The final overall conversion and the individual conversions of ST and SMA all decrease with increasing SMA concentration.
Furthermore, at a particular reaction time, the individual conversion of SMA is always greater than that of ST. Monomer droplet nucleation was retarded severely for the monomer pair ST/LMA, presumably due to the very strong Ostwald ripening effect. As a result, relatively slow rates of copolymerization of ST and LMA were attained compared with the ST/SMA counterpart. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 620-628, 2011″
“Study Design. Several senescence biomarkers were observed JNJ-26481585 to investigate cell senescence in degenerative
intervertebral lumbar discs of foreleg-amputated rats.
Objective. To determine if cell senescence is accelerated in degenerative intervertebral lumbar disc cells in an upright-rat model.
Summary of Background Data. Cellular senescence was accelerated in human and sand rat degenerative intervertebral disc (IVD) cells. Repeated use of upright posture by rats contributed to degenerative disc changes. No convincing evidence of cell senescence was observed in the lumbar disc of the foreleg amputated rat.
Methods. The forelimbs of 20 rats were amputated at 1 month of age such that they maintained an upright stance; rats were housed in custom-made cages. Nonamputated rats, also 1 month of age, were INCB018424 mouse kept in regular cages and served as a control group. The lumbar IVDs were harvested from rats in 2 groups, at 5 or 9 months find more following amputation. Senescence-associated-beta-galactosidase-positive staining was used to detect cell senescence. p16INK4a and p27KIP were assessed by immunohistochemistry analysis. Total RNA isolated from these samples was used to measure the gene expression of p16INK4a, RB, cyclin D1, CDK4, PTEN, p27KIP, p19ARF, p21, TERT, and RAGE by real-time polymerase chain reaction assay.
Results. The highest levels of SA-beta-GAL activity were detected in
9-month amputated rats. Quantitative immunohistochemical analysis showed that there were highest rates of p16INK4a and p27KIP protein expression in the cartilage endplate and anulus fibrosus of 9-month amputated rats. The mRNA levels of p16INK4a, RB, PTEN, p27KIP, p19ARF, and RAGE were upregulated. The increased cyclin D1 mRNA level was statistically significant only at the ninth month following amputation; CDK4 and TERT mRNA levels were downregulated to a similar extent at both points compared with nonamputated controls. mRNA expression of p21 was significantly downregulated.
Conclusion. Accelerated cell senescence was associated with forelimb amputation that causes abnormal loading in rat lumbar IVDs.