We discuss a wide range of applications of electric fields in biology and medicine. For example, physiological strength (<500 V/m) fields are used to improve the healing of wounds, the stimulation of neurons, and the positioning and activation of cells on scaffolds for tissue engineering purposes. The brief, strong pulses used in electroporation are used to improve the insertion of drugs into tumors and DNA into cell nuclei. The references direct readers to detailed reviews of these applications. The mechanism by which cells detect physiological strength fields is not well understood. We also describe a fieldtransduction mechanism that shares features common to the detection of fluid shear by cells. We then provide some experimental evidence that supports our model.
In preparation for blastocyst implantation, uterine luminal epithelial cells express new cell adhesion molecules on their apical plasma membrane. Since one mechanism epithelial cells employ to regulate membrane polarity is the establishment of specific membrane-cytoskeletal interactions, this study was undertaken to determine if new cytokeratin (CK) intermediate filament assemblies are expressed in endometrial epithelial cells during developmental stages related to blastocyst implantation. Type-specific CK antibodies were used for immunocytochemical and immunoblot analyses of 1) intermediate filament networks of the endometrial epithelium during embryo implantation in rabbits and 2) proliferative and secretory phases of the human menstrual cycle. CK18, a type I CK found in most simple epithelia, was expressed in all luminal and glandular epithelial cells of both the human and rabbit endometrium at all developmental stages analyzed; it was also strongly expressed in trophectoderm of the implanting rabbit blastocyst. In contrast, CK13, another type I cytokeratin, exhibited a regulated expression pattern in luminal, but not glandular, epithelial cells of secretory phase human and peri-implantation stage rabbit endometrium. Furthermore, in the rabbit implantation chambers, CK13 was predominantly localized at the cell apex of luminal epithelial cells, where it assembled into a dense filamentous network. These data suggest that the stage-specific expression of CK13 and a reorganization of the apical intermediate filament cytoskeleton of uterine luminal epithelial cells may play important functions in preparation for the implantation process.
The application of physiological strength electric fields may produce a wide range of effects on cells. The mechanisms by which cells detect the presence of these fields, however, are not fully understood. Previous experiments have shown that directionality of cells in the field is governed by an electromechanical mechanism in which the field exerts a torque on the negatively charged, inner glycocalyx that is then transmitted as a force on the cytoskeleton. This mechanism is similar to that by which cells detect fluid shear forces. Several authors, however, have reported that cell directionality and motility behave differently in an electric field. We propose here a second electromechanical mechanism in which the field bends the negatively charged, outer glycocalyx in proximity to the substrate, increasing cell adhesion and, thus, cell motility. The increase in motility depends not only on the field strength, but also on the adhesion of the cell to the substrate prior to application of the field. We show that these mechanisms are common to both human cells and amoebae and, hence, are evolutionarily conserved. Furthermore, the mechanism for detection of electric fields is simply an extension of the mechanism for detecting fluid shears. Bioelectromagnetics. 38:482-493, 2017. © 2017 Wiley Periodicals, Inc.
A comparative study of the Falck-Hillarp Technique, a modification of Eaton-Fedde procedure and silver staining of aldehyde-fixed tissue was carried out to determine the most efficient procedure to demonstrate neuroendocrine cells of the hamster and rat lung. The modified EatonFedde procedure is the most efficient method of observing these cells, and is also the easiest to perform. With this method, the normal hamster lung contains a total of 2 00x 10-1 to 30Ox 10-1 neuroendocrine cells/mm in the small and large bronchioles. In the larger airways approximately 3 51 x 10-1 neuroepithelial bodies (NEB)/mm are observed. Immediately after 24-hour exposure to NO2 the number of APUD cells dropped to approximately 25% of the control levels. These cells were decreased to 50 % of the control levels throughout the 28 days of exposure. The number of NEB decreased transiently after 24 hours of NO2 but returned to normal numbers by day 14. We recommend the application of fluorescence techniques coupled with standardised sections and quantitative methods of study for analysis of APUD cells and NEB.In 1949, Frohlich' described a unique cell type in the lung epithelium which had clear cytoplasm and was given the descriptive name Helle-Zellen.
Confronting cisternae (CC) are described for the first time in normal fetal rat and mouse liver and intestinal epithelial cells. In these cells, CC characteristically consist of 2 parallel cisternae which are devoid of ribosomes on their juxtaposed surfaces. The intracisternal spacing is consistently 20 nm. While CC occur in rapidly proliferating tissues such as fetal liver and intestinal epithelium, they do not occur in hepatocytes following partial hepatectomy. Although it has been postulated that the intact CC profiles represent a mechanism of assuring the presence of pre-formed nuclear envelope (NE) or rough endoplasmic reticulum (RER) in cells, it is more likely that the subunits which result from CC degradation serve as a pool of membrane precursors for new NE or RER.
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