Assessing undergraduate medical education through a generalist lens.

PROBLEM BEING ADDRESSED: Medical schools aim to integrate the values of generalism into their undergraduate programs. However, currently no program has been described to measure the degree to which formal curricular materials represent generalist principles. OBJECTIVE OF PROGRAM: To quantify the generalism principles present in undergraduate medical education learning materials and to provide recommendations to enhance generalism content. PROGRAM DESCRIPTION: A review of the literature and accreditation documents was conducted to identify key elements of medical generalism. An evidence-informed tool, the Toronto Generalism Assessment Tool, was developed and applied to the new preclerkship undergraduate cases at the University of Toronto in Ontario. The findings regarding the presence of generalism principles and recommendations to enhance generalism content were provided to case developers. The recommendations were valued and were incorporated into subsequent iterations of the cases. CONCLUSION: This is the first report of a successful evidence-informed program to assess the degree of generalism reflected in undergraduate medical education curricular documents. This program can be used by other institutions wishing to review their curricula through a generalist lens.

Incorporation of osteopontin peptide into kidney stone-related calcium oxalate monohydrate crystals: a quantitative study.

Polyelectrolyte-crystal interactions regulate many aspects of biomineralization, including the shape, phase, and aggregation of crystals. Here, we quantitatively investigate the role of phosphorylation in interactions with calcium oxalate monohydrate crystals (COM), using synthetic peptides corresponding to the sequence 220-235 in osteopontin, a major inhibitor of kidney stone-related COM formation. COM formation is induced in the absence or presence of fluorescent-labeled peptides containing either no (P0), one (P1) or three (P3) phosphates and their adsorption to and incorporation into crystals determined using quantitative fluorimetry (also to determine maximum adsorption/incorporation), confocal/scanning electron microscopy and X-ray/Raman spectroscopy. Results demonstrate that higher phosphorylated peptides show stronger irreversible adsorption to COM crystals (P3: K0 ~ 66.4 × 106 M-1; P1: K0 ~ 29.4 × 106 M-1) and higher rates of peptide incorporation into crystals (maximum: P3: ~ 58.8 ng and P1: ~ 8.9 ng per µg of COM) than peptides containing less phosphate groups. However, crystals grown at that level of incorporable P3 show crystal-cleavage. Therefore, extrapolation of maximum incorporable P3 was carried out for crystals that are still intact, resulting in ~ 49.1 ng P3 µg-1 COM (or ~ 4.70 wt%). Both processes, adsorption and incorporation, proceed via the crystal faces {100} > {121} > {010} (from strongest to weakest), with X-ray and Raman spectroscopy indicating no significant effect on the crystal structure. This suggests a process in which the peptide is surrounded by growing crystal matrix and then incorporated. In general, knowing the quantity of impurities in crystalline/ceramic matrices (e.g., kidney stones) provides more control over stress/strain or solubilities, and helps to categorize such composites.

Osteopontin mediates mineralization and not osteogenic cell development in vitro.

Biomineralization is a complex process in the development of mineralized tissues such as bone and pathological calcifications such as atherosclerotic plaques, kidney stones and gout. Osteopontin (OPN), an anionic phosphoprotein, is expressed in mineralizing tissues and has previously been demonstrated to be a potent inhibitor of hydroxyapatite formation. The OPN-deficient (Opn-/-) mouse displays a hypermineralized bone phenotype starting at 12 weeks postnatally. By isolating and culturing Opn-/- and wild-type (WT) osteoblasts, we sought to determine the role of OPN and two of its functional peptides in osteoblast development and mineralization. Opn-/- osteoblasts had significantly increased mineral deposition relative to their WT counterparts, with no physiologically relevant change in gene expression of osteogenic markers. Supplementation with bovine milk OPN (mOPN) led to a dramatic reduction in mineral deposition by the Opn-/- osteoblasts. Treatment with OPN-derived peptides corresponding to phosphorylated OPN-(220-235) (P3) and non-phosphorylated OPN-(65-80) (OPAR) also rescued the hypermineralization phenotype of Opn-/- osteogenic cultures. Supplementation with mOPN or the OPN-derived peptides did not alter the expression of terminal osteogenic markers. These data suggest that OPN plays an important role in the regulation of biomineralization, but that OPN does not appear to affect osteoblast cell development in vitro.

Peptides of Matrix Gla protein inhibit nucleation and growth of hydroxyapatite and calcium oxalate monohydrate crystals.

Matrix Gla protein (MGP) is a phosphorylated and γ-carboxylated protein that has been shown to prevent the deposition of hydroxyapatite crystals in the walls of blood vessels. MGP is also expressed in kidney and may inhibit the formation of kidney stones, which mainly consist of another crystalline phase, calcium oxalate monohydrate. To determine the mechanism by which MGP prevents soft-tissue calcification, we have synthesized peptides corresponding to the phosphorylated and γ-carboxylated sequences of human MGP in both post-translationally modified and non-modified forms. The effects of these peptides on hydroxyapatite formation and calcium oxalate crystallization were quantified using dynamic light scattering and scanning electron microscopy, respectively. Peptides YGlapS (MGP1-14: YγEpSHEpSMEpSYELNP), YEpS (YEpSHEpSMEpSYELNP), YGlaS (YγESHESMESYELNP) and SK-Gla (MGP43-56: SKPVHγELNRγEACDD) inhibited formation of hydroxyapatite in order of potency YGlapS > YEpS > YGlaS > SK-Gla. The effects of YGlapS, YEpS and YGlaS on hydroxyapatite formation were on both crystal nucleation and growth; the effect of SK-Gla was on nucleation. YGlapS and YEpS significantly inhibited the growth of calcium oxalate monohydrate crystals, while simultaneously promoting the formation of calcium oxalate dihydrate. The effects of these phosphopeptides on calcium oxalate monohydrate formation were on growth of crystals rather than nucleation. We have shown that the use of dynamic light scattering allows inhibitors of hydroxyapatite nucleation and growth to be distinguished. We have also demonstrated for the first time that MGP peptides inhibit the formation of calcium oxalate monohydrate. Based on the latter finding, we propose that MGP function not only to prevent blood-vessel calcification but also to inhibit stone formation in kidney.