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)     

“双击”大鼠脾脏IκBα和TLR4基因表达及参麦注射液对其影响

目的通过观察“双击”(失血性休克+内毒素)大鼠脾脏中IκBα和TLR4mRNA表达及参麦注射液对其的影响,探讨参麦注射液抗休克的分子机制。方法大鼠随机分为单纯失血性休克(HS)组、“双击”(HS+LPS)组、地塞米松(HS+LPS+DEX)组和参麦注射液(HS+LPS+SM)组。大鼠第一次打击为失血性休克(MBP维持在5.3kPa),第二次打击舌下静脉LPS注射(1.5mg/kg),舌下静脉给予参麦注射液(28.8mg/kg)、地塞米松(2mg/kg)。4h后测定脾脏组织中IκBα和TLR4mRNA表达。结果HS+LPS+DEX组和HS+LPS+SM组TLR4mRNA表达高于HS、HS+LPS组;HS+LPS+Dex组和HS+LPS+SM组IκBαmRNA表达低于HS、HS+LPS组。结论参麦注射液能够下调脾脏组织中TLR4mRNA表达,同时上调脾脏组织中IκBα的表达,提示参麦可能通过调节NF-κB信号转导途径抑制炎症反应来对机体细胞起保护作用。     

Inflammatory effects of coarse and fine particulate matter in relation to chemical and biological constituents

There is conflicting evidence in the literature as to the predominant mechanism and also the compositional element(s) that drives the pulmonary inflammatory response of ambient particulate matter (PM). We have investigated the inflammogenic potential of coarse (2.5-10 microm) and fine (<2.5 microm) PM from both a rural and an industrial location in Germany, using bronchoalveolar lavage (BAL) of rat lungs 18 h post intratracheal instillation with PM. Irrespective of the sampling location, the coarse fraction of PM(10) but not its fine counterpart caused neutrophilic inflammation in rat lungs, in the absence of any severe pulmonary toxicity as indicated by the lack of an increase in lavage protein and lactate dehydrogenase levels. The rural sample of coarse PM also caused a significant increase in the tumor necrosis factor alpha (TNFalpha) content as well as glutathione depletion in the BAL fluid. The contrasting inflammatory responses of the different samples could not be explained by differences in the concentrations of soluble Fe, Cu, V, Ni, Cr, or Al or by the.OH generating capacities of the PM suspensions. However, the effects of the different PM samples were clearly associated with their endotoxin content, as well as their ability to induce interleukin (IL)-8 and TNFalpha from whole blood in vitro. In conclusion, on an equal mass basis, coarse but not fine PM samples from our sampling campaign induced an inflammatory reaction in the lung in the absence of gross cellular lung damage, following intratracheal instillation. Our data also indicate, in accordance with previous independent in vitro observations, that endotoxin or related contaminants may play a role in these in vivo effects.     

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.     

Maternal exposure to bacterial endotoxin during pregnancy enhances amphetamine-induced locomotion and startle responses in adult rat offspring

An increased incidence of schizophrenia has been associated with several perinatal insults, most notably maternal infection during pregnancy and perinatal hypoxia. This study used a rat model to directly test if maternal exposure to bacterial endotoxin (lipopolysaccharide, LPS) during pregnancy alters behaviors relevant to schizophrenia, in offspring at adulthood. The study also tested if postnatal anoxia interacted with gestational LPS exposure to affect behavior. At adulthood, offspring from dams administered LPS on days 18 and 19 of pregnancy showed significantly increased amphetamine-induced locomotion, compared to offspring from saline-treated dams. A period of anoxia on postnatal day 7 had no effect on amphetamine-induced locomotion and there was no interaction between effects of gestational LPS and postnatal anoxia on this behavior. Offspring from LPS-treated dams also showed enhanced acoustic startle responses as adults, compared to offspring from saline-treated dams. In offspring tested for pre-pulse inhibition (PPI) of acoustic startle and for apomorphine modulation of PPI, no effects of either gestational LPS or of postnatal anoxia and no interactions between LPS and anoxia were observed. It is concluded that maternal LPS exposure during pregnancy in the rat may be a useful model to study mechanisms responsible for effects of maternal infection on behaviors relevant to schizophrenia, in offspring.     

Oxidant Stress in Hemodialysis Patients: What Are the Determining Factors?

Oxidant stress contributes to morbidity in hemodialysis patients. Three possible causes of oxidant stress have been suggested: the uremic state, the dialyzer membrane, and bacterial contaminants from the dialysate. Oxidant stress occurs in uremia before dialysis therapy is initiated, as evidenced by increased production of reactive oxygen species, increased levels of oxidized plasma proteins and lipids, and decreased antioxidant defenses. It has been proposed that increased production of reactive oxygen species during hemodialysis is also an important contributor to oxidant stress. Hemodialysis is associated with a transient increase in production of reactive oxygen species, particularly with cellulose membranes. In addition, surveys have shown widespread contamination of dialysate by endotoxin, which may cross membranes and prime production of reactive oxygen species by phagocytic cells. Recent studies, however, show a decrease in protein oxidation from pre- to post-dialysis and a normalization of neutrophil reactive oxygen species production. Taken together, these data suggest that uremia, per se, is the most important cause of oxidant stress in hemodialysis patients. Dialysate quality may also contribute to oxidant stress, but evidence that the dialyzer membrane plays a role is weak.