Biomedical subjects

A Werner

Publications and source records attributed to A Werner.

At least 19 recordsLinked to original sources

PubMed2005

Novel mechanism of anomalous electron heat conductivity and thermal crashes during Alfvénic activity in the Wendelstein 7-AS stellarator.

Enhanced plasma heat conductivity in the presence of kinetic Alfvén waves (KAW) is predicted theoretically. The enhancement is shown to be strongest when the electron collision frequency exceeds the particle transit frequency in the wave field. Alfvén waves (both KAW and ideal MHD Alfvén eigenmodes generating the KAW) are studied in a shot of the Wendelstein 7-AS stellarator. On the basis of these results, strong thermal crashes observed during bursting Alfvénic activity in the mentioned shot are explained.

Journal Article↗

PubMed2005

[Switching sickness funds and risk compensation mechanisms in the statutory health insurance system in Germany--empirical results from the cooperative health research in the region of Augsburg (KORA)].

Since 1996, all citizens of the Federal Republic of Germany who are insured in the statutory health insurance system are entitled to switch their sickness fund. The rationale of this regulation was to strengthen elements of competition in this system in order to stimulate the sickness funds to improve the efficiency of health care and to respond to consumers' preferences. Simultaneously, to avoid the implicit incentives for sickness funds to engage in risk selection, a risk compensation mechanism was introduced, including as morbidity-related risk adjusters age, sex and incapacity to work. Based on the KORA survey S4 (1999/2001) we take the case of switching behaviour in the region of Augsburg, and analyse whether this risk adjustment scheme was working effectively. The results show that persons changing their sickness fund were characterised by a comparatively smaller burden of chronic diseases and by a less frequent utilization of inpatient health care. Under these conditions, differences in the contribution rates do not accurately reflect differences in the performance and efficiency of sickness funds. Moreover, the migration of good risk to sickness funds with favourable contribution rates threatens the principle of financial solidarity. Therefore, the system of risk equalisation has to be developed towards measuring the risk volume borne by the sickness funds more precisely than hitherto.

Adult↗

PubMed2005

The effect of suture materials and techniques on the outcome of repair of the rotator cuff: a prospective, randomised study.

In a prospective, randomised study on the repair of tears of the rotator cuff we compared the clinical results of two suture techniques for which different suture materials were used. We prospectively randomised 100 patients with tears of the rotator cuff into two groups. Group 1 had transosseous repair with No. 3 Ethibond using modified Mason-Allen sutures and group 2 had transosseous repair with 1.0 mm polydioxanone cord using modified Kessler sutures. After 24 to 30 months the patients were evaluated clinically using the Constant score and by ultrasonography. Of the 100 patients, 92 completed the study. No significant statistical difference was seen between the two groups: Constant score, 91% vs 92%; rate of further tear, 18% vs 22%; and revision, 4% vs 4%. In cases of further tear the outcome in group 2 did not differ from that for the intact repairs (91% vs 91%), but in group 1 it was significantly worse (94% vs 77%, p = 0.005). Overall, seven patients had complications which required revision surgery, in four for pain (two in each group) and in three for infection (two in group 1 and one in group 2).

Adult↗

PubMed2004

[Pain management in non-juvenile, aseptic osteonecrosis].

BACKGROUND: Adult aseptic osteonecrosis (ON) represents a clinical picture with unexplained etiology. Since curative treatment of this disease often succeeds only in the early stage, pain therapy plays an important role in the treatment process. METHOD: We compared established and novel treatment options for ON as well as our own results after i.v. administration of the prostacyclin analogue iloprost with corresponding studies in the literature. RESULTS: In addition to treatment with nonsteroidal antirheumatic agents and opioids, surgical "core decompression," vasoactive medications, and hyperbaric oxygenation are effective. Treatment with iloprost for 5 days resulted in highly significant pain reduction. CONCLUSION: Symptomatic treatment is indicated in all stages of ON and curative treatment in stage I and early stage II. In cases of disease progression in the large joints, early endoprosthetic replacement is indicated to avoid secondary damage. In addition to employing vasoactive substances, a further curative treatment approach could be the use of mesenchymal stem cells.

Adult↗

PubMed2004

Estimation of vasodilator response by analysis of Doppler intensity kinetics with myocardial contrast echocardiography using an intravenous standardized bolus administration.

HYPOTHESIS: Myocardial perfusion can be analyzed by the first pass of Doppler intensity (DI) signals in the myocardium by myocardial contrast echocardiography with triggered power Doppler harmonic imaging (PDHI). METHODS AND RESULTS: DI versus time plots during 1:1 triggering was acquired during a mechanically standardized intravenous bolus application of Levovist (400 mg ml(-1); 3 ml min(-1)) at rest and during vasodilator stress with dipyridamole. Data were analyzed in 21 patients (pts) with normal coronary arteries and in 6 pts with left anterior descending artery (LAD) stenosis. Transthoracic distal LAD-flow velocities could be determined in 7 normal pts. At stress the DI wash-in rate and the DI plateau increased (3.14+/-0.3 versus 5.06+/-0.4 DI s(-1); 24.6+/-2.5 versus 30.8+/-1.8 DI, respectively). To analyze the effect of heart rate on the DI versus time plots investigations were performed in 7 additional controls at rest and during rapid pacing. Heart rates below 100 bpm did not disturb the DI kinetics at 1:1 triggering. CONCLUSIONS: Myocardial perfusion can be assessed by the analysis of the first pass DI kinetics using Levovist. The estimation of vasodilator response by PDHI seems to be an alternative to the determination of coronary flow reserve.

Aged↗

PubMed2004

[Primary diagnostics of acute diverticulitis of the sigmoid].

AIM: The initial diagnostics of acute diverticulitis of the sigmoid should render the correct diagnosis as well as assisting in the decision on the options of conservative or surgical treatment by ruling out or demonstrating complications. At present, sonography or computed tomography (CT) are the two competing diagnostic options. This study was designed to demonstrate that sonography could be used as the method of choice. METHOD: 63 patients with clinical suspicion of acute diverticulitis of the sigmoid were examined initially by sonography or CT in a prospective study. RESULTS: Sonography and CT showed a 97 % sensitivity and specificity for reaching the accurate and clinically plausible diagnosis. As to the demonstration of complications of the disease, sensitivity and specificity were comparably high for both diagnostic methods. CONCLUSIONS: Sonography can compete with the more complex CT examination and therefore represents the recommended primary diagnostic procedure.

Aged↗

PubMed2004

[Growth behaviour of human mononuclear cells derived from bone marrow and cord blood on a collagen carrier for osteogenic regeneration].

UNLABELLED: We investigated the biocompatibility and osteogenetic potency of a porcine collagen I/III carrier in a human bone marrow and cord blood cell culture system. METHODS: Human mesenchymal mononuclear cells were isolated from cord blood and iliac crest bone marrow and cultivated in various cell densities on a semipermeable porcine collagen I/III carrier. After 14 days of in vitro cultivation both cultures were subjected to osteogenic stimulation by dexamethasone, ascorbic acid and beta-glycerol phosphate (DAG) until day 40. Semiquantitative immunochemical evaluation based on osteoblastic and progenitor cell markers was then done. RESULTS: With regard to the minimal local cell density required for growth and osteogenic differentiation, cord blood derived progenitor cells showed lower tolerance in comparison with bone marrow derived cells. For both cell culture systems three-dimensional growth and calcification within the collagen fibres were seen after osteogenic stimulation. CONCLUSION: Human cord blood and bone marrow derived mesenchymal stem cell are capable of differentiating into osteoblasts after incubation with a collagen I/III biomaterial.

Animals↗

PubMed2003

Dietary P regulates phosphate transporter expression, phosphatase activity, and effluent P partitioning in trout culture.

Phosphate utilization by fish is an important issue because of its critical roles in fish growth and aquatic environmental pollution. High dietary phosphorus (P) levels typically decrease the efficiency of P utilization, thereby increasing the amount of P excreted as metabolic waste in effluents emanating from rainbow trout aquaculture. In mammals, vitamin D3 is a known regulator of P utilization but in fish, its regulatory role is unclear. Moreover, the effects of dietary P and vitamin D3 on expression of enzymatic and transport systems potentially involved in phosphate utilization are little known. We therefore monitored production of effluent P, levels of plasma vitamin D3 metabolites, as well as expression of phosphatases and the sodium phosphate cotransporter (NaPi2) in trout fed semipu diets that varied in dietary P and vitamin D3 levels. Mean soluble P concentrations varied markedly with dietary P but not with vitamin D3, and constituted 40-70% of total effluent P production by trout. Particulate P concentrations accounted for 25-50% of effluent P production, but did not vary with dietary P or vitamin D3. P in settleable wastes accounted for <10% of effluent P. The stronger effect of dietary P on effluent P levels is paralleled by its striking effects on phosphatases and NaPi2. The mRNA abundance of the intestinal and renal sodium phosphate transporters increased in fish fed low dietary P; vitamin D3 had no effect. Low-P diets reduced plasma phosphate concentrations. Intracellular phytase activity increased but brushborder alkaline phosphatase activity decreased in the intestine, pyloric caeca, and gills of trout fed diets containing low dietary P. Vitamin D3 had no effect on enzyme activities. Moreover, plasma concentrations of 25-hydroxyvitamin D3 and of 1,25-dihydroxyvitamin D3 were unaffected by dietary P and vitamin D3 levels. The major regulator of P metabolism, and ultimately of levels of P in the effluent from trout culture, is dietary P.

6-Phytase↗

PubMed2003

Multi-slice spiral CT in routine diagnosis of suspected acute left-sided colonic diverticulitis: a prospective study of 120 patients.

This prospective study evaluated the use of multi-slice CT (MSCT) for detection of clinically suspected left-sided colonic diverticulitis with regard to diagnosis, complications and alternative diagnoses. One hundred twenty patients with clinically suspected acute left-colonic diverticulitis underwent MSCT of the lower abdomen with IV contrast after rectal application of iodic contrast. The MSCT results were compared with histopathological and intraoperative findings or other radiological or endoscopic methods and clinical outcome. Acute diverticulitis was proven in 67 of the 120 (55.8%) patients, which was detected by MSCT with an accuracy of 98% (sensitivity 97%, specificity 98%). Contained perforation or abscess formation were detected with an accuracy of 96% (sensitivity 100%, specificity 91%) and 98% (sensitivity 100%, specificity 97%), respectively. In 31 of 120 (25.8%) patients diagnoses other than diverticulitis caused abdominal pain, which was correctly diagnosed by MSCT in 71%. The MSCT as well as other concurrently performed diagnostic methods showed normal findings and no causes for the patients symptoms in 22 of the 120 (18.4%) patients. Multi-slice CT is reliable in detecting diverticulitis, including extracolic complications, and often reveals other diagnoses; therefore, MSCT is recommended as standard diagnostic procedure in suspected acute diverticulitis.

Acute Disease↗

PubMed2003

[Intraarticular pathology of atraumatic shoulder dislocations. An arthroscopic study].

AIM OF THE STUDY: According to the literature, atraumatic shoulder dislocations occur without or only minor trauma,self-reduction and no or little pain. Little is known about intraarticular pathology in this entity. It was the purpose of our study to evaluate such findings. METHODS: During a 2-year period,226 patients had surgery for shoulder dislocation.28 patients met the criteria for atraumatic dislocation as above (group A). Patients with bony pathology or recurrent microtrauma were excluded. All had been treated with a rehabilitation program without success.28 consecutive patients with surgery after posttraumatic dislocation served as a control group (group B). At the beginning of the surgery,arthroscopy was performed in all patients and the intraarticular findings were recorded. For the capsulo-labral pathology,we determined 3 types: type I had capsular elongation or scarring and included so called "non-Bankart-lesions"; type II had classic "Bankart"-lesions and type III more complex capsulo-labral lesions like e.g. "ALSPA"-lesions. RESULTS: The mean age in group A was 27.6 y and 26.2 y in group B.12 patients in group A and 5 in group B were female. The average no.of dislocations was 10 (1-30) or 9 (1-28), respectively. In group A we saw type I lesions in 11 patients (39.3%), type II lesions in 9 (32.1%) and type III lesions in 8 (28.6%) patients. In group B we found type I lesions in 8 (28.6%), type II lesions in 4 (14.3%) and type III lesions in 16 (57.1%) patients.Hill-Sachs lesions were found in 22 (78.6%) and 23 (82.1%) of the patients, respectively.Also, we saw chondral glenoid damage, cuff lesions and SLAP-lesions in both groups. CONCLUSION: The above mentioned criteria for atraumatic shoulder dislocation do not exclude intraarticular pathology comparable to posttraumatic cases, at least for patients, who do not respond to a conservative treatment. Besides the etiology, the given pathology must be considered for therapy.

Adult↗

PubMed2003

[Detection of prostate carcinomas with T1-weighted dynamic contrast-enhanced MRI. Value of two-compartment model].

AIM: The suitability of dynamic parameters of the two-compartment model for detecting prostate carcinomas and its correlation with tumor microvascular density were evaluated. METHODS: The study included 43 patients with biopsy-proven prostate carcinoma: 28 were examined by 1.0-T MRI (Turbo-FLASH) and 15 by 1.5-T MRI (FLASH) with infusion of 0.1 mmol/kg Gd-DTPA. Signal time curves were parametrized with an open two-compartment model in amplitude and exchange rate constants (k(ep)). The microvascular density of resected prostate carcinomas was determined. RESULTS: The microvascular density in the tumors was significantly higher than in the adjacent healthy prostate tissue and correlated in both sequences with k(ep). Prostate carcinomas of the peripheral zone were demarcated by amplitude and k(ep). In the Turbo-FLASH sequence there was a significant difference between the tumor tissue and healthy peripheral zone in terms of k(ep) and in the FLASH sequence in terms of amplitude. CONCLUSION: Prostate carcinomas can be visualized with dynamic T1-weighted MR sequences using a two-compartment model. Moreover, the parameter k(ep) reveals the microvascular density in the tumor and can thus provide valuable clinical information for characterizing the tumors.

Biopsy↗

PubMed2003

[Tendinitis of the long head of biceps tendon associated with lesions of the "biceps reflection pulley"].

UNLABELLED: In some patients with persistent pain around the Long Head of Biceps Tendon (LHB), lesions of the "biceps reflection pulley", associated with biceps tendinitis, can be found. The aim of this study is to describe the anatomy of the reflection pulley and the arthroscopic appearance of the pulley lesion. Therapeutic options will be discussed. METHOD: The results of a former histo-anatomic study done by the authors in 13 cadaver shoulders are compared with the intra-operative findings in patients with persistent tendinitis of the LHB together with a lesion of the reflection pulley and signs of LHB instability. Intra-operative findings from patients with either posttraumatic anterior instability or calcific tendinitis served as control. RESULTS: The superior glenohumeral ligament (SGHL) together with the coraco-humeral ligament (CHL) and fibers from the subscapularis and supraspinatus tendons form a stabilizing reflection pulley for the LHB in the rotator cuff interval. Arthroscopy shows an association between a lesion of this pulley and persistent LHB-tendinitis. Pulley lesions can occur as isolated ligamentous pathology or together with a partial detachment of rotator cuff tendons. CONCLUSION: In patients with therapy-resistant pain around the LHB, lesions of the reflection pulley need to be excluded beside more common causes of biceps problems. Arthroscopy is a reliable tool to assess these lesions. Therapy should address the definite pathology.

Adult↗

PubMed2003

[Ultrasonographic evaluation of the rotator cuff after shoulder arthroplasty].

AIM: Ultrasonography of the rotator cuff tendons is a standard imaging technique. Although increasing numbers of shoulder arthroplasty are performed, there is no available data concerning the use of ultrasound after shoulder replacement. Our experimental study was performed to analyse the value of ultrasonography after shoulder arthroplasty a) in an ex-vivo-setting and b) in a retrospective analysis of our patients after shoulder hemiprothesis. METHOD: After defrosting, anatomic modular humeral head replacement was performed in four fresh-frozen specimens with intact rotator cuffs. The supraspinatus and subscapularis tendons of each specimen were either detached to simulate a cuff defect or reattached anatomically (four times per specimen). Two experienced examiners then performed ultrasonography to evaluate the two tendons to be either intact or deficient. In a retrospective study, 22 patients with 25 hemiprotheses of the shoulder underwent clinical and sonographic examination. For documentation of the clinical findings, the Constant score was used. RESULTS: In the cadaver study, the reliability of the method was slightly higher for the subscapularis tendon (13 correct, 3 false results) than for the supraspinatus tendon (12 correct, 4 false results). In our patients, rotator cuff defects and effusions around the biceps tendon and in the subdeltoid bursa could be detected. Normal sonograms correlated with good clinical results. CONCLUSION: In the cadaver study, we found a good reproducibility of in-vivo conditions. We believe that ultrasonography is beneficial in follow-up evaluation after shoulder arthroplasty.

Arthroplasty↗

PubMed2002

Characterization of a type IIb sodium-phosphate cotransporter from zebrafish (Danio rerio) kidney.

Zebrafish (Danio rerio) express two isoforms of the type IIb Na-dependent P(i) cotransporter (NaPi). Type NaPi-IIb1 has previously been cloned and characterized. Here, we report the cloning of the NaPi-IIb2 transcript from zebrafish kidney, its localization, and its functional characterization. RT-PCR with renal RNA and degenerate NaPi-IIb-specific primers resulted in a specific fragment. 3'-Rapid amplification of cDNA ends yielded a product that contained typical NaPi-IIb characteristics such as a cysteine-rich COOH terminus and a PDZ (PSD95- Dlg-zona occludens-1) binding motif. Several approaches were unsuccessful at cloning the 5' end of the transcript; products lacked an in-frame start codon. The missing information was obtained from an EST (GenBank accession number ). The combined clone displayed a high degree of homology with published type IIb cotransporter sequences. Specific antibodies were raised against a COOH-terminal epitope of both NaPi-IIb1 and NaPi-IIb2 isoforms. Immunohistochemical mapping revealed apical expression of both isoforms in zebrafish renal and intestinal epithelia, as well as in bile ducts. The novel clone was expressed in oocytes, and function was assayed by the two-electrode voltage-clamp technique. The function of the new NaPi-IIb2 clone was found to be significantly different from NaPi-IIb1 despite strong structural similarities. NaPi-IIb2 was found to be strongly voltage sensitive, with higher affinities for both sodium and phosphate than NaPi-IIb1. Also, NaPi-IIb2 was significantly less sensitive to external pH than NaPi-IIb1. The strong structural similarity but divergent function makes these zebrafish transporters ideal models for the molecular mapping of functionally important regions in the type II NaPi-cotransporter family.

Amino Acid Sequence↗

PubMed2002

The value of ultrasound after shoulder arthroplasty.

OBJECTIVE: This study was undertaken to evaluate whether sonography is a useful tool in the diagnosis of soft tissue disorders as a possible cause for discomfort and/or pain after shoulder arthroplasty. DESIGN AND PATIENTS: Static and dynamic ultrasound examinations were performed in the standard sectional planes on 22 patients with 25 hemiprostheses and the results were correlated with the clinical outcome. The stability was determined in the transverse and frontal planes and the clinical results were evaluated according to the Constant and Swanson scores. RESULTS: Several pathological changes were detected: rotator cuff lesions, subdeltoid bursitis, changes around the long biceps tendon as well as an increase in intra-articular volume due to effusion and/or synovitis. The correlation of sonographic and clinical results demonstrated that patients with an excellent clinical result showed no or only a few pathological findings on sonography compared with those with a moderate or poor result. CONCLUSION: Pathological changes of the periarticular tissue in the direct neighbourhood of the implant can be detected by sonography, which can be recommended as a valuable examination technique to evaluate the soft tissue in patients after shoulder arthroplasty.

Adult↗

PubMed2002

New advanced operational regime on the W7-AS stellarator.

A promising new plasma operational regime on the Wendelstein stellarator W7-AS has been discovered. It is extant above a threshold density and characterized by flat density profiles, high energy and low impurity confinement times, and edge-localized radiation. Impurity accumulation is avoided. Quasistationary discharges with line-averaged densities n(e) to 4 x 10(20) m(-3), radiation levels to 90%, and partial plasma detachment at the divertor target plates can be simultaneously realized. Energy confinement is up to twice that of a standard scaling. At B(t) = 0.9 T, an average beta value of 3.1% is achieved. The high n(e) values allow demonstration of electron Bernstein wave heating using linear mode conversion.

Journal Article↗

PubMed2002

[Kapandji intramedullary wire osteosynthesis in proximal humeral fractures].

For operative treatment of proximal humeral fractures minimal invasive techniques reduce the risk of iatrogenic damage of blood supply and periarticular scarring. Reported preliminary results are encouraging. We present our experience achieved with an intramedullary wire fixation adapted from a report of Kapandji in 1989. Between 3/95 and 6/00 29 patients were treated with this technique at our institution. All received early functional treatment. 14 patients (average mean age 56 years at time of trauma) who had a minimum follow up of 24 months (mean 36.4 months) and therefore allowed a preliminary conclusion regarding avascular head necrosis (AVN) were reexamined by use of the Constant Score and x-ray. We examined three unstable 2-part, four 3-part and seven 4-part fractures (5 of them valgus-impacted). The mean Constant Score at follow up was 70 points (31-86 points). We saw one total collapse of the humeral head because of AVN. In one patient the distal end of the wires led to a skin irritation and had to be shortened. We observed no secondary fragment displacement or non-unions. In our hands, this technique offers good results, even in valgus-impacted 4-part fractures of the elderly and allows internal fixation in little displaced but unstable fractures with the benefit of early functional treatment instead of longer immobilization. Based on the experience with intramedullary wiring the previously performed technique using threading wires was abandoned and the indication for primary arthroplasty considerably influenced.

Adult↗

PubMed2002

[Use of a newly developed piezoelectrically driven drilling machine for MR-guided bone biopsies].

PURPOSE: Development and clinical testing of an MR-compatible bone biopsy system, to enable the sample collection from osteosclerotic or subcortical lesions for histological investigation under MR control. MATERIALS AND METHODS: A piezoelectrically driven drilling machine was constructed and tested in connection with an MR-compatible bone biopsy set in a vertical open MR scanner (0.5 T) on a phantom and 10 patients with ambiguous bone lesions. Images were obtained using T(1)-weighted spin-echo sequences and, in case of real-time imaging, a fast spoiled gradient-echo sequence. RESULTS: The influence of the enabled motor (RF-interference) leads to a reduction of the signal to noise ratio of the images, but can be minimised by appropriate measures. The observed slight field distorsions do not affect the image quality during real time acquisition in a substantial manner. No complications occurred. The extracted biopsy material was sufficient and of good quality. CONCLUSIONS: In spite of slightly restricted image quality, the described drilling machine combined with the bone biopsy set is well suited for MR-guided bone biopsies, which require the application of a motor driven drill. Its application within an interventional MR scanner is safe and its handling simple and manageable.

Biopsy, Needle↗