Cytogenetic monitoring of hospital workers exposed to low-level ionizing radiation

In the present study the cytogenetic effects in hospital workers exposed to low-level radiation were evaluated. Samples of peripheral blood were collected from 63 subjects working in radiodiagnostics and from 30 subjects, working in the same hospitals, who were used as controls. A higher number of cells with chromosome-type aberrations (CA) was observed in the exposed workers vs. the controls and the difference was statistically significant (p less than 0.05). No correlation was, on the contrary, found between CA and years of exposure. A significant difference was observed in the incidence of cells with CA between smokers and non-smokers, but in the control group only. In contrast, in the workers exposed to ionizing radiation, the frequency of cells with CA was very similar in smokers and non-smokers.

Influence of a constant magnetic field on human lymphocyte cultures

The growing exposure to magnetic fields of a certain intensity could represent a serious hazard for our health. In the present note we analyze the effect of a 740 Gauss magnetic field on human lymphocyte cell cultures. From the analysis of our data it is possible to point out that this field produces an inhibition of the cell growth, while does not affect at all the sister chromatid exchange frequency of the chromosomes. Conversely we found a significant increase of chromosome aberrations in the exposed cells. The chromosome aberrations found were mostly gaps and breaks.

[Location of acetylcholinesterase in axotomized ciliary ganglia]

In the present note we have investigated the cytochemical localization of acetylcholinesterase (AChE) in the chick ciliary ganglion (CG) after post-ganglionic axotomy obtained by ablation of the eyeball. Preliminary results show at quite early stages after axotomy a remarkable reduction of cytoplasmic AChE, the residual one being localized in the rough endoplasmic reticulum. On the contrary synaptic areas, in particular those concerning the calyciform synapses, still show a marked AchE activity, similarly to what observed in physiological conditions. The decrease of cytoplasmic AChe in axotomized CG does suggest the possibility that such AChE undergoes to a topographical rearrangement moving towards the synaptic areas of ganglionic neurons.

Cell kinetics and sister-chromatid-exchange frequency in human lymphocytes

Repeated cultures from 5 healthy donors were set up in 3 tissue-culture media: TC109, TC199 and TC1640. For each donor, 3 blood samples were taken at 1-week intervals, making a total of 5 x 3 x 3 = 45 cultures. Our results show a large variability in the individual SCE base-line frequency. This variability can be partly attributed to the different tissue-culture media or to the donors themselves. Our results, however, stress the importance of the proliferating rate of the culture in determining the SCE frequency.

The banded karyotypes of Macaca fuscata compared with Cercocebus aterrimus

The karyotypes of Macaca fuscata and Cercocebus aterrimus are compared after G, C and AgNOR banding. Although it is often assumed that the 42-chromosome monkeys (species of the genera Macaca, Papio, and Cercocebus) are identical at the chromosomal level, a number of clear and consistent differences between the karyotypes of these two taxa are described. These differences include one pericentric inversion and differences in staining intensity, particularly in centromeric and pericentromeric areas. It is probable that high resolution chromosome techniques could reveal more differences between taxa in the 42-chromosome group than are now believed to exist. It is therefore probable that karyological data could provide insight into the phylogenetic relationships in this group of Old World monkeys.

Analysis of cell kinetics, chromosome aberration frequency and sister chromatid exchanges in lymphocyte "in vitro" cultures of patients irradiated by 131I. Preliminary note

In the present note we analyse the possible effect of 131I administration on lymphocyte cultures or patients previously subjected to thyroidectomy because of carcinoma. Three parameters were taken into consideration: cell kinetics, SCE frequency and chromosome aberrations frequency before and after treatment. It is possible to point out only an increase of chromosome aberrations. Our data stress the importance of considering several variables at the same time when we are faced with the problem of evaluating possible DNA damage.

The effect of cell kinetics and harvest time on SCE and NOR associations in Macaca fuscata lymphocytes

The relationship between cell kinetics and cell harvest time on sister chromatid exchange (SCE) and NOR (marker chromosome) association was investigated in cultured Macaca fuscata lymphocytes. The average number of SCE's in individuals ranged from 3.77 to 9.07 per cell. The highest SCE rate was found in cultures harvested at 60 h. The data suggest a decrease in SCE frequency between 60 h and subsequent cell harvest at 72, 84, and 96 h. NOR association frequency was also affected by cell kinetics, as well as by cell harvest time. The highest association frequencies were at 48 h, when the number of first mitoses was greatest.

Clastogenic effect of BrdU on different phases of human lymphocyte "in vitro" cell cycle

From the data presented, it can be pointed out a mitotic delay in the cell cycle, possibly due to BrdU cytotoxic effect. Irradiation in G1 phase does not produce any increase in SCE frequency while irradiation in S or G2 phase increases significantly this frequency. Our data support the hypothesis that BrdU does not produce by itself an increase of chromosome aberrations but act as sensitizer for cells which have incorporated it.

Analysis of human lymphocyte cell cycle kinetics in vitro by incorporation into DNA of bromodeoxyuridine

Human lymphocytes of four donors were cultured for 40 to 76 hours and harvested at 4 hour intervals. They were analysed for the number of 1st, 2nd and 3rd division metaphases using the BrdU-Giemsa technique. All 44 hours cultures showed metaphases only in their 1st division; 2nd division metaphases began to appear in 48 hours cultures and 3rd division metaphases in 64 hours cultures. Another group of lymphocytes from 4 other donors were irradiated and harvested at 72 hours. These cultures showed a decrease in the percentage of 3rd division metaphases, accompanied by an increase in the percentage of 1st division metaphases, proportional to the irradiation dose.

Analysis of chromosome aberrations after exposure to ionizing radiation in "in vitro" cultures of human lymphocytes by means of BrdU incorporation

From the data presented, it can be pointed out that a linear relationship does not exist between irradiation doses and Sister chromatid exchanges. The number of chromosome aberrations instead increases regularly in correspondence with the increase of the irradiation doses while SCE remain at the same level. Our data demonstrate that, at each division, there is, at least in vitro, the loss of about 50% of the dicentrics and support the necessity in order to evaluate chromosome damage, of considering cultures harvested not later than 44 hours.

Satellite associations of human acrocentric chromosomes identified by trypsin treatment at metaphase

In the present work 2526 metaphase plates were prepared from 28 normal adult individuals (12 male and 16 female) and then treated with the trypsin method in order to recognize the acrocentric chromosomes involved in the satellite associations. From our data it can be inferred that while the pattern of association of D--D, D--G and G--G groups seems to be random, there exists some preferential association, particularly between the pairs 13--14, 13--13, 13--21 and 21--21. This non-random participation of the acrocentric chromosomes could fit with the new concepts of interphase/metaphase organization of the chromatin fibre.