Search

Objective: This study was conducted to evaluate the potential of a novel trifunctional methacrylate as a component of a photocurable composite resin with reduced curing shrinkage., Methods: Tris[4-(2'-hydroxy-3'-methacryloyloxypropoxy)phenyl]methane (TTEMA) was synthesized by reacting triphenylolmethane triglycidyl ether (TTE) with methacrylic acid in the presence of 4-(dimethylamino)pyridine. Photopolymerization reactivity and volumetric shrinkage of unfilled resins based on TTEMA were investigated by Fourier transform infrared spectroscopy and density measurements, respectively, and the results were compared with those for conventional dental monomers. A three-point bending test of the TTEMA-containing composite resin was carried out., Results: TTEMA was easily prepared in a good yield of 89%. Unfilled resins of TTEMA and bis-GMA, each containing 40% TEGDMA, showed similar photopolymerization reactivity. TTEMA exhibited a very low photopolymerization shrinkage of 2.09%, and 3:2 TTEMA-TEGDMA unfilled resin revealed 10% lower shrinkage than a conventional bis-GMA system containing the same amount of TEGDMA. The flexural strength of a light-activated composite resin formulated with TTEMA is comparable to that of a bis-GMA composite resin under the same conditions., Significance: TTEMA is promising for application as a photocurable dental monomer due to ease of synthesis, good polymerization reactivity, and relatively low curing shrinkage.

Transthyretin (TTR) is a plasma protein that transports thyroid hormone and retinol binding protein-vitamin A complex. Eighty-four variants of TTR have been identified and seventy-four are associated with familial amyloidotic polyneuropathy. Normal TTR is the major protein found in the fibrillar deposits in the heart at time of autopsy of individuals with senile systemic amyloidosis. The mechanism by which normally soluble TTR deposits as organ-damaging, insoluble, pathological fibrils late in life is unknown. Understanding the mechanism of fibrillogenesis of normal TTR is critical to the design of clinical treatments aimed at retardation, prevention, or reversal of fibril deposition. We have employed a biophysical approach to explore the hypothesis that an instability in a particular secondary or tertiary structure plays a role in the ability of normal TTR to form fibrils at physiological pH. Using far UV circular dichroic (CD) spectroscopy as a function of temperature we have identified simultaneous, cooperative, reversible structural changes in the beta-sheet and alpha-helical regions. The flexible short, surface-located loops undergo an irreversible conformational change at a lower temperature. Spectra before and after heating are different, particularly in the wavelength region associated with these loops, strongly suggesting that the major portion of TTR returns to its initial conformation while the loops do not. Near UV CD reveals partially reversible and irreversible changes in tertiary structure. Using calorimetry to directly measure the enthalpy associated with these changes, two peaks are observed, with further analysis suggesting conformational intermediates. Precipitates from heated samples reveal pre-fibrillar morphology by negative stain electron microscopy. These biophysical studies suggest that heat-induced conformational rearrangements enable normal TTR to assemble into pre-fibrils at physiological pH.

Although cardiac tamponade is a well-known complication of malignancy, it is uncommon as the initial manifestation. The antemortem diagnosis is difficult and distant metastasis is extremely rare. The presentations of primary pericardial mesothelioma are nonspecific. Pathologically, mesothelioma is the most common in primary tumors of the pericardium. Radical surgery can be used to treat a localized mesothelioma. However, the therapy for advanced primary pericardial mesothelioma is usually palliative because it is resistant to irradiation, and chemotherapy does not markedly improve the outcome. The prognosis is uniformly poor. The median survival from the onset of symptoms is 6 months. We present a 67-year-old woman with cardiac tamponade 4 months prior to a definitive diagnosis of primary pericardial mesothelioma. A computed tomogram confirmed multiple well-enhanced nodules in the pericardium, lungs and liver. Unfortunately, the patient died of multiple organ failure.