The role of oxygen radicals in immune complex injury.

In this review we will summarize our current understanding of the mediation of immune complex induced tissue injury. Comparisons will be made between the mediation of IgG versus IgA immune complex injury with emphasis on the role that reactive oxygen products derived from leukocytic phagocytic cells play in the initiation of the tissue injury.

The production of tumor necrosis factor alpha and the development of a pulmonary capillary injury following hepatic ischemia/reperfusion.

The large mass of fixed macrophages resident in the liver make it a potentially rich source of cytokines. We have previously demonstrated that an isolated and severe ischemia/reperfusion injury to the liver results in cytokine release, specifically tumor necrosis factor alpha, and that TNF is then involved in the development of pulmonary pathology. This study was designed to determine the kinetics of TNF release following varying periods of hepatic ischemia and to further investigate the acute lung injury that follows. Suprahepatic blood samples were obtained at serial time points following a 45-, 60-, 75-, or 90-min ischemic insult to a segment of the rat liver with subsequent reperfusion. Using a bioassay based on the WEHI 164 cell line, plasma TNF levels were measured in all experimental animals; sham-operated control animals had undetectable levels. Changes in pulmonary capillary permeability were then measured using a standard 125I-labeled albumin washout technique following a 90-min ischemic insult with subsequent reperfusion. A significant increase in the mean permeability index was observed 9 to 12 hr following hepatic reperfusion (.601 +/- 102 as compared with .114 +/- .085 in sham-operated controls, P less than 0.005). Animals treated with anti-TNF antiserum prior to the induction of hepatic ischemia had a significantly reduced pulmonary capillary leak compared to animals pretreated with rabbit serum without TNF-blocking properties (.184 +/- .029 versus .694 +/- 052 for the control serum, P less than 0.005). TNF release follows both moderate and severe ischemic injury to the liver and the results reported here implicate TNF as an important mediator of increased pulmonary capillary permeability. These experiments confirm previous histologic studies that demonstrated pulmonary edema and intra-alveolar hemorrhage following hepatic ischemia/reperfusion, with subsequent blockade of the histologic injury by pretreatment with anti-TNF antiserum.

The effects of hypovolemia on multiple organ injury following intestinal reperfusion.

This study examines the relationship between hypovolemia and remote organ injury following intestinal reperfusion. Sprague-Dawley rats underwent intestinal ischemia (120 min) and reperfusion (90 min, IIR) or sham operation (CTL). The animals received normal saline (NS) at 0, 30, or 40 ml/kg/h intravenously. Lung and intestinal injury was quantitated using an edema index, and liver injury was assessed by measuring bile flow rates. The infusion of 40 ml/kg/h of NS attenuated the intestinal edema index of IIR animals nearly 50% (p < .05). Despite this improvement, this parameter remained nearly 10-fold greater than that of CTL (p < .05). The lung edema index was 70% greater in IIR animals receiving 30 and 40 ml/kg/h of NS than those not receiving NS. The infusion of 40 ml/kg/h of NS restored bile flow rates in IIR animals to that of CTL. These data suggest that hypovolemia may contribute to the intestinal and hepatic injury in this model. The lung injury is independent of hypovolemia.

Complement activation by the hydroxyl radical during intestinal reperfusion.

This study examines the hypothesis that hydroxyl radical (OH.) generation during intestinal reperfusion activates the complement system forming the potent chemotaxin C5a. Anesthetized Sprague-Dawley rats underwent 120 min of intestinal ischemia and 60 min of reperfusion (IIR). Complement (C) activation was assessed by measuring total plasma C activity and C5a-related chemotaxis and leukoaggregation. Dimethylthiourea and the iron chelator deferoxamine were utilized to assess the role of the OH. in the activation of C in this model. Sham-operated animals served as controls. Total plasma C activity of animals sustaining IIR was 64% of controls (p < .05). Plasma of animals sustaining IIR induced greater chemotaxis and leukoaggregation than plasma from sham-operated groups (p < .05). Treatment of IIR plasma with anti-C5a antibody ameliorated the enhanced leukoaggregation characteristic of IIR plasma. Pretreatment with dimethylthiorea and deferoxamine prevented reperfusion-induced activation of complement and inhibited the chemotactic activity of plasma from IIR animals. These data are consistent with the hypothesis that IIR activates complement and that the OH. generated during reperfusion may be one mechanism by which C is activated in this injury model.

Hepatic hypoperfusion after intestinal reperfusion.

BACKGROUND: Intestinal ischemia-reperfusion injury (IIR) induces hepatic and pulmonary dysfunction and thus has been used as a model of multiple organ failure syndrome. This study examines the hypothesis that hepatic blood flow is markedly reduced in this injury model. METHODS: Sprague-Dawley rats underwent 120 minutes of intestinal ischemia and 60 minutes of reperfusion (IIR). Hepatic blood flow was measured with radiolabeled microspheres and Doppler flow probes. Hepatic dysfunction was quantitated by measuring bile flow and serum alanine aminotransferase and hepatic tissue adenosine triphosphate levels. Sham-operated animals served as controls. RESULTS: Intestinal ischemia reduced portal flow by 66% when compared with sham-operated animals (p = 0.0001) but had no effect on hepatic arterial flow. In contrast, reperfusion reduced hepatic artery flow by 80% when compared with controls (p = 0.002) with most of this change occurring within 5 minutes of reperfusion. IIR induced a 63% reduction in bile flow (p < 0.05), a fivefold rise in serum alanine aminotransferase level (p < 0.0002), and a 33% reduction in hepatic adenosine triphosphate level (p < 0.05). CONCLUSIONS: These data suggest that IIR induces profound hepatic hypoperfusion, which is temporally related to acute hepatic dysfunction. This observation suggests that hepatic ischemia may contribute to IIR-induced liver injury.

Blunt liver injury in childhood: evolution of therapy and current perspective.

One hundred eighty-eight consecutive children with serious blunt abdominal or multisystem trauma were evaluated between August 1981 and July 1985. Of the 188 patients, 53 (28%) were found to have hepatic parenchymal injuries and are the basis of this report. Four of the 53 (8%) underwent emergency laparotomy for exsanguinating hemorrhage; two patients died, both of hepatic vein lacerations, and two are alive and well after right hepatic lobectomy. Forty-nine (92%) of the children with liver injuries did not require operation for hemorrhage. Four of these 49 patients developed serious complications; hemobilia occurred in one patient and bile peritonitis occurred in three. The one case of hemobilia was resolved without surgery. One child underwent a delayed operative biliary tract reconstruction that was successful. The other two children required a combination of debridement and drainage procedures. Fifty-one of the 53 children (96%) are currently alive without morbidity related to their liver injuries. Both children who died had multiple trauma including central nervous system injuries and had exsanguinating hemorrhage that required emergency laparotomy at initial evaluation. There were no children with "late" hemorrhage and none who developed septic complications. Nonoperative management of most childhood blunt abdominal trauma is possible. Widespread use of abdominal computerized tomography scanning has made this approach practical. This large series of consecutive liver injuries from a large pediatric trauma center illustrates the advantages and the risks of a selective but primarily nonoperative approach to liver trauma in children.

Late results of fundoplication for gastroesophageal reflux in infants and children.

The Nissen fundoplication (NFP) for the management of severe gastroesophageal reflux (GER) in infants and children has become one of the most frequently performed operations in pediatric surgical centers in the United States. Short-term outcome, morbidity, and mortality are consistently favorable in several large series. The long-term success of this procedure is presumed but has not been established objectively. To examine the late results of this operation, 46 infants and children were carefully evaluated more than 5 years after NFP (mean, 6.7 years). Evaluation included parental interview, physical examination, upper gastrointestinal series, and esophageal pH monitoring. The mean age at the time of operation was 4.13 years. Fifty-seven percent of the patients had significant neurologic impairment, and 80% had at least one serious additional medical problem. Twenty-four percent of the children died during the period of follow-up--all but one death related to serious underlying medical problems. Of the 35 survivors, 26 (74.3%) have no symptoms; five (14.3%) have mild symptoms potentially referable to GER that necessitate little if any treatment; four (11.5%) have had symptomatic recurrence of GER necessitating repeat fundoplication. Three of these patients now have no symptoms. Forty-five percent of the patients had at least one postoperative complication. NFP provides efficacious, long-term treatment of GER in infants and children, with acceptable morbidity. Mortality in this group of children is related primarily to associated diseases rather than to GER.

Activation of complement by hydroxyl radical in thermal injury.

Complement activation resulting from local burn injury of skin and other soft tissues can be linked to systemic complications, such as intravascular hemolysis, neutrophil activation, and acute lung injury. This study was designed to clarify the relationship between cutaneous thermal injury, oxygen radical formation, and complement activation in vivo. A model for "selective" venous sampling from the area of a partial-thickness cutaneous burn over 25% to 30% of the total body surface in the rat was developed. Interventions involving oxygen radical scavengers, antioxidant enzymes, xanthine oxidase inhibitors, an iron chelator, complement depletion, and neutrophil depletion were used to probe the nature of the oxygen products involved in complement activation. Plasma from the area of burn was examined for total hemolytic complement activity, content of C5a-related chemotactic peptide, and relationship of oxygen products to appearance of this peptide. Xanthine oxidase inhibitors, hydroxyl radical scavengers, and complement depletion diminished the generation of C5a activity at the burn site, whereas neutrophil depletion was without effect. These data suggest that C5a activity may be related to oxygen products from xanthine oxidase. The catalase sensitivity and iron dependency of C5a generation suggest that hydroxyl radical may be related to complement activation and C5a appearance. This is the first report to directly link oxygen radical generation and complement activation in vivo.

Evidence for neutrophil-related acute lung injury after intestinal ischemia-reperfusion.

Intestinal ischemia-reperfusion injury is a common and important clinical event associated with the activation of an endogenous inflammatory response. Some of the mediators of this response may be involved in the pathogenesis of multiple organ system failure. The purpose of this study was to determine whether remote organ dysfunction--specifically, acute lung injury--occurs after intestinal ischemia-reperfusion injury. After an ischemia-reperfusion event in rat intestine, whole lungs were obtained for measurement of tissue adenosine triphosphate (ATP) and myeloperoxidase values, and evaluation of histologic condition. In addition, lung microvascular permeability was assessed by determination of the rate at which iodine 125-labeled bovine serum albumin sequestration in the extravascular compartment occurred. Lung tissue ATP levels were no different in sham-operated animals than in those that had undergone 120 minutes of intestinal ischemia. Within 15 minutes of gut reperfusion, however, lung ATP decreased from 3.82 +/- 0.27 to 1.53 +/- 0.90 x 10(-7) moles/50 mg tissue, p less than 0.05. Neutrophil accumulation in the lungs, estimated by tissue myeloperoxidase determination, increased sevenfold (0.13 +/- 0.02 to 0.97 +/- 0.25 units/gm, p less than 0.05) after 120 minutes of ischemia and 15 minutes of reperfusion. Lung microvascular permeability increased threefold after 120 minutes of intestinal ischemia and 120 minutes of reperfusion (0.10 +/- 0.01 vs. 0.35 +/- 0.05 [lung/blood counts per minute], p less than 0.05). Intestinal ischemia followed by reperfusion is associated with acute lung injury characterized by increased microvascular permeability, histologic evidence of alveolar capillary endothelial cell injury, reduced lung tissue ATP levels, and the pulmonary sequestration of neutrophils. These data confirm an acute lung injury associated with intestinal ischemia-reperfusion and suggest a possible pathogenic role for the neutrophil.

Oxidized glutathione as a marker of ischemia reperfusion associated with single lung transplantation.

BACKGROUND: Previous data have shown that glutathione (GSH), an endogenous antioxidant, is converted to its oxidized form (GSSG) after oxidative ischemia-reperfusion events. As GSSG is toxic to cells and is extruded through an active mechanism dependent on intracellular GSSG levels, substance appears in plasma. STUDY DESIGN: Single lung transplantation was performed upon 18 puppies, 3 to 5 kg, with a two hour ischemic time for the donor lung before reimplantation. Recipient animal plasma was obtained after anesthesia induction, pulmonary artery ligation, recipient pneumonectomy, reestablishment of blood flow to the donor lung, completion of transplant, and one, two, and three hours postoperatively. Donor lung bronchoalveolar lavage fluid (BALF) was obtained at the time of harvest, after perfusion of the donor lung with EuroCollins, immediately pretransplant, and after completion of the vascular anastomoses. Oxidized and total GSH levels in plasma and BALF samples were determined by a spectrophotometric assay. RESULTS: After reimplantation of the ischemic donor lung, there was a statistically significant increase in both GSSG and GSH in plasma samples, and a statistically significant increase in GSSG in the BALF. CONCLUSIONS: Compartmental differences between arterial and venous plasma, as well as the increase in GSSG in the BALF, implicated the lung that was transplanted as the source of oxygen free radical generation and GSSG release. Plasma GSSG levels seem to provide a sensitive, noninvasive, repeatable measure of ongoing tissue response and oxygen free radical production.

Choledochal cysts presenting in late childhood and adulthood.

Primary excision is well accepted in children. Although the length of follow-up is inadequate, our review of the literature and experience with five patients suggests primary excision as the procedure of choice in older children and adults. Although the number of cases is too small and the follow-up too sporadic to draw statistically valid conclusions, excision has a lower morbidity, mortality and reoperation rate than internal cyst drainage, and definitive removal of tissue at risk for malignant degeneration seems intuitively more appealing.

Failure of antioxidant therapy (polyethylene glycol-conjugated catalase) in acute pancreatitis.

Previous studies have demonstrated that intravenous catalase infusion protects against the formation of pancreatic edema in cerulein-induced acute pancreatitis; however, polyethylene glycol (PEG)-conjugated catalase given as a bolus was not protective. Using radiolabeled catalase and PEG-catalase in subtherapeutic tracer doses, the pancreas tissue distributions of each were determined in rats with and without pancreatitis. Rats with cerulein-induced pancreatitis developed tissue concentrations of catalase within the pancreas that were three times those of PEG-catalase. The relatively low levels of PEG-catalase in the pancreas outside of the vascular compartment suggest that the failure to prevent edema formation may result from inability of PEG-catalase to reach extravascular sites of injury because of the large molecular size.

Superoxide dismutase and catalase: a possible role in established pancreatitis.

The mechanism of cerulein-induced acute pancreatitis may involve the production of free radicals in excess of the capacity of endogenous intracellular scavengers. These radicals destroy the cellular membranes, releasing digestive enzymes and cellular proteins into the interstitium. Thereafter, a cascade of events, including polymorphonuclear infiltration and complement activation, leads to pancreatic destruction. The present study demonstrates that superoxide dismutase and catalase reduce the ultrastructural and biochemical injury associated with cerulein-induced acute pancreatitis in rats. Pretreatment with superoxide dismutase and catalase 30 minutes before injury did not appear to be protective, presumably because the half-life of intravenous superoxide dismutase is only 6 minutes. This and similar studies suggest a potential clinical role for free radical scavengers in acute established pancreatitis.

Lung injury in acute pancreatitis: primary inhibition of pulmonary phospholipid synthesis.

Alterations in the pulmonary surfactant system are partly responsible for the respiratory insufficiency seen with acute pancreatitis. In this model of cerulein-induced pancreatitis in rats, we utilized a new stable isotope metabolic tracer technique to examine one aspect of the pulmonary surfactant system and its relationship to associated lung injury. We have demonstrated primary, early depression of lung phospholipid synthesis reflected in both lung tissue and alveolar washings. We suggest that this quantitative change in pulmonary surfactant synthetic rate may partly explain the occurrence of respiratory failure with acute pancreatitis.

Treatment of intestinal ischemia with oxygenated intraluminal perfluorocarbons.

Liquid perfluorocarbons are biologically inert compounds capable of dissolving up to 40 percent oxygen by volume. This remarkable and reversible oxygen solubility has encouraged investigations into therapeutic application in situations where tissue oxygen delivery is impaired. One such setting is intestinal ischemia. Identically prepared devascularized segments of rat intestine were treated with either intraluminal oxygenated perfluorocarbon (perfluorotributylamine) or physiologic saline solution. After timed sacrifice, blinded quantitative histologic evaluation for ischemic injury was performed. The perfluorotributylamine treatment groups had histologic scores indicative of less severe injury between 1 and 4 hours. These scores achieved statistical significance (p less than 0.05). We conclude that intraluminal oxygenated perfluorocarbons have a significant protective effect in this model of intestinal ischemia. This quantitative analysis is unique and is an important aspect of the preclinical evaluation of the perfluorocarbon preparations.

Gastrointestinal hemorrhage in children. A pragmatic update.

Gastrointestinal hemorrhage in infants and children is notable for its association with benign disease and its varied, age-dependent etiologies. We have presented these in brief. Much of the information presented, particularly that related to diagnostic endoscopy and sclerotherapy, represents extension of commonly used adult techniques to the pediatric population. Guidelines for resuscitation and diagnosis are provided with the expectation that an individual clinical assessment will lead to modification. Rigidity in approach is to be avoided. Notable recent changes in the management of children with GI hemorrhage are summarized and placed in perspective.

Staging of the endorectal pull-through operation for ulcerative colitis.

Of 43 patients undergoing operation for ulcerative colitis or polyposis, we found staging of the operation advisable in 7 instances. The initial operation consisted of subtotal colectomy with a Hartman's pouch and an ileostomy. The second procedure was a mucosal proctectomy, ileoanal anastomosis, and construction of a pelvic reservoir into the terminal ileum. The ileostomy was closed as a third procedure with approximately 6 months between each operation. Staging is recommended when emergency operation is required because of bleeding, perforation, or toxic megacolon; when significant technical problems are encountered with the mucosal stripping; or when the surgeon has had limited experience with the procedure. With the addition of staging to the surgeon's armamentarium, it is now possible to offer total colectomy with preservation of rectal continence to virtually all patients suffering from chronic ulcerative colitis.

Transtracheal repair of recurrent tracheoesophageal fistula.

A recurrent tracheoesophageal fistula is generally associated with considerable mediastinal induration and inflammation. The conventional operative approach may be formidable with considerable blood loss and a high complication rate. For two infants with recurrent fistulae, we have employed a simplified low cervical transtracheal approach through noninflamed tissues. This brief atraumatic procedure was followed by gratifying results. Details of the approach are presented.

Embryonal rhabdomyosarcoma of the ampulla of Vater with long-term survival following pancreaticoduodenectomy.

Rhabdomyosarcoma of the biliary tree is a rare cause of biliary tract obstruction in childhood. A 3-year-old child is reported here after presenting with obstructive jaundice secondary to an embryonal rhabdomyosarcoma of the ampulla of Vater. He underwent pancreaticoduodenectomy followed by adjuvant chemotherapy and irradiation. He is now well and free of disease 5 years following treatment. This child appears to be the first long-term survivor who has required pancreaticoduodenal resection for this lesion.

Successful separation of a conjoined biliary tract in a set of omphalopagus twins.

Omphalopagus twins were separated in the first 48 hours of life. Preoperative evaluation did not disclose either their conjoined intestines or their conjoined biliary tract; intraoperative evaluation, including an operative cholangiogram, was required to determine if separation was possible. The intestines were divided to give each infant an equal share, and an hepaticoenterostomy was constructed in each of the twins.