Proposal of leukotoxin, 9,10-epoxy-12-octadecenoate, as a burn toxin

It is postulated that toxic substances (burn toxin) synthesized in burned skin are transferred into general circulation and cause multiple organ failure. We found a highly cytotoxic substance, leukotoxin, a linoleate epoxide, exists in burned skin. Leukotoxin, as the name indicates, was synthesized by leukocytes from linoleate as a substrate. The aim of this study is to evaluate the possibility of leukotoxin as a burn toxin. We studied plasma leukotoxin level of four patients with extensive burns (over 50% of body surface area) and examined coagulation studies in these patients. We detected considerable amounts of leukotoxin (11.4 nmol/ml-37.0 nmol/ml) in all patients. Leukotoxin was not detected in the control subjects. Pulmonary edema, cardiac failure, and coagulation abnormalities were found in these patients. Exogeneously administered leukotoxin induced similar pathological conditions in experimental animals to those observed in patients with extensive burns. Hence, it is concluded that leukotoxin is a responsible substance as a burn toxin.     

Hypertonic saline dextran after burn injury decreases inflammatory cytokine responses to subsequent pneumonia-related sepsis

The present study examined the hypothesis that hypertonic saline dextran (HSD), given after an initial insult, attenuates exaggerated inflammation that occurs with a second insult. Adult rats (n = 15 per group) were divided into groups 1 (sham burn), 2 [40% total body surface area burn + 4 ml/kg isotonic saline (IS) + 4 ml.kg(-1).% burn(-1) lactated Ringer solution (LR)], and 3 (burn + 4 ml/kg HSD + LR), all studied 24 h after burns. Groups 4 (sham burn), 5 (burn + IS + LR), and 6 (burns + HSD + LR) received intratracheal (IT) vehicle 7 days after burns; groups 7 (burn + IS + LR) and 8 (burn + HSD + LR) received IT Streptococcus pneumoniae (4 x 10(6) colony-forming units) 7 days after burn. Groups 4-8 were studied 8 days after burn and 24 h after IT septic challenge. When compared with sham burn, contractile defects occurred 24 h after burn in IS-treated but not HSD-treated burns. Cardiac inflammatory responses (pg/ml TNF-alpha) were evident with IS (170 +/- 10) but not HSD (45 +/- 5) treatment vs. sham treatment (80 +/- 15). Pneumonia-related sepsis 8 days after IS-treated burns (group 7) exacerbated TNF-alpha responses/contractile dysfunction vs. IS-treated burns in the absence of sepsis (P < 0.05). Sepsis that occurred after HSD-treated burns (group 8) had less myocyte TNF-alpha secretion/better contractile function than IS-treated burns given septic challenge (group 7, P < 0.05). We conclude that an initial burn injury exacerbates myocardial inflammation/dysfunction occurring with a second insult; giving HSD after the initial insult attenuates myocardial inflammation/dysfunction associated with a second hit, suggesting that HSD reduces postinjury risk for infectious complications.     

Temporal cytokine profiles in severely burned patients: a comparison of adults and children

A severe burn leads to hypermetabolism and catabolism resulting in compromised function and structural changes of essential organs. The release of cytokines has been implicated in this hypermetabolic response. The severity of the hypermetabolic response following burn injury increases with age, as does the mortality rate. Due to the relationship between the hypermetabolic and inflammatory responses, we sought to compare the plasma cytokine profiles following a severe burn in adults and in children. We enrolled 25 adults and 24 children who survived a flame burn covering more than 20% of total body surface area (TBSA). The concentrations of 22 cytokines were measured using the Linco multiplex array system (St. Charles, MO, USA). Large perturbations in the expression of pro- and anti-inflammatory cytokines were seen following thermal injury. During the first week following burn injury, IFN-gamma, IL-10, IL-17, IL-4, IL-6, and IL-8 were detected at significantly higher levels in adults compared with children, P < 0.05. Significant differences were measured during the second week post-burn for IL-1beta (higher in children) and IL-5 (higher in adults), P < 0.05. IL-18 was more abundant in children compared with adults during the third week post-burn, P < 0.05. Between post-burn d 21 and d 66, IL-1alpha was detected at higher concentrations in pediatric compared with adult patients, P < 0.05. Only GM-CSF expression was significantly different at all time points; it was detected at lower levels in pediatric patients, P < 0.05. Eotaxin, G-CSF, IL-13, IL-15, IP-10, MCP-1, and MIP-1alpha were detected at significantly different concentrations in adult compared with pediatric patients at multiple time points, P < 0.05. There were no differences in IL-12, IL-2, IL-7, or TNF levels in adult compared with pediatric burn patients at any of these time points. Following severe flame burns, the cytokine profiles in pediatric patients differ compared with those in adult patients, which may provide insight with respect to the higher morbidity rate in adults. Furthermore, the dramatic discrepancies observed in plasma cytokine detection between children and adults suggest that these two patient populations may benefit from different therapeutic interventions to achieve attenuation of the post-burn inflammatory response.     

TIMP-1, MMP-2, MMP-9, and PIIINP as serum markers for skin fibrosis in patients following severe burn trauma

The wound-healing process of patients with severe burns often leads to the formation of extensive fibrotic scars. In this study, serum concentrations of tissue inhibitors of metalloproteinase-1 (TIMP-1), matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9), and amino-terminal propeptide of procollagen type III (PIIINP) were measured by enzyme-linked immunosorbent assay as markers for excessive cicatrization in 22 patients with acute burn injuries. All patients were followed up for 6 months to determine a fibrotic reaction during the wound-healing process after operative treatment using the Burn Scar Index. Blood samples were drawn immediately before the operation; at postoperative days 1, 3, 7, and 14; and 1, 3, and 6 months after the operation. Twenty patients who underwent elective plastic surgical operations served as the control group. There was a significant increase (p < 0.05) of TIMP-1 in the burned patients by the third postoperative day. Later in the follow-up period, the serum concentrations remained at a significantly elevated level (p < 0.05) compared with preoperative values. In comparison with the control group, the postoperative serum concentrations of TIMP-1 of the burned patients were significantly higher (p < 0.05) at any time and correlated with the total body surface area burned at the third and seventh postoperative days (p < 0.05; r2 = 0.46 versus r2 = 0.53) and the Burn Scar Index after 6 months (p < 0.05; r2 = 0.65). Serum levels of MMP-2 and MMP-9 showed a significant elevation (p < 0.05) only between postoperative days 3 and 14 in patients with burn wounds. PIIINP increased significantly (p < 0.05) in the sera of the burned patients at postoperative day 3 and remained significantly elevated up to 6 months after injury. At any time after trauma, PIIINP serum levels were significantly higher (p < 0.05) in the burned patients than in the control group and correlated with the total body surface area burned at postoperative days 3 and 7 (p < 0.05; r2 = 0.41 versus r2 = 0.44) and the Burn Scar Index after 6 months (p < 0.05; r2 = 0.5). Obviously, the physiological balance between matrix metalloproteinases and their endogenous inhibitors is disturbed after burn trauma. The elevated systemic TIMP-1 concentration might contribute to tissue fibrosis, leading to pathological scar formation. The increase of PIIINP after thermal trauma indicates a fibrogenic component of wound healing.     

Coping with severe burns in the early stage after burn injury

This study examined the relationship between coping strategies, anxiety and depression levels and burn injury characteristics in the early phase of the treatment in burn-injured patients. Seventy patients with severe burns were interviewed within two weeks of their burn trauma. Coping strategies were measured by the coping with burns questionnaire (CBQ). Anxiety and depression levels were assessed with the Beck Depression Inventory and the Beck Anxiety Inventory. There were no statistically significant gender differences in various coping strategies. Avoidance was associated with higher levels of anxiety, depression and hopelessness. The percentage of total body surface area (TBSA) and localization of burns were not associated with coping patterns. Implications for the assessment and management of burn injured patients were discussed.     

Burn and smoke inhalation injury in sheep depletes vitamin E: kinetic studies using deuterated tocopherols

To test the hypothesis that burn and smoke injury will deplete tissue alpha-tocopherol and cause its faster plasma disappearance, deuterium-labeled vitamin E was administered to sheep exposed to both surface skin burn and smoke insufflation, which cause injuries similar to those of human victims of fire accidents. Two different protocols were used: (1) deuterated vitamin E was administered orally with food at time 0 (just before injury) or (2) the labeled vitamin E was administered orally with food the day before injury. The animals, which had been operatively prepared seven days before, were anesthetized and then received both 40% body surface area third-degree burn and 48 breaths of cotton smoke or sham injuries. All were resuscitated with Ringer's lactate solution (4 ml/kg/% BSA burn/24 h) and mechanically ventilated. Blood samples were collected at various times after vitamin E dosing. In both studies the depletion of plasma alpha-tocopherol was faster in the injured sheep. The sheep given deuterated vitamin E 24 h before injury had similar maximum alpha-tocopherol concentrations at similar times. The exponential rates of alpha-tocopherol disappearance were 1.5 times greater and half-lives were 12 h shorter (p < 0.05) in the injured sheep. In separate studies, various tissues were obtained from sheep that were sacrificed from 4 to 48 h after injury. The liver alpha-tocopherol concentrations in sheep killed at various times after injury seem to show a linear decrease at a rate of 0.1 nmol alpha-tocopherol/g liver per hour, suggesting that the liver is supplying alpha-tocopherol to maintain the plasma and lung alpha-tocopherol concentrations, but that this injury is so severe the liver is unable to maintain lung alpha-tocopherol concentrations. These findings suggest that alpha-tocopherol should be administered to burn patients to prevent vitamin E depletion and to protect against oxidative stress from burn injury.     

The isolated burned palm in children: epidemiology and long-term sequelae

The isolated burn of the palm is a typical injury in young children. Positioning and splinting in small hands is difficult, and long-term sequelae of these injuries are not uncommon. The objective of the present study was to assess the outcome of palm burns and to identify the risk factors for long-term sequelae. All patients admitted to our hospital affected with isolated palm injuries between January of 1988 and January of 1998 were reviewed. In total, 120 pediatric patients were admitted with isolated palm burns; 110 patients (91.7 percent) had partial-thickness burns, and 10 patients (8.3 percent) had full-thickness burns. Only four patients (3.3 percent) required excision and skin autografting, but all patients whose palms were operated on in the acute phase developed burn contractures. Sixteen patients (13.3 percent) developed palmar contractures, and more than half of them (56 percent) required reconstructive procedures. All palm burns that healed in more than 3 weeks developed scarring and sequelae (p<0.05 compared with no sequelae). Pediatric palmar burns are benign injuries with a low incidence of late sequelae. However, flame and contact burns are more prone to develop scarring. Excision and autografting should be performed on wounds that take over 3 weeks to heal, but it does not prevent late sequelae.     

Fire Season Effects on Flowering Characteristics and Germination of Longleaf Pine (Pinus palustris) Savanna Grasses

Pinus palustris (longleaf pine) savannas depend on contiguous grass cover to facilitate frequent surface fires. Enhanced flowering, seed production, and germination may be linked to season of fires. We assessed the effect of month of prescribed fire (February, April, May, and July) on percentage of plants with flowering culms (FCs%), FC/area, FC/plant, seed production, and germination for five warm seasons, fall‐flowering grasses. Multivariate analysis indicated the response of flowering and fruiting to burn month varied among the grass species. The dominant species, Sporobolus junceus and Schizachyrium scoparium var. stoloniferum, had greater numbers of most flowering characteristics when burnt during April, May, and July. Aristida purpurascens had increased FC/plant after May and July burns. In contrast, Ar. mohrii had the fewest FC/plant and seeds/FC when burnt in July. Germination was greatest (26–60%) for Ar. purpurascens. Seeds collected following July burns for Ar. purpurascens and Ar. ternarius and after May burns for S. junceus were within the highest germination values recorded. Germination of Sc. scoparium var. stoloniferum was very low after February and July burns (≤5%). With Ar. mohrii, only seed collected following February (2%) and April burns (3%) germinated. April, May, and July fires increased seed production of dominant matrix grasses, thus facilitating the potential for recruitment of these species and facilitating seed collection from potential donor sites for ground‐layer restoration projects. Varying prescribed fire burn month captured variation in flowering characteristics among these grasses.     

Estimation of breast burn size

It is the authors' opinion that the size of chest burns on large-breasted women can be significantly underestimated, especially if the methods of calculation rely on burn charts, such as the Lund and Browder burns chart. This latter chart is based on data derived from only three women and eight men. The surface area of the torsos of 60 volunteers (20 men, 20 small-breasted women, and 20 large-breasted women) was measured using two well-established techniques. The torso surface area was divided into two parts: the anterior trunk and the posterior trunk (i.e., torso surface area = posterior trunk + anterior trunk). The anterior trunk was subdivided and the area above the costal margins defined as the pectoral region. These areas were measured separately for each individual. The volunteers' total body surface area was calculated using normograms, based on their weight and height. The area of each torso section was recorded as a percentage of the total body surface area and torso surface area. Whereas the torso surface area/total body surface area ratio did not vary significantly between the groups, the proportion of anterior to posterior trunk size did depend on the sex and on breast size. There was a direct correlation between the woman's bra cup size and the ratio of anterior-to-posterior trunk surface area. A simple chart was therefore derived that estimates the relative size of a woman's torso surface area once her bra cup size is known. Such a chart can be used to improve accuracy in adult female chest burn estimation, when used in conjunction with a burns chart. Breast burns in larger breasted women are underestimated when calculated using current burn charts. We recommend that a correction be made when estimating chest burns in women to account for the increased surface area of the breasts. A chart, such as the one we have developed, could be used in conjunction with a burn chart (e.g., Lund and Browder) to make this correction.     

Gene expression profiles and protein balance in skeletal muscle of burned children after beta-adrenergic blockade

Propranolol, a nonselective beta-blocker, has been shown effective in hypermetabolic burn patients by decreasing cardiac work, protein catabolism, and lipolysis. This study investigates the effect of propranolol on gene and protein expression changes in skeletal muscle of burned children by use of high-density oligonucleotide arrays to establish the genetic profiles and stable isotope technique to quantitate protein synthesis. Thirty-seven children (mean age 9.7 +/- 1.1 yr) were randomized into groups to receive placebo (n = 23) or propranolol (n = 14) titrated to reduce heart rate by 15%. Children had >40% total body surface area burns (mean 43 +/- 5.6%). Protein net balance was determined by stable-isotope infusion technique. Total RNA from muscle biopsies was isolated, labeled, and cRNA hybridized to the HG-U95Av2 Affymetrix array. Mean net balance of protein synthesis and breakdown was -14.3 +/- 12.9 nmol. min-1. 100 ml leg volume-1 for placebo and +69.3 +/- 34.9 nmol. min-1. 100 ml leg volume-1 in the propranolol-treated children (P = 0.012). Comparison of 12,000 genes in burned children receiving placebo showed increased expression of two genes with time, whereas children receiving propranolol showed increased expression of nine genes with a decrease in five genes. We conclude that burned children receiving propranolol showed a significant upregulation in genes involved in muscle metabolism and downregulation of an important enzyme involved in gluconeogenesis and insulin resistance compared with burned children receiving placebo. The upregulation of genes involved in muscle metabolism correlates well with the increase in net protein balance across the leg.     

Prognostic significance of erythroblasts in burns

Changes in hematopoiesis that occur in humans after a burn injury may have important effects on morbidity and mortality. In patients with a variety of severe diseases, the presence of erythroblasts in peripheral blood is known to be indicative of a poor prognosis. However, the prognostic significance of erythroblasts in peripheral blood of burn patients has not yet been estimated. This study included 464 consecutive burn patients, of whom 81 did not survive their injuries (17.5 percent). Together with erythroblasts in blood, data on age, sex, total burn surface area, third-degree burn, inhalation trauma, white blood cell count, C-reactive protein, and hemoglobin were studied. The mortality rate of patients with erythroblasts in peripheral blood (n = 53) amounted to 56.6 percent (n = 30; total burn surface area, 39 percent), which is significantly higher (p < 0.001) than the mortality rate of patients without erythroblasts (12.4 percent, n = 51; total burn surface area, 18.69 percent). None of the 10 patients with more than 1000 erythroblasts x 10/liter survived. The detection of erythroblasts in the peripheral blood of burn patients is highly predictive of death, with the odds ratio after adjustment for the other known prognostic factors being 8.3 (95 percent confidence interval, 4.5 to 15.3). Erythroblasts were detected for the first time on average 10 +/- 4 days (median, 6 days) after admission and 13 +/- 6 days (median, 7 days) before death. Detection of erythroblasts in burn patients is of high prognostic power with regard to in-hospital mortality, providing physicians with a strong prognostic method with which to identify seriously threatened patients. It seems attractive to think about an incorporation of erythroblasts into further refinements of burn scores.     

Bactericidal/permeability increasing protein attenuates the myocardial inflammation/dysfunction that occurs with burn complicated by subsequent infection.

Intubation and mechanical ventilation after burn contribute to pneumonia-related infection. Although postburn presence or absence of endotoxin has been described, inactivation of Toll-like receptor 4 signaling has been shown to improve postburn organ function, suggesting that LPS participates in burn-related susceptibility to infection. We hypothesized that bactericidal/permeability-increasing protein (rBPI) given postburn would attenuate myocardial inflammation/dysfunction associated with postburn septic challenge given 7 days postburn. Rats were given burn over 40% total body surface area, lactated Ringer 4 ml.kg(-1).% burn(-1); burns received either vehicle or rBPI, 1 mg.kg(-1).h(-1) for 48 h postburn. Postburn day 7, subgroups of burns and shams were given intratracheal Klebsiella pneumoniae, 4 x 10(6) CFU to produce burn complicated by sepsis; additional sham and burn subgroups received intratracheal vehicle to produce sham sepsis. Vehicle-treated groups: 1) sham burn + sham sepsis 2) sham burn + sepsis, 3) burn + sham sepsis, 4) burn + sepsis. rBPI-treated groups: 5) sham burn + sham sepsis, 6) sham burn + sepsis, 7) burn + sham sepsis, 8) burn + sepsis. Cardiomyocyte cytokine secretion and myocardial function were studied 24 h after septic challenge, postburn day 8. Pneumonia-related infection 8 days after vehicle-treated burn produced myocyte cytokine secretion (pg/ml), indicated by increased myocyte TNF-alpha, 549 +/- 46; IL-1beta, 50 +/- 8; IL-6, 286 +/- 3 levels compared with levels in sham myocytes (TNF-alpha, 88 +/- 11; IL-1beta, 7 +/- 1; IL-6, 74 +/- 10; P < 0.05). Contractile dysfunction was evident from lower left ventricular pressure +/-dP/dt values in this group compared with sham. rBPI attenuated myocyte cytokine responses to septic challenge and improved contractile function, suggesting that burn-related mobilization of microbial-like products contribute to postburn susceptibility to infection.     

重度烧伤患者细菌感染菌群分布及影响因素

目的 探讨重度烧伤患者细菌感染的菌群分布并分析其影响因素。 方法 选取我院2017年1月-2019年1月收治的重度烧伤患者212例,普通培养烧伤后10~15 d创面分泌物,观察细菌感染菌群分布情况,并从性别、年龄、烧伤深度、烧伤面积、低蛋白血症、糖尿病、早期休克、延迟复苏、血红蛋白尿、吸入性损伤、抗菌药物使用等方面分析重度烧伤患者感染的影响因素。 结果 212例重度烧伤患者中有89例患者发生创面感染,感染率为41.98％。89例发生创面细菌感染患者中:26例感染鲍氏不动杆菌,占29.21％;20例感染金黄色葡萄球菌,占22.47％;17例感染铜绿假单胞菌,占19.10％;12例感染肺炎克雷伯菌,占13.48％;8例感染大肠杆菌,占8.99％;4例感染变形杆菌,占4.49％;2例感染不动杆菌,占2.25％。影响重度烧伤患者细菌感染的单因素有烧伤面积、低蛋白血症、糖尿病、早期休克、延迟复苏、吸入性损伤(P结论 重度烧伤患者易发生细菌感染,感染影响因素有烧伤面积、低蛋白血症、糖尿病、早期休克、延迟复苏、吸入性损伤,临床应针对危险因素积极采取防治措施,控制细菌感染发生率,促进患者康复。     

Vitamin E attenuates acute lung injury in sheep with burn and smoke inhalation injury

Abstract

Introduction: A decrease in α-tocopherol (vitamin E) plasma levels in burn patients is typically associated with increased mortality. We hypothesized that vitamin E supplementation (α-tocopherol) would attenuate acute lung injury induced by burn and smoke inhalation injury.

Materials and Methods: Under deep anesthesia, sheep (33 ± 5 kg) were subjected to a flame burn (40% total body surface area, third degree) and inhalation injury (48 breaths of cotton smoke, < 40°C). Half of the injured group received α-tocopherol (1000 IU vitamin E) orally, 24 h prior to injury. The sham group was neither injured nor given vitamin E. All three groups (n = 5 per group) were resuscitated with Ringer's lactate solution (4 ml/kg/%burn/24 h), and placed on a ventilator (PEEP = 5 cmH₂O; tidal volume = 15 ml/kg) for 48 h.

Results: Plasma α-tocopherol per lipids doubled in the vitamin E treated sheep. Vitamin E treatment prior to injury largely prevented the increase in pulmonary permeability index and moderated the increase in lung lymph flow (52.6 ± 6.2 ml/min, compared with 27.3 ± 6.0 ml/min, respectively), increased the PaO₂/FiO₂ ratio, ameliorated both peak and pause airway pressure increases, and decreased plasma conjugated dienes and nitrotyrosine.

Conclusions: Pretreatment with vitamin E ameliorated the acute lung injury caused by burn and smoke inhalation exposure.     

Our Clinical Experience using Cryopreserved Cadaveric Allograft for the Management of Severe Burns

Human cadaveric allograft is the most commonly used alternative wound closure material for excised burn wounds when limited donor sites or the overall patient condition does not permit immediate grafting with autologous skin. The Skin Bank in Singapore has supplied a total of 33,000 cm² of cryopreserved cadaveric allograft to the Burns Centre in Singapore for the early post-burn treatment of 17 severely burned patients with body surface area (BSA) burn wounds averaging 58% (range 33–90). An average of 13% (range 3–30%) cadaveric allograft was transplanted on 17 patients. Seven patients had recovered from their burn injuries and ten patients died of multiple complications related to their burn injuries. Our clinical observation has shown good adherence of cadaveric allograft when applied on clean and debrided wound bed after 4–7 days of post-operation. The availability of cadaveric allograft permits early excision and wound coverage before the patients' condition is further compromised. Our clinical experience using cryopreserved cadaveric allograft is proving to be indispensable in the management of patients with severe burns. This revised version was published online in July 2006 with corrections to the Cover Date.     

小鼠Ⅲ度烧伤模型的复制及皮肤病理形态改变的动态观察

目的利用近交系小鼠建立方法简便、效果稳定的Ⅲ度烧伤模型,对其皮肤病理改变进行动态观察,为烧伤实验治疗研究提供资料。方法小鼠实验前备毛,乙醚麻醉固定小鼠四肢,苏醒后于备毛部覆盖自制控制烧伤面积硬纸片,滴加95%酒精,点燃计时;烧伤早期和远期取皮肤进行病理检查,用Ki67抗体免疫组化观察细胞增殖。结果按本方法建立小鼠Ⅲ度烧伤模型,面积准确,深度一致,操作简便易行。小鼠烧伤皮肤病理改变与人类基本一致,但有其特点：小鼠Ⅲ度烧伤包括表皮至脂膜肌,烧伤后炎性渗出较晚,约需2 d;创面周围毛发生长活跃,倾向创面,Ki67抗体阳性细胞集中于毛囊底部。结论为利用小鼠烧伤模型进行实验治疗的研究提供了有实用价值的资料。     

Sodium Butyrate Protects against Severe Burn-Induced Remote Acute Lung Injury in Rats

High-mobility group box 1 protein (HMGB1), a ubiquitous nuclear protein, drives proinflammatory responses when released extracellularly. It plays a key role as a distal mediator in the development of acute lung injury (ALI). Sodium butyrate, an inhibitor of histone deacetylase, has been demonstrated to inhibit HMGB1 expression. This study investigates the effect of sodium butyrate on burn-induced lung injury. Sprague–Dawley rats were divided into three groups: 1) sham group, sham burn treatment; 2) burn group, third-degree burns over 30% total body surface area (TBSA) with lactated Ringer’s solution for resuscitation; 3) burn plus sodium butyrate group, third-degree burns over 30% TBSA with lactated Ringer’s solution containing sodium butyrate for resuscitation. The burned animals were sacrificed at 12, 24, and 48 h after burn injury. Lung injury was assessed in terms of histologic changes and wet weight to dry weight (W/D) ratio. Tumor necrosis factor (TNF)-α and interleukin (IL)-8 protein concentrations in bronchoalveolar lavage fluid (BALF) and serum were measured by enzyme-linked immunosorbent assay, and HMGB1 expression in the lung was determined by Western blot analysis. Pulmonary myeloperoxidase (MPO) activity and malondialdehyde (MDA) concentration were measured to reflect neutrophil infiltration and oxidative stress in the lung, respectively. As a result, sodium butyrate significantly inhibited the HMGB1 expressions in the lungs, reduced the lung W/D ratio, and improved the pulmonary histologic changes induced by burn trauma. Furthermore, sodium butyrate administration decreased the TNF-α and IL-8 concentrations in BALF and serum, suppressed MPO activity, and reduced the MDA content in the lungs after severe burn. These results suggest that sodium butyrate attenuates inflammatory responses, neutrophil infiltration, and oxidative stress in the lungs, and protects against remote ALI induced by severe burn, which is associated with inhibiting HMGB1 expression.     

Effects of burn wound excision on bacterial colonization and invasion

Rates of survival after thermal injury have improved in the past two decades, and rates of wound infections and sepsis have decreased during the same period. Early excision has been advocated as one of the major factors, but its safety and efficacy and the exact timing of burn excision are still under debate. It was hypothesized that acute burn wound excision (in the first 24 hours after burning) would be superior to conservative treatment and delayed excision in preventing bacterial colonization and invasion. Twenty consecutive patients with thermal injuries were studied. Twelve patients underwent acute burn wound excision, and eight patients underwent conservative treatment and delayed excision. The second group of patients received topical treatments in another facility and underwent delayed excision after transfer to our service, on postburn day 6. Quantitative bacteriological assessments of the excised wound and biopsy samples of the wound bed, obtained before autografting and/or homografting, were performed. The effects of time on bacterial counts, differences between superficial and deep biopsy samples, and the effects of early versus late debridement were studied. Patients admitted early exhibited bacterial counts of less than 10 bacteria per gram of tissue. Patients in this group did not experience infection or graft loss. Patients admitted late exhibited counts of more than 10 bacteria (p = 0.001, compared with early admission). Three patients in the late excision group experienced infection and graft loss (p < 0.05, compared with the early excision group). Burn wound excision significantly decreased bacterial colonization for all patients (p < 0.001). Greater bacterial colonization and higher rates of infection were correlated with topical treatment and late excision (p < 0.001). It is concluded that burn wound excision significantly reduces bacterial colonization. Patients who undergo topical treatment and delayed burn wound excision exhibit greater bacterial colonization and increased rates of infection. Acute burn wound excision should be considered for all full-thickness burns.     

Effects of Phenology at Burn Time on Post‐Fire Recovery in an Invasive C4 Grass

The spread of non‐indigenous, C₄ grasses threatens global conservation of savannas and subtropical grasslands. Identifying control methods to selectively target these invasives has proven difficult. Here, we tested the hypothesis that the effectiveness of prescribed burns for control is determined, in part, by the phenology of the target species at burn time. We conducted two experiments in a subhumid, C₄ grassland in central Texas. The focal invasive was the C₄, perennial bunchgrass Bothriochloa ischaemum (L.) Keng (KR bluestem). Burns were conducted in early and late fall when plants were in different phenological states. In addition, we attempted to manipulate phenological state through temporary rainout shelters to expedite maturation. The two experiments differed in the timing of the rainout shelter application (experiment 1: May to July, experiment 2: August and September), but otherwise had the same complete factorial design (burn time × shelter). Across experiments, when at least 50% of all tillers were pre‐reproductive at burn time, either due to shelter treatment or time of year, spring tiller densities were significantly lower than when plants were burned in a more advanced reproductive state. Trends in fall biomass generally followed trends in spring tiller densities, with one exception where plants in no‐shelter plots burned in October had lower biomass than expected based on tiller densities. Treatment responses for the native C₄ grass B. laguroides were consistent with those of B. ischaemum. These findings suggest that strategic burns can be used to reduce the subsequent recovery of invasive C₄ grasses while not disadvantaging native grasses.     

Short-term effects of fire frequency on vegetation composition and biomass in mixed prairie in south-western Manitoba

The net effects of one, two, and three spring burns in consecutive yearson the aboveground biomass, species composition, and soil variables wereassessed in two different mixed-grass prairie sites in south-western Manitoba.Precipitation in the first year was greater than the 30-year average but lowerduring the next three years. The first site (Area 6) was characterized byBouteloua gracilis, Stipa spartea,Selaginella densa and lichens, while the second, somewhatdrier site (Area 10) was dominated by B. gracilis andCarex spp. Each burn treatment was applied to 15 plots inarandom block design. Vegetation and soil data collected following the thirdburnare presented. In general, the effects of repeated burning were more pronouncedin the drier Area 10, where litter was significantly reduced with eachadditional burn. In Area 6, litter was significantly reduced only after threeyears of burning. In both sites, the cumulative effect of fire had nosignificant effect on total standing crop, even after three consecutive yearsofburning. In the drier Area 10, however, the biomass of several componentsshifted such that B. gracilis biomass increasedsignificantly and forb biomass decreased significantly after three burns. Plantcover was also affected more in the drier Area 10. The cover of B.gracilis, the dominant C₄ grass, significantly increasedand Carex spp. cover decreased after two burns in thedriersite. In Area 6, the most significant effect of fire was a reduction inSelaginella and lichen cover. Bare ground increased inbothsites as the number of burns increased. There was little change in soilnutrients with burning, but soil moisture somewhat decreased and surfacetemperature significantly increased after three burns.