Sister-chromatid exchanges in lymphocytes from patients with Schistosoma hematobium

Sister-chromatid exchange (SCE) frequencies were studied in peripheral blood lymphocytes from 19 patients (13 males and 6 females) with Schistosoma hematobium, prior to the initiation of chemotherapy. The mean frequency of SCE per metaphase for the patients (both sexes) was 10.4 +/- 4.2 which was significantly higher (P less than 0.01) than the mean SCE (6.4 +/- 1.1) score for 35 healthy controls. A highly significant reduction in lymphocyte division and delay in cell-cycle progression as a result of infection were also noticed. These data indicate that infection with S. hematobium could increase SCEs in the host somatic cells.     

Cytogenetic studies on blood lymphocytes from patients with Schistosoma mansoni

Chromosomal aberrations and sister chromatid exchange (SCE) frequencies were studied in peripheral blood lymphocytes from 10 patients with Schistosoma mansoni prior to initiation of chemotherapy. The mean frequencies of chromatid and chromosome breaks for the patients were 1.80 and 2.30%, respectively, which were significantly higher (P less than 0.01) than the means 0.35 and 0.30%, scored for 20 healthy controls. Significant increase in the mean frequency of SCEs in the patients (9.1 +/- 0.5 SCE/cell) was noticeable when compared with the controls (6.2 +/- 0.1 SCEs/cell). Reductions in the lymphocyte divisions and replications in the patients were also observed. These results indicate that infection with S. mansoni could have in vivo mutagenic effects on human chromosomes.     

Baseline frequency of sister-chromatid exchanges in 142 persons of the general Korean population.

Baseline frequencies of sister-chromatid exchange (SCE) were measured in lymphocytes of 142 healthy Koreans ranging in age from newborn infants to the fifties. The overall mean frequency of SCE was 8.78 +/- 0.24/cell. However, highly significant differences were found between individuals. The mean SCE values of the newborn babies and small children less than 10 years old were significantly lower than those of other age groups. No age effect was, however, observed in adolescent and adult subjects. Females had statistically higher SCE levels than males. The mean SCE frequencies of smokers, measured in male subjects more than 10 years old, were slightly, but statistically significantly, higher than those of non-smokers.     

The correlation between the frequency of sister chromatid exchanges and the kinetics of human lymphocyte proliferation: the dependence on the sex of the donor

Sister chromatid exchanges (SCE) and average generation time (AGT) were studied in lymphocytes from 35 donors (23 females and 12 males). A higher SCE frequency was found in lymphocytes from females than from males. Smoking increased SCE frequency in lymphocytes of males, but not of females. No differences in AGTs between males and females were found. Partial correlation coefficients between SCE frequency, AGT values, donor's age and smoking were determined. A statistically significant correlation (r = 0.650, P less than 0.01) between SCE frequency and AGT was found in lymphocytes obtained from females. In lymphocytes from males statistically significant partial correlation coefficients were detected between SCE frequency and AGT (r = -0.696, P less than 0.05), SCE frequency and donor's age (r = 0.770, P less than 0.01), SCE frequency and smoking intensity (r = 0.697, P less than 0.01), AGT value and donor's age (r = 0.882, P less than 0.01), and AGT value and smoking (r = 0.634, P less than 0.05). Thus, considerable differences in number of indices between males and females exist. The present observations together with other studies (D'Souza et al., 1988) suggest that considerations for population monitoring using cytogenetic techniques (ICPEMC Publication No 14) may be supplemented with the recommendation to use (whenever it possible) only males as donors in population studies.     

Whole blood and serum copper levels in relation to sex and age

The copper content in whole blood and serum was determined in healthy human subjects (240 males and 217 females) by atomic absorption spectrophotometry. The mean level of copper obtained in whole blood was 104.8 +/- 20.5 micrograms/100 ml in males and 117.1 +/- 20.1 micrograms/100 ml in females. The mean level of copper in serum was 102.3 +/- 21.7 micrograms/100 ml and 123.9 +/- 30.4 micrograms/100 ml, in males and females respectively. The copper concentration in whole blood and serum in females proved to be significantly higher than in males (p less than 0.001). With respect to age, the copper level showed a slightly negative correlation which is only statistically significant in whole blood in females (p less than 0.05).     

Sister chromatid exchange in patients with viral disease

Sister chromatid exchange (SCE) frequencies were studied in differentially stained chromosomes from lymphocytes of 17 patients with viral disease. The mean SCE score for the patients was 8.7 +/- 2.9 standard deviations. SCE scores were significantly elevated in the patients compared with the controls (p less than 0.01); however, variability in SCE means was observed in the patients. SCE elevations were also present in long term cultured Epstein Barr virus positive human B lymphocytes.     

The effect of valproic acid on SCE and chromosome aberrations in epileptic children

Sister-chromatid exchange (SCE) and chromosome aberrations have been studied in peripheral lymphocytes of 20 epileptic children treated in monotherapy with valproic acid (VPA) for 6-52 months and in 2 matched control groups. The frequencies of SCE in the VPA-treated epileptic children were significantly higher than in the 2 control groups (p less than 0.01); rates of chromosome aberrations were slightly higher but not significantly different from the 2 control groups. We also examined SCE in 10 epileptic children before and after they took sodium valproate for 6-7 months; there was a statistically significant change in SCE following VPA. 9 normal children whose lymphocytes were exposed in vitro to sodium valproate (5-20 micrograms/ml) showed a significant increase in SCE.     

Whole blood and serum zinc levels in relation to sex and age

The zinc content in whole blood and serum was determined in 239 healthy males and 217 healthy females by atomic absorption spectrophotometry. The mean level of zinc obtained in whole human blood from males was 607.0 +/- 105.3 micrograms/100 ml and in females 585.2 +/- 122.9 micrograms/100 ml. The mean level of zinc in serum was 116.6 +/- 55.2 micrograms/100 ml and 105.2 +/- 66.9 micrograms/100 ml in males and females respectively. The zinc concentration in whole blood and serum in males proved to be slightly higher than in females though the difference is not statistically significant. For the males a positive correlation was found between age and the zinc level in whole blood and serum; this is only statistically significant in whole blood. In females, the zinc level in whole blood showed a positive correlation with age which was not statistically significant, while in serum this correlation was negative and statistically significant.     

Analyses of sister-chromatid exchange and cell-cycle kinetics in mouse T- and B-lymphocytes from peripheral blood cultures

A reliable mouse peripheral blood lymphocyte culture assay has been developed for sister-chromatid exchange analysis. Crucial aspects for optimal mitogenesis include: (1) the addition of 5 X 10(5) leucocytes/ml culture; (2) the use of animals with leucocyte counts from 5 to 7 X 10(6)/ml; and (3) the addition of 6% mouse plasma for the first 24 h of a total 54-h incubation. When 7 micrograms phytohemagglutinin/ml were used to stimulate T-lymphocytes, the mitotic index was 3.4 +/- 0.3%, 28 +/- 2.3% of the metaphases were in first-division, and the SCE frequency/metaphase was 7.3 +/- 0.2 (n = 14 mice). When B-lymphocytes were stimulated with 60 micrograms lipopolysaccharide/ml, the mitotic index was 4.5 +/- 0.3%, 64 +/- 3.3% of the metaphases were in first-division, and the SCE frequency/metaphase was 4.6 +/- 0.1 (n = 7 mice). This culture method consistently yields sufficient numbers of metaphases from both B- and T-lymphocytes for SCE and chromosome-breakage studies.     

Serum thyroxine and triiodothyronine radioimmunoassay values in the normal ferret

The European ferret, Mustela putorius furo, has become increasingly popular as an animal model in biomedical research. However, certain important normal clinical data have not been established for the ferret. In this study, serum thyroxine (T4) and 3,3',5-triiodothyronine (T3) values were obtained from ferrets by the use of commercial radioimmunoassays. Sera from 44 animals, 31 males (27 intact and 4 castrated) and 13 females (10 intact and 3 spayed) were assayed. Serum T4 values ranged from 1.01-8.29 micrograms/dl for males (mean = 3.24 +/- 1.65 micrograms/dl), and 0.71-3.43 micrograms/dl for females (mean = 1.87 +/- 0.79 micrograms/dl). Serum T4 values of adult female ferrets, juvenile ferrets (less than 1 year old) of either sex, and castrated males were similar to the normal T4 values of the cat, 1.20-3.80 micrograms/dl. Intact adult male ferrets had higher serum T4 values which were more comparable to those of the normal dog 1.52-3.60 micrograms/dl. Serum T3 values ranged from 0.45-0.78 ng/ml for males (mean = 0.58 +/- 0.09 ng/ml), and 0.29-0.73 ng/ml for females (mean = 0.53 +/- 0.13 ng/ml). These values are comparable to those of dogs and cats which are 0.50-1.50 ng/ml.     

Implications of an elevated sister-chromatid exchange frequency in rat lymphocytes cultured in the absence of erythrocytes

One important variable in complex culture systems such as whole blood is the interaction of the cell types present. To investigate the effects of erythrocytes (RBCs) and monocytes on the sister-chromatid exchange (SCE) frequency, Ficoll-Hypaque-separated Fischer-344 rat leukocytes were added to 1.9 ml of culture medium containing either 4 micrograms phytohemagglutinin or 4-8 micrograms concanavalin A/ml. Bromodeoxyuridine (BrdU;2 microM) was added at 24 h, and the cultures were harvested at 54 or 72 h. SCE frequencies in the mononuclear leukocyte cultures were consistently about 1.5- to 2-fold higher than in the whole-blood cultures. The titration of rat or human RBCs (0.05-2.5 X 10(9)) into purified rat leukocyte cultures reduced the SCE frequency to that of whole-blood cultures. Monocyte depletion decreased the elevated SCE frequency by approximately 50%. Scintillation counting of [14C]BrdU uptake in isolated RBCs revealed that less than 8% of the total amount of BrdU was sequestered. Also, BrdU induced a concentration-dependent increase in SCE in purified leukocytes, but the absolute increase was no greater than in whole-blood lymphocytes. Thus, BrdU had a minor role in the elevated SCE frequency in purified lymphocytes. Neither anti-oxidant enzymes such as catalase and superoxide dismutase nor the hydroxyl radical scavenger, dimethyl sulfoxide, decreased the SCE frequency. Although purified human lymphocytes had a small, but significant increase in SCE compared to whole blood, the magnitude of the dichotomous response between man and rat may represent a fundamental species difference.     

A study of sister-chromatid exchange in peripheral lymphocytes of hepatitis B patients with HBsAg positive and their children

Previous studies of sister-chromatid exchange (SCE) in patients with hepatitis B have been reported. But as far as we know, no such work has been done in children born to parents with hepatitis B, either one or both of whom are infected. In the present study, frequencies of SCE in the peripheral lymphocytes of 30 hepatitis B parents with hepatitis B surface antigen (HBsAg) positive and 40 of their children were observed. SCE frequencies of 20 normal adults and 3 normal children were analysed for comparison with the patients and their children. The results obtained from all of the samples were as follows: The hepatitis B patients with HBsAg positive had a significantly higher SCE frequency than the normal adults (P less than 0.01); the children born after their parents contracted hepatitis B had a significantly higher SCE frequency than normal children (P less than 0.01); there was no significant difference in SCE (P greater than 0.05) between children born after their parents contracted hepatitis B, children born after their mothers acquired it and children born after their fathers acquired it. The above results indicate that hepatitis B patients with HBsAg positive and their children born after they contracted hepatitis B had significantly higher frequencies of SCE; these data might throw new light on the study of genetic factors acting on the mechanism of hepatitis B.     

Effect of hyperthermia on the frequency of sister-chromatid exchanges in patients with cancer of cervix uteri

The frequencies of sister-chromatid exchanges (SCE) were studied in patients with cancer of the cervix uteri and normal controls at 37 degrees C and 40 degrees C. At 37 degrees C the mean frequency of SCE was found to be 8.26 +/- 1.91 in untreated patients with cervical cancer and 7.91 +/- 1.68 in cancer patients treated with radiotherapy; these values were significantly higher than the control value of 5.34 +/- 1.28 exchanges. Increase of the growth temperature to 40 degrees C elevated the SCE frequency to 11.95 +/- 2.12 in patients without radiotherapy treatment, 13.37 +/- 2.17 in patients with radiotherapy treatment and 7.82 +/- 1.84 in normal controls. These data indicate that there is a differential induction of SCEs by hyperthermia in the lymphocytes of control women and patients with cancer of the cervix uteri.     

Sex difference in the saturable binding of low-density lipoprotein by liver membranes in ageing rats

It is well documented that women of child-bearing age tend to have lower serum low-density lipoprotein (LDL) concentrations than men. In order to explore the metabolic basis of this sex difference, we have compared the saturable binding of 125I-labeled LDL (d 1.02-1.05 g/ml) at 37 degrees C by liver membranes from healthy male and female Wistar rats of different ages (15-213 days). Woolf plots of saturable binding curves over the concentration range 15-65 micrograms LDL protein/ml were linear and compatible with a single class of binding sites. Maximum binding capacity (Bmax) was not significantly different in male and female animals of 15-19 days of age (respectively, 0.331 +/- 0.018 vs. 0.427 +/- 0.044 micrograms LDL protein/mg membrane protein, mean +/- S.E.). Thereafter, Bmax increased in females, reaching a peak of 0.635 +/- 0.042 micrograms LDL protein/mg membrane protein at 60 days. As no increase in Bmax occurred in males, values were significantly higher (P less than 0.02) in females than in males (by a mean of 61-117%) at all ages after 30 days. During ageing, serum cholesterol concentration changed reciprocally with Bmax in females (Pearson's correlation coefficient, r = -0.761, P less than 0.01) and remained essentially constant in males. The equilibrium dissociation constant for 125I-labelled LDL binding to the hepatic membranes was unaffected by both age and sex. These results provide evidence that the sex difference in the plasma total and LDL cholesterol concentrations is related, at least in part, to a greater mean LDL receptor density in the livers of females.     

Sister chromatid exchange in lymphocytes from patients with malignant lymphoma

Summary Sister chromatid exchange (SCE) frequencies were studied in differentially stained lymphocytes from 47 patients with malignant lymphoma. Thirteen patients were untreated when studied. The mean SCE frequency [±standard error (SE)] for these patients was 12.7±0.9 per mitosis. The mean score for 40 controls was 6.1±0.3. SCE mean scores were significantly higher in the untreated patients than in the controls (P<0.001). Seven patients were treated with radiotherapy alone. They demonstrated a mean SCE frequency (8.8±0.8) significantly lower (P<0.01) than that found in untreated patients. Eleven patients received cyclophosphamide within 4 weeks prior to study. They demonstrated a mean SCE frequency (14.3±1.3) significantly higher (P<0.05) than that found in patients who had received regimens that did not contain cyclophosphamide in the prior 4 weeks (11.1±1.3) or who had been off drugs for at least 8 weeks (10.1±0.8). Our data suggest that untreated patients with malignant lymphoma have elevated SCE frequencies, which may be further increased by certain chemotherapeutic agents.     

Sister chromatid exchange (SCE) for the first time in Casertana pig breed

Lymphocyte cell cultures from 30 Casertana pigs (13 males and 17 females), reared in southern Italy, underwent the sister chromatid exchange (SCE) test. The Casertana pig is an endangered native breed from the region of Campania, raised chiefly half-wild. In the 1500 cells we studied, the mean SCE was 6.32+/-2.92 and SCE frequency did not follow a Poisson distribution. A higher mean value of SCE cell(-1) was found in the older group (SCE cell(-1)=6.68+/-2.95) compared with the younger (SCE cell(-1)=5.94+/-2.84), the difference being statistically significant (P<0.01). To our knowledge, this is the first investigation in a representative sample of Italian pig breed using the SCE test. Furthermore, this is the first report where the differences found in the mean SCE values were related to age in domestic species.     

Genome instability in the F1-progeny of mice irradiated by ionizing radiation as determined by micronucleus assay

The F1-progeny of BALB/c male mice chronically exposed to low-dose gamma-radiation (0.1; 0.25 and 0.5 Gy; dose rate 0.01 Gy/day) as well as the F1-progeny of females exposed to acute X-radiation (0.5; 1.0 and 2.0 Gy; dose rate 0.1 Gy/min) shown the significant elevated micronuclei frequencies in bone marrow erythrocytes, as compared to the F1-progeny of unirradiated males and females. The increase in the micronuclei frequency in the F1-progeny was determined by the dose of irradiation of parents. The values of elevated micronuclei frequency in the F1-progeny of chronically irradiated males and acutely irradiated females for a dose of 0.5 Gy were comparable. The micronuclei frequencies in the F1-progeny of irradiated females and males for this dose were in 1.5 and in 1.6 times higher than ones in the F1-progeny of unirradiated mice correspondingly. The results suggest the possibility of transfer of genome instability from irradiated parents to the somatic cells of the F1-progeny via non-lethally damaged germ cells of parents.     

Sister-chromatid exchanges in human lymphocytes exposed to 1-p-(3-methyltriazeno)benzoic acid potassium salt

The 1-p-(3-methyltriazeno) benzoic acid potassium salt (MTBA) is a triazeno analogue of dacarbazine, an antineoplastic agent capable of mediating the appearance of new antigenic specificities on cancer cells in mice, a phenomenon described as 'chemical xenogenization' (CX). Recently we reported the clastogenic potential of MTBA on human lymphocytes. Since sister-chromatid exchange (SCE) assay is more sensitive than clastogenic tests, at least at low drug concentrations, we assessed SCE frequencies induced by MTBA on human lymphocytes stimulated by PHA. Drug treatment at 2-500 micrograms/ml was performed in vitro prior to or after PHA addition. SCE values increased significantly in a dose-dependent manner up to 200 micrograms/ml. However, SCE frequencies, as well as chromosome breaks, did not increase dramatically. These data indicate that MTBA concentrations used for CX do not cause severe cytogenetic damage to immune cells at least in vitro.     

Evaluation of genotoxic effects of Apitol (cymiazole hydrochloride) in vitro by measurement of sister chromatid exchange

Apitol, with cymiazole hydrochloride as the active ingredient, is used in bee-keeping against the ectoparasitic mite Varroa destructor. The preparation was evaluated for genotoxicity in cultured human peripheral blood lymphocytes. Sister chromatid exchange, the mitotic index and the cell proliferation index were determined for three experimental concentrations of Apitol (0.001, 0.01 and 0.1 mg/ml). All concentrations significantly (p < 0.001) increased the mitotic index (MI = 7.35+/-0.18%, 8.31+/-0.20% and 12.33+/-0.25%, respectively), the proliferative index (PI = 1.83+/-0.01, 1.84+/-0.01 and 1.88+/-0.02, respectively) and the frequency of sister chromatid exchange (SCE = 8.19+/-1.81, 8.78+/-1.80 and 13.46+/-1.88, respectively), suggesting that cymiazole hydrochloride has genotoxic potential.     

Cytogenetic analysis in workers occupationally exposed to nickel carbonyl

Chromosomal aberration and sister-chromatid exchange (SCE) base-line frequencies and SCE frequencies induced by 10 ng/ml mitomycin C (MMC) were analysed in cultured peripheral lymphocytes of 65 workers occupationally exposed to nickel carbonyl Ni(CO)4. The subjects were divided into 4 groups: (1) control; (2) exposed to nickel carbonyl (= exposed); (3) cigarette smokers; (4) smoking-exposed. The results show that there are no significant differences in chromosomal aberration frequencies, breaks or gaps, between the various groups. However, the SCE base-line frequency of the smoking-exposed group, with an average of 7.7/cell, was significantly higher than that of the control group, with an average of 6.5/cell (P less than 0.01), and also than that of the exposed group with an average of 5.9/cell (P less than 0.01). Similarly, the SCE frequency induced by 10 ng/ml MMC in the smoking-exposed group which averaged 15.5/cell was significantly higher than that of the control group (average of 13.2/cell (P less than 0.05], and also than that of the exposed group with an average of 12.3/cell (P less than 0.01). Under our experimental conditions, it may be that the level of exposure was not high enough to elicit an increase in chromosomal aberrations and SCE frequencies in the non-smoker exposed group. The fact that an increase in SCE frequencies was only found in the smoking-exposed group implies that the two factors, smoking and exposure to nickel carbonyl, are jointly responsible for the result.