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.

Effects of Sulforaphane on the Proliferation and Apoptosis of Human Renal Tubular Epithelial Cells Induced by High Glucose and Its Mechanism / 中国药房

OBJECTIVE：To study the effects of sulforaphane on the prolifera tion and apoptosis of human renal tubular epithelial cells HK- 2 induced by high glucose ，and to investigate its mechanism primarily. METHODS ：HK-2 cells were divided into normal group ，high glucose group ，irbesartan group （positive control ，1 μmol/L），sulforaphane low ，medium and high concentration groups （10，20，40 μmol/L）. The cells in normal group were cultured in DMEM medium for 96 hours. T he cells in other groups were cultured in high glucose DMEM medium （containing 40 mmol/L glucose ）for 48 hours. After inducing cell injury，the cells were added with corresponding drugs for 48 hours. Survival rate and apoptotic rate of cells were detected. mRNA expression of cyclin D 1，caspase-3，Bcl-2 and Bax as well as protein expression of p-mTOR ，p-AMPK，p-Akt and p-PI 3K were also determined. In addition ，HK-2 cells were divided into normal group ，high glucose group ，sulforaphane high concentration group（40 μmol/L），acardicin group （AMPK agonist ，1 mmol/L），sulforaphane high concentration+compound C group （sulforaphane 40 μmol/L+AMPK inhibitor compound C 40 μmol/L），perifoxine group （Akt inhibitor ，19.95 μmol/L）、sulforaphane high concentration+SC 79 group（sulforaphane 40 μmol/L+Akt agonist SC79 4 μmol/L）. After cultured with the same method ， protein expression of p-mTOR ，p-AMPK，p-Akt and p-PI 3K were detected in HK- 2 cells. RESULTS ：Compared with normal group，survival rate of HK- 2 cells，mRNA expression of cyclin D 1 and Bcl- 2 as well as protein expression of p-AMPK were decreased significantly in high glucose group （P＜0.05）；apoptotic rate ，mRNA expression of caspase- 3 and Bax ，protein expression of p-mTOR ，p-Akt and p-PI 3K in HK- 2 cells were increased significantly （P＜0.05）. Compared with high glucose group，above indexes of sulforaphane low ，medium and high concentration groups ，irbesartan group were all improved significantly （P＜0.05）；the improvement of above indexes in sulforaphane medium and high concentration groups were significantly better those of sulforaphane low concentration group （P＜0.05）. There was no significant difference in above indexes between sulforaphane high concentration group and irbesartan group （P＞0.05）. Compared with sulforaphane high concentration group，there were no significant difference in the protein expression of p-AMPK ，p-mTOR in acardicin group and p-mTOR ，p-Akt and p-PI 3K in perifoxine group （P＞0.05）；the protein expression of p-AMPK in sulforaphane high concentration+compound C group was decreased significantly （P＜0.05），while the protein expression of p-mTOR was increased significantly （P＜0.05）；the protein expression of p-mTOR 、p-Akt、p-PI3K in sulforaphane high concentration+SC 79 group were increased significantly （P＜ 0.05）. CONCLUSIONS ：Sulforaphane can promote the proliferation of renal tubular epithelial cells and inhibit its apoptosis ；its mechanism may be associated with up-regulating the expression of p-AMPK and down-regulating the expression of p-mTOR ，p-Akt and p-PI 3K.

Cichoric acid from extracted Echinacea purpurea induces the proliferation and apoptosis of peripheral blood mononuclear cells from yaks

BACKGROUND: Cichoric acid (CA) is extracted from Echinacea purpurea. It is well known and widely used for its immunological function. However, the effect of CA on peripheral blood mononuclear cells (PBMCs) from yaks is still unclear. This study investigated the potential influences of CA on the proliferation, cytokine induction, and apoptosis of PBMCs from Datong yak in vivo, and aimed to provide a basis for exploring the pharmacological activities of CA on yaks. RESULTS: In this study, CA promoted PBMCs proliferation by combining concanavalin A (Con A) and exhibited a dose-dependent effect as demonstrated by a Cell Counting Kit-8. The concentration of 60 µg/ml CA was the best and promoted the transformation from the G0/G1 phase to the S and G2/M phases with Con A. Furthermore, 60 µg/ml CA significantly increased IL-2, IL-6, and IFN-γ levels and PCNA, CDK4 and Bcl-2 expression levels, but it significantly inhibited the TP53, Bax, and Caspase-3 expression levels. Transcriptome analysis revealed a total of 6807 differentially expressed genes (DEGs) between the CA treatment and control groups. Of these genes, 3788 were significantly upregulated and 3019 were downregulated. Gene Ontology and pathway analysis revealed that DEGs were enriched in cell proliferation and immune function signaling pathways. The expression level of some transcription factors (BTB, Ras, RRM_1, and zf-C2H2) and genes (CCNF, CCND1, and CDK4) related to PBMCs proliferation in yaks were significantly promoted after CA treatment. By contrast, anti-proliferation-associated genes (TP53 and CDKN1A) were inhibited. CONCLUSIONS: In summary, CA could regulate the immune function of yaks by promoting proliferation and inhibiting inflammation and apoptosis of PBMCs.

Analysis of the population structure and genetic diversity of the red swamp crayfish (Procambarus clarkii) in China using SSR markers

BACKGROUND: Procambarus clarkii produces high-quality, delicious meat that is high in protein, low in fat, and rich in calcium and phosphorus. It has become an important aquatic resource in China. Our objectives are (i) to analyze the level of genetic diversity of P. clarkii populations; (ii) to explore the genetic differentiation (Gst); and (iii) to propose appropriate strategies for the conservation. RESULTS: In this study, Shannon's index (I) and Nei's gene diversity index (H) for P. clarkii were high (I = 0.3462 and H = 0.2325 on average and I = 0.6264, H = 0.4377 at the species level) based on the SSR markers. The expected heterozygosity value of 17 microsatellite loci in 25 crayfish populations was 0.9317, the observed heterozygosity value was 0.9121, and the observed number of alleles per locus was 2.000; and the effective number of alleles per locus was 1.8075. Among the P. clarkii populations, the inbreeding coefficient within populations (Fis) was 0.2315, overall inbreeding coefficient (Fit) was 0.4438, genetic differentiation coefficient among populations (Fst) was 0.3145 and gene differentiation (Gst) was 0.4785 based on SSR analyses. The cluster analysis results obtained by unweighted pair-group method with arithmetic mean (UPGMA) analysis, principal coordinate analysis (PCoA) and STRUCTURE analysis were similar. A mantel test showed that the isolation-by-distance pattern was not significant. CONCLUSIONS: The high Gst among P. clarkii populations is attributed to genetic drift and geographic isolation. The results indicated that more P. clarkii populations should be collected when formulating conservation and aquaculture strategies.