Study of nonlinear viscoelastic mechanical properties of degenerated intervertebral discs / Estudio de las propiedades mecánicas viscoelásticas no lineales de discos intervertebrales degenerados

SUMMARY: Biomechanical factors are important factors in inducing intervertebral disc degeneration, in this paper, the nonlinear viscoelastic mechanical properties of degenerated intervertebral discs were analyzed experimentally. Firstly, the loading and unloading curves of intervertebral discs before and after degeneration at different strain rates were compared to analyze the changes of their apparent viscoelastic mechanical properties; The internal stress/strain distribution of the disc before and after degeneration was then tested by combining digital image technology and fiber grating technology. The results show that the intervertebral disc is strain-rate- dependent whether before or after degeneration; The modulus of elasticity and peak stress of the degenerated disc are significantly reduced, with the modulus of elasticity dropping to 50 % of the normal value and the peak stress decreasing by about 55 %; Degeneration will not change the distribution of the overall internal displacement of the intervertebral disc, but has a greater impact on the superficial and middle AF; The stress in the center of the nucleus pulposus decreases, and the stress in the outer AF increases after degeneration. Degeneration has a great impact on the nonlinear viscoelastic mechanical properties of intervertebral disc, which has reference value for the mechanism, treatment and prevention of clinical degenerative diseases.

RESUMEN: Los factores biomecánicos son importantes en la inducción de la degeneración del disco intervertebral. En este estudio se analizaron experimentalmente las propiedades mecánicas viscoelásticas no lineales de los discos intervertebrales degenerados. En primer lugar se compararon las curvas de carga y descarga de los discos intervertebrales, antes y después de la degeneración, a diferentes velocidades de deformación para analizar los cambios aparentes de sus propiedades mecánicas viscoelásticas. La distribución interna de tensión/deformación del disco antes y después de la degeneración se probó luego combinando tecnología de imagen digital y tecnología de rejilla de fibra. Los resultados mostraron que el disco intervertebral depende de la velocidad de deformación antes o después de la degeneración; El módulo de elasticidad y la tensión máxima del disco degenerado se reducen significativamente, cayendo el módulo de elasticidad al 50 % del valor normal y la tensión máxima disminuyendo en aproximadamente un 55 %; La degeneración no cambiará la distribución del desplazamiento interno general del disco intervertebral, pero tiene un mayor impacto en la FA superficial y media; El estrés en el centro del núcleo pulposo disminuye y el estrés en el FA externo aumenta después de la degeneración. La degeneración tiene un gran impacto en las propiedades mecánicas viscoelásticas no lineales del disco intervertebral, que tiene valor de referencia para el mecanismo, tratamiento y prevención de enfermedades clínicas degenerativas.

Deeper Understanding the Pathogenesis of Osteoarthritis from Matrix Viscoelasticity and Calcium Signaling / 医用生物力学

Generally, extracellular matrix (ECM) has the characteristics of viscoelasticity. In osteoarthritis (OA), catabolic processes alter the viscoelastic properties of functional pericellular matrix (PCM) of chondrocytes. Chondrocytes sense and respond to their mechanical microenvironment via an array of mechanosensitive receptors and channels that activate a complex network of downstream signaling pathways to regulate several cell processes central to OA pathology. Advances in understanding the specific mechanosignalling mechanisms in articular cartilage will promote the development of cell microenvironment construction in cartilage tissue engineering and the targeted precision therapeutics for OA. In this review, the work on the mechanism of matrix viscoelasticity regulating chondrocytes mechanotransduction by Agarwal et al. was briefly commented, and the recent advances related with their work was also discussed.

Biomechanical Modeling of Tissues at Relaxation Stage Based on Neural Network / 医用生物力学

Objective Taking pig kidney as an example, through a series of comparative and analogical experiments, the influencing factors of compressive stress at relaxation stage of biological tissues were analyzed, and a more accurate and widely applicable biomechanical model at relaxation stage was established. Methods The compressive stress relaxation experiments of pig kidney under different conditions were carried out by using the self-built mechanical experiment platform. The collected data were analyzed and mapped, and various factors affecting the relaxation force changes were summarized. Based on the conclusion, the neural network learning algorithm was used to model the force change process at relaxation stage of pig kidney. Results The pre-extrusion pressure and relaxation time were the main influencing factors for compressive stress changes of biological tissues at relaxation stage. The average error of test sample validation experiment was 6.4 mN, and the average prediction error of generalization sample validation experiment was 34.9 mN, so the modeling effect was good. Conclusions Neural network modeling algorithm has the advantages of strong generalization ability and good fault tolerance, which contributes to providing more realistic force tactile feedback prediction for virtual surgery system. It is also a new idea for mechanical modeling of nonlinear biological tissues.

Hardness Properties of Pig Esophageal at Nanoscale Using Atomic Force Microscope / 医用生物力学

Objective To study the hardness properties of pig esophageal at the nanoscale using atomic force microscope (AFM). Methods The porcine esophagus was chosen as experimental sample to study the hardness properties of esophageal tissues at different loading rates, deflection and dwell time with AFM. Results The hardness of esophageal tissues at the nanoscale was strongly correlated with the loading rate and the deflection, which increased with the increasing loading rate and decreased with the increasing deflection of cantilever. The difference in the hardness was associated with the viscoelasticity and viscoplasticity of esophageal tissues, including contact stress, energy transition and strain plastic gradient. Conclusions The experimental results have important significance for clinical diagnosis, surgical operation and artificial material development, and reveal the changing patterns for mechanical properties of the esophageal tissues at the microscale.

Stress relaxation and creep test of modified glass ionomer cement / 中国组织工程研究

BACKGROUND: Most of studies on the mechanical properties of modified glass ionomer cement mainly focus on the compression and bending experiments, but there are few reports on the stress relaxation and creep experiments of glass ionomer cement after adding strontium hydroxyapatite. OBJECTIVE: To compare the stress relaxation and creep characteristics of traditional glass ionomer cement, composite resin enamel adhesive and modified glass ionomer cement. METHODS: Strontium doped hydroxyapatite was added into glass ionomer cement according to the mass ratio of 15%, and then the modified glass ionomer cement was prepared. Samples of modified glass ionomer cement, composite resin enamel adhesive and traditional glass ionomer cement were maded. Ten samples from each group were taken for stress relaxation test and another 10 samples for creep test. RESULTS AND CONCLUSION: (1) At 7 200 s in the stress relaxation test, the stress in the traditional group was decreased by 1.18 MPa, decreased by 1.39 MPa in the composite group, and decreased by 1.38 MPa in the modified group. The decreased value in the traditional group was significantly less than that in the composite and modified groups (P 0.05). (2) At 7 200 s in the creep test, the stress in the traditional group was increased by 0.24%, increased by 0.33% in the composite group, and increased by 0.32% in the modified group. The increased value in the traditional group was significantly less than that in the composite and modified groups (P 0.05). (3) The viscoelastic properties of glass ionomer cement are improved by compounding 15% strontium-doped hydroxyapatite with glass ionomer cement. The increase of viscoelasticity is beneficial to the adhesion and bulk bond strength of glass ionomer cement.

Development and Application of Non-invasive Real-time Detection System for Viscoelasticity of Skin Tissue / 中国医疗器械杂志

To satisfy the daily demand of skin condition maintenance, make non-invasive real-time detection, and get proper quantitative evaluation of skin viscoelasticity parameters at the same time, a portable non-invasive detection system to acquire real-time skin tissue viscoelasticity is developed. The system relies mainly on a single-degree-of-freedom forced vibration model, with spring-damp-mass, and on dynamic micro indentation method. The experiment is conducted on two kinds of springs, and on pigskin tissues as well, the system's suitability, accuracy and stability are confirmed. The skin viscoelasticity detection in vivo is also carried out on 20 subjects with different ages, the differences of skin viscoelasticity in various parts of the body are investigated, and the correlations between age and skin viscoelasticity are clarified.

Preliminary study on correlation between carotid viscoelasticity and blood flow shear rate / 上海交通大学学报（医学版）

Objective • To examine the carotid viscoelasticity by using ultrasonic shear wave dispersion (USWD) technique, and to preliminarily analyze its correlation with blood flow shear rate. Methods • Forty-five patients of General Surgery Department of Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine from December 2018 to January 2019 were recruited, and divided into the elder group (≥ 50 years old) and the younger group (<50 years old) according to the median age. The carotid viscoelasticity of the patients was examined by USWD technique and the indexes were obtained, including carotid shear wave elasticity (SWER), shear wave dispersion (SWDR), blood flow maximum shear rate (SRmax) and mean shear rate (SRmean). The correlations between SWER, SWDR and blood flow shear rate were analyzed by Pearson correlation, respectively. Results • ① Compared with the younger group, the carotid artery SWER, SWDR, SRmax and SRmean of the patients in the elder group were lower (all P<0.05). ② The SWER and SWDR of carotid artery of all patients were positively correlated with SRmax and SRmean, respectively (all P<0.05). Conclusion • Carotid arterial viscoelastic index based on USWD technique is closely related to the blood flow shear rate, which is expected to provide a new perspective for the study of carotid arterial diseases.

Correlation between carotid viscoelasticity and hemodynamics based on ultrasound shear wave dispersion imaging / 第二军医大学学报

Objective: To measure the carotid viscoelasticity using ultrasound shear wave dispersion (USWD), and to explore the correlation between the viscoelasticity and hemodynamics. Methods: Forty-fve volunteers without history of cardiovascular and cerebrovascular events were recruited and divided into elder group (≥50 years old, n=23) and younger group (<50 years old, n = 22) according to the median age. The common carotid arteries were detected by USWD, and SWER (elastic index) and SWDR (viscous index) were obtained. Hemodynamic parameters, including velocity time integral (VTI), peak systolic velocity (PSV), end-diastolic velocity (EDV), and mean flow velocity (MFV), were measured using Doppler ultrasound. Correlations between SWER, SWDR and hemodynamic parameters were analyzed using Pearson analysis. Results: The SWER, SWDR, VTI, PSV, EDV and MFV in the elder group were significantly lower than those in the younger group (P<0.05, P<0.01). The SWER was positively correlated with VTI, PSV, EDV and MFV (r=0.354, 0.400, 0.467 and 0.310; P<0.01, P<0.05). The SWDR was negatively correlated with VTI and PSV (r= - 0.481 and - 0.522, both P<0.01), but positively correlated with MFV (r=0.352, P<0.01). Conclusion: USWD may identify the change of carotid viscoelasticity, and the change of viscoelasticity is related to hemodynamics.

Assessment of elasticity and viscosity in the human carotid artery using ultrasound shear wave dispersion imaging: a comparison study / 中华超声影像学杂志

Objective@#To detect the viscoelasticity of carotid artery in healthy volunteers using ultrasonic shear wave dispersion (SWD) technique, and explore the feasibility and influencing factors for SWD parameters.@*Methods@#Forty-five healthy volunteers were recruited and divided into elder group (≥50 years old) and younger group (<50 years old) according to the age. The carotid arteries were examined by SWD at systole, axial elastic modulus (SWER) and viscous index (SWDR) were obtained. The pulse wave velocity (PWV), a carotid artery circumferential elastic parameter was obtained and considered as the reference indicator. The difference of SWER, SWDR and PWV were compared between two groups; and the correlation between them were analyzed by Pearson analysis, respectively.@*Results@#①Compared with the younger group, the carotid PWV increased, while SWER and SWDR decreased in the elder group(all P<0.05). ②In all subjects, SWER was negatively correlated with PWV (r=-0.256, P<0.05). In the elder group, SWER was negatively correlated with systolic blood pressure (r=-0.357, P<0.05), and SWDR was negatively correlated with PWV (r=-0.393, P<0.05). In the younger group, SWDR was positively correlated with systolic blood pressure (r=0.366, P<0.05).@*Conclusions@#Compared with the elder group, the carotid viscoelasticity was higher in young people, and it is correlated with PWV. SWD can evaluate carotid viscoelasticity, and contribute to better understanding of its tissue characteristics.

Assessment of elasticity and viscosity in the human carotid artery using ultrasound shear wave dispersion imaging :a comparison study / 中华超声影像学杂志

Objective To detect the viscoelasticity of carotid artery in healthy volunteers using ultrasonic shear wave dispersion ( SWD ) technique ,and explore the feasibility and influencing factors for SWD parameters . Methods Forty‐five healthy volunteers were recruited and divided into elder group ( ≥50 years old) and younger group ( ＜50 years old) according to the age . T he carotid arteries were examined by SWD at systole ,axial elastic modulus ( SWER ) and viscous index ( SWDR ) were obtained . T he pulse wave velocity ( PWV ) ,a carotid artery circumferential elastic parameter was obtained and considered as the reference indicator . T he difference of SWE R ,SWDR and PWV were compared between two groups ; and the correlation between them were analyzed by Pearson analysis ,respectively . Results ① Compared with the younger group ,the carotid PWV increased ,w hile SWE R and SWDR decreased in the elder group ( all P ＜0 .05) . ②In all subjects ,SWER was negatively correlated with PWV ( r ＝ －0 .256 , P ＜ 0 .05 ) . In the elder group ,SWER was negatively correlated with systolic blood pressure ( r ＝ －0 .357 , P ＜ 0 .05 ) ,and SWDR was negatively correlated with PWV ( r ＝ －0 .393 , P ＜0 .05 ) . In the younger group ,SWDR was positively correlated with systolic blood pressure ( r ＝0 .366 , P ＜0 .05) . Conclusions Compared with the elder group ,the carotid viscoelasticity was higher in young people ,and it is correlated with PWV . SWD can evaluate carotid viscoelasticity ,and contribute to better understanding of its tissue characteristics .

Ultrasound shear wave dispersion imaging in evaluation of carotid viscoelasticity / 中国医学影像技术

Objective: To observe the feasibility of ultrasound shear wave dispersion imaging (USWD) in evaluating carotid viscoelasticity. Methods: Totally 45 volunteers were recruited and divided into 2 groups according to age, i.e. ≥50 years old group (n=23) and <50 years old group (n=22). Four shear wave viscoelastic modulus of the common carotid artery (CCA), including shear wave elastic modulus values of the superficial and deep walls (SWES and SWED), shear wave dispersion values of superficial and deep walls (SWDS and SWDD) were obtained using USWD, respectively. In addition, the pulse wave velocity (PWV) was measured. The viscoelastic indexes were compared between the two groups, and the correlations with age, blood pressure and PWV were analyzed. Results: Before and after adjusted with body mass index, systolic blood pressure (SBP) and diastolic blood pressure (DBP), SWES, SWED, SWDS and SWDD were higher in <50 years old group than those in ≥50 years old group (all P<0.05). Among all subjects, SWE was negatively correlated with age, SBP, DBP and PWV, respectively (r=-0.282, -0.374, -0.321, -0.256, all P<0.05). SWD was negatively correlated with PWV in ≥50 years old group (r=-0.393, P=0.038), while positively correlated with SBP in <50 years old group (r=0.366, P=0.048). Conclusion: The viscoelasticity of arterial wall can be non-invasively and quantitatively assessed with USWD.

Determination of a visco-hyperelastic material law based on dynamic tension test data / 生物医学工程学杂志

The objective of this study was to determine the visco-hyperelastic constitutive law of brain tissue under dynamic impacts. A method combined by finite element simulations and optimization algorithm was employed for the determination of material variables. Firstly, finite element simulations of brain tissue dynamic uniaxial tension, with a maximum stretch rate of 1.3 and strain rates of 30 s and 90 s , were developed referring to experimental data. Then, fitting errors between the engineering stress-strain curves predicted by simulations and experimental average curves were assigned as objective functions, and the multi-objective genetic algorithm was employed for the optimation solution. The results demonstrate that the brain tissue finite element models assigned with the novel obtained visco-hyperelastic material law could predict the brain tissue's dynamic mechanical characteristic well at different loading rates. Meanwhile, the novel material law could also be applied in the human head finite element models for the improvement of the biofidelity under dynamic impact loadings.

Viscoelastic properties of embryonic neuroepithelial cells in neural tube defects mice / 国际生物医学工程杂志

Objective To explore the role of mechanical properties of embryonic neuroepithelial cells in the process of neural tube closure.Methods Neural tube defects (NTDs) mouse model was established by intragastric administration with all-trans retinoic acid at embryo 7.25 day.All the pregnant mice were sacrificed at embryo 9.5 day and 11.5 day,respectively,and the primary neuroepithelial cells were isolated from neural tube tissue of normal and NTDs mice,respectively.The mechanical characteristics of neuroepithelial cells were analyzed using micropipette aspiration technique combined with a standard solid viscoelastic mechanical model.Results The mechanical characteristics of mouse embryonic neuroepithelial cells showed typical viscoelastic solid characteristics.Compared with the control group,the three viscoelastic parameters,i.e.equilibrium modulus,transient modulus and apparent viscosity coefficient,of the neuroepithelial cells in the NTDs group were significantly increased,and the differences were statistically significant (all P＜0.05).However,there was no significant difference in the viscoelastic parameters of the same group between embryo 9.5 d and 11.5 d (all P＞0.05).Conclusion The decrease in the deformability of embryonic neuroepithelial cells may be one of the factors responsible for neural tube closure disorders.

Numerical Study on Effects of Different Adhesive Materials for Ceramic Restoration on Stress Distributions / 医用生物力学

Objective To investigate the effect of different adhesive materials on all-ceramic restoration. Methods The all-ceramic restoration system model of mandibular first molar was established by spiral computed tomography (CT) scanning and computer-aided design (CAD) modeling. Four types of resin adhesive materials (Duo Cement,Lute-It,Rely-X ARC,Variolink II) used in clinics were selected, and the stress distribution was calculated using the ABAQUS software. Results The stress at the bonding interface was the highest when low filler adhesive Lute-It was used. Based on the viscoelasticity analysis, resin adhesives with a larger storage modulus and loss modulus could yield lower stress extremes. Conclusions The study suggests that high-filler type resin adhesives with a large energy storage modulus and loss modulus should be used clinically.

Management of freezing rate and trehalose concentration to improve frozen dough properties and bread quality

Abstract Bread is one of the most consumed foods in the world, and alternatives have been sought to extend its shell life, and freezing is one of the most popular methods. The purpose of this study was to evaluate the effect of freezing rate and trehalose concentration on the fermentative and viscoelastic properties of dough and bread quality. Dough was prepared and trehalose was added at three concentrations (0, 400, 800 ppm); dough was pre fermented and frozen at two freezing rates then stored for 42 days. Frozen dough samples were thawed every two weeks. CO2 production and elastic and viscous modulus were determined. In addition, bread was elaborated and specific volume and firmness were evaluated. High trehalose concentrations (400 and 800 ppm) produced dough with the best viscoelastic and fermentative properties. Greater bread volume and less firmness were observed when a slow freezing rate (-.14 °C/min) was employed.

An experimental study on effects of paraformaldehyde fixation on viscoelasticity of rat vertebrae / 医用生物力学

Objective To observe the effect of paraformaldehyde fixation on viscoelastic properties of the vertebrae in rats, so as to find the best methods of preserving cancellous bone samples from the perspective of biomechanics. Methods Twenty 8-week-old healthy female Sprague-Dawley rats were selected, and their whole L4 and L5 vertebra were separated by surgery. The total 40 vertebrae were randomly and evenly divided into experimental group and control group. The experimental group was fixed with 4% paraformaldehyde for 72 h, and the control group was transferred to 5 mL EP tube and cryopreserved at -20 ℃. Ten vertebrae were randomly selected from each group for stress relaxation and creep experiments. After 7 200 s, the samples were collected and their micro-structure changes were analyzed by micro-CT. Results The relaxation creep curve of experimental group was smoother than that of control group, the time to reach steady state was shorter, and the total amount of relaxation creep at 500 s and 7 200 s was significantly decreased (P<0.01). Micro-CT results showed that relaxation and creep experiment could cause trabecular rupture, and trabecular damage was more severe in experimental group than that in control group. Conclusions Paraformaldehyde significantly reduce the viscoelasticity of rat vertebrae, and it is more easily to cause microstructure damage under mechanical stimulation, which is detrimental to cancellous bone preservation.

Preparation and Rheological Property of Cross-Linked Sodium Hyaluronate Gel / 中国药学杂志

OBJECTIVE: To prepare crossed-linked sodium hyaluronate (CHA) gel and study its rheological property. METHODS: CHA was prepared using 1, 4-butanediol diglycidyl ether (BDDE). The linear viscoelastic properties and creep recovery of hyalouronan(HA) and CHA were measured with a rheometer. The influencing factors of rheological properties were analyzed, such as concentration, proportion of cross-linker and temperature. RESULTS: Cross-linked sodium hyaluronate gel was prepared. The viscoelasticity was measured with a pair of 20 mm stainless steel plates at the frequency of 1 Hz and shear-strain of 1 Pa at (25±0.1)℃. As shown by the creep recovery test, CHA had a smaller strain and shorter time to recover to the minimum strain than HA, which showed typical linear viscoelastic and creep recovery properties. CONCLUSION: CHA is a non-Newtonian fluid, which is easy to administer and conforms completely to the requirements for viscoelastic supplementation materials for intra-articular injection. Compared with HA, CHA has more advantageous viscoelastic property and stability.

Effect of isopropyl myristate on the viscoelasticity and drug release of a drug-in-adhesive transdermal patch containing blonanserinEffect of isopropyl myristate on the viscoelasticity and drug release of a drug-in-adhesive transdermal patch containing blonanserinretain-->

The purpose of this study was to investigate the effect of isopropyl myristate (IPM), a penetration enhancer, on the viscoelasticity and drug release of a drug-in-adhesive transdermal patch containing blonanserin. The patches were prepared with DURO-TAK87-2287 as a pressure-sensitive adhesive (PSA) containing 5% (/) of blonanserin and different concentrations of IPM. Anrelease experiment was performed and the adhesive performance of the drug-in-adhesive patches with different concentrations of IPM was evaluated by a rolling ball tack test and a shear-adhesion test. The glass transition temperature () and rheological parameters of the drug-in-adhesive layers were determined to study the effect of IPM on the mechanical properties of the PSA. The results of therelease experiment showed that the release rate of blonanserin increased with an increasing concentration of IPM. The rolling ball tack test and shear-adhesion test showed decreasing values with increasing IPM concentration. The results were interpreted on the basis of the IPM-induced plasticization of the PSA, as evidenced by a depression of the glass transition temperature and a decrease in the elastic modulus. In conclusion, IPM acted as a plasticizer on DURO-TAK87-2287, and it increased the release of blonanserin and affected the adhesive properties of the PSA.

A cross‑sectional study to compare intraocular pressure measurement by sequential use of Goldman applanation tonometry, dynamic contour tonometry, ocular response analyzer, and Corvis ST.

Objective: To study the correlation and effect of sequential measurement of intraocular pressure (IOP) with Goldmann applanation tonometer (GAT), ocular response analyzer (ORA), dynamic contour tonometer (DCT), and Corvis ST. Setting and Design: Observational cross‑sectional series from the comprehensive clinic of a tertiary eye care center seen during December 2012. Methods: One hundred and twenty‑five study eyes of 125 patients with normal IOP and biomechanical properties underwent IOP measurement on GAT, DCT, ORA, and Corvis ST; in four different sequences. Patients with high refractive errors, recent surgeries, glaucoma, and corneal disorders were excluded so as to rule out patients with evident altered corneal biomechanics. Statistical Analysis: Linear regression and Bland–Altman using MedCalc software. Results: Multivariate analysis of variance with repeated measures showed no influence of sequence of device use on IOP (P = 0.85). Linear regression r2 between GAT and Corvis ST, Corvis ST and Goldmann‑correlated IOP (IOPg), and DCT and Corvis ST were 0.37 (P = 0.675), 0.63 (P = 0.607), and 0.19 (P = 0.708), respectively. The Bland–Altman agreement of Corvis ST with GAT, corneal compensated IOP, and IOPg was 2 mmHg (−5.0 to + 10.3), −0.5 mmHg (−8.1 to 7.1), and 0.5 mmHg (−6.2 to 7.1), respectively. Intraclass correlation coefficient for repeatability ranged from 0.81 to 0.96. Conclusions: Correlation between Corvis ST and ORA was found to be good and not so with GAT. However, agreement between the devices was statistically insignificant, and no influence of sequence was observed.

Phosphorylation and Reorganization of Keratin Networks: Implications for Carcinogenesis and Epithelial Mesenchymal Transition

Metastasis is one of hallmarks of cancer and a major cause of cancer death. Combatting metastasis is highly challenging. To overcome these difficulties, researchers have focused on physical properties of metastatic cancer cells. Metastatic cancer cells from patients are softer than benign cancer or normal cells. Changes of viscoelasticity of cancer cells are related to the keratin network. Unexpectedly, keratin network is dynamic and regulation of keratin network is important to the metastasis of cancer. Keratin is composed of heteropolymer of type I and II. Keratin connects from the plasma membrane to nucleus. Several proteins including kinases, and protein phosphatases bind to keratin intermediate filaments. Several endogenous compounds or toxic compounds induce phosphorylation and reorganization of keratin network in cancer cells, leading to increased migration. Continuous phosphorylation of keratin results in loss of keratin, which is one of the features of epithelial mesenchymal transition (EMT). Therefore, several proteins involved in phosphorylation and reorganization of keratin also have a role in EMT. It is likely that compounds controlling phosphorylation and reorganization of keratin are potential candidates for combating EMT and metastasis.