Investigation of bystander effects in hybrid cells by means of cell fusion and premature chromosome condensation induction.

The established dogma in radiation sciences that underlies radiation protection and therapeutic applications is that radiation effects require induction of DNA damage only in cells that are directly hit by the radiation. However, extensive work during the last decade demonstrates that DNA damage responses can be detected in cells that are only bystanders. Such effects include cell killing and responses associated with DNA and chromosome damage. Here, we developed a strategy for investigating bystander effects on chromosomal integrity by premature chromosome condensation using hybrid cell formation between nontargeted human lymphocytes and targeted CHO cells or vice versa. We reasoned that signaling molecules generated in the targeted component of the hybrid will transfer to the nontargeted cell, inducing damage detectable at the chromosomal level. The results indicate that bystander cytogenetic effects between CHO and human lymphocytes cannot be detected under the experimental conditions used. This may be due either to the lack of communication of such responses between the components of the hybrid or to their abrogation by the experimental manipulations. These observations and the methodology developed should be useful in the further development of protocols for investigating bystander responses and for elucidating the underlying mechanisms.

Presence of human herpes virus-8 in saliva and non-lesional oral mucosa in HIV-infected and oncologic immunocompromised patients.

BACKGROUND/AIM: Human Herpes Virus-8 (HHV-8) is a recently identified virus etiologically associated with Kaposi's sarcoma. Studies regarding its presence in the oral cavity have given variable results. This study attempted to determine the oral presence of HHV-8 in an area where classic Kaposi's sarcoma is primarily found such as Greece. METHODS: Three groups of patients were studied: 10 immunocompromised with hematologic malignancies, 10 immunocompromised with HIV infection and 20 immunocompetent as controls. Whole unstimulated saliva and scrapes from the lingual and the buccal mucosa were collected and polymerase chain reaction was applied to amplify HHV-8 DNA. RESULTS: None of the patients in any group had oral lesions. In the control group, all samples tested negative (0/60). HHV-8 DNA was detected in 5/30 (17%) of all samples from HIV-positive patients (the mean value of their CD4+ T-lymphocytes being 385/mm3) and in 13/30 (43%) of all samples from oncologic patients (mean CD4+ T-lymphocytes 51/mm3). HHV-8 DNA was found in 10% of saliva samples and 40% of lingual and buccal scrapes both of HIV-infected and of oncologic patients. CONCLUSION: HHV-8 is present in the saliva and the non-lesional oral mucosa (not simultaneously) of patients with impaired immunity, with or without HIV co-infection. The oral epithelium seems to represent an independent location of viral residency and may be of viral replication; the clinical implications need further clarification.

Oral health status in Greek children and teenagers, with disabilities.

Nowadays there is a sharp increase of population with disabilities. The aim of this investigation was a) to survey the dental health status, estimate the treatment requirements of children and adolescents with cerebral palsy, mental retardation and visual disorders and b) to compare the oral health status of these groups of individuals. The investigation entailed the clinical examination of 170 individuals, between 6 and 15 years old, who were attending four special schools in Athens, Greece. In conclusion, our investigation documented the following: The treatment needs regarding both dentitions are extremely high in all groups of individuals. The oral hygiene status is in general, moderate to low-grade, especially in the individuals with mental retardation. The highest rate of malocclusion is observed in the group of individuals with cerebral palsy.

Increased G2 chromosomal radiosensitivity in cancer patients: the role of cdk1/cyclin-B activity level in the mechanisms involved.

PURPOSE: To test the hypothesis that deficient DNA repair as measured by increased G2 chromosomal radiosensitivity results from up-regulation of cdk1/cyclinB and cell cycle control mechanisms during the G2 to M transition. MATERIALS AND METHODS: A total of 185 cancer patients and 25 normal individuals were tested for G2 chromosomal radiosensitivity. The chromatid breaks were analysed in metaphase using the G2 assay or directly in G0 and G2 phase using premature chromosome condensation (PCC). The activity of cdk1/cyclinB, a key regulator of the G2 to M-phase transition, was measured by histone H1 kinase activity and correlated with the development of chromatid breaks after irradiation of cell lines in vitro. RESULTS: Based on the G2 assay, cancer patients on average showed increased chromosomal radiosensitivity above controls. When the analysis was carried out directly in G0 or G2 lymphocytes using PCC, no differences in the induction of chromosomal damage and its repair were observed between G2 assay-sensitive and G2-normal donors. Using the G2 assay to test G2 radiosensitivity in various cell lines, it was found that the higher the cdk1/cyclinB activity level of the cell line tested, the higher the yield of chromatid breaks scored. Furthermore, when mitotic cells from these cell lines were used for PCC induction in irradiated G2 lymphocytes it was observed that the higher the cdk1/cyclinB activity level of mitotic cells used, the higher was the induced yield of chromatid breaks. CONCLUSION: The cdk1/cyclin-B activity levels during the G2 to M transition impair DNA repair processes and play a major role in the yield of chromatid breaks induced after G2-irradiation. Regulation of cdk1/cyclinB complex activity rather than deficient repair enzymes of DNA damage may underlie the mechanisms of G2 radiosensitivity.

The lateral periodontal cyst: aetiology, clinical significance and diagnosis.

The lateral periodontal cyst (LPC) is a relatively uncommon but widely recognized odontogenic cyst of developmental origin. It is found mostly in adults and has no sex predilection. LPC is usually discovered during routine radiographic examination, is located mainly between the roots of vital mandibular canines and premolars, and seldom causes pain or other clinical symptoms. The defect appears on radiographs as a round or teardrop-shaped, well circumscribed radiolucency. Due to its location it can easily be misdiagnosed as a lesion of endodontic origin. In this paper, two cases of lateral periodontal cysts are presented. In the first case, the patient (woman, 62 years old) complained of an asymptomatic gingival swelling in the region between the right maxillary canine and premolar. The radiographic examination revealed a well circumscribed radiolucency with a radiopaque margin between the roots of the canine and premolar. The adjacent teeth had vital pulp. Surgical enucleation of the lesion was performed and the histological examination revealed that the lesion was a "lateral periodontal cyst of developmental origin". In the second case, the patient (women, 44 years old) complained of a swelling in the area of tooth 32. During radiographic examination a well circumscribed radiolucency between the roots of the lateral incisor and the canine was discovered. Surgical enucleation of the lesion was performed and the histological examination revealed that the lesion was a "lateral periodontal cyst of developmental origin".

[Determination of absorbed doses of radiation in patients during periapical dental radiography]. / Prosdiorismos ton doseon aktinobolias se astheneis kata te lepse 14 opisthophatniakon aktinographematon.

The aim of this study was to determine the absorbed doses of radiation in the skin region of temporomandibular joint (T.M.J.), maxillary sinus, parotid gland, body of mandible and thyroid gland during 14 periapical radiographs. For this purpose were used: a minim-X, 2000 CIAS international (Kvp:50, mA:10, t:0.1, sec, 0.2 sec), 31 male patients and 31 female patients about the same age, weighing and height who were selected from the Oral Diagnosis Clinic of Athens University, and had indication for periapical dental radiography. The calculation was performed with thermoluminescent dosimeters (T.L.D.) which calibrated by a Known source of Co60 before use. Dosimetry were calculated in T.L.D. detector Model 2000 A-2000 C Harchaw Chemical Co. and the results of calculation which were evaluated statistically using the student t-test, were the following: 1. Dose above 1.00 cGy received the body of mandible region and the maxillary sinus. 2. Dose below 1.00 cGy received the parotid, the T.M.J. and the thyroid region. 3. The male patients received greater doses than the female patients in all anatomical regions which were examined. 4. Doses on the right side were greater than the left side.