Cell-Electrode Models for Impedance Analysis of Epithelial and Endothelial Monolayers Cultured on Microelectrodes.

Electric cell-substrate impedance sensing has been used to measure transepithelial and transendothelial impedances of cultured cell layers and extract cell parameters such as junctional resistance, cell-substrate separation, and membrane capacitance. Previously, a three-path cell-electrode model comprising two transcellular pathways and one paracellular pathway was developed for the impedance analysis of MDCK cells. By ignoring the resistances of the lateral intercellular spaces, we develop a simplified three-path model for the impedance analysis of epithelial cells and solve the model equations in a closed form. The calculated impedance values obtained from this simplified cell-electrode model at frequencies ranging from 31.25 Hz to 100 kHz agree well with the experimental data obtained from MDCK and OVCA429 cells. We also describe how the change in each model-fitting parameter influences the electrical impedance spectra of MDCK cell layers. By assuming that the junctional resistance is much smaller than the specific impedance through the lateral cell membrane, the simplified three-path model reduces to a two-path model, which can be used for the impedance analysis of endothelial cells and other disk-shaped cells with low junctional resistances. The measured impedance spectra of HUVEC and HaCaT cell monolayers nearly coincide with the impedance data calculated from the two-path model.

Endodontic apical surgery with novel endoscope: Three-case series.

Successful apical surgery relies on effective magnification and illumination. In the field of endodontics, the microscope has emerged as the predominant tool for meeting these requirements. The rigid endoscope is also a valuable instrument in apical surgery. This study introduces three cases demonstrating the application of endoscope technology in endodontic apical surgery. The first case employs a soft endoscope for treating an anterior tooth with apical periodontitis, the second integrates an endoscope with new attachments for a premolar, and the third combines an endoscope, attachments and navigation for the lower first molar surgery. It revealed that endoscopes offer certain advantages that are not achievable with microscope-assisted surgery, these cases had a great outcome. In the future, a broader application of endoscopic technology in various procedures is anticipated.

Keloid-derived, plasma/fibrin-based skin equivalents generate de novo dermal and epidermal pathology of keloid fibrosis in a mouse model.

Keloids are wounding-induced tumor-like human scars. Unclear etiology and lack of animal models to reveal disease mechanisms and invent therapies deepen the grievous health and psychosocial state of vulnerable individuals. Epitomizing the injury-repair environment which triggers and fosters keloid formation and essential dermal/epidermal interactions in disease development, the novel animal model was established by implanting porous polyethylene ring-supported plasma/fibrin-based epidermal-dermal skin constructs on the dorsum of athymic NU/J mice. The implants were stable to 18 weeks, contained abundant human cells, and remodeled to yield scar architecture characteristic of keloid fibrosis compared with normal implants and clinical specimens: (1) macroscopic convex or nodular scar morphology; (2) morphogenesis and accumulation of large collagen bundles from collagen-null initial constructs; (3) epidermal hyperplasia, aberrant epidermal-dermal patency, and features of EMT; (4) increased vasculature, macrophage influx, and aggregation; and (5) temporal-spatial increased collagen-inducing PAI-1 and its interactive partner uPAR expression. Development of such pathology in the NU/J host suggests that T-cell participation is less important at this stage than at keloid initiation. These accessible implants also healed secondary excisional wounds, enabling clinically relevant contemporaneous wounding and treatment strategies, and evaluation. The model provides a robust platform for studying keloid formation and testing knowledge-based therapies.