Effects Of Different Fragments Research Articles

Research on Numerical Simulation of Fragments towards Major Fighting Tank’s File System

we analyze the damage effect of different fragments of tank weapon system. The fragment penetrating 125mm smoothbore tube as an example, we established the simulation modeling and setting the initial conditions for the calculation of the. Numerical simulation of damage of fragment penetrating the gun tube by using ANSYS software, we analyze the damage assessment parameters. By using multiple regression method to analyze the results, we conclude that damage rule fragment penetration of gun tube.

Cancerogenic effect of different fragments of the hepatitis C virus core protein

The hepatitis C virus core protein plays an extremely important role in the hepatocarcinogenesis of hepatitis C virus. Little, however, is known about the oncogenic potency of fragments. Thus, the purpose of the present study is to investigate the cancerogenic effects of the different core protein fragments. Two series of recombinant plasmids containing hepatitis C virus core gene fragments encoding the different-length core protein were constructed using plasmid enhanced green fluorescent protein (pEGFP)-C1 and pcDNA3.1(+), respectively. Human hepatocyte L02 cells transiently transfected with pEGFP-C1-based plasmids were subjected to confocal laser scanning microscopy analysis to determine the localization of the different core protein fragments. The stably transfected L02 cells with the pcDNA3.1(+)-based core protein plasmids were used to investigate the ultrastructural effects of the core protein and the tumorigenicity of L02 cells expressing core protein fragments in athymic nude mice. The full-length core protein and Core130-191 were completely localized in the cytoplasm, while Core1-59 existed exclusively in the nucleus. On the other hand, Core50-140 and Core1-140 were observed in both the nucleus and the cytoplasm. Ultrastructural changes of L02 cells expressing the full-length core protein were comprehensive and included, for example, irregular nuclear, increased nuclear/cytoplasmic ratio and mitochondria swelling. The slight changes were observed in the cells expressing Core50-140 and Core130-191, whereas the ultrastructure of the cells expressing Core1-59 remained normal. All the L02 cells stably expressing different fragments of the core protein, with the exception of the C-terminal truncated fragment Core1-59, could induce the occurrence of tumor in the nude mice. The N-terminal fragment of the core protein, Core1-59, was not oncogenic, while the intermediate and posterior segments of the hepatitis C virus core protein had the cancerogenic potency. In view of the existence of many important immunogenic epitopes in it, the core protein anterior segment might be a safer candidate for the development of hepatitis C virus vaccine.

Context-dependent Dysregulation of Transcription by Mutant Huntingtin

Huntington disease (HD) is an adult-onset neurodegenerative disease caused by expansion of a polyglutamine (poly(Q) tract in the N-terminal region of huntingtin (htt). Although the precise mechanisms leading to neurodegeneration in HD have not been fully elucidated, transcriptional dysregulation has been implicated in disease pathogenesis. In HD, multiple N-terminal mutant htt fragments smaller than the first 500 amino acids have been found to accumulate in the nucleus and adversely affect gene transcription. It is unknown whether different htt fragments in the nucleus can differentially bind transcription factors and affect transcription. Here, we report that shorter N-terminal htt fragments, which are more prone to misfolding and aggregation, are more competent to bind Sp1 and inhibit its activity. These effects can be reversed by Hsp40, a molecular chaperone that reduces the misfolding of mutant htt. Our results provide insight into the beneficial effects of molecular chaperones and suggest that context dependent transcriptional dysregulation may contribute to differential toxicity of various N-terminal htt fragments.

Negative Control of the Poly(A)-binding Protein mRNA Translation Is Mediated by the Adenine-rich Region of Its 5′-Untranslated Region

Translation of the mRNA for the poly(A)-binding protein (PABP) may be autoregulated by the binding of PABP to the A-rich segment of its 5'-untranslated region (UTR). To test this hypothesis, we examined the effect of different fragments of the 5'-UTR from human PABP cDNA on the translation of the beta-galactosidase (beta-Gal) reporter gene. Presence of the A-rich sequence from the 5'-UTR of PABP mRNA inhibited expression of the chimeric beta-Gal gene in transfected HeLa cells. The differences in expression of beta-Gal polypeptide was due to the translational repression of beta-Gal mRNA containing the A-rich 5'-UTR of PABP mRNA. The A-rich region of the 5'-UTR located within nucleotides 58-146 of PABP mRNA was sufficient to mediate translational control of this mRNA expression. We also examined the effect of overexpression of PABP mRNA in HeLa cells. The ectopic PABP mRNA without the A-rich 5'-UTR region was translated efficiently, whereas the translation of the endogenous PABP mRNA was substantially inhibited in the transfected cells. In contrast, the ectopic PABP mRNA containing the A-rich 5'-UTR region did not show similar effect on the translation of the endogenous PABP mRNA in these cells. These results suggest that feedback control of mRNA translation is involved in regulating PABP expression in HeLa cells.

Effects of three fragments of parathyroid hormone on calcium channel currents in neonatal rat ventricular cells

The effects of different fragments of bovine parathyroid hormone, bPTH-(1–34), bPTH-(1–84) and bPTH-(3–34), on two types of calcium channel currents in neonatal rat ventricular cells were compared in the present study. bPTH-(1–34) increased the amplitude of L channel currents, but not of the T channel currents. This effect of bPTH-(1–34) was sustained after a complete washout of the peptide from the bath. The intact PTH molecule, bPTH-(1–84), also increased L channel currents but not affecting T channel currents. While bPTH-(3–34) did not affect the amplitudes of either L or T channel currents by itself, pretreatment of cells with bPTH-(3–34) abolished the effects of both bPTH-(1–34) and bPTH-(1–84) on L channel currents. Moreover, the kinetics of L channel currents in the presence of bPTH-(1–34) or bPTH-(3–34) were different. bPTH-(1–34) increased the time constant of activation, but not of inactivation, of L channel currents from 1.8 to 2.5 ms ( P<0.05). In contrast, bPTH-(3–34) decreased the time constant of inactivation, but not of activation, of L channel currents from 159 to 117 ms ( P<0.05). These results indicate that different fragments of PTH exert different effects on the amplitudes or kinetics of cardiac calcium channel currents.

Cholecystokinin stimulates dopamine synthesis in synaptosomes by a cyclic AMP-dependent mechanism.

The effects of different fragments of cholecystokinin (CCK) on dopamine synthesis were studied in synaptosomal preparations from the striatum, substantia nigra, and frontal cortex. In striatal synaptosomes, dopamine synthesis rate measured by dopamine accumulation was 12.5% lower than that measured by 3,4-dihydroxyphenylalanine (DOPA) accumulation; however, K+-accelerated synthesis was the same for both methods. Synthesis rate was independent of exogenous tyrosine levels. In the three regions studied, the combined stimulatory effects of 8-Br-cyclic AMP and high K+ were additive. CCK-5, CCK-3, CCK-27-33, and CCK-8 (sulphated) enhanced synthesis, CCK-5 being the most potent fragment. The nonsulphated octapeptide had no effect. In all three regions, CCK-5 and high K+ had an additive effect on dopamine synthesis; CCK-5 and 8-Br-cyclic AMP together produced the same enhancement of synthesis as CCK-5 alone. CCK-5 produced similar dose-dependent increases in dopamine synthesis and cyclic AMP accumulation in striatal synaptosomes, and both effects were blocked by the CCK antagonist proglumide.

Effects of different fragments of the fibronectin molecule on latex bead translocation along neural crest migratory pathways

Previous studies from this laboratory have utilized latex beads as probes of embryonic migratory pathways. After microinjection into embryos at the time of neural crest migration, uncoated latex polystyrene beads were found to translocate to ventral sites and to settle in the vicinity of endogenous neural crest derivatives. However, latex beads coated with fibronectin did not translocate ventrally, but remained associated with cells surrounding the implantation site. Fibronectin is a large glycoprotein with a variety of biological activities and multiple binding domains. Here, the binding activities which might be responsible for immobilization of the fibronectin-coated beads are examined. Latex beads were coated with three types of fragments of the fibronectin molecule representing different functional domains: (i) a 66-kDa fragment containing collagen-binding activity; (ii) a mixture of 45- and 32-kDa fragments containing heparin-binding activity; and (iii) a 120-kDa fragment containing cell-binding activity. The beads coated with fibronectin fragments were injected into the newly formed trunk somites of avian embryos. After injection, beads coated with either the heparin- or the collagen-binding domain translocated ventrally and distributed analogously to uncoated latex beads. In contrast, the majority of beads coated with the fibronectin cell-binding domain did not translocate but remained associated with dermamyotomal cells surrounding the injection site. The cell-binding fragment, however, was not as effective as the intact fibronectin molecule in preventing translocation of the beads. The results suggest that the cell-binding domain is primarily responsible for restriction of fibronectin beads from the ventral neural crest pathway. Because intact fibronectin is more effective at immobilizing beads than is the cell-binding fragment, other binding domains of fibronectin, more efficient coating with intact fibronectin, or crosslinking of intact fibronectin molecules may also play some role in immobilization of the beads at the implantation site.

Relationship between structure and correcting activity of bovine high molecular weight kininogen upon the clotting time of fitzgerald-trait plasma

Bovine high molecular weight kininogen (bHMWK) partially corrects the activated plasma thromboplastin time (aPTT) of Fitzgerald trait plasma which is congenitally deficient in HMWK. The relationship between the structure and activity of HMWK was clarified by studying the effects of different fragments of bHMWK on the aPTT of Fitzgerald-trait plasma. The peptides studied were lys-bradykinin-free HMWK, bradykinin-fragment 1-2-free HMWK, heavy chain, fragment 1-2-light chain, and light chain. All fragments were tested in equimolar concentrations. Bradykinin-fragment 1-2-free HMWK, heavy chain, and light chain have little or no correcting activity upon Fitzgerald-trait plasma aPTr. Fragment 1-2 light chain has the same correcting activity as intact bHMWK, while that of lys-bradykinin-free HMWK appears to be higher. Both fragment 1-2 and fragment 2 inhibit the clotting time of normal human plasma. When compared on a molar basis, fragment 2 is a more active inhibitor than fragment 1-2. When the effects of bovine plasma kallikrein upon bHMWK and hHMWK were studied, it was found that it released kinins from both kininogens. However, while the correcting activity of bHMWK was completely destroyed after 60 min of incubation, that of hHMWK was fully retained. These data suggest that: (a) the active part of bHMWK is comprised of the fragment 1-2 light chain portion; (b) fragment 1-2 or fragment 2 is the binding site to negatively charged surfaces, while the light chain interacts with other components of the surface-mediated reactions; and (c) bovine plasma kallikrein releases kinins, but probably does not cause the release of fragment 1-2 from human HMWK.