Die Wellenzahlanalyse zur Ermittlung des Baugrundaufbaus bei der Untersuchung von Fundamentschwingungen und Bodenerschuetterungen

In sub-soil models of building sites the shear modulus of the soil, which is related to the shear wave velocity, is used for numerical calculations. By measuring the phase velocity of surface waves (in this work Rayleigh waves) the shear wave profile and henceforth the shear modulus profile of the sub-soil is determined by applying data inversion processes. In this work a new and more accurate method to experimentally determine the phase velocities of Rayleigh waves will be presented. It is based on the method of the wave number analysis and alows an exact determination and separation of surface wave modes. The advantages of the new method is illustrated by comparing the phase velocities determined by different methods. Furthermore, using the boundary element method for different sub-soil models foundation impedances and compliances are determined and compared with experimental results. Some recommendations on how to choose model parameters are made. The effects of a built in block to reduce foundation vibrations and wave propagation is investigated by analysing experimental and numerical data. (orig.)SIGLEAvailable from TIB Hannover: RA 3043(97-1) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Stimulation of Purinergic Receptors Modulates Chemokine Expression in Human Keratinocytes

ATP is abundantly released from stressed or damaged cells in response to mechanical stimulation, bacteria, or noxious agents. In this study, we have investigated the possible involvement of P2 receptors (receptor for extracellular nucleotides) in the expression and release of inflammatory mediators by human keratinocytes. Notably, extracellular ATP displayed a complex regulation of IFN-gamma-stimulated chemokine expression, with upregulation of CC chemokine ligand 2 (CCL2), CCL5 and CXC chemokine ligand 8 (CXCL8), and suppression of the receptor CXC chemokine receptor 3 (CXCR3), CXCL9, CXCL10, and CXCL11. The effect of ATP was mimicked by ADP and adenosine-5'-O-3-thiotriphosphate, whereas 2',3'-O-(4-benzoylbenzoyl) ATP (BzATP) downmodulated all chemokines investigated. UTP had no effect on IFN-gamma-stimulated chemokine secretion. The broad-spectrum P2 receptor antagonist suramin and the selective P2Y1 inhibitor adenosine 3'-phosphate 5'-phosphosulfate counteracted the effect of ATP on secretion of all the chemokines examined, whereas pyridoxal phosphate 6-azophenyl 2',4'-disulfonic acid and KN62 (1-[N,O-bis(5-isoquinoline sulfonyl)-N-methyl-L-tyrosyl] 4 phenylpiperazine) partially prevented the inhibitory effect of ATP on CXCL10 secretion, but on the other hand potentiated the ATP-stimulatory effect on CCL5, CCL2, and CXCL8 release. In lesional skin of psoriasis and atopic dermatitis patients, intense P2X7 reactivity was confined to the cell membrane of the basal layer, whereas diffuse P2Y1 immunostaining was found throughout the epidermis. Collectively, our data suggest that the orchestrated activation of distinct P2Y and P2X receptors modulates skin inflammation

Human primary keratinocytes express functional P2 receptors whose expression is modulated by inflammatory cytokines.

Extracellular nucleotides are agonists at the family of receptors known as P2 receptors. Besides a few reports (Burrell et al., 2003; Greig et al., 2003; 2003a), at present an extensive characterization of P2 receptor expression in human keratinocytes has not yet been carried out. In this study, we have investigated P2 receptor expression and function in human primary keratinocytes. Cells from healthy donors were cultured in vitro and mRNA expression was studied by RT-PCR. We found that human keratinocytes expressed the mRNA for several P2X subtypes (P2X3, P2X4, P2X5, P2X6, P2X7) while P2Y subtypes were less represented (P2Y1, P2Y2). Different cytokines (IL-4, IFN-gamma and TNF-alpha) are thought to play a role in skin diseases, particularly in psoriasis and atopic dermatitis. Human keratinocytes were challenged with cytokines and mRNA expression was analysed at different time-points. IL-4 and IFN-gamma, increased mRNA expression for the P2Y1, P2X3, P2X4 and P2X7 subtypes while, on the contrary, TNF-alpha induced a down-regulation of P2Y2, P2X3, P2X4, P2X5, P2X7. Functional expression and of P2 receptors as been shown by fluorometric analysis. Stimulation of cells with ATP and UTP, in a concentration range from 0.03 to 3000 µM induced a fast and dose-dependent increase in the intracellular calcium concentration ([Ca2+]i). ATP-gammaS, ADP and BzATP also elicited Ca2+ responses. Conversely, UDP-glucose was much less effective. Stimulation of human keratinocytes with the P2X agonist BzATP induced striking morphological changes accompanied by shedding of microvescicles from the cells. Our data show that human keratinocytes express different purinergic receptors whose stimulation is coupled to [Ca2+]i changes, and production of microvesicles. At present, microvesicle content is under investigation

A His-155 to Tyr polymorphism confers gain-of-function to the human P2X7 receptor of human leukemic lymphocytes.

The P2X(7)R is an ATP-gated cation channel expressed in hemopoietic cells that participates in both cell proliferation and apoptosis. Expression and function of the P2X(7)R have been associated with the clinical course of patients affected by chronic lymphocytic leukemia (CLL). Functional variants causing loss-of-function of the P2X(7)R have been identified, namely, polymorphisms 1513A>C (E496A), 1729T>A (I568N), and 946G>A (R307Q). Here we investigated other nonsynonymous polymorphisms located either in the extracellular portion of the receptor, such as the 489C>T (H155Y) variant, or in the long cytoplasmic tail of the receptor, such as the 1068G>A (A348T), 1096C>G (T357S), and 1405A>G (Q460R) variants. P2X(7)R function was monitored by measuring ATP-induced Ca(2+) influx in PBL of patients affected by CLL and in recombinant human embryonic kidney (HEK) 293 cells stably transfected with each single P2X(7) allelic variant. Ca(2+) influx was markedly reduced in association with the 1513C allele, whereas variants located in the same intracellular domain, such as the 1068A, 1096G, or 1405G variants, were associated with a minor functional decrease. Significant Ca(2+) flux increase was observed in lymphocytes from CLL patients bearing the 489C/T and 489T/T genotypes in association with the 1513A/A genotype. Functional analysis in recombinant HEK293 cells expressing P2X(7)R confirmed an increased ATP-dependent activation of the P2X(7) 489T mutant with respect to the wild type receptor, as assessed by both by [Ca(2+)](i) influx and ethidium uptake experiments. These data identify the 489C>T as a gain-of-function polymorphism of the P2X(7)R

The antibiotic polymyxin B modulates P2X7 receptor function

The natural peptide polymyxin B (PMB) is a well-known and potent antibiotic that binds and neutralizes bacterial endotoxin (LPS), thus preventing its noxious effects among LPS-mediated endotoxin shock in animal models. We have investigated the effect of PMB on responses mediated by the P2X(7)R in HEK293 and K562 cells transfected with P2X(7) cDNA and in mouse and human macrophages. In addition, in view of the potential exploitation of P2X(7)-directed agonists in antitumor therapy, we also investigated the effect of PMB in B lymphocytes from patients affected by chronic lymphocytic leukemia. PMB, at an optimal concentration dependent on the given cell type, greatly potentiated the effect of nucleotide-mediated P2X(7) stimulation. In particular, ATP-mediated Ca(2+) influx, plasma membrane permeabilization, and cytotoxicity were enhanced to an extent that, in the presence of PMB, cells were killed by otherwise ineffective nucleotide concentrations. The synergistic effect due to the combined application of ATP and PMB was prevented by incubation with the irreversible P2X blocker oxidized ATP (oATP), but not with the reversible antagonist 1-(N,O-bis(1,5-isoquinolinesulfonyl)-N-methyl-l-tyrosyl)-4-phenilpiperazine (KN-62). Cells lacking P2X(7) were fully insensitive to the combined stimulation with PMB and ATP. Furthermore, PMB at the concentrations used had no untoward effects on cell viability. These results point to PMB as a useful tool for the modulation of P2X(7)R function and suggest that care should be used in the evaluation of ATP-stimulated immune cell responses in the presence of PMB as they may not solely be affected by removal of contaminating LPS

A His-155 to Tyr polymorphism confers gain-of-function to the human P2X7 receptor of human leukemic lymphocytes.

The P2X(7)R is an ATP-gated cation channel expressed in hemopoietic cells that participates in both cell proliferation and apoptosis. Expression and function of the P2X(7)R have been associated with the clinical course of patients affected by chronic lymphocytic leukemia (CLL). Functional variants causing loss-of-function of the P2X(7)R have been identified, namely, polymorphisms 1513A>C (E496A), 1729T>A (I568N), and 946G>A (R307Q). Here we investigated other nonsynonymous polymorphisms located either in the extracellular portion of the receptor, such as the 489C>T (H155Y) variant, or in the long cytoplasmic tail of the receptor, such as the 1068G>A (A348T), 1096C>G (T357S), and 1405A>G (Q460R) variants. P2X(7)R function was monitored by measuring ATP-induced Ca(2+) influx in PBL of patients affected by CLL and in recombinant human embryonic kidney (HEK) 293 cells stably transfected with each single P2X(7) allelic variant. Ca(2+) influx was markedly reduced in association with the 1513C allele, whereas variants located in the same intracellular domain, such as the 1068A, 1096G, or 1405G variants, were associated with a minor functional decrease. Significant Ca(2+) flux increase was observed in lymphocytes from CLL patients bearing the 489C/T and 489T/T genotypes in association with the 1513A/A genotype. Functional analysis in recombinant HEK293 cells expressing P2X(7)R confirmed an increased ATP-dependent activation of the P2X(7) 489T mutant with respect to the wild type receptor, as assessed by both by [Ca(2+)](i) influx and ethidium uptake experiments. These data identify the 489C>T as a gain-of-function polymorphism of the P2X(7)R

Stimulation of Purinergic Receptors Modulates Chemokine Expression in Human Keratinocytes

ATP is abundantly released from stressed or damaged cells in response to mechanical stimulation, bacteria, or noxious agents. In this study, we have investigated the possible involvement of P2 receptors (receptor for extracellular nucleotides) in the expression and release of inflammatory mediators by human keratinocytes. Notably, extracellular ATP displayed a complex regulation of IFN-γ-stimulated chemokine expression, with upregulation of CC chemokine ligand 2 (CCL2), CCL5 and CXC chemokine ligand 8 (CXCL8), and suppression of the receptor CXC chemokine receptor 3 (CXCR3), CXCL9, CXCL10, and CXCL11. The effect of ATP was mimicked by ADP and adenosine-5′-O-3-thiotriphosphate, whereas 2′,3′-O-(4-benzoylbenzoyl) ATP (BzATP) downmodulated all chemokines investigated. UTP had no effect on IFN-γ-stimulated chemokine secretion. The broad-spectrum P2 receptor antagonist suramin and the selective P2Y1 inhibitor adenosine 3′-phosphate 5′-phosphosulfate counteracted the effect of ATP on secretion of all the chemokines examined, whereas pyridoxal phosphate 6-azophenyl 2′,4′-disulfonic acid and KN62 (1-[N,O-bis(5-isoquinoline sulfonyl)-N-methyl-L-tyrosyl] 4 phenylpiperazine) partially prevented the inhibitory effect of ATP on CXCL10 secretion, but on the other hand potentiated the ATP-stimulatory effect on CCL5, CCL2, and CXCL8 release. In lesional skin of psoriasis and atopic dermatitis patients, intense P2X7 reactivity was confined to the cell membrane of the basal layer, whereas diffuse P2Y1 immunostaining was found throughout the epidermis. Collectively, our data suggest that the orchestrated activation of distinct P2Y and P2X receptors modulates skin inflammation