[Causes, injuries, therapy and possibilities of prevention of equine-related accidents. Results of a 2-center-study]. / Ursachen, Verletzungen, Therapie und Präventionsmöglichkeiten von Unfällen im Reitsport. Ergebnisse einer 2-Center-Studie.

BACKGROUND: Horse riding is associated with a high rate of injuries. The possibilities of prevention are limited because of deficient knowledge about the causes and mechanisms of equine-related accidents. In the present study 198 equine-related accidents were analyzed and based on these data risk groups were identified and guidelines to improve safety in horse riding were formulated. MATERIAL AND METHODS: In this 2-center study the accidents of 169 riders over a period of 12 months were analyzed. Data on equine-related patterns of injury and the resulting treatment were collated from the clinical records. Additionally, a questionnaire was completed on the day of trauma by the patients, which covered age, gender, the cause and mechanism of injury and the use of safety equipment at the time of the accident. RESULTS: There were 169 (85.5%) female and 29 (14.5%) male riders with a median age of 27.2 years (range 5-74 years). Of the riders 55 (27.8%) were aged 18 years or younger, 134 (67.7%) riders were treated as outpatients while 64 (32.3%) required hospitalization, 51 (25.8%) required surgical treatment, 66 (33.3%) used a helmet and 14 (7.1%) a body protector at the time of accident. DISCUSSION: Equestrians wear helmets increasingly more when riding but the willingness to wear body protectors is disappointing. Protective headgear has been proven to reduce the risk of injuries but based on these data a positive effect of body protectors could not be shown. In this study safety vest users suffered from injuries of the upper body more often than those who did not wear a body protector. Children and adolescents often overestimate their skills; therefore, teaching and supervision of inexperienced young riders along with the use of protective equipment can prevent major injuries.

[Osteoporotic fractures of the distal radius. What is new?]. / Osteoporotische Frakturen des distalen Radius. Was ist neu?

The demographic development will result in an increase of up to 30 % of distal radius fractures. There are various therapy options but what is new? Conservative therapy: conservative therapy is reserved for stable fractures only. Osteosynthesis by K-wires: due to low biomechanical stability in older patients, insufficient functional and radiological results were achieved. External fixator: external fixators are used in compound and complex fractures and show better results than K-wire osteosynthesis. Angular stable plate osteosynthesis: with angular stable plates it is possible to achieve good results with complex fractures and they are currently the method of choice. Intramedullary osteosynthesis: intramedullary nails result in a faster functional improvement than angular stable plates but have limitations. New is that 90% of osteoporotic distal radial fractures are treated with angular stable plates which have shown good results in single study groups.

Evaluation of reproductive barriers and realisation of interspecific hybridisations depending on genetic distances between species in the genus Helleborus.

The genus Helleborus comprises 22 species, which are allocated to six sections. H. x hybridus and H. niger, which belong to different Helleborus sections, are economically important ornamentals. Several other species with minor impact exhibit interesting features, e.g. flower size, flower colour, foliage, scent and disease resistance, which should be introgressed into H. x hybridus or H. niger through interspecific hybridisation. The aims of this study were to investigate whether and which kind of hybridisation barriers occur in crosses between Helleborus species and if they differ in their manifestations, depending on the genetic distance of the respective partners. In order to obtain interspecific hybrids despite crossing barriers, a method to overcome these barriers should be developed. Crossing barriers in Helleborus were localised as predominantly post-zygotic according to in situ pollen tube staining with aniline blue. For certain crosses, pre-zygotic barriers could also be assumed, but pollen tube growth was not totally inhibited. Therefore, embryo rescue techniques via ovule culture were established to overcome the post-zygotic barriers. Ovules were isolated from maternal plants 5-7 weeks after pollination in most cases and then cultured in vitro. Overall, 219 hybrids were successfully obtained, of which 16 were derived from inter-sectional crosses. Hybrids were verified by flow cytometry and/or by molecular DNA markers.

On the role of DNA biomechanics in the regulation of gene expression.

DNA is traditionally seen as a linear sequence of instructions for cellular functions that are expressed through biochemical processes. Cellular DNA, however, is also organized as a complex hierarchical structure with a mosaic of mechanical features, and a growing body of evidence is now emerging to imply that these mechanical features are connected to genetic function. Mechanical tension, for instance, which must be felt by DNA within the heavily constrained and continually fluctuating cellular environment, can affect a number of regulatory processes implicating a role for biomechanics in gene expression complementary to that of biochemical regulation. In this article, we review evidence for such mechanical pathways of genetic regulation.

Mid-term results after operative treatment of rockwood grade III-V acromioclavicular joint dislocations with an AC-hook-plate.

Acromioclavicular joint dislocations often occur in athletic, young patients after blunt force to the shoulder. Several static and dynamic operative procedures with or without primary ligament replacement have been described. Between February 2003 and March 2009 we treated 313 patients suffering from Rockwood III-V lesions of the AC joint with an AC-hook plate. 225 (72 %) of these patients could be followed up. Mean operation time was 42 minutes in the conventional group and 47 minutes in the minimal invasive group. The postoperative pain on a scale from 1 to 10 (VAS-scale) was rated 2.7 in the conventional group and 2.2 in the minimal invasive group. Taft score showed very good and good results in 189 patients (84%). Constant score showed an average of 92.4 of 100 possible points with 89 % excellent and good results and 11 % satisfying results. All patients had some degree of pain or discomfort with the hook-plate in place. These symptoms were relieved after removal of the plate. The overall complication rate was 10.6 %. There were 6 superficial soft tissue infections, 1 fracture of the acromion, 7 redislocations after removal of the hook-plate. We observed 4 broken hooks which could be removed at the time of plate removal, 4 seromas and 2 cases of lateral clavicle bone infection, which required early removal of the plate. We can conclude that clavicle hook plate is a convenient device for the surgical treatment of Rockwood Grade III-V dislocations, giving good mid-term results with a low overall complication rate compared to the literature. Early functional therapy is possible and can avoid limitations in postoperative shoulder function.

Bead size effects on protein-mediated DNA looping in tethered-particle motion experiments.

Tethered particle motion (TPM) has become an important tool for single-molecule studies of biomolecules; however, concerns remain that the method may alter the dynamics of the biophysical process under study. We investigate the effect of the attached microsphere on an illustrative biological example: the formation and breakdown of protein-mediated DNA loops in the lac repressor system. By comparing data from a conventional TPM experiment with 800 nm polystyrene beads and dark-field TPM using 50 nm Au nanoparticles, we found that the lifetimes of the looped and unlooped states are only weakly modified, less than two-fold, by the presence of the large bead. This is consistent with our expectation of weak excluded-volume effects and hydrodynamic surface interactions from the cover glass and microsphere.

[Pseudo-arthroses]. / Pseudarthrosen.

Pseudo-arthroses are disorders of fracture healing after conservative or operative treatment of fractures which are older than 6 months. Decisive for a targeted therapy is a differentiation between aseptic and septic or atrophic, oligotrophic or hypertrophic pseudo-arthrosis. The operative principals include revitalization of atrophic bone fragments, stabilizing reosteosynthesis for instability and the treatment of infection by transformation of a septic into a stabilized or aseptic pseudo-arthrosis.

Determination of optimal non-invasive patient fixation methods for use in robotic hip replacement surgery--an in vitro study.

BACKGROUND: A robotic system for the implantation of a total hip arthroplasty (THA) is currently under development. One of the goals of this system is non-invasive patient fixation, aiding the robotic system by an infrared tracking system. To determine the extent of fixation that can be achieved by non-invasive methods, an in vitro study was performed. METHODS: In cadaver testing, different non-invasive fixation methods (Arthrex leg holder with tourniquet mechanism; arthroscopic leg holder with disposable foam inserts; gynaecological leg holder; Goepel knee crutch) were evaluated under load in different directions. RESULTS: Deviation was measured in the range 0.33-18.1 mm with up to 20 N load. The testing showed the pneumatic leg holder system to provide the highest stability, followed by an arthroscopic leg holder system with foam inserts. CONCLUSIONS: Use of a leg holder with foam inserts produced a stability that should enable tracking of the remaining deviation by the navigation system. We will therefore use this method in our future development of the robotic milling tool.

Particle transport in asymmetric scanning-line optical tweezers.

We describe a scanning-line optical tweezing technique with an asymmetric beam profile in the back focal plane of the microscope objective. The motion of a trapped particle along the scan line is studied as a function of beam asymmetry, and it is shown that this technique can be used to exert a constant lateral force on the particle, realizing purely optical constant-force tweezing. The observed effect is attributed in a geometric optics model to a non-zero lateral component of the scattering force.

Femtonewton force spectroscopy of single extended DNA molecules.

We studied the thermal fluctuations of single DNA molecules with a novel optical tweezer based force spectroscopy technique. This technique combines femtonewton sensitivity with millisecond time resolution, surpassing the sensitivity of previous force measurements in aqueous solution with comparable bandwidth by a hundredfold. Our data resolve long-standing questions concerning internal hydrodynamics of the polymer and anisotropy in the molecular relaxation times and friction coefficients. The dynamics at high extension show interesting nonlinear behavior.

Systemic effects and side effects of interstitial techniques used in liver tissue.

BACKGROUND: Percutaneous ethanol injection (PEI) and cryosurgery are increasingly used for the treatment of liver malignancies. To create a safety margin and to destroy completely diffusely growing tumors, the precise destruction of healthy liver tissue is necessary. Little is known about the effects of operating on this type of tissue. This study evaluated the effects and side effects of PEI and cryosurgery when applied to normal parenchyma of the liver. STUDY DESIGN: Two groups of six minipigs each were treated with either PEI or cryosurgery to create necrosis in the liver. During and after the procedures, vital signs were monitored and necrotic areas were observed by ultrasonography. Standard and immunohistochemistry stains were made from samples of the necrosis, the liver, and the lung. RESULTS: In the PEI group, thromboembolic complications occurred in all animals (fatality rate 50%). Hematogenous spread of hepatocytes was demonstrated by immunohistochemistry and was a cause of pulmonary embolism. In the cryosurgery group, neither specific complications nor signs of cell spillage occurred. Because of an isolating effect of blood perfusion, hepatocytes close to the portal triads were less damaged, vital cells were present in the periphery, and the necroses were smaller than the induced lesions. CONCLUSIONS: The effect of PEI in healthy liver tissue is unpredictable. This makes the creation of a safety margin or the treatment of a diffusely infiltrating tumor impossible. PEI always introduces the risk of hematogenous cell spread. Effects of cryosurgery are less dependent on tissue qualities. In both techniques, the real extent of complete tissue destruction cannot be visualized by ultrasonography.

Genetic modification of the phenotypes produced by amyloid precursor protein overexpression in transgenic mice.

Overexpression of Alzheimer amyloid precursor protein (APP) produces dramatically different phenotypes in transgenic mice depending on the genetic background. For example, concentrations of APP that produce amyloid plaques in outbred transgenic lines are lethal for inbred FVB/N or C57BL/6J mice. Expression of SOD1 transgenes is protective, suggesting involvement of oxidative damage in premature death, but ablation of Apoe had no significant effect. In contrast, FGF2 transgene overexpression enhances the lethal effects of APP. Differential survival does not appear to reflect genetic differences in APP processing, but rather host responses to APP or its derivatives.

Cockroach allergy in Kentucky: a comparison of inner city, suburban, and rural small town populations.

The cockroach has been reported as a major allergen in inner city asthmatic patients. The retrospective chart review of 799 patients tested over a 10-year period (1981-1991) derived from a private allergy practice and a university allergy clinic is reported. Patients from both groups were divided geographically by home zip codes into inner city, suburban, or rural small town populations. Criteria for positive skin tests were wheal greater than 5 mm for prick and greater than 10 mm for intradermal tests with flare. Overall, 36.9% (295/799) of all patients surveyed were positive by either prick or intradermal skin testing. Cockroach reactivity was observed in 38.6% (95/246) of the private patients tested with 36.2% (200/553) of the university patients showing positive results. The inner city populations in both groups of patients were similar with 43.7% and 40.3% of the private and university patients, respectively, testing positive, with an overall positivity of 41% for all inner city patients. Inner city and rural small town populations for both study groups demonstrated almost identical reactivity with 41% and 43% overall positivity, respectively. Of the suburban group, 37.5% of the private patients and 28.8% of the university patients had reactive skin tests results with an overall rate of positivity of 30.1%. This rate (30.1%) is significantly less than the rate for either inner city (41.0%, P < .05) or rural small town (43.6%, P < .01) populations.(ABSTRACT TRUNCATED AT 250 WORDS)