346 research outputs found
Fourier transform ion cyclotron resonance MS reveals the presence of a water molecule in an enzyme transition-state analogue complex
The structures of several powerful inhibitors of hydrolytic enzymes resemble that of the altered substrate in the transition state, except that a hydrogen atom replaces one substituent (typically the leaving group). To test the hypothesis that a water molecule might be present in the gap resulting from this replacement, we examined a transition-state analogue complex formed by Escherichia coli cytidine deaminase by Fourier transform ion cyclotron resonance MS in electrospray mode. Upon nebularization from aqueous solution under conditions (pH 5.6) where the enzyme is active, cytidine deaminase remains dimeric in the vapor phase. In the presence of inhibitor, the enzyme's exact mass can be used to infer the presence at each active site of zinc, 5-fluoro-3,4-dihydrouridine, and a single water molecule
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Conceptual design for a receiving station for the nondestructive assay of PuO/sub 2/ at the fuels and materials examination facility
We propose a conceptual design for a receiving station for input accountability measurements on PuO/sub 2/ received at the Fuels and Materials Examination Facility at the Hanford Engineering Development Laboratory. Nondestructive assay techniques are proposed, including neutron coincidence counting, calorimetry, and isotopic determination by gamma-ray spectroscopy, in a versatile data acquisition system to perform input accountability measurements with precisions better than 1% at throughputs of up to 2 M.T./yr of PuO/sub 2/
Towards high-throughput metabolomics using ultrahigh-field Fourier transform ion cyclotron resonance mass spectrometry
With unmatched mass resolution, mass accuracy, and exceptional detection sensitivity, Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FTICR-MS) has the potential to be a powerful new technique for high-throughput metabolomic analysis. In this study, we examine the properties of an ultrahigh-field 12-Tesla (12T) FTICR-MS for the identification and absolute quantitation of human plasma metabolites, and for the untargeted metabolic fingerprinting of inbred-strain mouse serum by direct infusion (DI). Using internal mass calibration (mass error β€1 ppm), we determined the rational elemental compositions (incorporating unlimited C, H, N and O, and a maximum of two S, three P, two Na, and one K per formula) of approximately 250 out of 570 metabolite features detected in a 3-min infusion analysis of aqueous extract of human plasma, and were able to identify more than 100 metabolites. Using isotopically-labeled internal standards, we were able to obtain excellent calibration curves for the absolute quantitation of choline with sub-pmol sensitivity, using 500 times less sample than previous LC/MS analyses. Under optimized serum dilution conditions, chemical compounds spiked into mouse serum as metabolite mimics showed a linear response over a 600-fold concentration range. DI/FTICR-MS analysis of serum from 26 mice from 2 inbred strains, with and without acute trichloroethylene (TCE) treatment, gave a relative standard deviation (RSD) of 4.5%. Finally, we extended this method to the metabolomic fingerprinting of serum samples from 49 mice from 5 inbred strains involved in an acute alcohol toxicity study, using both positive and negative electrospray ionization (ESI). Using these samples, we demonstrated the utility of this method for high-throughput metabolomics, with more than 400 metabolites profiled in only 24 h. Our experiments demonstrate that DI/FTICR-MS is well-suited for high-throughput metabolomic analysis
Comparative Toxicity of Nanoparticulate CuO and ZnO to Soil Bacterial Communities
The increasing industrial application of metal oxide Engineered Nano-Particles (ENPs) is likely to increase their environmental release to soils. While the potential of metal oxide ENPs as environmental toxicants has been shown, lack of suitable control treatments have compromised the power of many previous assessments. We evaluated the ecotoxicity of ENP (nano) forms of Zn and Cu oxides in two different soils by measuring their ability to inhibit bacterial growth. We could show a direct acute toxicity of nano-CuO acting on soil bacteria while the macroparticulate (bulk) form of CuO was not toxic. In comparison, CuSO4 was more toxic than either oxide form. Unlike Cu, all forms of Zn were toxic to soil bacteria, and the bulk-ZnO was more toxic than the nano-ZnO. The ZnSO4 addition was not consistently more toxic than the oxide forms. Consistently, we found a tight link between the dissolved concentration of metal in solution and the inhibition of bacterial growth. The inconsistent toxicological response between soils could be explained by different resulting concentrations of metals in soil solution. Our findings suggested that the principal mechanism of toxicity was dissolution of metal oxides and sulphates into a metal ion form known to be highly toxic to bacteria, and not a direct effect of nano-sized particles acting on bacteria. We propose that integrated efforts toward directly assessing bioavailable metal concentrations are more valuable than spending resources to reassess ecotoxicology of ENPs separately from general metal toxicity
ΠΡΡ Π΅ΡΠΈΠΏ ΡΠ²ΠΎΠ±ΠΎΠ΄Π° Ρ ΠΊΠΎΠ½ΡΠ΅ΠΊΡΡΡ ΡΡΠ°Π½ΡΡΠ·ΡΠΊΠΎΡ ΠΏΠΎΠ»ΡΡΠΈΡΠ½ΠΎΡ ΡΠ΅ΠΎΡΡΡ ΡΠ° ΡΡΡΠΎΡΡΡ
Π ΠΎΠ·Π³Π»ΡΠ½ΡΡΠΎ ΡΡΡΠ°ΡΠ½Ρ ΠΏΡΠ΄Ρ
ΠΎΠ΄ΠΈ ΡΠΎΠ΄ΠΎ Π°Π½Π°Π»ΡΠ·Ρ ΠΏΠΎΠ»ΡΡΠΈΡΠ½ΠΎΡ ΠΌΠ΅Π½ΡΠ°Π»ΡΠ½ΠΎΡΡΡ. Π£ ΠΌΠ΅ΠΆΠ°Ρ
ΠΏΠΎΠ»ΡΡΠΎΠ»ΠΎΠ³ΡΡΠ½ΠΎΠ³ΠΎ Π°Π½Π°Π»ΡΠ·Ρ ΠΎΠΊΡΠ΅ΡΠ»Π΅Π½ΠΎ ΠΊΠΎΠ»ΠΎ ΠΏΡΠΎΠ±Π»Π΅ΠΌ, ΡΠΊΡ ΠΏΠΎΡΡΠ΅Π±ΡΡΡΡ Π²ΠΈΡΡΡΠ΅Π½Π½Ρ Π· Π²ΠΈΠΊΠΎΡΠΈΡΡΠ°Π½Π½ΡΠΌ ΠΏΡΠ΄Ρ
ΠΎΠ΄ΡΠ² ΠΏΡΠΈΡ
ΠΎΠ»ΠΎΠ³ΡΡ. ΠΡΠΎΠ±Π»Π΅Π½ΠΎ Π²ΠΈΡΠ½ΠΎΠ²ΠΎΠΊ ΠΏΡΠΎ ΡΠ΅, ΡΠΎ Π°ΡΡ
Π΅ΡΠΈΠΏ βΡΠ²ΠΎΠ±ΠΎΠ΄Π°β ΡΡΠ°Π½ΠΎΠ²ΠΈΡΡ Π²Π°ΠΆΠ»ΠΈΠ²ΠΈΠΉ Π΅Π»Π΅ΠΌΠ΅Π½Ρ ΠΏΠΎΠ»ΡΡΠΈΡΠ½ΠΎΡ ΠΌΠ΅Π½ΡΠ°Π»ΡΠ½ΠΎΡΡΡ ΡΡΠ°Π½ΡΡΠ·ΡΠ².Modern approaches of analysis of political mentality are considered. Within the limits of political science analysis outlined circle of problems which need decision with the use of approaches of psychology. A conclusion is done that archetype freedom makes the important element of political mentality of Frenchβs
The utility of pathway selective estrogen receptor ligands that inhibit nuclear factor-ΞΊB transcriptional activity in models of rheumatoid arthritis
Rheumatoid arthritis (RA) is a chronic inflammatory disease that produces synovial proliferation and joint erosions. The pathologic lesions of RA are driven through the production of inflammatory mediators in the synovium mediated, in part, by the transcription factor NF-ΞΊB. We have identified a non-steroidal estrogen receptor ligand, WAY-169916, that selectively inhibits NF-ΞΊB transcriptional activity but is devoid of conventional estrogenic activity. The activity of WAY-169916 was monitored in two models of arthritis, the HLA-B27 transgenic rat and the Lewis rat adjuvant-induced model, after daily oral administration. In both models, a near complete reversal in hindpaw scores was observed as well as marked improvements in the histological scores. In the Lewis rat adjuvant model, WAY-169916 markedly suppresses the adjuvant induction of three serum acute phase proteins: haptoglobin, Ξ±1-acid glycoprotein (Ξ±1-AGP), and C-reactive protein (CRP). Gene expression experiments also demonstrate a global suppression of adjuvant-induced gene expression in the spleen, liver, and popliteal lymph nodes. Finally, WAY-169916 was effective in suppressing tumor necrosis factor-Ξ±-mediated inflammatory gene expression in fibroblast-like synoviocytes isolated from patients with RA. Together, these data suggest the utility of WAY-169916, and other compounds in its class, in treating RA through global suppression of inflammation via selective blockade of NF-ΞΊB transcriptional activity
Estrogen deficiency heterogeneously affects tissue specific stem cells in mice
Postmenopausal disorders are frequently observed in various organs, but their relationship with estrogen deficiency and mechanisms remain unclear. As tissue-specific stem cells have been found to express estrogen receptors, we examined the hypothesis that estrogen deficiency impairs stem cells, which consequently contributes to postmenopausal disorders. Six-week-old C57BL/6 female mice were ovariectomized, following which they received 17Ξ²-estradiol replacement or vehicle (control). Sham-operated mice were used as healthy controls. All mice were killed for evaluation 2 months after treatments. Compared with the healthy control, ovariectomy significantly decreased uterine weight, which was partially recovered by 17Ξ²-estradiol replacement. Ovariectomy significantly increased the numbers of c-kit-positive hematopoietic stem/progenitor cells in bone marrow, but impaired their capacity to grow mixed cell-type colonies in vitro. Estrogen replacement further increased the numbers of c-kit-positive hematopoietic stem/progenitor cells in bone marrow, without significantly affecting colony growth in vitro. The number of CD105-positive mesenchymal stem cells in bone marrow also significantly decreased after ovariectomy, but completely recovered following estrogen replacement. Otherwise, neither ovariectomy nor estrogen replacement changed the number of Pax7-positive satellite cells, which are a skeletal muscle-type stem cell. Estrogen deficiency heterogeneously affected tissue-specific stem cells, suggesting a likely and direct relationship with postmenopausal disorders
MHC Class I Bound to an Immunodominant Theileria parva Epitope Demonstrates Unconventional Presentation to T Cell Receptors
T cell receptor (TCR) recognition of peptide-MHC class I (pMHC) complexes is a crucial event in the adaptive immune response to pathogens. Peptide epitopes often display a strong dominance hierarchy, resulting in focusing of the response on a limited number of the most dominant epitopes. Such T cell responses may be additionally restricted by particular MHC alleles in preference to others. We have studied this poorly understood phenomenon using Theileria parva, a protozoan parasite that causes an often fatal lymphoproliferative disease in cattle. Despite its antigenic complexity, CD8+ T cell responses induced by infection with the parasite show profound immunodominance, as exemplified by the Tp1214β224 epitope presented by the common and functionally important MHC class I allele N*01301. We present a high-resolution crystal structure of this pMHC complex, demonstrating that the peptide is presented in a distinctive raised conformation. Functional studies using CD8+ T cell clones show that this impacts significantly on TCR recognition. The unconventional structure is generated by a hydrophobic ridge within the MHC peptide binding groove, found in a set of cattle MHC alleles. Extremely rare in all other species, this feature is seen in a small group of mouse MHC class I molecules. The data generated in this analysis contribute to our understanding of the structural basis for T cell-dependent immune responses, providing insight into what determines a highly immunogenic p-MHC complex, and hence can be of value in prediction of antigenic epitopes and vaccine design
In Situ-Targeting of Dendritic Cells with Donor-Derived Apoptotic Cells Restrains Indirect Allorecognition and Ameliorates Allograft Vasculopathy
Chronic allograft vasculopathy (CAV) is an atheromatous-like lesion that affects vessels of transplanted organs. It is a component of chronic rejection that conventional immuno-suppression fails to prevent, and is a major cause of graft loss. Indirect allo-recognition through T cells and allo-Abs are critical during CAV pathogenesis. We tested whether the indirect allo-response and its impact on CAV is down-regulated by in situ-delivery of donor Ags to recipient's dendritic cells (DCs) in lymphoid organs in a pro-tolerogenic fashion, through administration of donor splenocytes undergoing early apoptosis. Following systemic injection, donor apoptotic cells were internalized by splenic CD11chi CD8Ξ±+ and CD8β DCs, but not by CD11cint plasmacytoid DCs. Those DCs that phagocytosed apoptotic cells in vivo remained quiescent, resisted ex vivo-maturation, and presented allo-Ag for up to 3 days. Administration of donor apoptotic splenocytes, unlike cells alive, (i) promoted deletion, FoxP3 expression and IL-10 secretion, and decreased IFN-Ξ³-release in indirect pathway CD4 T cells; and (ii) reduced cross-priming of anti-donor CD8 T cells in vivo. Targeting recipient's DCs with donor apoptotic cells reduced significantly CAV in a fully-mismatched aortic allograft model. The effect was donor specific, dependent on the physical characteristics of the apoptotic cells, and was associated to down-regulation of the indirect type-1 T cell allo-response and secretion of allo-Abs, when compared to recipients treated with donor cells alive or necrotic. Down-regulation of indirect allo-recognition through in situ-delivery of donor-Ag to recipient's quiescent DCs constitutes a promising strategy to prevent/ameliorate indirect allorecognition and CAV
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