[Deer farming in Switzerland - Current epidemiological situation with focus on husbandry, management and nutrition]

INTRODUCTION

Between September 2016 and February 2017 a survey in Swiss deer farms were conducted to gain information about their husbandry. Questions about the business, feeding, management, health and deworming strategies were asked. 98 (19%) out of 527 registered farms (2016) participated in the survey. The farms were often run on a sideline business, had an average used agricultural area of 7.3 ha with an average of 38 deer. Pasture access was the preferred feeding strategy followed by offering first and second cut hay. Between 2013-2015 the most common causes of death were sudden death and injuries. Parasites were classified as no or rather small problem by 91 out of 102 deer owner. Fecal parasitological examinations of fecal samples were conducted in 36 (35%) of the responding farms. Gastrointestinal roundworms (Trichostrongylidae) were identified as the most common pathogens (in 42-59% of sampled farms), in addition large lungworms (Dictyocaulus sp.) and coccidia were detected. 45% of the participating farmers conducted at least one treatment against parasites between 2013 and 2015.

[Displaced pain pump because of a pendulous abdomen - dermatolipectomy as solution of the problem]

A female patient with a chronic pain syndrome after multiple operation on her muskuloskeletal system presented with a displaced pain pump in her lower left abdominal region. After an excessive weight loss due to gastric banding the patient developed a massive pendulous abdomen causing the complication. An interdisciplinary dermatolipectomy together with a refixation of the pump was performed. Since this operation a recurrence of the displacement has not been observed and consecutively the filling of the pump could be accomplished without radiological investigations. This rare case demonstrates the significance of interdisciplinary treatment in which a primarily aesthetic intervention was necessary for a successful therapeutic outcome.

Decellularized dermis in combination with cultivated keratinocytes in a short- and long-term animal experimental investigation

Decellularized human dermis as a potentially ideal scaffold for dermal substitution in severe burns was examined in a two-staged animal experiment. In an initial step, an in vitro generated composite graft consisting of human keratinocytes and decellularized dermis (AlloDerm) was transplanted onto nude mice in a short-term trial (n = 20, 14 days). Subsequently, a combined one-step grafting of full thickness wounds with both decellularized dermis (in part preincubated with fibroblasts) and cultivated autologous keratinocytes as a cell suspension in fibrin glue was done in a long-term porcine animal model (n = 10, 6 months). In both series, macroscopic wound healing was evaluated by planimetry. Histological investigations included morphological as well as immunohistochemical parameters. The short-term study showed both successful integration of the composite grafts and reduction of wound contraction compared with the control group (epithelial grafts). The long-term porcine study displayed reduced myofibroblast formation and contraction in the wounds that had been treated with fibroblast-preincubated dermis. After 4 weeks, a decline of the structural integrity of the dermal matrix could be noticed. The utility of decellularized dermis as template for both dermal reconstitution and keratinocyte delivery vehicle was shown. The closure of full thickness wounds by a single-step combination of an autologous keratinocyte fibrin sealant suspension and acellular dermis in a pig animal model could be shown. Incorporation of fibroblasts led to reduced wound contraction but could not prevent the loss of dermal integrity. The engineered 'skin' remained viable and stable over a period of 6 months.

Tissue engineering of skin substitutes

Cultivated epithelial autografts as multilayered thin sheets represent common standard in clinically applied tissue engineering substitutes, outnumbering all experimental alternatives. However, the unsatisfying short and long term results concerning mechanical stability and scarring demand for alternatives. Our group investigated cultivation and transplantation of cultured autologous keratinocytes as a single cell suspension in a fibrin sealant matrix in athymic mice in combination with allogenic skin grafting. We observed reliable wound reepithialization after a cultivation period of only 2 weeks. Additionally, we could allocate successful combination of a keratinocyte fibrin sealant suspension and acellular dermis in an attempt to regenerate full thickness skin defects in a pig animal model. The potential clinical implication of subconfluently cultured keratinocytes is enhanced by the possibility of co-transplantation with decellularized dermis.

[Skin tissue engineering]

Cultivated epithelial autografts as multilayered, thin sheets represent a common standard in clinically applied tissue engineering substitutes, outnumbering all experimental alternatives. However, the unsatisfying short- and long-term results concerning mechanical stability and scarring require alternatives. The cultivation and transplantation of cultured autologous keratinocytes as a single cell suspension in a fibrin matrix, combined with allogenic skin grafting, has been investigated extensively in athymic nude mice. Wounds can be reliably reepithelialized after a cultivation period of only 14 days. Moreover, the successful combination of keratinocyte fibrin suspension and acellular dermis in an attempt to regenerate full thickness skin defects in a pig model has been demonstrated. The usefulness of subconfluently cultured keratinocytes-which can be harvested very early and are easy to handle-is enhanced by cotransplantation with decellularized dermis.

Skin tissue engineering

The coverage of extensive wounds with viable autologous keratinocytes remains the only option of treatment if autologous donor skin is not obtainable. There is evidence that proliferating keratinocytes, as suspended cells or as a single layer, are adequate for wound closure. Understanding keratinocyte-matrix interactions not only allows us to influence keratinocyte outgrowth, adhesion, and migration, but may also guide us to modify matrix molecules for enhancing keratinocyte take. Further approaches may include the generation of genetically manipulated keratinocytes, which allow the use of an off-the-shelf epidermal replacement. As surgeons, our goal is to help burn patients with the best quality of skin in the shortest time possible. As tissue engineers, we have not achieved the goal of a universal skin product. By continually reviewing the options and using them, we can at least use the proper material in the adequate situation. Because of the limited resources, the need for comparisons of clinical effectiveness and cost are ever more important. As anatomy and physiology of engineered skin substitutes improve, they will become more similar to native skin autografts. Improvement of skin substitutes will result from inclusion of additional cell types (eg, melanocytes) and from modifications of culture media and scaffolds. Skin-substitute materials may be able to stimulate regeneration rather than repair, and tissue-engineered skin may match the quality of split-skin autografts, our present gold standard.

Feasibility of biolistic gene therapy in burns

Skin is an especially attractive target for genetic manipulation because it is readily accessible and easily monitored for both the presence and the expression of inserted genes. This study was designed to assess the feasibility of particle mediated gene transfer to burned skin and to compare the transfection efficiency, anatomic distribution, and duration of transgene expression achievable in normal versus burned skin. Two days following scald injury of varying depths in 60 degrees C water (10 s: superficial partial; 20 s: deep partial; 40 s: full thickness) reporter gene (beta-galactosidase) constructs were delivered using a gene gun at various helium pressures (200-600 psi) to normal and burned skin. A time course study was performed to examine the kinetics of transgene expression. Animals received a superficial partial thickness burn and were sacrificed 12 h, 1, 3, 5, 7, 14, or 21 days after gene transfer. India Ink injection and immunohistochemistry were used to assess the depth of the scald injury. Transfection efficiency was measured in skin homogenates 24 h after gene transfer by morphometric and chemoluminescent assays. We found that the extent of tissue damage was directly related to the duration of heat source exposure. Reporter gene activity was significantly higher in superficial partial thickness burns compared to normal controls and gradually declined with increasing tissue injury. No activity was seen in the full thickness burn group. Beta-galactosidase activity reached a maximum level 12 h after gene transfer in both normal and superficial partial thickness burned skin with no levels seen after 5 days post-transfection. These findings indicate that particle-mediated gene transfer in thermally injured skin is feasible and may provide a means of introducing biologic agents into injured tissue capable of enhancing bacterial clearance and improving wound healing.