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  • 1
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 19 (1998), S. 98-106 
    ISSN: 0197-8462
    Schlagwort(e): power-frequency ; heart rate variability ; EKG ; HRV ; EMF ; Fourier transform ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: Heart rate variability (HRV) results from the action of neuronal and cardiovascular reflexes, including those involved in the control of temperature, blood pressure and respiration. Quantitative spectral analyses of alterations in HRV using the digital Fourier transform technique provide useful in vivo indicators of beat-to-beat variations in sympathetic and parasympathetic nerve activity. Recently, decreases in HRV have been shown to have clinical value in the prediction of cardiovascular morbidity and mortality. While previous studies have shown that exposure to power-frequency electric and magnetic fields alters mean heart rate, the studies reported here are the first to examine effects of exposure on HRV. This report describes three double-blind studies involving a total of 77 human volunteers. In the first two studies, nocturnal exposure to an intermittent, circularly polarized magnetic field at 200 mG significantly reduced HRV in the spectral band associated with temperature and blood pressure control mechanisms (P = 0.035 and P = 0.02), and increased variability in the spectral band associated with respiration (P = 0.06 and P = 0.008). In the third study the field was presented continuously rather than intermittently, and no significant effects on HRV were found. The changes seen as a function of intermittent magnetic field exposure are similar, but not identical, to those reported as predictive of cardiovascular morbidity and mortality. Furthermore, the changes resemble those reported during stage II sleep. Further research will be required to determine whether exposure to magnetic fields alters stage II sleep and to define further the anatomical structures where field-related interactions between magnetic fields and human physiology should be sought. Bioelectromagnetics 19: 98-106, 1998. © 1998 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 17 (1996), S. 263-273 
    ISSN: 0197-8462
    Schlagwort(e): ELF ; EMF ; human ; neuroendocrine ; cancer ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: Two double-blind laboratory-based studies were performed to determine whether a suppression of nocturnal melatonin similar to that observed in rodents occurs when humans are exposed to magnetic fields at night. In study 1, 33 men were exposed to sham, 10 mG, or 200 mG intermittent, circularly polarized magnetic fields from 2300 to 0700 h under controlled environmental and exposure test conditions. Overall, exposure had no effect on melatonin levels. Men with preexisting low levels of melatonin, however, showed significantly greater suppression of melatonin when they were exposed to light and also when they were exposed to the 200 mG magnetic-field condition. Study 2 directly tested the hypothesis that low-melatonin subjects show enhanced sensitivity when exposed to light and to 200 mG magnetic fields. After preexposure screening, each of 40 men slept in the exposure facility on two nights. On one night, the men were sham exposed. On the other night, they were exposed to the 200 mG field condition used previously. Again, exposure had no overall effect on melatonin levels. The original finding of enhanced sensitivity in low-melatonin subjects was not replicated in this study. We conclude that the intermittent exposure conditions used in these two studies were not effective in altering nocturnal melatonin release patterns in human volunteers. Further research is underway with regard to exposure parameters, hormonal and immune system measures, and individual differences. © 1996 Wiley-Liss, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
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    Unbekannt
    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 1998-09-28
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cook, P -- New York, N.Y. -- Science. 1998 Sep 4;281(5382):1466-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Cell Biology, Sir William Dunn School of Pathology, Oxford OX2 3RE, UK. peter.cook@path.ox.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9750117" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Cell Nucleus/*metabolism ; *DNA Replication ; *Genome ; Genome, Human ; Humans ; Models, Biological ; *Transcription, Genetic
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    facet.materialart.
    Unbekannt
    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 1999-06-12
    Beschreibung: Models for replication and transcription often display polymerases that track like locomotives along their DNA templates. However, recent evidence supports an alternative model in which DNA and RNA polymerases are immobilized by attachment to larger structures, where they reel in their templates and extrude newly made nucleic acids. These polymerases do not act independently; they are concentrated in discrete "factories," where they work together on many different templates. Evidence for models involving tracking and immobile polymerases is reviewed.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cook, P R -- Wellcome Trust/United Kingdom -- New York, N.Y. -- Science. 1999 Jun 11;284(5421):1790-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK. Peter.Cook@Path.OX.AC.UK〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10364545" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; *DNA Replication ; DNA-Directed DNA Polymerase/*metabolism ; DNA-Directed RNA Polymerases/*metabolism ; Humans ; Models, Genetic ; Replication Origin ; Templates, Genetic ; *Transcription, Genetic
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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