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J Wiecha

Publications and source records attributed to J Wiecha.

11 recordsLinked to original sources
PubMed2002

[Long-term follow-up after direct PTCA in women with acute myocardial infarction].

METHODS: Long-term follow-up of 204 consecutive and unselected women vs 577 men after direct PTCA for acute myocardial infarction. RESULTS: Women were older, had more significant comorbidity, and had a longer prehospital phase. Direct PTCA of the infarct artery was angiographically successful in 95% of women and in 94% of men. Total cumulative mortality during 4 years of follow-up was 12.5%, 14.5% 18%, and 23% in women, respectively, vs 9%, 10.5%, 12%, and 15%, respectively, in men (p=ns through year 3, p<0.05 thereafter). After multivariate analysis, gender was no independent risk factor of increased mortality. Major cardiac events and need for target vessel revascularization were unrelated to gender. CONCLUSIONS: There are no gender-specific differences in mortality after direct PTCA for acute myocardial infarction.

Aged↗
PubMed2002

[Prevalence and significance of coronary collateral circulation in patients with acute myocardial infarct].

UNLABELLED: Angiograms from consecutive and unselected patients with acute myocardial infarction were studied with respect to the prevalence as well as the significance of coronary collateral circulation to myocardium distal to the acute coronary occlusion. METHODS: Coronary angiograms were obtained from 700 consecutive and unselected patients with an acute transmural infarction within 3.7 +/- 3 hours (0.5-12) of symptom onset. No patient had undergone i.v. thrombolysis prior to angiography. Complete and acute vessel occlusion was found in 626/700 patients (89%). Coronary collaterals were detected and graded using Rentrop's classification. The grade of collateral circulation was related to the clinical course after 30 days and to the global and regional left ventricular wall motion. RESULTS: Collaterals were found in 334 patients (69%); 242 patients (38%) had collateral flow grade 2 or 3. Collaterals were demonstrated more frequently in women vs men and in patients with multivessel disease. The prevalence of collaterals was unrelated to age and the presence of diabetes mellitus. Patients who had angiography within 3 hours of symptom onset had collaterals detected less frequently than patients who had angiography beyond 6 hours (66% vs 75%, p < 0.05). No collaterals were found in 17/37 patients (47%) in cardiogenic shock and inferior MI but in only 30/164 patients (18%, p < 0.01) without shock. Global and regional left ventricular wall motion after 2 weeks was unrelated to the degree of coronary collateral circulation during acute myocardial infarction. CONCLUSION: Collateral circulation to myocardium distal to an acutely occluded coronary artery is detected in 2/3 patients during the acute infarct phase. The absence of collaterals is related to the early occurrence of cardiogenic shock in patients with inferior MI but not to the presence of diabetes mellitus. After direct angioplasty of the infarct vessel, the protective effects of coronary collaterals on chronic LV function remain uncertain.

Aged↗
PubMed2001

Clinical performance of a specific algorithm to reconfirm self-terminating ventricular arrhythmias in current implantable cardioverter-defibrillators.

Inappropriate shock therapy is a frequent problem in patients with implantable cardioverter-defibrillators (ICDs), caused mostly by supraventricular rhythms. Self-terminating ventricular arrhythmias (STVAs), however, may also lead to inappropriate shock discharges even in ICDs with abortive shock capabilities. The aim of this study was to evaluate the clinical performance of a specific ventricular tachycardia/ventricular fibrillation (VT/VF) reconfirmation algorithm implemented in current ICD devices from Medtronic to prevent inappropriate shock discharges due to STVAs. A total of 161 STVA episodes were documented in 59 of 150 patients (39%) within a mean follow-up of 30 +/- 20 months and resulted in 25 inappropriate shock discharges in 15 of 150 patients (10%) despite activation of the reconfirmation algorithm. The first synchronization interval of the algorithm was met in 92% of STVA episodes with and even 38% of STVA episodes without shock delivery. A reduced incidence of inappropriate shocks due to STVAs was found with tachycardia/fibrillation detection intervals (TDI/FDI) programmed to shorter cycle lengths < or =280 ms or the use of the first 2 cycles after the end of charging to be considered for reconfirmation only. Thus, inappropriate shocks due to STVAs still occur in 10% of patients with ICDs despite activation of a specific VT/VF reconfirmation algorithm, and are mainly caused by meeting the first synchronization interval that therefore should be shortened in cycle length. Moreover, to reduce the likelihood of inappropriate shocks, the VF reconfirmation algorithm should be optimized by basing the synchronization intervals exclusively on the FDI with short cycle lengths or using the first 2 cycles for reconfirmation only.

Algorithms↗
PubMed1999

Reducing obesity via a school-based interdisciplinary intervention among youth: Planet Health.

OBJECTIVE: To evaluate the impact of a school-based health behavior intervention known as Planet Health on obesity among boys and girls in grades 6 to 8. DESIGN: Randomized, controlled field trial with 5 intervention and 5 control schools. Outcomes were assessed using preintervention (fall 1995) and follow-up measures (spring 1997), including prevalence, incidence, and remission of obesity. PARTICIPANTS: A group of 1295 ethnically diverse grade 6 and 7 students from public schools in 4 Massachusetts communities. INTERVENTION: Students participated in a school-based interdisciplinary intervention over 2 school years. Planet Health sessions were included within existing curricula using classroom teachers in 4 major subjects and physical education. Sessions focused on decreasing television viewing, decreasing consumption of high-fat foods, increasing fruit and vegetable intake, and increasing moderate and vigorous physical activity. MAIN OUTCOME MEASURES: Obesity was defined as a composite indicator based on both a body mass index and a triceps skinfold value greater than or equal to age- and sex-specific 85th percentiles. Because schools were randomized, rather than students, the generalized estimating equation method was used to adjust for individual-level covariates under cluster randomization. RESULTS: The prevalence of obesity among girls in intervention schools was reduced compared with controls, controlling for baseline obesity (odds ratio, 0.47; 95% confidence interval, 0.24-0.93; P = .03), with no differences found among boys. There was greater remission of obesity among intervention girls vs. control girls (odds ratio, 2.16; 95% confidence interval, 1.07-4.35; P = .04). The intervention reduced television hours among both girls and boys, and increased fruit and vegetable consumption and resulted in a smaller increment in total energy intake among girls. Reductions in television viewing predicted obesity change and mediated the intervention effect. Among girls, each hour of reduction in television viewing predicted reduced obesity prevalence (odds ratio, 0.85; 95% confidence interval, 0.75-0.97; P = .02). CONCLUSION: Planet Health decreased obesity among female students, indicating a promising school-based approach to reducing obesity among youth.

Adolescent↗
PubMed1998

A remark on the high-conductance calcium-activated potassium channel in human endothelial cells.

The patch-clamp technique was used to examine the presence of large conductance calcium-activated potassium channels (BKCa) in human endothelial cells and to characterize their properties in terms of voltage dependence, ion conduction and blockade by iberiotoxin (IbTX). Experiments were performed using cell-attached and outside-out configurations on human umbilical vein endothelial cells (HUVEC). For the experiments HUVECs, which were passaged 6-19 times, were used. In early passages channel activities were absent suggesting the appearance of BKCa depending on cell culture time. The inverse logarithmic voltage sensitivity was 10.17 mV (median) for cell-attached recordings and 12.10 mV (median) for outside-out patches (membrane voltage range: 60-120 mV, symmetrical 140 mM K+ solutions). The I/V relationship was quasilinear in the range of 0-80 mV and exhibited a nonlinear behaviour under further depolarization suggesting some kind of saturation mechanism. Using a sigmoid function to fit the data, channel conductance was calculated as 172.9 pS (median) for cell-attached patches and as 262.1 pS (median) for outside-out patches. IbTX, known as one of the most selective blockers of BKCa was perfused to outside-out patches. In two out of three experiments there was complete block of the ion channel after 1 min.

Cells, Cultured↗
PubMed1998

Modulation of Ca2+-activated K+ channels in human vascular cells by insulin and basic fibroblast growth factor.

Insulin and basic fibroblast growth factor (bFGF) play an important role in the pathogenesis of atherosclerosis and have been shown to have vasodilatory effects. Since modulation of vascular ion channels determines membrane potential and thereby influences essential Ca2+-dependent intracellular pathways, we have investigated the effect of insulin and bFGF on Ca2+-activated K+ channels (BKCa) in human umbilical vein endothelial cells (HUVEC) and smooth muscle cells. The latter were obtained from either atherosclerotic plaques (SMCP) or from media segments (SMCM) of human coronary arteries. Using the patch-clamp technique, insulin (100 microU/ml) caused a significant increase in BKCa open-state probability in SMCP and HUVEC, whereas no significant changes were observed in SMCM. Basic FGF (30 ng/ml) revealed a significant increase in BKCa activity in HUVEC and a significant decrease in the BKCa open-state probability in SMCP, but caused no changes in SMCM. Thus, growth factors modulate vascular BKCa in a cell-type specific manner, which may be of importance concerning vasoactive and atherogenic effects of growth factors.

Arteriosclerosis↗
PubMed1997

Ca(2+)-activated K+ channels in human smooth muscle cells of coronary atherosclerotic plaques and coronary media segments.

The behavior of Ca(2+)-activated K+ channels of large conductance (BKCa) in smooth muscle cells, which were obtained from atherosclerotic plaque material (SMCP) and from media segments (SMCM) of human coronary arteries, were compared using the patch-clamp technique. Voltage-clamp protocols in cell-attached patches revealed the characteristic voltage-dependent activation of BKCa in both cell groups. Single-channel conduction as 216.4 +/- 16.7 pS (n = 6) in SMCP and 199.9 +/- 6.7 pS (n = 6) in SMCM in symmetrical 140 mM K+ solutions. Using outside-out patches, external perfusion with 500 microM tetraethylammonium ions caused a typical "flickery block" of the unitary current. The selective BKCa channel inhibitor iberiotoxin (50 nM) effectively blocked BKCa, channel activity. Comparing BKCa open-state probabilities (P0) at +80 mV in cell-attached patches, a highly significant difference between SMCP (P0 = 0.1438 +/- 0.1301; n = 15) and SMCM (P0 = 0.0093 +/- 0.0044; n = 15; Kruskal-Wallis test, p < 0.001) was found. In contrast to this finding, there was no significant difference in the open-state probability of BKCa, between SMCP (P0 = 0.542 +/- 0.0237; n = 9) and SMCM (P0 = 0.0472 +/- 0.0218; n = 10; p = n.s.) using inside-out patches. The results show an interesting difference in the behavior of large conductance Ca(2+)-activated K+ channel in SMCP compared to SMCM with a significantly higher channel activity in human smooth muscle cells obtained from coronary atherosclerotic plaque material. This finding may indicate an important functional role of BKCa channels in the development of atherosclerosis.

Calcium↗
PubMed1997

Exercise.

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Adolescent↗
PubMed1993

Cellular electrophysiological properties in myocardial infarction.

Important ventricular arrhythmias consequent upon myocardial infarction have several pathophysiological features. Because the arrhythmogenic substrate following myocardial infarction gradually changes different electrophysiological and biochemical determinants can be related to ventricular arrhythmias at distinct periods. In acute ischaemia and infarction, multiple ionic and metabolic changes result in marked electrophysiological inhomogeneity at the cellular level, in which post-repolarization refractoriness and cellular uncoupling are involved in conduction disturbances. Twenty-four to 72 h after coronary occlusion (subacute phase), action potential abnormalities, in addition to abnormal impulse generation in surviving cell layers within and in the border zone of the infarcted area, contribute mainly to arrhythmias. In healed infarcted myocardium, changes in intercellular impulse propagation as well as non-uniform anisotropic cardiac tissue play a major role in the maintenance of arrhythmias, whereas the initiating mechanisms are less well defined.

Action Potentials↗
PubMedDate not supplied

Blockade of Ca2+-activated K+ channels inhibits proliferation of human endothelial cells induced by basic fibroblast growth factor.

Basic fibroblast growth factor (bFGF) exerts angiogenic and mitogenic properties in human tissue. Since changes in ion currents modulate essential Ca2+-dependent intracellular pathways in endothelial cells, we have investigated a possible contribution of Ca2+-activated K+ channels (BKCa) on bFGF-induced endothelial cell proliferation. The patch-clamp technique was used to identify BKCa and to study their modulation by bFGF in cultured endothelial cells of human umbilical cord veins (HUVEC). Cell counts of HUVEC were carried out on different days to analyze bFGF-induced cell proliferation and its influence by the specific BKCa blocker iberiotoxin (IBX). Using single-channel recordings, we found characteristic BKCa with a single-channel slope conductance of 170.3 +/- 2.1 pS (n = 7), half-maximal activation at internal pCa = 5.7 (n = 5; test potential: 80 mV), and dose-dependent block by IBX (25-100 nmol/l). In cell-attached patches bFGF (50 ng/ml) caused a significant increase in the open-state probability (NPo) after 6 min at test potentials of 80 and 100 mV (n = 28; p < 0.001), respectively, which lasted up to 30 min. After preincubation with pertussis toxin (100 ng/ml; 4 h) bFGF superfusion did not cause a significant increase in BKCa activity until 25 min had passed (n = 20; p < 0.01). Addition of 100 nmol/l IBX to the pipette solution caused a total block of BKCa within 2 min in cell-attached patches, whereas bFGF (50 ng/ml) was not able to activate BKCa. When incubated with IBX (25-100 nmol/l) every 2 days, bFGF-induced proliferation of HUVEC was significantly decreased by 50 (-41%) and 100 nmol/l (-50%) IBX (n = 5; p < 0.001) after 7 days. We conclude that activation of BKCa by bFGF may play an important role in bFGF-induced proliferation of human endothelial cells and thus might be important in the process of angiogenesis and vascular remodelling.

Calcium↗