Biomedical subjects
Publications and source records attributed to H Hoppe.
The introduced new developed navigation system is a High Intensity Approach Light System for augmented reality in image-guided surgery. The surgeon follows the projected approach lights with his ordinary surgical instruments. Thus, tracked instruments are not necessary with this system.
We conducted a comprehensive Kelvin probe force microscopy (KPFM) study on a classical organic solar cell system consisting of MDMO-PPV/PCBM blends. The KPFM method yields the information of topography and local work function at the nanometer scale. Experiments were performed either in the dark or under cw laser illumination at 442 nm. We identified distinct differences in the energetics on the surface of chlorobenzene and toluene cast blend films. Together with high-resolution scanning electron microscopy (SEM) experiments we were able to interpret the KPFM results and to draw some conclusions for the electron transport toward the cathode in the solar cell configuration. The results suggest that surfaces of toluene cast films exhibit a morphologically controlled hindrance for electron propagation toward the cathode, which is usually evaporated on top of the films in the solar cell device configuration.
BACKGROUND: Surgical planning and tumor margins from preoperative image data sets can be transferred to the surgical site by use of computer-assisted navigation systems. Usually registration markers are placed prior to image data acquisition in order to correlate the patient's preoperative image data set with his/her position in the operating room. Pointers are commonly used for navigation, and the position of the pointer within the surgical site is compared to its position within the image data set. With a new navigation system, patient registration can be performed without registration markers. Tumor margins and osteotomy lines can be projected onto the surgical site. MATERIALS AND METHODS: With the new navigation system, which has been developed by the Sonderforschungsbereich 414 of the Deutsche Forschungsgemeinschaft, markerless patient registration is performed using the contours of the patient's face. A scanner is mounted above the operating table, which detects the surface of the surgical site intraoperatively. Osteotomy lines and tumor margins are projected onto this surface using an intense beamer. The procedure is illustrated for a patient with a meningeal tumor of the orbit. RESULTS: Patients can be registered with an accuracy of 1 mm. Pointers are not required to transfer the data on the surgical site. Furthermore, monitors are no longer required, since the information is projected directly on the patient's surface. CONCLUSIONS: Surgical planning and tumor margins can exactly be visualized within the surgical site. Ergonomics are especially improved for navigated orbitotomies via a coronal approach.
Unenhanced spiral computed tomography is now applied in the investigation of patients with acute flank pain to search for suspected urinary tract calculi. Spiral CT can depict urinary calculi more accurately than plain radiographs, sonography or excretory urography, and can be performed using a low dose protocol. Almost all urinary calculi, including calculi composed of uric acid, xanthine and cystine, can be detected. In addition to determining size and location of the stone, unenhanced helical CT can predict its composition. Furthermore, it reveals secondary signs of obstruction, such as dilatation of the renal collecting system and perinephric stranding. In the absence of urolithiasis, CT can frequently detect or exclude other causes of acute flank pain, thus guiding subsequent imaging and the therapeutic management.
PURPOSE: To evaluate benefit, feasibility, and frequency of complications with transjugular liver biopsy using a semi-automatic Tru-cut system. MATERIALS AND METHODS: Eighty-five consecutive patients (57 males, 28 females) with various liver disorders (cirrhosis [30], hepatitis [12], acute hepatopathy [34], orthotopic liver transplantation [8], hepatocellular carcinoma [1]), coagulopathies (n=71) and/or ascites (n = 46) were referred to our department for a transjugular liver biopsy. Mean age was 48 +/- 16 years (range 17 to 75 years). Success and complications were retrospectively evaluated from the radiology reports, pathology reports, and patient files. Success was defined as procuring a tissue specimen that enabled a definite histological diagnosis. The complications included thrombosis at the puncture site, hematoma, cardiac arrhythmia, capsular perforation, hemorrhage, and cardiac damage. Mortality included all deaths within 30 days after the procedure. Procedure-related mortality included all deaths related to the procedure. RESULTS: The procedure was technically successful in 80 patients (94 %) and unsuccessful in 5 patients (6 %) due to a failed hepatic vein cannulation (1 patient with Budd Chiari syndrome and total liver vein occlusion, 4 patients with unsuitable anatomy). One biopsy pass was made in 22 patients, and two passes were made in 45 and three or more passes in 14 patients, all in a single session. The sample quality was judged by the pathologist as good in 71 of 80 patients (89 %) and poor in 8 patients (10 %). A diagnosis was not possible in 1 patient. Eight procedure-related complications occurred, which were classified according to the criteria of the Society of Interventional Radiology (SIR) as minor in 5 (3 type A, 2 type B) and major in 3 (1 pneumothorax, type C, 1 nonfatal bleeding, type D, and 1 fatal bleeding, type F). Procedure-related mortality was 1 %, overall mortality 15 % (mostly due to progressive liver failure). CONCLUSION: In patients with coagulopathies, transjugular liver biopsy is a viable alternative for hepatic tissue evaluation with a good sample quality. In a small number of patients severe complications may occur.
Virtual endoscopy of the upper, central and peripheral airways (virtual laryngoscopy or virtual bronchoscopy) produces endoluminal images similar to those of fiberoptic endoscopy. In particular, virtual endoscopy is useful for the assessment of endoluminal tumor extent and tracheobronchial stenosis. Especially since the introduction of multirow detector CT, high-resolution virtual-endoscopic images of the airways can be reconstructed. Either surface rendering or volume rendering can be used for realistic depiction of the airways. Semitransparent color-coded volume rendering is advantageous, because adjacent structures can be displayed in addition to endoluminal views. A major advantage of virtual endoscopy over fiberoptic endoscopy is its non-invasiveness. With virtual endoscopy, even a high-grade stenosis is passable, enabling evaluation of the distal airways. Disadvantages are its inability to depict mucosal color and to perform therapeutic maneuvers. In comparison to other CT display modes, virtual endoscopy allows a more realistic assessment of tracheobronchial stenosis than axial CT slices and multiplanar reformats. Virtual endoscopy of the airways can be used complementary to fiberoptic endoscopy before tracheotomy, stent implantation or lung resection and for post-operative follow-up. In the future, virtual airway endoscopy will be increasingly applied for interactive virtual reality guidance of airway procedures such as bronchoscopy and surgery.
PURPOSE: To evaluate the benefit and feasibility of gadolinium contrast agents for intra-arterial use in diagnostic and therapeutic angiography in patients with renal insufficiency. METHODS: In 15 patients with planned peripheral or renal vascular interventions digital subtraction angiography with intra-arterial administration of gadolinium (gadodiamide n = 14, gadolinium-DTPA n = 1) was performed. Gadolinium was used selectively after peripheral catheter placement, mainly as an adjunct to CO2 (n = 12), to assess the distal run-off vessels or to characterize stenotic lesions. RESULTS: In 14 cases gadolinium yielded good or satisfactory results that were superior to those of CO2 angiography in the femoropopliteal region and calf, but also to the aorto-iliac vessels and the renal arteries. A small amount of iodinated contrast media was administered due to insufficient contrast of gadolinium in one patient. Mean serum creatinine level after angiography (295 +/- 167 micromol/l; range 125 - 764 micromol/l) was not significantly different (p >/= 0,37) from the initial level (279 +/- 149 micromol/l; range 143 - 728 micromol/l). CONCLUSION: Gadolinium is a viable alternative contrast agent for digital subtraction angiography and percutaneous transluminal angioplasty in patients with renal insufficiency. It enhances the diagnostic evaluation of stenosis and run-off vessels.
PURPOSE: A controlled trial was performed to compare non-invasive multislice CT (virtual laryngoscopy, axial CT slices, coronal and sagittal reformats) in the detection and grading of upper airway stenosis with fiberoptic laryngoscopy. MATERIAL AND METHODS: Multislice CT and fiberoptic laryngoscopy were used to examine 111 upper airway sections (supraglottis, glottis, subglottis, trachea) in 29 patients. CT data were acquired on a multirow detector CT (collimation 4 x 1 mm, reconstruction interval 1 mm, IV contrast) and postprocessing was performed using multiplanar reformatted images (MPR) and virtual laryngoscopy. RESULTS: All CT methods accurately detected upper airway stenosis (accuracy was 96 % for virtual laryngoscopy and MPR and 94 % for axial CT-slices). Correlation of fiberoptic and virtual laryngoscopy (r = 0.94) for grading of stenosis was closer than with sagittal reformats (r = 0.80), coronal reformats (r = 0.72), and axial CT slices (r = 0.57). Even high grade stenosis could be passed with virtual laryngoscopy that was impassable for fiberoptic laryngoscopy. CONCLUSIONS: Virtual laryngoscopy enabled better assessment of stenosis as compared to reading of axial CT slices or MPR. Virtual laryngoscopy is complementary to fiberoptic laryngoscopy and should be combined with axial CT slices and MPR readings for evaluation of the surrounding structures.
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The preoperative planning of complex craniofacial surgical interventions is increasingly realized with the aid of appropriate planning systems in order to achieve high precision, minimal invasion and protection of risk areas. But the most important step from the planning to the actual intervention consists of providing the planning data intraoperatively in a reasonable and easy to handle way. In this regard, augmented reality is one of the most challenging and promising techniques to solve this problem. In this paper we present two different systems based on see-through glasses resp. a common video projector to directly visualize the planning data in the surgeon's field of view. The work is funded by the 'Deutsche Forschungsgemeinschaft (DFG)' and Stryker Leibinger Freiburg/Germany.
Advances in conformal radiation therapy to control disease via dose escalation are challenged by set-up uncertainties. Recently, techniques have been developed to use surface features to evaluate the patient's position and correct it where necessary. The aim of this study was to use the patient's surface as a tool for daily set-up control and monitoring. We use a surface scanner based on the projection of coded light to receive--in a daily routine--a large amount of surface points which enables us to register the CT-based planning data with the patients current position. By superimposing current and planned volumes, a volume of congruency was obtained. An error below 1 mm was considered acceptable. In cases where set-up was not satisfactory a map of the surface comparison was evaluated showing the areas of missing alignment. According to this information a manual repositioning was performed. This procedure was repeated until the error was acceptable. No more then 3 repetitions where necessary to obtain an acceptable result. The whole procedure including registration, calculation and visualization took about 20 sec for one repetition. The use of structured light projection in the daily set-up control and monitoring proved to be a noninvasive, easy, quick, inexpensive and reliable solution.
In the treatment of malignant disease external beam radiation therapy (EBRT) is often combined with surgery. Intraoperative radiotherapy (IORT) improves the local control by dose escalation. For reasons of recording, improvement and security of the intervention, it would be necessary to merge the IORT-dose distribution with the postoperative CT-based EBRT-planing. The aim of this work was to develop a method to reconstruct the IORT field and register it with the postoperative planing CT. This enables the reconstruction of the IORT dose distribution and merge it with the CT-based EBRT planing data. We use a surface scanner to receive a large amount of surface points which enables us reconstruct the IORT-field and to register it with the CT-based EBRT planning data. Scanning and calculation time is not over 2 seconds, depending mainly on the CPU power. The error of a single point is below 1 mm. The density of the point cloud is approx. 4 per mm2. In this paper we give an overview of our experimental setup and the accuracy of the method.
A continuous fermentation process has been developed in Pichia pastoris (P. pastoris) with the glyceraldehyde-3-phosphate dehydrogenase (GAP) promoter in order to produce large quantities of recombinant human chitinase (rh-chitinase) for preclinical studies as a potential high-dose antifungal drug. Expression levels of about 200 to 400 mg/L have been demonstrated in fed-batch fermentations using strains with either the traditional methanol-inducible or the constitutive GAP promoter. Proteolytic degradation of the enzyme was typically seen in fed-batch fermentations. Continuous production of the enzyme by P. pastoris with the GAP promoter was demonstrated in a 1.5-L working volume fermentor using either glucose or glycerol as the carbon source. The fermentation could be extended for >1 month with a steady-state protein concentration of approximately 300 mg/L. Cell densities were >400 g/L wet cell weight (WCW) (approximately 100 g/L dry cell weight [DCW]) at a dilution rate (D) of 0.83 day(-1) or 1.2 volume exchanges per day (VVD). No proteolytic degradation of the enzyme was seen in the continuous fermentation mode.
Films of spinodally decomposing binary liquid mixtures show transient wetting of both confining interfaces by one of the phases, and rupture, with characteristic wavelength lambda(c) and time tau(rupture), leading to flat droplets of the nonwetting phase encapsulated by the wetting phase. Over the entire range of film thicknesses d approximately 100-3500 nm, we find tau(rupture)~d(1.01+/-0.08), indicating film structures that scale self-similarly with d, and find also that lambda(c) approximately 60d(0.97+/-0.03), the large prefactor suggesting a rupture wavelength which minimizes the interfacial tension of the roughened film.
Surprisingly alkaline phosphatase (AP) (EC 3.1.3.1) of calf intestine is found in large amounts, e.g. 80%, within chyme. Most of the enzyme is present as a mixture of four differently hydrophobic anchor-bearing forms and only the minor part is present as an anchorless enzyme. To investigate whether changes in the N-glycosylation pattern are signals responsible for large-scale liberation from mucosa into chyme, the glycans of the two potential glycosylation sites predicted from cDNA were investigated by matrix-assisted laser desorption/ionization and electrospray ionization mass spectrometry in combination with exoglycosidase treatment after tryptic digestion and reversed-phase chromatography. The glycans linked to Asn249 are at least eight different, mainly non-fucosylated, biantennary or triantennary structures with a bisecting N-acetylglucosamine. For the most abundant glycopeptide (40%) the following glycan structure is proposed: [carbostructure: see text]. The glycans linked to Asn410 are a mixture of at least nine, mainly tetraantennary, fucosylated structures with a bisecting N-acetylglucosamine. For the most abundant glycopeptide (35%) the following glycan structure is proposed: [carbostructure: see text]. For the structures the linkage data were deduced from the reported specificities of the exoglycosidases used and the specificities of the transglycosidases active in biosynthesis. The majority of glycans are capped by alpha-galactose residues at their non-reducing termini. In contrast to the glycans linked to other AP isoenzymes, no sialylation was observed. Glycopeptide 'mass fingerprints' of both glycosylation sites and glycan contents do not differ between AP from mucosa and chyme. These results suggest that the observed large-scale liberation of vesicle-bound glycosylphosphatidylinositol (GPI)-anchored AP from mucosa into chyme is unlikely to be mediated by alteration of glycan structures of the AP investigated. Rather, the exocytotic vesicle formation seems to be mediated by the controlled organization of the raft structures embedding GPI-AP. (c) 2001 John Wiley & Sons, Ltd.
A case of a 43-year-old patient with recurrent pulmonary infections due to pulmonary sequestration is presented. MR-angiography revealed an aberrant artery originating from the abdominal aorta feeding the intralobar pulmonary sequestration. Platinum coil embolization of the aberrant artery was performed preoperatively to allow safe surgical resection on the following day. To our knowledge this is the first case in the literature in which elective coil embolization has been performed before resection of lung sequestration.
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Until recently an internet presentation of a surgical department could rarely be found on the World Wide Web (WWW). Today an increasing number of departments provide a Web site, but often contents and graphics can still be improved. For more than 4 years the Department of Surgery at the University Hospital of Würzburg has maintained an internet presentation (www.chirurgie.uni-wuerzburg.de). Contents and technical features have been continuously updated. In order to provide a powerful Web site, contents were structured for the 3 target groups: visitors, that are patients including their relatives (consultation hours, directions, maps of campus and wards), physicians (main points in diagnostics and therapy, research, publications, further education, job offers) and medical students (teaching schedules, courses, learning materials). Concerning the technical aspects of the Web site, emphasis was put on a distinct layout and clear design. Therefore, text was arranged in tables or lists and a limited number of standard fonts was used. Graphics were compressed to a minimum file size. To allow effortless navigation for the visitor two roll-over menu banners, a sitemap, a search tool and easy-to-follow symbols were implemented. The internet is an important source of information, and used correctly, the WWW is very useful for the presentation and communication of a surgical department.