Role of lymphatics in bacterial translocation from intestine in burn rats / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the role of lymphatics in bacterial translocation from intestine of rats with burn.</p><p><b>METHODS</b>Escherichia coli (E. coli) labeled with chloromethylbenzamidodialkylcarbocyanine (CM-DIL) were prepared. Sixty adult male Wistar rats were randomly divided into scald group and sham injury group according to the envelope method, with 30 rats in each group. Rats in both groups were gavaged with 0.5 mL fluid containing CM-DIL-labeled E. coli. Rats in scald group were inflicted with 30% TBSA deep partial-thickness scald (verified by pathological section) and resuscitated with fluid. Rats in sham injury group were sham injured by bathing in 25 degrees C water for 10 s (verified by pathological section) and also received with fluid infusion. Mesenteric lymph node (MLN), liver, mesenteric lymph fluid (MLF), and liver vein blood (LVB) were harvested at post injury hour (PIH) 2, 24, and 72. Bacteria translocation was detected with fluorescent tracing technique and bacteria culture. The endotoxin content in above-mentioned four kinds of specimens was quantitatively determined with chromogenic substrate limulus amebocyte lysate. The carrying capacity of endotoxin in MLF and LVB was calculated. Data were processed with t test or one-way analysis of variance.</p><p><b>RESULTS</b>(1) Living bacteria were in short-stick form, and they were seen moving in single or in doubles or triples in sample fluid. Dead bacteria were in irregular aggregates. Labeled bacteria in small amount were detected in sham injury group, their number peaked at PIH 24. A large amount of labeled bacteria were detected in scald group at PIH 2, which peaked at PIH 24 and decreased at PIH 72. The largest amount of labeled bacteria were found in MLN in scald group as compared to those in the other samples, and the number peaked at PIH 24 [(5872 +/- 1976) x 10(3) CFU/g], which was obviously higher than that [(216 +/- 110) x 10(3) CFU/g, t = 30.129, P = 0.000] in sham injury group. The number of bacteria decreased at PIH 72, but it was still significantly different from that in sham injury group ( t = 4.323, P = 0.000). The number of bacteria in LVB was the smallest. (2) 29 (24.2%) samples out of the 120 samples in sham injury group were positive for bacteria. 72 (60.0%) samples out of the 120 samples in scald group were positive for bacteria. No alive bacterium was detected at any time point in LVB sample in both group; the other three samples were detected with alive bacteria since PIH 2. There were more alive bacteria detected in MLN and liver as compared with the other two kinds of samples in scald group. The amount of bacteria in MLN, liver, and MLF in scald group were higher than those in sham injury group (with t value respectively 4.353, 4.354, 4.965, P values all equal to 0.000). (3) The endotoxin level in each kind of sample at each time point was obviously higher in scald group than that in sham injury group, and it peaked at PIH 2 in liver and MLF. The difference of endotoxin level among 4 kinds of samples in scald group at PIH 2 was statistically significant ( F = 258.47, P = 0.000), and the endotoxin level was higher in liver, MLN, and MLF. They were obviously higher than those in sham injury group (with t value respectively 43.378, 43.123, 22.423, P values all equal to 0.000). The endotoxin level in MLF was 9 times of that in LVB. (4) The carrying capacity of endotoxin in LVB and MLF at each time point in scald group was higher than that in sham injury group.</p><p><b>CONCLUSIONS</b>CM-DIL marked bacteria can reflect the microbial translocation condition. The lymphatic route is an important pathway for bacteria translocation.</p>

Expression of tumor necrosis factor related apoptosis inducing ligand and its receptor in thymus during early post-burn stage in rat with severe burns / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the effect of tumor necrosis factor related apoptosis inducing ligand (TRAIL) and its receptor on apoptosis in thymus during early post-burn stage in rat with severe burns.</p><p><b>METHODS</b>Fifty Wistar rats were randomly divided into sham scald group (SS, n = 10) and burn group (n = 40). The apoptosis in thymus in rats was detected with annexin V/FITC-PI double staining at 4, 12, 24, 48 post-burn hours (PBH). The expression of TRAIL death receptor DR5, DR4 and its decoy receptor DcR1, DcR2 in thymus were detected by RT-PCR and Western blot at above time-points.</p><p><b>RESULTS</b>Compared with that in SS group (6.7 +/- 0.8)%, the apoptosis in the thymus in burn group started to increase at 4 PBH [(17.1 +/- 0.4)%], peaked at 12 PBH [(25.2 +/- 1.1)%], and it was still evidently higher than that in SS group at 48 PBH (P < 0.05). There was no obvious difference in the apoptosis rate in rats in burn group among all the time-points. The expression of DR5 in burn group at each time-points was significantly higher than those in SS group, while that of DcR2 shown an opposite tendency (P < 0.05). The expression of DR4, DcR1 was similar in both groups.</p><p><b>CONCLUSION</b>The marked increase in apoptosis rate in rat thymus at early post-burn stage, and the significant change in the expression of DR5 and DcR2 show that TRAIL pathway may participate in apoptosis.</p>

Expression and significance of TRAIL receptors in fibroblasts of hypertrophic scar / 中华整形外科杂志

<p><b>OBJECTIVE</b>To detect the expression of TRAIL receptors in fibroblasts of hypertrophic scar in the proliferative stage and explore its significance.</p><p><b>METHODS</b>30 samples of hypertrophic scar were taken from 30 burn cases in the proliferative stage. 30 samples of normal skin were taken as the control. The expressions of TRAIL receptors in the fibroblasts of hypertrophic burn scar and the normal skin were assayed by semiquantitative RT-PCR and flowcytometry.</p><p><b>RESULTS</b>The expression level of DR5 in the fibroblasts of hypertrophic burn scar is much lower than the control (P < 0.05); the expression level of DcR1 in the fibroblasts of hypertrophic burn scar is much higher than the control (P < 0.05).</p><p><b>CONCLUSIONS</b>The down-regulated DR5 expression and elevated DcR1 expressions in the fibroblasts of hypertrophic burn scar may attribute to the apoptosis change induced by TRAIL and explain the apoptosis differences between the fibroblasts of hypertrophic scar and normal skin to a certain extent.</p>

The changes in the tumor necrosis factor alpha, interleukin-6 and interleukin-8 levels in the lymph and of the dynamics of the lymphokines during shock stage of rats with major burns / 中华烧伤杂志

<p><b>OBJECTIVE</b>To study the dynamic changes in the lymphokines and the changes in tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6), interleukin-8 (IL-8) levels in the lymph during shock stage of rats with major burns.</p><p><b>METHODS</b>Forty-two male adult Wistar rats were randomly divided into burn resuscitation group (A, n = 18), burn non-resuscitation (B, n = 18) and the control (C, n = 6) groups. The TNF-alpha, IL-6 and IL-8 levels in the lymph were determined with radioimmunoassay at 6, 24, 48 postburn hours (PBH). The lymphokines in the mesenteric lymphatic vessels was observed at 6, 24 and 48 PBH with inverted microscopy and digital image processing, and the contraction frequency of the lymphatic was calculated. The lymph was collected by cannulation of the chylous cistern, and its speed of flow was calculated.</p><p><b>RESULTS</b>The lymphatic contents of TNF-alpha and IL-6 in both A and B groups began to increase at 6PBH, reaching the peak values at 24 PBH (TNF-alpha in A and B groups were 1.61 +/- 0.27 ug/L and 1.86 +/- 0.34 ug/L, respectively; IL-6 in A and B groups were 398 +/- 67 ng/L and 572 +/- 97 ng/L, respectively), and they were significantly higher than those in C group at each time points (P < 0.01), meanwhile there was also obvious difference in them between A and B groups (P < 0.01). The lymphatic contents of IL-8 in A and B groups began to increase at 24 PBH, and continued to increase till 48PBH (540.29 +/- 0.32 ng/L in A group, 863.48 +/- 105.16 ng/L in B group), which were evidently higher than those in C group (P < 0.01). There was significant difference in IL-8 contents between A and B groups (P < 0.01). The contraction frequency of the mesenteric lymphatic vessels in A and B groups were decreased, especially so at 24 PBH (P < 0.01). The speed of lymphatic flow in A and B groups was increased at each time points (P < 0.01). The central chylous vessels in the villi of the small intestine were extremely dilated as seen under microscope.</p><p><b>CONCLUSION</b>After burn injury, the lymphatic vessels dilated, with its motility decreased and speed of flow increased, and the contents of TNF-alpha, IL-6 and IL-8 in lymph were increased during the shock stage of burn rats. Fluid resuscitation could improve the lymph circulation.</p>