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Biomedical subjects

R Lenz

Publications and source records attributed to R Lenz.

At least 19 recordsLinked to original sources

Improving pathway compliance and clinician performance by using information technology.

To deliver patient-specific advice at the time and place of a consultation is an important contribution to improving clinician performance. Using computer-based decision support on the basis of clinical pathways is a promising strategy to achieve this goal. Thereby integration of IT applications into the clinical workflow is a core precondition for success. User acceptance and usability play a critical role: additional effort has to be balanced with enough benefit for the users and interaction design and evaluation should be handled as an intertwined, continuous process. Experiences from routine use of an online surgical pathway at Marburg University Medical Center show that it is possible to successfully address this issue by seamlessly integrating patient-specific pathway recommendations with documentation tasks which have to be done anyway, by substantially reusing entered data to accelerate routine tasks (e.g. by automatically generating orders and reports), and by continuously and systematically monitoring pathway conformance and documentation quality.

Academic Medical Centers↗

IT support for clinical pathways--lessons learned.

Clinical pathways are an effective instrument to decrease undesired practice variability and improve clinician performance. IT applications embedded into clinical routine work can help to increase pathway compliance. Successfully implementing such applications requires both a responsive IT infrastructure and a participatory and iterative design process aimed at achieving user acceptance and usability. Experiences from the implementation and iterative improvement of an online surgical pathway at Marburg University Medical Centre have shown that pathway conformance actually could be improved by the use of IT. An analysis of the iterative design process has shown that future pathway projects can benefit from the lessons learned during this project. Based on these lessons a method for developing well adapted interaction mechanisms is presented, which is aimed at improving process alignment. Our goal is to build up a library of tested reusable components to reduce the number of iterations for pathway implementation.

Academic Medical Centers↗

Demand-driven evolution of IT systems in healthcare--a case study for improving interdisciplinary processes.

OBJECTIVES: To analyze and to optimize interdisciplinary clinical processes, to introduce an IT-supported model for demand-driven system evolution in healthcare, and to demonstrate the feasibility of the approach for a clinical example and to present an evaluation. METHODS: System evolution and change management are viewed as two sides of the same coin, thus formal methods for process analysis and IT system evolution were embedded into a goal-oriented change management model. Based on a process model, a Failure Mode and Effects Analysis (FMEA) and a computer simulation were performed. A tool for rapid application development (RAD) was used to incrementally improve the healthcare information system according to newly arising needs. RESULTS: Each of the formal methods used contributed to the successful reorganization of the interdisciplinary clinical process. An evaluation demonstrated significant improvements. An integrated IT application was implemented to support the optimized process. CONCLUSIONS: Process improvement is feasible and effective when formal methods for process analysis and requirements specification are used in a reasonable and goal-oriented way. It might be necessary to trade off costs and benefits or simplify a given method in the context of a particular project. As the same information is utilized in different tools, it is supposed that the efforts for process analysis, documentation and implementation of adapted applications could be reduced if different tools were integrated and based on a single coherent reference model for description of clinical processes.

Computer Simulation↗

Improving pathway compliance and clinician performance by using information technology.

To deliver patient-specific advice at the time and place of a consultation, to improve clinician performance and compliance by using computer-based decision support, and to integrate such IT solutions with the clinical workflow are important strategies for the implementation of clinical pathways. User acceptance plays a critical role: additional effort has to be balanced with enough benefit for the users. Experiences from routine use of an online surgical pathway at Marburg University Medical Center show that it is possible to successfully address this issue by seamlessly integrating patient-specific pat documentation tasks which have to be done anyway and by substantially reusing entered data to accelerate routine tasks (e.g. by automatically generating orders and reports).

Academic Medical Centers↗

Towards a continuous evolution and adaptation of information systems in healthcare.

OBJECTIVES: To address the problem of alignment of health information systems to healthcare processes, which is a major challenge in healthcare organizations; to present a layered approach for system evolution and adaptation based on an application framework and rapid application development; to accomplish a demand-driven system evolution by embedding the software engineering process in business process optimization projects and by closely involving end users to improve their own work practices. METHODS: We have used a holistic health information system as a core application framework. System functionality is incrementally improved using an integrated "generator tool" for rapid application development. We have developed an iterative and participatory software engineering process, adapted to the conditions of the generator tool. The documentation techniques provided by the Unified Modeling Language (UML) were modified to achieve a straight forward documentation covering the whole development cycle from the business process model to generator-based computer applications. RESULTS AND CONCLUSION: The layered approach for system evolution did provide an environment in which a flexible and participatory software development process could be established. Today, generator-based applications are used in all clinical departments of our 1200-bed University Hospital. We expect that tools for rapid application development will be further improved and will play an increasingly important role to establish responsive IT-infrastructures where the application developer can concentrate on business process alignment instead of coding and debugging.

Academic Medical Centers↗

Experiences with a generator tool for building clinical application modules.

OBJECTIVES: To elaborate main system characteristics and relevant deployment experiences for the health information system (HIS) Orbis/OpenMed, which is in widespread use in Germany, Austria, and Switzerland. METHODS: In a deployment phase of 3 years in a 1.200 bed university hospital, where the system underwent significant improvements, the system's functionality and its software design have been analyzed in detail. We focus on an integrated CASE tool for generating embedded clinical applications and for incremental system evolution. We present a participatory and iterative software engineering process developed for efficient utilization of such a tool. RESULTS: The system's functionality is comparable to other commercial products' functionality; its components are embedded in a vendor-specific application framework, and standard interfaces are being used for connecting subsystems. The integrated generator tool is a remarkable feature; it became a key factor of our project. Tool generated applications are workflow enabled and embedded into the overall data base schema. Rapid prototyping and iterative refinement are supported, so application modules can be adapted to the users' work practice. CONCLUSIONS: We consider tools supporting an iterative and participatory software engineering process highly relevant for health information system architects. The potential of a system to continuously evolve and to be effectively adapted to changing needs may be more important than sophisticated but hard-coded HIS functionality. More work will focus on HIS software design and on software engineering. Methods and tools are needed for quick and robust adaptation of systems to health care processes and changing requirements.

Computer Systems↗

Molecular characterization of the salutaridinol 7-O-acetyltransferase involved in morphine biosynthesis in opium poppy Papaver somniferum.

Salutaridinol 7-O-acetyltransferase (EC ) catalyzes the conversion of the phenanthrene alkaloid salutaridinol to salutaridinol-7-O-acetate, the immediate precursor of thebaine along the morphine biosynthetic pathway. We have isolated a cDNA clone that corresponds to the internal amino acid sequences of the native enzyme purified from a cell suspension culture of opium poppy Papaver somniferum. The recombinant enzyme acetylated the 7-hydroxyl moiety of salutaridinol in the presence of acetyl-CoA. The apparent K(m) value for salutaridinol was determined to be 9 microm and 54 microm for acetyl-CoA. The gene transcript was detected in extracts from Papaver orientale and Papaver bracteatum in addition to P. somniferum. Genomic DNA gel blot analysis indicated that there is likely a single copy of this gene in the P. somniferum genome. The amino acid sequence of salutaridinol 7-O-acetyltransferase is most similar (37% identity) to that of deacetylvindoline acetyltransferase of Catharanthus roseus. Salutaridinol 7-O-acetyltransferase is the second enzyme specific to morphine biosynthesis for which we have isolated a cDNA. Taken together with the other cDNAs cloned encoding norcoclaurine 6-O-methyltransferase, (S)-N-methylcoclaurine 3'-hydroxylase, the cytochrome P-450 reductase, and codeinone reductase, significant progress has been made toward accumulating genes of this pathway to enable the end goal of a biotechnological production of morphinan alkaloids.

Acetyltransferases↗

Diagnosis of babesiosis using an immunoblot serologic test.

Although the current indirect immunofluorescent assay (IFA) diagnostic antibody test for human babesiosis is sensitive and specific, an immunoblot antibody test may be easier to standardize and to perform. Our objective, therefore, was to determine the efficacy of and develop interpretive criteria for an immunoblot antibody test for diagnosing acute human babesiosis using a Babesia microti whole-cell lysate as the antigen. We compared the reactivity of sera to a B. microti immunoblot assay in 24 human subjects experiencing symptoms and expressing laboratory evidence of babesiosis, 28 subjects who experienced Lyme disease, 12 subjects who experienced human granulocytic ehrlichiosis, and 51 subjects who reported no history of any of these diseases and whose sera did not react against B. microti antigen in an IFA test. Immunoblot strips were impregnated with proteins derived from the GI strain of B. microti that had been electrophoresed in an acrylamide sodium dodecyl sulfate gel, followed by electroblotting onto nitrocellulose membranes. The sera of all subjects who experienced babesiosis reacted against the B. microti antigen in the IFA and against at least one of nine immunoblot protein bands specific to B. microti. In contrast, none of the sera from people who appeared not to have experienced this infection reacted against the B. microti antigen in the IFA (compared to 4% in the immunoblot assay). When two reactive bands were considered as definitive, immunoblot test sensitivity was 96%, while specificity was 99% and predictive positivity and predictive negativity were 96 and 99%, respectively. Our B. microti immunoblot procedure shows promise as a sensitive, specific, and reproducible assay for routine clinical diagnosis of acute babesiosis.

Antibodies, Protozoan↗

Light scattering and ink penetration effects on tone reproduction.

Light scattering, or the so-called Yule-Nielsen effect, and ink penetration into the substrate paper play important roles in tone reproduction. We develop a framework in which the influences of both of these effects on the reflectance and tristimulus values of a halftone sample are investigated. The properties of the paper and the ink and their bilateral interaction can be parameterized by the reflectance Rp(o) of the substrate paper, the transmittance Ti of the ink layer, the parameter gamma describing the ink penetration, and p describing the Yule-Nielsen effect. We derive explicit expressions that relate the reflectance of the ink dots (Ri), the paper (Rp) and the halftone image (R) as functions of these parameters. We also describe the optical dot gain as a function of these parameters. We further demonstrate that ink penetration leads to a decrease in optical dot gain and that scattering in the paper results in the printed image's being viewed as more saturated in color.

Journal Article↗

Intranet meets hospital information systems: the solution to the integration problem?

Based on the results of an extensive market analysis and technology assessment, this paper summarizes the state of the art in web technology and compares it with the needs of integration in hospital information systems. Web technology and intranet have evolved to a core technology for distributed computing and distributed information systems. The advantage of platform independent distribution of information has led to euphoric visions of future integrated systems. However, true integration takes more than transparent access to heterogeneous information sources. To overcome the essential problems related to integration of autonomous systems it is important to find a common ontological basis for future component based systems.

Computer Communication Networks↗

Mechanism and rate of degradation of polyhydroxyoctanoate films in aqueous media: A long-term in vitro study.

The present study investigated the in vitro mechanism and degradation rate of polyhydroxyoctanoate (PHO). Solution-cast PHO films were incubated in either water or isoosmotic phosphate-buffered saline (PBS) for periods ranging from 1 to 24 months. Physical characterization included weight loss, water absorption, pH change, tensile strength, and scanning electron microscopy (SEM) studies. Analytical investigations including electron spectroscopy for chemical analysis, Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), wide-angle X-ray diffraction, and size exclusion chromatography were also performed to assess chemical and morphological changes to the structure of the PHO. The results show that the PHO-cast films incubated in either water or isoosmotic PBS underwent a simple hydrolytic degradation process characterized by water absorption, gradual molecular weight decrease, and negligible mass loss after 24 months of incubation. DSC results suggest that degradation occurred in the amorphous zone, followed by an attack in the crystalline domain. An increase in the vibration stretching of OH after 24 months of incubation, as revealed by FTIR, may indicate that the degradation process began internally, moving outwardly toward the surface of the PHO films. This process was more rapid in the films incubated in PBS than in those incubated in water. However, no significant changes in the morphology of the films were detected by SEM. This study demonstrated that the in vitro degradation of PHO in water or in PBS is a very slow hydrolytic process, exceeding 2 years. Our findings also suggest that the internal degradation mechanism is faster in PBS because of the ionic strength of the medium and that this internal process surface moves gradually toward the surface.

Biocompatible Materials↗

Chemoenzymatic synthesis of L-galactosylated dimeric sialyl Lewis X structures employing alpha-1,3-fucosyltransferase V.

L-Galactosylated dimeric sialyl Lewis X (SLeX) has been prepared employing a combination of chemical and enzymatic synthetic methods. GDP-L-galactose has been chemically synthesised. Enzymatic transfer of L-galactose onto the acceptor (Sia-alpha2,3-Gal-beta1,4-GlcNAc-beta1,3/6)2-Man-alpha1-OMe was achieved using the human alpha-1,3-fucosyltransferase V.

Carbohydrate Sequence↗

[Selection of a hospital information system--experiences and critical aspects].

Due to typical problems (heterogeneity, lack of clinical functionality, Y2K problems) the board of directors of the university hospital of Marburg decided in 1997 to replace major components of the existing system by commercially available software. The products available on the market were analyzed, and, under participation of different user groups, a comprehensive functional specification was generated. This was the basis for a Europe-wide vendor selection process. In this context, several key aspects were identified, which are critically important for realizing a HIS that fulfills the specified functional requirements. Among these key aspects are the integration of heterogeneous system components, the support of cross-departmental workflow, and flexibility as well as adaptability to specific clinical requirements. As a result, we found that with today's commercially available products and standards there is no single solution that fully meets all requirements. However, some "generalist" vendors are offering integrated systems with acceptable clinical functionality. Tools are emerging which enable the clinical user to generate forms for data input and data flow. Still, a hospital information system will consist of separate components that have to be integrated, but the role of integrated, component-based approaches is becoming more important.

Computer Systems↗

Molecular cloning and functional expression of codeinone reductase: the penultimate enzyme in morphine biosynthesis in the opium poppy Papaver somniferum.

The narcotic analgesic morphine is the major alkaloid of the opium poppy Papaver somniferum. Its biosynthetic precursor codeine is currently the most widely used and effective antitussive agent. Along the morphine biosynthetic pathway in opium poppy, codeinone reductase catalyzes the NADPH-dependent reduction of codeinone to codeine. In this study, we have isolated and characterized four cDNAs encoding codeinone reductase isoforms and have functionally expressed them in Escherichia coli. Heterologously expressed codeinone reductase-calmodulin-binding peptide fusion protein was purified from E. coli using calmodulin affinity column chromatography in a yield of 10 mg enzyme l-1. These four isoforms demonstrated very similar physical properties and substrate specificity. As least six alleles appear to be present in the poppy genome. A comparison of the translations of the nucleotide sequences indicate that the codeinone reductase isoforms are 53% identical to 6'-deoxychalcone synthase from soybean suggesting an evolutionary although not a functional link between enzymes of phenylpropanoid and alkaloid biosynthesis. By sequence comparison, both codeinone reductase and 6'-deoxy- chalcone synthase belong to the aldo/keto reductase family, a group of structurally and functionally related NADPH-dependent oxidoreductases, and thereby possibly arise from primary metabolism.

Alcohol Oxidoreductases↗

Effect of sterilization on the physical and structural characteristics of polyhydroxyoctanoate (PHO).

The present study examined the potential applicability of poly(beta-hydroxy octanoate) (PHO), a bacterial polyester, as a candidate for biomaterial applications, by investigating the effect of sterilization on the physical and structural characteristics of PHO. PHO-cast films were sterilized by either ethylene oxide (EO) gas at 38 degrees C or gamma radiation (2.5 Mrad) in air at room temperature. The physical characteristics of the EO and gamma-sterilized PHO were determined by scanning electron microscopy (SEM) and tensile strength analyses. In addition, various analytical methods were used to detect modifications in the chemical and morphological structure of PHO, namely, electron spectroscopy for chemical analysis (ESCA), Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), and size exclusion chromatography (SEC). The results show that EO sterilization did not modify the chemical and physical characteristics of PHO, however, significant modifications in both the structural and tensile properties were observed with gamma-sterilized PHO. These changes accounted for decreases in both the weight average, number average and melting temperature, and increases in the heat of fusion and tensile strength. No residual EO was detected following sterilization as revealed by head-space chromatography. The physical and structural properties of PHO were shown to be well preserved following EO sterilization, whereas gamma radiation caused random chain scission and physical cross-linking, a frequent phenomenon observed with organic polymers.

Bacteria↗

Hydrolytic and enzymatic incubation of polyhydroxyoctanoate (PHO): a short-term in vitro study of a degradable bacterial polyester.

The present study examined the degradation behaviour of poly(beta-hydroxy octanoate) (PHO), a bacterial poly(beta-hydroxy alkanoate), following incubation under hydrolytic or enzymatic conditions in vitro. Solution-cast PHO films were incubated in a citrate buffer solution with and without acid phosphatase and in an acetate buffer with and without beta-glucuronidase for periods ranging from 7 to 60 days. The physical characterization of the PHO films was analyzed by SEM and tensile strength studies. In addition, various analytical methods were used to detect modifications in the chemical and morphological structure of the PHO, namely, ESCA, FTIR, DSC, X-ray diffraction, and SEC. The results indicate that the enzymatic conditions selected in the present study induced no significant surface morphological or chemical modifications, and no significant weight loss was observed after 60 days of incubation. However, as revealed by weight average molecular weight Mw and number average molecular weight Mn decreases, changes in the bulk structure of the PHO were observed with acid phosphatase at 28 and 60 days, in contrast to smaller Mw and Mn decreases recorded in both the buffers and the beta-glucuronidase. The tensile properties had decreased following incubation, yet showed no difference under all of the selected conditions. With no weight loss or surface changes, the PHO films incubated in acid phosphatase showed only a chemical hydrolytic process characterized by Mw and Mn decreases with time of incubation. The present study demonstrated that the degradation of PHO films is one of slow, chemical hydrolysis only, perhaps requiring several months of incubation. The hydrophobic nature of the long alkyl pendent chain in PHO may be responsible for this slow process. The inability of enzymes to degrade PHO may be attributed to the latter's poor adsorption capacity, due to its hydrophobic nature, and to a lack of specificity in the catalytic activity of these enzymes.

Acid Phosphatase↗

Building a hospital information system: design considerations based on results from a Europe-wide vendor selection process.

A number of research and development projects in the U.S. and in Europe have shown that novel technologies can open significant perspectives for hospital information systems (HIS). The selection of software products for a HIS, however, is still nontrivial. Generalist vendors promise a broad scope of functionality and integration, while specialist vendors promise elaborated and highly adapted functionality. In 1997, the university hospital Marburg, a 1,250 bed teaching hospital, decided to introduce a new large-scale HIS. The objectives of the project included support of clinical workflows, cost effectiveness and a maximum standard of medical care. In 1997/98 a formal Europe-wide vendor contest was performed. 15 vendors, including several from the U.S., participated. Systems were checked against the hospital's objectives, functionality, and technological criteria. One of the results of both technology and market assessment was the identification of fundamental technological and design aspects strongly influencing functionality and flexibility.

Commerce↗

Hospital information systems: chances and obstacles on the way to integration.

Today, most large hospital information systems (HIS) comprise many heterogeneous application systems, loosely coupled via interfaces. Integration could offer many advantages, like the support of interdepartmental workflows or a consistent patient record. This cannot be achieved, however, by simply interfacing originally unrelated component systems. In this paper, we present relevant concepts of integration, the autonomy/consistency tradeoff, and technical alternatives in some detail. Based on our recent experiences in analyzing an existing HIS and selecting adequate vendors for the needs of our 1250-bed hospital, we then discuss strategies and tradeoffs on the way to a HIS that utilizes state-of-the-art technology to fill the users' needs.

Hospital Information Systems↗