Search PubMed⌕ Search

Biomedical subjects

R Voisard

Publications and source records attributed to R Voisard.

35 records · Page 2Linked to original sources
PubMed1995

Cyclosporine A stimulates endothelin release.

Administration of cyclosporine A is often associated with the development of renal dysfunction and hypertension. Because recent data provide evidence that endothelin (ET) might be involved in mediating cyclosporine-associated cardiovascular and renal side effects, the present study aimed to investigate the influence of cyclosporine A on ET release from cultured smooth-muscle cells and whether ET plasma concentrations are elevated in cyclosporine-treated patients. Addition of cyclosporine A to the medium of cultured human smooth-muscle cells, isolated from atherosclerotic iliac arteries, induced a dose-dependent increase in ET release. ET plasma levels were significantly elevated in cyclosporine-treated patients after bone marrow transplantation, compared to control groups. These data suggest that enhanced ET release might be involved in mediating the cyclosporine-associated side effects.

Cells, Cultured↗
PubMed1994

Corticosteroid agents inhibit proliferation of smooth muscle cells from human atherosclerotic arteries in vitro.

We studied the in vitro effect of steroid agents on smooth muscle cells from human atherosclerotic arteries. Recent advances in the understanding of the biology of restenosis indicate that restenosis is predominantly caused by a multifactorial stimulation of smooth muscle cell proliferation. 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. The steroid agents prednisolone (0.0075-750 micrograms/ml), hydrocortisone (0.0125-1250 micrograms/ml), and dexamethasone (0.0004-40 micrograms/ml) were added to the cultures. Six days after seeding the cells were trypsinized and the cell number was measured by a cell counter. All three steroid agents exhibited a significant antiproliferative effect on smooth muscle cell proliferation. At high concentrations of hydrocortisone, cytoskeletal elements of smooth muscle cells such as actin, microtubules, and vimentin, were largely altered. Our data indicate that the proliferation of smooth muscle cells from human atherosclerotic arteries in vitro can be inhibited by steroid agents and thus may open the way for local post-angioplasty treatment strategies.

Actins↗
PubMed1993

The in-vitro effect of antineoplastic agents on proliferative activity and cytoskeletal components of plaque-derived smooth-muscle cells from human coronary arteries.

BACKGROUND: Restenosis after successful percutaneous transluminal coronary angioplasty remains the major clinical problem limiting the long-term efficacy of the treatment. Recent advances in the understanding of the biology of restenosis indicate that its cause is predominantly a multifactorial stimulation of smooth-muscle cell proliferation. The aim of this study was to investigate the in-vitro effect of antineoplastic agents on smooth-muscle cells isolated from human coronary plaque material. METHODS: Atherosclerotic tissue from coronary arteries was extracted from 15 patients of both sexes by thrombendarterectomy. Cells were isolated using enzymatic disaggregation and identified to be smooth-muscle cells with fluorescent antibodies for smooth-muscle-specific alpha-actin. The antineoplastic agents cytarabine (500-0.005 micrograms/ml), doxorubicin (50-0.0005 micrograms/ml), and vincristine (10-0.0001 micrograms/ml) were added to the cultures. Six days after seeding, the cells were trypsinized and then counted. RESULTS: All three antineoplastic agents had a strong dose-dependent antiproliferative effect on cultured smooth-muscle cells. After the application of cytostatic agents, cells either became rounded or underwent complete lysis. Cytoskeletal elements, such as actin, microtubules, and vimentin, were largely altered. CONCLUSION: This investigation examined the potential role of antineoplastic therapy in the prevention of restenosis after coronary angioplasty. The development of new intravascular delivery systems, such as coated stents, may open the way for local antiproliferative strategies in interventional cardiology.

Aged↗
PubMed1991

[In vitro balloon treatment of coronary plaque material of the human: effect of dilation time on proliferation of smooth muscle cells].

The proliferation of smooth muscle cells (SMC) seems to be an important factor in the development of restenosing events after angioplasty. Primary stenosing plaque material was obtained from human coronary arteries by thrombendarterectomy. Specimens were cut in small pieces and dilated in a flexible tube with a balloon-catheter (Medtronic 18K2030E) for 1 min., 5 min. and 10 min. at 3 atm. For the isolation of plaque cells the expant technique was used. The majority of plaque cells was identified as smooth muscle cells by positive reaction with monoclonal antibodies against smooth muscle alpha-actin. For the cultivation of SMC a mixture of Waymouth's MB 752/1 and Ham F-12 (1:1) was used. After 8 weeks cell number was analysed by a cell counter (Casy I, Schärfe System). There was a clear increase of SMC-proliferation in dependence to the duration of angioplasty (1 min. = 100%, 5 min. = 112%, 10 min. = 153%). If these data are confirmed by clinical and experimental studies, the duration of angioplasty has to be considered as a risc factor for the development of restenosis.

Angioplasty, Balloon, Coronary↗
PubMed1991

[Restenosed growth of plaque cells from restenosed peripheral and coronary plaque material of the human in vitro: a correlation to animal experiment results following angioplasty].

In this study cells were isolated from primary-stenosing and re-stenosing tissue of human peripheral (extraction by Prof. Höfling and Dr. Bauriedel, Munich) and coronary arteries. The vast majority of plaque cells was identified as smooth muscle cells (SMC) by positive reaction with monoclonal antibodies against smooth muscle alpha-Actin. All SMC consisted of two different subpopulations, which were discriminated by different cell diameters: Relatively small cells (diameter: 18.0 +/- 4 microns, mean +/- SD) and large cells (diameter: 26.0 +/- 3 microms, mean +/- SD). Population doublings per day (PD/day) for SMC from re-stenosing lesions were significantly increased (0.60 +/- 0.13 PD/day, mean +/- SD) in comparison to SMC from primary-stenosing lesions (0.15 +/- 0.04 PD/day, mean +/- SD), p much less than 0.001). Thus, the increased growth of SMC from restenosing lesions in vitro might be the equivalent to the rapid progression of restenosing events after angioplasty in vivo. These results are in accordance with data from experimental studies after angioplasty.

Aged↗
PubMed1991

[Cell culture as a prescreening system for drug prevention of restenosis?].

Migration and proliferation of smooth muscle cells (SMC) from the media into the subendothelial space are important steps in the development of restenosing events after angioplasty; therefore a medical inhibition of this activity seems to be of clinical interest. Primary stenosing plaque material of 20 patients and restenosing plaque material of 6 patients was removed by atherectomy (Prof. Höfling, Dr. Bauriedel, Munich). For the isolation of plaque cells a mixture of Collagenase/Elastase was used. The vast majority of plaque cells was identified as smooth muscle cells by positive reaction with monoclonal antibodies against smooth muscle alpha-Actin. Propranolol (10(-4) mol/l to 10(-9) mol/l), Prednisolone (10(-3) mol/l to 10(-8) mol/l) and Etoposide (10(-4) mol/l to 10(-9) mol/l) were added to the cultures one day after seeding. After 3 days cell number and cell size distribution were analysed in a cell counter (Casy I, Schärfe System, Reutlingen). While Propranolol didn't change proliferative activity of SMC, Prednisolone caused a slight, but dose dependent inhibition of SMC-proliferation. Etoposid inhibited SMC-proliferation even below clinical concentrations to 50%. The local application of steroid or cytostatic agents might improve long term results after angioplasty. The clinical relevance of this 'Prescreening System' has to be evaluated by experimental and clinical studies.

Angioplasty, Balloon↗
PubMed1990

In vitro growth characteristics of human atherosclerotic plaque cells: comparison of cells from primary stenosing and restenosing lesions of peripheral and coronary arteries.

Cell size distribution and growth rates were studied in vitro in human plaque cells from advanced primary stenosing and fresh restenosing lesions of peripheral and coronary arteries. Cells were isolated either by the explant technique or by enzymatic disaggregation and were identified as smooth muscle cells by their typical growth pattern and their positive reaction with antibodies against smooth muscle alpha-actin. Endothelial cells were found in plaque specimens from coronary arteries but were only present in primary cultures. Smooth muscle cells from primary stenosing tissue (ps-SMC) exhibited a significantly lower growth rate in culture (0.15 +/- 0.04 population doublings per day; means +/- SD) compared with cells from restenosing lesions (re-SMC; 0.60 +/- 0.13 population doublings per day; means +/- SD). ps-SMC usually became senescent in their second passage, i.e., after 5-7 cumultive population doublings. re-SMC retained their high proliferative activity even after five passages (15 cumulative population doublings). Cell populations of both origins consisted of two distinct subpopulations which could be discriminated by cell size measurements: relatively small, predominant cells (cell diameter: 18.0 +/- 4 microns; means +/- SD) and large fibroblast-like cells (cell diameter: 26.0 +/- 3 microns; means +/- SD). The proportion of large cells was higher in cell populations derived from primary stenosing tissue. These results suggest that stenosing plaque tissue from human peripheral and coronary arteries consists of two smooth muscle cell subpopulations. The low proliferative activity of total smooth muscle cell populations of advanced primary stenosing lesions contrasts with the high mitotic activity of smooth muscle cells obtained from secondary stenosing intimal proliferates.

Aged↗
PubMedDate not supplied

Selective percutaneous "biopsy" of atheromatous plaque tissue for cell culture.

The combination of percutaneous atherectomy and angioscopy enabled a selective "biopsy" of protruding atheromatous plaque material from 11 patients with arterial occlusive disease. The removed specimens were cultivated as adhering explants or single cells were obtained by enzymatic disintegration. The vast majority of the cultivated cells resembled fibroblasts, but could be identified as smooth muscle cells by their smooth muscle alpha-actin content. Proliferation rate was slow with 0.1 doublings per day. Endothelial cells were not observed by immunologic criteria. The described biopsy technique and in vitro evaluation of cultured human atheromatous plaque material may be useful for a better understanding of atherogenesis.

Actins↗
PubMedDate not supplied

High-dose diltiazem prevents migration and proliferation of vascular smooth muscle cells in various in-vitro models of human coronary restenosis.

BACKGROUND: Restenosis after coronary angioplasty is considered to be caused mainly by increased migration and proliferation of smooth muscle cells (SMC). The concept of local, site-specific delivery of pharmacologic therapies has opened the door for new, high-dose drug regimes. METHODS AND RESULTS: SMC were isolated by enzymatic disaggregation with collagenase/elastase from human coronary plaque tissue of 29 patients (pSMC) and post mortem from the coronary media of 33 corpses (mSMC). Endothelial cells were isolated from human umbilical veins by enzymatic disaggregation with collagenase/dispase. By positive reaction with antibodies against smooth muscle alpha-actin and von Willebrand factor cells were identified as SMC or endothelial cells. In proliferation studies 5-150 micrograms/ml diltiazem was added to the culture media of pSMC, mSMC and endothelial cells. After 5 days there was a significant dose-dependent inhibition of cell proliferation (for pSMC with > 50 micrograms/ml, for mSMC with > 25 micrograms/ml, and for endothelial cells with > 5 micrograms/ml). In migration studies the effect of 5-150 micrograms/ml diltiazem on the velocity of migration of pSMC was investigated over a period of 48 h. Administration of diltiazem at concentrations of 100 and 150 micrograms/ml caused a significant inhibition of the migration of pSMC. The cytoskeletal components smooth muscle alpha-actin, vimentin, and alpha-tubulin of pSMC and the expression of von Willebrand factor of endothelial cells were investigated after an incubation period of 5 days with 50 and 150 micrograms/ml diltiazem. In the transfilter coculture model the effect of 50 micrograms/ml diltiazem on mSMC was investigated after mechanical injury of cocultured endothelial cells. Administration of diltiazem at a concentration of 50 micrograms/ml inhibited the development of a neointimal proliferate in the transfilter coculture model significantly (P < 0.001). CONCLUSIONS: A high dose of diltiazem inhibited the migratory and proliferative activities of coronary SMC significantly. In further experimental studies the effect of locally applied high doses of diltiazem on postangioplasty restenosis should be elucidated.

Actins↗
PubMedDate not supplied

Growth characteristics and cytoskeletal organization of cultured smooth muscle cells from human primary stenosing and restenosing lesions.

Growth characteristics of human plaque cells selectively extracted from advanced primary stenosing and fresh restenosing lesions by percutaneous transluminal atherectomy were studied in vitro. Cells were isolated either by explant technique or by enzymatic disaggregation, and they were identified as smooth muscle cells (SMC) by positive reaction with antibodies against alpha-smooth muscle actin. Endothelial cells were not found in the atherectomized tissue. The cells of primary stenosing tissue (ps-SMC) exhibited a significantly low growth rate (0.16 +/- 0.04 population doublings per day) in comparison to the cells of restenosing lesions (re-SMC, 0.64 +/- 0.15 population doublings per day). Furthermore, ps-SMC became senescent and remained quiescent after two passages, whereas re-SMC retained a high proliferative activity and became quiescent by passage 8 to 10. Both types of cells responded to increasing serum concentrations in a dose-dependent manner. Ps-SMC failed to respond to purified platelet-derived growth factor (PDGF) and a mitogen mixture isolated from bovine brain (ECGF), but their proliferative activity was increased by the addition of re-SMC-conditioned culture medium. Despite their high basic growth rate, the proliferative activity of re-SMC was significantly stimulated by PDGF and ECGF in a dose-dependent manner. PS-SMC and re-SMC populations consisted of two distinct subpopulations, which could be discriminated by cell size measurements and cell adhesion: 1) relatively small (cell diameter, 18.6 +/- 5 microns), low-adhesive, predominant cells, and 2) enlarged (cell diameter, 27.1 +/- 3 microns), high-adhesive, fibroblast-like cells with abundant microfilaments. Neither ps-SMC or re-SMC stained with antibodies against desmin, but did express vimentin. The organization patterns of vimentin and tubulin were unaltered in comparison to each other and to smooth muscle cells cultured from the media of nonatherosclerotic human arteries.

Arteriosclerosis↗
PubMedDate not supplied

Estradiol concentrations in premenopausal women with coronary heart disease.

BACKGROUND: Because of the beneficial effects of estrogen, premenopausal women are normally protected against coronary heart disease (CHD) and are at lower risk for myocardial infarction; consequently, CHD occurs very rarely in menstrually active women. Given this background, the aim of the present study was to test the hypothesis that decreased concentrations of estrogen are associated with CHD in premenopausal women. METHODS: Fourteen premenopausal women with CHD were investigated and compared with a healthy control group comparable for age and cardiovascular risk factors. Relevant characteristics of patients and controls were assessed: age, blood pressure, body mass index, total cholesterol and high-density lipoprotein cholesterol, triglycerides, former pregnancies, ovariectomy and related surgical interventions, smoking history and former use of oral contraceptives. To ensure the premenopausal status of the participants, the regularity of the menstrual cycle and the follicle-stimulating hormone concentrations were also assessed. Plasma estradiol and progesterone and urine estrone concentrations (24 h urine collection) were measured at day 6 after estimated ovulation to assess the relative increase in plasma estradiol and progesterone during the second half of the menstrual cycle. RESULTS: Compared with the control group, premenopausal women with CHD had significantly lower concentrations of plasma estradiol (408.9 +/- 141 pmol/l and 287.8 +/- 109 pmol/l respectively; P = 0.0228) and total estrogen (2061 +/- 693 pg/mumol creatinine and 1607 +/- 448 pg/mumol creatinine respectively; P = 0.025) in the urine. However, the progesterone concentrations were not significantly different between the groups. These findings might be explained by a partial ovarian dysfunction, as the patient group had a significantly higher number of tubal sterilizations (eight compared with one). CONCLUSION: Our data provide support for the hypothesis that decreased concentrations of estradiol might be an additional pathogenetic factor for the development of CHD in menstrually active premenopausal women.

Adult↗