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Biomedical subjects

C Susanne

Publications and source records attributed to C Susanne.

At least 37 records · Page 2Linked to original sources
PubMed1984

Comparison of metaphase and interphase nucleolar activity in Hela-CCL2 cells and PHA-stimulated human lymphocytes.

Metaphase and interphase nucleolar activity in cultured Hela-CCL2 cells and PHA-stimulated human lymphocytes have been studied with silver nitrate staining. In metaphase, we examined the relationship between the actual number of active NORs (AgNORs) and total number of NOR-bearing acrocentrics. Interphase silver staining over the nucleus was analyzed cytodensitometrically and morphologically. From all investigations, Hela-CCL2 cells and lymphocytes were shown to have similar levels of nucleolar activity. Our results suggest that there is a form of regulation of nucleolar activity in malignant Hela-CCL2 cells as compared to PHA-stimulated human lymphocytes.

Cell Nucleolus↗
PubMed1984

Mercury-induced segregational errors of chromosomes in human lymphocytes and in Indian muntjac cells.

Segregational errors of chromosomes were studied in human lymphocytes and in Indian muntjac fibroblasts exposed to methylmercury chloride (CH3HgCl) or mercury chloride (HgCl2). The cells were exposed to the mercury compounds only during a limited period of the pre-DNA synthetic stage of the cell cycle or from that stage up to mitosis. In the lymphocytes we observed a clear increase of C-mitotic figures for both mercury compounds and for both exposure times. Segregational errors were, however, much more important after the shorter exposure period. Muntjac fibroblasts appear to be more sensitive to the mercury than are the lymphocytes so that their suitability for the study of C-mitosis may be questionable. The muntjac cells may be an important tool for the study of polyploidy induction.

Aneuploidy↗
PubMed1984

[Current age of the menarche in Belgium].

In Belgium, as in most industrialized countries, studies about menarcheal age have shown an earlier physical and sexual maturation. In this paper we will consider the secular trend in menarcheal age over the last twenty years in Brussels. The results concerning menstruation have been obtained in 1980-1982 from 1048 Belgian girls aged between 9 and 17. These girls have very varied socio-economic backgrounds, representative of the diversity of social origin in the Belgian population of Brussels (city and suburbs). Our data were collected using the status quo-method and compared with Jeurissen's (menarcheal age in Belgium between 1915 and 1959). Percentiles and probits were used. The lower limit, where 10% of the girls have had their menarches remains more or less constant. Between 1915 and 1959, Jeurissen noted the tendency of the median menarcheal age toward earlier sexual maturation from 14 years 4 months to 13.0. But, for the first time in Belgium, it seems that the median age is stabilized at 13.0 years. However, the higher limit (age, where 90% have had their menarches) is attained at a lower age: 15.0 for girls born between 1950-1954 and 14.0 in our sample. In conclusion, it seems that better conditions of life cause an evolution in the cases of late menarches but have no more repercussions on the median menarcheal age in this Belgian group.

Adolescent↗
PubMed1983

Mercury chloride--and methyl mercury chloride--induced inhibition in NOR activity.

Previous work has raised the question of whether mercury compounds inhibit the activity of the nucleolar organizing genes. For that reason we performed a cytophotodensitometric analysis on silver-stained interphase nuclei from human peripheral blood lymphocytes exposed to various concentrations of HgCl2 (0-150 X 10(-6) M), CH3HgCl (0-50 X 10(-6) M), and actinomycin D (0-0.1 microgram/ml). The last compound was used as a positive control. The cells were exposed to the compounds either during G1-early S phase, allowing recovery after the exposure, or from G1 until harvest; thus no recovery was allowed in this case. Like actinomycin D, both mercury compounds were shown to inhibit the NOR activity. This inhibition was furthermore more evident during the short exposure experiment. Our results do confirm that mercury compounds may, to a certain extent, influence some factors regulating the nucleolus-organizing activity.

Adult↗
PubMed1983

Genetic and environmental factors in head and face measurements of Belgian twins.

Seventeen head and face measurements of 205 twin pairs, aged 18 to 25 years, are analyzed. In both sexes a significant genetic variance component is found for head length, head breadth, and frontal breadth, for seven breadth measurements of the face, for physio-face height, and nose height. A significant genetic variance component is found for nasion-gnathion, nasion-stomion, and lips height in males and for the two ear measurements in females. We suggest that the sex difference for heritability may be due to random factors and to continued growth from 18 to 25 years in males.

Adolescent↗
PubMed1983

C heterochromatin variation in couples with recurrent early abortions.

The possible influence of the high polymorphic C heterochromatic regions of human chromosomes 1, 9, 16, and Y on meiotic chromosome segregation was investigated. Faulty chromosome segregation may be the result of either an abnormal quantity of C heterochromatin on the homologues, or disequilibrium between the homologues. The aim of our study was to determine whether either a variation in the amounts of total C heterochromatin or differences in the amounts of C heterochromatin between homologues could lead to faulty chromosome segregation. The study was performed on C banded metaphases obtained from peripheral lymphocyte cultures of 15 couples with recurrent early abortions and 15 control couples, all Caucasians. Analysis of variance was first performed on separate metaphases to measure intra-individual, inter-individual, and between population variation in a hierarchical model. Since the significant intra-individual differences covered the other parameters we performed, secondly, a one way analysis of variance on the mean values of metaphases per person in order to measure the inter-individual and between population variation. The results did not show a relationship between C heterochromatin lengths and occurrence of recurrent abortions.

Abortion, Habitual↗
PubMed1983

Comparison of chromosome associations in human lymphocytes arrested by colcemid, nocodazole, or cycloheximide.

The method of "generalized distances" was applied to compare the effects on homologous interchromosomal distances of colcemid, the routinely used tubulin inhibitor with the effects of two other metaphase arrestants: nocodazole, also a tubulin inhibitor and cycloheximide, an inhibitor of protein synthesis which preserves somatic association. More homologous pairs were associated in the cycloheximide treatment than in the other two procedures; however, while several chromosomes which tend to lie toward the center of the metaphase plate showed somatic association in the various treatments, we found no evidence for somatic association of the larger, more peripherally located chromosomes in human cells in any of our treatments (chromosome pair 7 excepted in the colcemid sample).

Benzimidazoles↗
PubMed1983

Is there a predisposition for meiotic nondisjunction that may be detected by mitotic hyperploidy?

The aneuploidy frequencies have been studied in vitro in lymphocytes from couples with recurrent abortions, from parents of a trisomic child and from control couples with at least two normal children; c-heterochromatin variants have been analysed on the same samples by length measurements. A significant increase of hyperploid cells has been observed in the lymphocytes from parents of a trisomic child and couples with recurrent abortions as well. However, no consistent correlation has been found so far between c-heterochromatin variants and an increase of aneuploidy.

Abortion, Habitual↗
PubMed1982

Comparison of two measuring methods for the evaluation of C-heterochromatin in human chromosomes.

In this study two different methods for evaluating the size of the C heterochromatin blocks of human chromosomes 1, 9, 16, and Y were compared. The first method measured the lengths of both the euchromatin and the C heterochromatin parts of the p and q arms of chromosomes 1, 9, 16, and Y. The second method analyzed the same chromosome segments, but by measuring the areas. In the comparison, the relative C heterochromatin value (length or surface) of each chromosome, the mean for each individual, the standard deviation, and the coefficient of variation were taken into account. It is proposed that the best estimation for the size of a C heterochromatin segment is the ratio of its length to the total length of the chromosome; accurate estimation requires at least 20 metaphases.

Chromosome Banding↗
PubMed1982

The central localization of the small and early replicating chromosomes in human diploid metaphase figures.

Centromere-center distances are analyzed in 700 metaphase plates, which belong to four different samples. The descriptive analysis of the chromosome distribution shows that smaller, earlier replicating, genet-dense chromosomes are preferentially found near the metaphase plate center, surrounded by longer chromosomes which finish their replication rather late during S phase. This general pattern is highly constant in diploid metaphase samples and independent of sex, culture time, and number of individuals used in the sample. There is accumulating evidence that this overall distribution is not the result of technical artifacts. The metaphase plate data are complementary to the concept of an interphase nucleus structure in which late-replicating, genetically less active chromatin is accumulated at the periphery of the nucleus, while other, earlier replicating chromatin is connected with the intranuclear matrix. Although the currently available data should not be overinterpreted, an extension of the "bodyguard" hypothesis, which was suggested for C heterochromatin, provides a functional interpretation for these data: The peripherally localized, late-replicating genetic material protects the centrally localized euchromatin against mutagens, clastogens, and maybe also against viruses.

Adult↗
PubMed1982

Genetic and environmental influences on body measurements of Belgian twins.

A study of 100 MZ and 67 DZ twin pairs aged 18 to 25 years has shown a highly significant genetic contribution to the following measurements: standing and sitting height; height on tragus; arm length; biacromial, biiliac, and bitrochanteric diameter; weight; circumference of thigh and of upper arm relaxed and contracted; and head length and breadth. The twins were brought up together and of the same socioeconomical, geographical, ethnical, and cultural origin. Zygosity diagnosis was based on 22 to 26 blood groups. The means of the measurements were smaller in MZ than in DZ twins, some of them significantly so. The intraclass correlation coefficients of the MZ cotwins were all significant and greater than those of the DZ cotwins. In families of same geographical origin, sib-sib correlations were somewhat smaller than those of the DZ cotwins, but for the three diameters of the body the order was reversed.

Adolescent↗
PubMed1982

Chromosome distribution studies in XXY karyotypes.

The method of 'generalised distances' was applied to characterise the relative position of the metaphase chromosomes in a population of XXY subjects (180 metaphases from 28 subjects). The most striking observation was that the presence of an extra gonosome coincided with a disturbance of the normally stable centromere-centre distribution pattern. The distribution analysis gave no clear cut evidence for the induction of gonosomal trisomy XXY by chromosome association. No significant association was observed between X and X or X and Y but there was a smaller distance between X and Y in XXY karyotypes than in XY karyotypes. As far as autosomes are concerned, the XXY karyotypes were characterised by a less central location of the acrocentrics without a clear decrease of association frequencies of these acrocentrics, and the C heterochromatin rich chromosomes were more often associated than in the XX and XY control populations. These data do not support the idea that gonosomal trisomies result from chromosome associations, but favour the hypothesis that spindle degeneration as a result of intrafollicular ageing of C heterochromatin polymorphism may be responsible for non-disjunctions.

Cells, Cultured↗
PubMed1981

Mutagenicity study on mice given mercuric chloride.

The mutagenic activity of different concentrations of mercuric chloride (0, 2, 4 and 6 mg HgCl2 per kg body wt) has been analysed in Swiss Albino mice at several periods (12, 24, 36 and 48 h) after intraperitoneal injection. No increased frequency of chromosomal aberrations was observed in bone marrow cells or in spermatogonia.

Animals↗
PubMed1980

Telomere and centromere association tendencies in the human male metaphase complement.

"Generalized distances" between centromeres and between telomeres were statistically analyzed (chi 2 tests) in 100 trypsin-banded metaphase figures derived from normal males. Analysis of association tendencies on the first column of obtained c-c, p-p, q-p, and p-q histograms showed significant heterochromatin attraction not only between nonacrocentrics and acrocentrics but also between two nonacrocentric chromosome pairs (1 and 16). However since not all c-heterochromatin-rich chromosomes were involved in associations (pair 5), and conversely, since chromosomes without an important centromeric heterochromatin block were involved in associations (pairs 8 and 11), it is probable that centromeric heterochromatin is not the only factor responsible for chromosome association. Moreover associations occur not only at the centromeres; in our circle analysis of the binding capacity of the telomeres or centromere of one chromosome pair with the telomeres or the centromeres of all other chromosome pairs, we also found preferential associations for T(4,13), T(9,15), T(11,15), T(13,19), T(15,19), T(17,18), T(17,22), and T(19,20). We therefore suggest that heterochromatin is not the only reason for chromosome association and that telomeres may also play an important part in this process.

Adult↗