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Coloboma and microphthalmos in chromosomal aberrations. Chromosomal aberrations and neural crest cell developmental field.

A survey of more than 500 reports on patients with autosomal chromosomal aberrations associated with microphthalmos and/or coloboma shows that these anomalies are unspecific. Anterior chamber anomalies were common as were abnormal ears, preauricular pits and tags, cleft lip-palate, micrognathia, urogenital malformations, congenital heart disease, atresia of the anus and minor malformations of the hands and feet. It is proposed that the chromosomal aberrations induce faulty development of neural crest cells and rostral neural plate derivatives.

Abnormalities, Multiple

Increased gene amplification in L5178Y mouse lymphoma cells with hydroxyurea-induced chromosomal aberrations.

Chromosomal aberrations and dihydrofolate reductase gene amplification are observed in L5178Y mouse lymphoma cells after treatment with hydroxyurea. The types of aberrations include polyploidy, endoreduplication, chromosome fragmentation, and the presence of extrachromosomal DNA. Hydroxyurea-treated cells analyzed by cell sorting showed a subpopulation of cells with increased DNA and increased dihydrofolate reductase. This subpopulation shows a high incidence of chromosome aberrations and an increased frequency of dihydrofolate reductase gene amplification. Hydroxyurea-treated cells with the normal amount of DNA and dihydrofolate reductase have few aberrations and a low frequency of dihydrofolate reductase gene amplification. We propose that hydroxyurea treatment causes overreplication of DNA and that recombination of overreplicated DNA can lead to chromosome aberrations and gene amplification.

Animals

Low density lipoprotein receptor activity in human leukemic cells--relation to chromosome aberrations.

Chromosome analysis and low density lipoprotein (LDL) receptor activity of leukemic cells from 38 patients with acute non-lymphocytic leukemia were correlated. Clonal chromosome aberrations were found in 22 patients, and an extra chromosome 8 was found in 7 of them. LDL receptor activity was significantly higher in patients with an extra chromosome 8 than in patients with other abnormalities or a normal karyotype. Chromosome 8 may harbor genes of importance for the expression of the LDL receptor.

Adolescent

[Antibody deficiency syndrome and chromosome aberrations].

Chromosome analyses were made on culture lymphozytes from peripheral blood in 37 patients with humoral and local antibody deficiency syndrome. In one child with humoral IgA-deficiency a ploidymutation of sex chromosomes - a Klinefelter-Syndrome - and a structural variante of chromosome 16 were detected - karyotype 47, XXY, 16q+. No aberrations of chromosomes 18 and 21 were found out in these phenotypic completely normal children. Patients with secret-IgA-deficiency in mucosae had normal karyotypes. Theoretical aspects of possible connection of antibody deficiency syndrome and chromosomal anomalies are discussed.

Bacterial Infections

Nonrandom chromosomal aberrations and clonal chromosomal evolution in acute leukemia associated with Down's syndrome.

Nine Down's syndrome (DS) children, four with acute leukemia, one with acute leukemia as well as rhabdomyosarcoma, and four with other hematologic disorders, were analyzed for constitutional and acquired chromosomal aberrations. Acquired clonal chromosomal aberrations were identified only in the acute leukemia cases, and four of the five acute leukemia demonstrated numerical and/or structural aberrations involving chromosomes #8, #19, and #21. Of the 11 aneuploid stem cell lines identified in the five acute leukemia cases, trisomy 21, trisomy 8, trisomy 19, and tetrasomy or pentasomy 21 was found in 11, seven, four, and two lines, respectively. The frequent appearance of multiple stem cell lines with common and/or overlapping chromosomal aberrations in acute leukemia cases demonstrates the existence of genomic instability and heterogeneity of the neoplastic cell population, which results from clonal chromosomal evolution. Furthermore, trisomy 19 was identified only with the concurrent presence of trisomy 8, suggesting that the nondisjunction of chromosome #19 probably occurred after that of #8. Trisomy 21 was observed in every aneuploid stem cell line and, in one case, trisomy 21 was maintained in the bone marrow leukemic cells but not in the orbital rhabdomyosarcoma cells, indicating that this constitutional chromosomal aberration is probably crucial for and predisposed to the development of acute leukemia in DS patients. The association of acquired clonal chromosomal aberrations, especially those involving chromosomes #8, #19, and #21, with DS acute leukemia strongly suggests the clinical implication of cytogenetic analysis in the diagnosis of acute leukemia development in DS patients.

Acute Disease

[Single-strand DNA breaks and chromosome aberrations in the hepatocytes of mice of different ages].

The same damages were found to occur in hepatocyte DNA from old mice of different strains by means of sedimentation in alkaline sucrose concentration gradient. At the same time, the number of hepatocytes with aberrant chromosomes is strongly different in these strains. From these data an assumption is made that some other damages being accumulated with aging are responsible for chromosome aberrations except for single-strand DNA breaks. The number of single-strand breaks registered in hepatocyte DNA of the old animals under gamma-irradiation is two-three times more than that of the young animals, though the rates of repair of the induced single-strand breaks in DNA are the same for mice of different age and strains.

Aging

[DNA repair capacity, chromosome aberration rate and chromosome fragile sites among members of 7 cancer families].

A nucleoid sedimentation technique was developed and used for analysis of DNA repair capacity in 40 members from 7 cancer families. Chromosome aberration rate (CAR) and chromosome fragile sites (CFS) were assayed simultaneously for comparison. It was shown that 32 members (80%) had a decreased DNA repair capacity and 34 (85%) had increased CAR as well as an apparent increase of CFS. 28 members (70%) showed both decreases of DNA repair capacity and increases of CAR. The importance of these criteria in heritable susceptibility to cancer is discussed.

Adult

Studies on radiation-induced chromosome aberrations in mouse spermatocytes. II. Dose-response relationships of chromosome aberrations induced at zygotene stage in mouse primary spermatocytes following fast neutron- and 60Co gamma-irradiations.

The chromosome aberrations induced at zygotene stage in mouse spermatocytes following exposures to fast neutrons and 60Co gamma-rays were examined at diakinesis-metaphase I. The dose-response relationships were well fitted to linear equation for deletion-type aberrations and to linear-quadratic equation for exchange-type aberrations in 60Co gamma-irradiation group. In fast neutron-irradiation group, the dose-response relationships were well fitted to linear equations for deletion- and exchange-type aberrations. The rate of deletion-type aberrations was remarkably high for fast neutrons, about 6 times higher than that after 60Co gamma-irradiation. The main types of chromosome aberrations observed were iso-chromatid breaks or fragments and chromatid exchanges in both irradiation groups as well as X-irradiation. These results indicate that there is a possibility that two double-strand breaks are induced simultaneously at iso-locus position in sister chromatids by a single track of radiations. Production of such single-track-induced two double-strand breaks in iso-chromatids may be very frequently expressed as iso-chromatid-type deletions in the high LET fast neutron-irradiation group. On the contrary, in the low LET 60Co gamma- or X-irradiation group, the above-mentioned mechanism may not be so effective for contribution to chromosome aberration induction in mouse spermatocytes. This mechanism was discussed in detail.

Animals

Studies on chromosome aberrations in the eggs of mice fertilized in vitro after irradiation. I. Chromosome aberrations induced in sperm after X-irradiation.

The induction of chromosome aberrations in eggs of mice fertilized with X-irradiated sperm was performed by using an in vitro fertilization technique. Capacitated mature sperm was irradiated with various doses of X-rays and cytological analysis of the first cleavage metaphase of in vitro fertilized eggs was made. The frequencies of chromosome aberrations increased exponentially with dose and the dose-response relationship for overall breaks fitted well to a quadratic equation. The chromosome aberrations were mainly chromosome-type (82.1%), and the majority of aberrations were fragments.

Animals

Studies on radiation-induced chromosome aberrations in mouse spermatocytes. I. Stage specificity and dose-response relationships of chromosome aberrations induced in mouse primary spermatocytes following X-irradiation.

The cytological analysis of chromosome aberrations induced at diplotene, mid-pachytene, zygotene and leptotene stages following X-irradiation was performed at diakinesis-metaphase I in mouse spermatocytes. The dose-response relationships fitted well to linear equations for deletion-type aberrations at each stage, and to linear-quadratic equations for exchange-type aberrations at all stages except for leptotene. The radiosensitivity to chromosome aberration induction tended to increase gradually with progression through synaptic and post-synaptic stages, diplotene being the most sensitive. Chromatid exchanges were hardly observed at leptotene, the aberrations being mainly isochromatid fragments. On the contrary, chromatid exchanges and isochromatid deletions were mainly observed at later stages (zygotene-diplotene). The specificity of chromosome aberration induction in primary spermatocytes might be influenced by chromatin organization and chromosomal configuration peculiar to meiotic cells.

Animals

Studies on chromosome aberrations in the eggs of mice fertilized in vitro after irradiation. II. Chromosome aberrations induced in mature oocytes and fertilized eggs at the pronuclear stage following X-irradiation.

Cytological analysis of the first-cleavage metaphase of eggs exposed to X-rays at the mature oocyte stage or the pronuclear stage 4 h after fertilization was performed using the in vitro fertilization technique. The frequency of chromosome aberrations in irradiated mature oocytes increased exponentially with dose, the dose-response relationship being best fitted to the linear-quadratic model. On the other hand, in eggs irradiated at the early pronuclear stage, the frequency increased linearly with dose and the dose-response relationship was best fitted to the linear model. The aberrations were mainly chromosome-type (mature oocytes: 86.0% and pronuclear stage: 88.5%) and the majority were fragments in both cases. Eggs in the early pronuclear stage were markedly more radiation-sensitive than mature oocytes. A comparison of the present results with the previous ones (Matsuda et al., 1985b) showed that the sensitivities to induction of chromosome aberrations were in the order: egg at early pronuclear stage (highest) greater than mature oocyte greater than mature sperm.

Animals

Variation of spontaneous occurrence rates of chromosomal aberrations in the second chromosomes of Drosophila melanogaster.

After accumulating mutations by the aid of marked inversions, spontaneous occurrence rates of chromosome aberrations were estimated for 1148 chromosome lines that originated from five stem line second chromosomes of Drosophila melanogaster. In chromosome lines originating from three stem chromosomes (CH, PQ, and RT), mutations were accumulated for 7550, 7252, and 7256 chromosome generations, respectively, but no structural change was detected. For the chromosome lines that originated from the other two stem chromosomes, the situation was different: Twenty aberrations (19 paracentric inversions and 1 translocation between the second and the third chromosomes) during 45990 chromosome generations took place in the 500 chromosome lines derived from stem line chromosome (AW), and 92 aberrations (83 paracentric inversions, 6 pericentric inversions, 2 translocations between the second and the third chromosomes and 1 transposition) arose during 45006 chromosome generations in the 500 chromosome lines derived from stem line chromosome (JH). For the AW group the occurrence rate becomes 0.00043 per chromosome per generation for all aberrations and 0.00041 for inversions. For the JH group the corresponding rates are 0.00204 and 0.00198, respectively.-A non-random distribution of the breakpoint on the salivary gland chromosome was observed and the breakpoints were concentrated in the regions 26, 29, 33, and 34.-The cytoplasms and the chromosomes (other than the second chromosomes) were made approximately uniform throughout the experiments. Thus, this remarkable variability in the occurrence rate is most probably due to the differences in one or more chromosomal elements on the original five stem chromosomes. The mutable chromosomes (AW and JH) appear to carry a kind of mutator factor such as hi (Ives 1950).

Animals

[Chromosome aberrations in chronic and lupus glomerulonephritis ].

The levels of aberration of chromosomes in peripheral blood leucocytes were investigated in patients with chronic and lupoid glomerulonephritis considering the clinical variants and morphological forms of the disease. In chronic glomerulonephritis high levels of chromosome aberration were found in patients with nephrotic type; in lupoid glomerulonephritis the frequency of chromosome aberration was higher in patients with active glomerulonephritis. Chronic renal failure did not essentially change the level of chromosome aberration both in chronic and lupoid glomerulonephritis. In different morphological forms of glomerulonephritis the frequency of chromosome aberration was determined by the clinical variant of the disease.

Adolescent

Three cases of minor chromosomal aberrations discovered by prenatal chromosome determination.

A case of pronounced secondary constriction of a chromosome belonging to pair N0. 9, a case of deletion of the short arms of one of the chromosomes in pair No. 13, and a case of partial trisomy of the distal portion of a chromosome in pair No. 14 were discovered by prenatal chromosome determination. Analysis of the parents' karyotypes enabled the clinical importance of the three different chromosomal aberrations to be elucidated.

Abortion, Induced

[Identification of aberrant chromosomes based on the morphometry of the synaptonemal complexes in a sterile male mouse].

The synaptonemal complexes (SCs) of surface-spread spermatocytes of male mouse from the F1 progeny of a male exposed to a mutagen have been examined by electron microscopy. Nonreciprocal translocation was recognised in analysing configuration of SC. Electron microscope analysis revealed translocation in 100% pachytene spermatocytes and light microscope analysis of air-dried metaphase spermatocytes demonstrated this in 58% cells. Different types of association of X-chromosome with aberrant chromosomes were discovered in pachytene spermatocytes. Computer analysis of relative length of SCs permits to detect a nonreciprocal translocation from chromosome 4 to chromosome 16. The length of the translocated fragment was determined to be from 66 to 75% of the length of chromosome 4. It has been impossible to discover a telomere fragment of chromosome 16, because the break point of chromosome 16 is too close to the distal end.

Animals