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Biomedical subjects

B Meier

Publications and source records attributed to B Meier.

At least 73 records · Page 4Linked to original sources
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↗
PubMed2000

[Nonsurgical occlusion of an atrial septal defect in childhood: initial Swiss experiences].

The initial experience with catheter closure of an atrial septal defect (ASD) in children, performed at two Swiss centers is presented. The ASD closures were performed according to international multicenter study protocols. 14 children, aged 3.9-17.5 years underwent closure by catheter. The defect size varied between 12 and 22 mm (balloon sized), the ratio between pulmonary and systemic blood flow showed a mean of 2.2 (1.5-3.5). Catheter closure was done using three different occlusion devices. More recently only the Amplatzer occluder was used at both institutions. In 12 children (86%) defect closure was successful and after a follow-up of 3-32 months (mean 17) only one child had a trivial residual interatrial shunt. In all children, echocardiographic follow-up showed an unchanged and correct device position on both sides of the atrial septum. In two children, a floppy aortic segment of the atrial septal rim led to instable device position: both children underwent surgical defect closure later. The children with successful device closure showed no complications during the catheterization or during follow-up. There were no thrombotic complications on the surfaces of the devices. Catheter closure of an ASD during childhood is a safe and efficient alternative to standard surgical treatment.

Adolescent↗
PubMed2000

Genetic comparison between different populations of Eulemur macaco flavifrons in northwest Madagascar using RAPD markers.

Eulemur macaco flavifrons, the Sclater's black lemur, is a critically endangered subspecies of northwest Madagascar, which is not yet protected by any reserve. In order to study the feasibility of creating such a reserve, an area of outstanding biological importance was selected in the region of Maromandia-Sahamalaza, which is probably the only remaining place which would permit the long-term survival of the Sclater's black lemur. To determine if genetic management is needed for the Sahamalaza black lemur population, its genetic variability was estimated with random amplified polymorphic DNA (RAPD) markers and compared with other populations. These comparisons demonstrate that the Sahamalaza black lemurs have a genetic variability equivalent to those in other areas. Thus, we conclude that no genetic management is required at the present time.

Animals↗
PubMed2000

Mechanical compression of coronary artery stents: potential hazard for patients undergoing cardiopulmonary resuscitation.

Mechanical compression of coronary artery stents may be associated with a fatal outcome as the result of refractory myocardial ischemia. We present the history of an 83-yr-old patient, who died owing to hemorrhagic shock 3 days after stent implantation, despite immediate cardiopulmonary resuscitation (CPR). Postmortem examination showed stent compression, probably due to mechanical deformation during CPR. This complication has been reported in two other cases in the literature, suggesting that CPR may be hazardous to patients with coronary artery stents.

Aged↗
PubMed2000

Efficacy of Vitex agnus castus L. extract Ze 440 in patients with pre-menstrual syndrome (PMS).

In a prospective, multicentre trial the efficacy of an Vitex agnus castus L extract Ze 440 was investigated in 50 patients with pre-menstrual syndrome (PMS). The patients were treated daily with one tablet (20 mg native extract) during three menstrual cycles. 43 patients completed the study protocol which encompassed 8 menstrual cycles (2 baseline, 3 treatment and 3 post-treatment). 13/43 patients were receiving concomitant oral contraceptives. 6 patients did not complete the study for reasons not related to study medication, and one patient complained of fatigue possibly related to study medication. All evaluated patients took at least 85% of the prescribed medication. The main effect parameter was the validated Moos' menstrual distress questionnaire (MMDQ), and secondary parameters were a visual analogue scale (VAS; self-assessment) and a global impression scale (GI, self-assessment). The study population was homogenous in age (31.3+/-7.7 years) weight (58.9+/-6.9 kg) and cycle length (28.4+/-0.3 d). The diagnosis was according to DMS-III. At the end of the study, PMS-related symptoms were reduced by treatment. There was a significant score reduction (42.5%) of the MMDQ as the main effect parameter (p<0.001). Symptoms gradually returned after treatment cessation. However, a difference from baseline remained (20%; p<0.001) up to 3 cycles thereafter. 20/43 patients were considered "responders", with a reduction in MMDQ score by at least 50% relative to baseline. At baseline, the VAS score was elevated in the late luteal phase and low at the follicular phase, as expected. During treatment, VAS score decreased in the late luteal phase (47.2%; p<0.01) and remained 21.7% (p<0.001) below baseline after 3 cycles post-cessation of treatment. The low VAS score within the follicular phase remained unchanged over the whole observation period. 38 patients judged the global efficacy moderate to excellent, 5 patients indicated no global efficacy. The number of days patients sustained PMS symptoms was reduced slightly from 7.5 to 6. Resting levels of blood prolactin remained within the physiological range throughout. No differences were seen between patients on or off oral contraceptives. 20 patients reported 37 adverse events (AE). No serious AE were reported. One patint withdrew after four days of treatment due to fatigue and headache. Laboratory safety control parameters were not affected. In conclusion, patients with PMS can be treated successfully with Vitex agnus-castus extract Ze 440, as indicated by clear improvement in the main effect parameter during treatment and the gradual return after cessation of treatment. The main response to treatment seems related to symptomatic relief rather than to the duration of the syndrome.

Adult↗
PubMed2000

Bisanthraquinone glycosides of Hypericum perforatum with binding inhibition to CRH-1 receptors.

Four new bisanthraquinone glycosides, S-(+)-skyrin-6-O-beta-glucopyranoside (1), R-(-)-skyrin-6-O-beta-glucopyranoside (2), S-(+)-skyrin-6-O-beta-xylopyranoside (3) and S-(+)-skyrin-6-O-beta-alpha-arabinofuranoside (4), have been isolated from an ethanol-water (1:1, v/v) dry extract of the aerial parts of Hypericum perforatum L. The structures were elucidated by spectroscopic methods, mainly NMR and mass spectrometry. Circular dichroism was used to determine their axial stereochemistry revealing 1 and 2 to be atropisomers. 1 and 2 inhibited [125I]sauvagine binding to corticotropin releasing hormone (CRH-1) receptors.

Acetylation↗
PubMed2000

Results of transvenous occlusion of secundum atrial septal defects with the fourth generation buttoned device: comparison with first, second and third generation devices. International Buttoned Device Trial Group.

OBJECTIVES: The purpose of this study was to assess safety and effectiveness of the fourth generation buttoned device in dosing atrial septal defects (ASDs) and to test the hypothesis that introduction of double button reduces unbuttoning rate without reducing effectiveness. BACKGROUND: Because of the high unbuttoning rate (7.2%) with first, second and third generation buttoned devices, the device was modified (fourth generation) so that there were two radiopaque spring buttons 4 mm apart on the button loop attached to the occluder. METHODS: During a four-year period ending in September 1997, 423 patients, ages 1.5 to 80 years (median 16 years), underwent closure of ASD at 40 medical centers around the world. RESULTS: The ASD size varied between 5 and 30 mm (median 17 mm). The device size varied between 25 and 60 mm. Unbuttoning occurred in 4 (0.9%) of 423 patients. Effective occlusion, defined as no (n = 343) or trivial (n = 34) residual shunt on echo-Doppler studies performed within 24 h of the procedure, was demonstrated in 377 patients (90%). Thus, the unbuttoning rate (0.9 vs. 7.2%) decreased (p<0.01) while effective occlusion rate (90 vs. 92%) remained unchanged (p>0.1) with this device, compared with earlier generation devices. During follow-up from one month to five years (23+/-15 months), 21 (5%) of 417 patients required surgical (n = 12) or transcatheter (n = 9) reintervention, mostly to treat significant residual shunt. In the remaining patients there was gradual reduction and disappearance of the residual shunt. No wire integrity problems were observed. CONCLUSIONS: These data suggest that the fourth generation buttoned device is as effective as earlier generation devices, but without significant unbuttoning. Follow-up results remained good, with a reintervention-free rate of 89% at five years.

Adolescent↗
PubMed2000

Pharmacological activities of Vitex agnus-castus extracts in vitro.

The pharmacological effects of ethanolic Vitex agnus-castus fruit-extracts (especially Ze 440) and various extract fractions of different polarities were evaluated both by radioligand binding studies and by superfusion experiments. A relative potent binding inhibition was observed for dopamine D2 and opioid (micro and kappa subtype) receptors with IC50 values of the native extract between 20 and 70 mg/mL. Binding, neither to the histamine H1, benzodiazepine and OFQ receptor, nor to the binding-site of the serotonin (5-HT) transporter, was significantly inhibited. The lipophilic fractions contained the diterpenes rotun-difuran and 6beta,7beta-diacetoxy-13-hydroxy-labda-8,14-dien . They exhibited inhibitory actions on dopamine D2 receptor binding. While binding inhibition to mu and kappa opioid receptors was most pronounced in lipophilic fractions, binding to delta opioid receptors was inhibited mainly by a aqueous fraction. Standardised Ze 440 extracts of different batches were of constant pharmacological quality according to their potential to inhibit the binding to D2 receptors. In superfusion experiments, the aqueous fraction of a methanolic extract inhibited the release of acetylcholine in a concentration-dependent manner. In addition, the potent D2 receptor antagonist spiperone antagonised the effect of the extract suggesting a dopaminergic action mediated by D2 receptor activation. Our results indicate a dopaminergic effect of Vitex agnus-castus extracts and suggest additional pharmacological actions via opioid receptors.

Animals↗
PubMed2000

Quantitatively assessed coronary collateral circulation and restenosis following percutaneous revascularization.

AIMS: A high degree of collateral supply to a vascular area where a percutaneous transluminal coronary angioplasty (PTCA) has been performed represents a haemodynamic force competing with the antegrade flow through the dilated lesion. Therefore, our purpose was to determine whether patients with restenosis following PTCA have a higher collateral flow to the recipient vessel than patients without restenosis. METHODS AND RESULTS: In 200 consecutive PTCA patients, an intracoronary pressure-derived collateral flow index (CFI) was determined quantitatively during balloon occlusion, using simultaneous measurements of the mean aortic pressure (P(ao)) and of the intracoronary pressure distal to the occluded stenosis (P(occl)), as well as the estimated central venous pressure (CVP=5 mmHg): CFI=(P(occl)-CVP)/(P(ao)-CVP). Sixty-four patients had an angiographic follow-up examination after at least 2 months, and were subdivided into patients with restenosis (>50% diameter stenosis, n=34) and patients without restenosis (n=30). Patients with restenosis had a significantly higher collateral flow index at the initial coronary angiography than patients without restenosis (0.26 +/- 0.14 vs 0.12 +/- 0.09; P<0.0001). CONCLUSIONS: Patients with restenosis after PTCA show a more extended collateral supply to this recipient area than patients without restenosis. Well developed collaterals to a revascularized region are a risk factor for restenosis of the treated lesion.

Adult↗
PubMed2000

Total occlusion trial with angioplasty by using laser guidewire. The TOTAL trial.

AIMS: A randomized trial was performed to assess the safety and efficacy of a laser guidewire, in the treatment of chronic coronary occlusions. METHODS AND RESULTS: In 18 European centres, 303 patients with a chronic coronary occlusion were randomized to treatment with either the laser guidewire (n=144) or conventional guidewires (mechanical guidewire, n=159). The primary end-point of the study was treatment success, defined as reaching the true lumen distal to the occlusion by the allocated wire within 30 min of fluoroscopic time: laser guidewire vs mechanical guidewire; 52.8% (n=76) vs 47.2% (n=75), P=0.33. Serious adverse events following the initial guidewire attempt were 0% (laser guidewire) and 0.6% (mechanical guidewire), respectively. Angioplasty (performed following successful guidewire crossing) was successful in 179 patients (91%, laser guidewire n=79, mechanical guidewire n=100), followed by stent implantation in 149 (79%). At the 6-month angiographic follow-up, the difference in binary restenosis rate (laser guidewire vs mechanical guidewire; 45.5% vs 38.3 %, P=0.72) or reocclusion rate (25.8% vs 16.1%, P=0.15) did not reach statistical significance. At 1, 6 and 12 months, angina and event-free survival were 69%, 35% and 24% (laser guidewire) vs 74%, 40% and 31% (mechanical guidewire). CONCLUSION: Although laser guidewire technology was safe, the increase in crossing success did not reach statistical significance.

Aged↗
PubMed2000

Quantitative high performance liquid chromatographic analysis of diterpenoids in agni-casti fructus.

Pharmacological data have indicated that part of the dopaminergic activity of Vitex agnus-castus is attributed to the labdan diterpenoids found in the fruits. Therefore an analytical method for the standardization of rotundifuran (1), vitexilactone (2) and 6 beta,7 beta-diacetoxy-13-hydroxy-labda-8,14-diene (3) was developed. Because of the time-consuming and expensive isolation of the diterpenoids, p-cymene was chosen as an internal standard. The concentration of rotundifuran in different extracts and trade samples of the drug varies between 0.04 and 0.30% in the drug and between 1.04 and 2.23% in the extract. The concentration of vitexilactone was generally lower between 0.016 and 0.167% for the drug and between 0.34 and 1.01% for the extract. The determined concentration of 6 beta,7 beta-diacetoxy-13-hydroxy-labda-8,14-diene in the drug was in the range of 0.02 and 0.10% and in the extract in the range of 0.18 and 0.80%. Determination of the factors of correction of p-cymene gave 5.63 for rotundifuran, 2.73 for vitexilactone and 3.74 for 6 beta,7 beta-diacetoxy-13-hydroxy-labda-8,14-diene.

Chromatography, High Pressure Liquid↗