The inhibition of skeletal changes in a rat burn model with a local muscle flap

The effects of early wound closure using a local muscle flap on the development of periosteal new bone formation in a rat burn model were studied. Following a full-thickness burn to one hind limb, periosteal new bone formation along the tibial diaphysis was measured by the use of the fluorochrome agent calcein and an image-analysis system. Prostaglandin E levels, a known inflammatory mediator, from the bone beneath the burn also were measured. Periosteal new bone formation was inhibited by 50 percent in animals that had debridement and wound closure with a gastrocnemius muscle flap and skin graft on postburn day 2 compared to untreated controls or animals closed with skin grafts only. There was a trend toward reduced prostaglandin E measurements from tibial sections in the early closure group compared to untreated controls. This study demonstrates that early wound closure using a local muscle flap inhibits the periosteal new bone formation which is possibly associated with the inflammation in a rat burn model.     

Evaluation of Lyophilised, Gamma-Irradiated Amnion as a Biological Dressing

Burns, non-healing wounds and pressure sores cause extensive damage to the skin leading to infection and loss of precious body fluids. Despite advances in burn management the mortality rate continues to be high and the search for an economical and easily available dressing to control burn wound infection continues. Autologous skin has limited availability and is associated with additional scarring. Conventional dressings require frequent changes which can be painful and may even require anaesthesia.Amnion is an excellent biological dressing and its use in the treatment of burns has special appeal in India as there are religious barriers to the acceptance of bovine and porcine skin.Lyophilised, irradiated amnion provided for the first time in the country by the Tata Memorial Hospital Tissue Bank was evaluated as a temporary biological dressing. It was used to treat 35 patients with burns, 21 patients with bedsores and non-healing ulcers and the skin graft donor sites of 11 patients.The amnion was easy to handle and stuck well to the raw wound bed. An open dressing was used in most of the second degree burns which healed with hyperemia and early pigmentation. In patients with third degree burns, ulcers or skin graft donor sites, closed dressings were used. The exudate and induration were reduced and patients were more comfortable and experienced less pain. There was healthy granulation with good re-epithelialisation. Amnion was not used in patients with infected third degree burns.     

Leukotoxin,a linoleate epoxide: Its implication in the late death of patients with extensive burns

Burn death based on circulatory shock is often encountered after recovery from primary shock in patients with deep and extensive burns,i.e., late death. Several toxic substances have been proposed, however, the responsible substance remains obscure. Since we have found leukotoxin, a highly cytotoxic linoleate epoxide biosynthesized by neutrophils, in the burned skin, in the present study we determined plasma leukotoxin concentrations in various degree of 30 burn patients. C-reactive protein and circulatory white blood cells were also measured. A significantly high mortality rate of patients with extensive burns (burn surface area over 70%) was observed compared with that in patients with burn surface area under 70%, and significantly high leukotoxin concentrations were observed within a week, and 3 weeks after the thermal injury in patients with extensive burns compared with those in patients with burn surface area under 70%. There were two peaks of plasma leukotoxin concentrations,i.e., the early phase (within 1 week) and the late phase (over 1 week) in patients with extensive burns. Plasma leukotoxin concentrations significantly correlated with burn surface area in the early phase, and similar correlations were observed in the late phase. A significantly high mortality rate (61%) of patients with peak leukotoxin concentrations over 30 nmol/ml was observed compared with 8% for those below 30 nmol/ml. Plasma leukotoxin concentration correlated significantly to C-reactive protein concentration, log (leukotoxin nmol/ml)=0.042×C-reactive protein (mg/dl)+0.74, (r=0.83,P<0.01) in the late phase. From these results, it is concluded that leukotoxin is produced in patients with burns particularly in the late phase of extensive burns, and leukotoxin might play an important role in the tissue destructive procedure associated with severe burns.     

Effects of fire on landscape heterogeneity in Yellowstone National Park,Wyoming

Abstract. A map of burn severity resulting from the 1988 fires that occurred in Yellowstone National Park (YNP) was derived from Landsat Thematic Mapper (TM) imagery and used to assess the isolation of burned areas, the heterogeneity that resulted from fires burning under moderate and severe burning conditions, and the relationship between heterogeneity and fire size. The majority of severely burned areas were within close proximity (50 to 200 m) to unburned or lightly burned areas, suggesting that few burned sites are very far from potential sources of propagules for plant reestablishment. Fires that occurred under moderate burning conditions early during the 1988 fire season resulted in a lower proportion of crown fire than fires that occurred under severe burning conditions later in the season. Increased dominance and contagion of burn severity classes and a decrease in the edge: area ratio for later fires indicated a slightly more aggregated burn pattern compared to early fires. The proportion of burned area in different burn severity classes varied as a function of daily fire size. When daily area burned was relatively low, the proportion of burned area in each burn severity class varied widely. When daily burned area exceeded 1250 ha, the burned area contained about 50 % crown fire, 30 % severe surface burn, and 20 % light surface burn. Understanding the effect of fire on landscape heterogeneity is important because the kinds, amounts, and spatial distribution of burned and unburned areas may influence the reestablishment of plant species on burned sites.     

珍珠粉治疗兔眼角膜烫伤作用的实验研究

本文将淡水珍珠粉治疗兔眼角腹烫伤的实验研究所采用的料材、方法、结果进行了总结。实验结果表明:珍珠粉治疗实验性烫伤的兔眼与不用珍珠粉的对照组比较,疗效有显著性差异;从病理切片也见到治疗组组织结趋构向于正常;停药三个月后,治疗组所形成的角膜翳小。     

Experimental study of new polymer dressings in the treatment of burn wounds

Data on the experimental study of a new polymer coverage for treatment of burn wounds are presented in the article. Application of this coverage, which has a tanning and absorbing affect promotes formation of a dry eschar over a burn wound within the first two days after the accident. This allows to perform early chemical necrectomy on the 6-7th day after the accident. Microbiological investigations show that wound dissemination after application of the coverage remains low and is 3.5 +/- 0.1 per. 1.0 g of the tissue.     

Comparative evaluation of aloe vera in the management of burn wounds in guinea pigs

An experimental study was designed using Hartley guinea pigs, who received full-thickness burns covering 3 percent of their body surface area by direct contact with a hot plate. A total of 40 animals were equally divided among four modalities of closed burn wound management as follows: group I: silver sulfadiazine (Silvadine); group II: aloe vera gel extract (Carrington Dermal Wound Gel); group III: salicylic acid cream (aspirin); and group IV: plain gauze occlusive dressing only. The dressings were changed daily, and the size and appearance of each burn wound were recorded until complete healing. On the sixth postburn day, quantitative burn wound cultures were made. The average time to complete healing in the control group was 50 days, and the only significant difference was found in the aloe vera-treated animals, which healed on an average of 30 days (p less than 0.02). Wound bacterial counts were effectively decreased by silver sulfadiazine (p = 0.015) and by aloe vera extract (p = 0.015). From our data it appears that aloe gel extracts permit a faster healing of burn wounds.     

Histochemical study of alkali-burned rabbit anterior eye segment in which severe lesions were prevented by aprotinin treatment

Activities of different enzymes (acid glycosidases, phosphatases, Na+ - K+ -dependent ATPase, proteases, dehydrogenases) and acid glycosaminoglycans were studied by histochemical methods in sections of rabbit anterior eye segments after experimental alkali burn and treatment with aprotinin, an inhibitor of plasmin and other serine proteinases. Solutions of sodium hydroxide (0.25-1.0 M) were applied on corneas using 12-mm-diameter plastic tube for 15-60 s. After wiping with cotton and rinsing with tap water aprotinin solutions were applied in saline (in experimental animals) and saline (in control animals) dropwise in 12-h intervals for a month. Within the first two weeks aprotinin was used at a concentration of 5000 IU/ml. During the subsequent two weeks the aprotinin concentration was reduced to 2500 IU/ml. Striking differences in enzyme activities and in the healing between treated and untreated eyes were found. Without aprotinin, ulcers developed in most corneas within 3 weeks and plasmin was regularly demonstrated in tears and in the aqueous. When aprotinin treatment was started within 24 h after the burn, the number of enzymatically active inflammatory cells was significantly lower, not only in the cornea itself but also in the whole anterior eye segment. With aprotinin treatment no ulcerations and no plasmin in tears and the aqueous were observed and the corneas healed within a month. The healing process started from the zone of enzymatically activated corneal cells in the unburned zone at the corneal periphery. In the regenerating epithelium and endothelium high activities of Na+ -K+ -dependent ATPase, gamma-glutamyltransferase, lactate and succinate dehydrogenases appeared very soon.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reepithelialization of a full-thickness burn from stem cells of hair follicles micrografted into a tissue-engineered dermal template (Integra)

We report a head and neck full-thickness burn injury that was reconstructed with a tissue-engineered dermal template and then early implantation of microdissected hair follicles through the silicone epidermis 12 days after the burn injury. The treatment resulted in complete reepithelialization and a hair-bearing scalp without the need for a split-thickness skin graft. Restoration of the stem cell population, hair growth, and earlier reepithelialization were achieved using this novel micrografting technique, and histologic examination confirmed maturation of a normal skin type over the subsequent 2 years.     

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.     

Lymphopenia-induced homeostatic proliferation of CD8+ T cells is a mechanism for effective allogeneic skin graft rejection following burn injury

Burn patients are immunocompromised yet paradoxically are able to effectively reject allogeneic skin grafts. Failure to close a massive burn wound leads to sepsis and multiple system organ failure. Immune suppression early (3 days) after burn injury is associated with glucocorticoid-mediated T cell apoptosis and anti-inflammatory cytokine responses. Using a mouse model of burn injury, we show CD8+ T cell hyperresponsiveness late (14 days) after burn injury. This is associated with a CD8+ T cell pro- and anti-inflammatory cytokine secretion profile, peripheral lymphopenia, and accumulation of a rapidly cycling, hyperresponsive memory-like CD8+CD44+ IL-7R- T cells which do not require costimulation for effective Ag response. Adoptive transfer of allospecific CD8+ T cells purified 14 days postburn results in enhanced allogeneic skin graft rejection in unburned recipient mice. Chemical blockade of glucocorticoid-induced lymphocyte apoptosis early after burn injury abolishes both the late homeostatic accumulation of CD8+ memory-like T cells and the associated enhanced proinflammatory CD8+ T cell response, but not the late enhanced CD8+ anti-inflammatory response. These data suggest a mechanism for the dynamic CD8+ T cell response following injury involving an interaction between activation, apoptosis, and cellular regeneration with broad clinical implications for allogeneic skin grafting and sepsis.     

Cardiac effects of burn injury complicated by aspiration pneumonia-induced sepsis

Early fluid resuscitation, antimicrobials, early excision, and grafting have improved survival in the early postburn period; however, a significant incidence of pneumonia-related sepsis occurs after burn injury, often progressing to multiple organ failure. Recent studies have suggested that this initial injury (burn injury) primes the subject, producing an exaggerated response to a second insult, such as pneumonia-related sepsis. We developed an experimental animal model that included a third-degree burn over 40% of the total body surface area, followed by sepsis (intratracheal administration of Streptococcus pneumoniae, 4 x 106 colony-forming unit), which was produced either 48 or 72 h after burn injury in adult male rats. Hearts harvested after either burn alone, sepsis alone, or burn plus sepsis were used to assess either contractile function (Langendorff) or cardiomyocyte secretion of tumor necrosis factor-alpha, interleukin (IL)-1beta, IL-6, and IL-10 (ELISA). Experimental groups included the following: 1). sham (sham burn and no sepsis); 2). burn injury alone studied either 24, 48, or 72 h postburn; 3). pneumonia-related sepsis in the absence of burn injury; and 4). pneumonia-induced sepsis studied either 48 or 72 h after an initial burn injury. Burn injury alone (24 h) or sepsis alone produced myocardial contractile defects and increases in pro- and anti-inflammatory cytokine secretion by cardiomyocytes. Sepsis that occurred 48 h postburn exacerbated the cardiac contractile defects seen with either burn alone or sepsis alone. Sepsis that occurred 72 h postburn produced contractile defects resembling those seen in either burn alone or sepsis alone. In conclusion, our data suggest that burn injury primes the subject such that a second insult early in the postburn period produces significantly greater cardiac abnormalities than those seen with either burn alone or sepsis alone.     

The effect of prescribed burning on plant rarity in a temperate forest

Rare species can play important functional roles, but human‐induced changes to disturbance regimes, such as fire, can inadvertently affect these species. We examined the influence of prescribed burns on the recruitment and diversity of plant species within a temperate forest in southeastern Australia, with a focus on species that were rare prior to burning. Floristic composition was compared among plots in landscapes before and after treatment with prescribed burns differing in the extent of area burnt and season of burn (before–after, control‐impact design). Floristic surveys were conducted before burns, at the end of a decade of drought, and 3 years postburn. We quantified the effect of prescribed burns on species grouped by their frequency within the landscape before burning (common, less common, and rare) and their life‐form attributes (woody perennials, perennial herbs or geophytes, and annual herbs). Burn treatment influenced the response of rare species. In spring‐burn plots, the recruitment of rare annual herbs was promoted, differentiating this treatment from both autumn‐burn and unburnt plots. In autumn‐burn plots, richness of rare species increased across all life‐form groups, although composition remained statistically similar to control plots. Richness of rare woody perennials increased in control plots. For all other life‐form and frequency groups, the floristic composition of landscapes changed between survey years, but there was no effect of burn treatment, suggesting a likely effect of rainfall on species recruitment. A prescribed burn can increase the occurrence of rare species in a landscape, but burn characteristics can affect the promotion of different life‐form groups and thus affect functional diversity. Drought‐breaking rain likely had an overarching effect on floristic composition during our study, highlighting that weather can play a greater role in influencing recruitment and diversity in plant communities than a prescribed burn.     

Analysis of Travelling Waves Associated with the Modelling of Aerosolised Skin Grafts

A previous model developed by the authors investigates the growth patterns of keratinocyte cell colonies after they have been applied to a burn site using a spray technique. In this paper, we investigate a simplified one-dimensional version of the model. This model yields travelling wave solutions and we analyse the behaviour of the travelling waves. Approximations for the rate of healing and maximum values for both the active healing and the healed cell densities are obtained. PACS 92B05     

Fine-scale genetic structure and fire-created habitat patchiness in the Australian allodapine bee, Exoneura nigrescens (Hymenoptera: Apidae)

Fire promotes an abundance of nest sites for the stem nesting bee Exoneura nigrescens, which remain viable for approximately 10 years. The finite duration of nesting substrate and localized fire events suggest that migration should minimize genetic structure among suitable habitat patches. Exoneura nigrescens was sampled from 7 localities with a known fire history in southwestern Victoria, Australia. Individual bees were genotyped at 8 microsatellite loci and genic and genotypic analyses applied to examine genetic structure among burn patch localities, within burn patches, and within colonies. Despite relatively short-term availability of nesting substrates, remarkably fine-scale genetic structure was observed both among burn patches and within burn patches. The spatial distribution of relatedness shows a strong pattern of isolation-by-distance at geographic distances to 35 km, suggesting that genetic partitioning among burn patches is, at least in part, a result of dispersal ability. Genetic structure within burn patches includes colonies consisting of close kin with genic partitioning among nests. Relatedness structure within colonies suggests that polygamy, multiple breeding pairs, and a lack of inbreeding typifies the mating system.     

Des-acyl-ghrelin (DAG) normalizes hyperlactacidemia and improves survival in a lethal rat model of burn trauma

Critical illness, including burn injury, results in elevated plasma lactate levels. Dysregulation of PI3K/Akt signaling has been shown to play a predominant role in the inactivation of skeletal muscle PDC and, hence, in hyperlactacidemia in rat models of sepsis and endotoxemia. This observation, and our previous finding that DAG can reverse burn-induced skeletal muscle proteolysis through the activation of PI3K/Akt pathway, led us to hypothesize that DAG may also attenuate hyperlactacidemia in burn injury. Our investigations revealed that burn injury significantly elevated both skeletal muscle lactate production and plasma lactate levels. Moreover, this was accompanied in skeletal muscle by a 5–7 fold increase in mRNA expression of pyruvate dehydrogenase kinases (PDK) 2 and 4, and a ∼30% reduction in PDC activity. DAG treatment of burn rats completely normalized not only the mRNA expression of the PDKs and PDC activity, but also hyperlactacidemia within 24 h of burn injury. DAG also normalized epinephrine-induced lactate production by isolated skeletal muscles from normal rats. Moreover, DAG also improved survival in a lethal rat model of burn trauma. These findings with DAG may have clinical implications because chances of survival for critically ill patients are greatly improved if plasma lactate levels are normalized within 24 h of injury.     

Enhancement of dendritic cell production by fms-like tyrosine kinase-3 ligand increases the resistance of mice to a burn wound infection

Fms-like tyrosine kinase-3 ligand (Flt3L) is a hemopoietic cytokine that stimulates the production of dendritic cells. This study evaluated the ability of Flt3L-enhanced dendritic cell production to increase the resistance of mice to a burn wound infection with Pseudomonas aeruginosa, a common source of infections in burn patients that have impaired immunity and are susceptible to opportunistic microorganisms. Treatment of mice with Flt3L for 5 days caused a significant increase in dendritic cell numbers in the spleen and significantly increased survival upon a subsequent burn wound infection. Improved survival in Flt3L-treated mice was associated with limited bacterial growth and spread within the burn wounds and a decrease in systemic dissemination of P. aeruginosa. Resistance to burn wound infection could also be conferred to recipient mice by the adoptive transfer of dendritic cells that had been isolated from spleens of Flt3L-treated mice. Adoptive transfer of the same number of splenic dendritic cells from nontreated mice did not confer resistance to burn wound infection. These data indicate that Flt3L can increase the resistance of mice to a P. aeruginosa burn wound infection through both stimulation of dendritic cell production and enhancement of dendritic cell function.     

Fetal fracture healing in a lamb model.

A large animal model to assess fetal fracture repair and the ability to close excisional bony defects is presented. Incisional and excisional ulnar fractures were made in 14 midgestation fetal lambs, harvested at serial time points, and subjected to high-resolution low-kilovolt magnification radiographs, magnetic resonance imaging scans, and histologic analysis. Fetal fracture healing was characterized by early closure of excisional defects and rapid fracture healing with minimal or no soft-tissue inflammation or callus formation. Magnetic resonance imaging scans of the fractures revealed a characteristic pattern compatible with the histologic findings, namely, minimal inflammation in soft tissue adjacent to the fracture site. Histologic and magnification radiographic findings indicated that complete bony repair occurred within 21 days in incisional defects and within 40 days in excisional defects. In both cases, healed fetal bone resembled normal bone matrix. Excisional defects, including periosteum, of greater than three times the width of the bony cortex closed rapidly with virtually normal-appearing bony matrix and with minimal or no callus formation.     

抗内毒素Fab’对严重烧伤早期肠源性内毒素血症小鼠NO、MDA与iNOS的影响及意义

目的：观察抗内毒素Fab’对严重烧伤早期肠源性内毒素血症小鼠肠组织中NO、iNOS、MDA水平的影响,探索防治烧伤脓毒症的新措施。方法：采用严重烧伤早期肠源性内毒素血症小鼠模型,分为烧伤组、治疗组及对照组,分别于6、12、24、48h4个时相点测定肠组织中NO、iNOS、MDA的浓度：结果：烧伤后肠组织中NO、iNOS、MDA水平均比正常对照组显著增高;治疗组肠组织中NO、iNOS、MDA水平较烧伤组显著降低。结论：抗内毒素Fab’能减轻内毒素对机体的损害,从而起到对严重烧伤早期肠源性脓毒症的防治作用。     

Burn injury initiates a shift in superantigen-induced T cell responses and host survival

Severe injury induces a temporal shift in immune reactivity that can cause serious complications or even death. We previously reported that mice exposed to bacterial superantigen (SAg) early after injury undergo a strong SAg response with lethal consequences. This study compares the early and late effects of burn injury on SAg reactivity in vivo to establish how injury influences adaptive immune responses. We found that mice challenged with ordinarily sublethal doses of staphylococcal enterotoxin A or staphylococcal enterotoxin B at 1 day after burn injury exhibited high mortality, whereas no mortality occurred at 7 days after injury. This shift in mortality correlated with higher Th2-type cytokines (IL-4 and IL-10) being expressed by CD4(+) and CD8(+) T cells from burn as opposed to sham mice at 7 days after injury. Lymph node cells from burn-injured mice also produced higher levels of Th2-type cytokines at 7 days after injury. The results of cell-mixing studies using CD4(+) and CD8(+) T cells mixed with APCs from sham or burn mice suggested that changes in both T cells and APCs are involved in the altered SAg response. Finally, the biological significance of altered SAg reactivity following injury was shown by demonstrating that blocking IL-10 activity in vivo caused higher SAg-induced mortality at 7 days after injury. These findings support the idea that injury promotes a Th2-type shift in adaptive immune reactivity. Although prior studies link this counterinflammatory-type response to lowered resistance to infection, the present results suggest it may sometimes benefit the injured host.