Faculty Bibliography

We previously reported that topically applied calreticulin (CRT), a calcium-binding ER chaperone protein comprising N, P, and C domains, markedly enhances diabetic murine (db/db) and porcine cutaneous wound healing. Consistent with the potent wound healing effects, we further showed, in vitro, that exogenous CRT stimulated proliferation of keratinocytes and fibroblasts, induced concentration-dependent migration of these cells and monocytes and macrophages, and upregulated protein expression of collagen, fibronectin, and TGF-beta-3 in fibroblasts. Notably, all these broad-ranging effects purport novel non-ER functions for CRT that act from outside the cell inward. The current studies address: 1) whether the ER chaperone function of CRT is required for its extracellular functions, 2) the molecular structure(s) of CRT that function in its biological activities and 3) the in vitro effects of CRT on diabetic compared to normal mouse and human fibroblasts. Using CRT null mouse embryo fibroblasts (K42) compared to wild type (K41) in proliferation and migration assays (scratch plate and chamber), we show that exogenous CRT stimulates proliferation of null K42 cells to a similar extent as K41 cells (2-fold at 10 pg/ml). However, K42 cells require 100 times more CRT for a peak migratory response (1 vs 100 ng/ml), with a 20% decreased response. We also show that the C domain stimulates fibroblast proliferation to the same extent and peak response as the entire molecule. Finally, we show that fibroblasts isolated from db/db mouse skin and human fibroblasts cultured in high glucose, to simulate type II diabetes, respond to CRT by migration and proliferation albeit with 1/3 less robust response requiring 10-fold more CRT for peak responses compared to controls. The breath of novel non-ER functions of CRT, structure-function relationships, and effects on diabetic cells in vitro underscore this molecule as a potential potent agent for the topical treatment for healing diabetic wounds

Summary form only given. This study aims to evaluate the potential of atmospheric pressure non-thermal plasma technology (NPT) to enhance the adhesive bond strength on normative dentin substrates. Two different microplasma jets were used in our experiments, a direct-current driven microhollow cathode discharge jet operated in air and a rf-driven jet operated in Ar. Other gas mixtures, e.g. He/O2 are also being explored.Initial experiments were carried out using fresh, non-carious third molars obtained under a protocol approved by the New York University College of Medicine Institutional Review Board. The occlusal enamel of each tooth was removed perpendicular to the long axis of the tooth to expose a flat dentin surface, which was subsequently polished. The specimens were randomly assigned to 3 groups for bonding and NPT applications. For the control group, three teeth were etched with phosphoric acid etched, the dentin bonding agent (DBA) was applied and the teeth were restored with a 4 mm thick resin composite. Another group of 3 teeth was treated with an Ar plasma and a third group was exposed to an air plasma. For the plasma-treated groups, the dentin substrates were etched for 15 s, rinsed for 10s and treated by the plasma for 20 s followed by DBA application and resin composite placement. All specimens were stored in water for 24 h prior to a microtensile bonding test. Preliminary data indicate that the bond strength values were not significantly affected by the Ar or air plasma treatment. We observed that teeth treated with the Ar plasma exhibited an enhanced premature failure rate (-50%) during the cutting or specimen mounting phases. This was not observed for the control or for the air plasma treated groups. Extensive surface characterization studies using various microscopy techniques, XPS, and micro-Raman are underway to assess the effect of the plasma on the surface. Optical emission spectroscopy is used to monitor the presence of reactive spe- - cies (eg. OH, O) in the plasma for various operating conditions and feed gases or gas mixtures. The results of these studies will be presented and discussed in detail at the Conference

Calcium phosphate-based bioactive ceramics in various physical and chemical formulations have been extensively utilized as biomaterials for bone regeneration/conduction. However, the determination of their in vivo temporal behavior from the short to long term in humans has been a challenge due to the lack of physical reference for morphologic and morphometric evaluation. The present study evaluated bone morphology and morphometry (bone-to-implant contact [BIC]) around plasma-sprayed hydroxyapatite (PSHA)-coated endosseous implants that were retrieved due to prosthetic reasons while successfully in function at the posterior region of the jaws from as early as 2 months to approximately 13 years after a 6-month healing period after placement. Bone morphology was evaluated by light microscopy, and BIC was determined using computer software. Irrespective of the time in vivo, lamellar bone was observed in close contact with the implant PSHA-coated surface and between plateaus. BIC ranged from approximately 35-95%, was highly directional, and Haversian-like osteonic morphology between plateaus was observed for most implants. The PSHA coating was present with little variation in thickness between the samples retrieved regardless of time in vivo.