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W Steffen

Publications and source records attributed to W Steffen.

At least 55 records · Page 3Linked to original sources
PubMed1994

Catheter-delivered high intensity, low frequency ultrasound induces vasodilation in vivo.

This study investigated the effect of intravascular high intensity, low frequency catheter-delivered ultrasound on vasomotor behaviour in vivo. Catheter-delivered therapeutic ultrasound induces endothelium-independent vasodilation in vitro. To study this effect in vivo we analysed the angiograms of canine coronaries and human femoropopliteal arteries before and after ultrasound exposure. Vasomotor behaviour was studied using a computer edge detection program. We analysed the angiograms of: (1) eight canine left coronary arteries before and after ultrasound; (2) eight canine left coronaries only subjected to serial angiograms, and three canine left coronary arteries of two dogs after passing the unactivated ultrasound probe down the coronary artery infusing saline at a rate of 10-20 ml.min-1, which served as controls, and (3) eight angiographically normal human arterial sites proximal to occlusions in eight femoropopliteal arteries of patients undergoing ultrasound angioplasty for peripheral vascular disease. Vessel diameter of canine coronaries after ultrasound exposure increased from 2.3 +/- 0.3 mm to 2.8 +/- 0.3 mm (21 +/- 2.3%) (P < 0.01). There was no change in vascular diameter in controls after multiple angiograms (2.4 +/- 0.3 mm vs 2.5 +/- 0.2 mm (4.2 +/- 0.2%) (P = ns). Average vessel diameter after passage of the unactivated probe with saline infusion decreased in the left anterior descending coronary artery from 3.66 mm to 3.13 mm, and in the left circumflex coronary artery from 2.88 mm to 2.62 mm. Vessel diameter in human femoropopliteal arteries increased from 3.2 +/- 0.2 mm to 3.6 +/- 0.5 mm or by 14.3 +/- 2.9% respectively (P < 0.01) after exposure to ultrasound energy.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty↗
PubMed1994

Use of therapeutic ultrasound in percutaneous coronary angioplasty. Experimental in vitro studies and initial clinical experience.

BACKGROUND: Previous studies have shown the feasibility of peripheral arterial ultrasound angioplasty. METHODS AND RESULTS: In this report, we describe the use of percutaneous therapeutic ultrasound for coronary angioplasty. In vitro, 11 postmortem, atherosclerotically occluded coronary arteries were obtained to assess catheter-delivered ultrasound for arterial recanalization as well as for assessment of the size of particulate debris. Clinically, coronary ultrasound angioplasty was performed in 19 patients (mean age, 56 years) to assess safety and feasibility for the treatment of obstructive coronary atherosclerosis. Three patients with unstable angina and 16 with exercise-induced myocardial ischemia were treated with a prototype 4.6F coronary catheter ultrasound ablation device with a 1.7-mm diameter ball tip. The ultrasound coronary catheter delivered ultrasound energy at 19.5 kHz, with a power output of 16 to 20 W at the transducer. Energy is delivered in a pulsed mode with a 50% duty cycle of 30 milliseconds. Patients were treated for a mean of 493 seconds (range, 130 to 890) with intracoronary ultrasound ablation. All lesions were treated with adjunctive balloon angioplasty. All 11 postmortem coronary occlusions were recanalized, and 99% of the particulates generated were < 10 microns in diameter. We found that after ultrasound, mean (+/- SD) coronary arterial stenosis fell from 80 +/- 12% to 60 +/- 18% (P < .001) and to 26 +/- 11% (P < .001) after adjunctive balloon angioplasty. Mean pressures required to achieve full balloon inflation were 2.7 atm (range, 1 to 5.5) with a median of 3.0-mm balloon size (2.5 to 3.5). No ultrasound-related complications were identified. CONCLUSIONS: Intracoronary ultrasound plaque ablation appears to be safe. Our findings suggest that catheter-delivered high-intensity, low-frequency ultrasound may be useful for lesion debulking and enhancing arterial distensibility, allowing balloon dilation at relatively low pressures.

Angioplasty, Balloon, Coronary↗
PubMed1994

Centrosomal components immunologically related to tektins from ciliary and flagellar microtubules.

Centrosomes are critical for the nucleation and organization of the microtubule cytoskeleton during both interphase and cell division. Using antibodies raised against sea urchin sperm flagellar microtubule proteins, we characterize here the presence and behavior of certain components associated with centrosomes of the surf clam Spisula solidissima and cultured mammalian cells. A Sarkosyl detergent-resistant fraction of axonemal microtubules was isolated from sea urchin sperm flagella and used to produce monoclonal antibodies, 16 of which were specific- or cross-specific for the major polypeptides associated with this microtubule fraction: tektins A, B and C, acetylated alpha-tubulin, and 77 and 83 kDa polypeptides. By 2-D isoelectric focussing/SDS polyacrylamide gel electrophoresis the tektins separate into several polypeptide spots. Identical spots were recognized by monoclonal and polyclonal antibodies against a given tektin, indicating that the different polypeptide spots are isoforms or modified versions of the same protein. Four independently derived monoclonal anti-tektins were found to stain centrosomes of S. solidissima oocytes and CHO and HeLa cells, by immunofluorescence microscopy. In particular, the centrosome staining of one monoclonal antibody specific for tektin B (tekB3) was cell-cycle-dependent for CHO cells, i.e. staining was observed only from early prometaphase until late anaphase. By immuno-electron microscopy tekB3 specifically labeled material surrounding the centrosome, whereas a polyclonal anti-tektin B recognized centrioles as well as the centrosomal material throughout the cell cycle. Finally, by immunoblot analysis tekB3 stained polypeptides of 48-50 kDa in isolated spindles and centrosomes from CHO cells.

Animals↗
PubMed1993

Enhancement of thrombolysis by external ultrasound.

The purpose of our study was to assess the efficacy of external ultrasound to enhance in vitro thrombolysis with urokinase or streptokinase. One-hour-, 1-day-, 4-day-, and 6-day-old human blood thrombi (n = 366) were incubated in normal saline solution with three different concentrations of streptokinase (50, 250, and 2000 mu/ml) or urokinase (200, 2000, and 5000 mu/ml). Thrombi were exposed to pulsed ultrasound of 1 MHz at 1.0, 1.5 and 2.2 W/cm2 at different exposure times. The combination of ultrasound (2.2 W/cm2, 30 min) and urokinase or streptokinase enhanced lysis rate by an average of 25% compared with lysis with thrombolytic agents alone (p < 0.05). The enhancement was greater at higher ultrasound power outputs (2.2 W/cm2 > 1.5 W/cm2 > 1.0 W/cm2). At higher-power outputs there was no increase of temperature in the solution containing the thrombus. The extent of lysis was higher with longer ultrasound exposure time and with fresh thrombi. These data suggest that use of external ultrasound has the potential to increase both efficacy and rate of thrombolysis.

Combined Modality Therapy↗
PubMed1993

Percutaneous ultrasonic angioplasty: initial results of an in-vitro study on normal and atherosclerotic human vessel segments.

The aim of the present study was to assess the efficacy and safety of a new ultrasound catheter system in vitro before employing it in humans. Ultrasound energy was applied to 141 normal and atherosclerotic human vessel segments, obtained at autopsy. Macroscopical and histological examination of the treated vessel segments revealed that ultrasound energy is atraumatic to the normal vessel wall. In atherosclerotic vessel segments, there was macroscopically significant reduction in the size of plaques. In 7/10 completely occluded femoral arterial segments, recanalization could be achieved. The resulting lumen approximated the diameter of the wire probe. Therefore, ultrasound energy is an appealing form of energy for recanalization of completely obstructed atherosclerotic vessels and for disintegration of atherosclerotic plaques. Clinically, ultrasonic angioplasty may become an adjunctive modality to balloon angioplasty.

Angioplasty, Balloon↗
PubMed1992

[Percutaneous sonographic angioplasty. Initial experimental results].

Aim of the present study was to examine in vitro the effects of a new ultrasound catheter system on atherosclerotic and normal vessels before employing the system in humans. 141 attempts were made on 32 vascular preparations obtained at autopsy. The vessels were opened longitudinally within 24 hours of death, dilated with gelatine and were then "treated" in a waterbath using varying degrees of pressure, angle of incidence, sound intensity and duration of sound. Macroscopic and histological examinations of the preparation showed no morphological change in normal vessels except evidence of pressure by the catheter. In particular, there were no perforations of the vessel wall. In atherosclerotic segments there was significant reduction in the size of plaques following treatment.

Angioplasty, Balloon↗
PubMed1992

Evidence for a non-tubulin spindle matrix and for spindle components immunologically related to tektin filaments.

Tektins were originally described as a set of three filamentous proteins (tektin A, B and C) associated with the walls of axonemal microtubules of sea urchin sperm. Using affinity-purified polyclonal antibodies raised against tektins of two sea urchin species, Lytechinus pictus and Strongylocentrotus purpuratus, we looked for tektin-like components in microtubule systems other than axonemes. By immunofluorescence microscopy we observed labeling of meiotic spindles in eggs of the surf clam Spisula solidissima and in several mammalian cell lines. In Spisula eggs the tektin-like antigens were still associated with the spindles after about 95% of the tubulin had been removed via a calcium/cold treatment. In pig kidney epithelial cells the tektin-like antigen appeared to be associated with bundles of calcium-stable spindle microtubules. By SDS-PAGE immunoblot the affinity-purified anti-tektins recognized several polypeptides in tubulin-depleted spindle remnants of Spisula eggs: A approximately 52 kDa, 1 M KCl-resistant component was identified by the antibody raised against tektin C from S. purpuratus, a approximately 48 kDa component was recognized by the antibody specific for tektin A from L. pictus, and three polypeptide bands (approximately 64 kDa, approximately 100 kDa and greater than 200 kDa) were detected by the antibody specific for tektin C from L. pictus. Only the latter antibody, however, stained Spisula spindles by immunofluorescence microscopy. We further report that the sensitivity of antibody recognition of proteins on immunoblots is dependent on the purity of sodium dodecyl sulfate.

Animals↗
PubMed1991

Sublingual administration of captopril in patients with acute myocardial ischemia.

To investigate the anti-ischemic capability of the angiotensin-converting enzyme inhibitor captopril, 10 patients with acute myocardial ischemia (angina pectoris less than 1 h, ST-segment depression greater than or equal to 0.1 mV, no rise in creatine phosphokinase) received 25 mg captopril sublingually after being treated with an intravenous infusion of nitroglycerin (3 mg/h) and heparin (1200 IU/h) for 1 hour. A control group of 10 patients received placebo instead of captopril. Results showed a decrease of the initial ST-segment depression from 0.25 +/- 0.04 to 0.2 +/- 0.03 mV (p less than 0.01) with nitroglycerin for the captopril group and from 0.26 +/- 0.05 to 0.21 +/- 0.05 mV (p less than 0.01) for the control group. An additional decrease to 0.13 +/- 0.03 mV (p less than 0.001) was measured after sublingual captopril, while no significant change was found in the placebo group (0.19 +/- 0.04 mV). In both groups, 3 patients had no incidents of angina after 1-h nitroglycerin infusion. An additional 6 patients resolved their complaints after captopril administration in contrast to only 1 after placebo. Two patients in the placebo group required increased doses of nitroglycerin because of impairment of anginal complaints. Hemodynamic measurements documented a significant drop of pulmonary vascular resistance after a 1-h infusion of nitroglycerin (-12.9% and -13.1%, respectively, p less than 0.05), while all other parameters remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1991

[Soft tissue swelling in sports traumatology. Comparative study of the effectiveness of 2 ointments].

An open randomized study design was used to compare the soft-tissue swelling in patients with fibular capsule injuries under therapy with Chomelanum (preparation A), Lasonil (preparation B) and ointment base of Chomelanum (preparation C). 90 patients were selected for participation in the study, and the results of 85 patients were available for evaluation. Concerning the initial condition there was no significant difference between the three therapy groups of the study. Assessment criteria were the difference of circumference in plane of ankle joint (injured/uninjured side) and the difference of soft-tissue above lateral malleoulus in sonography. The study showed that preparation A had a significantly larger influence on soft tissue detumescence than preparation B- and B larger than C. In observation period all patients of group B and C still showed soft tissue swelling. Between third and fourth day of treatment half of patients in group A did not need any treatment because of complete detumescence. In all assessment criteria significant differences in favor of preparation A were observed.

Ankle Injuries↗
PubMed1990

Sublingual administration of captopril versus nitroglycerin in patients with severe congestive heart failure.

Angiotensin-converting enzyme inhibition has proven to be a successful approach for the long-term treatment of patients with congestive heart failure. This investigation compared the acute hemodynamic changes after sublingual administration of the angiotensin-converting enzyme inhibitor captopril with those after nitroglycerin. A total of 24 patients with severe left heart failure (New York Heart Association classes III and IV) were given 25 mg captopril and 0.8 mg nitroglycerin sublingually in this randomized, cross-over study. Hemodynamic monitoring revealed a clear improvement in pre- and afterload parameters for both drugs (P less than 0.01 and P less than 0.001), while captopril induced a higher increase in cardiac index (+49.2% vs. +25%), stroke volume index (+53.5% vs. +25.7%), and stroke work index (+55% vs. +28%) than nitroglycerin (P less than 0.001). Although not statistically significant, the onset of change for most hemodynamic parameters was measured earlier after nitroglycerin (after 12-19 vs. 16-22 minutes). Captopril revealed later peak effects (after 47-84 vs. 25-55 minutes, P less than 0.001) and a longer sustained improvement in hemodynamic values (return to baseline values after 117-162 vs. 68-120 minutes, P less than 0.001). No side effects occurred after either captopril or nitroglycerin in this study. Thus, these results indicate there is an early improvement in hemodynamic parameters after the sublingual administration of both drugs in patients with severe congestive heart failure, and that captopril induces a more pronounced and prolonged improvement than nitroglycerin.

Administration, Sublingual↗
PubMed1989

[Hemodynamics after sublingual administration of captopril in severe heart failure. A pilot study].

In a preliminary trial, 23 patients in severe left-heart failure and, in some instances, also right-heart failure (NYHA classes III and IV) received a single sublingual dose of 25 mg captopril. Invasive measurement of various haemodynamic parameters indicated (1) an increase in cardiac index and stroke-volume index of 34% and 38%, respectively (P less than 0.001 for each); (2) decrease in pulmonary artery and systemic pressures by an average of 7% and 11.4% (P less than 0.01 and less than 0.001, respectively); (3) no significant change in heart rate and mean right atrial pressure; (4) decrease in systemic and pulmonary artery resistance by 33% and 29% (P less than 0.001 for both); (5) an increase in left ventricular stroke work index by 18% (P less than 0.001); and (6) a fall in heart rate x pressure product by 10% (P less than 0.005). These haemodynamic changes started within 12 to 23 minutes after captopril administration, the peak effect occurring between 40 and 90 minutes. Baseline values were reached after three hours. Reproducibility measurements revealed a close quantitative and temporal correlation (r for all greater than 0.8). To obtain similar changes of cardiac function 1.65 micrograms/min.kg sodium nitroprusside were needed. The results indicate that sublingual administration of captopril in severe heart failure will achieve early and significant improvement in cardiac function.

Administration, Sublingual↗
PubMed1989

Relationship between tektins and intermediate filament proteins: an immunological study.

Affinity-purified antibodies raised against three flagellar tektins (tektin A, B, and C) from each of two sea urchin species (Lytechinus pictus and Strongylocentrotus purpuratus) were used to study the immunological relationship between tektins and intermediate filament proteins. By immunofluorescence microscopy, several antitektins revealed a staining of intermediate filament-like arrays in three vertebrate cell lines tested. Immunoelectron microscopy substantiated the cross reaction of antitektins with intermediate filaments. When the cells were treated with cytochalasin B, the arrangement of the filaments recognized by anti-(Lp)-tektin B was altered; the alteration observed is typical for keratin filaments. By immunoblot, it was found that anti-(Lp)-tektin B cross reacted with two isoforms or different proteins of approximately 54 kD with pIs of 6.1 and 6.2 in human carcinoma epithelia (HeLa) cells and with two isoforms or different proteins of approximately 55 kD with pIs of 6.1 and 6.3 in pig kidney epithelia (LLC-PK1) cells. Furthermore, when antitektin antibodies were affinity purified with the 54 kD HeLa keratin, these keratin-specific antibodies again restained the original tektins on immunoblots. From these observations, it can be concluded that tektins and keratins are to a certain extent immunologically related. To determine the degree of the immunological relationship, tektin filaments and purified intermediate filaments from HeLa cells were cleaved with alpha-chymotrypsin and examined by quantitative immunoblot analysis. On immunoblots of digested tektins from L. pictus, anti-(Lp)-tektin B recognized several cleavage products in the range of 20 kD to 46 kD. However, when immunoblots of digested intermediate filaments from HeLa cells were probed, the cross reaction of anti-(Lp)-tektin B with HeLa keratins was eliminated by more than 98% within 2 min, suggesting that tektins have epitopes in common with the end domains of certain keratins.

Animals↗
PubMed1989

Multiple immunoblot: a sensitive technique to stain proteins and detect multiple antigens on a single two-dimensional replica.

A multiple immunoblotting technique was developed to positively identify up to three different antigens on a single nitrocellulose replica of a two-dimensional isoelectric focusing/sodium dodecyl sulfate-polyacrylamide gel. Three highly sensitive immunoblot assays were selected, including: horseradish peroxidase/luminescence, alkaline phosphatase, and silver-enhanced immunogold. As a major advantage, the method permits a simultaneous detection of up to three different antigens without eluting the antibody-dye complex between staining of single polypeptides, thus providing a highly accurate identification of closely migrating components. The staining procedure is summarized in a flow chart. In addition to the multiple immunoblot staining, some suggestions are provided for a sensitive protein staining.

Animals↗
PubMed1988

Evidence for tektins in centrioles and axonemal microtubules.

Affinity purified, polyclonal antibodies were prepared against three tektins (tektins A, B, and C) isolated from sea urchin sperm axonemal microtubules. These antibodies (anti-tektins) were used to localize tektins in axonemes, basal bodies, and centrioles. By immunofluorescence microscopy it could be demonstrated that in sperm tails from Lytechinus pictus all three anti-tektins stain all nine axonemal doublet microtubules and A-tubule extensions along their entire length. In addition to staining doublet microtubules, anti-tektin C weakly labeled the central-pair microtubules in sperm tails from Patiria miniata. The anti-tektin staining revealed also a clear cross-reaction with basal bodies of sea urchin sperm and with centrioles of cells from hamsters, humans, and pigs. These data provide evidence of tektin or tektin-like proteins in basal bodies and centrioles and suggest that centriole microtubules are constructed according to the same principles as flagellar microtubules.

Animals↗
PubMed1987

Characterization of antibodies as probes for structural and biochemical studies of tektins from ciliary and flagellar microtubules.

Rabbit antibodies raised and purified against three tektins, proteins of flagellar doublet microtubules from sea-urchin sperm (Lytechinus pictus and Strongylocentrotus purpuratus), were used to study tektin biochemistry and their structural localization. Doublet microtubules were fractionated into tektin filaments and separated by SDS-PAGE into three major tektin polypeptide bands (Mr = 47, 51 and 55 (X 10(3)), which were used to immunize rabbits. Antibodies against each tektin (anti-tektins) were affinity-purified and then characterized by two-dimensional isoelectric focusing/SDS-PAGE immunoblotting and by immunofluorescence microscopy. In two-dimensional immunoblots of 0.5% Sarkosyl-resistant fractions of flagellar microtubules, the antibody against the 55 X 10(3) Mr tektin (anti-55) stained one major polypeptide of 55 X 10(3) Mr and pI 6.9, anti-51 stained two polypeptides of 51 X 10(3) Mr and pI approximately 6.15, and anti-47 stained one major polypeptide of 47 X 10(3) Mr and pI 6.15. The anti-tektins also stained several minor neighbouring polypeptides, which may be isoelectric variants, novel tektins or unrelated proteins. Furthermore, anti-47 crossreacted with the major 55 X 10(3) Mr polypeptide. By immunofluorescence microscopy all three anti-tektins stained methanol-fixed echinoderm sperm flagella and embryonic cilia. In addition, anti-47 and anti-55 stained unfixed, demembranated axonemes. Besides staining axonemes, all anti-tektins labelled the basal body region, and anti-51 labelled the sperm head envelope. These results indicate that the tektins are a complex family of proteins that are components of axonemal microtubules and possibly other cytoplasmic and nuclear structures.

Animals↗