Self-management for patients on ventricular assist device support: a national, multicentre study: protocol for a 3-phase study

INTRODUCTION

Self-management (SM) may facilitate patient participation and involvement to become active and knowledgeable partners in the care of complex chronic conditions such as ventricular assist device (VAD) therapy. The 'SM model for patients on VAD support' will serve to distinguish between SM components, and will guide the development, implementation and evaluation of an evidence-based curriculum.

METHODS AND ANALYSIS

This is a 3-phase, multicentre study. In phase 1, a prevalence study will be performed. Phase 2 aims to develop an evidence-based, interprofessional curriculum for SM support for VAD patients. In phase 3, a non-blinded block-randomised controlled trial (RCT), allocation ratio 1:1, intervention group superiority, with an unblinded multifacetted intervention with assessments before (T1) and after (T2) the intervention, and two follow-up assessments at three (T3), and 12 (T4) months after VAD implantation, will be performed. The curriculum guides the intervention in the RCT. Patient recruitment will consider centre-related volume: power analyses require 384 patients for phase 1, and 142 patients for phase 3.

ETHICS AND DISSEMINATION

Ethical considerations will be continuously taken into account and approved by the institutional review boards. Central ethical review board approval has been obtained by the Albert-Ludwigs University Freiburg. This study will be performed in concordance with the Declaration of Helsinki and the European data protection law. Publications will exclusively report aggregated data and will be distributed in the scientific community, and patient support groups. Report languages will be German and English.

TRIAL REGISTRATION NUMBERS

NCT04234230 and NCT04526964; Pre-results.

Self-management with the therapeutic regimen in patients with ventricular assist device (VAD) support - a scoping review

BACKGROUND

Ventricular assist device (VAD) implantation has become an established treatment strategy for the increasing number of patients with advanced heart failure. Adequate patient self-management becomes essential to prevent adverse events, which could diminish expected outcomes and survival for patients on VAD support.

OBJECTIVES

The aim of this study was to provide an overview of the current state of evidence concerning self-management in VAD patients through a systematized search and mapping of the literature.

METHODS

Following the scoping review process, a comprehensive literature search (PubMed, PsychInfo), tabular synthesis of included articles, and data analysis of synthesized findings were performed.

RESULTS

Overall, twenty articles were included. Results describe the complexity of regular self-management tasks and give direction for specific self-management training.

CONCLUSIONS

This article represents the first comprehensive overview of available evidence suggesting the need for development and implementation of evidence-based, patient self-management curricula with therapeutic regimen for VAD patients.

[Communication with children: practical hints and tools for the anesthesiology routine]

BACKGROUND

Pediatric patients represent a special challenge both for the management of anesthesia and for communication, especially the anxious and screaming child. Children have specific features of fears, cognition, comprehension and skills depending on the stage of development. In addition, behavior and anxiety are strongly shaped by the parents who have to be incorporated.

AIM

This article presents the special features of children as well as practical strategies and aids for dealing with children in a perioperative setting.

MATERIAL AND METHODS

In children suggestibility and susceptibility to placebo and nocebo effects are increased. This makes them more sensitive to negative factors but can also be utilized for positive, constructive effects. Possibilities are presented which make use of the special characteristics of children. A number of examples from daily clinical routine are given.

RESULTS

A child's imagination, creativity and capability for dissociation in particular allow an effective application of indirect suggestion, metaphors, stories, changes in focus of attention, retreat to an inner or imagined safe place, reframing of disturbing noises and events, pacing and leading in small steps and an activation of inner resources. A hand puppet, a pet toy, a little magic trick, introducing a magic friend, acupoint for palpitations with self-affirmation, stick figure drawings, ceiling pictures or holding hands can be quite helpful. All medical devices and interventions can be explained in a way that children can understand and in positive statements without lying or neglecting the need for information.

CONCLUSION

Meeting at eye level, talking to the child instead of just about it, a language appropriate for children but not childish, comprehensible information and explanations, return of control and care more than pure technical distance, all play an important role. A serious look into such communication strategies can help the anesthetist to overcome uncertainties that a child can easily sense.

Anesthesiologic regimen and intraoperative delirium in deep brain stimulation surgery for Parkinson's disease

BACKGROUND

In many centers the standard anesthesiological care for deep brain stimulation (DBS) surgery in Parkinson's disease patients is an asleep-awake-asleep procedure. However, sedative drugs and anesthetics can compromise ventilation and hemodynamic stability during the operation and some patients develop a delirious mental state after the initial asleep phase. Further, these drugs interfere with the patient's alertness and cooperativeness, the quality of microelectrode recordings, and the recognition of undesired stimulation effects. In this study, we correlated the incidence of intraoperative delirium with the amount of anesthetics used intraoperatively.

METHODS

The anesthesiologic approach is based on continuous presence and care, avoidance of negative suggestions, use of positive suggestions, and utilization of the patient's own resources. Clinical data from the operations were analyzed retrospectively, the occurrence of intraoperative delirium was extracted from patients' charts. The last 16 patients undergoing the standard conscious sedation procedure (group I) were compared to the first 22 (group II) psychologically-guided patients.

RESULTS

The median amount of propofol decreased from 146 mg (group I) to 0mg (group II), remifentanyl from 0.70 mg to 0.00 mg, respectively (P<0.001 for propofol and remifentanyl). Using the new procedure, 12 of 22 patients (55%) in group II required no anesthetics. Intraoperative delirium was significantly less frequent in group II (P=0.03).

CONCLUSIONS

The occurrence of intraoperative delirium correlates with the amount of intraoperative sedative and anesthetic drugs. Sedation and powerful analgesia are not prerequisites for patients' comfort during awake-DBS-surgery.

[Optimization of blood gas analysis in intensive care units : Reduction of preanalytical errors and improvement of workflow]

BACKGROUND

Point of care testing with blood gas analysis (BGA) is an important factor for intensive care medicine. Continuous efforts to optimize workflow, improve safety for the staff and avoid preanalytical mistakes are important and should reflect quality management standards.

AIM

In a prospective observational study it was investigated whether the implementation of a new system for BGA using labeled syringes and automated processing of the specimens leads to improvements compared to the previously used procedure.

MATERIAL AND METHODS

In a 4-week test period the time until receiving the final results of the BGA with the standard method used in the clinical routine (control group) was compared to the results in a second 4-week test period using the new labeled syringes and automated processing of the specimens (intervention group). In addition, preanalytical mistakes with both systems were checked during routine daily use. Finally, it was investigated whether a delay of 10 min between taking and analyzing the blood samples alters the results of the BGA.

RESULTS

Preanalytical errors were frequently observed in the control group where non-deaerated samples were recorded in 87.3 % but in the intervention group almost all samples (98.9 %) were correctly deaerated. Insufficient homogenization due to omission of manual pivoting was seen in 83.2 % in the control group and in 89.9 % in the intervention group; however, in the intervention group the samples were homogenized automatically during the further analytical process. Although a survey among the staff revealed a high acceptance of the new system and a subjective improvement of workflow, a measurable gain in time after conversion to the new procedure could not be seen. The mean time needed for a complete analysis process until receiving the final results was 244 s in the intervention group and 201 s in the control group. A 10-min delay between taking and analyzing the blood samples led to a significant and clinically relevant elevation of the values for partial pressure of oxygen (pO2) in both groups compared to the results when analyzing the samples immediately (118.4 vs. 148.6 mmHg in the control group and 115.3 vs. 123.7 mmHg in the intervention group). When using standard syringes the partial pressure of carbon dioxide (pCO2) was significantly lower (40.5 vs. 38.3 mmHg) whereas no alterations were seen when using the labeled syringes.

CONCLUSION

The implementation of a new BGA system with labeled syringes and automated processing of the specimens was possible without any difficulties under daily clinical routine conditions in this 10-bed intensive care unit (ICU). A gain of time could not be measured but a reduction in preanalytical errors using the labeled syringes with automated processing was found. Delayed analysis of blood samples can lead to significant changes in pO2 and pCO2 depending on the type of syringe used.

[Placement of a central venous catheter in cases of persistent left superior vena cava]

This article presents a case report on the placement of a central venous catheter (CVC) in a patient with an unknown persistent left superior vena cava (PLSVC). Normally, PLSVCs remain asymptomatic but can be associated with disastrous consequences for the patient during placement of a CVC particularly due to vascular perforation and pulmonary injury. A PLSCV is particularly common in association with congenital heart defects; however, otherwise healthy patients can also be affected. As the presence of a PLSCV is normally unknown special attention must be paid in every patient during placement of a CVC.

[Anesthesiological aspects of deep brain stimulation : special features of implementation and dealing with brain pacemaker carriers]

Deep brain stimulation (DBS) provides a very effective treatment for a number of neurological diseases including Parkinson's disease, movement disorders and epilepsy. In DBS microelectrodes are positioned in defined cerebral target areas and connected to a pacemaker. It is most often performed as an awake craniotomy with intraoperative testing. Various anesthesiological regimes are used to protect the patient from surgical stress on the one hand and to achieve ideal test conditions on the other. They include local anesthesia or scalp blocks, intermittent general anesthesia or analgosedation with or without airway protection; however, anesthetic agents interfere with hemodynamic stability and ventilation, with vigilance and cooperation and in addition with the symptoms and microelectrode recording. Guidance and communication have a pivotal impact on patient needs for pharmacological interventions. With increasing numbers of DBS procedures, anesthesiologists are more often faced with patients carrying brain pacemakers. For anesthesia the characteristics of the disease as well as the respective long-term medication have to be considered. In addition, the rules for handling patients with pacemakers need to be followed to avoid both dysfunction of the generator and tissue damage due to overheating of the electrodes.

[Secondary sclerosing cholangitis after multiple trauma and long-term intensive care treatment: case report of a characteristic course]

This article reports on a patient who needed intensive care treatment because of multiple trauma. The patient had no preexisting liver disease but developed secondary sclerosing cholangitis and finally died. The etiology, diagnosis and therapeutic options of this clinical picture are discussed and a review of the literature is presented.

[Sports and activities after achilles tendon injury of the recreational athlete]

BACKGROUND

There is abundant literature on the treatment of Achilles tendon rupture; however data on sports and recreational activities after this injury is scarce.

PATIENTS AND METHODS

71 patients were assessed in a prospective cross-sectional study after an average of 3 years after Achilles tendon rupture. 44 patients were treated non-operatively, using a functional algorithm, and 23 patients were treated operatively. Outcome parameters were the AOFAS-Score and the SF-36 Score. The strength of plantar-flexion was measured using the Isomed 2000 system, the structural integrity of the tendon was assessed sonografically.

RESULTS

Patients treated operatively had a higher complication rate than patients treated non-operatively (p = 0.05). Re-rupture rate was identically in both groups. No difference was noted between the two groups for the AOFAS score (92 vs. 90). Moreover the SF-36 score did not show any significant difference between the groups. However, if compared to the age-adjusted normative population significant lower scores were achieved. A significant reduction in practicing sports was detected, as well as a reduction of plantar flexion of the affected foot (p = 0.04).

CONCLUSION

Except for complication rate no significant difference could be detected between the groups. Thus operative treatment in the recreational athlete should only be considered, if no adaptation of the ends of the tendon is diagnosed during the initial or repeated ultrasound. Regardless of the therapeutic intervention chosen an Achilles tendon rupture leads to marked changes in sports- and recreational activities.

A rare case of primary rectal rhabdomyosarcoma in an adult

We report an extremely rare case (1:200 000) of primary rectal rhabdomyosarcoma (RMS) in an adult. In the literature, this case report is the first one dealing with an adult patient. The diagnosis was assessed by computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), endoscopy and histological examination. Neoadjuvant systemic chemotherapy with adriamycin and isofosfamide followed by anterior rectum resection was performed. This article should implicate RMS as a rare differential diagnosis of atypical rectal tumours in adults.

Clinical aspects and strategy for biomaterial engineering of an auricle based on three-dimensional stereolithography

At the present time, the partial and/or complete reconstruction of an auricle from autologous rib cartilage is one of most widely published techniques. In the field of tissue engineering, different techniques have been described to generate cartilage tissue using isolated chondrocytes. The basis of these tissue-engineering techniques is bioresorbable or non-bioresorbable biomaterials, which serve as a three-dimensional cell carrier. Tissue engineering of an auricle requires preformed bioresorbable biomaterials designed to fit the form of a patient's auricular defect. Three-dimensional imaging acquired from computed tomography scans or laser surface scanning has become an important tool in modern medicine. This study represents the preoperative procedures for the reconstruction of an auricle through tissue engineering in accordance with the clinical aspects. Hyaff 11, a hyaluronic acid derivative, was used as a three-dimensional cell carrier for isolated human nasoseptal chondrocytes. The chondrocytes were amplified in a conventional monolayer culture before the cells were seeded on a hyaluronic non-woven mesh and cultured in vitro for 4 weeks. The chondrogenic potential of human nasal chondrocytes in Hyaff 11 was investigated by confocal laser scanning microscopy, histology (toluidine blue) and immunohistochemistry (collagen type II). Computer-aided design (CAD) and manufacture of an auricle model with stereolithographical methods were used for the prefabrication of a bioresorbable three-dimensional cell carrier designed in the form of a patient's auricular defect. The cell carrier used was Hyaff 11, a fully benzyl-esterified hyaluronic acid derivative. Confocal laser scanning microscopy has shown good cell attachment, a homogenous distribution of amplified chondrocytes and a viability of more than 90%. After 4 weeks in vitro culture the human nasoseptal chondrocytes synthesized new cartilage with the expression of cartilage-specific collagen type II. In order to shape a patient's designed scaffold the auricle model was fitted exactly and symetrically to the contralateral side. Subsequently, the mirror image patient-specific model was used to prepare an identical scaffold model made of a fully benzyl-esterified hyaluronic acid derivative. The bioresorbable scaffold that was produced gave a satisfactory representation of auricle structure. Bioresorbable preformed biomaterials in the form of a patient's auricle defect represent an important prerequisite for the tissue engineering of autologous auricle grafts. Hyaff 11 seems to be a promising material for tissue engineering of cartilage transplants, and the application of this approach will improve conventional reconstructive surgery in the future.

[MRI of intraosseous fistulous systems and sequesters in chronic osteomyelitis with standard spin echo sequences, highly selective chemical-shift imaging, diffusion weighted imaging, and magnetization-transfer]

PURPOSE

To study and test the impact of modern MRI techniques in diagnostic imaging in the evaluation of intra-osseous fistulous systems and sequesters.

MATERIALS AND METHODS

In a prospective study, nine patients with chronic osteomyelitis of the legs were examined by MRI. Patients with clinical signs of osteomyelitis requiring surgery were included in the study. T1-weighted spin echo (SE) sequences, proton density (PD) and T2-weighted fast spin echo (FSE) sequences, water- and fat-selective FSE sequences, and diffusion weighted (DW) PSIF sequences were used preoperatively. Furthermore, magnetizing transfer (MT) with gradient echo (GRE) sequences was evaluated.

RESULTS

Water selective sequences revealed the highest sensitivity for the detection of fistulas (100%), providing the best delineation of the extent of the entire fistulous systems. Fat-selective sequences (sensitivity 55.6%) and T1-weighted sequences (sensitivity 77.8%) displayed fistulas as hypointense bands, which, however, cannot be well differentiated from cortical bone in the transcortical areas. PD and T2-weighted images were found to have a poor sensitivity (55.6% and 66.7%) for fistulas in any location. The sensitivity of water-selective sequences to demonstrate intraosseous sequesters was 100%. The sensitivity was low for the other sequences. In 4 of 5 patients with surgically proven infection, DW and MT revealed an abnormal spatial distribution, with high diffusion in the central parts of the fistulas and high MT effect peripherally surrounding a weak MT effect centrally.

CONCLUSION

Water-selective sequences are superior when demonstrating fistulous systems and intraosseous sequesters. The combined use of MT and DW sequences seems to allow a differentiation between solid granulation tissue and liquid pus.

[Use of VR (virtual reality) software for preoperative implantation fitting with an implantable hearing aid as an example]

PURPOSE

To prove the feasibility of a preoperative fitting test for an implantable hearing aid using a VR environment.

METHODS

A high-resolution spiral CT was performed after mastoidectomy in 10 temporal bone specimens. The bony structures were segmented and merged with the Computer-Aided Design (CAD) data of the hearing aid in a VR environment. For each specimen a three-dimensional fitting test was carried out by three examiners determining the implantability of the hearing aid. The implantation simulation was compared with the real implantation procedure performed by an experienced ENT surgeon.

RESULTS

The used VR system enabled real-time 3D-visualisation and manipulation of CT- and CAD-data. All objects could be independently moved in all three dimensions. The VR fitting test corresponded closely with the real implantation. The implantability of the hearing aid was properly predicted by all three examiners.

CONCLUSION

Merging CT and CAD data in a virtual reality environment bears high potential for the pre-surgical determination of the fit and mountability of medical implants in complex anatomical regions.

Identification of gcpE as a novel gene of the 2-C-methyl-D-erythritol 4-phosphate pathway for isoprenoid biosynthesis in Escherichia coli

The 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway for isoprenoid biosynthesis is essential in most eubacteria and plants and has remarkable biotechnological interest. However, only the first steps of this pathway have been determined. Using bioinformatic and genetic approaches, we have identified gcpE as a novel gene of the MEP pathway. The distribution of this gene in bacteria and plants strictly parallels that of the gene encoding 1-deoxy-D-xylulose 5-phosphate reductoisomerase, which catalyses the first committed step of the MEP pathway. Our data demonstrate that the gcpE gene is essential for the MEP pathway in Escherichia coli and indicate that this gene is required for the trunk line of the isoprenoid biosynthetic route.

Synergistic effect between iron and gadolinium in MRI

Different combinations of iron glycerophosphate (Fe) and gadolinium-diethylene triamine pentaacetic acid (DTPA) (Gd) were imaged with a three-dimensional (3D) gradient-recalled echo (GRE), a 2D GRE, and a HASTE sequence on a 1.5-T MR scanner. A combination of Fe and Gd results in a synergistic effect, which improves the signal gain for selective 3D imaging of the colon and simultaneously decreases the endoluminal signal on the HASTE and 2D GRE images for better visualization of water and Gd-enhanced structures in the gut wall.

Human SPRY2 inhibits FGF2 signalling by a secreted factor

Growth factor signalling pathways and their inhibitors coordinate the formation of three-dimensional patterns of vertebrates and invertebrates. Temporal and spatial restriction of the response to a few well-defined cells is crucial and needs the integration of positive and negative signals. Recently, Spry has been identified as an inhibitor of fibroblast growth factor (FGF) signalling during Drosophila trachea development. Spry has been described as an intracellular protein that can exert its function in a cell autonomous or a paracrine manner. Here we describe the role of SPRY2, a human homologue of Spry, in human FGF2 signalling. We show that in primary human dermal endothelial cells (MVEC) SPRY2 mRNA is transiently upregulated in response to FGF2. Overexpression of SPRY2 in A375 cells leads to the secretion of a soluble factor that inhibits FGF2- but not VEGF-stimulated proliferation of MVEC. Direct administration of recombinant SPRY2 protein has no effect on MVEC proliferation. However, SPRY2 protein binds the intracellular adaptor protein GRB2, indicating an intracellular localization. A SPRY2/GFP fusion protein remains in the cell, further supporting the intracellular localization of SPRY2. So the intracellular protein SPRY2 is involved in the non-cell autonomous inhibitory effect indirectly, via regulating the secretion of an inhibitor of FGF2 signalling in vertebrates, the evidence of which is presented here for the first time.

Effective contrast use in CT angiography and dual-phase hepatic CT performed with a subsecond scanner

OBJECTIVE

To deduce an optimal injection protocol for CT angiography and fast dual-phase hepatic CT.

METHODS

Fifty-two patients underwent fast dual-phase hepatic CT using one of three different injection protocols: A (0.9 g/sec iodine injection rate, 36 g dose); B (1.35 g/sec, 30 g); C (1.6 g/sec, 40 g). Aortic attenuation time curves as well as aorta-to-liver contrast and hepatic enhancement time curves obtained by region of interest measurements along the helical axis were analyzed.

RESULTS

Protocol C revealed a significantly higher peak in aortic attenuation and hepatic enhancement than the other protocols. Approximately 50 seconds after the bolus injection, hepatic enhancement declined to a plateau similar to that seen with the other protocols. In terms of the areas under the curves of the aorta-to-liver contrast and hepatic enhancement dynamics, protocol C was significantly superior to the other protocols.

CONCLUSIONS

A high iodine injection rate realized by a high iodine concentration in conjunction with fast dual-phase scanning (total scan time < 50 seconds) promises to enhance CT angiography and contrast of liver lesions.

[Evaluation of right heart load with spiral CT in patients with acute lung embolism]

PURPOSE

Purpose of this study was to evaluate whether spiral-CT allows judgment of right ventricular failure in patients with acute pulmonary embolism.

MATERIALS AND METHODS

61 patients underwent spiral-CT due to suspicion of acute pulmonary embolism. Patients with pulmonary embolism were divided into subpopulations according to the severity of pulmonary embolism in the CT scan. Cardiac measurements were performed on axial spiral-CT images and compared to those of patients without suspicion of pulmonary embolism or cardiac diseases.

RESULTS

In 30 patients spiral-CT revealed acute pulmonary embolism. Significant differences in cardiac measurements in patients with severe and less severe pulmonary embolism were found on comparing the following dimensions: left ventricular width (p = 0.0003), left (p = 0.008) and right (p = 0.009) ventricular cross-sectional area, proportion of right to left ventricular width (p = 0.0003) and proportion of right to left ventricular cross-sectional area (p = 0.0001). The proportion of the cross-sectional areas (r = 0.65) and the proportion of the width (r = 0.60) of both ventricles correlated well with the severity of central pulmonary embolism.

CONCLUSION

Besides reliable assessment of pulmonary embolism spiral-CT allows the evaluation of cardiac dimensions for judgment of right ventricular failure.

Influence of helical CT parameters on spatial resolution in CT angiography performed with a subsecond scanner

RATIONALE AND OBJECTIVES

In helical CT, the beam collimation, table feed (TF) per tube rotation, voltage, current, reconstruction increment, kernel, linear interpolation algorithm (LIA), and contrast are variable parameters. The purpose of this study was to determine which of these parameters are most important to minimize partial volume effects for improving spatial resolution in CT angiography.

METHODS

Phantom vessel stenoses of different lengths (2, 8 mm) and diameters (0.5, 1, 2, 3, 4 mm) were scanned with helical CT using a constant tube rotation time of 0.75 sec and 42 selected combinations of the above-mentioned parameters. Orthogonal targeted maximum intensity projections of the stenoses were ordered according to the increase in blurring and noise in a consensus reading by two radiologists blinded to the parameters used.

RESULTS

Three millimeters of collimation and TF in conjunction with a 180 degrees LIA and > 250 Hounsfield unit contrast density was considered the optimal parameter combination and enabled a continuous visualization of the stenoses down to 0.5 mm in diameter. A collimation of 1 or 2 mm and 5 mm was considered inferior to a collimation of 3 mm because of, respectively, noise and blurring. With 3 mm collimation, significant blurring occurred when a pitch larger than 1.5 was used. A 3 mm collimation with a pitch of 2 (6 mm TF) was found to be superior to a collimation of 5 mm in conjunction with a pitch of 1 (5 mm TF). With 5 mm collimation, the short stenoses could be visualized only when using a 180 degrees LIA and a TF per tube rotation smaller than 7 mm. Eight and 10 mm collimations failed to depict the short stenoses.

CONCLUSIONS

Collimation had the most influence on image quality in CT angiography, followed by LIA, pitch, and contrast density. Decreasing the reconstruction increment to less than one third of the TF or increasing the voltage or current beyond standard values did not improve the delineation of the stenoses. For screening examinations, the authors recommend the use of 3 mm collimation, 180 degrees LIA, and a pitch of 2.

Relations between cardiopulmonary exercise testing and quantitative high-resolution computed tomography associated in patients with alpha-1-antitrypsin deficiency

High-resolution computed tomography (HRCT) can be used to diagnose and quantify emphysema noninvasively, as significant correlations have been found between the histological grade on resected lung specimens and quantified (q) computed tomography (CT). In this study, we performed thin section qHRCT in patients with severe hereditary alpha-1-antitrypsin (AAT) deficiency. AAT deficiency is the most common genetic cause of emphysema in adults, and exercise intolerance is the most disabling, distressing consequence of emphysema for the majority of patients. qHRCT was used to quantify precisely the alterations in the lung parenchyma due to pulmonary emphysema. Up until now, the important relationship between the severity of emphysema and the reduced exercise capacity has received little attention. Therefore the purpose of the study was to investigate the relationship between emphysema as displayed by qHRCT and cardiopulmonary exercise testing (CPX) in patients with severe cardiopulmonary impairment. - qHRCT was performed in 21 patients with homozygous AAT deficiency. CT scans were obtained at three spirometrically standardized levels at the carina and (5 cm above and below the carina). The mean lung density at 50% of vital capacity and a quantitative histogram analysis of the frequencies of CT values were determined. All patients underwent symptom-limited CPX to analyse simultaneously cardiovascular and ventilatory systems responses. - In all patients, qualitative CT assessment demonstrated panlobular emphysema with large and extensive areas of uniform low attenuation, characteristically with a lower-lobe distribution. Mean CT density values of the patients (-845 +/- 6.9 (mean +/- SEM)) were significantly correlated with work capacity (r = 0.55, p <0.01), oxygen-pulse (r = 0.54, p <0.01) and functional dead space ventilation (r = -0.54, p <0.01). Moreover, severe emphysema index (CT values below a threshold value of 950 HU) correlated positively with functional dead space ventilation (r = 0.60, p <0.01) and alveolar-arterial oxygen difference (r = 0.70, p <0.001). - These results clearly demonstrate that CPX parameters, indicating a disturbed pulmonary gas exchange and a ventilation-perfusion-mismatch during exercise, are significantly related to the extent of lung emphysema.

[Virtual and three-dimensional bronchoscopy with spiral and electron beam computed tomography]

PURPOSE

To compare spiral computed tomography (CT) and electron-beam CT (EBT) for 3D and virtual CT-bronchoscopy.

MATERIALS AND METHODS

17 patients with various disorders of the tracheobronchial system were examined using fiberoptic bronchoscopy, spiral CT and EBT. 3D images were reconstructed from CT data sets using automated segmentation based on volume-growing methods. Surface-rendered, volume-rendered, and hybrid reconstructions were visualized in real time using a data helmet.

RESULTS

All data sets could be processed to high-quality three-dimensional (3D) and virtual reconstructions. The reduction of motion artifacts due to shorter scan times made EBT data sets better suited for automated segmentation and less susceptible to motion artifacts. 3D and virtual reconstructions did not increase the diagnostic sensitivity of CT compared to axial reconstructions alone.

CONCLUSIONS

Shorter scan times of CT imaging yield higher-quality 3D and virtual reconstructions. Modern reconstruction techniques are valuable visualization tools for select indications and are the prerequisite for future developments in computer-aided medicine.

[Computer-assisted diagnosis based on computer-based image interpretation and 3D-visualization]

PURPOSE

To survey methods for 3D data visualization and image analysis which can be used for computer based diagnostics.

MATERIAL AND METHODS

The methods available are explained in short terms and links to the literature are presented. Methods which allow basic manipulation of 3D data are windowing, rotation and clipping. More complex methods for visualization of 3D data are multiplanar reformation, volume projections (MIP, semi-transparent projections) and surface projections. Methods for image analysis comprise local data transformation (e.g. filtering) and definition and application of complex models (e.g. deformable models).

RESULTS

Volume projections produce an impression of the 3D data set without reducing the data amount. This supports the interpretation of the 3D data set and saves time in comparison to any investigation which requires examination of all slice images. More advanced techniques for visualization, e.g. surface projections and hybrid rendering visualize anatomical information to a very detailed extent, but both techniques require the segmentation of the structures of interest. Image analysis methods can be used to extract these structures (e.g. an organ) from the image data.

DISCUSSION

At the present time volume projections are robust and fast enough to be used routinely. Surface projections can be used to visualize complex and presegmented anatomical features.

Hybrid rendering of the cervico-cranial arteries using spiral computed tomography

PURPOSE

The purpose of this study was to develop a shaded-surface and volume display (hybrid rendering method) of the whole vascular system of the cervico-cranial arteries using spiral computed tomography (SCT).

MATERIALS AND METHODS

We examined 12 patients with anatomic abnormalities and pathological conditions of the arterial vascular system. The cervico-cranial arteries were segmented using an interactive threshold interval density volume-growing method and visualized with a color-coded shaded-surface display (SSD) rendering method. The adjacent bone structures were visualized using a transparent volume rendering method.

RESULTS

In all cases, the entire volume of the vascular system of the cervico-cranial arteries and the anatomic abnormalities and pathological conditions could be visualized.

CONCLUSION

Hybrid rendering of the circulation of the cervico-cranial arteries using image data sets from a subsecond spiral CT scanner is useful for the visualization of anatomical and pathological abnormalities and offer a promising minimally invasive alternative compared with other diagnostic procedures.

[MRI of fingers in systemic scleroderma. Initial results with contrast-enhanced studies using a dedicated MRI system]

PURPOSE

To estimate disease activity in patients with systemic sclerosis using contrast-enhanced MRI of the skin.

MATERIAL AND METHODS

In a pre-study, sequences of a low-field (0.2 T) scanner (Artoscan, Esaote, Genova, Italy) were optimized for detection of intravenous contrast (0.1 mmol/l Gd-DTPA) in six patients with the autoimmune disease systemic scleroderma. Based on the results of the pre-study, 17 patients with scleroderma (7 sclerotic/10 active inflammatory disease) were scanned using gradient-spoiled 3D GRE sequences (FA 90 degrees, TR 100 ms, TE 18 ms), which had been established as most sensitive for intravenous contrast. Contrast enhancement of the skin was determined quantitatively by contrast-to-noise ratios (CNR), comparing post- to pre-contrast and dynamic scans (for 6 min, 1 acquisition/min). Patients in the chronic state with sclerodactylia and active inflammation of the hands were considered separately and compared to a control group (n = 10) matched according to age.

RESULTS

CNR increase after intravenous contrast was significantly higher in patients with active disease (86 +/- 16% increase) than sclerosing disease (29 +/- 3%, p < 0.05) and the control group (4 +/- 2%, p < 0.05). The dynamic examination showed a significantly slower decrease after the peak rise in the first minute in patients with active disease (CNR 15.4 +/- 0.7 to 14.2 +/- 1.4) than in those with chronic disease (14.1 +/- 0.5 to 11.3 +/- 0.9, p < 0.05).

DISCUSSION

Capillary leakage is the most likely explanation for the increased enhancement in patients with active scleroderma. Using sequences optimized for contrast detection, disease activity in the course of scleroderma and response to therapy can be determined by MRI in the future.

Gene structure and 5'-flanking regulatory region of the murine serotonin transporter

By modulating the magnitude and duration of postsynaptic responses, carrier-facilitated serotonin (5-HT) transport into and release from the presynaptic neuron is central to the fine tuning of serotonergic neurotransmission. The 5-HT transporter (5-HTT) is the prime target for widely used antidepressants, psychostimulants, drugs of abuse and neurotoxins. We have isolated the gene encoding the murine 5-HTT and determined the sequence of all exons including adjacent intronic regions and approximately 3.6 kb of the 5'-flanking regulatory region. The murine 5-HTT gene is composed of 14 exons spanning approximately 34 kb. The single gene transcript after splicing is 2744 bp in length and it contains 186 bp of 5' untranslated region (5'-UTR) and 668 bp of 3'-UTR. A TATA-like motif and several potential binding sites for transcription factors including AP1, AP2, AP4, SP1 as well as CRE- and GRE-like motifs are present in the GC-rich 5'-flanking region. The characterization of murine 5-HTT cDNA and genomic organization will facilitate studies of 5-HT uptake function with molecular pharmacologic and transgenic strategies as well as investigations of its role in quantitative traits and psychiatric disorders.

Molecular heterogeneity of neurotransporters: implications for neurodegeneration

Neurotransporters are high-affinity transport proteins located in the plasma membrane of both presynaptic nerve and glial cells that mediate the removal of neurotransmitters from the synaptic cleft or represent intracellular transport systems that concentrate neurotransmitters in synaptic vesicles. They comprise three subgroups, Na+/Cl(-)- or Na+/K(+)-dependent cell surface transporters and H(+)-dependent transporters associated with synaptic vesicles. The new insights into neurotransporter diversity provide the means for novel approaches of studying neurotransmitter uptake processes at the molecular level, such as substrate translocation and antagonist binding as well as regulation of gene expression, of intracellular trafficking, and of posttranslational modification. Moreover, modeling neurotransporter-related disorders and therapeutic strategies in genetically engineered animals are now feasible research strategies. Through an improved understanding of the modulation of neurotransporter function in the brain, it may be possible to identify the molecular factors underlying the etiopathogenesis and pathophysiology of neurodegenerative disorders. Due to their specificity for distinct neuronal systems, neurotransporters and their genes are potential targets for novel therapeutic strategies.

[CT subtraction angiography (CTSA). Results with an automated "elastic" subtraction algorithm]

PURPOSE

To develop and implement a method to obtain digital subtraction (DS) spiral computed tomography angiograms (SCTA) in order to avoid superimposition of bony structures and vascular calcifications on SCTA maximum intensity projections (MIPs) and shaded surface display (SSD).

METHOD

Two SCTA data sets, one before and one during the injection of a contrast agent bolus, were obtained with identical scan parameters. Since ordinary subtraction of the two data sets fails to reliably separate bones and calcifications from the vascular lumen because of motion, a so-called elastic subtraction procedure was designed to correct 3D misregistration between the two data sets. It automatically accommodates for local position changes between baseline and contrast images, including regionally inconsistent non-linear displacements and arbitrary rotations. This method was tested in seven patients and evaluated against ordinary DS in terms of image quality and artifacts.

RESULTS

In all patients "elastic" CTSA proved superior to ordinary DS. It provides automated and reliable separation of vessels from bones and calcifications. This improves the delineation of vessels in the neck and the skull base and of intracranial vessels. DS-SCTA facilitates MIPs and SSD without artifacts introduced by thresholding.

CONCLUSION

Elastic DS-SCTA is a robust method for automated unmasking of vessels from bones and warrants clinical trials and comparison with MR- and conventional angiography.

[Increased liver density in computed tomography as a result of anti-arrhythmia therapy with amiodarone]

PURPOSE

To assess whether the hepatic density on CT scans of patients receiving amiodarone therapy differs significantly from the hepatic density of a control group not receiving the drug.

METHODS

Hepatic density was assessed by CT in 31 patients receiving amiodarone, 7 receiving short-term (12-14 days), 8 receiving mid-term (20-89 days) and 16 receiving long-term therapy (3-26 months), as well as in a control group of 15 patients.

RESULTS

Mean liver density of all patients under amiodarone therapy (77.9 +/- 11.7 HU) was significantly higher (p < 0.005) than in the control group (56.6 +/- 2.8 HU). The smallest increase in density was found in patients with short-term therapy (64.8 +/- 3.4 HU; p < 0.05), the greatest increase in patients with long-term therapy (85.0 +/- 8.9 HU; p < 0.001).

CONCLUSION

In patients receiving amiodarone therapy, a significantly increased hepatic density on CT scans is observed. This finding has to be considered as a differential diagnosis to other hepatopathies with increased density of the liver.

Biosynthesis of isoprenoids (carotenoids, sterols, prenyl side-chains of chlorophylls and plastoquinone) via a novel pyruvate/glyceraldehyde 3-phosphate non-mevalonate pathway in the green alga Scenedesmus obliquus

Isoprenoid biosynthesis was investigated in the green alga Scenedesmus obliquus grown heterotrophically on 13C-labelled glucose and acetate. Several isoprenoid compounds were isolated and investigated by 13C-NMR spectroscopy. According to the 13C-labelling pattern indicated by the 13C-NMR spectra, the biosynthesis of all plastidic isoprenoids investigated (prenyl side-chains of chlorophylls and plastoquinone-9, and the carotenoids beta-carotene and lutein), as well as of the non-plastidic cytoplasmic sterols, does not proceed via the classical acetate/mevalonate pathway (which leads from acetyl-CoA via mevalonate to isopentenyl diphosphate), but via the novel glyceraldehyde 3-phosphate/pyruvate route recently detected in eubacteria. Formation of isopentenyl diphosphate involves the condensation of a C2 unit derived from pyruvate decarboxylation with glyceraldehyde 3-phosphate and a transposition yielding the branched C5 skeleton of isoprenic units.

[A method of computer-assisted, 3-dimensional subtraction angiography using spiral roentgen computerized tomography]

The objective of this study was to develop a method for 3D subtraction CT angiography and to optimize the visualization after semi-automatic segmentation. Ten patients with aneurysms of the abdominal aorta were examined using spiral CT. To reconstruct the vessels, as well as adjacent organs such as the liver and kidneys, one image data volume was acquired before and after injection of the contrast agent. The CT scans were obtained with a Siemens Somatom Plus 4. To improve the results of automatic segmentation, as well as visualization by maximum intensity projection (i.e. removal of bony structures), subtraction of both image volumes is necessary. However, small translation shifts disturb the subtraction process and produce artificial contours. To calculate the disparities along the three coordinate axes of two corresponding image volumes, a cepstrum filter is applied to a pair of image volumes. After detection of the disparities, which manifest as bright spots, the real shift of the two subsignals can be calculated. Translation of the corresponding image volume pairs to their correct positions improves the subtraction process. In all cases the size of the aneurysm and the abdominal organs could be better segmented and visualized. Application of the cepstrum filter and subtraction of the image volumes before and after contrast medium injection completely removes the bony structures in the image data and results in superior visualization results.

Spirometrically controlled high resolution computed tomography - quantitative assessment of density distribution in patients with diffuse fibrosing alveolitis

STUDY OBJECTIVE

Lung density assessed by high resolution computed tomography (HRCT) is sufficiently sensitive for the diagnosis of interstitial lung disease, but may be hampered by uneven disease distribution. We determined the mean and subpleural density values in patients with diffuse fibrosing alveolitis (FA) and evaluated the diagnostic accuracy of both parameters, expressed as post-test odds ratios.

MATERIALS AND METHODS

Pulmonary HRCT was performed on 21 FA patients and compared to scans of 27 healthy volunteers. The HRCT procedure was standardized by taking 3 scans at the carina +/- 5 cm, and by defining inspiration levels at 50% vital capacity. Mean lung density (MLD) and subpleural lung density (SLD) were calculated for all participants.

RESULTS

MLD and SLD values for healthy subjects were significantly higher compared with the patient group. Odds ratios were 7.8:1 and 3.9:1 for SLD and MLD, respectively, demonstrating a superior discrimination power of SLD in the diagnosis of FA.

CONCLUSION

Diagnostic accuracy of quantitative HRCT measurements in FA was improved by the separate evaluation of subpleural lung density, which is a better indicator of the presence or absence of lung fibrosis than is mean lung density.

[Quantitative computerized tomography of the lung--respiration controlled diagnosis of diffuse lung diseases]

STUDY OBJECTIVE

Computed tomography provides measurements of lung attenuation which reflect changes in the air to tissue ratio and can thereby be employed for diagnosis of diffuse lung disease. In this prospective study, we quantitatively analyzed lung density by high resolution computed tomography (HRCT) in 26 healthy volunteers, 15 patients with chronic obstructive pulmonary disease (COPD), and 15 patients with idiopathic lung fibrosis (IPF). The procedure was standardized by examination of 3 scans at the carina +/- 5 cm and by defining inflation levels by %VC using an on-line hand held spirometer.

RESULTS

Performance of HRCT at 50% VC provides not only significant and distinguishable group data, but is the easiest to carry out for dyspneic patients. The mean lung density at 50% VC for healthy subjects was -820 +/- 4.2 (mean +/- SEM) Hounsfield units (HU). It was significantly lower (p < 0.01) in COPD patients (-865 +/- 9.2 HU), and considerably higher (-697 +/- 17.8 HU, p < 0.001) in the IPF group. At an inflation level of 20% VC, mean lung density values were similarly distributed, at significantly lower values relative to those at 50% VC, but the procedure was more difficult to perform for patients with dyspnea. In contrast, at 80% VC, lung density values for the COPD and control groups were not significantly different (p = 0.08). The sensitivity to detect COPD was improved by selecting HRCT values lower than -900 HU, which represent the part of the lung with an increased air/tissue ratio. For IPF patients an increase of lung density values above -699 HU was characteristic, indicating a decrease of the air/tissue relationship.

CONCLUSION

From our data we propose to perform quantitative HRCT measurements at 50% VC. Diagnosis of diffuse lung disease can be further improved by consideration of specific CT -value intervals. Spirometrically controlled quantitative HRCT is a clinically meaningful tool for the assessment of diffuse parenchymal lung disease.

Spirometrically controlled quantitative CT for assessing diffuse parenchymal lung disease

OBJECTIVE

Assessment of lung attenuation by CT reflects changes in the air-to-tissue ratio of the lung. We have analyzed the interdependence of intrathoracic gas volume, lung morphology, and functional disorder by high resolution CT (HRCT) to assess quantitative disease threshold in obstructive and restrictive diffuse lung disease.

MATERIALS AND METHODS

Pulmonary HRCT was performed on 24 healthy volunteers, 11 patients with chronic obstructive pulmonary disease (COPD), and 16 patients with idiopathic lung fibrosis (IPF). HRCT measurement was standardized by taking three scans at the carina +/- 5 cm and by defining inspiration levels by percent vital capacity (VC) via spirometrically gating to the scanner.

RESULTS

The mean lung density at 50% VC (DL50) for healthy subjects was -819 +/- 3.8 (mean +/- SEM) HU. In contrast, COPD DL50 was lower, averaging -861 +/- 6.4 HU, and the IPF DL50 was considerably higher (-731 +/- 17.7 HU), both significantly different (p < 0.001) compared with the control group. The accuracy of quantitative HRCT at different inspiration levels was evaluated by scanning the basal layer at 20, 50, and 80% VC. The control values were -747 +/- 5.6, -816 +/- 3.6, and -855 +/- 3.0 HU, respectively, which were significantly higher (p < 0.001) than those seen in COPD patients at 20 and 50% VC. Again, the IPF patients exhibited increased lung density (p < 0.001) at all inspiratory levels. Discrimination power was best among all cohorts at 20 and 50% VC. Position-dependent artifacts on lung density were quantified by the anteroposterior density gradient (APG). Irrespective of the underlying disease, APG at 50 and 80% VC was similar, but was up to twofold higher at 20% VC, indicating that quantitative estimates near RV may misrepresent mean lung density.

CONCLUSION

Our data indicate that quantitative HRCT measurements should be performed not near full inspiration or expiration, but at an intermediate degree of lung inflation, e.g., 50% VC, for reasons of accuracy, intra- and intersubjective comparability, and feasibility. We conclude quantitative HRCT to be a sensitive tool for the evaluation of diffuse parenchymal lung disease.

Functional promoter and polyadenylation site mapping of the human serotonin (5-HT) transporter gene

We have isolated and characterized the 5'-flanking region and the proximal polyadenylation site of the human 5-HT transporter gene. The major gene transcript is 2,793 bp in length and it contains 208 bp of 5'-untranslated region (5'-UTR) and 694 bases of 3'-UTR. While only a single mRNA species occurs in rats and mice, the most proximal signal for polyadenylation in the human gene appears to be highly degenerate in comparison to the rat and murine motif. This polyadenylation signal-like motif may lead to alternate usage of additional polyadenylation sites resulting in multiple mRNA species in humans. A TATA-like motif and several potential binding sites for transcription factors including AP1, AP2, SP1, and a cAMP response element (CRE)-like motif are present in the 5'-flanking region. A approximately 1.7 kb fragment beginning 217 bp downstream from the transcription start site, which had been ligated into a luciferase reporter vector and transiently expressed in JAR human placental choriocarcinoma cells, displayed both constitutive and forskolin/cholera toxin-induced promoter activity. Functional promoter mapping revealed that there are negative attenuating elements between bp -1,428 and -1,185 and positive elements between bp -1,184 and -78 from the transcription initiation site. Studies with deletional mutants also indicated that core promoter sequences are contained within 78 bp of the transcription start site and that regulation of cAMP-inducible promoter activity depends on multiple cis-acting elements including two AP1 binding sites and a single CRE-like element located at bp -99. Our findings suggest that (1) the 5-HT transporter gene promoter is active in human JAR cells, but inactive in 5-HT transporter-deficient human SK-N-SH neuroblastoma and HeLa cells, (2) the information contained within 1.4 kb of 5'-flanking sequence is sufficient to confer its cell-specific expression, (3) the promoter responds to cAMP induction, and (4) the expression of the 5-HT transporter gene is regulated by a combination of positive and negative cis-acting elements operating through a basal promoter unit defined by a TATA-like motif.

Ongoing enterovirus-induced myocarditis is associated with persistent heart muscle infection: quantitative analysis of virus replication, tissue damage, and inflammation

Coxsackievirus B3-induced myocarditis in different immunocompetent mouse strains was used as a model to investigate interrelationships between virus replication and development of chronic enteroviral heart disease. Using in situ hybridization to detect enteroviral RNA, we show that heart muscle infection is not only detected in acute myocarditis but is also detected during the chronic phase of the disease. Coxsackievirus B3 could evade immunological surveillance in a host-dependent fashion, thus inducing a persistent infection of the myocardium in association with ongoing inflammation. Patterns of acute and persistent myocardial infection were quantitatively assessed in one representative mouse strain (A.CA/SnJ, H-2f) by applying computer-assisted digital image processing; these patterns were then related to the extent of myocardial tissue damage as well as to inflammation. We observed a strong correlation, both spatial and temporal, between viral replication and development of myocardial lesions, indicating that acute and chronic myocardial injuries are a consequence of multifocal organ infection. Analysis of strand-specific in situ hybridization revealed that viral replication in persistent infection is restricted at the level of RNA synthesis. The described procedure for quantitating organ infection provides a powerful tool for evaluating virus-host interactions and will be of particular interest to those studying human enterovirus-induced cardiomyopathies.

Natural history of Coxsackievirus B3-induced myocarditis in ACA/Sn mice: viral persistence demonstrated by quantitative in situ hybridization histochemistry

Enteroviruses are considered to be the major aetiological agents of myocarditis in humans. Recent in situ hybridization studies on endomyocardial biopsies and autopsy hearts indicate that enterovirus RNA can be detected (pattern of persistent infection) not only in acute myocarditis (pattern of acute infection), but also in chronic dilated cardiomyopathy. Our experimental studies on murine coxsackievirus B3 myocarditis provided evidence that persistent infection may also occur in mice. Quantitative in situ hybridization and immunohistochemistry as well as electron microscopical in situ hybridization experiments were performed on ACA/SnJ mice 3-30 days after infection. The pattern of acute infection (days 3-9 p.i.) is characterized by rapid progression of myocardial lesions, an increasing number of inflammatory cells and a high number of infected myocytes. Hallmarks of the persistent pattern (days 15-30 p.i.) are reduced inflammation, reduced numbers of persistently infected cells and a slow progression of myocardial lesions. Infection is primarily restricted to degenerated, atrophic myocytes and to fibroblasts.