Inhibitory effect of insulin on nuclear factor-kappa B nuclear translocation of vascular endothelial cells induced by burn serum / 中华烧伤杂志

<p><b>OBJECTIVE</b>To study the inhibitory effects of insulin on nuclear factor-kappa B (NF-kappaB) nuclear translocation of vascular endothelial cells induced by burn serum and its correlative mechanism.</p><p><b>METHODS</b>Human umbilical vein endothelial cells (HUVECs) were cultured in vitro and divided into 5 groups: blank control group (BC, ordinary culture without any stimulation), normal serum control group (NS, cultured with nutrient solution containing 20% healthy human serum), burn serum stimulation group (BS, cultured with nutrient solution containing 20% burn human serum), burn serum+insulin treatment group (BI, cultured with nutrient solution containing 20% burn human serum and 1x10(-7) mol/L insulin), inhibitor pretreatment group [IP, pretreated with 50 micromol/L protein kinase B (Akt) specific inhibitor LY-294002, then cultured with the same medium as used in BI group 30 minutes later] according to the random number table. Six hours later, the injury and apoptosis of HUVECs was respectively observed by the scanning electron microscope and determined by the flow cytometry. Meanwhile, the phosphorylation of inhibitor kappa B-alpha (p-IkappaB-alpha) and Akt (p-Akt) in cytoplasm, and the content of NF-kappaB-p65 in nucleus were determined with Western blot.</p><p><b>RESULTS</b>(1) Compared with those in BC group, HUVECs in BS group shrank obviously with irregular nuclear structure, and intercellular links jagged or vanished. Slight change was observed in HUVECs structure in NS and BI groups, with the cell ductility and nuclear structure much better than those in BS group. (2) The apoptosis rates of HUVECs in BS group [(28.5+/-2.3)%], BI group [(22.3+/-1.8)%], and IP group [(29.7+/-2.4)%] were all obviously higher than that in BC group [(15.7+/-2.2)%, F=14.288, P<0.05 or P<0.01]. There was no significant statistical difference between NS group [(17.0+/-2.5)%] and BC group in apoptosis rate (F=14.288, P>0.05). The apoptosis rate of HUVECs in BI group was obviously lower than that in BS group (F=14.288, P<0.05). (3) Compared with those in BC group, the protein expressions of p-IkappaB-alpha in cytoplasm and NF-kappaB-p65 in nucleus were up-regulated, and the protein expression of p-Akt in cytoplasm was down-regulated in BS and IP groups. The expression levels of the three proteins in NS and BI groups were close to those in BC group.</p><p><b>CONCLUSIONS</b>Insulin could inhibit the IkappaB phosphorylation, and then restrict NF-kappaB nuclear translocation and improve the vascular endothelial cells function accordingly through regulating phosphatidylinositol 3 kinase/Akt pathway.</p>

Reproduction of a model of heat injured keratinocyte in vitro and observation on its apoptosis rate / 中华烧伤杂志

<p><b>OBJECTIVE</b>To reproduce a model of heat injured KC in vitro and explore its apoptosis rate of KC due to heat injury at different temperature.</p><p><b>METHODS</b>Human KCs were cultured in vitro, and they were incubated at 37, 41, 43, 45, 48, and 51 degrees C respectively for 10 mins in water bath. Trypan blue staining and Hoechst 33258 fluorescence staining were used respectively to determine necrosis and apoptosis of KC. Rates of apoptosis and necrosis of KC were analyzed quantitatively by flow cytometer. The proliferation activity of KC after heat injury was detected by MTT test.</p><p><b>RESULTS</b>The results of trypan blue staining, Hoechst 33258 fluorescence staining, and flow cytometer demonstrated that number of apoptotic and necrotic KC increased gradually along with a rise of water bath temperature. The rates of apoptosis and necrosis of KC were respectively (12.3 +/- 3.2)% and (14.1 +/- 1.6)% at 45 degrees C, (27.7 +/- 5.1)% and (58.0 +/- 4.2)% at 48 degrees C. Rate of KC necrosis reached up to (83.0 +/- 5.3)% at 51 degrees C. Inhibition of KC growth reached a stationary phase when the injurious temperature reached 45 degrees C as observed with MTT test.</p><p><b>CONCLUSIONS</b>Heat injury can induce apoptosis and growth inhibition of KC in vitro. Incubating KC at 45 degrees C for 10 mins is a good condition to reproduce a model of heat injured KC in vitro. This model may be used to study the biological character and apoptosis of KC after burn injury.</p>

Study of biosensor technology on the detection of endotoxin-neutralizing materials / 中华烧伤杂志

<p><b>OBJECTIVE</b>To explore the application of biosensor technology in the determination of endotoxin-neutralizing materials.</p><p><b>METHODS</b>After mixing polymyxin B (PMB) with endotoxin in certain concentration, the neutralizing ratio of PMB to endotoxin was assessed by biosensor technique and limulus amebocyte lysate test respectively. The results from the two methods were compared.</p><p><b>RESULTS</b>The neutralizing ratio of PMB to endotoxin as assessed by biosensor technology was 0.35 microg to 1 ng, while that by dynamic turbidimetric and chromogenic limulus amebocyte lysate (LAL) technique was 0.5 mg to 1 ng and 1 mg to 1 ng, respectively. The results obtained by biotechnology were similar to that by biosensor technique.</p><p><b>CONCLUSION</b>Biosensor technology was an accurate, convenient and rapid method for the determination of potency of endotoxin-neutralizing materials.</p>