The anti-apoptosis effect of intensive insulin treatment on cardiac myocytes in severe scald rats / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the anti-apoptosis effect of intensive insulin treatment on cardiac myocytes and its underlying mechanism in severe scald rats.</p><p><b>METHODS</b>Twelve SD rats were suffered from 30% TBSA full thickness scald, and they were divided into: IT group [with intravenous injection of isotonic saline including insulin (15 mU x kg(-1) x min(-1)) and 100 g/L glucose], B group [with treatment of isotonic saline (2 mL x kg(-1) x %TBSA(-1) x 8 h(-1)]. Six SD rats received sham burn as controls[sham(S)group, with treatment of fluid at physiologic dose]. + dp/ dtmax (the rate of the rise of left ventricular pressure) and -dp/ dtmax (the rate of the fall of left ventricular pressure)at 6 post burn hour (PBH)were recorded. Apoptosis were determined by TUNEL staining and DNA ladder. The phosphorylation f Akt and protein expression of Bcl-2 in cardiomyocyte were assayed by Western blotting.</p><p><b>RESULTS</b>The + dp/ dtmax in the S group, IT group and B group at6 PBH were respectively (5.5 +/- 0.5) x 10(3) mm Hg/s, (3.4 +/- 0.4) x 10(3 mm Hg/s and (2.5 +/- 0.5) x 10(3) mm Hg/s (1 mm Hg = 0.133 kPa), the - dp/ dtmax were respectively (4.55 +/- 0.34) x 10(3) mmHg/s, (2.94 +/- 0.22) x 10(3) mm Hg/s and (2.05 +/- 0.19) x 10(3) mmHg/s.The +/- dp/dtmax in IT group was significantly higher than those in B group( P < 0.01). The apoptosis index in B group was (13.1 +/- 3.4)%, which was obviously higher than that in IT group (6.7 +/- 1.8)% and S group (0.6 +/- 0.4)% (P < 0.01). DNA ladder showed that no DNA fragmentation in S group, but obvious DNA fragmentation forming ladder pattern in B group, and no obvious ladder pattern in IT group. The phosphorylation of Akt and level of Bcl-2 protein in B group were markedly higher than those in IT group ( P < 0.05 or P < 0.01).</p><p><b>CONCLUSION</b>Intensive insulin treatment can upregulate the activity of Akt and enhance the expression of Bcl-2, and they might constitute the mechanisms for anti-apoptosis in cardiomyocyte and protection of cardiac function.</p>

Study on crosstalk between phosphatidylinositol 3 -kinase/Akt pathway and p38 mitogen-activated protein kinase pathway in cardiomyocyte with challenge of burn serum / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the possibility of crosstalk between phosphatidylinositol 3-kinase (PI3-K)/Akt pathway and p38 mitogen-activated protein kinase (p38MAPK) pathway in cardiomyocyte with challenge of burn serum, and to explore their influence on cardiomyocyte injury after burn.</p><p><b>METHODS</b>The model of murine cardiomyocyte with stimulation of burn serum was established. (1) The level of Akt and p38 phosphorylation in cardiomyocyte were examined with stimulation of 10% burn serum before stimulation and 1, 3, 6, 12, 24 hour after stimulation. (2) The levels of Akt and p38 phosphorylation in cardiomyocyte were determined with stimulation of burn serum (at concentration of 5%, 10%, 20%) or 10% burn serum plus insulin (at concentration of 1 x 10(-8), 1 x 10(-7), 1 x 10(-6)mol/L). The content of creatine kinase (CK) in supernate was also detected. (3) Addition to the inhibitor of p38 MAPK pathway (SB203580) and PI3K/Akt pathway (LY294002), the level of p38MAPK, PI3K/Akt and the content of CK in supernate were determined.</p><p><b>RESULTS</b>(1) The level of p-p38 in cardiomyocyte was 4.0 +/- 0.8, 3.6 +/- 0.8, 5.1 +/- 1.6, 2.4 +/- 0.5, 3.0 +/- 0.6 at 1, 3, 6, 12, 24 hour (s) after stimulation of burn serum, which was obviously higher than that immediate after stimulation (1.0, P < 0.01). The level of p-Akt was 0.15 +/- 0.07, 0.64 +/- 0.10, 0.26 +/- 0.08, 0.38 +/- 0.11, 0.59 +/- 0.13, which was obviously lower than that before stimulation (1.00, P < 0.01). (2) With stimulation of different concentration of burn serum or burn serum plus insulin, the level of p-Akt and p-p38 changed in the opposite directions comparatively. The content of CK increased along with increase of burn serum concentration, but decreased obviously with treatment of insulin (P < 0.05 or 0.01). (3) Low level of p38 induced by burn serum was increased after treatment of LY294002, which neutralized the protection of insulin (P < 0.01). Low level of p-Akt induced by burn serum increased after treatment of SB203580 (P < 0.01), which inhibited the release of CK induced by burn serum.</p><p><b>CONCLUSION</b>There is being crosstalk between PI3K/Akt pathway and p38 MAPK pathway in cardiomyocytes with challenge of burn serum, which may regulate cardiomyocytes.</p>

The protective effect of intensive insulin treatment on the myocardium in severely scalded rats / 中华烧伤杂志

<p><b>OBJECTIVE</b>To study the protective effect of intensive insulin treatment on the myocardium of severely scalded rats, and to primarily explore its mechanism.</p><p><b>METHODS</b>Eighteen SD rats were divided into three groups, with 6 rats in each group. The rats in burn and intensive insulin group were inflicted with 30% TBSA full-thickness injury on the back. Isotonic saline containing 0.12 U/ml insulin solution, and 100 g/L glucose solution were infused into the rats in the intensive insulin group to keep plasma glucose at the level of 4.0 - 6.6 mmol/L (the total fluid amount was 2 ml x kg(-1) x 8h(-1)). In sham burn group,fluid was given according to physiological demand. The same amount of isotonic saline was infused into the rats in burn group. The venous blood was obtained for the detection of plasma glucose contents, and the left ventricular systolic pressure (LVSP) and left ventricular end-diastolic pressure (LVEDP) were recorded via aortic ventricle cannula before scald and at 1, 2, 3, 4, 5, 6 post-scald hours (PSH). The tissue of the left ventricle was harvested at 6 PSH for the detection of troponin T expression in myocardiocytes.</p><p><b>RESULTS</b>Plasma glucose level was increased to (7.6 +/- 1.7) mmol/L - (8.4 +/- 4.7) mmol/L in burn group during 1-6 PSH, which was significantly higher than that in intensive insulin group (4.5 +/- 0.9) mmol/L - (5.2 +/- 1.3) mmol/L, P < 0.01). Compared with the intensive insulin group, LVSP was markedly decreased in the burn group (60 +/- 11 mm Hg vs 72 +/- 8 mm Hg, P < 0.05) at 1 PSH,whereas LVEDP was increased significantly (21.3 +/- 11.3 mmHg vs 11.7 +/- 5.2 mmHg, P < 0.05). Intensive insulin treatment could significantly inhibit the loss of troponin T protein in myofilaments of myocardium.</p><p><b>CONCLUSION</b>Intensive insulin treatment possesses a protective effect on myocardia function after severe burns, and it may be related to its preventive effect on the loss of contractile protein in cardiocytes.</p>

Protective effect of insulin on oxygen-radical induced hepatic injury in severely scalded rats / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the protective effect of insulin on oxygen-radical induced hepatic injury in severely scalded rats in early stage of severe scald.</p><p><b>METHODS</b>Eighty-four male Sprague-Dawley rats were randomly divided into three groups: i. e, normal group, saline group, and insulin group, with 28 rat in each group. The rats in the latter two groups were subjected to 30% TBSA full-thickness scald on the back, and received intra-peritoneal injection of 40ml/kg isotonic saline, and subcutaneous injection of 3 IU/kg insulin, respectively. The total anti-oxygen capability (T-AOC), the expression of superoxide dismutase (SOD), reactive oxygen species (ROS) and intercellular adhesion molecule (ICAM-1) in hepatic tissue, and serum alanine transaminase (ALT) were determined in each group at 6, 12, 24, 48 post-scald hours (PSH) with corresponding methods.</p><p><b>RESULTS</b>The hepatic T-AOC and SOD content were obviously decreased, while the ROS content were markedly increased at 6 PSH in saline group compared with that in normal group (P < 0.05 or P < 0.01). The expression of ICAM-1 and serum content of ALT were significantly higher than that in normal group at 12 PSH and 48 PSH (P < 0.01). At 24 PSH, the hepatic T-AOC (386 +/- 75) U/g and SOD content (210 +/- 39 ) U/g were obviously higher in insulin group than those in saline group [(124 +/- 18), (111 +/- 9) U/g, respectively, P < 0.01), but the ROS content (154 +/- 29 ) U/g was much lower than that in saline group [(351 +/- 41) U/g, respectively, P < 0.01]. At 48 PSH, the serum content of ALT and hepatic expression of ICAM-1 in insulin group exhibited obvious difference when compared with those in saline group (P < 0.01). Meanwhile, Pathological examination showed that hepatic injury was alleviated by insulin administration after scald.</p><p><b>CONCLUSION</b>Insulin administration early after severe scald exhibits protective effect on liver function by improving anti-oxygen radical ability of rat liver.</p>

Study of the anti-endotoxin effect of beta-1, 2, 3, 4, 6-penta-O-galloyl-D-glucopyranose in vitro / 中华烧伤杂志

<p><b>OBJECTIVE</b>To study the anti-endotoxin effect of beta-1, 2, 3, 4, 6-penta-O-galloyl-D-glucopyranose (PGG) in vitro.</p><p><b>METHODS</b>The affinity of PGG with lipid A was determined with biosensor technology, and the endotoxin-neutralizing effect was assayed with LAL. Human peripheral blood mononuclear cells (hPBMC) were separated from healthy donors and cultured in vitro. The effect of different concentrations of PGG on the release of TNF-alpha and hIL-6 from LPS-stimulated hPBMC were measured by ELISA method.</p><p><b>RESULTS</b>Lipid A was combined with different concentrations of PGG. The combination speed was shortened with the increase in PGG concentration. The KD value between PGG and Lipid A was 5.2 x 10(-7) mol/L. The release of TNF-alpha and IL-6 of hPBMC under LPS stimulation (958 +/- 234 ng/L vs 1 351 +/- 99 ng/L) was obviously inhibited by PGG in the concentration of higher than 20 mg/L compared with that without PGG treatment (1 788 +/- 171 ng/L vs 1 965 +/- 232 ng/L, P < 0.05).</p><p><b>CONCLUSION</b>PGG show an anti-endotoxin effect in vitro, which may be associated with its ability to combine and neutralize endotoxin.</p>

Experimental study on the antagonistic activity of cationic multi-peptide mastoparan-1 against lipopolysaccharide / 中华烧伤杂志

<p><b>OBJECTIVE</b>To explore the mechanism of cationic multi-peptide mastoparan-1 (MP-1) on the protection of mice from lipopolysaccharide (LPS) challenge.</p><p><b>METHODS</b>Thirty Kunming mice were divided randomly into MP-1, injury, protection groups with 10 mice in each group. The mice in MP-1 group were injected with 3 mg/kg MP-1 by tail vein, while those in injury group were injected with 20 mg/kg LPS by tail vein, and those in protection group 3 mg/kg MP-1 within 20 seconds after 20 mg/kg LPS injection were injected. The effects of MP-1 on the protection of mice from LPS challenge were observed. In vitro, the affinity of MP-1 and PMB to LPS was compared by biosensor and FAST fit construct and expressed as Kd. And the neutralizing activity of MP-1 and PMB in dose of 5, 10, 20, 40 micromol/L on LPS (2 microg/L) was detected by dynamic turbidimetric limulus test with LPS neutralizing 0 micromol/L MP-1 and PMB as control. The mRNA expression levels of TLR4, TNF-alpha and IL-6 in murine peritoneal macrophages (PM phi) after exposure to LPS (100 ng/ml) were assayed by RT-PCR.</p><p><b>RESULTS</b>MP-1 could significantly protect mice from LPS challenging with protection rate of 90%. In vitro, MP-1 had a high affinity (Kd value: 484.0 nmol/L) and neutralizing ability with LPS, but it was lower than that of PMB (Kd value: 18.9 nmol/L). The neutralizing effect of 20 and 40 micromol/L MP-1 was obviously stronger than that in 0 micromol/L (P < 0.01). MP could obviously inhibit the expression of TLR4, TNF-alpha and IL-6 mRNA in LPS-stimulated murine PM phi.</p><p><b>CONCLUSION</b>MP-1 can evidently protect mice from lethal LPS challenge, and the mechanism might be related to the activity of MP-1 which binding and neutralizing LPS, blocking the combination LPS with its receptors. So the murine macrophage activation induced by LPS was inhibited.</p>

Study on the injurious effect of a self designed micro-skin machine on the epithelia / 中华烧伤杂志

<p><b>OBJECTIVE</b>To observe the injury on micro-skin induced by a self designed micro-skin machine.</p><p><b>METHODS</b>Micro-skin was produced either with the machine or by hand. Cells at the edge of micro-skin were observed by transmission electron microscope. succinic dehydrogenase activity in supernatant of cultivated cells was analyzed, and the cell proliferation of micro-skin was assessed by (3)H-TdR. Twenty patients were enrolled in the study for the observation of the wound healing time between the two groups of micro-skin after being grafted.</p><p><b>RESULTS</b>Transmission electron microscope examination revealed that the cellular injury at the edge of the micro-skin in machine-made group was mild compared with that in man-made group. (3)H-TdR rate was elevated but the activity of succinic dehydrogenase in the supernatant of cultured cells decreased in supernatant of cultured cells of machine produced micro-skin. Wound healing time was shortened in machine made group. (P < 0.05).</p><p><b>CONCLUSION</b>The cellular injury at the edge of micro-skin in the machine made group was mild when compared with that in the man-made group with cell proliferation accelerated and wound healing time shortened.</p>