Tumour suppressor genes retinoblastoma (Rb1) and adenomatous polyposis coli (Apc) as well as the proliferating cell nuclear antigen (PCNA) are involved in embryonic development. The purpose of the present study was to investigate the expression of Rb1 protein, APC protein and PCNA during development of the human foetal testis. Qualitative analysis of their expression at the singlecell level was performed using immunohistochemistry on archive samples of the foetal testis (18-37 gestation week). Stereological parameters (volume density, absolute volume, numerical density, absolute number) were calculated for quantification of the overall expression of those proteins that were expressed frequently enough for such an analysis. PCNA was frequently expressed in nuclei of immature Sertoli cells and prospermatogonia and less frequently in surrounding peritubular (myoid) and interstitial cells. The pRb1 protein was present in nuclei of prospermatogonia and Sertoli cells but was absent from the interstitial tissue. APC protein was expressed in the cytoplasm of a very small number of prospermatogonia and interstitial (Leydig) cells. The overall expression of PCNA in all stages of development was higher than pRb1 expression.
In a unique serum- and protein-free chemically defined in vitro culture model of postimplantation mammalian development the epidermis differentiates regularly, although the differentiation of other tissues is impaired due to the lack of the serum. The present study in that model was done to estimate more carefully the degree of epidermal differentiation in defined media supplemented with some growth- or differentiation-stimulating substances. The main objective was to discover by grafting in vivo to the richer environment whether simple protein-free culture conditions restrict an inherent embryonic potential for differentiation of skin appendages. Embryonic parts of E9.5 gastrulating Fischer rat embryos were cultivated for 2 weeks in the protein-free Eagle’s minimum essential medium supplemented with holotransferrin, apotransferrin, insulin and/or Na2SeO3 and in controls cultivated in protein-free medium or in serum-supplemented medium. In all experiments there was a high incidence of differentiation of the epidermis. A high level of epidermal differentiation was confirmed for the first time at the ultrastructural level. A well-differentiated cornified layer and cells connected with desmosomes containing keratohyaline masses and cytokeratin filaments were found. A strong immunohistochemical signal for the proliferating cell nuclear antigen was always detected in the basal layer of the epidermis showing that those cells were still able to proliferate. Finally, embryos precultivated for 1 or 2 weeks in the protein-free medium and media supplemented with apotransferrin or serum were grafted under the kidney capsule for an additional 2 weeks. It was discovered that even after spending 2 weeks in the simple protein-free medium in vitro, embryos retained their developmental potential for differentiation of skin appendages (hair and sebaceous glands).
Human physiological activity and condition during illness are under the control of the circadian rhythm. Circadian rhythms handle a wide diversity of physiological and metabolic functions, and the interruption of these rhythms has been linked to obesity, sleep disorders, metabolic and psychological disorders, and cardiovascular events such as myocardial infarction (MI), stroke, and vascular death. Disruption of circadian rhythms increases the risk of developing myocardial infarction, indicating that circadian genes might play an essential role in determining disease susceptibility. It is well known that many cardiovascular processes show daily variations depending on the circadian rhythm (blood pressure, heart rate), and the gene expression of the cardiomyocyte circadian clock influences myocardial contractile function, metabolism, and other gene expressions. We present a review of the latest knowledge on the impact of circadian rhythm and circadian rhythm genes on myocardial infarction. Today, in a time of personalized medicine, it is essential to know each person's circadian rhythm for its treatment and possible inclusion in the diagnostic procedures.
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