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Biomedical subjects

S Vetter

Publications and source records attributed to S Vetter.

At least 19 recordsLinked to original sources
PubMed2006

Relevant training issues for introduction of digital radiology: results of a survey.

Council Directive 97/43/Euratom establishes the need for adequate training of radiology staff. The transition to digital radiology implies changes in various imaging aspects, which are not sufficiently covered by current institutional training programmes. This work aimed to assess how professionals, experienced in digital imaging, acquired their expertise and hence, what form institutional training should take. Within DIMOND III, a survey on training and resources was performed among radiology professionals. A lack of institutional education for digital radiology was found. In the transition to digital radiology, 30-35% train on the job and another 23-28% receive training from digital equipment vendors. A general agreement exists on the need for new quality criteria and strategies for dose management. Issues relevant for conventional/digital transition are only sparsely covered in EC training programmes. Based on these results, a set of training issues was produced, to be included in future European guidelines.

Education, Medical, Continuing↗
PubMed2006

Optimisation strategies and justification: an example in uterine artery embolisation for fibroids.

Radiation risk has to be justified and optimised. This study discusses the radiation risk of uterine artery embolisation (UAE) for the treatment of fibroids. A total of 70 consecutive UAE dosimetry parameters were assessed. Using Monte Carlo simulation, organ and effective doses and dose conversion coefficients (DCCs) (mSv Gy cm(-2)) were calculated. During UAE optimisation, avoidance of oblique views and use of last-image-hold (LIH) documentation instead of digital subtraction angiography (DSA) were investigated. Mean dose-area product (DAP) was 37.1 Gy cm2 (median 23.7 Gy cm2) and mean fluoroscopy time was 18.4 min (median 16.6 min). Dose values decreased as the study progressed: mean DAP for patients 1-21, 68.5 Gy cm2; patients 22-43, 35.7 Gy cm2; and patients 44-69, 13.0 Gy cm2. Average DCC for DSA image procedures was 0.572, yielding a mean effective dose of 29.6 mSv (median 17.1 mSv). For LIH-only procedures, an average DCC of 0.813 was estimated [using mean effective dose: 10.6 mSv (median 8.1 mSv)].

Adult↗
PubMed2004

[Cost analysis for ambulatory patients in internal medicine].

We analyzed the diagnostical and therapeutical costs of 300 ambulatory patients over a two year period in a Swiss university policlinic of internal medicine. The calculations were based on the catalogue of hospital services (Spitalleistungskatalog) and the drugstore prices for pharmaceuticals (Apothekenpreise). The overall costs for the 300 patients were about 238,400 CHF. The refund by the health insurances represented 56% (excluding specific services such as radiological examinations). The main costs concerned analytical laboratory services (32%), physicians services (27%), technical services (26%), and pharmaceuticals (15%). Some analytical and technical services were prescribed unexpectedly frequently. Prevalent among the emitted pharmaceuticals were protone pump inhibitors, modern cardiovascular drugs and statins. Presumed reasons may be a minor cost awareness of the physicians and a trend towards modern but expensive therapies. An adequate cost awareness can only emerge from precise data of effective costs.

Adult↗
PubMed2004

The use of atorvastatin treatment in usual care environments: pooled analysis of six prospective, observational studies in 90,535 patients.

OBJECTIVE: We investigated the pattern of use as well as the efficacy and safety of atorvastatin in unselected inpatients and outpatients in routine clinical practice in Germany. DESIGN: Six prospective, observational studies with a similar design were pooled. The studies lasted for up to 12 weeks and data from 90,535 patients (7,287 inpatients, 83,248 outpatients) were collected. The studies were performed in Germany in 2000 and 2001. Hospital or office-based physicians selected hyperlipemic patients with or without coronary heart disease (CHD) for once daily treatment with atorvastatin. Information on demographics, atorvastatin dosage, concomitant medication, concomitant diseases, cardiovascular risk factors, lipid profile as well as adverse events (AEs) and serious adverse events (SAEs) were obtained at 2-3 visits and descriptively analyzed. MAIN OUTCOME MEASURES: Absolute and relative changes in lipid parameters, percentage of patients with low-density lipoprotein cholesterol (LDL-C) values within target ranges according to the National Cholesterol Education Program (NCEP) criteria, and frequencies of AEs. RESULTS: On average, patients were treated for 22.4 days (inpatients) and 106.0 days (outpatients), respectively. The overall mean atorvastatin dose of 14.4 mg/day was well tolerated by a heterogeneous patient population with a variety of concomitant diseases and medications. Overall, 0.8% of patients suffered from one or more AEs, 0.6% were considered as treatment-related. The corresponding figures for SAEs and treatment-related SAEs were 0.1% (131 patients) and 0.01% (13 patients), respectively. Subgroup analyses did not reveal a particular safety concern in any subgroup. In total, 99% of patients judged the tolerability of atorvastatin as very good or good. The mean percentages of reduction in LDL-C at the final visit ranged between 24.8% and 28.5%. Overall, 26.3% of patients reached the NCEP LDL-C goal compared to 4.9% at baseline. Inpatients achieved the target range for LDL-C more frequently than outpatients (35.3% vs 25.6%). An underuse of atorvastatin titration in clinical practice in Germany was apparent, particularly in outpatients. CONCLUSIONS: The use of atorvastatin in usual care environments is effective and safe. There is a gap between treatment guidelines and clinical practice in Germany as reflected by the number of patients outside the target range for LDL-C. A major opportunity exists to increase the number of patients who achieve LDL-C target ranges by appropriate dose titration and/or giving patients a higher initial dose. Available guidelines need to be implemented more stringently.

Anticholesteremic Agents↗
PubMed2003

[Endoscopic drainage of symptomatic pancreatic pseudocysts. An efficient and safe therapy in the clinical routine?].

BACKGROUND AND OBJECTIVE: Clinical studies have demonstrated excellent success and low complication rates of endoscopic therapy of pancreatic pseudocysts. But it is not known, if these results can be reached in gastroenterological centers outside clinical studies. PATIENTS AND METHODS: We investigated the outcome of endoscopic therapy in 21 patients (15 male, 6 female, age 40 - 81) with pancreatic pseudocysts treated in our clinic between 1997 and 2002. A follow-up examination was included. RESULTS: Similar to the results of reported clinical studies the initial clinical success rate was 18/21 with symptomatic recurrences in two patients. All therapy-induced complications were successfully treated conservatively. CONCLUSION: Excellent results of endoscopic therapy of pancreatic pseudocysts can be reached in a gastroenterological center. Surgical treatment can be reserved for cases, when endoscopic therapy fails.

Adult↗
PubMed2003

Patient radiation exposure in uterine artery embolization of leiomyomata: calculation of organ doses and effective dose.

The goal of this study was estimation of patient effective dose from uterine artery embolization of leiomyomata. Parameters and data relevant to patient dose were recorded for 33 consecutive procedures. Using Monte Carlo simulation of radiation transport, organ and effective doses were calculated in detail for a subset of five procedures, to estimate the effective dose for all procedures. Mean dose area product was 59.9, median 23.4, and range 8.8-317.5 Gycm(2). Mean absorbed ovarian dose was calculated as 51 mGy in the five procedures. Using the dose conversion factor estimated from the Monte Carlo simulation for all procedures a mean estimated effective dose of 34 mSv (median 13 mSv, range 5-182 mSv) results, with a tendency to lower values regarding the succession of the procedures. Patients' radiation exposure level is up to twice of that of an abdominal CT examination. Angiographic equipment related dose-reducing features and radiographic technique essentially influence organ doses and effective dose. Consistent application of dose-reducing techniques and awareness of radiation exposure justifies uterine artery embolization as a therapeutic option for the treatment of uterine fibroids.

Adult↗
PubMed2003

[Mirizzi Syndrome without Cholecystolithiasis].

BACKGROUND: Mirizzi syndrome is a rare cause of biliary symptoms and jaundice. It describes an obstruction of the common hepatic bile duct by external compression caused by an impacted gallstone in the gallbladder neck or cystic duct. This setting is usually associated with cholecystolithiasis. CASE REPORT: A 64-year-old caucasian woman with intermittent abdominal pain and newly diagnosed jaundice was admitted to our clinic. An ERC was performed a few weeks earlier because of similar complaints without jaundice. At that time there was no evidence of choledocholithiasis. Now ERC surprisingly showed a gallstone impacted in the cystic duct, leading to an external compression of the common hepatic bile duct (Mirizzi syndrome). Since an endoscopic stone extraction failed, surgical intervention was performed. A laparoscopic cholecystectomy was performed without trans-cystic stone removal. After removal of the bile duct drainage it became evident that the impacted stone was still located in the remaining part of the cystic duct. After successful endoscopic extraction of the impacted stone the patient remained free of symptoms without recurrent jaundice. CONCLUSION: In rare cases Mirizzi syndrome without cholecystolithiasis can cause biliary symptoms. A close interdisciplinary cooperation is necessary in order to guarantee an excellent therapeutic management.

Bile Duct Diseases↗
PubMed2002

[Primary and secondary aortoiliac reconstructions in patients with coexistent horseshoe and pelvic kidney].

The coexistence of dystopic kidney and abdominal aortic aneurysm or aortoiliac occlusive arterial disease is uncommon (0.12-0.15 %) and constitutes a technical challenge to vascular surgeons. Between 1997 and 1999 we performed 249 aortoiliac reconstructions and encountered four patients (1.6 %) with dystopic kidneys. The aortoiliac reconstructions were performed successfully in all patients while maintaining renal blood supply. Aortoiliac reconstructions in patients with horseshoe or pelvic kidney show similar results as regular reconstructions on the condition that optimal preoperative diagnosis and operative technique are used considering atypical renal vessels. Nevertheless, pelvic kidneys can lead to serious complications as we describe in this report. On the basis of our patients anatomy, embryology and surgical management of this entity.

Aged↗
PubMed2001

Clinical aspects of quality criteria in digital radiography.

In clinical radiological practice two main questions regarding image quality have to be looked at: Which degree of image quality is needed? and: How can this image quality be objective? Image quality requirements depend on size, density and contrast of the objects of interest and on the clinical question which has to be answered. In comparison to conventional radiography, the digital radiographic techniques offer additional features concerning optimisation of image quality and dose, like a wider dynamic range, digital fluoroscopic techniques and post-processing. Therefore it is necessary to define new quality criteria for these techniques. In the following, typical examples demonstrate the development of the 'Diagnostic Requirements for Digital Radiographic Procedures'. These examinations include projection radiographs with digital luminiscent radiography, fluoroscopic procedures with digital image intensifier radiography and angiographic procedures with digital subtraction angiography. The clinical question of a radiological examination also forms the background to optimisation strategies considering image quality and radiation dose.

European Union↗
PubMed2000

Flexible tantalum stents for the treatment of renovascular hypertension: a 10-year experience.

The aim of this study was to determine long-term success of flexible tantalum stents for the treatment of ostial and truncal renal artery stenosis. Since 1989, flexible tantalum stents (type Strecker) were implanted in 34 patients (36 arteries, 25 ostial lesions, 11 truncal lesions) with uncontrollable renovascular hypertension, 9 of them in association with renal insufficiency. Stents were placed unilaterally in 32 patients, and bilaterally in 2 patients for the treatment of renal artery stenosis. Thirty-five of 36 lesions were atherosclerotic, including 5 recurrencies after previous percutaneous transluminal renal angioplasty (PTRA). One patient had Takayasu arteritis. Stents were implanted after unsuccessful PTRA of 11 truncal and 23 ostial lesions, and as a primary procedure in 2 ostial lesions. Follow-up examinations included blood pressure measurement, determination of serum creatinine level, color duplex sonography, or angiography. The technical success rate was 92%. Technical failure included incorrect stent placement (1 of 36 lesions, 2.8 % ), and stent dislocation (2 of 36 lesions, 5.6 %), and two stents were retrieved percutaneously. In one case of Takayasu arteritis, residual stenosis of 40% was observed. After technically successful stent placement, 77% of patients became normotensive with or without medication. In the remaining patients there was partial improvement with blood pressure between 140 and 180 mmHg. Renal function improved in 76% of patients (completely in 3 of 8, 38%; and partially in 3 of 8, 38%). Primary patency rate including all stented lesions and initial technical failures was 82.4% +/- 6.8 (1 year) and 82.4% +/- 9.2 (3 years). After technically successful stent placement, patency rates were 89.9 +/- 5.6% (1 year), and 89.9 +/- 7.6% (3 years). For ostial lesions, primary patency rate was 87.9 +/- 6.7% (1 year) and 87.9 +/- 9.2% (3 years). Placement of flexible tantalum stents in renal arteries is technically demanding, especially in ostial lesions. Once placed successfully stent patency rate is excellent.

Aged↗
PubMed2000

Treatment with a combined endothelin A/B-receptor antagonist does not prevent chronic renal allograft rejection in rats.

A markedly increased expression of endothelin (ET)-1 has been observed in renal allografts with chronic rejection, one of the most common causes of kidney graft loss. In this study we investigated the effect of treatment with a combined ET-A/B-receptor antagonist on the course of chronic renal allograft rejection. Experiments were performed in the Fisher-to-Lewis rat model of chronic rejection. Lewis-to-Lewis isografts and uninephrectomized Lewis rats served as controls. Animals were treated with either the oral combined ET-A/B-receptor antagonist LU224332 (20 mg/kg/day) or vehicle. Animal survival, blood pressure, creatinine clearance, proteinuria, and urinary ET excretion were investigated for 24 weeks. Kidneys were removed for light-microscopic evaluation and immunohistochemical assessment of cell-surface markers. Treatment with LU224332 did not improve survival after 24 weeks (0.47 vs. 0.38; p > 0.05 by log-rank test), nor did it have an influence on blood pressure, creatinine clearance, or proteinuria. Combined ET-A/B-receptor blockade was associated with a reduction of expression of cell-surface markers for macrophages (EDI), T-cells (R73), and major histocompatibility complex (MHC) II (F17-23-2), but did not lead to an improvement of histologic changes of chronic allograft rejection. Our data show that blocking both ET-A- and -B receptors, in opposition to a previously published beneficial effect of selective ET-A blockade, does not prevent the progression of chronic renal allograft rejection and does not prolong survival in this model. Functional integrity of the ET-B receptor therefore seems to play an important role in the nephroprotection provided by selective ET-A-receptor antagonists in chronic renal allograft nephropathy.

Animals↗
PubMed1999

Serine/threonine phosphorylation of calmodulin modulates its interaction with the binding domains of target enzymes.

The interaction of serine/threonine-phosphorylated calmodulin with synthetic peptides corresponding to the calmodulin-binding domains of six enzymes has been studied by fluorescence spectroscopy. For five peptides, the dissociation constant of the calmodulin-peptide complex (K(d)) increased when calmodulin was phosphorylated. An increase of more than one order of magnitude was observed with peptides derived from smooth-muscle myosin light-chain kinase and cAMP phosphodiesterase. In contrast, only a slight increase in K(d) was noted with two peptides derived from the plasma membrane Ca(2+)-ATPase and for the peptide derived from nitric oxide synthase. No significant change in affinity was detected with the peptide derived from calcineurin. In contrast, a decrease in the dissociation constant was observed with the peptide derived from the Ca(2+)-calmodulin dependent kinase II. Phosphorylation also affected the peptide-calmodulin binding stoichiometry: a decrease from two to one binding sites was observed with the peptides derived from myosin light-chain kinase and phosphodiesterase.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1999

Prevention of chronic renal allograft rejection in rats with an oral endothelin A receptor antagonist.

BACKGROUND: Chronic rejection is the most common cause of graft loss in renal transplantation. The pathomechanisms underlying chronic rejection are poorly understood, and no treatment has yet successfully been established. We hypothesized that, in analogy to models of reduced renal mass, the administration of a selective endothelin (ET) A receptor antagonist could improve the course of chronic rejection in renal allografts. METHODS: Experiments were performed in the Fisher-to-Lewis rat model of chronic rejection. Lewis-->Lewis isografts served as controls. Animals were treated with either the oral selective ET-A receptor antagonist LU135252 (50 mg/kg/day) or vehicle. Animal survival, blood pressure, creatinine clearance, proteinuria, and urinary ET excretion were investigated for 24 weeks. Kidneys were removed for light microscopical evaluation, determination of ET mRNA expression and tissue protein concentration, and immunohistochemical assessment of cell surface markers. RESULTS: Rats with chronic rejection showed an increase in renal ET mRNA synthesis and ET protein content. Treatment with LU135252 resulted in a significant improvement in survival after 24 weeks (0.92 vs. 0.38, P<0.01 by log-rank test). Creatinine clearance was higher in animals treated with the selective ET-A receptor antagonist (P<0.05). LU135252 had no influence on blood pressure and proteinuria. Selective ET-A blockade was associated with significantly less morphological changes and a significant reduction of expression of cell surface markers for macrophages (ED1), T cells (R73), and MHC II (F17-23-2). CONCLUSION: The renal ET-A system plays an important role in the pathomechanisms underlying chronic renal allograft rejection, because the treatment with a selective ET-A receptor antagonist dramatically improves the course of chronic renal failure after allograft transplantation. These results offer a novel therapeutical option for treatment of chronic renal allograft rejection, for which so far no therapy is known.

Administration, Oral↗
PubMed1999

Tryptanthrins and other tryptophan-derived agonists of the dioxin receptor.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and related environmental pollutants exert most of their adverse effects via the aryl hydrocarbon or dioxin receptor (AhR). While most potent agonists of the AhR are of synthetic origin, an increasing number of natural compounds is now recognized as receptor agonists. Our findings demonstrate that some tryptanthrin derivatives biosynthesized in incubations of Candida lipolytica with tryptophan and anthranilic acid or its derivatives activate the AhR measured as induction of cytochrome P4501A1 mRNA and protein in rat hepatocytes in primary culture. The specificity of the inducing effect of tryptanthrins was demonstrated in gel retardation experiments in Hepa-1 mouse hepatoma cells using an oliogonucleotide comprising the sequence of the dioxin-responsive element. Furthermore, unidentified AhR agonists were formed in incubations of rat feces with a minimal medium supplemented with tryptophan. It is suggested that the receptor may be part of a defense system protecting higher organisms from secondary tryptophan-derived metabolites formed by the microflora of the host or its environment.

Animals↗
PubMed1999

Matrix-assisted laser desorption/ionization mass spectra reflect solution-phase zinc finger peptide complexation.

The complexation between an 18-residue zinc finger peptide of CCHC type (CCHC = Cys-X2-Cys-X4-His-X4-Cys, X = variable amino acid) from the gag protein p55 of human immunodeficiency virus type 1 (HIV-1) and various transition metal ions was studied by means of circular dichroism spectroscopy and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). A correlation between the complexation behavior in solution and in MALDI-MS could be established. It was shown that MALDI-MS is a fast method suitable for studying metal binding properties of zinc finger complexes.

Amino Acid Sequence↗
PubMed1999

[Dose-dependent decrease of the rate of restenosis of stents in peripheral vessels with reviparin].

PURPOSE: In clinical prospective trials, we examined the effect of the low molecular weight heparin (lmwh) reviparin on restenosis rate after Strecker stent implantation in femoral popliteal arteries. MATERIALS AND METHODS: 62 patients were treated between 1992 and 1998. Patients received reviparin, 3500 IU, prior to stent implantation followed by 7500 IU for 24 h (i.v.) and 2 x 1750 IU/day s.c. over three weeks (n = 12) or 10,500 IU for 24 h (i.v.) and 2 x 3500 IU/day s.c. over 3 1/2 weeks (n = 50). Follow-up parameters were clinical symptoms, ankle-brachial index, color Doppler flow duplex sonography, and DSA. RESULTS: Three thrombotic occlusions and three stenoses were observed in the low-dose group. Raising the dose resulted in neither thrombotic nor other events within the first three months. Seven stenoses occurred afterwards up to the 7th month. The complication rate was low: one moderate hematoma and one puncture aneurysm. Primary patency rate was 88% and 80% for one and two years, respectively. This is significantly better than the primary patency rates for patients receiving low-dose lmwh (p < 0.005) or unfractionated heparin (p < 0.05). CONCLUSIONS: Hence, high-dose administration of the lmwh reviparin lowers the restenosis rate after stent implantation in femoropopliteal arteries.

Aged↗
PubMed1998

Characterization of a calcium-dependent calmodulin-binding domain in the 135-kD human protein 4.1 isoform.

The putative calmodulin binding domain of non-erythroid protein 4.1, previously suggested by Kelly et al. [Kelly, G. M., Zelus, B. D. & Moon, R. T. (1991) J. Biol. Chem. 266, 12469-12473] has been synthesized, and its binding to calmodulin has been studied by fluorescence spectroscopy. For this purpose, the peptide has been N-terminally dansylated. The 4.1 peptide Dns-Abu-S76RGLSRLFSSFLKRPKS92, binds calmodulin in a calcium-dependent way with high affinity (Kd = 23 +/- 6 nM). The peptide inhibits bovine-heart phosphodiesterase with an IC50 of 50 nM. Since the sequence of the peptide shows two putative consensus sites of phosphorylation by cAMP-dependent protein kinase or Ca2+-calmodulin protein-kinase II, the interaction of the two mono-phosphorylated peptides (P4.1 Ser(80-P) and P4.1 Ser(84-P)) and the di-phosphorylated peptide (P4.1 Ser(80-P)/Ser(84-P)) with calmodulin has been investigated. A decrease of affinity by a factor 1.5-8 has been observed for the phosphorylated peptides. CD measurements have shown an increase of the content of alpha helices in the peptides when bound to calmodulin.

Amino Acid Sequence↗