Differences in the glutathione system of cultured aortic smooth muscle cells from young and aged rats

We studied the relation between the glutathione (GSH) system and cell proliferation in a model of smooth muscle cells (SMC) derived from the thoracic aorta of 4–6-week-old (young) and 15-month-old (aged) rats. SMC from aged rats showed greater levels of total non-protein thiol compounds (T-SH), increased glutathione transferase (GST) and increased glutathione reductase (GSSG-Red) activities compared with cells from young rats. These changes were associated with an increased proliferation rate of SMC from aged rats. To evaluate the role of GSH on cell proliferation better, a specific inhibitor of gamma-glutamyl-cystein synthetase, -buthionine-SR-sulphoximine (BSO) was used. BSO showed a dose-dependent inhibition of cell growth, with an IC₅₀ of 10⁻⁴ M, after 48–72 h of incubation. Removal of BSO restored cell growth, further suggesting a link between GSH levels and vascular cell proliferation. The inhibitory effect of BSO was about two times greater on SMC from young than on SMC from aged rats. BSO showed 56% inhibition on the proliferation of SMC from young rats and 32% inhibition on SMC from aged rats (10⁻⁴ M, 72 h of incubation). A parallel reduction of GSH levels of 38% and 19% for SMC from young and aged rats, respectively, was observed, suggesting that age-related factors may influence the involvement of GSH system in cell proliferation.     

Mediastinal large B-cell lymphoma: clinical and immunohistological findings in 18 patients treated with different third-generation regimens

We report on the immunophenotype, clinical findings and response to aggressive chemotherapy of 18 patients with mediastinal large B-cell lymphoma (MLCL). Cases were collected from a series of 286 high-grade non-Hodgkin's lymphomas (HG-NHL) which, in the period September 1988 to August 1991, were enrolled in a prospective multicentre trial designed to compare the MACOP-B and F-MACHOP regimens. Immunostaining on frozen sections revealed a previously unrecognized phenotype, i.e. co-expression of B-cell (CD19, CD20, CD22, Ig-associated dimer) and activation-associated antigens (CD30 and CDw70) in about 60% of MLCL cases; in contrast, the activation-associated antigens CD25 and Ki-27 (unclustered) were consistently negative. This peculiar phenotype may reflect a derivation of the tumour from a subset of thymic activated B cells. Clinically, the patients (median age 31 years; F/M ratio 2.6) presented with bulky mediastinal mass (72%) associated with mediastinal syndrome in >50% cases; disease was stage IIA in most cases. All 18 patients received aggressive chemotherapy (F-MACHOP 11; MACOP-B 7). Complete response (CR) was achieved in 57.1% of cases treated with MACOP-B. In contrast, the response of the 11 MLCL treated with F-MACHOP was poor (CR 18.2%) as compared to that of the 135 HG-NHL treated with the same regimen during the trial (CR 69.6%). This difference was still statistically significant after adjusting for negative prognostic factors (mediastinal mass > 10 cm plus increased LDH) and suggests that F-MACHOP might not be the most appropriate regimen for this kind of lymphoma.     

Virus species polemics: 14 senior virologists oppose a proposed change to the ICTV definition of virus species

The Executive Committee of the International Committee on Taxonomy of Viruses (ICTV) has recently decided to modify the current definition of virus species (Code of Virus Classification and Nomenclature Rule 3.21) and will soon ask the full ICTV membership (189 voting members) to ratify the proposed controversial change. In this discussion paper, 14 senior virologists, including six Life members of the ICTV, compare the present and proposed new definition and recommend that the existing definition of virus species should be retained. Since the pros and cons of the proposal posted on the ICTV website are not widely consulted, the arguments are summarized here in order to reach a wider audience.     

A case of Burkitt lymphoma-L3ALL with t(8;14) translocation, developed 10 years after Hodgkin's disease

We report the case of a 38-year-old man, previously treated for Hodgkin's disease (HD) with chemo-radiotherapy who, 10 years later, developed a Burkitt lymphoma (BL) as a tumour mass of the ascendent colon and regional lymph nodes and, subsequently, on leukaemic bone-marrow cells, on the basis of histological, immunological (B phenotype, IgM-lambda) and cytogenetic, translocation t(8;14) features. The patient died a few days later; at autopsy no evidence of HD was found. This is the 2nd case of BL developing after HD so far described. The relationship between the 2 diseases is discussed and the importance of the immunodepression in the pathogenesis of the secondary Burkitt lymphoma is emphasized.     

Development of large numbers of mast cells at sites of idiopathic chronic dermatitis in genetically mast cell-deficient WBB6F1-W/Wv mice

The normal skin and other tissues of adult mast cell-deficient WBB6F1- W/Wv or WCB6F1-Sl/Sld mice contain less than 1.0% the number of mast cells present in the corresponding tissues of the congenic normal (+/+) mice. As a result, genetically mast cell-deficient WBB6F1-W/Wv or WCB6F1-Sl/Sld mice are widely used for studies of mast cell differentiation and function. We found that mast cells developed at sites of idiopathic chronic dermatitis in WBB6F1-W/Wv mice and that the number of mast cells present in the skin of WBB6F1-W/Wv mice was proportional to the severity of the dermatitis (in ear skin, there were 33 +/- 4 mast cells/mm2 of dermis at sites of severe dermatitis v 9 +/- 3 at sites of mild dermatitis, 0.8 +/- 0.3 in skin without dermatitis, and 100 +/- 7 in the normal skin of congenic WBB6F1-+/+ mice; in back skin, the corresponding values were 2.0 +/- 0.6, 1.1 +/- 0.9, 0.025 +/- 0.025, and 26.2 +/- 3.2). The development of mast cells was a local, not systemic, consequence of the dermatitis. Thus, WBB6F1-W/Wv mice with severe dermatitis lacked mast cells in skin not showing signs of dermatitis and also in the peritoneal cavity, stomach, cecum, and tongue. Idiopathic chronic dermatitis was not associated with the local development of mast cells in WCB6F1-Sl/Sld mice, a mutant whose mast cell deficiency is due to a mechanism distinct from that of WBB6F1-W/Wv mice. These findings may have implications for understanding the nature of the mast cell deficiency in WBB6F1-W/Wv and WCB6F1-Sl/Sld mice and for the use of these mutants to analyze mast cell differentiation and function.