Nitric oxide (NO), is a ubiquitous, water soluble, free radical gas, which plays key role in various physiological as well as pathological processes. Over past decades, NO has emerged as a molecule of interest in carcinogenesis and tumor growth progression. However, there is considerable controversy and confusion in understanding its role in cancer biology. It is said to have both tumoricidal as well as tumor promoting effects which depend on its timing, location, and concentration. NO has been suggested to modulate different cancer-related events including angiogenesis, apoptosis, cell cycle, invasion, and metastasis. On the other hand, it is also emerging as a potential anti-oncogenic agent. Strategies for manipulating in vivo production and exogenous delivery of this molecule for therapeutic gain are being investigated. However, further validation and experimental/clinical trials are required for development of novel strategies based on NO for cancer treatment and prevention. This review discusses the range of actions of NO in cancer by performing an online MEDLINE search using relevant search terms and a review of the literature. Various mechanisms by which NO acts in different cancers such as breast, cervical, gastric,colorectal, and head and neck cancers are addressed. It also offers an insight into the dichotomous nature of NO and discusses its novel therapeutic applications for cancer prevention and treatment.

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Objective: Interaction between reactive oxygen species (ROS) and reactive nitrogen species (RNS) is a crucial determinant in the etiology of oral squamous cell carcinoma (OSCC), and antioxidants protect against cellular and molecular damage caused by these. This study aims to evaluate ROS and RNS, together with the total antioxidant capacity (TAC), in serum and tissues of OSCC patients. Method: Total nitric oxide (TNO), malondialdehyde (MDA), and TAC were evaluated using a UV visible spectrophotometer in the serum of 30 controls, 30 precancer and 30 OSCC patients and in tissues of 10 controls and 30 OSCC patients. Results: MDA and TNO were significantly elevated with concomitant depletion of TAC in serum and tissues of OSCC patients when compared to controls. A significant positive correlation (p = 0.01), at different levels between TNO and MDA in OSCC patients, was found, which increased with the grade of OSCC. Conclusion: An increase in the levels of TNO, NO-mediated lipid peroxidation, resulting in an increase in MDA levels, the positive TNO-MDA correlation with a deranged antioxidant defense system as demonstrated by significantly low levels of TAC; when all these facts are taken together, we can conjecture that oxidative DNA damage, a vital phenomenon for carcinogenesis, occurs due to the interplay of ROS, RNS and TAC.

Background:The annual mortality rate from head and neck squamous cell carcinoma (HNSCC) is over 11,000 worldwide. Squamous cell carcinoma of the head and neck (SCCHN) frequently metastasizes to the regional lymph nodes which are the first site of arrest of tumor cells that have invaded the peritumoral lymphatics, hence the strongest predictor of disease prognosis and outcome.Aim:The present study aims to compare the efficacy of frozen sections (cryosection), step-serial sectioning conventional H and E staining, immunohistochemistry (IHC) and RT-PCR analysis in detection of lymph node micrometastasis.Materials and Methods:A prospective series of 30 patients who were diagnosed with primary squamous cell carcinoma of the oral cavity and underwent surgical treatment including unilateral or bilateral selective neck dissection were considered for the study.Result:Metastatic carcinomatous cells were observed in H and E staining of frozen section in 18 lymph nodes (54%) and in 19 lymph nodes (57%) in step-serial sectioned H and E-stained sections of the 78 lymph nodes from 30 patients. Carcinomatous cells were immunolabeled with pancytokeratin in 18 lymphnodes (54%). CK19 mRNA was detected in 33 lymph nodes of 16 patients. RT-PCR gave positive signals for 24% and 23% of lymph nodes positive by histopathology and immunohistochemistry.Conclusion:Our study demonstrated that RT-PCR is far more sensitive in detection of micrometastasis than any other technique used in routine procedures and immunohistochemistry. Fifty-three percent patients with micrometastasis detected by RT-PCR had large T3/T4 tumors. Prognosis was poor for patients who were positive for micrometastasis detected only by RT-PCR, among which two patients died within a period of 6 months.

Objective:The aim of this study was to examine if there are qualitative differences in the appearance of external root resorption patterns of primary teeth undergoing physiologic resorption and permanent teeth undergoing pathological root resorption in different conditions.Material and Methods:A total of 40 teeth undergoing external root resorption in different conditions were divided into 4 groups and prepared for examination under scanning electron microscopy at magnifications ranging from 20x to 1000x. Group I: 10 primary molars exfoliated due to physiologic root resorption; Group II: 10 permanent teeth with periapical granulomas showing signs of resorption; Group III:10 permanent teeth therapeutically extracted during the course of orthodontic therapy with evidence of resorption, and Group IV: 10 permanent teeth associated with odontogenic tumors that showed evidence of resorption.Results:In Group I, the primary teeth undergoing resorption showed smooth extensive and predominantly regular areas reflecting the slow ongoing physiologic process. In Group II, the teeth with periapical granulomas showed the resorption was localized to apex with a funnel shaped appearance in most cases. Teeth in Group III, which had been subjected to a short period of light orthodontic force, showed the presence of numerous resorption craters with adjoining areas of cemental repair in some cases. Teeth associated with odontogenic tumors in Group IV showed many variations in the patterns of resorption with extensive loss of root length and a sharp cut appearance of the root in most cases.Conclusion:Differences were observed in the patterns of external root resorption among the studied groups of primary and permanent teeth under physiologic and pathological conditions.