HIV-1 sub-type C chimaeric VLPs boost cellular immune responses in mice

Several approaches have been explored to eradicate HIV; however, a multigene vaccine appears to be the best option, given their proven potential to elicit broad, effective responses in animal models. The Pr55 Gagprotein is an excellent vaccine candidate in its own right, given that it can assemble into large, enveloped, virus-like particles (VLPs) which are highly immunogenic, and can moreover be used as a scaffold for the presentation of other large non-structural HIV antigens. In this study, we evaluated the potential of two novel chimaeric HIV-1 Pr55 Gag-based VLP constructs - C-terminal fusions with reverse transcriptase and a Tat::Nef fusion protein, designated GagRT and GagTN respectively - to enhance a cellular response in mice when used as boost components in two types of heterologous prime-boost vaccine strategies. A vaccine regimen consisting of a DNA prime and chimaeric HIV-1 VLP boosts in mice induced strong, broad cellular immune responses at an optimum dose of 100 ng VLPs. The enhanced cellular responses induced by the DNA prime-VLP boost were two- to three-fold greater than two DNA vaccinations. Moreover, a mixture of GagRT and GagTN VLPs also boosted antigen-specific CD8+ and CD4+ T-cell responses, while VLP vaccinations only induced predominantly robust Gag CD4+ T-cell responses. The results demonstrate the promising potential of these chimaeric VLPs as vaccine candidates against HIV-1. © 2010 Pillay et al; licensee BioMed Central Ltd.

An investigation of the C77G and C772T variations within the human protein tyrosine phosphatase receptor type C gene for association with multiple sclerosis in an Australian population

Multiple sclerosis (MS) is a common cause of neurological disability in young adults. The disease generally manifests in early to middle adulthood and causes various neurological deficits. Autoreactive T lymphocytes and their associated antigens have long been presumed important features of MS pathogenesis. The Protein tyrosine phosphatase receptor type C gene (PTPRC) encodes the T-cell receptor CD45. Variations within PTPRC have been previously associated with diseases of autoimmune origin such as type 1 diabetes mellitus and Graves' disease. We set out to investigate two variants within the PTPRC gene, C77G and C772T in subjects with MS and matched healthy controls to determine whether significant differences exist in these markers in an Australian population. We employed high resolution melt analysis (HRM) and restriction length polymorphism (RFLP) techniques to determine genotypic and allelic frequencies. Our study found no significant difference between frequencies for PTPRC C77G by either genotype (Χ2 = 0.65, P = 0.72) or allele (Χ2 = 0.48, P = 0.49). Similarly, we did not find evidence to suggest an association between PTPRC C772T by genotype (Χ2 = 1.06, P = 0.59) or allele (Χ2 = 0.20, P = 0.66). Linkage disequilibrium (LD) analysis showed strong linkage disequilibrium between the two tested markers (D' = 0.9970, SD = 0.0385). This study reveals no evidence to suggest that these markers are associated with MS in the tested Australian Caucasian population. Although the PTPRC gene has a significant role in regulating CD4+ and CD8+ autoreactive T-cells, interferon-beta responsiveness, and potentially other important processes, our study does not support a role for the two tested variants of this gene in MS susceptibility in the Australian population.

Spatial filtering nearly eliminates the side-lobes in single- and multi-photon 4pi-type-C super-resolution fluorescence microscopy

Super-resolution microscopy has tremendously progressed our understanding of cellular biophysics and biochemistry. Specifically, 4pi fluorescence microscopy technique stands out because of its axial super-resolution capability. All types of 4pi-microscopy techniques work well in conjugation with deconvolution techniques to get rid of artifacts due to side-lobes. In this regard, we propose a technique based on spatial filter in a 4pi-type-C confocal setup to get rid of these artifacts. Using a special spatial filter, we have reduced the depth-of-focus. Interference of two similar depth-of-focus beams in a 4 pi geometry result in substantial reduction of side-lobes. Studies show a reduction of side-lobes by 46% and 76% for single and two photon variant compared to 4pi - type - C confocal system. This is incredible considering the resolving capability of the existing 4pi - type - C confocal microscopy. Moreover, the main lobe is found to be 150 nm for the proposed spatial filtering technique as compared to 690 nm of the state-of-art confocal system. Reconstruction of experimentally obtained 2PE - 4pi data of green fluorescent protein (GFP)-tagged mitocondrial network shows near elimination of artifacts arising out of side-lobes. Proposed technique may find interesting application in fluorescence microscopy, nano-lithography, and cell biology. (C) 2013 AIP Publishing LLC.

Three centered hydrogen bonds of the type C=O...H(N)...X-C in diphenyloxamide derivatives involving halogens and a rotating CF3 group: NMR, QTAIM, NCI and NBO studies

The existence of three centered C=O...H(N)...X-C hydrogen bonds (H-bonds) involving organic fluorine and other halogens in diphenyloxamide derivatives has been explored by NMR spectroscopy and quantum theoretical studies. The three centered H-bond with the participation of a rotating CF3 group and the F...H-N intramolecular hydrogen bonds, a rare observation of its kind in organofluorine compounds, has been detected. It is also unambiguously established by a number of one and two dimensional NMR experiments, such as temperature perturbation, solvent titration, N-15-H-1 HSQC, and F-19-H-1 HOESY, and is also confirmed by theoretical calculations, such as quantum theory of atoms in molecules (QTAIM), natural bond orbital (NBO) and non-covalent interaction (NCI).

Heterojunction solar cells with n-type nanocrystalline silicon emitters on p-type c-Si wafers

Hydrogenated nanocrystalline silicon (nc-Si:H) n-layers have been used to prepare heterojunction solar cells on flat p-type crystalline silicon (c-Si) wafers. The nc-Si:H n-layers were deposited by radio-frequency (RF) plasma enhanced chemical vapor deposition (PECVD), and characterized using Raman spectroscopy, optical transmittance and activation energy of dark-conductivity. The nc-Si:H n-layers obtained comprise fine grained nanocrystallites embedded in amorphous matrix, which have a wider bandgap and a smaller activation energy. Heterojunction solar cells incorporated with the nc-Si n-layer were fabricated using configuration of Ag (100 nm)/1T0 (80 nm)/n-nc-Si:H (15 nm)/buffer a-Si:H/p-c-Si (300 mu m)/Al (200 nm), where a very thin intrinsic a-Si:H buffer layer was used to passivate the p-c-Si surface, followed by a hydrogen plasma treatment prior to the deposition of the thin nanocrystalline layer. The results show that heterojunction solar cells subjected to these surface treatments exhibit a remarkable increase in the efficiency, up to 14.1% on an area of 2.43 cm(2). (c) 2006 Elsevier B.V. All rights reserved.

Heterojunction solar cells with n-type nanocrystalline silicon emitters on p-type c-Si wafers

Hydrogenated nanocrystalline silicon (nc-Si:H) n-layers have been used to prepare heterojunction solar cells on flat p-type crystalline silicon (c-Si) wafers. The nc-Si:H n-layers were deposited by radio-frequency (RF) plasma enhanced chemical vapor deposition (PECVD), and characterized using Raman spectroscopy, optical transmittance and activation energy of dark-conductivity. The nc-Si:H n-layers obtained comprise fine grained nanocrystallites embedded in amorphous matrix, which have a wider bandgap and a smaller activation energy. Heterojunction solar cells incorporated with the nc-Si n-layer were fabricated using configuration of Ag (100 nm)/1T0 (80 nm)/n-nc-Si:H (15 nm)/buffer a-Si:H/p-c-Si (300 mu m)/Al (200 nm), where a very thin intrinsic a-Si:H buffer layer was used to passivate the p-c-Si surface, followed by a hydrogen plasma treatment prior to the deposition of the thin nanocrystalline layer. The results show that heterojunction solar cells subjected to these surface treatments exhibit a remarkable increase in the efficiency, up to 14.1% on an area of 2.43 cm(2). (c) 2006 Elsevier B.V. All rights reserved.

An Efficient Ullmann-Type C-O Bond Formation Catalyzed by an Air-Stable Copper(I)-Bipyridyl Complex

An efficient O-arylation of phenols and aliphatic alcohols with aryl halides was developed that uses an air-stable copper(I) complex as the catalyst. This arylation reaction can be performed in good yield in the absence of Cs2CO3. A variety of functional groups are compatible with these reaction conditions with low catalyst loading levels.

New Cu-Based Catalysts Supported on TiO2 Films for Ullmann SNAr-Type C-O Coupling Reactions

New routes for the preparation of highly active TiO2-supported Cu and CuZn catalysts have been developed for C-O coupling reactions. Slurries of a titania precursor were dip-coated onto glass beads to obtain either structured mesoporous or non-porous titania thin films. The Cu and CuZn nanoparticles, synthesized using a reduction by solvent method, were deposited onto calcined films to obtain a Cu loading of 2 wt%. The catalysts were characterized by inductively coupled plasma (ICP) spectroscopy, temperature-programmed oxidation/reduction (TPO/TPR) techniques, Cu-63 nuclear magnetic resonance (NMR) spectroscopy, X-ray diffraction (XRD), scanning and transmission electron microscopy (S/TEM-EDX) and X-ray photo-electron spectroscopy (XPS). The activity and stability of the catalysts obtained have been studied in the C-O Ullmann coupling of 4-chloropyridine and potassium phenolate. The titania-supported nanoparticles retained catalyst activity for up to 12 h. However, catalyst deactivation was observed for longer operation times due to oxidation of the Cu nanoparticles. The oxidation rate could be significantly reduced over the CuZn/TiO2 catalytic films due to the presence of Zn. The 4-phenoxypyridine yield was 64% on the Cu/nonporous TiO2 at 120 degrees C. The highest product yield of 84% was obtained on the Cu/mesoporous TiO2 at 140 degrees C, corresponding to an initial reaction rate of 104 mmol g(cat)(-1) s(-1). The activation energy on the Cu/mesoporous TiO2 catalyst was found to be (144 +/- 5) kJ mol(-1), which is close to the value obtained for the reaction over unsupported CuZn nanoparticles (123 +/- 3 kJ mol(-1)) and almost twice the value observed over the catalysts deposited onto the non-porous TiO2 support (75 +/- 2 kJ mol(-1)).

Computational learning of the conditional phase-type (C-Ph) distribution: Learning C-Ph distributions

This paper presents a new algorithm for learning the structure of a special type of Bayesian network. The conditional phase-type (C-Ph) distribution is a Bayesian network that models the probabilistic causal relationships between a skewed continuous variable, modelled by the Coxian phase-type distribution, a special type of Markov model, and a set of interacting discrete variables. The algorithm takes a dataset as input and produces the structure, parameters and graphical representations of the fit of the C-Ph distribution as output.The algorithm, which uses a greedy-search technique and has been implemented in MATLAB, is evaluated using a simulated data set consisting of 20,000 cases. The results show that the original C-Ph distribution is recaptured and the fit of the network to the data is discussed.

The Conditional Phase-type distribution: Graphical Models for Continuous Non-Normal Data:The Conditional Phase-type (C-Ph) distribution:

Conditional Gaussian (CG) distributions allow the inclusion of both discrete and continuous variables in a model assuming that the continuous variable is normally distributed. However, the CG distributions have proved to be unsuitable for survival data which tends to be highly skewed. A new method of analysis is required to take into account continuous variables which are not normally distributed. The aim of this paper is to introduce the more appropriate conditional phase-type (C-Ph) distribution for representing a continuous non-normal variable while also incorporating the causal information in the form of a Bayesian network.

N-acétyltransférase lysosomale : organisation, fonctionnement et défauts moléculaires chez les patients atteints du syndrome de Sanfilippo type C

L’acétylation des résidus de glucosamine terminaux par la N-acétyltransférase lysosomale (HGSNAT) est une étape essentielle de la dégradation catabolique de l’héparan sulfate. Des défauts dans cette réaction causent une maladie de surcharge lysosomale autosomale récessive rare : le désordre de Sanfilippo type C (SFC). À ce jour, 54 mutations ont été rapportées chez des patients SFC, incluant 13 mutations des sites d’épissage, 11 insertions et délétions, 8 mutations non-sens, 18 mutations faux-sens et 4 polymorphismes, avec différentes manifestations phénotypiques. Nous avons identifié 10 d’entre elles et effectué une étude exhaustive portant sur l’éventail des mutations SFC, leur distribution dans la population de patients, ainsi que leur impact potentiel sur la structure de la HGSNAT. Les erreurs d’épissage, les mutations non-sens, les insertions et les délétions devraient toutes entraîner un ARN non fonctionnel qui est rapidement dégradé par des mécanismes de contrôle qualité cellulaire. Les 4 polymorphismes identifiés sont des changements d'acides aminés qui ne modifient pas l'activité enzymatique, la glycosylation ou la localisation et n'ont donc pas de signification au niveau clinique. Au niveau des enzymes, les polymorphismes sont des changements d’acides aminés qui n’affectent pas la fonction, mais dans un contexte d’acides nucléiques ils peuvent être considérés comme des mutations faux-sens. Les dix-huit mutations faux-sens qui ont été exprimées ont produit des protéines inactives, en raison d'erreurs dans leur repliement. Ceci expliquerait donc la progression sévère de la maladie chez les personnes porteuses de ces mutations. Les protéines mutantes mal repliées sont anormalement glycosylées et conservées dans le réticulum endoplasmique. La thérapie par amélioration de l’activité enzymatique par des chaperonnes est une option thérapeutique potentielle, spécifiquement conçue pour exploiter l'activité enzymatique résiduelle de mutants mal repliés, afin d’éliminer les substrats stockés. Nous avons démontré que le traitement de plusieurs lignées de fibroblastes de patients SFC avec le chlorhydrate de glucosamine, un inhibiteur spécifique de la HGSNAT, a partiellement restauré l’activité de l'enzyme mutante, fournissant une preuve de l’utilité future de la thérapie par des chaperonnes dans le traitement de la maladie de SFC.

Régulation du cycle cellulaire par le récepteur natriurétique de type C dans les cellules du muscle lisse vasculaire : mécanismes moléculaires

Nous avons précédemment montré que l’activation du récepteur natriurétique de type C (NPR-C) par son agoniste spécifique, le C-ANP4-23, atténue l’augmentation de la prolifération des cellules du muscle lisse vasculaire (CMLV) induite par les peptides vasoactifs (Ang II, ET-1 et l’AVP). Puisque les CMLV provenant de rats spontanément hypertendus (SHR) montrent elles aussi un taux de prolifération plus élevé que leur contrôle, les CMLV de rats Wystar-Kyoto (WKY), nous avons entrepris cette étude dans le but de déterminer si C-ANP4-23 peut également diminuer le taux élevé de prolifération des CMLV de SHR et, le cas échéant déterminer les mécanismes responsables de cette réponse. Nos résultats montrent que le taux de prolifération des CMLV de SHR est significativement plus élevé que celui des CMLV de WKY et que la présence de C-ANP4-23 diminue de manière-dose dépendante le taux de prolifération des CMLV de SHR. En plus, l’expression des protéines de la phase G1 du cycle cellulaire, la cycline D1, la kinase dépendante des cyclines 2 (cdk2) et la forme phosphorylée de la protéine du rétinoblastome (pRb) est augmentée dans les CMLV de SHR comparativement aux CMLV de WKY et est atténué par C-ANP4-23. De plus, nos résultats montrent que les inhibiteurs du complexe cycline D1/cdk4 (NSC 625987) et cdk2 (NU2058) diminue le taux de prolifération élevé des CMLV de SHR. Les CMLV de SHR montrent également un taux de phosphorylation de ERK1/2 et d’AKT et est atténué par C-ANP4-23. De plus, le taux d’expression élevé des protéines cycline D1, cdk2 et pRb des CMLV de SHR est diminué par la toxine pertussis qui inactive la protéine Giα, le PD 98095, un inhibiteur de MEK de la voie des MAPK, du wortmannin, un inhibiteur de la PI3-K et finalement du losartan, un antagoniste du récepteur AT1. Ces résultats suggèrent que l’activation du récepteur NPR-C par C-ANP4-23 diminue le taux de prolifération élevé des CMLV de SHR par une régulation à la baisse des composantes du cycle cellulaire via l’inhibition de la protéine Giα et des voies signalétique MAP kinase/PI3-K.

Type C botulism in swine fed on restaurant waste

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)