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Biomedical subjects

U Weber

Publications and source records attributed to U Weber.

At least 19 recordsLinked to original sources
PubMed2006

[Myocardial infarction in a 21-year-old ASA I patient after arthroscopic surgery of the knee under general anaesthesia].

Myocardial ischemia is a major complication in the perioperative period, mostly in patients with high cardiac risks. After non-cardiac surgery myocardial infarction was observed in 5.6% of patients with coronary heart disease, the rate in patients with no cardiac diseases was 0.1-0.7%. We present the case of a 21-year-old ASA I male patient who underwent surgery to reconstruct the cruciate ligament of the knee. General anaesthesia was performed in combination with a femoral nerve block. After surgery the patient suffered from myocardial infarctions on the day of surgery and the 6th day after surgery. After resuscitation, thrombolysis and percutaneous transluminal coronary angioplasty (PTCA), an intraaortic balloon pump had to be temporarily implanted due to persistent cardiogenic shock.

Adult↗
PubMed2006

[Instability of the upper cervical spine due to rheumatism].

Rheumatic manifestation at the cervical spine occurs in more than 50% of all cases in the natural course of this disease. The first cervical manifestation takes place in the upper cervical spine. The initial involvement of the C1/C2 segment leads to atlantodental subluxation. Progressive destruction can result in vertical instability, which is characterized by cranial subluxation of the odontoid process with the danger of resulting stenosis and cervical myelopathy. The goal of diagnosis has to be the early recognition of these changes to establish an effective treatment protocol. Persistent pain, neurological deficits, and progressive radiological signs for instability are indications for operative stabilizing procedures. These procedures avoid progressive destruction and improve the prognosis regarding pain decrease, regression of neurological deficits, and life expectancy.

Aged↗
PubMed2006

[Injuries to the craniocervical junction].

Injuries to the upper cervical spine (C0-C2) play a major role in surgical treatment of traumatic sequelae in the entire cervical spine. Even though the number of such operations has increased in recent years, there are no clear treatment recommendations for most types of cervical spine injuries. In view of the wide range of injury types and the correspondingly large number of treatment options, this review focuses mainly on the following types of injuries: C0 fractures, occipital condyle fractures (OCF), atlanto-occipital dislocation (AOD), atlas fractures, atlantoaxial dislocation (AAD), and axis fractures. Important aspects of the mechanisms of injury, clinical signs and symptoms, diagnostic procedures, and treatment options are discussed. Special emphasis is placed on comparatively reviewing the different treatment options discussed in the literature. A summary in table form is presented at the end of each chapter for quick reference.

Adolescent↗
PubMed2006

[Rare pathological alterations of the upper cervical spine requiring surgical treatment].

Because of its unique anatomy, specific diseases and lesions arise in the upper cervical spine, which differ widely from the rest of the spine. During the last two decades standardised diagnostic and therapeutic algorithms have been defined for most of the craniocervical pathologies often occurring in combination with an underlying disease requiring surgical intervention as well. On the other hand there are some very rare phathological alterations: about 20% of the patients suffering from neurofibromatosis type I develop spinal deformities. These are mostly found in the thoracic and lumbar spine (dystrophic/non-dystrophic type). In rare cases the dystrophic neurofibromatosis type I involves the upper cervical spine leading to bizarre deformities endangering the spinal cord. An aggressive, timely and combined operative therapy is necessary. Patients with Down syndrome should be investigated regularly for affections of the upper cervical spine. Though only in about 1% of all patients with Down syndrome do instabilities require surgical intervention, the upper cervical spine should be screened on a regular basis, since neurological changes due to the pathognomy of the underlying disease often remain undetected for a long time. The operative therapy of the instable os odontoideum in Down syndrome follows the general principles of this pathoanatomical variation. Even though the Klippel-Feil syndrome is generally not linked with neuropathological findings, rare associated deformities of the upper cervical spine should be excluded by proper diagnostic procedures.

Adolescent↗
PubMed2006

Ultrasonically implanted PLA suture anchors are stable in osteopenic bone.

We compared the in vitro pullout strengths of a metallic screw-type suture anchor (5-mm Corkscrew) and a new ultrasonically implanted absorbable pin from cadaveric humeral heads with different bone densities. They were assessed quantitatively using microcomputed tomography. Pullout tests were done at four standardized sites and then correlated with the local bone density. The mean pullout strengths for the 5-mm Corkscrew and the 3.5-mm polylactic pin were similar in weak bone (76 +/- 24 N versus 104 +/- 46 N), intermediate quality bone (194 +/- 81 N versus 218 +/- 76 N), and strong bone (349 +/- 127 N versus 325 +/- 100 N). Pullout strength correlated with bone density for both implants (r = 0.76 and r = 0.86 for the Corkscrew and polylactic pin, respectively). The ultrasonically implanted absorbable 3.5-mm polylactic pin achieved equal pullout strength in weak bone as the larger 5-mm titanium Corkscrew. Bone density is highly variable in humeral heads and influenced the pullout strength of both implants.

Absorbable Implants↗
PubMed2006

Hygienic relevance and risk assessment of antimicrobial-impregnated textiles.

The antimicrobial impregnation of textiles is intended to provide protection of textiles against microbial corrosion, prevention of malodor or prophylaxis and therapy of infections, respectively. For every biocidal product a careful risk assessment for humans and the environment has to be performed. The advantage of antimicrobially active textiles has to be documented for every agent as well as for every application, and a balance has to be found between a textile's quality rating and the potential risks, e.g. sensitization, disturbance of the ecology of the skin, toxic side effects by means of systemic absorption, cytotoxicity, genotoxicity, carcinogenicity, teratogenicity and ecotoxicity. This article evaluates the applicability of silver compounds as well as the classic antimicrobials triclosan, quaternary ammonium compounds, copper and further new options like chitosan and zeolite. It has to be emphasized that there are no objections against the use of antimicrobially active textiles if their use is equal or superior to other preventive or therapeutic measures. This applies to the amelioration of the course of dermatological diseases with disturbed skin flora, in particular atopic dermatitis, the prevention and therapy of acute and chronic wound infections by wound dressings, the use of impregnated surgical suture material as well as special indications in the prevention of infection in medical facilities. The use of antimicrobial textiles for the prevention of dermatomycosis by antifungal impregnation is of questionable use; the antimicrobial impregnation of textiles for deodorization purposes has to be avoided. Presently, from a hygienic point of view, the following questions have to be clearly determined: declaration of any antimicrobial impregnation; development of international standards for in vitro testing and preclinical evaluation of efficacy and tolerance; evaluation of the advantage of the antimicrobial properties for the intended use including the risk-benefit assessment.

Anti-Infective Agents↗
PubMed2005

Conversion of a CHO cell culture process from perfusion to fed-batch technology without altering product quality.

During the development of a new drug product, it is a common strategy to develop a first-generation process with the aim to rapidly produce material for pre-clinical and early stage clinical trials. At a later stage of the development, a second-generation process is then introduced with the aim to supply late-stage clinical trials as well as market needs. This work was aimed at comparing the performance of two different CHO cell culture processes (perfusion and fed-batch) used for the production of a therapeutically active recombinant glycoprotein at industrial pilot-scale. The first-generation process was based on the Fibra-Cel packed-bed perfusion technology. It appeared during the development of the candidate drug that high therapeutic doses were required (>100mg per dose), and that future market demand would exceed 100 kg per year. This exceeded by far the production capacity of the first-generation process, and triggered a change of technology from a packed-bed perfusion process with limited scale-up capabilities to a fed-batch process with scale-up potential to typical bioreactor sizes of 15m(3) or more. The productivity per bioreactor unit volume (in product m(-3)year(-1)) of the fed-batch process was about 70% of the level reached with the first-generation perfusion process. However, since the packed-bed perfusion system was limited in scale (0.6m(3) maximum) compared to the volumes reached in suspension cultures (15m(3)), the fed-batch was selected as second-generation process. In fact, the overall process performance (in product year(-1)) was about 18-fold higher for the fed-batch compared to the perfusion mode. Data from perfusion and fed-batch harvests samples indicated that comparable product quality (relative abundance of monomers dimers and aggregates; N-glycan sialylation level; isoforms distribution) was obtained in both processes. To further confirm this observation, purification to homogeneity of the harvest material from both processes, followed by a complementary set of studies (e.g. full physico-chemical characterization, assessment of in vitro and in vivo bioactivity, comparative pharmacokinetics and pharmacodynamics studies in relevant species, etc.) would be required. Finally, this illustrates the need to fix the production process early during the development of a new drug product in order to minimize process conversion efforts and to shorten product development time lines.

Animals↗
PubMed2005

[Transpupillary thermotherapy for occult choroidal neovascularizations].

PURPOSE: This contribution describes the results of transpupillary thermotherapy (TTT) for age-related exudative macular degeneration (AMD) with regression. PATIENTS AND METHODS: In exudative AMD with occult choroidal neovascularization (CNV), transpupillary thermotherapy (TTT) was performed using a diode laser (Iridex) in unselected patients. Before therapy and 1, 3, and 6 months after the initial treatment the patients were examined clinically. Additionally threshold testing in the 10 degrees field (Humphrey) and fluorescein angiographies were documented at all check-ups. RESULTS: With respect to vision, differences in the slope of the regression lines between small, medium, and large CNV were significant (p<0.001). The slope of the regressions lines was significant except for small CNV. Regarding the 10 degrees field (Humphrey), there were no statistical differences in the slope of the regression lines (p=0.867). CONCLUSIONS: Transpupillary thermotherapy with small CNV did not show a statistically significant decrease of VA. Thus, in clinical terms early treatment of occult CNV with TTT seems to be able to prevent a further loss of visual acuity.

Aged↗
PubMed2005

[Effect of vertebral body stiffness before and after vertebroplasty on intradiscal pressure].

Fractures of osteoporotic vertebral bodies are increasingly stabilized with bone cement. The effects of vertebral-body stiffness before and after augmentation with bone cement and of wedge-shaped vertebral body fractures on intradiscal pressure are insufficiently known. In a finite element model of the lumbar spine the elastic modulus of cancellous bone as well as the amount and the elastic modulus of bone cement were varied and the dependency of intradiscal pressure on these parameters was calculated. In addition, a wedge-shaped vertebral-body fracture was simulated. The bulge of the vertebral-body endplate and thus the intradiscal pressure depends strongly on the grade of osteoporosis in the vertebral body. The influence of amount and elastic modulus of bone cement on intradiscal pressure is small. A wedge-shaped vertebral-body fracture causes an anterior shift of upper-body centre of gravity. If this shift is not compensated, it leads to an increased flexion moment that has to be balanced by muscle forces. In addition, this shift leads to a stronger increase of intradiscal pressure than the augmentation of the vertebral body with bone cement.

Bone Cements↗
PubMed2004

Treatment planning for scanned ion beams.

Since 1997 a radiotherapy unit using fast carbon ions is operational at GSI. An intensity-controlled magnetic raster scanner together with a synchrotron allowing fast energy variation enable a unique method of purely active dose shaping in three dimensions. This contribution describes the necessary steps to establish a treatment planning system for this novel modality. We discuss the requirements for the physical beam model and the radiobiological model. Based on these we chose to implement a home-grown pencil beam model to describe the ion-tissue interaction and the Local Effect Model to calculate the RBE voxel-by-voxel. Given the large number of degrees of freedom biological dose optimization must be achieved by means of inverse treatment planning. All ion-related aspects are collected in our TRiP98 software. Biological dosimetry measuring cell survival in two dimensions turns out to be a good way to verify the model predictions as well as the actual irradiation procedure. We show a patient example and outline the future steps towards a dedicated clinic facility for all light ions.

Carbon↗
PubMed2004

The Heidelberg Ion Therapy Center.

The ion beam therapy facility presently under construction at the Department of Clinical Radiology, University of Heidelberg, Germany, will be the first dedicated and hospital-based irradiation facility for protons and heavier ions in Europe. A capacity of more than 1000 patient treatments per year is planned. The facility comprises two horizontally-fixed beamlines for patient treatments plus a fixed-beam experimental area. In addition, the world-wide first scanning ion gantry is under construction. The facility fully relies on an active beam delivery method, the intensity-controlled rasterscan technique. The availability of different ion species ranging from protons to oxygen under identical conditions optimally supports clinical trials aiming to clarify the question of which particle species is best suited for the individual indications. A linac-synchrotron combination will deliver libraries of energy-, focus- and intensity-variable pencil-beams for each ion species to the dose-delivering scanning systems at each treatment station. The available energies correspond to water-equivalent ranges from 2 cm to 30 cm. The intensity-controlled rasterscan technique allows for the administration of inversely planned and biologically optimized dose distributions having utmost precision. The facility will be equipped with state-of-the-art imaging modalities as well as an in-situ Positron-Emission-Tomography (PET). The commissioning of the different sections is scheduled for 2006. The pre-clinical operation will start early in 2007 followed by the routine patient treatment.

Heavy Ion Radiotherapy↗
PubMed2003

Spondylodiscitis as the first manifestation of Whipple's disease -a removal worker with chronic low back pain.

Whipple's disease is a rare systemic infectious disease caused by the actinobacterium Tropheryma whipplei. Spondylodiscitis is an extremely rare manifestation of the infection and has previously been described in only three case reports. We present a 55-year-old man with persistent lumbago and signs of systemic illness, but without any gastrointestinal symptoms or arthralgia. The signal response in the lumbar spine in magnetic resonance tomography, both native and after intravenous gadolinium administration, was compatible with spondylodiscitis at the L4/L5 level. Culture of a specimen obtained by radiographically guided disc puncture and repeated blood cultures remained sterile. Tropheryma whipplei was detected by PCR amplification in material obtained from the disc specimen, from a biopsy of the terminal ileum and from the stool. The histology of duodenum, terminal ileum, colon and disc material was normal and, in particular, showed no PAS-positive inclusions in macrophages. Long-term antibiotic treatment with sulphamethoxazole and trimethoprim was successful, with marked improvement of the low back pain and normalisation of the systemic inflammatory signs. The possibility of Whipple's disease must be suspected in the case of a 'culture-negative' spondylodiscitis even if there are no gastrointestinal symptoms and no arthralgia present.

Anti-Bacterial Agents↗
PubMed2003

Patch-clamping of primary cardiac cells with micro-openings in polyimide films.

Patch-clamping is a powerful method for investigating the function and regulation of ionic channels. Currently, great efforts are being made to automate this method. As a step towards this goal, the feasibility of patch-clamping primary cells with a microscopic opening in a planar substrate was tested. Using standard microfabrication and ion beam technology, small-diameter openings (2 and 4 microm) were formed in polyimide films (thickness 6.5 microm). Single cells (sheep Purkinje heart cells, Chinese hamster ovary cells) in a suspension were positioned on top of the opening and sucked towards the opening to improve adhesion of the cell to the planar substrate, hence increasing the seal resistance. Voltage/current measurements yielded a median seal resistance of 1.3 Mohms with 4 microm openings (n=24) and 26.0 Mohms with 2 microm openings (n = 75), respectively. With 2 microm openings, successful loose-patch recordings of TTX-sensitive inward currents and action potentials in sheep Purkinje heart cells (n = 18) were made. In rare cases, gigaseals (n = 4) were also measured, and a whole-cell configuration (n = 1) could be established. It was concluded that the simple planar patch approach is suitable for automated loose-patch recordings from cells in suspension but will hardly be suitable for high-throughput whole-cell patch-clamping with high-resistance seals.

Animals↗
PubMed2003

[Rehabilitation after injuries to the metacarpal and finger joints].

Finger joint injuries are the most frequent injuries of the hand. Besides operative and conservative therapy of these injuries, it is even more important to ensure a correct and thorough follow-up treatment. The aim of good rehabilitation is a painless, stabilized joint. Based on the therapeutic guidelines of the department of orthopedics, traumatology, and hand surgery of the Free University Berlin, the rehabilitation of these injuries is discussed.

Aftercare↗
PubMed2003

[Rehabilitation after replantation].

Limb replantation represents a particular surgical challenge. Rehabilitation and functional integration of the patient into everyday life has proven to be as equally important as the operation itself. This requires intensive and long-term cooperation between surgeon, therapist, and patient since replanted limbs without restoration of function are of no use. Besides physiotherapy, ergotherapy is highly important for this since it helps to reactivate daily activities.Also, tactile gnosis and protecting nervous sensibility and motor function can be improved by ergotherapy. With the help of special devices, adjustments,and psychological care, ergotherapy also supports the patient's reintegration into his former social environment.

Activities of Daily Living↗
PubMed2003

Comparison of three distraction methods and conventional radiography for early diagnosis of canine hip dysplasia.

Two radiographic distraction techniques (one employing a wooden lath and, the other, a PennHip distractor), an ultrasonographic distraction method and conventional radiographic Fédération Cynologique Internationale (FCI) hip score were evaluated in eight-month-old Labrador retrievers to determine the most reliable method for predicting radiographic FCI hip score at the age of one year. With reference to the FCI hip score, sensitivity and specificity of the PennHip method were 100 per cent and 54 per cent; sensitivity and specificity of the lath technique were 85 per cent and 71 per cent; whereas they were 62 per cent and 67 per cent for the ultrasonographic method. For all distraction methods, the positive predictive value (PPV) was moderate and the negative predictive value (NPV) was high. Sensitivity, specificity, PPV and NPV were 100 per cent for the FCI hip score. It is concluded that, at the age of eight months, FCI hip score is the most reliable method for predicting FCI hip score at the age of one year in the colony of dogs investigated. Both the PennHip and lath method were also clinically reliable techniques in predicting true negatives. The ultrasonographic distraction method was moderately reliable.

Animals↗