[Effects and mechanism of bFGF on rat myoblast oxidative injury induced by hydrogen peroxide].

OBJECTIVE: To explore the protective role of basic fibroblast growth factor (bFGF) on attenuating hydrogen peroxide-induced injury in cultured rat myoblasts. METHODS: Cultured rat myoblasts at growth phase were randomly divided into four groups (n=6):control group (control), bFGF group (bFGF), model group(H2O2) and the treatment group (bFGF + H2O2). Model group was treated with 100 µmol/L hydrogen peroxide for 4h. B-cell lymphoma-2 (Bcl-2) positive particles were detected by immunohistochemistry; Reactive oxygen species (ROS) and expression for Bcl-2 associated X protein (Bax), Bcl-2 and Cytochrome C (Cyt. C) fluorescence were observed under the invented microscope; Cyt. C and Poly ADP-ribose polymerase(PARP)protein were assessed by Western blot. RESULTS: Compared with control group, the myoblats in the model group showed low expression of Bcl-2 positive particles, accompanied by high expression of ROS level and Cyt. C fuorescence (P < 0.05); Compared with model group, bFGF enhanced Bcl-2 activity of the myoblasts, and significantly downregulated Cyt. C and PARP expression (P < 0.05). CONCLUSIONS: bFGF could attenuate oxidative injury of rat myoblasts induced by hydrogen peroxide, which mechanism might be related to enhanced Bcl-2 and reduced ROS, Cyt. C levels.

Pressure Combined with Ischemia/Reperfusion Injury Induces Deep Tissue Injury via Endoplasmic Reticulum Stress in a Rat Pressure Ulcer Model.

Pressure ulcer is a complex and significant health problem in long-term bedridden patients, and there is currently no effective treatment or efficient prevention method. Furthermore, the molecular mechanisms and pathogenesis contributing to the deep injury of pressure ulcers are unclear. The aim of the study was to explore the role of endoplasmic reticulum (ER) stress and Akt/GSK3ß signaling in pressure ulcers. A model of pressure-induced deep tissue injury in adult Sprague-Dawley rats was established. Rats were treated with 2-h compression and subsequent 0.5-h release for various cycles. After recovery, the tissue in the compressed regions was collected for further analysis. The compressed muscle tissues showed clear cellular degenerative features. First, the expression levels of ER stress proteins GRP78, CHOP, and caspase-12 were generally increased compared to those in the control. Phosphorylated Akt and phosphorylated GSK3ß were upregulated in the beginning of muscle compression, and immediately significantly decreased at the initiation of ischemia-reperfusion injury in compressed muscles tissue. These data show that ER stress may be involved in the underlying mechanisms of cell degeneration after pressure ulcers and that the Akt/GSK3ß signal pathway may play an important role in deep tissue injury induced by pressure and ischemia/reperfusion.

[The role of cell apoptosis mediated by endoplasmic reticulum stress (ERS) of deep tissue injury of pressure ulcer of rats].

OBJECTIVE: To observe the the expression of endoplasmic reticulum stress (ERS) related factors in deep tissue injury (DTI) at pressure ulcer rat and to investigate the ERS mechanism of DTI in muscle tissue and protective effect of 4-phenylbutyric acid (4-PBA) in local tissue. METHODS: Fifty male SD rats were randomly devided into control group, model group, experimental group NS group and PBA group, the experimental groups were divided into 4 d, 7 d, 14 d and 21 d group according to the observation time (n = 5). Rats in the PBA group were administrated with gastric perfusion of 4-PBA after the modeling; the NS group was given normal saline of the same quantity. Using HE staining to observe morphologic character. The expression of glucose regulated protein 78 (GRP78), CHOP, Caspase 12 were detected by immunohistochernical staining. Cell apoptosis was detected by TUNEL assay. RESULTS: HE staining results showed that each group demonstrated compression injury compared with control group: cellular swelling, ompaction of nuclear, and apoptosis in muscle tissue. The new muscle fiber in 4-PBA group fused faster than those in NS group. The number of TUNEL positive cells peaked at 4 day after compression, then got decreased on day 7 in muscle tissue, apoptosis positive cells were diminished after 4-PBA treatment. The immunohistochemical staining results showed that the expression of protein GRP78, CHOP, Caspase 12 peakd 4 d after modeling and decreased gradually. The GRP78, CHOP, Caspase 12 protein expression were significantly higher than those of PBA group at all time points (P < 0.05). CONCLUSION: Cell apoptosis induced by endoplasmic reticulum stress took part in deep tissue injury resulting of pressure ulcer, which mechanism might be related to reducing apoptosis mediated by CHOP, Caspase 12.

[Expressions of tumor necrosis factor-alpha and NF-kappa B in skeletal muscles and its effect on apoptosis in deep tissue injury of rats].

OBJECTIVE: To evaluate the changes of tumor necrosis factor-alpha (TNF-alpha) and nuclear factor-kappaB (NF-kappaB) expression in muscle of pressure ulcer rats and explore the relationship with apoptosis. METHODS: Fifty-four male SD rats were randomly divided into nine groups (n = 6), the experiment groups were pressed 9 circles (3 circles/day, 3 days), then observed on the 1st, 3rd, hematoxylin and eosin staining under the microscope; the expression of TNF-alpha was detected by Western blot; the expressions of NF-kappaB and caspase-3 were determined by immunohistochemistry, and evaluated the relationship of TNF-alpha with NF-kappaB and caspase-3; the number of apoptotic cells in compressed muscle tissue was detected by Hoechst 33258 staining under the fluorescence microscope. RESULTS: Compared with the control group, histology examination showed that the tissue structure in experiment groups was in disorder, inter-space was wider, cell edema and the number of inflammatory cells were increased, the tissue was arranged in order and inflammatory cell recruitment was gradually attenuated. The expressions of TNF-alpha, NF-kappaB and caspase-3 were higher in the experiment groups than those in the control group (P < 0.05), reached their peak on the first day, gradually decreased on the 3nd day, but still had a significantly higher level than that in the control group (P < 0.01) on the 7th day; The number of apoptotic cells of experiment groups had a downward trend after the first rise under the fluorescence microscope; the expressions of TNF-alpha and NF-kappaB caspase-3 were found to have positive correlationship (P < 0.05), the expressions of NF-kappaB and caspase-3 were found to have positive correlationship (P < 0.01). CONCLUSION: Apoptosis is closely correlated with inflammation in deep tissue injury of pressure ulcer, NF-kappaB plays a role not only in the formation of inflammation, but also triggering apoptosis, which may induce the pathological change and clinical progress of pressure ulcer.