Search PubMed⌕ Search

Biomedical subjects

B Meier

Publications and source records attributed to B Meier.

At least 55 records · Page 3Linked to original sources
PubMed2001

Evolution of percutaneous transluminal coronary angioplasty in Europe from 1992-1996.

BACKGROUND: The working group Coronary Circulation of the European Society of Cardiology has been conducting a yearly survey on coronary interventions in Europe. The purpose of this study is to present the evolution of percutaneous transluminal coronary angioplasty (PTCA) with epidemiological and economic implications. METHODS: Coronary interventions were polled by questionnaires distributed to all institutions performing cardiac catheterization. Aggregated country data of the years 1992-1996 on indication, type of procedure, technique, and outcome of coronary interventions were analysed. RESULTS: Population-adjusted coronary angiographies and PTCA procedures increased by 76% and by 105%, respectively. The Percentage of coronary stenting increased from zero to almost half of all procedures. Analysis per country groups reveals considerable variation, ranging, e.g. for PTCA in 1996 from 157 procedures per million population in a group of eastern countries to 1138 in a central European group. Relating total revascularization (R) to standardized death rate for ischaemic heart disease (SDR) and to gross domestic product (GDP), there was an increase from 1.0 to 1.8 R/SDR and 40 to 61 R/GDP in the central European group compared with an increase from 0.06 to 0.18 R/SDR and 43 to 85 R/GDP in the eastern group. CONCLUSIONS: An overall increase in PTCAs at an annual rate between 15 and 25% was observed. The wide variation in the use of PTCA in Europe appears to be dependent mostly on economic factors and national health care policies.

Angioplasty, Balloon, Coronary↗
PubMed2001

Percutaneous closure of patent foramen ovale in symptomatic patients.

BACKGROUND: Patent foramen ovale (PFO) and atrial septal aneurysm (ASA) have been associated with stroke in young adults. Patients with PFO suffering from paradoxical embolism are at increased risk for recurrent events. Percutaneous PFO closure is a new treatment modality aimed at secondary prevention. METHODS AND RESULTS: Since April 1994, 132 consecutive patients, aged 51 +/- 12 years with PFO and with at least one paradoxical embolic event, underwent percutaneous PFO closure using six different device types. The embolic index event was an ischemic stroke in 62% of patients, a transient ischemic attack (TIA) in 33% of patients, and a peripheral embolism in 5% of patients. Thirty-six (27%) patients had PFO associated with ASA, whereas 96 (73%) patients had PFO only. The implantation procedure was successful in 130 (98%) patients. During and up to 6 years of follow-up (mean 1.8 +/- 1.6 years, 231 patient years), a total of eight recurrent embolic events were observed, with six TIAs, two peripheral emboli, and no ischemic stroke. The actuarial freedom from recurrence of the combined end point of TIA, ischemic stroke, and peripheral embolism was 95.3% (95% confidence interval [CI], 91.0%-96.4%) at 1 year and 90.5% (95% CI, 83.6%-97.2%) at 6 years. CONCLUSIONS: Percutaneous PFO closure can be performed with a high success rate. The procedure appears a promising therapeutic modality for secondary prevention of recurrent embolism in patients with PFO. Randomized trials must define its therapeutic value.

Adult↗
PubMed2001

New function of CDC13 in positive telomere length regulation.

Two roles for the Saccharomyces cerevisiae Cdc13 protein at the telomere have previously been characterized: it recruits telomerase to the telomere and protects chromosome ends from degradation. In a synthetic lethality screen with YKU70, the 70-kDa subunit of the telomere-associated Yku heterodimer, we identified a new mutation in CDC13, cdc13-4, that points toward an additional regulatory function of CDC13. Although CDC13 is an essential telomerase component in vivo, no replicative senescence can be observed in cdc13-4 cells. Telomeres of cdc13-4 mutants shorten for about 150 generations until they reach a stable level. Thus, in cdc13-4 mutants, telomerase seems to be inhibited at normal telomere length but fully active at short telomeres. Furthermore, chromosome end structure remains protected in cdc13-4 mutants. Progressive telomere shortening to a steady-state level has also been described for mutants of the positive telomere length regulator TEL1. Strikingly, cdc13-4/tel1Delta double mutants display shorter telomeres than either single mutant after 125 generations and a significant amplification of Y' elements after 225 generations. Therefore CDC13, TEL1, and the Yku heterodimer seem to represent distinct pathways in telomere length maintenance. Whereas several CDC13 mutants have been reported to display elongated telomeres indicating that Cdc13p functions in negative telomere length control, we report a new mutation leading to shortened and eventually stable telomeres. Therefore we discuss a key role of CDC13 not only in telomerase recruitment but also in regulating telomerase access, which might be modulated by protein-protein interactions acting as inhibitors or activators of telomerase activity.

Blotting, Southern↗
PubMed2001

Quantitative contrast echocardiographic assessment of collateral derived myocardial perfusion during elective coronary angioplasty.

OBJECTIVE: To determine whether myocardial contrast echocardiography can be used to quantify collateral derived myocardial flow in humans. METHODS: In 25 patients undergoing coronary angioplasty, a collateral flow index (CFI) was determined using intracoronary wedge pressure distal to the stenosis to be dilated, with simultaneous mean aortic pressure measurements. During balloon occlusion, echo contrast was injected into both main coronary arteries simultaneously. Echocardiography of the collateral receiving myocardial area was performed. The time course of myocardial contrast enhancement in images acquired at end diastole was quantified by measuring pixel intensities (256 grey units) within a region of interest. Perfusion variables, such as background subtracted peak pixel intensity and contrast transit rate, were obtained from a fitted gamma variate curve. RESULTS: 16 patients had a left anterior descending coronary artery stenosis, four had a left circumflex coronary artery stenosis, and five had a right coronary artery stenosis. The mean (SD) CFI was 19 (12)% (range 0-47%). Mean contrast transit rate was 11 (8) seconds. In 17 patients, a significant collateral contrast effect was observed (defined as peak pixel intensity more than the mean + 2 SD of background). Peak pixel intensity was linearly related to CFI in patients with a significant contrast effect (p = 0.002, r = 0.69) as well as in all patients (p = 0.0003, r = 0.66). CONCLUSIONS: Collateral derived perfusion of myocardial areas at risk can be demonstrated using intracoronary echo contrast injections. The peak echo contrast effect is directly related to the magnitude of collateral flow.

Aged↗
PubMed2001

Influence on collateral flow of recanalising chronic total coronary occlusions: a case-control study.

OBJECTIVE: To assess the effect of recanalisation on collateral flow in a case-control study in patients with and without chronic total coronary occlusions. DESIGN: In 54 patients undergoing percutaneous transluminal coronary angioplasty (PTCA) (mean (SD) age 61 (6) years), coronary collateral flow was measured by intracoronary pressure or Doppler guide wires at the end of repeated balloon occlusions. Coronary collateral flow index (collateral flow relative to normal antegrade flow) during the first two balloon inflations in 27 patients with a chronic total occlusion (occlusion group) was compared with that of 27 patients matched for age, sex, and collateral flow index at the first occlusion and with a coronary artery diameter stenosis </= 80% (stenosis group). RESULTS: Following revascularisation, collateral flow index decreased in 17 of the patients in the occlusion group (63%) and in eight of the patients in the stenosis group (30%) (p = 0.03 between groups). The overall change of collateral flow index between the first and the second balloon occlusion was -0.04 (0.01) in the occlusion group (p = 0.07 for paired comparison; from 0.29 (0.17) to 0.25 (0.14)), and +0.02 (0.06) in the stenosis group (p = 0.06 for paired comparison; from 0.27 (0.13) to 0.30 (0.15)). The trend to collateral enhancement in the stenosis group differed significantly from the occlusion group (p = 0.01). CONCLUSIONS: While repeated coronary balloon occlusions induce collateral recruitment in the majority of patients with moderate stenoses, recanalisation of chronic total coronary occlusions is more often associated with collateral flow reduction. A later decrease in collateral flow by involution of collateral channels cannot be excluded by this study but has not been reported so far.

Angioplasty, Balloon, Coronary↗
PubMed2001

Washout collaterometry: a new method of assessing collaterals using angiographic contrast clearance during coronary occlusion.

OBJECTIVE: To investigate the hypothesis that the time to washout of radiographic contrast medium trapped distal to an occluded collateral receiving vessel is inversely related to collateral flow, and that this provides an accurate method for characterising coronary collaterals. METHODS: An intracoronary pressure derived collateral flow index was determined in 54 patients undergoing percutaneous transluminal coronary balloon angioplasty (PTCA). The study group was subdivided according to whether the collateral vessels were sufficient (n = 17) or insufficient (n = 37) to prevent ECG signs of myocardial ischaemia during PTCA. Washout collaterometry-an angiographic washout method-was carried out simultaneously; after injection of radiographic contrast medium into the collateral receiving vessel followed immediately by vascular occlusion, the number of heart beats was counted until approximately half the length of the epicardial vessel was cleared of contrast. RESULTS: The collateral flow index was higher (0.28 (0.09) v 0.12 (0.07); p < 0.0001) and the contrast washout time shorter (8.0 (2.9) v 17.5 (6.7) heart beats; p < 0.0001) in patients with sufficient versus insufficient collaterals. There was an inverse correlation between contrast washout time and collateral flow index (r = 0.72, p < 0.0001). Washout of contrast distal to the occluded vessel within 11 heart beats correctly determined sufficient and insufficient collaterals with 88% sensitivity and 81% specificity. CONCLUSIONS: Washout collaterometry is a new radiographic contrast washout method based on the inverse relation between collateral flow and the time to clearance of radiographic dye injected into the ipsilateral vessel during PTCA. It appears to be an accurate method of characterising coronary collateral vessels.

Angioplasty, Balloon, Coronary↗
PubMed2001

Absorbance data of hypericin and pseudohypericin used as reference compounds for medicinal plant analysis.

The evaluation of the absorbance data of hypericin and pseudohypericin revealed the molar/specific coefficients of absorbance in methanol-pyridine (99:1, v/v) at the maximum of the longest wavelength to be 51936/1030 and 43486/836, respectively. The absorbance data of hypericin were also determined in methanol. They were not significantly different from those in the presence of pyridine. The decrease of the coefficients by water addition was found to be the same for hypericin and pseudohypericin. It was concluded that hypericin and pseudohypericin reveal the same homoassociation behavior.

Anthracenes↗
PubMed2001

[Do dissociations between implicit and explicit memory disappear, when reliability of the tests is comparable? An example].

Implicit memory measures tend to be less reliable than explicit memory measures. Consequently dissociations can arise as a consequence of differential reliabilities of the tasks. In the present study the effect of a manipulation of levels of processing in an implicit and an explicit memory task were investigated in a sample of 200 students after establishing comparable reliabilities of the memory tasks. A fragmented object-naming test was used as an indirect test and a recognition task was used as a direct test. The reliabilities of these measures were comparable in all conditions. A main effect of levels of processing, but no interaction between type of test and levels of processing, was found. These findings reinforce the necessity of taking into account the reliability of memory measures for the interpretation of dissociations between explicit and implicit memory.

Adult↗
PubMed2001

Patent foramen ovale: pathophysiology and therapeutic options in symptomatic patients.

The foramen ovale, a remnant from the fetal circulation, remains patent through adulthood in approximately 1/4th of the general population, thus representing the most common persistent abnormality of fetal origin. In these individuals, the patent foramen ovale (PFO) permits interatrial right-to-left shunting during those periods of time when right atrial exceeds left atrial pressure. Recently, the pathophysiological aspects of the PFO have been increasingly appreciated, giving rise to disease manifestations such as paradoxical embolism, refractory hypoxemia in patients with right ventricular infarction or severe pulmonary disease, orthostatic desaturation in the setting of the rare platypnea-orthodeoxia syndrome, neurological decompression illness in divers, and migraine headache with aura. Despite the growing recognition of the PFO, particularly when associated with an atrial septal aneurysm, as risk factor for paradoxical embolism, the optimal treatment strategy for symptomatic patients remains undefined. Most patients with presumed paradoxical embolism are currently treated medically with antithrombotic medications, with a paucity of data concerning the efficacy of oral anticoagulant as opposed to antiplatelet therapy. Surgical PFO closure has proved feasible, but the procedure is associated with the well known complications of cardiac surgery, and the results have been mixed with respect to stroke prevention. The recent introduction of interatrial septal occlusion devices set the stage for a minimally invasive, percutaneous approach. The present article discusses the pathophysiology of the PFO, and the advantages and drawbacks of the different therapeutic options available for symptomatic patients.

Embolism, Paradoxical↗
PubMed2000

[Non-surgical closure of patent ductus arteriosus: acute and long-term results].

INTRODUCTION: Closure of a patent ductus arteriosus (PDA) even with small shunt volumes in asymptomatic patients is recommended because of the risk of endocarditis (1.5% per year) and the potential development of congestive heart failure or pulmonary hypertension. METHODS: 16 patients (9 adults [5 men/4 women] and 7 children [3 boys/4 girls]) underwent transcatheter closure of a PDA. The intervention was performed using the Rashkind umbrella in 12 cases, the Amplatzer duct occluder in 2 cases, a coil in 2 cases, and the Sideris self-adjusting device in one case. Echocardiographic controls were carried out one day, 6 months, 12 months and 24 months after the intervention. RESULTS: PDA closure was complete immediately following the intervention in 9 of 16 patients (56%). At follow-up (mean 19 months) complete closure was observed in 14 of 16 patients (87%). All residual shunts were trivial. The complete closure rate in adults was 100% and in children 71%. Complications such as device embolism, endarteritis and haemolysis did not occur. CONCLUSION: Non-surgical closure of a PDA is a safe and effective technique.

Adult↗
PubMed2000

Percutaneous closure of patent foramen ovale in patients with paradoxical embolism: long-term risk of recurrent thromboembolic events.

BACKGROUND: Patients with a patent foramen ovale (PFO) and paradoxical embolism are at risk for recurrent thromboembolic events. This study investigated the long-term risk of recurrent thromboembolic events in patients with PFO and paradoxical embolism after percutaneous PFO closure. METHODS AND RESULTS: Since 1994, a total of 80 patients with PFO and at least 1 paradoxical embolic event (transient ischemic attack [TIA], cerebrovascular accident [CVA], peripheral embolism) have undergone percutaneous PFO closure with 5 different devices. There were 30 women and 50 men, with a mean age of 52+/-12 years. Sixty patients had only a PFO, whereas 20 patients had both a PFO and an atrial septal aneurysm. The implantation procedure was successful in 78 patients (98%). During 5 years of follow-up (mean, 1.6+/-1.4 years; range, 0.1 to 5.0 years), the actuarial annual risk to suffer a recurrent thromboembolic event was 2.5% for TIA, 0% for CVA, 0.9% for peripheral emboli, and 3.4% for the combined end point of TIA, CVA, or peripheral embolism. A postprocedural shunt was a predictor of recurrent paradoxical embolism (RR, 4.2; 95% CI, 1.1 to 17.8; P=0.03). The risk for recurrent thromboembolic events in patients with both atrial septal aneurysm and PFO was not significantly increased compared with patients with only PFO (RR, 1.0; 95% CI, 0.2 to 4.7; P=0.95). CONCLUSIONS: Percutaneous PFO closure appears to be a promising technique in the prevention of recurrent systemic thromboembolism in patients with a PFO after a first event. Prospective studies comparing percutaneous PFO closure with antithrombotic medications or surgery must define its therapeutic value.

Actuarial Analysis↗