Biomedical subjects

Halil Demirtas

Publications and source records attributed to Halil Demirtas.

8 recordsLinked to original sources

PubMed2007

Age-dependent decreases in mitogen-stimulation level and RNA content in peripheral blood mononuclear cells of Down syndrome patients.

OBJECTIVE: The aim of the present study was to determine whether or not the phytohemagglutinin (PHA)-activated proliferation and average RNA content in peripheral blood mononuclear cells (PBMC) of Down syndrome (DS) patients change with age. METHOD: Stimulated portion of PBMC and total RNA levels in these cells after 72 h of PHA stimulation from 38 DS patients were compared with 28 age-matched healthy controls using flow cytometric measurement. RESULTS: Decreased ratio of PBMC from DS patients undergoes mitogenic stimulation with age (r = -0.84, P = 0.000). This decrease is not observed in the cells of control individuals (r = 0.03, P = 0.869). Stimulated PBMC in infants with DS have higher level of RNA contents compared to controls (Z = 2.227, P = 0.026). While RNA content in mitogen-stimulated PBMC of DS decreased progressively and significantly with age (r = -0.70, P = 0.000), no significant age-related change in RNA content was found among the cells of healthy individuals in the range of 0-27 year old (r = 0.275, P = 0.157, P > 0.05). CONCLUSION: Age-dependent decreases in mitogen-activated proliferation ratio and average RNA content of PBMC from DS patients appear as regular events. These results may contribute to the explanation of the immune deficiency seen in DS patients since the PHA-stimulated cells are principally T-lymphocytes. This is the first report on the decrease in PHA-stimulated proliferation ratio (stimulability) and RNA level in PBMC of DS patients in relation to age.

Adolescent↗

PubMed2006

Two-dimensional agnor evaluation as a prognostic variable in urinary bladder carcinoma: a different approach via total agnor area/nucleus area per cell.

Traditional criterions are not sufficient to predict accurately the recurrence of transitional cell carcinoma of the urinary bladder. Therefore, we aimed to evaluate the AgNORs via total AgNOR area/nucleus area (TAA/NA) for each cell as a prognostic parameter, in TCC of urinary bladder. Tumor tissues of 20 consecutive cases of male bladder cancer patients were divided into two groups as middle differentiated (LG) and high grade (HG). The extra-tumoral tissue (ETT) samples of 10 males served as control group. A second control group (HC) consisted of five healthy and normal bladder tissue samples. The 3 microm of sections from each paraffin embedded tumoral, extra-tumoral and normal tissue samples served as patient and control groups. After deparaffinization and rehydratation steps, silver (AgNO(3)) staining of nucleolar organizer regions-associated proteins (AgNORs) was performed. Instead of Giemsa stain, we used Hematoxylin for contra staining. The images of the 100 analyzable nuclei from each tissue sample, transferred by means of a video camera and video capture card from microscope and recorded onto a computer. Software was prepared in Delphi language for analysis. Mean (E+02) TAA/NA values of HC, ETT, LG and HG groups were 6.97+2.80, 5.70+1.82, 7.80+3.22 and 9.24+3.88, respectively. Statistical comparisons have shown significant differences between all groups. In conclusion, mean TAA/NA per cell has a potential to be a prognostic parameter. Therefore, further evaluation of big patient series will be useful.

Antigens, Nuclear↗

PubMed2006

Flow cytometric comparison of RNA content in peripheral blood mononuclear cells of Down syndrome patients and control individuals.

OBJECTIVE: Trisomy 21 or Down syndrome (DS) is the most common genetic cause of mental retardation associated with the immunologic and other known defects. Extra chromosome 21 of DS patients contains an average of 40 extra copies of rRNA genes and the in vivo regulation of these genes' activity is not known. Because over 80% of total cellular RNA is rRNA, the measurement of total cellular RNA provides information on rRNA content. The aim of this work was to determine whether or not the additional chromosome 21 causes any increase in total cellular RNA content in mononuclear cells from peripheral blood (PBMNCs) of these patients and whether or not this content is modified with age. METHOD: PBMNCs of 48 patients with DS and 48 healthy controls were studied. RNA content of isolated PBMNCs was evaluated by flow cytometric measurements. RESULTS: Average RNA content of younger DS patients' cells was significantly higher than that of healthy controls (P=0.003). Furthermore, the RNA content decreased significantly with increasing age of DS patients (r=-0.377, P=0.008) in the range of 0-26 year old, whereas no significant relationship was found between age and PBMNCs' RNA content of healthy controls in the same range of ages. CONCLUSION: RNA content of PBMNCs from DS patients decreases rapidly with age. This is the first work on the age-dependent decrease of the RNA content in PBMNCs of DS patients.

Adolescent↗

PubMed2006

Increased micronucleus frequency after oral administration of cadmium in dogs.

Cadmium (Cd) is a toxic heavy metal that has been classified as a human carcinogen by the International Agency for Research on Cancer. The genotoxic effects of cadmium oxide (CdO) were investigated in cultured dog lymphocytes after a short-term oral CdO administration by the micronucleus (MN) test. The dogs were given 10 mg CdO/kg body weight per day for 3 and 28 d, respectively group I (n = 7) and group II (n = 6). Blood samples were collected at the beginning of feeding and at 4 and 29 d after Cd administration and cultured for 72 h. Whereas no significant increase in the MN frequency in group I was observed (p = 0.398), a significant MN induction with CdO was found in group II (p = 0.028) when compared with initial MN frequencies of dogs in both groups. Our results suggest that CdO might be directly and/or indirectly genotoxic after a monthly oral administration of CdO in dogs.

Administration, Oral↗

PubMed2005

NOR expression increases in interphase lymphocytes of Down syndrome babies/children as AgNORs surface, according to the mitogen concentration in the culture medium.

The extra chromosome 21 of Down syndrome (DS) or trisomy 21 patients contains an average of 40 extra copies of rRNA genes and the in vivo/in vitro regulation of the activity of these genes is not fully understood. The objective of this work was to compare the NORs expression pattern in interphase lymphocytes of DS patients with regular trisomy 21 and control individuals according to phytohemagglutinin (PHA) concentration (0.37, 0.75, 1.48 and 2.21 ml) per 100 ml of medium. Because the AgNOR staining is an indicator of the active rRNA genes, comparison of the image analysis values of the AgNOR area in 72 h cultivated lymphocytes for each concentration of PHA between DS patients (N=30) and controls (N=24) provided a plausible conclusion on the regulation of the extra rRNA genes in DS lymphocytes. The nucleolus organizer regions area/total nuclear area (NORa/TNa) was calculated using an in-house computer program. Fifty consecutive interphases per PHA concentration were analysed for each individual, for determination of the NORa/TNa. In contrast to healthy controls, NORa/TNa of lymphocytes from DS patient babies/children (0-8 years old) increased gradually in parallel with the PHA concentration in the culture medium: 10.44+/-1.72% for 0.37 ml of PHA, 11.74+/-1.93% for 0.75 ml of PHA, 13.25+/-2.03% for 1.48 ml of PHA and 13.43+/-2.08% for 2.21 ml of PHA per 100 ml of medium. Contrary to control cells (in which the NORa/TNa ratio according to PHA concentration in the culture medium remains constant), DS interphase lymphocytes in culture do not down-regulate their NOR expression. These results obtained from interphase NORs are consistent with the previous results obtained by evaluating the mean of AgNOR+ chromosome number in metaphase cells, also in relation to the mitogen concentration in the culture medium.

Antigens, Nuclear↗

PubMed2005

NOR expression increases on metaphase chromosomes of Down syndrome lymphocytes in concordance with mitogen concentration in culture medium.

BACKGROUND: Regulation of nucleolus organizer region (NOR) expression in trisomy 21 (Down syndrome [DS]) cells is not fully explained. This work compared NOR expression on metaphase chromosomes in gradiently stimulated lymphocytes from DS patients with those from healthy controls. METHOD: Conventional peripheral blood culture (72 h) and chromosomal preparation procedures were used except that blood samples from each individual were cultivated in the same but gradiently increasing concentrations (0.37, 0.75, 1.48, and 2.21 ml) of phytohemagglutinin (PHA) per 100 ml of medium. One hundred consecutive metaphases per concentration were analyzed for scoring the means of the active NORs bearing chromosomes (AgNOR+ chromosome) per individual and per concentration. RESULTS: In contrast to healthy controls (n=24), AgNOR+ chromosomal number in lymphocytes from 30 DS patients increased in concordance to the gradient of PHA concentration in the culture medium. CONCLUSION: DS lymphocytes do not downregulate their NOR expression in the limit of control cells. This in vitro result may serve as a clue for the explanation of the DS phenotype due to the wasted energy in producing unnecessary rRNA transcripts and AgNOR proteins in utero during organogenesis. These results also indicate that precautions must be used in routine work of NOR evaluation/interpretation in DS lymphocytes.

Azure Stains↗

PubMed2005

Higher NORs-expression in lymphocyte of trisomy 21 babies/children: in vivo evaluation.

Extra chromosome 21 of Down syndrome (DS) or trisomy 21 patients contains an average of 40 extra copies of rRNA genes and the in vivo regulation of these genes is not known. The objective of this work is to compare the NORs expression in interphase nuclei in non-stimulated lymphocytes of DS patients and healthy controls. Because the AgNOR staining is the indicator of the active rRNA genes, comparison of the image analysis values of AgNORs area between DS's and healthy controls' interphase lymphocytes is considered to be sufficient to evaluate the level of rDNA activities in the two groups. The Nucleolus Organizer Regions area/Total Nuclear area (NORa/TNa) was calculated using a computer program designed by us. 100 consecutive NORa/TNa per individual were evaluated. We report that 24 DS children's peripheral lymphocytes show significantly higher NORa/TNa mean value (6.32 +/- 1.77%) than that of the 20 healthy controls' cells (5.31 +/- 1.34%) (2-tailed Mann-Whitney U test, z = 19.4, P = 0.000). The same is true for the nucleolus (AgNOR spot) number per nucleus. The mean value of nucleoli number per nucleus in DS lymphocytes was significantly higher than that of the controls: z = 14.6, P = 0.000. In conclusion, extra rRNA genes on the chromosome 21 are not down-regulated in DS patients' lymphocytes. Rather, extra NORs expressions in 'in vivo' condition contribute to the increase of AgNORs area and AgNOR spots number per nucleus. This is the first work on the comparison of NORs activities in resting (non-stimulated) interphase lymphocytes between DS and healthy controls.

Child↗

PubMed2002

Micronucleus evaluation in mitogen-stimulated lymphocytes of PUVA treated patients.

PUVA describes the treatment of patients with psoralens plus an exposure to a source of UV light of 320-400 nm (UVA). Contradictory results have been reported on the chromosomal damage of PUVA when assayed by sister chromatid exchange (SCE) method. Micronucleus (MN) test is used to detect both clastogenic (breaking) and aneugenic (abnormal segregation) effect of physical/chemical agents on the chromosomes. No data have been found on the MN formation in the cells of PUVA treated patients. Frequency of micronuclei in 72 hours cultivated/mitogen-stimulated lymphocytes of patients have been evaluated at zero time and after 20, 40, 60 sessions of PUVA treatment. While the beginning MN frequency was approximately 0.22% (n=23), it raised to approximately 0.32 (n=23), approximately 0.42 (n=14) and approximately 0.53% (n=10) corresponding respectively to 20, 40 and 60 sessions. These sessions correspond reciprocally to 54+/-23, 172+/-48, 300+/-61 joules/cm2 of UVA and 13, 26, 39 mg/kg of 8-metoxypsoralen (8-MOP). While large interindividual variances were apparent, highly significant differences have been observed between initial MN frequency and after that of the 20, 40 and 60 sessions, (p = 0.000, p = 0.004, p = 0.005, reciprocally, Wilcoxon two-related samples test). The coefficient of correlation between MN frequency and UVA doses starting from zero to 60 sessions of treatment has been found as r = 0.61. This indicates a significant relationship between UVA doses and MN frequencies. However, MN inducibility and synergistic property of 8-MOP with UVA should be taken into account. Gradual MN increase during different sessions of PUVA treatment shows that--once appeared--a part of MN at least persist in the cells of patients from a few days to a few weeks. Smoking as a confounding factor seems to increase MN frequency (p = 0.053, Mann-Whitney U-test) in the beginning population, taken as the control population. This is the first report on the kinetics of MN formation during different sessions of PUVA treatment. Based on our results, we concluded that PUVA treatment causes a detectable chromosome damaging effect on the relatively profound cells/tissues of its human users. Therapists should be careful with its use, especially on the patients who may be more susceptible to carcinogenesis (e.g. immunosuppressed and/or elderly subjects).

Adolescent↗