Expression of CD 68, CD 45 and human leukocyte antigen‑DR in central and peripheral giant cell granuloma, giant cell tumor of long bones, and tuberculous granuloma: An immunohistochemical study.

Background: Multinucleated giant cells (MNCs) form an integral part of numerous bone and soft tissue tumors, tumor‑like lesions and are often associated with granulomas of immunological and nonimmunological origin. The presence of various types of giant cells depends on the lesions in which they are present which are difficult to be diagnosed under routine histological techniques. Immunohistochemistry can be used for a better diagnosis and understanding of the origin of various giant cells using various markers of immune response like human leukocyte antigen‑DR (HLA‑DR) and those expressed on monocytes and macrophages like CD 68 and leukocyte common antigen (LCA). Materials and Methods: The study group consisted of 10 cases of giant cell tumor (GCT) of long bones, tuberculous granuloma, and giant cell granuloma to evaluate and analyze the expression pattern of LCA, CD 68, and HLA‑DR in various giant cell lesions. Results: Strong expression of CD 68 was observed in 80% of the lesions, strong and moderate expression of CD 45 observed in 70% of the lesions among and within the groups. In contrast, HLA‑DR demonstrated negative expression in 80% of cases except for tuberculous granuloma where all the 10 cases showed moderate to strong immunoreactivity. Conclusion: CD 68 and CD 45 expression was found in central giant cell granuloma, peripheral giant cell granuloma and GCT, suggesting the origin from mononuclear phagocyte system and considering their clinical behavior of osteoclast type. High expressivity of HLA‑DR in tuberculous granulomas which is an essential factor for presentation of the microbial antigen to CD 4 helper cells thus reassuring the fact that they are up‑regulated in response to infection.

Promoter hypermethylation patterns of P16, DAPK and MGMT in Oral Squamous Cell Carcinoma: A systematic review and meta-analysis.

Background: Oral squamous cell carcinoma (OSCC) is a common cancer world‑wide that is highly lethal due to its recurrence and metastasis. Methylation is a common epigenetic mechanism that leads to gene silencing in tumors and could be a useful biomarker in OSCC. The prevalence of P16, death‑associated protein kinase (DAPK) and O6‑methylguanine‑DNA‑methyltransferase (MGMT) promoter hypermethylation in OSCC has been evaluated for several years while the results remain controversial. Objective: The aim of this systematic review is to critically analyze and perform a meta‑analysis on the various studies in the literature that have reported the promoter hypermethylation of P16, DAPK and MGMT genes in OSCC. Search Strategy: Articles were searched and selected through PubMed. Hand search from the relevant journals was also performed. Articles were reviewed and analyzed. Results: The estimated prevalence of P16 methylation was 43%, DAPK methylation was 39.7% and MGMT methylation was 39.8%. Heterogeneity in methylation prevalences and correlations with the clinical outcomes of the disease prevailed in various studies. Conclusion: We can conclude from our systematic review that a higher prevalence of methylation of P16, DAPK and MGMT occur in OSCC. Further studies are required to substantiate the role of methylation of P16, DAPK and MGMT as a marker in OSCC.

Antioxidant and pro-oxidant activity of Vitamin C in oral environment.

Context: Antioxidant properties and Vitamin C. Background: Vitamin C is a naturally occurring organic compound and a potent antioxidant preventing oxidative damage to lipids and other macromolecules. It can also exhibit bimodal activity as a pro‑oxidant at a higher concentration. Vitamin C has a switch over role from being an antioxidant in physiologic conditions to a pro‑oxidant under pathologic conditions. A systematic review of this role would help to elucidate whether it is an antioxidant or a pro‑oxidant in the oral environment. Objective: To review studies reported in the literature elucidating the activity of Vitamin C and determine whether it is an antioxidant or a pro‑oxidant. Materials and Methods: Articles were searched in PubMed, MEDLINE using appropriate key words like “Vitamin C,” “antioxidant activity,” “pro‑oxidant activity,” “oral health” “oral disease.” Hand search of journals was also performed. Articles were reviewed and analyzed. Results: Search strategy reviewed 10 relevant articles which studied the dual role of Vitamin C. 65% of authors analyzed antioxidant action of ascorbic acid compared to 35% of the pro‑oxidant potential. Vitamin C acts as an antioxidant and a pro‑oxidant by a plethora of mechanisms. Factors determining its bimodal activity were studied, and the frequencies of their occurrence in the literature were depicted in percentage. Conclusion: The data validates the role of Vitamin C as an antioxidant under physiologic conditions exhibiting a cross over role as a pro‑oxidant in pathological conditions. Further studies are required to substantiate its pro‑oxidant activity to draw concrete conclusions.