Successful management of the cervicothoracic esophagus reconstruction by expanded skin flap.

The limited availability of reconstruction materials can often make it difficult to treat defects in the esophagus caused by necrosis of the transplanted intestinal tissue after cervicothoracic esophagus reconstruction. We were forced to perform flap reconstruction on a patient who suffered necrosis due to impeded blood flow of the transplanted intestinal tract after twice conducting cervicothoracic esophagus reconstruction with an intestinal tract flap. The procedure we performed was esophagus reconstruction using a pectoralis major myocutaneous flap that had been expanded with a tissue expander due to the small volume of tissue available to perform the reconstruction. This case suggested that esophagus reconstruction with a skin flap using a tissue expander should be considered as a possible treatment choice when performing reconstruction of the cervicothoracic esophagus, which requires stable blood flow and a large amount of tissue.

Endoscopic transmaxillary repair of orbital floor fractures: a minimally invasive treatment.

Although endoscopic transmaxillary repair of orbital floor fractures is a minimally invasive treatment, controversy remains regarding the method for supporting the orbital floor after elevation of the orbital contents. To date, a urethral balloon catheter has been widely used. However, it can be difficult to leave the catheter in place for a long time period due to the inconvenience, and prolapse of the orbital contents may recur in the case of its premature removal. This study described the techniques for endoscopic reduction and use of a balloon for orbital floor fractures. From June 2006 through November 2011, 30 of 52 patients (57.7%) with an isolated orbital floor fracture underwent endoscopic transmaxillary repair. A maxillary sinus balloon (#3007, Koken Co., Japan) was inserted into the maxillary sinus to support the orbital floor after endoscopic transmaxillary reduction, and the connecting tube of the balloon was pulled into the nasal cavity through the maxillary ostium. After confirmation of accurate reduction by postoperative CT, the connecting tube was shortened and hidden in the nasal cavity. The balloon was left in place for 4-8 weeks, and then removed via the maxillary ostium on an outpatient basis. Complete resolution of the preoperative diplopia was achieved in 93%, and no late-developing enophthalmos was seen in 97% of the patients. There were no significant complications. This technique is safe and permits prolonged retention of the balloon, without interfering with daily life.

Wound dressing material containing lyophilized allogeneic cultured cells.

Although topical application of a single growth factor is known to accelerate wound healing, treatment with allogeneic cultured cells is more efficient and physiological, because they release various mediators that interact and regulate the wound healing mechanism. However, in clinics, the cells must be cryopreserved until use. To overcome this inconvenience, we designed novel wound dressing materials containing lyophilized allogeneic cultured epithelial cells and/or fibroblasts. This study aimed to confirm growth factor release from those lyophilized products. The results revealed that the cultured cells retained their morphology even after lyophilization and released growth factors. When fibroblasts were used alone, they released growth factors in significantly higher concentrations after lyophilization than after cryopreservation. In particular, bFGF release was almost a hundredfold higher in the lyophilized group compared to the cryopreserved group. When epithelial cells and fibroblasts were co-cultured, both bFGF and VEGF were released in higher concentrations by the cryopreserved dressing material than by the lyophilized dressing material. The growth factors' release was probably regulated by interaction between epithelial cells and fibroblasts. We speculate that repeated application may be necessary for treating difficult wounds with the lyophilized product, because the lyophilized cells release the mediators in a single, transient burst.

False-negative monitoring flap in free jejunal transfer.

We treated a case that exhibited dissociation between blood flow in the transferred jejunum and the monitoring flap. The monitoring flap showed a false-negative, indicating blood flow to be favorable despite blood congestion in the transferred jejunum. The patient was a 69-year-old man. After tumor resection, reconstruction was performed with free jejunal transfer. Vascular anastomosis was performed on the jejunal artery and transverse cervical artery and on the jejunal vein (V1) and external jugular vein. After esophagus anastomosis, blood congestion was noted in the transferred jejunum. An engorged arcade vein (V2) was observed in the mesenterium on the transferred jejunum side. Therefore, it was anastomosed to the external jugular vein bifurcation. The first postoperative day, thrombus had formed in the vein (V2). The transferred jejunum side vein (V2) was re-anastomosed to the external jugular vein, and improved blood flow was observed in the transferred jejunum. Monitoring transferred jejunum blood flow with monitoring flap exteriorization appears to be a simple and highly reliable method. However, because the monitoring flap cannot directly evaluate transferred jejunum blood flow, blood flow obstruction can occur between the transferred jejunum and the true situation may not be reflected.

Administration of poly(ADP-ribose) polymerase inhibitor into bronchial artery attenuates pulmonary pathophysiology after smoke inhalation and burn in an ovine model.

Poly(ADP-ribose) polymerase (PARP) is well known to be an enzyme that repairs damaged DNA and also induces cell death when overactivated. It has been reported that PARP plays a significant role in burn and smoke inhalation injury, and the pathophysiology is thought to be localized in the airway during early stages of activation. Therefore, we hypothesized that local inhibition of PARP in the airway by direct delivery of low dose PJ-34 [poly(ADP-ribose) polymerase inhibitor] into the bronchial artery would attenuate burn and smoke-induced acute lung injury. The bronchial artery in sheep was cannulated in preparation for surgery. After a 5-7 day recovery period, sheep were administered a burn and inhalation injury. Adult female sheep (n=19) were divided into four groups following the injury: (1) PJ-34 group A: 1h post-injury, PJ-34 (0.003mg/kg/h, 2mL/h) was continuously injected into the bronchial artery, n=5; (2) PJ-34 group B: 1h post-injury, PJ-34 (0.03mg/kg/h, 2mL/h) was continuously injected into bronchial artery, n=4; (3) CONTROL GROUP: 1h post-injury, an equivalent amount of saline was injected into the bronchial artery, n=5; (4) Sham group: no injury, no treatment, same operation and anesthesia, n=5. After injury, all animals were placed on a ventilator and fluid resuscitated equally. Pulmonary function as evaluated by measurement of blood gas analysis, pulmonary mechanics, and pulmonary transvascular fluid flux was severely deteriorated in the control group. However, the above changes were markedly attenuated by PJ-34 infusion into the bronchial artery (P/F ratio at 24h: PJ-34 group A 398±40*, PJ-34 group B 438±41*†‡, Control 365±58*, Sham 547±47; * vs. sham [p<0.05], † vs. control [p<0.05], ‡ vs. PJ-34 group A [p<0.05]). Our data strongly suggest that local airway production of poly(ADP-ribose) polymerase contributes to pulmonary dysfunction following smoke inhalation and burn.

Preliminary report of novel technique for cryopreservation--vacuum-assisted cryoprotectant infiltration.

To date, cryopreservation of large soft tissues has not been successfully achieved because of limitation of cryoprotective agent (CPA) infiltration into the tissue. This study aimed to investigate the effects of a vacuum on the tissue-infiltration of a CPA. An instant pickle-maker was modified for use as a vacuum apparatus, and glycerol was selected as the CPA. Twenty-six rats were used, and their thighs were divided into three treatment groups. Group 1: fresh control; Group 2: cryopreserved control, i.e., immersed in the CPA for 1h under atmospheric pressure and cryopreserved; Group 3: vacuum-assisted CPA infiltration, i.e., immersed in the CPA under negative pressure (20, 40 and 60 cmHg, for durations of 10, 20 and 30 min at each) and cryopreserved. The Groups 2 and 3 specimens were thawed after 3 weeks of cryopreservation at -80 °C and histologically examined, in comparison with Group 1. Skin: in Groups 2 and 3, the skin was well preserved. Muscle: in Group 2, both extracellular and intracellular ice crystal formation was widely distributed throughout the muscle tissue. In Group 3, under an adequate vacuum, the muscle tissue was well preserved, with no ice crystal formation. However, when the treatment was conducted under excessive vacuum conditions, the muscle tissue showed focal necrosis. Blood vessels: in Group 3, both the arteries and veins were well preserved up to the tunica intima. The method described in this paper may be a useful technique for achieving cryopreservation of large soft tissues.

Activated nuclear factor kappa B and airway inflammation after smoke inhalation and burn injury in sheep.

In a recent study, we have shown a rapid inflammatory cell influx across the glandular epithelium and strong proinflammatory cytokine expression at 4 hours after inhalation injury. Studies have demonstrated a significant role of nuclear factor kappa B in proinflammatory cytokine gene transcription. This study examines the acute airway inflammatory response and immunohistochemical detection of p65, a marker of nuclear factor kappa B activation, in sheep after smoke inhalation and burn injury. Pulmonary tissue from uninjured sheep and sheep at 4, 8, 12, 24, and 48 hours after inhalation and burn injury was included in the study. Following immunostaining for p65 and myeloperoxidase, the cell types and the percentage of bronchial submucosal gland cells staining for p65 and the extent of myeloperoxidase stained neutrophils in the bronchial submucosa were determined. Results indicate absence of detection of P65 before 12 hours after injury. At 12 hours after injury, strong perinuclear staining for p65 was evident in bronchial gland epithelial cells, macrophages, and endothelial cells. Bronchial submucosal gland cells showed a significant increase in the percentage of cells stained for p65 compared with uninjured animals and earlier times after injury, P < .05. At 24 and 48 hours after injury, p65 expression was evident in the bronchiolar epithelium, Type II pneumocytes, macrophages, and endothelial cells. Quantitation of the neutrophil influx into the bronchial submucosa showed a significant increase compared with uninjured tissue at 24 and 48 hours after injury, P < .05. In conclusion, immunohistochemical detection of activated p65 preceded the overall inflammatory response measured in the lamina propria. However, detection of p65 did not correlate with a recent study showing rapid emigration of neutrophils at 4 hours postinjury. Together, these results suggest that p65 immunostaining may identify cells that are activated to produce proinflammatory cytokines after injury; however, the immunoexpression may not adequately reflect the temporal activation of gene transcription that may occur with proinflammatory cytokine production with inhalation injury.

Plasma and tissue vitamin E depletion in sheep with burn and smoke inhalation injury.

Oxidants are involved in the pathogenesis of many disorders caused by burn and smoke inhalation; alpha- and gamma-tocopherols are major tissue antioxidants, and their depletion should reflect oxidant injury. To determine whether plasma and tissue vitamin E levels would thus be depleted in severe burn, prepared sheep were randomly divided into the following groups: non-injured, burn- and smoke-exposed, burned only and smoke-exposed only. All were resuscitated with Ringer's lactate solution, mechanically ventilated and sacrificed at various time intervals. Immediately following injury plasma, lung, trachea, heart and liver tocopherols/lipids were measured and found to be significantly depleted except in the heart. Reduction of tissue gamma-tocopherol appeared earlier than reduction of alpha-tocopherol. Thus animals receiving combined burn and inhalation injury underwent marked oxidative stress, suggesting that vitamin E might be depleted also in humans with burn and smoke inhalation injury, and that appropriate supplementation should be evaluated.

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

INTRODUCTION: A decrease in alpha-tocopherol (vitamin E) plasma levels in burn patients is typically associated with increased mortality. We hypothesized that vitamin E supplementation (alpha-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 degrees C). Half of the injured group received alpha-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 alpha-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.

Skin nitric oxide and its metabolites are increased in nonburned skin after thermal injuries.

Local and systemic inflammation can lead to progression of burn wounds, converting second- to third-degree wounds or extending the burn to adjacent areas. Previous studies have suggested that the skin is an important site of production of nitric oxide (NO), synthesized by inducible nitric oxide synthase (iNOS) activation after injury. NO increases in burned wounds, but its formation in noninjured skin has not been investigated. We hypothesized that after severe burns, NO and cytotoxic peroxynitrite would increase in noninjured skin. We also tested the hypothesis that BBS-2, a specific inhibitor of iNOS, would impair NO formation after burn. Thirteen female sheep were randomized into burn injury and smoke inhalation (n = 5, group 1), burn and smoke treated with BBS-2 (n = 3, group 2), and sham (saline treatment, no injury) (n = 5, group 3). All the animals, including the sham-injury group, were mechanically ventilated for 48 h. Samples of nonburned skin and plasma were collected from each animal, and levels of NO and its metabolites were evaluated using a NO chemiluminescent detector. Nitrotyrosine and iNOS expression were determined in the skin by Immunoperoxidase staining, and scoring of masked slides (epidermis, hair follicles, vessels, glands, and stroma) was performed. Skin NO and metabolites significantly increased in the burn and smoke injury group, and this was inhibited by BBS-2. Nitrotyrosine expression also increased significantly in the skin of burned animals. BBS-2 prevented the increase of NOx but not the increase of nitrotyrosine expression in skin. Plasma levels of NO increased in burned animals when compared with sham, but this increase was not significant. The increase of NO and its metabolites after burn in noninjured skin is followed by a significant increase in peroxynitrite, a potent cytotoxic mediator.

Inhibition of poly (ADP-ribose) polymerase attenuates acute lung injury in an ovine model of sepsis.

It is known that in various pathophysiological conditions, reactive oxidants cause DNA strand breakage and subsequent activation of the nuclear enzyme poly(ADP ribose) polymerase (PARP). Activation of PARP results in cellular dysfunction. We hypothesized that pharmacological inhibition of PARP reduces the damage in the ovine model of acute lung injury (ALI). After smoke inhalation, Pseudomonas aeruginosa (5 x 109 cfu/kg) was instilled into both lungs. All of the animals were mechanically ventilated with 100% O2. The infusion of the PARP inhibitor (INO-1001, n = 6) began 1 h after the injury and thereafter through 24 h (3 mg bolus + 0.3 mg/kg/h, i.v.). Control animals (n = 6) were treated with saline. Sham injury animals (n = 8) received sham smoke and were mechanically ventilated in the same fashion. One-half of those sham animals (n = 4) were given the same dose of INO-1001. PaO2/FiO2 ratio at 24 h in saline and in the INO-1001-treated groups were 95 +/- 22 and 181 +/- 22, respectively (P < 0.05). Peak airway pressure at 24 h in the saline- and INO-1001-treated groups was 32.6 +/- 3.0 and 24.4 +/- 2.2, respectively (P < 0.05). Pulmonary shunt fraction was also significantly attenuated. INO-1001 treatment reduced pulmonary histological injury and attenuated poly (ADP-ribose) accumulation in the lung. In conclusion, inhibition of PARP improved the ALI after smoke inhalation and pneumonia. The results suggest that the activation of PARP plays a role in the pathophysiology of ALI in sheep.

Pyridoxalated haemoglobin polyoxyethylene conjugate, a nitric oxide scavenger, decreases dose-limiting hypotension associated with interleukin-2 (IL-2) therapy.

Interleukin-2 (IL-2), a cytokine that induces natural killer cells termed lymphokine-activated killer (LAK) cells, is in use as an anticancer agent. During IL-2 therapy, adverse effects, such as vasodilatation and hypotension, are common. Previous studies suggest that these effects are due to nitric oxide (NO). Therefore a model of IL-2-induced hyperdynamic response in sheep was developed to test the effect of pyridoxalated haemoglobin polyoxyethylene conjugate (PHP; a NO scavenger), which is currently in clinical development for the treatment of shock associated with systemic inflammatory response syndrome. Twelve female sheep were divided into four groups (n =3 per group): sham control (Ringer's lactate solution), PHP alone (20 mg x kg(-1) x h(-1) for 96 h), IL-2 alone (recombinant human IL-2; 1,440,000 units/kg intravenously every 8 h) and a combination of PHP and IL-2. All of the sheep received Ringer's lactate solution to maintain haematocrit at baseline levels. The sheep had free access to food and water. A fall in the mean arterial pressure and systemic vascular resistance index by 20% was observed in the IL-2 group, but not in the PHP+IL-2 group. The fluid requirement to maintain the haematocrit was higher in the IL-2 group (5 ml x kg(-1) x h(-1)) than in the PHP+IL-2 group (4 ml x kg(-1) x h(-1)). The sham group showed no changes in any of the parameters. Scavenging NO by PHP prevented the hyperdynamic reaction induced by IL-2 administration in sheep. This activity of PHP may prevent the early discontinuation of IL-2 therapy that results because of these adverse events.

Inducible nitric oxide synthase dimerization inhibitor prevents cardiovascular and renal morbidity in sheep with combined burn and smoke inhalation injury.

Inducible nitric oxide synthase (iNOS) is implicated in the pathogenesis of acute respiratory distress syndrome (ARDS). ARDS treatment is frequently complicated by significant extrapulmonary comorbidity. This study was designed to clarify the role of iNOS in mediating extrapulmonary comorbidity in sheep after combined burn and smoke inhalation injuries using a potent and highly selective iNOS dimerization inhibitor, BBS-2. Twenty-two female sheep were operatively prepared. After 5 days of recovery, tracheostomy was performed under ketamine-halothane anesthesia. Sheep were given a 40% total body surface third-degree burns and insufflated with cotton smoke (48 breaths, <40 degrees C). Sheep were divided into four groups: noninjured and nontreated (sham group; n = 6), noninjured but treated with BBS-2 (sham/BBS-2 group; n = 4), injured but nontreated (control group, n = 6), and injured but treated with 100 microg.kg-1.h-1 BBS-2 (BBS-2 group; n = 6). Evaluation was in a laboratory intensive care unit setting for 48 h. The sham group had stable cardiopulmonary and systemic hemodynamics. Control animals showed multiple signs of morbidity. Decreased left ventricular stroke work index and stroke volume index with elevated left atrial pressure indicated myocardial depression. Systemic vascular leak was evidenced by robust hemoconcentration, decreased plasma oncotic pressure, and increased transvascular fluid flux into the lymphatic system. Finally, severely impaired renal function (urinary output) was associated with adverse net fluid balance. Treatment with BBS-2 prevented all these morbidities without adversely effecting cardiovascular hemodynamics such as cardiac index and mean arterial pressure. The results identify a major role for iNOS in mediating extrapulmonary comorbidity in a clinically relevant and severe trauma model and support the use of highly selective iNOS inhibitors as novel treatments in critical care medicine.

Ketorolac attenuates cardiopulmonary derangements in sheep with combined burn and smoke inhalation injury.

Massive cutaneous burn combined with smoke inhalation causes high mortality in fire victims. Cyclo-oxygenase (COX) and inducible nitric oxide (NO) synthase (iNOS) have been shown to be up-regulated in burn injury. Ketorolac, a non-steroidal, anti-inflammatory agent (NSAID), inhibits prostaglandin and thromboxane synthesis through inhibition of COX. NSAIDs have been shown to down-regulate iNOS. Thus we hypothesized that treatment with ketorolac would attenuate burn/smoke-related cardiopulmonary derangements. We conducted a fully controlled long-term laboratory investigation in an Intensive Care Unit setting. Eighteen female sheep were surgically prepared for chronic study. After a recovery period of 5 days, a tracheotomy was performed under ketamine/halothane anaesthesia. Sheep were given a 40% total body surface third-degree burn and insufflated with cotton smoke (48 breaths, <40 degrees C). Sheep were divided into three groups: sham (not injured and not treated; n =6), control (injured, but not treated; n =6) and treated (injured and administered ketorolac 60 mg/day; n =6). The sham group had stable cardiopulmonary and systemic haemodynamics. Control animals showed depressed cardiopulmonary function, decreased pulmonary gas exchange, increased pulmonary microvascular leakage and decreased left ventricle stroke work index with elevated left atrial pressure. Systemic vascular leak in control animals was evidenced by robust haemoconcentration (haematocrit and fluid net balance). Treatment with ketorolac prevented all of these morbidities. Post-treatment with ketorolac also resulted in significant inhibition of elevated plasma nitrite/nitrate levels in control animals. These results suggest that ketorolac may ameliorate cardiopulmonary morbidity, at least in part, by inhibiting excessive NO.

Inhibition of neuronal nitric oxide synthase by 7-nitroindazole attenuates acute lung injury in an ovine model.

Nitric oxide (NO) has been shown to play a major role in acute lung injury (ALI) after smoke inhalation. In the present study, we developed an ovine sepsis model, created by exposing sheep to smoke inhalation followed by instillation of bacteria into the airway, that mimics human sepsis and pneumonia. We hypothesized that the inhibition of neuronal NO synthase (nNOS) might be beneficial in treating ALI associated with this model. Female sheep (n = 26) were surgically prepared for the study and given a tracheostomy. This was followed by insufflation of 48 breaths of cotton smoke (40 degrees C) into the airway of each animal and subsequent instillation of live Pseudomonas aeruginosa [5 x 10(11) colony forming units (CFU)] into each sheep's lung. All sheep were mechanically ventilated using 100% O2. Continuous infusion of 7-nitroindazole (7-NI), an nNOS inhibitor, NG-monomethyl-l-arginine (l-NMMA), a nonspecific NOS inhibitor, or aminoguanidine (AG), an inducible NOS inhibitor, was started 1 h after insult. The administration of 7-NI improved pulmonary gas exchange (PaO2/FiO2; where PaO2 is arterial PO2 and FiO2 is fractional inspired oxygen concentration) and pulmonary shunt fraction and attenuated the increase in lung wet-to-dry weight ratio seen in the nontreated sheep. Histologically, 7-NI prevented airway obstruction. The increase in airway blood flow after injury in the nontreated group was significantly inhibited by 7-NI. The increase in plasma concentration of nitrate and nitrite (NOx) was inhibited by 7-NI as well. Posttreatment with l-NMMA improved the pulmonary gas exchange, but AG did not. The results of the present study show that nNOS may be involved in the pathogenesis of ALI after smoke inhalation injury followed by bacterial instillation in the airway.

High-dose heparin fails to improve acute lung injury following smoke inhalation in sheep.

Thrombin is involved in various inflammatory responses. In sepsis, coagulation abnormalities are major complications. Acute lung injury is one of the most life-threatening problems that can result from sepsis. We hypothesized that high-dose heparin might be effective in attenuating acute lung injury in our sepsis model. Female sheep ( n =16) were surgically prepared for the study. After a tracheotomy, 48 breaths of cotton smoke (<40 degrees C) were insufflated into the airway. Afterwards, live Pseudomonas aeruginosa (5 x 10(11) colony-forming units) bacteria were instilled into the lung. All sheep were ventilated mechanically with 100% O(2), and were divided into three groups: a heparin infusion group ( n =6), a Ringer's lactate infusion group ( n =6), and a sham-injury group ( n =4; surgically prepared in the same fashion but receiving no inhalation injury or bacteria). The treatment was started 1 h after the insult, and was continued thereafter for 24 h. The dose of heparin was adjusted by monitoring to target an activated clotting time of between 300 and 400 s (baseline=approx. 150 s). Sheep exposed to lung injury presented with typical hyperdynamic cardiovascular changes, including an increased cardiac output and a fall in systemic vascular resistance. There was a decrease in the arterial partial pressure of O(2). In conclusion, high-dose heparin did not prevent lung dysfunction in this model, in which acute lung injury was induced by combined smoke and septic challenge.

Effect of poly(ADP ribose) synthetase inhibition on burn and smoke inhalation injury in sheep.

We investigated the role of the nuclear enzyme poly (ADP ribose) synthetase (PARS) in the pathogenesis of combined burn and smoke inhalation (burn/smoke) injury in an ovine model. Eighteen sheep were operatively prepared for chronic study. PARS inhibition was achieved by treatment with a novel and selective PARS inhibitor INO-1001. The PARS inhibitor attenuated 1) lung edema formation, 2) deterioration of gas exchange, 3) changes in airway blood flow, 4) changes in airway pressure, 5) lung histological injury, and 6) systemic vascular leakage. Lipid oxidation and plasma nitrite/nitrate (stable breakdown products of nitric oxide) levels were suppressed with the use of INO-1001. We conclude that PARS inhibition attenuates various aspects of the pathophysiological response in a clinically relevant experimental model of burn/smoke inhalation injury.

The inducible nitric oxide synthase inhibitor BBS-2 prevents acute lung injury in sheep after burn and smoke inhalation injury.

In this study we examined the role of inducible nitric oxide synthase (iNOS) in acute respiratory distress syndrome (ARDS) in sheep with severe combined burn and smoke inhalation injury. BBS-2, a potent and highly selective iNOS dimerization inhibitor, was used to exclude effects on the endothelial and neuronal NOS isoforms. Seven days after surgical recovery, sheep were given a burn (40% of total body surface, 3rd degree) and insufflated with cotton smoke (48 breaths, < 40 degrees C) under anesthesia. BBS-2 was provided by constant infusion at 100 microg/kg/hour, beginning 1 hour after injury. During 48 hours, control sheep developed multiple signs of ARDS. These included decreased pulmonary gas exchange, increased pulmonary edema, abnormal lung compliance, and extensive airway obstruction. These pathologies were associated with a large increase in tracheal blood flow and elevated plasma NO2-/NO3- (NOx) levels. These variables were all stable in sham animals. Treatment of injured sheep with BBS-2 attenuated the increases in tracheal blood flow and plasma NOx levels, and significantly attenuated all the pulmonary pathologies that were noted. The results provide definitive evidence that iNOS is a key mediator of pulmonary pathology in sheep with ARDS resulting from combined burn and smoke inhalation injury.