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991.
JA Lednicky AS Arrington AR Stewart XM Dai C Wong S Jafar M Murphey-Corb JS Butel 《Canadian Metallurgical Quarterly》1998,72(5):3980-3990
Simian virus 40 (SV40) DNAs in brain tissue and peripheral blood mononuclear cells (PBMCs) of eight simian immunodeficiency virus-infected rhesus monkeys with SV40 brain disease were analyzed. We report the detection, cloning, and identification of five new SV40 strains following a quadruple testing-verification strategy. SV40 genomes with archetypal regulatory regions (containing a duplication within the G/C-rich regulatory region segment and a single 72-bp enhancer element) were recovered from seven animal brains, two tissues of which also contained viral genomes with nonarchetypal regulatory regions (containing a duplication within the G/C-rich regulatory region segment as well as a variable duplication within the enhancer region). In contrast, PBMC DNAs from five of six animals had viral genomes with both regulatory region types. It appeared, based on T-antigen variable-region sequences, that nonarchetypal virus variants arose de novo within each animal. The eighth animal exclusively yielded a new type of SV40 strain (SV40-K661), containing a protoarchetypal regulatory region (lacking a duplication within the G/C-rich segment of the regulatory region and containing one 72-bp element in the enhancer region), from both brain tissue and PBMCs. The presence of SV40 in PBMCs suggests that hematogenous spread of viral infection may occur. An archetypal version of a virus similar to SV40 reference strain 776 (a kidney isolate) was recovered from one brain, substantiating the idea that SV40 is neurotropic as well as kidney-tropic. Indirect evidence suggests that maternal-infant transmission of SV40 may have occurred in one animal. These findings provide new insights for human polyomavirus disease. 相似文献
992.
AR Kolker CJ Hirsch BS Gingold JM Stamatos MK Wallack 《Canadian Metallurgical Quarterly》1997,40(3):339-343
Fibrodysplasia ossificans progressiva (FOP) is a rare genetic disorder characterized by congenital malformation of the great toes and progressive heterotopic ossification in distinct anatomic patterns. Early preosseous lesions in FOP are clinically and histologically indistinguishable from the lesions of aggressive juvenile fibromatosis (AJF). Although the genetic defect in FOP is unknown, bone morphogenetic proteins (BMPs) 2 and 4 are plausible candidates genes. To determine if there is a difference in BMP 2/4 expression in the early fibromatous lesions of the two conditions, we performed immunohistochemical studies with a monoclonal antibody to BMP 2/4 on the earliest detectable fibromatous lesions of FOP and compared them with histologically identical lesions resected from children who had AJF. Fibromatous cells from the early FOP lesions exhibited immunostaining for BMP 2/4, whereas histologically indistinguishable fibromatous cells from AJF lesions showed no evidence of BMP 2/4 immunostaining. It is incumbent on all physicians who treat patients with suspected fibromatosis to examine the toes to rule out FOP and to avoid unnecessary diagnostic biopsies because surgical trauma induces further bone formation in patients who have FOP. However, if diagnostic confusion still exists and a biopsy is performed, immunostaining with BMP 2/4 antibody may resolve the diagnostic dilemma between FOP and AJF before the appearance of heterotopic ossification is observed in the FOP lesions. Our data suggest that the BMP 2/4 subfamily of secreted proteins may be involved in the pathogenesis of the FOP lesions. 相似文献
993.
994.
With the many changes that have occurred at the National League for Nursing (NLN) during the past several years, including the formation of the National League for Nursing Accreditation Commission (NLNAC), preparation for an accreditation site visit can be a stress producing event for nursing students, faculty and the nursing administrator. This article is designed for the nursing administrator and faculty who are relatively inexperienced in the accreditation process and provides practice guidelines on how to prepare for the culmination of the preparation process and the actual site visit to the school by a peer review team. 相似文献
995.
996.
CI2 folds and unfolds as a single cooperative unit by simple two-state kinetics, which enables the properties of the transition state to be measured from both the forward and backward rate constants. We have examined how the free energy of the transition state for the folding of chymotrypsin inhibitor 2 (CI2) changes with pH and temperature. In addition to the standard thermodynamic quantities, we have measured the overall acid-titration properties of the transition state and its heat capacity relative to both the denatured and native states. We were able to determine the latter by a method analogous to a well-established procedure for measuring the change in heat capacity for equilibrium unfolding: the enthalpy of activation of unfolding at different values of acid pH were plotted against the average temperature of each determination. Our results show that the transition state of CI2 has lost most of the electrostatic and van der Waals' interactions that are found in the native state, but it remains compact and this prevents water molecules from entering some parts of the hydrophobic core. The properties of the transition state of CI2 are then compared with the major folding transition state of the larger protein barnase, which folds by a multi-state mechanism, with the accumulation of a partly structured intermediate (Dphys or I). CI2 folds from a largely unstructured denatured state under physiological conditions via a transition state which is compact but relatively uniformly unstructured, with tertiary and secondary structure being formed in parallel. We term this an expanded pathway. Conversely, barnase folds from a largely structured denatured state in which elements of structure are well formed through a transition state that has islands of folded elements of structure. We term this a compact pathway. These two pathways may correspond to the two extreme ends of a continuous spectrum of protein folding mechanisms. Although the properties of the two transition states are very different, the activation barrier for folding (Dphys-->++) is very similar for both proteins. 相似文献
997.
998.
999.
AR Kennedy 《Canadian Metallurgical Quarterly》1996,350(1):81-91
A method is described using counterflow centrifugation elutriation to isolate macrophages from murine liver and spleen. In this study three, size fractionated, macrophage populations were collected. Isolation resulted in a high yield of pure Kupffer cells (total of 10 x 10(6) /g liver) and enrichment of splenic macrophages to 20%. In addition to standard methods such as non-specific esterase staining, the isolated macrophages were also characterized by flow cytometry using specific monoclonal antibodies. In addition, a rapid flow cytometry method was introduced to determine the percentage of macrophages based on autofluorescence. A strong correlation was found between the percentages of macrophages found by non-specific esterase staining and autofluorescence. Functional tests revealed differences between the isolated macrophages in terms of tumor necrosis factor-alpha (TNF-alpha) production, oxygen metabolism and the production of nitric oxide. However, no significant differences in phagocytic activity was observed between the fractions. After two weeks of culture without the addition of antibiotics the cells still exhibited the above mentioned functions. 相似文献
1000.
The organic anions, p-aminohippurate (PAH) and fluorescein, are transported across the basolateral membrane of the renal proximal tubule in exchange for intracellular alpha-ketoglutarate (alpha KG), a mechanism indirectly coupled to sodium via Na+/alpha KG cotransport. To determine whether this mechanism mediates the basolateral transport of other organic anions, transport of the herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D), was examined in rat renal cortical slices and basolateral membrane vesicles. In slices, uptake of 2,4-D increased steadily over time, approaching steady-state tissue/medium ratios of approximately 8 after 60 min. Probenecid, PAH and chlorophenol red inhibited steady-state uptake of 2,4-D. Accumulation of 10 microM 2,4-D was stimulated 2-fold by 60 microM glutarate; other dicarboxylic acids failed to stimulate uptake. In the presence of sodium, the addition of 5 mM LiCl or 2 mM ouabain to the bathing medium abolished glutarate stimulation. Removal of sodium from the bathing medium reversibly inhibited uptake as much as 75%. Furthermore, PAH inhibited 2,4-D uptake by slices in a dose-dependent manner, and increasing the external 2,4-D concentration decreased the inhibitory potency of PAH. In basolateral membrane vesicles, unlabeled 2,4-D inhibited sodium glutarate-coupled uptake of 3H-labeled PAH and 2,4-D in a concentration-dependent manner. Moreover, concentrative uptake of 2,4-D into vesicles could be driven by an outwardly directed gradient of glutarate or alpha KG that was generated by lithium-sensitive Na+/dicarboxylate cotransport or imposed experimentally. An outwardly directed gradient of unlabeled 2,4-D or PAH also stimulated uptake of 2,4-D. Based on these data, basolateral accumulation of 2,4-D by the renal proximal tubule is mediated by 2,4-D/alpha KG exchange, a mechanism energetically coupled to Na+/alpha KG cotransport and shared with PAH. 相似文献