Chromosome aberrations, sister chromatid exchanges and micronuclei were studied in irradiated and unirradiated peripheral blood lymphocytes of smokers and nonsmokers. No effect of smoking could be observed in the number of chromosome aberrations, either in the irradiated or nonirradiated samples. Smokers had significantly elevated SCE values in the unirradiated samples, but the difference in SCE frequencies between smokers and nonsmokers in the irradiated series was not significant. The mean frequency of micronuclei in smokers was significantly higher than in nonsmokers. After irradiation the mean difference in micronuclei frequencies between smokers and nonsmokers was greater than the difference between the unirradiated samples of the two groups.
Cytological findings in 5 individuals with structurally abnormal X chromosomes are presented. Of 4 patients with an i(Xq) chromosome, 2 had an apparently dicentric, and 2 an apparently monocentric isochromosome. The former type of chromosome had twice as much centric heterochromatin (2 distinct C‐bands) as the latter. In the apparently dicentric isochromosomes, it could not be determined whether one or both centromeres were functional. These findings confirm our previously presented hypothesis that transverse breakage of the X chromosome in the centromere region leading to isochromosome formation may occur at more than one site.
A 60‐year‐old female, 154 cm in height, with primary amenorrhoea and no other signs of Turner's syndrome, had 46 chromosomes, including a normal X and a giant chromosome composed of two X chromosomes joined end to end by their short arms. By conventional staining this chromosome had 1 centromere, but C‐banding revealed centric heterochromatin both in the centromere and at the site where the centromere of the second component chromosome should have occurred. It is inferred that centric heterochromatin can occur elsewhere than at the centromere and is not necessarily associated with kinetochore function.
Thoracic duct drainage and re-infusion of the irradiated lymph was carried out as immunosuppressive treatment in 2 patients with progressive, therapy-resistant rheumatoid arthritis. In both patients, a marked clinical improvement was achieved even during the first days of treatment. A reduced number of T cells in the blood was seen 3 days after onset of drainage, whereas no significant change in the number of B cells was observed. No recirculation of the infused cells could be detected, nor was the radiation removal of T cells accompanied by rapid proliferation of "new" T cells. As clinical improvement and reduction in T cells occurred simultaneously, there is probably a connection between these two events. The beneficial clinical response and the achievement of T cell suppression by thoracic duct drainage--the result of irradiation and re-infusion of irradiated lymph--encourage further clinical trials with this type of treatment in severe therapy-resistant rheumatoid arthritis.
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