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Sauer U, Borsdorf H, Dietrich P, Liebscher A, Möller I, Martens S, Möller F, Schlömer S, Schütze C. Application of open-path Fourier transform infrared spectroscopy for atmospheric monitoring of a CO 2 back-production experiment at the Ketzin pilot site (Germany). ENVIRONMENTAL MONITORING AND ASSESSMENT 2018; 190:114. [PMID: 29396669 DOI: 10.1007/s10661-018-6488-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 01/22/2018] [Indexed: 06/07/2023]
Abstract
During a controlled "back-production experiment" in October 2014 at the Ketzin pilot site, formerly injected CO2 was retrieved from the storage formation and directly released to the atmosphere via a vent-off stack. Open-path Fourier transform infrared (OP FTIR) spectrometers, on-site meteorological parameter acquisition systems, and distributed CO2 point sensors monitored gas dispersion processes in the near-surface part of the atmospheric boundary layer. The test site provides a complex and challenging mosaic-like surface setting for atmospheric monitoring which can also be found at other storage sites. The main aims of the atmospheric monitoring of this experiment were (1) to quantify temporal and spatial variations in atmospheric CO2 concentrations around the emitting vent-off stack and (2) to test if and how atmospheric monitoring can cope with typical environmental and operational challenges. A low environmental risk was encountered during the whole CO2 back-production experiment. The study confirms that turbulent wind conditions favor atmospheric mixing processes and are responsible for rapid dilution of the released CO2 leading to decreased detectability at all sensors. In contrast, calm and extremely stable wind conditions (especially occurring during the night) caused an accumulation of gases in the near-ground atmospheric layer with the highest amplitudes in measured gas concentration. As an important benefit of OP FTIR spectroscopic measurements and their ability to detect multiple gas species simultaneously, emission sources could be identified to a much higher certainty. Moreover, even simulation models using simplified assumptions help to find suitable monitoring network designs and support data analysis for certain wind conditions in such a complex environment.
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Dragatsis I, Dietrich P, Ren H, Deng YP, Del Mar N, Wang HB, Johnson IM, Jones KR, Reiner A. Effect of early embryonic deletion of huntingtin from pyramidal neurons on the development and long-term survival of neurons in cerebral cortex and striatum. Neurobiol Dis 2017; 111:102-117. [PMID: 29274742 PMCID: PMC5821111 DOI: 10.1016/j.nbd.2017.12.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 11/07/2017] [Accepted: 12/19/2017] [Indexed: 12/12/2022] Open
Abstract
We evaluated the impact of early embryonic deletion of huntingtin (htt) from pyramidal neurons on cortical development, cortical neuron survival and motor behavior, using a cre-loxP strategy to inactivate the mouse htt gene (Hdh) in emx1-expressing cell lineages. Western blot confirmed substantial htt reduction in cerebral cortex of these Emx-httKO mice, with residual cortical htt in all likelihood restricted to cortical interneurons of the subpallial lineage and/or vascular endothelial cells. Despite the loss of htt early in development, cortical lamination was normal, as revealed by layer-specific markers. Cortical volume and neuron abundance were, however, significantly less than normal, and cortical neurons showed reduced brain-derived neurotrophic factor (BDNF) expression and reduced activation of BDNF signaling pathways. Nonetheless, cortical volume and neuron abundance did not show progressive age-related decline in Emx-httKO mice out to 24 months. Although striatal neurochemistry was normal, reductions in striatal volume and neuron abundance were seen in Emx-httKO mice, which were again not progressive. Weight maintenance was normal in Emx-httKO mice, but a slight rotarod deficit and persistent hyperactivity were observed throughout the lifespan. Our results show that embryonic deletion of htt from developing pallium does not substantially alter migration of cortical neurons to their correct laminar destinations, but does yield reduced cortical and striatal size and neuron numbers. The Emx-httKO mice were persistently hyperactive, possibly due to defects in corticostriatal development. Importantly, deletion of htt from cortical pyramidal neurons did not yield age-related progressive cortical or striatal pathology.
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Grötzsch D, Streeck C, Nietzold C, Malzer W, Mantouvalou I, Nutsch A, Dietrich P, Unger W, Beckhoff B, Kanngießer B. A sealable ultrathin window sample cell for the study of liquids by means of soft X-ray spectroscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:123112. [PMID: 29289209 DOI: 10.1063/1.5006122] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A new sample cell concept for the analysis of liquids or solid-liquid interfaces using soft X-ray spectroscopy is presented, which enables the complete sealing of the cell as well as the transport into vacuum via, for example, a load-lock system. The cell uses pressure monitoring and active as well as passive pressure regulation systems, thereby facilitating the full control over the pressure during filling, sealing, evacuation, and measurement. The cell design and sample preparation as well as the crucial sealing procedure are explained in detail. As a first proof-of-principle experiment, successful nitrogen K-edge fluorescence yield near-edge X-ray absorption fine structure experiments of a biomolecular solution are presented. For this purpose, it is shown that the careful evaluation of all involved parameters, such as window type or photon flux, is desirable for optimizing the experimental result.
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Kjærvik M, Hermanns A, Dietrich P, Thissen A, Bahr S, Ritter B, Kemnitz E, Unger WES. Detection of suspended nanoparticles with near-ambient pressure x-ray photoelectron spectroscopy. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:474002. [PMID: 28891804 DOI: 10.1088/1361-648x/aa8b9d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Two systems of suspended nanoparticles have been studied with near-ambient pressure x-ray photoelectron spectroscopy: silver nanoparticles in water and strontium fluoride-calcium fluoride core-shell nanoparticles in ethylene glycol. The corresponding dry samples were measured under ultra high vacuum for comparison. The results obtained under near-ambient pressure were overall comparable to those obtained under ultra high vacuum, although measuring silver nanoparticles in water requires a high pass energy and a long acquisition time. A shift towards higher binding energies was found for the silver nanoparticles in aqueous suspension compared to the corresponding dry sample, which can be assigned to a change of surface potential at the water-nanoparticle interface. The shell-thickness of the core-shell nanoparticles was estimated based on simulated spectra from the National Institute of Standards and Technology database for simulation of electron spectra for surface analysis. With the instrumental set-up presented in this paper, nanoparticle suspensions in a suitable container can be directly inserted into the analysis chamber and measured without prior sample preparation.
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Abstract
CLINICAL/METHODICAL ISSUE Cerebellar syndromes result in distinct clinical symptoms, such as ataxia, dysarthria, dysmetria, intention tremor and eye movement disorders. STANDARD RADIOLOGICAL METHODS In addition to the medical history and clinical examination, imaging is particularly important to differentiate other diseases, such as hydrocephalus and multi-infarct dementia from degenerative cerebellar diseases. Degenerative diseases with cerebellar involvement include Parkinson's disease, multiple system atrophy as well as other diseases including spinocerebellar ataxia. ACHIEVEMENTS In addition to magnetic resonance imaging (MRI), nuclear medicine imaging investigations are also helpful for the differentiation. PRACTICAL RECOMMENDATIONS Axial fluid-attenuated inversion recovery (FLAIR) and T2-weighted sequences can sometimes show a signal increase in the pons as a sign of degeneration of pontine neurons and transverse fibers in the basilar part of the pons. The imaging is particularly necessary to exclude other diseases, such as normal pressure hydrocephalus (NPH), multi-infarct dementia and cerebellar lesions.
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Dietrich P, Fritz V, Hellerbrand C, Bosserhoff A. Tumorsuppressive MicroRNA-188-5p Reveals Novel Oncogenes for Hepatocellular Carcinoma. ZEITSCHRIFT FUR GASTROENTEROLOGIE 2016. [DOI: 10.1055/s-0036-1597499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Vienken T, Schelenz S, Rink K, Dietrich P. Sustainable intensive thermal use of the shallow subsurface-a critical view on the status quo. GROUND WATER 2015; 53:356-361. [PMID: 24826995 DOI: 10.1111/gwat.12206] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 03/11/2014] [Indexed: 06/03/2023]
Abstract
Thermal use of the shallow subsurface for heat generation, cooling, and thermal energy storage is increasingly gaining importance in reconsideration of future energy supplies. Shallow geothermal energy use is often promoted as being of little or no costs during operation, while simultaneously being environmentally friendly. Hence, the number of installed systems has rapidly risen over the last few decades, especially among newly built houses. While the carbon dioxide reduction potential of this method remains undoubted, concerns about sustainability and potential negative effects on the soil and groundwater due to an intensified use have been raised-even as far back as 25 years ago. Nevertheless, consistent regulation and management schemes for the intensified thermal use of the shallow subsurface are still missing-mainly due to a lack of system understanding and process knowledge. In the meantime, large geothermal applications, for example, residential neighborhoods that are entirely dependent up on shallow geothermal energy use or low enthalpy aquifer heat storage, have been developed throughout Europe. Potential negative effects on the soil and groundwater due to an intensive thermal use of the shallow subsurface as well as the extent of potential system interaction still remain unknown.
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Vienken T, Dietrich P. Discussion of papers: determination of hydraulic conductivity from grain-size distribution for different depositional environments. GROUND WATER 2014; 52:823-824. [PMID: 25271004 DOI: 10.1111/gwat.12278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 08/04/2014] [Indexed: 06/03/2023]
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Tsantoulis P, Migliorini D, Martin-Lluesma S, Durigova A, Bodmer A, Dietrich P, Labidi-Galy I. Mad2L1 Overexpression Leads to Early Metastasis in Breast Cancer. Ann Oncol 2014. [DOI: 10.1093/annonc/mdu327.29] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Dietrich P, Graetz KW, Mutzbauer TS. Evaluation of pressure-controlled ventilation concepts during cardiopulmonary resuscitation (CPR) in dental chairs. Oral Maxillofac Surg 2013; 17:173-179. [PMID: 22868985 DOI: 10.1007/s10006-012-0351-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Accepted: 07/25/2012] [Indexed: 06/01/2023]
Abstract
BACKGROUND Infrequent training of lay rescuers in cardiopulmonary resuscitation may lead to stomach inflation during ventilation of the unsecured airway. This is caused by a pressure loss of the lower oesophageal sphincter (LOSP) after onset of cardiac arrest. To minimise the risk of stomach inflation, the SMART BAG® (SB), a disposable flow-limited bag-valve-mask resuscitator, has been designed. Aim The aim of this study was to evaluate the occurrence of stomach inflation by use of SB in comparison to two other ventilation devices with respect to the ventilation capability. METHOD An Easy Grip® disposable bag-valve-mask resuscitator (EG), an SB and an EG with an interposed T-piece attached to a 0.5 l reservoir bag (EG/R) were compared in a manikin ventilation training setting. Fourteen dentists performed ventilations on a Mini Ventilation Training Analyzer using EG, SB and EG/R with lung compliance (LC) and LOSP being adjusted to 700 ml/kPa and 1.5 kPa (best case) and 500 ml/kPa and 0.5 kPa (worst case) in a randomised order. RESULTS Sufficient tidal volumes were obtained by use of all the three test devices regardless of LC or LOSP. No statistical differences were detected between the use of SB and EG/R. Using EG led to statistically larger volumes. Stomach inflation could only be avoided using SB and EG/R at a high LOSP regardless of LC. CONCLUSION Even in the worst case scenario, use of SB and EG/R administered sufficient tidal volumes with a significantly smaller stomach inflation compared to EG. Combination of standard bag-valve devices with a reservoir bag may provide similar protection from gastric inflation as the SMART BAG®.
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Hecht M, Fischer T, Dietrich P, Kraus W, Descalzo AB, Unger WES, Rurack K. Fluorinated Boron-Dipyrromethene (BODIPY) Dyes: Bright and Versatile Probes for Surface Analysis. ChemistryOpen 2013. [DOI: 10.1002/open.201300006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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Dietrich P, Moleda L, Kees F, Müller M, Straub RH, Hellerbrand C, Wiest R. Dysbalance in sympathetic neurotransmitter release and action in cirrhotic rats: impact of exogenous neuropeptide Y. J Hepatol 2013; 58:254-61. [PMID: 23041305 DOI: 10.1016/j.jhep.2012.09.027] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 09/24/2012] [Accepted: 09/25/2012] [Indexed: 12/16/2022]
Abstract
BACKGROUND & AIMS Splanchnic vasodilation is an essential disturbance in portal hypertension. Increased systemic sympathetic nerve activity is well known, but potential corresponding vascular desensitization is incompletely characterized. Release of splanchnic sympathetic neurotransmitters noradrenaline (NA) and co-transmitter neuropeptide Y (NPY) remains to be elucidated. Finally, the effects of exogenous NPY on these mechanisms are unexplored. METHODS Portal vein ligated cirrhotic, and control rats were used for in vitro perfusion of mesenteric arteries. Depletion of vascular pressure response was induced by repetitive electric sympathetic perivascular nerve stimulation (PNS) and performed in the absence and presence of exogenous NPY. Additionally, PNS-induced release of NA and NPY was measured. RESULTS Mesenteric PNS-induced pressure response was lower in portal hypertension. Depletion of the pressure response to PNS, representing the degree of desensitization, was enhanced in portal hypertension. NA release was elevated, whereas NPY release was attenuated in cirrhosis. Administration of exogenous NPY led to marked recovery from desensitization and vasoconstrictive improvement in cirrhotic rats, being associated with more pronounced decrease of NA release. CONCLUSIONS Pronounced depletion of splanchnic arterial pressure-response to repetitive sympathetic nerve stimulation in cirrhosis is partly attributable to altered NA release as well as to deficient NPY release. External NPY restores vascular contractility and attenuates pathologically elevated NA release in the portal hypertensive mesenteric vasculature, revealing post-, and prejunctional effects at the vascular smooth muscle motor endplate; therefore outlining encouraging therapeutic strategies.
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Hecht M, Fischer T, Dietrich P, Kraus W, Descalzo AB, Unger WES, Rurack K. Fluorinated Boron-Dipyrromethene (BODIPY) Dyes: Bright and Versatile Probes for Surface Analysis. ChemistryOpen 2013; 2:25-38. [PMID: 24551526 PMCID: PMC3594589 DOI: 10.1002/open.201200039] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Indexed: 12/22/2022] Open
Abstract
A family of bright boron-dipyrromethene-type fluorophores with a high number of fluorine atoms (F-BODIPYs) has been developed and characterized by X-ray crystallography and optical spectroscopy. The introduction of 3,5-bis(trifluoromethyl)phenyl and pentafluorophenyl moieties significantly enhances the photostability of such dyes, yielding for instance photostable near-infrared (NIR) fluorophores that show emission maxima>750 nm, when the BODIPY's π system is extended with two (dimethylamino)styryl and (dimethylamino)naphthastyryl moieties, or green-emitting BODIPYs with fluorescence quantum yields of unity. When equipped with a suitable group that selectively reacts for instance with amines, F-BODIPYs can be used as potent dual labels for the quantification of primary amino groups on surfaces by X-ray photoelectron spectroscopy (XPS) and fluorescence, two powerful yet complementary tools for the analysis of organic surface functional groups. The advantage of reactive F-BODIPYs is that they allow a fast and non-destructive mapping of the labelled supports with conventional fluorescence scanners and a subsequent quantification of selected areas of the same sample by the potentially traceable XPS technique. The performance is exemplarily shown here for the assessment of the amino group density on SiO2 supports, one of the most common reactive silica supports, in particular, for standard microarray applications.
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Schütze C, Lau S, Reiche N, Sauer U, Borsdorf H, Dietrich P. Ground-based Remote Sensing with Open-path Fourier- transform Infrared (OP-FTIR) Spectroscopy for Large-scale Monitoring of Greenhouse Gases. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/j.egypro.2013.06.330] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Girard-Lauriault PL, Dietrich P, Gross T, Unger WES. Is quantitative chemical derivatization XPS of plasma deposited organic coatings a valid analytical procedure? SURF INTERFACE ANAL 2012. [DOI: 10.1002/sia.4947] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Hottinger AF, Ben Aissa A, Bodmer A, Squiban D, Dunkel N, Maradan N, Vargas MI, Weber DC, Brendel E, Dietrich P. Phase l study of sorafenib in combination with radiation therapy and temozolomide for the first-line treatment of patients with high grade glioma. J Clin Oncol 2011. [DOI: 10.1200/jco.2011.29.15_suppl.2054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Templeton A, Rothermundt C, Cathomas R, Baertschi D, Droege C, Gautschi O, Borner MM, Fechter E, Stenner F, Winterhalder RC, Mueller B, Dutoit V, Dietrich P, Schiess R, Wild P, Thalmann GN, Klingbiel D, Gillessen S. Everolimus as first-line therapy in nonrapidly progressive metastatic castration-resistant prostate cancer (mCRPC): A multicenter phase II trial (SAKK 08/08). J Clin Oncol 2011. [DOI: 10.1200/jco.2011.29.15_suppl.4588] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Dietrich P, Anschütz U, Kugler A, Becker D. Physiology and biophysics of plant ligand-gated ion channels. PLANT BIOLOGY (STUTTGART, GERMANY) 2010; 12 Suppl 1:80-93. [PMID: 20712623 DOI: 10.1111/j.1438-8677.2010.00362.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Small molecules and metabolites often act as intra- or extracellular messengers in signal transduction pathways. Ligand-gated ion channels provide a mean to transduce those biochemical signals at the membrane into electrical events and ion fluxes. In plants, cyclic nucleotides and glutamate represent intra- and extracellular signalling ligands, respectively. While the former have been shown to regulate voltage-dependent ion channels and are supposed to activate cyclic nucleotide gated (CNG) channels, the latter are perceived by ionotropic glutamate receptors (GLRs). This review summarises our current knowledge about CNG channels and glutamate receptors in plants and their proposed roles in plant development and adaptation to biotic and abiotic stresses.
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Stauch P, Dietrich P, Bernhard M, Jaspersen D, Gries A, Hellinger A. Milzruptur nach Vorsorgekoloskopie. Chirurg 2010; 81:746-9. [DOI: 10.1007/s00104-010-1893-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Zarwell S, Dietrich S, Schulz C, Dietrich P, Michalik F, Rück-Braun K. Preparation of an Indolylfulgimide-Adamantane Linker Conjugate with Nitrile Anchoring Groups through Palladium-Catalyzed Transformations. European J Org Chem 2009. [DOI: 10.1002/ejoc.200801199] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Elsner C, Cordes T, Dietrich P, Zastrow M, Herzog TT, Rück-Braun K, Zinth W. Photochromic Bis(thiophen-3-yl)maleimides Studied with Time-Resolved Spectroscopy. J Phys Chem A 2009; 113:1033-9. [DOI: 10.1021/jp806945m] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Dragatsis I, Goldowitz D, Del Mar N, Deng YP, Meade CA, Liu L, Sun Z, Dietrich P, Yue J, Reiner A. CAG repeat lengths > or =335 attenuate the phenotype in the R6/2 Huntington's disease transgenic mouse. Neurobiol Dis 2008; 33:315-30. [PMID: 19027857 DOI: 10.1016/j.nbd.2008.10.009] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Revised: 10/15/2008] [Accepted: 10/17/2008] [Indexed: 11/17/2022] Open
Abstract
With spontaneous elongation of the CAG repeat in the R6/2 transgene to > or =335, resulting in a transgene protein too large for passive entry into nuclei via the nuclear pore, we observed an abrupt increase in lifespan to >20 weeks, compared to the 12 weeks common in R6/2 mice with 150 repeats. In the > or =335 CAG mice, large ubiquitinated aggregates of mutant protein were common in neuronal dendrites and perikaryal cytoplasm, but intranuclear aggregates were small and infrequent. Message and protein for the > or =335 CAG transgene were reduced to one-third that in 150 CAG R6/2 mice. Neurological and neurochemical abnormalities were delayed in onset and less severe than in 150 CAG R6/2 mice. These findings suggest that polyQ length and pathogenicity in Huntington's disease may not be linearly related, and pathogenicity may be less severe with extreme repeats. Both diminished mutant protein and reduced nuclear entry may contribute to phenotype attenuation.
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Levchenko V, Guinot DR, Klein M, Roelfsema MRG, Hedrich R, Dietrich P. Stringent control of cytoplasmic Ca2+ in guard cells of intact plants compared to their counterparts in epidermal strips or guard cell protoplasts. PROTOPLASMA 2008; 233:61-72. [PMID: 18648729 DOI: 10.1007/s00709-008-0307-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2007] [Accepted: 01/28/2008] [Indexed: 05/26/2023]
Abstract
Cytoplasmic calcium elevations, transients, and oscillations are thought to encode information that triggers a variety of physiological responses in plant cells. Yet Ca(2+) signals induced by a single stimulus vary, depending on the physiological state of the cell and experimental conditions. We compared Ca(2+) homeostasis and stimulus-induced Ca(2+) signals in guard cells of intact plants, epidermal strips, and isolated protoplasts. Single-cell ratiometric imaging with the Ca(2+)-sensitive dye Fura 2 was applied in combination with electrophysiological recordings. Guard cell protoplasts were loaded with Fura 2 via a patch pipette, revealing a cytoplasmic free Ca(2+) concentration of around 80 nM at -47 mV. Upon hyperpolarization of the plasma membrane to -107 mV, the Ca(2+) concentration increased to levels exceeding 400 nM. Intact guard cells were able to maintain much lower cytoplasmic free Ca(2+) concentrations at hyperpolarized potentials, the average concentration at -100 mV was 183 and 90 nM in epidermal strips and intact plants, respectively. Further hyperpolarization of the plasma membrane to -160 mV induced a sustained rise of the guard cell cytoplasmic Ca(2+) concentration, which slowly returned to the prestimulus level in intact plants but not in epidermal strips. Our results show that cytoplasmic Ca(2+) concentrations are stringently controlled in guard cells of intact plants but become increasingly more sensitive to changes in the plasma membrane potential in epidermal strips and isolated protoplasts.
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Ly J, Dietrich P, Ilnicka M, Madden F, Lee S, Novak T, Misner D. ASSESSING CARDIAC POTASSIUM CHANNEL INHIBITION IN DIFFERENT SPECIES. J Pharmacol Toxicol Methods 2007. [DOI: 10.1016/j.vascn.2007.02.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Rück-Braun K, Lager M, Dietrich P, Weinrich D. Synthesis of Nitrosoalkyl- and Amino-Substituted α,β-Unsaturated Ketones by Cleavage of the N-O-Bond of Bicyclic Δ4-Isoxazolines. HETEROCYCLES 2007. [DOI: 10.3987/com-07-s(w)59] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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