Cardiac apoptosis in burned rats with delayed fluid resuscitation

Research progress and considerations on oral rehydration therapy for the prevention and treatment of severe burn shock: A narrative review

Severe burns are a significant cause of life-threatening conditions in both peacetime and wartime. Shock is a critical complication during the early stages of burn injury, contributing substantially to mortality and long-term disability. Effective fluid resuscitation is crucial for preventing and treating shock, with prompt administration being vital. However, timely intravenous fluid resuscitation is often challenging, and errors in resuscitation significantly contribute to mortality. Therefore, exploring a more rapid and effective non-invasive method of fluid resuscitation is necessary. Oral rehydration therapy (ORT) has shown considerable potential in this regard. This paper reviews ORT's historical development and current research progress, discussing its application in early anti-shock treatment for burns. While ORT is generally safe, potential complications like diarrhoea, vomiting, and abdominal discomfort must be noted, particularly if the rehydration rate is too rapid or if gastrointestinal issues exist. Careful patient assessment and monitoring are essential during ORT administration. Based on a comprehensive review of relevant research, we present provisional guidelines for ORT in burn patients. These guidelines aim to inform clinical practice but should be applied cautiously due to limited clinical evidence. Implementation must be tailored to the patient's condition under healthcare supervision, with adjustments according to evolving circumstances: ① Initiation timing: Start as soon as possible, and the ideal start time is usually within 6 h after injury. ② Rate of application: Employing a fractional administration approach, wherein small quantities of approximately 150-250 millilitres are provided for each instance and the initial fluid rate of oral rehydration can be simplified to 100 mL/kg/24 h. ③ Composition combination: In addition to essential salts and glucose, the oral rehydration solution can incorporate various anti-inflammatory and cellular protection constituents.

Effects of glycine supplementation on myocardial damage and cardiac function after severe burn

BACKGROUND

Glycine has been shown to participate in protection from hypoxia/reoxygenation injury. However, the cardioprotective effect of glycine after burn remains unclear. This study aimed to explore the protective effect of glycine on myocardial damage in severely burned rats.

METHODS

Seventy-two Wistar rats were randomly divided into three groups: normal controls (C), burned controls (B), and glycine-treated (G). Groups B and G were given a 30% total body surface area full-thickness burn. Group G was administered 1.5 g/(kg d) glycine and group B was given the same dose of alanine via intragastric administration for 3d. Serum creatine kinase (CK), lactate dehydrogenase (LDH), aspartate transaminase (AST), and blood lactate, as well as myocardial ATP and glutathione (GSH) content, were measured. Cardiac contractile function and histopathological changes were analyzed at 12, 24, 48, and 72 hours.

RESULTS

Serum CK, LDH, AST, and blood lactate increased, while myocardial ATP and GSH content decreased in both burned groups. Compared with group B, the levels of CK, LDH, and AST significantly decreased, whereas blood lactate as well as myocardial ATP and GSH content increased in group G. Moreover, cardiac contractile function inhibition and myocardial histopathological damage in group G significantly decreased compared with group B.

CONCLUSION

Myocardial histological structure and function were damaged significantly after burn. Glycine is beneficial to myocardial preservation by improving cardiomyocyte energy metabolism and increasing ATP and GSH abundance.

Myocardial autophagy after severe burn in rats

BACKGROUND

Autophagy plays a major role in myocardial ischemia and hypoxia injury. The present study investigated the effects of autophagy on cardiac dysfunction in rats after severe burn.

METHODS

Protein expression of the autophagy markers LC3 and Beclin 1 were determined at 0, 1, 3, 6, and 12 h post-burn in Sprague Dawley rats subjected to 30% total body surface area 3rd degree burns. Autophagic, apoptotic, and oncotic cell death were evaluated in the myocardium at each time point by immunofluorescence. Changes of cardiac function were measured in a Langendorff model of isolated heart at 6 h post-burn, and the autophagic response was measured following activation by Rapamycin and inhibition by 3-methyladenine (3-MA). The angiotensin converting enzyme inhibitor enalaprilat, the angiotensin receptor I blocker losartan, and the reactive oxygen species inhibitor diphenylene iodonium (DPI) were also applied to the ex vivo heart model to examine the roles of these factors in post-burn cardiac function.

RESULTS

Autophagic cell death was first observed in the myocardium at 3 h post-burn, occurring in 0.008 ± 0.001% of total cardiomyocytes, and continued to increase to a level of 0.022 ± 0.005% by 12 h post-burn. No autophagic cell death was observed in control hearts. Compared with apoptosis, autophagic cell death occurred earlier and in larger quantities. Rapamycin enhanced autophagy and decreased cardiac function in isolated hearts 6 h post-burn, while 3-MA exerted the opposite response. Enalaprilat, losartan, and DPI all inhibited autophagy and enhanced heart function.

CONCLUSION

Myocardial autophagy is enhanced in severe burns and autophagic cell death occurred early at 3 h post-burn, which may contribute to post-burn cardiac dysfunction. Angiotensin II and reactive oxygen species may play important roles in this process by regulating cell signaling transduction.

Apoptosis in cardiac myocytes during the early stage after severe burn

BACKGROUND

Cardiac dysfunction after severe burn is associated with postburn myocardial injury. We hypothesize that myocyte apoptosis is triggered and presented as the pathologic basis of postburn myocardial injury during the early stage after severe burn, and that apoptosis may be related to inflammatory responses in the postburn myocardium.

METHODS

Rats with 40% total body surface area full-thickness burn were used. The following functions were measured at several time points after the burn injury: myocyte apoptosis (TUNEL staining, DNA ladder, and caspase-3 activity assay); mRNA levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (reverse transcriptase-polymerase chain reaction [RT-PCR]); activities of myeloperoxidase and p38 mitogen activated protein (MAP) kinase (Western blots); and left cardiac function.

RESULTS

TUNEL positive myocytes appeared as early as 6-hour and their numbers showed further increases at 12-hour and 24-hour postburn; DNA fragmentation was clearly observed, and caspase-3 activity was significantly increased in the myocardium after burn. Infiltration of neutrophils, evidenced by the levels of myeloperoxidase activity, expression of TNF-alpha, and p38 MAP kinase activity in the heart, were all significantly increased within 24-hour after burn. Cardiac function was decreased after burn, which approximately paralleled the increased amount of cardiac apoptosis.

CONCLUSION

These results demonstrate that cardiomyocyte apoptosis progressively develops during the early stage after severe burn, which may in part contribute to burn-induced cardiac dysfunction. Myocardial inflammatory responses, evidenced by the increased infiltration of neutrophils, as well as production of TNF-alpha probably because of the activation of p38 MAP kinase, may be involved in burn-induced cardiomyocyte apoptosis.

“Systemic apoptotic response” after thermal burns

The systemic pathophysiologic changes following thermal injuries affect multiple organs and body systems leading to clinical manifestations including shock, intestinal alterations, respiratory and renal failure, immunosuppression and others. Recent advances in the comprehension of mechanisms underlying systemic complications of thermal injuries have contributed to uncover part of the cellular and molecular basis that underlie such changes. Recently, programmed cell death (apoptosis) has been considered playing an important role in the development of such pathological events. Therefore, investigators utilizing animal models and clinical studies involving human primates have produced a large body of information suggesting that apoptosis is associated with most of the tissue damages triggered by severe thermal injuries. In order to draw the attention on the important role of apoptosis on systemic complications of thermal injuries, in this review we describe most of these studies, discuss possible cellular and molecular mechanisms and indicate ways to utilize them for the development of therapeutic strategies by which apoptosis may be prevented or counteracted.

Effect of Ligustrazine on liver injury after burn trauma

This study was designed to investigate the effect of Ligustrazine on burn-induced liver injury as well as the activation of nuclear factor kappaB (NF-kappaB) in severely burned rats. Sprague-Dawley rats were divided into three groups: (1) sham group, rats who underwent sham burn; (2) control group, rats given third-degree burns over 30% total body surface area (TBSA) and lactated Ringer solution for resuscitation; (3) Ligustrazine group, rats given burn and lactated Ringer's solution with Ligustrazine inside for resuscitation. Liver injury was assessed at 24 h post-burn by serum levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), as well as liver wet/dry weight ratio. Liver myeloperoxidase (MPO) activity was also analyzed. Hepatic NF-kappaB activity was examined by electrophoretic mobility shift assay (EMSA). Burn results in hepatic dysfunction and increased hepatic NF-kappaB activity, elevated liver wet/dry ratio and hepatic MPO activity. Ligustrazine inhibited these changes and alleviated burn-mediated hepatic dysfunction. The data indicated that Ligustrazine has a protective effect on burn-induced liver injury and possible mechanism may be attributed to its inhibitory action on the activation of NF-kappaB following burn trauma.

Human serum from patients with septic shock activates transcription factors STAT1, IRF1, and NF-kappaB and induces apoptosis in human cardiac myocytes

Proinflammatory cytokines have been linked to depression of myocardial contractility in vivo in patients with acute septic shock and in vitro models employing isolated myocytes exposed to serum from such patients. The key pathways involved in mediating this septic organ dysfunction (cell adhesion molecule expression, inducible nitric-oxide synthase induction, and apoptosis) are known to be regulated by transcription factors STAT1, IRF1, and NF-kappaB. Utilizing a model that mimics human disease, we have demonstrated activation of the transcription factors STAT1, IRF1, and NF-kappaB in human fetal myocytes exposed to human septic serum. Both reporter and electrophoretic mobility shift assays demonstrated a 5-19-fold increase in activation of transcription factors STAT1, IRF1, and NF-kappaB in response to incubation with human septic serum. The addition of human septic serum to human fetal myocytes induced apoptosis in human fetal myocytes and activation of the mitogen-activated protein kinase c-Jun NH -terminal kinase and caspase 1 as measured by Western blot. These data suggest that transcription factor activation and early myocyte apoptosis play a mechanistic role in septic myocardial depression and sepsis-induced organ dysfunction.

Expression and regulation of vascular cell adhesion molecule-1 in human umbilical vein endothelial cells induced by sera from severely burned patients

OBJECTIVE

The purpose of this study was to determine the expression and regulation of vascular cell adhesion molecule (VCAM)-1 in human umbilical vein endothelial cells (HUVECs) induced by sera from severely burned patients.

DESIGN

Controlled laboratory study.

SETTINGS

Research laboratory in a university hospital.

SUBJECTS

HUVECs.

INTERVENTIONS

HUVECs were incubated with serum from eight healthy controls and eight patients with thermal injuries of >50% total body surface area. The experiment was repeated after pretreatment with pyrrolidine dithiocarbamate, an inhibitory effect on nuclear factor-kappaB activation, SB203580, a specific p38 mitogen-activated protein kinase inhibitor, and PD98059, a mitogen-activated protein/extracellular signal-regulated kinase inhibitor.

MEASUREMENTS AND MAIN RESULTS

Protein and messenger RNA expression of VCAM-1 was measured by flow cytometry and reverse transcription-polymerase chain reaction respectively. Soluble VCAM-1 level in HUVECs culture supernatants was measured by enzyme-linked immunosorbent assay. Sera from severely burned patients showed a stimulatory effect on VCAM-1 messenger RNA levels and an increased VCAM-1 expression on the endothelial cell surfaces. The soluble form of VCAM-1 molecules was also elevated by the stimulation of burn sera. In vitro peripheral blood mononuclear leukocytes adherence to HUVECs incubated with burn sera was significantly increased compared with those incubated with control sera. Finally, these events were significantly inhibited by pretreatment with antioxidants pyrrolidine dithiocarbamate or SB203580, whereas PD98059 had no significant effect.

CONCLUSIONS

These findings suggest that sera from severely burned patients induced up-regulation of VCAM-1 expressions in HUVECs, and this process might be largely dependent on oxidant-mediated nuclear factor-kappaB activation and p38 mitogen-activated protein kinase pathways.

Nitric oxide, inflammation and acute burn injury

Nitric oxide (NOz.rad;) is a diatomic mediator liberated on oxidation of L-arginine by the nitric oxide synthase (NOS) family of enzymes. It has complex and wide ranging functions in vivo and has been implicated in the development of the profound inflammatory response that occurs as a result of cutaneous burn injury. In addition, dysregulation of NOS activity has been associated with multiple organ failure in human burn patients and may therefore represent a novel therapeutic target in such circumstances. This review focuses on the role of NOz.rad; in inflammation, with particular emphasis on the acute post-burn inflammatory response. Specific areas of discussion include the maintenance of microvascular haemostasis, leukocyte recruitment and remote organ dysfunction following thermal injury.

Role of p38 mitogen-activated protein kinase in Kupffer cell secretion of the proinflammatory cytokines after burn trauma

This study was designed to investigate the role of p38 mitogen-activated protein (MAP) kinase on Kupffer cells (KCs) secretion of proinflammatory cytokines such as tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta and hepatic injury following burn trauma. Sprague-Dawley rats were randomized into four groups: (1) sham burn rats given vehicle, (2) sham burn rats given the p38 MAP kinase inhibitor SB203580 (10mg/kg i.v., 15min and 12h after sham burn), (3) rats given a 30% total body surface area (TBSA) full-thickness burn and fluid resuscitation plus vehicle, and (4) burn rats given injury and fluid resuscitation plus SB203580. Rats from each group were killed at 24h post-burn to examine plasma aspartate transaminase (AST) and alanine transaminase (ALT) and KCs were isolated. The KCs secretion of TNF-alpha and IL-1beta and p38 MAP kinase activity (by Western blot analysis) were also examined. These studies showed by more significant activation of p38 MAP kinase in KCs harvested from burn rats than from shams. Burn trauma resulted in hepatic dysfunction and promoted KCs secretion of TNF-alpha and IL-1beta. SB203580 inhibited p38 MAP kinase activity, reduced KCs secretion of proinflammatory cytokines, and alleviated burn-mediated hepatic dysfunction. These data suggest p38 MAP kinase activation is one important aspect of the signaling event that may mediate the KCs secretion of proinflammatory cytokines TNF-alpha and IL-1beta following burn trauma.

Apoptotic cell death in the lens epithelium of rat sugar cataract

Apoptosis of lens epithelial cells (LECs) is implicated in the pathogenesis of several types of cataract formation. The high intracellular levels of polyol induce histological change in the LECs, which is considered the earliest event in sugar cataractogenesis. This study was designed to investigate whether high galactose exposure induces apoptosis in LECs during the development of sugar cataract. The effect of an aldose reductase inhibitor, SNK-860, was also examined. We induced sugar cataract in Sprague-Dawley rats by feeding them a 50% galactose-containing diet with or without SNK-860. The percentage of LECs undergoing apoptosis was measured by the terminal deoxynucleotidyl transferase-mediated biotin-dUTP nick-end labeling (TUNEL) method, and DNA fragmentation analyses were performed. Galactitol levels in the lens epithelium were quantified by gas chromatography. The number of TUNEL-positive cells gradually increased throughout the period of galactose exposure, up to 5 days. DNA fragmentation analysis in LECs of rats fed a galactose-rich diet demonstrated an apparent ladder pattern. SNK-860 reduced the percentage of TUNEL-positive cells, the amount of intracellular galactitol, and the levels of DNA laddering. To explore the mechanism of the apoptotic process, the expression of p53, a potent mediator of apoptosis, was examined. Based on Western blot and real-time reverse transcription-polymerase chain reaction results, the amount of p53-expression increased at both the protein and mRNA levels after galactose exposure, and the increase in p53-expression was inhibited by SNK-860. Based on these results, we concluded that apoptosis occurs in rat lens epithelial cells following galactose exposure. Furthermore, the reduction of apoptosis by aldose reductase inhibitor suggests that this apoptosis is associated with the accumulation of sugar alcohols. It is probable that the mechanism of apoptosis during sugar cataract formation involves the increased expression of p53.

Role of p38 mitogen-activated protein kinase in lung injury after burn trauma

This study was undertaken to evaluate the effect of SB203580, a specific p38 mitogen-activated protein (MAP) kinase inhibitor, on burn-induced lung injury as well as the release of tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta in rats to characterize the role of p38 MAP kinase in lung injury after burn trauma. Sprague-Dawley rats were divided into three groups: 1) sham group, or rats who underwent sham burn; 2) control group, or rats given third-degree burns over 30% total body surface area (TBSA) and lactated Ringer solution for resuscitation; and 3) SB203580 group, or rats given burn injury and lactated Ringers solution with SB203580 inside for resuscitation. Pulmonary injury was assessed at 24 h by pulmonary capillary permeability determined with fluorescein isothiocyanate-labeled albumin and lung histologic analysis. TNF-alpha and IL-1beta protein in bronchoalveolar lavage fluid and serum were measured by enzyme-linked immunosorbent assay and p38 MAP kinase was activity determined in lung by Western blot analysis. These studies showed that significant activation of p38 MAP kinase at 24 h postburn compared with control. Burn trauma resulted in increased pulmonary capillary leakage permeability, elevated levels of TNF-alpha and IL-1beta in bronchoalveolar lavage fluid and serum, and worsened histologic condition. SB203580 inhibited the activation of p38 MAP kinase, reduced the levels of TNF-alpha and IL-1beta, and prevented burn-mediated lung injury. These data suggest that p38 MAP kinase activation is one important aspect of the signaling event that may mediate the release of TNF-alpha and IL-1beta and contributes to burn-induced lung injury.