Faculty Bibliography

Selenium (Se) supplementation is reported to decrease the incidence and total mortality of cancer. Whereas in vitro and in vivo studies have shown a decrease in prostate, lung, and liver cancers, this has not been shown in thyroid cancer. ARO (anaplastic), NPA (BRAF positive papillary), WRO (BRAF negative papillary), and FRO (follicular) cells treated with 150 microM seleno-l-methionine (SM) were assessed for viability at 24, 48, and 72 h. Treated FRO cells were examined for cell cycle using flow cytometry, for apoptosis using terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay, and for gene expression using microarray. Genes identified as upregulated were confirmed by real-time PCR (RT-PCR) and proteins by Western blot analysis. SM treatment significantly decreased the proliferation of all cell lines. TUNEL assay showed no evidence of apoptosis, and flow cytometry showed a significant cell-cycle arrest in S (271% increase, P = 0.006) and G2/M (61% increase, P = 0.002) compared to control. Microarray revealed 21 differentially expressed genes with greater than twofold change. A relative overexpression of growth arrest and DNA damage inducible (GADD)34 and GADD153 in treated cells was confirmed with RT-PCR and Western blot. SM inhibits thyroid cancer cell proliferation through a time dependent upregulation of the GADD family of genes and arrest in S and G2/M phases of the cell cycle. This is the first report of selenium induced inhibition of thyroid cancer cell growth.

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.

Purpose: Cutaneous radiation injury occurs during the treatment of cancer, or in rare environmental exposure. As the acute wound heals, fibrosis is induced and extracellular matrix (ECM) is deposited. The fibrotic pathway is mediated by the transforming growth factor-beta (TGF-beta) cascade, and is dependent on Smad3, a transcription factor for ECM. We characterized gene expression of this cascade after radiation injury and performed in vitro and in vivo gene silencing of Smad3 in an attempt to reverse the fibrotic pathway. Methods: Wild-type murine dermal fibroblasts were irradiated with 20Gy and harvested at serial time-points. RT-PCR was performed for known regulators and mediators of fibrosis. Smad3 was silenced by transfection with siRNA. For the in vivo experiment, dorsal skin of wild-type mice was irradiated with 45 Gy. Five weeks later, siRNA was applied to the fibrotic areas for one week. Skin was harvested and tissue analyzed by RT-PCR and Western blotting, as well as tissue tensiometry, which quantitatively measures rigidity. Results: Following irradiation, there was a steady increase in mRNA expression of Smad3, TGFbeta, and ECM genes collagen 1A1, metalloprotease2, and tissue inhibitor of metalloprotease-1, with peak expression at 12-24 hours. Inhibition of Smad3 with siRNA significantly decreased expression of Smad3, TGFbeta, and ECM genes. In the mouse model, topical treatment with siRNA again significantly decreased expression of these genes. Tensiometry demonstrated decreased stiffness in Smad3 siRNA treated skin, with a Young's modulus nearer to normalcompared to untreated and nonsense siRNA treated skin. Conclusion: Following initiation of the fibrotic pathway by radiation, Smad3 siRNA treatment both in vitro and in vivo effectively reversed gene expression. Furthermore, cutaneous Smad3 inhibition mitigated radiation-induced fibrotic stiffening. These findings suggest a therapeutic role for Smad3 silencing for cancer patients treated with radiation as well as those accidentally exposed to radiation

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