Abstract. Retinoids as important growth and differentiation regulating agents have a potential role in the chemoprevention of head and neck squamous cell carcinoma (HNSCC). Despite the promising preclinical and early clinical findings, limitations of application are raised by intrinsic resistance acquired during carcinogenesis. Retinoic acid receptor ß2 (RARß2) is one of the proximate mediators of retinoid signalling and its expression is often diminished in early stages of head and neck carcinogenesis. One form of retinoid resistance has been associated with the methylation-induced silencing of the RARß gene. We studied primary HNSCC samples of different anatomical sites in respect of methylation, expression and allelic loss of RARß gene. A strong correlation (p<0.01) was found between hypermethylation and reduced expression of RARß2, however the allelic loss at 3p24, the locus of RARß, did not considerably influence its mRNA level. Hypopharynx tumors showed significantly lower hypermethylation (p<0.05) and higher mRNA expression levels of RARß2 compared to the tumors located at other sites of the head and neck. We could also provide evidence that poorly differentiated grade 3 tumors had significantly higher RARß2 expression and lower methylation levels (p<0.05) than better differentiated grade 1 and grade 2 tumors. In addition, we found a good correlation between the methylation degree of the RARß2 promoter and the ages of patients. Collectively, our results suggest that evaluation of several factors such as tumor location, age, histology and methylation state of the RARß gene might contribute to the selection of patients for retinoid-based chemoprevention.

Under the conditions of the study, root canal form influenced short-term sealing ability. In the long-term the seal was affected by the sealer rather than root canal form.

The objective of this study was to analyse the effectiveness of some parameters which characterise the change in morphology in human root canals subjected to ProTaper rotary enlargement with the help of an X-ray microfocus computed tomography (MCT) and to introduce a novel parameter that is effective in quantifying changes in root canal morphology. Ten each straight and curved root canals with mature apices chosen from extracted human upper incisor and canine teeth were scanned with MCT before and after canal shaping using ProTaper rotary instruments in order to facilitate three-dimensional digital reconstruction and quantitative gauging of relevant instrumental parameters and changes therein (surface area and volume). Root canal geometry change and the effectiveness of shaping were quantified with Structure Model Index change (ΔSMI) and surface area change to volume change ratio (ΔSA/ΔV). These two parameters were also tested on simulated canals. Postinstrumentation cross-sectional changes were also analysed, but only on the plastic blocks. Statistical analysis of parameters was carried out to verify the significance of results. Analysis of cross-sectional shape of postinstrumented resin simulated canals showed statistically significant decrease in Form Factor (p<0.05) and statistically significant increase in Eccentricity (p<0.005). ΔSMI did not show significant difference between straight and curved canals. SMI values showed bidirectional change during root enlargement which questions the reliability of this metric in analysing instrumentation. Statistically significant (p<0.005) deviations in ΔSA/ΔV were quantified as 1.92 and 3.22 for straight and curved human canals, respectively. Instrumentation-induced canal geometry change was determined to be more pronounced in curved canals using the novel parameter ΔSA/ΔV. This has been proven as being a statistically accurate and reproducible parameter for quantitative characterisation of root canal geometry change and differentiation of preparational efficacy for both straight and curved root canals.

Results expression of ghRh was found to be positive in 61.9 % of samples. pghRh receptor was not expressed in our sample set, while sV1 could be detected in 17.4 % and sV2 in 8.6 % of the gB tissues. In 65.2 and 78.3 % of samples, significant egFR over-expression or Pten under-representation could be detected, respectively. In 47.8 % of cases, egFR up-regulation and Pten down-regulation occurred together. survival was significantly poorer in tumors lacking ghRh expression. this worse prognosis in ghRh negative group remained significant even if sV1 was also expressed. Conclusion Our study shows that ghRh and sV1 genes expressed in human gB samples and their expression patterns are associated with poorer prognosis.Keywords ghRh · pghRhR · splice variants · sV1 · egFR · Pten · human glioblastoma AbstractPurpose glioblastoma (gB) is the most frequent brain tumor. Despite recent improvement in therapeutic strategies, the prognosis of gB remains poor. growth hormone-releasing hormone (ghRh) may act as a growth factor; antagonists of ghRh have been successfully applied for experimental treatment of different types of tumors. the expression profile of ghRh receptor, its main splice variant sV1 and ghRh have not been investigated in human gB tissue samples. Methods We examined the expression of ghRh, fulllength pituitary-type ghRh receptor (pghRhR), its functional splice variant sV1 and non-functional sV2 by Rt-PCR in 23 human gB specimens. epidermal growth factor receptor (egFR) and phosphatase and tensin homolog gene (Pten) expression levels were also evaluated by quantitative Rt-PCR. Correlations between clinico-pathological parameters and gene expressions were analyzed.g. Mezey and a. treszl contributed equally to this work.

No abstract