15 male Wistar rats of 8 weeks old were used in this experment. After deeply anesthesia, the masseter muscles, digastric muscles, lateral pterygoid muscles were stimulated in the apartment that was made by us. The curves that express the relations of force-electronic stimulates were recorded and the constitutive equations of these muscles were given. When a single electronic signal stimulates the muscle, the respondence of the muscles can be expressed as F = A(e-alpha t - e-beta t) and the constant A, alpha, beta were determined. When the frequency of the electronic stimulation was higher than 3 Hz, the respondence was expressed as F = Ce-gamma/t + Dsin omega t and the constants C, D and gamma were determined. When the frequency of the electronic stimulation was thirty or higher, the tetanic convulsion occurred.
Animals ; Electric Stimulation ; Jaw ; physiology ; Male ; Masticatory Muscles ; physiology ; Muscle Contraction ; physiology ; Myography ; Rats ; Rats, Wistar ; Time Factors

Objective To express the recombinant caspid of genotype 4 hepatitis E virus(HEV) ORF2. Methods HEV recombinant capsid protein D66 was expressed in E. coli, using the ORF2 fragment (aa368-606, obtained from swine bile) of genotype 4 HEV. Results The recombinant capsid proteins D66 self-assemble to be particle with a radius of 13 nm through dimeric form in neutral solution. Coated particles reacted well with sera obtained from patients during acute or recovered phase of HEV infection. Immunofluorescence and immnoblot assay suggested that D66 bound and penetrated HepG2 cell lines, and the process of attachment was blocked by sera collected from patients during acute or recovered phase of HEV infection.Conclusion Recombinant D66 particles simulate the structure at the surface of genotype 4 HEV well and specifically adhere and penetrate the host cells, which lays the foundation for the investigation of the molecular mechanism of genotype 4 HEV infection.

To study the response of cultured cells to the cyclical biaxial biomechanical strain, a system was made according to the principle of Winston. The system was made of culture dish, pressure cavity and step motor. The culture dishes were made of polymethyl methacrylate and the bottom of the culture dishes were made of silicone rubber membrane. When the diameter of the silicone rubber tube and the distance between rollers and curvilinear plate changed, the pressure in the pressure cavity changed and the strain of the membrane changed from 0 to 4%. When the roll of the step motor changed, the frequency of the strain changed from 0.1 to 5 Hz.
Animals ; Cell Culture Techniques ; instrumentation ; Equipment Design ; Finite Element Analysis ; Rats ; Stress, Mechanical