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  • 1
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 222 (1969), S. 605-605 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] SIR,-In the December 14 issue of Nature (220, 1078; 1968) your cell biology correspondent referred to a paper by Grouse (Proc. US Nat. Acad. Sci., 61, 971; 1968) in which some experiments of ours were repeated concerning the prevention of puff formation in Sciara coprophila by cortisone. In our ...
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-0886
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract We have investigated the possibility that some high molecular weight nonhistone chromosomal (NHC) proteins may have been conserved through the evolution of two distantly related diptera-Drosophila melanogaster and Sciara coprophila. Antisera produced against three NHC protein subfractions were analyzed for cross-reactivity with Sciara polytene chromosomes. The indirect immunofluorescent staining technique used couples an assay for immunologic cross-reactivity with an assay for the in situ distribution of the proteins under study. The results indicate that the σ-φ and ϱ NHC protein antigens have been conserved since the divergence of Drosophila and Sciara, while the Drosophila π NHC protein antigen is not present on Sciara chromosomes. In one case, with anti-σ-φ serum, we have identified a highly conserved, very high molecular weight NHC protein (or class of proteins) which appears to interact strongly with all chromatin in a manner which is not DNA sequence-specific. In the second case, with anti-ϱ serum, we have identified an NHC protein which may have evolved an additional function(s) in Sciara relative to its function(s) in Drosophila.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 54 (1994), S. 281-288 
    ISSN: 0730-2312
    Schlagwort(e): c-myc promoter ; CAT expression ; low frequency electric ; EM fields ; transcription ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: The level of c-myc transcripts is increased in cells exposed to extremely low frequency (elf) electromagnetic (EM) fields at 60 Hz. The aim of the present experiments was to determine if regulatory regions upstream of the c-myc gene modulate the response to EM fields. DNA upstream of P1 of both mouse and human c-myc genes was transfected into cells as CAT constructs. The presence of DNA 5′ to the human or mouse myc genes results in increased expression of CAT following 20 min exposures of cells to 60 Hz elf EM fields. Specific portions of the human upstream DNA were deleted and introduced into cells. The region responsive to EM fields is located between -353 and -1,257 relative to the P1 promoter.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 66 (1997), S. 482-488 
    ISSN: 0730-2312
    Schlagwort(e): cellular stress ; heat shock element (HSE) ; heat shock factor (HSF) ; electrophoretic mobility shift assay (EMSA) ; electromagnetic (EM) field ; heat shock protein (hsp) ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Stimulation of human promyelocytic HL60 cells by a 60Hz magnetic field at normal growth temperatures results in heat shock factor 1 activation and heat shock element binding, a sequence of events that mediates the stress-induced transcription of the stress gene HSP70 and increased synthesis of the stress response protein hsp70kD. Thus, the events mediating the electromagnetic field-stimulated stress response appear to be similar to those reported for other physiological stresses (e.g., hyperthermia, heavy metals, oxidative stress) and could well be the general mechanism of interaction of electromagnetic fields with cells. J. Cell. Biochem. 66:482-488, 1997. © 1997 Wiley-Liss, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 70 (1998), S. 297-303 
    ISSN: 0730-2312
    Schlagwort(e): magnetic fields ; heat shock ; HSP70 gene expression ; protein binding sites ; nucleotide sequences ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: The mechanisms involved in sensing, signaling, and coordinating changes resulting from magnetic field-induced stress show substantial similarities to those of heat shock, e.g., magnetic field-induced heat shock 70 gene (HSP70) expression involves heat shock factor (HSF) activation and heat shock element binding. However, an additional requirement for transactivation of HSP70 expression by magnetic fields is the binding of Myc protein, indicating that additional elements and/or pathways are involved in the induction of HSP70 expression by magnetic fields. To investigate the possible participation of additional genetic elements in magnetic field-induced HSP70 expression, we examined both magnetic field exposure and heat shock on protein-DNA binding of the transcription factors HSF, AP-1, AP-2, and SP-1 in four human cell lines. The binding sites for these transcription factors are present in the HSP70 promoter. AP-1 binding activity, normally not increased by heat shock, was increased by magnetic fields; heat shock induced an increase only in HSF binding. Although intersecting and converging signaling pathways could account for the multiplicity of elements involved in magnetic field-induced HSP70 transcription, direct interaction of magnetic fields with DNA is also a possible mechanism. Because magnetic fields penetrate the cell, they could well react with conducting electrons present in the stacked bases of the DNA. J. Cell. Biochem. 70:297-303, 1998. © 1998 Wiley-Liss, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 71 (1998), S. 577-583 
    ISSN: 0730-2312
    Schlagwort(e): hsp70 ; translation ; heat shock proteins ; stress response ; restimulation ; feedback inhibition ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: To develop an alternative to hyperthermia for the induction of hsp70 for presurgical cytoprotection, we investigated the optimal exposure conditions for magnetic field induction of hsp70. Normal human breast cells (HTB124) were exposed to 60-Hz magnetic fields and hsp70 levels were measured following three different exposure conditions: continuous exposure up to 3 h, a single 20-min exposure, and a single 20-min exposure followed by repeated 20-min exposures at different field strengths. In cells exposed continuously for 3 h, hsp70 levels peaked (46%) within 20 min and returned to control levels by 2 h. Following a single 20-min exposure, the return of hsp70 levels to control values extended to more than 3 h. When cells underwent a 20-min exposure followed by repeated 20-min exposures (restimulation) with different field strengths, additional increases in hsp70 levels were induced: 31% at 1 h, 41% at 2 h, and 30% at 3 h. J. Cell. Biochem. 71:577-583, 1998. © 1998 Wiley-Liss, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 15 (1994), S. 329-336 
    ISSN: 0197-8462
    Schlagwort(e): transcription ; translation ; SV-40 ; large T-antigen ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: In its integrated form, SV-40 DNA offers an opportunity to observe the behavior of what is in effect a viral genome within a cellular genome, with transcriptional and translational products that can be clearly distinguished from those of the host cell. Exposure of SV40-transformed human fibroblasts to a 60 Hz continuous-wave sinusoidal electromagnetic (EM) field resulted in increased levels of virally derived mRNA and protein of large T-antigen. These findings provide evidence that a foreign DNA integrated into cells can be affected by EM fields under conditions known to cause increased transcripts from endogenous cellular genes. © 1994 Wiley-Liss, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 18 (1997), S. 111-115 
    ISSN: 0197-8462
    Schlagwort(e): signal transduction ; transcription ; biosynthesis ; Na,K-ATPase ; mobile charges ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: The mechanisms whereby electromagnetic (EM) fields stimulate changes in biosynthesis in cells are not known. It has generally been assumed that EM fields first interact with cell membranes, but this pathway may not be the only one. Interactions with membranes are well documented, but recent studies of EM signal transduction in the membrane Na,K-ATPase are best explained by direct interaction of electric and magnetic fields with mobile charges within the enzyme. Interaction with moving charges may be a mechanism that is operative in other biopolymers. Recent studies on DNA have shown that large electron flows are possible within the stacked base pairs of the double helix. Therefore, gene activation by magnetic fields could be due to direct interaction with moving electrons within DNA. Electric fields as well as magnetic fields stimulate transcription, and both fields could interact with DNA directly. The mechanism of EM field-stimulated transcription may be related to the process in striated muscles, where endogenous electrical activity induces the synthesis of new proteins. Bioelectromagnetics 18:111-115, 1997. © 1997 Wiley-Liss, Inc.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 8 (1987), S. 1-7 
    ISSN: 0197-8462
    Schlagwort(e): magnetic fields ; transcriptional increases ; polytene chromosomes ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: We previously demonstrated that exposure of salivary gland cells of the dipteran, Sciara coprophila, to either asymmetrical or symmetrical changing magnetic fields results in an increase in the incorporation of radioactive uridine into RNA. The present report is an analysis of the grain count distribution over the X chromosome of Sciara in transcription autoradiograms following exposure of the salivary gland cells to two pulsed magnetic signals and a 72-Hz sine wave signal. The results show augmented uptake of 3H-uridine into nascent RNA chains following short exposures of the cells to magnetic fields. Transcription is augmented in previously active loci, as well as at chromosome regions that are not detectable as active in control cells. The quantitative pattern of RNA synthesis in transcription autoradiograms is hypothesized to be signal specific on the basis of differences in grain counts over significantly labelled chromosome sites.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 11 (1990), S. 297-312 
    ISSN: 0197-8462
    Schlagwort(e): ELF fields ; transient response ; chemical-reaction model ; rate constant ; RNA synthesis ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: The exposure of cells to relatively low-intensity, pulsed, low-frequency electromagnetic fields can result in a transient augmentation of mRNA synthesis. Under certain conditions of irradiation, the augmentation is a function of the strength of the electromagnetic field. A linear, multi-step, chemical-reaction model accounts for many of the principal features that are observed in both the time- and intensity-dependent variations of transcriptional effects. The crucial assumption in the model is that the direct effect of electromagnetic fields on exposed cells is an increase in the rate constant that characterizes one of the intermediate sequential reactions in the synthesis of mRNA.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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