Hamiyet Dönmez

Condensed chromatin surface and NORs surface enhancement in mitogen-stimulated lymphocytes of Down syndrome patients

Mitogen-stimulated lymphocytes of 20 Down syndrome (DS) patients with regular trisomy 21 contain more condensed chromatin surface (11.28 +/- 2.64 % of the total nuclear surface: mean +/- SD) and more nucleolus organiser regions surface (13.21 +/- 3.45 %) than that of 12 healthy controls: (8.84 +/- 2.23 and 9.12 +/- 2.33 %, reciprocally). The source of this peculiarity has been investigated. A computer program was designed for the planimetric measurement of the condensed chromatin surface (CCs)/ total nuclear surface(TNs) and the nucleolus organiser regions surface (NORss) /TNs proportions in interphase nuclei. CCs/TNs and NORss/TNs of 100 maximally activated nuclei (MANs) were measured for each patient and control case. The difference was found highly significant (P<0.01). Nuclei with a diameter of >/= 17 micrometer measured on the slide (in flattened state) were considered as maximally activated nuclei (MANs). NORss/TNs enhancement and fluorescent in situ hybridisation (FISH) studies in MANs of DS patients indicate that this phenomenon is due to the over-expression (or lack of downregulative mechanism) of NORs (rDNA) to some extent, including the NOR of the supernumerary chromosome 21. No statistical difference was observed between 12 healthy controls and 5 Robertsonian translocation type of DS Patients (where the two involved NORs are missing) when the two parameters were considered.

Evaluation of the Nucleolar Organizer Regions in Alzheimer’s Disease

Background: Alzheimer’s disease (AD) is a neurodegenerative disorder in middle and late age. Ribosomal RNA (rRNA) genes are located in the nucleolus (nucleolar organizer regions = NORs). There are increased deposits of β-amyloid protein in the brains of the patients with AD and aged individuals with Down’s syndrome (DS). The β-amyloid gene is located in the acrocentric chromosome 21 that is responsible for rRNA synthesis. Therefore, it is possible that there is a relationship between ribosomal genes and AD. Objective: To investigate the activities of ribosomal genes of AD patients by comparing the activities of NORs in AD patients and healthy controls with the silver-staining method. Methods: NOR surface/the total nucleus surface proportions in interphase nuclei, and silver stainability and satellite association (SA) of acrocentric chromosomes in the metaphases of cultivated lymphocytes of 20 AD patients and 20 healthy controls (10 elderly and 10 young) were evaluated. Results: A decrease in NOR surface/total nucleus surface proportions has been observed in the interphase nucleus of AD patients when compared with elderly controls (p = 0.035). When compared with the sizes of Ag+ segments of acrocentric chromosomes of AD patients and control groups, the Ag-staining size 1 of the chromosome 22 of AD patients was found to be more increased than that of the young controls (p = 0.018). There was no statistically significant difference between AD patients and control groups regarding the number of Ag+ acrocentric chromosomes, Ag+ chromosome 21 and SA frequency (p > 0.05). It has been found that there is only a slight increase in the total number of chromosomes in SA in AD patients when compared with elderly controls (p = 0.05). Conclusion: The decrease in NOR surface/total nucleus surface proportions of AD patients may indicate a reduction in the activity of the ribosomal genes of these patients.

Increased sister chromatid exchanges in workers exposed to occupational lead and Zinc

Sister chromatid exchange (SCE) in blood lymphocytes was determined in 32 male workers occupationally exposed to lead (Pb) and zinc (Zn) and in 20 controls matched for age and smoking habits. Exposed workers have higher SCE mean values than control workers (p < 0.01). In exposed persons, blood Pb concentrations were also significantly higher than controls (p < 0.0001), but the difference between Zn levels in the blood of these groups was not found to be significant (p > 0.05). Our results indicate that Pb may be genotoxic and harmful to human health.

Sister chromatid exchange frequency in inhabitants exposed to asbestos in Turkey

Pleural mesothelioma, lung cancer, pleural calcification and fibrosis have been observed among inhabitants of the villages in Ivriz-Zanapa valley in Turkey. Earlier reports have stated that these endemic pathological conditions are caused by the inhalation of actinolite asbestos, a mineral commonly used indiscriminately to paint the walls and floors of houses. In the present study, 40 inhabitants in Yassikaya village in Ivriz-Zanapa valley and 20 controls were further investigated. The peripheral blood lymphocytes were cultured and harvested at 72 h for sister chromatid exchange (SCE) frequency. Inhabitants had a raised mean SCE rate compared with a control population.

Micronucleus frequencies in workers exposed to lead, zinc, and cadmium

Micronuclei (MN) in blood lymphocytes were determined in 31 male workers occupationally exposed to lead (Pb), zinc (Zn), and cadmium (Cd) and 20 control workers matched for age and smoking habits. Exposed workers have higher MN mean values than control workers (p<0.01). In exposed workers, blood Pb concentrations were also significantly higher than in control workers (p<0.001), but the mean concentrations of Zn and Cd in the blood were not statistically significant compared to the controls (p>0.05). These results suggest that lead may be genotoxic and the human lymphocyte micronucleus test can be used to assess genotoxic effects that result from occupational exposures.

Plasma and erythrocyte lipid peroxide levels in workers with occupational exposure to lead

The plasma and erythrocyte lipid peroxide levels were measured in a group of male subjects occupationally exposed to lead for an average period of 17 yr, and compared to those from an age-matched control group living in the same city in a similar socioeconomical environment.The blood lead and plasma zinc levels were measured by atomic absorption spectroscopy. The plasma and erythrocyte lipid peroxide levels were established by the malondialdehyde determination method. Significant differences were found in the blood lead levels in lead-exposed workers, 15.00±10.15 µg/dL as compared to controls, 2.37±0.89 µg/dL. The plasma (2.67±0.69 µM) and erythrocyte (27.53±6.28 nmol/g Hb) lipid peroxide levels in workers with occupational exposure to lead were significantly higher than controls, 1.23±0.61 µM and 14.35±2.08 nmol/g Hb, respectively. There were no significant differences of the zinc levels in both groups.The blood lead levels had a statistically significant positive correlation with age and with duration of exposure in both groups, but showed no relationship to the corresponding blood zinc levels. The results presented in this study indicate that the increase of plasma and erythrocyte lipid peroxide levels in workers exposed to lead may be related to the lead concentration, age and duration of exposure.

Investigation of Genome Instability in Exfoliated Colonic Epithelial Cells and in Mitogen-Stimulated Lymphocytes of Patients with Ulcerative Colitis

Objective: The present study aimed to evaluate the micronucleus (MN), nucleoplasmic bridges (NPBs) and nuclear buds (NBUDs) in the mitogen-stimulated lymphocytes of patients with ulcerative colitis (UC). In addition, we assessed MN frequency in exfoliated colonic epithelial cells obtained from both the diseased and healthy colonic mucosa of patients. Design: The study was conducted in 22 newly diagnosed patients with UC and in 22 healthy controls. MN, NPB and NBUD values scored in binucleated (BN) cells were obtained from the mitogen-stimulated lymphocytes of patients and control subjects. In addition, the MN values in exfoliated epithelial cells obtained from the diseased and healthy colonic mucosa of patients were evaluated. Results: We found significantly higher MN, NPB and NBUD frequencies in the BN cells of patients with UC than in those of the control subjects (1.61 ± 0.75 vs. 0.89 ± 0.29, 3.93 ± 1.91 vs. 1.39 ± 1.10, and 1.55 ± 0.89 vs. 0.64 ± 0.48, p = 0.001). Also, a statistically significant difference was found between MN frequencies obtained from the diseased and healthy colonic mucosa of patients (1.07 ± 0.46 vs. 0.59 ± 0.21, p = 0.001). No significant relationship was found between age and MN frequency in patients with UC (r = 0.076, p = 0.735). Conclusion: Increased MN, NPB and NBUD frequencies observed in both the lymphocytes and exfoliated colonic epithelial cells obtained from patients with UC may reflect genomic instability.