Chromogenic endotoxin determination in blood — clinical relevance

Summary In a pilot study in 400 patients LPS-quantification in blood using chromogenic substrates, bacterial cultures and bacterial quantification were performed. Decreased plasma levels of antithrombin III and plasminogen were early predictors of gram-negative septicemia, which already were apparant 3 days prior to the first positive LPS-test. It is concluded that daily determinations of LPS may reduce the delay in proper antibiotic therapy.     

Effects of two bacterial products,muramyl dipeptide and endotoxin,on bone resorption in organ culture

Summary We have compared two components of bacterial cell walls, muramyl dipeptide (MDP) and lipopolysaccharide (LPS), for their effects on bone resorption as measured by the release of previously incorporated⁴⁵Ca. MDP is the smallest active component of peptidoglycan, whereas LPS is the active component of endotoxin. Fetal rat long bones were cultured for 5 days in a chemically defined medium supplemented with bovine serum albumin (BSA) or serum. LPS increased⁴⁵Ca release at concentrations of 0.03–1.0 μg/ml. LPS further purified by electrolytic dialysis (ED-LPS) was active at 0.01 μg/ml. ED-LPS was ineffective at such low concentrations in the presence of serum. The response to MDP was more variable than that to LPS, but bone resorption was stimulated at concentrations of 10⁻⁷–10⁻⁵ M. MDP was less effective or inactive in medium supplemented with serum. Stereoisomers of MDP that do not have adjuvant activity caused minimal stimulation of bone resorption, whereas 6-0-steroyl MDP stimulated resorption at 10⁻⁸ M. The stimulation of bone resorption by LPS and MDP was not inhibited by indomethacin. Both LPS and MDP increased lysosomal enzyme release in proportion to their effects on⁴⁵Ca release. LPS also markedly increased collagenase activity in the medium, but MDP did not. These results indicate that chemically different products of bacterial cell walls can stimulate bone resorption in vitro. These products may be distinguished by differences in dose response curve, serum inhibition, and collagenase release. Part of this work was presented at the 2nd Annual Meeting of the American Society for Bone and Mineral Research, Washington, D.C., June 1980 [1].     

Hypothalamic opioids and the acute-phase glycoprotein response in guinea pigs

Endogenous opioids (EO) probably do not modulate endotoxin (LPS)- or interleukin 1 (IL1)-induced fever because naloxone does not prevent its development. Yet, increases in CSF and hypothalamic levels of beta-endorphin have been reported during LPS-and IL1-induced fevers. Since IL1 also reduces the specific binding of opioids to their receptors in guinea pig brain, the opioids could be involved in modulating nonfebrile effects of IL1. To determine whether EO might have a role in the IL1-induced acute-phase glycoprotein response of guinea pigs, (1) naloxone (5 and 10 mg/kg, SC) was injected prior to LPS (S. enteritidis 2 micrograms/kg, IV; N = 5), and (2) morphine (MOR, 10 micrograms/microliter), [D-ala2]-met-enkephalinamide (DAME, 5 micrograms/microliter), or dynorphin A (DYN, 5 micrograms/microliter) was injected into the preoptic area (1 microliter, bilaterally; N = 8/treatment) or into the 3rd ventricle (N = 4/treatment); pyrogen-free saline was the control injection. Measurements were: core temperature (Tco) and, as indices of acute-phase glycoproteins, plasma levels of copper (Cu) and N-acetylneuraminic acid (NANA). Naloxone did not prevent the fever or the increases in plasma Cu and NANA levels evoked by LPS. The intracerebral administration of opioid agonists by either route induced variable rises in Tco, each with a different pattern, but no increases in plasma Cu and NANA levels. Thus, EO do not participate in the central modulation of acute-phase glycoprotein synthesis, but may have a role in influencing other nonthermal IL1 effects in the CNS.     

84. Endotoxinschock: Erkennung und Behandlung

Zusammenfassung Der Endotoxinschock ist die häufigste Form des septischen Schocks. Endotoxin, ein makromolekulares Lipopolysaccharid wird beim Zerfall aus der Zellwand der gramnegativen Keime freigesetzt. Bei Patienten mit bakterieller Peritonitis sind: Fieber über 38°C, Thrombocytopenie, Leukocytose, Lactacidose, Kreatininanstieg hinweisende Zeichen. Die Frühlaparotomie ist bei bakterieller Peritonitis der entscheidende Schritt zur Vermeidung eines Endotoxinschocks.     

Biological reactions resulting from endotoxin adsorbed on dialysis membrane: an in vitro study

Some types of dialysis membrane are known to adsorb endotoxin (ET). It is suggested that the biocompatibility of dialysis membrane is enhanced by adsorption and inhibition of ET. This study attempts to clarify the membrane-mediated biological reaction of the ET that is adsorbed to a dialysis membrane. After a dialysis circuit was prepared, contaminated dialysate was introduced on the dialysate side of a polyether polymer alloy (PEPA) membrane that adsorbs ET while saline solution or blood were introduced on the blood side, and the difference in ET adsorption between the two set-ups was measured. Further, the side filled with blood was left standing for 2 h, after which the changes in the amount of interleukin 1 receptor antagonist (IL-1Ra) produced from the whole blood were also assayed. Significantly more ET was adsorbed to the dialysis membrane when blood rather than saline was on the other side. In addition, the IL-1Ra production from the dialysis membrane that adsorbed ET was significantly higher. The ET adsorbed to the dialysis membrane may influence a living body even if it does not pass through the membrane. Accordingly, it is difficult to assume that the adsorption of ET to the membrane enhances its biocompatibility.     

Developing ovarian follicles inhibit the endotoxin-induced glomerular inflammatory reaction in pseudopregnant rats

PROBLEM: We tested the hypothesis that developing ovarian follicles produce factors inhibiting the endotoxin induced inflammatory response. METHOD OF STUDY: Pseudopregnant rats were treated with FSH to induced follicular development (FSH-rats). For control we used untreated pseudopregnant rats (PSP-rats) and rats in the follicular phase of the ovarian cycle (C-rats). All rats were infused with either saline or endotoxin. Three days after the infusion rats were sacrificed and kidney specimens were snapfrozen. Cryostat kidney sections were stained for the presence of monocytes, granulocytes, CD11a- and CD11b-positive cells and for ICAM-1 expression. RESULTS: The results show that induction of follicular development in pseudopregnant rats inhibited glomerular infiltration of monocytes and CD11b(+) cells, while it did not affect the other parameters, i.e. glomerular granulocyte number, CD11a(+) cells and glomerular ICAM-1 expression. CONCLUSION: Developing ovarian follicles produce factors inhibiting monocyte responses to endotoxin.     

Severe vagal response after endotoxin administration in humans

Objective Endotoxin administration to humans is a common means to study systemic inflammation. Worldwide, thousands of volunteers have received endotoxin, and adverse events are rarely reported. The aim of this report was to increase awareness of specific risks of the intravenous administration of endotoxin to human volunteers.Design Report of four cases who developed severe bradycardia or protracted asystole after administration of endotoxin. Interviews with investigators at three large centers that conduct normal volunteer endotoxin studies.Setting Clinical research unit.Cases Four subjects developed severe bradycardia or protracted asystole, approximately 1 h after administration of endotoxin. Further analyses revealed that the subjects had a history of vasovagal syncope or a positive head-tilt test, indicating increased vagal sensitivity. Relative volume depletion associated with fasting overnight may have predisposed these subjects to this condition.Conclusions These responses are very rare and are likely due to the cardioinhibitory Bezold-Jarisch reflex. A thorough screening regarding a history of vagal sensitivity and liberal oral or intravenous fluid administration prior to and during the endotoxin challenge may decrease the risk of these events.P. Pickkers is a recipient of a Clinical Fellowship grant of the Netherlands Organisation for Scientific Research (ZonMw)     

Clinical evaluation of PMX-DHP for hypercytokinemia caused by septic multiple organ failure

Endotoxin-adsorbing fibers have been applied to treat septic shock patients. The limitations of endotoxin hemoadsorption therapy (PMX-DHP) and the optimal time to start PMX-DHP were examined in patients with septic multiple organ failure with hypercytokinemia (interleukin-6 = 1000 pg/mL). Subjects were separated into those who survived more than 28 days after the start of PMX-DHP therapy (S group) and those who did not (N-S group). Severity of symptoms and background factors, blood biochemical parameters, hemodynamic parameters, PaO(2)/FiO(2), pathogens, endotoxin, cytokines, and vascular endothelial cell function-related markers were examined before and after PMX-DHP. Number of days from onset of shock (or symptom development) to PMX-DHP initiation was longer in the N-S group than in the S group. These results suggest that PMX-DHP could save more lives in patients with septic multiple organ failure with IL-6 = 1000 pg/mL when applied early after the onset of shock.     

Regulation of pro-inflammatory and anti-inflammatory cytokine responses by Kupffer cells in endotoxin-enhanced reperfusion injury after total hepatic ischemia

The effects of Kupffer cells on cytokine responses in endotoxin-enhanced reperfusion injury after total hepatic ischemia were investigated in this study. Male rats pretreated with either normal saline solution (NS group) or gadolinium chloride (GdCl(3)) to inhibit Kupffer cell function (GC group) were subjected to 60 min of hepatic ischemia. These animals received either normal saline solution or sublethal doses of endotoxin (1 mg/kg) at reperfusion. In the NS group, endotoxin administration induced an enhanced tumor necrosis factor-alpha (TNF-alpha) and interleukin-10 production 1 h after reperfusion with a subsequent peak of macrophage inflammatory protein-2 (MIP-2) levels, which resulted in a 7-day survival rate of 30%. Despite endotoxin administration, GdCl(3) pretreatment significantly suppressed TNF-alpha and increased interleukin-10 production 1 h after reperfusion, which led to a decline in MIP-2 production and amelioration of functional and structural liver damage with a 7-day survival rate of 80%. Augmented pro-inflammatory and anti-inflammatory cytokine responses by Kupffer cells were associated with endotoxin-enhanced reperfusion injury after hepatic ischemia. Kupffer cell blockade has a potential to attenuate the insult via modulation of cytokine responses.