Regulation of ICAM-1 and IL-6 in myocardial ischemia: effect of reperfusion.
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Amino Acid Sequence↗
Biomedical subjects
C W Smith
Publications and source records attributed to C W Smith.
Complement and tumor necrosis factor-alpha contribute to Mac-1 (CD11b/CD18) up-regulation and systemic neutrophil activation during endotoxemia in vivo.
The increased expression of Mac-1 (CD11b/CD18) adhesion glycoproteins on neutrophils was studied using flow cytometry in male Fischer 344 rats treated with 5 mg/kg Salmonella enteritidis endotoxin. A rapid and sustained threefold increase of Mac-1 expression was observed after endotoxin injection. Inhibition of complement activation with the soluble complement receptor type 1 (sCR1) completely suppressed the initial up-regulation of Mac-1 (< or = 15 min) but did not prevent the activation during the later phase (30-90 min). During that time period, Mac-1 expression increased in parallel with the concentration of tumor necrosis factor alpha (TNF-alpha) in plasma and could be significantly attenuated with TNF antiserum. To verify the results, isolated human neutrophils were incubated with rat plasma obtained at various times after endotoxin injection. Using shape change as indicator of neutrophil activation, complement and TNF-alpha could be identified as responsible mediators for neutrophil activation during endotoxemia in vivo. In contrast, the massive neutrophil accumulation in the liver after endotoxin was only slightly reduced by sCR1 and unaffected by TNF antiserum. It is concluded that Mac-1 up-regulation on neutrophils after endotoxin injection in vivo may have limited relevance for hepatic neutrophil infiltration but may be important for the pathogenesis of endotoxin-induced liver injury by facilitating adherence-dependent neutrophil cytotoxicity.
Animals↗
Antineutrophil monoclonal antibody (1F12) alters superoxide anion release by neutrophils and Kupffer cells.
The formation of oxygen-derived radicals by phagocytes is regulated by chemotactic agents, cytokines, and adhesion molecules, such as CD11b/CD18 (Mac-1). In the rat system, we investigated the effect of monoclonal antibody 1F12 against rat neutrophils on hepatic sequestration of neutrophils and superoxide release by hepatic phagocytes. Within 15 min after 1F12 injection, there was profound neutropenia, which persisted for 24 h. The majority of the "lost" neutrophils were sequestered in the liver 4 h after treatment. Zymosan-induced superoxide release in vitro by isolated hepatic neutrophils from 1F12-treated rats was significantly attenuated at 4 and 24 h. The phorbol myristate acetate mediated superoxide release was inhibited 24 h after treatment. Superoxide anion release by normal adherent neutrophils in the presence of agonists was also inhibited by 1F12 in vitro. The in vivo administration of 1F12 primed the Kupffer cells to release superoxide. In vitro treatment of Kupffer cells with 1F12 also stimulated superoxide release. Monoclonal antibody WT.3 (also directed against rat neutrophils), which does not cause neutropenia, did not alter superoxide generation by neutrophils and Kupffer cells. These results indicate that 1F12 may be useful in attenuating inflammation and tissue injury associated with neutrophil activation. However, the activation of Kupffer cells to release toxic oxygen-derived metabolites may predispose the liver to injury in certain pathological conditions.
Animals↗
Sterility of the umbilical cord.
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Female↗
A beam profile generation algorithm for wedged half-beam blocked asymmetric fields.
A method is presented to predict beam profiles and outputs for wedged asymmetric fields defined by independent collimator jaws allowing fast generation of beam profiles whilst requiring very little additional data to that already used by most treatment planning systems in generating symmetric field isodoses. Symmetric field data are modified by the use of wedged primary off-centre ratios (POCRS) which are obtained from in air measurements of the largest possible wedged field. Beam hardening occurring within the flattening filter and wedge is taken into account by the use of attenuation coefficients measured under each wedge and used to generate the wedged POCR at depth. A full investigation into the comparison between measured and calculated profiles was performed which demonstrates favourable agreement across the whole of the asymmetric field including the penumbra.
Algorithms↗
Accuracy of dose calculation methods for retracted tissue compensators.
Uncertainties arise in dose calculations involving retracted tissue compensators due to the effects of the compensator upon the scatter component of the dose. Many commercial treatment-planning systems cannot allow directly for the presence of a compensator in isodose calculation or else use simple 2D methods. We present data to test calculation accuracy for a wax compensation system by comparing retraction factors measured along central-axis and off-axis raylines for a variety of compensator shapes, with those derived using effective attenuation coefficient and 3D analytical calculations. The accuracy of using measured uniform-thickness retraction factors for non-uniform shapes and the dose uniformity achievable using a simple compensation system are also discussed. We conclude that the accuracy of simple calculation methods is shape dependent and that calculation errors and dose variations can exceed +/-5% where missing-tissue thickness variations are large. The analytical method is shown to give good agreement with experiment and indicates that it should be possible to adapt algorithms that calculate scatter from the patient for use with compensators.
Algorithms↗
Postreperfusion inflammation: a model for reaction to injury in cardiovascular disease.
In the preceding section various strategies to interdict postreperfusion inflammatory injury of the myocardium were proposed; effectively the strategies were aimed at specific targets such as stimuli which control cell motility, mechanisms of alteration of cell phenotype, and the induction of cell adhesion and proliferation. It is of interest to see how similar these targets would be if one were to attempt a cell biological approach to vascular injury which results in subintimal hyperplasia. In the latter, cells in the media adopt a phenotype which allows cell migration in the direction of a gradient (presumably chemotactic) which directs them to the subintima which is the site of injury. This motility is associated with the expression in these cells of non-muscle myosin and beta actin, both of which are implicated in the motility of leucocytes. Another similarity between acute inflammation and subintimal hyperplasia relates to the role of cellular adhesion as an important determinant of cell motility. As reviewed above, leucocyte motility involves cell adhesion mediated by a class of molecules termed leucocyte integrins (beta 2 integrins) which vary in their alpha subunits and share CD18 as a common beta subunit (CD11a/CD18 = LFA-1, CD11b/CD18 = Mac-1). The activation and inactivation of these integrins is associated with a high and low affinity state, and motility is effected by the cycling of high and low affinity states as well as by cytoskeleton mediated redistribution of adhesion molecules on the leucocyte membrane. In similar fashion, the migration of medial cells and macrophages to the subintima is associated with specific adhesion to extracellular matrix. This adhesion is mediated by similar classes of integrins containing varying alpha subunits and common beta subunits (in this case beta 1 or beta 3) that have been also shown to undergo activation and inactivation cycles yielding high and low affinity states. The similarities between these integrin mediated adhesion events in leucocytes and in the vascular cells is further emphasised by the fact that leucocytes also contain beta 1 integrins; in fact monocytes and T-lymphocytes express a beta 1 integrin (VLA-4) which supports transmigration out of the vascular space via its interaction with VCAM-1 as an alternative to beta 2 integrin-ICAM-1 adhesion. Substantial evidence suggests that integrin mediated adhesion also functions as a transducer of cell secretion of matrix proteins, growth factors, and cytokines from smooth muscle cells, tissue macrophages, transmigrated leucocytes, and endothelial cells.(ABSTRACT TRUNCATED AT 400 WORDS)
Chemotactic Factors↗
Do the clinical years change medical students' attitudes to old people?
Students at the Christchurch School of Medicine have previously been shown to demonstrate a significant improvement in attitudes and knowledge about old people after a 5-week attachment in their first clinical year (fourth year of their medical course). The original cohort were retested between 1 and 3 years after graduation. A modified version of the Rosencranz-McNevin Semantic Differential Scale was used to measure general attitudes to old age and a Likert scale to measure attitudes to medical care and knowledge. Attitudes measured by the Rosencranz-McNevin Scale showed no change between the completion of the fourth-year attachment and graduation. The Likert scale showed no change in knowledge but the attitude score showed a worsening (P < 0.001). Knowledge and attitudes of graduates who had completed a house office attachment in health care of the elderly were better than those who had not (knowledge P < 0.01, attitude P < 0.06).
Aged↗
Cardiac pacemaker electrodes: improved methods of extraction. Work in progress.
PURPOSE: To develop improved methods of extracting pacemaker electrodes from the femoral vein by using standard equipment and techniques. MATERIALS AND METHODS: Pacemaker electrodes were removed from 61 patients aged 21-91 years (mean, 68 years). In 25 patients (41%), traction was applied to locking stylets to remove electrodes at the subclavian vein entry site. In 30 patients, the electrode tip was freed with traction at the subclavian vein entry site. The electrode was then extracted through a sheath placed in the femoral vein. In six patients (10%), the electrode tip was freed via the femoral vein when traction was applied to grasping devices. The electrode was then removed through a femoral venous sheath. RESULTS: Ninety-nine (95%) of 104 pacemaker electrodes were extracted completely. Two electrodes were trapped in fibrous tissue in the subclavian vein. One right atrial tear occurred. CONCLUSION: Pacemaker electrodes can be removed effectively by using percutaneous techniques.
Aged↗
P-selectin and ICAM-1-dependent adherence reactions: role in the genesis of postischemic no-reflow.
The aim of this study was to determine whether immunoneutralization of P-selectin or intercellular adhesion molecule-1 (ICAM-1) (endothelial cell adhesion molecules involved in leukocyte rolling and firm adhesion, respectively) would attenuate the development of postischemic capillary no-reflow. Microvascular patency was assessed in vascularly isolated canine gracilis muscles by perfusion with contrast media (India ink) at the end of the experimental protocol. Computerized video imaging was used to quantitate the number of ink-containing microvessels (< 10 microns diam) per muscle fiber in histological samples obtained from isolated canine gracilis muscles subjected to 4.5 h of continuous perfusion (nonischemic control), 4 h of ischemia and 30 min of reperfusion (I-R), I-R + P-selectin monoclonal antibodies (MAbs) (MD6 or PB1.3), and I-R + ICAM-1 MAbs (CL18/6C7 or R6.5). The efficacy of a P-selectin MAb (MD3) that binds to a nonfunctional epitope was also evaluated. I-R was associated with a marked reduction in the number of patent capillaries per fiber (3.1 +/- 0.2 vs. 1.1 +/- 0.2 patent capillaries/fiber for control and I-R, respectively). Immunoneutralization with MAbs directed against functional epitopes on P-selectin (MD6 or PB1.3) significantly improved capillary perfusion (2.3 +/- 0.3 and 3.6 +/- 0.6 patent capillaries/fiber, respectively). On the other hand, MAb MD3, which binds to nonfunctional epitopes on P-selectin, failed to limit the development of postischemic no-reflow (1.0 +/- 0.2 patent capillaries/fiber). Immunoneutralization of ICAM-1 with CL18/6C7 and R6.5 increased the number of patent capillaries per fiber to 1.8 +/- 0.1 and 2.5 +/- 0.3, respectively. These data indicate that P-selectin and ICAM-1-dependent adherence reactions play an important role in the development of the no-reflow phenomenon in postischemic skeletal muscle.
Animals↗
Partial characterization of leukocyte binding molecules on endothelial cells induced by minimally oxidized LDL.
Treatment of rabbit aortic endothelial cells, human umbilical vein endothelial cells, and human aortic endothelial cells for 4 hours with minimally oxidized low-density lipoprotein (MM-LDL) induced the adhesion of monocytes but not neutrophils or lymphocytes to these cells. This induction was blocked by inhibitors of glycoprotein synthesis (cycloheximide and tunicamycin), and binding was abolished by treatment of cells with low levels of trypsin, suggesting that the binding molecule(s) is a protein. There was no increase in binding of antibodies to E-selectin, vascular cell adhesion molecule-1 (VCAM-1), or intercellular adhesion molecule-1 (ICAM-1) after treatment of cells with MM-LDL. Treatment of endothelial cells with Fab fragments of antibody to monocyte chemotactic protein-1 or to fibronectin did not block monocyte binding. Several sugars (lactose-1-phosphate, maltose-1-phosphate, and N-acetylglucosamine) inhibited monocyte binding to cells treated with MM-LDL, but binding was not blocked by mannose-6-phosphate, fructose-6-phosphate, glucose-1-phosphate, or glucose-6-phosphate. EDTA or EGTA treatment inhibited binding, which was restored by adding either calcium or magnesium. We conclude that the binding of monocytes to endothelial cells induced by a 4-hour treatment with MM-LDL is caused by a binding molecule(s) other than E-selectin, VCAM-1, or ICAM-1 and that carbohydrate chains on the monocytes or the endothelium play a role in binding.
Cell Adhesion↗
Molecular evidence for induction of intracellular adhesion molecule-1 in the viable border zone associated with ischemia-reperfusion injury of the dog heart.
BACKGROUND: Acute inflammation may play a role in injury during reperfusion following myocardial ischemia. Studies in vitro suggest that intracellular adhesion molecule-1 (ICAM-1) mediates neutrophil adherence to cardiac myocytes and neutrophil-mediated injury. We have shown cytokine activity in postischemic cardiac lymph sufficient to maximally express ICAM-1 on myocytes and that ICAM-1 mRNA is found in the previously ischemic myocardium early in reperfusion. METHODS AND RESULTS: In the present study, we used in situ hybridization techniques to detect ICAM-1 mRNA and examine the cells of origin, relation to cell injury, and relation to inflammatory infiltration after 1 hour of ischemia and varying times of reperfusion. By 1 hour of reperfusion, ICAM-1 mRNA was detected in much of the ischemic myocardium, except in areas of contraction band necrosis. At 2 and 3 hours, a clear demarcation of necrotic areas surrounding ischemic areas of viable myocardium with ICAM-1 mRNA staining was present, and ICAM-1 mRNA staining increased with time. Nonischemic areas had no visible ICAM-1 mRNA staining in the first 3 hours. By 24 hours of reperfusion, ICAM-1 mRNA was present in both control and ischemic segments (excluding the necrotic areas) compatible with a generalized circulation of cytokines persistent at 24 hours. In the absence of reperfusion, ICAM-1 mRNA staining was not seen in the first 3 hours and was markedly reduced at 24 hours. The interface of viable and necrotic cells also contained the most extensive inflammatory infiltration. CONCLUSIONS: Evidence is presented that induction of ICAM-1 mRNA has highly specific localization to ischemic but viable myocardium. Induction of ICAM-1 mRNA transcription in early reperfusion may render the viable "border zone" susceptible to neutrophil-induced injury.
Animals↗
Intracellular oxidative stress induced by nitric oxide synthesis inhibition increases endothelial cell adhesion to neutrophils.
The objective of the present study was to determine whether prolonged inhibition of nitric oxide synthesis in endothelial cells increased the surface adhesion of these cells for neutrophils. Human umbilical vein endothelial cells (HUVECs) were grown to confluence in 48-well microtiter plates. Exposure of HUVECs to the nitric oxide synthesis inhibitor NG-nitro-L-arginine methyl ester (L-NAME) did not cause neutrophil adhesion at 1 hour but increased adhesion at 4 hours in a dose-dependent manner. The increased adhesion was prevented with L-arginine or nitric oxide donors but not an analogue of cGMP. The increased adhesion was inhibited by monoclonal antibodies directed against the beta 2-integrin CD18 and endothelial cell adhesion molecule ICAM-1. Platelet-activating factor (PAF) receptor antagonist WEB 2086 also prevented the L-NAME-induced neutrophil adhesion. Intracellular oxygen radical scavengers (dimethyl sulfoxide, butylated hydroxytoluene, and alpha, alpha'-dipyridyl), the iron chelator desferrioxamine, and the mitochondrial inhibitor azide inhibited the L-NAME-induced neutrophil adhesion, whereas extracellular oxygen radical scavengers (superoxide dismutase and catalase) had no effect. HUVECs were loaded with 2',7'-dichlorodihydrofluorescein diacetate, and oxidation to the fluorescent dichlorodihydrofluorescein (DCHF) was monitored. Fluorescence was enhanced in the L-NAME-treated HUVECs throughout the 4-hour incubation, an event inhibitable by an antioxidant and azide. The magnitude of the intracellular oxidation of DCHF was equivalent to approximately 0.8 mumol/L H2O2. These data suggest that prolonged nitric oxide synthesis inhibition in HUVECs causes an oxidant- and PAF-associated rise in adhesion on the surface of these endothelial cells for neutrophils.
Antigens, CD↗
Induction of intercellular adhesion molecule-1 by lipopolysaccharide in canine alveolar macrophages.
Previous studies have demonstrated that alveolar macrophages (AMphis) adherent to plastic release interleukin-8 in response to lipopolysaccharide (LPS). We sought to determine whether LPS could also alter surface adhesion molecule expression and thus modulate additional AMphi adhesive interactions. Canine AMphis obtained by bronchoalveolar lavage of excised lung were adhered onto tissue culture plastic and exposed to LPS (0.01 to 100 ng/ml). Expression of beta 2 integrins and intercellular adhesion molecule-1 (ICAM-1) was subsequently determined by flow cytometry, a cDNA probe to canine ICAM-1 was used to quantify ICAM-1 mRNA, and changes in adhesion molecule function were assessed by evaluating the extent of homotypic aggregation. ICAM-1 and CD11a/CD18 were present on freshly isolated AMphis. CD11b/CD18 and CD11c/CD18 were expressed at lower levels. Nonadherent AMphis expressed a pattern of beta 2 integrin and ICAM-1 comparable to adherent cells. During short-term LPS stimulation (3 h), adherent AMphis increased both the synthesis and expression of ICAM-1. CD18 expression was either decreased or remained unchanged with LPS stimulation. LPS stimulation in vitro (> 0.01 ng/ml) enhanced the homotypic aggregation of adherent AMphis. Aggregation was blocked by monoclonal antibodies to ICAM-1 (CL18/6) and CD11a (R7.1) and CD18 (R15.7). Similar kinetics were found for expression of ICAM-1 and homotypic aggregation, suggesting that up-regulation of ICAM-1 is a major determinant of the LPS-stimulated aggregation of AMphis.
Animals↗
A two-step adhesion cascade for T cell/endothelial cell interactions under flow conditions.
Neutrophil adherence to endothelial cells (ECs) under conditions of flow occurs in successive steps, including selectin-dependent primary adhesion and CD18-dependent secondary adhesion. We used a parallel-plate flow chamber to assess the steps in T cell adherence in vitro. On monolayers of L cells transfected with the EC adhesion molecules E-selectin, vascular cell adhesion molecule-1 (VCAM-1), or intercellular adhesion molecule-1 (ICAM-1), E-selectin was capable of mediating only primary adhesion, ICAM-1 was capable of mediating only secondary adhesion, and VCAM-1 was capable of mediating both primary and secondary adhesion. Studies using human umbilical vein EC monolayers stimulated for 24 h with IL-1 also revealed distinct primary and secondary steps in T cell adhesion under flow, and the secondary adhesion was inhibited > 90% by blocking both VCAM-1/alpha 4 beta 1 integrin and ICAM-1/CD18 integrin pathways. However, the primary adhesion under conditions of flow could not be attributed to any of the mechanisms known to support adhesion of leukocytes to ECs. Alone, this pathway was shown to mediate T cell rolling and was a necessary prerequisite for engagement of the two integrin pathways in this system. Thus, T cell adherence to 24-h IL-1-stimulated human umbilical vein ECs at venular wall shear stresses involves at least two successive steps, with clear molecular distinctions from the mechanisms accounting for neutrophil/EC adhesion.
Animals↗
Role of leukocyte adhesion molecules in lung and dermal vascular injury after thermal trauma of skin.
Acute second degree thermal injury of rat skin involving 25 to 30% total body surface of anesthetized rats results at 4 hours in evidence of vascular injury both locally (in skin) and remotely (involving lung). The neutrophil dependency for both types of injury has now been established. Monoclonal antibodies to various adhesion molecules have been used to define the requirements for these molecules in the development of vascular injury. In dermal vascular injury, a requirement for Mac-1 (CD11b/CD18) but not for leukocyte function-associated antigen-1 (LFA-1, CD11a/CD18) has been established. In this model requirements have also been demonstrated for intercellular adhesion molecule-1 (ICAM-1) and E- and L-selectin but not for very late arising antigen-4 (VLA-4) or P-selectin. With respect to lung vascular injury, dual requirements for both leukocyte function-associated antigen-1 and Mac-1 were found as well as for ICAM-1 and E- and L-selectin but not for VLA-4 and P-selectin. In the lung, there was a close correlation between neutrophil content of the tissue (as assessed by myeloperoxidase) and the effects of protective interventions (directed against blocking of adhesion molecules). These data emphasize the roles of beta 2 integrins, selectins (L and E), and ICAM-1 in events that lead to neutrophil-mediated vascular injury of dermis and lung after thermal trauma to skin.
Animals↗
Beneficial effects of extracellular glutathione against endotoxin-induced liver injury during ischemia and reperfusion.
The potential beneficial effect of hepatocellular glutathione against inflammatory liver damage was investigated in a model of endotoxin-enhanced ischemia-reperfusion injury. Animals were subjected to 20 min of hepatic ischemia, followed by 4 hr of reperfusion. The injection of 0.5 mg/kg Salmonella enteritidis endotoxin potentiated liver injury and the postischemic oxidant stress, as indicated by increased plasma levels of glutathione disulfide. Depletion of hepatic glutathione levels by > 90% with phorone and inhibition of glutathione synthesis with buthionine sulfoximine further increased liver injury in this model, as indicated by enhancement of plasma alanine aminotransferase activities from 2,234 +/- 122 U/L to 4,024 +/- 282 U/L. Continuous infusion of a glutathione (GSH) solution in GSH-depleted animals (22 mumol/kg/hr) attenuated reperfusion injury by 55%. In vitro experiments demonstrated the capability of GSH to react rapidly with reactive oxygen species, such as hydrogen peroxide (H2O2) and hypochlorous acid (HOCl). Only H2O2 oxidized GSH quantitatively to its disulfide; HOCl oxidized GSH to higher oxidation states. These data support the hypothesis that the enhanced release of hepatocellular GSH functions as a defense mechanism against reactive oxygen species generated by inflammatory cells during endotoxemia and reperfusion. This internal defense system of the liver may be of general importance in preventing, or at least limiting, liver damage by reactive oxygen generated in particular by Kupffer cells during their physiological function to remove gut-derived endotoxin and bacteria.
Animals↗
Contribution of complement-stimulated hepatic macrophages and neutrophils to endotoxin-induced liver injury in rats.
The role of complement as potential activator for tissue macrophages and neutrophils was investigated in an experimental model of endotoxin-induced liver injury in male Fischer rats. Injection of Salmonella enteritidis endotoxin (1 mg/kg) into Corynebacterium parvum-pretreated animals (7 mg/kg; single dose 6 days before endotoxin) resulted in severe oxidant stress, as indicated by a 37-fold increase of plasma levels of glutathione disulfide (basal concentration, 0.36 +/- 14 mumol/L), accumulation of neutrophils in the liver (600 +/- 31 neutrophils/50 high-power fields) and liver injury (plasma ALT, 1184 +/- 185 U/l; necrosis; 19% +/- 3%) 10 hr after endotoxin. The oxidant stress induced by 1 mg/kg endotoxin in the C. parvum-treated animals was always significantly higher than that in control animals receiving the same dose of endotoxin. Inhibition of complement activation with the soluble complement receptor type 1 attenuated the oxidant stress and liver injury by 50% to 65% but had no effect on hepatic neutrophil accumulation or plasma tumor necrosis factor-alpha levels. Treatment with a monoclonal antibody directed against the alpha-chain of CD11b/CD18 adhesion proteins (clone 17), which was highly effective in attenuating ischemia-reperfusion injury in the liver by reducing the number of neutrophils and functionally inactivating these cells, neither protected against parenchymal cell injury nor affected hepatic neutrophil infiltration in the C. parvum model. We conclude that reactive oxygen derived from complement-stimulated macrophages is critical for the development of liver injury in the C. parvum/endotoxin model.
Adenosine Triphosphate↗