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Jansen RS, Duijst S, Mahakena S, Sommer D, Szeri F, Váradi A, Plomp A, Bergen AA, Oude Elferink RPJ, Borst P, van de Wetering K. ABCC6-mediated ATP secretion by the liver is the main source of the mineralization inhibitor inorganic pyrophosphate in the systemic circulation-brief report. Arterioscler Thromb Vasc Biol 2014; 34:1985-9. [PMID: 24969777 DOI: 10.1161/atvbaha.114.304017] [Citation(s) in RCA: 230] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVE Mutations in ABCC6 underlie the ectopic mineralization disorder pseudoxanthoma elasticum (PXE) and some forms of generalized arterial calcification of infancy, both of which affect the cardiovascular system. Using cultured cells, we recently showed that ATP-binding cassette subfamily C member 6 (ABCC6) mediates the cellular release of ATP, which is extracellularly rapidly converted into AMP and the mineralization inhibitor inorganic pyrophosphate (PPi). The current study was performed to determine which tissues release ATP in an ABCC6-dependent manner in vivo, where released ATP is converted into AMP and PPi, and whether human PXE ptients have low plasma PPi concentrations. APPROACH AND RESULTS Using cultured primary hepatocytes and in vivo liver perfusion experiments, we found that ABCC6 mediates the direct, sinusoidal, release of ATP from the liver. Outside hepatocytes, but still within the liver vasculature, released ATP is converted into AMP and PPi. The absence of functional ABCC6 in patients with PXE leads to strongly reduced plasma PPi concentrations. CONCLUSIONS Hepatic ABCC6-mediated ATP release is the main source of circulating PPi, revealing an unanticipated role of the liver in systemic PPi homeostasis. Patients with PXE have a strongly reduced plasma PPi level, explaining their mineralization disorder. Our results indicate that systemic PPi is relatively stable and that PXE, generalized arterial calcification of infancy, and other ectopic mineralization disorders could be treated with PPi supplementation therapy.
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Research Support, Non-U.S. Gov't |
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230 |
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Almendral JM, Sommer D, Macdonald-Bravo H, Burckhardt J, Perera J, Bravo R. Complexity of the early genetic response to growth factors in mouse fibroblasts. Mol Cell Biol 1988; 8:2140-8. [PMID: 2898731 PMCID: PMC363395 DOI: 10.1128/mcb.8.5.2140-2148.1988] [Citation(s) in RCA: 219] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Genes whose expression is growth factor regulated are likely to be important components in the mechanisms controlling cell proliferation and differentiation. With the aim of identifying some of those genes, a lambda cDNA library was prepared with poly(A)+ RNA from quiescent NIH 3T3 cells stimulated with serum for 4 h in the presence of cycloheximide. Differential screening of approximately 200,000 recombinant phage plaques revealed 2,540 clones that cross hybridized preferentially with [32P]cDNA derived from RNA of stimulated cells rather than with cDNA derived from nonstimulated cells. Cross hybridization of these clones identified 82 independent sequences, including c-fos and c-myc. Seventy-one clones were further studied. Analysis of the changes in transcription and mRNA levels after serum stimulation demonstrated that the kinetics and extent of the induction vary dramatically between the different genes. Cycloheximide in all cases superinduced the mRNA levels by two mechanisms, inhibiting the shutoff of transcription and prolonging the half-lives of the mRNAs. Our results showed that induction of proliferation is accompanied by the onset of a complex genetic program.
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Abstract
We here enumerate criteria that we believe are suitable for the diagnosis of migraine in children. Using these criteria, we identified 84 children retrospectively, and studied their illness for 3 to 9 years thereafter. The majority were male, and 47 patients had frontal headaches. EEGs were performed in 64 children: 17 were paroxysmal, but 7 patients never developed seizures. Referral to a neurologist occurred when there was a marked increase in the frequency or severity of headaches. Irrespective of the form of treatment, about one-half of all patients had more than a 50% reduction in headache frequency in the 6 months following their initial visit to a neurologist.
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46 |
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Van Broeckhoven J, Sommer D, Dooley D, Hendrix S, Franssen AJPM. Macrophage phagocytosis after spinal cord injury: when friends become foes. Brain 2021; 144:2933-2945. [PMID: 34244729 DOI: 10.1093/brain/awab250] [Citation(s) in RCA: 78] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 06/12/2021] [Accepted: 06/20/2021] [Indexed: 11/14/2022] Open
Abstract
After spinal cord injury (SCI), macrophages can exert either beneficial or detrimental effects depending on their phenotype. Aside from their critical role in inflammatory responses, macrophages are also specialized in the recognition, engulfment, and degradation of pathogens, apoptotic cells, and tissue debris. They promote remyelination and axonal regeneration by removing inhibitory myelin components and cellular debris. However, excessive intracellular presence of lipids and dysregulated intracellular lipid homeostasis result in the formation of foamy macrophages. These develop a pro-inflammatory phenotype that may contribute to further neurological decline. Additionally, myelin-activated macrophages play a crucial role in axonal dieback and retraction. Here, we review the opposing functional consequences of phagocytosis by macrophages in SCI, including remyelination and regeneration versus demyelination, degeneration, and axonal dieback. Furthermore, we discuss how targeting the phagocytic ability of macrophages may have therapeutic potential for the treatment of SCI.
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Journal Article |
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Koepchen HP, Klüssendorf D, Sommer D. Neurophysiological background of central neural cardiovascular-respiratory coordination: basic remarks and experimental approach. JOURNAL OF THE AUTONOMIC NERVOUS SYSTEM 1981; 3:335-68. [PMID: 6792255 DOI: 10.1016/0165-1838(81)90074-6] [Citation(s) in RCA: 68] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
This paper is comprised of a review of past contributions and their theoretical consequences and a presentation of new results in studies of the origin of sympathetic rhythms and tone. Two basic mechanisms are involved: a primary intracentral coupling with the main cardiovascular-respiratory rhythm (MCRR) generator and a secondary reflex coupling. It was found that the activity and rhythms of certain sympathetic efferents, such as the cervical sympathetic, are closely related to the MCRR. Other efferents, such as the renal sympathetics, are loosely linked and follow drives from other circuits in the genesis of their rhythms and tone. New experimental evidence is given that rhythmic and tonic activity in sympathetic nerves originates from several sources. Hence central respiratory-autonomic systems interaction is not explained by simplistic concepts.
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Sommer D, Fakata KL, Swanson SA, Stemmer PM. Modulation of the phosphatase activity of calcineurin by oxidants and antioxidants in vitro. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:2312-22. [PMID: 10759856 DOI: 10.1046/j.1432-1327.2000.01240.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Previous research has indicated that oxidants, antioxidants and the intracellular redox state regulate the activities of a variety of protein tyrosine kinases, protein tyrosine phosphatases, phospholipases and transcription factors. In order to explore the redox regulation of the serine/threonine phosphatase calcineurin, we have investigated the effects of a variety of oxidants and antioxidants on calcineurin phosphatase activity in vitro. The oxidants hydrogen peroxide, superoxide and glutathione disulfide inhibited the phosphatase activity of calcineurin in a dose-dependent manner. Incubation of purified calcineurin with the antioxidants ascorbate, ascorbate 2-phosphate, alpha-lipoic acid, N-acetyl-L-cysteine and glutathione increased phosphatase activity relative to untreated controls. In contrast, several other commonly used antioxidants, including butylated hydroxytoluene, butylated hydroxyanisole, TEMPOL (4-hydroxy-2,2,6, 6-tetramethylpiperidine-N-oxyl), Trolox (6-hydroxy-2,5,7, 8-tetramethyl-chroman-2-carboxylic acid) and dihydrolipoic acid decreased the activity of purified calcineurin, possibly through prooxidative mechanisms. Although the antioxidant pyrrolidine dithiocarbamate increased the activity of purified calcineurin, it significantly inhibited the activity of calcineurin present in crude fibroblast lysates. These results support and extend the hypothesis that redox factors modulate the phosphatase activity of calcineurin and suggest that further in vivo studies are warranted.
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65 |
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Cohen MI, Feldman JL, Sommer D. Caudal medullary expiratory neurone and internal intercostal nerve discharges in the cat: effects of lung inflation. J Physiol 1985; 368:147-78. [PMID: 4078740 PMCID: PMC1192590 DOI: 10.1113/jphysiol.1985.sp015851] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
In midcollicular decerebrate, thoracotomized, paralysed cats that were ventilated by a cycle-triggered pump and had an expiratory load, recordings were taken from expiratory neurones in the nucleus retroambigualis of the caudal medulla and from the internal intercostal nerves at T8-T9 levels. Expiratory neurone and internal intercostal activities had augmenting patterns of two types: (a) step-ramp (one-third of the neurones): a large initial increase of activity synchronous with inspiratory termination, followed by a ramp increase throughout the expiratory phase; (b) ramp (two-thirds of the neurones): a steady rise of activity without a sharp initial increase, discharge usually starting after a delay (as much as several hundred milliseconds) from the onset of expiration. Both types of unit pattern could occur together with each type of internal intercostal pattern. At the end of expiration, unit activity shut off abruptly just prior (0-120 ms) to the onset of phrenic discharge. The effects of pulmonary afferent discharge on unit and internal intercostal activities were evaluated by use of inflation tests: withholding inflation during the preceding inspiratory phase; maintaining inflation at the end-inspiratory level during expiration. Both tests produced lengthening of expiratory phase duration (TE), but their effects on activity differed. Following no-inflation during inspiration, the discharge onset delay was lengthened for most ramp neurones, but for only a minority of step-ramp neurones; the slope of activity augmentation did not change on the average; and the peak (end-expiratory) discharge frequency was only slightly increased. The predominant effect of maintained expiratory inflation was reduction of activity slope for ramp neurones and for a minority of step-ramp neurones, as well as increase of peak frequency; there was a moderate increase of discharge onset delay for ramp neurones, but not for step-ramp neurones. The lengthening of TE produced by no-inflation in the preceding inspiration was associated with lengthening of the durations of both the discharge onset delay and the discharge burst, but there was no correlation between changes of these two variables. We observed a 'reversal phenomenon': moderate inflation facilitated activity, whereas higher inflation levels depressed activity, as demonstrated by: comparison of effects of maintained expiratory deflation (removal of the expiratory load) and of maintained expiratory inflation, both of which reduced activity; comparison of effects of phasic expiratory inflations having different magnitudes.(ABSTRACT TRUNCATED AT 400 WORDS)
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research-article |
40 |
59 |
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Kindler CH, Szirt L, Sommer D, Häusler R, Langewitz W. A quantitative analysis of anaesthetist-patient communication during the pre-operative visit. Anaesthesia 2005; 60:53-9. [PMID: 15601273 DOI: 10.1111/j.1365-2044.2004.03995.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Previous communication research in general medical practice has shown that effective communication enhances patient compliance, satisfaction and medical outcome. It is expected that communication is equally important in anaesthesia, since patients often suffer from anxiety and lack of knowledge about anaesthetic procedures. However, little is known about the nature of communication during routine anaesthetic visits. The present study of 57 authentic anaesthetic visits provides the first results on the structure and content of communication in the pre-operative setting using the Roter Interaction Analysis System (RIAS). Patient-centred communication behaviours of anaesthetists and the extent of patient involvement were particularly investigated. From the 57 pre-operative visits, 18 267 utterances were coded. The mean (SD) [range] duration of the visit was 16.1 (7.8) [3.7-42.7] min. Anaesthetists provided 169 (68) and patients 153 (82) utterances per visit (53.5% vs. 46.5%). Physician and patient gender had no impact on the distribution of utterances and the duration of the visit. Conversation mainly focussed on biomedical issues with little psychosocial discussion (< 0.1% of all anaesthetist utterances). However, anaesthetists quite frequently used emotional comments toward patients (7%) and involved them in the conversation. The use of facilitators, open questions and emotional statements by the anaesthetist correlated with high patient involvement. The amount of patient participation in anaesthetic decisions was assessed with the Observing Patient Involvement Scale (OPTION). Compared with general practitioners, anaesthetists offered more opportunities to discuss treatment options (mean (SD) OPTION score 26.8 (16.8) vs. 16.8 (7.7)).
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Journal Article |
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51 |
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Sommer D, Heffels-Redmann U, Köhler K, Lierz M, Kaleta EF. [Role of the poultry red mite (Dermanyssus gallinae) in the transmission of avian influenza A virus]. Tierarztl Prax Ausg G Grosstiere Nutztiere 2016; 44:26-33. [PMID: 26830386 DOI: 10.15653/tpg-150413] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 09/30/2015] [Indexed: 11/22/2022]
Abstract
OBJECTIVE The aim of this study was to investigate the role of the poultry red mite (Dermanyssus [D.] gallinae) in the horizontal transmission of avian influenza A virus (AIV) to chickens. This mite is the most common ectoparasite in poultry worldwide, and may play a role in the spread of infectious agents including AIV. Currently, the control of mites is difficult due to frequently developed resistance to many acaricides, their nocturnality and their ability to survive hidden without feeding for months. MATERIALS AND METHODS D. gallinae were collected in a commercial layer farm and housed in self-made fibreboard boxes. SPF chickens were intravenously infected with AIV strain A/turkey/Ontario/7732/1966 (H5N9). The viraemia in chickens was monitored and at an appropriate time point about 1000 mites were allowed to suck on the AIV infected chickens. Re-isolation of the virus from blood-filled mites was tried daily for 14 days using chicken embryo fibroblast cultures and embryonated chicken eggs. Subsequently, the virus containing mites were placed into boxes that contained naïve SPF chickens to enable virus transmission from mites to chickens. Possible transmission to the chickens was examined using clinical signs, serology, gross lesions, histopathology and immunohistochemistry. RESULTS Chickens developed a dose-dependent viraemia one day after infection, therefore this day was chosen for the bloodmeal of the mites. AIV was detected in mites after bloodsucking on AIV-infected chickens over a 10-day period. Naïve SPF chickens were infected during bloodsucking of AIV carrying mites. AIV isolates in mites and in chickens were undistinguishable from the original AIV inoculum by RT-PCR. CONCLUSIONS D. gallinae ingested AIV during bloodmeals on AIV infected chickens and are able to transmit AIV to SPF chickens. Therefore, mites serve as mechanical vector of AIV and may play a major role in the circulation of AIV within a facility or area although the life span of infectious virus in the mite is limited. CLINICAL RELEVANCE The proven transmission requires more than ever a systematic control of this ectoparasite in order to maintain poultry health and productivity. The demonstrated vector function of this mite is of great significance for poultry flocks all over the world.
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Journal Article |
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Romero LC, Sommer D, Gotor C, Song PS. G-proteins in etiolated Avena seedlings. Possible phytochrome regulation. FEBS Lett 1991; 282:341-6. [PMID: 1903719 DOI: 10.1016/0014-5793(91)80509-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The molecular mechanism of light signal transduction in plants mediated by the photosensor phytochrome is not well understood. The possibility that phytochrome initiates the signal transduction chain by modulating a G-protein-like receptor is examined in the present work. Etiolated Avena seedlings contain G-proteins as examined in terms of the binding of GTP as well as by cross-reaction with mammalian G-protein antibodies. The binding of GTP was regulated in vivo by red/far-red light. The possible involvement of G-proteins in the phytochrome-mediated signal transduction in etiolated Avena seedlings has been implicated from the study of the light regulated expression of the Cab and phy genes.
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Sommer D, Forte V. Advances in the management of major airway collapse: the use of airway stents. Otolaryngol Clin North Am 2000; 33:163-77. [PMID: 10637350 DOI: 10.1016/s0030-6665(05)70213-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The management of major airway collapse in the pediatric age group has evolved and continues to evolve over time. Tracheobronchomalacia, either primary or secondary, is still the most frequent cause of major airway collapse. This article reviews tracheobronchomalacia and discusses several treatment options; from traditional aortopexy to the more recent introduction of tracheobronchial stenting. Various types of stents are discussed and the authors' preferences are included.
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Review |
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Korr H, Kurz C, Seidler TO, Sommer D, Schmitz C. Mitochondrial DNA synthesis studied autoradiographically in various cell types in vivo. Braz J Med Biol Res 1998; 31:289-98. [PMID: 9686151 DOI: 10.1590/s0100-879x1998000200012] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
It is generally accepted that mitochondria are able to proliferate even in postmitotic cells due to their natural turnover and also to satisfy increased cell energy requirements. However, no detailed studies are available, particularly with respect to specific cell types. Since [3H]-thymidine is incorporated not only into nuclear (n) DNA but also into the DNA of cytoplasmic mitochondria, an autoradiographic approach was developed at the light microscopy level in order to study basic questions of mitochondrial (mt) proliferation in organs of rodents in situ via the cytoplasmic incorporation of [3H]-thymidine injected into the animals 1 h before sacrifice. Experiments carried out on mice after X-irradiation showed that cytoplasmic labeling was not due to a process such as unscheduled nuclear DNA synthesis (nUDS). Furthermore, half-lives of mitochondria between 8-23 days were deduced specifically in relation to cell types. The phase of mtDNA synthesis was about 75 min. Finally, mt proliferation was measured in brain cells of mice as a function of age. While all neurons showed a decreasing extent of mtDNA synthesis during old age, nUDS decreased only in distinct cell types of the cortex and hippocampus. We conclude that the leading theories explaining the phenomenon of aging are closely related, i.e., aging is due to a decreasing capacity of nDNA repair, which leads to unrepaired nDNA damage, or to an accumulation of mitochondria with damaged mtDNA, which leads to a deficit of cellular energy production.
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Review |
27 |
39 |
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Sommer D, Ohls K. Direkte Probeneinführung in ein stabil brennendes, induktiv gekoppeltes Plasma. ACTA ACUST UNITED AC 1980. [DOI: 10.1007/bf00474365] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Navez ML, Monella C, Bösl I, Sommer D, Delorme C. 5% Lidocaine Medicated Plaster for the Treatment of Postherpetic Neuralgia: A Review of the Clinical Safety and Tolerability. Pain Ther 2015; 4:1-15. [PMID: 25896574 PMCID: PMC4470968 DOI: 10.1007/s40122-015-0034-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Indexed: 12/23/2022] Open
Abstract
Postherpetic neuralgia (PHN) is a common, very painful, and often long-lasting complication of herpes zoster which is frequently underdiagnosed and undertreated. It mainly affects the elderly, many of whom are already treated for comorbidities with a variety of systemic medications and are thus at high risk of drug-drug interactions. An efficacious and safe treatment with a low interaction potential is therefore of high importance. This review focuses on the safety and tolerability of the 5% lidocaine medicated plaster, a topical analgesic indicated for the treatment of PHN. The available literature (up to June 2014) was searched for publications containing safety data regarding the use of the 5% lidocaine medicated plaster in PHN treatment; unpublished clinical safety data were also included in this review. The 5% lidocaine medicated plaster demonstrated good short- and long-term tolerability with low systemic uptake (3 ± 2%) and minimal risk for systemic adverse drug reactions (ADRs). ADRs related to topical lidocaine treatment were mainly application site reactions of mild to moderate intensity. The treatment discontinuation rate was generally below 5% of patients. In one trial, the 5% lidocaine medicated plaster was better tolerated than systemic treatment with pregabalin. The 5% lidocaine medicated plaster provides a safe alternative to systemic medications for PHN treatment, including long-term pain treatment.
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Journal Article |
10 |
32 |
15
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Feldman JL, Sommer D, Cohen MI. Short time scale correlations between discharges of medullary respiratory neurons. J Neurophysiol 1980; 43:1284-95. [PMID: 7373367 DOI: 10.1152/jn.1980.43.5.1284] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
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Sommer D, Golz M. Evaluation of PERCLOS based current fatigue monitoring technologies. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2011; 2010:4456-9. [PMID: 21095770 DOI: 10.1109/iembs.2010.5625960] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In an overnight driving simulation study three commercially available devices of fatigue monitoring technologies (FMT) were applied to test their accuracy. 16 volunteers performed driving tasks during eight sessions (40 min each) separated by 15 minutes breaks. The main output variable of FMT devices, which is the percentage of eye closure (PERCLOS), the driving performance (standard deviation of lateral position in lane, SDL), the electroencephalogram (EEG) and electrooculogram (EOG) were recorded during driving. In addition, the subjective self-rated Karolinska sleepiness scale (KSS) was assessed every 2 min. As expected, Pearson product-moment correlation coefficient (PMCC) yielded significant linear dependence between KSS and PERCLOS as well as between SDL and PERCLOS. However, if PMCC was estimated within smaller data segments (3 min) as well as without averaging across subjects then strongly decreased correlation coefficients resulted. To further validate PERCLOS at higher temporal resolution its ability to discriminate between mild and strong fatigue was investigated and compared to the results of the same analysis for EEG/EOG. Spectral-domain features of both types of signals were classified using Support-Vector Machines (SVM). Results suggest that EEG/EOG indicate driver fatigue much better than PERCLOS. Therefore, current FMT devices perform acceptably if temporal resolution is low (> 20 min). But, even under laboratory conditions large errors have to be expected if fatigue is estimated on an individual level and with high temporal resolution.
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Research Support, Non-U.S. Gov't |
14 |
31 |
17
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Wouters E, de Wit NM, Vanmol J, van der Pol SMA, van het Hof B, Sommer D, Loix M, Geerts D, Gustafsson JA, Steffensen KR, Vanmierlo T, Bogie JFJ, Hendriks JJA, de Vries HE. Liver X Receptor Alpha Is Important in Maintaining Blood-Brain Barrier Function. Front Immunol 2019; 10:1811. [PMID: 31417573 PMCID: PMC6685401 DOI: 10.3389/fimmu.2019.01811] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 07/17/2019] [Indexed: 12/17/2022] Open
Abstract
Dysfunction of the blood-brain barrier (BBB) contributes significantly to the pathogenesis of several neuroinflammatory diseases, including multiple sclerosis (MS). Potential players that regulate BBB function are the liver X receptors (LXRs), which are ligand activated transcription factors comprising two isoforms, LXRα, and LXRβ. However, the role of LXRα and LXRβ in regulating BBB (dys)function during neuroinflammation remains unclear, as well as their individual involvement. Therefore, the goal of the present study is to unravel whether LXR isoforms have different roles in regulating BBB function under neuroinflammatory conditions. We demonstrate that LXRα, and not LXRβ, is essential to maintain barrier integrity in vitro. Specific knockout of LXRα in brain endothelial cells resulted in a more permeable barrier with reduced expression of tight junctions. Additionally, the observed dysfunction was accompanied by increased endothelial inflammation, as detected by enhanced expression of vascular cell adhesion molecule (VCAM-1) and increased transendothelial migration of monocytes toward inflammatory stimuli. To unravel the importance of LXRα in BBB function in vivo, we made use of the experimental autoimmune encephalomyelitis (EAE) MS mouse model. Induction of EAE in a constitutive LXRα knockout mouse and in an endothelial specific LXRα knockout mouse resulted in a more severe disease score in these animals. This was accompanied by higher numbers of infiltrating leukocytes, increased endothelial VCAM-1 expression, and decreased expression of the tight junction molecule claudin-5. Together, this study reveals that LXRα is indispensable for maintaining BBB integrity and its immune quiescence. Targeting the LXRα isoform may help in the development of novel therapeutic strategies to prevent BBB dysfunction, and thereby neuroinflammatory disorders.
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research-article |
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31 |
18
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Golz M, Sommer D, Trutschel U, Sirois B, Edwards D. Evaluation of fatigue monitoring technologies. SOMNOLOGIE 2010. [DOI: 10.1007/s11818-010-0482-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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29 |
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Abstract
In most patients with hypomelanosis of Ito, the hypopigmentation is characterized by narrow bands following the lines of Blaschko. We report a 13-year-old severely retarded girl with leaf-shaped patches of hypopigmentation on the back together with short stature, scoliosis, facial dysmorphism, and asymmetrical leg length. The cytogenetic examination of both lymphocytes and fibroblasts demonstrated a mosaicism of 46,XX/47,XX+13. This result was confirmed by in situ hybridization using a chromosome 13-specific library in interphase cells. The pigmentary disturbance of our patient was similar to the phylloid pattern (type 3) of the classification of pigmentary patterns postulated by Happle. This type has been described in four patients so far, along with additional anomalies and a chromosomal mosaisicm in two patients.
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Case Reports |
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Ohls K, Sommer D. Direkte Analyse fester Proben mit der induktiv gekoppelten Plasma-Emissionsspektrometrie bei hoher Leistung. ACTA ACUST UNITED AC 1979. [DOI: 10.1007/bf00471932] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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46 |
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21
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Broggio D, Bento J, Caldeira M, Cardenas-Mendez E, Farah J, Fonseca T, Konvalinka C, Liu L, Perez B, Capello K, Cowan P, Cruzate JA, Freire L, Gómez-Ros JM, Gossio S, Heide B, Huikari J, Hunt J, Kinase S, Kramer G, Kurihara O, Kyrieleis A, Lebacq AL, Leone D, Li C, Li J, Mihailescu LC, Moraleda M, Navarro JF, Oliveira C, Puerta N, Reichelt U, Simões C, Sommer D, Takahashi M, Teles P, Vanhavere F, Vrba T, Franck D, Gualdrini G, Lopez MA. Monte Carlo modelling for the in vivo lung monitoring of enriched uranium: Results of an international comparison. RADIAT MEAS 2012. [DOI: 10.1016/j.radmeas.2012.04.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Ballou LU, Pasquini M, Bremel RD, Everson T, Sommer D. Factors affecting herd milk composition and milk plasmin at four levels of somatic cell counts. J Dairy Sci 1995; 78:2186-95. [PMID: 8598403 DOI: 10.3168/jds.s0022-0302(95)76846-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A longitudinal study was carried out on samples of bulk tank milk collected from 200 farms for 12 mo to evaluate SCC, plasmin and plasminogen activities, psychrotrophic bacteria count, and protein quality in milk and to examine the proteolytic effects of plasmin on milk proteins. Herds were selected randomly from client lists of two dairies to create four groups based on milk SCC of the month before the study; herds were reassigned monthly to one of four groups based on SCC for that month. Overall means were 3.73% fat, 3.13% protein by infrared analysis, 3.16% protein by Kjeldahl analysis, 2.42% casein percentage, 4.65% lactose, 5.43 cells/ml of log SCC, 1.13 U of plasmin, 45.6 U of plasminogen, and log 2.86 cfu/ml of psychrotrophic bacteria. The ANOVA showed a significant effect of month on all factors except SCC, which was fixed by the experimental design. Plasmin and plasminogen activities were high from December to May. Plasmin activities and psychrotroph counts were significantly higher for the high SCC group. Casein percentage and number were significantly higher for the low SCC group.
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Sommer D, Song PS. A plant nucleoside diphosphate kinase homologous to the human Nm23 gene product: purification and characterization. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1222:464-70. [PMID: 8038216 DOI: 10.1016/0167-4889(94)90055-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Nucleoside diphosphate kinases (NDPKs) catalyze the transfer of high-energy phosphates from nucleoside triphosphates to nucleoside diphosphates and may be involved in the regulation of growth, development, and signal transduction processes. We report here the purification and characterization of NDPK from detergent-solubilized extracts of dark-grown oat (Avena) tissue. The purification was achieved primarily through adsorption to GTP-agarose, followed by elution with ATP. SDS-polyacrylamide gel electrophoresis and gel filtration chromatography indicated that the purified protein is composed of six 18 kDa subunits. Substrate specificity experiments indicated that the purified kinase is capable of using all tested nucleosides as substrates. N-terminal sequencing of the Avena protein revealed that 87% of the 23 amino acids sequenced were identical to the human Nm23 protein, a nucleoside diphosphate kinase identified as a possible tumor metastasis suppressor and transcriptional activator of the myc oncogene.
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Comparative Study |
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Sommer D, Song PS. Chromophore topography and secondary structure of 124-kilodalton Avena phytochrome probed by Zn2(+)-induced chromophore modification. Biochemistry 1990; 29:1943-8. [PMID: 2184893 DOI: 10.1021/bi00459a040] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The relative extent of chromophore exposure of the red-absorbing (Pr) and far-red-absorbing (Pfr) forms of 124-kDa oat phytochrome and the secondary structure of the phytochrome apoprotein have been investigated by using zinc-induced modification of the phytochrome chromophore. The absence of bleaching of Pr in the presence of a 1:1 stoichiometric ratio of zinc ions, in contrast to extensive spectral bleaching of the Pfr form, confirms previous reports of differential exposure of the Pfr chromophore relative to the Pr chromophore [Hahn et al. (1984) Plant Physiol. 74, 755-758]. The emission of orange fluorescence by zinc-chelated Pfr indicates that the Pfr chromophore has been modified from its native extended/semi-extended conformation to a cyclohelical conformation. Circular dichroism (CD) analyses of native phytochrome in 20 mM Tris buffer suggests that the Pr-to-Pfr phototransformation is accompanied by a photoreversible change in the far-UV region consistent with an increase in the alpha-helical folding of the apoprotein. The secondary structure of phytochrome in Tris buffer, as determined by CD, differs slightly from that of phytochrome in phosphate buffer, suggesting that phytochrome is a conformationally flexible molecule. Upon the addition of a 1:1 molar ratio of zinc ions to phytochrome, a dramatic change in the CD of the Pfr form is observed, while the CD spectrum of the Pf form is unaffected. Analysis of the bleached Pfr CD spectrum by the method of Chang et al. (1978) reveals that chelation with zinc ions significantly alters the secondary structure of the phytochrome molecule, specifically by increasing the beta-sheet content primarily at the expense of alpha-helical folding.(ABSTRACT TRUNCATED AT 250 WORDS)
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Sanchez S, Lemmens S, Baeten P, Sommer D, Dooley D, Hendrix S, Gou Fabregas M. HDAC3 Inhibition Promotes Alternative Activation of Macrophages but Does Not Affect Functional Recovery after Spinal Cord Injury. Exp Neurobiol 2018; 27:437-452. [PMID: 30429652 PMCID: PMC6221838 DOI: 10.5607/en.2018.27.5.437] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 09/07/2018] [Accepted: 09/28/2018] [Indexed: 12/31/2022] Open
Abstract
After spinal cord injury (SCI), monocyte derived macrophages play a detrimental role. Histone deacetylases (HDACs) are central epigenetic regulators of macrophage-polarization. We hypothesized that HDAC3 inhibition suppresses the pro-inflammatory macrophage phenotype (M1), promotes the anti-inflammatory phenotype (M2) and improves functional recovery after SCI. Therefore, two inhibitors of HDAC3 were selected, namely scriptaid and RGFP966. The impact on macrophage polarization was studied by investigating the effect on gene and protein expression of selected M1 and M2 markers. We show that scriptaid differentially influences M1 and M2 markers. It increases CD86 and iNOS gene expression and decreases GPR18, CD38, FPR2 and Arg-1 gene expression as well as the production of IL-6 and NO. RGFP966 primarily increased the expression of the M2 markers Arg-1 and Ym1 and reduced the production of IL-6 (M1). RGFP966 and scriptaid reduced the formation of foamy macrophages. Finally, to investigate the impact of HDAC3 inhibition on functional recovery after SCI, we studied the effects of RGFP966 and scriptaid in an in vivo T-cut hemisection SCI model. Histological analyses were performed on spinal cord sections to determine lesion size and astrogliosis, demyelinated area and selected infiltrating immune cells. RGFP966 and scriptaid did not affect functional recovery or histopathological outcome after SCI. In conclusion, these results indicate that specific HDAC3 inhibition with RGFP966 promotes alternative activation of macrophages and reduces the formation of foamy macrophages, but does not lead to a better functional recovery after SCI.
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