The invariant chain (Ii) due to its intimate association with major histocompatibility complex (MHC) alpha and beta chains is a determining element in the development of immune responses. Ii plays a ...major role in the assembly, the intracellular transport and peptide selection by class II MHC. A segment of Ii designated as CLIP (class II-associated Ii peptide) binds into the antigen binding site of class II MHC molecules until class II MHC reach intracellular compartments that contain peptides from internalized antigens. This association limits the self endogenous peptides that can bind to class II MHC molecules. The removal of CLIP from class II MHC catalyzes the binding of antigenic peptides and their subsequent cell surface expression. An isoform of Ii, known as chondroitin sulfate-modified Ii (IiCS), that is surface-expressed enhances T cell activation while acting as a coreceptor for CD44. The expression of class II MHC molecules by mucosal epithelial cells has generated interest in the role that these cells may have in mucosal immunity. Since in classical antigen-presenting cells (APC) the biology of class II MHC is regulated by Ii, it is necessary to bring into perspective the known functions of Ii in conventional APC to understand the role that Ii may play in mucosal epithelial cells as potential regulators of local immune responses.
Helicobacter pylori infection is linked to chronic gastritis, peptic ulcer and gastric carcinoma. During
H. pylori infection, class II MHC expression by the gastric epithelium increases, as does the ...number of local CD4
+ T cells, which appear to be important in the associated pathogenesis. These observations suggested that the epithelium might present antigens to T cells. Thus, we sought to determine whether gastric epithelial cells process antigens to establish their function as local antigen presenting cells (APC). We examined a panel of gastric epithelial cell lines for expression of the antigen processing cathepsins B (CB), L (CL), S (CS), and D (CD). The mRNA for these enzymes were detected by RT-PCR and the enzymes in the gastric epithelial cells were identified by various independent methods. We corroborated the expression of CB and CD on gastric epithelial cells from human biopsy samples. The functions of these proteases were confirmed by assessing their ability to digest ovalbumin, a conventional dietary antigen, and proteins from
H. pylori. In summary, multiple lines of evidence suggest gastric epithelial cells process antigens for presentation to CD4
+ T cells. To our knowledge, these are the first studies to document the antigen processing capacity of human gastric epithelial cells.
Deep second and third degree burns treatment requires fibroblasts, keratinocytes and other skin cells in order to grow new dermis and epidermis. Cells can proliferate, secrete growth factors and ...extracellular matrix required to repair the damaged tissue. Radiosterilized human amnion and radiosterilized pig skin have been used as natural origin skin dressings for burned patients. Adipose-derived mesenchymal stem cells can differentiate into fibroblasts and keratinocytes and improve wound-healing progress. These cells can stimulate vascular tissue formation, release growth factors, synthetize new extracellular matrix and immunoregulate other cells. In this study, we developed mesenchymal stem cells-cellularized skin substitutes based from radiosterilized human amnion or pig skin. Third-degree burns were induced in mice animal models to evaluate the effect of cellularized skin substitutes on burn wound healing. Mesenchymal phenotype was immunophenotypically confirmed by flow cytometry and cell viability was close to 100%. Skin recovery was evaluated in burned mice after seven and fourteen days post-coverage with cellularized and non-cellularized sustitutes. Histological techniques and immunofluorescence were used to evaluate re-epithelization and type I collagen deposition. We determined that cellularized-human amnion or cellularized-pig skin in combination with mesenchymal stem cells improve extracellular matrix deposition. Both cellularized constructs increase detection of type I collagen in newly formed mouse skin and can be potentially used as skin coverage for further clinical treatment of burned patients.
The High Luminosity LHC (HL-LHC) phase is designed to increase by an order of magnitude the amount of data to be collected by the LHC experiments. The foreseen gradual increase of the instantaneous ...luminosity of up to more than twice its nominal value of \(10\times10^{34}\ {\rm cm}^{-1}{\rm s}^{-2}\) during Phase I and Phase II of the LHC running, presents special challenges for the experiments. The region with high pseudo rapidity (\(\eta\)) region of the forward muon spectrometer (\(2.4 > |\eta| > 1.9\)) is not equipped with RPC stations. The increase of the expected particles rate up to 2 kHz cm\(^{-1}\) ( including a safety factor 3 ) motivates the installation of RPC chambers to guarantee redundancy with the CSC chambers already present. The current CMS RPC technology cannot sustain the expected background level. A new generation of Glass-RPC (GRPC) using low-resistivity glass was proposed to equip the two most far away of the four high \(\eta\) muon stations of CMS. In their single-gap version they can stand rates of few kHz cm\(^{-1}\). Their time precision of about 1 ns can allow to reduce the noise contribution leading to an improvement of the trigger rate. The proposed design for large size chambers is examined and some preliminary results obtained during beam tests at Gamma Irradiation Facility (GIF++) and Super Proton Synchrotron (SPS) at CERN are shown. They were performed to validate the capability of such detectors to support high irradiation environment with limited consequence on their efficiency.
A Simple Synthesis of γ-Cyclohomocitral Cruz Almanza, Raymundo; Hinojosa Reyes, Agustín
Synthetic communications,
03/1993, Letnik:
23, Številka:
6
Journal Article
Recenzirano
A simple and efficient synthesis for γ-cyclohomocitral (10), a key and versatile intermediate for the synthesis of some furanosesquiterpenes, is described. The formal total synthesis of (±) ...Pallenscensone (2) was accomplished.
North Tijuana, Mexico is home to many individuals at high risk for transmitting and acquiring human immunodeficiency virus (HIV). Recently, policy shifts by local government impacted how these ...individuals were handled by authorities. Here we examined how this affected regional HIV transmission dynamics.
HIV pol sequences and associated demographic information were collected from 8 research studies enrolling persons in Tijuana and were used to infer viral transmission patterns. To evaluate the impact of recent policy changes on HIV transmission dynamics, qualitative interviews were performed on a subset of recently infected individuals.
Between 2004 and 2016, 288 unique HIV pol sequences were obtained from individuals in Tijuana, including 46.4% from men who have sex with men, 42.1% from individuals reporting transactional sex, and 27.8% from persons who inject drugs (some individuals had >1 risk factor). Forty-two percent of sequences linked to at least 1 other sequence, forming 37 transmission clusters. Thirty-two individuals seroconverted during the observation period, including 8 between April and July 2016. Three of these individuals were putatively linked together. Qualitative interviews suggested changes in policing led individuals to shift locations of residence and injection drug use, leading to increased risk taking (eg, sharing needles).
Near real-time molecular epidemiologic analyses identified a cluster of linked transmissions temporally associated with policy shifts. Interviews suggested these shifts may have led to increased risk taking among individuals at high risk for HIV acquisition. With all public policy shifts, downstream impacts need to be carefully considered, as even well-intentioned policies can have major public health consequences.
The use of engineered nanoparticles (NPs) has increased considerably because of their almost universal applications, such as electronics, optical, pharmaceutical, biomedical and energy fields, which ...have been expanding rapidly during the past few decades. Due to the widespread applications of zinc oxide nanoparticles (ZnONPs), the potential exposure of workers, consumers and scientists to these particles has increased. We conducted a ZnONPs synthesis through a low cost, eco-friendly and sustainable method, where Beta vulgaris extract was utilized as a reducing agent. Characterization of ZnONPs was conducted by High-Resolution Transmission Electron Microscopy (HRTEM), Fourier-Transform Infrared Spectroscopy (FTIR) and X-ray diffraction analysis (XRD) to obtain the morphological properties. In this study, we evaluate ZnONPs toxicity in vitro in two mouse fibroblast cell lines C2C12 and L929 myoblast cell lines and human lymphocytes from peripheral blood (HLPB), using Trypan blue dye exclusion method. MTT assay method only in cell lines C2C12 and L929 after 24 h of exposure. The results show the ZnONPs size was between 16 and 24 nm, with hexagonal crystal structure and semi-spherical morphology. The toxic effects of ZnONPs were analyzed in the two cell lines after a 24 and 48 h incubation period. The value of TC50 ZnONPs was calculated after a 24 h exposure, which was found to be between 28 and 37 μg/mL and 20–30 μg/mL at a 48 h exposure. The viability value was reported non toxic at concentrations of 1 × 10−6-1x10−3 μg/mL.
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