As a major component of the epidermal tissue, a primary keratinocyte has served as an essential tool not only for the study of pathogenesis of skin-related diseases but also for the assessment of potential toxicities of various chemicals used in cosmetics. However, its short lifespan in ex vivo setting has been a great hurdle for many practical applications. Therefore, a number of immortalization attempts have been made with success to overcome this limitation. In order to understand the immortalization process of a primary keratinocyte, several key biological phenomena governing its lifespan will be reviewed first. Then, various immortalization methods for the establishment of stable keratinocyte cell lines will be explained. Finally, its application to a three-dimensional skin culture system will be described.
Aging ; Biological Phenomena ; Cell Line ; Keratinocytes* ; Skin*

OBJECTIVETo predict the impact of MF radiation on human health.

METHODSThe vertical distribution of field intensity was estimated by analogism on the basis of measured values from simulation measurement.

RESULTSA kind of analogism on the basis of geometric proportion decay pattern is put forward in the essay. It showed that with increasing of height the field intensity increased according to geometric proportion law.

CONCLUSIONThis geometric proportion prediction model can be used to estimate the impact of MF radiation on inhabited environment, and can act as a reference pattern in predicting the environmental impact level of MF radiation.

Electromagnetic Phenomena ; Environment ; Models, Biological ; Radiation

The present paper proposed a central-driven structure of upper limb rehabilitation robot in order to reduce the volume of the robotic arm in the structure, and also to reduce the influence of motor noise, radiation and other adverse factors on upper limb dysfunction patient. The forward and inverse kinematics equations have been obtained with using the Denavit-Hartenberg (D-H) parameter method. The motion simulation has been done to obtain the angle-time curve of each joint and the position-time curve of handle under setting rehabilitation path by using Solid Works software. Experimental results showed that the rationality with the central-driven structure design had been verified by the fact that the handle could move under setting rehabilitation path. The effectiveness of kinematics equations had been proved, and the error was less than 3° by comparing the angle-time curves obtained from calculation with those from motion simulation.
Biomechanical Phenomena ; Humans ; Models, Biological ; Robotics ; Stroke Rehabilitation ; Upper Extremity

A lot of experimental findings have confirmed that: Animal cells acquire a spherical shape just before the division; Under biochemical stimulus of mitotic apparatus aster the cells form a contractile ring in equator plane, and the mother cell divides into two daughter cells; meanwhile the total volume keeps constant. In Zinemanas and Nir's model the reorientation of microfilament and the visco-elasticity of cortex have been took into consideration. In our present work, the effective coefficient m due to biochemical stimulus was incorporated into the model, and the local distribution C was modified to diffuse with the plasma membrane motion. The numerical results showed that the formation of a contractile ring and parameters such as the surface tension in the furrow and internal pressure can be predicted successfully. Compared with Zinemanas and Nir's model, the results of our model are more correspondent with the experimental results. It can be concluded that the effective coefficient m has limited effects on the process control of cytokinesis.
Animals ; Biomechanical Phenomena ; Cytokinesis ; Humans ; Models, Biological ; Surface Tension

In order to understand the electricity frequency specialties of blood, we have developed a wide frequency electricity characteristic testing system and used it to test the amplitude frequency property and phase frequency property of the blood in different states and constituents at 1 Hz to 20 MHz. Further analysis on the results of tests helped us know some important properties of blood at even more microcosmic levels from a new angle. Meanwhile, some problems and considerations on the improvement of the electricity model of biotic tissue and blood were pointed out. (1) From 1 Hz to 5 KHz, the impedance of blood descended 99%. (2) Simple equivalent circuit of resistance and capacitance must be used in series equivalent but not in usual parallel connection equivalent. (3) Experiment indicated, equivalent circuits of blood need more analysis, because simple equivalent circuit of resistance and capacitance is liable to gross error. (4) When the three element model is used for measuring the resistance of inside liquid, capacitance of cell membrane and the resistance of outside liquid of blood, the three testing frequencies must be very similar.
Blood ; Blood Physiological Phenomena ; Electric Impedance ; Electrophysiology ; Humans ; Models, Biological

Lysophosphatidic acid (LPA) is a small phospholipid that is present in all eukaryotic tissues and blood plasma. As an extracellular signaling molecule, LPA mediates many cellular functions by binding to six known G protein-coupled receptors and activating their downstream signaling pathways. These functions indicate that LPA may play important roles in many biological processes that include organismal development, wound healing, and carcinogenesis. Recently, many studies have found that LPA has various biological effects in different kinds of bone cells. These findings suggest that LPA is a potent regulator of bone development and remodeling and holds promising application potential in bone tissue engineering. Here, we review the recent progress on the biological regulatory function of LPA in bone tissue cells.
Biological Phenomena ; Bone and Bones ; Lysophospholipids ; Receptors, Lysophosphatidic Acid

In order to understand biological phenomena accurately, single molecule techniques using a physical research approach to molecular interactions have been developed, and are now widely being used to study complex biological processes. In this review, we discuss some of the single molecule methods which are composed of two major parts: single molecule spectroscopy and manipulation. In particular, we explain how these techniques work and introduce the current research which uses them. Finally, we present the oral biology research using the single molecule methods.
Biological Phenomena ; Biological Processes ; Biology ; Methods ; Molecular Biology ; Optical Tweezers ; Spectrum Analysis

A biphasic porous medium model based on the mixture theory in continuum mechanics frame was used to depict the distributions of osseous stress field, distortion field and pore pressure when the bone tissue was subject to various dynamic loads. In the model, the bone tissue was considered as a transversely isotropic, liquid saturated porous material. The coupling relationship among the distortion, fluid flow and the streaming potential is studied. The Galerkin weighted residual method was used to derive the finite element formulation for dynamic response and the streaming potential calculating formulation of bone tissue, the penalty finite element formulation was obtained via introducing the ratio term of pressure p and penalty parameter beta in the continuity equation and, in turn, eliminated the pressure term in governing equation sets. The computational results show that the viscoelastic behavior and the energy dissipation property in the bone tissue, especially in the cancellous bone, is caused to a great extent by the pore liquid flow and diffusion. Meanwhile, because of the existence of electrical double layer between the solid phase and liquid phase, when the liquid constituents in the pore diffuse, the streaming potential appears, and the growth and absorption of bone tissue is expedited.
Biomechanical Phenomena ; Biophysical Phenomena ; Biophysics ; Bone and Bones ; physiology ; Elasticity ; Electrophysiology ; Finite Element Analysis ; Humans ; Models, Biological ; Porosity ; Stress, Mechanical ; Viscosity

Disorders of galactose metabolism can be fatal if not treated early. Newborn screening has made it possible to detect and treat this disease. Three cases of galactosemia, one with galactokinase deficiency and two with galactose-1-phosphate uridyltransferase deficiency detected by newborn screening, are presented. Because of early detection and management, the first patient was spared the early complications of galactosemia and continues to grow and develop normally. The two other patients were diagnosed at 1 month, initial presentation included hepatomegaly and failure to thrive. Institution of treatment was able to reverse the acute complications and both are currently doing well. The importance of galactosemia newborn screening in preventing complications resulting from the disease is emphasized.

Human ; Male ; Infant ; Infant Newborn ; Galactosemias ; Neonatal Screening ; Galactose ; Failure To Thrive ; Hepatomegaly ; Biological Phenomena ; Physiological Phenomena ; Early Diagnosis

A first order system model is proposed for simulating the influence of stress stimulation on fracture strength during fracture healing. To validate the model, the diaphyses of bilateral tibiae in 70 New Zealand rabbits were osteotomized and fixed with rigid plates and stress-relaxation plates, respectively. Stress shielding rate and ultimate bending strength of the healing bone were measured at 2 to 48 weeks postoperatively. Ratios of stress stimulation and fracture strength of the healing bone to those of intact bone were taken as the system input and output. The assumed first order system model can approximate the experimental data on fracture strength from the input of stress stimulation over time, both for the rigid plate group and the stress-relaxation plate group, with different system parameters of time constant and gain. The fitting curve indicates that the effect of mechanical stimulus occurs mainly in late stages of healing. First order system can model the stress adaptation process of fracture healing. This approach presents a simple bio-mathematical model of the relationship between stress stimulation and fracture strength, and has the potential to optimize planning of functional exercises and conduct parametric studies.
Animals ; Biomechanical Phenomena ; Fracture Healing ; physiology ; Mathematics ; Models, Animal ; Models, Biological ; Rabbits