when eIF-2 alpha is phosphorylated, resulting in the accumulation of these complexes, some of which dissociate into Met-tRNA(f) X 40 S X mRNA and 60 S X eIF-2 X GDP.  相似文献   
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Plant seed storage proteins were among the first proteins to be isolated (20); however, only recently, as a result of using molecular biology techniques, have the amino acid sequences of many of these proteins been determined. With the accumulation of amino acid sequence data for many vicilin-type storage proteins much has been learned concerning the location of conserved amino acid regions and other regions which can tolerate amino acid sequence variation. Combining this knowledge with recent advances in plant gene transfer technologies will allow molecular biologists to correct (by using amino acid replacement mutations) the sulfur amino acid deficiency inherent to bean seed storage proteins. The development of more nutritious soybean and common bean seeds will be of benefit to programs involving human and animal nutrition.  相似文献   
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The transfer of genetic material into soybean tissue was accomplished by using an avirulent strain of Agrobacterium tumefaciens which contained the binary vector pGA482. The method used for transformation requires no tissue culture steps as it involves the inoculation of the plumule, cotyledonary node, and adjacent cotyledon tissues of germinating seeds. The identification of neomycin phosphotransferase (NPT) II enzyme activity in the tissues of 16 (R0) soybean plants indicated that the plant expressible Nos-NPT II gene, contained within the T-DNA region from pGA482, had been transferred at least into somatic tissues. Putative transformed R0 soybean plants were advanced to produce R1 plants which were also assayed for the presence of the transferred Nos-NPT II gene. The combined results of these assays indicated that about 0.7% of the surviving inoculated seeds yielded transformed tissues in the R0 plant, and that about 1/10 of these plants yielded transformed R1 plants. The presence of the Nos-NPT II gene in DNAs isolated from both R0 and R1 plant was demonstrated by using genomic blot hybridization and polymerase chain reaction methods. Integration of this gene into the soybean genome was demonstrated for three R1 soybean plants.  相似文献   
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