Multiple systems organ failure: I. The basal state

Protective effect of Hypericum perforatum in zymosan-induced multiple organ dysfunction syndrome: Relationship to its inhibitory effect on nitric oxide production and its peroxynitrite scavenging activity

Hypericum perforatum is a medicinal plant species containing many polyphenolic compounds, namely flavonoids and phenolic acids. Since polyphenolic compounds have high antioxidant potential, we have investigated the effects of H. perforatum extract on the development of multiple organ dysfunction syndrome caused by zymosan (500 mg/kg, administered i.p. as a suspension in saline) in mice. Organ failure and systemic inflammation in rats was assessed 18 h after administration of zymosan and/or H. perforatum extract and monitored for 12 days (for loss of body weight and mortality). Treatment of mice with H. perforatum extract (30 mg/kg i.p., 1 and 6h after zymosan) attenuated the peritoneal exudation and the migration of polymorphonuclear cells caused by zymosan, pulmonary, intestinal and pancreatic injury, and renal dysfunction as well as the increase in myeloperoxidase in the lung and intestine. Immunohistochemical analysis for inducible nitric oxide synthase (iNOS), nitrotyrosine, and poly(ADP-ribose) (PAR) revealed positive staining in lung and intestine tissues obtained from zymosan-injected mice. The degree of staining for nitrotyrosine, iNOS, and PAR was markedly reduced in tissue sections obtained from zymosan-treated mice, which received H. perforatum extract. In conclusion, this study provides evidence, for the first time, that H. perforatum extract attenuates the degree of zymosan-induced multiple organ dysfunction syndrome in mice.

MOF, MODS, and SIRS: what is in a name or an acronym?

The most prominent contributions to multiple organ failure, multiple organ dysfunction syndrome, and systemic inflammatory response syndrome are described in this article. However, it is quite possible that there are others that have been missed. The problem of organ failure continues to perplex clinicians and scientists, and it contributes to fatal outcomes for patients with illnesses, infections, and injuries after operations. Although we know a fair bit about these problems, we frequently can do little about it. The best approach remains support to prevent failure.

Protective effects of M40401, a selective superoxide dismutase mimetic, on zymosan-induced nonseptic shock

OBJECTIVE

Zymosan enhances formation of reactive oxygen species, which contributes to the pathophysiology of organ failure during nonseptic shock. Here we have investigated the effects of M40401, a new superoxide dismutase mimetic, on the organ failure associated with nonseptic shock caused by zymosan in rats.

DESIGN

Experimental study.

SETTING

Laboratory.

SUBJECTS

Male Sprague-Dawley rats.

INTERVENTIONS

We investigated the effects of M40401 on the organ failure associated with nonseptic shock caused by zymosan (500 mg/kg, administered intraperitoneally as a suspension in saline) in rats.

MEASUREMENTS AND MAIN RESULTS

Organ failure and systemic inflammation in rats were assessed 18 hrs after administration of zymosan and/or M40401 and were monitored for 12 days (for loss of body weight and mortality). Treatment of rats with M40401 (10 mg/kg intraperitoneally, 1 and 6 hrs after zymosan) attenuated the peritoneal exudation and the migration of polymorphonuclear cells caused by zymosan. M40401 administration also attenuated the lung and intestinal injury (histology) as well as the increase in myeloperoxidase activity and malondialdehyde concentrations caused by zymosan in lung and intestine. Immunohistochemical analysis for nitrotyrosine and for poly(adenosine 5'-diphosphate-ribose) revealed positive staining in lung and intestine from zymosan-treated rats. The degree of staining for nitrotyrosine and poly(adenosine 5'-diphosphate-ribose) was markedly reduced in tissue sections obtained from zymosan-treated rats administered with M40401.

CONCLUSION

This study provides the first evidence that M40401 attenuates the degree of zymosan-induced nonseptic shock in the rat.

Effects of calpain inhibitor I on multiple organ failure induced by zymosan in the rat

OBJECTIVE

Zymosan enhances the formation of reactive oxygen species, which contributes to the pathophysiology of multiple organ failure. We investigated the effects of calpain inhibitor I (5, 10, or 20 mg/kg) on the multiple organ failure caused by zymosan (500 mg/kg, administered intraperitoneally as a suspension in saline) in rats.

SETTING

University research laboratory.

SUBJECTS

Male Sprague-Dawley rats.INTERVENTIONS Multiple organ failure in rats was assessed 18 hrs after administration of zymosan and/or calpain inhibitor I and was monitored for 12 days (for loss of body weight and mortality rate).

MEASUREMENT AND MAIN RESULTS

Treatment of rats with calpain inhibitor I (5, 10, or 20 mg/kg intraperitoneally, 1 and 6 hrs after zymosan) attenuated the peritoneal exudation and the migration of polymorphonuclear cells caused by zymosan in a dose-dependent fashion. Calpain inhibitor I also attenuated the lung, liver, and intestinal injury (histology) as well as the increase in myeloperoxidase activity and malondialdehyde concentrations caused by zymosan in the lung, liver, and intestine. Immunohistochemical analysis for nitrotyrosine and for poly(adenosine-disphosphate-ribose) revealed positive staining in lung, liver, and intestine from zymosan-treated rats. The degree of staining for nitrotyrosine and poly(adenosine-disphosphate-ribose) was reduced markedly in tissue sections obtained from zymosan-treated rats administered calpain inhibitor I (20 mg/kg intraperitoneally). Furthermore, treatment of rats with calpain inhibitor I significantly reduced the expression of inducible nitric oxide synthase and cyclooxygenase-2 in lung, liver, and intestine.

CONCLUSION

This study provides the first evidence that calpain inhibitor I attenuates the degree of zymosan-induced multiple organ failure in the rat.

Beneficial effects of tempol, a membrane-permeable radical scavenger, on the multiple organ failure induced by zymosan in the rat

BACKGROUND AND METHODS

We investigated the effects of tempol, a membrane-permeable radical scavenger, on the multiple organ failure (MOF) caused by zymosan in the rat. Zymosan (500 mg/kg, suspended in saline solution, ip) enhances formation of reactive oxygen species, which contribute to the pathophysiology of MOF. After zymosan or saline administration, animals were monitored for 12 days.

RESULTS

Treatment of rats with tempol (10, 30, or 100 mg/kg ip, 1 and 6 hrs after zymosan) attenuated the peritoneal exudation and the migration of polymorphonuclear cells caused by zymosan in a dose-dependent fashion. Tempol also attenuated the lung, liver, and intestinal injury (histology) as well as the increase in the concentrations of myeloperoxidase and malondialdehyde caused by zymosan in the lung, liver, and intestine. Immunohistochemical analysis for nitrotyrosine and for poly(adenosine 5'-diphosphate-ribose)synthetase demonstrated a positive staining in lung, liver, and intestine from zymosan-treated rats. The degree of staining for nitrotyrosine and for poly(adenosine 5'-diphosphate-ribose) synthetase was markedly reduced in tissue sections obtained from zymosan-treated rats that had received tempol (100 mg/kg ip). Furthermore, treatment of rats with tempol significantly reduced the following: a) the formation of peroxynitrite, b) the DNA damage, c) the impairment in mitochondrial respiration, and d) the decrease in the cellular concentration of oxidized nicotinamide adenine dinucleotide observed in macrophages harvested from the peritoneal cavity of rats treated with zymosan.

CONCLUSION

This study provides the first evidence that tempol, a small molecule that permeates biological membranes and scavenges reactive oxygen species, attenuates the degree of MOF associated with zymosan-induced peritonitis in the rat.

Pulmonary damage by Vibrio vulnificus cytolysin

Vibrio vulnificus is an estuarine bacterium that causes septicemia and serious wound infection. Cytolysin produced by V. vulnificus has been incriminated as one of the important virulence determinants of bacterial infection. Cytolysin (8 hemolytic units) given intravenously to mice via their tail veins caused severe hemoconcentration and lethality. Cytolysin treatment greatly increased pulmonary wet weight and vascular permeability as measured by (125)I-labeled albumin leakage without affecting those factors of other organs significantly. Blood neutrophils were markedly decreased in number after cytolysin injection, with a concomitant increase in the level of pulmonary myeloperoxidase activity, indicating that cytolysin-induced neutropenia might be due to pulmonary sequestration of neutrophils. By microscopic examination, severe perivascular edema and neutrophil infiltration were evident in lung tissues. These results suggest that increased vascular permeability and neutrophil sequestration in the lungs are important factors in lethal activity by cytolysin.

Plasma concentrations of cytokines, their soluble receptors, and antioxidant vitamins can predict the development of multiple organ failure in patients at risk

OBJECTIVES

The aims of this study were: a) to evaluate plasma concentrations of cytokines and their soluble receptors, as well as antioxidant substances in patients at high risk of developing multiple organ failure; b) to investigate early change: and c) to examine the possible prognostic value of these elements.

DESIGN

Prospective analysis.

SETTING

Surgical intensive care unit (ICU) of a university hospital.

PATIENTS

sixteen patients at risk for multiple organ failure.

MEASUREMENTS AND MAIN RESULTS

Ten patients developed multiple organ failure and five of them died. Whereas tumor necrosis factor-alpha (TNF-alpha) plasma concentrations were only borderline higher in patients developing multiple organ failure, TNF-soluble receptors 55 and 75 were significantly increased during all ICU days compared with patients not going into organ failure. Interleukin-6 plasma concentrations were higher in patients developing multiple organ failure during the first 2 days after ICU admission. The antioxidant vitamin C was significantly decreased in patients going into multiple organ failure during all ICU days. Other biochemical markers of antioxidant activity, such as vitamin E, copper, and zinc plasma concentrations, did not differ between the two groups.

CONCLUSIONS

Our data suggest that there is a marked increase in anti-TNF activity and a decrease of antioxidant defense in patients at risk of developing multiple organ failure. The predictive value of plasma concentrations of circulating TNF-soluble receptors and vitamin C in this type of patient needs further evaluation.

Metabolic abnormalities of mitochondrial redox potential in postburn multiple system organ failure

Forty-five burn patients underwent sequential assays for plasma acetoacetate and beta-hydroxybutyrate concentrations as well as plasma amino acid levels. Those patients who went on to develop multiple system organ failure were noted to have a decrease in their acetoacetate concentration with time, whereas there was no change in those patients who failed to develop multiple system organ failure. The plasma concentration of beta-hydroxybutyrate was not altered by multiple system organ failure. In addition, the plasma acetoacetate/beta-hydroxybutyrate ratio was found to be directly related to the plasma concentration of branched chain amino acids and inversely related to the concentration of aromatic amino acids.

[Multiple trauma: definition, shock, multiple organ failure]

Multiple organ failure (MOF) following major trauma occurs in response to perfusion deficits, a persistent inflammatory focus, or a persistent focus of dead and/or injured tissue. Several pathophysiologic aspects are considered relevant to current clinical practice. Their application in settings of trauma and surgical sepsis reduces overall mortality and incidence of multiple organ failure. With regard to the pathophysiologic background (I) microcirculatory resuscitation, (II) source control, and (III) metabolic support appear to be important therapeutic principles. (I) Microcirculatory Resuscitation: Since time is a critical factor in damage control, resuscitation and restoration of microvascular perfusion needs to occur as soon as possible if multiple system organ failure is to be avoided during the later time course. (II) Source control: The best treatment for multiorgan failure appears to be prevention. With early, aggressive control or removal of risk factors for multiple organ failure, namely early surgical intervention for control of hemorrhage, control of potential septic sources, decompression, and early fracture stabilization reductions in the incidence and mortality of MOF have been observed. Metabolic support: Malnutrition appears to be an important cofactor in morbidity and mortality. (III) Metabolic support needs to be started early and prior to the phenomenon of nitrogen retention during the hypermetabolic state of multiple organ failure.

The multiple organ failure syndrome

Technology that has made it possible to resuscitate the severely sick and injured from formerly lethal shock has exposed a new disease. A potential sequela of ruptured aneurysm, acute pancreatitis, septic shock, burns, surgical complications, and trauma, MOF syndrome is the leading cause of death in surgical ICUs. Aggressive monitoring and prompt therapy can save lives.

Hypermetabolism in the acute stage of hemorrhagic cerebrovascular disease

Oxygen consumption (VO2), carbon dioxide production (VCO2), urinary nitrogen excretion, respiratory quotient, resting energy expenditure (REE), %REE, and the consumption rates of carbohydrate, fat, and protein (%CHO, %Fat, %Prot, respectively) were determined pre- and postoperatively by indirect calorimetry in 13 patients with ruptured intracranial aneurysms and 11 patients with hypertensive intracerebral hemorrhage in the acute stage. The preoperative VCO2, VO2, urinary nitrogen excretion, respiratory quotient, REE, and %REE were, respectively (mean +/- standard deviation): 171 +/- 46 ml/min, 203 +/- 56 ml/min, 10.3 +/- 1.7 gm/day, 0.84 +/- 0.01, 1397 +/- 389 Cal/day, and 129% +/- 8%. The values for VCO2, VO2, REE, and %REE were all increased above normal levels. The %Prot was increased to 26.1% +/- 9.1%. In the postoperative period, the VCO2, VO2, urinary nitrogen excretion, REE, and %REE significantly increased to: 186 +/- 44 ml/min, 229 +/- 56 ml/min, 14.8 +/- 2.9 gm/day, 1557 +/- 384 Cal/day, and 141% +/- 21%, respectively. The %Fat and %Prot also increased significantly, but the %CHO significantly decreased. Preoperatively, in the patients with ruptured intracranial aneurysms, there was a greater increase in %Prot in eight patients classified (according to Fischer) as having a Group 3 or 4 subarachnoid hemorrhage (SAH) on computerized tomography than in five patients classified as having a Group 1 or 2 SAH. In summary, increased metabolic expenditure, especially increased catabolism of protein and fat, is characteristic of accompanying hemorrhagic cerebrovascular disease, and there is an increase in consumption of fat and protein in the postoperative period. Lack of precise knowledge about the cause and consequences of these metabolic responses makes it impossible at present to judge the optimal extent of nutritional replacement. The hypermetabolic state should be taken into consideration when caring for these patients as it may cause weight loss, poor wound healing, and susceptibility to infection.

Clinical pharmacological and therapeutic considerations in general intensive care. A review

The application of clinical pharmacological concepts and therapeutic standards in intensive care settings presents particularly difficult problems due to the lack of adequately controlled background information and the highly variable and rapidly evolving clinical conditions where drugs must be administered and their impact evaluated. In this review, an attempt has been made to discuss the available knowledge within the framework of a problem-oriented approach, which appears to provide a more clinically useful insight than a drug-centred review. Following a brief discussion of the scanty data and the most interesting models to which reference can be made from a pharmacokinetic point of view (the burn patient being taken as an example), the review concentrates on the main general intervention strategies in intensive care patients. These are based mainly on non-pharmacological measures (correction of fluid and electrolyte balance, total parenteral nutrition, enteral nutrition, oxygenation and ventilatory management) and are discussed with respect to the specific challenge they present in various clinical conditions and organ failure situations. In addition, 4 major selected clinical conditions where general management criteria and careful use of prophylactic and therapeutic drug treatments must interact to cope with the variety of presentations and problems are reviewed. These include: acute cerebral damage; anti-infective prophylaxis and therapy; cardiovascular emergencies; and problems of haemostasis. Each problem is analysed in such a way as to frame the pharmacological intervention in its broader context of the underlying (established or hypothesised) pathophysiology, with special attention being paid to those methodological issues which allow an appreciation of the degree of reliability of the data and the recommendations which appear to be practiced (often haphazardly) in intensive care units. The thorough review of the published literature provided (up to mid-1986) clearly shows that in this field the quality of randomised controlled and epidemiological studies is rather unsatisfactory. It would be highly beneficial to research and to clinical care if larger multicentric protocols and prospective epidemiological comparative investigations could be carried out to investigate more timely and adequately the variables which determine drug action, and the final outcome in the many subgroups of patients which must be considered in a proper stratification of intensive care unit populations.

The gut origin septic states in blunt multiple trauma (ISS = 40) in the ICU

The association between support elements (ventilator days = Vd, enteral protein = EnP, number of antibiotics per day = AB/d) and the magnitude of the septic state (SSS) and its bacteriologic manifestations (bacti. log) in 66 patients with blunt multiple trauma (mean HTI-ISS = 40) over 1649 days have been studied retrospectively. SSS is measured by summing the standard deviation units of change in the septic direction for the 16 measurements taken every day in the intensive care unit. Increasing Vd is tightly associated with an increasing SSS (r = +0.52), after day 10 an increasing bacti. log (r = +0.21 to +0.32), and an increasing AB/d (r = +0.26) (all p less than 0.001, N = 1615 - 1626). The independent variables that best predicted Vd were delayed operations (DORS), day of rising EnP, and total positive blood cultures (TPC) (adj. R sq. = 0.84, F = 104, dF = 3/59). An increasing AB/d was associated with an increasing SSS (r = +0.38), increasing Vd (r = +0.26), and an increased bacti. log (r = +0.14 to +0.18) (all p less than 0.001, N = 1615). Only an increased EnP was consistently associated with a reduced SSS (r = -0.38) and a reduction in bacti. log (r = -0.10 to -0.21) (all p less than 0.001, N = 1626-1636). The independent variables Vd, EnP, AB/d, and TPC best predicted SSS for all surviving patients (adj. R sq. = 0.42, F = 268, dF = 4/1496). The patients who died of sepsis were not different in terms of bacti. log from those with equal Vd but were distinguished by zero EnP, high AB/d, and persistent ventilatory support. In conclusion, DORS is tightly associated with increased Vd, SSS, AB/d, and zero EnP. If Vd exceeds 10, there is an increasing bacti. log and evidence of infection probably from the gut. This responds only to increased EnP and not to AB/d. Death due to sepsis is not associated with increased bacti. log but with zero EnP and high AB/d and their consequences.

Survival from hepatic transplantation. Relationship of protein synthesis to histological abnormalities in patient selection and postoperative management

Forty-one patients, all in end stage hepatic failure, underwent 46 liver transplantations with a long-term survival rate of 63%. Six patients died of uncontrollable bleeding due to primary graft malfunction at or immediately after operation. Nine died early or late with overwhelming infection. In addition to clinical assessment, needle liver biopsy, central plasma clearance rate of amino acids (CPCR-AA), and routine "liver function tests" were employed to aid in selection of patients for transplantation and for guidance in postoperative management. Although liver biopsies usually afforded an exact diagnosis, neither they nor the routine liver function tests quantitated the extent to which hepatocyte function was impaired. CPCR-AA, which measures the rate of amino acid uptake by the liver and other central tissues for oxidation, gluconeogenesis, and protein synthesis was 91 +/- 9 ml/M2/min in the preoperative transplant group. This compares with a value of 97 +/- 16 in a previously studied series of cirrhotics who died following other forms of surgery and a CPCR-AA of 220 +/- 26 ml/m2/min in those who survived. In addition, the preoperative CPCR-AA was found to correlate with the in vitro hepatic protein synthetic rate of slices from the resected recipient liver (r = 0.72, p less than 0.02). After operation, serial hepatic needle biopsies were classified by histology into four grades of injury, ranging from normal liver transplant (Grade I) to mild hypoxic or rejection injury (Grade II), viral hepatitis (Grade III), and severe hypoxic or rejection injury (Grade IV). Significant relationships of the histological grades to ultimate mortality, CPCR-AA, and prothrombin times were found. CPCR-AA and prothrombin time correlate inversely (r = 0.57, p less than 0.001), further demonstrating the relationship of CPCR-AA to protein synthesis of clotting factors. These patterns of posttransplant response were delineated by serial CPCR-AA values. "Early" responders had values over 290 ml/M2/min and all survived. Twelve patients with delayed response were characterized by values of 150 +/- 12, rising to over 200 ml/M2/min after 2 weeks. Two who failed to increase CPCR-AA died. In six "poor" responders, CPCR-AA with Grade IV injury remained below 110 ml/M2/min. All died except for one whose CPCR-AA subsequently rose following retransplantation. It is concluded that percutaneous hepatic needle biopsies and CPCR-AA measurements in combination are of proven value, not only in understanding the nature of injury and functional impairment of the liver, but are also important as guides to selection of patients and for their posttransplant management.

Effects of branched chain enriched amino acid solutions on septic rats

An experimental study was performed to determine the effects of a BCAA enriched amino acid solution on sepsis in rats. After sepsis had been induced in male Wistar rats by caecal ligation and puncture the animals were divided into four groups according to the amino acid solutions infused: Group B-I, a solution containing no amino acid; Group B-II, a commercially available solution containing 21.1% branched chain amino acids (BCAA); Group B-III, a solution containing 38.7% BCAA and Group B-IV, that containing BCAA only. The control group of the animals received simple laparotomy and infusion without amino acids. Infusion was continued for 96 hours after the operation and all the solutions had the same caloric and nitrogen value. Group B-I had a plasma aminogram peculiar to sepsis; a significant rise in the concentration of the total 17 amino acids (TAA), BCAA and aromatic amino acid (AAA) together with a decrease in the BCAA/AAA ratio. Furthermore, the arterio-venous difference (AV-D) of AAA and BCAA showed a large negative value. In the three groups infused with amino acids, only Group B-III showed a significant improvement in the survival rate and nitrogen balance compared with Group B-I. Moreover, not only did the concentration of TAA and AAA significantly decline, but also the BCAA/AAA ratio increased. Therefore, the abnormal aminogram in sepsis tended to return to the control level. In Group B-IV despite the significant decrease of the peripheral TAA, no improvement in plasma aminogram, nitrogen balance or survival rate were shown. In Group B-II, in addition to the persisting plasma aminogram changes and peripheral efflux of amino acids, no improvement of survival rate were noted. Therefore, it was concluded that an amino acid composition richer in BCAA and lower in both AAA and SCAA is beneficial in the treatment of sepsis.

Macrophage-mediated modulation of hepatic function in multiple-system failure

Hepatic insufficiency associated with the multiple-system organ-failure (MSOF) syndrome is a frequent sequellae of sepsis and severe trauma. Although its etiology is poorly understood, there is a growing literature suggesting that it may be mediated in part by secretory products of cells of monocyte/macrophage lineage including Kupffer cells. Several investigators have reported in vitro macrophage/Kupffer cell-mediated cytotoxicity toward target cells following appropriate stimulation. In addition, in vivo hepatocyte toxicity has been documented following activation of the reticuloendothelial system. The role of several secretory products including active oxygen intermediates, neutral proteases, and interleukin 1 in this cell-mediated model of hepatocellular modulation is reviewed.

Survival from sepsis. The significance of altered protein metabolism regulated by proteolysis inducing factor, the circulating cleavage product of interleukin-1

Amino acid (AA) arterial blood plasma concentrations, K1 (peripheral production + infusion rates), and central plasma clearance rates (K1 divided by arterial concentration) (CPCR-AA) were measured in 70 seriously septic patients. All of these people were in the "hyperdynamic" state at the time of observation. Thirty-seven recovered and 33 died. In addition, 10 noninfected, nontraumatized patients about to undergo laparotomy were studied. In 31 patients receiving parenteral alimentation, CPCR-AA was 326 +/- 38 in survivors and 160 +/- 17 ml/M2/min in the deaths (p less than 0.005). In 58 patients studied, while fasted with no intravenous amino acid infusion, values for CPCR-AA were: survivors 202 +/- 22 (28) and deaths 112 +/- 16 (30) ml/M2/min (p less than 0.002). The CPCR-AA in 10 noninfected patients was only 68 +/- 11 ml/M2/min. CPCR-AA in 19 patients correlated with hepatic protein synthetic rates in liver biopsies obtained simultaneously (r = 0.658, p less than 0.01), which shows that CPCR-AA is an indicator of visceral protein synthesis. To study the regulation of amino acid metabolism by synthesis. To study the regulation of amino acid metabolism by proteolysis inducing factor (PIF), the proteolysis inducing activity (PIA) of the plasma fraction (0-50,000 D) was measured 55 times in conjunction with metabolic studies. No significant differences existed in PIA between survivors and deaths. However, in those patients who recovered, PIA was significantly correlated to both peripheral amino acid production (r = 0.773, p less than 0.001) and to CPCR-AA (r = 0.721, p less than 0.001). This observation demonstrates the presence of one or more circulating agents affecting amino acid flux. PIA measured simultaneously in vivo correlated with in vitro protein synthetic rate in incubated liver biopsies (r = 0.653, p less than 0.01). PIF (4,000 D), isolated by chromatography, in patients without amino acid infusion was 35 +/- 3% in survivors and 33 +/- 6% in deaths (N.S.) and only 9 +/- 3% over control in noninfected patients. In patients who recovered, PIF titre was strongly correlated with peripheral amino acid production (r = 0.798, p less than 0.001) and with CPCR-AA (r = 0.835, p less than 0.001). However, values for patients who later died were significantly less for a given PIF titre. Thus, it is concluded that survival from sepsis is, in part, dependent on a significantly elevated CPCR-AA and hepatic protein synthesis, both of which appear to be related to the blood plasma PIF titre.

Killed Escherichia coli stimulates macrophage-mediated alterations in hepatocellular function during in vitro coculture: a mechanism of altered liver function in sepsis

Hepatic dysfunction is a poorly understood and highly lethal component of multiple-system organ failure. Both in vivo and in vitro studies of "liver" function have generally neglected hepatocyte-Kupffer cell interactions. In the following experiments, isolated hepatocytes were cocultivated with unstimulated peritoneal cells, predominately macrophages, which served as a readily available Kupffer cell analog. Coculture of hepatocytes with peritoneal cells resulted in little or no change in [3H]leucine incorporation into hepatocyte protein. When gentamicin-killed Escherichia coli cells (GKEC) were added to coculture, there was a marked decrease in hepatocyte [3H]leucine incorporation. In contrast, GKEC added to hepatocytes alone had no effect. Kinetic data revealed an 8-h delay before any significant decrease in leucine incorporation into hepatocyte protein after the addition of GKEC to the coculture. The maximal decrease in hepatocyte [3H]leucine incorporation occurred 24 h after GKEC were added. The decrease observed 24 h after GKEC were added disappeared almost completely after 48 h of coculture. Similar alterations in cocultured hepatocyte protein synthesis were observed after the addition of phorbol myristate acetate, lipopolysaccharide, or muramyl dipeptide, a component of bacterial peptidoglycan. Hepatocyte viability by trypan blue exclusion was unchanged, and gross morphology by light or electron microscopy was unaffected. We propose that during sepsis, macrophages (Kupffer cells) respond to circulating microbial products and mediate alterations in hepatocyte function. These experiments underscore the important role of Kupffer cell function in attempts to understand hepatic malfunction in multiple-system organ failure.

Parenteral nutrition of injured patients: Effect of manipulation of aminoacid infusion (increasing branched chain while decreasing aromatic and sulphurated aminoacids)

Sixteen critically ill injured patients received parenteral nutrition providing nitrogen (0.34 g kg(-1) day(-1)) and glucose (32 kcal kg(-1) day(-1)) for 5 days. They were randomly divided into two groups with respect to aminoacid supply: an essential aminoacid solution vs the same solution enriched in branched chain amino acid (BCAA) content and decreased in phenylalanine and methionine content (mean BCAA intake, 0.55 vs 0.69 g kg(-1) day(-1)). Basal values of nitrogen metabolism without treatment showed no difference between the two groups. Nitrogen losses and 3 methylhistidine (3-MEH) excretion were elevated; the plasma aminoacid pattern was altered by the trauma and except for phenylalanine, aspartate and glutamate, plasma aminoacid concentrations were decreased below normal values. Net muscular aminoacid output was demonstrated by femoral arterio-venous (av) differences that were all negative except for glutamate and citrulline TPN with both solutions improved the nitrogen balance and reduced the negative aminoacid balance across the leg. Adjusting a TPN regimen to increase the BCAA content without altering the total nitrogen infused, had no effect on overall nitrogen balance, but exerted a beneficial effect on body protein catabolism, as assessed by the urinary 3-MEH excretion rate, and a transient improvement in the aminoacid balance across the leg at the peak of the infusion. The short-lived effect of BCAA suggest a metabolic effect of these aminoacids which deserves further study.

Muscle proteolysis induced by a circulating peptide in patients with sepsis or trauma

Accelerated proteolysis of muscle is characteristic in patients with trauma or sepsis, but its cause is not well understood. Using rat muscle in vitro, we developed a bioassay to compare the proteolytic activity of plasma from 50 patients with trauma or sepsis with that of plasma from 14 normal volunteers and from 15 patients who had undergone "clean" elective surgical procedures. The mean proteolytic activity in the plasma of patients with trauma or sepsis was found to be 190 +/- 8.0 per cent of the control value (rat muscle incubated in medium alone), whereas the activity in normal plasma was 124 +/- 4.5 per cent (P less than 0.001). The activity in the plasma of patients who had undergone elective surgery was slightly elevated at 142 +/- 2.5 per cent (P less than 0.005). In 25 of the patients with trauma or sepsis the rate of amino acid release from one leg was measured by subtracting the concentration of tyrosine plus phenylalanine in the femoral artery plasma from that in the femoral vein; this rate correlated well with the bioactivity of the plasma in the bioassay system (r = 0.67, P less than 0.001). By means of ultrafiltration and chromatography, the plasma factor inducing proteolysis was isolated and found to be a peptide, probably containing sialic acid, with a chain of 33 amino acids and a molecular weight of approximately 4274 daltons.