The Dorsal Skinfold Chamber as a New Tympanic Membrane Wound Healing Model: Intravital Insights into the Pathophysiology of Epithelialized Wounds.

BACKGROUND: Tympanic membrane perforations (TMPs) are a common complication of trauma and infection. Persisting perforations result from the unique location of the tympanic membrane. The wound is surrounded by air of the middle ear and the external auditory canal. The inadequate wound bed, growth factor, and blood supply lead to circular epithelialization of the perforation's edge and premature interruption of defect closure. Orthotopic animal models use mechanical or chemical tympanic membrane laceration to identify bioactive wound dressings and overcome premature epithelialization. However, all orthotopic models essentially lack repetitive visualization of the biomaterial-wound interface. Therefore, recent progress in 3D printing of customized wound dressings has not yet been transferred to the unique wound setup of the TMP. Here, we present a novel application for the mice dorsal skinfold chamber (DSC) with an epithelialized full-thickness defect as TMP model. METHODS: A circular 2-mm defect was cut into the extended dorsal skinfold using a biopsy punch. The skinfold was either perforated through both skin layers without prior preparation or perforated on 1 side, following resection of the opposing skin layer. In both groups, the wound was sealed with a coverslip or left unclosed (n = 4). All animals were examined for epithelialization of the edge (histology), size of the perforation (planimetry), neovascularization (repetitive intravital fluorescence microscopy), and inflammation (immunohistology). RESULTS: The edge of the perforation was overgrown by the cornified squamous epithelium in all pre-parations. Reduction in the perforation's size was enhanced by application of a coverslip. Microsurgical preparation before biopsy punch perforation and sealing with a coverslip enabled repetitive high-quality intravital fluorescence microscopy. However, spontaneous reduction of the perforation occurred frequently. Therefore, the direct biopsy punch perforation without microsurgical preparation was favorable: spontaneous reduction did not occur throughout 21 days. Moreover, the visualization of the neovascularization was sufficient in intravital microscopy. CONCLUSIONS: The DSC full-thickness defect is a valuable supplement to orthotopic TMP models. Repetitive intravital microscopy of the epithelialized edge enables investigation of the underlying pathophysiology during the transition from the inflammation to the proliferation phase of wound healing. Using established analysis procedures, the present model provides an effective platform for the screening of bioactive materials and transferring progress in tissue engineering to the special conditions of tympanic membrane wound healing.

A prospective survey study on the education and awareness about walking exercise amongst inpatients with symptomatic peripheral arterial disease in Germany.

Background: To determine the adherence to supervised exercise training and underlying reasons for non-adherence amongst patients with inpatient treatment of symptomatic lower extremity peripheral arterial disease (PAD). Patients and methods: This was a prospective questionnaire-based survey study of all consecutively treated inpatients with treatment for either intermittent claudication or chronic limb-threatening ischaemia (CLTI) surveyed at sixteen participating centres in Germany. Results: A total of 235 patients (median age 70 years) were included, thereof 29.4% females and 34.6% with CLTI. The median time from first PAD diagnosis was 4 years (IQR: 1-8). Only 11.4% have previously participated in any walking exercise programme before the index treatment, thereby 10.0% in the IC subgroup and 12.0% with CLTI. Amongst all patients, 35.6% responded they were appropriately informed about the necessity and benefits of walking exercise programmes by their hospital physicians (25.8% by general practitioners), and 65.3% agreed that adherence to supervised exercise may improve their pain-free walking distance. A total of 24.5% responded they had access to necessary information concerning local walking exercise programmes. Amongst 127 free text comments on the reasons for non-adherence to supervised exercise training, 64% of the comments contained lack of information or consent on such measures. Conclusions: Less than 12% of the patients enrolled in the current study have ever participated in a walking exercise programme during their life course. Although all practice guidelines contain corresponding class I recommendations, especially for patients suffering from IC, most patients responded that they were not appropriately informed about the necessity of exercise training along with the fact that 65% agreed that exercise may increase the pain-free walking distance. Taken all together, these results emphasise that we miss an important opportunity in the patient-physician communication. Efforts should be made to improve acceptance and application of structured walking-exercise for patients with PAD.

Hyperspectral imaging for monitoring of perfusion failure upon microvascular anastomosis in the rat hind limb.

BACKGROUND/PURPOSE: Objective, reliable and easy monitoring of microvascular tissue perfusion is a goal that was achieved for many years with limited success. Therefore, a new non-invasive hyperspectral camera system (TIVITA™) was tested for this purpose in an in vivo animal model. METHODS: Evaluation of tissue oxygenation during ischemia and upon reperfusion was performed in left hind limb in a rat model (n=20). Ischemia was induced by clamping and dissection of the superficial femoral artery. Reperfusion of the limb was achieved by microsurgical anastomosis of the dissected artery. Oxygenation parameters of the hind limb were assessed via TIVITA™ before and immediately after clamping and dissection of the artery, 3 and 30min after reperfusion as well as on postoperative days 1 and 2. Thereby, the non-operated hind limb served as control. As clinical parameters, the refill of the anastomosis as well as the progress of the affected leg were assessed. RESULTS: In 12 from 20 cases, TIVITA™ recorded a sufficient reperfusion with oxygenation parameters comparable to baseline or control condition. However, in 8 from 20 cases oxygenation was found impaired after reperfusion causing a re-assessment of the microvascular anastomosis. Thereby, technical problems like stenosis or local thrombosis were found in all cases and were surgically treated leading to an increased tissue oxygenation. CONCLUSIONS: The TIVITA™ camera system is a valid non-invasive tool to assess tissue perfusion after microvascular anastomosis. As it safely shows problems in oxygenation, it allows the clinician a determined revision of the site in time in order to prevent prolonged ischemia.

The effects of hydrogen sulfide on platelet-leukocyte aggregation and microvascular thrombolysis.

The volatile transmitter hydrogen sulfide (H2S) is known for its various functions in vascular biology. This study evaluates the effect of the H2S-donor GYY4137 (GYY) on thrombus stability and microvascular thrombolysis. Human whole blood served for all in vitro studies and was analyzed in a resting state, after stimulation with thrombin-receptor activating peptide (TRAP) and after incubation with 10 or 30 mM GYY or its vehicle DMSO following TRAP-activation, respectively. As a marker for thrombus stability, platelet-leukocyte aggregation was assessed using flow cytometry after staining of human whole blood against CD62P and CD45, respectively. Furthermore, morphology and quantity of platelet-leukocyte aggregation were studied by means of scanning electron microscopy (scanning EM). Therefore, platelets were stained for CD62P followed by immuno gold labeling. In vivo, the dorsal skinfold chamber preparation was performed for light/dye induction of thrombi in arterioles and venules using intravital fluorescence microscopy. Thrombolysis was assessed 10 and 22 h after thrombus induction and treatment with the vehicle, GYY, or recombinant tissue plasminogen activator (rtPA). Flow cytometry revealed an increase of CD62P/CD45 positive aggregates after TRAP stimulation of human whole blood, which was significantly reduced by preincubation with 30 mM GYY. Scanning EM additionally showed a reduced platelet-leukocyte aggregation and a decreased leukocyte count within the aggregates after preincubation with GYY compared to TRAP stimulation alone. Further on, morphological signs of platelet activation were found markedly reduced upon treatment with GYY. In mice, both GYY and rtPA significantly accelerated arteriolar and venular thrombolysis compared to the vehicle control. In conclusion, GYY impairs thrombus stability by reducing platelet-leukocyte aggregation and thereby facilitates endogenous thrombolysis.

Effect of the hydrogen sulfide donor GYY4137 on platelet activation and microvascular thrombus formation in mice.

This study evaluates the effect of the H2S donor GYY4137 (GYY) on adhesion molecule expression, protein S-sulfhydration and morphology of platelets in vitro and on kinetics of microvascular thrombus formation in vivo. Using flowcytometry, untreated resting, TRAP-activated, or TRAP-activated and GYY-exposed human platelets were studied for expression of P-selectin, GPIb and GPIIb/IIIa as well as for fibrinogen binding. By means of electron microscopy, platelet morphology and intracellular granule numbers were assessed. Platelet shape change was studied using immunohistochemistry for P-selectin, NSF and F-actin by SR-SIM. Biotin switch assay served for the analysis of platelet protein S-sulfhydration by GYY. Using the FeCl3 and the light/dye model in dorsal skinfold chamber-equipped mice, the effect of GYY and its vehicle DMSO was studied on venular thrombus formation and tail-vein bleeding time. Soluble (s)P-selectin plasma concentrations were measured in GYY- or DMSO-treated animals. Exposure to GYY increased the S-sulfhydration of platelet proteins. GYY reduced dose-dependently the TRAP-induced adhesion molecule expression and attenuated the morphological signs of TRAP-associated platelet activation. In mice, GYY caused a significant prolongation of venular thrombus formation and tail-vein bleeding time. Application of an anti-P-selectin antibody in DMSO-exposed animals prolonged thrombosis formation comparably as GYY did. GYY reversed the TRAP-induced distribution of P-selectin at the plasma membrane of platelets. This indicates reduced exocytosis and shedding of P-selectin, which is supported by significantly lower sP-selectin concentrations in GYY- vs. DMSO-treated mice. H2S acts anti-thrombotic and seems to regulate thrombogenesis by interference with platelet activation and adhesion molecule-mediated aggregation.

Synergistic effect of cold gas plasma and experimental drug exposure exhibits skin cancer toxicity in vitro and in vivo.

INTRODUCTION: Skin cancer is often fatal, which motivates new therapy avenues. Recent advances in cancer treatment are indicative of the importance of combination treatments in oncology. Previous studies have identified small molecule-based therapies and redox-based technologies, including photodynamic therapy or medical gas plasma, as promising candidates to target skin cancer. OBJECTIVE: We aimed to identify effective combinations of experimental small molecules with cold gas plasma for therapy in dermato-oncology. METHODS: Promising drug candidates were identified after screening an in-house 155-compound library using 3D skin cancer spheroids and high content imaging. Combination effects of selected drugs and cold gas plasma were investigated with respect to oxidative stress, invasion, and viability. Drugs that had combined well with cold gas plasma were further investigated in vascularized tumor organoids in ovo and a xenograft mouse melanoma model in vivo. RESULTS: The two chromone derivatives Sm837 and IS112 enhanced cold gas plasma-induced oxidative stress, including histone 2A.X phosphorylation, and further reduced proliferation and skin cancer cell viability. Combination treatments of tumor organoids grown in ovo confirmed the principal anti-cancer effect of the selected drugs. While one of the two compounds exerted severe toxicity in vivo, the other (Sm837) resulted in a significant synergistic anti-tumor toxicity at good tolerability. Principal component analysis of protein phosphorylation profiles confirmed profound combination treatment effects in contrast to the monotherapies. CONCLUSION: We identified a novel compound that, combined with topical cold gas plasma-induced oxidative stress, represents a novel and promising treatment approach to target skin cancer.

Contribution of protein Z and protein Z-dependent protease inhibitor in generalized Shwartzman reaction.

OBJECTIVE: Sepsis, a leading cause of mortality in critically ill patients, is closely linked to the excessive activation of coagulation and inflammation. Protein Z, a cofactor for the protein Z-dependent protease inhibitor, enhances the inhibition of coagulation factor Xa, and protein Z-dependent protease inhibitor inhibits factor XIa in a protein Z-independent fashion. The functions of protein Z and protein Z-dependent protease inhibitor in the inflammatory and coagulant responses to septic illness have not been evaluated. DESIGN: For induction of generalized Shwartzman reaction, dorsal skinfold chamber-equipped mice were challenged twice with lipopolysaccharide (0.05 mg/kg on day -1 and 5 mg/kg body weight 24 hr later). Time-matched control animals received equal volumes of saline. SETTING: University research laboratory. SUBJECTS, INTERVENTIONS, AND MEASUREMENTS: Using intravital fluorescence microscopy in protein Z-dependent protease inhibitor deficient (ZPI) and protein Z deficient (PZ) mice, as well as their wild-type littermates (ZPI, PZ), kinetics of light/dye-induced thrombus formation and microhemodynamics were assessed in randomly chosen venules. Plasma concentrations of chemokine (C-X-C motif) ligand 1, interleukin-6, and interleukin-10 were measured. Liver and lung were harvested for quantitative analysis of leukocytic tissue infiltration and thrombus formation. MAIN RESULTS: After induction of generalized Shwartzman reaction, all mice showed significant impairment of microhemodynamics, including blood flow velocity, volumetric blood flow, and functional capillary density, as well as leukocytopenia and thrombocytopenia. Thrombus formation time was markedly prolonged after induction of generalized Shwartzman reaction in all mice, except of ZPI mice, which also had a significantly higher fraction of occluded vessels in liver sections. PZ mice developed the highest concentrations of interleukin-6 and interleukin-10 in response to generalized Shwartzman reaction and showed greater leukocytic tissue infiltration than their wild-type littermates. CONCLUSIONS: In this murine model of generalized Shwartzman reaction, protein Z-dependent protease inhibitor deficiency enhanced the thrombotic response to vascular injury, whereas protein Z deficiency increased inflammatory response.

Effects of systemic pretreatment with CpG oligodeoxynucleotides on skin wound healing in mice.

Unmethylated CpG oligodeoxynucleotides (ODN) bind to the Toll-like receptor 9, thus stimulating the immune system. To study the effects of systemic pretreatment with CpG ODN on dermal regeneration, C57BL6/J Tyr mice were treated with CpG or control ODN 6 days prior to implantation of a dorsal skinfold chamber and skin wounding. Wound epithelialization was analyzed by planimetric microscopy. On day 18, wound tissues were taken for (immuno)histochemical staining. CpG ODN increased epithelialization compared with control ODN treatment. Histological analysis revealed reduced capillary density, reduced wound cellularity, and reduced numbers of infiltrating leukocytes, as well as reduced F4/80-positive macrophages, but increased numbers of RELM-α-positive M2 macrophages after CpG ODN treatment, reflecting a better quality of wound healing on day 18 compared with control ODN treatment. Reverse transcription-polymerase chain reaction analysis of Toll-like receptor 9 showed the receptor expression on both fibroblasts and keratinocytes. Fibroblasts showed an increase of migration upon increasing dosages of CpG and not control ODN, reaching ∼50% of the response of basic fibroblast growth factor-exposed cells. Keratinocytes dose-dependently responded to both CpG and control ODN up to values found in keratinocyte growth factor-exposed cells. In summary, CpG ODN support late tissue-remodeling processes that contribute to resolution of inflammation and solid wounds during skin regeneration.

Quality of Life after Desarda Technique for Inguinal Hernia Repair-A Comparative Retrospective Multicenter Study of 120 Patients.

Inguinal hernia repair, according to Desarda, is a pure tissue surgical technique using external oblique fascia to reinforce the posterior wall of the inguinal canal. This has provided an impetus for the rethinking of guideline adherence toward minimally invasive and mesh-based surgery of inguinal hernia. In this study, a retrospective analysis of this technique was conducted in two German hospitals. Between 6/2013 and 12/2020, 120 operations were performed. Analysis included patient characteristics, duration of operation, length of hospital stay, and perioperative complications. Data were used to achieve a matched-pair analysis comparing Desarda to laparoscopic transabdominal preperitoneal (TAPP) hernia repair. Propensity scores were calculated based on five preoperative variables, including sex, age, American Society of Anesthesiology classification, localization, and width of the inguinal hernia in order to achieve comparability. Additionally, we assessed pain level and quality of life (QoL) 12 months postoperatively. The focus of our study was a comparison of QoL to a reference population and TAPP cohort. The study population consisted of 106 male and 14 female patients, and the median age was 37.5 years. The median operation time was 50 min, and the median length of hospital stay was 2 days. At a follow-up of 17 months, the median recurrence rate was 0.8%, and two cases of chronic postoperative pain were recorded. Postoperative QoL does not significantly differ between Desarda and TAPP. In contrast, Desarda patients had a significantly higher QoL compared with the reference population. In summary, Desarda's procedure is a good option as a pure tissue method for inguinal hernia repair.

Assessment of Quality of Life after Endovascular and Open Abdominal Aortic Aneurysm Repair: A Retrospective Single-Center Study.

Postoperative quality of life is an important outcome parameter after treatment of abdominal aortic aneurysms. The aim of this retrospective single-center study was to assess and compare the health-related quality of life (HRQoL) of patients after open repair (OR) or endovascular treatment (EVAR), and furthermore to investigate the effect of incisional hernia (IH) formation on HRQoL. Patients who underwent OR or EVAR for treatment of an abdominal aortic aneurysm between 2008 and 2016 at a University Medical Center were included. HRQoL was assessed using the SF-36 questionnaire. The incidence of IH was recorded from patient files and by telephone contact. SF-36 scores of 83 patients (OR: n = 36; EVAR: n = 47) were obtained. The mean follow-up period was 7.1 years. When comparing HRQoL between OR and EVAR, patients in both groups scored higher in one of the eight categories of the SF36 questionnaires. The incidence of IH after OR was 30.6%. In patients with postoperative IH, HRQoL was significantly reduced in the dimensions "physical functioning", "role physical" and "role emotional" of the SF-36. Based on this data, it can be concluded that neither OR nor EVAR supply a significant advantage regarding HRQoL. In contrast, the occurrence of IH has a relevant impact on the HRQoL of patients after OR.

3D-printed lightweight dorsal skin fold chambers from PEEK reduce chamber-related animal distress.

The dorsal skinfold chamber is one of the most important in vivo models for repetitive longitudinal assessment of microcirculation and inflammation. This study aimed to refine this model by introducing a new lightweight chamber made from polyetheretherketone (PEEK). Body weight, burrowing activity, distress, faecal corticosterone metabolites and the tilting angle of the chambers were analysed in mice carrying either a standard titanium chamber or a PEEK chamber. Data was obtained before chamber preparation and over a postoperative period of three weeks. In the early postoperative phase, reduced body weight and increased faecal corticosterone metabolites were found in mice with titanium chambers. Chamber tilting and tilting-related complications were reduced in mice with PEEK chambers. The distress score was significantly increased in both groups after chamber preparation, but only returned to preoperative values in mice with PEEK chambers. In summary, we have shown that light chambers reduce animal distress and may extend the maximum dorsal skinfold chamber observation time. Chambers made of PEEK are particularly suitable for this purpose: They are autoclavable, sufficiently stable to withstand rodent bites, inexpensive, and widely available through 3D printing.

Treatment of an Infected TEVAR with Extra- and Endovascular Bacteriophage Application.

Introduction: Graft infections are severe complications. Surgical resection of infected aortic stent grafts is associated with high mortality and morbidity. Therefore, alternatives or adjuncts to antibiotic treatment and extensive surgery are urgently needed. Report: A 67 year old woman was admitted with a methicillin sensitive Staphylococcus aureus infected stent graft in the thoracic aorta. Local infection was confirmed by PET-CT imaging. Surgical resection of the stent graft was not feasible because of comorbidities. Therefore, a three step approach for local bacteriophage treatment was performed as a last resort treatment. Firstly, the para-aortic tissue was debrided via left thoracotomy, a bacteriophage suspension was applied on the outer surface of the aorta, and a vacuum irrigation system was installed. After repeated alternating instillation of the bacteriophage suspension for three days, as a second step, the vacuum sponges were removed and a bacteriophage containing gel was applied locally on the outer surface of the aorta. In the third step, the bacteriophage containing gel was applied to a thoracic stent graft, which in turn was placed endovascularly into the infected stent. Discussion: After 28 days, the patient was discharged from hospital with normalised infection parameters. PET-CT imaging at three and 12 months post-intervention did not show signs of infection in or around the thoracic aorta. This Case demonstrates successful treatment of an infected endovascular stent graft by application of bacteriophages both to extravascular and, as a novel approach, endovascular sites using a bacteriophage coated stent graft.

Evaluation of Hyperspectral Imaging for Follow-Up Assessment after Revascularization in Peripheral Artery Disease.

BACKGROUND: Assessment of tissue oxygenation is an important aspect of detection and monitoring of patients with peripheral artery disease (PAD). Hyperspectral imaging (HSI) is a non-contact technology for assessing microcirculatory function by quantifying tissue oxygen saturation (StO2). This study investigated whether HSI can be used to monitor skin oxygenation in patients with PAD after appropriate treatment of the lower extremities. METHODS: For this purpose, 37 patients with PAD were studied by means of ankle-brachial index (ABI) and HSI before and after surgical or endovascular therapy. Thereby, the oxygenation parameter StO2 and near infrared (NIR) perfusion index were quantified in seven angiosomes on the diseased lower leg and foot. In addition, the effects of skin temperature and physical activity on StO2 and the NIR perfusion index and the respective inter-operator variability of these parameters were investigated in 25 healthy volunteers. RESULTS: In all patients, the ABI significantly increased after surgical and endovascular therapy. In parallel, HSI revealed significant changes in both StO2 and NIR perfusion index in almost all studied angiosomes depending on the performed treatment. The increase in tissue oxygenation saturation was especially pronounced after surgical treatment. Neither heat nor cold, nor physical activity, nor repeated assessments of HSI parameters by independent investigators significantly affected the results on StO2 and the NIR perfusion index. CONCLUSIONS: Tissue oxygen saturation data obtained with HSI are robust to external confounders, such as temperature and physical activity, and do not show inter-operator variability; therefore, can be used as an additional technique to established methods, such as the ABI, to monitor peripheral perfusion in patients with PAD.

Distribution of Mobile Health Applications amongst Patients with Symptomatic Peripheral Arterial Disease in Germany: A Cross-Sectional Survey Study.

BACKGROUND: Broadly available digital and mobile health applications (also known as mHealth) have recently gained increasing attention by the vascular community, but very little is known about the dissemination and acceptance of such technologies in certain target populations. The current study aimed to determine the user behaviour and acceptance of such digital technologies amongst patients with peripheral arterial disease (PAD). METHODS: A cross-sectional survey of consecutively treated inpatients at 12 university institutions, as well as one non-university institution, was conducted. All admitted patients with symptomatic PAD were surveyed for 30 consecutive days within a flexible timeframe between 1 July and 30 September 2021. The factors associated with smartphone use were estimated via backward selection within a logistic regression model with clustered standard errors. RESULTS: A total of 326 patients participated (response rate 96.3%), thereof 102 (34.0%) were treated for intermittent claudication (IC, 29.2% women, 70 years in median) and 198 were treated for chronic limb-threatening ischaemia (CLTI, 29.5% women, 70 years in median). Amongst all of the patients, 46.6% stated that they had not changed their lifestyle and health behaviour since the index diagnosis (four years in median), and 33.1% responded that they were not aware of the reasons for all of their medication orders. Amongst all those surveyed, 66.8% owned a smartphone (IC: 70.6%, CLTI: 64.1%), thereof 27.9% needed regular user support. While 42.5% used smartphone apps, only 15.0% used mobile health applications, and 19.0% owned wearables. One out of five patients agreed that such technologies could help to improve their healthy lifestyle. Only higher age was inversely associated with smartphone possession. CONCLUSIONS: The current survey showed that smartphones are prevalent amongst patients with peripheral arterial disease, but only a small proportion used mobile health applications and a considerable number of patients needed regular user support. Almost half of the patients did not change their lifestyle and one third were not aware of the reasons for their medication orders, emphasising room for improvement. These findings can further help to guide future projects using such applications to identify those target populations that are reachable with digital interventions.

Erythropoietin improves skin wound healing and activates the TGF-ß signaling pathway.

We could recently report that erythropoietin (EPO) accelerates skin wound healing in mice. Now, we provide insight into the molecular mechanisms of this non-hematopoietic property of EPO analyzing the transforming growth factor (TGF)-ß signaling pathway. EPO receptor was found expressed in both non-wounded and wounded skin tissue as well as in fibroblasts and keratinocytes. In saline-treated control animals, wounds exhibited a significant upregulation of TGF-ß1 and of α-smooth muscle actin (α-SMA) compared with non-wounded skin. EPO treatment accelerated wound epithelialization and induced mRNA expression of TGF-ß1 and α-SMA. In addition, EPO significantly enhanced phosphorylation of Smad2 and Smad3 in fibroblasts and also elevated phosphorylation of Smad3 in wound tissue. Blockade of TGF-ß using a neutralizing anti-TGF-ß antibody attenuated EPO-induced acceleration of wound epithelialization in vivo and markedly reversed EPO effects on mRNA expression of TGF-ß1 and α-SMA. In conclusion, EPO caused activation of the Smad-dependent TGF-ß signaling pathway, enhanced differentiation of myofibroblasts, and accelerated skin wound closure.

Experimental Models to Study Skin Wound Healing with a Focus on Angiogenesis.

A large number of models are now available for the investigation of skin wound healing. These can be used to study the processes that take place in a phase-specific manner under both physiological and pathological conditions. Most models focus on wound closure, which is a crucial parameter for wound healing. However, vascular supply plays an equally important role and corresponding models for selective or parallel investigation of microcirculation regeneration and angiogenesis are also described. In this review article, we therefore focus on the different levels of investigation of skin wound healing (in vivo to in virtuo) and the investigation of angiogenesis and its parameters.

Intraoperative Assessment of Gastric Sleeve Oxygenation Using Hyperspectral Imaging in Esophageal Resection: A Feasibility Study.

INTRODUCTION: Sufficient tissue oxygenation is essential for anastomotic healing in visceral surgery. Hyperspectral imaging (HSI) is a noncontact, noninvasive technique for clinical assessment of tissue oxygenation in real time. METHODS: In this case series, HSI was used in 4 patients who were admitted for either esophageal cancer or cardiac carcinoma (AEG type I or II). Thoraco-abdominal surgical esophageal resection was performed after staging and neoadjuvant therapy. Intraoperative oxygenation of superficial (StO2) and underlying tissue (NIR perfusion index) of the gastric sleeve were studied intrathoracic by means of the TIVITA® Tissue HSI camera. This was performed prior to esophagogastric anastomosis. The postoperative course, especially in view of surgical complications, was recorded. RESULTS: Assessment of StO2 and NIR perfusion index was performed in 4 regions of interest per gastric sleeve, aboral and oral of the clinically determined resection line. It allowed the fast quantification of gastric oxygenation prior gastroesophageal anastomosis. Median StO2 aboral of the determined resection line was 69%, while median StO2 in the oral part of the gastric sleeve was found at 53%. In contrast, the median NIR perfusion index was similar aboral (80) and oral (82) of the resection line. In none of the 4 studied patients, an anastomotic failure appeared. DISCUSSION/CONCLUSION: This report suggests that HSI is a feasible technique for intraoperative assessment of tissue oxygenation before gastroesophageal anastomosis and might reduce the incidence of anastomotic failure in the gastrointestinal tract.

Distress Analysis of Mice with Cervical Arteriovenous Fistulas.

The welfare of laboratory animals is a consistent concern for researchers. Its evaluation not only fosters ethical responsibility and addresses legal requirements, but also provides a solid basis for a high quality of research. Recently, a new cervical arteriovenous model was created in mice to understand the pathophysiology of arteriovenous fistula, which is the most commonly used access for hemodialysis. This study evaluates the distress caused by this new animal model. Ten male C57B6/J mice with cervical arteriovenous fistula were observed for 21 days. Non-invasive parameters, such as body weight, faecal corticosterone metabolites, burrowing activity, nesting activity and distress scores were evaluated at each time point. Six out of ten created arteriovenous fistula matured within the observation time as defined by an increased diameter. The body weight of all animals was reduced after surgery but recovered within five days. In addition, the distress score was significantly increased during the early time point but not at the late time point after arteriovenous fistula creation. Neither burrowing activity nor nesting behaviour were significantly reduced after surgical intervention. Moreover, faecal corticosterone metabolite concentrations did not significantly increase. Therefore, the cervical murine arteriovenous fistula model induced moderate distress in mice and revealed an appropriate maturation rate of the fistulas.

Diagnostic Ability of Methods Depicting Distress of Tumor-Bearing Mice.

Subcutaneous tumor models in mice are the most commonly used experimental animal models in cancer research. To improve animal welfare and the quality of scientific studies, the distress of experimental animals needs to be minimized. For this purpose, one must assess the diagnostic ability of readout parameters to evaluate distress. In this study, we evaluated different noninvasive readout parameters such as body weight change, adjusted body weight change, faecal corticosterone metabolites concentration, burrowing activity and a distress score by utilising receiver operating characteristic curves. Eighteen immunocompromised NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ mice were used for this study; half were subcutaneously injected with A-375 cells (human malignant melanoma cells) that resulted in large tumors. The remaining mice were inoculated with SCL-2 cells (cutaneous squamous cell carcinoma cells), which resulted in small tumors. The adjusted body weight and faecal corticosterone metabolites concentration had a high diagnostic ability in distinguishing between mice before cancer cell injection and mice bearing large tumors. All other readout parameters had a low diagnostic ability. These results suggest that adjusted body weight and faecal corticosterone metabolites are useful to depict the distress of mice bearing large subcutaneous tumors.