Sebastian E. Dunda

Retrograde tracing and toe spreading after experimental autologous nerve transplantation and crush injury of the sciatic nerve: a descriptive methodological study.

Evaluation of functional and structural recovery after peripheral nerve injury is crucial to determine the therapeutic effect of a nerve repair strategy. In the present study, we examined the relationship between the structural evaluation of regeneration by means of retrograde tracing and the functional analysis of toe spreading. Two standardized rat sciatic nerve injury models were used to address this relationship. As such, animals received either a 2 cm sciatic nerve defect (neurotmesis) followed by autologous nerve transplantation (ANT animals) or a crush injury with spontaneous recovery (axonotmesis; CI animals). Functional recovery of toe spreading was observed over an observation period of 84 days. In contrast to CI animals, ANT animals did not reach pre-surgical levels of toe spreading. After the observation period, the lipophilic dye DiI was applied to label sensory and motor neurons in dorsal root ganglia (DRG; sensory neurons) and spinal cord (motor neurons), respectively. No statistical difference in motor or sensory neuron counts could be detected between ANT and CI animals. In the present study we could indicate that there was no direct relationship between functional recovery (toe spreading) measured by SSI and the number of labelled (motor and sensory) neurons evaluated by retrograde tracing. The present findings demonstrate that a multimodal approach with a variety of independent evaluation tools is essential to understand and estimate the therapeutic benefit of a nerve repair strategy.

A multi-center study on the regenerative effects of erythropoietin in burn and scalding injuries: study protocol for a randomized controlled trial

BackgroundAlthough it was initially assumed that erythropoietin (EPO) was a hormone that only affected erythropoiesis, it has now been proposed that EPO plays an additional key role in the regulation of acute and chronic tissue damage.Via the inhibition of inflammatory reactions and of apoptosis, stem cell recruitment, advancement of angiogenesis and growth factor release, EPO enhances healing and thus restitutio ad integrum after trauma. Human skin contains EPO receptors and is able to synthesize EPO. We therefore hypothesize that EPO is able to optimize wound healing in thermally injured patients.Methods/DesignThis is a large, prospective, randomized, double-blind, multi-center study, funded by the German Federal Ministry of Education and Research, and fully approved by the designated ethics committee. The trial, which is to investigate the effects of EPO in severely burned patients, is in its recruitment phase and is being carried out in 13 German burn care centers. A total of 150 patients are to be enrolled to receive study medication every other day for 21 days (EPO 150 IU/kg body weight or placebo). A follow-up of one year is planned. The primary endpoint of this study is the time until complete re-epithelialization of a defined skin graft donor site is reached. Furthermore, clinical parameters such as wound healing, scar formation (using the Vancouver scar scale), laboratory values, quality of life (SF-36), angiogenic effects, and gene- and protein-expression patterns are to be determined. The results will be carefully evaluated for gender differences.DiscussionWe are seeking new insights into the mechanisms of wound healing in thermally injured patients and more detailed information about the role EPO plays, specifically in these complex interactions. We additionally expect that the biomimetic effects of EPO will be useful in the treatment of acute thermal dermal injuries.Trial registrationEudraCT Number: 2006-002886-38, Protocol Number: 0506, ISRCT Number: http://controlled-trials.com/ISRCTN95777824/ISRCTN95777824.

The performance of an orthosilicic acid-releasing silica gel fiber fleece in wound healing

In the present work, we have examined the impact of an inorganic orthosilicic acid-releasing spun fiber fleece (SIFIB) on wound closure in a porcine wound model in vivo as well as on wound healing-relevant parameters in vitro. In vivo SIFIB was completely bio-degradable and had no negative effects on wound closure or the wound healing process. In the in vitro experiments, SIFIB had no negative effects on proliferation of human skin fibroblast (FB) and endothelial cell (EC) cultures but strongly retarded the growth of the human monocyte cell line THP-1, and effectively inhibited human skin keratinocyte (KC) proliferation, which based on significantly enhanced KC differentiation. Furthermore, SIFIB exhibited strong anti-inflammatory properties, which based on SIFIB-dependent inhibition of expression and activity of NF-кB and/or concomitant enhanced expression of IкB, a NF-кB-inhibiting protein. Additionally, SIFIB significantly inhibited TGFβ-induced fibroblast differentiation and collagen synthesis as well as effectively reduced TGF-β synthesis of activated fibroblasts. We have demonstrated wound healing-relevant biological activities of a silica-based bio-degradable inorganic material, which might represent a new therapeutic tool in the treatment of chronic wounds.

Epineurial sheath tube (EST) technique: an experimental peripheral nerve repair model.

Abstract Objective: Here we present the epineurial sheath tube (EST) technique as a modified microsurgical rat sciatic nerve model. The EST technique provides a cavity or pouch consisting of an outer epineurial sleeve that has been freed from nerve fascicles. This cavity may be appropriate to test the effectiveness and biocompatibility of implanted growth factors, cell suspensions (embedded in solutions or gels), or bioartificial nerve guide constructs. Methods: A total number of 10 rats underwent the surgical procedure for the EST technique. Cylinders made of fibrin gel served as implants and place-holders. Three animals were euthanized directly after operation, while the others survived for 6 weeks. After immersion fixation (3·9% glutaraldehyde), both conventional histology [semi-thin sections (1 μm), toluidine blue] and scanning electron microscopy were performed. Results: Conventional histology and scanning electron microscopy of samples that had been fixed directly after the surgical procedure displayed the integrity of the closed epineurial tube with the fibrin cylinder in its center. Even after 6 weeks, the outer epineurium was not lacerated, the stitches did not loosen, and the lumen did not collapse, but remained open. Discussion: The practicability of the EST technique could be verified regarding feasibility, reproducibility, mechanical stability, and openness of the lumen. The EST technique can be adapted to other nerve models (e.g. median or facial nerve). It provides a cavity or pouch, which can be used for different neuroscientific approaches including concepts to improve the therapeutic benefit of autologous nerve grafting or therapies to be used as an alternative to autologous nerve grafting.

A Rare Case of Toxic Epidermal Necrolysis with Unexpected Fever Resulting from Dengue Virus

Toxic epidermal necrolysis (TEN), also known as Lyell’s syndrome, is a life-threatening disease with common development of large wounds. Thus, affected patients are usually treated in specialized centers. Herein, we present a case of TEN in a patient infected with human immunodeficiency virus with the additional, unexpected diagnosis of dengue fever. In this context, we discuss cause, diagnosis, pathology, and treatment of TEN and highlight the role of rare and unexpected findings, as in this case an additional tropical virus infection. We underpin the importance of an interdisciplinary approach involving dermatologists, ophthalmologists, intensive care physicians, burn specialists and various other departments and emphasize the challenge of TEN treatment, especially if rare pathological findings occur.

Management, clinical outcomes, and complications of acute cannula-related peripheral vein phlebitis of the upper extremity: A retrospective study

Objective Acute phlebitis due to peripheral vein catheter use is frequently observed in clinical practice, and requires surgical therapy in severe cases. In this retrospective study, we aimed to increase awareness, evaluate current treatment options, and develop recommendations to optimize treatment outcomes. Methods A total of 240 hospitalized patients with a diagnosis of upper extremity phlebitis from 2006 to 2011 were evaluated in terms of initial clinical features, parameters, co-morbidities and treatment regimes. Severity of phlebitis was graded according to the Baxter scale by assessing clinical symptoms such as pain, erythema, induration, swelling, or palpable venous cord (grade 0–5). Patients were divided in two subgroups: conservative (n = 132) and operative (n = 108) treatment. Results Surgical intervention rates and severity were higher for cannula insertion in the cubital fossa region than for cannula insertion in the forearm and hand region (p < 0.05). Baxter scale grades were higher in the surgical treatment group than in the conservative treatment group (4.47 vs. 2.67, respectively). Conclusions The cubital fossa region is vulnerable to severe phlebitis and is not recommended as the first site of choice for cannulation. Phlebitis of Baxter scale grade 4 or 5 should be considered for early surgical intervention.

Current diagnostics and treatment of the cubital tunnel syndrome in Austria.

According to the vote of the Austrian Society for Surgery of the Hand (ÖGH) an investigation to collect data on the current state of the treatment of cubital tunnel syndrome was initiated. Over one year a total of 875 patients with cubital tunnel syndrome were operated in Austria, this means an incidence of this nerve entrapment of 0.011%. Most of the operations were done by trauma surgeons (287; 33%). For diagnosis most of the centers rely on clinical symptoms, electroneurophysiology, and elbow X-ray. 40% of the institutions regard conservative therapy as useless and not indicated. If conservative treatment modalities are applied, physiotherapy (97%), non-steroidal anti-inflammatory medication (77%), and glucocorticoid injections (30%) are primarily used. In case of simple nerve entrapment most of the surgeons (72%) prefer simple nerve decompression. If there is additional pathology subcutaneous cubital nerve transposition is recommended (62%). Endoscopic techniques are only use by 3% of the surgeons. In the postoperative care, physiotherapy is favored in 51%, whereas 24% do not judge any postoperative care as beneficial. The three most often encountered complications were incomplete remission, scar contracture and hypertrophy, and postoperative bleeding.

[In Vitro and In Vivo Biocompatibility of a Novel, 3-Dimensional Cellulose Matrix Structure].

BACKGROUND Biological and physical characteristics of matrices are one essential factor in creating bioartificial tissue. In this study, a new 3-dimensional cellulose matrix (Xellulin(®)) was tested in terms of biocompatibility and applicability for tissue engineering in vitro and in vivo. MATERIALS AND METHODS The tested matrix Xellulin(®) is a natural hydrological gel-matrix containing bacterial cellulose and water. To evaluate the cell biocompatibilty, cell adherence and proliferation characteristics in vitro, the matrix was cultured with human fibroblasts. Further in vivo studies were carried out by transplanting preadipocytes of 4- to 6-week-old Wistar rats with 3 different conditions: a) Xellulin(®) including 500 000 preadipocytes subcutaneous, b) Xellulin(®) including 500 000 preadipocytes within an in vivo bioreactor chamber, c) Xellulin(®) without cells subcutaneous as control. After explantation on day 14 histomorphological and immunohistochemical evaluations were performed. RESULTS In vitro study revealed an excellent biocompatibility with good cell adherence of the fibroblasts on the matrix and evidence of cell proliferation and creation of a 3-dimensional cell network. In vivo neocapillarisation could be shown in all groups with evidence of erythrocytes (H/E staining) and endothelial vascular cells (RECA-1-staining). A significantly higher vascular density was shown in vascularised bioreactor group (18.4 vessels/100 000 µm(2) (group b) vs. 8.1 (group a), p<0.05). Cell density was the highest in the vascularised group, but without significant values. No immunogenic reaction to the matrix was noticed. DISCUSSION The promising in vitro results concerning cell adherence and proliferation on the tested matrix could be confirmed in vivo with an evidence of 3-dimensional neocapillarisation. Cell survival was higher in the vascularised group, but without significance. Long-term tests (28-42 days) need to be carried out to evaluate long-term cell survival and the matrix stability. Furthermore, studies concerning the implementation of the matrix within anatomic structures as well as long-term biocompatibility are needed.

Reconstructive surgery in immunocompromised patients: evaluation and therapy.

Background: An increasing number of patients undergoing reconstructive surgery are immunocompromised due to different reasons and different medical treatments. Some of the used immunosuppressive drugs may affect the process of wound healing and thereby, impair the long-term success of surgical treatment. Therefore, this retrospective analysis aimed at the evaluation of the perioperative treatment and surgical outcome of immunocompromised patients undergoing different reconstructive procedures. Methods: A retrospective review was performed of 8 immunocompromised patients with different primary diseases who needed reconstructive surgery: 2 patients with non-Hodgkin lymphoma, 1 patient with an acute myeloid leukemia, 1 patient with colitis ulcerosa, 1 patient with liver cirrhosis, 1 patient with chronic polyarthritis, and 2 patients with malignant melanoma. Results: In 7 of our 8 presented cases, multiple operations with wound debridements have been necessary to optimize the granulation of the wound bed before reconstructive surgery. 3 out of these 7 patients required further operations due to wound dehiscence or necrosis, with 2 of them as a result of increased immunosuppressive therapy. 5 out of 8 patients needed no further surgical treatment. Conclusions: Both the perioperative drug therapy and the reconstructive surgery concept need to be determined carefully in each individual case of the immunocompromised patients. Thus, the appropriate point in time of operation to achieve the best possible wound healing as well as the complexity of the procedure will require the consideration of a ‘less is more’ strategy in selected cases.