Properties of dental resins submitted to pH catalysed hydrolysis

Objectives

This study evaluated the surface microhardness (SM) and roughness (SR) alterations of dental resins submitted to pH catalysed degradation regimens.

Methods

Thirty discs of each TPH Spectrum (Dentsply), Z100 (3M-ESPE), or an unfilled experimental bis-GMA/TEGDMA resin were fabricated, totaling 90 specimens. Each specimen was polymerized for 40 s, finished, polished, and individually stored in deionized water at 37 °C for 7 days. Specimens were randomly assigned to the following pH solutions: 1.0, 6.9 or 13, and for SM or SR evaluations (n = 5). Baseline Knoop-hardness of each specimen was obtained by the arithmetic mean of five random micro-indentations. For SR, mean baseline values were obtained by five random surface tracings (R_a). Specimens were then soaked in one of the following storage media at 37 °C: (1) 0.1 M, pH 1.0 HCl, (2) 0.1 N, pH 13.0 NaOCl, and (3) deionized water (pH 6.9). Solutions were replaced daily. Repeated SM and SR measurements were performed at the 3-, 7- and 14-day storage time intervals. For each test and resin, data were analysed by two-way ANOVA followed by Tukey's test (α = 0.05).

Results

There was significant decrease in SM and increase in SR values of composites after storage in alkaline medium. TPH and Z100 presented similar behaviour for SM and SR after immersion in the different media, whereas unfilled resin values showed no significant change.

Conclusion

Hydrolytic degradation of resin composites seems to begin with the silanized inorganic particles and therefore depend on their composition.

Significance

To accelerate composite hydrolysis and produce quick in vitro microstructural damage, alkaline medium appears to be more suitable than acidic medium. Contemporary resin composite properties seem to withstand neutral and acidic oral environments tolerably well.     

Hippo signaling: bridging the gap between cancer and neurodegenerative disorders

During development, regulation of organ size requires a balance between cell proliferation, growth and cell death. Dysregulation of these fundamental processes can cause a variety of diseases. Excessive cell proliferation results in cancer whereas excessive cell death results in neurodegenerative disorders. Many signaling pathways known-to-date have a role in growth regulation. Among them, evolutionarily conserved Hippo signaling pathway is unique as it controls both cell proliferation and cell death by a variety of mechanisms during organ sculpture and development. Neurodegeneration, a complex process of progressive death of neuronal population, results in fatal disorders with no available cure to date. During normal development, cell death is required for sculpting of an organ. However, aberrant cell death in neuronal cell population can result in neurodegenerative disorders. Hippo pathway has gathered major attention for its role in growth regulation and cancer, however, other functions like its role in neurodegeneration are also emerging rapidly. This review highlights the role of Hippo signaling in cell death and neurodegenerative diseases and provide the information on the chemical inhibitors employed to block Hippo pathway. Understanding Hippo mediated cell death mechanisms will aid in development of reliable and effective therapeutic strategies in future.     

The diagnostic accuracy and strength of agreement between endoscopic ultrasound and histopathology in the staging of ampullary tumors

Aim

Ampullary tumors are rare. Reports on ampullary tumor staging are heterogeneous and combine both periampullary and ampullary tumors. This study assessed the performance of endoscopic ultrasound (EUS) in the local staging of ampullary tumors only.

Methods

Data were collected retrospectively. We included patients with an ampullary tumor who underwent EUS and surgical resection. Tumor (T) and nodal (N) TNM staging for EUS and histopathological (HP) staging were compared.

Results

From 2009 to 2010, a total of 79 patients with ampullary tumors were identified. Of these, 26 had both EUS and Whipple??s surgery and were included (28 did not undergo resection, 13 had palliative surgery only and 12 had resection without EUS). For T staging by HP, there were 2 (7.7?%) T1, 11 (42.3?%) T2, 12 (46.2?%) T3 and 1 (3.8?%) T4 tumors. The accuracy of EUS T staging was 73.1?% with a Kappa value of 0.564 (p?<?0.0001). The sensitivity, specificity, positive predictive value (PPV), negative predictive values (NPV) of EUS, respectively were 50.0?%, 91.7?%, 33.3?% and 95.7?% for T1 tumors; 81.8?%, 80.0?%, 75.0?% and 85.7?% for T2; 75.0?%, 92.9?%, 90.0?% and 81.3?% for T3 tumors. For N staging by HP, 17 (65.4?%) were N0 and 9 (34.6?%) N1. The N staging diagnostic accuracy was 80.8?% with a Kappa value of 0.586 (p?=?0.003). The sensitivity, specificity, PPV, NPV for N0 disease were 82.4?%, 77.8?%, 87.5?% and 70.0?%, respectively while for N1 they were 77.8?%, 82.4?%, 70.0?% and 87.5?%, respectively.

Conclusions

EUS had a moderate strength of agreement with histopathology for both T and N staging, and a high diagnostic accuracy for nodal staging.     

HER2 expression in gastric cancer in Indian population—An immunohistochemistry and fluorescence in situ hybridization study

Aim

Human epidermal growth factor receptor (HER2, also known neu, ERBB2) protein expression in gastric cancer is associated with poor prognosis, aggressive disease and poor response to chemotherapy. Trastuzumab, a monoclonal antibody against HER2, in combination with chemotherapy is currently advocated as a new standard option for patients with HER2-positive advanced gastric and gastroesophageal junction carcinoma. Frequency of HER2 expression in gastric cancer has been reported from different geographic zones with a wide range of 13?% to 91?%. There are no reported data of HER2 protein expression in gastric cancer tissue from India. The purpose of this study was to evaluate the frequency of HER2 expression in gastric cancer.

Methods

The frequency of HER2 expression in 52 patients with gastric adenocarcinoma was prospectively evaluated over a six month period at Asian Institute of Gastroenterology from January 2010 to July 2010, using immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH).

Results

HER2 overexpression was confirmed in 23 of 52 (44.2?%) patients. Two patients had equivocal result by IHC (2+), one of whom was positive on analysis by FISH. There was no difference in HER2 overexpression (positivity) or negativity in relation to age, gender, tumor site, histological subtype, tumor differentiation, serosal involvement or lymph nodal status. HER2 overexpression rates were similar for intestinal type as compared to diffuse histological type (OR 1.84), as also for proximal as compared to distal gastric cancers (OR 0.81).

Conclusion

HER2 overexpression was observed in significant number of advanced gastric adenocarcinoma patients. There was no difference in HER2 overexpression in relation to clinicopathological parameters.