Aortic aneurysm and aortic graft infection related to Mycobacterium bovis after intravesical Bacille Calmette-Guérin therapy-a case series.

BACKGROUND: So called "mycotic" aortic aneurysms account for only 0.7 to 1.3% of all aortic aneurysms and are commonly caused by Staphylococcus aureus and Salmonella species. Bacillus Calmette-Guérin (BCG), a live attenuated strain of Mycobacterium bovis, is part of the therapy of non-muscle-invasive bladder cancer (NMIBC). CASE PRESENTATION: We report a case series of three patients with a mycobacterial graft infection related to BCG after surgical treatment of a presumed mycotic aortic aneurysm as an extremely rare complication after NMIBC treatment. All three patients developed aortic aneurysm after BCG instillation and subsequent mycobacterial graft infection. CONCLUSION: Diagnosis requires a high degree of suspicion because of its nonspecific symptoms and imaging. The pathogen is not detected by standard microbiological testing. Treatment includes triple antimycobacterial therapy and radical surgical interventions. Graft preservation may be considered if no anastomosis is involved.

[System and skill utilization in an Austrian emergency physician system: retrospective study]. / System- und Fertigkeitseinsatz in einem österreichischen Notarztsystem: retrospektive Studie.

BACKGROUND: The continuous rise in calls for emergency physicians and the low proportion of indicated missions has led to a loss of job attractiveness, which in turn renders services in some areas unable to sufficiently staff units. This retrospective analysis evaluated the frequency of emergency and general medical interventions in a ground-based emergency physician response system. METHODS: A retrospective analysis of anonymized data from the electronic documentation system of the emergency physician response unit at the Medical University of Graz was carried out. Calls answered by emergency physicians between 2010 and 2018 were extracted, measures carried out were evaluated and categorized into three groups: specific emergency interventions (category I), general medical interventions (category II) and no medical activity (category III). The frequency of occurrence of these categories was compared and incidences of individual measures per 100,000 inhabitants were calculated. RESULTS: A total of 15,409 primary responses and 322 secondary transports were extracted and analyzed. The annual rate of system activation rose almost continuously from 1442 calls in 2010 to 2301 calls in 2018. The 3687 (23.4%) cancellations resulted in 12,044 patient contacts. Of these, 2842 (18%) calls were coded as category I, 7372 (47%) as category II and 5518 (35%) as category III. The frequency of specific emergency measures and general medical interventions was estimated at 157/100,000 and 409/100,000 inhabitants, respectively. CONCLUSIONS: No specific emergency physician interventions were required in the majority of call-outs. The current model of preclinical care does not appear to be patient-oriented and efficient. Furthermore, the low proportion of critically ill and injured patients already leads to a reduction in attractiveness for emergency physicians and may introduce the threat of quality issues due to insufficient routine experience and lack of training.

Temporal averaging for analysis of four-dimensional whole-heart computed tomography perfusion of the myocardium: proof-of-concept study.

To assess the feasibility of four-dimensional (4D) whole-heart computed tomography perfusion (CTP) of the myocardium and the added value of temporal averaging of consecutive 3D datasets from different heartbeats for analysis. We included 30 patients with suspected or known coronary artery disease (CAD) who underwent 320-row coronary CT angiography (CTA) and myocardial CTP. Out of these, 15 patients underwent magnetic resonance myocardial perfusion imaging (MR MPI). All CTP examinations were initiated after 3 min of intravenous infusion of adenosine (140 µg/kg/min) and were performed dynamically covering the entire heart every heart beat over a period of 20 ± 3 heart beats. Temporal averaging for dynamic CTP visualisation was analysed for the combination of two, three, four, six, and eight consecutive 3D datasets. Input time attenuation curves (TAC) were delivered from measurement points in the centre of the left ventricle. In all 30 patients, myocardial 4D CTP was feasible and temporal averaging was successfully implemented for all planned combinations of 3D datasets. Temporal averaging of three consecutive 3D datasets showed best performance in the analysis of all CTP image quality parameters: noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), subjective image quality, and diagnostic accuracy with an improvement of SNR and CNR by a factor of 2.2 ± 1.3 and 1.3 ± 0.9. With increasing level of temporal averaging, the input TACs became smoother, but also shorter. Out of the 11 perfusion defects detected with MR MPI, 9 defects were also visible on the 4D CTP images. Whole-heart CTP of the myocardium is feasible and temporal averaging of dynamic datasets improves quantitative image quality parameters and visualization of perfusion defects while further studies are needed to assess its added value for quantification of perfusion parameters.

[Teleradiological report turnaround times: An internal efficiency and quality control analysis]. / Teleradiologische Prozess- und Untersuchungszeiten: Eine institutsinterne Effizienz- und Qualitätsanalyse.

AIMS: The teleradiological examinations performed at the Charité were analyzed for the purpose of internal quality and efficiency control. Data included the type and number of examinations performed, the time of day and week the examination was performed and the differences in teleradiologist report turnaround times. MATERIAL AND METHODS: A retrospective analysis of the radiology information system (RIS) database of all teleradiological computed tomography examinations performed at the Charité from 2011 through 2013 was carried out. The search retrieved 10,200 teleradiological examinations which were included in the analysis. The records were analyzed for the time of the day and week the examination was performed, the interval between examination and time of reporting, the type of teleradiological examination and the campus in which they were performed. RESULTS: The number of teleradiological examinations performed increased continuously during the observation period. Computed tomography of the head was the most frequently performed type of examination with 86%. Taking all forms of examination into consideration it took an average of 34 min until a report was written. Over the 3-year observation period the times remained virtually unaltered. CONCLUSION: During the 3-year observation period nearly constant report times could be observed in spite of the increased numbers of examinations. This indicates an efficiency enhancement and rational integration of teleradiology into the radiological workflow.

Patient satisfaction with coronary CT angiography, myocardial CT perfusion, myocardial perfusion MRI, SPECT myocardial perfusion imaging and conventional coronary angiography.

OBJECTIVES: To evaluate patient acceptance of noninvasive imaging tests for detection of coronary artery disease (CAD), including single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI), stress perfusion magnetic resonance imaging (MRI), coronary CT angiography (CTA) in combination with CT myocardial stress perfusion (CTP), and conventional coronary angiography (CCA). METHODS: Intraindividual comparison of perception of 48 patients from the CORE320 multicentre multinational study who underwent rest and stress SPECT-MPI with a technetium-based tracer, combined CTA and CTP (both with contrast agent, CTP with adenosine), MRI, and CCA. The analysis was performed by using a validated questionnaire. RESULTS: Patients had significantly more concern prior to CCA than before CTA/CTP (p < 0.001). CTA/CTP was also rated as more comfortable than SPECT-MPI (p = 0.001). Overall satisfaction with CT was superior to that of MRI (p = 0.007). More patients preferred CT (46%; p < 0.001) as a future diagnostic test. Regarding combined CTA/CTP, CTP was characterised by higher pain levels and an increased frequency of angina pectoris during the examination (p < 0.001). Subgroup analysis showed a higher degree of pain during SPECT-MPI with adenosine stress compared to physical exercise (p = 0.016). CONCLUSIONS: All noninvasive cardiac imaging tests are well accepted by patients, with CT being the preferred examination. KEY POINTS: • A variety of cardiac imaging tests is available without known patient preference • CTA/CTP shows a lower degree of concern than conventional coronary angiography • CTA/CTP shows higher overall satisfaction compared to stress perfusion magnetic resonance imaging • CTA/CTP is rated as more comfortable than SPECT-MPI • CTA/CTP is the preferred cardiac imaging test.

Effect of butylscopolamine on image quality in MRI of the prostate.

AIM: To evaluate the impact of butylscopolamine on the quality of magnetic resonance imaging (MRI) images of the prostate. MATERIAL AND METHODS: Eighty-two MRI examinations of the prostate were retrospectively analysed. MRI was performed with a combined endorectal/body phased-array coil including proton density-weighted (PD) sequence, T1-weighted turbo spin-echo (TSE)-sequence, and T2-weighted TSE-sequences. Forty milligrams of butylscopolamine was administered intramuscularly in 31 patients (im-group) and intravenously in 30 patients (iv-group). Twenty-one patients did not receive premedication with butylscopolamine (ø-group). Overall image quality, delineation of the bowel wall, and visualization of the prostate, neurovascular bundle, and pelvic lymph nodes were evaluated qualitatively using a five-point scale (from 1=excellent to 5=non-diagnostic/structure not discernible). Motion artefacts within the endorectal coil were quantified by baseline adjusted signal intensities inside the endorectal coil area. RESULTS: Delineation of the bowel wall using the PD-sequence was significantly improved after both intramuscular and intravenous butylscopolamine administration (ø-group: 3.6+/-0.7; im-group: 2.9+/-0.7; iv-group: 2.9+/-0.7; p=0.001). However, there were no significant differences in motion artefacts measured within the endorectal coil (ø-group: 1.18+/-0.14; im-group: 1.15+/-0.11; iv-group: 1.12+/-0.06; p=0.39). There were also no significant differences in qualitative assessment of visualization of the prostate, neurovascular bundle, pelvic lymph nodes, and of overall image quality between the study groups. CONCLUSION: : In conclusion, butylscopolamine had only a small effect on image quality and is not mandatory for MRI of the prostate.

Improvement of skills and knowledge by a hands-on cardiac CT course: before and after evaluation with a validated questionnaire and self-assessment.

PURPOSE: Cardiac computed tomography (CT) is becoming increasingly important in noninvasive imaging. To meet this demand, there are a growing number of short training courses for cardiac CT. Whether such courses improve the knowledge and skills of participants is not known. MATERIALS AND METHODS: The concept of a two-day cardiac CT course consisting of introductory lectures, live patient examinations, and hands-on exercises for interpreting cardiac CT scans on workstations was analyzed using participant evaluations (scales from 1=excellent to 6=very poor). Participants rated their increase in knowledge and completed a validated questionnaire with 20 questions. RESULTS: A total of 102 participants attended the courses. There were significant differences in the number of correctly answered test questions between cardiac CT experts and participants at the beginning of the course (91.5+/-6.3 % vs. 62.4+/-16.1% p<0.001). The number of questions answered correctly by the participants increased significantly after completion of the course (mean increase of 4 correctly answered questions, 81.8+/-11.4%. vs. 62.4+/-16.1% p<0.001). This objective increase in knowledge was in good agreement with participant self-assessments (76.4+/-12.6% vs. 81.8+/-11.4%). The quality of the course received good to very good scores, ranging from 1.8+/-0.7 for speed of presentation to 1.4+/-0.5 for lecturer competence. The score for overall course quality was 1.4+/-0.6. CONCLUSION: A relatively short cardiac CT course can significantly improve the quantifiable knowledge of participants. The overall quality of the course was rated as very good.

High-resolution T2-weighted abdominal magnetic resonance imaging using respiratory triggering: impact of butylscopolamine on image quality.

BACKGROUND: Respiratory triggering allows the acquisition of high-resolution magnetic resonance (MR) images of the upper abdomen. However, the depiction of organs close to the gastrointestinal tract can be considerably impaired by ghosting artifacts and blurring caused by bowel peristalsis. PURPOSE: To evaluate the effect of gastrointestinal motion suppression by intramuscular butylscopolamine administration on the image quality of a respiratory-triggered T2-weighted turbo spin-echo (T2w TSE) sequence of the upper abdomen. MATERIAL AND METHODS: Images of 46 patients were retrospectively analyzed. Twenty-four patients had received intramuscular injection of 40 mg butylscopolamine immediately before MR imaging. Fourteen of the 24 patients in the butylscopolamine group underwent repeat imaging after a mean of 29 min. Quantitative analysis of the ghosting artifacts was done by measuring signal intensities in regions of interest placed in air anterior to the patient. In addition, image quality was assessed qualitatively by two radiologists by consensus. RESULTS: Spasmolytic medication with butylscopolamine reduced ghosting artifacts and significantly improved image quality of the respiratory-triggered T2w TSE sequence. The most pronounced effect of butylscopolamine administration on image quality was found for the pancreas and the left hepatic lobe. The rate of examinations with excellent or good depiction of the pancreas and the left hepatic lobe in the group without premedication and in the butylscopolamine group was 55% vs. 96% (pancreatic head), 35% vs. 88% (pancreatic body), 43% vs. 96% (pancreatic tail), and 45% vs. 83% (left hepatic lobe), respectively. Regarding the duration of the effect of intramuscular butylscopolamine, repeat imaging after a mean of 29 min did not result in a significant deterioration of image quality. CONCLUSION: Intramuscular butylscopolamine administration significantly improves image quality of respiratory-triggered T2-weighted abdominal MR imaging by persistent reduction of peristaltic artifacts. MR imaging of the liver and pancreas in particular benefits from the suppression of gastrointestinal peristalsis by butylscopolamine.

Influence of substrate binding on the mechanical stability of mouse dihydrofolate reductase.

We investigated the effect of substrate binding on the mechanical stability of mouse dihydrofolate reductase using single-molecule force spectroscopy by atomic force microscopy. We find that under mechanical forces dihydrofolate reductase unfolds via a metastable intermediate with lifetimes on the millisecond timescale. Based on the measured length increase of approximately 22 nm we suggest a structure for this intermediate with intact substrate binding sites. In the presence of the substrate analog methotrexate and the cofactor NADPH lifetimes of this intermediate are increased by up to a factor of two. Comparing mechanical and thermodynamic stabilization effects of substrate binding suggests mechanical stability is dominated by local interactions within the protein structure. These experiments demonstrate that protein mechanics can be used to probe the substrate binding status of an enzyme.

Unfolding forces of titin and fibronectin domains directly measured by AFM.

AFM-based Single Molecule Force Spectroscopy provides a new tool for probing the mechanical properties of single molecules. In this chapter we show that the unfolding forces of single protein domains can be directly measured. Unfolding forces give new insight into protein stability that cannot be deduced from thermodynamic measurements. A comparison between the unfolding forces measured in Ig domains of the muscle protein titin and those measured in fibronectin Type III domains reveals an extraordinarily high stability of titin domains.

Myosin-V stepping kinetics: a molecular model for processivity.

Myosin-V is a molecular motor that moves processively along its actin track. We have used a feedback-enhanced optical trap to examine the stepping kinetics of this movement. By analyzing the distribution of time periods separating discrete approximately 36-nm mechanical steps, we characterize the number and duration of rate-limiting biochemical transitions preceding each such step. These data show that myosin-V is a tightly coupled motor whose cycle time is limited by ADP release. On the basis of these results, we propose a model for myosin-V processivity.

Mechanical stability of single DNA molecules.

Using a modified atomic force microscope (AFM), individual double-stranded (ds) DNA molecules attached to an AFM tip and a gold surface were overstretched, and the mechanical stability of the DNA double helix was investigated. In lambda-phage DNA the previously reported B-S transition at 65 piconewtons (pN) is followed by a second conformational transition, during which the DNA double helix melts into two single strands. Unlike the B-S transition, the melting transition exhibits a pronounced force-loading-rate dependence and a marked hysteresis, characteristic of a nonequilibrium conformational transition. The kinetics of force-induced melting of the double helix, its reannealing kinetics, as well as the influence of ionic strength, temperature, and DNA sequence on the mechanical stability of the double helix were investigated. As expected, the DNA double helix is considerably destabilized under low salt buffer conditions (

In vitro assays of processive myosin motors.

Myosin V is an actin-based motor thought to be involved in vesicle transport. Since the properties of such a motor may be expected to differ from those of muscle myosin II, we have examined myosin V-driven movement using a combination of gliding filament and optical trap assays to observe single molecules with high resolution. The results clearly demonstrate that brain myosin V is a highly efficient processive motor. In vitro motility assays at low myosin V densities reveal apparent single-molecule supported movement. Processive stepping was also observed in optical trapping assays of myosin V-driven motion. Here the methods that were used to demonstrate the processivity of myosin V are described. These methods include density-dependent assays that eliminate the possibility of aggregation or chance colocalization of multiple motors being responsible for apparent single-molecule motility. Such assays will be useful tools for identifying other processive classes of myosins.

Myosin-V is a processive actin-based motor.

Class-V myosins, one of 15 known classes of actin-based molecular motors, have been implicated in several forms of organelle transport, perhaps working with microtubule-based motors such as kinesin. Such movements may require a motor with mechanochemical properties distinct from those of myosin-II, which operates in large ensembles to drive high-speed motility as in muscle contraction. Based on its function and biochemistry, it has been suggested that myosin-V may be a processive motor like kinesin. Processivity means that the motor undergoes multiple catalytic cycles and coupled mechanical advances for each diffusional encounter with its track. This allows single motors to support movement of an organelle along its track. Here we provide direct evidence that myosin-V is indeed a processive actin-based motor that can move in large steps approximating the 36-nm pseudo-repeat of the actin filament.

Sequence-dependent mechanics of single DNA molecules.

Atomic force microscope-based single-molecule force spectroscopy was employed to measure sequence-dependent mechanical properties of DNA by stretching individual DNA double strands attached between a gold surface and an AFM tip. We discovered that in lambda-phage DNA the previously reported B-S transition, where 'S' represents an overstretched conformation, at 65 pN is followed by a nonequilibrium melting transition at 150 pN. During this transition the DNA is split into single strands that fully recombine upon relaxation. The sequence dependence was investigated in comparative studies with poly(dG-dC) and poly(dA-dT) DNA. Both the B-S and the melting transition occur at significantly lower forces in poly(dA-dT) compared to poly(dG-dC). We made use of the melting transition to prepare single poly(dG-dC) and poly(dA-dT) DNA strands that upon relaxation reannealed into hairpins as a result of their self-complementary sequence. The unzipping of these hairpins directly revealed the base pair-unbinding forces for G-C to be 20 +/- 3 pN and for A-T to be 9 +/- 3 pN.

Single-molecule biomechanics with optical methods.

Single-molecule observation and manipulation have come of age. With the advent of optical tweezers and other methods for probing and imaging single molecules, investigators have circumvented the model-dependent extrapolation from ensemble assays that has been the hallmark of classical biochemistry and biophysics. In recent years, there have been important advances in the understanding of how motor proteins work. The range of these technologies has also started to expand into areas such as DNA transcription and protein folding. Here, recent experiments with rotary motors, linear motors, RNA polymerase, and titin are described.

How strong is a covalent bond?

The rupture force of single covalent bonds under an external load was measured with an atomic force microscope (AFM). Single polysaccharide molecules were covalently anchored between a surface and an AFM tip and then stretched until they became detached. By using different surface chemistries for the attachment, it was found that the silicon-carbon bond ruptured at 2.0 +/- 0.3 nanonewtons, whereas the sulfur-gold anchor ruptured at 1.4 +/- 0.3 nanonewtons at force-loading rates of 10 nanonewtons per second. Bond rupture probability calculations that were based on density functional theory corroborate the measured values.