Ivana Medvedec Mikić

Analysis of expression patterns of IGF-1, caspase-3 and HSP-70 in developing human tooth germs

AIMS To analyze expression patterns of IGF-1, caspase-3 and HSP-70 in human incisor and canine tooth germs during the late bud, cap and bell stages of odontogenesis. MATERIALS AND METHODS Head areas or parts of jaw containing teeth from 10 human fetuses aged between 9th and 20th developmental weeks were immunohistochemically analyzed using IGF-1, active caspase-3 and HSP-70 markers. Semi-quantitative analysis of each markers expression pattern was also performed. RESULTS During the analyzed period, IGF-1 and HSP-70 were mostly expressed in enamel organ. As development progressed, expression of IGF-1 and HSP-70 became more confined to differentiating tissues in the future cusp tip area, as well as in highly proliferating cervical loops. Few apoptotic bodies highly positive to active caspase-3 were observed in enamel organ and dental papilla from the cap stage onward. However, both enamel epithelia moderately expressed active caspase-3 throughout the investigated period. CONCLUSIONS Expression patterns of IGF-1, active caspase-3 and HSP-70 imply importance of these factors for early human tooth development. IGF-1 and HSP-70 have versatile functions in control of proliferation, differentiation and anti-apoptotic protection of epithelial parts of human enamel organ. Active caspase-3 is partially involved in formation and apoptotic removal of primary enamel knot, although present findings might reflect its ability to perform other non-death functions such as differentiation of hard dental tissues secreting cells and guidance of ingrowth of proliferating cervical loops.

Involvement of IGF-2, IGF-1R, IGF-2R and PTEN in development of human tooth germ – an immunohistochemical study

ABSTRACT Insulin-Like Growth Factor 2 (IGF-2) is a peptide hormone essential for prenatal growth and development. IGF-2 exerts its mitogenic effects via Insulin-Like Growth Factor 1 Receptor (IGF-1R), and is eliminated by binding to Insulin-Like Growth Receptor 2 (IGF-2R). IGF-2 is also negatively regulated by Phosphatase and Tensin Homolog (PTEN), a phosphatase mutated in various tumors. Not much is known about the interplay between these factors during human odontogenesis. In this study, expression patterns of IGF-2, IGF-1R, IGF-2R and PTEN were analyzed by double immunofluorescence in incisor human tooth germs during the foetal period of development between the 7th and 20th gestational week. Throughout the investigated period, IGF-2 was mostly expressed in enamel organ, whereas mild to moderate expression of PTEN could be seen in dental papilla and parts of enamel organ. Expression of IGF-1R was ubiquitous and displayed strong intensity throughout the entire enamel organ. In contrast, expression of IGF-2R had rather erratic pattern in enamel organ and dental papilla alike. Expression patterns of IGF-2, IGF-1R, IGF-2R and PTEN in highly proliferative cervical loops, as well as in differentiating pre-ameloblasts and pre-odontoblasts of cusp tip region during the early and late bell stages when enamel organ acquires definitive shape, indicate importance of these factors in crown morphogenesis of human incisor. Taken together, our data suggest the involvement of IGF-2, IGF-1R, IGF-2R and PTEN in temporo-spatial patterning of basic cellular processes (proliferation, differentiation) during normal tooth development. They are also relevant for improving knowledge of molecular basis of human odontogenesis.

The prevalence of celiac disease in patients with geographic tongue.

BACKGROUND Geographic tongue (GT) is a benign inflammatory condition usually involving the dorsal surface and lateral borders of the tongue. Numerous etiological factors of GT have been suggested, including immunological factors; genetic; atopic or allergic predisposition; emotional stress; and hormonal disturbances. GT may also coexist as one of the possible manifestations of celiac disease (CD). Therefore, the aim of this study was to investigate the prevalence of CD, positive serologic tests for CD screening, and HLA-DQ presence in patients with GT. METHODS Tissue transglutaminase antibodies (anti-tTG), antibodies against gliadin (AGA), and human leukocyte antigen (HLA) typing were assessed for 60 GT patients and 60 healthy control subjects. The duodenal biopsy was performed in patients with positive serologic tests. RESULTS We found that 9 (15%) GT patients were positive for IgA tTG, and in those patients histological changes consistent with CD were confirmed by duodenal biopsy. Only two of them reported the presence of gastrointestinal symptoms. There were statistically significant differences between the GT patients and control group for immunoglobulin (Ig) A tTG (P = 0.03), IgG tTG (P = 0.04), IgA AGA (P = 0.04), and IgG AGA (P = 0.02). CONCLUSION The results of our study demonstrated the increased prevalence of CD in patients with GT. Therefore, the clinical oral examination should be considered a diagnostic tool, especially in atypical or silent forms of CD, since it may contribute to provide an early diagnosis.

Genotoxic biomonitoring of flowable and non-flowable composite resins in peripheral blood leukocytes.

Abstract Objective. Composite restorative materials represent one of the most important groups of materials in contemporary dental practice. However, their incomplete polymerization may lead to monomer-induced genotoxicity. The objective of this study was to evaluate the genotoxicity of three flowable (Filtek Supreme XT Flow, Tetric EvoFlow, Gradia Direct Flo) and three non-flowable dental composite materials (Filtek Z250, Tetric EvoCeram, Gradia Direct Posterior). Materials and methods. Genotoxicity assessment of composite materials was carried out in vitro in human peripheral blood leukocytes using the alkaline single-cell gel electrophoresis technique (comet assay). Prepared materials were eluted in saline solution for 1 h, 1 day and 5 days. Thereafter leukocyte cultures were treated with different concentrations of eluates obtained from each of the tested dental composite materials. Kruskall-Wallis non-parametric test was used for statistical analysis (p < 0.05). Results. The tested materials did not show genotoxic effects after exposure of leucocytes to 1 h eluates. Culture treated with 1 day eluates of all tested materials, only at a highest concentration (10−2), affected the measured cytogenetic parameters. Of all tested materials, only Filtek Z250 and Filtek Supreme XT Flow did not exhibit a genotoxic effect in cultures that were under the influence of 5 day eluates. Conclusion. Tested materials exhibited limited genotoxic activity in peripheral blood leukocytes. Since the effect was observed only in leukocyte cultures treated by 1-day eluates at the highest concentration (10−2) and it decreases in cultures exposed to 5 day eluates, it should not pose a significant risk to the human genome.