A 10-year retrospective study on odontogenic tumors in Iran.

OBJECTIVE: The aim of this study was to review cases of odontogenic tumors diagnosed in two pathology centers in Tehran, Iran, during a 10-year period. STUDY DESIGN: Patients' records were seen at two teaching pathology Centre's of Shahid Beheshti University between the months of March 2000 to 2010 with histologic diagnosis of any type of odontogenic tumors. The records were analyzed for frequency, age, sex, site, as well as clinical, radiographic and histopathologic findings. RESULTS: Of 30706 biopsies, 4767 (15.5%) cases were diagnosed as oral and maxillofacial lesions. Among these, 720 cases were tumoral with 188 (26.1%) cases of odontogenic tumors. Tumors with odontogenic epithelium origin formed 70.2% of total numbers of odontogenic tumors. Mixed odontogenic tumors and tumors of odontogenic ectomesenchyme comprised 12.2% and 17.5% of the cases respectively. Ameloblastoma, with a frequency of 62.2% was the most common tumor in this review which was followed by odontoma and odontogenic myxoma. CONCLUSION: Although there are few studies on odontogenic tumors in literature, the comparison of our results with existing data shows significant differences in the distribution of tumors and age of patients, which may be due to ethnic features and geographic distribution of patients. Future studies on other ethnic groups are essential for further clarification of the findings in this research.

Cyclin d1 expression in odontogenic cysts.

OBJECTIVE: In the present study expression of cyclin D1 in the epithelial lining of odontogenic keratocyst, radicular cyst, dentigerous cyst and glandular odontogenic cyst was investigated to compare proliferative activity in these lesions. MATERIAL AND METHOD: Immunohistochemical staining of cyclin D1 on formalin-fixed, paraffin-embedded tissue sections of odontogenic keratocysts (n=23), dentigerous cysts (n=20), radicular cysts (n=20) and glandular odontogenic cysts (n=5) was performed by standard EnVision method. Then, slides were studied to evaluate the following parameters in epithelial lining of cysts: expression, expression pattern, staining intensity and localization of expression. RESULTS: The data analysis showed statistically significant difference in cyclin D1 expression in studied groups (p < 0.001). Assessment of staining intensity and staining pattern showed more strong intensity and focally pattern in odontogenic keratocysts, but difference was not statistically significant among groups respectively (p=0.204, 0.469). Considering expression localization, cyclin D1 positive cells in odontogenic keratocysts and dentigerous cysts were frequently confined in parabasal layer, different from radicular cysts and glandular odontogenic cysts. The difference was statistically significant (p < 0.01). CONCLUSION: Findings showed higher expression of cyclin D1 in parabasal layer of odontogenic keratocyst and the entire cystic epithelium of glandular odontogenic cysts comparing to dentigerous cysts and radicular cysts, implying the possible role of G1-S cell cycle phase disturbances in the aggressiveness of odontogenic keratocyst and glandular odontogenic cyst.

The effect of ghrelin on MK-801 induced memory impairment in rats.

Accumulating evidence indicates that the brain-gut peptide ghrelin which is expressed in hippocampus improves memory and learning processes. The MK-801, a noncompetitive NMDA receptor antagonist, has also shown amnesic properties in animal model. The current study was to find out whether intracerebroventricular administration of ghrelin can prevent amnesia induced by MK-801 in rats. A week after the surgery, during which cannuals were implanted in the lateral ventricular, the animals were trained and tested in a step-through type passive avoidance task. Memory retrieval was measured by step-through latency (STL) and total time in dark compartments (TDC). In the first series of experiments, we established a dose-response relationship for ghrelin on the passive avoidance paradigm. In the second set of experiments, animals were divided to two groups. In the first group, MK-801 (0.075, 0.15 and 0.3mg/kg) was injected intraperitoneally (i.p.) immediately after the acquisition session and in the second group MK-801 (same doses) was injected (i.p.) 30 min before the retention session. Analysis of data showed that in both groups, MK-801 impaired learning and memory. In the third set of experiments, administration of ghrelin (200 ng/rat) right after the acquisition session (i.e. before MK-801 injection) improved the MK-801 induced memory impairment, but administration of ghrelin before retrieval session did not affect the MK-801 induced memory impairment. These results show an interaction between ghrelin and glutamatergic system. A novel finding in this study is that ghrelin can prevent amnesia produced by NMDA antagonist in rats when injected in post-training phase.