Biomedical subjects

R Voisard

Publications and source records attributed to R Voisard.

At least 19 recordsLinked to original sources

PubMed2006

Nicephor[e]: a web-based solution for teaching forensic and scientific photography.

Nicephor[e] is a project funded by "Swiss Virtual Campus" and aims at creating a distant or mixed web-based learning system in forensic and scientific photography and microscopy. The practical goal is to organize series of on-line modular courses corresponding to the educational requirements of undergraduate academic programs. Additionally, this program could be used in the context of continuing educational programs. The architecture of the project is designed to guarantee a high level of knowledge in forensic and scientific photographic techniques, and to have an easy content production and the ability to create a number of different courses sharing the same content. The e-learning system Nicephor[e] consists of three different parts. The first one is a repository of learning objects that gathers all theoretical subject matter of the project such as texts, animations, images, and films. This repository is a web content management system (Typo3) that permits creating, publishing, and administrating dynamic content via a web browser as well as storing it into a database. The flexibility of the system's architecture allows for an easy updating of the content to follow the development of photographic technology. The instructor of a course can decide which modular contents need to be included in the course, and in which order they will be accessed by students. All the modular courses are developed in a learning management system (WebCT or Moodle) that can deal with complex learning scenarios, content distribution, students, tests, and interaction with instructor. Each course has its own learning scenario based on the goals of the course and the student's profile. The content of each course is taken from the content management system. It is then structured in the learning management system according to the pedagogical goals defined by the instructor. The modular courses are created in a highly interactive setting and offer autoevaluating tests to the students. The last part of the system is a digital assets management system (Extensis Portfolio). The practical portion of each course is to produce images of different marks or objects. The collection of all this material produced, indexed by the students and corrected by the instructor is essential to the development of a knowledge base of photographic techniques applied to a specific forensic subject. It represents also an extensible collection of different marks from known sources obtained under various conditions. It allows to reuse these images for creating image-based case files.

Computer-Assisted Instruction↗

PubMed2001

Different effects of antisense RelA p65 and NF-kappaB1 p50 oligonucleotides on the nuclear factor-kappaB mediated expression of ICAM-1 in human coronary endothelial and smooth muscle cells.

BACKGROUND: Activation of nuclear factor-kappaB (NF-kappaB) is one of the key events in early atherosclerosis and restenosis. We hypothesized that tumor necrosis factor-alpha (TNF-alpha) induced and NF-kappaB mediated expression of intercellular adhesion molecule-1 (ICAM-1) can be inhibited by antisense RelA p65 and NF-kappaB1 p50 oligonucleotides (RelA p65 and NF-kappaB1 p50). RESULTS: Smooth muscle cells (SMC) from human coronary plaque material (HCPSMC, plaque material of 52 patients), SMC from the human coronary media (HCMSMC), human endothelial cells (EC) from umbilical veins (HUVEC), and human coronary EC (HCAEC) were successfully isolated (HCPSMC, HUVEC), identified and cultured (HCPSMC, HCMSMC, HUVEC, HCAEC). 12 hrs prior to TNF-alpha stimulus (20 ng/mL, 6 hrs) RelA p65 and NF-kappaB1 p50 (1, 2, 4, 10, 20, and 30 microM) and controls were added for a period of 18 hrs. In HUVEC and HCAEC there was a dose dependent inhibition of ICAM-1 expression after adding of both RelA p65 and NF-kappaB1 p50. No inhibitory effect was seen after incubation of HCMSMC with RelA p65 and NF-kappaB1 p50. A moderate inhibition of ICAM-1 expression was found after simultaneous addition of RelA p65 and NF-kappaB1 p50 to HCPSMC, no inhibitory effect was detected after individual addition of RelA p65 and NF-kappaB1 p50. CONCLUSIONS: The data point out that differences exist in the NF-kappaB mediated expression of ICAM-1 between EC and SMC. Experimental antisense strategies directed against RelA p65 and NF-kappaB1 p50 in early atherosclerosis and restenosis are promising in HCAEC but will be confronted with redundant pathways in HCMSMC and HCPSMC.

Journal Article↗

PubMed2001

Aspirin (5 mmol/L) inhibits leukocyte attack and triggered reactive cell proliferation in a 3D human coronary in vitro model.

BACKGROUND: Leukocyte attack (LA) and the triggered reactive proliferation of smooth muscle cells (SMCs) are key events for the development of early atherosclerosis and restenosis. In the present study, we used a 3D human coronary in vitro model of LA (3DLA model) to examine the effect of high-dose aspirin on the adhesion and chemotaxis of leukocytes and the reactive proliferative response of SMCs. METHODS AND RESULTS: For dose-finding, the effect of aspirin (1, 2, 5, and 10 mmol/L) on the tumor necrosis factor-alpha-induced upregulation of intercellular adhesion molecule-1 was analyzed in monocultures of human coronary endothelial cells (HCAEC) and the SMCs of the human coronary media (HCMSMC). In cytoflow and Northern blot experiments, the expression of intercellular adhesion molecule-1 was slightly reduced after incubation with 5 mmol/L aspirin, and strong inhibition was found after incubation with 10 mmol/L. In 3DLA models, HCAECs and HCMSMCs were cultured on both sides of a porous filter. For LA, human monocytes or CD4(+) lymphocytes were seeded on the HCAEC side of the 3DLA unit. A dose of 5 mmol/L aspirin inhibited the adherence of monocytes or CD4(+) lymphocytes by 50% (P:<0.01) and the chemotaxis of monocytes by 90% (P:<0.01). The reactive proliferative response of cocultured HCMSMCs after LA, as measured by the uptake of bromodeoxyuridine, was significantly reduced by 83% after selective monocyte attack (P:<0.001) and by 42% after selective CD4(+) lymphocyte attack (P:<0.05). CONCLUSIONS: A local concentration of 5 mmol/L aspirin should be accepted as the lowest rational concentration for the beneficial in vitro effects of high-dose aspirin to be reproduced in clinical studies.

Aspirin↗

PubMed2001

Leukocyte attack in a 3D human coronary in-vitro model.

OBJECTIVE: The importance of peripheral blood leukocytes for the development of early atherosclerosis and restenosis has confronted cardiologists with classical hematologic issues. Three-dimensional human coronary in-vitro units of leukocyte attack (3DLA-units) open the field for exact studies of leukocyte attack and its subsequent effects on human medial coronary smooth muscle cells (HCMSMC). METHODS: Central part of 3DLA-units are polycarbonate membranes with a pore size of 5 microm that correspond to the internal elastic membrane. Human coronary endothelial cells (HCAEC) were cultured on one side of the membranes, HCMSMC on the other side. Before leukocyte attack expression of adhesion molecules was up-regulated by tumour necrosis factor-alpha (TNF-alpha). Leukocyte attack was mimicked by selective adding of human monocytes (MC), respectively human CD4+-lymphocytes (CD4+-LC) to the HCAEC side of the 3DLA-units. Three-dimensional leukocyte attack units were fixed and stained after a period of 30 min, 1, 2, 3, 4, 6, and 24 h. Cell divisions of HCMSMC were analysed by measuring the uptake of bromodeoxyuridine (BrdU). RESULTS: Monocytes were able to adhere to the endothelial surface, pass through the filter-pores, and penetrate the HCMSMC side of the 3DLA-units. Human CD4+-lymphocytes (CD4+-LC) only attached to the HCAEC side, and no chemotaxis to the HCMSMC side was detected. Proliferation of HCMSMC was increased 2.9-fold (P< 0.001) after selective MC-attack and 3.5-fold after selective MC-attack and TNF-alpha stimulus. No significant increase was found after selective CD4+-LC attack, a significant increase (2.1-fold; P < 0.001) was seen after selective CD4+-LC attack and TNF-alpha, stimulus. CONCLUSIONS: Within the given limitations of the model the study emphasizes a predominance of MC in comparison to CD4+-LC in the process of adhesion, chemotaxis, and triggered reactive proliferation of co-cultured HCMSMC within the first 24 h after leukocyte attack. 3DLA-units offer an elegant method to study directly the effects of intravascular and intramural treatment strategies.

CD4-Positive T-Lymphocytes↗

PubMed2000

Intracoronary beta-irradiation with a liquid (188)re-filled balloon: six-month results from a clinical safety and feasibility study.

BACKGROUND: Coronary irradiation is a new concept to reduce restenosis. We evaluated the feasibility and safety of intracoronary irradiation with a balloon catheter filled with (188)Re, a liquid, high-energy beta-emitter. METHODS AND RESULTS: Irradiation with 15 Gy at 0.5-mm tissue depth was performed in 28 lesions after balloon dilation (n=9) or stenting (n=19). Lesions included 19 de novo stenoses, 4 occlusions, and 5 restenoses. Irradiation time was 515+/-199 seconds in 1 to 4 fractions. There were no procedural complications. One patient died of noncardiac causes at day 23. One asymptomatic patient refused 6-month angiography. Quantitative angiography after intervention showed a reference diameter of 2. 77+/-0.35 mm and a minimal lumen diameter of 2.36+/-0.43 mm. At 6-month follow-up, minimal lumen diameter was 1.45+/-0.88 mm (late loss index 0.57). Target lesion restenosis rate (>50% in diameter) was low (12%; 3 of 26). In addition, we observed 9 stenoses at the proximal or distal end of the irradiation zone, potentially caused by the short irradiation segment and the decreasing irradiation dose at its borders ("edge" stenoses). The total restenosis rate was 46% and was significantly lower (29% vs 70%, P=0.042) when the length of the irradiated segment was more than twice the lesion length. CONCLUSIONS: Coronary irradiation with a (188)Re-filled balloon is technically feasible and safe, requiring only standard percutaneous transluminal coronary angioplasty techniques. The target lesion restenosis rate was low. The observed edge stenoses appear to be avoidable by increasing the length of the irradiated segment.

Adolescent↗

PubMed2000

A statistical study of air bubbles on athletic shoesoles.

Comparisons of a shoemark with a shoesole (and standards) sometimes lead to associations based on air bubbles (among other manufacturing or acquired characteristics). Today, the assessment of the evidential value of air bubbles coincidences relies largely upon the examiner's experience and/or follows sometimes a verification based on the examination of a small number of analogous pairs collected for the case at hand. Statistical data related to the occurrence and characteristics of air bubbles on shoesoles in an attempt to model the potential variability have been gathered. Seventy-one pairs of shoes with the same design, brand, model and size were obtained. Right and left soles were photographed. An image-processing algorithm was developed to allow the systematic acquisition of data such as: (1) the number of air bubbles on the sole and around given structural elements; (2) the measure of air bubbles characteristics such as their surface and position. These data allow a discussion of the assessment of the probability of finding on shoesoles (same design, brand, model and size) a certain number of air bubbles on a surface with the same positions and morphology.

Air↗

PubMed2000

Different radiosensitivity of smooth muscle cells and endothelial cells in vitro as demonstrated by irradiation from a Re-188 filled balloon catheter.

There is an increasing interest in irradiation to control restenosis after balloon angioplasty by an internal radioactive source. Differences in radiosensitivity of the predominant cells of the human coronary artery (i.e. endothelial cells (HCAEC), smooth muscle cells from the media (HCMSMC) and from plaque material (HCPSMC), are issues of controversal discussion. Therefore, we investigated the graded inhibition of cells by irradiation from a balloon catheter filled with a high-energy beta-emitter (Rhenium-188) in vitro. HCPSMC, HCMSMC and HCAEC were cultured and irradiated with increasing dose from 7.5 to 37.5 Gy at a dose rate of 1.5+/-0.3 Gy/min. After irradiation, bromodeoxyuridine (BrdU) was added and cells were fixed 18 h later. In a limited field opposite to the balloon, the number of BrdU-positive cells were analysed in comparison to non-irradiated controls. Significant inhibition was demonstrated in HCPSMC and HCMSMC at 7.5 Gy while HCAEC needed 22.5 Gy for similar effects. The antiproliferative effect was dose dependent in all cell strains. The effect of irradiation with 22.5 Gy on smooth muscle alpha-actin, vimentin, and alpha-tubulin of HCPSMC and HCMSMC and on von Willebrand factor (vWF), vimentin, and alpha-tubulin of HCAEC was investigated by means of indirect immunofluorescence. Within 18 h after irradiation no effect on cytoskeletal components and vWF was documented. This in vitro study demonstrates that irradiation inhibits HCMSMC and HCPSMC at lower dose rates compared to HCAEC.

Catheterization↗

PubMed1999

A human arterial organ culture model of postangioplasty restenosis: results up to 56 days after ballooning.

BACKGROUND: Restenosis is a reparative process that is activated in response to injury induced by angioplasty. Despite numerous experimental models of restenosis the number of human arterial organ culture systems is very limited and long-term experiences do not exist. METHODS AND RESULTS: During routine nephrectomies parts of the renal arteries of 88 patients were extracted, 47 were suitable for organ culture preparations. Sections were made at 3 mm intervals perpendicular to the vessel wall axis. The arterial segments were treated with 3 mm standard balloon-catheters (Medtronic 14K2030E) for 60 s with 3, 6, 9, and 12 bar. After angioplasty, the organ segments were cultured in a mixture of Waymouth's MB 752/1 and Ham F-12, supplemented with 15% fetal calf serum. After 0, 4, 14, 21, 28, and 56 days the organ cultures were fixed in 4% para-formaldehyde and embedded in paraffin. After staining with a modified elastica-van Gieson technique the intimal wall thickening was analyzed with a computerized morphometric system. For the identification of smooth muscle cells (SMC) a monoclonal antibody against smooth muscle alpha-actin was used. Endothelial cells were identified using an anti-human von Willebrand factor. To determine the number of cells undergoing DNA synthesis, bromodeoxyuridine (BrdU), a thymidine analogue, was added to the culture media 18 h prior to fixation. BrdU was detected with a monoclonal antibody, as secondary antibody a biotinylated horse-anti-mouse antibody was used. After 14, 21, and 28 days in culture BrdU-positive cells were detected in the neointima of the organ cultures, indicating mitotic activity in this area. After 28 and 56 days in culture a clear increase of neointimal thickening was found in the morphometric analysis. By positive reaction with antibodies against smooth muscle alpha-actin these cells were partly identified as SMC. CONCLUSIONS: The organ culture model offers opportunities for in vitro investigations of postangioplasty restenosis. The data emphasize the importance of a relatively late proliferative response of SMC in the human arterial organ culture model.

Adult↗

PubMed1999

Altered expression of extracellular matrix in human-cytomegalovirus-infected cells and a human artery organ culture model to study its biological relevance.

The influence of human cytomegalovirus (HCMV) on the transcription of 11 selected, representative extracellular matrix genes was investigated in cell culture. Northern blot hybridization indicated the downregulation of all mRNAs investigated. Based on our results and the known repression of other extracellular matrix transcripts and the beta-actin transcription during HCMV infection, we suggest that one molecular mechanism contributing to the cytopathic effect may be the transcriptional downregulation of genes encoding proteins involved in cell structure and intercellular connection. To further study the biological relevance of this and other pathogenetic mechanisms, we established a human renal artery organ culture system and characterized this new infection model for HCMV. Our model is a new suitable system for the investigation of molecular as well as functional consequences of HCMV infection in a more physiological microenvironment.

Cells, Cultured↗

PubMed1998

Modulation of Ca2+-activated K+ channels in human vascular cells by insulin and basic fibroblast growth factor.

Insulin and basic fibroblast growth factor (bFGF) play an important role in the pathogenesis of atherosclerosis and have been shown to have vasodilatory effects. Since modulation of vascular ion channels determines membrane potential and thereby influences essential Ca2+-dependent intracellular pathways, we have investigated the effect of insulin and bFGF on Ca2+-activated K+ channels (BKCa) in human umbilical vein endothelial cells (HUVEC) and smooth muscle cells. The latter were obtained from either atherosclerotic plaques (SMCP) or from media segments (SMCM) of human coronary arteries. Using the patch-clamp technique, insulin (100 microU/ml) caused a significant increase in BKCa open-state probability in SMCP and HUVEC, whereas no significant changes were observed in SMCM. Basic FGF (30 ng/ml) revealed a significant increase in BKCa activity in HUVEC and a significant decrease in the BKCa open-state probability in SMCP, but caused no changes in SMCM. Thus, growth factors modulate vascular BKCa in a cell-type specific manner, which may be of importance concerning vasoactive and atherogenic effects of growth factors.

Arteriosclerosis↗

PubMed1998

Effect of diltiazem and verapamil on endothelin release by cultured human coronary smooth-muscle cells and endothelial cells.

Recent data suggest that endothelin (ET) production is enhanced in coronary atherosclerotic lesions. In several studies, an anti-atherosclerotic effect has been attributed to calcium-channel antagonists. This study aimed to investigate whether ET release from cultured human coronary artery smooth muscle and endothelial cells is influenced by the calcium-channel antagonists diltiazem and verapamil. Coronary plaque smooth-muscle cells (SMCs) were isolated from primary stenosis plaque material. Normal coronary smooth muscle and endothelial cells were obtained from organ donors. Addition of diltiazem (5, 15, 25, 50, or 100 micrograms/ml) and verapamil (0.25, 2.5, 25, 50, or 75 micrograms/ml) to the culture medium induced in all three cell types a dose-dependent reduction in ET secretion (coronary plaque SMCs: diltiazem 98.1 +/- 1.5, 94.9 +/- 5.0, 82.0 +/- 6.4**, 63.3 +/- 3.7***, 38.9 +/- 2.4***; control 108.4 +/- 2.8; verapamil 97.0 +/- 7.7, 91.9 +/- 5.5, 67.3 +/- 4.5**, 30.6 +/- 3.0***, 27.6 +/- 2.2***; control 103.4 +/- 6.1 pg/10(4) cells, n = 6; normal coronary SMCs: diltiazem 9.6 +/- 0.7, 8.7 +/- 0.6, 5.4 +/- 0.5***; 3.7 +/- 0.5***, 3.2 +/- 0.4***; control 10.7 +/- 0.5; verapamil 10.3 +/- 0.9, 10.0 +/- 0.7, 6.6 +/- 0.5***, 4.0 +/- 0.3***, 3.0 +/- 0.3***; control 11.1 +/- 0.6 pg/10(4) cells, n = 6; means +/- SEM, **p < 0.01, ***p < 0.001 vs. control). These data suggest that ET release from cultured coronary smooth muscle and endothelial cells is decreased by diltiazem and verapamil. In further studies, it remains to be elucidated whether the local application of diltiazem or verapamil might have a beneficial effect on the progression of coronary atherosclerosis.

Aged↗

PubMed1998

Expression of intercellular adhesion molecule-1 in human coronary endothelial and smooth muscle cells after stimulation with tumor necrosis factor-alpha.

BACKGROUND: The intercellular adhesion molecule-1 (ICAM-1) is one of several human cell adhesion molecules that play a critical role in the early stages of postangioplasty restenosis. In this study, the in-vitro expression of ICAM-1 in human coronary endothelial cells and human coronary smooth muscle cells (SMC) after stimulation with tumor necrosis factor-alpha (TNF-alpha) was investigated. METHODS AND RESULTS: SMC were isolated from the media of normal human coronary arteries (n = 26) up to 10 h post mortem (HCMSMC) and from human atherosclerotic coronary arteries (HCPSMC) that were extracted by thrombendarterectomy (n = 25). Endothelial cells of human coronary arteries (HCAEC) were purchased from Clonetics (Cell System, Remagen, Germany), and endothelial cells from human umbilical cord veins (HUVEC) were isolated after vaginal delivery. For investigations of the effect of TNF-alpha (2.5, 5, 10, and 20 ng/ml) on the proliferative activity of HUVEC, HCAEC, HCPSMC, and HCMSMC, serum-free media was used. After 24 h cell number and cell size distribution were measured in a cell analyzer system. The proliferation of HCPSMC and HCMSMC was increased by TNF-alpha; however, significant differences compared with controls were not reached. The proliferation of HUVEC and HCAEC was significantly reduced by TNF-alpha. For investigations of the effect of TNF-alpha (2.5, 5, 10, and 20 ng/ml) on the surface expression of ICAM-1, monoclonal anti-ICAM-1 antibodies (84H10) were used. The expression of ICAM-1 was analyzed using an immunofluorescence microscope. For flow cytometry analysis, 5 x 10(3) cells (100% gated) were analyzed using a fluorescence-activated cell sorter. In control cultures with no stimulation, the expression of ICAM-1 was positive in HCAEC, HCPSMC, HCMSMC, and HUVEC. TNF-alpha stimulated the expression of ICAM-1 in a time- and dose-dependent manner. After maximal stimulation with TNF-alpha (20 ng/ml for 24 h), the expression of ICAM-1 was stronger in HCMSMC than in HCPSMC. CONCLUSIONS: These results suggest that the cytokine TNF-alpha regulates the expression of ICAM-1 in both human coronary endothelial cells and SMC, and could therefore play an important role in the pathophysiology of inflammatory and immune processes in restenosis after angioplasty.

Cell Division↗

PubMed1998

Effect of the antioxidant Nicanartine on the proliferative and inflammatory response after experimental balloon angioplasty.

BACKGROUND: Antioxidant treatment seems to reduce the development of restenosis after percutaneous transluminal angioplasty. In this study, the effect of Nicanartine, a new antioxidant drug with both antiproliferative and lipid-lowering properties, on the proliferative and inflammatory response after balloon angioplasty was investigated in a rabbit model of restenosis. METHODS: To induce pre-interventional plaques in the common carotid artery of 48 New Zealand White rabbits, electrostimulation was carried out for 28 days. After a break of 7 days, balloon angioplasty was performed in 36 animals, of which 18 received Nicanartine at a dose of 120 mg/kg body weight; the other 18 served as a control group. The vessels were excised by day 7 and 28 after balloon angioplasty and examined for intimal plaque size, macrophage content and proliferative activity. Bromodeoxyuridine labeling was used to determine proliferating cells in the dilated segment; macrophages were detected using the RAM-11 antibody. RESULTS: In the Nicanartine-treated group, immunohistological quantification 7 days after intervention showed a statistically significant (P< 0.05) reduction of both cells undergoing DNA synthesis (1.6+/-1.4% versus 3.7+/-2.2%) and intimal macrophages (0.7+/-1.2% versus 1.3+/-0.6%). Twenty-eight days after balloon angioplasty, proliferative activity in both groups was decreased to a level comparable to the non-dilated control groups. A clear trend towards smaller plaques could be seen in the Nicanartine group (0.146+/-0.077 mm2 versus 0.255+/-0.174 mm2). Total cholesterol levels did not differ significantly between the groups. CONCLUSION: Under treatment with Nicanartine a clear reduction in the proliferative and inflammatory response after balloon angioplasty was observed. Antioxidant treatment, especially with compounds having antiproliferative and lipid-lowering properties, appears to be an effective secondary preventive strategy after interventional treatment in patients with coronary artery disease.

Angioplasty, Balloon↗

PubMed1997

Ca(2+)-activated K+ channels in human smooth muscle cells of coronary atherosclerotic plaques and coronary media segments.

The behavior of Ca(2+)-activated K+ channels of large conductance (BKCa) in smooth muscle cells, which were obtained from atherosclerotic plaque material (SMCP) and from media segments (SMCM) of human coronary arteries, were compared using the patch-clamp technique. Voltage-clamp protocols in cell-attached patches revealed the characteristic voltage-dependent activation of BKCa in both cell groups. Single-channel conduction as 216.4 +/- 16.7 pS (n = 6) in SMCP and 199.9 +/- 6.7 pS (n = 6) in SMCM in symmetrical 140 mM K+ solutions. Using outside-out patches, external perfusion with 500 microM tetraethylammonium ions caused a typical "flickery block" of the unitary current. The selective BKCa channel inhibitor iberiotoxin (50 nM) effectively blocked BKCa, channel activity. Comparing BKCa open-state probabilities (P0) at +80 mV in cell-attached patches, a highly significant difference between SMCP (P0 = 0.1438 +/- 0.1301; n = 15) and SMCM (P0 = 0.0093 +/- 0.0044; n = 15; Kruskal-Wallis test, p < 0.001) was found. In contrast to this finding, there was no significant difference in the open-state probability of BKCa, between SMCP (P0 = 0.542 +/- 0.0237; n = 9) and SMCM (P0 = 0.0472 +/- 0.0218; n = 10; p = n.s.) using inside-out patches. The results show an interesting difference in the behavior of large conductance Ca(2+)-activated K+ channel in SMCP compared to SMCM with a significantly higher channel activity in human smooth muscle cells obtained from coronary atherosclerotic plaque material. This finding may indicate an important functional role of BKCa channels in the development of atherosclerosis.

Calcium↗

PubMed1996

Increased endothelin release by cultured human smooth muscle cells from atherosclerotic coronary arteries.

OBJECTIVES: Endothelin, a 21-amino acid peptide initially purified from the medium of cultured endothelial cells, is a potent vasoconstrictor exerting its effects predominantly in a paracrine or autocrine manner. Recent data indicate that endothelin is also synthesized by cultured vascular smooth muscle cells and that endothelin is an effective stimulator of smooth muscle cell proliferation. This study aimed to investigate the endothelin release of cultured human smooth muscle cells, isolated from coronary plaques and from normal coronary tunica media, and to determine circulating endothelin concentrations in patients with coronary artery disease compared to control subjects. METHODS: Coronary plaque material was extracted by thrombendarterectomy during aorto-coronary bypass grafting (n = 19). Segments of normal coronary arteries were obtained at autopsy (n = 33). Cells were isolated by enzymatic disaggregation and identified as smooth muscle cells with antibodies against smooth muscle alpha-actin. Venous blood samples were drawn from patients with coronary artery disease undergoing cardiac catheterization (n = 32) and from control subjects (n = 38). Endothelin concentrations in culture medium and in plasma samples were measured by radioimmunoassay after Sep Pak C18 extraction. RESULTS: Cultured smooth muscle cells, isolated from coronary plaques, released a significantly (P < 0.001) higher amount of immunoreactive endothelin into the culture medium (39.2 +/- 3.9 pg/10(4) cells, mean +/- s.e.m., 31 supernatant samples) than smooth muscle cells from normal coronary tunica media (3.9 +/- 0.8 pg/10(4) cells, 28 samples). Circulating endothelin concentrations were slightly elevated (P < 0.01) in patients with coronary artery disease (3.8 +/- 0.2 pg/ml) compared to control subjects (3.0 +/- 0.2 pg/ml). CONCLUSIONS: These data suggest that the endothelin production is markedly increased in smooth muscle cells of coronary atherosclerotic plaques. The enhanced endothelin release may stimulate smooth muscle cell proliferation in a paracrine or autocrine manner and thus may contribute to the development or progression of coronary artery disease.

Cells, Cultured↗

PubMed1995

A prescreening system for potential antiproliferative agents: implications for local treatment strategies of postangioplasty restenosis.

BACKGROUND: Recent advances in the understanding of the biology of restenosis indicate that it is predominantly caused by a multifactorial stimulation of smooth muscle cell proliferation. The aim of this study was to investigate the in vitro effect of five potential antiproliferative agents on smooth muscle cells from human atherosclerotic femoral arteries. METHODS AND RESULTS: Primary stenosing plaque material of 24 patients (aged 63 +/- 14 years) and restenosing plaque material of 7 patients (aged 65 +/- 9 years) was selectively extracted from femoral arteries by the Simpson atherectomy device. Cells were isolated by enzymatic disaggregation and identified as smooth muscle cells by positive reaction with smooth muscle alpha-actin. Dalteparin sodium (0.001-100 anti-Xa units/ml), cyclosporine A (0.005-500 micrograms/ml), colchicine (0.00004-4 pg/ml), etoposide (0.002-200 micrograms/ml), and doxorubicin (0.0005-50 micrograms/ml) were added to the cultures. Six days after seeding, cells were trypsinized and cell number was measured by a cell counter. All five agents tested exhibited a significant inhibition of smooth muscle cell proliferation (P < 0.001). After an incubation time of 48 h, the cytoskeletal components, alpha-actin, vimentin, and microtubules were investigated. At peak concentrations, all five tested agents except dalteparin sodium caused severe damage to the cytoskeleton. CONCLUSIONS: All five potential antiproliferative agents exhibited a significant inhibition of smooth muscle cell proliferation. The development of new intravascular delivery systems may open the way for local antiproliferative treatment strategies in interventional cardiology.

Actins↗

PubMed1995

A coronary porcine organ culture system for studies of postangioplasty cell proliferation.

BACKGROUND: Restenosis after angioplasty is generally considered to be caused mainly by an increased proliferation of smooth muscle cells, but recently this theory has been questioned. METHODS: Fresh hearts of 25 pigs were obtained and the left anterior descending coronary arteries carefully prepared, cut into segments and treated with a 3 mm standard balloon catheter for 60 s with 3, 6, 9 and 12 bar. Immediately after angioplasty the specimens were cultured in a mixture of WM/F-12, supplemented with 15% fetal calf serum. RESULTS: After staining with a modified Verhoeff-van Gieson technique, intimal wall thickening was analysed with a computerized morphometric system. After 14 days in culture, angioplasty with 6, 9 and 12 bar resulted in a significant (P < 0.05) increase of neointimal thickening. After 21 days, a significant increase of neointimal thickening was seen after ballooning with 3, 9 or 12 bar (P < 0.05). After 28 days angioplasty with 3 or 6 bar showed a dose-dependent increase of neointima, which was not further increased after ballooning with 9 or 12 bar. Significance was reached after ballooning with 6, 9 and 12 bar (P < 0.05). Smooth muscle cells were identified with a monoclonal antibody against smooth muscle alpha-actin. Endothelial cells were identified using an anti-human von Willebrand factor. To determine the number of cells undergoing DNA synthesis, bromodeoxyuridine, a thymidine analogue, was added to the culture media 18 h before fixation. It was detected with a monoclonal antibody, with a biotinylated horse-anti-mouse antibody as secondary antibody. After 4 and 7 days in culture bromodeoxyuridine-positive cells were observed, indicating an early proliferative response after angioplasty. CONCLUSIONS: The coronary organ culture model offers opportunities for investigations of complex cellular events that are considered important in the development of restenosis. The data reported emphasize the importance of an early proliferative response of smooth muscle cells after coronary angioplasty, resulting in a significant neointimal thickening.

Angioplasty, Balloon↗

PubMed1995

[Recurrent stenosis following coronary angioplasty. Clinical, cell biological and molecular aspects].

Percutaneous transluminal coronary angioplasty by balloon dilatation (PTCA) has proved to be the standard procedure for non-operative removal of coronary artery stenoses. Since the initial description and application by Andreas Grüntzig, the results of this procedure are excellent with an acute success rate of 90-96%, a rate of severe acute complications of 1% and less, and a procedure-related death rate below 1%, mainly due to considerable technical improvements and greater experience of the interventional cardiologists. On the other hand, the restenosis rate following PTCA could not be significantly lowered. In recent years a number of alternative angioplasty devices has been developed aimed at-among other indications-reducing the restenosis rate following PTCA by a "less traumatic" vessel angioplasty. These include radiofrequency angioplasty (RFCA), high frequency rotational angioplasty (HFRCA), excimer-laser angioplasty (ELCA), directional atherectomy (DCA), as well as implantation of intravascular stents. Based on more or less extensive experiences from the literature, the aim at lowering the recurrency rate by the latter procedures has been missed, despite the fact that particularly ELCA and HFRCA were used to reduce stenoses in lesions unsuitable for balloon catheter dilatation. There is a trend of lowering the recurrence rate with the implantation of coronary stents. The benefit of this procedure, however, is at the expense of an increased rate of acute stent thrombosis and by local acute bleeding problems quite often requiring surgical repair. The cellular biological mechanisms following balloon angioplasty are only partially understood. Among these are a number of interactive processes like cell adhesion, coagulation, vascular contraction, cell migration, cell proliferation, and synthesis of extracellular matrix. In this respect, migration and proliferation of smooth muscle cells represent a key process for the development of restenosis. In addition, endothelial denudation represents a stimulus for migration and proliferation of smooth muscle cells. Rapid and efficient reendothelialization may counteract this process. Recent progress of modern biology has provided new concepts and methodological tools for the molecular analysis of vascular remodeling. It has been shown that specialized cellular functions such as proliferation, migration, and production of extracellular matrix can be mediated by growth factors such as platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF) or transforming growth factor-beta (TGF-beta).(ABSTRACT TRUNCATED AT 400 WORDS)

Angioplasty, Balloon, Coronary↗