A new model of skin avulsion injuries in rats / 中华整形外科杂志

<p><b>OBJECTIVE</b>To create a stable and reliable model of skin avulsion in rats.</p><p><b>METHODS</b>30 male, SD rats were randomly divided into axial pattern skin flap (9 cm x 3 cm) group and random pattern skin flap group (6 cm x 4 cm), each having the control groups and avulsion groups. Flaps were subjected to avulsion force of 6 kg in axial pattern skin flaps or 8 kg in random pattern skin flaps, and the lasting time was 8 s or 12 s, respectively. Retraction of wounds and necrosis of skin flaps were observed.</p><p><b>RESULTS</b>There was more significant wound retraction in avulsion groups than that in control groups on post-operation day 7 (P < 0.05). The proportion of the wound retraction increased by 1 fold in avulsion groups on post-operation day 14 as compared to post-operation day 7 (P < 0.01). Interestingly, necrosis of partial or most of skin flaps was observed in all animals of avulsion groups, while slight necrosis happened in one of six in control animals. The necrosis area of flaps was 38% - 77% when avulsed for 8 s, and was 40% - 80% when avulsed for 12 s in axial pattern skin flaps. However, the necrosis area in random pattern skin flaps was smaller than that in axial pattern skin flaps, from 17% - 40% when avulsed for 8 s to 24% - 43% when avulsed for 12 s.</p><p><b>CONCLUSIONS</b>It might be possible to create animal model of skin avulsion injuries with rats.</p>

Effects of escharectomy during shock stage on tissue high mobility group box-1 expression and balance of pro-/anti-inflammatory response in rats after severe thermal injury / 中华外科杂志

<p><b>OBJECTIVE</b>To investigate the effects of escharectomy during shock stage on tissue high mobility group box-1 protein (HMGB1) expression and balance of pro-/anti-inflammatory cytokines, and to elucidate the potential mechanism underlying beneficial effect of early escharectomy after severe burns.</p><p><b>METHODS</b>Wistar rats inflicted by 30% full-thickness thermal injury were randomly divided into thermal injury group, 24 h escharectomy group and 72 h escharectomy group, in which escharectomy were performed at 24 and 72 h postburn, respectively. Gene expression of HMGB1, interleukin-10 (IL-10), and tumor necrosis factor-alpha (TNF-alpha) in liver and lungs was detected with reverse-transcription PCR, and protein levels of IL-10 and TNF-alpha in liver and lung tissues were measured by ELISA. The plasma AST and ALT contents, and pulmonary myeloperoxidase (MPO) activity were also assayed.</p><p><b>RESULTS</b>The mRNA expression of HMGB1 and TNF-alpha in liver and lungs was up-regulated on postburn day 2, with IL-10 over-expression on postburn day 8. In the 24 h escharectomy group, HMGB1 and TNF-alpha mRNA expression in liver and lungs was down-regulated on postburn day 4, and IL-10 expression returned to normal range on postburn day 8, while the down-regulation of HMGB1, TNF-alpha and IL-10 were not noted in the 72 h escharectomy group. There were two peaks in liver TNF-alpha protein levels appearing on postburn days 2 and 8, respectively, with an unexpected marked decrease on day 4 in thermal injury controls, yet liver TNF-alpha levels maintained in normal range in animals of 24 h and 72 h escharectomy groups. The ratios of TNF-alpha to IL-10 protein levels in liver tissue were significantly increased on postburn days 2 and 4 (P = 0.0001 and 0.002, respectively), while escharectomy during shock stage markedly reduced hepatic TNF-alpha to IL-10 ratios (P = 0.0008 and 0.040, respectively). No significant changes in TNF-alpha protein levels in lung tissue were observed. Additionally, plasma AST as well as ALT contents, and pulmonary MPO activity were markedly decreased on postburn days 4 and 8 in the 24 h escharectomy group compared to the 72 h escharectomy group or thermal injury controls (P < 0.05).</p><p><b>CONCLUSIONS</b>Escharectomy during burn shock stage could inhibit the over-expression of both early and late inflammatory mediators, and maintain the balance of pro-/anti-inflammatory response, thereby improving multiple organ functions in rats following severe burns.</p>

The protective effect of supplementation of probiotics combined with riboflavin on the intestinal barrier of the rats after scald injury / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the effect and its possible mechanism of the supplementation of probiotics combined with riboflavin on the intestinal barriers of the rats after scald injury.</p><p><b>METHODS</b>Seventy Wistar rats were used in the study and were randomly divided into scald control (SC, n = 30), scald and treatment (ST, n = 30) and normal control (NC, n = 10) groups. The rats in SC and ST groups were subjected to 30% TBSA III degree scald. 1.5 ml of isotonic saline suspension containing 5 x 10(12) CFU/L of Bifidobacteria, 5 x 10(10) CFU/L of Bacillus cereus and 5 mg/L of riboflavin was given to rats by gavage in ST group twice a day. For the rats in SC and NC group equal amount of isotonic saline was fed twice a day. The changes in the incidence of bacterial translocation, the amount of intestinal membranous flora, the synthesis and secretion of SIgA in the ileum, and the repair of injured intestinal mucosa were observed.</p><p><b>RESULTS</b>The incidence of bacterial translocation in ST group was significantly lower than that in SC group (P = 0.000 - 0.025). The plasma level of endotoxin in ST group was markedly lower than that in SC group on 3 post-scald day (PSD) (P < 0.05). The amount of bifidobacteria in caecal membrane flora increased by about 20 to 40 fold, whereas the amounts of E. coli and fungi significantly decreased (P < 0.01). The membranous injury scoring was 3 to 0 on 5 PSD (P < 0.05), and the SIgA content in intestinal mucus returned to normal value on the 5th PSD (P < 0.01) in the ST group.</p><p><b>CONCLUSION</b>Supplementation of probiotics together with riboflavin could ameliorate translocation of bacteria and endotoxin in rats with scald injury, implying that the intestinal barrier function was effectively protected.</p>

Influence of escharectomy during shock stage on the systemic and intestinal immune function in scalded rats / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the influence of escharectomy during shock stage on systemic and intestinal immune function and its mechanism in scalded rats.</p><p><b>METHODS</b>Ninety-six Wistar rats were employed in the study of which 8 were used as normal control group. The donor skin from the trunk in twenty-four rats were preserved in liquid nitrogen. The other 64 rats were subjected to 30% full-thickness scalding, and they were randomly divided into A (n = 24, no treatment after scalding), B (n = 24) and C (n = 16) groups. Physiological saline was intraperitoneally injected (50 ml/kg) on the 24 post-scalding hours to the rats in the B and C groups. The rats in B group underwent escharectomy during shock stage, and the excision wounds were covered with the cryo-preserved alloskin. The rats in C group received the same treatment as in B group but at 72 post-scalding hours. The change in the proliferative ability of splenic lymphocytes, the plasma and intestinal tissue content of interleukin 2 (IL-2), the contents of sIgA in intestinal mucus, and the content of DAO in the intestinal tissue were observed on 2, 4 and 8 post burn days (PBD) in A and B groups and also on 4 and 8 PBD in C group, respectively.</p><p><b>RESULTS</b>The splenocytic proliferative ability, IL-2 level in the plasma and intestinal tissue, and the sIgA content in intestinal mucus in the rats in A, B and C groups were lower than that in control group at all time points (P < 0.05). The proliferative ability of splenic lymphocytes in B group on 4 and 8 PBD and in C group on 8 PBD respectively was similar to that in control group. Whereas the IL-2 content in plasma and in intestinal tissue was higher in B and C groups than that in A group (P < 0.01). The sIgA content in intestinal mucus in B group was twice of that in C group respectively [(3.51 +/- 2.14) mg/g vs (1.40 +/- 0.64) mg/g, (3.03 +/- 0.95) mg/g vs (1.52 +/- 1.26) mg/g (P < 0.05 or P < 0.01)] on 4 and 8 PBD. The DAO activity in the intestinal tissue in A group was lower than that in control and B group (P < 0.05) on 4 and 8 PBD.</p><p><b>CONCLUSION</b>Escharectomy during shock stage might be beneficial to the recovery of the systemic and intestinal immune functions in rats with scalding injury.</p>

Bifidobacterial supplement enhances the expression and excretion of intestinal sIgA in severely burned rats / 中华外科杂志

<p><b>OBJECTIVE</b>To investigate the potential effect of bifidobacterial supplement on intestinal mucosal immunity associated with severe burns.</p><p><b>METHODS</b>Wistar rats were randomly divided into burn control group (BC group, n = 30), treatment group (BT group, n = 30), and sham-burn group (NC group, n = 10). Rats in BT group were fed bifidobacterial preparation (5 x 10(9) CFU/ml) after 30% total body surface area full-thickness burns, 1.5 ml, twice daily. Rats in BC group and NC group were fed normal saline, 1.5 ml, twice daily. Samples were taken on post-burn 1-, 3-, and 5-day. The incidence of bacterial translocation and bifidobacteria counts in the cecum mucosa were determined with standard methods. The sIgA levels in the mucus of the small intestine were measured by RIA. The positive sIgA expression in the lamina propria was detected by immunohistochemical staining.</p><p><b>RESULTS</b>The incidence of bacterial translocation was 42% and 16% in BC and BT groups on post-burn day 3 (P = 0.004), 30% and 8% on day 5 (P = 0.002), respectively. Plasma endotoxin levels were markedly higher in BC and BT groups than in NC group at the early stage post-burn. There was a significant decrease between BT group and BC group on post-burn day 1 (P = 0.0412). Bifidobacteria counts in cecum mucosa were reduced by 10- to 60-fold after thermal injury, but there was a remarkable increase in bifidobacteria counts in animals fed with bifidobacteria. sIgA levels in the intestinal mucus were significantly decreased in group BC, but they returned to normal range in BT group on post-burn day 5. Similarly, sIgA expression in the lamina propria was also weakened after burns, and had a tendency to recover after prescription of a 5-day bifidobacteria-supplemented formula. A strong positive correlation was observed between the counts of bifidobacteria in the cecal mucosa and the levels of sIgA in the intestinal mucus (r = 0.7534, P = 0.0000).</p><p><b>CONCLUSIONS</b>The expression and excretion of sIgA in the intestine appear to be markedly inhibited following a severe thermal injury. The supplement of exogenous bifidobacteria could improve sIgA formation in the small intestine, thereby reducing the incidence of bacterial/endotoxin translocation secondary to major burns.</p>