An In Vitro Study to Compare the Effect of Two Etching Techniques on the Tensile Bond Strength of Resin Cement Bonded to Base Metal Alloy and Enamel

Resin-bonded retainers are being preferred for anterior restorations. To increase the retentive strength of the metal fixed to the tooth, the retainer surface has to be etched. Different etching techniques are described in the literature with different researchers expressing the superiority of one technique over the other. This study was conducted to compare electro chemical and chemical etching techniques and the mode of bond failure. Twenty human maxillary premolars with the crown portion separated from root were embedded in resin block such that mesial or distal portion of it was exposed on the top of the block. 4 × 5 mm area was marked on the tooth, and wax pattern was prepared to cover the exact area, with the opposite end having a hook like structure which was later attached to universal testing machine. Wiron99 Ni–Cr alloy was used for casting. Once the casting and etching procedures were finished, wax patterns were invested, casted and half the samples were etched chemically using Aqua-regia and the other half samples were etched electrochemically. The castings were cleaned and cemented to tooth structure using Rely-X ARC (3 M ESPE, USA) resin cement. Specimens were fixed to universal testing machine and de-bonded. The load required to de-bond and mode of de-bonding was noted. Results were subjected to five different statistical tests, each test specific to the variable being tested. The mean failure load was calculated as 5.95 kg for electrochemically etched samples and that of chemically etched samples was calculated as 11.15 kg. The standard deviation of the force required to debond the specimens (Kgf) was calculated and found to be 0.65 for electrochemically etched samples and 1.11 for chemically etched samples. The following conclusions have been drawn from the study. 1. Chemical etching of the samples created better retentive surfaces than electrochemical etching. 2. The results of mode of de-bonding show that in case of chemical etching maximum debonding occurred at resin-enamel interface and in electrochemical type it occurred at resin-metal interface.     

Influence of ferulic acid on gamma-radiation induced DNA damage, lipid peroxidation and antioxidant status in primary culture of isolated rat hepatocytes

Ionizing radiation is known to induce oxidative stress through generation of reactive oxygen species (ROS) resulting in imbalance of the pro-oxidant and antioxidant activities ultimately resulting in cell death. Ferulic acid (FA) is a phytochemical commonly found in fruits and vegetables such as tomatoes, sweet corn, and ricebran. FA exhibit a wide range of pharmacological effects including antiageing, anti-inflammatory, anticancer, antidiabetic, antiapoptotic, and neuroprotective. The present work is aimed at evaluating the radioprotective effect of FA, on gamma-radiation induced toxicity in primary cultures of isolated rat hepatocytes. Hepatocytes were isolated from the liver of rats by collagenase perfusion. The cellular changes were estimated using lipid peroxidative indices like thiobarbituric acid reactive substances (TBARS), the antioxidants superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and reduced glutathione (GSH), ceruloplasmin, Vitamins A, E and C and uric acid. DNA damage was analyzed by single cell gel electrophoresis (comet assay). An increase in the severity of DNA damage was observed with increasing dose (1, 2 and 4Gy) of gamma-radiation in cultured hepatocytes. TBARS were increased significantly, whereas the levels of GSH, Vitamins C, E and A, ceruloplasmin, uric acid and antioxidant enzymes were significantly decreased in gamma-irradiated groups. The maximum damage to hepatocytes was observed at 4Gy irradiation. Pretreatment with FA (1, 5 and 10 microg/ml) significantly decrease the levels of TBARS and DNA damage. In addition, pretreatment with FA significantly increased antioxidant enzymes, GSH, Vitamins A, E and C, uric acid and ceruloplasmin levels. The maximum protection of hepatocytes was observed at 10 microg/ml of FA pretreatment. Thus, pretreatment with FA helps in protecting the hepatocytes against gamma-radiation induced cellular damage and can be developed as a effective radioprotector during radiotherapy.     

Berberine inhibits growth, induces G1 arrest and apoptosis in human epidermoid carcinoma A431 cells by regulating Cdki-Cdk-cyclin cascade, disruption of mitochondrial membrane potential and cleavage of caspase 3 and PARP

Chemotherapeutic approach using non-toxic botanicals may be one of the strategies for the management of the skin cancers. Here we report that in vitro treatment of human epidermoid carcinoma A431 cells with berberine, a naturally occurring isoquinoline alkaloid, decreased cell viability (3-77%, P < 0.05-0.001) and induced cell death (3-51%, P < 0.01-0.001) in a dose (5-75 microM)- and time (12-72 h)-dependent manner, which was associated with an increase in G(1) arrest. G(0)/G(1) phase of the cell cycle is known to be controlled by cyclin dependent kinases (Cdk), cyclin kinase inhibitors (Cdki) and cyclins. Our western blot analysis showed that berberine-induced G(1) cell cycle arrest was mediated through the increased expression of Cdki proteins (Cip1/p21 and Kip1/p27), a simultaneous decrease in Cdk2, Cdk4, Cdk6 and cyclins D1, D2 and E and enhanced binding of Cdki-Cdk. In additional studies, treatment of A431 cells with berberine (15-75 microM) for 72 h resulted in a significant dose-dependent increase in apoptosis (31-60%, P < 0.05-0.001) than non-berberine-treated control (11.7%), which was associated with an increased expression of pro-apoptotic protein Bax, decreased expression of anti-apoptotic proteins Bcl-2 and Bcl-xl, disruption of mitochondrial membrane potential, and activation of caspases 9, 3 and poly (ADP-ribose) polymerase. Pretreatment of A431 cells with the pan-caspase inhibitor (z-VAD-fmk) significantly blocked the berberine-induced apoptosis in A431 cells confirmed that berberine-induced apoptosis is mediated through activation of caspase 3-dependent pathway. Together, this study for the first time identified berberine as a chemotherapeutic agent against human epidermoid carcinoma A431 cells in vitro, further in vivo studies are required to determine whether berberine could be an effective chemotherapeutic agent for the management of non-melanoma skin cancers.     

Grape seed proanthocyanidins induce apoptosis and inhibit metastasis of highly metastatic breast carcinoma cells

The strategies available for the treatment of metastatic breast cancer are limited. Dietary botanicals may have a better protective effect on this disease. We therefore investigated the effects of grape seed proanthocyanidins (GSPs) on a highly metastatic mouse mammary carcinoma cell line. In vitro treatment of breast cancer cells, 4T1, MCF-7 and MDA-MB-468, with GSPs resulted in significant inhibition of cellular proliferation and viability, and induction of apoptosis in 4T1 cells in a time- and dose-dependent manner. Further analysis indicated an alteration in the ratio of Bax/Bcl-2 proteins in favor of apoptosis, and the knockdown of Bax using Bax siRNA transfection of 4T1 cells resulted in blocking of GSPs-induced apoptosis. Induction of apoptosis was associated with the release of cytochrome c, increased expression of Apaf-1 and activation of caspase 3 and poly (ADP-ribose) polymerase. Treatment with the pan-caspase inhibitor (Z-VAD-FMK) resulted in partial but significant inhibition of apoptosis in 4T1 cells suggesting the involvement of both caspase activation-dependent and activation-independent pathways in the apoptosis of 4T1 cells induced by GSPs. The effects of dietary GSPs were then examined using an in vivo model in which 4T1 cells were implanted subcutaneously in Balb/c mice. Dietary GSPs (0.2 and 0.5%, w/w) significantly inhibited the growth of the implanted 4T1 tumor cells and increased the ratio of Bax:Bcl-2 proteins, cytochrome c release, induction of Apaf-1 and activation of caspase 3 in the tumor microenvironment. Notably, the metastasis of tumor cells to the lungs was inhibited significantly and the survival of the mice enhanced. These data suggest that GSPs possess chemotherapeutic efficacy against breast cancer including inhibition of metastasis.     

Antiallergic, antipyretic, hypoglycemic and hepatoprotective effects of aqueous extract of Coronopus didymus Linn

The aqueous extract of whole plant of Coronopus didymus LINN (CD) [Family: Bracicacea] was screened for antiallergic, antipyretic and hepatoprotective effects in rats and hypoglycemic activity in mice. The extract showed significant antiallergic, antipyretic, hypoglycemic and hepatoprotective activity at 200 and 400 mg/kg doses on oral administration. Mechanistically, CD acts as an antioxidant as evidenced by its ability to scavenge DPPH and superoxide radicals. All the observed activities may be due to the presence of flavonoids, saponins and tannins as they are reported to possess a variety of biological activities.     

Can root pulp visibility in mandibular first molars be used as an alternative age marker at the 16 year threshold in the absence of mandibular third molars: an orthopantomographic study in a South Indian sample

In many countries, the 16 years of age threshold is considered to be legally relevant according to the law. This research aims to ascertain the sensitivity and specificity of Olze et al. stages of root pulp visibility (RPV) in a sample of 760 south Indian children aged between 12 and 20 years, with an age threshold of 16 years, using receiver operating characteristic curves and area under the curve (AUC). Spearman’s rho correlation showed a strong positive correlation between the RPV stages and age. No significant difference between the right and left lower first molars was seen. RPV Stage 2 showed the highest AUC in both females (0.813) and males (0.790). The performance of the RPV Stage 2 to discriminate the legal age threshold of 16 years resulted in the sensitivity, specificity and accuracy values of 0.61, 0.96 and 0.77 in males, 0.65, 0.97 and 0.80 in females. It resulted in 3.6% and 2.9% of false positives and 38.5% and 34.5% of false negatives in both sexes. Even though, RPV Stage 2 can discriminate reasonably well between two age categories, due to the high percentage of false negatives we recommend its use in conjunction with other age estimation methods.