Effects of the Na+/H+-exchange inhibitor Hoe 642 on intracellular pH, calcium and sodium in isolated rat ventricular myocytes

The inhibitors of the Na+/H+-exchange (NHE1) system Hoe 694 and Hoe 642 possess cardioprotective effects in ischaemia/reperfusion. It is assumed that these effects are due to the prevention of intracellular sodium (Nai) and calcium (Cai) overload. The purpose of the present study was to investigate the effects of Hoe 642 on intracellular pH, Na+ and Ca2+ (pHi, Nai and Cai) in isolated rat ventricular myocytes under anoxic conditions or in cells in which oxidative phosphorylation had been inhibited by 1.5 mmol/l cyanide. In cells which were dually loaded with the fluorescent dyes 2, 7-biscarboxyethyl-5,6-carboxyfluorescein (BCECF) and Fura-2, anoxia caused acidification of the cells (from pHi 7.2 to pHi 6.8) and an increase in Cai from about 50 nmol/l to about 1 micromol/l. The decrease in pHi began before the cells underwent hypoxic (rigor) contracture, whereas Cai only began to rise after rigor shortening had taken place. After reoxygenation, pHi returned to its control value and Cai oscillated and then declined to resting levels. It was during this phase that the cells rounded up (hypercontracture). When 10 micromol/l Hoe 642 was present from the beginning of the experiment, pHi and Cai were not significantly different from control experiments. At reoxygenation, pHi did not recover, but Cai oscillated and returned to its resting level. To monitor Nai, the cells were loaded with the dye SBFI. After adding 1.5 mmol/l cyanide or 100 micromol/l ouabain, Nai increased from the initial 8 mmol/l to approximately 16 mmol/l. Hoe 642 or Hoe 694 (10 micromol/l) did not prevent the increase in Nai. In contrast, the blocker of the persistent Na+ current R56865 (10 micromol/l) attenuated the CN--induced rise in Nai. The substance ethylisopropylamiloride was not used because it augmented considerably the intensity of the 380 nm wavelength of the cell's autofluorescence. In conclusion, the specific NHE1 inhibitor Hoe 642 did not attenuate anoxia-induced Cai overload, nor CN--induced Nai and Cai overload. Hoe 642 prevented the recovery of pHi from anoxic acidification. This low pHi maintained after reoxygenation may be cardioprotective. Other possible mechanisms of NHE1 inhibitors, such as prevention of Ca2+ overload in mitochondria, cannot be ruled out. The increase in Nai during anoxia is possibly due to an influx of Na+ via persistent Na+ channels.     

An integral equation for normal solutions to meromorphic differential equations

Normal solutions for meromorphic systems of linear ODE have been defined and studied by the author, in collaboration with W. B. Jurkat and D. A. Lutz. Here, we show that they satisfy a system of integral equations.     

First-level formal solutions and multisummability

The concept of first-level formal solutions has been introduced and studied in earlier papers of the author. Here, a different but equivalent definition is given, and their existence proof is outlined. Furthermore, it is shown how this concept leads to a proof for the multisummability of formal solutions (in the usual sense) for linear systems of ODE.     

Psychologist-legislator: Reflection on the first year in office.

As a Massachusetts State Representative, the author describes how being a psychologist affected her campaign and 1st year in office. Her history of past and current political interests in women, education, labor, and human services has contributed to her legislative and political agenda. This article reports how the Massachusetts Psychological Association played a significant role in her campaign and how mental health issues have been her top priority. Serving as a state legislator has integrated her 2 passions: political activism and psychology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the central connection problem for equations with an irregular singular point of a single level

We study the central connection problem for linear systems of equations with two singularities: one at the origin which is assumed to be regular-singular, and another one at infinity having a formal fundamental solution of only one level (in the Newton polygon).     

Bragg-wave scattering and the narrow-vee wake

A coherent radar on a cliff overlooking the ocean was used to illuminate the ocean surface at a grazing angle of 10° during and after the passage of a ship through the beam. Simultaneous L-band and X-band data were collected. The display of surface reflectivity (power) showed a prominent narrow-vee feature at L-band, as was observed in earlier L-band satellite observations. A corresponding narrow-vee structure was observed in X-band, but was not as strong as other components of the wake signature. On the other hand, the Doppler-velocity displays at both radar frequencies yielded the same distinctive signature, i.e., a pair of compact features traveling outward from the centerline, each exhibiting a Doppler velocity that was the Bragg phase velocity corresponding to that radar frequency. The location of the velocity signature coincided at L-band with that of the power signature. Further, the L-band wake was persistent enough to verify that the feature was propagating at the Bragg group velocity, roughly the same as that for X-band. This result confirms an earlier hypothesis that the mechanism underlying the narrow-vee signature is the outward propagation of Bragg waves created by the ship's passage     

Verbesserung des Eigenspannungszustands beim Kaltfließpressen durch den aktiven Einsatz eines gesteuerten Gegenstempels

By using an active counter punch during cold extrusion, the residual stress of the component can significantly be improved, which can increase its fatigue strength. In general, the workpieces produced through full‐forward extrusion are characterized by a strongly unfavourable stress state: The resulting high axial tensile residual stresses on the surface as well as the steep stress gradient accelerate the formation and the growth of cracks during cyclic loading. A system developed by the authors, consisting of a counter punch actively employed during the forming process allows improving the residual stress state of the final product. This result is obtained through a homogenization of the deformations in the samples during the cold extrusion. Therefore, a finite element simulation of the process was developed in Simufact Forming®. The simulation was experimentally validated by using the two austenitic steels 1.4307 and 1.4404. Another focus is the development of suitable measuring strategies for the X‐ray residual stress analysis with the sin²Ψ‐method to ensure the quality of the measurement results despite coarse‐grained and anisotropic microstructures. The results of the simulations and the experiments show that his technique has a considerable potential to increase the product quality without modifying the process time.     

Comparative assessments of benzene, toluene, and xylene natural attenuation by quantitative polymerase chain reaction analysis of a catabolic gene, signature metabolites, and compound-specific isotope analysis

A controlled-release study conducted at Vandenberg Air Force Base involved the injection of anaerobic groundwater amended with benzene, toluene, and o-xylene (BToX; 1-3 mg/L each) in two parallel lanes: lane A injectate contained no ethanol, whereas lane B injectate contained approximately 500 mg/L ethanol. As reported previously by Mackay and co-workers, ethanol led to slower BToX disappearance in lane B. Here, we report on assessments of BToX natural attenuation by three independent and specific monitoring approaches: signature metabolites diagnostic of anaerobic TX metabolism (benzysuccinates), compound-specific isotope analysis (CSIA), and quantitative polymerase chain reaction (qPCR) analysis of a catabolic gene involved in anaerobic TX degradation (bssA). In combination, the three monitoring methods provided strong evidence of in situ TX biodegradation in both lanes A and B; however, no single method provided strong evidence for TX biodegradation in both lanes. Benzylsuccinates were detected almost exclusively in lane B, where slower TX degradation and higher residual TX concentrations led to higher metabolite concentrations. In contrast, CSIA provided evidence of TX biodegradation almost exclusively in lane A, as greater degradation rates led to more pronounced isotopic enrichment. qPCR analyses of bssA were more complex. Evidence of increases in bssA copy number (up to 200-fold) after the release started was stronger in lane A, but higher absolute bssA copy number (and bacterial abundance, based on 16S rRNA genes) was observed in lane B, where bacteria genetically capable of anaerobic TX degradation may have been growing primarily on ethanol or its metabolites rather than TX.     

On the Convergence of Borel Approximants

For a wide class of functions having a representation as Laplace integrals, we obtain expansions in terms of certain higher transcendental functions. Compared with the classical method of expansions as factorial series, these series converge considerably faster and, at the same time, in larger regions.