Nadja Nikolic

Human Cytomegalovirus and Epstein-Barr Virus Genotypes in Apical Periodontitis Lesions

INTRODUCTION Different genotypes of human cytomegalovirus (HCMV) and Epstein-Barr virus (EBV) possess specific pathogenic abilities because of various interactions with the hosts immune system and differences in cell tropism. The aim of this study was to determine the distribution of HCMV and EBV genotypes in apical periodontitis lesions in relation to their clinical and histopathologic features. METHODS One hundred samples of apical periodontitis lesions and 25 control samples (healthy pulp tissue) were collected. The presence of HCMV glycoprotein B (gB) and EBV nuclear antigen-2 genotypes was analyzed by nested polymerase chain reaction and restriction fragment length polymorphisms analysis. RESULTS EBV and HCMV were detected in apical periodontitis lesions at significantly higher frequencies than in healthy pulp controls (P = .020 and P = .020, respectively). HCMV gB type II was significantly more frequent compared with gB type I in the examined groups (P = .036). No HCMV gB type III or IV products were found. In both periapical lesions and controls, EBV-1 occurred more often compared with EBV-2 (P = .001). Dual EBV and HCMV coinfection was more frequently detected in large-size periapical lesions (P = .038). CONCLUSIONS Both HCMV and EBV are associated with inflammatory processes of periapical bone destruction. HCMV gB type II and EBV-1 are the most prevalent genotypes in apical periodontitis lesions.

Survivin gene promoter -31 G/C polymorphism is associated with Wilms tumor susceptibility in Serbian children.

Survivin, an apoptotic inhibitor, is overexpressed in various types of cancer. Mechanisms of survivin upregulation are still poorly understood, but single nucleotide polymorphisms in the survivin gene promoter have been shown to modulate survivin expression and consequently the risk for some types of cancer. The aim of the present study was to investigate whether survivin promoter −31 G/C and −241 C/T polymorphisms could represent susceptibility factors for Wilms tumor (WT) development in Serbian population. Genotype and allele frequencies for the 2 polymorphisms in survivin promoter have been analyzed by polymerase chain reaction/restriction fragment length polymorphism in 59 WT patients and 82 controls. The frequencies of alleles and genotypes were significantly different between patients and controls for the −31 G/C polymorphism. Individuals with CC and CG genotypes had significantly decreased risk of WT compared with GG individuals (odds ratio 0.26, 95% confidence interval, 0.07-0.96; odds ratio 0.30, 95% confidence interval, 0.15-0.60). There was also a statistically significant difference in genotype frequencies between intermediate and high-risk prognostic groups (P=0.015). The −241 C/T polymorphism did not show association with WT susceptibility. Our findings suggest that the G allele at −31 survivin gene promoter position is associated with a significantly higher cancer risk in Serbian children, with a gene dosage effect.

The role of TERT-CLPTM1L SNPs, hTERT expression and telomere length in the pathogenesis of oral squamous cell carcinoma

The aim of this study was to assess TERT-CLPTM1L single-nucleotide polymorphisms (SNPs) (rs402710 C/T in the CLPTM1L gene; rs2736100 A/C and rs2736098 G/A in the TERT gene) as risk factors for development of oral squamous cell carcinoma (OSCC), and to investigate the relationship between the analyzed polymorphisms, relative telomere length (RTL), telomerase expression and clinicopathologic characteristics of OSCC in a Serbian population. Paraffin-embedded tumor samples and buccal swabs from cancer-free controls were genotyped using PCR-RFLP, while tumor RTL values and telomerase expression were estimated by real-time PCR and immunohistochemistry, respectively. CLPTM1L rs402710 and TERT rs2736100 polymorphisms were associated with a significantly increased risk of OSCC, and TERT rs2736098 with a significantly decreased risk. No significant association was found between TERT-CLPTM1L polymorphisms, tumor RTL values, telomerase expression, and clinicopathologic features, although a trend towards longer telomeres was evident in telomerase-positive samples and less advanced tumors. Kaplan-Meier survival analysis showed that patients with longer telomeres in their tumors had significantly better overall survival than patients with shorter telomeres. Our research seems to provide strong evidence for an association between CLPTM1L rs402710C/T and TERT rs2736100A/C SNPs and the risk of OSSC, and suggests that higher tumor RTL values and positive hTERT expression may be applicable as early prognostic markers.(J Oral Sci 58, 449-458, 2016).

High frequency of p16 and p14 promoter hypermethylation and marked telomere instability in salivary gland tumors.

OBJECTIVES to investigate p16(INK4a) and p14(ARF) tumor suppressor gene methylation status, determine telomere length and assess the importance of these epigenetic and genetic parameters in the development of pleomorphic adenoma and carcinoma ex pleomorphic adenoma of the parotid salivary glands. MATERIALS AND METHODS Genomic DNA from paraffin-embedded samples of 50 pleomorphic adenomas and 10 carcinomas ex pleomorphic adenoma was subjected to methylation specific polymerase chain reaction for hypermethylation analyses and real time polymerase chain reaction for the relative telomere length calculations. RESULTS Promoter hypermethylation of the two genes was a very frequent event in both neoplasms - between 60% and 90% of samples were hypermethylated - but without significant difference between the groups. The mean relative telomere length in the pleomorphic adenoma group was significantly increased in comparison to the control group (P=0.00), and significantly decreased in comparison to the carcinoma group (P=0.05). Telomeres were also longer in myxoid and cellular histological subtypes of adenomas than in the classic type (P=0.044 and P=0.018, respectively). Longer telomeres were more frequent in tumors with hypermethylated p14(ARF) alleles (P=0.013). CONCLUSION Promoter hypermethylations seems to be an important mechanism of p16(INK4a) and p14(ARF) inactivation in parotid gland tumors. Telomeric lengthening appears to be involved in the pathogenesis of both benign and malignant tumors of the parotid glands.

P14 methylation: an epigenetic signature of salivary gland mucoepidermoid carcinoma in the Serbian population

OBJECTIVE To investigate the prevalence of p16INK4 a, p14ARF, tumor protein p53 (TP53), and human telomerase reverse transcriptase (hTERT) promoter hypermethylation in mucoepidermoid carcinomas (MECs) and search for a possible association between methylation status and clinicopathological parameters. STUDY DESIGN DNA extracted from 35 formalin-fixed and paraffin-embedded MEC samples and 10 normal salivary gland (NSG) tissue samples was analyzed for the presence of promoter hypermethylation using methylation-specific polymerase chain reaction testing. RESULTS The percentages of gene hypermethylation in MECs versus NSGs were the following: p14: 100% versus 20% (P<.001); p16: 60% versus 20% (P = .035); hTERT: 54.3% versus 20% (P = .078); and TP53: 31.4% versus 30% (P = .981). Multiple sites were found to be methylated in 86% of MECs compared with 10% in NSGs (P< .001). TP53 and hTERT were more often methylated in lower clinical stages (P = .033 and P = .005, respectively). CONCLUSIONS Hypermethylation of p14 appears to be an important event in the development of mucoepidermoid carcinoma. High frequency of gene hypermethylation and high incidence of methylation at multiple sites point to the importance of epigenetic phenomena in the pathogenesis of MECs, although with modest impact on clinical parameters.

Differentiation of stem cells from apical papilla into neural lineage using graphene dispersion and single walled carbon nanotubes: NEURAL DIFFERENTIATION OF SCAP

Stem cell-based therapies are considered a promising treatment modality for many medical conditions. Several types of stem cells with variable differentiation potentials have been isolated from dental tissues, among them stem cells from apical papilla (SCAP). In parallel, new classes of biocompatible nanomaterials have also been developed, including graphene and carbon nanotube-based materials. The aim of the study was to assess whether graphene dispersion (GD) and water-soluble single walled carbon nanotubes (ws-SWCNT), may enhance SCAPs capacity to undergo neural differentiation. SCAPs cultivated in neuroinductive medium supplemented with GD and ws-SWCNT, separately and in combination, were subjected to neural marker analysis by real-time polymerase chain reaction (neurofilament medium [NF-M], neurogenin-2 [ngn-2], β III-tubulin, microtubule-associated protein 2) and immunocytochemistry (NeuN and β III-tubulin). GD, ws-SWCNT, and their combination, had neuro-stimulatory effects on SCAPs, as judged by the production of neural markers. Compared to cells grown in nanomaterial free medium, cells with GD showed higher production of B3T, cells with ws-SWCNT had higher production of ngn-2 and NF-M, while the combination of nanomaterials gave similar levels of both B3T and NF-M as the neuroinductive medium alone, but with the finest neuron-like morphology. In conclusion, GD and ws-SWCNT seem to enhance neural differentiation of SCAP.

TNF α (-308G>A) And TNF-R1 (36A>G) Single nucleotide polymorphisms are strong risk factors for odontogenic keratocystic tumor development.

BACKGROUND Polymorphisms in genes encoding tumor necrosis factor-α (TNF-α) and its receptor TNF-R1 have been shown to affect one persons susceptibility to develop certain neoplastic diseases. The aim of the present association study was to investigate whether single nucleotide polymorphisms (SNPs) in TNF-α (-308G>A) and TNF-R1 (36A>G) genes modulate the susceptibility for keratocystic odontogenic tumors (KCOTs) development in Serbian patients. METHODS Genotyping was performed in 60 KCOT patients and 125 healthy individuals, using polymerase chain reaction/restriction fragment length polymorphism analysis. RESULTS A significant difference in genotype and allele frequencies was found between patients and controls for both SNPs (P < 0.05). Carriers of the TNF-α A variant had an eightfold increase of KCOT risk (OR = 8.12, 95% CI = 3.98-16.56, P < 0.0001), while carriers of the TNF-R1 G variant had approximately a fourfold increase of KCOT risk (OR=3.65, CI: 1.60-8.40, P = 0.001). CONCLUSIONS Our findings suggest that the two polymorphisms are strong risk factors for KCOT development in Serbian population.

Clinical and microbiological effects of the initial periodontal therapy

INTRODUCTION Periodontitis is a destructive inflammatory disease of the tooth-supporting tissues, primarily caused by Gram-negative microorganisms. Thus, the primary objective of cause-related initial periodontal therapy is disruption and removal of the subgingival biofilm. OBJECTIVE The aim of this study was to evaluate the clinical and microbiological effects of the initial therapy in patients diagnosed with chronic periodontitis. METHODS Forty patients with chronic periodontitis were included in the study. As a part of the clinical assessment undertaken prior to the initial therapy, as well as one month and three months post-therapy, plaque index, gingival index, papilla bleeding index, probing pocket depth and clinical attachment level were recorded. Microbiological testing was performed prior to the initial therapy and three months after therapy. Polymerase chain reaction assays were used to determine the presence of Porphyromonas gingivalis, Tannerella forsythensis, Prevotella intermedia and Aggregatibacter actinomycetemcomitans. RESULTS All clinical parameters were significantly reduced after therapy. The prevalence of Aggregatibacter actinomycetemcomitans was reduced by 22.5%, which was a statistically significant decrease compared to the baseline. The prevalence of Porphyromonas gingivalis, Tannerella forsythensis and Prevotella intermedia tended to decrease after therapy; however, the difference did not reach statistical significance. CONCLUSION The results of the present study demonstrated the beneficial effects of the initial periodontal therapy on both the clinical and microbiological parameters.