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Showing papers on "Ring chromosome published in 1972"




Journal ArticleDOI
TL;DR: The present cases of D-trisomy each had, at necropsy, a tumour of an adrenal gland in which the adrenal glands were enlarged and morphologically abnormal, which is most unusual in children with neuroblastoma.
Abstract: neoplastic disease. Leukaemia has been reported in 2 patients with D group chromosomal aberrations (Schade et al, 1962; Zuelzer et al, 1968). The present cases of D-trisomy each had, at necropsy, a tumour of an adrenal gland. In case 1, the tumour was regarded as a probable carcinoma because of its size, cellularity, and irregular histological arrangement, because the cells were basophilic and arranged in cords and acini, it was considered to have originated from the definitive cortex. Marin-Padilla, Hoefnagel, and Benirschke (1964) described 2 cases of D-trisomy in which the adrenal glands were enlarged and morphologically abnormal. However, the association of D-trisomy with an adrenal cortical carcinoma is most unusual. A 5-year-old boy with an anaplastic adrenal carcinoma had, on chromosome analysis of the peripheral lymphocytes, an extra large sub-metacentric chromosome similar to group B (Pascasio et al, 1967). Ellwood and Pearson (1968) found normal karyotypes in 2 girls with adrenal cortical carcinomas. In case 2, a microscopic neuroblastoma was present in the adrenal medulla. This tumour is frequently seen as an incidental finding in infants who die before the age of 3 months (Beckwith and Perrin, 1963). The child with neuroblastoma described by Mittelbach and Szekely (1934/1935) had a cleft lip and palate, microcephaly, cerebral atrophy, absence of the corpus callosum, widely patent ductus arteriosus, and patent foramen ovale -features suggestive of D-trisomy. Cytogenetic findings in children with neuroblastoma have been variable; Nichols (1968) did not observe any abnormality but recently Wakonig-Vaartaja et al (1971) who studied 21 children with neuroblastoma noted an increased number of abnormal metaphases in pretreatment samples of peripheral blood and bone marrow.

13 citations


Journal ArticleDOI
TL;DR: Two cases are described in which ring chromosomes were found in direct preparations of cervical epithelium showing presumptive precancerous states, and both showed “microcarcinoma”, though not in parts of the cervix from which samples for chromosomes were obtained.

10 citations


Journal ArticleDOI
TL;DR: It is suggested that an alternative cytological mechanism exists for ring perpetuation that may not follow strictly McClintock’s principle of ‘ breakage-fusion-bridge cycle ’.
Abstract: The cytological mechanisms for the formation and perpetuation of varying-sized ring chromosomes have been explored extensively by McClintock (1938) in Zea mays. According to McClintock, a somatic crossover between the two sister chromatids of a monocentric ring during the duplication period gives rise to a dicentric double-sized ring at the following anaphase stage. Because of the anaphase movement, the dicentric ring might break at unequal or equal points. Thus, two unequal or equal-sized rings would be produced in the daughter nuclei. In the following cell division, these daughter rings would repeat the earlier cytological steps so that a ‘ breakage-fusion-bridge cycle ’ is maintained in the subsequent cell generations. In the present communication a comparative metaphase behaviour of two unequal rings in a human subject has been studied in leucocytes grown in vitro. Our observations suggest that an alternative cytological mechanism exists for ring perpetuation that may not follow strictly McClintock’s principle of ‘ breakage-fusion-bridge cycle ’.

9 citations


Journal Article
Grosse Kp, Schwanitz G, Rott Hd, Klein K, von Zyl J 

3 citations