Chromosome aberrations in in vitro irradiated lymphocytes from human cord blood

Summary An in vitro dose effect curve of dicentric chromosome aberrations in human cord blood lymphocytes has been obtained for 250-kV X-rays. This is compared with a curve prepared in an identical manner using blood from adults. The comparison shows a marginally higher dicentric yield in blood of newborns at doses above about 250 rads.Acknowledgment. We wish to thank Miss P. Orledge of the John Radcliffe Hospital, Oxford, for samples of cord blood, Mr M.J. Corp of the MRC Radiobiology Unit, Harwell, for irradiating the samples and Mr A.A. Edwards of NRPB, for help with statistics. The work was partly supported by Euratom Contract No. 171-76-1 BIO UK.     

Chromosome aberrations in in vitro irradiated lymphocytes from human cord blood.

An in vitro dose effect curve of dicentric chromosome aberrations in human cord blood lymphocytes has been obtained for 250-kV X-rays. This is compared with a curve prepared in an identical manner using blood from adults. The comparison shows a marginally higher dicentric yield in blood of newborns at doses above about 250 rads.     

Chromosome aberrations in cattle raised on bracken fern pasture

Thirteen cows maintained on natural bracken fern (Pteridium aquilinum) were analyzed cytogenetically. The frequency of structural chromosome aberrations detected in peripheral blood cells was significantly higher when compared to that detected in animals raised on pasture containing no bracken fern. We discuss the clastogenic action of fern and its synergistic action with infection by type 2 and 4 papilloma virus in the same animals.     

Chromosome aberrations,micronuclei, and activity of superoxide dismutases in human lymphocytes after irradiation in vitro

The goal of this study was to provide data on the dose-dependent production of dicentrics and micronuclei in human lymphocytes irradiated with 22.6 MeV protons and to estimate the possible contribution of intracellular superoxide dismutases (SOD) to the relative biological effectiveness (RBE) of protons. For the dose-response study, heparinized whole blood of a healthy volunteer was irradiated with protons and X-rays employing radiation doses of 0.5-4 Gy. Three biological endpoints were analyzed: chromosomal aberrations, micronuclei, and specific activity of cytosolic (CuZnSOD) and mitochondrial (MnSOD) superoxide dismutases in harvested human blood cells. Dicentric dose-response curves fit a linear-quadratic form (alpha = 0.094 +/- 0.006, beta = 0.032 +/- 0.001) induced with X-rays and (alpha = 0.119 +/- 0.057, beta = 0.029 +/- 0.014) for 22.6 MeV protons. Protons were more effective than X-rays in producing exchanges, particularly at 0.5 and 1 Gy. In contrast to X-ray irradiated samples where a significant increase in the specific activity of MnSOD was recorded (up to a radiation dose of 1 Gy), irradiation with protons markedly reduced its activity. As a consequence of the reduced activity of MnSOD, the chromosomal dose-response curve became quadratic. The RBE for dicentrics varies with dose (from 2.2 to 1.01) and reduced activity of MnSOD is an important contributor to the RBE of protons. SODs, particularly MnSOD, play an important role in defending DNA from reactive oxygen species. A reduced activity of SOD, particularly MnSOD, is an important contributor to the RBE of protons.     

Chromosome aberrations in mice by the antifungal antibiotic,nystatin

Summary Nystatin, a fungicide of current medical use, was tasted in mice for its effect on chromosomes of bone marrow cells. A significant increase of aberrations, mostly of chromatid type, was observed over a period of from 15 min to 15 days following the application of the drug. Our data indicate a non-random distribution of the breaks.     

Chromosome aberrations induced by daunomycin in human leucocyte cultures,with the apparent synergistic effect of arginine

Zusammenfassung Das Antibiotikum und Zytostatikum Daunomycin induziert beträchtliche Chromosomenaberrationen in menschlichen Leukozyten in der Konzentration von 0,02 µg/cm³. Dieser Effekt wird durch Zusatz von Arginin zur Zellkultur wesentlich verstärkt, und die Aberrationen werden auch qualitativ verändert. Es ist nicht bekannt, wie Daunomycin und Arginine aufeinander einwirken.     

Chromosome breaking activity of A139 in human lymphocytes in vitro

Zusammenfassung 2,5-bis-(methoxyäthoxy)-3,6-bis-äthylenimino-p-benzochinon (Bayer A 139) induziert dosisabhängig Chromatidenaberrationen in menschlichen Lymphozyten in vitro. Die intrachromosomale Aberrationsverteilung ist nicht zufällig.

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I thank Mrs.R. Pieper for her careful technical assistance. I am also grateful to the firm Bayer, Leverkusen, for supplying the A 139.     

Epigenetic aberrations during oncogenesis

The aberrant epigenetic landscape of a cancer cell is characterized by global genomic hypomethylation, CpG island promoter hypermethylation of tumor suppressor genes, and changes in histone modification patterns, as well as altered expression profiles of chromatin-modifying enzymes. Recent advances in the field of epigenetics have revealed that microRNAs’ expression is also under epigenetic regulation and that certain microRNAs control elements of the epigenetic machinery. The reversibility of epigenetic marks catalyzed the development of epigenetic-altering drugs. However, a better understanding of the intertwined relationship between genetics, epigenetics and microRNAs is necessary in order to resolve how gene expression aberrations that contribute to tumorigenesis can be therapeutically corrected.     

Chromosome 13 dementias

The importance of cerebral amyloid deposition in the mechanism of neurodegeneration is still debatable. Classic arguments are usually centered on amyloid β(Aβ) and its role in the neuronal loss characteristic of Alzheimer’s disease, the most common form of human cerebral amyloidosis. Two non-Aβ cerebral amyloidoses, familial British and Danish dementias (FBD and FDD), share many aspects of Alzheimer’s disease, including the presence of neurofibrillary tangles, parenchymal preamyloid and amyloid deposits, cerebral amyloid angiopathy and a variety of amyloid-associated proteins and inflammatory components. Both early-onset conditions are linked to specific mutations at or near the stop codon of the chromosome 13 gene BRI2 that cause generation of longer-than-normal protein products. Furin-like processing of these longer precursors releases two de novo-created peptides, ABri and ADan, which deposit as amyloid fibrils in FBD and FDD, respectively. Due to the similar pathology generated by completely unrelated amyloid subunits, FBD and FDD, collectively referred to as chromosome 13 dementias, constitute alternative models for studying the role of amyloid deposition in the mechanism of neuronal cell death.Received 4 March 2005; received after revision 24 April 2005; accepted 26 April 2005     

Detection and isolation of induced chromosome aberrations in Lepidoptera

Summary An embryo chromosome technique combined with larval testes sampling permits isolation within 1 generation of lepidopteran strains carrying chromosome aberrations     

Chromsome aberrations in cattle raised on bracken fern pasture

Summary Thirteen cows maintained on natural bracken fern (Pteridium aquilinum) were analyzed cytogenetically. The frequency of structural chromosome aberrations detected in peripheral blood cells was significantly higher when compared to that detected in animals raised on pasture containing no bracken fern. We discuss the clastogenic action of fern and its synergistic action with infection by type 2 and 4 papilloma virus in the same animals.Acknowledgments. We are grateful to Dr F. J. Benesi, Dr J. L. Guerra and Dr I. L. Sinhorini for performing some of the clinical and pathological analyses; O. P. Ferraz, L. A. Tadeu Dias, L. F. Feitosa and A. M. N. Paiva for technical assistance; and to Dr N. H. C. Castro and Dr C. de Araujo Peres for critical and statistics review, respectively. Research was supported by CNPq FAPESP and CAPES.     

Chromosome 17-linked dementias

Chromosome 17-linked dementias have been defined by linkage analysis. The most common of these syndromes has been estimated to be the cause of between 2 and 20% of all dementia and has alternately been called frontotemporal dementia, Pick's disease (without Pick bodies) and dementia lacking distinctive features [1 – 3]. The identification of the mutation responsible for these conditions in a group of clinically and pathologically heterogeneous disorders may allow us to gain broad insight into the processes of neurodegeneration.