Gelatin-Collagen Nonwoven Scaffold Provides an Alternative to Suprathel for Treatment of Superficial Skin Defects.

OBJECTIVE: To evaluate the effect of a new biologic gelatin-collagen nonwoven scaffold compared with a more common synthetic wound dressing on the healing of superficial wounds. METHODS: Three superficial wounds with a depth of 0.5 mm and a length of 2.4 cm were created on the flanks of six minipigs using a skin dermatome. One wound on each pig was treated with the new nonwoven scaffold, one with the more common synthetic wound dressing, and one functioned as an untreated control wound. All three wounds were then covered with a semipermeable, sterile, transparent film. RESULTS: After 7 days, complete wound closure of all wounds could be detected; epidermal thickness and the number of epidermal cells of all treated wounds were significantly increased compared with the control wounds. The nonwoven dressing showed slightly better results compared with the more common dressing. CONCLUSIONS: The nonwoven scaffold is an interesting and competitive material for promoting epidermal wound healing. Because it is a biologic dressing, it degenerates completely and does not have to be removed from the wound. Further research should be conducted to compare this new dressing with other currently available wound treatments.

A Quantitative Analysis of Microcirculation in Skin Defects Covered with Topical Wound Dressings or a Newly Developed Collagen Matrix.

OBJECTIVE: Innovative skin substitutes and temporary wound dressings are frequently used in the treatment of superficial and partial-thickness wounds. The aim of this study was to compare 2 commonly used temporary skin dressings with a newly developed collagen matrix to determine changes in microcirculation as measured by blood flow, hemoglobin oxygenation, and relative hemoglobin values during healing of partial-thickness skin defects. METHODS: This animal study involved 28 adult male Lewis rats. On the back of each rat, 2 standardized partial-thickness skin defects were generated through a skin dermatome (n = 56). Then, wounds were treated with polylactide-based copolymer skin substitute (Suprathel, PolyMedics, Denkendorf, Germany; n = 14), biosynthetic skin dressing (Biobrane, Smith & Nephew, Hamburg, Germany; n = 14), or Collagen Cell Carrier (CCC; Naturin Viscofan, Weinheim, Germany; n = 14). The remaining control wounds were left untreated (n = 14). MAIN OUTCOME MEASURES: Perfusion dynamics were assessed every 10 days for 80 days with the O2C device (LEA Medizintechnik, Gießen, Germany) to determine blood flow, hemoglobin oxygenation, and relative amount of hemoglobin. MAIN RESULTS: Blood flow was increased in all wounds for at least 30 days after wound generation. The relative amounts of hemoglobin were increased in superficial layers (2 mm) for 10 to 20 days. Hemoglobin oxygenation in the superficial layers decreased in the polylactide-based copolymer skin substitute and biosynthetic skin dressing-treated groups and initially increased in the untreated wounds and CCC groups on day 10; these values also decreased. CONCLUSIONS: The presented results demonstrate the complex changes in microcirculation in the course of healing partial-thickness wounds with different wound dressings and contribute to a better understanding of these wounds. However, based on the results of the study, a clear recommendation for a specific substitute is not yet possible.

Determining the appropriate number and duration of leech therapy in congested tissues using tissue spectrophotometry and laser Doppler flowmetry.

A universal protocol determining the number of leeches and their application time does not exist. The aim of this study, therefore, is to quantify perfusion dynamics in venous congested tissues after leech application to get more detailed information about changes due to leech-induced skin microcirculation and to evaluate the usability of the Oxygen to See (O2C) device in terms of determining the appropriate number of leeches and the duration of therapy. Twelve patients with the need for leech therapy participated in the study. Perfusion dynamics of the congested tissue was assessed using the O2C device, which determines blood flow (BF), the relative amount of hemoglobin (rHB), and the oxygen saturation (SO2). Measurements were carried out before leech application and on various intervals like 10 minutes, one hour, and three hours after leech application. The leech application effectuated after 10 minutes a nonsignificant perfusion improvement, which further increased after one hour with a significant reduction of the relative amount of hemoglobin and a significant increase of blood flow and oxygen saturation (BF= +56.7%; rHB= -25.5%; SO2= +53.7%). After three hours, the values returned to the levels before leech administration. In two cases, in which further administration of leeches within the measurement period was necessary, no substantial perfusion changes were obtained. The results of this study forms a more precise pattern of microcirculatory changes of leech therapy in congested tissues. According to our measurements a venous drainage improvement can be expected in congested tissue one hour after leech administration. The O2C seems to be a useful method to determine the appropriate number and duration of leech therapy.

A Novel Collagen-Gelatin Scaffold for the Treatment of Deep Dermal Wounds-An Evaluation in a Minipig Model.

BACKGROUND: Today, autologous skin transplantation is frequently used for full-thickness skin defects. There is still a high demand for new wound-healing products to replace autologous skin transplantation. OBJECTIVE: In this context, the effect of a new collagen-gelatin scaffold on full-thickness skin defects was evaluated. MATERIALS AND METHODS: Four full-thickness skin defects were created surgically on the dorsum of 6 Göttingen minipigs. Three wounds were randomly treated with a novel collagen-gelatin scaffold in different thicknesses, whereas the fourth wound was left untreated and served as a control wound. During the experimental period of 21 days, a close-up photographic documentation was performed. Afterwards, the areas of the initial wounds were excised and examined histologically. RESULTS: The systematic evaluation of 24 wounds showed that treatment with the new collagen-gelatin scaffold led to an accelerated wound repair of 1.1 days. Compared to control wounds, it also demonstrated improved skin quality in regard to epidermal thickness. CONCLUSION: The new collagen-gelatin scaffold supports and accelerates dermal wound repair compared to untreated control wounds. Nevertheless, wound treatment with the scaffold was only performed on the first day. In further studies, the impact of multiple scaffold applications on full-thickness skin defects should be investigated.

Frequent Application of the New Gelatin-Collagen Nonwoven Accelerates Wound Healing.

OBJECTIVE: Mortality after chronic wounds is high. Thus, proper and effective therapy is of critical importance. Adult mammalian skin cannot regenerate spontaneously. It heals under scar formation in a process of repair. In general, wound closure is achieved through a combination of contraction, scar formation, and regeneration. To enhance wound healing, research groups are continuously inventing and evaluating novel skin replacement products. A single application of a new gelatin-collagen nonwoven accelerates wound closure of full-thickness skin defects. Therefore, the authors' objective was to evaluate the effect of a higher application frequency of the nonwoven on wound closure in a minipig model. MATERIALS AND METHODS: Four full-thickness skin defects were created surgically on the dorsum of 12 Göttingen minipigs. Next, 3 wounds were treated randomly with a novel gelatin-collagen nonwoven in different thicknesses, while the fourth wound was left untreated and served as the control wound. Moreover, 6 minipigs achieved multiple applications of the wound dressing. During the experimental period of 21 days, a close-up photographic documentation was performed. Finally, the areas of the initial wounds were excised and examined histologically. RESULTS: More frequent application of the nonwoven achieved accelerated wound healing and better epidermis quality compared with a single application. Mean time until wound closure of all wounds treated with a multiple application of the nonwoven was 11.0 (± 1.2) days, compared with a single application of the nonwoven with 12.4 (± 1.26) days and control wounds with 13.5 (± 1.19) days. Furthermore, the epidermal thickness of all wounds treated with multiple applications of the nonwoven was increased by 10.67 µm (31.89 ± 8.86 µm, P = .0007) compared with a single application of the nonwoven and by 6.53 µm (27.75 ± 7.24 µm, P = .0435) compared with the control group. CONCLUSIONS: Multiple applications of the gelatin-collagen nonwoven may be an appropriate treatment for chronic wounds leading to a fast wound closure through a combination of contraction and re-epithelialization.

Tracheocutaneous fistula closure using a Cartilo-musculo-cutaneous bilobed flap.

In general, the development of a tracheocutaneous fistula (TCF) after tracheotomy is a seldom but recurrent clinical problem in long-term ventilated patients. In cases of prolonged wound healing with no spontaneous wound closure or insufficient later closure by secondary suture, different surgical procedures have been previously described for the closure of TCFs. Nonetheless, each procedure has its individually associated complications so that definite closure of TCFs still remains a challenge. The purpose of this case report is to present a unique case of a patient with a persistent TCF that was successfully closed using a local cartilo-musculo-cutaneous bilobed flap.

A Theoretical Framework for a Hybrid View of the N400.

In this study, we present a novel theoretical account of the N400 event-related potential (ERP) component. Hybrid views interpret this ERP component in terms of two cognitive operations: (i) access of information, which is related to predictions (predictability component), and (ii) integration of information, which is related to plausibility (plausibility component). Though there is an empirical evidence for this view, what has been left open so far is how these two operations can be defined. In our approach, both components are related to categorization. The critical word and the argument position it is related to are associated with categories that have a graded structure. This graded structure is defined in terms of weights both on attributes and values of features belonging to a category. The weights, in turn, are defined using probability distributions. The predictability component is defined in terms of the information gain with respect to non mismatched features between the two categories. The plausibility component is defined as the difference in the degree of typicality between the two categories. Finally, the N400 amplitude is defined as a function of both components.

[SL fusion - no alternative for the treatment of chronic scapholunate dissociation]. / SL-Fusion ­ keine Alternative zur Behandlung der chronischen skapholunären Dissoziation.

INDRODUCTION: The treatment of chronic scapholunate dissociation (SLD) is currently uneven and still presents a major challenge. Both, the primary ligament suture and frequently applied ligament reconstruction techniques cannot provide a permanent stable connection between the scaphoid and lunate. For this reason, the present study evaluates the value of a bony compound as a treatment option for the treatment of chronic SLD. PURPOSE: To evaluate the radiological and clinical outcome of scapholunate fusion for chronic SLD. PATIENTS AND METHODS: Ten patients with a scapholunate fusion with corticocancellous iliac bone graft interposition and Herbert screw fixation for symptomatic chronic SLD were retrospectively evaluated in terms of clinical and radiological findings after a mean of 7.6 years. The examination included range of motion, grip strength, pain, DASH, Krimmer and Modified Mayo Wrist Score (MMWS), and a radiological examination. RESULTS: Primary bone healing was achieved in 4 out of 10 patients. In 2 patients, bone healing of the scapholunate fusion was achieved after revision surgery, in one patient by including the capitate bone in the fusion. Two patients developed fibrous nonunion. In 2 patients, the SLD persisted, requiring a four-corner fusion and wrist denervation, respectively. In all patients, degenerative changes were seen in the radiocarpal joint at follow-up. In spite of the radiological results, the clinical results ranged from fair to good. Seven patients were pain-free at rest. The average MMWS Score was 72 (40-95), the Krimmer Score 78 (55-100), and the DASH Score 17 (0-60). CONCLUSION: Although the clinical results were fair to good, scapholunate fusion cannot be recommended for the treatment of chronic SLD due to a primary failure rate of 60 % regarding bone healing and a 40 % rate of revision surgery.

Changes in the Biomechanical Properties of Human Skin in Hyperthermic and Hypothermic Ranges.

INTRODUCTION: The prevalence of thermal skin injuries is high. Despite new research findings, skin burns and acute cold-contact injuries, together with resulting tissue damage, are not entirely understood. In particular, little is known about how these types of injuries alter the biomechanical properties of skin. OBJECTIVE: This study evaluates hyperthermic- and hypothermic-induced alterations in the biomechanical properties of human skin using a skin elasticity measurement device. MATERIALS AND METHODS: In 54 cases, local hypothermia (15°C and 5°C) and local hyperthermia (40°C and 45°C) were induced at the palmar forearm of healthy participants. The biomechanical properties of skin were measured using the skin elasticity measurement device before and after each temperature change at 2 different depths. RESULTS: The skin firmness, pliability, retraction, and elasticity/calculated elasticity showed a continuous decrease in values with decreasing skin temperatures in total skin measurements and an increase in values with increasing skin temperatures in the upper layer and total skin measurements. CONCLUSIONS: As per the results, the investigators believe these hyperthermic- and hypothermic-induced alterations in biomechanical skin properties are due to increased blood flow, in addition to a reversible increase in interstitial and intracellular fluid contents, thermal contraction, and expansion of collagen and elastic fibers, all of which are precursors to irreversible damage.

Sequestration of cholesterol within the host late endocytic pathway restricts liver-stage Plasmodium development.

While lysosomes are degradative compartments and one of the defenses against invading pathogens, they are also hubs of metabolic activity. Late endocytic compartments accumulate around Plasmodium berghei liver-stage parasites during development, and whether this is a host defense strategy or active recruitment by the parasites is unknown. In support of the latter hypothesis, we observed that the recruitment of host late endosomes (LEs) and lysosomes is reduced in uis4- parasites, which lack a parasitophorous vacuole membrane protein and arrest during liver-stage development. Analysis of parasite development in host cells deficient for late endosomal or lysosomal proteins revealed that the Niemann-Pick type C (NPC) proteins, which are involved in cholesterol export from LEs, and the lysosome-associated membrane proteins (LAMP) 1 and 2 are important for robust liver-stage P. berghei growth. Using the compound U18666A, which leads to cholesterol sequestration in LEs similar to that seen in NPC- and LAMP-deficient cells, we show that the restriction of parasite growth depends on cholesterol sequestration and that targeting this process can reduce parasite burden in vivo. Taken together, these data reveal that proper LE and lysosome function positively contributes to liver-stage Plasmodium development.

J-dot targeting of an exported HSP40 in Plasmodium falciparum-infected erythrocytes.

Plasmodium falciparum exports a large number of proteins to its host cell, the mature human erythrocyte, where they are involved in host cell modification. Amongst the proteins trafficked to the host cell, many are heat shock protein (HSP)40 homologues. We previously demonstrated that at least two exported PfHSP40s (referred to as PFE55 and PFA660) localise to mobile structures in the P. falciparum-infected erythrocyte (Kulzer et al., 2010), termed J-dots. The complete molecular content of these structures has not yet been completely resolved, however it is known that they also contain an exported HSP70, PfHSP70x, and are potentially involved in transport of the major cytoadherance ligand, PfEMP1, through the host cell. To understand more about the nature of the association of exported HSP40s with J-dots, here we have studied the signal requirements for recruitment of the proteins to these structures. By expressing various exported GFP chimeras, we can demonstrate that the predicted substrate binding domain is necessary and sufficient for J-dot targeting. This targeting only occurs in human erythrocytes infected with P. falciparum, as it is not conserved when expressing a P. falciparum HSP40 in Plasmodium berghei-infected murine red blood cells, suggesting that J-dots are P. falciparum-specific. This data reveals a new mechanism for targeting of exported proteins to intracellular structures in the P. falciparum-infected erythrocyte.

The use of collagen-based matrices in the treatment of full-thickness wounds.

Chronic and complex full-thickness wounds have become increasingly prevalent. Besides autologous skin transplantation, innovative wound dressing products have gained interest, as the functional and esthetic outcome is still limited. In this respect, the effect of a novel modifiable collagen-gelatin fleece on the healing of deep dermal wounds was examined and compared with untreated controls and Matriderm(®). A total of 48 full-thickness skin defects were generated on six minipigs and treated with the novel collagen-gelatin fleece of different thicknesses in single or multiple application (n=36) or treated with Matriderm(®) in a single application (n=6), or the wounds were left untreated (n=6). Wound healing was analyzed planimetrically by wound closure per time and histologically with regard to epidermal thickness and cell density. Compared to untreated wounds, wound closure per time and histological skin quality with regard to the mean epidermal thickness and epidermal cell amount were enhanced in both treatment groups. Overall, the best results for the novel collagen-gelatin fleece were achieved for multiple applications with a thickness of 150g/m(2). The novel biomaterial shows accelerated and improved dermal wound repair in a minipig model. As the manufacturing process of the scaffold allows the integration of bioactive substances such as antibiotics and growth factors, we intend to design a composite biomaterial using this scaffold as a carrier matrix.

Trafficking of the signature protein of intra-erythrocytic Plasmodium berghei-induced structures, IBIS1, to P. falciparum Maurer's clefts.

Remodeling of the host red blood cell by Plasmodium falciparum is well established and crucial for infection and parasite virulence. Host cell modifications are not exclusive to human Plasmodium parasites and also occur in hepatocytes and erythrocytes infected with murine Plasmodium parasites. The recently described intra-erythrocytic P. berghei-induced structures (IBIS) share similarities to P. falciparum Maurer's clefts. It is shown here that a potential candidate IBIS1 homologue in P. falciparum, PfHYP12 (PF3D7_1301400), is partially exported into the erythrocyte cytoplasm. To analyze a potential similarity between IBIS and Maurer's clefts we expressed the signature protein of IBIS in P. falciparum parasites. Visualization of the tagged protein revealed that PbIBIS1 can be exported by P. falciparum and localizes to Maurer's clefts in P. falciparum-infected erythrocytes, which indicates that IBIS and Maurer's clefts may be evolutionarily conserved parasite-induced structures in infected erythrocytes.

Alteration of Biomechanical Properties of Skin During the Course of Healing of Partial-thickness Wounds.

UNLABELLED: The incidence of partial-thickness wounds is high and, until recently, little was known about the alteration of the biomechanical properties of the skin in these wounds during the course of healing. The aim of this study was to demonstrate the biomechanical changes in skin elasticity. MATERIALS AND METHODS: Fourteen standardized skin defects were created on the back of fourteen adult male Lewis rats (Charles River Laboratories International, Inc, Wilmington, MA) using a skin dermatome. Biomechanical properties of the skin were determined every 10 days over a period of 3 months using a skin elasticity measurement device (Cutometer MPA 580, Courage and Khazaka, Cologne, Germany). Calculated elasticity (UE), firmness of skin (R0), and overall elasticity (R8) were assessed. In addition, histological evaluation was performed in regard to quality of skin. RESULTS: After an initial decrease of UE, R0, and R8 until 30 days after surgery, the values of R0 and R8 increased between day 50 and day 60. Starting on day 60, a further decrease of values was indicated. CONCLUSION: The alteration of biomechanical properties of skin is a function of tissue structure. The presented results demonstrate the complex changes of skin biomechanical properties in the course of healing of partial-thickness wounds. This study could serve as a model to compare the effectiveness of different wound dressings in regard to skin elasticity.

Assessment of microcirculatory changes of cold contact injuries in a swine model using laser Doppler flowmetry and tissue spectrophotometry.

BACKGROUND: Until now, the exact pathophysiology of frostbite injuries is poorly understood. The aim of the study is to evaluate the perfusion changes of frostbite injuries to get a better understanding of the exact mechanism underlying the resulting tissue damage. Particular attention has been given to the differentiation of changes between the various injury depths. METHODS: Cold contact injury ranging from superficial, superficial-partial, deep-partial to full thickness were generated using seven goettingen minipigs. The perfusion dynamics were assessed before and 3 h after the injuries were inflicted using the O2C-device, which combines a laser light, to determine blood flow, and white light to determine hemoglobin oxygenation and relative amount of hemoglobin. A total of 42 cold contact injuries were inflicted and 84 measurements were carried out. RESULTS: In superficial and superficial partial injuries there was an increase in the blood flow (mean, 20 ± 2.4%, 15 ± 5.1%, respectively) and in the relative amount of hemoglobin (mean, 29 ± 9.1%, 28 ± 7.2%, respectively), whereas the hemoglobin oxygenation did not alter (mean, -0.15 ± 2.4%, -0.8 ± 3.1%, respectively). In deep partial injuries there was a decrease in the blood flow (mean range, -4 ± 2.1 to -17 ± 4.7%) and an increase in the relative amount of hemoglobin (mean range, 79 ± 17.2 to 93 ± 17.7%), whereas the hemoglobin oxygenation did not alter (mean range, -0.7 ± 3.1 to -2.9 ± 3.3%). In full thickness injuries there was a drop in the blood flow (mean range, -24 ± 7.6 to -27 ± 11.8%) and in the hemoglobin oxygenation (mean range, -16 ± 3.5 to -19 ± 2.5%) and an increase in the relative amount of hemoglobin (mean range, +126 ± 19.8 to 145 ± 10.9%). CONCLUSION: The results of this study form a more precise pattern of cold contact injury perfusion changes, which can be a valuable tool to assess the degree of cold contact injury and furthermore the efficacy of novel diagnostic aids, therapeutics and treatment modalities.

Development of an animal frostbite injury model using the Goettingen-Minipig.

BACKGROUND: A standardized reproducible animal model is desirable to gain a better understanding in the pathophysiology of frostbite injury and to develop novel therapies. Little has been studied about frostbite injury models. The depth and extent were not always being controllable and consistent. Therefore, we developed a frostbite injury model using the Göttingen Minipigs. METHODS: 42 frostbite injuries were inflicted on the abdomen of seven minipigs using an aluminium bar (300g, circular with a radius of 1cm) frozen with liquid nitrogen to -196°C. The bar was applied for 1, 3, 6, 12, 30 and 60s. Five hours after injury biopsies were performed and evaluated by the presence of denatured collagen, blood vessels, follicular epithelial cells and mesenchymal cells. RESULTS: A large spectrum of frostbite injuries was obtained ranging from superficial, superficial partial, deep partial to full thickness. The depth of injury in the sets of frostbites was highly consistent (Pearson correlation ranged from r=0.89 to 0.94). CONCLUSION: We described a simple, inexpensive and safe swine frostbite model. The accurate reproducibility of the depth of the frostbite injuries allows researchers to accurately plan frostbite studies.

Use of self-assembling GFP to determine protein topology and compartmentalisation in the Plasmodium falciparum-infected erythrocyte.

In recent years, and largely supported by the increasing use of transfection technology, much research attention has been given to protein trafficking in the Plasmodium falciparum infected red blood cell. By expression of fluorescent reporter proteins, much information has been gained on both the signals and mechanisms directing proteins to their correct sub-cellular localisation within the parasite and infected host cell. Generally however, verification of the observed fluorescent phenotype is carried out using more traditional techniques such as co-immunofluorescence, protease protection, and cell fractionation followed by Western blot. Here we apply a self-assembling split GFP (saGFP) system and show that this can be used to determine both membrane topology and compartmentalisation using transfection technology alone. As an example, we verify the topology of an ER membrane protein, hDer1-1, and of an exported parasite Hsp40 co-chaperone, PFE55. Additionally, we can demonstrate that this system has the potential to be applied to analysis of organellar proteins.

Functional importance of laparoscopic sleeve gastrectomy for the lower esophageal sphincter in patients with morbid obesity.

BACKGROUND: Obesity is characterized by excess body fat measured in body mass index (BMI), which is the weight in kilograms (kg) divided by the height in square meters [m(2)]. In the Northern Hemisphere, the prevalence of overweight has increased by up to 34%. This situation is associated with high incidence of comorbidities such as gastroesophageal reflux disease. Bariatric surgery is the only effective treatment for severe obesity, resulting in amelioration of obesity comorbidities. Data on LES competence following sleeve gastrectomy (SG), one of the several bariatric procedures, are conflicting. METHODS: In a prospective study, we enrolled 37 patients and divided them into two subgroups in order to evaluate lower esophageal sphincter pressure (LESP) and esophageal motility before and after laparoscopic sleeve gastrectomy (LSG) by means of stationary esophageal manometry. A study collective also underwent a gastroscopy. Participants (20) were healthy controls who volunteered. RESULTS: Preoperative median BMI in group I (control) differed statistically significantly (p < 0.0001) as compared to groups II and III (22 vs. 50.5 or 47.5 kg/m², respectively). After LSG, the BMI of groups II and III decreased to 39.5 and 45 kg/m², respectively. Postoperatively, LESP increased significantly, namely, from preoperative 8.4 to 21.2 mmHg in group II and from 11 to 24 mmHg (p < 0.0001) in group III. Tubular esophageal motility profits from LSG. As expected, the gastroscopy findings ranged from cardiac insufficiency, esophagitis and hiatal hernia to gastric ulcer. CONCLUSION: LSG significantly increased lower esophageal pressure independent of weight loss after LSG and may protect obese patients from gastroesophageal reflux.