摘要:

AbstractA unique tension response can be obtained by stimulating an isometrically held skeletal muscle or a single muscle fiber by a train of high‐frequency pulses (2,000 pps) at higher‐than‐normal intensity, or by a long DC pulse. It is called the tetanoid response, and it is composed of three well‐defined stages. Initially, tension develops rapidly, and mechanical output (P0) reaches about 0.35. Subsequently, this tension is maintained at a nearly steady level for the remainder of stimulation. After stimulation, a final increase of tension takes place.Intracellular electrical recordings show that the initial development of tension is elicited by two or three action potentials generated at the beginning of the stimulation, and that no additional action potentials are generated for the remainder of stimulation. During stimulation, part of the fiber membrane (regarded in cross‐section) is depolarized, which generates tension, and part of the membrane is hyperpolarized. With termination of stimulation, a single action potential is elicited via anode‐break excitation (ABE) on the hyperpolarized portion of the membrane, which gives rise to the final increase

ISSN:0197-8462    

DOI:10.1002/bem.2250100402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractTo clarify the potential of non‐ionizing electromagnetic radiation to cause biological effects by athermal mechanisms, and to initiate elucidation of those mechanisms, a model system amenable to scrutiny at the molecular level has been designed and characterized. Assessment of β‐galactosidase activity inE. coliJM101 containing the plasmid pUC8 provides a sensitive assay with many important advantages. The ability to examine at the molecular level each of the processes involved in producing β‐galactosidase should permit elucidation of the molecular mechanism(s) that give rises to an observed

ISSN:0197-8462    

DOI:10.1002/bem.2250100403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractEffects produced by electromagnetic fields from exoatmospheric nuclear detonations, known as electromagnetic pulses (EMPs) and devices, which simulate these EMPs are analyzed for their potential danger to human beings in contact with large energy collectors. Comparison is made with ANSI guidelines established for radio‐frequency electromagnetic field

ISSN:0197-8462    

DOI:10.1002/bem.2250100404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractMouse spermatozoa were exposed in vitro for 1 h to 27‐ or 2,450‐MHz CW RF radiation at SARs of 0 to 90 W/kg under isothermal (37 ± 0.2 °C) conditions. Exposure at either frequency to RF radiation at SARs of 50 W/kg or greater resulted in a statistically significant reduction in the ability of irradiated sperm to fertilize mouse ova in vitro (P<.05). Over the range of SARs there was no apparent difference in the effects of 27‐ vs. 2,450‐MHz RF radiation. There were no readily detectable exposure effects on spermatozoan morphology, ultrastructure, or capacitation. The reduction of in vitro fertilization is attributed to a direct effect of RF radiation on spermatozoa rather than t

ISSN:0197-8462    

DOI:10.1002/bem.2250100405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractUniform electrical fields have been applied to human gingival fibroblasts by means of uniform ionic currents passed through a thin chamber. Cells were observed to align in fields between 0.1 and 1.5 V/mm but did not display directed motion toward the anode or the cathode of the chamber. Statistical analysis of directional data was used to distinguish threshold levels of orientation at low field intensities, to quantify the dependence of alignment on time and field intensity, and to analyze differences between alignment of cells treated with the Ca2+transport modifiers A23187, verapamil, and lanthanum. Alignment occurred at a steady rate and was dependent in a saturating fashion on field strength. The Ca2+ionophore A23187 had a significant inhibitory effect on cell alignment in applied electrical fields; however, the Ca2+channel blockers lanthanum and verapamil did not have a significant effect on alignment.

ISSN:0197-8462    

DOI:10.1002/bem.2250100406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractMature female rats and their subsequent litters were exposed either to 112‐ or to 150‐kV/m, 60‐Hz electric fields or sham‐exposed for 19 h daily through pre‐breeding, breeding, and rearing periods of experimentation. Exposed females mated in equal percentages and reared litters of equal numbers, and mean body masses of pups were the same as those of sham‐exposed animals. Thus, experiments to investigate electric‐field effects on reproduction and development in rats are feasible at effective field strengths of 112

ISSN:0197-8462    

DOI:10.1002/bem.2250100407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

ISSN:0197-8462    

DOI:10.1002/bem.2250100401

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY