Analysis of damage localisation results in GFRP panel for different configurations of air-coupled transducers.

In this paper results of the damage assessment of fiber-reinforced composite panels using guided wave propagation phenomenon are presented. For this purpose, non-contact elastic wave generation based on an air-coupled transducer (ACT) is utilised. Elastic wave sensing was based on a scanning laser Doppler vibrometer (SLDV). The problem of ACT slope angle for the effectiveness of elastic wave modes generation is analysed. It was shown that for an excitation frequency of 40 kHz it is possible to generate A0 wave mode. The authors also investigated the damage sensitivity related to panel coverage area by elastic waves with large energy. An artificial damage in the form of Teflon inserts was utilised. Moreover, the influence of single and multiple acoustic wave sources on artificial damage localisation results was investigated. For this purpose RMS wave energy maps, statistical parameters, and damage indices are utilised. Different locations of ACTs and their influence on damage localisation results are investigated. A damage imaging algorithm based on wavefield irregularity mapping (WIM) has been proposed. In this research low-cost and popular, low-frequency ACT was utilised giving the possibility of realisation of the non-contact damage localisation method.

Tumor lysate-loaded Bacterial Ghosts as a tool for optimized production of therapeutic dendritic cell-based cancer vaccines.

Cancer immunotherapy with dendritic cell (DC)-based vaccines has been used to treat various malignancies for more than two decades, however generally showed a limited clinical success. Among various factors responsible for their modest clinical activity is the lack of universally applied, standardized protocols for the generation of clinical-grade DC vaccines, capable of inducing effective anti-tumor immune responses. We investigated Bacterial Ghosts (BGs) - empty envelopes of Gram-negative bacteria - as a tool for optimized production of DC vaccines. BGs possess various intact cell surface structures, exhibiting strong adjuvant properties required for the induction of DC maturation, whereas their empty internal space can be easily filled with a source tumor antigens, e.g. tumor lysate. Hence BGs emerge as an excellent platform for both the induction of immunogenic DC maturation and loading with tumor antigens in a single-step procedure. We compared the phenotype, cytokine secretion profile, functional activity and ability to induce immunogenic T-cell responses in vitro of human monocyte-derived DCs generated using BG platform and DCs matured with widely used lipopolysaccharide (LPS) plus interferon-γ cocktail and loaded with tumor lysate. Both approaches induced DC maturation, however BG-based protocol was superior to LPS-based protocol in terms of the ability to induce DCs with a lower tolerogenic potential, resulting in a more robust CD8+ T cell activation and their functional activity as well as significantly lower induction of regulatory T cells. These superior parameters are attributed, at least in part, to the ability of BG-matured DCs to resist potential immunosuppressive and pro-tolerogenic activity of various tumor cell lysates, including melanoma, renal carcinoma and glioblastoma.

Conditioned medium from HeLa cells enhances motility of human monocyte-derived dendritic cells but abrogates their maturation and endocytic activity.

Progressive tumor proliferation may be associated with suppression of the immune response. Several different mechanisms can contribute to immune evasion. It is generally proposed that inhibition of dendritic cell functions would be a key mechanism by which tumors could escape immune surveillance. Therefore, the purpose of this study was to evaluate the capacity of HeLa cells conditioned medium (HeLa-CM) to modulate phenotypic and functional parameters of human peripheral blood monocyte-derived dendritic cells (DCs). Two types of reference DCs population were generated in vitro, the first cultured in the presence of IL-4 and GM-CSF which represented immature DCs (iDCs) and the second, representing mature DCs (mDCs), was raised from the iDCs by additional stimulation with a maturation cocktail - TNF-alpha, IL-1beta, IL-6, PGE2. In parallel, the iDCs were treated with HeLa-CM collected from the tumor cells. The analysis of DC populations demonstrated that the HeLa-CM prevented maturation of these cells and also impaired their capacity to uptake an antigen and stimulate proliferation of allogeneic T cells. In contrast, HeLa-CM modulated DCs exhibited a 3-fold increase mobility over iDCs. The latter functional capacity did not correlate with the levels of matrix metalloproteinase expression in the analysed cells. Altogether, our results provide evidence that HeLa cells produce soluble factors that might dramatically alter basic phenotypic and functional characteristics of DCs.

A simple computer model of excitable synaptically connected neurons.

The space-lumped two-variable neuron model is studied. Extension of the neural model by adding a simple synaptic current allows the demonstration of neural interactions. The production of synchronous burst activity in this simple two-neuron excitatory loop is modeled, including the influence of random background excitatory input. The ability of the neuron model to integrate inputs spatially and temporally is shown. Two refractory periods after stimuli were identified and their role in burst cessation is demonstrated. Our findings show that simple neural units without long-lasting membrane processes are capable of generating long lasting patterns of activity. The results of simulation of simple background activity suggest that an increase in background activity tends to cause decreased activity of the network. This phenomenon, as well as the existence of two refractory periods, allows for burst cessation without inhibition in this simple model.

Detection of spontaneous postsynaptic potentials.

The amplitude and time course of postsynaptic potentials (PSPs) recorded by intracellular techniques contain information that allow different synaptic events to be detected. In the present paper an algorithm to detect spontaneous PSPs is described. The algorithm is based on computation of approximations of first and second derivatives of the signals. The method was tested on both computer-simulated potentials and on experimental data recorded from dissociated mouse spinal cord neurons in tissue culture. The receiver operating characteristics of the detection algorithm were computed. This method can be applied to investigations of dynamic changes in the activity of neural networks.