Effect of endotoxin and a burn injury on lung and liver lipid peroxidation and catalase activity

Both endotoxin and a burn alone produce oxidant-induced tissue lipid peroxidation. The endotoxin response is due in large part to hydrogen peroxide. The combination of endotoxin after a burn results in an increased liver, but not lung, oxidant injury. Our purpose was to determine whether the burn oxidant injury inactivated endogenous liver tissue catalase, thereby amplifying a subsequent H2O2 insult. Twenty-six adult sheep were studied. Twelve sheep had a 15% TBS burn. Tissue catalase activity, measured in lung and liver 3 days postburn, was significantly decreased from a control of 3.58 +/- 1.8 and 193 +/- 63, respectively, to 1.72 +/- 0.63 and 148 +/- 33 k(sec-1)/0.5 gram tissue. The addition of endotoxin 3 days postburn resulted in an increase in liver malondialdehyde, MDA, a measure of lipid peroxidation, from a control of 110 +/- 80 to 450 +/- 54 nmol/gram tissue. This value was significantly greater than the 210 +/- 80 nmol/gram tissue seen after endotoxin alone. Lung tissue MDA with burn and endotoxin was 65 +/- 8 compared to 42 +/- 7 for control and 80 +/- 6 nmol/gram for endotoxin alone. We conclude that a decrease in liver catalase activity occurs after a burn. The decrease corresponds to an accentuated oxidant-induced lipid peroxidation after an added endotoxin insult where H2O2 is known to be an etiologic agent. The catalase activity also decreases in postburn lung, but accentuated lung damage was not seen, indicating a variable tissue response from the burn-induced decrease in antioxidant activity.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of a body burn on endotoxin-induced lipid peroxidation: comparison with physiologic and histologic changes

We determined the effect of a 15% total body surface (TBS), full-thickness burn on the physiologic, histologic, and oxidant-induced lipid peroxidation changes produced by endotoxin. The endotoxin-burn response was compared with that of endotoxin alone. Twenty-two adult sheep with chronic lung and flank lymph fistulas were studied. In 11 sheep a burn was produced under anesthesia and 3 days later they were given 2 micrograms/kg of endotoxin. Data were also compared with those of control sheep and those that were given burns alone. Circulating conjugated dienes increased with endotoxin alone but remained at baseline with endotoxin and burn injury. The lung lymph flow response was increased significantly in the endotoxin-burn group (sixfold) compared with that of endotoxin alone (fourfold). Histologic quantitation of lung neutrophil count was comparable in both groups 6 hours after injury, although mononuclear cells were much more evident in lungs in the endotoxin-burn group. Lipid peroxidation measured by malondialdehyde was significantly increased in the endotoxin group compared with the endotoxin-burn group, despite the greater increase in lymph flow and lung water in the burned group. Oxygen consumption (VO2) remained constant after endotoxin alone compared with baseline. However, VO2 increased twofold immediately after endotoxin in the endotoxin-burn group. This marked increase was followed by a significant decrease in VO2 from baseline. Flank soft-tissue nonburned increased lung lymph flow twofold to threefold with endotoxin and burn, indicating increased soft-tissue permeability, whereas it remained unchanged with endotoxin alone. Liver malondialdehyde increased from a control of 110 +/- 20 to 210 +/- 80 mmol/gm tissue with endotoxin alone and to 450 +/- 54 nmol/gm tissue with endotoxin and burn. We can conclude that burn injury accentuates both the pulmonary and systemic physiologic response to endotoxin, possibly as a result of mediators released from mononuclear cells already activated in the presence of the burn. The increased lung physiologic response does not appear to be caused by greater oxidant-induced lipid peroxidation, as was seen in the liver with the combined injury.     

Topical flurbiprofen decreases burn wound-induced hypermetabolism and systemic lipid peroxidation

We studied the effect of the topical application of the nonsteroidal anti-inflammatory agent, flurbiprofen, on postburn hypermetabolism and systemic lipid peroxidation. Twelve sheep with a 15% total body surface third-degree burn were monitored over a 4-day postburn period. In six sheep, a single application of a 5% flurbiprofen cream was placed on the burn wound on day 3. Data were compared to both burned and nonburned controls (n = 6). All animals were killed on day 4. Oxygen consumption was increased at day 3 by 28% +/- 10% over the preburn value in all animals. Flurbiprofen significantly attenuated the increase in oxygen consumption, returning the value essentially to baseline by 12 hours after application. Lung and liver peroxidation, as measured by malondialdehyde, was significantly increased in the burned, nontreated sheep at day 4 from a control value of 45 +/- 9 and 110 +/- 12 to 60 +/- 6 and 310 +/- 71 nmol/gm tissue, respectively. In flurbiprofen-treated animals, values were 42 +/- 8 and 160 +/- 18 nmol/gm at day 4, significantly attenuated from burn alone. Protein-rich burn lymph flow remained fourfold increased in both groups, indicating a persistent increase in burn tissue vascular permeability, not modified by flurbiprofen. Burn wound biopsies revealed bacterial contents of less than 10(4) organisms/gram tissue in all animals. We conclude that topical flurbiprofen significantly decreases burn wound-induced systemic hypermetabolism and oxidant-induced lipid peroxidation seen at 3 days after burn injury, but does not attenuate the remaining local burn-wound vascular permeability.     

Early postburn lipid peroxidation: effect of ibuprofen and allopurinol

We measured lipid peroxidation of plasma, lung, and liver in anaesthetized sheep after third-degree burns involving 30% of total body surface. Animals were resuscitated to baseline filling pressures with lactated Ringer's solution and killed 10 hours after burn. Six sheep were pretreated with ibuprofen (12.5 mg/kg) and five with allopurinol (50 mg/kg). We used conjugated dienes and malondialdehyde as measures of lipid peroxidation. Circulating conjugated dienes increased from a baseline of 0.48 +/- 0.06 to 0.64 +/- 0.05 after burn, while protein-rich burn tissue lymph flow increased up to eightfold. We also noted a significant increase in lung tissue malondialdehyde from 45 +/- 4 to 60 +/- 6 nmol/gm and liver malondialdehyde from 110 +/- 20 to 271 +/- 34 nmol/gm along with increased tissue neutrophil sequestration. Ibuprofen attenuated lung-tissue malondialdehyde but had no effect on lung inflammation, circulating lipid peroxides or burn edema, indicating that ibuprofen most likely decreased O2 radical release in lung tissue by the already-sequestered neutrophils. Allopurinol, possibly via xanthine oxidase inhibition, markedly attenuated burn QL and circulating lipid peroxides and prevented all pulmonary lipid peroxidation and inflammation, indicating that release of oxidant from burn tissue was in part responsible for local burn edema, as well as distant inflammation and oxidant release, the latter most likely from complement activation. Neither antioxidant decreased lipid peroxidation in the liver; this indicates that its mechanism of production was different from that seen in burn tissue, in plasma, or in the lung. An ischemic event resulting from a selective decrease in splanchnic blood flow may be the cause of the liver changes.     

Moderate smoke inhalation produces decreased oxygen delivery, increased oxygen demands, and systemic but not lung parenchymal lipid peroxidation

We studied the first 24-hour lung and systemic physiologic response to a moderate smoke inhalation injury. In addition, we monitored oxidant-induced lipid peroxidation (LP), using malondialdehyde and conjugated dienes. Sixteen adult sheep with lung and soft tissue lymph fistulas were given 20 breaths of smoke while under anesthesia. Eight sheep were given a tidal volume of 5 ml/kg smoke, confining the inflammatory injury to airways only. Eight sheep were given 10 ml/kg smoke after which focal alveolar collapse and a carboxyhemoglobin level of 28% +/- 5% were noted in addition to airways injury. No significant lung or systemic physiologic changes were noted in the 5 ml/kg smoke exposure. However, plasma levels of malondialdehyde increased significantly, indicating that LP had occurred. With the 10 ml/kg smoke exposure, a 50% early decrease in oxygen consumption was noted. At 12 hours, oxygen consumption was then significantly increased by 30% over baseline. Fluid requirements to maintain filling pressures were also significantly increased, comparable to that seen after a 20% total body surface burn. A change in soft tissue permeability was noted with a twofold increase in systemic lymph, which could in part explain the fluid requirements. Lung lymph flow increased by only twofold, and lung water was not increased, whereas arterial partial oxygen pressure decreased from a baseline of 95 +/- 4 mm Hg to 60 +/- 5 mm Hg. Systemic LP was evident when both plasma malondialdehyde and conjugated dienes increased significantly. Liver tissue malondialdehyde at postmortem examination was double the normal level. However, lung parenchymal malondialdehyde was not increased.(ABSTRACT TRUNCATED AT 250 WORDS)     

Fluid resuscitation with deferoxamine prevents systemic burn-induced oxidant injury.

We studied the effect of deferoxamine (DFO) infused after burns on hemodynamic stability as well as local and systemic inflammation and oxidant-induced lipid peroxidation. Eighteen anesthetized sheep were given a 40% of total body surface burn and fluid resuscitated to restore oxygen delivery (DO2) and filling pressures to baseline values. Animals were resuscitated with lactated Ringer's (LR) alone or LR plus 1,500 ml of a 5% hetastarch complexed with DFO (8 mg/ml). Animals were killed 6 hours postburn. The sheep resuscitated with LR and LR plus hetastarch demonstrated significant lung inflammation and significant increases in lung and liver malondialdehyde (MDA) from controls of 47 +/- 6 and 110 +/- 7 nMol/gm to 63 +/- 13 and 202 +/- 59 for LR and 67 +/- 4 and 211 +/- 9 for LR + hetastarch, respectively. The group resuscitated with hetastarch alone required 15% less fluid. VO2 returned to baseline values in both groups by 2 hours. Resuscitation with the 5% hetastarch-DFO decreased total fluids by 30% over LR and prevented the increase in lung and liver MDA. In addition, postburn VO2 increased by 25% above baseline values. Burn tissue edema, measured as protein-rich lymph flow, was significantly increased with the administration of DFO compared with the other groups. We conclude that DFO used for burn resuscitation prevents systemic lipid peroxidation and decreases the vascular leak in nonburn tissues while also increasing O2 utilization. Resuscitation with hetastarch-DFO may accentuate burn tissue edema, possibly by increased perfusion of burn tissue.     

Burn edema is accentuated by a moderate smoke inhalation injury in sheep.

We determined the lung and systemic response of a moderate smoke inhalation injury combined with a 15% total body surface third-degree burn compared with a burn alone and inhalation alone. Adult sheep were prepared with chronic lung and bilateral prefemoral soft tissue lymph fistula. The burn was confined to one side. Physiologic parameters, lymph flow (QL), and lymph/plasma protein ratio were monitored. Oxidant changes were measured as lipid peroxidation by circulating and lymph-conjugated dienes and lung tissue malondialdehyde. Animals were resuscitated with lactated Ringer's solution during the 24-hour study period to restore and maintain vascular filling pressures and cardiac index. We found net 24-hour fluid balance for burn-inhalation injuries to be 4.1 +/- 1.2 L compared with burn alone of 2.9 +/- 0.9 L and inhalation alone of 2.4 +/- 0.5 L, a significant difference. Protein-rich burn tissue QL increased by fivefold to sixfold with burn alone compared with more than tenfold with burn-inhalation injury. A twofold increase in both lung and nonburn soft tissue QL was also seen in the combined injury not seen with burn alone. Arterial blood gases decreased only at 12 hours. Plasma conjugated dienes were increased in all groups, whereas burn lymph values were increased only in combined insult. In addition, lung malondialdehyde content at 24 hours was 155 +/- 11 nmol/gm with burn-inhalation injury compared with 62 +/- 8 nmol/L for burn alone, 55 +/- 9 nmol/L in inhalation alone, and 45 +/- 4 nmol/L for controls. However, no alveolar flooding was noted in any group. We conclude that a modest smoke inhalation (carboxyhemoglobin of 25%) added to a 15% total body surface burn markedly increases the degree of burn edema, as well as nonburn soft tissue and lung QL, compared with burn alone, indicating increased plasma to interstitial fluid transport in these tissues as well. Increased burn tissue lipid peroxidation products corresponded with the increased burn fluid losses. The increased lung lipid peroxidation also indicates further lung oxidant activity as well.     

Systemic lipid peroxidation and inflammation induced by thermal injury persists into the post-resuscitation period

We determined the time course of the oxidant-induced systemic lipid peroxidation seen after burn injury. Twelve sheep were given a 15% of total body surface third-degree burn and monitored for 3 or 5 days. Circulating lipid peroxides were monitored by both malondialdehyde (MDA) and conjugated dienes (CD). Lung and liver tissue MDA was also measured and compared to controls. A significant but transient increase in circulating MDA and CD was noted several hours after burn. Venous plasma levels increased again 3-5 days postburn with onset of wound inflammation. Oxygen consumption, VO2, also increased by 35 +/- 12% at this time. Lung MDA, which increased to 64 +/- 5 from a control of 45 +/- 4 nMol/gm, at 12 hours after burn was still increased 3 days after injury. Marked lung inflammation was present early after injury and persisted for the 5-day study period. Liver MDA also increased from control value of 110 +/- 20 to 252 +/- 25 at 12 hours and remained increased over the 5-day period. Serum alkaline phosphatase was also increased. Burn biopsies revealed no infection to explain the ongoing lipid peroxidation process, i.e., bacterial content was less than 10(5) organisms/gram burn tissue. We conclude that an initial system lipid peroxidation occurs immediately after burn injury, and that this process continues well into the post-resuscitation period, corresponding in time with increased VO2, lung inflammation, and evidence of liver dysfunction. The ongoing oxidant changes with the presence of a burn may explain the accentuated organ dysfunction seen with an additional septic insult in burned patients.     

The immediate effect of burn wound excision on pulmonary function in sheep: the role of prostanoids, oxygen radicals, and chemoattractants

Pulmonary dysfunction is a well-recognized complication of burn wound excision. It remains unclear whether this is caused by bacteria or inflammatory mediators released during excision of the wound. We produced a 15% full-thickness burn in 18 sheep, and between days 5 and 7 completely excised the wound under general anesthesia. Pulmonary parameters of static and dynamic lung compliance (CSTAT and CDYN), PaO2/FiO2, and pulmonary artery pressure (Ppa) were measured, as well as burn lymph, venous and aortic thromboxane B2 (TxB2), chemotactic index (chemotaxis/chemikinesis), and oxygen radical activity reflected in the level of lipid peroxidation in lung tissue. We noted a transient increase in burn lymph and venous TxB2 during excision, increasing from a preburn value of 200 and 220 +/- 50 pg/ml to 950 +/- 210 and 980 +/- 280 pg/ml, respectively. In 13 of 18 sheep, chemotactic activity and lung tissue lipid peroxidation, measured as malondialdehyde (MDA) content, were not increased. In this group only a very transient decrease in CDYN, PaO2/FiO2, and a 3 mm Hg increase in mean Ppa was seen with excision, with these parameters returning rapidly to baseline. Five of the 13 sheep had wound biopsy specimens that were greater than 10(6) organisms/gm tissue. In the remaining five sheep, plasma chemotactic index was also significantly increased with excision, as was lung MDA content, while decreases in CDYN, CSTAT, and PaO2/FiO2 and an increase in Ppa were more protracted. Three of these five sheep had wound biopsy specimens greater than 10(6) organisms/gm. We conclude that a release of thromboxane occurs during excision, which corresponds in time to transient lung dysfunction. If there is also a release of chemotactic factors, a more protracted pulmonary response occurs with evidence of O2 radical-induced lung changes.     

Tissue inflammation without bacteria produces increased oxygen consumption and distant organ lipid peroxidation

An inflammatory focus was produced by implantation of gauze below the hide in the flanks of six sheep with flank lymph fistulas. Physiologic and metabolic parameters were monitored in the unanesthetized animals for 7 days, after which the gauze was removed and monitoring continued for another 5 days. Animals were then killed. Lung and liver tissue was inspected and analyzed for lipid peroxide content. Data were compared with those of six controls in which gauze was not implanted. We noted a transient significant increase (on day 1 only) in wound lymph, thromboxane B2, and 6-keto-PGF1 alpha from baseline values of 190 +/- 70 and 20 +/- 10 pg/ml to 1000 +/- 240 and 420 +/- 70 pg/ml, respectively. Plasma values were also significantly increased on day 1. Body temperature increased by 1 degree C and cardiac index increased by 30% during this period, whereas oxygen consumption, VO2, was not significantly increased. The VO2 and cardiac index increased by 50% over baseline, beginning on day 5, whereas systemic vascular resistance decreased. Body temperature was not increased. These changes corresponded with an increase in wound lymph monocyte count from 0% to 15% of total. The VO2 and cardiac index remained increased after gauze removal. No bacteria were found in the wound. Postmortem analysis revealed a marked monocyte-macrophage infiltration in both lung and liver. Lung water, represented as water content over dry weight, was normal. Lung and liver lipid peroxidation, measured by the by-product malondialdehyde content, increased 300% and 90% over control values, respectively. We conclude that a local, nonbacteria-induced wound inflammation increases VO2, with the increase not corresponding to increase in body temperature. Distant organ changes, namely, changes in lung and liver, were also evident 5 days after gauze removal.     

Pulmonary dysfunction secondary to soft-tissue endotoxin

Our purpose was to determine whether peripheral soft tissues produce and release prostanoids in response to local sepsis, and whether this mediator release can produce pulmonary dysfunction. Escherichia coli endotoxin (2 micrograms/kg in 100 mL of saline) was injected below the hide of the flank in seven unanesthetized sheep. In three additional sheep, ibuprofen (12.5 mg/kg of body weight) was injected with the endotoxin. Thromboxane B2 and 6-keto-PGF1 alpha (prostacyclin) levels were measured in tissue lymph draining the flank, lung lymph, pulmonary artery (Ppa), and aortic plasma. One hour after endotoxin administration, mean PaO2 decreased from 90 to 74 mm Hg and Ppa increased from 22 to 35 mm Hg. Lung lymph flow (QL) increased only 50% with QL being protein poor. No increase in lung or peripheral soft-tissue vascular permeability was noted. Tissue lymph (TxB2) increased from 220 +/- 114 to greater than 10,000 pg/mL with levels in Ppa plasma increasing from 300 +/- 128 to 595 +/- 124 pg/mL and aortic plasma from 270 +/- 141 to 410 +/- 104 pg/mL. Lung lymph TxB2 paralleled aortic values. Peak levels of 6-keto-PGF1 alpha in systemic lymph exceeded 2,000 pg/mL while levels in lung lymph remained relatively constant. The pulmonary injury and the increase in TxB2 was prevented by ibuprofen. We conclude that the response of soft tissue to local endotoxin is to release thromboxane in quantities sufficient to raise plasma levels and to produce hypoxia and pulmonary hypertension. The lung dysfunction is not produced by an increase in lung water or vascular permeability.     

Oxygen consumption early postburn becomes oxygen delivery dependent with the addition of smoke inhalation injury.

We determined the relationship between oxygen delivery, DO2, and oxygen consumption, VO2, in sheep after a moderate smoke inhalation injury and 15% TBSA third-degree burn compared with burn alone and controls. Comparison was made beginning three hours after injury when carboxyhemoglobin levels were back to baseline values. We decreased DO2 between three and eight hours by 25% by either removing blood (controls) or decreasing the resuscitation fluid infusion rate. Lung oxidant, measured as tissue malondialdehyde (MDA) levels, and histologic changes were also assessed. Animals were killed at 24 hours. We found that in controls and animals with a burn alone, a 25% decrease in DO2 was compensated for by an increase in O2 extraction, maintaining VO2 constant. Correlation of DO2 to VO2 was r2 = 0.3, indicating independence of VO2 from DO2. With the combined injury, VO2 decreased in proportion to DO2, since O2 extraction did not increase. The correlation of DO2 to VO2 was r2 = 0.9, indicating delivery-dependent consumption, a pathologic process most likely caused by increased inflammatory mediators from the combined injury. Lung lipid peroxidation was markedly increased in the combined injury, 148 +/- 18 nmol MDA/gram of tissue compared with burn alone, 64 +/- 5 nmol/g, or controls, 45 +/- 4 nmol/g. However, no decrease in arterial O2 tension or increase in lung water was noted, i.e., the sheep did not have ARDS, which is known to impair O2 extraction. We conclude that a pathologic O2 delivery-dependent consumption develops with the combination of burn and inhalation injury, increasing the potential for tissue hypoxemia. This change corresponds with increased lung tissue oxidant change.     

The lung inflammatory response to thermal injury: relationship between physiologic and histologic changes

We studied the effect of a body burn on lung physiologic, biochemical, and histologic changes in a 2-day postburn period. A 15% of total-body-surface third-degree burn was produced in 24 adult sheep with lung and burn lymph fistulas. Eight sheep were killed at 12 hours and eight at 48 hours. At 12 hours we noted increased lung tissue lipid peroxidation, lung congestion, and neutrophil sequestration, in addition to a 30% decrease in lung compliance. Lung permeability and water content were not increased. Increased release of lipid peroxides and prostanoids were noted from burn tissue, as evidenced by increased plasma levels of malondialdehyde and conjugated dienes that remained elevated for about 8 hours and were decreased with wound removal. The lung inflammatory response was still present at 48 hours, the cells being primarily neutrophils. Nevertheless, the lipid peroxidation process, as measured by lung tissue malondialdehyde, had resolved. There was no evidence of burn tissue infection, measured by quantitative culture, to explain the persistent increase in lung inflammatory cells. Excision and closure of the burn wound at 3 hours postburn in eight sheep attenuated the lipid peroxidation and compliance changes but did not decrease the neutrophil sequestration. We conclude that burn injury results in a local wound oxidant release that leads to lipid peroxidation, both in wounds and in lung, as well as lung inflammation. The lipid peroxidation process may be attenuated by removal of the wound. The neutrophil sequestration is not altered, however, indicating this response occurs very early after injury, probably as a result of oxidant-initiated complement activation.     

Endotoxin causes hydrogen peroxide-induced lung lipid peroxidation and prostanoid production

We studied the role of hydrogen peroxide release on endotoxin-induced lung injury in unanesthetized sheep with chronic lung lymph fistulas. We also further defined the relationship between endotoxin injury, lipid peroxidation, and prostaglandin production. Sheep were given endotoxin alone (1 microgram/kg) or pretreated with catalase (32,500 U/kg) or ibuprofen (12.5 mg/kg). Endotoxin alone resulted in an early prostanoid release, lipid peroxidation measured as circulating conjugated dienes both one and four hours after the administration of endotoxin, pulmonary hypertension, hypoxia, and increased protein permeability. Permeability was monitored by lymph flow and lymph protein content. Catalase pretreatment significantly attenuated all of these aspects of the endotoxin response. Ibuprofen prevented the early lung changes and blocked prostanoid release but did not attenuate the increased permeability. In addition, cyclo-oxygenase inhibition had a dual effect on lipid peroxidation, increasing initial conjugated diene levels while suppressing the later release. The initial effect was clearly related to cyclo-oxygenase blockade. The early conjugated diene release appears to be related to arachidonic acid metabolism and does not correspond to the degree of increased permeability. We conclude that H2O2 plays a major role in lung injury after endotoxin.     

The impact of laparoscopic biopsy of pancreatic lymph nodes on lipid peroxidation using helium and carbon dioxide in BOP-induced pancreatic cancer in hamsters

BACKGROUND: Increased lipid peroxidation is believed to stimulate liver metastasis in pancreatic cancer. However, the effect of the laparoscopic biopsy of pancreatic lymph nodes on liver metastasis is still unknown. We hypothesized that the effects of a pneumoperitoneum with carbon dioxide (CO2) increase lipid peroxidation and stimulate liver metastasis. METHODS: Ductal pancreatic adenocarcinoma was induced in Syrian hamsters (n = 30) by weekly subcutaneous injections of N-nitrosobis-2-oxopropylamine (BOP) for 12 weeks. In group 1, a laparotomy and biopsy of pancreatic lymph nodes was performed. Groups 2 and 3 underwent laparoscopic biopsy with either CO2 or helium. In the 5th postoperative week, the hamsters were killed and the incidence of liver metastasis was analyzed histopathologically. We then made determinations of the level of lipid peroxidation (thiobarbituric acid-reactive substances [TBARS])as well as the activity of glutathionperoxidase (GSH-PX) and superoxidismutase (SOD) in pancreatic carcinoma and liver metastases of the animals. RESULTS: The incidence of liver metastasis was higher in the CO2 group (60%) than in the helium (30%) and laparotomy groups (20%) (p < 0.05). The concentration of TBARS was greater in pancreatic carcinoma and intrametastatic hepatic tissue than in extratumorous pancreatic and extrametastastic hepatic tissue in all groups. Extrametastatic hepatic concentration of TBARS was higher in the CO2 group (19.4 +/- 0.88 nmol/mg protein) than the laparotomy (10.66 +/- 0.95 nmol/mg protein) and helium groups (10.79 +/- 0.58 nmol/mg protein). GSH-PX and SOD activity was significantly lower in pancreatic carcinoma tissue and intrametastatic hepatic tissue than in extratumorous pancreatic and extrametastatic hepatic tissue. However, in the CO2 group (1.24 +/- 0.48 107 U/mg protein), extrametastatic GSH-PX activity was lower than in the laparotomy (1.73 +/- 0.4 107 U/mg protein) and helium groups (1.63 +/- 0.28 107 U/mg protein). CONCLUSION: After laparoscopic biopsy of pancreatic lymph nodes in the CO2 group, lipid peroxidation was increased and GSH-PX activity was decreased in extrametastatic hepatic tissue compared to the intrametastatic sections. This mechanism may be responsible for the increased liver metastasis in the CO2 group.     

Effect of a body burn on the lung response to endotoxin

Our purpose was, in general, to determine the effect of a body burn on the pulmonary response to endotoxemia and, specifically, to determine whether increased thromboxane (TxA2) production by the burn wound was responsible for the accentuated lung injury. Thirty-two unanesthetized sheep with lung and soft tissue lymph fistulae were studied. Twelve sheep were given a sublethal dose of intravenous E. coli endotoxin (2 micrograms/kg). A characteristic two-phase injury was noted as evidenced by early pulmonary hypertension and hypoxia and later increased lung permeability. TxA2 was significantly increased in lung lymph as well as aortic plasma relative to venous plasma, indicating the lung to be the source. Twelve of 12 sheep survived. Five of 13 sheep died from endotoxemia when given 3-5 days after a 25% total body surface (TBS) burn and five of seven died with endotoxin (2 micrograms/kg) and a 50% burn. Physiologic parameters were at preburn levels before endotoxin. Animals died both during the early phase from hypoxia and the later phase due, in large part, to increasing pulmonary dysfunction. Absolute levels of TxA2 were not increased in the postburn animals, nor was there a clear release of TxA2 from burn tissue to explain the accentuated response. Prostacyclin levels were, however, less elevated in postburn animals in response to endotoxin, thereby altering the TxA2/PGI2 ratio in favor of TxA2. However, a cause and effect relationship between the increased lung injury and TxA2 remains undetermined. Lymph flow or lymph protein content was not altered in burn tissue in response to endotoxin.     

Effects of glucocorticoids on lung glutamine and alanine metabolism

The role of the glucocorticoid hormones as possible mediators of the accelerated lung glutamine and alanine release that occurs during critical illness was investigated. Studies were done in adult rats receiving dexamethasone (0.6 mg intramuscularly/100 gm body weight/day for 2 consecutive days; n = 24) or saline solution (controls; n = 20). Measurements were made in the postabsorptive state and amino acid flux was calculated by multiplying pulmonary blood flow by the right ventricular-arterial concentration difference for glutamine and alanine. Lung glutamine release was 703 +/- 184 nmol/100 gm body weight/min in control rats. This release rate doubled in the dexamethasone-treated rats (1476 +/- 256; p less than 0.05). The activity of the glutamine synthetase enzyme increased by 33% in the dexamethasone-treated animals and there was a 50% decrease in lung glutamine content (p less than 0.01). Likewise, dexamethasone accelerated the release of alanine by the lungs twofold (559 +/- 173 nmol/100 gm body weight/min in controls vs 1113 +/- 184 nmol/100 gm body weight/min in dexamethasone-treated rats; p less than 0.05). The increased release of both amino acids was caused by a significant increase in the concentration difference across the lungs and not a change in pulmonary blood flow. Glucocorticoids appear to be key mediators of the accelerated lung amino acid release that characterizes catabolic diseases.     

Influence of fructose-1,6-diphosphate on endotoxin-induced lung injuries in sheep

BACKGROUND: Fructose-1,6-diphosphate (FDP) is reported to have a salutary effect in endotoxin shock and sepsis. This investigation describes the effect of FDP on pulmonary and systemic hemodynamics, lung lymph protein clearance, and leukocyte count in sheep infused with Escherichia coli endotoxin. MATERIALS AND METHODS: Anesthetized sheep (n = 18), some of which underwent thoracotomy to cannulate lymphatic nodes, were used in this study. After stabilization, all sheep received E. coli endotoxin, 5 microg/kg i.v. infusion over 30 min. Concomitant with the endotoxin infusion, half of the animals were randomly selected to receive an i.v. bolus of FDP (10%), 50 mg/kg, followed by a continuous infusion of 5 mg.kg(-1).min(-1) for 4 h; the rest were treated in the same manner with glucose (10%) in 0.9% NaCl. RESULTS: Pulmonary artery pressure (PAP) and resistance in the glucose group increased from 20.8 +/- 1.6 to 36.7 +/- 3.2 mmHg (P < 0.007) and from 531 +/- 114 to 1137 +/- 80 dyn.s(-1).cm(-5), respectively (P < 0.005). Despite an increase during endotoxin infusion, these parameters in the FDP group returned to control values. There were no differences in left ventricular pressures, cardiac output, heart rate, and arterial oxygen tension between the groups. In the glucose group, lymph protein clearance was higher (P < 0.01) and blood leukocyte count was lower (P < 0.02). The wet/dry lung weight ratio (g/g) for the glucose group was 5.57 +/- 0.04 and for the FDP-treated group 4.76 +/- 0.06 (P < 0.0005). CONCLUSION: FDP treatment attenuated significantly the characteristic pulmonary hypertension, lung lymph protein clearance, and pulmonary vascular leakage seen in sheep infused with endotoxin.     

Effect of hydroxyl radical scavenging on endotoxin-induced lung injury

The release of oxygen radicals, in particular the hydroxyl radical, from sequestered neutrophils produces acute lung injury after a number of insults. Our purpose was to determine whether hydroxyl radical, OH., is responsible for the lung injury from endotoxin characterized by (1) pulmonary leukostasis, (2) increased thromboxane production leading to pulmonary hypertension and hypoxia, and (3) increased protein permeability. This hypothesis was tested by infusion of a selective OH. scavenger, dimethyl thiourea (0.75 gm/kg), into unanesthetized sheep before endotoxin and comparison of the response to that seen with endotoxin alone. Pulmonary vascular integrity was measured by the use of lung lymph flow, QL, and lymph protein transport. Thromboxane A2 was measured as TxB2 and prostacyclin as 6-keto-PGF1 alpha. We found no difference in the degree of leukopenia and hypoxia after endotoxin or the levels of TxB2, 6-keto-PGF1 alpha, and pulmonary hypertension with dimethyl thiourea, compared with endotoxin alone. The permeability injury was also identical, with a twofold to threefold increase in protein-rich lymph seen in both groups. It appears that OH. does not play a major causative role in either phase of endotoxin lung injury.     

Regulation of glutathione redox status in lung and liver by conditioning regimens and keratinocyte growth factor in murine allogeneic bone marrow transplantation.

BACKGROUND: Reactive oxygen species (ROS) and glutathione (GSH) depletion contribute to organ injury after bone marrow transplantation (BMT). Keratinocyte growth factor (KGF) ameliorates graft-versus-host disease (GVHD)-associated organ injury in murine BMT models. METHODS: B10.BR mice received total body irradiation (TBI; day -1) +/- cyclophosphamide (Cy; 120 mg/kg/day i.p., days -3 and -2), then were transplanted on day 0 with C57BL/6 bone marrow + spleen cells as a source of GVHD-causing T cells. KGF (5 mg/kg/day subcutaneously [s.c.]) or saline was given on days -6, -5, and -4. Lung and liver GSH and oxidized GSH disulfide (GSSG) levels were measured on days 0 and 5 and glutathione redox potential (Eh) calculated. Organ malondialdehyde (MDA) was determined on day 5 as an index of ROS-mediated lipid peroxidation. RESULTS: In lung, TBI+BMT oxidized GSH Eh and increased MDA. Cy further oxidized lung GSH Eh. In liver, neither BMT regimen altered GSH redox status or MDA. KGF prevented the decrease in lung GSH after TBI+Cy and decreased lung MDA after both TBI and TBI+Cy. KGF increased liver GSH levels and GSH Eh after TBI and GSH Eh after TBI+Cy. CONCLUSIONS: In murine allogeneic BMT, TBI oxidizes the lung GSH redox pool and Cy exacerbates this response by 5 days post-BMT. In contrast, liver GSH redox status is maintained under these experimental conditions. KGF treatment attenuates the Cy-induced decrease in lung GSH, decreases post-BMT lung lipid peroxidation, and improves liver GSH redox indices. KGF may have a therapeutic role to prevent or attenuate GSH depletion and ROS-mediated organ injury in BMT.