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Biomedical subjects

B Meier

Publications and source records attributed to B Meier.

At least 109 records · Page 6Linked to original sources
PubMed1999

Involvement of reactive oxygen species in TNF-alpha mediated activation of the transcription factor NF-kappaB in canine dermal fibroblasts.

The cytokine tumor necrosis factor-alpha (TNF-alpha) plays a major role in inflammatory and immune-pathological reactions of the skin. With respect to a possible therapeutic modulation of TNF-alpha mediated activation of Nuclear Factor-kappa B (NF-kappaB) in canine cutaneous inflammation, we investigated the role of NF-kappaB and the involvement of reactive oxygen species (ROS) in the TNF-alpha signalling pathway in dermal fibroblasts of the dog. TNF-alpha treatment resulted in the activation of NF-kappaB as assessed by electrophoretic mobility shift assay (EMSA). Additionally, NF-kappaB translocation was induced with butylhydroperoxide and antimycin A, but not with hydrogen peroxide. TNF-alpha stimulated NF-kappaB activation was partially inhibited by preincubation with the antioxidants alpha-lipoic acid and butylated hydroxyanisol (BHA). No superoxide generation following TNF-alpha stimulation could be detected in the supernatant of canine fibroblasts with the superoxide dismutase-inhibitable cytochrome c reduction test. In contrast, production of TNF-alpha dependent intracellular hydrogen peroxide, the dismutation product of the superoxide radical, was demonstrated spectroscopically by formation of electron dense cerium-hydroperoxide precipitates. With electron energy loss spectroscopy (EELS) significant cerium deposits were detected in the mitochondria, the endoplasmatic reticulum, the cytosol and to a lesser extent on the plasma membrane of canine fibroblasts indicating multiple hydrogen peroxide production sites. Peroxides, therefore, possibly play an important part in the redox-sensitive pathway of TNF-alpha dependent NF-kappaB activation in canine skin. An adjunctive therapy with appropriate antioxidants modulating NF-kappaB overactivation in cutaneous inflammation in the dog is promising.

Animals↗
PubMed1999

[Invasive diagnosis of coronary heart disease in patients over 75 years old].

Between January 1, 1993, and August 31, 1995, 268 patients over 75 years underwent coronary angiography at the University Hospital of Bern. Their clinical reports were analyzed in order to determine whether invasive diagnosis of coronary artery disease (CAD) is justifiable also in the elderly considering risks and complications. The main indication for coronary angiography were symptoms of ischemic heart disease. Twenty-nine underwent the procedure for planned cardiac surgery, mostly valve replacement. In 79% of patients, coronary angiography revealed CAD. In the remaining 21% there were no significant coronary stenoses, but 82% of them had valvular heart disease. Only 4% had neither coronary nor valvular heart disease. Following coronary angiography 63% of patients had a therapeutical intervention: 24% coronary angioplasty (PTCA), 13% bypass-grafting, 17% valve replacement, 8% combined surgery (revascularization and valve-replacement), and 1% another intervention. Four percent had no cardiac disease, 1% died before a planned surgery. The remaining 32% were continued on medical therapy. As indicators of appropriateness and success of the invasive procedure the rates of complications and the duration of hospitalization were analyzed. The incidence of deaths, myocardial infarctions, cerebral complications, and arrhythmias was five to ten times higher for cardiac surgery than for PTCA or conservative treatment. Invasive diagnosis and therapy of CAD in patients over 75 years can nevertheless be reasonable and successful if the decision is taken carefully considering risk factors and concomitant disease.

Aged↗
PubMed1999

Is the development of myocardial tolerance to repeated ischemia in humans due to preconditioning or to collateral recruitment?

OBJECTIVES: The purpose of this study in patients with quantitatively determined, poorly developed coronary collaterals was to assess the contribution of ischemic as well as adenosine-induced preconditioning and of collateral recruitment to the development of tolerance against repetitive myocardial ischemia. BACKGROUND: The development of myocardial tolerance to repeated ischemia is nowadays interpreted to be due to biochemical adaptation (i.e., ischemic preconditioning). METHODS: In 30 patients undergoing percutaneous transluminal coronary angioplasty, myocardial adaptation to ischemia was measured using intracoronary (i.c.) electrocardiographic (ECG) ST segment elevation changes obtained from a 0.014-in. (0.036 cm) pressure guidewire positioned distal to the stenosis during three subsequent 2-min balloon occlusions. Simultaneously, an i.c. pressure-derived collateral flow index (CFI, no unit) was determined as the ratio between distal occlusive minus central venous pressure divided by the mean aortic minus central venous pressure. The study patients were divided into two groups according to the pretreatment with i.c. adenosine (2.4 mg/min for 10 min starting 20 min before the first occlusion, n = 15) or with normal saline (control group, n = 15). RESULTS: Collateral flow index at the first occlusion was not different between the groups (0.15 +/- 0.10 in the adenosine group and 0.13 +/- 0.11 in the control group, p = NS), and it increased significantly and similarly to 0.20 +/- 0.14 and to 0.19 +/- 0.10, respectively (p < 0.01) during the third occlusion. The i.c. ECG ST elevation (normalized for the QRS amplitude) was not different between the two groups at the first occlusion (0.25 +/- 0.13 in the adenosine group, 0.25 +/- 0.19 in the control group). It decreased significantly during subsequent coronary occlusions to 0.20 +/- 0.15 and to 0.17 +/- 0.13, respectively. There was a correlation between the change in CFI (first to third occlusion; deltaCFI) and the respective ST elevation shift (deltaST): deltaST = -0.02 to 0.78 x deltaCFI; r = 0.54, p = 0.02. CONCLUSIONS: Even in patients with few coronary collaterals, the myocardial adaptation to repetitive ischemia is closely related to collateral recruitment. Pharmacologic preconditioning using a treatment with i.c. adenosine before angioplasty does not occur. The variable responses of ECG signs of ischemic adaptation to collateral channel opening suggest that ischemic preconditioning is a relevant factor in the development of ischemic tolerance.

Adenosine↗
PubMed1999

[Bj"ork-Shiley heart vales at the Bern University Hospital. Long-term follow-up of 12 to 23 years after mitral and aortic valve replacement in 503 patients].

Long-term follow-up, cardial complications and factors influencing the survival time have been investigated retrospectively in 503 patients, who underwent 344 aortic and 191 mitral valve replacements with Björk-Shiley heart valve prosthesis between 1973 and 1984 at the University Hospital of Berne, Switzerland. Informations were assessed from the patient's files and a questionnaire to the family physician. The cumulative follow-up contains a total of 4,810 patient years or a median of 14 years per patient. The median survival time was 19 years, hardly less than the normal life expectancy. Of the 135 patients found alive in 1996 66% had no cardiac problems at all. Two cases of outlet strut fracture of the Björk-Shiley valve were reported during the follow-up time. Both patients had a mitral valve replacement in 1982 with a 31 mm Björk-Shiley valve because of mitral stenosis. The most common complication was a thromboembolic incident (1.6 in 100 patient years). Furthermore eight cases of valve thrombosis, 16 of endocarditis and 24 of myocardial infarction occurred in this population. The study showed that survival time after heart valve replacement with Björk-Shiley valve is long. The mortality was elevated significantly with the following preoperative findings: severe dyspnea (x 2.0), pulmonary congestion (x 1.7) and increased cardiac size (x 1.5). The survival time was shorter when a valve prosthesis with a diameter larger than 27 was used or when in addition coronary heart disease, hypertension, diabetes mellitus or obesity were present.

Adolescent↗
PubMed1999

A prospective, randomized evaluation of nonsurgical closure of femoral pseudoaneurysm by compression device with or without ultrasound guidance.

Femoral artery pseudoaneurysm (PA) is a significant complication following diagnostic or therapeutic catheterization. The treatment of choice for femoral artery PA is freehand ultrasound-guided compression repair (UGCR). An alternative method is compression by mechanical devices. The study evaluated the mechanical compression device (FemoStop) with (G1) or without (G2) ultrasound guidance for initial placement in a randomized fashion. Thirty-eight patients (20 women, 18 men) age 40 to 85 (mean 54) years with clinical signs of PA underwent diagnostic color Doppler ultrasound. Randomization yielded 19 patients each for G1 and G2. PA occurred after 12 diagnostic cardiac catheterizations, 18 coronary stent implantations or balloon angioplasties, 2 electrophysiology procedures, and 6 peripheral percutaneous transluminal angioplasties. The G1 protocol was successful in 15 of 19 patients (79%), with a mean compression time of 28 min. The three other patients were treated successfully with UGCR. Only one patient needed vascular surgery. The G2 protocol was successful in 14 of 19 patients (74%) with a mean compression time of 33 min. The failed patients were treated successfully: three with UGCR and two with the same mechanical compression device now positioned under ultrasound control. Compression therapy with the compression device (FemoStop) for iatrogenic femoral pseudoaneurysm does not require ultrasound guidance for positioning. Cathet. Cardiovasc. Intervent. 47:304-309, 1999.

Aged↗
PubMed1999

Coronary and peripheral artery remodeling in patients undergoing PTCA: An intracoronary and transcutaneous ultrasound study.

The aim of this study was to assess the relationship between the plaque burden of nonstenotic coronary artery segments and the wall thickness of peripheral arteries using intracoronary and transcutaneous ultrasound imaging, respectively. Intracoronary ultrasound (CVIS, 3.5 Fr) was performed in 27 patients undergoing percutaneous transluminal coronary angioplasty. Carotid arteries were imaged by B-mode ultrasound with semiautomatic edge detection and radial arteries by high resolution A-mode echotracking (NIUS 2). Quantitative measurements included coronary artery intima-media cross-sectional area (IM(CSA)) and cross-sectional narrowing (CSN), as well as intima-media thickness (IMT) and lumen radius (r) of the common carotid and the radial arteries. Intima-media thickness was increased in coronary, carotid, and radial arteries. Coronary arteries had an IM(CSA) of 7.7 +/- 2.5 mm(2) and a CSN of 24% +/- 8%. Despite this moderate plaque burden, lumen area was preserved (12.3 +/- 4.2 mm(2)) because of compensatory enlargement of coronary arteries. Right and left carotid and right radial arteries had an IMT of 575 +/- 78 microm, 570 +/- 129 microm, and 328 +/- 61 microm, respectively. There was no correlation between coronary IM(CSA) and carotid IMT (r = 0.07) or radial IMT (r = 0.02), and there was no correlation between coronary CSN and carotid IMT/r (r = 0.12), or radial IMT/r (r = 0.25). In conclusion, in these patients with symptomatic ischemic disease no relationship between IMT of the coronary arteries and IMT of carotid or radial arteries was found. Although increasingly popular, IMT of peripheral arteries may be of limited value as surrogate marker for the severity of coronary artery disease. Cathet. Cardiovasc. Intervent. 48:12-17, 1999.

Adult↗
PubMed1999

Radiographic evaluation of the transplant bone height in patients with clefts of the lip/alveolus/palate after secondary bone grafting.

After secondary osteoplasty radiographic assessment was carried out on 101 patients with cleft lip, jaw and palate (CLP) with 129 uni- and bilateral clefts. The bone formation in the grafted area was assessed on dental radiographs taken 2.9 years on average after secondary osteoplasty. Patients were assigned to 4 groups (Types I to IV) with Types I and II being rated as a success. The purpose of the study was to compare the results in terms of the patients' age at time of surgery, presence or absence of the lateral incisors and prosthetic or orthodontic space closure. The best results in grafted bone height were observed among 6- to 9-year-olds and when the space in the dental arch had been closed orthodontically. If even hypoplastic lateral incisors were preserved, growth into the grafted area could be observed, resulting in successful bone formation of Types I and II. Space due to missing lateral incisors could best be orthodontically closed in the youngest age group and resulted in favorable septal height. The results obtained for the over 14-year-olds were least satisfactory. A reduced septal height was observed and space closure had to be obtained most frequently by prosthetic means.

Adolescent↗
PubMed1999

Simultaneous intracoronary velocity- and pressure-derived assessment of adenosine-induced collateral hemodynamics in patients with one- to two-vessel coronary artery disease.

OBJECTIVES: The purpose of this investigation in patients with poorly and well developed coronary collaterals was to assess the influence of collateral and collateral adjacent vascular resistances and, in part, a stenotic lesion of the collateral supplying vessel on the hemodynamic collateral responses to adenosine. BACKGROUND: In humans, little is known about the functional behavior of the coronary collateral circulation. METHODS: In 50 patients with one- and two-vessel coronary artery disease (CAD) undergoing percutaneous transluminal coronary angioplasty (PTCA), collateral flow index (CFI, no unit) changes and vascular resistance index (R, cm/mm Hg) changes of the collateral (R(coll)) and the distal collateral receiving (R4) vessel in response to adenosine (140 microg/min/kg IV) were measured by intracoronary (i.c.) Doppler and pressure guidewires. The variables were determined at baseline and during adenosine in patients with poor (angiographic collateral degree before PTCA <2 of 0 to 3) and good coronary collaterals. RESULTS: Pressure-derived CFI (CFI(p)) decreased under adenosine in patients with poor collaterals, and it increased in the group with good collaterals. There were inverse correlations between the adenosine-induced change in CFI(p) and the change in R(coll) (r = 0.61, p = 0.0001). In the group with good, but not with poor collaterals, there was also a significant correlation between CFI(p) increase and the decrease in R4, between the severity of the contralateral stenosis and CFI(p) augmentation and among the left versus right coronary artery as ipsilateral vessel and CFI(p) change. CONCLUSIONS: Overall, patients with well, versus poorly developed coronary collaterals do better regarding the capacity to increase collateral flow in response to adenosine. In patients with good, but not poor, collaterals, an adenosine-induced collateral flow increase depends on the ipsilateral distal vascular resistance decrease, but is also directly influenced by the severity of a contralateral stenosis and probably by the size of the collateralized vascular bed.

Adenosine↗
PubMed1999

Audit and quality control in angioplasty in Europe: procedural results of the AQUA Study 1997: assessment of 250 randomly selected coronary interventions performed in 25 centres of five European countries. AQUA Study Group, Nucleus Clinical Issues, Working Group Coronary Circulation, of the European Society of Cardiology.

AIMS: Percutaneous transluminal coronary angioplasty (PTCA) has become the most widely used major intervention in western medicine. However, there is disparate use of this technique among different European countries and the U.S.A. In an attempt at quality assurance, the working group Coronary Circulation of the European Society of Cardiology has carried out a study on appropriateness, necessity, and performance of PTCA in Europe. The present paper reports on the procedural results of this survey. METHODS: In a multicentre case-control study in Europe, 750 patients (544 men, 206 women) with documented vascular disease of the From the countries participating in the European Registry of Coronary Intervention, the three countries with the highest absolute PTCA volume (Germany, France, and the United Kingdom) and two randomly selected countries (Belgium and Italy) were chosen for investigation. In these countries, five centres were selected at random according to the following criteria: one centre with >1000, three centres with 300-1000, and one centre with <300 procedures per year. In each of these, 10 cases from the first half of 1997 were randomly identified and all pertinent documentation was collected. RESULTS: In 250 cases, 325 stenoses were addressed as target lesions. Single vessel disease was present in 41%. History included stable angina in 49%, unstable angina in 32%, atypical chest pain in 6%, no anginal pain in 12%, and acute/subacute myocardial infarction in 13%. The percentage of patients with either positive stress test and/or unstable angina, acute/subacute infarction, previous infarction (within 6 months) or coronary revascularization amounted to 98%. Single vessel intervention accounted for 90%. In 41% balloon-only angioplasty was performed and in 54% at least one stent was implanted with considerable variation among countries. The use of other new devices amounted to only 3%. In 92%, the operators documented a successful procedure. Major complications (myocardial infarction, emergency bypass surgery, or death) were found in 4.8%. CONCLUSIONS: Based on scrutinized hospital and operator data, the present study revealed a satisfactorily high percentage of justifiable indications, an adequate procedural success rate, and an acceptably low complication rate. Further analysis by an expert panel will address appropriateness, necessity, and procedural performance of the individual cases.

Angioplasty, Balloon, Coronary↗
PubMed1999

A randomized evaluation of early revascularization to treat shock complicating acute myocardial infarction. The (Swiss) Multicenter Trial of Angioplasty for Shock-(S)MASH.

AIM: To test whether emergency revascularization improves survival in patients with acute myocardial infarction and shock. METHODS AND RESULTS: Patients with acute myocardial infarction and early shock were randomized either to undergo emergency angiography, followed immediately by revascularization when indicated, or to receive initial medical management. In five of the nine participating centres, patients with shock but not randomized were entered in a registry. Only 55 patients could be randomized. Of the 32 patients in the invasive group, 30 (94%) underwent early angiography, 27 (84%) PTCA, and one (4%) CABG. Twenty-two (69%) died within 30 days in the invasive group vs 18/23 (78%) in the medically managed group (ns, RR=0.88, 95% confidence interval 0.6-1.2). Among the registry patients, 24/51 were excluded from randomization solely because of patient or physician preference for the invasive approach: 23 (96%) of them underwent emergency angiography, 21 (88%) PTCA, and 12 (50%) died within 30 days. Among the remaining registry patients (n=27) only nine (33%) underwent early angiography, nine (33%) PTCA and 20 (74%) died. CONCLUSION: We failed to demonstrate that emergency PTCA significantly improves survival in patients with acute myocardial infarction and early cardiogenic shock. Because the study was stopped prematurely, due to an insufficient patient inclusion rate, a clinically meaningful benefit of early reperfusion may have been missed.

Aged↗
PubMed1999

Indications for intracoronary stent placement: the european view. Working Group on Coronary Circulation of the European Society of Cardiology.

AIMS: In Europe, no written official guidelines on indications for coronary stent placement are available. We therefore assessed the opinions of European interventional cardiologists on these indications. METHODS AND RESULTS: In April 1997, a questionnaire was sent to the members of the Working Group on Coronary Circulation of the European Society of Cardiology with interventional cardiology as the main activity. A total of 165 questionnaires were returned and analysed. For the treatment of acute or threatened vessel closure during PTCA, the threshold for stenting is set at the level of a type C dissection by 42% of the cardiologists, while 22% stent any form of dissection and 13% require an impaired TIMI flow. A suboptimal PTCA result necessitating stenting is defined as a residual stenosis of >50% by 35% or of 30 >30% by 55% of the respondents. When considering primary prevention of restenosis, only 2% unconditionally stent focal, new-onset lesions in native coronary arteries, 44% refrain from stenting in a case of a stent-like PTCA result (</=30% residual stenosis) and 73% think that stent types other than the Palmaz-Schatz may be implanted for this indication. Restenotic lesions are unconditionally stented by 30% of the interventionists while 64% reserve this option only for suboptimal PTCA results. Amongst the other indications, stenting is considered to be the treatment of choice as follows: chronic total occlusion, 85%; saphenous vein graft lesions, 59%; aorto-coronary ostial lesions, 64%; and primary intervention for myocardial infarction: 59%. CONCLUSION: European interventional cardiologists have integrated current literature on stenting into their daily practice. The most cited indications (threatened vessel closure and suboptimal PTCA results) are not supported by randomized trials. The variations in the conclusions from randomized trials may be explained by the general expectation that stenting will improve PTCA results.

Angioplasty, Balloon, Coronary↗