[A case of myelodysplastic syndrome transforming into acute B-cell lymphoid leukemia]

Case history of a seventy year old man with myelodysplastic syndrome is presented. The disease terminated into acute leukaemia in 22 months. The pure, B lymphoid stem cell nature of the leukaemic cells has been proved, beside morphology and cytochemistry, by detailed flow cytometric phenotyping and PCR amplification as well as sequencing of the immunoglobulin heavy chain gene CDR3 region.

Cell kinetic analysis in recurrent neuro-epithelial tumours

The biological behaviour of brain tumours is variable. In the majority of cases, recurrence of the tumour is the decisive factor determining the prognosis and individual survival of patients suffering from a neuro-epithelial neoplasm. The time course of recurrences varies significantly according to differences in tumour cell proliferation. In this study, predictive factors concerning the expected prognosis following the resection of neuro-epithelial tumours were investigated with the aim of improving the histological diagnosis. A retrospective analysis of 22 recurrent neuro-epithelial tumours (recurrent tumour group) and 12 neuro-epithelial tumours with a minimum survival rate of 5 years following radical excision (cured tumour group) was performed by means of flow cytometry and immunohistochemistry using the MIB 1 antibody. Histological samples of the subgroups of the recurrent tumour group, i. e., the primary tumours and their recurrences were compared with each other, and the subgroups were compared with the cured tumour group. A multivariate analysis of the data was performed with the BMPD Hotteling T square test. A statistically significant difference was found between the recurrent tumour group (primary tumours + recurrences) and the cured group from every investigated aspect. On the other hand, no difference could be found between the sub-groups primary tumours and their recurrences. All tumours in the recurrent group had an accelerated, active cell cycle, which was expressed in a high proliferation activity. The following conclusion was drawn: an increased risk of recurrence is to be expected in neuro-epithelial tumours characterized by: an S-phase fraction higher than 6-9%, an MIB 1-labelled cell number higher than 2-3/high-power fields, and a number of mitoses higher than 1/10 high-power fields.

Nucleolin and fibrillarin expression in stimulated lymphocytes and differentiating HL-60 cells. A flow cytometric assay

Nucleolin and fibrillarin are two histone-like major proteins in the nucleolus that were found to be overexpressed in proliferating cells. Using specific antibodies to either nucleolin or fibrillarin flow cytometric, measurements were carried out to demonstrate quantitative changes of these proteins during lymphocyte mitogenic activation and differentiation of HL-60 promyelocytic leukaemia cells. The expression of nucleolin increased during lymphocyte stimulation and decreased slowly but constantly in the course of differentiation of HL-60 cells. Expression of fibrillarin reached a maximum in the first cell cycle and then dropped to a basic level in stimulated lymphocytes. Compared to nucleolin, the level of fibrillarin decreased more rapidly and more extensively in differentiating HL-60 cells. The data support other observations that nucleolin is a stabile structural protein at the ribosomal genes while fibrillarin may have a more specific functional role in nucleologenesis and ribosome production.

In situ fluorescent visualization of nucleolar organizer region-associated proteins with a thiol reagent

Nucleolar organizer regions (NORs) are nucleolus-forming rDNA loops associated with argyrophil proteins, the amount of which varies according to the proliferative state of the cell. It has been presumed that the nucleolar protein-related thiol groups may have a role in selective silver staining. We investigated the nuclear thiol distribution with a fluorescent thiol reagent, coumarinyl-phenyl-maleimide (CPM) in human K-562 myeloblast cultures and found that SH group-related fluorescence was brightest in the area of nucleoli, which became highly selective after RNAse digestion. A remarkable co-localization of AgNOR silver reaction and CPM fluorescence was observed, although occupation of the SH groups by CPM did not prevent the silver staining. We applied the stain to dual-parameter flow cytometry in combination with DNA content measurements, which provide further information on nucleolar function and changes in experimental and pathological specimens.

[Protothecosis. A new, or rarely recognized disease?]

Two cases of infection caused by Prototheca, belonging to the colourless algae, are discussed. In one of the patients colpitis, in the other one disease of the cubital bursa developed due to Prototheca. In the first case recovery was attained with tetracyclin, in the second case with surgical treatment. Microbiology, epidemiology, pathology and clinical aspects of the insufficiently known in Hungary protothecosis are outlined.