Morphologic changes of red blood cells during hemorrhagic shock replicate changes of aging.

Blood loss leads to the reduction in vitality of red blood cells (RBCs). However, the changes in morphology at different stages of hemorrhagic shock have not been studied. Thus, the aim of this study was to identify and quantitate the sequence of morphological changes in RBCs during hemorrhage. This study was performed on 15 adult inbred dogs. Blood samples were taken before hemorrhage, when the mean arterial pressure reached 40 mm Hg (initial stage of shock), and at a mean arterial pressure level of 20 mm Hg (decompensated stage of shock). The volume of blood removed averaged 33.6+/-8.9 and 55.1+/-6.9 mL/kg, respectively. Evaluation of RBC morphology was performed by computerized light microscopic morphometry and scanning electron microscopy. At the early stage of hemorrhage the number of "young-appearing" RBCs with large visible surface areas (41-50 microm2) increased from 17.7%+/-3.1% to 26.6%+/-3.5% (P < 0.05). Concomitantly, the number of "old-appearing" RBCs with small visible surface area (20-30 microm2) significantly decreased from 5.3%+/-2.7% to 2.7%+/-2.3% (P < 0.01). At the stage of decompensated blood loss, the opposite phenomenon was observed. The number of "old-appearing" RBCs increased to 8.2%+/-1.1% (P < 0.01), whereas the number of "young-appearing" RBCs decreased to 12.3%+/-4.2% (P< 0.01). The changes in visible surface area of RBCs was accompanied by significant alterations in their shape. The percentage of abnormal shaped RBCs increased from 8.9%+/-1.1% before the hemorrhage to 36.4%+/-5.8% at the stage of decompensated hemorragic shock (P < 0.01). Thus, during the late decompensated stage of hemorrhagic shock, RBCs assume shape and surface area changes that are similar to those seen in aging. These changes in RBC size and shape may be due to the effects of shock-induced oxidative stress.

Hemorrhage exacerbates bacterial translocation at low levels of intra-abdominal pressure.

BACKGROUND: It has been shown previously that the adverse cardiopulmonary sequelae of increased intra-abdominal pressure (IAP) are worsened by hemorrhage and resuscitation. Bacterial translocation (BT) to the mesenteric lymph nodes (MLNs), liver, and spleen has also been shown to occur with increased IAP. OBJECTIVE: To investigate the hypothesis that BT associated with elevated IAP would be significantly increased after hemorrhage and resuscitation. MATERIALS AND METHODS: Anesthetized adult male rats had femoral artery and vein catheters placed, and an intra-abdominal catheter placed to measure IAP. Group 1 underwent surgery only and served as controls. Group 2 had IAP raised to 10 mm Hg by infused lactated Ringer's solution for 40 minutes. Group 3 had a 25% hemorrhage, followed by resuscitation by infused lactated Ringer's solution and shed blood. Group 4 first had a 25% hemorrhage, resuscitated using infused lactated Ringer's solution and shed blood, and then had IAP raised to 10 mm Hg by infused lactated Ringer's solution for 40 minutes. All groups were killed after 2 hours, and had MLNs, liver, and spleen harvested for quantitative cultures. RESULTS: Hemorrhage and resuscitation alone did not increase BT to the MLNs, liver, or spleen. An increase in IAP to 10 mm Hg resulted in a significant level of BT to the MLNs and liver on MacConkey II agar (P<.05), and a significant increase in the level of BT only to the liver on trypticase soy agar with 5% sheep's blood (P<.05). Hemorrhage and resuscitation did increase the level of BT to the liver and spleen when IAP was increased to 10 mm Hg (P<.05). CONCLUSIONS: In this model, hemorrhage and resuscitation alone did not increase BT to the MLNs, liver, or spleen. However, hemorrhage and resuscitation increased BT to the liver and spleen when IAP was increased to 10 mm Hg. This supports the concept that prior hemorrhage and resuscitation exacerbates the effects of increased IAP.

Effect of hemorrhage on superior mesenteric artery flow during increased intra-abdominal pressures.

BACKGROUND: Elevations in intra-abdominal pressure (IAP) adversely affect organ function. Prior hemorrhage and resuscitation exacerbates the cardiac and pulmonary effects of IAP. We have recently shown that superior mesenteric artery flow (SMAF) is reduced with increasing IAP. This study was designed to determine whether and how hemorrhage and resuscitation affects SMAF with increasing IAP. METHODS: Ten pigs were divided into two groups after placement of a Doppler flow probe around the proximal SMA and insertion of a pulmonary artery (PA) catheter. Group 1 underwent intraperitoneal infusion of fluid to increase IAP to 10, 20, 30, and 40 mm Hg followed by a 20-minute equilibration period at each IAP. Group 2 was hemorrhaged 20% of circulating volume followed by standard resuscitation. After equilibration, this group had IAP increased in the same manner as group 1. Cardiac output (CO), PA pressures, and SMAF were recorded 1 hour after laparotomy and after equilibration at each IAP. Comparisons were made using repeated measures of analysis of variance, Student's t test, and linear regression analysis. RESULTS: In group 2, a reduction in SMAF was noted at 30 and 40 mm Hg of IAP when compared with baseline (p = 0.009). This reduction was not seen in group 1. There was also a significant (p = 0.001) reduction in CO between baseline and all levels of increased IAP in group 2. This decrease was again not seen in group 1. The correlation between CO and SMAF in group 2 was r = 0.74, r2 = 0.55, p = 0.0001. There was no significant correlation between CO and SMAF in group 1. CONCLUSION: SMAF and CO are reduced with increasing IAP to a greater degree when preceded by hemorrhage and resuscitation. Although there is a strong correlation between the reductions in CO and SMAF, the reduction in SMAF is greater than the reduction in CO. This finding suggests that optimizing cardiac function alone during periods of even moderate levels of increased IAP may be inadequate to normalize SMAF. This lends further support for early abdominal decompression in the treatment of trauma patients with increased IAP.

Intestinal permeability correlates with severity of injury in trauma patients.

BACKGROUND: Increased intestinal permeability (IP) and the release of toxic intraluminal materials have been implicated in the systemic inflammatory response syndrome (SIRS) and multiple organ failure (MOF) observed in patients after severe trauma. Previous studies of intestinal permeability have failed to demonstrate a correlation between early measurements of IP and indicators of injury severity. This study examines the relationship between standard measures of injury severity and the early (day 1) and delayed (day 4) changes in IP. Associations between IP and the development of SIRS, MOF, and infectious complications were also studied. METHODS: The metabolically inactive markers lactulose (L) and mannitol (M) were used to measure IP in 29 consecutive patients who sustained injuries that required admission to the surgical intensive care unit and in 10 healthy control subjects. Measurements were made within 24 hours of admission and on hospital day 4. Severity of injury was assessed by A Severity Characterization of Trauma (ASCOT), Trauma and Injury Severity Score (TRISS), Injury Severity Score (ISS), Revised Trauma Score (RTS), and Acute Physiology and Chronic Health Evaluation (APACHE) II score. Postinjury infections and parameters of SIRS and MOF were recorded. RESULTS: The IP of healthy volunteers (L/M, 0.025 +/- 0.008) was within the normal range (L/M < or = 0.03), whereas the average IP in injured patients was increased both within 24 hours (L/M, 0.139 +/- 0.172) and on the fourth hospital day (L/M, 0.346 +/- 0.699). No significant correlation between severity of injury and increased IP was seen within 24 hours of injury. A significant correlation was seen on hospital day 4, however, with all severity indices measured (ASCOT: r = 0.93, R2 = 0.87, p < 0.001; TRISS: r = 0.93, R2 = 0.87, p < 0.001; ISS: r = 0.84, R2 = 0.70, p < 0.001; RTS: r = 0.68, R2 = 0.47, p = 0.002; APACHE II score: r = 0.51, R2 = 0.26, p = 0.04). Patients with markedly increased IP (L/M > or = 0.100) experienced a significant increase in the development of SIRS (83 vs. 44%; p = 0.03) and subsequent infectious complications (58 vs. 13%; p = 0.01) and showed close correlation with the multiple organ dysfunction scores (r = 0.87, R2 = 0.76, p < 0.001). CONCLUSION: These observations demonstrate that the increased IP observed after trauma correlates with severity of injury only after 72 to 96 hours and not within the initial 24 hours of injury. A large increase in IP is associated with the development of SIRS, multiple organ dysfunction, and an increased incidence of infectious complications.

The relationship of packed cell transfusion to red blood cell deformability in systemic inflammatory response syndrome patients.

RBC deformability (RBCD) is decreased in critically ill patients. This is thought to impede the passage of the RBC through the microcirculation. The cell transit analyzer (CTA) provides an evaluation of RBCD. RBCD was examined in 16 patients admitted to the surgical intensive care unit. CTA analysis was conducted within 24 h of admission to the surgical intensive care unit or as soon as possible thereafter, and then repeated every 72 h. Counts per second (C/s) was the parameter used as an index of RBCD. Patients were classified as Septic/SIRS or nonseptic at the time of each blood collection by standard clinical criteria. There were 34 total specimens, 22 septic/SIRS and 12 nonseptic. The C/s for the SIRS samples (41.7 +/- 3.4 was significantly (p < .05) lower than that of the non-SIRS samples (54.3 +/- 5.3). Seventeen of the Septic/SIRS samples were obtained following blood transfusion. Pearson's test calculated for the C/s and the total number of packed RBC transfusions showed a positive correlation (r = .594) that was statistically significant (p < .02). CTA was also performed on 10 U of banked packed RBC in vitro. Deformability was maintained at a constant level until the very end of the storage period, at which time there was a statistically significant decrease in C/s (p < .0001). These data suggest that packed RBC transfusion is associated with a significant improvement in the abnormally low RBCD seen in critically ill patients. This may be due to replacement of previously rigidified cells by cells with a more normal RBCD.

Hemorrhage lowers the threshold for intra-abdominal hypertension-induced pulmonary dysfunction.

BACKGROUND: Intra-abdominal hypertension has been associated with pulmonary and cardiac dysfunctions. We have noted in the clinical scenario of hemorrhagic shock and resuscitation that avoidance of even moderate levels of increased intra-abdominal pressure, using prophylactic decompression, improves outcomes when compared with patients who were decompressed when intra-abdominal pressures went over 20 cm H2O. We hypothesized that prior hemorrhage and resuscitation exacerbates the cardiopulmonary dysfunction associated with intra-abdominal hypertension. METHODS: Ten anesthetized pigs underwent placement of arterial and pulmonary artery catheters and a Silastic intra-abdominal catheter for measuring and manipulating intra-abdominal pressure. Group 1 animals (n = 5) were subjected to increasing intra-abdominal pressures at 10 mm Hg increments up to a level of 40 mm Hg. Group 2 animals (n = 5) were exposed to a severe hemorrhage and resuscitation before the increasing intra-abdominal pressure protocol. RESULTS: Compared with baseline, hemorrhage and resuscitation caused a significant deterioration in cardiac output at intra-abdominal pressures of 10 mm Hg and above. Oxygenation was reduced at 30 and 40 mm Hg. These changes were not seen in group 1 animals. A significant difference was found between groups 1 and 2 in VT, PaCO2, and PaCO2/FIO2 ratio at an intra-abdominal pressure of 20 mm Hg. This difference was not seen at lower or higher pressures. CONCLUSIONS: Prior hemorrhage and resuscitation caused an earlier decline in cardiopulmonary function in the setting of increased intra-abdominal pressure. These data suggest that, when interpreting intra-abdominal pressures, the clinical scenario must be considered. Prior hemorrhage and resuscitation produce the adverse consequences of intra-abdominal hypertension at lower pressures than when intra-abdominal hypertension is the only insult.

Laparoscopic cholecystectomy in the inner-city hospital.

Laparoscopic cholecystectomy (LCCY) has become the treatment of choice for patients undergoing elective CCY. Inner-city hospitals treat a large number of patients with advanced or acute disease, and the ability to perform LCCY in this patient population is unclear. The records of the first 107 patients undergoing LCCY were reviewed. There were 96 women and 11 men with a mean age of 42 years (range 14-86 years). Twenty-seven (42%) of the patients were admitted through the emergency room and were operated upon urgently, whereas 35 (58%) underwent elective LCCY. More than two-thirds of the patients were either uninsured or covered by Medicaid. In the urgent group, 38% had gallstone pancreatitis, 41% had abnormal LFTs, and 26% had a WBC > 13,000. A total of 70% of these patients were discharged within 48 hours after LCCY. The conversion rate was 9% and was similar between urgent and elective LCCY. In summary, acute biliary tract pathology accounted for one-half of the patients undergoing LCCY in our hospital. In conclusion, LCCY can be performed in this group of patients with low morbidity, especially if the need for liberal conversion to open CCY is recognized.

Correlation between red blood cell deformability and changes in hemodynamic function.

BACKGROUND: In sepsis red blood cells (RBCs) have been shown to be less deformable (i.e., more rigid) and have been implicated in decreasing nutrient blood supply and possibly leading to organ dysfunction. However, no studies have demonstrated an association between organ dysfunction and rigid RBCs. This study examined cardiovascular physiologic and histologic changes in two different models to determine whether a relationship may exist between RBC deformability and organ function. METHODS: In the following two experiments, cardiac index (CI) was continuously measured, whereas both deformability index and histology were examined at the end of the experimental periods. The first experiment studied nonanesthetized, hydrated rats after a cecal ligation and puncture (CLP), a slow-developing means of inducing RBC rigidity. In a second experiment animals were anesthetized and received a 20% total blood volume transfusion of either diamide-treated (rigid) RBCs or normal RBCs. RESULTS: CLP-treated animals' CI gradually decreased during 18 hours (232 +/- 60 ml/min/kg to 123 +/- 90 ml/min/kg; p = 0.05), with an increase in systemic vascular resistance (1459 +/- 517 dyne.sec/cm5.m2 to 2337 +/- 1213 dyne.sec/cm5.m2; p = 0.02). Diamide-treated animals had a rapid decrease in CI (86 +/- 7.0 ml/min/kg to 58 +/- 13 ml/min/kg; p = 0.05) and increase in SVR (2269 +/- 373 dyne.sec/cm5.m2 to 3897 +/- 988 dyne.sec/cm5.m2; p = 0.05) from baseline to 120 minutes after treatment respectively. The DI was significantly lower in both CLP and diamide groups (p < 0.03) when compared with control animals. Histologic evidence of subendocardial necrosis was shown in both the CLP- and Diamide-treated animals. CONCLUSIONS: These data suggest an association with RBC deformability and organ function in both septic and nonseptic animal models.

Decreased red blood cell deformability and impaired oxygen utilization during human sepsis.

Sepsis is characterized by decreased microcirculatory flow and increased peripheral shunting. Previous studies have shown red blood cell deformability (RCD) is decreased during sepsis. The purpose of this study was to evaluate the effect of changes in RCD on hemodynamics and oxygen utilization during sepsis. RCD, arteriovenous oxygen difference (DA-VO2), mixed venous oxygen saturation (MVO2), intrapulmonary shunt (QS/QT), cardiac index, and systemic vascular resistance were measured in 10 trauma patients, all of whom had or developed clinical sepsis. Data are expressed as mean +/- SD. Patients with normal RCD (> 0.75) were compared with those with low RCD (< 0.75). Patients with low RCD had a significantly higher incidence of sepsis (100% vs. 20%, P < 0.05, Student's t test or Fisher's Exact Test), lower DA-VO2 (2.4 +/- 0.9 vs. 4.8 +/- 1.5 P < 0.05, Student's t test or Fisher's Exact Test), and higher MVO2 (79 +/- 8 vs. 65 +/- 11 P < 0.05, Student's t test) or Fisher's Exact Test) than those patients with normal RCD. There was a direct correlation between RCD and DA-VO2 (r = 0.852, P < 0.001). MVO2 correlated inversely with changes in RCD (r = 0.813, P < 0.001). No significant correlation existed between RCD and cardiac index or systemic vascular resistance. Patients with low RCD demonstrated impaired oxygen utilization; changes in RCD correlated closely with changes in DA-VO2 and MVO2. These data suggest that decreased RCD may have an etiologic role in the impaired oxygen utilization that occurs during sepsis.

The role of laparoscopy in abdominal trauma.

Thirty-nine hemodynamically stable trauma patients were evaluated prospectively by laparoscopy before planned celiotomy. Laparoscopy was performed using a forward-viewing laparoscope connected to two high-resolution video monitors. The mechanism of injury was blunt trauma in eight, stab wounds (SWs) in 16, and gunshot wounds (GSWs) in 15. Laparoscopy correctly identified the presence of an intraperitoneal injury in 26 patients. Six other patients had retroperitoneal injuries, five of which were seen on laparoscopy. The remaining seven patients had no demonstrable intraperitoneal or retroperitoneal injuries, did not undergo celiotomy, and were observed without morbidity. In comparison with findings at surgery, laparoscopy identified injuries to the liver in eight of ten, to the diaphragm in three of three, to the colon in two of three, to the stomach in three of three, to the kidney in one of one, to the spleen in none of three, and to the small bowel in none of four patients. Visualization of the spleen was achieved in only one patient. The extent of the hemoperitoneum was underestimated from the laparoscopic examination in all nine patients with greater than 750 mL of peritoneal blood, four of whom had undetected active bleeding. Laparoscopy was performed easily in all patients and there were no complications associated with its use. In conclusion, the absence of an intra-abdominal injury was correctly identified with laparoscopy in 11 patients and laparoscopy may decrease the need for celiotomy in selected patients. However, the inability to "run the small bowel," visualize the spleen, and evaluate hemorrhage limits the utility of laparoscopy in determining which patients with laparoscopically visualized injuries will require celiotomy.

Red cell deformability is an early indicator of infection.

Red blood cells (RBC) have been shown to become less deformable during infection. The RBC deformability index (DI) was measured within 24 hours of admission in 37 patients who had suffered trauma and every 48 to 72 hours thereafter while they were in the surgical intensive care unit to assess whether DI could be used as an early indicator of infection after injury. Infection was defined as a temperature of 101 degrees F or more and a white blood cell count of more than 12,000/cm3 associated with a positive culture. Eighteen patients developed an infection, and 19 patients did not. On day 1, both groups showed a significant decrease in DI, compared to controls (0.33 +/- 0.18 and 0.34 +/- 0.25 for patients with infection and patients with no infection vs 1.52 +/- 0.12 for control volunteers; p less than 0.05). In the group with no infection, the DI improved in 16 of 19 patients after injury; the DI in patients with infection continued to decrease in 17 of 18 patients. The decrease in DI occurred 4 +/- 2 days (range, 2 to 8 days) before the diagnosis of infection. No significant differences were apparent in the absolute white blood cell count between the group with infection and the group with no infection at any time after injury. Differences in maximal temperature were noted on day 3 and beyond; however, 30% of patients with no infection had a temperature of more than 101 degrees F for 7 days. These data show that trauma results in a significant decrease in RBC deformability and that serial changes in DI appeared to predict which patients would develop an infection and which patients would recover uneventfully. RBC deformability may be helpful in early detection of infection in patients who have suffered trauma.

Oxygen free radicals: effect on red cell deformability in sepsis.

OBJECTIVE: To examine the effect of alpha-tocopherol, a free radical scavenger, on RBC deformability, mixed venous hemoglobin saturation (SvO2), arterial-venous oxygen content difference (C[a-v]O2), pHv, and survival during sepsis. DESIGN: Randomized controlled study. INTERVENTIONS: Sprague-Dawley rats were randomized to three groups: sham, cecal ligation and puncture, or alpha-tocopherol/cecal ligation and puncture (pretreatment with alpha-tocopherol before cecal ligation and puncture). MEASUREMENTS AND MAIN RESULTS: The cecal ligation and puncture group had a significantly (p less than .05) higher SvO2 and lower C (a-v)O2, pHv, and survival rate when compared with alpha-tocopherol/cecal ligation and puncture and sham groups. No difference in pHa existed between groups. CONCLUSIONS: The alpha-tocopherol treatment improves survival in sepsis. RBC deformability during sepsis is prevented by alpha-tocopherol, suggesting that free radicals may cause the decrease in RBC deformability. This study provides indirect evidence that decreased RBC deformability may play a role in the physiologic peripheral shunting and decreased microcirculatory flow that occurs during sepsis.

Effect of oxygen-free radical scavengers on survival in sepsis.

UNLABELLED: Sepsis remains a leading cause of death in the surgical intensive care unit (SICU) patient following major surgery or trauma. Recent work has demonstrated that oxygen-free radicals (OFR) generated during sepsis contribute to the pathogenesis of this syndrome. The purpose of this study was to evaluate the effect of various new free radical scavengers on survival in sepsis. A total of 85 male Sprague-Dawley rats were placed into one of the following treatment groups. CONTROL: cecal ligation and puncture (CLP); PRE-AT: pretreatment with alpha-tocopherol (AT) 10 mg/100 gm SC x 3 days, and 5 mg/100 gm IV prior to CLP; AT: 20 mg/100 gm at time of CLP and 4 hours following CLP; U74006F: (21-aminosteroid which inhibits lipid peroxidation) 3 mg/kg IV at the time of and 4 hours following CLP; U78517F: (alpha-tocopherol analogue) 3 mg/kg at the time of and 4 hours following CLP. Survival was determined at various time points up to 72 hours. Pretreatment with AT resulted in improved survival, whereas the novel OFR scavengers U78517F and U74006F significantly improved survival and were efficacious without pretreatment. It was concluded that OFR scavengers can improve survival in sepsis.

Reoperative versus conservative management for gastrointestinal fistulas.

Development of a fistula is a serious complication. It is necessary to identify its anatomic and pathologic features, as these can influence the outcome of treatment independent of the primary disease. Electrolyte abnormalities should be addressed as volume deficits are being restored. Sepsis, the most common cause of death in patients with fistulas, must be controlled, and the skin must be protected. Reoperation and conservative management are not opposing forms of therapy but rather are complementary.

A comparison of intravenous access sites for bolus injections during shock and resuscitation after emergency room thoracotomy with and without aortic crossclamping.

Thoracotomy with aortic crossclamping is used to resuscitate trauma victims. Pharmacologic boluses are often given via intravenous lines of central, brachial, or femoral origin. This study was undertaken to determine the efficacy of intravenous access site on delivery of a bolus injection to the heart with thoracotomy and aortic crossclamping during shock and resuscitation. Six dogs were anesthetized, intubated, and underwent brachial and femoral venotomy and Swan-Ganz insertion (central). Baseline measurements of central, brachial, and femoral transit times for 10 cc cold saline were obtained via Swan-Ganz thermistor. Each animal then underwent thoracotomy, aortic crossclamping alone, hemorrhage to blood pressure (BP) 50 mm Hg for 30 minutes with aorta unclamped and then aorta crossclamped and resuscitation with lactated Ringer's Solution with aorta unclamped and then crossclamped. Femoral-Brachial Index (FBI) was determined by dividing femoral transit time by brachial transit time at each observation. The data suggest that femoral access significantly prolongs bolus transit time when compared with central or brachial access during aortic crossclamping in the euvolemic, shock, or aggressively resuscitated model. Brachial access is therefore the preferred route for bolus injection delivery in the emergency room thoracotomy with or without aortic crossclamping because it provides expedient bolus delivery equal to central access and superior to femoral access.

Organ distribution of radiolabeled enteric Escherichia coli during and after hemorrhagic shock.

Translocation of intestinal bacteria to the blood during hemorrhagic shock (HS) has been confirmed in rats and humans. The current study was designed to trace the path of translocated intestinal bacteria in a murine HS model. Thirty-one rats were gavaged with 1,000,000 counts of viable 14C oleic acid-labeled Escherichia coli. Forty-eight hours later the animals were bled to 30 mmHg until either 80% of their maximal shed blood was returned or 5 hours of shock had elapsed and they were resuscitated with Ringer's lactate as previously described. Control animals were cannulated but not shocked. Eight rats immediately after shock and resuscitation, 6 rats 24 hours after shock, 3 rats 48 hours after shock, and 4 animals that died in shock had their heart, lung, liver, spleen, kidney, and serum harvested, cultured, and radioactive content measured. Translocated enteric bacteria are found primarily in the lung immediately after shock with redistribution to the liver and kidney 24 hours later. Animals surviving to 48 hours were capable of eliminating the majority of the bacteria from their major organ systems. Positive cultures for E. coli were also found in the blood, lung, liver, and kidney. We speculate that the inflammatory response stimulated by the bacteria in these organs may contribute to the multiple-organ failure syndrome seen after HS.

Kupffer cell-hepatocyte interactions and the changes in 1-14C-arachidonate incorporation in response to endotoxin in vitro.

The present experiments were undertaken to elucidate the effect of either the hepatocyte (HC) or hepatocyte supernatant on prelabeled endotoxin (LPS)-stimulated Kupffer cell (KC) arachidonic acid utilization. HC, KC, or their coculture were incubated for 18 hours with labeled 1-14C- arachidonic acid followed by a 24 hour incubation with 10 micrograms/ml LPS. LPS had no effect on the percent distribution of labeled arachidonate into the HC phospholipid or neutral lipid. KC showed a decreased percent neutral lipid labeled arachidonic acid distribution with generally no effect on the phospholipid. However, KC:HC cocultures or the addition of HC supernatant to KC exposed to LPS dramatically reversed the labeled arachidonate distribution into the KC with an increased incorporation into neutral lipid. Labeled PGE2 and PGD2 were increased in the KC following incubation with HC supernatant while only labeled PGE2 levels were elevated in the cocultures. The changes in the distribution of cell's labeled arachidonate required the addition of LPS. These results suggest that the HC can promote changes in the lipid fraction during sepsis by elaborating a substance that can modulate labeled arachidonate distribution in the KC lipids as well as stimulate prostaglandin production.

Hepatocyte modulation of Kupffer cell prostaglandin E2 production in vitro.

It is likely that dynamic interactions between hepatocytes and Kupffer cells contribute to the responses of these cell types both under normal conditions and during sepsis. In this study, we examined the influences of hepatocytes on the concentration of the inflammatory mediator PGE2 in Kupffer cell cultures. Evidence to suggest that cultured rat hepatocytes both metabolize PGE2 and produce a substance that promotes LPS-stimulated Kupffer cell PGE2 biosynthesis include the following: 1) PGE2 levels in Kupffer cell: hepatocyte coculture were lower than the levels in Kupffer cell cultures early after LPS stimulation; 2) 36 h after LPS, coculture PGE2 levels exceeded the levels in Kupffer cell cultures despite the demonstrated capacity for hepatocytes to metabolize PGE2; 3) a transferable, non-dialyzable, and heat-unstable factor in hepatocyte supernatant promoted PGE2 production when added to Kupffer cells with LPS or after LPS; 4) there was no increased PGE2 synthesis when the hepatocyte supernatant was added without LPS or if hepatocyte supernatant was preincubated with the Kupffer cells for 6 or 18 h before LPS administration; 5) there was an inability of the hepatocyte factor to promote PGE2 production in response to other macrophage-activating agents, including calcium ionophore A23187 or phorphol myristate acetate; and 6) there was no increased cell replication or protein synthesis in the Kupffer cell cultures following hepatocyte supernatant incubation. The increased Kupffer cell PGE2 production by the hepatocyte supernatant was not due to contamination of the hepatocyte supernatant by endotoxin or PGE2. These in vitro results raise the possibility that hepatocytes have the capacity to modulate local PGE2 levels by two distinct mechanisms. Hepatocytes can metabolize PGE2 as well as release factor(s) which promote LPS-induced PGE2 production by Kupffer cells.

A "treated" model for severe hemorrhagic shock: a comparison of conventional and germ-free animals.

In an unanesthetized "treated" model of severe hemorrhagic shock, a bacteremia originating from the animal's enteric flora was demonstrated by finding radiolabeled Escherichia coli in the blood as early as 2 hr after the onset of shock. In 50 patients admitted to our trauma unit, the observation was similar, with 56% positive blood cultures, when their mean arterial blood pressure was 80 mmHg or less. The relationship of bacterial translocation and the high post-shock mortality in our conventional (CV) animal model is being evaluated in germfree (GF) Sprague-Dawley rats. Preliminary observations in 15 GF animals showed 80% survival at 24 hr post-shock, 54% at 48 hr, and 42% at 72 hr compared with those of CV animals in previous experiments with survival at similar times of 73%, 20% and 7%, respectively.