Cell proliferation, apoptosis, and expression of Bcl-2 and Bax in non-lactating human breast epithelium in relation to the menstrual cycle and reproductive history.

Cell proliferation, apoptosis, and the expression of Bcl-2 and Bax were investigated in breast tissue of healthy premenopausal women in order to study the effect of the menstrual cycle and reproductive history on the cell turnover in the non-lactating mammary gland epithelium. Immunohistochemistry was used to detect the proliferation-associated antigen Ki-67, as well as Bcl-2 and Bax. Apoptotic cells were identified by enzymatic labelling of fragmentized DNA (TUNEL-technique) and morphologic analysis. Consistent with published data, the proliferative activity and the frequency of apoptotic events as detected by morphologic analysis was higher in the luteal than in the follicular phase of the menstrual cycle. Parity, lactation, and age correlated with lower proliferative activity, whereas the frequency of apoptosis was not significantly influenced by the reproductive history. Staining patterns for Bax and Bcl-2 showed characteristic changes due to the menstrual cycle with a maximum of immunoreactivity for Bcl-2 in the follicular phase and for Bax in the luteal phase. However, there was no statistically significant association between Bcl-2/Bax immunoreactivity and menstrual cycle or reproductive parameters. We conclude that other molecular pathways than the Bax/Bcl-2 antagonism may additionally be involved in the regulation of apoptotic cell death in the breast epithelium. Knowledge of the entire complexity of apoptosis regulation is necessary to understand the observed effects of parity and lactation on mammary epithelial biology, and possibly to be able to influence pathological processes caused by an imbalance between cell renewal and elimination.

Intraoperative evaluation of skin-flap viability using laser-induced fluorescence of indocyanine green.

Laser-induced fluorescence of indocyanine green (ICG) is a new method for evaluating skin perfusion, which is superior to conventional fluorescein angiography. In a prospective clinical study ICG fluorescence video-angiography was used for the intraoperative evaluation of skin-flap perfusion. The results of ICG imaging were compared with clinical outcome 1 week postoperatively. Intraoperative ICG filling defects were always associated with delayed wound healing. In 50% of the patients, the regions of sloughing and epitheliolysis corresponded accurately to the regions of dye-filling deficits. All of the flaps without ICG filling defects healed primarily. These results suggest that ICG fluorescence is a sensitive tool for assessing nutritive blood flow in pedicled skin flaps with and without an axial vessel. Future clinical studies are required to establish critical threshold fluorescence indices that correlate with skin viability in the postoperative course.

Cell turnover in apocrine metaplasia of the human mammary gland epithelium: apoptosis, proliferation, and immunohistochemical detection of Bcl-2, Bax, EGFR, and c-erbB2 gene products.

Apocrine metaplasia is considered to be a benign lesion of human mammary epithelium. However, it is not known how apocrine differentiation develops, and whether there is a relationship with particular subtypes of mammary carcinoma. In order to investigate cell turnover in apocrine metaplasia, apoptosis was detected by terminal transferase nick-end-labelling, and Ki-67 was used as proliferation marker. Bcl-2, Bax, epidermal growth factor receptor (EGFR), and c-erbB2-encoded protein were detected by immunohistochemistry. The proliferative activity was low (<1%). Frequency and intraepithelial localization of apoptotic cells resembled those of normal mammary epithelium. Bax immunostaining was inconstant and weak, and Bcl-2 was not detectable in apocrine metaplasia. Immunoreactivity of the c-erbB2 gene product was membrane-bound and showed a moderate to strong intensity, whereas staining for EGFR was weak and inconsistent. When compared with normal breast epithelium, apocrine metaplasia shows a regular cell turnover at a low rate, although the expression patterns of regulatory proteins are clearly altered. Our data suggest that changes in the expression of Bcl-2 or c-erbB2 protein do not result in a significant imbalance of apoptosis and proliferation, and thus should not be interpreted as indicator for increased risk of neoplastic transformation.

Immunohistochemical analysis of Bcl-2 and Bax expression in relation to cell turnover and epithelial differentiation markers in the non-lactating human mammary gland epithelium.

The expression of the apoptosis-related proteins Bcl-2 and Bax was investigated by immunohistochemistry in the normal non-lactating human mammary gland in relation to cell proliferation and apoptosis. In order to characterize individual Bax/Bcl-2-immunoreactive cells, the epithelial markers cytokeratin 14 and 19 and the macrophage marker CD 68 were used. Secretory-like differentiation of epithelial cells was characterized by histochemistry and lectin staining of surface glycoconjugates. Cell proliferation was exclusively found in glandular epithelial cells with broad contact to the ductular lumen, whereas nuclei with apoptosis-related DNA fragmentation were seen predominantly in basally located glandular epithelial cells and in myoepithelial cells. Weak immunoreactivity for Bcl-2 and Bax was present throughout all epithelia, suggesting a balance between pro- and antiapoptotic effects in the majority of epithelial cells. However, specific cells showed a strong staining for Bax or Bcl-2. The strongly Bcl-2-immunoreactive epithelial cells were not identical with proliferating cells, but they resembled them in configuration and in the luminal intraepithelial position. In contrast, the strongly Bax-positive epithelial cells had no or only a narrow contact to the ductular lumen. The different patterns of Bax/Bcl-2 immunoreactivity in specific glandular epithelial cells suggest that there are also different grades of susceptibility towards apoptotic stimuli in individual glandular epithelial cells. We conclude that specific Bax/Bcl-2 expression patterns could reflect particular cell differentiation states, and that the strongly Bcl-2-positive cells in part could represent epithelial stem cells.

[Use of keratinocyte cultures in treatment of severe burns--experiences up to now, outlook for further subsequent developments]. / Die Verwendung von Keratinozytenkulturen in der Schwerbrandverletztenbehandlung--bisherige Erfahrungen, Ausblicke zur weiteren Entwicklung.

There is a world-wide growing interest in cultured epithelium. It is commonly accepted that cultured epithelial auto- or allografts can stimulate wound healing and shorten re-epithelialization time. Sheets of cultured autologous epidermal cells have been used for more than 15 years as grafts to achieve permanent coverage of full-thickness burn wounds. Yet many surgeons who have used cultured epidermal grafts have reported a substantial variability in their outcome. The best results have been obtained by performing early excision, followed by temporary coverage with a cadaver homograft. Within 3 weeks the donor allodermis is incorporated and forms a neodermis. The epidermal parts of the donor skin are removed after about 3 weeks and cultured epidermal autografts are transplanted (composite graft technique). There is some hope that progress in the cultivation procedure and a modified transplantation technique will shorten the healing time. In our opinion, great progress was made when cryopreserved allogeneic epithelial grafts became available for the treatment of deep dermal burn wounds. We obtained a good re-epithelialization rate (56%) after 9.5 days in 56 cases. In the last 25 cases, the re-epithelialization time was 72% after 11.5 days. Especially burn wounds of the face have been treated successfully, avoiding over-grafting and achieving highly acceptable, aesthetic and functional results. Many laboratories are developing dermal equivalents, combining synthetic and biological materials in order to form a multilayer neodermis. Although it seems possible to cultivate adnexae of the skin, a neodermis with cultivated adnexae is not yet in sight.