Morphometric changes in the corpus luteum of pregnant hypokinetic rats.

The aim of this work was to study the influence of hypokinetic conditions on the ovary and corpus luteum of pregnant rats. The rats were kept in hypokinetic conditions for 5 days in the period between the 13th and 18th days of pregnancy. A three-dimensional reconstruction of the ovary and corpora lutea and also a stereological evaluation of the luteal cells and their nuclei were performed using serially cut material.

AAF-cmk sensitizes tumor cells to trail-mediated apoptosis.

TRAIL is a member of the tumor necrosis factor (TNF) superfamily. This cytokine is cytotoxic for a high proportion of tumor cells, but could be also toxic for normal cells. There is a need to find other agents able to potentiate the antitumor effects of this cytokine.

Proteasome localization and ultrastructure of spermatozoa from patients with varicocele--immunoelectron microscopic study.

Localization of proteasomes in spermatozoa from patients with varicocele-associated sterility was studied by means of immunolabeling with the MPC21 monoclonal antibody detecting the C3 subunit of the 20S proteasome. The reaction was visualized for electron microscopy using the secondary Nano-Gold-coupled antibody with Gold-Enhancement in pre-embedding technique. We found that semen samples from varicocele patients contained a large amount of abnormal spermatozoa characterized by the presence of dispersed chromatin and large residual bodies (cytoplasmic droplets) as well as spermatids at various stages of spermiogenesis.

Effects of the combination of a proteasome inhibitor (PSI) and an inhibitor of ubiquitin-ligases (Leu-Ala) on the ultrastructure of human leukemic U937 cells.

We have used the dipeptide Leu-Ala in an attempt to prevent the formation of ubiquitin-protein conjugates in U937 cells by inhibition of cellular E3 enzymes (ubiquitin ligases). Proteasome inhibitors induce the formation of perinuclear aggregates of ubiquitinated proteins and proteasomes (aggresomes) in the area of the proteolytic center of the cell. Leu-Ala did not prevent the forrmation of those aggregates under the action of PSI (peptidyl aldehyde, selective inhibitor of the chymotrypsin-like activity of the proteasome), however it induced an accumulation of lipid droplets in treated cells, suggesting a previously unknown involvement of Leu-Ala in lipid metabolism.

Localization of a proteasomal antigen in human spermatozoa: immunohistochemical electron microscopic study.

The ultrastructural localization of a proteasomal antigen in human spermatozoa was studied by means of immunolabeling with the MPC21 monoclonal antibody and secondary gold labeled antibody with 1.4 nm gold particles in combination with silver enhancement reaction using pre-embedding technique. The labeling was found in the acrosomal and postacrosomal regions, in the connecting-piece (neck) and, in some cases, in the middle-piece and also in the residual bodies.