Biomedical subjects

S Zahler

Publications and source records attributed to S Zahler.

At least 19 recordsLinked to original sources

PubMed2001

Modified phosphatidylethanolamine as the active component of oxidized low density lipoprotein promoting platelet prothrombinase activity.

We analyzed the influence of the atherogenic oxidized low density lipoproteins (LDL) on the activity of the platelet prothrombinase complex, a major contributor to overall thrombin formation in vivo. Platelet dependent thrombin generation was found to be strongly stimulated by in vitro oxidized LDL. The enhancement was additive to that observed with the platelet agonist thrombin. Oxidized LDL increased the platelet binding of annexin-V, suggesting that the augmented surface exposure of aminophospholipids promoted the prothrombinase activity. All of the stimulatory activity of the oxidized LDL could be recovered in the microemulsions prepared from the lipid portion of the modified particles. Phospholipid vesicles were prepared containing the total lipids of the oxidized LDL but lacking specifically in one lipid component. Following the selective removal of the ethanolamine phospholipids (PE) from the LDL lipids, the platelet-dependent thrombin formation was markedly reduced. Vesicles enriched with the isolated PE fraction alone enhanced the thrombin generation. Analyses with autoxidized phospholipids indicated that oxidation products of unsaturated diacyl-PE were mainly responsible for the increased prothrombinase activity. Oxidized LDL and its PE fraction lost their stimulatory activity after treatment with NaCNBH(3), a chemical reductant of Schiff base adducts. Phospholipid vesicles supplemented with synthetic aldehyde-PE adducts largely reproduced the stimulation of the thrombin generation. We conclude that the oxidized LDL particles elicit a pronounced prothrombotic response by increasing the activity of the platelet prothrombinase complex. Specific oxidative modifications of the LDL-associated ethanolamine phospholipids are mainly responsible for this stimulation.

Blood Platelets↗

PubMed2001

Platelet-associated tissue factor contributes to the collagen-triggered activation of blood coagulation.

The extravascular localization of tissue factor (TF), the central initiator of coagulation, is thought to ensure that thrombus formation is prevented in the intact vessel. We observed that during a 5-min stimulation of human blood with collagen (type I), TF antigen appeared on the surface of platelets adhering to leukocytes. The rapidly presented intravascular TF was competent to start the coagulation cascade. The isolated platelets from healthy donors contained appreciable amounts of the TF protein, while no TF antigen was detected in the neutrophils and rapidly isolated monocytes. Direct interactions with the neutrophils and monocytes were apparently necessary to activate the platelet-associated TF. This was most likely mediated by inactivation of tissue factor pathway inhibitor through leukocyte elastase. In summary, the leukocyte-elicited activation of the platelet TF participates in the rapid initiation of coagulation by collagen.

Adult↗

PubMed2001

Evidence for inflammatory responses of the lungs during coronary artery bypass grafting with cardiopulmonary bypass.

OBJECTIVE: The occurrence of a systemic inflammatory reaction during cardiac surgery with cardiopulmonary bypass (CPB) has been well established, and the heart itself has been shown to release inflammatory mediators after ischemia. The hypothesis of the present study was that the lungs are also a site of inflammatory responses during early reperfusion. METHODS: In 20 consecutive patients undergoing coronary artery bypass grafting, blood was simultaneously drawn from the right atrium (RA) and the pulmonary vein (PV) before CPB and at 1 min, 10 min, and 20 min of reperfusion. The levels of interleukin (IL)-6, IL-8, IL-10, and tumor necrosis factor (TNF)-alpha were determined, as well as the adhesion molecules CD41 and CD62 on platelets and CD11b and CD41 on leukocytes. As a measure of the pulmonary release, ratios of PV and RA levels were calculated. RESULTS: Before CPB, the concentrations of cytokines tended to be lower in the PV compared with the RA. At 1 min of reperfusion, no significant concentration increases were found in the PV. At 10 min of reperfusion, the PV/RA ratio (mean +/- SEM) for IL-6 was 2.06 +/- 0.37 and 1.24 +/- 0.15 for IL-8 (p = 0.02 and p = 0.04, respectively, compared with the pre-CPB ratios of 0.89 +/- 0.4 and 0.99 +/- 0.2). At 20 min of reperfusion, PV/RA ratios for IL-6 (1.95 +/- 0.37) and IL-10 (0.99 +/- 0.4) were higher than before CPB (0.89 +/- 0.04, p = 0.05 and 0.85 +/- 0.06, p = 0.03, respectively). Adhesion molecule counts on platelets and polymorphonuclear neutrophils (PMNs) tended to be higher in the PV than in the RA before CPB. At 1 min of reperfusion, the PV/RA ratio of CD41 on monocytes (0.89 +/- 0.04) and of CD41 on PMNs (1.05 +/- 0.05) was less than before CPB (1.24 +/- 0.08, p = 0.0002 and 1.55 +/- 0.14, p = 0.0002). At 10 min and 20 min of reperfusion, similar changes were found. CONCLUSIONS: The observed changes indicate an inflammatory response of the lungs. Proinflammatory cytokines are increased in pulmonary venous blood. At the same time, activated blood cells are retained in the pulmonary circulation. This may contribute to pulmonary dysfunction almost routinely observed after CPB.

Aged↗

PubMed2000

Endothelial function and hemostasis.

The vascular endothelium influences not only the three classically interacting components of hemostasis: the vessel, the blood platelets and the clotting and fibrinolytic systems of plasma, but also the natural sequelae: inflammation and tissue repair. Two principal modes of endothelial behaviour may be differentiated, best defined as an anti- and a prothrombotic state. Under physiological conditions endothelium mediates vascular dilatation (formation of NO, PGI2, adenosine, hyperpolarizing factor), prevents platelet adhesion and activation (production of adenosine, NO and PGI2, removal of ADP), blocks thrombin formation (tissue factor pathway inhibitor, activation of protein C via thrombomodulin, activation of antithrombin III) and mitigates fibrin deposition (t- and scuplasminogen activator production). Adhesion and transmigration of inflammatory leukocytes are attenuated, e.g. by NO and IL-10, and oxygen radicals are efficiently scavenged (urate, NO, glutathione, SOD). When the endothelium is physically disrupted or functionally perturbed by postischemic reperfusion, acute and chronic inflammation, atherosclerosis, diabetes and chronic arterial hypertension, then completely opposing actions pertain. This prothrombotic, proinflammatory state is characterised by vaso-constriction, platelet and leukocyte activation and adhesion (externalization, expression and upregulation of von Willebrand factor, platelet activating factor, P-selectin, ICAM-1, IL-8, MCP-1, TNF alpha, etc.), promotion of thrombin formation, coagulation and fibrin deposition at the vascular wall (expression of tissue factor, PAI-1, phosphatidyl serine, etc.) and, in platelet-leukocyte coaggregates, additional inflammatory interactions via attachment of platelet CD40-ligand to endothelial, monocyte and B-cell CD40. Since thrombin formation and inflammatory stimulation set the stage for later tissue repair, complete abolition of such endothelial responses cannot be the goal of clinical interventions aimed at limiting procoagulatory, prothrombotic actions of a dysfunctional vascular endothelium.

Arteriosclerosis↗

PubMed2000

Reactive oxygen species and nitric oxide in myocardial ischemia and reperfusion.

Oxygen radicals and reactive oxygen species (ROS) are known to be generated in large amounts under inflammatory conditions and in the first few minutes of postischemic organ reperfusion. Due to the interaction of ROS with nitric oxide (NO), formed constitutively by endothelial cells, two alternatives are feasible. On the one hand, reaction with superoxide radicals may induce toxification (formation of peroxynitrite), and, on the other hand, by reacting with superoxide and hydroxyl radicals, NO can serve as a radical scavenger (formation of the innocuous anions, nitrate and nitrite, respectively). However, NO is considered to play a pivotal role in numerous physiological and pathophysiological processes, with effects arising from both lack and surfeit of this easily diffusible and chemically very reactive molecule. Physiologic contributions to vascular dilatation and inhibition of platelet and leukocyte activation, e.g., are infringed by enhanced inactivation of NO. Such inactivation occurs readily due to spontaneous reaction of NO with the superoxide radical, formed, e.g., by stressed endothelial cells and activated leukocytes. Conversely, overproduction of NO by induced NO synthase (iNOS) may lead to circulatory shock, cell apoptosis or even cell necrosis. Caution would, thus, seem to be warranted when attempting to interfere with homeostasis of NO. We have investigated the ability of NO to act as a radical scavenger during myocardial reperfusion in experimental and clinical settings. In the former, inhibition of angiotensin converting enzyme was employed to generate more endogenous NO (via bradykinin), in the latter, low-dose sodium nitroprusside was used as the donor of exogenous NO in patients undergoing coronary bypass grafting. Inhibition of leukocyte adhesion, attenuation of platelet activation and mitigation of redox-stress and inflammation were observed in both instances. Accordingly, modest enhancement of NO levels should afford cardioprotection during reperfusion.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2000

Sodium nitroprusside in patients with compromised left ventricular function undergoing coronary bypass: reduction of cardiac proinflammatory substances.

OBJECTIVE: The aim of the present study was to investigate whether the nitric oxide donor sodium nitroprusside can reduce the cardiac inflammatory response during coronary artery bypass grafting in patients with severely compromised left ventricular function. METHODS: Patients (n = 30) were assigned to receive placebo or sodium nitroprusside (0.5 microg. kg(-1). min(-1)) for the first 60 minutes of reperfusion. Interleukin 6, interleukin 8, and tumor necrosis factor alpha levels; platelet adhesion molecule CD41 and CD62 levels; and CD11b on leukocytes were determined in the radial artery and coronary sinus before cardiopulmonary bypass and during reperfusion (1, 5, 10, 35, and 75 minutes). RESULTS: At 1 minute of reperfusion, coronary venous levels of CD41-positive polymorphonuclear leukocytes were 8% lower than arterial levels in the placebo group and 18% higher in the sodium nitroprusside group (P =.021). At 5 minutes of reperfusion, the respective levels were 29% and 1% for interleukin 6 (P =.015), -5% and 20% for CD41-positive monocytes (P =.032), and -2% and 16% for CD11b-positive monocytes (P =.038). At 10 minutes of reperfusion, these levels were -14% and 21% for CD41-positive monocytes (P =.006). At 35 minutes of reperfusion, these levels were -13% and 7% for CD41-positive monocytes (P =.017), -41% and 23% for CD11b-positive monocytes (P =.001), and 7% and 25% for CD62-positive platelets (P =. 041). At 75 minutes of reperfusion, the levels were 15% and -7% for tumor necrosis factor alpha (P =.025) and -10% and 10% for CD62-positive platelets (P =.041). CONCLUSIONS: Transcardiac production of proinflammatory cytokines is reduced in patients undergoing coronary artery bypass grafting treated with the nitric oxide donor sodium nitroprusside. At the same time, less activated leukocytes and platelets are retained in the coronary circulation.

Aged↗

PubMed2000

Reduction of pro-inflammatory cytokine levels and cellular adhesion in CABG procedures with separated pulmonary and systemic extracorporeal circulation without an oxygenator.

OBJECTIVE: We have recently shown that a considerable amount of pro-inflammatory cytokines is released during pulmonary passage after aortic declamping in patients undergoing coronary artery bypass grafting. The present study was performed to investigate whether bilateral extracorporeal circulation with the lungs as oxygenators can reduce the inflammatory responses of the lungs. METHODS: Eighteen consecutive patients undergoing coronary artery bypass grafting were randomly assigned to routine extracorporeal circulation with cannulation of right atrium and aorta (routine circulation, ten patients) or to a bilateral extracorporeal circulation with additional cannulation of left atrium and pulmonary artery (bilateral circulation, eight patients). Blood was simultaneously drawn from right atrium and pulmonary vein at 1, 10 and 20 min reperfusion. The levels of interleukin (IL)-6 and IL-8 and the adhesion molecules CD41 and CD62 on platelets and CD11b and CD41 on leukocytes were determined. Because of considerable interindividual scatter, the pulmonary venous levels are normalized to percent of the respective right atrial value at each time point. RESULTS: At 1 min reperfusion pulmonary venous levels of IL-6 and IL-8 in routine circulation were +44+/-15% and +43+/-28% of the respective right atrial values. The respective values in bilateral circulation were -3+/-4% and -6+/-7% (P=0.02 and P=0.05 vs. respective right atrium). Similar increments were found after 10 and 20 min. Platelet-monocyte coaggregates were retained during pulmonary passage at 1 min reperfusion in routine circulation (-21+/-6%), but washed out in bilateral circulation (+5+/-8%, P=0. 007). At 20 min reperfusion, activated polymorphonuclear neutrophils (PMN) were retained in routine circulation (-16+/-9%) but washed out in bilateral circulation (+19+/-29%, P=0.05; all data given as mean+/-SEM). CONCLUSIONS: Bilateral extracorporeal circulation without an artificial oxygenator significantly reduces the inflammatory responses during pulmonary passage after aortic declamping.

Aged↗

PubMed2000

Endothelial preconditioning by transient oxidative stress reduces inflammatory responses of cultured endothelial cells to TNF-alpha.

Brief episodes of ischemia can render an organ resistant to subsequent severe ischemia. This 'ischemic preconditioning' is ascribed to various mechanisms, including oxidative stress. We investigated whether preconditioning exists on an endothelial level. Human umbilical vein endothelial cells (HUVECs) were transiently confronted with oxidative stress (1 mM H(2)O(2), 5 min). Adhesion molecules ICAM-1 and E-selectin and release of cytokines IL-6 and IL-8 to subsequent stimulation with TNF-alpha (2.5 ng/ml, 4 h) were measured (flow cytometry and immunoassay), as were nuclear translocation of the transcription factor NFkappaB (Western blotting, confocal microscopy) and redox status of HUVECs (quantification of glutathione by HPLC). TNF-alpha elevated IL-6 in the cell supernatant from 8.8 +/- 1 to 41 +/- 3 pg/ml and IL-8 from 0.5 +/- 0. 03 to 3 +/- 0.2 ng/ml. ICAM-1 was increased threefold and E-selectin rose eightfold. Oxidative stress (decrease of glutathione by 50%) reduced post-TNF-alpha levels of IL-6 to 14 +/- 3 and IL-8 to 1 +/- 0.2; the rise of ICAM-1 was completely blocked and E-selectin was only doubled. The anti-inflammatory effects of preconditioning via oxidative stress were paralleled by reduction of the translocation of NFkappaB on stimulation with TNF-alpha, and antagonized by the intracellular radical scavenger N-acetylcysteine. 'Anti-inflammatory preconditioning' of endothelial cells by oxidative stress may account for the inhibitory effects of preconditioning on leukocyte adhesion in vivo.

Apoptosis↗

PubMed2000

Nonuniform behavior of intravenous anesthetics on postischemic adhesion of neutrophils in the guinea pig heart.

UNLABELLED: Adhesion of polymorphonuclear neutrophils (PMN) to the coronary endothelium is a crucial step in the development of ischemic myocardial injury. We tested the possible effects of six widely used IV anesthetics on non- and postischemic coronary adhesion of PMN in isolated perfused guinea pig hearts. Hearts (n = 5-11/group) were perfused under conditions of constant coronary flow. After 15 min global warm ischemia, PMN (10(6)) were infused in the second minute of reperfusion. The number of cells reemerging in the coronary effluent within 2 min was expressed as a percentage of the total number of administered PMN. Anesthetics were given 20 min before ischemia and during reperfusion. In addition, the ability of the drugs to influence the oxidative burst reaction of PMN was assessed by measuring luminol-enhanced chemiluminescence in response to 0.1 microM N-formyl-L-methionyl-L-leucyl-L-phenylalanine. Under nonischemic conditions, 26.3% +/- 0.5% of the injected PMN did not acutely reemerge from the coronary system. Subjecting the hearts to ischemia augmented retention to 40.0% +/- 1.6% (P < 0.05). This postischemic stimulation of adhesion was fully prevented by ketamine (10 microM: 22.8% +/- 1.6%, 20 microM: 26.6% +/- 0.7%), thiopental (25 microM: 24.0% +/- 1.7%, 50 microM: 24.0% +/- 1.4%), and midazolam (1.5 microM: 29.0% +/- 0.9%, 3 microM: 26.4% +/- 1.4%). Propofol also inhibited the augmented postischemic retention at 25 microM (28.7% +/- 2.4%). However, 50 microM propofol, etomidate (0.5 and 1 microM), and fentanyl (1 microM) all had no effect. Only thiopental reduced the nonischemic adhesion value (14.0% +/- 3.7%). This may be linked to the direct antioxidative action of thiopental (50% reduction in oxidative burst activity). Whereas ketamine, midazolam, and propofol did not significantly influence oxidant production by PMN, etomidate and the lipid solvent Intralipid enhanced the burst reaction. This activating effect of the lipid component could explain the biphasic behavior of propofol emulsion. Despite some possible differences in efficacy, several IV anesthetics may protect the heart from PMN-mediated reperfusion injury. IMPLICATIONS: Ketamine, thiopental, and midazolam, but not etomodate or fentanyl, reduce postischemic adhesion of neutrophils in the coronary system of isolated perfused guinea pig hearts, suggesting a role in mitigating myocardial reperfusion injury.

Anesthetics, Intravenous↗

PubMed1999

ACE-inhibition attenuates cardiac cell damage and preserves release of NO in the postischemic heart.

Cardioprotective effects of angiotensin-converting enzyme (ACE) inhibition have been demonstrated in postischemic reperfusion. This occurred via bradykinin and indirect evidence suggested mediation by nitric oxide (NO), which probably acts as a radical scavenger. To test this hypothesis, we measured release of lactate dehydrogenase (LDH) from isolated guinea pig hearts (constant flow perfusion, 37 degrees C) as a marker of cellular damage, before and after global ischemia (15 min), and we investigated the release of NO during reperfusion, both, without and with ACE inhibition. The main catabolites of NO, nitrate and nitrite, were also quantified. Coronary perfusion pressure (CPP) indicated coronary resistance changes. Cilazaprilat (CIL, 10 microM) was used for inhibition of ACE. Marked and protracted cellular damage occurred during reperfusion in the control group, myocardial LDH release rising nearly 10-fold from 1.5 mU/ml (basal level) to 14 mU/ml during acute reperfusion, then declining to 7 mU/ml after 5 min. ACE inhibition mitigated the acute rise of LDH (9 mU/ml), and reduced its release to preischemic values already after 3 min of reperfusion. Postischemic NO release in the 2nd min of reperfusion was about 40% of the preischemic value (approx. 200 nM) in untreated hearts, while there was 70% recovery after ACE inhibition. After 25 min, NO had recovered to 69% in controls vs. 100% with CIL. Coronary venous nitrate + nitrite was not infringed during early reperfusion (2nd min). After 25 min, nitrate + nitrite had decreased in controls (about 75% of preischemic values), but increased to 110% with CIL. In control hearts, CPP rose continuously from the 10th to the 25th min of reperfusion (from 39 to 55 mmHg), indicating progressive vasoconstriction. CIL significantly attenuated this effect. The results suggest that NO might be consumed during early reperfusion in the act of detoxifying radicals. In control hearts, "endothelial stunning" takes place. Concerning NO production and vasodilatory tone, ACE-inhibition augments postischemic NO release and mitigates disturbances caused by ischemia and reperfusion.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1999

Significant leukocyte and platelet retention during pulmonary passage after declamping of the aorta in CABG patients.

During reperfusion of the heart and the lungs in patients undergoing coronary artery bypass grafting, these organs have been shown to release inflammatory mediators. The present study was performed to quantitatively determine cellular retention or washout during pulmonary passage in early reperfusion. In 14 consecutive patients undergoing coronary artery bypass grafting blood was simultaneously drawn from right atrium and pulmonary vein at 1, 10 and 20 min reperfusion. The counts for platelets, leukocytes and the leukocyte subsets polymorphonuclear neutrophils (PMN), lymphocytes and monocytes were determined. Pulmonary veno-right atrial (transpulmonary) differences are given in percent with respective right atrial values being considered as 100%. Before CPB leukocyte counts were 4.7 +/- 0.5 in right atrium and 4.2 +/- 0.4 in pulmonary vein, x10(9)/l, resp. (transpulmonary difference of -8 +/- 3%). During reperfusion, pulmonary retention was in the range of 20-23% (p <0.01 vs. right atrial value). The basal values for PMN were 2.4 +/- 0.3 in right atrium and 1.9 +/- 0.3 in pulmonary vein, x10(9)/l, resp. (transpulmonary difference -15 +/- 8%). Thereafter, retention was in the range of 25-30% (p <0.01 vs. right atrium). Basal values for lymphocytes were 1.5 +/- 0.2 in right atrium and 1.6+/-0.3 in pulmonary vein, x10(9)/l, resp. (transpulmonary difference +6 +/- 10%). A tendency towards a washout of lymphocytes at 1 min reperfusion (+1 +/- 12%) was followed by retention of these cells at 10 and 20 min reperfusion (-14 +/- 12% and -10 +/- 5%, p <0.05 vs right atrium). Before ischemia monocyte counts were 0.7 +/- 0.2 in right atrium and 0.6 +/- 0.2 in pulmonary vein, x10(9)/l, resp. (transpulmonary difference -10 +/- 4%) and -9 +/- 9%, -27 +/- 12% (p <0.05 vs right atrium) and -22 +/- 14% at 1, 10 and 20 min reperfusion. During early reperfusion of the lungs after declamping of the aorta, significant amounts of leukocytes, platelets and the leukocyte subsets are retained in the pulmonary vascular bed. These retained cells may be responsible for the previously described pulmonary release of cytokines.

Aged↗

PubMed1999

Tumor necrosis factor-alpha contributes to ischemia- and reperfusion-induced endothelial activation in isolated hearts.

-During myocardial reperfusion, polymorphonuclear neutrophil (PMN) adhesion involving the intercellular adhesion molecule-1 (ICAM-1) may lead to aggravation and prolongation of reperfusion injury. We studied the role of early tumor necrosis factor-alpha (TNF-alpha) cleavage and nuclear factor-kappaB (NF-kappaB) activation on ICAM-1 expression and venular adhesion of PMN in isolated hearts after ischemia (15 minutes) and reperfusion (30 to 480 minutes). NF-kappaB activation (electromobility shift assay) was found after 30 minutes of reperfusion and up to 240 minutes. ICAM-1 mRNA, assessed by Northern blot, increased during the same interval. Functional effect of newly synthesized adhesion molecules was found by quantification (in situ fluorescence microscopy) of PMN, given as bolus after ischemia, which became adherent to small coronary venules (10 to 50 microm in diameter). After 480 minutes of reperfusion, ICAM-1-dependent PMN adhesion increased 2.5-fold compared with PMN adhesion obtained during acute reperfusion. To study the influence of NF-kappaB on PMN adhesion, we inhibited NF-kappaB activation by transfection of NF-kappaB decoy oligonucleotides into isolated hearts using HJV-liposomes. Decoy NF-kappaB but not control oligonucleotides blocked ICAM-1 upregulation and inhibited the subacute increase in PMN adhesion. Similar effects were obtained using BB 1101 (10 microg), an inhibitor of TNF-alpha cleavage enzyme. These data suggest that ischemia and reperfusion in isolated hearts cause liberation of TNF-alpha, activation of NF-kappaB, and upregulation of ICAM-1, an adhesion molecule involved in inflammatory response after ischemia and reperfusion.

Animals↗

PubMed1999

Selectins and beta 2-integrins mediate post-ischaemic venular adhesion of polymorphonuclear leukocytes, but not capillary plugging, in isolated hearts.

Leukocytes adhering to venular endothelium and emigrating into the tissue contribute to myocardial reperfusion injury. The aim of the present study was to characterize the contribution of two different families of adhesion molecules, selectins and integrins, to post-ischaemic capillary plugging and venular adhesion of leukocytes in an isolated heart model. Guinea-pig hearts were perfused using the Langendorff technique. After 20 min stabilization global ischaemia was induced for 15 min at 37 degrees C. With the onset of reperfusion 10(7) isolated polymorphonuclear leukocytes (PMN), prelabelled with rhodamine 6G, were infused within 1 min. Perfusion was continued for 2 min to wash out all cells not firmly adhering to the vascular endothelium. Hearts were then arrested, mounted on a microscope stage and perfused with a cardioplegic solution containing 0.01% fluorescein isothiocyanate (FITC)-dextran (MW 150,000). In situ videofluorescence microscopy was used to quantify PMN plugging and adherent PMN. Four groups were studied: control (no treatment or ischaemia, n = 6); ischaemia (no treatment and 15 min ischaemia, n = 5); fucoidin (pretreatment of hearts and PMN with 0.3 mg/ml selectin inhibitor fucoidin and 15 min ischaemia, n = 5) and CD18 (pretreatment of PMN with 0.1 mg monoclonal antibody against CD18 and 15 min ischaemia, n = 5). Capillary plugging by PMN was 25 +/- 5 PMN/mm2 epicardial surface area and increased moderately to 55 +/- 6 PMN/mm2 in reperfused hearts. This increase was not affected by fucoidin or CD18 antibody. In contrast, post-ischaemic adhesion of PMN in small venules increased ninefold from 21 +/- 5 to 196 +/- 23 PMN/mm2 endothelial surface area. The increase in PMN adhesion to venular endothelium was blocked completely by pretreatment with fucoidin (19 +/- 5 PMN/mm-2) or CD18 antibody (7 +/- 2 PMN/mm-2). We conclude that selectin interaction alone is not sufficient to account for post-ischaemic PMN adhesion in the small venules of the coronary vasculature, because blocking the integrin subunit CD18 also inhibited PMN adhesion completely. On the other hand, neither integrins nor selectins seem to be involved in post-ischaemic capillary plugging by PMN in our perfused heart model.

Animals↗

PubMed1999

Sodium nitroprusside during coronary artery bypass grafting: evidence for an antiinflammatory action.

BACKGROUND: It was the aim of the present study to investigate whether a nitric oxide donor can reduce systemic inflammation and the cardiac inflammatory response during coronary artery bypass grafting with cardiopulmonary bypass. METHODS: Patients undergoing elective coronary artery bypass grafting (n = 22) were randomly assigned to treatment with either sodium nitroprusside (0.5 microg x kg(-1) x min(-1)) or placebo (controls), both for the first 20 minutes of reperfusion. Interleukin-6 and interleukin-8 levels, the adhesion molecules CD41 and CD62 on platelets and CD41 on monocytes and PMN (as markers for coaggregate formation), CD11b on monocytes and PMN, as well as platelet and leukocyte counts were determined in radial artery and coronary sinus blood before cardiopulmonary bypass and during reperfusion (1, 5, 10, 25, and 35 minutes). RESULTS: A reduction of systemic interleukin-6 levels (15.4+/-3.5 pg/mL, 36.7+/-5.9 pg/mL, and 46.8+/-8.0 pg/mL versus 33.4+/-7.7 pg/mL, 76.7+/-13.2 pg/mL, and 106.0+/-26.5 pg/mL, respectively, at 1, 25, and 35 minutes of reperfusion) and interleukin-8 (29.6+/-4.5 pg/mL versus 54.0+/-9.4, pg/mL, resp., at 35 minutes of reperfusion) resulted from treatment with sodium nitroprusside. No intracardiac production of interleukin-8 in sodium nitroprusside-treated patients (-1.1+/-0.4 pg/mL and -2.8+/-2.2 pg/mL, resp., for the coronary sinus-radial artery difference at 5 and 25 minutes of reperfusion) was observed, whereas cardiac production of interleukin-8 was present in controls (2.5+/-1.5 pg/mL and 5.5+/-2.8 pg/mL, resp.). Retention of platelet/leukocyte coaggregates occurred during coronary passage in controls (coronary sinus-radial artery difference for CD41-positive monocytes at 1 and 10 minutes of reperfusion, -16.3%+/-8.5% and -8.8%+/-2.6%, resp.). This was reduced in sodium nitroprusside-treated patients (with 5.8%+/-5.2% and 0.0%+/-3.2%). Retention of platelets in controls (ratio of coronary sinus to radial artery platelet count at 5 and 10 minutes of reperfusion, 88%+/-6% and 91%+/-5%) was compared to washout in treated patients (108%+/-6% and 113%+/-7%). CONCLUSIONS: In patients undergoing routine coronary artery bypass grafting, administration of sodium nitroprusside during early reperfusion alleviates systemic inflammation and the cardiac inflammatory response.

Aged↗

PubMed1999

Acute cardiac inflammatory responses to postischemic reperfusion during cardiopulmonary bypass.

OBJECTIVES: The investigation centers on whether there is a reperfusion-induced specific cardiac inflammatory reaction after bypass surgery. BACKGROUND: Cardiopulmonary bypass (CPB) leads to systemic inflammation. Additionally, cardiac inflammation due to reperfusion could occur. Knowledge about nature and time course of this reaction might help to develop cardioprotective interventions. METHODS: In 12 patients receiving coronary bypass grafts, arterial and coronary venous blood was obtained before onset of CPB, and 1, 5, 10, 25, 35 and 75 min after cardiac reperfusion. Plasma levels of IL6 and IL8 were measured by immunoassay. CD11b, CD41, and CD62 on blood cells were quantified by flow cytometry. Measurement of CD41, a platelet marker, on neutrophils and monocytes allowed detection of leukocyte-platelet microaggregates. RESULTS: Transcardiac veno-arterial difference of IL6 rose in the 10th and 25th min of reperfusion (from 0 to 7 pg/ml; p < 0.05), and after 75 min (15 pg/ml). IL8 did not change. CD11b on neutrophils (PMN) decreased transcardially to 95, 88 and 82% of the initial level in the 5th, 10th, and 75th min, respectively, suggesting sequestration of activated neutrophils. CD62 on platelets rose about 30% in the 75th min. Initially, leukocyte-platelet microaggregates were formed during coronary passage (+31% of the arterial level for PMN, +23% for monocytes). During reperfusion, coaggregates were retained (PMN: -1% and -7% in the 5th and 10th min, monocytes: -22%, -13% and -12% in the 1st, 5th and 10th min. CONCLUSIONS: During early reperfusion after aortic declamping, the coronary bed is already a source of proinflammatory stimuli and target for activated leukocytes, partly in conjunction with platelets. Mitigation of these phenomena might help to improve cardiac function after CPB especially in patients at risk.

Analysis of Variance↗

PubMed1999

Indirect enhancement of neutrophil activity and adhesion to cultured human umbilical vein endothelial cells by isoprostanes (iPF2alpha-III and iPE2-III).

Isoprostanes are metabolites of arachidonic acid found in blood under various conditions of oxidative stress. Because arachidonic acid derivatives are major mediators of inflammation, we investigated the potential inflammatory effects of iPF2alpha-III (previously 8-isoPGF2alpha) and iPE2-III (8-isoPGE2) on human polymorphonuclear granulocytes (PMN), as well as on human umbilical vein endothelial cells (HUVECs). The early activation marker CD11b on PMN and the adhesion molecules ICAM-1, E-selectin, and P-selectin on HUVECs were quantified by flow cytometry. Levels of the cytokines interleukin (IL)-6 and IL-8 were measured in the culture supernatant by enzyme-linked immunosorbent assay. Furthermore, adhesion of PMN to HUVECs was assessed. Neither isoprostane showed any direct stimulatory effects on PMN or HUVECs at concentrations of 0.1 or 1 microM: there was no acute elevation in expression of CD11b or P-selectin and no change of ICAM-1 or E-selectin after 4 or 24 h of incubation, respectively. The levels of interleukin IL-6 and IL-8 were also unaltered. However, PMN adhesion was significantly enhanced both after 4 and 24 h of incubation of HUVECs with iPF2alpha-III, and CD11b expression on PMN was elevated by contact of these cells with the supernatant of pre-exposed HUVECs. Neither of these actions were inhibited by an endothelin receptor antagonist (bosentan) or a combined thromboxane A2/isoprostane-receptor antagonist (SQ29548). Thus, although not having a direct pro-inflammatory potential, isoprostanes might indirectly accentuate PMN stimulation. This seems to occur via a receptor-independent mechanism, perhaps the production of an active metabolite of isoprostanes by endothelial cells.

Cell Adhesion↗

PubMed1999

Ketamine does not inhibit inflammatory responses of cultured human endothelial cells but reduces chemotactic activation of neutrophils.

BACKGROUND: Ketamine is a widely used general anaesthetic, which has been reported to inhibit neutrophil function and neutrophil-endothelial interaction. To date, however, it is unknown whether ketamine has any direct effects on endothelial cells with respect to inflammation. Therefore, we investigated the influence of varying concentrations of ketamine (0.5, 1, and 3 microM) on the endothelial expression of cytokines and adhesion molecules with relevance for inflammation. METHODS: Cultured human umbilical vein endothelial cells were stimulated with tumor necrosis factor alpha (TNFalpha, 2.5 ng/ml) for 4 h in the absence or presence of ketamine. The adhesion molecules ICAM-1 and E-selectin on the endothelial cells were measured by flow cytometry. Release of the proinflammatory cytokines IL-6 and IL-8 by endothelial cells was quantified by ELISA. The acute effect of ketamine on leukocyte activation by the supernatant of endothelial cells pre-stimulated with TNFalpha (4 h) was tested by flow cytometric measurement of CD11b, a leukocyte activation marker, after 15 min of coincubation. RESULTS: TNFalpha caused dramatic upregulation of both adhesion molecules (15-fold and 5-fold vs. control for ELAM-1 and ICAM-1, respectively) and of both cytokines (500-fold and 1.8-fold for IL-6 and IL-8, respectively). No concentration of ketamine employed in our study had any effect on these inflammatory parameters. However, activation of leukocytes by supernatant of TNFalpha-conditioned endothelial cells (70% increase of CD11b) was attenuated by coincubation of the PMN with 0.5 and 5 microM ketamine (47% and 44% increase, respectively). CONCLUSION: These data suggest that ketamine exerts its antiinflammatory actions primarily via inhibition of leukocyte reactivity. Indeed, no inhibition of endothelial responses was detectable in our study.

Anesthetics, Dissociative↗

PubMed1999

S(+)-ketamine, but not R(-)-ketamine, reduces postischemic adherence of neutrophils in the coronary system of isolated guinea pig hearts.

UNLABELLED: Polymorphonuclear neutrophils (PMN) play a crucial role in the initiation of reperfusion injury. In a previous study, we found that ketamine reduced the postischemic adherence of PMN to the intact coronary system of isolated guinea pig hearts. Because ketamine is a racemic mixture (1:1) of two optical enantiomers, we looked for possible differences in action between the stereoisomers. Seventy-six guinea pig hearts were perfused in the "Langendorff" mode under conditions of constant flow (5 mL/min) using modified Krebs-Henseleit buffer. After 15 min of global warm ischemia, freshly isolated human PMN (10(6)) were infused as a bolus into the coronary system during the second minute of reperfusion. PMN adhesion was expressed as the numeric difference between PMN recovered in the effluent and those applied. Series A hearts received 5 microM S(+), 5 microM R(-), or 10 microM racemic ketamine starting 20 min before ischemia and during reperfusion. In Series B hearts, 10 microM nitro-L-arginine, an inhibitor of NO synthase, was added to the perfusate. In Series C, PMN were preincubated for 15 min with 5 microM S(+)- or R(-)-ketamine. Coronary vascular leak was assessed by measuring the rate of formation of transudate on the epicardial surface. Ischemia/reperfusion without anesthetics increased coronary PMN adherence from 25.5% +/-2.3% (basal) to 35.3%+/-1.5% of the number applied. S(+)-ketamine reduced postischemic adherence in each series (A, 25.5%+/-5.1%; B, 22.5%+/-1.7%; C, 25.3%+/-7.7%), as did racemate (A, 26.4%+/-3.7%). Although 5 microM R(-)-ketamine had no effect on adhesion (A, 30.5%+/-6.7%; B, 34.3%+/-5.1%; C, 34.3%+/-4.3%), it significantly increased vascular leak in the presence of NOLAG. These findings indicate stereoselective differences in biological action between the two ketamine isomers: S(+)-ketamine inhibited PMN adherence, R(-)-ketamine worsened coronary vascular leak in reperfused isolated hearts. IMPLICATIONS: In this study, we demonstrated stereoselective differences in the biologic action of the two ketamine isomers in an animal model of myocardial ischemia. Polymorphonuclear neutrophil adherence to the coronary vasculature after ischemia was inhibited by S(+)-ketamine, whereas R(-)-ketamine increased coronary vascular fluid leak.

Anesthetics, Dissociative↗