Evaluation of the Educational Environment of a Cadaver Course in Robotic Colorectal Surgery: A Cross-sectional Study.

BACKGROUND: The educational environment is a crucial metric of medical education that affects the course participants' motivation, achievement, happiness and success. The aim of this study was to evaluate the educational environment of a cadaver course in robotic colorectal surgery by comparing the perceptions of the participating residents to those of the participating surgeons. METHODS: This was a cross-sectional study carried out in 2017. Participants from the U.S. and Europe attended a course using eight fresh frozen cadaver torsos with no prior abdominal surgery. After course completion, participants anonymously completed 50-item Dundee Ready Educational Environment Measure (DREEM) questionnaires to evaluate five components of the educational environment: perception of learning, perception of teachers, academic self-perception, perception of atmosphere, and social self-perception. Internal consistency of the questionnaire was assessed using Cronbach's alpha coefficient. Mean scores were compared using an independent samples t-test. RESULTS: Twenty of 24 participants completed the DREEM questionnaire, consisting of 9 residents and 11 surgeons (12 from the U.S., 8 from Europe). The internal consistency of the questionnaire was excellent (alpha=0.97). The mean total score was excellent for both residents and surgeons, and the difference between the groups was not significant (154.1±25.8 vs. 168.1±18.9, p=0.197). Perception of learning was significantly better among surgeons ("teaching highly thought of") than among residents ("a more positive perception") (40.5±3.6 vs. 35.7±5.6, p=0.04). CONCLUSIONS: This study suggests that the residents' perception of learning may have been negatively influenced by the participation of surgeons in the same cadaver station.

Embolization of a common carotid aneurysm with rhVEGF coupled to a pH-responsive chitosan in a rat model.

OBJECT: Treatment of cerebral aneurysms by endovascular deployment of liquid embolic agents has been proposed as an alternative strategy to conventional coiling, and new materials are being developed for embolization. In this study, the authors used a single-injection, biocompatible, biodegradable and pH-responsive acrylated chitosan (aCHN) with conjugated vascular endothelial growth factor (rhVEGF) in a rat aneurysm model. METHODS: The efficacy of the aCHN formulation with rhVEGF was tested using a common carotid artery occlusion model in rats, and the extent of embolization was evaluated using quantitative, qualitative, and histopathological techniques after 14 days of implantation. RESULTS: The mean occlusion was significantly greater for the rhVEGF/aCHN-treated group (96.8 +/- 3.0%) than for the group receiving aCHN (74.7 +/- 5.6%) (p < 0.01). Through qualitative evaluation, intimal and medial proliferation were significantly greater with rhVEGF/aCHN than with aCHN and controls (p < 0.001). Degradation of the aCHN filler was monitored in concert with the production of extracellular matrix components. Macrophages migrated in and proliferated inside the occluded carotid artery lumens were identified by histological and immunostainings. Results showed resorption of chitosan with concurrent development of collagen and elastin into the vessel lumen, suggesting clot maturation into fibrosis. CONCLUSIONS: Chitosan with a bioactive agent such as rhVEGF showed excellent results in occluding aneurysms in a rat model.

Noninvasive and high-resolution optical monitoring of healing of diabetic dermal excisional wounds implanted with biodegradable in situ gelable hydrogels.

Closure of diabetic dermal chronic wounds remains a clinical challenge. Implant-assisted healing is emerging as a potential class of therapy for dermal wound closure; this advancement has not been paralleled by the development in complementary diagnostic techniques to objectively monitor the wound-healing process in conjunction with assessing/monitoring of implant efficacy. Biopsies provide the most objective morphological assessments of wound healing; however, they not only perpetuate the wound presence but also increase the risk of infection. A noninvasive and high-resolution imaging technique is highly desirable to provide objective longitudinal diagnosis of implant-assisted wound healing. We investigated the feasibility of deploying optical coherence tomography (OCT) for noninvasive monitoring of the healing of full-thickness excisional dermal wounds implanted with a novel in situ gelable hydrogel composed of N-carboxyethyl chitosan, oxidized dextran, and hyaluronan, in both normal and db/db mice. The results showed that OCT was able to differentiate the morphological differences (e.g., thickness of dermis) between normal and diabetic mice as validated by their corresponding histological evaluations (p < 0.05). OCT could detect essential morphological changes during wound healing, including re-epithelization, inflammatory response, and granulation tissue formation as well as impaired wound repair in diabetic mice. Importantly, by tracking specific morphological changes in hydrogel-assisted wound healing (e.g., implants' degradation and resorption, cell-mediated hydrogel degradation, and accelerated re-epithelization), OCT could also be deployed to monitor and evaluate the transformation of implanted biomaterials, thus holding the promise for noninvasive and objective monitoring of wound healing longitudinally and for objective efficacy assessment of implantable therapeutics in tissue engineering.

Cells and tissue interactions with glycated collagen and their relevance to delayed diabetic wound healing.

Dermal accumulation of advanced glycation end products (AGEs) has increasingly been implicated as the underlying cause of delayed diabetic wound healing. Devising an in vitro model to adequately mimic glycated tissues will facilitate investigation into the mechanism of glycation in conjunction with exploration of new approaches or improvement of current therapies for treating diabetic chronic wounds. Collagen matrices were artificially glycated and the presence of AGEs was demonstrated by immunostaining. Both the mechanical properties of the collagen matrices and their interactions with fibroblasts (morphology, attachment, proliferation, and migration) were altered after glycation, moreover, there was evidence of impairment on extracellular matrix (ECM) remodeling as well as inhibition of cell-induced material contraction. The actin cytoskeletons of the fibroblasts residing in the glycated collagen matrices were reorganized. In vivo mice full-thickness dermal wound models implanted with glycated collagen matrices showed delayed wound healing response. Thus, the glycated collagen matrix is an adequate in vitro model to mimic glycated tissues and could serve as a facile experimental tool to investigate the mechanism of glycation in conjunction with exploration of new approaches or improvement of current therapies for treating diabetic wounds.

In vitro and in vivo suppression of cellular activity by guanidinoethyl disulfide released from hydrogel microspheres composed of partially oxidized hyaluronan and gelatin.

This paper describes the preparation of oxidized hyaluronan crosslinked gelatin microspheres for drug delivery. Microspheres were prepared by a modified water-in-oil-emulsion crosslinking method, where three-dimensional crosslinked hydrogel microspheres formed in the absence of any extraneous crosslinker. SEM analyses of the microspheres showed rough surfaces in their dried state with an average diameter of 90 microm. Lyophilization of fully swollen microspheres revealed a highly porous structure. Guanidinoethyl disulfide (GED) was used as a model drug for incorporation into the microspheres; encapsulation of GED was confirmed by HPLC. There was an inverse correlation between the diameters of the microspheres with their GED loading. Macrophage was used as a model cell to evaluate the in vitro efficacy of GED release from the microspheres. The in vivo efficacy of the microspheres was further validated in a mouse full-thickness transcutaneous dermal wound model through suppression of cell infiltration.