Frequency Of Satellite Associations Research Articles

Frequency of Satellite Associations of Acrocentric Chromosomes in Oral Squamous Cell Carcinoma Patients after 5-FU and Cisplatin Treatments

Oral squamous cell carcinoma is one of the most prevalent diseases worldwide. Acrocentric (D and G groups) satellite associations are known to play important role in the pathogenesis of diseases including cancers. The present work was aimed to study the frequency of satellite association (SA) in human peripheral blood lymphocytes of freshly diagnosed oral squamous cell carcinoma patients. Study was also carried out with in vitro combined treatments of anticancer drugs namely 5- Flurouracil (5-FU) and Cisplatin to note changes in frequency of SA. A Results revealed a significant impact of combined treatments of chemotherapeutic agents on the frequency and pattern of satellite associations.

A Study of Anticancer Drug Treatment on Satellite Associations in Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma is one of the most prevalent diseases worldwide. Satellite associations are known to play an important role in the pathogenesis of certain diseases including cancer . The present work aimed to study the frequency of satellite association in human peripheral blood lymphocyte culture of freshly diagnosed oral squamous cell carcinoma patients. In vitro anticancer drugs (5-Fluorouracil {5-FU } and Cisplatin) were studied for the frequency of satellite association. Results showed significant impact of chemotherapeutic agents on the frequency of satellite associations of dif ferent groups of acrocentric chromosomes.

Smoking-induced satellite associations in a rural population of south India: An in vitro study

Background:Genotoxic carcinogens in cigarette smoke interact with DNA, causing cytotoxicity. Cytogenetic damage therefore seems to be an excellent biomarker for determining the effect of exposure to chromosome-damaging agents in cigarette smoke.Purpose:To study the utility of measurement of frequency of satellite associations (SA) as a biomarker for chromosomal damage using cytogenetic assay in peripheral blood lymphocytes.Materials and Methods:This study was conducted on 30 smokers and 30 nonsmokers drawn from a rural population of South India. Smokers were divided into three groups of ten each based on their smoking index (SI) (group I: SI < 150, group II: SI 150–300, and group III: SI > 300) and the frequency of SAs was studied.Results:The frequency of SAs was significantly greater in smokers than in nonsmokers and the frequency of SAs among the smokers was also seen to increase with increase in SI.Conclusion:The results of this study indicate that the genotoxic effect of cigarette smoke on chromosomes increases with smoking intensity. These findings can be used to support smoking cessation interventions.

Ag-NOR staining and satellite association in lymphoproliferative disorders

The nucleolar organizer regions (NORs) activity and the frequency of satellite associations (SA) in peripheral blood lymphocytes from patients with two chronic lymphoproliferative disorders were studied: 10 cases with B-cell chronic lymphocytic leukemia (B-CLL) and 10 with mycosis fungoides (MF). Thirteen healthy individuals formed the MF control group, and the oldest 7 constituted the B-CLL control group. The mean of Ag-NORs per metaphase was increased in B-CLL patients (8.80 +/- 0.63) compared with their controls (7.99 +/- 0.90) (P less than 0.025), meanwhile MF patients' value did not differ from their controls. In both disorders, the frequency of Ag-NORs in the G chromosomes was increased. The analysis of SA in B-CLL patients only revealed an increase in the frequency of cells with more than 4 ASPs (association pairs). Meanwhile, a significant higher mean of ASPs per cell in MF patients (1.74 +/- 0.41) compared to controls (1.40 +/- 0.24) (P less than 0.05) was observed. Furthermore, a close correlation between cells with complexes of 3 or more chromosomes and the mean of ASPs per cell was also found in MF. In conclusion, an increase of the Ag-NORs expression in B-CLL patients and a modification in the degree of SA in MF patients were found.

Satellite Associations in Recurrent Aborters

KEY WORDSCytogenetics; association; absolutes. ABSTRACT The frequency and pattern of satellite association was studied in lymphocyte culture of couples with recurrent spontaneous abortions and control popu- lation. A statistically highly significant increase of the satellite association frequency among the aborter couples has been observed in comparison to the control group (P < 0.001). The role of satellite association in non- disjunction is discussed.

Monitoring of workers occupationally exposed to pesticides in grape gardens of andhra pradesh

Studies were undertaken to investigate the effect of pesticides on workers employed in grape gardens of Andhra Pradesh. The data obtained on the reproductive performance showed an increase in the incidence of abortions and stillbirths. Out of 12 employed couples in grape gardens, 2 were found to be sterile. Cytogenetic studies revealed a significant increase in chromatid breaks and gaps in chromosomes of peripheral blood in workers exposed to pesticides. In addition, a high frequency of satellite associations was recorded in these workers.

Cytogenetic effect of colistin on human lymphocytes in vitro: chromosome aberrations, sister chromatid exchanges, mitotic index, cell cycle kinetics, and acrocentric associations.

Colistin, a peptide antibiotic, was tested at three different concentrations--71, 142, and 214 units/ml. One hundred forty-two units per milliliter corresponds to the plasma level after receiving therapeutic dose. There was a dose-dependent increase in the frequency of chromosome aberrations irrespective of the duration of treatment (T0, T24, T48). This antibiotic decreased the mitotic index and delayed the cell turn over rate indicating inhibition of DNA synthesis by it. Inhibition of DNA synthesis probably results in increase in the frequency of chromosome aberrations. Frequency of satellite associations of acrocentric chromosomes was increased with increasing concentration of the drug, but the differences at three concentrations were not significant compared to controls. There was no increase in the frequency of SCEs at any concentration or duration of treatment compared to controls. It appears that colistin induces the type of lesions that lead to chromosome aberrations and not to SCEs.

The study of X-rays and TCDD effects on satellite associations may suggest a simple model for application in environmental mutagenesis.

Satellite associations were used as parameters to test nucleolar organizer activity. Assuming that toxic and/or mutagenic agents may affect the ribosomal genes, satellite associations in human lymphocytes were analysed following exposure to X-rays and compared with the satellite association pattern of subjects exposed to TCDD. A significant decrease in the satellite association frequency in D group chromosomes was found both in irradiated lymphocytes and in subjects exposed to Dioxin. The findings seem to be in accordance with the hypothesis based on random damage of functional nucleolar organizing regions.

NORs and satellite associations in a family with 13/14 translocation.

The distribution and size of Ag-NORs and the frequency of satellite associations was investigated in a family where the mother and a son were 13/14 translocation carriers. In cells with good quality silver impregnation and G-banding, Ag-NORs were constant per subject in number and distribution, while Ag-NOR size varied from cell to cell. The father had the maximal number Ag-NORs (10). The mother's translocation chromosome, free chromosome 13 and both chromosomes 22 were Ag-NOR negative and these were transmitted to the children. The mean number of associations per cell for a particular subject was positively correlated with the subject's characteristic number of Ag-NORs. In this family, the positive correlation was also present between mean Ag-NOR size of acrocentric homologue chromosome pairs and their coefficient of association. No biological mechanism compensating for the absence of active NORs was demonstrated for this family.

Correlations between relatives for acrocentric association frequency.

Acrocentric association was investigated in peripheral blood lymphocytes of twins (10 female monozygotic and 11 females dizygotic pairs), newborns and both parents (30 families), and spouses (51 pairs). Seventy two hour cultures were G-banded and scored for both absolute and relative acrocentric association frequency, except in the case of the spouse pairs where only the absolute frequency was measured. Both relative and absolute parameters of acrocentric association show positive correlations between relatives with the values being highest and most consistent in monozygotic twins, intermediate in parent and offspring, and most variable in dizygotic twins. Husband and wife pairs from our family collections show a positive correlation for the absolute parameter but not for relative parameters. The environmental factors responsible have not been identified. A rough estimate of broad sense heritability (0.81) has been made for the relative parameters. It probably contains a large component due to genetic dominance. Heritability of the absolute parameters is probably lower than for the relative parameters though estimation of its value is complicated by inconsistent results. A model is proposed to account for the variation in satellite association frequency which contains two elements: (i) The genotype determines the ratio of one chromosome type to another in the population of associated chromosomes (ii) All other environmental factors influence the absolute frequency of association without altering this basic ratio.

Nucleolar changes in human phytohaemagglutinin-stimulated lymphocytes.

The nucleoli of lymphocytes from circulating peripheral blood and from phytohaemagglutinin (PHA)-stimulated cultures (from 2 h-96h) were studied using a silver method, RNA-specific fluorescent staining, and electron microscopy of ultrathin sections. In peripheral blood about 75% of the lymphocytes have one "ring-shaped" nucleolus composed of a distinct fibrillar centre surrounded by a dense pars fibrillaris and little granular material; the remaining lymphocytes showing two or more small "ring-shaped" nucleoli. With PHA stimulation, the number of cells with several nucleoli increases first (from 2 h--12 h). Next, cells containing one or, at most, two large nucleoli with nucleolonema devoid of fibrillar centers are seen (from 4 h on). 34 h after PHA, nucleoli of the "compact" type containing one or more fibrillar centres appear and comprise about 60% of the cells after 72 h. The appearance of more than one nucleolus per cell shortly after PHA administration suggests an activation of additional nucleolar organizer regions (NOR), which fuse to form one or two large nucleoli with nucleolonema. These are then transformed into "compact" nucleoli. The fibrillar centers stasin preferentially with silver. They contain nonchromosomal proteins and may serve as stores for nucleolar proteins. The fusion of activated NORs during the first cell cycle explains the relatively high frequency of satellite associations in first mitoses compared to later mitoses after stimulation.

Possible origin of a small bisatellited additional chromosome.

The possible derivation of a small supernumerary marker chromosome was investigated by means of different staining techniques and the frequency of satellite associations. It could be demonstrated that the marker chromosome participates at satellite association more than randomly. The marker chromosome is supposed to derive from 2 of chromosomes 13, 14, 21, or 22.

Satellite associations and silver staining in a case of multiple G and D variants.

Satellite associations and silver staining were analyzed in a normal woman carrying three "s" variants, on chromosomes 13, 21, and 22. Six of the acrocentric chromosomes were identified and a positive correlation between the parameters of satellite association frequency and positive silver staining was found for each chromosome. These parameters seem to depend on the presence and size of a secondary constriction and are unaffected by stallelite size.

Satellite association frequency and number of nucleoli depend on cell cycle duration and NOR-activity. Studies on first, second, and third mitoses of lymphocyte cultures.

In human lymphocyte cultures the frequencies of satellite associations in first, second, and third mitoses were investigated using the BUDR-method. A marked decrease of the association frequency with increasing numbers of cell cycles was found. The number of nucleoli seen in interphase is correlated with the satellite association frequency in the respective metaphase. Satellite association is positively correlated to Ag-staining intensity of the NORs. Individual differences in satellite association are due to differences in NOR activity and in lymphocyte activation. BUDR diminishes somewhat the Ag-staining intensity of the NORs but has no effect on satellite association frequencies. The main reason for the decrease of satellite association frequency in second and third lymphocyte mitoses is presumably a certain dislocation of the original chromosome position during mitosis and a decreased possibility of association during the short interphases. The high association frequency in first mitosis resembles the chromosome position in the long interphase of G0-lymphocytes.

Relationships between satellite association and the occurence of non-disjunction in man

It has been reported that there is an increased incidence of Down's syndrome among the children of parents who have been exposed to ionizing radiations for radiodiagnostic or radiotherapeutic reasons. Work with Drosophila, mice and human lymphocytes has shown that irradiation with X- or γ-rays induces aneuploidy, presumably by non-disjunction. It has been suggested that in man the frequency of satellite association (s.a.) of acrocentric chromosomes may be involved in the causation of chromosomal non-disjunction. In the present work the effects of radiation on s.a. have, therefore, been investigated. The frequency of s.a. between acrocentric chromosomes was determined after the exposure of human blood from normal and chromosomally abnormal individuals to various small doses of Co-60 γ-rays. The criteria of Zang and Back were used for the evaluation of s.a. complexes. No effects of radiation on the frequency of s.a. were apparent within the dose range investigated. The same result was obtained when s.a. was evaluated using the silver-staining technique in which physical connections between the associating satellites may be observed and the association complexes evaluated directly. The effects of other radiation sources have also been investigated.

Distribution patterns of satellite associations in human lymphocytes relative to age and sex.

Using ammoniacal silver for differential staining of satellites, associations from 1,668 human metaphases were studied from lymphocyte cultures of 167 normal individuals and were correlated with age and sex. There is a peak in satellite association frequency up to age 20 years in males and to 25 in females. With older ages there is a decline in association frequencies. No associations with four or more chromosomes were found in newborns. Furthermore, association in newborns, as well as in individuals older than 50 years, are significantly low compared to in-between age groups. Females have a higher frequency of satellite associations than males between the ages of 3 and 50 years. Typically, females have greater multiple associations, while males have more single associations. Randomness or non-randomness of occurrence of associations fluctuates for different age groups within and between the two sexes.

N-band polymorphism of human acrocentric chromosomes and its relevance to satellite association.

With the aid of Q- and N-banding techniques we investigated the relationship between the length of satellite stalks, the appearance of N-bands and the frequency of satellite association of individual acrocentric chromosomes in the cells of seven individuals, including one male with a satellited and small Y-chromosomes. The appearance of N-bands, seemed to be a constant and characteristic property of individual acrocentric chromosomes, independent of the status of concentration of the chromosomes at metaphase. The homolog with longer satellite stalks had larger N-bands and participated in satellite association at a higher frequency than the one with shorter stalks. It appeared that N-bands were present along the whole length of the satellite stalk, the size of which could possibly reflect the amount of rDNA present in the nucleolar organizers in human chromosomes.

Abnormal chromosome 22 and recurrence of trisomy-22 syndrome.

Trisomy-22 was confirmed with both Q- and G-banding in two sibs. Growth and mental retardation plus various dysmorphic features of this syndrome are described and compared with previous reports. Cytogenetic...

Variation in the number of genes for rRNA among human acrocentric chromosomes: correlation with frequency of satellite association

Grain counts after hybridization of 125I-rRNA to human chromosomes indicate numerical polymorphism at the rDNA sites. Prephotographing procedures decrease labeling but do not change the proportions of labeled RNA annealed to different chromosomes. A positive correlation was found between the frequency of participation of a given chromosome in satellite associations and its rDNA content by the criterion of grain count. Certain individual chromosomes are clear exceptions to this correlation.

Satellite-association frequency and rDNA content of a double-satellited chromosome.

A correlation between the amount of rDNA and the frequency of participation in satellite associations is observed in a double-satellited human acrocentric chromosome.