108 resultados para PPV derivative


Relevância:

10.00% 10.00%

Publicador:

Resumo:

Pizgrischite, (Cu,Fe)Cu14PbBi17S35, is a new mineral species named after the type locality, Piz Grisch Mountain, Val Ferrera, Graubunden, Switzerland. This sulfosalt occurs as thin, striated, metallic lead-grey blades measuring up to I cm in length, embedded in quartz and associated with tetrahedrite, chalcopyrite, pyrite, sphalerite, emplectite and derivatives of the aikinite-bismuthinite series. In plane-polarized light, the new species is brownish grey with no perceptible pleochroism; under crossed nicols in oil immersion, it presents a weak anisotropy with dark brown tints. Minimum and maximum reflectance values (in %) in air are: 40.7-42.15 (470 nm), 41.2-43.1 (546 nm), 41.2-43.35 (589 nm) and 40.7-43.3 (650 nm). Cleavage is perfect along 001 I and well developed on {010}. Abundant polysynthetic twinning is observed on (010). The mean micro-indentation hardness is 190 kg/mm(2) (Mohs hardness 3.3), and the calculated density is 6.58 g/cm(3). Electron-microprobe analyses yield (wt%; mean result of seven analyses): Cu 16.48, Pb 2.10, Fe 0.77, Bi 60.70, Sb 0.35, S 19.16, Se 0.04, total 99.60. The resulting empirical chemical formula is (Cu15.24Fe0.80Pb0.60)(Sigma 16.64)(Bi17.07Sb0.17)(Sigma 17.24)(S35.09Se0.03)(Sigma 35.12), in accordance with the formula derived from the single-crystal refinement of the structure, (Cu,Fe)Cu14PbBi17S35. Pizgrischite is monoclinic, space group C2/m, with the following unit-cell parameters: a 35.054(2), b3.91123(I), c43.192(2) angstrom, beta 96.713(4)degrees, V5881.24 angstrom(3), Z=4. The strongest seven X-ray powder-diffraction lines [d in angstrom (I)(hkl)] are: 5.364(40)((6) over bar 04), 4.080(50)((8) over bar 05), 3.120(40)(118), 3.104(68)((3) over bar 18), 2.759(53) ((9) over bar 11),2.752(44)(910) and 1.956(100)(020). The crystal structure is an expanded monoclinic derivative of kupcikite. Pizgrischite belongs to the cuprobismutite series of bismuth sulfosalts but, sensu stricto, it is not a homologue of cuprobismutite. At the type locality. pizarischite is the result of the Alpine metamorphism under greenschist-facies conditions of pre-Tertiary hydrothermal Cu-Bi mineralization.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

To directly assess the binding of exogenous peptides to cell surface-associated MHC class I molecules at the single cell level, we examined the possibility of combining the use of biotinylated peptide derivatives with an immunofluorescence detection system based on flow cytometry. Various biotinylated derivatives of the adenovirus 5 early region 1A peptide 234-243, an antigenic peptide recognized by CTL in the context of H-2Db, were first screened in functional assays for their ability to bind efficiently to Db molecules on living cells. Suitable peptide derivatives were then tested for their ability to generate positive fluorescence signals upon addition of phycoerythrin-labeled streptavidin to peptide derivative-bearing cells. Strong fluorescent staining of Db-expressing cells was achieved after incubation with a peptide derivative containing a biotin group at the C-terminus. Competition experiments using the unmodified parental peptide as well as unrelated peptides known to bind to Kd, Kb, or Db, respectively, established that binding of the biotinylated peptide to living cells was Db-specific. By using Con A blasts derived from different H-2 congenic mouse strains, it could be shown that the biotinylated peptide bound only to Db among > 20 class I alleles tested. Moreover, binding of the biotinylated peptide to cells expressing the Dbm13 and Dbm14 mutant molecules was drastically reduced compared to Db. Binding of the biotinylated peptide to freshly isolated Db+ cells was readily detectable, allowing direct assessment of the relative amount of peptide bound to distinct lymphocyte subpopulations by three-color flow cytometry. While minor differences between peripheral T and B cells could be documented, thymocytes were found to differ widely in their peptide binding activity. In all cases, these differences correlated positively with the differential expression of Db at the cell surface. Finally, kinetic studies at different temperatures strongly suggested that the biotinylated peptide first associated with Db molecules available constitutively at the cell surface and then with newly arrived Db molecules.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

To investigate the molecular basis that makes heterodimeric CD8alphabeta a more efficient coreceptor than homodimeric CD8alphaalpha, we used various CD8 transfectants of T1.4 T cell hybridomas, which are specific for H-2Kd, and a photoreactive derivative of the Plasmodium berghei circumsporozoite peptide PbCS 252-260 (SYIPSAEKI). We demonstrate that CD8 is palmitoylated at the cytoplasmic tail of CD8beta and that this allows partitioning of CD8alphabeta, but not of CD8alphaalpha, in lipid rafts. Localization of CD8 in rafts is crucial for its coreceptor function. First, association of CD8 with the src kinase p56lck takes place nearly exclusively in rafts, mainly due to increased concentration of both components in this compartment. Deletion of the cytoplasmic domain of CD8beta abrogated localization of CD8 in rafts and association with p56lck. Second, CD8-mediated cross-linking of p56lck by multimeric Kd-peptide complexes or by anti-CD8 Ab results in p56lck activation in rafts, from which the abundant phosphatase CD45 is excluded. Third, CD8-associated activated p56lck phosphorylates CD3zeta in rafts and hence induces TCR signaling and T cell activation. This study shows that palmitoylation of CD8beta is required for efficient CD8 coreceptor function, mainly because it dramatically increases CD8 association with p56lck and CD8-mediated activation of p56lck in lipid rafts.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Bacteria released in large numbers for biocontrol or bioremediation purposes might exchange genes with other microorganisms. Two model systems were designed to investigate the likelihood of such an exchange and some factors which govern the conjugative exchange of chromosomal genes between root-colonizing pseudomonads in the rhizosphere of wheat. The first model consisted of the biocontrol strain CHA0 of Pseudomonas fluorescens and transposon-facilitated recombination (Tfr). A conjugative IncP plasmid loaded with transposon Tn5, in a CHA0 derivative carrying a chromosomal Tn5 insertion, promoted chromosome transfer to auxotrophic CHA0 recipients in vitro. A chromosomal marker (pro) was transferred at a frequency of about 10(sup-6) per donor on wheat roots under gnotobiotic conditions, provided that the Tfr donor and recipient populations each contained 10(sup6) to 10(sup7) CFU per g of root. In contrast, no conjugative gene transfer was detected in soil, illustrating that the root surface stimulates conjugation. The second model system was based on the genetically well-characterized strain PAO of Pseudomonas aeruginosa and the chromosome mobilizing IncP plasmid R68.45. Although originally isolated from a human wound, strain PAO1 was found to be an excellent root colonizer, even under natural, nonsterile conditions. Matings between an auxotrophic R68.45 donor and auxotrophic recipients produced prototrophic chromosomal recombinants at 10(sup-4) to 10(sup-5) per donor on wheat roots in artificial soil under gnotobiotic conditions and at about 10(sup-6) per donor on wheat roots in natural, nonsterile soil microcosms after 2 weeks of incubation. The frequencies of chromosomal recombinants were as high as or higher than the frequencies of R68.45 transconjugants, reflecting mainly the selective growth advantage of the prototrophic recombinants over the auxotrophic parental strains in the rhizosphere. Although under field conditions the formation of chromosomal recombinants is expected to be reduced by several factors, we conclude that chromosomal genes, whether present naturally or introduced by genetic modification, may be transmissible between rhizosphere bacteria.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

FtsK acts at the bacterial division septum to couple chromosome segregation with cell division. We demonstrate that a truncated FtsK derivative, FtsK(50C), uses ATP hydrolysis to translocate along duplex DNA as a multimer in vitro, consistent with FtsK having an in vivo role in pumping DNA through the closing division septum. FtsK(50C) also promotes a complete Xer recombination reaction between dif sites by switching the state of activity of the XerCD recombinases so that XerD makes the first pair of strand exchanges to form Holliday junctions that are then resolved by XerC. The reaction between directly repeated dif sites in circular DNA leads to the formation of uncatenated circles and is equivalent to the formation of chromosome monomers from dimers.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

BACKGROUND: The purpose of this prospective study was to perform a head-to-head comparison of the two methods most frequently used for evaluation of carotid plaque characteristics: Multi-detector Computed Tomography Angiography (MDCTA) and black-blood 3 T-cardiovascular magnetic resonance (bb-CMR) with respect to their ability to identify symptomatic carotid plaques. METHODS: 22 stroke unit patients with unilateral symptomatic carotid disease and >50% stenosis by duplex ultrasound underwent MDCTA and bb-CMR (TOF, pre- and post-contrast fsT1w-, and fsT2w- sequences) within 15 days of symptom onset. Both symptomatic and contralateral asymptomatic sides were evaluated. By bb-CMR, plaque morphology, composition and prevalence of complicated AHA type VI lesions (AHA-LT6) were evaluated. By MDCTA, plaque type (non-calcified, mixed, calcified), plaque density in HU and presence of ulceration and/or thrombus were evaluated. Sensitivity (SE), specificity (SP), positive and negative predictive value (PPV, NPV) were calculated using a 2-by-2-table. RESULTS: To distinguish between symptomatic and asymptomatic plaques AHA-LT6 was the best CMR variable and presence / absence of plaque ulceration was the best CT variable, resulting in a SE, SP, PPV and NPV of 80%, 80%, 80% and 80% for AHA-LT6 as assessed by bb-CMR and 40%, 95%, 89% and 61% for plaque ulceration as assessed by MDCTA. The combined SE, SP, PPV and NPV of bb-CMR and MDCTA was 85%, 75%, 77% and 83%, respectively. CONCLUSIONS: Bb-CMR is superior to MDCTA at identifying symptomatic carotid plaques, while MDCTA offers high specificity at the cost of low sensitivity. Results were only slightly improved over bb-CMR alone when combining both techniques.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Using a direct binding assay based on photoaffinity labeling, we have studied the interaction of an antigenic peptide with MHC class I molecules and the TCR on living cells. Two photoreactive derivatives of the H-2Kd (Kd) restricted Plasmodium berghei circumsporozoite (PbCS) peptide 253-260 (YIPSAEKI) were used. The first derivative contained an N-terminal photoreactive iodo, 4-azido salicyloyl (IASA) group and biotin on the TCR contact residue Lys259 [IASA-YIPSAEK(biotin)I]. As previously described, this derivative selectively bound to and labeled the Kd molecule. The second photoreactive compound, the isomeric biotin-YIPSAEK(IASA)I, also efficiently bound to the Kd molecule, but failed to label this protein. A CTL clone derived from a mouse immunized with this derivative recognized this conjugate but not the parental P. berghei circumsporozoite peptide or the [IASA-YIPSAEK-(biotin)I] derivative in an Kd-restricted manner. Incubation of the cloned CTL cells with biotin-YIPSAEK(IASA)I, but not its isomer, followed by UV irradiation resulted in photoaffinity labeling of the TCR-alpha chain that was dependent on the conjugate binding to the Kd molecule. The TCR labeling was partially inhibited by anti-LFA 1 and anti-ICAM1 mAb, but was increased by addition of beta 2m or soluble KdQ10. The exquisite labeling selectivity of the two photoprobes opens a new, direct approach to the molecular analysis of antigen presentation and recognition by living CTL.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A new metabolite profiling approach combined with an ultrarapid sample preparation procedure was used to study the temporal and spatial dynamics of the wound-induced accumulation of jasmonic acid (JA) and its oxygenated derivatives in Arabidopsis thaliana. In addition to well known jasmonates, including hydroxyjasmonates (HOJAs), jasmonoyl-isoleucine (JA-Ile), and its 12-hydroxy derivative (12-HOJA-Ile), a new wound-induced dicarboxyjasmonate, 12-carboxyjasmonoyl-l-isoleucine (12-HOOCJA-Ile) was discovered. HOJAs and 12-HOOCJA-Ile were enriched in the midveins of wounded leaves, strongly differentiating them from the other jasmonate metabolites studied. The polarity of these oxylipins at physiological pH correlated with their appearance in midveins. When the time points of accumulation of different jasmonates were determined, JA levels were found to increase within 2-5 min of wounding. Remarkably, these changes occurred throughout the plant and were not restricted to wounded leaves. The speed of the stimulus leading to JA accumulation in leaves distal to a wound is at least 3 cm/min. The data give new insights into the spatial and temporal accumulation of jasmonates and have implications in the understanding of long-distance wound signaling in plants.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

To study the role of CD8 beta in T cell function, we derived a CD8 alpha/beta-(CD8-/-) T cell hybridoma of the H-2Kd-restricted N9 cytotoxic T lymphocyte clone specific for a photoreactive derivative of the Plasmodium berghei circumsporozoite peptide PbCS 252-260. This hybridoma was transfected either with CD8 alpha alone or together with CD8 beta. All three hybridomas released interleukin 2 upon incubation with L cells expressing Kd-peptide derivative complexes, though CD8 alpha/beta cells did so more efficiently than CD8 alpha/alpha and especially CD8-/- cells. More strikingly, only CD8 alpha/beta cells were able to recognize a weak agonist peptide derivative variant. This recognition was abolished by Fab' fragments of the anti-Kd alpha 3 monoclonal antibody SF1-1.1.1 or substitution of Kd D-227 with K, both conditions known to impair CD8 coreceptor function. T cell receptor (TCR) photoaffinity labeling indicated that TCR-ligand binding on CD8 alpha/beta cells was approximately 5- and 20-fold more avid than on CD8 alpha/a and CD8-/- cells, respectively. SF1-1.1.1 Fab' or Kd mutation D227K reduced the TCR photoaffinity labeling on CD8 alpha/beta cells to approximately the same low levels observed on CD8-/- cells. These results indicate that CD8 alpha/beta is a more efficient coreceptor than CD8alpha/alpha, because it more avidly strengthens TCR-ligand binding.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Melanoma-associated genes (MAGEs) encode tumor-specific antigens that can be recognized by CD8+ cytotoxic T lymphocytes. To investigate the interaction of the HLA-A1-restricted MAGE-1 peptide 161-169 (EADPT-GHSY) with HLA class I molecules, photoreactive derivatives were prepared by single amino acid substitution with N beta-[iodo-4-azidosalicyloyl]-L-2,3-diaminopropionic acid. These derivatives were tested for their ability to bind to, and to photoaffinity-label, HLA-A1 on C1R.A1 cells. Only the derivatives containing the photoreactive amino acid in position 1 or 7 fulfilled both criteria. Testing the former derivative on 14 lymphoid cell lines expressing over 44 different HLA class I molecules indicated that it efficiently photoaffinity-labeled not only HLA-A1, but possibility also HLA-A29 and HLA-B44. MAGE peptide binding by HLA-A29 and HLA-B44 was confirmed by photoaffinity labeling with photoreactive MAGE-3 peptide derivatives on C1R.A29 and C1R.B44 cells, respectively. The different photoaffinity labeling systems were used to access the ability of the homologous peptides derived from MAGE-1, -2, -3, -4a, -4b, -6, and -12 to bind to HLA-A1, HLA-A29, and HLA-B44. All but the MAGE-2 and MAGE-12 nonapeptides efficiently inhibited photoaffinity labeling of HLA-A1, which is in agreement with the known HLA-A1 peptide-binding motif (acidic residue in P3 and C-terminal tyrosine). In contrast, photoaffinity labeling of HLA-A29 was efficiently inhibited by these as well as by the MAGE-3 and MAGE-6 nonapeptides. Finally, the HLA-B44 photoaffinity labeling, unlike the HLA-A1 and HLA-A29 labeling, was inhibited more efficiently by the corresponding MAGE decapeptides, which is consistent with the reported HLA-B44 peptide-binding motif (glutamic acid in P2, and C-terminal tyrosine or phenylalanine). The overlapping binding of homologous MAGE peptides by HLA-A1, A29, and B44 is based on different binding principles and may have implications for immunotherapy of MAGE-positive tumors.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

To investigate the role of the coreceptor CD8 and lipid rafts in cytotoxic T lymphocyte (CTL) activation, we used soluble mono-and multimeric H-2Kd-peptide complexes and cloned S14 CTL specific for a photoreactive derivative of the Plasmodium berghei circumsporozoite (PbCS) peptide 252-260 [PbCS(ABA)]. We report that activation of CTL in suspension requires multimeric Kd-PbCS(ABA) complexes co-engaging TCR and CD8. Using TCR ligand photo-cross-linking, we find that monomeric Kd-PbCS(ABA) complexes promote association of TCR/CD3 with CD8/p56lck. Dimerization of these adducts results in activation of p56lck in lipid rafts, where phosphatases are excluded. Additional cross-linking further increases p56lck kinase activity, induces translocation of TCR/CD3 and other signaling molecules to lipid rafts and intracellular calcium mobilization. These events are prevented by blocking Src kinases or CD8 binding to TCR-associated Kd molecules, indicating that CTL activation is initiated by cross-linking of CD8-associated p56lck. They are also inhibited by methyl-beta-cyclodextrin, which disrupts rafts and by dipalmitoyl phosphatidylethanolamine, which interferes with TCR signaling. Because efficient association of CD8 and p56lck takes place in rafts, both reagents, though in different ways, impair coupling of p56lck to TCR, thereby inhibiting the initial and essential activation of p56lck induced by cross-linking of engaged TCR.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Purpose: To evaluate the use of high frequency jet ventilation (HFJV) in patients undergoing percutanous thermal ablation procedures.Materials: From may to september 2011 patients with lung, liver or kidney tumors suitable for percutanous thermal ablation were prospectively enrolled to be treated under general anesthesia using HFJV instead of conventional positive pressure ventilation (PPV). Our primary endpoint was feasability of HFJV during percutanous ablation, our secondary endpoints were assessment of breathing related movements by image fusion (CT/US), precision and ease of needle placement by number of CT aquisition/needle reposition and procedure related complications.Results: Twenty-nine patients (21 males, 8 females mean age 66.2 years) with 30 liver tumors, 1 kidney tumors and 6 lung tumors were included. Tumor ablation was performed by radiofrequency (RFA) in 26 cases, microwaves ( MWA) in 2 and cryoablation (CRA) in 1. The ablation procedure could be completed under HFJV in 22 patients. In 2 patients HFVJ had to be stopped in favor of PPV because the tumor was better seen under PPV. HFJV was not performed in 5. Breathing related movements of the target lesion in the cranio-caudal direction as estimated by image fusion were always inferior to 5mm compared to 20mm when patients are under PPV. Needle placement was straightforward under CT as well as US. No patient needed needle repositionning before ablation. We did not observe any HFJV related complications.Conclusions: HFJV significantly reduces breathing movements of target lesion during percutaneous ablation procedures. It does not seem to cause any particular complication. However in some cases such as tumors located at the base of the lungs or in the dome of the liver, the target may be best seen under PPV.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Genomic islands, large potentially mobile regions of bacterial chromosomes, are a major contributor to bacteria evolution. Here, we investigated the fitness cost and phenotypic differences between the bacterium Pseudomonas aeruginosa PAO1 and a derivative carrying one integrated copy of the clc element, a 103-kb genomic island [and integrative and conjugative element (ICE)] originating in Pseudomonas sp. strain B13 and a close relative of genomic islands found in clinical and environmental isolates of P. aeruginosa. By using a combination of whole genome transcriptome profiling, phenotypic arrays, competition experiments, and biofilm formation studies, only few differences became apparent, such as reduced biofilm growth and fourfold stationary phase repression of genes involved in acetoin metabolism in PAO1 containing the clc element. In contrast, PAO1 carrying the clc element acquired the capacity to grow on 3-chlorobenzoate and 2-aminophenol as sole carbon and energy substrates. No fitness loss >1% was detectable in competition experiments between PAO1 and PAO1 carrying the clc element. The genes from the clc element were not silent in PAO1, and excision was observed, although transfer of clc from PAO1 to other recipient bacteria was reduced by two orders of magnitude. Our results indicate that newly acquired mobile DNA not necessarily invoke an important fitness cost on their host. Absence of immediate detriment to the host may have contributed to the wide distribution of genomic islands like clc in bacterial genomes

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Purpose:To report the functional, anatomic outcome and safety profile of 23-gauge pars plana vitrectomy (PPV) combined with peeling and intravitreal injection of triamcinolone acetonide (TA) in eyes with idiopathic epiretinal membranes (ERM). Methods:Retrospective, nonrandomized study of consecutive patients who underwent 23-gauge transconjunctival sutureless PPV with subsequent membrane peeling and intravitreal TA injection for an idiopathic ERM. All patients were operated between February 2007 and February 2008 at the Jules Gonin University Eye Hospital. The minimum follow-up was 6-months. Results:Thirty-nine eyes of 39 patients were included. The mean follow-up was 7 months (SD: 2.2, range: 6-15 months). Twenty-two (56%) eyes were pseudophakic and 17 (44%) were phakic at the time of surgery. Mean preoperative intraocular pressure (IOP) was 14 mmHg (SD: 3.5). At the final follow-up mean IOP was 14.5 (SD: 2.7) that did not differ significantly from the IOP at baseline (P: 0.14- 2-tailed t test). Five patients (13%) needed temporary topical anti-glaucoma treatment.Mean preoperative BCVA was 0.28 decimal equivalent (logMAR 0.54, SD: 0.2, range: 1.0 - 0.2). and improved significantly (P <0.0001, 2-tailed t test) to a mean of 0.6 decimal equivalent (logMAR 0.22, SD: 0.16, range: 0.6 - 0) at the final follow-up. The visual acuity improved by a mean of 3.2 lines (SD 2.1, range 0- 8). Twenty-nine patients (74%) demonstrated a gain of 3 or more lines.Mean central macular thickness (CMT) was 456 µm (SD: 77) at the baseline that reduced significantly (P <0.0001, 2-tailed t test) at the final follow-up to 327µm (SD: 79). Average CMT reduction was 131µm (SD: 77, range: 36- 380 µm). A subgroup analysis of 15 selected cases that had CMT measurement 1 week after surgery demonstrated that 84% of the total final reduction in CMT occurred during the first week. Conclusions:23-gauge sutureless transconjunctival vitrectomy with the concomitant administration of intravitreal TA is a safe and effective technique for the treatment of idiopathic ERM and may speed up anatomical recovery.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Translocations are known to affect the expression of genes at the breakpoints and, in the case of unbalanced translocations, alter the gene copy number. However, a comprehensive understanding of the functional impact of this class of variation is lacking. Here, we have studied the effect of balanced chromosomal rearrangements on gene expression by comparing the transcriptomes of cell lines from controls and individuals with the t(11;22)(q23;q11) translocation. The number of differentially expressed transcripts between translocation-carrying and control cohorts is significantly higher than that observed between control samples alone, suggesting that balanced rearrangements have a greater effect on gene expression than normal variation. Many of the affected genes are located along the length of the derived chromosome 11. We show that this chromosome is concomitantly altered in its spatial organization, occupying a more central position in the nucleus than its nonrearranged counterpart. Derivative 22-mapping chromosome 22 genes, on the other hand, remain in their usual environment. Our results are consistent with recent studies that experimentally altered nuclear organization, and indicated that nuclear position plays a functional role in regulating the expression of some genes in mammalian cells. Our study suggests that chromosomal translocations can result in hitherto unforeseen, large-scale changes in gene expression that are the consequence of alterations in normal chromosome territory positioning. This has consequences for the patterns of gene expression change seen during tumorigenesis-associated genome instability and during the karyotype changes that lead to speciation.