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Biomedical subjects

C Bauters

Publications and source records attributed to C Bauters.

At least 55 records · Page 3Linked to original sources
PubMed1999

ACE gene polymorphism and coronary restenosis.

In humans, circulating levels of angiotensin-converting enzyme (ACE) are linked with an insertion (I)/deletion (D) polymorphism in the ACE gene: DD genotype bearers have higher levels of ACE than either ID or II genotype bearers. Recent studies have suggested that the ACE DD genotype might be associated with a higher risk of coronary artery disease. The aim of this paper is to review studies on the influence of the I/D polymorphism on coronary restenosis. The renin-angiotensin system has been implicated in the pathogenesis of neointimal hyperplasia in experimental models. In humans, the I/D polymorphism is not associated with restenosis after balloon angioplasty, but is strongly associated with restenosis after coronary stent implantation. This may be explained by the fact that the contribution of neointimal hyperplasia to restenosis is much more important after coronary stent implantation than after balloon angioplasty.

Angioplasty, Balloon, Coronary↗
PubMed1999

A novel 9-base pair duplication in RET exon 8 in familial medullary thyroid carcinoma.

Familial medullary thyroid carcinoma (FMTC) and multiple endocrine neoplasia type 2A syndromes are dominantly inherited diseases caused by activating germline mutations of the RET protooncogene. The majority of these patients carry a germline point mutation affecting one of five cysteine residues encoded by exon 10 (codon 609, 611, 618, or 620) or 11 (codon 634). In a few FMTC families, point mutations involving noncysteine codons in exon 13 (codons 768, 790, and 791), 14 (codon 804), or 15 (codon 891) have been reported. Hirschsprung's disease is a nonneoplastic disorder associated with RET mutations leading to a loss of function effect. Mutations are identified in 50% of the familial cases and are scattered along the gene. We now report the study of a FMTC family with four affected members and a history of fatal neonatal intestinal obstruction in the sister of the proband. Genetic analysis demonstrated the absence of an usual FMTC mutation and the presence of a germline 9-bp duplication in RET exon 8 in the heterozygous state in all patients with MTC. This new mutation creates an additional cysteine residue in the extracellular cysteine-rich domain of RET. Further studies are warranted to confirm whether this new mutation is causing MTC only or could be associated with Hirschsprung's disease.

Adult↗
PubMed1999

Growth factors and endothelial dysfunction.

Endothelial dysfunction has been implicated in the pathogenesis of many cardiovascular diseases: experimental and clinical studies have shown that endothelial dysfunction may be a key factor in various processes, including abnormal arterial vasomotion, thrombosis or neointimial proliferation. Endothelial dysfunction has been shown to be a characteristic feature of atherosclerotic vessels, sites subject to mechanical injury or collateral vessels that develop in response to severe ischaemia. Fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF) are important growth factors for endothelial cells in vitro. While VEGF is specific for endothelial cells. FGFs are also potent growth factors for other cell types such as smooth muscle cells. Recent studies have demonstrated the feasibility of using endothelial cell growth factors in vivo. Basic FGF (bFGF) and VEGF have been shown to increase the development of collateral vessels in ischaemic models and to enhance the extent of endothelial regrowth following arterial injury. The marked anatomical improvement associated with the administration of endothelial cell growth factors has promoted questions concerning a possible role for these factors in endothelial dysfunction. In vivo administration of endothelial cell growth factors is associated with significant improvement in endothelium-dependent responses. This effect is observed with bFGF and VEGF in various animal models of endothelial dysfunction such as the collateral circulation, the regenerated endothelium following arterial injury and experimental atherosclerosis. While the precise mechanisms underlying this ubiquitous beneficial effect of endothelial cell growth factors are still to be determined, these results do support the concept of using such factors as a new therapeutic strategy in patients with vascular diseases.

Animals↗
PubMed1999

Growth factors and endothelial dysfunction.

Endothelial dysfunction has been implicated in the pathogenesis of many cardiovascular diseases; experimental and clinical studies have shown that endothelial dysfunction may be a key factor in various processes, including abnormal arterial vasomotion, thrombosis or neointimal proliferation. Endothelial dysfunction has been shown to be a characteristic feature of atherosclerotic vessels, sites subject to mechanical injury or collateral vessels that develop in response to severe ischaemia. Fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF) are important growth factors for endothelial cells in vitro. While VEGF is specific for endothelial cells, FGFs are also potent growth factors for other cell types such as smooth muscle cells. Recent studies have demonstrated the feasibility of using endothelial cell growth factors in vivo. Basic FGF (bFGF) and VEGF have been shown to increase the development of collateral vessels in ischaemic models and to enhance the extent of endothelial regrowth following arterial injury. The marked anatomical improvement associated with the administration of endothelial cell growth factors has promoted questions concerning a possible role for these factors in endothelial dysfunction. In vivo administration of endothelial cell growth factors is associated with significant improvement in endothelium-dependent responses. This effect is observed with bFGF and VEGF in various animal models of endothelial dysfunction such as the collateral circulation, the regenerated endothelium following arterial injury and experimental atherosclerosis. While the precise mechanisms underlying this ubiquitous beneficial effect of endothelial cell growth factors are still to be determined, these results do support the concept of using such factors as a new therapeutic strategy in patients with vascular diseases.

Animals↗
PubMed1999

[Restenosis after angioplasty].

Restenosis remains the main limitation of endocoronary methods of revascularisation. It is observed in 20 to over 50% of cases, depending on the prevailing risk factors and techniques used. The mechanism of post balloon angioplasty restenosis consists of neointimal hyperplasia, vascular remodelling and thrombosis. Intra-stent thrombosis is mainly caused by the neointimal hyperplasia. The strategies developed to prevent restenosis may be grouped in two categories: mechanical and pharmacological strategies. Stenting is the only mechanical method to have been shown to be effective. With respect to pharmacological methods, the general impression is rather negative even if some positive results have been reported recently. Of the new strategies which may provide a solution in the coming years, gene therapy and endocoronary irradiation justify a special mention.

Angioplasty, Balloon, Coronary↗
PubMed1999

[Coronary angioplasty in diabetic patients. Analysis of the problems to improve results].

The object of this review is to update our knowledge of the results of revascularisation by angioplasty in diabetics. The authors discuss: 1. the clinical results in diabetic patients compared with non-diabetics and the results of coronary bypass surgery; 2. the factors influencing the prognosis of these patients after balloon angioplasty, especially with respect to restenosis; 3. the possibilities of improving the results by the use of modern techniques of revascularisation and prevention and 4. the strategies of revascularisation which may be proposed, based on available data.

Angioplasty, Balloon, Coronary↗
PubMed1998

Enhanced monocyte tissue factor response after experimental balloon angioplasty in hypercholesterolemic rabbit: inhibition with dietary L-arginine.

BACKGROUND: There is evidence that tissue factor (TF) is a major contributor to the thrombogenicity of a ruptured atherosclerotic plaque. Nitric oxide (NO) has antiatherogenic and antithrombotic properties. We investigated whether L-arginine (L-arg), the endogenous precursor of NO, might affect the ability of monocytes to produce TF. METHODS AND RESULTS: We studied TF expression in 18 rabbits with atherosclerosis induced by bilateral iliac damage and 10 weeks of a 2% cholesterol diet. Six weeks after the initiation of the diet, an angioplasty was performed. After angioplasty, the surviving rabbits (n=15) were randomized to receive L-arg (2.25%) supplementation in drinking water (L-arg group, n=8) or no treatment (untreated group, n=7). TF expression was evaluated in mononuclear cells from arterial blood in the presence and absence of endotoxin stimulation. Monocyte TF expression, as assessed with an amidolytic assay, did not differ significantly before or after the induction of atherosclerotic lesions (87+/-15 versus 70+/-12 mU of TF/1000 monocytes, P=NS). Endotoxin-stimulated TF activity increased significantly 4 weeks after angioplasty (138+/-22 versus 70+/-12 mU of TF/1000 monocytes, P=0.02). This increase was blunted by L-arg (43+/-16 mU of TF/1000 monocytes, P=0.01). CONCLUSIONS: This study demonstrates that angioplasty-induced plaque rupture is associated with a marked increase in monocyte TF response that is blunted by the oral administration of L-arg. This suggests that the documented antithrombotic properties of NO may be related in part to an inhibitory effect on monocyte TF response.

Angioplasty, Balloon↗
PubMed1998

Nitric oxide synthase modulates angiogenesis in response to tissue ischemia.

We tested the hypothesis that endothelial nitric oxide synthase (eNOS) modulates angiogenesis in two animal models in which therapeutic angiogenesis has been characterized as a compensatory response to tissue ischemia. We first administered L-arginine, previously shown to augment endogenous production of NO, to normal rabbits with operatively induced hindlimb ischemia. Angiogenesis in the ischemic hindlimb was significantly improved by dietary supplementation with L-arginine, compared to placebo-treated controls; angiographically evident vascularity in the ischemic limb, hemodynamic indices of limb perfusion, capillary density, and vasomotor reactivity in the collateral vessel-dependent ischemic limb were all improved by oral L-arginine supplementation. A murine model of operatively induced hindlimb ischemia was used to investigate the impact of targeted disruption of the gene encoding for ENOS on angiogenesis. Angiogenesis in the ischemic hindlimb was significantly impaired in eNOS-/- mice versus wild-type controls evaluated by either laser Doppler flow analysis or capillary density measurement. Impaired angiogenesis in eNOS-/- mice was not improved by administration of vascular endothelial growth factor (VEGF), suggesting that eNOS acts downstream from VEGF. Thus, (a) eNOS is a downstream mediator for in vivo angiogenesis, and (b) promoting eNOS activity by L-arginine supplementation accelerates in vivo angiogenesis. These findings suggest that defective endothelial NO synthesis may limit angiogenesis in patients with endothelial dysfunction related to atherosclerosis, and that oral L-arginine supplementation constitutes a potential therapeutic strategy for accelerating angiogenesis in patients with advanced vascular obstruction.

Animals↗
PubMed1998

Six-month angiographic outcome after successful repeat percutaneous intervention for in-stent restenosis.

BACKGROUND: In-stent restenosis is an increasing clinical problem. Discordant results have been published regarding the risk of recurrent restenosis after repeat angioplasty for the treatment of in-stent restenosis. METHODS AND RESULTS: One hundred three consecutive patients (107 vessels) underwent repeat percutaneous intervention for the treatment of in-stent restenosis and were entered in a prospective angiographic follow-up program. Repeat balloon angioplasty was performed at 93 lesions (87%) and additional stenting at 14 lesions (13%). The primary success rate was 98%. Six-month angiographic follow-up was performed in 85% of eligible patients. Restenosis was determined by quantitative angiography. Restenosis defined as a >50% diameter stenosis at follow-up was observed at 22% of lesions. The rate of target-lesion revascularization at 6 months was 17%. Repeat intervention for diffuse in-stent restenosis and severe stenosis before repeat intervention were associated with significantly higher rates of recurrent restenosis. CONCLUSIONS: The overall restenosis rate after repeat intervention for in-stent restenosis is low. The subgroup of patients with diffuse and/or severe in-stent restenosis, however, is at higher risk of recurrent restenosis and may benefit from alternative therapeutic strategies.

Aged↗
PubMed1998

Dual determination of angiotensin-converting enzyme and angiotensin-II type 1 receptor genotypes as predictors of restenosis after coronary angioplasty.

This study sought to assess the potential influence of the angiotensin-converting enzyme (ACE) and angiotensin II type 1 (AT1) receptor gene polymorphisms on restenosis after coronary balloon angioplasty. The authors conclude that screening for genetic suspectibility to restenosis based on genotyping of ACE and AT1 receptor polymorphisms before conventional balloon angioplasty is not clinically useful.

Angioplasty, Balloon, Coronary↗
PubMed1998

Predictors of restenosis after coronary stent implantation.

OBJECTIVES: We sought to determine predictors of restenosis after coronary stenting (CS) in a consecutive series of patients. BACKGROUND: Although stenting in highly selected patient groups reduces restenosis, the results of stenting in a heterogeneous patient group and the effects of clinical and procedural factors on stent restenosis are currently unclear. METHODS: We analyzed the 6-month angiographic outcome of 500 lesions in 463 consecutive patients undergoing successful CS. Clinical, qualitative and quantitative angiographic variables were correlated with restenosis assessed as both a binary and a continuous variable. RESULTS: Restenosis, defined as the presence of >50% diameter stenosis in the dilated segment, was present in 105 (26%) of the 405 lesions with angiographic follow-up. The mean late lumen loss during the follow-up period was 0.79+/-0.64 mm. Implantation of multiple stents (p < 0.0001) and a high acute gain (p < 0.0002) were independently associated with a higher late lumen loss. In contrast, the use of high inflation pressure (p < 0.02) and Palmaz-Schatz stents (p < 0.005) was independently associated with a lower late lumen loss. When restenosis was defined as a qualitative variable, implantation of multiple stents (p < 0.001), stenosis length (p < 0.01), small reference diameter (p < 0.02) and stent type other than Palmaz-Schatz (p < 0.01) were independent predictors of restenosis. None of the clinical variables tested was associated with restenosis. CONCLUSIONS: Coronary stenting in an unselected patient group is associated with an acceptable restenosis rate. Although some risk factors were identified, the risk of restenosis was not related to most of the variables tested. This suggests that the superiority of CS over balloon angioplasty, in terms of restenosis, might also apply to subgroups of patients that were not included in the recent randomized studies.

Aged↗
PubMed1998

Germ-line mutation analysis in patients with multiple endocrine neoplasia type 1 and related disorders.

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant syndrome predisposing to tumors of the parathyroid, endocrine pancreas, anterior pituitary, adrenal glands, and diffuse neuroendocrine tissues. The MEN1 gene has been assigned, by linkage analysis and loss of heterozygosity, to chromosome 11q13 and recently has been identified by positional cloning. In this study, a total of 84 families and/or isolated patients with either MEN1 or MEN1-related inherited endocrine tumors were screened for MEN1 germ-line mutations, by heteroduplex and sequence analysis of the MEN1 gene-coding region and untranslated exon 1. Germ-line MEN1 alterations were identified in 47/54 (87%) MEN1 families, in 9/11 (82%) isolated MEN1 patients, and in only 6/19 (31.5%) atypical MEN1-related inherited cases. We characterized 52 distinct mutations in a total of 62 MEN1 germ-line alterations. Thirty-five of the 52 mutations were frameshifts and nonsense mutations predicted to encode for a truncated MEN1 protein. We identified eight missense mutations and five in-frame deletions over the entire coding sequence. Six mutations were observed more than once in familial MEN1. Haplotype analysis in families with identical mutations indicate that these occurrences reflected mainly independent mutational events. No MEN1 germ-line mutations were found in 7/54 (13%) MEN1 families, in 2/11 (18%) isolated MEN1 cases, in 13/19 (68. 5%) MEN1-related cases, and in a kindred with familial isolated hyperparathyroidism. Two hundred twenty gene carriers (167 affected and 53 unaffected) were identified. No evidence of genotype-phenotype correlation was found. Age-related penetrance was estimated to be >95% at age >30 years. Our results add to the diversity of MEN1 germ-line mutations and provide new tools in genetic screening of MEN1 and clinically related cases.

Amino Acid Substitution↗
PubMed1998

Intramural injection of biodegradable microspheres as a local drug-delivery system to inhibit neointimal thickening in a rabbit model of balloon angioplasty.

Restenosis remains the major limitation of coronary angioplasty. The objective of this study was to develop microspheres able to be delivered at the angioplasty site for long-term drug release and to test their effects in a model of balloon angioplasty. Polylactic-co-glycolide acid microspheres (5-10 microm in diameter) were prepared by using an oil-in-water emulsion-solvent evaporation method. In vitro experiments with hydrocortisone-loaded microspheres revealed a hydrocortisone release for 4 weeks. We studied the in vivo effect of injection of microspheres into the arterial wall of New Zealand White rabbits by using a perforated balloon. Deep penetration of microspheres in the arterial wall was documented immediately after angioplasty. Intimal hyperplasia was assessed in iliac arteries 4 weeks after angioplasty. The morphometric analysis was performed in four groups of animals; the first group was subjected only to conventional angioplasty (control, n = 10), whereas the other three groups after conventional angioplasty were received perforated balloon angioplasty with saline (n = 10), microspheres (n = 10), or hydrocortisone-loaded microspheres (n = 7). Intramural injection of saline did not induce greater intimal hyperplasia compared with control (0.17 +/- 0.03 vs. 0.18 +/- 0.03 mm2, respectively). Microspheres injection was associated with a trend toward a greater degree of intimal hyperplasia that did not reach statistical significance. Hydrocortisone-loaded microspheres were associated with a significant reduction in intimal hyperplasia compared with unloaded microspheres (0.16 +/- 0.02 vs. 0.26 +/- 0.03 mm2, respectively). The polylactic-co-glycolide acid microspheres are well tolerated, easily injected into the arterial wall, and the increase of intimal hyperplasia is easily inhibited by release of hydrocortisone for 4 weeks after initial injury.

Angioplasty, Balloon↗
PubMed1998

Association between the ACE genotype and coronary artery disease. Insights from studies on restenosis, vasomotion and thrombosis.

Circulating levels of angiotensin-converting enzyme (ACE) in humans are linked with an insertion (I)/deletion (D) polymorphism in the ACE gene: DD genotype bearers have higher levels of ACE than either ID or II genotype bearers. Recent studies have suggested that the ACE DD genotype may be associated with a higher risk of coronary artery disease. The aim of this paper is to review studies on the influence of I/D polymorphism on coronary restenosis, coronary vasomotion and coronary thrombosis. The renin angiotensin system has been implicated in the pathogenesis of neointimal hyperplasia in experimental models. In humans, I/D polymorphism is not associated with restenosis after balloon angioplasty but is strongly associated with restenosis after coronary stent implantation. This may be explained by the fact that the contribution of neointimal hyperplasia to restenosis is much more important after coronary stent implantation than after balloon angioplasty. The renin angiotensin system may participate in the regulation of coronary vasomotion. An association between I/D polymorphism and coronary artery spasm has been reported. An increased production of plasminogen activator inhibitor-I and an increase in platelet aggregability may explain the higher risk of coronary thrombosis in subjects with high levels of ACE. The ACE I/D genotype has been associated with a lower incidence of a patent infarct-related artery after myocardial infarction and with a higher risk of total occlusion of the dilated site 6 months after successful balloon angioplasty. These studies suggest that the influence of the I/D polymorphism on coronary artery disease may be multifactorial. Possible mechanisms include interactions with neointimal formation, coronary artery spasm and coronary thrombosis.

Angioplasty, Balloon↗
PubMed1998

[From the angiogenic response to ischemia to the validation of the concept of "therapeutic angiogenesis"].

The object of this review is to assess the importance of angiogenesis in cardiovascular physiology and to review the new therapeutic approach which have opened up in this field. The authors report: 1) general information about growth factors implicated in angiotensin (fibroblast growth factor, vascular endothelial growth factor, scatter factor). 2) data obtained from embryo studies which have confirmed the relative rôle of certain intermediary molecules, especially vascular endothelial growth factor in vascular formation. 3) results of animal model experiments of chronic ischaemia and 4) the therapeutic possibilities that these studies suggest and the preliminary results of human applications.

Angiotensin II↗
PubMed1998

[Current data on atheromatous plaques and their evolution].

The modes of evolution of atheromatous plaques are now better understood. The process may start very early and continue for several decades. The severity of atherosclerosis lies in the results of phases of rapid progression involving a thrombotic mechanism. An initial mechanical accident (rupture or erosion of the plaque) is followed by a phenomenon of arterial thrombosis of variable severity. The vulnerability of an atheromatous plaque (defined as its potential for acute complication) is related to: 1) the risk of rupture, 2) the risk of thrombosis in case of rupture. A number of intrinsic properties influence the degree of plaque vulnerability. A thorough understanding of these mechanisms is essential for the development of new treatments to improve the prognosis of coronary patients.

Arteriosclerosis↗
PubMed1997

Effects of coronary stenting on restenosis and occlusion after angioplasty of the culprit vessel in patients with recent myocardial infarction.

BACKGROUND: PTCA of an infarct-related lesion is associated with a high rate of restenosis and/or vessel occlusion. Recent studies have shown that coronary stenting in patients with stable or unstable angina is associated with a significant reduction in the restenosis rate compared with conventional balloon angioplasty. However, no information is available concerning the long-term effect of coronary stenting at infarct-related lesions compared with balloon angioplasty alone. METHODS AND RESULTS: One hundred consecutive patients undergoing stent implantation at an infarct-related lesion and systematic 6-month angiographic follow-up were matched for major pre-PTCA clinical and angiographic variables with a group of patients undergoing conventional angioplasty. Preprocedural, postprocedural, and 6-month follow-up angiograms were analyzed with quantitative angiography. Coronary stenting was performed as a bailout procedure after failed balloon angioplasty in 20%, for a suboptimal result after balloon angioplasty in 71%, and electively in 9%. Stent implantation was associated with a higher acute gain than balloon angioplasty. At follow-up, the minimal lumen diameter was significantly (P<.0001) larger in the stent group (1.72+/-0.69 versus 1.23+/-0.72 mm). Restenosis (>50% DS at follow-up) occurred in 27% of the stent group versus 52% of the balloon group (P<.005). At follow-up, total occlusion at the dilated site occurred in 1% of the stent group versus 14% of the balloon group (P<.005). CONCLUSIONS: Coronary stenting of infarct-related lesions is associated with a highly beneficial effect on 6-month angiographic outcome compared with balloon angioplasty alone. Further studies are needed to establish whether the beneficial effect of coronary stenting on long-term vessel patency is associated with an improvement in left ventricular function or in clinical outcome.

Adult↗