Rolf Bunger - Academia.edu (original) (raw)

Papers by Rolf Bunger

Anesthesiology, 2006

Background Skeletal muscle fibers from malignant hyperthermia (MH)-susceptible humans and swine a... more Background Skeletal muscle fibers from malignant hyperthermia (MH)-susceptible humans and swine are markedly more sensitive to ryanodine receptor (RyR1) agonists than those from normal individuals. Reproducible shifts in the dose-response of skeletal muscle to caffeine and halothane are the basis of the current in vitro diagnostic caffeine-halothane contracture test. In an attempt to develop a less invasive MH diagnostic test, the authors determined the effects of RyR1 agonists (caffeine, 4-chloro-m-cresol [4CmC], and halothane) on the adductor muscle with respect to the lactate-pyruvate (L/P) system that was percutaneously dialyzed using a microdialysis technique in homozygous MH-susceptible compared with normal swine. Methods Animals were anesthetized (ketamine-propofol) and artificially ventilated. Sets of six CMA/20 microdialysis catheters were implanted; each catheter was perfused with different RyR1 agonist concentrations. After a 30-min equilibration after implantation, one o...

European Journal of Anaesthesiology, 2008

The caffeine/halothane contracture test in North America and the in vitro contracture test in Eur... more The caffeine/halothane contracture test in North America and the in vitro contracture test in Europe are currently the only validated bioassays for diagnosing malignant hyperthermia susceptibility and phenotyping families. Both tests are invasive requiring surgical muscle biopsy. Here, we report first use of the selective ryanodine receptor type I agonist ryanodine in a percutaneous microdialysis protocol designed to test whether microdialysis-induced local metabolic responses of skeletal muscle due to ryanodine receptor activation can differentiate between malignant hyperthermia-sensitive and normal pigs. Six microdialysis catheters were implanted percutaneously into the adductor muscles of the right and left thighs of malignant hyperthermia-susceptible (n = 9) and normal (n = 8) anaesthetized (ketamine/propofol) and mechanically ventilated swine. Systemic blood gases, haemodynamic parameters and creatine kinase levels were measured before, during and after microdialysis perfusion of ryanodine. After a post-implantation equilibration period of 30 min, one catheter perfused (2 micro min-1) with 0.9% NaCl (control) and was compared with the remaining five catheters perfused with increasing concentrations of ryanodine (0.2-100 micromol). Lactate and pyruvate levels were measured enzymatically. Continuous perfusion with ryanodine revealed dose-dependent sigmoidal increases in the dialysate lactate and lactate-pyruvate ratio parameters; these effects were greatly augmented in malignant hyperthermia-susceptible pigs compared to normal pigs (two- to threefold): estimated EC50 greatly decreased (>19-fold) while the maximum effect increased (>twofold) in the malignant hyperthermia-susceptible group. The in vivo percutaneous microdialysis protocol for skeletal muscle, using ryanodine as the ryanodine receptor type I agonist and dialysed lactate-pyruvate parameters as metabolic index, can reproducibly differentiate between malignant hyperthermia-susceptible and normal swine.

Anesthesiology, 2010

Malignant hyperthermia susceptibility (MHS) is diagnosed by an invasive in vitro caffeine-halotha... more Malignant hyperthermia susceptibility (MHS) is diagnosed by an invasive in vitro caffeine-halothane contracture test (CHCT) carried out on biopsied skeletal muscle tissue. We are presenting a novel blood test approach for malignant hyperthermia testing in a swine model. Our main aim was to determine whether adenosine production from lymphocytes after 4-chloro-m-cresol (4CmC) stimulation distinguishes homozygous swine carrying the Arg615Cys mutation in the ryanodine receptor type 1 (RyR1) gene (MHS swine) from normal swine. Lymphocytes were isolated from arterial blood (40 ml) obtained from MHS (n = 7) and normal (n = 7) swine. Cells were suspended in Hank&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s balanced salt solution and treated with 4CmC (0-10 mm) at 37°C in the presence of adenosine deaminase inhibitor. After termination and purification of samples, aliquots (50 μl) were assayed for adenosine content using high performance liquid chromatography. Baseline adenosine levels before stimulating lymphocytes with 4CmC were 0.025 ± 0.004 and 0.041 ± 0.006 μm (mean ± SEM) in lymphocytes from normal and MHS swine, respectively (P = 0.125). Maximum responses were achieved at 1 mm 4CmC for both cell-line groups. Adenosine levels after stimulation with 4CmC (1 mm) were 0.185 ± 0.009 and 0.397 ± 0.038 μm in lymphocytes from normal and MHS swine, respectively (P = 0.0035). There was no overlap between adenosine levels in stimulated lymphocytes from MHS and normal swine. 4CmC stimulation of porcine lymphocytes induces increased adenosine formation in MHS cells relative to those from normal swine; evaluation of adenosine formation in response to RyR1 agonists in human lymphocytes is needed.

Molecular Immunology, 2007

Intravenous injection of some liposomal drugs, diagnostic agents, micelles and other lipid-based ... more Intravenous injection of some liposomal drugs, diagnostic agents, micelles and other lipid-based nanoparticles can cause acute hypersensitivity reactions (HSRs) in a high percentage (up to 45%) of patients, with hemodynamic, respiratory and cutaneous manifestations. The phenomenon can be explained with activation of the complement (C) system on the surface of lipid particles, leading to anaphylatoxin (C5a and C3a) liberation and subsequent release reactions of mast cells, basophils and possibly other inflammatory cells in blood. These reactions can be reproduced and studied in pigs, dogs and rats, animal models which differ from each other in sensitivity and spectrum of symptoms. In the most sensitive pig model, a few miligrams of liposome (phospholipid) can cause anaphylactoid shock, characterized by pulmonary hypertension, systemic hypotension, decreased cardiac output and major cardiac arrhythmias. Pigs also display cutaneous symptoms, such as flushing and rash. The sensitivity of dogs to hemodynamic changes is close to that of pigs, but unlike pigs, dogs also react to micellar lipids (such as Cremophor EL) and their response includes pronounced blood cell and vegetative neural changes (e.g., leukopenia followed by leukocytosis, thrombocytopenia, fluid excretions). Rats are relatively insensitive inasmuch as hypotension, their most prominent response to liposomes, is induced only by one or two orders of magnitude higher phospholipid doses (based on body weight) compared to the reactogenic dose in pigs and dogs. It is suggested that the porcine and dog models are applicable for measuring and predicting the (pseudo)allergic activity of particulate &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;nanodrugs&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;.

Anesthesia and analgesia, 1996

Previous systematic investigations of the hemostatic effects of normovolemic hemodilution (NHD) h... more Previous systematic investigations of the hemostatic effects of normovolemic hemodilution (NHD) have not explored the influence of hematocrits less than 20% in humans or animals. However, clinical interest in maximizing the perioperative conservation of erythrocytes may involve profound NHD beyond traditionally accepted empiric end points. We report here on coagulation data in eight healthy adolescent patients undergoing profound NHD in concert with surgical correction of idiopathic scoliosis, and in 29 swine undergoing experimental stepwise NHD until death. Blood was replaced with 5% albumin in 0.9% saline in our patients, and with 5% albumin in lactated Ringer's solution in our pigs. A 75% blood volume exchange in our patients yielded a platelet count (PLT) of 158 +/- 26 x 10(3)/microL, fibrinogen concentration (FIB), 50 +/- 7 mg/dL, prothrombin time (PT), 25.4 +/- 2.6 s, activated partial thromboplastin time (aPTT), 87 +/- 15s, and a nadir hemoglobin of 2.8 +/- 0.2 g/dL; howe...

International journal of pharmaceutics, 2007

Poly(amino acid)s (PAAs) were evaluated as coating polymers for long-circulating liposomes. The p... more Poly(amino acid)s (PAAs) were evaluated as coating polymers for long-circulating liposomes. The pharmacokinetics of PAA-coated liposomes were assessed in rats. Prolonged circulation times were obtained, comparable to those reported for poly(ethylene glycol) (PEG)-liposomes. Besides, the enzymatic degradability of PAAs was studied. PAAs - in free as well as liposome-associated form - are degradable by proteases, which is beneficial for reducing the risks of accumulation in vivo. Furthermore, complement activation by PAA-liposomes was evaluated in vitro and in vivo. Like other liposome types, they appear to activate the complement system. However, a role of endotoxin contamination of the PAA-liposome formulations used cannot be excluded in our complement activation studies.

American journal of physiology. Heart and circulatory physiology, 2001

Pyruvate (PYR) improves cellular and organ function hypoxia and ischemia by stabilizing the reduc... more Pyruvate (PYR) improves cellular and organ function hypoxia and ischemia by stabilizing the reduced nicotinamide adenine dinucleotide redox state and cytosolic ATP phosphorylation potential. In this in vivo study, we evaluated the effects of intravenous pyruvate on neocortical function, indexes of the cytosolic redox state, cellular energy state, and ischemia during a prolonged (4 h) controlled arterial hemorrhage (40 mmHg) in swine. Thirty minutes after the onset of hemorrhagic shock, sodium PYR (n = 8) was infused (0.5 g x kg(-1) x h(-1)) to attain arterial levels of 5 mM. The volume and osmotic effects were matched with 10% NaCl [hypertonic saline (HTS)] (n = 8) or 0.9% NaCl [normal saline (NS)] (n = 8). During the hemorrhage protocol, the time to peak hemorrhage volume was significantly delayed in the PYR group compared with the HTS and NS groups (94 +/- 5 vs. 73 +/- 6 and 72 +/- 4 min, P < 0.05). In addition to the early onset of the decompensatory phase of hemorrhagic shock...

Computational and Mathematical Methods in Medicine, 2014

Multivariate radiation injury estimation algorithms were formulated for estimating severe hematop... more Multivariate radiation injury estimation algorithms were formulated for estimating severe hematopoietic acute radiation syndrome (H-ARS) injury (i.e., response category three or RC3) in a rhesus monkey total-body irradiation (TBI) model. Classical CBC and serum chemistry blood parameters were examined prior to irradiation (d 0) and on d 7, 10, 14, 21, and 25 after irradiation involving 24 nonhuman primates (NHP) (Macaca mulatta) given 6.5-Gy (60)Co Υ-rays (0.4 Gy min(-1)) TBI. A correlation matrix was formulated with the RC3 severity level designated as the &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;dependent variable&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; and independent variables down selected based on their radioresponsiveness and relatively low multicollinearity using stepwise-linear regression analyses. Final candidate independent variables included CBC counts (absolute number of neutrophils, lymphocytes, and platelets) in formulating the &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;CBC&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; RC3 estimation algorithm. Additionally, the formulation of a diagnostic CBC and serum chemistry &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;CBC-SCHEM&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; RC3 algorithm expanded upon the CBC algorithm model with the addition of hematocrit and the serum enzyme levels of aspartate aminotransferase, creatine kinase, and lactate dehydrogenase. Both algorithms estimated RC3 with over 90% predictive power. Only the CBC-SCHEM RC3 algorithm, however, met the critical three assumptions of linear least squares demonstrating slightly greater precision for radiation injury estimation, but with significantly decreased prediction error indicating increased statistical robustness.

Methods in Enzymology, 2003

Activation of complement (C) by haptenized liposomes has been utilized for a long time to study t... more Activation of complement (C) by haptenized liposomes has been utilized for a long time to study the interaction of biological membranes with C proteins, or as a sensitive immunoassay for the measurement of specific antigens, antibodies, or serum hemolytic C levels. However, it has been increasingly recognized that regardless of antigenicity, C activation is an intrinsic property of all charged phospholipid/cholesterol bilayers. Liposome-induced C activation and its biological consequences show significant interspecies and interindividual variation, and critically depend on the properties of vesicles as well. Activation can proceed through both the classical and the alternative pathways, with or without the involvement of antibodies. The practical significance of the phenomenon is twofold: 1) opsonization of the vesicles promotes their clearance from the circulation and 2) the liberation of C3a and C5a can cause numerous, potentially adverse, biological reactions. In fact, many cardiovascular and hematological changes observed following administration of liposomes in vivo can be explained by C activation; a fact that has not yet gained wide recognition in the field of drug-carrier liposomes.

Liposome-induced pulmonary hypertension: properties and mechanism of a complementmediated pseudoa... more Liposome-induced pulmonary hypertension: properties and mechanism of a complementmediated pseudoallergic reaction. Am J Physiol Heart Circ Physiol 279: H1319-H1328, 2000.-Intravenous injection of liposomes can cause significant pulmonary hypertension in pigs, a vasoconstrictive response that provides a sensitive model for the cardiopulmonary distress in humans caused by some liposomal drugs. The reaction was recently shown to be a manifestation of "complement activation-related pseudoallergy" (CARPA; Szebeni J, Fontana JL, Wassef NM, Mongan PD, Morse DS, Dobbins DE, Stahl GL, Bü nger R, and Alving CR. Circulation 99: [2302][2303][2304][2305][2306][2307][2308][2309] 1999). In the present study we demonstrate that the composition, size, and administration method of liposomes have significant influence on pulmonary vasoactivity, which varied between instantaneously lethal (following bolus injection of 5 mg lipid) to nondetectable (despite infusion of a 2,000-fold higher dose). Experimental conditions augmenting the pulmonary hypertensive response included the presence of dimyristoyl phosphatidylglycerol, 71 mol% cholesterol, distearoyl phosphatidylcholine, and hemoglobin in liposomes, increased vesicle size and polydispersity, and bolus injection vs. slow infusion. The vasoactivity of large multilamellar liposomes was reproduced with human C3a, C5a, and xenoreactive immunoglobulins, and it correlated with the complement activating and natural antibody binding potential of vesicles. Unilamellar, monodisperse liposomes with 0.19 Ϯ 0.10 m mean diameter had no significant vasoactivity. These data indicate that liposome-induced pulmonary hypertension in pigs is multifactorial, it is due to natural antibody-triggered classic pathway complement activation and it can be prevented by appropriate tailoring of the structure and administration method of vesicles. hypersensitivity reactions; anaphylatoxin; hemoglobin; IgMenriched intravenous immunoglobulin; hemodynamics LIPOSOMAL FORMULATIONS of some drugs, most importantly doxorubicin (Doxil) and amphotericin B (Ambi-Address for reprint requests and other correspondence: J. Szebeni,

European Journal of Biochemistry, 1990

The quantitative importance of glycolysis in cardiomyocyte reenergization and contractile recover... more The quantitative importance of glycolysis in cardiomyocyte reenergization and contractile recovery was examined in postischemic, preload-controlled, isolated working guinea pig hearts. A 25-min global but low-flow ischemia with concurrent norepinephrine infusion to exhaust cellular glycogen stores was followed by a 15-min reperfusion. With 5 mM pyruvate as sole reperfusion substrate, severe contractile failure developed despite normal sarcolemmal pyruvate transport rate and high intracellular pyruvate concentrations near 2 mM. Reperfusion dysfunction was characterized by a low cytosolic phosphorylation potential ([ATP]/([ADP][P,]) due to accumulations of inorganic phosphate (Pi) and lactate. In contrast, with 5 mM glucose plus pyruvate as substrates, but not with glucose as sole substrate, reperfusion phosphorylation potential and function recovered to near normal. During the critical ischemia-reperfusion transition at 30 s reperfusion the cytosolic creatine kinase appeared displaced from equilibrium, regardless of the substrate supply. When under these conditions glucose and pyruvate were coinfused, glycolytic flux was near maximum, the glyceraldehyde-3-phosphate dehydrogenase13phosphoglycerate kinase reaction was enhanced, accumulation of Pi was attenuated, ATP content was slightly increased, and adenosine release was low. Thus, glucose prevented deterioration of the phosphorylation potential to levels incompatible with reperfusion recovery. Immediate energetic support due to maximum glycolytic ATP production and enhancement of the glyceraldehyde-3-phosphate dehydrogenase/3-phosphoglycerate kinase reaction appeared to act in concert to prevent detrimental collapse of [ATP]/([ADP][P,]) during creatine kinase dysfunction in the ischemia-reperfusion transition. Dichloroacetate (2 mM) plus glucose stimulated glycolysis but failed fully to reenergize the reperfused heart; conversely, 10 mM 2-deoxyglucose plus pyruvate inhibited glycolysis and produced virtually instantaneous de-energization during reperfusion. The following conclusions were reached. (1) A functional glycolysis is required to prevent energetic and contractile collapse of the low-flow ischemic or reperfused heart (2). Glucose stabilization of energetics in pyruvate-perfused hearts is due in part to intensification of glyceraldehyde-3-phosphate dehydrogenase/3-phosphoglycerate kinase activity.

European Journal of Biochemistry, 1989

Bioenergetic and hemodynamic consequences of cellular redox manipulations by 0.2 -20 mM pyruvate ... more Bioenergetic and hemodynamic consequences of cellular redox manipulations by 0.2 -20 mM pyruvate were compared with those due to adrenergic stress (0.7 -1.1 pM norepinephrine) using isolated working guinea-pig hearts under the conditions of normoxia, low-flow ischemia, and reperfusion. 5 mM glucose (+ 5 U/l insulin) + 5 mM lactate were the basal energy-yielding substrates. To stabilize left ventricular enddiastolic pressure, ventricular filling pressure was held at 12 cmHzO under all conditions; this preload control minimized Frank-Starling effects on ventricular inotropism. Global low-flow ischemia was induced by reducing aortic pressure to levels (20 -10 cmH20) below the coronary autoregulatory reserve. Reactants of the creatine kinase, including H + and other key metabolites, were measured by enzymatic, HPLC, and polarographic techniques.

Military Medicine, 2011

Our purpose was to demonstrate the consistency of radiologists&amp;amp;amp;amp;amp;amp;am... more Our purpose was to demonstrate the consistency of radiologists&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; three-dimensional measurements of simulated blast fragment locations in vitro in an effort to objectively localize retained fragments and wound paths. We designed a phantom consisting of 10 nail heads (simulating blast fragments) glued to wooden pegs that were randomly situated at distances from a reference point within a plastic tub. The x, y, and z coordinates of simulated fragments were recorded in Cartesian 3-space relative to the reference point. Computed tomography images of the phantom were acquired. Differences in x, y, and z positions as determined by three observers were summed for each fragment. Agreement between recordings of coordinates across readers was assessed using the intraclass correlation coefficient. Summed differences in coordinate positions as determined by readers ranged between 0.00 and 1.204 cm (mean: 0.732 cm). Across readers, the intraclass correlation coefficient for each dimension was &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;0.99. We found excellent agreement among readers with minimal discrepancy of measured locations of simulated fragments. Our results provide a foundation for trajectory analysis necessary to lead to automated organ damage reporting for immediate assessment in the emergency department and for forensic investigation and long-term epidemiological analysis.

Military Medicine, 2012

Penetrating trauma is frequently encountered in forward deployed military combat hospitals. Abdom... more Penetrating trauma is frequently encountered in forward deployed military combat hospitals. Abdominal blast injuries represent nearly 11% of combat injuries, and multiplanar computed tomography imaging is optimal for injury assessment and surgical planning. We describe a multiplanar approach to assessment of blast and ballistic injuries, which allows for more expeditious detection of missile tracts and damage caused along the path. Precise delineation of the trajectory path and localization of retained fragments enables time-saving and detailed evaluation of associated tissue and vascular injury. For consistent and reproducible documentation of fragment locations in the body, we propose a localization scheme based on Cartesian coordinates to report 3-dimensional locations of fragments and demonstrating the application in three cases of abdominal blast injury.

Journal of Liposome Research, 2002

Pegylated liposomal doxorubicin (Doxil) and 99mTc-HYNIC PEG liposomes (HPL) were reported earlier... more Pegylated liposomal doxorubicin (Doxil) and 99mTc-HYNIC PEG liposomes (HPL) were reported earlier to cause hypersensitivity reactions (HSRs) in a substantial percentage of patients treated i.v. with these formulations. Here we report that (1) Doxil, HPL, pegylated phosphatidylethanolamine (PEG-PE)-containing empty liposomes matched with Doxil and HPL in size and lipid composition, and phosphatidylglycerol (PG)-containing negatively charged vesicles were potent C activators in human serum in vitro, whereas small neutral liposomes caused no C activation. (2) Doxil and other size-matched PEG-PE and/or PG-containing liposomes also caused massive cardiopulmonary distress with anaphylactoid shock in pigs via C activation, whereas equivalent neutral liposomes caused no hemodynamic changes. (3) A clinical study showed more frequent and greater C activation in patients displaying HSR than in non-reactive patients. These data suggest that liposome-induced HSRs in susceptible individuals may be due to C activation, which, in turn, is due to the presence of negatively charged PEG-PE in these vesicles.

Journal of Liposome Research, 2000

Page 1. JOURNAL OF LIPOSOME RESEARCH, 10(4), 467-481 (2000) THE ROLE OF COMPLEMENT ACTIVATION IN ... more Page 1. JOURNAL OF LIPOSOME RESEARCH, 10(4), 467-481 (2000) THE ROLE OF COMPLEMENT ACTIVATION IN HYPERSENSITIVITY TO PEGYLATED LIPOSOMAL DOXORUBICIN (DOXIL@) Janos Szebeni,B* Lajos ...

Journal of Liposome Research, 2007

Journal of Digital Imaging, 2007

The authors present a unique medical technical application for illustrating the success and/or fa... more The authors present a unique medical technical application for illustrating the success and/or failure of the physiological healing process as a dynamically morphed video. Two examples used in this report include the healing of a severely fractured humerus from an explosion in Iraq and the other of dramatic tissue destruction from a poisonous spider bite. For the humerus, several sequential x-rays obtained throughout orthopedic surgical procedures and the healing process were morphed together representing a time-lapsed video of the healing process. The end result is a video that demonstrates the healing process in an animation that radiologists envision and report to other clinicians. For the brown recluse spider bite, a seemingly benign skin lesion transforms into a wide gaping necrotic wound with dramatic appearance within days. This novel technique is not presented for readily apparent clinical advantage, rather, it may have more immediate application in providing treatment options to referring providers and/or patients, as well as educational value of healing or disease progression over time. Image morphing is one of those innovations that is just starting to come into its own. Morphing is an image processing technology that transforms one image into another by generating a series of intermediate synthetic images. It is the same process that Hollywood uses to turn people into animals in movies, for example. The ability to perform morphing, once restricted to high-end graphics workstations, is now widely available for desktop computers. The authors describe how a series of radiographic images were morphed into a short movie clip using readily available software and an average laptop. The resultant video showed the healing process of an open comminuted humerus fracture that helped demonstrate how amazingly the human body heals in a case presentation in a time-lapse fashion.

Circulation, 1999

Background-Intravenous administration of some liposomal drugs can trigger immediate hypersensitiv... more Background-Intravenous administration of some liposomal drugs can trigger immediate hypersensitivity reactions that include symptoms of cardiopulmonary distress. The mechanism underlying the cardiovascular changes has not been clarified. Methods and Results-Anesthetized pigs (nϭ18) were injected intravenously with 5-mg boluses of large multilamellar liposomes, and the ensuing hemodynamic, hematologic, and laboratory changes were recorded. The significant (PϽ0.01) alterations included 79Ϯ9% (meanϮSEM) rise in pulmonary arterial pressure, 30Ϯ7% decline in cardiac output, 11Ϯ2% increase in heart rate, 236Ϯ54% increase in pulmonary vascular resistance, 71Ϯ27% increase in systemic vascular resistance, and up to a 100-fold increase in plasma thromboxane B 2 . These changes peaked between 1 and 5 minutes after injection, subsided within 10 to 20 minutes, were lipid dose-dependent (ED 50 ϭ4.5Ϯ1.4 mg), and were quantitatively reproducible in the same animal several times over 7 hours. The liposome-induced rises of pulmonary arterial pressure showed close quantitative and temporal correlation with elevations of plasma thromboxane B 2 and were inhibited by an anti-C5a monoclonal antibody (GS1), by sCR1, or by indomethacin. Liposomes caused C5a production in pig serum in vitro through classic pathway activation and bound IgG and IgM natural antibodies. Zymosan-and hemoglobin-containing liposomes and empty liposomes caused essentially identical pulmonary changes. Conclusions-The intense, nontachyphylactic, highly reproducible, complement-mediated pulmonary hypertensive effect of minute amounts of intravenous liposomes in pigs represents a unique, unexplored phenomenon in circulation physiology. The model provides highly sensitive detection and study of cardiopulmonary side effects of liposomal drugs and many other pharmaceutical products due to "complement activation-related pseudoallergy" (CARPA).

Journal of Cerebral Blood Flow & Metabolism, 2005