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Biomedical subjects

C Jürgens

Publications and source records attributed to C Jürgens.

At least 19 recordsLinked to original sources
PubMed2007

[A sizeable chance--surgical management of profound obesity concurrent with post-traumatic osteoarthrosis].

In times of plentiful nutrition an environmental advantage turns into a problem - obesity. Apart from an increase in morbidity and overall mortality the development of osteoarthrosis is well documented. Pre-arthrotic conditions may arise from trauma and can lead, depending on the pattern of injury, to full-blown arthrosis. The presence of obesity can play the role of a relevant progressive factor in this setting. Here we report about the case of an obese man (BMI 53.5 kg/m(2)), who suffered a fracture of the femoral head with acetabular participation (Pipkin IV) as well as a fracture of the tibial plateau. Operative management and rehabilitation were followed by gastric bypass surgery for weight reduction. The case is discussed with regard to the present literature.

Adult↗
PubMed2006

[Progress in geriatric care through telemedicine].

A constantly aging population leads to an increasing number of elderly patients. As a result, the treatment of chronic illnesses becomes a significant part of daily routine. Today's concepts in social services and healthcare require time consuming and barely cost-effective efforts for the special needs of geriatric care. The use of telemedicine offers a possible solution, because telemedical methods may help to realize improved monitoring systems for optimized and effective patient management. This report provides an overview of the scenarios and advantages of telemedicine in general. In addition, we provide information on practical experiences in a project on telemedical glaucoma management in Mecklenburg-Vorpommern.

Aged↗
PubMed2006

[Digital patient record for remote monitoring of intraocular pressure, blood pressure and serum glucose].

BACKGROUND: At the University Eye Hospital of Greifswald, we have developed a digital patient record that allows close monitoring of glaucoma, diabetes and hypertension. The record stores contemporary, long-term profiles containing intraday variation and interaction of intraocular pressure, blood pressure and serum glucose levels even at night. METHODS: All patients are equipped with a home monitoring system. They subsequently transmit self-measurements via the "telemedical interface" to the server. Physicians use a web front-end to access electronic patient records; this provides a PDF export filter for printing. We intend to include a total number of 120 patients from Mecklenburg-Vorpommern who suffer from glaucoma possibly combined with hypertension/diabetes. This long-term investigation was designed as a randomised cross-over study in two groups. RESULTS: Especially for this project an electronic patient record was developed and implemented. The components of the home monitoring system were modified and connected to a custom-built "telemedical interface". To date the study includes 120 patients, 60 of whom constantly measure and transmit their values to the electronic patient record, while the others are treated without home monitoring. All self-measurements are presented in a tabular form. In addition, dynamically generated graphics provide a diagrammatic view of all values. On demand, a detailed protocol for every single measurement report allows a comprehensive evaluation of the quality of the self-measurements. Ocular perfusion pressure is calculated automatically from intraocular pressure and blood pressure. The presented system documents continuously all information that is relevant for treatment and provides fast access for all attending physicians. CONCLUSIONS: Central data collection and unlocalised access improve information exchange between involved physicians. Flexible measurement periods allow the detection of pressure spikes even at night. In addition, this may help to classify glaucoma (normal-pressure glaucoma) and its causal connection to blood pressure. The patients benefit from individualised therapy adaptation and early therapeutic intervention in case of critical parameters.

Blood Glucose Self-Monitoring↗
PubMed2004

Three-dimensional load measurements in an external fixator.

On the basis of a six-degree-of-freedom adjustable fracture reduction hexapod external fixator, a system which can be used for measuring axial and shear forces as well as torsion and bending moments in the fixator in vivo was developed. In a pilot study on 9 patients (7 fresh fractures and 2 osteotomies of the tibia), the load in the fixator during the healing process was measured after 2, 4, 8 and 12 weeks and at fixator removal. The measured values enabled both the type of fracture to be determined as well as the monitoring of the healing process. In well-reduced type A3 fractures small axial (direction of the bone axis) forces were found in the fixator. A2, B2 and C3 fractures showed distinct axial forces, which decreased during the healing process, according to an increasing load transfer over the bone. Bending moments in the fixator showed good correspondence with the clinical healing process, except in the case of a C3 fracture. A combination of bending moment and axial force proved to be particularly suitable to assess fracture healing. In transverse fractures, the well-known resorption phenomenon of bone in the fracture gap at approximately 4 weeks was detected by the system. Compared with other external fixator load measurements in vivo, the hexapod offers the advantage of being able to measure all forces and moments in the fixator separately and with a relatively simple mechanical arrangement. In our opinion, it will be possible to control fracture healing using this system, thereby minimizing radiation exposure from radiographs. Furthermore, the measurement system is a step towards the development of external fixator systems that enable automatic adjustments of the callus mechanical situation ("automatic dynamization") and inform the patients about the optimal weight bearing of their extremity ("intelligent fixator").

Equipment Design↗
PubMed2004

Quadriceps tendon ruptures-is there a complete functional restitution?

From January 1986 to November 1999, 35 patients with 36 traumatic ruptures of the quadriceps tendon, all without medical risk factors, were treated (33 men, 2 women; mean age 55 years). Thirty patients were operated within 14 days after trauma. With an average follow up of 55.4 months (7-168) 29 of 30 still living patients (96.7%) were studied retrospectively. Questionnaire (Lysholm score), physical examination, X-ray of both knees and isokinetic testing were performed. The outcome was significantly (P < 0.001) dependent on the time of operative procedure. Twenty-four patients treated within the first 14 days had 20 excellent and 4 good results, the other 5 one good, 1 satisfying and 3 poor results. Twenty-one of 23 patients (91%) could return to work. The type of repair (direct or transosseous suture with or without augmentation), the kind of postoperative physiotherapy, the age and the body mass index had no influence on the final outcome.

Adult↗
PubMed2002

[Simultaneous traumatic rupture of the patellar and contralateral quadriceps tendon].

We report a very rare case of a simultaneous rupture of the right patellar and left quadriceps tendon in an otherwise healthy 37-year-old patient, who jumped off a kickboard. Suture of both tendons was performed on the day of trauma. We describe our postoperative treatment and report the follow-up examination one year after the trauma. Beside functional questionnaire, Lysholm score and physical examination and x-ray, quadriceps isokinetic testing was performed.

Adult↗
PubMed2002

[Theory and software of the hexapod external fixator].

Using hexapod kinematics (Stewart platform), an external fixator was developed that can be adjusted in all six spatial degrees of freedom by means of six linear adjusting elements. With such a system, any desired three-dimensional bone movements, for example, fracture reduction or deformity correction, can be effected exactly, without having temporarily to compromise any stability already achieved or to rearrange the construction during treatment. Since the introduction of the hexapod principle by Stewart in 1965, computerized control has been deemed necessary for its application. This paper describes the mathematical basis and the software developed for clinical use. Mathematical procedures are needed for the calculation of the inverse and forward kinematics of the hexapod, and for the description of three-dimensional movements.

Biomechanical Phenomena↗
PubMed2001

Stability, catalytic versatility and evolution of the (beta alpha)(8)-barrel fold.

The (beta alpha)(8)-barrel is a versatile single-domain protein fold that is adopted by a large number of enzymes. The (beta alpha)(8)-barrel fold has been used as a model to elucidate the structural basis of protein thermostability and in studies to interconvert catalytic activities or substrate specificities by rational design or directed evolution. Recently, the (beta alpha)(4)-half-barrel was identified as a possible structural subdomain.

Catalysis↗
PubMed2000

Directed evolution of a (beta alpha)8-barrel enzyme to catalyze related reactions in two different metabolic pathways.

Enzymes participating in different metabolic pathways often have similar catalytic mechanisms and structures, suggesting their evolution from a common ancestral precursor enzyme. We sought to create a precursor-like enzyme for N'-[(5'-phosphoribosyl)formimino]-5-aminoimidazole-4-carboxamide ribonucleotide (ProFAR) isomerase (HisA; EC ) and phosphoribosylanthranilate (PRA) isomerase (TrpF; EC ), which catalyze similar reactions in the biosynthesis of the amino acids histidine and tryptophan and have a similar (betaalpha)(8)-barrel structure. Using random mutagenesis and selection, we generated several HisA variants that catalyze the TrpF reaction both in vivo and in vitro, and one of these variants retained significant HisA activity. A more detailed analysis revealed that a single amino acid exchange could establish TrpF activity on the HisA scaffold. These findings suggest that HisA and TrpF may have evolved from an ancestral enzyme of broader substrate specificity and underscore that (betaalpha)(8)-barrel enzymes are very suitable for the design of new catalytic activities.

Aldose-Ketose Isomerases↗
PubMed1998

Predictive neural networks for learning the time course of blood glucose levels from the complex interaction of counterregulatory hormones.

Diabetes mellitus is a widespread disease associated with an impaired hormonal regulation of normal blood glucose levels. Patients with insulin-dependent diabetes mellitus (IDDM) who practice conventional insulin therapy are at risk of developing hypoglycemia (low levels of blood glucose), which can lead to severe dysfunction of the central nervous system. In large retrospective studies, up to approximately 4% of deaths of patients with IDDM have been attributed to hypoglycemia (Cryer, Fisher, & Shamoon, 1994; Tunbridge, 1981; Deckert, Poulson, & Larsen, 1978). Thus, a better understanding of the complex hormonal interaction preventing hypoglycemia is crucial for treatment. Experimental data from a study on insulin-induced hypoglycemia in healthy subjects are used to demonstrate that feedforward neural networks are capable of predicting the time course of blood glucose levels from the complex interaction of glucose counterregulatory (glucose-raising) hormones and insulin. By simulating the deficiency of single hormonal factors in this regulatory network, we found that the predictive impact of glucagon, epinephrine, and growth hormone secretion, but not of cortisol and norepinephrine, were dominant in restoring normal levels of blood glucose following hypoglycemia.

Blood Glucose↗
PubMed1998

[Extended resection of locally advanced primary and recurrent rectal carcinomas by interdisciplinary cooperation of various surgical specialties].

Multivisceral resections have been performed on 35 patients with primary and 45 with recurrent rectal cancer. Lethality was 3.7%, morbidity was 9%. Macroscopic adhesions were confirmed histologically as tumorous in 66% of the additionally resected organs. Tumor invasion, tumor recurrence and surgical radicality were found as statistically significant prognostic factors. In radically resected primary tumors 5-yr-survival was 49%. Multivisceral resection in rectal cancer is possible with low morbidity and lethality and potentially curative in primary tumors. In recurrent tumors multivisceral resections are frequently palliative.

Abdominal Neoplasms↗
PubMed1995

[Treatment of severe concomitant injuries in severely burned patients].

Over a period of almost 6 years, 18 out of 320 burn patients treated in the burn centre had sustained additional severe trauma; for the most part the trauma was due to a motor vehicle accident or a fall. The risk of overlooking such additional injuries can be minimized by systematic examination and a team approach, the same as in normal multiple-trauma patients. Apart from the burn, life-threatening complications such as intra-abdominal bleeding or haemopneumothoracic injuries are to be treated immediately. In order to facilitate appropriate burn wound care and optimize mobilization, early internal or external fixation of unstable orthopaedic injuries should be performed as soon as possible. In our experience, operations carried out within 48 h after the injury have neither led to complications in wound healing nor to osteomyelitis.

Adolescent↗
PubMed1995

[Development and characterization of an absorbable temporary wound dressing].

Most of the temporary dressings used in the treatment of burns do not meet the objectives of a skin substitute concerning application, safety and comfort. Removal is often painful and traumatic and increases the risk of infection. Biodegradable polymers of lactic and caproic acid were developed as part of a research programme (BMFT/FRG 01 KG 8809/7), and chemical and physical properties were investigated. Films made of the copolymer material were characterized by structure, transparency, permeability, tensile strength, flexibility and degradation. The transparent films appeared increasingly opaque during hydrolysis. The water vapour permeance could be varied between 40 and 250 (40-136) ml/m2 per h (according to the method of measurement). The mechanical properties are characterized by a maximum elongation of > 2000% at 37 degrees C and a very low elastically modulus. When the results were compared with those of three established film dressings, no restriction was found in the aptitude of the material as a wound dressing.

Animals↗
PubMed1995

[In vitro and in vivo studies of a temporary absorbable dressing].

The major advantage of biodegradable synthetic wound dressings compared to other synthetic materials and biological tissue derivatives is avoidance of the necessity to change the dressing. The copolymer films used in this study were made of lactic and caproic acid. They pose no problems concerning immunology or transmission of diseases. Moreover, the substances released by degradation may possibly influence the process of wound healing. The material proved to be non-toxic and was used successfully as a carrier for cell culture with keratinocytes. The permeability for bacteria is determined by degradation. Evaluation of the bacteriological studies indicates secure protection against secondary contamination of the films for at least 15 days, however. Concerning application, dressing properties, wound healing and wound retraction, no disadvantages were found in comparison with the results of the competition's film Opsite. Based on these findings, the films are now used in a clinical study as a wound dressing for split-skin donor sites.

Animals↗
PubMed1994

[Standardized ultrasound examination for classification of instability of the acromioclavicular joint].

Anteroposterior X-ray views of both acromio-clavicular (AC-) joints with 10 kg weights in each hand are generally accepted for the diagnosis of Tossy I to III AC-joint separations. An analogue diagnosis can be made by standardized ultrasound examination. Ten individuals without AC-instability (Tossy I), eleven with Tossy II- and eight with Tossy III-instability were examined both radiographically and by B-mode ultrasound. AC-joint width was uniformly calculated by using an index (AC-index = AC-joint width of uninjured side/AC-joint width of injured side). The sonographically measured mean AC-index for Tossy I-stability was 1.0; sonographically 0.49 and radiographically measured 0.5 for Tossy II-injury; and sonographically 0.21 and radiographically measured 0.2 for Tossy III-instability. Statistical analysis resulted in significant differences for all mean AC-indices of the three groups (p < 0.0001). We conclude that ultrasound examination of AC-joint instability is as reliable as radiographic measurement. Standard X-rays of the shoulder remain mandatory to exclude fractures only. The decision for operative stabilisation of the AC-joint can be based on the side-effect free and cost-effective ultrasound examination of the grade of AC-joint instability (AC-index < 0.3 equivalent Tossy III).

Acromioclavicular Joint↗
PubMed1994

[Treatment concepts and results in non-infected post-traumatic pseudarthroses of the femur and tibia].

AIM OF INVESTIGATION: Different methods of internal and external fixation are used to treat aseptic posttraumatic nonunion of the femur and tibia. The advantages and disadvantages of the different methods will be demonstrated by analysing the clinical course and the outcome of our patients. Utilizing these data, a therapeutic concept tailored to the individual situation is recommended. METHODS: Depending on the form of reaction we distinguish between vital and non-vital nonunions. The classification is made according to the clinical course, x-ray-findings and in special cases the results of scintigraphy. Due to anatomic differences in vascularisation and soft tissue coverage nonunion of the femur and the tibia are discussed separately. Stabilisation is achieved by intramedullary nail, plate or external fixator. As new methods the internal plate fixator was used for the femur and the Ilizarov ring fixator for the tibia. If there has been a mistake in the choice of the method of the primary stabilisation a change of method is done. If the indication for the initial method of stabilisation was correct, the therapy of nonunions is limited to the correction of technical mistakes. Additionally, a biologic stimulation is required for the therapy of non-vital nonunion. RESULTS: The clinical data of 77 patients treated from 1985-1993 were analysed retrospectively. Vital nonunions of the femur (11) healed after 9.5 months on the average, those of the tibia (49) after 10 months. The duration of treatment of non-vital nonunions was much longer and required 20 and 16 months, respectively. The treatment of two non-vital nonunions of the tibia could not be completed. For the femur only intramedullary nail (4) and plate (8) were used, for the tibia mainly the fixator (43), of these in 18 cases the Ilizarov-apparatus. Differences in the duration of treatment due to the choice of implant could not be recognized. Complications were pin problems (14) and one lesion of the peroneal nerve in the fixator group and superficial wound infection (2), nerve irritation (1) and fracture (1) in the group treated with intramedullary nailing. CONCLUSIONS: Due to the good soft tissue coverage and vascularisation internal fixation is favored for the treatment of femoral nonunions. The fixator should only be used if distraction osteogenesis is necessary because of a bony defect. Due to the problematic soft tissue situation and poorer vascularisation on the external fixator is preferred in the treatment of tibial nonunions if a change of method is indicated. For this purpose, we currently use predominantly the Ilizarov-apparatus because of its biomechanical properties and the convincing results. Initial problems with its use could markedly be reduced with growing experience.

Adolescent↗
PubMed1994

[Change in the treatment method of infected pseudarthrosis with bone loss of the tibia].

AIM OF INVESTIGATION: The treatment of nonunions complicated by infection and bone loss is divided into two stages. Having calmed down the infection by stabilizing, removal of infected and necrotic tissue and local antibacterial measures, the bone loss has to be filled up. Bridging the gap by means of autogenous cancellous bone grafting is complicated by a high rate of refractures depending on the length of bone loss. Therefore after changing the method and using the Ilizarov procedure it is of interest, whether this method offers advantages. Our experience is to be reported and discussed. METHODS: According to the clinical course two groups of patients with nonunions of the tibia complicated by infection and bone loss were compared. 25 previously evaluated patients of the years 1980/81 whose tibial bone loss was bridged by cancellous bone grafting (1st group) were compared with 16 patients who were treated by the Ilizarov method from May 1990 to October 1993 (2nd group). The average age was nearly the same (32.6/32.9 years). In the first group the average of bone loss measured 4 cm, in the second 7.8 cm. The number of initial operations to eliminate infection and the duration of fixator application from the beginning of bridging bone loss were compared as well as early and late complications, especially the rate of refracture and reinfection. RESULTS: 1.2 operations were needed to eliminate infection in the first group, in the second only one was necessary. The handling of the Ilizarov device is more difficult and needs training. The higher rate of early complications at the beginning decreased with increasing experience. The average of fixation time could be reduced by about ten days per cm of bone loss using the Ilizarov technique. By segmental transport new cortical bone is generated which surpasses cancellous bone grafting in regard to stability. This seems to be an important reason that refracture did not occur in the second group. Furthermore, reinfection could be avoided up to now obviously due to sufficient segmental resection of infected and necrotic tissue. Limited stores of autogenous cancellous bone are not to be feared. The total number of operations can be reduced. At the docking side early single cancellous bone grafting is recommended.

Adolescent↗