Exchanges In Human Lymphocytes Research Articles

Induction of structural chromosome aberrations and sister chromatid exchanges in human lymphocytes in vitro by aristolochic acid.

The medicinal use of Aristolochia clematitis has been known for some time. The main active agent of this medicinal plant is aristolochic acid, a nitrophenanthrenecarbonic acid. Very recently, however, the Federal Health Office withdrew the licence for all drugs containing aristolochic acid, because of the well-founded suspicion that aristolochic acid may be a very potent carcinogen. We investigated the induction of structural chromosome aberrations and sister chromatid exchanges (SCEs) by aristolochic acid in human lymphocytes in vitro. Cells were treated with the agent tested throughout culture time and during the G0 phase of the cell cycle. We tested concentrations over a range of 1 to 20 micrograms/ml. Both treatment conditions resulted in an increased aberration frequency. The induction of gaps and breaks as well as the induction of SCEs showed a dose-dependent increase. The number of SCEs per metaphase was enhanced by a factor of 2 to 3. If conventional cytogenetic methods had been applied in time, one would have recognized the mutagenic risk of aristolochic acid earlier.

Absence of an effect of diagnostic ultrasound on sister-chromatid exchange induction in human lymphocytes in vitro

The frequency of sister-chromatid exchanges in human lymphocytes cultured in vitro was not changed after a 30-min exposure to a 2 MHz focused, diagnostic ultrasound beam with a pulse repetition rate of 1000 Hz, 1 μsec burst duration, 100 W/cm 2 temporal peak, spatial peak intensity. These results are consistent with those obtained with a number of other cell types and are contrary to some previously reported effects for human lymphocytes.

Induction of sister-chromatid exchanges in human lymphocytes by indirect carcinogens with and without metabolic activation

Sister-chromatid exchanges (SCEs) were examined in cultured human lymphocytes after exposure for 1 h to aflatoxin B 1 (AFB 1), Trp-P-1, Trp-P-2, dimethylnitrosamine (DMN), diethylnitrosamine (DEN) and benzo[ a]pyrene (BP) with and without a metabolic activation system (S9 mix). With metabolic activation, all the carcinogens produced significant and dose-dependent increases in SCE frequency. However, the molar concentrations that induced a 2-fold increase in SCEs per cell over the control level were distributed over a range of more than 10 4. Without metabolic activation, AFB 1, at 10 −4 M, caused a significant increase in SCE induction, whereas the other compounds caused little or no increase in SCE frequency above the control levels.

Induction of sister-chromatid exchanges in human lymphocytes by Aldicarb, Thiofanox and Methomyl

Induction of sister-chromatid exchanges in human lymphocytes by Aldicarb, Thiofanox and Methomyl

Induction of sister-chromatid exchanges in human lymphocytes by microsomal activation of benzene metabolites

Metabolic activation of the benzene metabolites, catechol, hydroquinone, and phenol, by rat-liver microsomes and an NADPH-generating system (S9 mix) caused an increased induction of sister-chromatid exchanges (SCEs) in cultured human lymphocytes. There were different optimal concentrations of S9 mix for converting each benzene metabolite into further reactive forms that could induce SCE-forming lesions. The data indicate that catechol and hydroquinone can be optimally metabolized to produce reactive species, presumably benzo(semi)quinones, under conditions of lower metabolic activity than those necessary for phenol and benzene.

Influence of mitogens on the yield of chemically induced sister-chromatid exchanges in human lymphocytes

Influence of mitogens on the yield of chemically induced sister-chromatid exchanges in human lymphocytes

The effect of smoking on the frequency of sister-chromatid exchange in human lymphocytes

The effect of smoking on the frequency of sister-chromatid exchange in human lymphocytes

The effects of temperature and ouabain on steady-state Na and K exchanges in human lymphocytes.

AbstractThe temperature‐dependence of steady‐state exchanges of K and Na were determined under conditions in which cell viability, ATP, water, Ca, and Mg were not confounding variables. Steady‐state ion contents are near‐normal between 37° and 10° C, Below 10° C K is replaced by Na in a mole‐for‐mole fashion with significant net K retention and Na exclusion occurring even below 3°C. The rates of steady‐state Kand Na exchanges have markedly different temperature‐dependences; between 37° and 10° C, for example, that of K decreases markedly while that of Na remains near‐normal, and there is no consistent correlation between the steady‐state exchanges and the ionic contents. Ouabain increases steady‐state Na flux at 37° C and induces a more marked temperature‐dependence over the entire temperature range. This effect is not due simply to inhibition of some processes and unmasking others; it mirrors a pronounced effect of ouabain on the intrinsic properties of Na self‐exchange. These results are compatible with a model based on two simple concepts: (1) partial ionic exclusion from cellular water that is ordered by interaction with proteins; and (2) ionic accumulation mediated by adsorption onto and desorption from fixed macromolecular anionic sites, the majority of which interact with one another in a cooperative fashion. In this view, the sharp temperature transition in the net replacement of K by Na below 10° C is due to a critical transition in the selectivity of the cooperatively interacting adsorption sites. The rates of steady‐state self‐exchanges of K and Na are determined by parameters of ion‐site interaction, and the major set of ion‐adsorbing sites that interact cooperatively have a steep thermal activation energy of ionic self‐exchange. When they are in the K‐preferring state above 10° C, exchange of K has a steep temperature‐dependence. When they are in the Na‐preferring state below 10° C, exchange of Na has a steep temperature‐dependence. When these sites are forced into a Na‐preferring state at all temperatures by treatment with ouabain, exchange of Na acquires a steep temperature‐dependence over the entire temperature range 37° to 0° C.

Sister chromatid exchanges in human lymphocytes exposed to single cytotoxic drugs in vivo or in vitro

Venous blood was taken from apparently healthy volunteers and patients with cancer, the latter both before and at intervals after treatment with single cytotoxic drugs. Cells from untreated individuals were exposed to a range of concentrations of drugs in culture medium. Chlorambucil, treosulfan and cyclophosphamide (activated by hepatic microsomes) significantly increased the numbers of SCEs, both in vitro and in the lymphocytes of patients. While methotrexate and 5-fluorouracil had no effect, bleomycin slightly increased the number of SCEs, but only in vitro. Although the in vitro dose-effect relationship indicated which drugs would increase the frequency of SCE in vivo, the magnitude of the response tended to be overestimated. When patients were treated with drugs the frequency of SCE increased, then declined with time. Though this complicates the quantitative relationship betwen dose and damage, SCEs may be useful to monitor the effects of alkylating agents on normal tissues.

The frequency of sister-chromatid exchanges in human lymphocytes treated with some methylindoles

The frequency of sister-chromatid exchanges in human lymphocytes treated with some methylindoles

A schedule to demonstrate radiation-induced sister chromatid exchanges in human lymphocytes.

The reciprocal interchange between the chromatids of a chromosome, termed sister chromatid exchange (SCE), is considered to be one of the most sensitive and accurate cytogenetic parameters and respond to toxic chemicals at very low doses. But the response of SCE to ionizing radiation is very poor. Human lymphocytes fail to give SCE response when irradiated at G0. Probably the primary lesions induced at G0 do not remain available long enough to find expression as SCEs. Based on this assumption a schedule was developed using caffeine to demonstrate radiation induced SCEs. Following this schedule a dose-dependent increase in the frequency of radiation induced SCEs has been observed.

Induction of sister-chromatid exchanges in human lymphocytes by extracts of particulate emissions from a diesel engine

Particulate matter was collected from the emissions of a diesel-powered engine and the organic components were extracted. The extract induced a dose-related increase in sister-chromatid exchanges in human lymphocytes with a potency of about one-fifth that of benzo[ a]pyrene.

Sister chromatid exchanges in human lymphocytes treated with combinations of cytotoxic drugs

Lymphocytes from peripheral blood of either ‘normal’ donors or patients with cancer were stimulated to divide in culture medium containing 5-bromo- 2′-deoxyuridine. During 74 hr of incubation, the cells were exposed to single agents or to permutations of two combinations of chemotherapeutic drugs, namely MOPP or cyclophosphamide and methotrexate. Only mustine and cyclophosphamide (activated and not activated) increased the frequency of sister chromatid exchanges (SCE). Neither vincristine, procarbazine or prednisolone with mustine, nor methotrexate with cyclophosphamide altered the number of SCEs expected from the use of mustine or cyclophosphamide alone. There was no difference in the response of cells from cancer patients and ‘normal’ subjects to the drugs. If the drugs of these two regimens do interact with one another to enhance the amount of subcellular damage, this is not manifested by changes in the number of SCEs in human lymphocytes in vitro.

Anti-tumour alkylating agents act synergistically with methylxanthines on induction of sister-chromatid exchange in human lymphocytes

Anti-tumour alkylating agents act synergistically with methylxanthines on induction of sister-chromatid exchange in human lymphocytes

The effect of metabolic inhibition on ion contents and sodium exchange in human lymphocytes.

Lymphocytes depleted of ATP by incubation in iodoacetate (IAA) and nitrogen (N2) lost K and gained Na. Isotopic Na exchange showed a fast fraction and a slower exponential fraction, the latter conventionally assumed to reflect surface membrane properties. The gain of cell Na was not accounted for by a decrease in 22Na efflux in either the slow or the fast fraction. After 3-5 hours, Na efflux increased. These results led us to question the concept that normal cell ion levels are maintained by an ATPase pump and could not be explained by exchange diffusion, co-transport, countertransport, or other inherently dissipative mechanisms. The data are, on the other hand, consistent with the concept that cell ion contents are determined by their relative exclusion from cell water coupled with selective adsorption onto fixed macromolecular anionic sites within the cell. In this view, the IAA,N2-induced rise in cell Na is due to the occupancy of adsorption sites losing K, while the increased isotopic exchange is due to a decreased activation energy for ion-site interaction.

Induction of sister-chromatid exchange in human lymphocytes by smoke condensates from different brands of cigarette

(Accepted 10 June 1981) Cigarette-smoke condensate contains over 1200 chemical entities (Schmeltz et al., 1974), many of which are known or suspected carcinogens (Weisburger et al., 1977). The mutagenicity of cigarette-smoke condensate has been shown in several short- term test systems, e.g. in bacterial tests (Hutton and Hackney, 1975; Kier et al., 1974; Sato et al., 1977) and in cytogenetic assays (de Raat, 1979; Hopkin and Evans, 1979). However, it has become evident that the mutagenicity of the tar is not only due to polycyclic aromatic hydrocarbons (Hopkin and Perry, 1980; Mizusaki et al., 1977), but rather to other mutagenic agents, e.g. pyrolysis products of amino acids (Yoshida and Matsumoto, 1980). Thus, the content of tar in different brands of cigarette may not be the major variable determining the mutagenicity of different types of cigarette. In the present work, the mutagenic activity in different types of cigarette-smoke condensate was evaluated by using the sensitive sister-chromatid exchange (SCE) analysis in cultured human lymphocytes. The smoke condensates were made from 6 commercially available cigarette brands (Table 1) by using the Filtrona 302 smoking machine (Filtrona Int., Great Britain). Cambridge type cigarette holders were used, and the condensates were trapped on Cambridge glass-fibre filters, by using standard 2-sec 35-ml puffs once each 60 sec. The butt length depended on the length of the filter so that with filtered cigarettes (A, B, C) the butt length was 28 mm and with non-filter cigarettes (D, E, F) it was 23 mm. The tars were extracted with 60 ml cyclohexane (p.a., Merck AG), and each sample was evaporated to dryness in liquid nitrogen and dissolved (25.0 mg tar/ml) in dimethyl sulphoxide (DMSO, p.a. Fluka AG) (Table 1). Heparinized venous blood of one healthy male donor was used in the experiments. Whole-blood lymphocyte cultures, containing bromodeoxyuridine (BrdU, Calbiochem), 5.0 #g/ml, were established and harvested according to routine methods of the laboratory (Norppa et al., 1980). 0165-7992/82/0000-0000/$02.75 © Elsevier Biomedical Press

Ethylene oxide induced sister chromatid exchange in human lymphocytes using a membrane dosimetry system.

In an earlier study, we demonstrated that human exposure to ethylene oxide (EO) during sterilization procedures was associated with increased sister chromatid exchanges (SCE) in cultured peripheral blood. To study further toxic and mutagenic properties of EO in vitro, we devised a membrane dosimetry system which can be used to expose lymphocytes in peripheral blood to specified amounts of EO. The system consists of an exposure chamber, cell culture dishes to which are applied plastic membranes of varying diameters and an infrared analyzer used to monitor ambient EO concentrations in the system. Aliquots of EO-exposed media were subjected to gas chromatography for quantitation. Our preliminary analyses of the cultured cells indicate that the membrane dosimetry system we developed is capable of reproducibly delivering quantities of EO to target cells. Elevated SCEs were observed at as little as 10 micrograms/ml (in media) during a 20-min exposure period. A significant dose-response relationship between SCE and EO dose was recorded up to 35 micrograms/ml, the highest dose tested. Lymphocytes at 35 micrograms/ml showed a fourfold increase in SCE compared to control cultures. We conclude that the membrane dosimetry system provides a reproducible method to investigate EO mutagenesis in human cells in vitro and may prove applicable to a wide range of mutagenic gases.

Sister-chromatid exchanges in human lymphocytes treated with 4-chloromethylbiphenyl and benzyl chloride

At non-inhibitory concentrations, 4CMB and BC both induced small, but dose-related increases in SCE. The dose-response curves gave a highly significant correlation for 4CMB ( r=0.996, P<0.001) and a significant correlation for BC ( r=0.757, P<0.05) which reflects the relative activities of these substances in bacterial mutation tests.

The effects of patulin and patulin-cysteine mixtures on dna synthesis and the frequency of sister-chromatid exchanges in human lymphocytes

The effects of patulin and patulin-cysteine mixtures on DNA synthesis in human blood lymphocytes were measured by assaying incorporation of [ 3H]thymidine into cellular DNA. Patulin inhibited and patulin-cysteine mixtures stimulated the incorporation of [ 3H]thymidine into DNA. The inhibitory action of patulin diminished with time in culture. Patulin was found to be unstable in the culture medium. The sister-chromatid exchange (SCE) frequency was significantly elevated by intermediate concentrations (0.1–0.2 μg/ml culture) of the toxin. The cells are protected from the effect at low concentrations of the toxin. There may be excessive damage at higher concentrations but only the unaffected cells go into mitosis. Therefore an increased frequency of SCEs is detected only at intermediate concentrations, or. at higher concentrations, with early harvesting. Cysteine seems to potentiate the effect of patulin on SCE frequency.

Induction of Sister Chromatid Exchanges in Human Lymphocytes by Trihalogenated Methanes

Induction of Sister Chromatid Exchanges in Human Lymphocytes by Trihalogenated Methanes