Bildung von Senkungsmulden in Lösslehm durch subterrane Erosion

Grundwasser - Eine temporär aktive Bachschwinde nahe der Stadt Koblenz ermöglicht einen Einblick in den lokalen Grundwasserfluss im Rheinischen Schiefergebirge. Ein im Lösslehm...     

Staff security and work pressure: contrasting patterns of stability and change across five dialysis units

We have previously shown that extracellular ATP, like norepinephrine (NE) and many other hypertrophy-inducing agents, increases expression of the immediate-early genes c-fos and junB in cultured neonatal cardiac myocytes but that the intracellular signaling pathways activated by ATP and responsible for these changes differ from those stimulated by NE. Furthermore, whereas NE increases incorporation of [14C]phenylalanine (14C-Phe) and cell size in neonatal cardiomyocytes, ATP does not. Since ATP is coreleased with NE from sympathetic nerve endings in the heart, we investigated whether ATP could modulate cardiac hypertrophy induced by adrenergic agonists, such as NE. We report in the present study that extracellular ATP inhibited the increase in incorporation of 14C-Phe into cellular protein and the increase in cell size in neonatal rat cardiac myocytes that was induced by NE, phenylephrine (PE), basic fibroblast growth factor, or endothelin-1. This inhibition was dose dependent, occurred predominantly through P2 purinergic receptors, and was observed even when cells were treated with ATP for as little as 1 hour before the addition of the hypertrophy-inducing agent. ATP also selectively affected changes in gene expression associated with hypertrophy. It prevented PE-stimulated increases in atrial natriuretic factor and myosin light chain-2 mRNA levels, while appearing to augment basal and PE-stimulated skeletal alpha-actin mRNA levels. ATP alone increased sarcoplasmic reticulum Ca2+-ATPase mRNA levels but had no effect when added with PE. ATP did not significantly affect the level of the constitutively expressed mRNA for GAPDH. Neither the PE-stimulated increase in immediate-early gene expression nor the initial induction of mitogen-activated protein kinase activity by PE was inhibited by ATP. These results demonstrate that extracellular ATP can inhibit hypertrophic growth of neonatal cardiac myocytes and differentially alter the changes in gene expression that accompany hypertrophy.     

Invited perspective: in vitro testing in developmental toxicity risk assessment

A surgical intervention is needed in patients with periodontal pouches deeper than 4-5 mm. The results of 239 operations in 182 patients are analyzed. Optimal variants of the operations are described, depending on the patient's status, analgesia, types of secondary adentia, surgical access, and intervals between the operations.     

Perilipin: unique proteins associated with intracellular neutral lipid droplets in adipocytes and steroidogenic cells

For several reasons it seems reasonable to suspect that perilipins participate in lipid hydrolysis. First, they are located at the lipid droplet surface, the presumed site of HSL and cholesteryl esterase action. Secondly, they are polyphosphorylated by PKA in concert with lipid hydrolysis. Finally, these proteins appear to be expressed primarily, if not solely, in adipocytes and steroidogenic cells, cells in which lipid hydrolysis is stimulated by cyclic AMP and mediated by HSL or cholesteryl esterase(s), whereas other cells that contain abundant neutral lipid depositions contain no perilipin [13]. Interestingly, these closely related hydrolases share no homology with other mammalian lipases [3]. Although such attributes provide a link between perilipin and lipid hydrolysis, we have no evidence that perilipins participate directly in, or are necessary for, lipid catabolism. The basis for the strong affinity between the perilipins and neutral lipids is unknown. Clearly, lipids and perilipins are tightly linked, as evidenced by selective targeting of epitope-tagged perilipin to lipid droplets and by the paradoxical appearance of lipid droplets in pre-adipocytes transfected with a sense perilipin A construct. Indeed, in differentiating adipocytes the earliest lipid depositions are associated with perilipins, and restriction of perilipin synthesis with anti-sense constructs may impede lipid formation and deposition. It remains to be determined if, in the normal course of events, perilipins are directed toward lipid depositions or if lipids are transported to perilipin foci. Whatever the temporal sequence, the result is that neutral lipids are encased in perilipin-bounded droplets.(ABSTRACT TRUNCATED AT 250 WORDS)     

The structure of R(1-x)Ga2(1- x)(0 < x < 0.33) and its relation to RGa6 (R = Rare Earth Element) and Ga

X-ray diffraction studies were used to investigate the wide solubility range of Ga in RGa₂ type compounds observed in several systems of light rare earth metals (= R) with Ga. A model, based on pairwise substitution of R atoms by Ga atoms, is suggested to explain the observed wide solubility. Using this model it is possible to explain the change in lattice parameters of the ε phase having the formula R(_1-x)Ga₂(_1+x). The structural relationships among the phases RGa₂, R(_1-x)Ga₂(_1+x,RGa₆, and pure Ga are delineated, and the common feature of these phases which belong to widely different crystal systems is shown.     

Analyzing and Synthesizing Images by Evolving Curves with the Osher-Sethian Method

Numerical analysis of conservation laws plays an important role in the implementation of curve evolution equations. This paper reviews the relevant concepts in numerical analysis and the relation between curve evolution, Hamilton-Jacobi partial differential equations, and differential conservation laws. This close relation enables us to introduce finite difference approximations, based on the theory of conservation laws, into curve evolution. It is shown how curve evolution serves as a powerful tool for image analysis, and how these mathematical relations enable us to construct efficient and accurate numerical schemes. Some examples demonstrate the importance of the CFL condition as a necessary condition for the stability of the numerical schemes.     

Rapid sintering protocol produces dense ceria‐based ceramics

We report on a rapid sintering protocol, which optimizes the preparation of 0‐29 mol% Gd‐doped ceria ceramics with density ≥98% of the theoretical crystal lattice value. The starting material is a nanometer grain‐sized powder prepared by carbonate co‐precipitation and calcined with minimal agglomeration and loss of surface area. Slow (5°C/min) heating of the green‐body from 500°C to the optimum temperature of rapid sintering (, dwell time <1 minute) followed by 20°C/min cooling to 1150°C with 6 minutes dwell time, produces maximum pellet density. increases from 1300 to ~1500°C with increase in Gd‐content, while the average grain size in the maximally dense pellets, as determined by scanning electron microscopy, ranges between 600 nm and ~1 μm. For each doping level, the logarithm of the average grain size decreases linearly with 1/T₁. By avoiding extended exposure to sintering temperatures, this protocol is expected to minimize undesirable Gd segregation.     

Energetics of bulk lutetium‐doped Ce1−xLuxO2−x/2 compounds

The dissolution enthalpy, ΔH_DS, and the formation enthalpy, ΔH_f,ox, of bulk lutetium‐doped cerium oxide (LuDC) were studied at 701°C in molten sodium molybdate. For the composition range of Ce_1?XLu_XO_2?X/2, studied 0 ≤ X ≤ 0.3, the ΔH_DS decreases linearly and smoothly with lutetium content according to ΔH_DS, kJ/mol = 73.5(1.0)?165.1(5.5)·x). The enthalpy of formation, ΔH_f,ox, becomes more exothermic linearly with lutetium content. No anomaly in ΔH_f,ox is observed at low Lu₂O₃ concentration as reported previously for several other rare‐earth‐doped ceria systems, suggesting possible differences in clustering and microstructure, which may also be related to difference in processing conditions.