Biomedical subjects
Publications and source records attributed to E Nagel.
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With cardiovascular magnetic resonance imaging (CMR), the necessity of invasive coronary angiography may be increasingly avoided. CMR provides information about the anatomy of the coronaries themselves (e.g. anomalies, aneurysm), functional information on myocardial blood flow (dobutamine-stress-MR, perfusion measurement) and detailed information on cell-mediated alterations (e.g. fibrosis, necrosis). However, visualization of distal coronary vessels and the small side branches is not yet adequate, so that complete replacement of invasive coronary angiography by CMR is not possible.
AIM: The study investigated the variance of the retinal vessel response to flicker light between the right and left eyes and after a short and a medium-length time interval. METHODS: The prospective study included 28 volunteers. In the first exam both eyes were examined. One eye selected randomly was measured again after 1 h and after 1 month. The diameter response of an arterial and venous vessel segment was measured continuously by a Dynamic Vessel Analyzer (DVA, IMEDOS, Jena). Each examination consisted of 50 s baseline measurement and three periods of 20-s flicker light provocation followed by 80 s observation. The mean of three provocational cycles was calculated as dynamic vessel response. RESULTS: A significant correlation of the flicker response parameters between the right and left eyes was found. Arterial and venous baseline diameter, flicker light dilation, AVDQ, and BP did not change significantly between the first and follow-up examinations. There was no correlation between changes of BP and changes of vessel diameter parameters in the follow-up exams. CONCLUSION: Flicker-evoked dilation of retinal arterioles measured by the DVA is characterized under similar conditions by small variance after short and medium-length time periods. Therefore, this parameter is suitable as a functional parameter of the regulation ability of retinal arteries.
"Social marketing" is the use of marketing principles to design and implement programmes to promote socially beneficial behaviour changes. In the field of health promotion and prevention, the systematic planning process of social marketing can offer new ideas and perspectives to the traditions of social science. Major characteristics of social marketing encompass continuous market research focussing on attitudes, motives and behavioural patterns of the target group, an integrated mix of strategic key elements, and the perpetual evaluation of all procedures. So far, however, it is unclear in how far social marketing is actually more effective than other concepts of programme planning. Furthermore, it has to be discussed whether the underlying philosophy of social marketing and its implicit understanding of relationships to the public are reconcilable with health promotion principles. In Anglo-Saxon countries, the social marketing concept has achieved widespread application and is subject to controversial scientific discussions, whereas this approach is hardly considered in German health promotion research and practice. Given the increasing call for quality management and evaluation of health promotion interventions, the social marketing concept may contribute useful insights at an operational level and thus add to a discussion on effective approaches for programme planning.
BACKGROUND: Although colorectal cancer is the second leading cause of cancer death in Germany, screening rates remain low. It is unknown whether local approaches to promoting colorectal cancer screening are effective. This study evaluates the effectiveness of a regional awareness campaign consisting of public information sessions and leaflet distribution, upon the use of colorectal cancer screening by faecal occult blood test (FOBT) and colonoscopy. METHODS: Data on FOBT and colonoscopy were collected by doctors for 12 months following the campaign, including reason for and result of the testing. 37 % (n = 43) of all physicians and practitioners in two administrative districts (249 632 inhabitants) that were exposed to the campaign participated in the study. It was recorded whether the individuals requesting colorectal cancer screening had been prompted by the campaign, so the number and outcome of campaign-related tests was determined. RESULTS: 3398 individuals (male: 54.6 %, female: 45.4 %, age: 64.3 +/- 8.3 years) underwent 3551 screening tests (2446 FOBT, 819 colonoscopy, 133 both). 141 additional diagnostic colonoscopies were performed because of a positive result in the FOBT. Adenomas were detected in 279 individuals, malignancies in 11 individuals. 225 FOBT (8.7 %) and 176 colonoscopies (18.5 %) were performed due to the campaign; among these individuals, 49 had adenoma(s), 1 had carcinoma. The effect could be attributed both to leaflets and to information sessions. The proportion of campaign-related screening tests declined over time. CONCLUSION: The regional information campaign could reach target individuals and motivate them to utilise colorectal cancer screening. The combination of mass media and personal communicative elements seems useful.
PURPOSE: The aim of this study was to compare the diameter response of retinal arteries and veins after provocation with flickering light regarding the amplitude and temporal course. METHODS: The study included 26 healthy volunteers. The vessel diameter was automatically and continuously measured by the retinal vessel analyzer. The examination consisted of a baseline measurement (100 s) followed by five periods of 20-s flicker light provocation and 80-s follow-up observation. RESULTS: A diameter dilation was observed immediately after the end of the flicker period in arteries (6.9+/-2.8%) and veins (6.5+/-2.8%, difference n.s.). The quotient of arterial and venous dilation (AVDQ) was 1.25+/-0.69 (range: 0.2-2.8). A significant correlation of age and arterial or venous dilation or the AVDQ was not observed. The arterial diameter reduced faster than the venous and reached a minimum of -2.7+/-1.4% at 25.9+/-10.8 s after the end of the flicker phase. The veins were dilated by 0.5+/-1.3% at the time of the maximal individual arterial constriction (p<0.0001). CONCLUSIONS: Flicker-evoked response of retinal arteries and veins did not differ in the dilative amplitude but in the temporal course of the abatement of the dilation.
A rare case of a primary fibrosarcoma of the liver infiltrating the right heart is described in a 72-year-old woman. The patient presented with a history of progressive dyspnea and ascites and her general condition was poor. Preoperative cardiac magnetic resonance (CMR) imaging revealed a large mass, which originated from the liver and had infiltrated the right atrium via the inferior vena cava. The patient underwent tumor resection yet died shortly afterwards. Histologically the mass was classified as a fibrosarcoma with positive immunostaining for vimentin. We report the CMR imaging characteristics in this uncommon case. Preoperative CMR proved to be useful for clinical decision making and the planning of surgery.
This ongoing multicenter prospective observational study was undertaken in de novo renal allograft recipients managed with cyclosporine (CsA) trough (C0) and 2-hour postdose (C2) level monitoring at defined times so as to assess the risk for an acute rejection episode or allograft dysfunction. The renal transplant recipients (n = 159) were enrolled at 11 German centers. The 6-month posttransplant data from 138 patients were evaluable for this interim analysis. Mean C2 levels (ng/mL), which were measured by liquid chromatography-tandem mass spectrometry at a central laboratory, were: days 3 to 5: 873.1 +/- 391.9; days 7 to 10: 939.1 +/- 422.8; days 14 to 28: 1116.3 +/- 497.6; 3 months: 905.0 +/- 316.8; and after 6 months: 787.0 +/- 276.5. To identify patients at higher risk for acute rejection or allograft dysfunction, we calculated the relative CsA absorption capacity (C2 [ng/mL]/morning dose [mg/kg]; CsA-Abs), yielding mean values on days 3 to 5: 284.4 +/- 115.1; days 7 to 10: 306.7 +/- 134.8; days 14 to 28: 382.5 +/- 164.7; month 3: 501.5 +/- 168.8; month 6: 512.7 +/- 176.5. Three groups were distinguished by CsA-Abs at days 7 to 10: low absorbers (CsA-Abs < 200), normal absorbers (CsA-Abs 200 to 350), and high absorbers (CsA-Abs > 350). A between-group comparison of absorption level at 6 months posttransplant revealed the incidences of biopsy-proven acute rejection and Cockcroft-Gault formula-based mean glomerular filtration rates of 23.8% and 54.7 +/- 19.0 mL/min, 22.6% and 59.5 +/- 20.7 mL/min, and 17.6% and 67.7 +/- 23.5, respectively. In conclusion, mean C2 levels >1000 ng/mL are attained within 2 to 4 weeks, with CsA-Abs increasing continuously over the first 6 posttransplant months. High CsA absorbers show a propensity toward good allograft function and lower acute rejection rates at 6 months after renal transplantation.
Evidence-based clinical guidelines in surgery are frequently confronted with scepticism by the medical staff, especially because a confinement of free decision making in therapy is expected. Considering that medicine is not merely natural science, but can as well be comprehended as social science or art, evidence-based medicine (EbM) may lead to an oversimplified and rigid standardization in medical care ("cook book medicine"). In addition, scientific progress might be prevented by inflexible guidelines. However, it is important for surgeons to engage in the development of evidence-based guidelines in order to put forward their interests, because it is the lack of medical guidelines that might threaten free decision making in surgery - by not confronting economical pressure with decisive minimal standards in medical care. Therapeutical freedom is a substantial principle in medicine, but it should be considered that according to occidental tradition, "freedom" is necessarily involving reason and conscientiousness.
PURPOSE: Colorectal cancer is the second main cause of cancer death in Germany, although several measures related to primary prevention are described, and the utilisation of existing diagnostic tools (faecal occult blood test = FOBT, colonoscopy) is known to significantly decrease incidence and mortality. However, screening rates remain low in Germany, and insufficient knowledge of prevention possibilities is assumed to be responsible. The aim of this study was to investigate the knowledge related to colorectal cancer prevention in a Bavarian population, in the context of a regional public awareness campaign ("Active against Colorectal Cancer"). METHODS: 618 individuals between 50 and 90 ys of age participated in a telephone survey (m: 219, f: 399, 63.2 +/- 9.17 ys); the participants were inhabitants of two Bavarian districts. The questionnaire consisted of open-ended questions concerning preventive behaviour, colorectal cancer screening, risk factors, early warning signs and knowledge of colorectal cancer information. RESULTS: More than 80% of participants recalled healthy diet as a possible protective factor against colorectal cancer; a distinctly smaller percentage, however, could correctly define concrete dietary factors: e. g., fruit and vegetables were named by 54.5%. 66% of participants knew that unusual rectal bleeding might be a warning sign of cancer. Colonoscopy was the screening test that was most frequently recalled (61.5%); fewer participants named FOBT (32.8%) and rectal examination (11.5%). The results demonstrate that for many knowledge items, females proved to be significantly better informed than males. The most frequent sources of colorectal cancer information were newspapers, magazines, television and/or radio (named by 76.7%), as well as physicians and pharmacies (45.1%). 11.5% of participants attended the regional public awareness campaign "Action against colorectal cancer"; this subgroup had a better knowledge of some aspects related to colorectal cancer prevention. CONCLUSION: Evidently, the interviewed Bavarian population of 50 years or older lack knowledge of risk or protection factors for colorectal cancer. Knowledge of existing screening tests was also poor. These findings can serve as starting point for information campaigns tailored for target groups.
PURPOSE: Different centers and vendors use different sequences and contrast agent application schemes for MR myocardial perfusion imaging. The purpose of this study was to evaluate the role of different sequences, dosages, and injection speeds of contrast media for semiquantitative MR-perfusion assessment. METHODS: In a pilot study with 58 consecutive patients three of the most commonly used sequences for MR myocardial perfusion imaging (T1-GrE, GrE-EPI or SSFP) were compared to each other in terms of peak myocardial enhancement and image quality. For the main part of the study dynamic first pass MR perfusion imaging (Philips Intera CV, Best, Tthe Netherlands) was performed in 24 patients using the most favorable sequence from the pilot study (SSFP) after peripheral i.v. administration of Gd-BOPTA during adenosine stress. Two doses (0.05 mmol/kg bw and 0.025 mmol/kg bw) and four different injection speeds (8, 4, 3, 2 ml/s) were used. Signal intensity time curves were determined in the LV and myocardial segments supplied by normal coronary arteries and correlation between LV and myocardial upslope as well as peak enhancement were noted. RESULTS: The SSFP-sequence showed a higher peak enhancement when using 0.05 mmol/kg bw of Gd-BOPTA and a superior image quality for both dosage regimen compared with the other sequences and was consequently applied for the main study. A significant correlation was found between the upslopes in the LV and the myocardium (r square = 0.85, p < 0.001). However, LV and myocardial upslopes were largely independent of the dosage. Myocardial upslope was significantly slower at an injection rate of 2 ml/s compared to 3 and 4 ml/s. Higher Gd-doses led to significantly higher enhancement (p < 0.001). CONCLUSION: In healthy myocardial segments, the myocardial upslope is mainly determined from the LV upslope. Both myocardial enhancement and upslope are largely independent from the injection rate of a contrast agent bolus as long as the injection speed is not below 3 ml/s. Myocardial enhancement, however, is dose dependent. Thus, a simple correction for LV upslope allows to normalize a wide variety of input parameters. Differences of myocardial upslope or peak signal intensity after correction should be mainly dependent on blood flow.
OBJECTIVES: To validate in vivo a magnetic resonance imaging (MRI) method for measurement of pulmonary vascular resistance (PVR) and subsequently to apply this technique to patients with pulmonary hypertension (PHT). METHODS AND RESULTS: PVR was assessed from velocity encoded cine MRI derived pulmonary artery (PA) flow volumes and simultaneously determined invasive PA pressures. For pressure measurements flow directed catheters were guided under magnetic resonance fluoroscopy at 1.5 T into the PA. In preliminary validation studies (eight swine) PVR was determined with the thermodilution technique and compared with PVR obtained by MRI (0.9 (0.5) v 1.1 (0.3) Wood units.m2, p = 0.7). Bland-Altman test showed agreement between both methods. Inter-examination variability was high for thermodilution (6.2 (2.2)%) but low for MRI measurements (2.1 (0.3)%). After validation, the MRI method was applied in 10 patients with PHT and five controls. In patients with PHT PVR was measured at baseline and during inhalation of nitric oxide. Compared with the control group, PVR was significantly increased in the PHT group (1.2 (0.8) v 13.1 (5.6) Wood units.m2, p < 0.001) but decreased significantly to 10.3 (4.6) Wood units.m2 during inhalation of nitric oxide (p < 0.05). Inter-examination variability of MRI derived PVR measurements was 2.6 (0.6)%. In all experiments (in vivo and clinical) flow directed catheters were guided successfully into the PA under MRI control. CONCLUSIONS: Guidance of flow directed catheters into the PA is feasible under MRI control. PVR can be determined with high measurement precision with the proposed MRI technique, which is a promising tool to assess PVR in the clinical setting.
BACKGROUND: Dobutamine stress MR (DSMR) is highly accurate for the detection of inducible wall motion abnormalities (IWMAs). Adenosine has a more favorable safety profile and is well established for the assessment of myocardial perfusion. We evaluated the diagnostic value of IWMAs during dobutamine and adenosine stress MR and adenosine MR perfusion compared with invasive coronary angiography. METHODS AND RESULTS: Seventy-nine consecutive patients (suspected or known coronary disease, no history of prior myocardial infarction) scheduled for cardiac catheterization underwent cardiac MR (1.5 T). After 4 minutes of adenosine infusion (140 microg x kg(-1) x min(-1) for 6 minutes), wall motion was assessed (steady-state free precession), and subsequently perfusion scans (3-slice turbo field echo-echo planar imaging; 0.05 mmol/kg Gd-BOPTA) were performed. After a 15-minute break, rest perfusion was imaged, followed by standard DSMR/atropine stress MR. Wall motion was classified as pathological if > or =1 segment showed IWMAs. The transmural extent of inducible perfusion deficits (<25%, 25% to 50%, 51% to 75%, and >75%) was used to grade segmental perfusion. Quantitative coronary angiography was performed with significant stenosis defined as >50% diameter stenosis. Fifty-three patients (67%) had coronary artery stenoses >50%; sensitivity and specificity for detection by dobutamine and adenosine stress and adenosine perfusion were 89% and 80%, 40% and 96%, and 91% and 62%, respectively. Adenosine IWMAs were seen only in segments with >75% transmural perfusion deficit. CONCLUSIONS: DSMR is superior to adenosine stress for the induction of IWMAs in patients with significant coronary artery disease. Visual assessment of adenosine stress perfusion is sensitive with a low specificity, whereas adenosine stress MR wall motion is highly specific because it identifies only patients with high-grade perfusion deficits. Thus, DSMR is the method of choice for current state-of-the-art treatment regimens to detect ischemia in patients with suspected or known coronary artery disease but no history of prior myocardial infarction.
INTRODUCTION: Alterations in the intrinsic ocular fundus fluorescence are under discussion particularly in connection with age-related macular degeneration. However, further knowledge of the chemical substrate of fluorescence is necessary. METHOD: Ocular fundus autofluorescence was observed using a fundus camera. The fluorescence emission was recorded using a 3-chip CCD camera. For comparison, the fluorescence spectra of lipofuscin, A2-E, FAD, NADH(2) and AGE's were recorded by the Jena ophthalmo-spectrometer. RESULTS: In contrast to the homogeneous intrinsic fluorescence of a normal fundus, the fluorescence images of patients suffering from AMD showed remarkable local differences. The detected fluorescence spectra showed remarkable overlaps. DISCUSSION: We introduced a new technique enabling the detection of spectral differences in images of ocular fundus autofluorescence. Besides the fluorescence of lipofuscin, we found a green one in patients suffering from nonexudative AMD.
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The strict separation of the out-patient and hospital-based health care delivery sectors in Germany leads to deficits in effectiveness and efficiency. Newly introduced legal initiatives to overcome this separation, namely "Ambulantes Operieren" (section 115 b SGB V), "Ambulante Behandlung durch Krankenhäuser" and Disease Management Programs (sections 116a-b SGB V) are described in detail in this article. Their impact on hospital-based health provision for out-patients is discussed. The aim of a better integration of different sectors with a better quality and a more efficient use of resources seems to be the target of these initiatives.
AIM: To investigate diameter changes in retinal arterioles in response to flicker variations of the examination light. METHODS: One randomised eye of five healthy subjects (mean age 33.8 (SD 1.6) years) was examined. The arterial diameter response to flicker light (12.5 Hz, 530-600 nm, duration 20 seconds) was automatically and continuously measured online three times by retinal vessel analyser (RVA) and once offline from flash images using the VesselMap program. RESULTS: An arterial diameter response to flicker light was found both by RVA and by analysis of flash images (p<0.001). The maximum induced dilation reached at the end of the flicker period was +7.4% (SD 2.4%) in the RVA measurements and +3.5% (0.8%) in the photographs (p = 0.01). In both techniques the vascular diameter overshot the baseline approximately 10 seconds. In the RVA measurements a minimum of -4.6% (1.9%) (p = 0.01) was measured 22 (4.7) seconds after the end of flicker exposure. CONCLUSION: Flicker evoked response for retinal arterioles was found both by RVA and by analysis of flash images. The authors believe that the method is suitable for the quantitative investigation of retinal vasosclerosis, especially in association with arteriosclerotic and hypertensive systemic disease.