Biomedical subjects

M M Rozek

Publications and source records attributed to M M Rozek.

At least 19 recordsLinked to original sources

PubMed2001

Randomized, placebo-controlled study for immunosuppressive treatment of inflammatory dilated cardiomyopathy: two-year follow-up results.

BACKGROUND: Previous studies have shown disappointing results for immunosuppressive treatment in patients with dilated cardiomyopathy. Therefore, we studied the effectiveness of such therapy in patients with HLA upregulation on biopsy. METHODS AND RESULTS: Of 202 patients with dilated cardiomyopathy, 84 patients with increased HLA expression were randomized to receive either immunosuppression or placebo for 3 months; they were then followed for 2 years. After 2 years, there were no significant differences in the primary end point (a composite of death, heart transplantation, and hospital readmission) between the 2 study groups (22.8% for the immunosuppression group and 20.5% for the placebo). The secondary efficacy end point included changes in ejection fraction, end-diastolic diameter, end-diastolic volume, end-systolic volume and NYHA class; left ventricular ejection fraction increased significantly in the immunosuppression group compared with the placebo group (95% CI, 4.20 to 13.12; P<0.001) after 3 months of follow-up. The early favorable effects of immunosuppressive therapy on left ventricular volume, left ventricular diastolic dimension, and New York Heart Association class were also present. This improvement was maintained in the immunosuppression group at 2 years (ejection fraction: 95% CI, 6.94 to 19.04; P<0.001). In addition, on the basis of the protocol-specified definition of improvement, 71.8% patients in the immunosuppression group versus 20.9% patients in the placebo group met the criteria of improvement after 3 months (P<0.001). At the end of the follow-up period, 71.4% patients from the immunosuppression group versus 30.8% patients from the placebo group were improved (P=0.001). CONCLUSIONS: These data demonstrate a long-term benefit of immunosuppressive therapy in patients with dilated cardiomyopathy and HLA upregulation on biopsy specimens. Thus, restoration of immunosuppressive therapy for such patients should be considered.

Adult↗

PubMed2001

Local delivery of enoxaparin to decrease restenosis after stenting: results of initial multicenter trial: Polish-American Local Lovenox NIR Assessment study (The POLONIA study).

BACKGROUND: Enoxaparin inhibits smooth muscle cell proliferation in experimental models. Intimal hyperplasia has been found to be the principal cause of restenosis after coronary stent implantation. We sought to determine whether the intramural delivery of enoxaparin before stenting of de novo lesions decreases restenosis. METHODS AND RESULTS: One hundred patients who were undergoing stenting were randomly assigned to either local administration of enoxaparin during predilation with reduced systemic heparinization or stenting with standard, systemic heparinization. All patients were treated with the same type of stent (NIR). The primary study end point was late luminal loss. The secondary end points were major adverse cardiac events, target lesion revascularization, and angiographic restenosis at 6 months. Angiographic follow-up at 6 months was completed in all except 1 patient. Late luminal loss was reduced to 0.76+/-0.42 mm in the local enoxaparin delivery group versus 1. 07+/-0.49 mm in the systemic heparinization group (P:<0.001). Restenosis, using a binary definition, occurred in 10% of patients in the enoxaparin group and in 24% of patients in the systemic heparinization group (P:<0.05). Target lesion revascularization rates occurred in 8% of the enoxaparin group and 22% of the systemic heparinization group (P:<0.05). There were no deaths and no emergent CABGs were performed. The only subacute stent closure and non-Q-wave infarction occurred in a patient assigned to the systemic heparinization group. CONCLUSIONS: This is the first prospective randomized trial in which the local delivery of a drug, enoxaparin, resulted in significant reduction in late luminal loss and restenosis after stent implantation in de novo coronary lesions.

Anticoagulants↗

PubMed2001

Bilateral carotid stenting combined with three-vessel percutaneous coronary intervention in single setting.

We describe a patient who underwent bilateral internal carotid artery stenting and three-vessel percutaneous coronary intervention during the same procedure. Stenting of carotid arteries was performed employing our innovative technique combining coronary and peripheral devices. No complications occurred. The patient was discharged home 1 day after the intervention and remains asymptomatic, leading a fully active life. To our knowledge, unstaged bilateral carotid stenting combined with three-vessel coronary intervention has not been reported previously.

Aged↗

PubMed1999

Novel approach to rotational atherectomy results in low restenosis rates in long, calcified lesions: long-term results of the San Antonio Rotablator Study (SARS).

Ablation technique and adjunctive strategy may affect restenosis after rotational atherectomy. To minimize trauma to the vascular wall, we changed the technique of rotablation as follows: the RPM range was decreased to 140,000-160,000 RPM, the ablation was performed using a repetitive pecking motion, avoiding a decrease in the rotational speed of the burr greater than 3,000 RPM, long lesions were divided into segments and each segment was separately ablated, and the burr-to-artery ratio was intended to be approximately 0.75. To prevent coronary spasm, before and after each pass, 100-200 microg nitroglycerin and 100-200 microg verapamil i.c. boluses were administered. Adjunctive PTCA was performed using a closely sized 1.1:1 balloon-to-artery ratio with a noncompliant balloon at low pressures for 120 sec. The study incorporated 111 patients with a combined total of 146 calcified lesions. Results. A total of 31.5% of patients underwent a multivessel procedure. No deaths occurred. Q-wave MI and/or creatine kinase elevation greater than three times baseline levels occurred in 4.5% of patients. By quantitative coronary angiography (QCA), the reference vessel diameter was 3.13+/-0.59 mm, mean lesion length was 33.41+/-18.58 mm. Percent stenosis and mean luminal diameter were as follows: at baseline 75.7%+/-10.8%, or 0.76+/-0.41mm, Post-rotational atherectomy 41.5%+/-3.6%, or 1.83+/-0.43 mm, Post-PTCA 18.2%+/-11.9%, or 2.56+/-0.50 mm. Six-month angiographic follow-up was available in 64 (57.7%) pts. Net luminal gain was 1.15+/-0.76 mm, with a late luminal loss of 0.65+/-0.84 mm. The mean diameter stenosis at follow-up was 37.6%+/-28.5%, with MLD 1.91+/-1.21 mm. The binary restenosis rate was 28.1%. Therefore, modification of rotational atherectomy technique with adjunctive PTCA resulted in a favorable restenosis rate in long, calcified lesions. Cathet. Cardiovasc. Intervent. 48:48-53, 1999.

Angioplasty, Balloon, Coronary↗

PubMed1998

Acute directional coronary atherectomy prior to stenting in complex coronary lesions: ADAPTS Study.

The purpose of this study was to determine the results of directional coronary atherectomy (DCA) combined with stenting in a high-risk patient population. The use of stenting or DCA alone for aorto-ostial lesions, total chronic occlusions, long lesions, and lesions containing thrombus is associated with lowered success and a relatively high restenosis rate. Between July 1993 and October 1996, we treated 89 lesions with the combined approach of DCA and stenting in 60 consecutive patients. Thirty-one (51.7%) patients were treated because of unstable angina, 11 (18.3%) for post-myocardial infarction (MI) angina, 3 (5.0%) for acute MI, and 15 (25.0%) patients for stable angina. A total of 43 (71.7%) patients had multivessel disease, 19 (31.7%) had undergone previous coronary artery bypass graft (CABG), and 17 (28.3%) patients had undergone multivessel revascularization. The procedure was successful in all patients; and no postprocedural deaths or emergent CABG occurred. Two patients (3.3%) had non-Q-wave MI after the procedure and 1 patient (1.7%) experienced Q-wave MI due to subacute stent closure 7 days after the procedure. During follow-up ranging from 6 months to 3 years, 2 (3.3%) patients died, 2 (3.3%) required CABG surgery, 1 (1.7%) patient had an MI, and 6 patients (10.0%) required target vessel revascularization. By the quantitative coronary angiography, the initial minimal luminal diameter (MLD) averaged 0.91+/-0.45 mm (74.7+/-11.8% stenosis) increasing to 3.80+/-0.44 mm (-6.7+/-12.1%) after the combined approach procedure. Thirty patients (50.0%) met criteria for late (> or =6 months) angiographic follow-up. Late MLD loss averaged 1.13+/-1.07 mm, for a mean net gain of 1.61+/-1.23 mm. Available angiographic follow-up evaluation showed a restenosis rate of 13.3%. A combined approach, defined as the use of both DCA and stenting, is safe and yields a low restenosis rate in high-risk patients who have lesions known to respond less favorably to stenting or DCA alone.

Aged↗

PubMed1998

Immunohistological diagnosis of myocarditis. Potential role of sarcolemmal induction of the MHC and ICAM-1 in the detection of autoimmune mediated myocyte injury.

AIMS: The aim of this study was to characterize the up-regulation of major histocompatibility complex antigens class I (HLA-A, B, C) and class II (HLA-DR), and intercellular adhesion molecule-1 with special emphasis on de novo induction of these molecules on cardiac myocytes in patients with suspected myocarditis. METHODS: Endomyocardial biopsy specimens were obtained from 83 consecutive patients. Specimens were subdivided into two groups according to clinical presentation of the disease: Group A, 58 patients with idiopathic congestive heart failure and Group B, 25 patients without heart failure. In group A, 15% of patients had active myocarditis, 36% had borderline and 48% no myocarditis according to Dallas criteria. In group B, myocarditis distribution was 12%, 36% and 52%, respectively. The major histocompatibility complex was considered to be positive when the immunoreactivity index was > or = 3+; intercellular adhesion molecules were considered positive when the score was > or = 2+. RESULTS: We observed two characteristic staining patterns of the HLA molecules on cardiac myocytes: (i) multifocal sarcolemmal staining at the sites of mononuclear inflammatory infiltration, (ii) linear sarcolemmal staining with otherwise normal endomyocardium. Positive immunoreactivity was observed in 60% of patients in group A, and in 44% of patients in group B. We found no correlation between a histopathological diagnosis of myocarditis or left ventricular systolic function and positive immunoreactivity. CONCLUSION: The lack of correlation between immunohistological signs of active inflammation and clinical symptoms in patients with myocarditis may indicate independence of an immunological mechanism. The lack of correlation between immunoreactivity and histopathological diagnosis of myocarditis may suggest low sensitivity of traditional histological evaluation. In our opinion, the induction of major histocompatibility and intercellular adhesion molecules on cardiac myocytes may indicate an autoimmune inflammatory response in patients with inflammatory myocardial disease. Immunohistochemical methods may be helpful in selecting patients for immunosuppressive therapy.

Adult↗

PubMed1997

Ryanodine and left ventricular function in intact dogs: dissociation of force-based and velocity-based indexes.

After anesthesia and autonomic blockade, nine dogs chronically instrumented with left ventricular (LV) micromanometers and piezoelectric dimension crystals were studied before and after the intravenous administration of 4 micrograms/kg ryanodine, a specific inhibitor of the sarcoplasmic reticulum Ca2+ release channel. Ryanodine prolonged LV contraction and relaxation (P < 0.001) without changing heart rate, end-diastolic volume (EDV), or end-systolic pressure. Velocity-dependent mechanical parameters were significantly depressed, including the maximal rate of LV pressure rise (dP/dtmax; P < 0.002), the mean velocity of circumferential fiber shortening (P < 0.002), the slope of the dP/dtmax-EDV relation (P < 0.05), and the time constant of LV relaxation (P < 0.01). In contrast, the slopes of the end-systolic pressure-volume (PES-VES) and stroke work (SW)-EDV relations, both force-based parameters, were increased (P < 0.05) or maintained, respectively. Ryanodine reduced overall LV contractile performance, evidenced by significant rightward shifts of the PES-VES, dP/dtmax-EDV, and SW-EDV relations and reduced SW at constant preload (P < 0.02). Thus, in the closed-chest dog, low-dose ryanodine resulted in 1) generalized slowing of LV mechanical events without changes in heart rate or load, 2) dissociation of velocity-based and force-based measures of LV function, with depression of the former but enhancement or maintenance of the latter, and 3) reduced overall LV inotropic performance. These effects are consistent with ryanodine-induced alterations of the Ca2+ transient and altered sarcoplasmic reticulum Ca2+ availability.

Animals↗

PubMed1995

Molecular mimicry, anti-coxsackievirus B3 neutralizing monoclonal antibodies, and myocarditis.

Molecular mimicry has been suggested as one mechanism to explain chronic myocarditis in some murine strains in the postinfectious period following induction of acute myocarditis by coxsackievirus B3 (CVB3). To test this hypothesis, neutralizing mAbs were generated against a highly myocarditic CVB3 virus (CVB3m). These mAbs neutralized several myocarditic and amyocarditic CVB3 variants by cytopathic effects inhibition assays. Data from several experiments suggest that these mAbs recognize discontinuous epitopes on CVB3m capsid proteins. Several mAbs were found to induce cardiopathologic alterations subsequent to i.p. inoculation of normal adolescent male CD-1 or C3H/HeJ mice. Immunocytochemical assays demonstrated significant binding of two mAbs to the surface of normal cultured murine cardiac fibroblasts. Also, several mAbs were shown to participate in C-mediated lysis of normal cardiac fibroblasts, but this property did not correlate well with cardiopathogenic potential. The two properties of a mAb that were the best predictors for cardiopathogenic potential were the capacity for stimulation of normal murine fibroblasts to produce a chemoattractant activity for unelicted murine peritoneal macrophages, and the capacity for recognition of an epitopes(s) on murine or human cardiac myosins. These data show that some anti-CVB3m neutralizing mAbs can participate in proinflammatory reactions in vitro and induce cardiopathologic alterations in vivo, suggesting one mechanism by which CVB3-induced chronic inflammation in murine heart tissues can be sustained in the absence of continued virus replication.

Animals↗

PubMed1994

Gamma interferon stimulates monocyte chemotactic protein (MCP-1) in human mesangial cells.

Cell-mediated immunity and monocyte infiltration is a prominent histologic feature of several different types of glomerulonephritis. Monocyte influx to the glomerulus correlates with glomerular hypercellularity and proteinuria. Glomerular mesangial cells, in addition to being targets for inflammatory stimuli, are also effector cells that actively participate in glomerular pathology. Mesangial cells release monocyte chemotactic protein (MCP-1). In the present article, we characterized and studied the regulation of MCP-1 released by cultured human mesangial cells. Serum-deprived mesangial cells constitutively release chemotactic activity that is neutralized by specific anti-MCP-1 antibody. An antibody to baboon MCP-1 recognized 16, 15, and 11 kd proteins from concentrated conditioned medium that were consistent with the presence of different forms of MCP-1. Gamma interferon (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1 (IL-1) markedly stimulate the release of MCP-1 as measured by a specific and sensitive radioimmunoassay. The release of MCP-1 in response to these cytokines is at least partially dependent on de novo synthesis of the protein because all three cytokines markedly stimulate the expression of MCP-1 mRNA. These data demonstrate that human mesangial cells synthesize and release at least three different forms of MCP-1 and that IFN-gamma and other cytokines regulate the secretion of MCP-1. IFN-gamma and MCP-1 may play a major role in the recruitment and activation of monocytes to the inflamed glomerulus.

Blotting, Northern↗

PubMed1992

Pathogenesis of the atherosclerotic lesion. Implications for diabetes mellitus.

In this review, we have highlighted pivotal cellular and molecular events in the initiation and progression of atherosclerosis. Key components of lesion initiation are an enhanced focal intimal influx and accumulation of lipoproteins, including LDL in hemodynamically determined lesion-prone areas, focal monocyte-macrophage recruitment, intimal generation of ROS, and oxidative modification of lipoproteins (including LDL [Ox-LDL]). Modified lipoproteins are taken up by the non-downregulating macrophage scavenger receptor, with foam cell formation and the development of the so-called fatty streak. One transitional event in lesion progression is foam cell necrosis, likely attributable to the cytotoxicity of both intimal free radicals and Ox-LDL, with development of an extracellular metabolically inert lipid core. Another is the migration to and proliferation within the intima of medial SMCs, leading to the synthesis of plaque collagens, elastin, and proteoglycans. Mural thrombosis plays a significant role in the late-stage progression of lesions. Regression of lesions is considered a function of the dynamic balance among components of initiation, progression, plaque stabilization, and removal of plaque constituents--the so-called regression quartet. Here, we critically examine how components of diabetes mellitus might impact not only lesion development, but also lesion regression. It is concluded that some components of diabetes mellitus augment key mechanisms in lesion initiation and progression and will likely retard the processes of plaque regression. Specifically, we focus on the various influences of diabetes mellitus on lipoprotein influx and accumulation, free radical generation and Ox-LDL, monocyte-macrophage recruitment, thrombosis and impaired fibrinolysis, and the reverse cholesterol transport system. The importance of nonenzymatic protein glycosylation in modifying a number of these processes is emphasized.

Arteriosclerosis↗

PubMed1992

Mechanisms in intimal monocyte-macrophage recruitment. A special role for monocyte chemotactic protein-1.

This article briefly addresses the role of the monocyte-macrophage in atherogenesis and the potential mechanisms participating in intimal blood monocyte recruitment. The obligatory components of the recruitment process, i.e., contact with the vascular endothelium, attachment, and migration into the subendothelial space, are addressed with reference to the influence of blood flow, plasma proteins (particularly low density lipoprotein), and inflammatory mediators and cytokines. The potentially important role of monocyte chemotactic protein-1 in regulating monocyte recruitment in plaque pathogenesis is discussed.

Arteriosclerosis↗

PubMed1991

Characterization of monocyte chemotactic protein-1 binding to human monocytes.

Monocyte chemotactic protein-1 (MCP-1) stimulates chemotaxis of peripheral blood monocytes. In order to understand the biologic basis of this specific activity, binding studies of 125I-MCP-1 were undertaken. MCP-1 showed saturable binding to monocytes. Scatchard analysis of the monocyte binding data indicate that there are approximately 1,600 high affinity binding sites per monocyte with a Kd = 1.1 nM. Studies with synthetic peptides constructed according to the MCP-1 amino acid sequence indicate that a synthetic peptide, MCP-1[13-35], stimulates monocyte migration and competes with native MCP-1 for binding sites. Inhibition of MCP-1 binding was tested with chemotactic connective tissue proteins. No inhibition of MCP-1 binding was observed with either collagen, elastin-derived peptides or fibronectin. These results identify a single class of unique high affinity MCP-1 binding sites that are likely to recognize a peptide domain on MCP-1 which include the amino acids within the region, 13-35.

Animals↗

PubMed1991

Anti-Coxsackievirus B3 neutralizing antibodies with pathological potential.

Adolescent CD-1 mice inoculated with coxsackievirus B3 (CVB3m) will develop acute myocarditis with focal lesions by 7 days post-inoculation (p.i.). Administration of murine sera containing anti-CVB3m-neutralizing antibodies into CVB3m-inoculated mice at 3 days p.i. will exacerbate myocarditis, suggesting the presence of pathological antibodies. To study potential pro-inflammatory properties of virus-induced antibodies, a panel of anti-CVB3m-neutralizing monoclonal antibodies (mAbs) was generated. Several studies demonstrated shared epitopes between CVB3m particles and cultured murine cardiac or neonatal skin fibroblasts: (1) one or more mAbs bound to cultured cardiac fibroblasts; (2) several mAbs can participate in complement-mediated lysis of neonatal skin fibroblasts; and (3) at least one mAbs stimulated synthesis of a macrophage chemoattractant from cultured neonatal skin fibroblasts. Injection of one mAb in three doses, each of about 5 micrograms, into adolescent male CD-1 mice induced focal myocarditic lesions which were similar to CVB3m-induced lesions. One mAb induced a diffuse interstitial hypercellularity in most mice and two mAbs did not induce detectable cardiopathology. These data suggest that some anti-CVB3m neutralizing idiotypes (antibodies) which initially can provide protection via virus clearance mechanisms can also bind to cross-reacting epitopes on normal tissues. Binding of antibodies to normal heart tissues could stimulate proinflammatory reactions by several mechanisms and sustain myocarditis.

Animals↗

PubMed1991

Surgically induced endometriosis does not alter peritoneal factors in the rabbit model.

OBJECTIVE: It was the purpose of this study to examine the cause and effect relationship between alterations in peritoneal factors and the presence of ectopic endometrium in the rabbit model. DESIGN: Forty rabbits had autologous endometrial or omental (control) tissue surgically implanted. Peritoneal fluid (PF) volume, macrophage number, and macrophage activation, as well as the number of implants with adhesions, were compared with values obtained during the initial surgery. The effect of hormonal treatment on these factors was evaluated at a third laparotomy. RESULTS: There was a significant increase (P less than 0.05) of adhesions in animals with endometrial implants. Peritoneal fluid volume, macrophage number, or macrophage activation were not increased in rabbits with endometrial implants as compared with controls, nor was there a response to hormonal manipulation. CONCLUSIONS: These results demonstrate that PF volume, macrophage number, and macrophage activation are not altered by endometrial implants in the rabbit model. This suggests that the increase in these peritoneal factors in women with endometriosis may not be caused exclusively by the presence of ectopic endometrial tissue.

Analysis of Variance↗

PubMed1989

Pathophysiology of the atherogenic process.

Atherosclerosis is conceptually defined as the result of a multiplicity of interactive cascades among injurious stimuli and the healing responses of the arterial wall, occurring concurrently within a hyperlipidemic environment. In this discussion, the inflammatory nature of the disease is emphasized. Four aspects of the pathophysiology of atherogenesis are addressed: (1) The role(s) of fluid mechanical or hemodynamic stresses in the focal initiation and/or augmentation of lesions is discussed in terms of the influence of shear stress on endothelial cellular geometry, compliance, membrane anisotropy (r), low-density lipoprotein (LDL)-receptor expression, intracellular potential and replication; (2) mechanisms of blood monocyte recruitment to the arterial intima, including the roles of chemoattractants such as smooth muscle cell-derived chemotactic factor and oxidized LDL; (3) the alternate or "scavenger" receptor pathway of the macrophage and its pivotal roles in foam cell formation and plaque pathogenesis; and (4) the emerging significance of various lipoprotein modifications, and in particular, the oxidative modification of LDL, which facilitates the uptake of the cytotoxic oxidized LDL via the scavenger receptor, thus providing a non-down-regulating mechanism for foam cell formation and plaque development. Evidence indicates that the antioxidant drug probucol prevents the oxidative modification of LDL, thereby retarding atherogenesis independently of cholesterol reduction.

Animals↗

PubMed1988

Influence of the acyl-CoA: cholesterol O-acyltransferase inhibitor, CL 277082, on cholesteryl ester accumulation in rabbit macrophage-rich granulomas and hepatic tissue.

The influence of the acyl-CoA: cholesterol O-acyltransferase (ACAT) inhibitor, CL 277082, on macrophage cholesteryl ester accumulation in a rabbit carrageenan granuloma macrophage-foam cell model was studied. Diets were supplemented with 0.3% cholesterol and 6% peanut oil with or without the inhibitor (0.25%) for 4 weeks prior to granuloma induction, and macrophage-rich granuloma tissue was harvested 14 days after carrageenan injection. Serum cholesterol was monitored biweekly, and plasma lipoproteins were isolated terminally. Total, free and esterified cholesterol contents were measured in hepatic and granuloma tissue. In hepatic tissue, administration of CL 277082 resulted in an 80% reduction in the content of total cholesterol, a 37% decrease in free cholesterol, and a 90% decrease in esterified cholesterol. Similarly, in macrophage-rich granuloma tissue, total cholesterol content was decreased by 44%, and esterified cholesterol content by 61%, with no change in free cholesterol. Additionally, CL 277082 was shown to inhibit granuloma tissue ACAT activity by 45%, VLDL mass was decreased slightly, LDL mass increased 3.4-fold and HDL mass was similar in both the inhibitor-treated and control animals. CL 277082 resulted in a 57% decrease in VLDL cholesteryl ester content and a 4.5-fold increase in triacylglycerol. Cholesteryl ester content in LDL was decreased by 31% and LDL triacylglycerol was increased 5.2-fold, while the only change in HDL composition was a 3.5-fold increase in triacylglycerol. The reductions in both hepatic tissue and macrophage-rich granuloma tissue esterified cholesterol accumulation are considered to be due largely to cellular ACAT inhibition, and the altered distribution and composition of the plasma lipoproteins.

Animals↗

PubMed1988

Influence of hypercholesterolemia and cholesterol accumulation on rabbit carrageenan granuloma macrophage activation.

These experiments were designed to determine whether hypercholesterolemia and the accumulation of cholesterol or cholesteryl esters in rabbit carrageenan granuloma macrophages might influence selected markers of macrophage activation. Granulomas induced by subcutaneous injection of carrageenan into rabbits were harvested after 4, 14, and 28 days. Macrophages were isolated from granuloma tissues by collagenase digestion and cultured overnight. Secretion of lysosomal beta-glucuronidase, membrane 5'-nucleotidase, cellular plasminogen activator, and superoxide anion generation were measured as markers of activation. beta-Glucuronidase activity secreted into the media by granuloma macrophages from normocholesterolemic (NC) and hypercholesterolemic (HC) rabbits showed a trend toward an increase with time between 4 and 14 days in both groups. This was confirmed in a separate experiment with a significant increase by 14 days, together with a significantly greater secretion by NC macrophages and a significantly elevated level of cellular beta-glucuronidase activity in NC relative to HC macrophages. Activity of the membrane ectoenzyme 5'-nucleotidase was minimal in lysates of NC or HC macrophages, in contrast to freshly isolated human monocytes, indicating that both NC and HC granuloma macrophages were highly activated. Cellular plasminogen activator activity was significantly increased between 4 and 14 days, and was significantly greater in HC than in NC macrophages at 14 days. Stimulation of macrophages with phorbol myristate acetate increased superoxide anion generation by both NC and HC macrophages; however, no difference in superoxide anion generation was observed between macrophages from NC and HC rabbits. On the basis of the 5'-nucleotidase findings, it is concluded that both the NC and HC granuloma macrophages are highly activated, and further that hypercholesterolemia does not enhance macrophage generation of superoxide anion, either spontaneously or as the result of phorbol myristate acetate stimulation. Although hypercholesterolemia results in macrophage activation in terms of an increased cellular plasminogen activator activity, the secretion of the lysosomal enzyme beta-glucuronidase is diminished. Thus, hypercholesterolemia associated with macrophage cholesterol and cholesteryl ester accumulation has no consistent overall influence on activation, a finding of potential importance in the context of atherogenesis.

5'-Nucleotidase↗

PubMed1988

Activation of human peripheral blood monocytes by lipoproteins.

Activation of human peripheral blood monocytes could enhance their attachment and or migration into the arterial intima and their various secretory and other functions, thus influencing the pathogenesis of atherosclerosis. In these experiments the authors have explored the role of lipoproteins in the activation of human blood monocytes. Monocytes were purified from citrated blood by Histopaque density gradient centrifugation and countercurrent centrifugal elutriation and cultured in DMEM in the presence of 20% acid-treated autologous serum or 100 micrograms/ml each of VLDL, LDL, Ac-LDL, and HDL. Secretion of beta-glucuronidase activity into the media was measured as a marker of activation. All of the lipoprotein density classes as well as serum stimulated secretion of beta-glucuronidase activity, with LDL and Ac-LDL having a greater influence than serum, VLDL, or HDL. Serum and LDL also stimulated secretion of prostaglandin E into the culture medium. Incubation of monocytes with serum or LDL in the presence of inhibitors of arachidonate metabolism (NDGA and indomethacin) resulted in a significant decrease in secreted and intracellular beta-glucuronidase activity, indicating a role for products of arachidonate metabolism in the activation of monocytes by lipoproteins.

Arachidonic Acid↗