Increase of sister chromatid exchanges in excision repair deficient xeroderma pigmentosum

Summary The distribution of spontaneous sister chromatid exchanges (SCEs) was studied in PHA-stimulated lymphocytes from 15 patients affected by xeroderma pigmentosum (XP). The study of unscheduled DNA synthesis (UDS) in twelve of these patients showed that seven were deficient and five proficient. The number of SCEs in XP patient cells was higher than in those of 19 controls, and the distributions of SCEs per cell were significantly different. However, the results varied when XP patients were considered in relation to their UDS: the group of XP patients with proficient UDS did not differ, whereas the group of XP patients with deficient UDS was very significantly different from controls. The group not tested for UDS was similar to the deficient UDS group. The possible relationship between the increase of SCEs and the type of DNA repair defect is discussed.     

Cell-stage dependence of mutagen-induced sister-chromatid exchanges in human lymphocyte cultures

The induction of sister-chromatid exchanges (SCEs) was studied in phytohemagglutinin (PHA)-stimulated human lymphocytes exposed for 1 h to mitomycin C (MMC, 3 X 10(-6) M), ethyl methanesulphonate (EMS, 2 X 10(-2) M), or 4-nitroquinoline-1-oxide (4NQO, 3 X 10(-5) M) at various cell-cycle stages of 72-h cultures. The doses of the chemical were chosen to give about 20 SCEs per cell when treated at Go. The SCE frequency increased almost linearly with MMC or EMS treatments at later times after PHA stimulation, peaking with those at 36 h (at around the first G1/S boundary in the 2 consecutive cell cycles, which was revealed by concomitant experiments), and then decreased with subsequent treatment times. Cell-cycle kinetics and the cell stages at which the cells were treated were measured by autoradiography and sister-chromatid differential staining. The data show that MMC and EMS produce larger numbers of SCEs when treated at stages closer to the beginning of S, and that the most efficient time of treatment is the G1/S boundary in the first cell cycle of the two consecutive cycles before sampling. Pulse treatment with EMS caused about 3 times larger inductions of SCEs when done at late G1/early S(G1/S boundary) in the first cell cycle compared to that at G0/early G1, whereas identical exposure to MMC at the first G1/S boundary produced only 1.5 times larger numbers of SCEs than that at G0/early G1. EMS and MMC both, however, induced 30-40% larger numbers of SCEs when treated at the G1/S boundary in the first cell cycle than when treated at the second cell cycle before sampling. On the contrary, treatment with 4NQO led to the induction of about the same numbers of SCEs even when treated at different cell-cycle stages before the second G1/S boundary. The SCE frequency in 4NQO-treated cells then decreased with subsequent treatment times.     

Distribution of sister chromatid exchanges in chromosomes of normal Chinese hamster and its cell lines exposed to BrdU and MMC

Sister chromatid exchanges (SCEs) were investigated in chromosomes from normal male Chinese hamster (CH) and its cell lines (CHW, 1102 and 1103). The fibroblasts were grown for two replication cycles in medium containing BrdU and mitomycin C (MMC) at concentrations of 0.01, 0.02 and 0.03 micrograms/ml of medium. The difference in SCEs/cell between male CH and CHW was negligible, but the difference between CHW and 1102 was about 2.6-fold. It is suggested from karyotypic differences between CHW and 1102, that the control of SCEs might be due partly or completely to chromosome 5 in Chinese hamster. The lines CHW and 1102 were less responsive than normal Chinese hamster cells when exposed to different MMC concentrations. It is suggested that the lines CHW and 1102 might be slightly resistant to MMC. The frequency of SCEs decreased with the decrease of chromosome size. SCEs are not preferentially distributed on any autosomal chromosomes. No SCEs were found in normal X-chromosomes. The majority of exchanges appear to be either interband regions or very near band-interband junctions.     

Ultraviolet light and mitomycin C induced sister-chromatid exchanges in fibroblasts from patients with retinoblastoma

Ultraviolet light and mitomycin C (MMC) induced sister-chromatid exchanges (SCEs) were investigated in 6 diploid fibroblast strains derived from 3 patients with deletion 13 and retinoblastoma, one patient with a hereditary form of retinoblastoma, one patient with trisomy 13, and one normal control. Two fibroblast strains with del(13)(q14q22) showed a significant increase in SCEs compared to the control after UV and MMC treatments. In contrast, cell strains with del(13)(q12q14) and trisomy 13 did not show increased SCEs. The frequency of SCEs in fibroblasts from a patient with autosomal dominant retinoblastomas (no deletions) was significantly increased by UV, but not by MMC. The results suggest that cell strains with different deletions of chromosome 13 have different SCE responses to UV and MMC inductions. The cells with del(13)(q14q22) may have a DNA-repair defect.     

Differential sensitivity of peripheral blood lymphocytes of untreated leprosy patients to mitomycin C

The effects of a bifunctional alkylating agent mitomycin C (MMC), an effective inducer of chromosome aberrations and sister-chromatid exchanges (SCEs), have been studied in untreated leprosy patients. This was done to study the mutagen sensitivity of the leprosy patients. The frequency of chromosomal aberrations induced by MMC (conc. 0.01 microgram/ml) was 2.5% in controls, 3.6% in paucibacillary (PB), and 6.8% in multibacillary (MB) patients. The difference in the frequency of MMC-induced chromosome aberrations between the 3 groups studied was highly significant (p less than 0.01). Cultures grown with MMC showed the frequency of SCEs/cell to be 12.70 +/- 1.19 in controls, 19.97 +/- 3.51 in PB, and 29.66 +/- 5.92 in MB patients. The differences in the frequency of MMC-induced SCEs between the 3 groups were found to be highly significant (p less than 0.01). The enhanced frequencies of spontaneous and MMC-induced chromosome aberrations and SCEs observed in PB and MB patients indicate a clear differential mutagen sensitivity between PB and MB patients who are known to have different immunological status and thereby differ in the severity of the disease.     

The ability of bifunctional and monofunctional pyrrole compounds to induce sister-chromatid exchange (SCE) in human lymphocytes and mutations in Salmonella typhimurium

The ability to induce sister-chromatid exchange (SCE) in human lymphocytes and mutations in Salmonella typhimurium has been assessed for 4 pyrrole compounds. Three of the compounds, 2,3-bishydroxymethyl-1-methylpyrrole (BHMP), 2-hydroxymethyl-1-methylpyrrole (2HMP) and 3-hydroxymethyl-1-methylpyrrole (3HMP) are synthetic pyrrolic alcohols; the fourth compound, dehydroretronecine (DHR) is a metabolite of several naturally occurring pyrrolizidine alkaloids. The activity of these compounds was compared with that of mitomycin C (MMC) and decarbamoyl mitomycin C (DCMMC), chemicals related structurally to the pyrrole compounds. All 6 compounds caused an increase in the numbers of SCEs. Whereas the bifunctional pyrroles, DHR and BHMP, and the mitomycins, MMC and DCMMC, increased levels of SCEs by 8-12 times control levels, the monofunctional pyrroles gave increases of only 2 times. Three of the 4 pyrrole compounds (DHR, BHMP and 3HMP) induced mutations in the Salmonella typhimurium base substitution strain TA92, the fourth (2HMP) was not found to be mutagenic in any of the 8 strains used. The mitomycins induced mutations in the frameshift strain TA94 in addition to the base substitution strain TA92, with DCMMC always more mutagenic and less cytotoxic than MMC. All bifunctional compounds induced more mutations and were less cytotoxic in strains containing an efficient excision-repair system. With the pyrrole compounds numbers of SCEs and mutations were only increased when using chemical concentrations significantly higher than those required for the mitomycins: more than twice as high to produce significant numbers of SCEs and more than 100 times as high to produce equal numbers of mutations.     

Effects of temperature on chemically induced sister-chromatid exchange in human lymphocytes

Lymphocytes from healthy adults were studied for sister-chromatid exchanges (SCEs) when pulse-treated in G0 with mitomycin C (MMC), ethyl methanesulfonate (EMS), or 4-nitroquinoline N-oxide (4NQO) at various temperatures ranging from 0 degrees C to 41 degrees C and then cultured in medium containing 5-bromodeoxyuridine at 37 degrees C. The results showed that the frequencies of SCEs induced by MMC or EMS varied according to the treatment temperature. In MMC- or EMS-exposed cultures, the SCE frequency increased continuously with increasing treatment temperature; treatment at 37 degrees C resulted in a 3-4 times greater induction of SCEs than did that at room temperature (25 degrees C). On the other hand, SCE frequencies in cells exposed to 4NQO remained within normal deviation, showing no temperature-dependent changes. Baseline SCE frequencies remained almost constant within the temperature range tested. These data indicate that treatment temperature is a very critical factor in determining the sensitivity of cells to the chemical induction of SCEs.     

DNA crosslinking, sister-chromatid exchange and specific-locus mutations

Chinese hamster ovary cells were treated with the DNA-crosslinking chemicals, mitomycin C (MMC) and porfiromycin (POR), and their monofunctional derivative decarbamoyl mitomycin C (DCMMC). After exposure, the cells were studied for the induction of sister-chromatid exchanges (SCEs) and mutations at the hypoxanthine phosphoribosyltransferase and adenine phosphoribosyltransferase loci. The frequency of SCEs varied significantly in successive sampling intervals, requiring the weighting of each interval by the percentage of second-division mitosis in that interval to obtain the mean SCE frequency for each dose. All 3 compounds were potent inducers of SCEs but weakly mutagenic. All 3 chemicals by concentration were approximately equally effective in inducing SCEs or mutations. When the induced SCEs and mutations were compared at equal levels of survival, DCMMC was slightly more effective than MMC or POR in inducing SCEs and somewhat less mutagenic. These results indicate that the DNA interstrand crosslink is not the major lesion responsible for the induction of SCE or mutation by these compounds.     

Harlequin banding and localisation of sister-chromatid exchanges.

Harlequin banding (HB) was standardised on Indian muntjac chromosomes by superimposing harlequin staining or sister-chromatid differentiation and G-banding after incorporation of bromodeoxyuridine (BrdU) or cholorodeoxyuridine (CldU), and after treatment with BrdU plus mitomycin C (MMC). SCEs were localized on these chromosomes with the aid of the G-band map. There were more SCEs in G-bands than in R-bands in BrdU-incorporated chromosomes. CldU-incorporated chromosomes, however, did not show a preferential localization of SCEs in either G- or R-bands. When BrdU + MMC-induced SCEs were localized in harlequin-banded chromosomes, there was a significantly greater number of SCEs in R-bands; and there was a concomitant reduction in the frequency of SCEs in G-bands, as compared to the SCEs observed in this region after BrdU incorporation alone. Centromeric regions of chromosomes 1 and X had preferred sites for occurrence of SCEs in BrdU-incorporated chromosomes, the preferred sites being more in G-bands after BrdU and CldU incorporation and in R-bands after treatment of BrdU-incorporated chromosomes with MMC. Thus the formation of SCEs is not restricted by structure per se as defined by euchromatin or heterochromatin, but depends on the site of lesion production, type of lesion and repair pathway followed.     

SCE frequencies in lymphocytes of systemic lupus erythematosus patients

The frequency of sister-chromatid exchanges (SCEs) was investigated in peripheral lymphocytes of lupus erythematosus patients and compared with values obtained for healthy controls. Irrespective of the kind of medical treatment, an increased level of spontaneously occurring SCEs could be demonstrated in lupus patients. In addition to spontaneously occurring SCEs, mitomycin C (MMC)-induced SCEs were evaluated. No difference between patients and controls was found with respect to MMC-induced SCEs.     

Influence of various mitogens on the yield of sister-chromatid exchanges, induced by chemicals, in human lymphocytes

The fluorochrome-plus-Giemsa (FPG) method of Perry and Wolff was used to compare the frequencies of sister-chromatid exchanges (SCEs) induced by cyclophosphamide (CP) or mitomycin C (MMC) in human lymphocytes stimulated by phytohaemagglutinin (PHA), concanavalin A (Con A), Wistaria floribunda (WFA), or lentil lectin (LcH-A) extracts. These 4 mitogens, differing in lectin valency and/or sugar specificity, are considered as activating primarily thymus-derived (T) lymphocytes. Regardless of the mitogen used, control cultures displayed a mean yield of about 8 SCEs/cell. A contact, of 1 h, with mitomycin alone or with cyclophosphamide and enzymatic activation, resulted in a significant augmentation of SCEs dependent on the mitogen used. An approximately 2-fold, 4-fold, or 6-fold increase in SCEs was observed for the cultures stimulated by PHA, Con A, and WFA or LcH-A respectively. Furthermore, there were mitogen-dependent differences in mitotic indices and cell-cycle kinetics in human lymphocytes harvested 72 h after stimulation.     

Mitomycin C-induced sister chromatid exchange in X chromosomes of Bovidae

Sister chromatid exchanges (SCEs) in early- and late-replicating X chromosomes of seven female cattle (Bos taurus L.) and five female river buffalo (Bubalus bubalis L.) were studied in untreated lymphocytes and lymphocytes treated with mitomycin C (MMC). In the experiment, 577 SCEs on X chromosomes of MMC-untreated cells and 825 SCEs on X chromosomes of MMC-treated cells from both species were observed. No significant differences between the number of SCEs in early- and late-replicating X chromosomes were found even when singular species and subjects were considered.     

EFFECTS OF DAY AND NIGHT TEMPERATURE AND TYPE OF CONTAINER ON THE GROWTH OF F1 HYBRID ANNUALS IN CONTROLLED ENVIRONMENTS

The effects of three day/night temperatures (18/12 C, 24/18 C, and 30/24 C), and two types of containers (clay and plastic) on the seedling growth of three F₁ hybrid annuals were determined after 14 days of controlled-environment treatment. A day/night temperature of 18/12 C was severely limiting to the early seedling growth of ‘Blue Blazer’ ageratum (Ageratum houstonianum Mill.), ‘Pink Cascade’ petunia (Petunia hybrida Vilm.), and ‘Double Eagle’ marigold (Tagetes erecta L.). Raising the day/night temperature to 24/18 C resulted in striking increases in growth in both clay and plastic pots. Fresh and dry weights of tops for all three species were increased four- to fivefold, and leaf areas of ageratum and petunia were increased more than fivefold irrespective of container. Height and node number were also increased significantly but to a much lesser degree. A day/night temperature of 30/24 C appeared to be optimum for early seedling growth of F₁ hybrid annuals the optimum being based on dry matter accumulation, stem elongation, node development, and leaf area production. Growth of lateral shoots was greatly stimulated at 30/24 C, especially in marigold. There were no appreciable differences in fresh or dry weight of tops or in leaf area between plants in clay and plastic containers at any of the three day/night temperatures.     

Enhancement by methylxanthines of sister-chromatid exchange frequency induced by cytostatics in normal and leukemic human lymphocytes

The effect of theobromine (TB) and diphylline (DP) or (1,2-dihydroxy-3-propyl)theophylline on SCE rates induced in vitro by mitomycin C (MMC), and the effect of caffeine on SCE rates induced in vitro by cytosine arabinoside (Ara-C) was studied. The combined treatments with MMC plus TB or DP showed the potentiating ability of the latter drugs. Caffeine also enhanced SCEs induced by Ara-C in cultured human lymphocytes. Caffeine and adriamycin (ADR) did not act synergistically on induction of SCEs. In a combined study, in vivo and in vitro, lymphocytes taken from 2 leukemic patients who had been given chlorambucil (CBC) or Ara-C by injection 3 h before, and then treated with caffeine in vitro, were found to have synergistically increased exchange frequencies.     

Dependency of the yield of sister-chromatid exchanges induced by alkylating agents on fixation time. Possible involvement of secondary lesions in sister-chromatid exchange induction

Chinese hamster V79 cells were pulse-treated (for 60 min) with various mutagens three, two or one cell cycles before fixation (treatment variants A, B and C, respectively) and the frequencies of induced SCEs were analysed and compared. The degree of increase in frequency of SCEs with dose in the treatment variants depended on the mutagen used. For the methylating agents MNU, MNNG and DMPNU, high yields of SCEs were obtained in the treatment variants A and B, and there was no difference in the efficiency with which these agents induced SCEs in these treatment variants. In the treatment variant C, however, no SCEs were induced with mutagen doses yielding a linear increase in SCE frequency in treatment variants A and B. A slight increase in SCE frequency in treatment variant C was observed only when relatively high doses of MNU or MNNG were applied. Like the above agents, EMS, ENU and MMS induced more SCEs in treatment variants A and B than in C, but for these agents treatment variant B was most effective and SCEs were induced over the entire dose range, also in treatment variant C. As opposed to the methylating and ethylating agents, MMC induced SCEs with high efficiency when treatment occurred one or two generations prior to fixation. There was no difference in SCE frequency between these treatment variants. MMC was completely ineffective for the induction of SCEs when treatment occurred three generations before fixation. The unexpectedly low SCE frequencies induced by the methylating and ethylating agents when treatment occurred one generation before fixation were not due to the exposure of cells to BrdU prior to mutagen treatment. From the results obtained, it is concluded that DNA methylation and ethylation lesions give rise to SCEs only with very low probability during the replication cycle after the lesion's induction, and that subsequent lesions produced during or after replication of the methylated or ethylated template (secondary lesions) are of prime importance for SCE formation after alkylation. For MMC, however, primary lesions seem to be most important for SCE induction.     

Repeated measurement of spontaneous and clastogen-induced sister-chromatid exchange

Sister-chromatid exchanges (SCE), both spontaneous and chemically-induced [blomycin (BLM), mitomycin-C (MMC), streptonigrin (SN), and 4-nitroquinoline-1-oxide (4NQO)], were studied in the lymphocytes of 24 normal individuals on 2 or 3 different occasions, separated by periods of up to 2 years. For all BLM-induced SCEs, the variation in SCE frequency among the samples from a single individual was significantly greater than the variation between replicate cultures on a given day. These results raise questions concerning the validity of conclusions based on a single observation of chemically-induced SCEs.     

Kwaliteit van leven bij dementie

Different definitions of quality of life (QOL) are found in the literature. This raised the question which domains are viewed as really important by persons with dementia. In an explorative study the opinions of persons with dementia (community-dwelling and living in nursing homes), were compared to those of professional carers and instruments for QOL in dementia. Data were gathered through interviews, focus groups and literature study. Most QOL-domains mentioned as important by persons with dementia were also acknowledged by carers and in measurement instruments. Some domains, however, were not mentioned by the carers (‘sense of aesthetics’, ‘financial situation’, ‘being useful’ and ‘spirituality’), or not selected in the measuring instruments (‘security and privacy’, ‘self-determination and freedom’, ‘being useful’ and ‘spirituality’). This indicates differences in perspectives on quality of life between persons with dementia, professional caregivers and researchers. Subsequently it was studied to what degree professionals focus on the QoL-domains that persons with dementia consider essential. Caregivers working on 29 units and 3 day care facilities of 13 nursing homes and in 12 meeting centers filled out a questionnaire (N=374). They reported to focus at least to some degree on most domains considered important by persons with dementia. However, little attention was paid to the domains ‘financial situation’ and ‘being useful’. Professionals offering daytime activities focused more than 24-hour care staff on ‘attachment’, ‘enjoyment of activities’, ‘sense of aesthetics’, and ‘being useful’ This article is a translation and merging of 1) Dröes et al. Quality of life in dementia in perspective; an explorative study of variations in opinions among people with dementia and their professional caregivers, and in literature. Dementia: The International Journal 2006; 5 (4): 533–558, and 2) Gerritsen et al. Differences in perspective: do professional caregivers focus on the Quality of life domains that are important for people with dementia? American Journal of Alzheimer’s Disease and Other Dementias 2007; 22:176–183.     

Repeated measurement of spontaneous and clastogen-induced sister-chromatid exchange.

Sister-chromatid exchanges (SCE), both spontaneous and chemically-induced [bleomycin (BLM), mitomycin-C (MMC), streptonigrin (SN), and 4-nitroquinoline-1-oxide (4NQO)], were studied in the lymphocytes of 24 normal individuals on 2 or 3 different occasions, separated by periods of up to 2 years. For all BLM-induced SCEs, the variation in SCE frequency among the samples from a single individual was significantly greater than the variation between replicate cultures on a given day. These results raise questions concerning the validity of conclusions based on a single observation of chemically-induced SCEs.     

Prevention by tiopronin (2-mercaptopropionyl glycine) of methylmercuric chloride-induced teratogenic and fetotoxic effects in mice

Previous investigations (Fuyuta et al., '76, '79) have shown that a single oral administration of 25 mg/kg methylmercuric chloride (MMC) to pregnant ICR mice on day 10 of pregnancy induced cleft palate in a remarkably high incidence in fetuses. Based on these findings, the present study dealing with the prevention of cleft palate by Tiopronin, (2-mercaptopropionyl glycine, Tp), was initiated. Twenty females in the positive control group were given 25 mg/kg MMC orally on day 10 of pregnancy and then given physiological saline intraperitoneally. Twenty females in the negative control group were given distilled water orally and then given saline intraperitoneally. Cleft palate was found in 98.1% of fetuses in the positive control group and none of them in the negative control group. Twenty females were pretreated with a single oral dose of 25 mg/kg MMC on day 10 of pregnancy and were posttreated with Tp intraperitoneally, immediately and at every 24, 48 and 72 hours after the MMC treatment. The doses of Tp were 320, 160 and 80 mg/kg/day. The incidences of cleft palate in fetuses were reduced to 1.49, 31.3 and 47.8% in the Tp-treated groups with the doses of 320, 160 and 80 mg/kg/day, respectively. Tiopronin could effectively prevent the expected incidence of cleft palate. Other types of abnormalities as well as fetotoxicity represented by reduced fetal body weight were also effectively prevented with the Tp-treatment.     

Mitomycin-C-induced sister-chromatid exchanges and cell-cycle kinetics in lymphocytes from patients with Klinefelter syndrome

The chromosomal sensitivity to mitomycin-C (MMC) and cell-cycle kinetics in cells from patients with Klinefelter syndrome, a sex chromosomal disorder giving a high risk of malignant tumor, were studied by techniques of sister-chromatid exchanges (SCEs). The frequencies of MMC-induced SCEs increased in proportion to the increase in MMC concentration in both patient and normal control cells. At low levels of MMC there were no significant differences in SCE frequencies between the patient and normal control cells, but at MMC concentrations of 3 X 10(-8) M (p less than 0.05) and 1 X 10(-7) M (p less than 0.01), significant increases in the frequency of MMC-induced SCEs were observed in cells from patients compared to cells from normal controls. Although the analysis of cell-cycle kinetics both after various culture times and after treatment with MMC revealed that there were no significant differences between the patient and normal control cells, patients with Klinefelter syndrome showed a tendency to cell-cycle delays after treatment with MMC in comparison with normal controls.