Appraisal of the PathoDiscovery: an interactive web-based educational tool for teaching pathophysiology and histopathology.

Virtual pathology education has shown to enhance the students' learning experience. At the Radboud University, an E-learning platform-called the "PathoDiscovery"-was developed and first used in a course about neoplasm development amongst first year (bio)medical sciences students. The PathoDiscovery incorporates high-power microscopic images, histological annotations, interactive questions and pre-programmed feedback.The objective of our study was to develop and evaluate the PathoDiscovery within the "Neoplasm" course focusing on student perceptions of usability and utility. For this study the online feedback on the PathoDiscovery that was obtained anonymously from (bio)medical students over two consecutive academic years was analyzed. The responses of the first year were used to make improvements. After the second year, the feedback of the two academic years was compared. The rating of the E-learning increased from 6.8 (n = 285) to 7.4 (n = 247) after implementation of feedback obtained in the first year. The students judged the structure as logical (90%). The content was considered easy or just right (57%), matched the learning objectives (76%), and contributed to knowledge development (78%). We conclude that the first experiences with the PathoDiscovery are positive for both students and lecturers; it is an example of a dynamic online learning tool that is easily adaptable and is well suited for a blended learning approach.

Intestinal involvement in amyloidosis is a sequential process.

BACKGROUND: Gastrointestinal amyloidosis causes dysmotility. A comprehensive histological analysis to explain these symptoms is lacking. Therefore, we systematically examined histological features of intestinal dysmotility in patients with AL and AA amyloidosis, compared to controls. METHODS: Autopsy tissue material from small bowel and colon was used for histological (semiquantitative) evaluation of the mucosa, blood vessels, muscular layers, enteric nervous system (ENS) and the interstitial cells of Cajal (ICC), using hematoxylin and eosin, periodic acid Schiff, Elastic von Gieson and Congo red staining, and immunohistochemistry with α-smooth muscle actin, HuC/D, S100 and CD117 antibodies, according to guidelines of the Gastro 2009 International Working Group. KEY RESULTS: Amyloid deposits were present in the vascular walls of all amyloidosis patients. In the mucosa, amyloid was found in 67% of AA patients. The muscular layers were involved in 64% of amyloidosis patients, most prominent in AA patients, associated with the presence of polyglucosan inclusion bodies, but not with either abnormal α-actin patterns or fibrosis. Amyloid in the muscularis propria surrounding the myenteric plexus was found, but not inside the myenteric plexus. These deposits might be related to loss of the ICC network, but there was no association with decreased neuronal or nerve fiber density. CONCLUSIONS & INFERENCES: We hypothesize that intestinal dysmotility in amyloidosis patients is a sequential process: amyloid deposition starts in the vasculature, followed by involvement of the muscular layers, ICC loss, and potentially affect the myenteric plexus. This final stage may be accompanied by clinical symptoms of severe intestinal dysmotility.

The enteric nervous system and the musculature of the colon are altered in patients with spina bifida and spinal cord injury.

Neurogenic bowel dysfunction occurs in a large percentage of adult patients with spina bifida (SB) and spinal cord injury (SCI), significantly affecting their quality of life. Although bowel motility is autonomously regulated by the enteric nervous system (ENS), disruption of the modulation of the ENS by extrinsic innervation as present in many patients with SB and SCI might lead to motility disorders. In order to gain insight in the pathophysiology, we studied histological changes of the neuromuscular structures in the colon of SB and SCI patients. Archival colon tissue blocks from SB (n = 13) and SCI (n = 34) patients were collected nationwide in The Netherlands and compared with control samples (n = 16). Histological (semiquantitative) evaluation of the ENS, the network of interstitial cells of Cajal (ICC), and the muscularis propria was performed using hematoxylin and eosin, periodic acid Schiff, and elastic von Gieson staining, and immunohistochemistry with antibodies against HuC/D, calretinin, S100, CD117, α-smooth muscle actin, and desmin. Compared to controls, SB and SCI patients showed neuronal loss and decreased nerve fiber density in the myenteric plexus. Lower nerve fiber density was significantly more often found in patients with severe bowel dysfunction. Other major findings were loss of ICCs around the myenteric plexus and fibrosis in the longitudinal muscle layer. Altered histology of the ENS may explain abnormal intestinal motility in SB and SCI patients. Furthermore, loss of myenteric nerve fibers (including enteric glial cells) may play a major role in the development of severe motility complaints.