Biomedical subjects

Michael Nerlich

Publications and source records attributed to Michael Nerlich.

16 recordsLinked to original sources

PubMed2006

Influence of surface pretreatment of titanium- and cobalt-based biomaterials on covalent immobilization of fibrillar collagen.

Collagen type-I is a major component of the extracellular matrix of most tissues and it is increasingly utilized for surface engineering of biomaterials to accelerate receptor-mediated cell adhesion. In the present study, coatings with layers of fibrillar type-I collagen were prepared on titanium, titanium alloy, and cobalt alloy to improve initial osteoblast adhesion and implant-tissue integration. To suppress the quick in vivo degradation rate of collagen the deposited layers were covalently immobilized at the metal surfaces as well as chemically cross-linked. The application of different oxidation techniques to the metallic substrates resulted in surfaces with varying hydroxyl group contents, which directly influenced the amount of immobilized silane coupling agents. It was found that a high density of surface-bound coupling agents increased the stability of the covalently linked collagen layers. After coating of metallic biomaterials with a cross-linked collagen layer, an improved cellular response of human osteoblast-like cells (MG-63) in vitro could be recognized.

Biocompatible Materials↗

PubMed2005

Surface engineering of stainless steel materials by covalent collagen immobilization to improve implant biocompatibility.

It was shown recently that the deposition of thin films of tantalum and tantalum oxide enhanced the long-term biocompatibility of stainless steel biomaterials due to an increase in their corrosion resistance. In this study, we used this tantalum oxide coating as a basis for covalent immobilization of a collagen layer, which should result in a further improvement of implant tissue integration. Because of the high degradation rate of natural collagen in vivo, covalent immobilization as well as carbodiimide induced cross-linking of the protein was performed. It was found that the combination of the silane-coupling agent aminopropyl triethoxysilane and the linker molecule N,N'-disulphosuccinimidyl suberate was a very effective system for collagen immobilizing. Mechanical and enzymatic stability testing revealed a higher stability of covalent bound collagen layers compared to physically adsorbed collagen layers. The biological response induced by the surface modifications was evaluated by in vitro cell culture with human mesenchymal stem cells as well as by in vivo subcutaneous implantation into nude mice. The presence of collagen clearly improved the cytocompatibility of the stainless steel implants which, nevertheless, significantly depended on the cross-linking degree of the collagen layer.

Adsorption↗

PubMed2004

Thoracic spondylitis from a mycotic (Streptococcus pneumoniae) aortic aneurysm: a case report.

STUDY DESIGN: We report on a 54-year-old man with chronic lower back pain after recent streptococcus pneumoniae pulmonary infection, resulting in a mycotic aortic aneurysm and spondylodiscitis of the eighth vertebrae 6 months later. Successful surgical treatment and recurrence-free survival after 4 years are described. SUMMARY OF BACKGROUND DATA: Osteomyelitis by Streptococcus pneumoniae of the spine combined with contained rupture of a mycotic aortic aneurysm into lung and spine has not been reported to date. Mycotic aneurysms with pulmonary fistulas are reported to carry a mortality rate of up to 100%. Few cases have been reported with different operative and conservative strategies. METHODS: The mycotic aortic aneurysm was excised using extracorporeal circulation and replaced by a Dacron graft. The spondylitic section of the eighth thoracic vertebrae was radically resected, and a tricortical bone block from the iliac crest was inserted into the defect. To keep compartments separated, collagen sponges with antibiotic supplementation were used. A triple antibiotic therapy (Metronidazol 3 x 0.5 g/day, Cefotaxim 3 x 2 g/day, and Flucloxacillin 3 x 2 g/day) was prescribed for 6 weeks and changed to Clindamycin for 1 year thereafter. RESULTS: The patient made a good recovery and is free of recurrence 4 years after surgery. CONCLUSIONS: Lower back pain might be a projected pain. Particularly in older patients or in the presence of comorbidities resulting in an immunocompromised status, an aggressive workup may be indicated. Radical resection of inflammatory tissues, sparse use of implant material, and prolonged administration of antibiotics proved a successful strategy in this patient.

Aneurysm, Infected↗

PubMed2004

Influence of different collagen species on physico-chemical properties of crosslinked collagen matrices.

Collagen-based scaffolds are appealing products for the repair of cartilage defects using tissue engineering strategies. The present study investigated the species-related differences of collagen scaffolds with and without 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC)/N-hydroxysuccinimide (NHS)-crosslinking. Resistance against collagenase digestion, swelling ratio, amino acid sequence, shrinkage temperature, ultrastructural matrix morphology, crosslinking density and stress-strain characteristics were determined to evaluate the physico-chemical properties of equine- and bovine-collagen-based scaffolds. Three-factor ANOVA analysis revealed a highly significant effect of collagen type (p=0.0001), crosslinking (p=0.0001) and time (p=0.0001) on degradation of the collagen samples by collagenase treatment. Crosslinked equine collagen samples showed a significantly reduced swelling ratio compared to bovine collagen samples (p< 0.0001). The amino acid composition of equine collagen revealed a higher amount of hydroxylysine and lysine. Shrinkage temperatures of non-crosslinked samples showed a significant difference between equine (60 degrees C) and bovine collagen (57 degrees C). Three-factor ANOVA analysis revealed a highly significant effect of collagen type (p=0.0001), crosslinking (p=0.0001) and matrix condition (p=0.0001) on rupture strength measured by stress-strain analysis. The ultrastructure, the crosslinking density and the strain at rupture between collagen matrices of both species showed no significant differences. For tissue engineering purposes, the higher enzymatic stability, the higher form stability, as well as the lower risk of transmissible disease make the case for considering equine-based collagen. This study also indicates that results obtained for scaffolds based on a certain collagen species may not be transferable to scaffolds based on another, because of the differing physico-chemical properties.

Animals↗

PubMed2004

Reduction of femoral shaft fractures in vitro by a new developed reduction robot system 'RepoRobo'.

Closed reduction of the long bones is associated with the use of considerable force. This force must be maintained for the reduction maneuver and fixation process. At present, apart from the extension table or the large AO distractor, only rather inadequate reduction aids are available. A solution to this problem is being sought in the form of a robotic system with which precision can be improved and the holding effort reduced. In the research project presented here, a synthetic femur with integrated tensioned mainspring and a 32-A3 type fracture served as a bone reduction model. The fracture was stabilized with a standard AO fixator. A Stäubli robot (model RX130) was converted by appropriate modification so that it could be used for the reduction of femoral shaft fractures in vitro. The robot was equipped with a pneumatic 2-fingered gripper, on which the fingers have been modified so that they can grip the AO fixator clamp. A Force-Feedback-Sensor was inserted between the gripper and the robot to obtain online recordings of the forces and moments in all three axes. With this setup it is possible to achieve precise reduction of the fracture in all planes under visual control.

External Fixators↗

PubMed2004

Cyclic, mechanical compression enhances chondrogenesis of mesenchymal progenitor cells in tissue engineering scaffolds.

The effects of cyclic, mechanical compression on human bone marrow-derived mesenchymal progenitor cells undergoing chondrogenic differentiation were examined in this study. Mesenchymal progenitor cells were injected into cylindrical biodegradable scaffolds (hyaluronan-gelatin composites), cultured in a defined, serum-free chondrogenic medium and subjected to cyclic, mechanical compression. Scaffolds were loaded for 4 hours daily in the first 7 days of culture. At 1, 7, 14 and 21 days of culture, scaffolds were harvested for reverse transcriptase Polymerase Chain Reaction (RT-PCR), histology, quantitative DNA, proteoglycan and collagen analysis. Scaffolds loaded for 7 days showed a significant upregulation especially of chondrogenic markers (type II collagen, aggrecan; p<0.0001). No significant difference could be found for DNA content between loaded samples and unloaded controls. At day 1 in culture no significant differences in proteoglycan- and collagen contents could be detected between unloaded and loaded samples. After 21 days the proteoglycan (p<0.001) and collagen contents (p<0.0001) were significantly higher in the loaded samples compared to unloaded controls. By histological analysis (toluidine blue) a higher amount of proteoglycan-rich, extracellular matrix production throughout the matrix could be detected for loaded samples compared to unloaded controls. This study indicates that cyclic, mechanical compression enhances the expression of chondrogenic markers in mesenchymal progenitor cells differentiated in vitro resulting in an increased cartilaginous matrix formation, and suggests that mechanical forces may play an important role in cartilage repair.

Biomarkers↗

PubMed2003

Demonstrating the practical value of new health technologies.

The applications of telemedicine are extremely diverse. They can be categorised as follows: teleconsulting, telemonitoring, centralised networked training as well as continuing and further education, and information systems. At the heart of telemedicine is, of course, the improvement of patient care, including care in decentralized parts of the health system. Expertise and therefore quality should be brought into the medical care system across the board by medical centers using technical aids. Particularly in rural areas, this increases a patient's chances of being able to be treated at home, even in the presence of complications or relatively rare medical conditions. Modern information and communication technologies also allow medical establishments or groups of establishments to manage their resources more efficiently. In this paper are presented many ongoing telemedicine projects at the University of Regensburg that demonstrate that beneficial aspects of telemedicine result not only in verifiable improvements in quality of care but also in substantial savings.

Cost Control↗

PubMed2003

A telemedicine guideline for the practice of teleconsultation.

UNLABELLED: To establish a guideline for the use of teleconsultation, which is one of the most important applications in telemedicine beeing perfomed very frequently in daily medical practice in almost any field of medicine. EVIDENCE: The recommendations are based on expert knowledge, because of the lack of evidence based data in the telemedical scientific literature. In addition, scientific articles of the highest level of evidence available published between 1970 and 1999 were reviewed. DEVELOPEMENT AND CONSENUS PROCESS: A guideline draft was prepared using the attributes of clinical practice guidelines developed by the Institute of Medicine (IOM) of the National Academy of Sciences. This draft was reviewed by telemedicine experts and the content of the guideline was approved by 100% group consensus in 5 meetings held between 1997 and 2000 by a panel of members of the Subproject 4 Group of the Global Health Care Application Project of the G8 countries. CONCLUSIONS: The guideline gives recommendations on all aspects of teleconsultation in any field of medicine and will be updated regularly implementing new evidence.

Computer Security↗

PubMed2003

Medical telematics in disaster response.

INTRODUCTION: Every year many disasters cause thousands of injuries, deaths, refugees. Depending on the kind of disaster (train/plane accident, flood, earthquake) not only an acute emergency medicine treatment but also general and family medicine and hospital treatment have to be safeguarded over a longer time-period in the disaster area. PROBLEM: Regarding to a lot of organizations, institutions and disaster teams taking part in the disaster assistance is there any lack of work or data flow in the medical treatment? METHODS: From the ODRA flood 1997, the high speed train crash in ESCHEDE 1998, the DANUBE flood 1999 and the ELBE flood in 2002 experience reports were collected. They were analysed with emphasis on data and work flow in the medical treatment and its command system: Standardised command structure? Communication problems? Used communication lines? Language problems? Medical Intelligence distribution? Use of Patient Tracking System? Triage problems? RESULTS: The use of spoken radio communication causes transmission mistakes or misunderstandings and radio-overload and need connection-set-up-time for each call. Manual distribution of same data for many receivers using different communication lines causes a time shift in the up-to-date-information. Language problems during the ODRA flood between German and Polish people led to longer reaction times. Up-to-date triage results as well as up-to-date transportation and hospital information are necessary for medical evacuation. Compared with other reports about these disasters the quality of disaster management depends on the quality of communication and information. CONCLUSION: The use of health telematics in disaster response helps to cope with the scenario. Modern technologies provide support for building up medical aid although the normal infrastructure is destroyed. To cope with disaster scenarios there are some telematic tools which can be used:--Computer-based Command and Control System--Telemedical support --Data-ressources-network /Medical Intelligence. A further study is recommended to evaluate the real impact of using these telematic tools in a disaster.

Disaster Planning↗

PubMed2003

Development of a robotic navigation and fracture fixation system.

The use of robotics in surgery is nothing new. However, there are areas of surgery, such as in fracture fixation, where robots have yet to be implemented. This paper considers the choice of robot, gripper and ancillary equipment together with navigation systems necessary for their application. Hitherto robots have seen operation in surgery only in cases where relatively low manipulation forces are required. Nothing yet exists with the capability of handling forces in excess of 200 Newton as would be required in the above scenario. Another encumbrance to robots which are already in medical use is the difficulty in programming. Unfortunately most of these robots are programmed by specialists for a particular application. However, there exists a number of robot programming languages, like Unimation VA-LII (recently superceded by Stäubli V+), which do not require specialist knowledge. The application of industrial robots to the "heavier" side of modern surgery is without doubt technically realisable. The remainder of this research project aims to determine exactly which robots and what ancilliary equipment are needed and then to implement them, first on plastic models and later on cadavers. A second phase is expected to deal with type approval and a final third phase with operations on live patients.

Fracture Fixation↗

PubMed2003

A communication-theory based view on telemedical communication.

Communication theory based analysis sheds new light on the use of health telematics. This analysis of structures in electronic medical communication shows communicative structures with special features. Current and evolving telemedical applications are analyzed. The methodology of communicational theory (focusing on linguistic pragmatics) is used to compare it with its conventional counterpart. The semiotic model, the roles of partners, the respective message and their relation are discussed. Channels, sender, addressee, and other structural roles are analyzed for different types of electronic medical communication. The communicative processes are shown as mutual, rational action towards a common goal. The types of communication/texts are analyzed in general. Furthermore the basic communicative structures of medical education via internet are presented with their special features. The analysis shows that electronic medical communication has special features compared to everyday communication: A third participant role often is involved: the patient. Messages often are addressed to an unspecified partner or to an unspecified partner within a group. Addressing in this case is (at least partially) role-based. Communication and message often directly (rather than indirectly) influence actions of the participants. Communication often is heavily regulated including legal implications like liability, and more. The conclusion from the analysis is that the development of telemedical applications so far did not sufficiently take communicative structures into consideration. Based on these results recommendations for future developments of telemedical applications/services are given.

Communication↗

PubMed2003

NOAH--a mobile emergency care system.

The German emergency care system is a very sophisticated one. However, negative headlines like "Emergency Patient Tourism" appearing from time to time, have provoked a thorough deficit analysis which revealed two weak points: communication and documentation. The communication system presently used is a rather outdated one employing analogue voice radio between the ambulance cars/helicopters and the dispatch center and telephone communication between the dispatch center and the emergency rooms. To document the emergency case the on-scene physician is required to fill out a form. A survey showed that many of these forms are filled out incompletely and/or inconsistently or are even missing completely. NOAH, which means "Emergency Organization and Administration Aid" ("Notfall Organisations- und Arbeits-Hilfe" in German) intends to address both of these communication and documentation deficits. The on-scene physician is equipped with a mobile ruggedised PC with an internal digital radio-modern. It provides a direct, digital communication channel from the on-scene physician to the emergency physician starting from the first minutes of the treatment of the emergency patient. It also provides an easy-to-fill-out variant of the paper form mentioned above with an on-line help function and visual aids. A typical course of events with the communication part of NOAH is as follows. The on-scene physician is alarmed via NOAH and can obtain details of the emergency during the approach. He can enter the status codes ("on the move","arrived at the emergency scene","arrived at the patient", etc.) with NOAH. During the first minutes of the treatment of the patient the physician enters a so called "First Message", which requires only 10 to 15 seconds. This message contains basic information like sex, age and the injuries of the patient. It helps the dispatch center (if the on-scene physician desires so) to make an informed recommendation where to bring the patient. This message is also forwarded to the emergency room of the destination hospital, where it can help to start appropriate preparations for the patient. When the on-scene physician has enough time, he can already bring up the documentation masks and give further information to the emergency room.

Documentation↗

PubMed2002

Ultrasound-guided decompression of the spinal canal in traumatic stenosis.

The purpose of this study was to examine the efficacy of ultrasound (US)-guided decompression of the myelon in the surgical treatment of spinal fractures. Intraoperative ultrasonography was performed in 22 patients with traumatic stenosis of the spinal canal during spinal cord surgery with removal of retropulsed bony fragments. US imaging requires a posterior approach and an enlarged foramen interarcuale. The posterior vertebral facet and the myelon can accurately be distinguished from small bony fragments by ultrasonography. Pre- and postoperative computed tomography was compared with intraoperative US imaging. Complete decompression of the spinal canal was controlled by US imaging of the restored ventral epidural space, as seen after repositioning of displaced fragments. Thus, the required extent of the surgical procedure was determined by intraoperative ultrasonography. We conclude that intraoperative US imaging is an important tool to monitor the restoration of the spinal canal and decompression of the spinal cord in case of fracture. The repositioning of stenosing bony fragments using surgical instruments can be monitored. US imaging as a real-time method intraoperatively provides the surgeon with additional information and significantly influences treatment options.

Decompression, Surgical↗

PubMed2002

International concerted action on collaboration in telemedicine: recommendations of the G-8 Global Healthcare Applications Subproject-4.

The main objectives of the G-8 Global Healthcare Applications Subproject-4 (G-8 GHAP-SP-4) were to establish an international concerted action on collaboration in telemedicine, telehealth, and health telematics (hereafter referred in this paper as telemedicine). In order to promote and facilitate the implementation of telemedicine or health telematics networks around the world, it was considered necessary to address certain key issues. Five thematic solution-seeking forums were held between May 1998 and December 1999. Each addressed a key issue, including interoperability of telemedicine and telehealth systems, impact of telemedicine on health care management, evaluation and cost effectiveness of telemedicine, clinical and technical quality and standards, and medico-legal aspects of national and international applications. The main objectives of these forums were to establish best practices and a thorough review of the issues and discussions among experts to determine the best solutions for the facilitation of global international telemedicine networks. More than 650 invited participants from 16 countries attended the five forums, which were of 2-3 days in duration. These forums provided a foundation for the exchange of ideas resulting in the initiation of collaborative activities. Based on these deliberations, a series of 21 recommendations were prepared by the national representatives of the G-8 GHAP SP-4. These recommendations propose to political leaders and health care managers of the G-8 and other countries roadmaps to follow in order to accelerate the achievement of a Global Society of Healthcare via Telemedicine, Telehealth, and Health Telematics. The 21 recommendations are presented in this report.

Humans↗

PubMed2002

Teleconsultation practice guidelines: report from G8 Global Health Applications Subproject 4.

This report presents a series of recommendations derived from deliberations of the G8 countries Subproject 4 Group (SP4 Group) of the Global Health Care Applications Project entitled, A Teleconsultation Practice Guideline. The recommendations provide an initial step toward developing a general guideline platform for the practice of telemedicine/teleconsultation.

Computer Security↗

PubMedDate not supplied

PEGylation does not impair insulin efficacy in three-dimensional cartilage culture: an investigation toward biomimetic polymers.

A major goal in tissue engineering is the controlled application of growth factors. As a novel application system, we are currently developing biomimetic polymers that are processed into three-dimensional scaffolds. Bioactive proteins will be covalently bound to the polymers via a poly(ethylene glycol) (PEG) linker. Of paramount importance is the maintenance of the biological activity of the protein after PEGylation and covalent binding to the polymer. Therefore, within this study, insulin used as a model protein was PEGylated with an active succinimidyl ester of poly(ethylene glycol) (SS-NH-PEG) (MW ~2000) and biological effects of the protein-PEG conjugate were monitored in comparison with unmodified insulin. No significant differences in chondrocyte proliferation were observed in a conventional proliferation assay after treatment with insulin or PEGylated insulin. In a complex three-dimensional cartilage-engineering model the effects of insulin and PEGylated insulin were investigated over a wide concentration range (0.025-25 microg/mL). Insulin and PEGylated insulin at equivalent concentrations resulted in cartilaginous tissue constructs exhibiting identical wet weight, cell number, biochemical composition of the extracellular matrix, and histological appearance, both compounds significantly improving tissue quality as compared with control constructs. In conclusion, the presented study demonstrates that PEGylation of insulin using SS-NH-PEG did not change the activity of the protein in a complex biological environment and is regarded as a step toward the development of biomimetic polymers.

Animals↗