Potent Stimulation of Blood Flow in Fingers of Volunteers after Local Short-Term Treatment with Low-Frequency Magnetic Fields from a Novel Device

A novel hand-held low-frequency magnetic stimulator (MagCell-SR) was tested for its ability to stimulate microcirculation in fingers of healthy volunteers. Blood flow during and after 5 minutes exposure was quantified using Laser Doppler Perfusion Imaging Technique. The device was positioned between the wrist and the dorsal part of the backhand. Because the increase in blood flow could be caused by a release of nitric oxide (NO) from the vascular endothelial cells we tested NO production with a fluorescence marker and quantified the measurements in cell cultures of human umbilical endothelial cells (HUVEC). Exposure increased blood flow significantly, persisted several minutes, and then disappeared gradually. In order to assess the effect of a static magnetic field, the measurements were also carried out with the device shutoff. Here, only a small increase in blood flow was noted. The application of the rotating MagCell-SR to the HUVEC cultures leads to a rapid onset and a significant increase of NO release after 15 minutes. Thus, frequencies between 4 and 12 Hz supplied by the device improve microcirculation significantly. Therefore, this device can be used in all clinical situations where an improvement of the microcirculation is useful like in chronic wound healing deficits

Potent Stimulation of Blood Flow in Fingers of Volunteers after Local Short-Term Treatment with Low-Frequency Magnetic Fields from a Novel Device

A novel hand-held low-frequency magnetic stimulator (MagCell-SR) was tested for its ability to stimulate microcirculation in fingers of healthy volunteers. Blood flow during and after 5 minutes exposure was quantified using Laser Doppler Perfusion Imaging Technique. The device was positioned between the wrist and the dorsal part of the backhand. Because the increase in blood flow could be caused by a release of nitric oxide (NO) from the vascular endothelial cells we tested NO production with a fluorescence marker and quantified the measurements in cell cultures of human umbilical endothelial cells (HUVEC). Exposure increased blood flow significantly, persisted several minutes, and then disappeared gradually. In order to assess the effect of a static magnetic field, the measurements were also carried out with the device shutoff. Here, only a small increase in blood flow was noted. The application of the rotating MagCell-SR to the HUVEC cultures leads to a rapid onset and a significant increase of NO release after 15 minutes. Thus, frequencies between 4 and 12 Hz supplied by the device improve microcirculation significantly. Therefore, this device can be used in all clinical situations where an improvement of the microcirculation is useful like in chronic wound healing deficits

The current image of the presidential contender : Donald Trump in the german and american media

Die vorliegende Masterthesis gibt einen Überblick über die Darstellungsweisen von amerikanischen und deutschen Medien bei der Berichterstattung über den Präsidentschaftsbewerber Donald J. Trump. Auf Grundlage bestehender Literatur zu den Themenbereichen Medienberichterstattung, Medientheorien und Medienwirkungstheorien wird eine Analyse zur Auswertung dieser Darstellungsweise angefertigt. Ziel dieser Masterthesis ist es, aufzuzeigen, welche stilistischen Mitteln Massenmedien bei ihrer Berichterstattung nutzen und welche Reize diese bei ihren Rezipienten auslösen kann

The use of nucleotide phosphorothioate diastereomers to define the structure of metal‐nucleotide bound to GTP‐AMP and ATP‐AMP phosphotransferases from beef‐heart mitochondria

The diastereomers of adenosine 5'-O-[1-thio]triphosphate (ATP[alpha S]) and adenosine 5'-O-[2-thio]triphosphate (ATP[beta S]) were utilized to seek unambiguous assignment of Mg2+ coordination to ATP when bound to ATP-AMP phosphotransferase from beef heart mitochondria (AK2). Similarly, the diastereomers of guanosine 5'-O-[thio]triphosphate (GTP[alpha S]) and guanosine 5'-O-[2-thio]triphosphate (GTP[beta S]) were utilized to seek unambiguous assignment of Mg2+ coordination to GTP when bound to GTP-AMP phosphotransferase from beef heart mitochondria (AK3). Furthermore the diastereomers of guanosine 5'-O-[1-thio]diphosphate (GDP-[alpha S]) have been used to assign Mg2+ coordination to GDP when bound to AK3. The ratios (V for isomer Sp)/(V for isomer Rp) obtained in the presence of Mg2+ and Cd2+ are compared to those already published for ATP-AMP phosphotransferases from pig muscle (AK1) [Kalbitzer et al. (1983) Eur. J. Biochem. 133, 221-227] and from baker's yeast (AKy) [Tomasselli and Noda (1983) Eur. J. Biochem. 132, 109-115]. In all cases, coordination of Mg2+ to the beta-phosphate via the pro-R oxygen is present, as shown by reversal of specificity for the diastereomers of ATP [beta S] or GTP [beta S] respectively on changing the metal ion. In contrast, there is no reversal of specificity for the diastereomers of ATP [alpha S] or GTP[alpha S], or for GDP[alpha S] in the case of AK3 for the reverse reaction, indicating that there is no interaction of the metal with the alpha-phosphate group. The observed stereospecificity for the alpha-thiophosphate is consistent with the assumption of an interaction of the pro-R oxygen of the alpha-phosphate group with the enzyme

Structural investigations of the Mg.ATP complex at the active site of porcine adenylate kinase using phosphorothioate analogs and electron paramagnetic resonance of Mn(II) with chiral 17O-labelled ATP analogs

The interaction between ATP, divalent metal ions and the active site of adenylate kinase from muscle has been studied by two different methods. No reversal of the relative reaction rates of the two diastereomers of adenosine 5′‐([α‐thio]triphosphate) was observed on changing the metal ion from Mg2+ to Cd2+, suggesting that the α‐phosphate group is not coordinated to the divalent metal ion in the enzyme · metal · ATP complex. This interpretation is confirmed by the lack of influence of 17O incorporated into the α‐phosphate group of ATP on the electron paramagnetic resonance (EPR) spectrum of Mn2+ at the active site of the enzyme. The specificity for the Sp diastereomer thus appears to be due to an interaction of the enzyme active site with the pro‐R oxygen of the α‐phosphate group. In contrast, the specificity of adenylate kinase for the diastereomers of adenosine 5′([β‐thio]triphosphate) is reversed from Sp to Rp on replacing Mg2+ by Cd2+, indicating an interaction of the pro‐R oxygen of the β‐phosphate group of ATP with the metal ion in the enzyme · metal · ATP complex. In agreement with this, ATP which is regio‐specifically labelled with 17O on the β‐phosphate group causes a line‐broadening of the EPR spectrum of Mn2+ at the active site, demonstrating coordination of at least one of the β‐phosphate oxygens with the metal. Using stereospecifically labelled [β‐17O]ATPs, it was found that (Rp)‐[β‐17O]ATP but not (Sp)‐[β‐17O]ATP caused a line broadening in the Mn2+ EPR spectrum similar to that seen with regio‐labelled [β‐17O]ATP, further indicating that the pro‐R oxygen of the β‐phosphate group of ATP is coordinated to the metal ion at the active site of adenylate kinase. These results lead to a value of 0.22–0.25 mT for the superhyperfine coupling constant of a single 17O‐Mn2+ interaction in a manganese‐ATP‐enzyme complex. ATP labelled with 17O on the γ‐phosphate group has no effect on the spectrum of Mn2+ at the active site, leading to the conclusion that Mg · ATP exists predominantly as a β‐monodentate complex at the active site of adenylate kinase. From the effect of H217O on the EPR spectrum of Mn2+ in the Mn · ATP complex at the active site it appears most likely that three, four or five water molecules are bound to the metal ion

The Structural Isomerisation of Human‐Muscle Adenylate Kinase as Studied by 1H‐Nuclear Magnetic Resonance

Human muscle adenylate kinase (ATP:AMP phosphotransferase, EC 2.7.4.3.) was studied by 1H-nuclear magnetic resonance spectroscopy. The C-2 and C-4 proton resonances of the active-center histidine His-36 could be identified; the pK of His-36 was determined as 6.1. The pK of His-189 is very low (4.9) although it is located at the surface of the protein. Other resonance lines are discussed in comparison with NMR spectra of porcine adenylate kinase [McDonald et al. (1975) J. Biol. Chem. 250, 6947-6954]. A pH-dependent structural isomerization as shown by X-ray crystallography in the pig enzyme [Pai et al. (1977) J. Mol. Biol. 114, 37-45] was not observed for human adenylate kinase in solution. However, the binding of adenosine(5')pentaphospho(5')adenosine (Ap5A), a bisubstrate inhibitor, to adenylate kinase causes an overall change of the NMR spectrum indicative of a large conformational change of the enzyme. The exchange rate (koff) for Ap5A was estimated as 10 s-1 and decreases by addition of Mg2+. On the basis of these values and the known dissociation constant it is likely that the binding of Ap5A is a diffusion-controlled process kon being 10(8) M-1 s-1. In conclusion, the system Ap5A/Mg2+/human adenylate kinase, which has been studied by NMR spectroscopy and X-ray diffraction in parallel, is suitable for analyzing the induced fit postulated by Jencks for all kinase-catalyzed reactions