94 research outputs found

    Pulsed Amperometric Detection of sulfur compounds at noble metal electrodes in aqueous solutions

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    The application of Pulsed Amperometric Detection (PAD) to inorganic and organic sulfur compounds is shown to be feasible at noble metal electrodes in aqueous solutions in conjunction with Flow-Injection (FI) and High Performance Liquid Chromatography (HPLC) analyses. Results are illustrated for inorganic sulfur anions detected at Pt and Au in alkaline solutions. Chromatographic separation and calibration of S(\u272-), SO(,3)(\u272-) and S(,2)O(,3)(\u272-) in alkaline solution was achieved. Detection limits were determined to be \u3c5 ppm for each anion;Organic sulfur compounds also are detectable using PAD at Pt and Au. A theoretical basis is given for understanding the adsorption behavior of thiourea on Pt and Au. Linearization of calibration curves is discussed and illustrated for thiourea, and a detection limit was found to be 0.38 ppb using FI/PAD. Representative chromatograms are shown for mixtures containing thioureas, thioamides, thiophenes and dithiocarbamates. Calibration of the later two classes of compounds was achieved for HPLC/PAD and detection limits were determined to be \u3c10 ppm and \u3c85 ppm, respectively;Sulfur containing boron polyhedrals, which other laboratories have used in combination with Boron Neutron Capture Therapy (BNCT) to irradiate cancerous brain tumors, are shown to be quantitatively determined using FI and HPLC with PAD. Calibration and chromatographic separation of B(,12)H(,12)SH(\u272-), B(,12)H(,11)SSH(,11)B(,12)(\u274-) and B(,12)H(,11)S(O)SH(,11)B(,12)(\u274-) are illustrated. Detection limits of sub-nmole quantities of all three compounds were achieved

    Pulsed Amperometric Detection: a method for detecting amines in liquid chromatography

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    It is the general experience that most organic compounds including organic amines do not produce reversible anodic waves at Pt electrodes. Furthermore, amperometric detection of these compounds at a constant potential fails due to the accumulation of adsorbed reaction products and/or an oxide film at the electrode surface. Pulsed Amperometric Detection (PAD) restores surface activity through the use of a triple-step potential waveform in which detection, cleaning, and analyte adsorption potentials are applied alternately. The analytical signal is sampled within a few milliseconds after application of the detection potential, and held in electronic memory through the remainder of the pulsed potential sequence. This procedure makes possible the sensitive detection of species that adsorb at Pt electrodes. Analytical response is concluded from experiments with CN(\u27-) and Cl(\u27-) to depend upon the Langmuir adsorption isotherm for the analyte species detected. Hence, the calibration plot of 1/I(,p) vs. 1/C(,b) is linear for low surface coverages by the adsorbed analyte;Primary, secondary, and tertiary aliphatic amines, all amino acids (including secondary amino acids), and aminoglycosides are detectable. Results are shown for the direct amperometric detection of amino acids by anion exchange chromatography using NaOH as the eluent and supporting electrolyte. The detection limits are comparable to those obtained by OPA detection methods (i.e. ca, 100 ppb), and no post-column addition of reagent is necessary. Chromatographic analyses of aminoglycoside antibiotics in production broths and blood serum are also demonstrated

    On the Camera Arts and Consecutive Matters: the Writings of Hollis Frampton

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    Book Review of On the Camera Arts and Consecutive Matters: the Writings of Hollis Frampton / Edited by Bruce Jenkins.--ISBN 9780262062763. Reviewed by Steve Polta

    Antisemitismus und Antifeminismus in Covid-19-Verschwörungsmythen

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    Der Beitrag untersucht im Zuge der Covid-19-Pandemie aufgekommene Verschwörungsmythen auf Verschränkungen von Antisemitismus und Antifeminismus. Antisemitismus und Antifeminismus werden dabei als Weltanschauungen begriffen, welche u.a. in Verschwörungsmythen zu ihrem Ausdruck gelangen. Sowohl Antisemitismus als auch Antifeminismus sind in allen Bereichen der Gesellschaft verbreitet. Die Basis dieses Beitrags bildet eine Untersuchung der Telegramkanäle der Verschwörungsideolog:innen Attila Hildmann, Eva Herman und Oliver Janich im Zeitraum vom 20. Juli 2020 bis 07. August 2020. Die Telegramkanäle wurden frame-analytisch untersucht und gängige Verschwörungsmythen dadurch rekonstruiert. Diese wurden auf ihren antisemitischen und antifeministischen Gehalt und deren spezifische Verschränkung untersucht. Antifeminismus, der im vorliegenden Fall deutlich auf die Diskurse um Abtreibung und Prostitution zurückgreift, wirkt dabei in einer verstärkenden Funktion auf die antisemitische Projektionsfläche in den Verschwörungsmythen.This article examines conspiracy myths that emerged in the course of the Covid-19 pandemic to find out whether antisemitism and antifeminism are intertwined. Antisemitism and antifeminism are understood as worldviews that find expression in conspiracy myths among other things. Both antisemitism and antifeminism are widespread in all areas of society. This article is based on an investigation of the telegram channels of the conspiracy ideologues Attila Hildmann, Eva Herman and Oliver Janich in the period from 20th July 2020 to 7th August 2020. The telegram channels were examined frame-analytically and common conspiracy myths were reconstructed. These were examined for their antisemitic and antifeminist content and their specific entanglement. Antifeminism, which in this case clearly draws on the discourses around abortion and prostitution, thereby acts in a reinforcing function on the antisemitic projection surface in the conspiracy myths

    Prognostic and symptomatic aspects of rapid eye movement sleep in a mouse model of posttraumatic stress disorder

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    Not every individual develops Posttraumatic Stress Disorder (PTSD) after the exposure to a potentially traumatic event. Therefore, the identification of pre-existing risk factors and early diagnostic biomarkers is of high medical relevance. However, no objective biomarker has yet progressed into clinical practice. Sleep disturbances represent commonly reported complaints in PTSD patients. In particular, changes in rapid eye movement sleep (REMS) properties are frequently observed in PTSD patients. Here, we examined in a mouse model of PTSD whether (1) mice developed REMS alterations after trauma and (2) whether REMS architecture before and/or shortly after trauma predicted the development of PTSD-like symptoms. We monitored sleep-wake behavior via combined electroencephalogram/electromyogram recordings immediately before (24 h pre), immediately after (0–48 h post) and 2 months after exposure to an electric foot shock in male C57BL/6N mice (n = 15). PTSD-like symptoms, including hyperarousal, contextual, and generalized fear, were assessed 1 month post-trauma. Shocked mice showed early onset and sustained elevation of REMS compared to non-shocked controls. In addition, REMS architecture before trauma was correlated with the intensity of acoustic startle responses, but not contextual fear, 1 month after trauma. Our data suggest REMS as prognostic (pre-trauma) and symptomatic (post-trauma) marker of PTSD-like symptoms in mice. Translated to the situation in humans, REMS may constitute a viable, objective, and non-invasive biomarker in PTSD and other trauma-related psychiatric disorders, which could guide pharmacological interventions in humans at high risk

    Sleep scoring made easy Semi-automated sleep analysis software and manual rescoring tools for basic sleep research in mice

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    Studying sleep behavior in animal models demands clear separation of vigilance states. Pure manual scoring is time-consuming and commercial scoring software is costly. We present a LabVIEW-based, semi-automated scoring routine using recorded EEG and EMG signals. This scoring routine is • designed to reliably assign the vigilance/sleep states wakefulness (WAKE), non-rapid eye movement sleep (NREMS) and rapid eye movement sleep (REMS) to defined EEG/EMG episodes. • straightforward to use even for beginners in the field of sleep research. • freely available upon request. Chronic recordings from mice were used to design and evaluate the scoring routine consisting of an artifact-removal, a scoring- and a rescoring routine. The scoring routine processes EMG and different EEG frequency bands. Amplitude-based thresholds for EEG and EMG parameters trigger a decision tree assigning each EEG episode to a defined vigilance/sleep state automatically. Using the rescoring routine individual episodes or particular state transitions can be re-evaluated manually. High agreements between auto-scored and manual sleep scoring could be shown for experienced scorers and for beginners quickly and reliably. With small modifications to the software, it can be easily adapted for sleep analysis in other animal models

    Altered synaptic plasticity and behavioral abnormalities in CNGA3-deficient mice

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    The role of the cyclic nucleotide-gated (CNG) channel CNGA3 is well established in cone photoreceptors and guanylyl cyclase-D-expressing olfactory neurons. To assess a potential function of CNGA3 in the mouse amygdala and hippocampus, we examined synaptic plasticity and performed a comparative analysis of spatial learning, fear conditioning and step-down avoidance in wild-type mice and CNGA3 null mutants (CNGA3(-/-) ). CNGA3(-/-) mice showed normal basal synaptic transmission in the amygdala and the hippocampus. However, cornu Ammonis (CA1) hippocampal long-term potentiation (LTP) induced by a strong tetanus was significantly enhanced in CNGA3(-/-) mice as compared with their wild-type littermates. Unlike in the hippocampus, LTP was not significantly altered in the amygdala of CNGA3(-/-) mice. Enhanced hippocampal LTP did not coincide with changes in hippocampus-dependent learning, as both wild-type and mutant mice showed a similar performance in water maze tasks and contextual fear conditioning, except for a trend toward higher step-down latencies in a passive avoidance task. In contrast, CNGA3(-/-) mice showed markedly reduced freezing to the conditioned tone in the amygdala-dependent cued fear conditioning task. In conclusion, our study adds a new entry on the list of physiological functions of the CNGA3 channel. Despite the dissociation between physiological and behavioral parameters, our data describe a so far unrecognized role of CNGA3 in modulation of hippocampal plasticity and amygdala-dependent fear memory

    Serum MicroRNA-21 as Marker for Necroinflammation in Hepatitis C Patients with and without Hepatocellular Carcinoma

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    Background: MicroRNA-21 (miR-21) is up-regulated in tumor tissue of patients with malignant diseases, including hepatocellular carcinoma (HCC). Elevated concentrations of miR-21 have also been found in sera or plasma from patients with malignancies, rendering it an interesting candidate as serum/plasma marker for malignancies. Here we correlated serum miR-21 levels with clinical parameters in patients with different stages of chronic hepatitis C virus infection (CHC) and CHC-associated HCC. Methodology/Principal Findings: 62 CHC patients, 29 patients with CHC and HCC and 19 healthy controls were prospectively enrolled. RNA was extracted from the sera and miR-21 as well as miR-16 levels were analyzed by quantitative real-time PCR; miR-21 levels (normalized by miR-16) were correlated with standard liver parameters, histological grading and staging of CHC. The data show that serum levels of miR-21 were elevated in patients with CHC compared to healthy controls (P<0.001); there was no difference between serum miR-21 in patients with CHC and CHC-associated HCC. Serum miR-21 levels correlated with histological activity index (HAI) in the liver (r = −0.494, P = 0.00002), alanine aminotransferase (ALT) (r = −0.309, P = 0.007), aspartate aminotransferase (r = −0.495, P = 0.000007), bilirubin (r = −0.362, P = 0.002), international normalized ratio (r = −0.338, P = 0.034) and γ-glutamyltransferase (r = −0.244, P = 0.034). Multivariate analysis revealed that ALT and miR-21 serum levels were independently associated with HAI. At a cut-off dCT of 1.96, miR-21 discriminated between minimal and mild-severe necroinflammation (AUC = 0.758) with a sensitivity of 53.3% and a specificity of 95.2%. Conclusions/Significance: The serum miR-21 level is a marker for necroinflammatory activity, but does not differ between patients with HCV and HCV-induced HCC
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