Efficient discovery of immune response targets by cyclical refinement of QSAR models of peptide binding

Peptides that induce and recall T-cell responses are called T-cell epitopes. T-cell epitopes may be useful in a subunit vaccine against malaria. Computer models that simulate peptide binding to MHC are useful for selecting candidate T-cell epitopes since they minimize the number of experiments required for their identification. We applied a combination of computational and immunological strategies to select candidate T-cell epitopes. A total of 86 experimental binding assays were performed in three rounds of identification of HLA-All binding peptides from the six preerythrocytic malaria antigens. Thirty-six peptides were experimentally confirmed as binders. We show that the cyclical refinement of the ANN models results in a significant improvement of the efficiency of identifying potential T-cell epitopes. (C) 2001 by Elsevier Science Inc.

Expression of RANTES and CCR1 in oral lichen planus and association with mast cell migration

Background: T lymphocytes and mast cells infiltrate the lamina propria in oral lichen planus (OLP). Chemokines and their receptors are involved in T cell and mast cell migration and accumulation during the inflammatory process. Methods: In the present study, we investigated the role of RANTES and its receptors in OLP using immunohistochemistry, RT-PCR and an in vitro chemotaxis assay. Results: RANTES and CCR1 were expressed on T cells and mast cells in OLP, while OLP lesional T cell supernatants stimulated CCR1 mRNA expression in a human leukemia mast cell line (HMC-1). TNF-alpha stimulated CCR1, CCR4 and CCR5 mRNA expression in the same cell line. OLP lesional T cell supernatants stimulated HMC-1 migration, which was partly inhibited by anti-RANTES antibody. Conclusions: The present study shows, for the first time, the distribution of RANTES and CCR1 in OLR It is hypothesized that RANTES and CCR1 may play important roles in mast cell trafficking and related events in OLP.

CD40 ligation conditions dendritic cell antigen-presenting function through sustained activation of NF-kappa B

An understanding of the biochemical control of dendritic cell (DC) differentiation/activation is essential for improving T cell immunity by various immunotherapeutic approaches, including DC immunization. Ligation of CD40 enhances DC function, including conditioning for CTL priming. NF-kappaB, and particularly RelB, is an essential control pathway for myeloid DC differentiation. Furthermore, RelB regulates B cell Ag-presenting function. We hypothesized that CD40 ligand (CD40L) and TNF-alpha, which differ in their capacity to condition DC, would also differ in their capacity to activate NF-kappaB. DC differentiated for 2 days from monocytes in the presence of GM-CSF and IL-4 were used as a model, as NF-kappaB activity was constitutively low. The capacity of DC to activate T cells following CD40L treatment was enhanced compared with TNF-alpha treatment, and this was NF-kappaB dependent. Whereas RelB/p50 translocation induced by TNF-alpha was attenuated after 6 h, RelB/p50 nuclear translocation induced by CD40L was sustained for at least 24 h. The mechanism of this difference related to enhanced degradation of IkappaBalpha following CD40L stimulation. However, NF-kappaB activation induced by TNF-alpha could be sustained by blocking autocrine IL-10. These data indicate that NF-kappaB activation is essential for T cell activation by DC, and that this function is enhanced if DC NF-kappaB activation is prolonged. Because IL-10 moderates DC NF-kappaB activation by TNF-alpha, sustained NF-kappaB activation can be achieved by blocking IL-10 in the presence of stimuli that induce TNF-alpha.

Identification of cellular changes associated with increased production of human growth hormone in a recombinant Chinese hamster ovary cell line

A proteomics approach was used to identify the proteins potentially implicated in the cellular response concomitant with elevated production levels of human growth hormone in a recombinant Chinese hamster ovary (CHO) cell line following exposure to 0.5 mM butyrate and 80 muM zinc sulphate in the production media. This involved incorporation of two-dimensional (2-D) gel electrophoresis and protein identification by a combination of N-terminal sequencing, matrix-assisted laser desorption/ionisation-time of flight mass spectrometry, amino acid analysis and cross species database matching. From these identifications a CHO 2-D reference,map and annotated database have been established. Metabolic labelling and subsequent autoradiography showed the induction of a number of cellular proteins in response to the media additives butyrate and zinc sulphate. These were identified as GRP75, enolase and thioredoxin. The chaperone proteins GRP78, HSP90, GRP94 and HSP70 were not up-regulated under these conditions.

Inter-subband redundancy prediction using neural network for video coding

High performance video codec is mandatory for multimedia applications such as video-on-demand and video conferencing. Recent research has proposed numerous video coding techniques to meet the requirement in bandwidth, delay, loss and Quality-of-Service (QoS). In this paper, we present our investigations on inter-subband self-similarity within the wavelet-decomposed video frames using neural networks, and study the performance of applying the spatial network model to all video frames over time. The goal of our proposed method is to restore the highest perceptual quality for video transmitted over a highly congested network. Our contributions in this paper are: (1) A new coding model with neural network based, inter-subband redundancy (ISR) prediction for video coding using wavelet (2) The performance of 1D and 2D ISR prediction, including multiple levels of wavelet decompositions. Our result shows a short-term quality enhancement may be obtained using both 1D and 2D ISR prediction.

Blockade of vascular smooth muscle cell proliferation and intimal thickening after balloon injury by the sulfated oligosaccharide PI-88: Phosphomannopentaose sulfate directly binds FGF-2, blocks cellular signaling, and inhibits proliferation

Percutaneous transluminal coronary angioplasty is a frequently used interventional technique to reopen arteries that have narrowed because of atherosclerosis. Restenosis, or renarrowing of the artery shortly after angioplasty, is a major limitation to the success of the procedure and is due mainly to smooth muscle cell accumulation in the artery wall at the site of balloon injury. In the present study, we demonstrate that the antiangiogenic sulfated oligosaccharide, PI-88, inhibits primary vascular smooth muscle cell proliferation and reduces intimal thickening 14 days after balloon angioplasty of rat and rabbit arteries. PI-88 reduced heparan sulfate content in the injured artery wall and prevented change in smooth muscle phenotype. However, the mechanism of PI-88 inhibition was not merely confined to the antiheparanase activity of this compound. PI-88 blocked extracellular signal-regulated kinase-1/2 (ERK1/2) activity within minutes of smooth muscle cell injury. It facilitated FGF-2 release from uninjured smooth muscle cells in vitro, and super-released FGF-2 after injury while inhibiting ERK1/2 activation. PI-88 inhibited the decrease in levels of FGF-2 protein in the rat artery wall within 8 minutes of injury. PI-88 also blocked injury-inducible ERK phosphorylation, without altering the clotting time in these animals. Optical biosensor studies revealed that PI-88 potently inhibited (K-i 10.3 nmol/L) the interaction of FGF-2 with heparan sulfate. These findings show for the first time the capacity of this sulfated oligosaccharide to directly bind FGF-2, block cellular signaling and proliferation in vitro, and inhibit injury-induced smooth muscle cell hyperplasia in two animal models. As such, this study demonstrates a new role for PI-88 as an inhibitor of intimal thickening after balloon angioplasty. The full text of this article is available online at http://www.circresaha.org.

Prediction of carbon monoxide in fires by conditional moment closure

Carbon monoxide is the chief killer in fires. Dangerous levels of CO can occur when reacting combustion gases are quenched by heat transfer, or by mixing of the fire plume in a cooled under- or overventilated upper layer. In this paper, carbon monoxide predictions for enclosure fires are modeled by the conditional moment closure (CMC) method and are compared with laboratory data. The modeled fire situation is a buoyant, turbulent, diffusion flame burning under a hood. The fire plume entrains fresh air, and the postflame gases are cooled considerably under the hood by conduction and radiation, emulating conditions which occur in enclosure fires and lead to the freezing of CO burnout. Predictions of CO in the cooled layer are presented in the context of a complete computational fluid dynamics solution of velocity, temperature, and major species concentrations. A range of underhood equivalence ratios, from rich to lean, are investigated. The CMC method predicts CO in very good agreement with data. In particular, CMC is able to correctly predict CO concentrations in lean cooled gases, showing its capability in conditions where reaction rates change considerably.

Constitutively Active Mutant D816VKit Induces Megakayocyte and Mast Cell Differentiation of Early Haemopoietic Cells from Murine Foetal Liver

Mutations of Kit at position D816 have been implicated in mastocytosis, acute myeloid leukaemia and germ cell tumours. Expression of this mutant Kit in cell lines results in factor-independent growth, differentiation and increased survival in vitro and tumourigenicity in vivo. Mutant D816VKit and wild-type Kit were expressed in murine primary haemopoietic cells and grown in stem cell factor (SCF) or the absence of factors. Expression of D816VKit did not lead to transformation as assessed by a colony assay, but resulted in enhanced differentiation of cells when compared to control cells. D816VKit induced an increase in the number of cells differentiating along the megakaryocyte lineage in the absence of factors. SCF had an added effect with an increase in differentiation of mast cells. Expression of wild-type Kit in the presence of SCF also failed to cause transformation and induced differentiation of mast cells and megakaryocytes. We conclude that constitutive expression of D816VKit in primary haemopoietic cells is not a sufficient transforming stimulus but leads to the survival and maturation of cells whose phenotype is influenced by the presence of SCF. (C) 2003 Elsevier Science Ltd. All rights reserved.

Is cell surface calreticulin involved in phagocytosis by insect hemocytes?

The innate immune system of insects consists of humoral and cellular components involved in the recognition of and responses to intruding foreign micro- or macroorganisms. Several molecules have been identified so far that recognize molecular patterns present on microorganisms, such as lipopolysaccharides, peptidoglycans and lipoteichonic acid. These molecules, acting as opsonins, trigger immune responses such as phagocytosis, nodule formation, melanization and encapsulation. Here, we investigated the role of calreticulin (CRT) present on the surface of Pieris rapae hemocytes in phagocytosis. Comparative phagocytosis assays using yeast cells showed that hemocytes from different insects exhibit significant variation in their phagocytosing potential and relative CRT involvement. (C) 2003 Elsevier Science Ltd. All rights reserved.