P2 purinergic receptor modulation of cytokine production

Cytokines serve important functions in controlling host immunity. Cells involved in the synthesis of these polypeptide mediators have evolved highly regulated processes to ensure that production is carefully balanced. In inflammatory and immune disorders, however, mis-regulation of the production and/or activity of cytokines is recognized as a major contributor to the disease process, and therapeutics that target individual cytokines are providing very effective treatment options in the clinic. Leukocytes are the principle producers of a number of key cytokines, and these cells also express numerous members of the purinergic P2 receptor family. Studies in several cellular systems have provided evidence that P2 receptor modulation can affect cytokine production, and mechanistic features of this regulation have emerged. This review highlights three separate examples corresponding to (1) P2Y6 receptor mediated impact on interleukin (IL)-8 production, (2) P2Y11 receptor-mediated affects on IL-12/23 output, and (3) P2X7 receptor mediated IL-1β posttranslational processing. These examples demonstrate important roles of purinergic receptors in the modulation of cytokine production. Extension of these cellular observations to in vivo situations may lead to new therapeutic strategies for treating cytokine-mediated diseases

Antibacterial Activity of Positive and Negative Polarity Low-voltage Pulsed Current (LVPC) on Six Typical Gram-positive and Gram-negative Bacterial Pathogens of Chronic Wounds

The positive effect of electrical stimulation (ES) on wound healing has been shown in vitro and in vivo. On the basis of increased blood flow, protein denaturation, and stimulation of cellular defense, an antibacterial effect of ES is to be expected. Although the antibacterial effect of ES already has been demonstrated in vitro, little attention has been paid to the direct antibacterial effect of changing polarity of the applied current. The aim of this study was to investigate the antibacterial effect of positive and negative monophasic low-voltage pulsed current on typical Gram-positive and Gram-negative pathogens of chronic wounds. Using the Dermapulse®-System, three Gram-negative (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae) and three Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis, Escherichia faecium) organisms were tested against positive and negative polarity low voltage pulsed current. All tested organisms were significantly reduced by ES. The reduction differed significantly between positive polarity and control and negative polarity and control, with the highest log10 reduction factor (RF) achieved with positive polarity. Using positive polarity, the maximum RF was measured for E. coli (median log10 RF 0.83; 25th percentile 0.59, 75th percentile 0.98) and the lowest for S. epidermidis (median log10 RF 0.20; 25th percentile 0.17, 75th percentile 0.24). Yet, there was no significant difference with positive ES against Gram-positive or Gram-negative organisms

Diagenetic and very low-grade metamorphic characteristics of the Paleozoic series of the Istanbul Terrane (NW Turkey)

The Istanbul Terrane along the Black Sea coast in NW Anatolia, is a Gondwana-derived continental microplate, comprising a well-developed Paleozoic succession. Petrographic and X-ray diffraction studies were performed on rock samples from measured sections throughout Ordovician-Carboniferous sedimentary units. Diagenetic-very low-grade metamorphic clastic (shale/mudstone, siltstone, sandstone) and calcareous rocks (limestone, dolomite) mainly contain phyllosilicates, quartz, feldspar, calcite, dolomite, hematite and goethite minerals. Phyllosilicates are primarily represented by illite, chlorite, mixed-layered chlorite-vermiculite (C-V), chlorite-smectite (C-S) and illite-chlorite (I-C). Feldspar is commonly present in the Ordovician and Carboniferous units, whereas calcite and dolomite are abundant in the Silurian and Devonian sediments. The most important phyllosilicate assemblage is illite + chlorite + I-C + C-V + C-S. Illite and chlorite-bearing mixed layer clays are found in all units. The amounts of illites increase in the upper parts of the Silurian series and the lower parts of the Devonian series, whereas chlorite and chlorite-bearing mixed-layers are dominant in the Ordovician and Carboniferous units. Kubler index values of illites reflect high-grade anchimetamorphism for the Early Ordovician rocks, low-grade metamorphism to high-grade diagenesis for the Middle Ordovician-Early Silurian rocks and high-grade diagenesis for the Late Silurian-Devonian units. The K-white micas b cell dimensions indicate intermediate pressure conditions in the Early Ordovician-Early Silurian units, but lower pressure conditions in the Middle Silurian-Devonian units. Illites are composed of 2M(1) +/- 1M(d) polytypes in all units, except for Upper Ordovician-Lower Silurian units which involve 1M polytype in addition to 2M(1) and 1M(d) polytypes. The 2M(1)/(2M(1) + 1M(d)) ratios rise from Devonian to Ordovician together with the increasing diagenetic-metamorphic grade. Chlorites have IIb polytype. In general, crystal-chemical data of clay minerals in the Istanbul Terrane show a gradual increase in the diagenetic/metamorphic grade together with increasing depth. The new data presented in this work indicate that the diagenetic/metamorphic grade of the Paleozoic of the Istanbul Terrane is higher than that of the neighboring Zonguldak Terrane and generated by a single metamorphic phase developed at the end of Carboniferous. This finding contrasts with the metamorphic history of the neighboring Zonguldak Terrane that displays a distinct Early Devonian unconformity and a thermal event

Variation of illite/muscovite Ar-40/Ar-39 age spectra during progressive low-grade metamorphism: an example from the US Cordillera

Ar/ Ar step-heating data were collected from micron to submicron grain-sizes of correlative illite- and muscovite-rich Cambrian pelitic rocks from the western United States that range in metamorphic grade from the shallow diagenetic zone (zeolite facies) to the epizone (greenschist facies). With increasing metamorphic grade, maximum ages from Ar/ Ar release spectra decrease, as do total gas ages and retention ages. Previous studies have explained similar results as arising dominantly or entirely from the dissolution of detrital muscovite and precipitation/recrystallization of neo-formed illite. While recognizing the importance of these processes in evaluating our results, we suggest that the inverse correlation between apparent age and metamorphic grade is controlled, primarily, by thermally activated volume diffusion, analogous to the decrease in apparent ages with depth observed for many thermochronometers in borehole experiments. Our results suggest that complete resetting of the illite/muscovite Ar thermochronometer occurs between the high anchizone and epizone, or at roughly 300 °C. This empirical result is in agreement with previous calculations based on muscovite diffusion parameters, which indicate that muscovite grains with radii of 0. 05-2 μm should have closure temperatures between 250 and 350 °C. At high anchizone conditions, we observe a reversal in the age/grain-size relationship (the finest grain-size produces the oldest apparent age), which may mark the stage in prograde subgreenschist facies metamorphism of pelitic rocks at which neo-formed illite/muscovite crystallites typically surpass the size of detrital muscovite grains. It is also approximately the stage at which neo-formed illite/muscovite crystallites develop sufficient Ar retentivity to produce geologically meaningful Ar/ Ar ages. Results from our sampling transect of Cambrian strata establish a framework for interpreting illite/muscovite Ar/ Ar age spectra at different stages of low-grade metamorphism and also illuminate the transformation of illite to muscovite. At Frenchman Mtn., NV, where the Cambrian Bright Angel Formation is at zeolite facies conditions, illite/muscovite Ar/ Ar data suggest a detrital muscovite component with an apparent age ≥967 Ma. The correlative Carrara Fm. is at anchizone conditions in the Panamint and Resting Spring Ranges of eastern California, and in these locations, illite/muscovite Ar/ Ar data suggest an early Permian episode of subgreenschist facies metamorphism. The same type of data from equivalent strata at epizone conditions (greenschist facies) in the footwall of the Bullfrog/Fluorspar Canyon detachment in southern Nevada reveals a period of slow-to-moderate Late Cretaceous cooling

Clay mineral formation in Permian rocks of a geothermal borehole at Northern Upper Rhine Graben, Germany

<jats:title>Abstract</jats:title><jats:p>Hydrothermally altered rhyolite rocks in the Permian Donnersberg Formation of a geothermal borehole in the Northern Upper Rhine Graben (Germany) were investigated to find out answers for the low hydraulic conductivity of the rocks. The composition of clay minerals and the temperature of smectite–illite transformation were carried out using X-ray diffraction, X-ray fluorescence, transmission electron microscopy, Fourier transform infrared spectroscopy, and polarized-light microscopy analyses. Clay mineral (CM) composition includes illite/muscovite (1<jats:italic>M</jats:italic>and 2<jats:italic>M</jats:italic><jats:sub>1</jats:sub>polytypes), illite–smectite interstratifications (IS-ml), smectite, and chlorite; and non-clay minerals such as quartz, feldspars, epidote, calcite, dolomite, and hematite were detected. The 2<jats:italic>M</jats:italic><jats:sub>1</jats:sub>-polytype mica might be the only primary sheet silicates from the parent rocks, while the others occur as authigenic neo-formed CMs under heat flow and geothermal gradient. The development of CMs indicates different mechanisms of illitization and smectitization. Based on the texture, morphology, structure/polytype, and chemistry of rocks and minerals, in particular CMs, the study grouped the CM formation into three transformation processes: smectitization during magma cooling and possible contact metamorphisms with decreasing and low temperature, smectite illitization controlled by burial diagenesis and hydrothermal alteration, and illite smectitization followed exhumation and Cenozoic subsidence with decreasing temperature. The rhyolites were altered to all of the orders IS-R0, IS-R1, and IS-R3 by the dissolution-precipitation and layer-to-layer mechanisms. The first one supported small xenomorphic plates and flakes of 1<jats:italic>M</jats:italic><jats:sub><jats:italic>d</jats:italic></jats:sub>, elongated particles of 1<jats:italic>M</jats:italic>, and pseudo-hexagonal forms of 2<jats:italic>M</jats:italic><jats:sub>1</jats:sub>. The second one could lead to the platy particles of 1<jats:italic>M</jats:italic><jats:sub><jats:italic>d</jats:italic></jats:sub>and 2<jats:italic>M</jats:italic><jats:sub>1</jats:sub>polytypes. The dominant temperature range for the transformation in the area has been 140–170 °C– ~ 230 °C.</jats:p&gt