[Mechanisms of early gastro-intestinal ischemia after burn: hemodynamic and hemorrheologic features]

OBJECTIVE

To study the mechanisms of early gastro-intestinal ischemia developed in acute burn period and its relationships with hemodynamic and hemorrheologic changes.

METHODS

Twelve pigs were randomly allocated into two groups: group C, a sham group that was subjected to all surgical procedures except burn; group B, 30% TBSA cutaneous thermal injury, and was resuscitated with Parkland formula one hour after burn.

RESULTS

MAP remained stable after burn, but RAP, MPAP, PAWP and CI decreased significantly to the lowest level 4-8 hours after burn, and recovered after resuscitation 24 hours postburn. Intramucosal pH declined immediately (1 hour after burn) and remained abnormal throughout observation period. Portal venous blood flow demonstrated similar changes as pHi, and correlated well with intestinal pHi. Whole blood viscosity and plasma viscosity in portal venous blood elevated obviously after burn.

CONCLUSIONS

1. GI ischemia occurred early and recovered slowly during burn shock phase with conventional resuscitation regime. 2. GI ischemia correlated significantly with portal venous blood flow, but did not with systemic hemodynamic variables. 3. Hemorheologic changes in portal venous blood may exaggerate ischemia injuries.

[Relationship between plasma D(-)-lactate levels and acute intestinal injury in rats following ischemia-reperfusion]

OBJECTIVE

To determine the kinetics of plasma D(-)-lactate levels in both portal and systemic circulations, and to examine whether elevated plasma D(-)-lactate would correlate to intestinal injury in rats subjected to acute intestinal ischemia-reperfusion.

METHODS

Anesthetized rats underwent 75 minutes of superior mesenteric artery occlusion followed by 6 hours of reperfusion. Plasma D(-)-lactate levels were measured by an enzymatic spectrophotometric assay.

RESULTS

It showed that intestinal ischemia for 75 minutes resulted in a significant elevation in D(-)-lactate levels in portal vein blood compared to baseline values (P < 0.05). Plasma D(-)-lactate levels had a tendency to further increase after reperfusion up to 6 hours. Similar alterations in D(-)-lactate were also found in systemic circulation, there were no significant differences between the portal and systemic circulation at any time point. Moreover, the histopathological evaluation scores were significantly correlated to the portal D(-)-lactate levels in animals at various time points (r = 0.415, P < 0.01). In addition, a remarkable rise of endotoxin concentration within portal vein was already found at the end of 75-minute ischemia (P < 0.05), reaching a peak at 2 hours post-reperfusion.

CONCLUSION

These data suggest that acute intestinal ischemia is associated with failure of mucosal barrier resulting in increased plasma D(-)-lactate levels in both portal and systemic blood. The subsequent reperfusion might cause further increase in D(-)-lactate levels, which correlated to the histopathological alterations. Plasma D(-)-lactate may be a useful marker of intestinal injury following both ischemia and reperfusion insults.

Opposing effects of Jun kinase and p38 mitogen-activated protein kinases on cardiomyocyte hypertrophy

c-Jun N-terminal protein kinase (JNK) and p38, two distinct members of the mitogen-activated protein (MAP) kinase family, regulate gene expression in response to various extracellular stimuli, yet their physiological functions are not completely understood. In this report we show that JNK and p38 exerted opposing effects on the development of myocyte hypertrophy, which is an adaptive physiological process characterized by expression of embryonic genes and unique morphological changes. In rat neonatal ventricular myocytes, both JNK and p38 were stimulated by hypertrophic agonists like endothelin-1, phenylephrine, and leukemia inhibitory factor. Expression of MAP kinase kinase 6b (EE), a constitutive activator of p38, stimulated the expression of atrial natriuretic factor (ANF), which is a genetic marker of in vivo cardiac hypertrophy. Activation of p38 was required for ANF expression induced by the hypertrophic agonists. Furthermore, a specific p38 inhibitor, SB202190, significantly changed hypertrophic morphology induced by the agonists. Surprisingly, activation of JNK led to inhibition of ANF expression induced by MEK kinase 1 (MEKK1) and the hypertrophic agonists. MEKK1-induced ANF expression was also negatively regulated by expression of c-Jun. Our results demonstrate that p38 mediates, but JNK suppresses, the development of myocyte hypertrophy.

The role of gut as a cytokine-generating organ in remote organ dysfunction after intestinal ischemia and reperfusion

OBJECTIVE

To test the hypothesis that in a rat model of acute intestinal ischemia/reperfusion injury, endotoxemia from the gastrointestinal tract would play a role in mediating tumor necrosis factor (TNF) response and remote organ dysfunction.

METHODS

Wistar rats underwent 45 minutes of superior mesenteric artery occlusion followed by 6 hours of reperfusion. The rats were treated intravenously with either TNF monoclonal antibody (MoAb) or saline solution 90 minutes prior to the onset of ischemia.

RESULTS

Significant elevation of plasma TNF level in both portal and systemic circulation was detected immediately after the onset of reperfusion. The level peaked at two hours after reperfusion (P < 0.01). Similarly, a remarkable TNF mRNA expression in the intestine in controls was detected at 0.5 hour post-reperfusion, and sustained a marked elevation throughout the observation period (P < 0.05-0.01). TNF elevation was found associated with gut-origin endotoxemia, and the maximal TNF response occurred approximately 0.5-2 hours after the initial appearance of endotoxin in the portal vein. Concomitantly, multiple organ dysfunction in response to local ischemic insult was also observed in untreated controls upon reperfusion, but it was significantly attenuated by pretreatment with MoAb against TNF.

CONCLUSIONS

Intestinal injury can result in the gut becoming a cytokine-liberating organ. The escape of endotoxin and bacteria from the gut may be responsible for the TNF expression and release, which would be an important mechanism underlying pathophysiological alterations associated with intestinal ischemia/reperfusion injury.

The effects of fibroblast growth factors on ischemic kidney, liver and gut injuries

OBJECTIVE

To explore the possibility of reducing reperfusion injuries of internal organ with acidic and basic fibroblast growth factors (aFGF and bFGF).

METHODS

Two kinds of ischemia and reperfusion animal models were used in this study. In rat model of superior mesenteric artery (SMA) occlusion, microvascular clamp was placed on the root of SMA to cut off the blood flow for 45 minutes, and then the clamp was removed. In rat model of bilateral renal ischemia and reperfusion, both renal arteries were clipped to get complete cessation of blood flow for 60 minutes, then the blood flow was allowed to return. At the onset of reperfusion, the doses of 4.0 micrograms/rat of bFGF in SMA occluded rats or 2.6 micrograms/rat of aFGF in rats with acute renal injury were administered through the jugular vein. The liver and renal function examination, tissue bacterial study and histopathological evaluation were done to evaluate the treatment results.

RESULTS

The functional impairment of ischemic liver, gut and kidney were reduced with venous administration of aFGF or bFGF at the onset of reperfusion. The results of pathological and tissue bacterial examination supported the assertion of significant protective effects of FGFs.

CONCLUSIONS

The protective effects of FGFs may come from the non-mitogenic effects of FGFs at the early and the mitogenic effects at the late stage of tissue repair. These results indicate a potential for clinical use of FGFs as a therapeutic modality in ischemic visceral organ injuries in the future.

[Clinical guidelines for timing of escharectomy and skin grafting during burn shock stage in extensively burned patients]

OBJECTIVE

To provide practical clinical guidelines to doctors who have no hemodynamic monitoring facilities in performing escharectomy during the shock period in extensively burned patients.

METHODS

We analyzed our clinical experiences in 60 patients with extensive burn.

RESULTS

Puting forward several clinical indexes for timing of escharectomy during burn shock stage: 1. Amount of fluids in the first 24 h postburn 2.6-3.0 ml.kg-1.1% TBSA-1; 2. Output of urine 80-100 ml/h; 3. Mentally fully conscious; 4. Thirst significantly alleviated and there is no nausea and vomiting; 5. Pulse 100/min; 6. Hb < or = 150 g/L; 7. Hct < or = 0.50.

CONCLUSION

With the clinical indexes as guidelines, we assume that escharectomy could be performed during burn shock stage with reasonable safety.

[Fatal complications in traffic accident injury]

OBJECTIVE

To discuss the relative factor, development tendency and prevention of the fatal complications in traffic accident injury.

METHOD

We observed injury severity scale (AIS-ISS), clinical response time, and occurrence in traffic accident injury with fatal complications. Ridit mathematical statistics and Q test were used.

RESULT

There were high ISS and long clinical response time in traffic accident injury with fatal complications. A significant relation was found between complications and the progress of time after trauma, thereby the clinical course could be divided into phases of cerebral hernia and shock (or acute), transition, infection and multiple organ dysfunction syndrome (MODS). There was higher head AIS in the cerebral hernia. ISS of shock patients was significantly higher than that of the others. Massive infections occurred in the patients with extremity trauma. There was a significant relation between the occurrence of MODS and infection.

CONCLUSION

The occurrence of fatal complications is related to the location and severity of injury in traffic accident injury. A regularity is present in the occurrence of fatal complications with time progress.

Study on delay two-phase multiple organ dysfunction syndrome

OBJECTIVE

To study the injury factors, pathogenic process and clinical features of delay two-phase multiple organ dysfunction syndrome (MODS) in severe burned patients and to replicate a standardized animal model that would accurately imitate the clinical features of MODS.

METHODS

Forty-five human patients with burn size larger than 30% total body surface area (TBSA) were analyzed. All of them underwent severe burn shock in early stage and sepsis in late stage. Thirty-two goats were randomly divided into three groups: 1) hemorrhagic shock (group H, n = 6); 2) endotoxemia (group E, n = 6); and 3) hemorrhagic shock plus endotoxemia (group M, n = 20). Hemorrhagic shock was produced according to the method of Wigger (6.7 kPa for an hour, 1 kPa = 7.5 mmHg). Endotoxin (E. coli O111 B4) was given via the portal vein 24 hours after the resuscitation of hemorrhagic shock, in a dose of 30 ng/kg/min for 5 consecutive days. During the observation period of 10 days, all animals were hemodynamically monitored, given standard metabolic support and due cardiac and pulmonary support according to human intensive care.

RESULTS

All the patients showed burn shock at 1-3 days and hyperdynamic circulation, hypermetabolism and systemic inflammatory responses over two weeks post-injury. Thirteen cases were found to develop MODS according to the prevailing diagnostic criteria, and 10 of them died with a mortality of 77%. Eighteen animals died in group M with a mortality of 90%, 12 of the 18 developed MODS, with overall incidence of 60%. Most animals in group M showed changes similar to that observed in human cases. The experimentation proved that in the pathogenic process of MODS, there was a two-hit phenomenon in the dvelopment of the syndrome. To prevent the development of MODS, it therefore was imperative to blunt the first hit or the second hit, so that an excessive inflammatory response was alleviated. This postulation has been verified in the treatment of extensive burns. Two patients with burn extent reaching 100% TBSA survived with only mild acute respiratory distress syndrome (ARDS) and renal dysfunction after comprehensive treatment of burn shock, including adequate fluid resuscitation, drugs to remove oxygen free radicals, rapid restoration of pHi, and early extensive excision of burn eschars.

CONCLUSION

Both in human patients or animal experimentation, the typical delay two-phase MODS is shown to be produced by two successive insults in the forms of hypovolemic shock and sepsis. This postulation is helpful in formulating the prevention and treatment modality of MODS.

Epidemiological study of chronic dermal ulcers in China

A total of 30,000 hospitalized surgical patients in 15 hospitals were screened for chronic ulcers. A total of 489 patients with chronic dermal ulcers were found with their major causes of ulceration including traumatic wounds, infections, diabetes mellitus, and venous diseases. Patients with chronic ulcers following trauma and infection comprised 67.48% of the total patient population. The incidence of diabetic ulcers and venous ulcers was 4.91% and 6.54% respectively. Sites of ulceration differed with different etiological factors. The percentage of chronic dermal ulcers in the lower extremities, upper extremities, thorax and abdomen, back, and head was 63.10%, 17.93%, 7.76%, 4.83% and 6.38% respectively. Of the 489 patients with chronic ulcers, 183 were farmers (37.42%), and 131 were workers (26.79%). Chronic dermal ulcers were more common in men than in women, but there was no significant difference in the sex-related prevalence. According to these data from different hospitals, the incidence of chronic ulcers in patients hospitalized for surgery was 1.5% to 3.0%. These data have primarily shown the prevalence and clinical characteristics of chronic ulcers in hospitalized patients in China. These data may not be consistent with reports from other countries. Significant differences in etiological factors of ulceration, professional distribution of patients with chronic dermal ulcers, and treatment methods were found when compared with reports of studies conducted in developed countries. Our results will benefit not only additional basic research, but these data will also be useful in preventing and managing chronic wounds in developing countries.

Evidence for interaction between transmembrane segments in assembly of Kv1.3

Previously, we showed that the N-terminal recognition domain (T1) of Kv1.3 was not required for assembly of functional channels [Tu et al. (1996) J. Biol. Chem. 271, 18904-18911]. Moreover, specific Kv1.3 peptide fragments including regions of the central core are able to inhibit expression of current produced from a channel lacking the T1 domain, Kv1.3(T1-). To elucidate the mechanism whereby Kv1.3 peptide fragments suppress Kv1.3(T1-) current, we have studied the ability of peptide fragments containing the transmembrane segments S1, S1-S2, or S1-S2-S3 to physically associate with the Kv1.3(T1-) polypeptide subunit in vitro in microsomal membranes. Using c-myc (9E10) epitope-labeled peptide fragments and anti-myc antibody as well as antisera to the Kv1.3 C-terminus, we now demonstrate specific association of these peptide fragments with Kv1.3(T1-). Association of peptide fragments with Kv1.3(T1-) was correlated with integration of both proteins into the membrane. Furthermore, the relative strength and kinetics of this association directly correlated with the ability of fragments to suppress Kv1.3(T1-) current. The rate-limiting step in the sequential synthesis, integration, and formation of a complex was the association of integrated polypeptides within the plane of the lipid bilayer. These results strongly suggest that the physical association of transmembrane segments provides the basis for suppression of K+ channel function by K+ channel peptide fragments in vivo. Moreover, the S1-S2-S3 peptide fragment potently suppressed full-length Kv1.3, thus implicating a role for the S1-S2-S3 region of Kv1.3 in the assembly of the Kv1.3 channel. We refer to these putative association sites as IMA (intramembrane association) sites.

[Water vapor permeability measurement of the materials used as a wound covering]

This paper introduces a new apparatus and method that suits to measuring the water vapor transmission rate (WVTR) of wound covering materials. WVTR of synthetic materials, amniotic membrane, porcine and cadaveric skin was measured under different conditions of four temperatures, three mediums, and "water cup" or "inverted water cup". The temperature was in close relationship with the WVTR except Omiderm, amniotic membrane, and cadaveric skin between 30 degrees C and 37 degrees C groups. The medium did not affect the WVTR (P > 0.05). There was significant difference between the "water cup" and "inverted water cup" groups(P < 0.01). This study suggests that the apparatus is easy-to-operate, reliable and suitable for the measurement of WVTR of burn wound coverings and other membranous materials.

[Serum neopterin levels after extensive burns and their relationship to endotoxemia and sepsis]

The present study was performed to determine the kinetics of serum neopterin levels after major thermal injury and their relationship to endotoxemia and sepsis. This prospective study included 35 patients (32 males and three females) with total burn surface area (TBSA) greater than 30% (30%-98%), and 22 healthy volunteers who served as normal controls. The results showed that neopterin levels increased in most patients on day 3 postburn, but they were not significantly correlated with the extent of the burn surface (P > 0.05). Patients with endotoxemia had much higher neopterin values than those who showed no endotoxemia from the second week onward (P < 0.05-0.01), and circulating endotoxin and neopterin levels were positively correlated in patients who developed endotoxemia on day 14 (r = 0.368, P < 0.05) and day 21 (r = 0.439, P < 0.01) after major burns. Moreover, a high serum neopterin level was found in patients with sepsis (n = 15), and the marked elevation persisted throughout the observation period. The difference between septic and non-septic patients (n = 20) became significant on 14 and 28 days postburn. These data suggest that extensive burns can lead to an elevation of serum neopterin independent of TBSA. The endotoxin release in the circulation may be involved in the continuous formation of neopterin during the late postburn stage. In addition, the presence of a constant high neopterin level is associated with a critical event in the development of burn sepsis.

[Effect of recombinant bactericidal/permeability-increasing protein on pulmonary cytokine mRNA expression in rats following hemorrhage and resuscitation]

To determine the possible mechanisms underlying beneficial effect of recombinant bactericidal/permeability-increasing protein (rBPI) on acute lung injury response to blood loss, we used reverse transcription polymerase chain reaction to measure pulmonary tumor necrosis factor (TNF), interleukin 6 (IL-6) mRNA expression in a rat model of prolonged hemorrhagic shock (4.00 kPa, 180 min) followed by adequate resuscitation. The results showed that systemic plasma endotoxin concentrations elevated rapidly after a 180-min hemorrhagic insult (P < 0.05), and TNF, IL-6 mRNA expression in the lung were significantly increased at 2, 8 hours after resuscitation respectively. However, treatment with rBPI resulted in almost neutralization of plasma endotoxin values, remarkable reduction of TNF, IL-6 mRNA levels following hemorrhage/resuscitation. Also, it was found that rBPI administration markedly blunted the increase in pulmonary Evans blue dye extravasation, concomitant with a significant decrease in lung myeloperoxidase activity compared with the control group (P < 0.05-0.01). These data suggest that local proinflammatory cytokine mRNA expression associated with gut origin endotoxemia may be an important mechanism contributing to the development of hemorrhage-induced lung injury. Treatment with rBPI is effective in inhibiting marked TNF, IL-6 mRNA expression and ameliorating acute lung injury secondary to severe hemorrhagic shock.

[The relationship between abnormalities of cell-mediated immunity and gut origin endotoxemia in a rat model of thermal injury]

This study was conducted to determine the relationship between abnormalities of cell-mediated immunity and gut-derived endotoxemia in rats following burns. Animals were subjected to a 40% full-thickness scald injury, and randomly divided into control and selective decontamination of the digestive tract (SDD) treated groups. It was found that thermal injury resulted in marked reductions in splenocyte proliferative response to concanavalin A or phytohemagglutinin, interleukin 2 (IL-2) production, and T helper/suppressor (Th/Ts) cells ratio. Prophylactic treatment with SDD significantly reduced the incidence of endotoxemia, prevented suppressive mitogenic response and inadequacy in IL-2 production (P < 0.05-0.01), but did not affect the abnormal ratio of Th/Ts in blood (P > 0.05). We conclude that bacteria/endotoxin translocation from the gastrointestinal tract appears to be involved in cellular immune dysfunction after thermal injury. Pretreatment with SDD might attenuate systemic immunosuppression by preventing translocation events.

Basic fibroblast growth factor reduces the gut and liver morphologic and functional injuries after ischemia and reperfusion

OBJECTIVE

To explore the possible effects of basic fibroblast growth factor (bFGF) on ischemic gut and liver injuries after trauma.

METHODS

Animal models of superior mesenteric artery occlusion (45 minutes) and reperfusion (3 days) were used in this study. Seventy-two Wistar rats were divided into three groups of 24 rats each. The animals in bFGF-treated group were injected with 4 microg bFGF/rat in 0.15 mL normal saline solution containing heparin 0.1% (w/v) through the jugular vein at the onset of reperfusion. In the normal saline control group, all rats received the same vehicle, but without bFGF. Group 3 (sham-operated) underwent the same laparotomy procedure, but without superior mesenteric artery occlusion. Liver function parameters, the levels of serum tumor necrosis factor alpha, nitric oxide, superoxide dismutase, malondialdehyde (MDA), tissue bacterial examination, and pathologic study were used to evaluate the results.

RESULTS

In bFGF-treated rats, the amounts of serum alanine transaminase and aspartate aminotransferase and serum tumor necrosis factor-alpha were reduced significantly at 6, 24, and 48 hours when compared with normal saline-treated rats. However, the changes in nitric oxide, superoxide dismutase, and MDA varied from each other as a function of time after injury. The amounts of nitric oxide were increased significantly at 6 hours in intestine in normal saline-treated rats and in liver in bFGF-treated rats (p < 0.05). At 6 hours after reperfusion, the activity of superoxide dismutase in normal saline-treated rats were much lower in liver than those in bFGF-treated and sham-operated rats (p < 0.05), but the levels of MDA were increased in intestine in bFGF-treated rats and in liver in normal saline-treated rats when compared with sham-operated rats (p < 0.05). At 24 hours, the levels of MDA in normal saline-treated rats were much higher than those in both bFGF and sham-operated rats (p < 0.05). Bacterial examination revealed that the ratio and the amounts of bacterial translocation from gut to liver, spleen, and mesenteric lymph nodes in bFGF-treated rats were much lower than those in normal saline-treated rats. The results of pathologic study support the assumption that bFGF provided protective effects against reperfusion injury.

CONCLUSIONS

Intravenous administration of bFGF may benefit in reducing gut and liver injuries after ischemia and reperfusion. The mechanisms of those effects may involve mitogenic and nonmitogenic effects of bFGF.

[Study on transposition behavior of IS5376 in Bacillus stearothermophilus]

IS5376 and IS5377 are two transposable elements discovered in Bacillus stearothermophilus. Analysis of random samples revealed that the frequency of transposition of IS5376 from CU21 chromosome to plasmids pFDC5 and pFDC12 was much higher at 65 degrees C than that at 48 degrees C while that of IS5377 was very low at both 48 degrees C and 65 degrees C. The exact nature of the temperature effect is obscure at present from evidences obtained so far it is concluded that this is a consequence of the innate property of IS5376. Furthermore, it was found that a certain degree of site specificity in transposition was evident and that a direct repeat of 4 or 5 bp of the target DNA appeared at the site of transposition.

[Measurement of urinary content of lactulose and mannitol by gas chromatography as an index of permeability of the gut]

We established lactulose-mannitol(L-M) measurement method by gas chromatography and 9202 computer data processing system to test intestinal permeability. The urine output of L-M was in linear correlation to its sample concentration within working range. In an animal model of acute pancreatitis, lactulosesecretion increased in urine, together with increased L/M ratio. The measurement of lactulose-mannitol intestinal permeability by our method might serve as a predictor for early diagnosis of endogenous infection and sepsis.

Cardiotrophin 1 (CT-1) inhibition of cardiac myocyte apoptosis via a mitogen-activated protein kinase-dependent pathway. Divergence from downstream CT-1 signals for myocardial cell hypertrophy

Cardiac myocyte survival is of central importance in the maintenance of the function of heart, as well as in the development of a variety of cardiac diseases. To understand the molecular mechanisms that govern this function, we characterized apoptosis in cardiac muscle cells following serum deprivation. Cardiotrophin 1 (CT-1), a potent cardiac survival factor (Sheng, Z., Pennica, D., Wood, W. I., and Chien, K. R. (1996) Development (Camb.) 122, 419-428), is capable of inhibiting apoptosis in cardiac myocytes. To explore the potential downstream pathways that might be responsible for this effect, we documented that CT-1 activated both signal transducer and activator of transcription 3 (STAT3)- and mitogen-activated protein (MAP) kinase-dependent pathways. The transfection of a MAP kinase kinase 1 (MEK1) dominant negative mutant cDNA into myocardial cells blocked the antiapoptotic effects of CT-1, indicating a requirement of the MAP kinase pathway for the survival effect of CT-1. A MEK-specific inhibitor (PD098059) (Dudley, D. T., Pang, L., Decker, S.-J., Bridges, A. J., and Saltiel, A. R. (1995) Proc. Natl. Acad. Sci. USA 92, 7686-7689) is capable of blocking the activation of MAP kinase, as well as the survival effect of CT-1. In contrast, this inhibitor did not block the activation of STAT3, nor did it have any effect on the hypertrophic response elicited following stimulation of CT-1. Therefore, CT-1 promotes cardiac myocyte survival via the activation of an antiapoptotic signaling pathway that requires MAP kinases, whereas the hypertrophy induced by CT-1 may be mediated by alternative pathways, e.g. Janus kinase/STAT or MEK kinase/c-Jun NH2-terminal protein kinase.

Oxygen free radical injury and its relation to bacterial and endotoxin translocation after delayed fluid resuscitation: clinical and experimental study

OBJECTIVE

To examine whether there is generation of oxygen free radicals (OFR) and lipid peroxidation of cell membrane after volume replacement for burn shock, and to study the relationship between OFR injury and enterogenous endotoxemia.

METHODS

Forty-seven burn patients were involved in this study. Among them, 18 had delayed fluid resuscitation (DR) and the others had early fluid resuscitation (ER) within 6 hours postburn. Sixty-six gnotobiotic rats were used in a collaborating experiment as burn models. They were divided into 4 groups: sham injury (n = 6), early resuscitation (n = 24), late resuscitation (n = 24) and vitamins E and C treatment group (n = 12). All the rats, except those in the sham injury group, were inflicted with 40% total body surface area (TBSA) third-degree burns. OFR was determined in the blood of patients with electron spin resonance (ESR). S/W ratio and tau c values of patients' erythrocytes were measured with ESR spectrometer. Blood superoxide dismutase (SOD) and glutathione peroxidase (GSHPx) activities, malondialdehyde contents and plasma endotoxin levels were assayed. Rats were sacrificed at the 12th, 24th, 48th and 72nd hour after injury. Plasma endotoxin levels, mucosal SOD, GSHPx and malondialdehyde (MDA), as well as diamine oxidase activity of ileum were determined. Cultures of mesenteric lymph nodes (MLN), liver, spleen, heart, lung, kidney and blood were done.

RESULTS

A significant increase in blood OFR contents and plasma MDA, and a significant decline in blood SOD and GSHPx were found after resuscitation in DR group as compared with those in ER group. Both strong to weak spectra component (S/W) ratio and tau c value were higher in DR group in contrast with those in ER group. Higher elevation in plasma endotoxin level in DR group was seen. In DR group, plasma MDA content was correlated with S/W ratio, tau c value and plasma endotoxin level. In rats, the level of mucosal MDA, plasma endotoxin and incidence of bacterial translocation (BT) were significantly higher. Mucosal SOD, GSHPx and diamine oxidase (DAO) activity were significantly lower in DR group as compared with those in ER group. In DR group, mucosal MDA content was negatively correlated with mucosal DAO activity, while the latter was negatively correlated with BT. After treatment with vitamins E and C, mucosal MDA content decreased, plasma endotoxin and BT significantly declined and mucosal DAO heightened.

CONCLUSIONS

Tissue reperfusion might induce the production of OFR, resulting in lipid peroxidation injury, especially to intestinal mucosa, and resulting in disruption of mucosal barrier function followed by endotoxemia and BT.

The relationship between gut-derived endotoxemia and tumor necrosis factor, neopterin: experimental and clinical studies

OBJECTIVE

To determine the relationship between gut-derived endotoxemia and tumor necrosis factor (TNF), neopterin/biopterin formation following hemorrhage, trauma and burns.

METHODS

Rats were subjected to hemorrhagic shock (30 mmHg, 90-180 min) and 40% III degrees thermal injury. Circulating endotoxin, TNF, biopterin levels and liver TNF mRNA expression were measured in animals following acute insults. Also, the subjects of this study included 35 patients with burn size greater than 30%, and 25 patients with multiple injuries (n = 18) and major surgery (n = 7).

RESULTS

It was found that significant portal and systemic endotoxemia took place in the control animal after hemorrhagic shock and thermal injury, but almost not in the animals that treated by measures aiming at controlling endotoxin/bacteria translocation, including polymyxin B, monoclonal antibody against core lipopolysaccharide, and selective decontamination of the digestive tract (SDD). Concomitantly, hemorrhage and thermal injury resulted in significant increases in systemic plasma TNF level together with tissue TNF mRNA expression, which were associated with the initial appearance of endotoxin in portal vein. However, anti-endotoxin treatment markedly decreased circulating TNF level as well as peak TNF mRNA expression caused by acute insults. There were also lower serum biopterin values in the SDD-treated group as compared with the control group on day 5 postburn. On the other hand, the results showed that the amounts of plasma endotoxin in patients increased during the early stages following major burns, which was significantly correlated with plasma TNF levels, particularly in patients who developed sepsis and multiple organ failure. Although the presence of early endotoxemia did not influence the alterations in serum neopterin, patients with endotoxemia had much higher neopterin values than those who showed no endotoxemia from the second week onward.

CONCLUSION

These results suggest that gut-derived endotoxemia could account, at least in part, for the inflammatory mediators formation and release, which might be involved in the pathogenesis of sepsis and multiple organ dysfunction following severe hemorrhage, trauma and burns.

Voltage-gated K+ channels contain multiple intersubunit association sites

A domain in the cytoplasmic NH2 terminus of voltage-gated K+ channels supervises the proper assembly of specific tetrameric channels (Li, M., Jan, J. M., and Jan, L. Y.(1992) Science 257, 1225-1230; Shen, N. V., Chen X., Boyer, M. M., and Pfaffinger, P. (1993) Neuron 11, 67-76). It is referred to as a first tetramerization domain, or T1 (Shen, N. V., Chen X., Boyer, M. M., and Pfaffinger, P.(1993) Neuron 11, 67-76). However, a deletion mutant of Kv1.3 that lacks the first 141 amino acids, Kv1.3 (T1(-)) forms functional channels, suggesting that additional association sites in the central core of Kv1.3 mediate oligomerization. To characterize these sites, we have tested the abilities of cRNA Kv1.3 (T1(-)) fragments co-injected with Kv1.3 (T1(-)) to suppress current in Xenopus oocytes. The fragments include portions of the six putative transmembrane segments, S1 through S6, specifically: S1, S1-S2, S1-S2-S3, S2-S3, S2-S3-S4, S3-S4, S3-S4-S5, S2 through COOH, S3 through COOH, S4 through COOH, and S5-S6-COOH. Electrophysiologic experiments show that the fragments S1-S2-S3, S3-S4-S5, S2 through COOH, and S3 through COOH strongly suppress Kv1.3 (T1(-)) current, while others do not. Suppression of expressed current is due to specific effects of the translated peptide Kv1.3 fragments, as validated by in vivo immunoprecipitation studies of a strong suppressor and a nonsuppressor. Pulse-chase experiments indicate that translation of truncated peptide fragments neither prevents translation of Kv1.3 (T1(-)) nor increases its rate of degradation. Co-immunoprecipitation experiments suggest that suppression involves direct association of a peptide fragment with Kv1.3 (T1(-)). Fragments that strongly suppress Kv1.3 (T1(-)) also suppress an analogous NH2-terminal deletion mutant of Kv2.1 (Kv2.1 (DeltaN139)), an isoform belonging to a different subfamily. Our results indicate that sites in the central core of Kv1.3 facilitate intersubunit association and that there are suppression sites in the central core, which are promiscuous across voltage-gated K+ channel subfamilies.

[Effect of escharectomy during burn shock stage on bacterial and endotoxic translocation from the gut]

120 SPF rats (Wistar) were randomly divided into 3 groups (1) simple skin grafting group (Group A). (2) Escharectomy during burn shock group (Group B). (3) Routine escharectomy group (Group C) Full-thickness burn of 30% TBSA was produced in Group B and Group C. One hour after scald intravenous fluid replacement was instituted. First stage escharectomy has been performed 24 hours after burn and 5 days postburn. The results demonstrated that the contents of both plasma LPS and TNF in Group B were significantly lower as compared with these in Group C. Our data indicated escharectomy during burn shock would effectively eliminate the effects of the endotoxemia. Endotoxin play an important role in the bacterial and endotoxic translocation.

Multiple organ injuries and failures caused by shock and reperfusion after gunshot wounds

Experiments were performed to observe the changes of multiple system organ failure (MSOF) and gut barrier function caused by shock and reperfusion after gunshot wounds. Eighteen dogs were divided randomly into two groups. In the experimental group, the dogs were subjected to 60 minutes of shock (40mm Hg), followed by reinfusion of shed blood after hindlimb gunshot wounds. In the control group, the dogs experienced pure gunshot wounds without shock and reperfusion. The results showed that dogs in the experimental group developed multiple system organ injuries or failures compared with the control group. The levels of malondialdehyde (MDA) values in plasma were significantly elevated in the experimental group when compared with preinjury and the control group. Gut flora disorder, bacillus intestinalis overgrowth, and bacterial translocation occurred in the experimental group. The pathological results support the gut barrier function injury. The results indicated that pure gunshot wounds do not easily injure gut barrier function and produce MSOF. Gunshot wounds with shock and reperfusion are capable of causing gut flora disorder, bacillus intestinalis overgrowth, and lead to bacterial translocation, furthermore causing MSOF. Although fluid resuscitation is a potential treatment modality, pathogenically, it can lead to MSOF.

In vivo effects of tumor necrosis factor-alpha on incised wound and gunshot wound healing

Recombinant tumor necrosis factor alpha (TNF-alpha) was applied to incised wounds (adult rats, n = 14) and gunshot wounds (dogs, n = 5). The accumulation of RNA and DNA in regenerative tissue, the wound disruption strength (WDS), and histology were examined. The results showed that a single dose of TNF-alpha in saline with highly purified bovine serum albumin increased the WDS and accumulation of RNA and DNA in regenerative tissue in incised wounds 3 days after surgery (p < 0.05). Also, TNF-alpha promoted the inflammatory reaction in the wounded area of gunshot wounds. Histology revealed increased capillary tube-like structures and collagen formation and fibroblast proliferation in both incised and gunshot wounds treated with TNF-alpha. The results indicated that locally applied TNF-alpha benefited the incised and gunshot wound healing. These mitogenic and inflammatory effects of TNF-alpha may be the synergistic effects with other growth factors such as platelet-derived growth factor (PDGF).