Biotic and abiotic factors influencing the distribution of Coleogyne communities in southern Nevada

Woody plant community composition was analyzed throughout the range of Coleogyne ramosissima in the Spring and Sheep Mountain ranges of southern Nevada. The lower Coleogyne elevational boundary was analyzed in detail in Lucky Strike Canyon, on the eastern edge of the Spring Mountains. TWINSPAN (2-way indicator species analysis) identified 4 primary species and stand groups from the 2 mountain ranges (extensive survey). Analysis of DECORANA (detrended correspondence analysis) results indicated that elevation and soil depth were the environmental factors most significantly associated with distribution of species and stand groups in the extensive survey. Elevation was the only significant physical factor associated with distribution of species and stand groups in the intensive survey. Five vegetation zones form the 2 mountain ranges were identified based on their dominant species in 15 extensive transects. Coleogyne were subdivided into pure stands and upper and lower ecotones for further investigation of species distribution and environmental factors. Selected environmental factors appear to play an important role in structuring the Mojave Desert vegetation zones in southern Nevada.     

Protein arginine deiminase 4: a target for an epigenetic cancer therapy

The recent approvals of anticancer therapeutic agents targeting the histone deacetylases and DNA methyltransferases have highlighted the important role that epigenetics plays in human diseases, and suggested that the factors controlling gene expression are novel drug targets. Protein arginine deiminase 4 (PAD4) is one such target because its effects on gene expression parallel those observed for the histone deacetylases. We demonstrated that F- and Cl-amidine, two potent PAD4 inhibitors, display micromolar cytotoxic effects towards several cancerous cell lines (HL-60, MCF7 and HT-29); no effect was observed in noncancerous lines (NIH 3T3 and HL-60 granulocytes). These compounds also induced the differentiation of HL-60 and HT29 cells. Finally, these compounds synergistically potentiated the cell killing effects of doxorubicin. Taken together, these findings suggest PAD4 inhibition as a novel epigenetic approach for the treatment of cancer, and suggest that F- and Cl-amidine are candidate therapeutic agents for this disease.     

The goal of explanation

I defend the claim that understanding is the goal of explanation against various persistent criticisms, especially the criticism that understanding is not truth-connected in the appropriate way, and hence is a merely psychological (rather than epistemic) state. Part of the reason why understanding has been dismissed as the goal of explanation, I suggest, is because the psychological dimension of the goal of explanation has itself been almost entirely neglected. In turn, the psychological dimension of understanding—the Aha! experience, the sense that a certain explanation “feels right”, and so on—has been conspicuously overemphasized. I try to correct for both of these exaggerations. Just as the goal of explanation includes a richer psychological—including phenomenological—dimension than is generally acknowledged, so too understanding has a stronger truth connection than is generally acknowledged.     

Hepatocyte growth factor-mediated attraction of mesenchymal stem cells for apoptotic neuronal and cardiomyocytic cells

Human bone marrow-derived mesenchymal stem cells (MSC) home to injured tissues and have regenerative capacity. In this study, we have investigated in vitro the influence of apoptotic and necrotic cell death, thus distinct types of tissue damage, on MSC migration. Concordant with an increased overall motility, MSC migrated towards apoptotic, but not vital or necrotic neuronal and cardiac cells. Hepatocyte growth factor (HGF) was expressed by the apoptotic cells only. MSC, in contrast, revealed expression of the HGF-receptor, c-Met. Blocking HGF bioactivity resulted in significant reduction of MSC migration. Moreover, recombinant HGF attracted MSC in a dose-dependent manner. Thus, apoptosis initiates chemoattraction of MSC via the HGF/c-Met axis, thereby linking tissue damage to the recruitment of cells with regenerative potential.     

Interaction and interrelation of P2X7 and P2X4 receptor complexes in mouse lung epithelial cells

P2X4 and P2X7 receptors are ATP-gated ion channels that are co-expressed in alveolar epithelial type I cells. Both receptors are localized to the plasma membrane and partly associated with lipid rafts. Here we report on our study in an alveolar epithelial cell line of the molecular organization of P2X7R and P2X4R receptors and the effect of their knockdown. Native gel electrophoresis reveals three P2X7R complexes of ~430, ~580 and ~760 kDa. The latter two correspond exactly in size to signals of Cav-1, the structural protein of caveolae. Interestingly knockdown of P2rx7 affects protein levels, the intracellular distribution and the supramolecular organization of Cav-1 as well as of P2X4R, which is mainly detected in a complex of ~430 kDa. Our data suggest upregulation of P2X4R as a compensatory mechanism of P2X7R depletion.     

Platelets in defense against bacterial pathogens

Platelets interact with bacterial pathogens through a wide array of cellular and molecular mechanisms. The consequences of this interaction may significantly influence the balance between infection and immunity. On the one hand, recent data indicate that certain bacteria may be capable of exploiting these interactions to gain a virulence advantage. Indeed, certain bacterial pathogens appear to have evolved specific ways in which to subvert activated platelets. Hence, it is conceivable that some bacterial pathogens exploit platelet responses. On the other hand, platelets are now known to possess unambiguous structures and functions of host defense effector cells. Recent discoveries emphasize critical features enabling such functions, including expression of toll-like receptors that detect hallmark signals of bacterial infection, an array of microbicidal peptides, as well as other host defense molecules and functions. These concepts are consistent with increased risk and severity of bacterial infection as correlates of clinical abnormalities in platelet quantity and quality. In these respects, the molecular and cellular roles of platelets in host defense against bacterial pathogens are explored with attention on advances in platelet immunobiology.     

Relaxin family peptide systems and the central nervous system

Since its discovery in the 1920s, relaxin has enjoyed a reputation as a peptide hormone of pregnancy. However, relaxin and other relaxin family peptides are now associated with numerous non-reproductive physiologies and disease states. The new millennium bought with it the sequence of the human genome and subsequently new directions for relaxin research. In 2002, the ancestral relaxin gene RLN3 was identified from genome databases. The relaxin-3 peptide is highly expressed in a small region of the brain and in species from teleost to primates and has both conserved sequence and sites of expression. Combined with the discovery of the relaxin family peptide receptors, interest in the role of the relaxin family peptides in the central nervous system has been reignited. This review explores the relaxin family peptides that are expressed in or act upon the brain, the receptors that mediate their actions, and what is currently known of their functions.     

Some milestones in the study of hydrocarbon flames

Nach einigen einleitenden Bemerkungen zur Bedeutung von Fachzeitschriften für die Entwicklung der Wissenschaften und einem Hinweis auf die wichtigsten Abschnitte des Lebenslaufes von August Leopold Crelle (1780–1855) wird seine herausragende Rolle als Gründer und Herausgeber wissenschaftlicher Fachzeitschriften gewürdigt. Zunächst wird die dabei von Crelle besonders für das Journal für die reine und angewandte Mathematik geleistete Arbeit ausführlicher dargestellt, dem sich der Versuch einer Einschätzung der Bedeutung dieser Zeitschrift mit Hilfe quantitativer Kennziffern anschließt. Schließlich wird die Bedeutung des gleichfalls von Crelle begründeten Journals für die Baukunst untersucht und herausgearbeitet, daß durch das Baujournal den deutschen Ingenieuren wichtige Informationen und Erfahrungen aus dem technisch fortgeschrittenerem Ausland übermittelt wurden. Abschließend werden fünf unveröffentlichte Dokumente im Wortlaut wiedergegeben, die mit der vorstehenden Thematik im Zusammenhang stehen.