Online professional development across institutions and borders.

Professional development (PD) is a key element for enhancing the quality of academic teaching. An increasing number of PD activities have moved to blended and online formats, especially since the COVID-19 pandemic. Due to the desire, potential, and need for collaboration among educators to learn from innovative and best practices, several institutions have started to pool their resources and expertise together and have started to implement cross-institutional and cross-national online professional development (OPD). The questions of what type of a (cross-)institutional OPD educators might prefer, and whether educators learn effectively from (and with) peers in such cross-cultural context have not been adequately explored empirically. In this case-study across three European countries, we explored the lived experiences of 86 educators as a result of a cross-institutional OPD. Using a mixed methods design approach our pre-post findings indicated that, on average, participants made substantial gains in knowledge. In addition, several cultural differences were evident in the expectations and lived experiences in ODP, as well as the intention to transfer what had been learned into one's own practice of action. This study indicates that while substantial economic and pedagogical affordances are provided with cross-institutional OPD, cultural differences in context might impact the extent to which educators implement lessons learned from OPD.

Investigation of magnetically driven passage of magnetic nanoparticles through eye tissues for magnetic drug targeting.

This paper elucidates the feasibility of magnetic drug targeting to the eye by using magnetic nanoparticles (MNPs) to which pharmaceutical drugs can be linked. Numerical simulations revealed that a magnetic field gradient of 20 T m-1 seems to be promising for dragging magnetic multicore nanoparticles of about 50 nm into the eye. Thus, a targeting magnet system made of superconducting magnets with a magnetic field gradient at the eye of about 20 T m-1 was simulated. For the proof-of-concept tissue experiments presented here the required magnetic field gradient of 20 T m-1 was realized by a permanent magnet array. MNPs with an optimized multicore structure were selected for this application by evaluating their stability against agglomeration of MNPs with different coatings in water for injections, physiological sodium chloride solution and biological media such as artificial tear fluid. From these investigations, starch turned out to be the most promising coating material because of its stability in saline fluids due to its steric stabilization mechanism. To evaluate the passage of MNPs through the sclera and cornea of the eye tissues of domestic pigs (Sus scrofa domesticus), a three-dimensionally printed setup consisting of two chambers (reservoir and target chamber) separated by the eye tissue was developed. With the permanent magnet array emulating the magnetic field gradient of the superconducting setup, experiments on magnetically driven transport of the MNPs from the reservoir chamber into the target chamber via the tissue were performed. The resulting concentration of MNPs in the target chamber was determined by means of quantitative magnetic particle spectroscopy. It was found that none of the tested particles passed the cornea, but starch-coated particles could pass the sclera at a rate of about 5 ng mm-2 within 24 h. These results open the door for future magnetic drug targeting to the eye.

In vitro effects of benzalkonium chloride and prostaglandins on human meibomian gland epithelial cells.

PURPOSE: Benzalkonium chloride is the most widely used preservative in ophthalmic topical solutions. The aim of this study was to investigate the influence of BAC as a single substance or as a component of several commercially available ophthalmic solutions on meibomian gland epithelial cells in vitro. MATERIALS AND METHODS: An immortalized human meibomian gland epithelial cell line (HMGEC) was used and cells were cultured in the absence or presence of fetal bovine serum to assess cell morphology, cell proliferation, cell viability (MTS assay) and impedance sensing (ECIS) after stimulation with BAC. Further, the viability of HMGECs stimulated with BAC-containing and BAC-free bimatoprost, travoprost and latanoprost was evaluated using the MTS assay. Real-time PCR analysis for hyperkeratinization associated genes (cornulin, involucrin) was performed. RESULTS: In the absence of serum, the proliferation rate of HMGECs decreased starting with 0.1µg/ml BAC. At concentrations of 50µg/ml BAC and higher, cell viability was reduced after 10min exposure with a corresponding change in cell morphology. Toxicity of BAC-containing ophthalmic solutions was greater than that of BAC alone, whereas BAC-free alternative products did not significantly influence cell viability. Confluence, cell-cell contacts and serum-containing medium appeared to facilitate HMGECs survival. Expression rate of involucrin and cornulin declined after exposure to preserved bimatoprost and BAC. CONCLUSIONS: BAC showed cytotoxic effects on HMGECs starting with a concentration of 0.1µg/ml. The combination of BAC and prostaglandin-analogs might have a synergistic effect which results in higher toxicity than BAC alone. Unpreserved eye drops and eye drops preserved with Polyquaternium-1 are less damaging to HMGECs.

Design of a randomized controlled double-blind crossover clinical trial to assess the effects of saliva substitutes on bovine enamel and dentin in situ.

BACKGROUND: Hyposalivation is caused by various syndromes, diabetes, drugs, inflammation, infection, or radiotherapy of the salivary glands. Patients with hyposalivation often show an increased caries incidence. Moreover, hyposalivation is frequently accompanied by oral discomfort and impaired oral functions, and saliva substitutes are widely used to alleviate oral symptoms. However, preference of saliva substitutes due to taste, handling, and relief of oral symptoms has been discussed controversially. Some of the marketed products have shown demineralizing effects on dental hard tissues in vitro. This demineralizing potential is attributed to the undersaturation with respect to calcium phosphates. Therefore, it is important to modify the mineralizing potential of saliva substitutes to prevent carious lesions. Thus, the aim of the present study was to evaluate the effects of a possible remineralizing saliva substitute (SN; modified Saliva natura) compared to a demineralizing one (G; Glandosane) on mineral parameters of sound bovine dentin and enamel as well as on artificially demineralized enamel specimens in situ. Moreover, oral well-being after use of each saliva substitute was recorded. METHODS/DESIGN: Using a randomized, double-blind, crossover, phase II/III in situ trial, volunteers with hyposalivation utilize removable dentures containing bovine specimens during the experimental period. The volunteers are divided into two groups, and are required to apply both saliva substitutes for seven weeks each. After both test periods, differences in mineral loss and lesion depth between values before and after exposure are evaluated based on microradiographs. The oral well-being of the volunteers before and after therapy is determined using questionnaires. With respect to the microradiographic analysis, equal mineral losses and lesion depths of enamel and dentin specimens during treatment with SN and G, and no differences in patients' experienced oral comfort after SN compared to G usage are expected (H0). DISCUSSION: Up to now, 14 patients have been included in the study, and no reasons for early termination of the trial have been identified. The design seems suitable for determining the effects of saliva substitutes on dental hard tissues in situ, and should provide detailed information on the oral well-being after use of different saliva substitutes in patients with hyposalivation. TRIAL REGISTRATION: ClinicalTrials.gov ID. NCT01165970.

Virtual microscopy-The future of teaching histology in the medical curriculum?

Conventional continuing education in microscopic anatomy, histopathology, hematology and microbiology has hitherto been carried out using numerous sets of sectioned tissue specimens in a microscopy laboratory. In comparison, after digitalization of the sections it would be possible to access teaching specimens via virtual microscopy and the internet at any time and place. This would make it possible to put innumerable new learning scenarios into practice. The present article elucidates the advantages of virtual microscopy in histology instruction and presents a concept of how virtual microscopy could be introduced into the teaching of microscopic anatomy in several steps. Initially, the presently existing microscopic teaching specimens would be digitalized and made available on-line without restriction. In a second step, instruction would be shifted to an emphasis on virtual microscopy, utilizing all of the advantages offered by the technique. In a third step, the microscopic contents could be networked with other anatomical, radiological and clinical content on-line, thus opening new learning perspectives for students of human and dental medicine as well as those of medically related courses of study. The advantages and disadvantages of such a concept as well as some possibly arising consequences are discussed in the following.

Ultrastructural and biochemical evaluation of the porcine anterior chamber perfusion model.

PURPOSE: To evaluate a porcine anterior chamber perfusion model and to test the transferability of data obtained with this model to the human system. METHODS: Porcine eyes were obtained from a local abattoir and processed within 2 hours after death. Anterior chambers of 42 pairs of eyes were dissected with removal of lens, vitreous, iris, and ciliary processes and perfused for 72 (40 pairs) or 140 (2 pairs) hours with medium or medium supplemented with 10 ng/mL transforming growth factor (TGF)-beta2. Facility was continuously measured. Afterward, trabecular meshwork (TM) specimens from all quadrants were prepared, and sections were analyzed morphologically and with immunohistochemical methods. TM sections of 10 nonperfused pairs of eyes were used as the control. RNA and protein was extracted from the TM specimens. Expression of alphaB-crystallin, fibronectin (FN), plasminogen activator inhibitor (PAI)-1, thrombospondin (TSP)-1, and connective tissue growth factor (CTGF) mRNA and protein in medium-perfused and TGF-beta2-perfused anterior segments was examined by Northern and Western blot analyses. RESULTS: The nonperfused TM showed prominent differences between the temporal and nasal quadrants. Temporally, the ciliary muscle (CM) was pronounced, the scleral sulcus was long and flat, and the scleral spur extended toward the iris root. Nasally, the CM was thin, the sulcus deep, and the spur compact. The outer TM was expanded between the scleral spur and cornea throughout the entire circumference. On the ultrastructural level, the elastic network was connected to the cribriform TM cells and the aqueous plexus endothelium. Perfusion itself had only small effects on the morphology of the outer TM. Aqueous plexus loops remained open, and TM cells showed no signs of necrosis or pyknosis. alphaB-crystallin expression was significantly increased in perfused eyes. Perfusion with TGF-beta2 for 72 hours reduced outflow facility to approximately 60% of that of the medium-perfused control. TM cells adjacent to putative drainage pathways showed enlarged cisterns of rough endoplasmic reticulum (rER), a sign of active protein synthesis. Expression of alphaB-crystallin and FN mRNA were elevated by factors of 5 and 3, respectively. The proteins were upregulated by a factor of 2.5. In addition, TGF-beta2 upregulated PAI-1 (1.7-fold) and TSP-1 (1.6-fold) proteins, two factors shown to be TGF-beta2 responsive in human TM cell culture experiments. CTGF expression was not altered. CONCLUSIONS: These new ultrastructural investigations indicate that the cribriform and subendothelial regions of the porcine TM have an architecture similar to that of the primate TM. The biochemical and physiological response to TGF-beta2 was identical with that described in human TM cell culture and anterior chamber perfusion. The porcine anterior chamber perfusion model is valid for the human system.

Effects of TGF-beta2 in perfused human eyes.

PURPOSE: TGF-beta2 is known to be present at elevated levels in the aqueous humor of patients with primary open-angle glaucoma (POAG). Studies have shown that TGF-beta2 influences cultured trabecular meshwork (TM) cells, but the effects of this cytokine on intact TM and outflow facility have not been studied. The purpose of this study was to investigate whether TGF-beta2 treatment induces changes in outflow facility and morphologic changes in the TM tissue and whether these changes are comparable to those previously recorded in glaucomatous eyes. METHODS: Baseline facility was measured in paired human eyes (n = 8 pairs), with a constant-flow anterior segment culture system. Medium perfusing experimental eyes was then supplemented with activated human recombinant TGF-beta2 (3.0 ng/mL, comparable to or slightly greater than measured aqueous humor levels in patients with POAG), and facility was measured for at least 8 days. At the conclusion of the perfusion, eyes were fixed and processed for light microscopy, transmission electron microscopy, and immunolabeling studies. RESULTS: TGF-beta2 perfusion reduced outflow facility by 27% (P = 0.03) and promoted focal accumulation of fine fibrillar extracellular material in multilayered structures under the inner wall of Schlemm's canal. In treated eyes, Schlemm's canal was 27% shorter (P = 0.02), and the length of the inner wall apparently available for fluid flow was 33% less (P = 0.001), both compared with paired control eyes. CONCLUSIONS: TGF-beta2 reduces outflow facility when perfused into cultured human anterior segments. Furthermore, TGF-beta2 affects the extracellular matrix of the trabecular meshwork in a manner that is consistent with the observed reduction in outflow facility. Although the distribution of accumulated fibrillar material was different in these perfused eyes than that in POAG, the difference could be due to variation in biomechanical environment for TM cells in cultured anterior segments compared with the living eye. Overall, these results support the hypothesis that elevated TGF-beta2 levels in the aqueous humor play a role in the pathogenesis of the ocular hypertension in POAG.