The presence of a type IV collagen skeleton associated with periductal elastosis in breast cancer

Using serial sections of frozen and AFA-fixed tissues from 34 breast cancers, we studied the presence of basement membrane material in the areas of elastosis. Various amounts of type IV collagen but not of laminin were demonstrated in areas of periductal elastosis. In some tumors, type IV collagen accumulated beneath the basement membrane. Periductal elastosis in areas of extensive fibrosis showed focal type IV collagen immunoreactivity, indicating remnants of ducts. Interstitial elastosis corresponded with weak type IV collagen reactivity. Each tumor showed type IV collagen immunostaining of the elastotic areas, with various degrees of intensity. Negative crossreactivity of the type IV collagen antibody with elastin was verified in skin biopsies with solar elastosis. Pre-incubation of the antibody with large amounts of elastin demonstrated an identical immunoreactivity. The specificity of the antibody was confirmed by ELISA and by Western blot analysis. To explain the periductal elastosis, we propose the following hypothesis. Excessive production of basement membrane material by the epithelial cells of the ducts leads to formation of a type IV collagen skeleton. This skeleton can act as the matrix for a secondary deposition of elastic material.Peer reviewe

5-Azacytidine and 5-aza-2'-deoxycytidine behave as different antineoplastic agents in B16 melanoma.

The antiproliferative effects of 5-azacytidine (acaCyd) and 5-aza-2'-deoxycytidine (azadCyd) were studied in murine B16 melanoma and a series of B16 melanoma derived mutant strains with selective resistances to the respective drugs. The in vitro cytotoxicities of azaCyd and azadCyd on B16 wild type, expressed in terms of IC50 values, were found to be 5 microM and 0.2 microM, respectively. The in vitro cytotoxicity of both drugs was dependent on the duration of exposure. Uridine and cytidine were able to reverse the in vitro cytotoxicity of azaCyd, but not of azadCyd. Conversely, 2'-deoxycytidine was able to reverse the cytotoxic effect of azadCyd but not of azaCyd. Thymidine and 2'-deoxyuridine had no detectable effects on the in vitro cytotoxicity of either azaCyd or azadCyd. B16 melanoma mutant strains that were selected for resistance to azaCyd showed no cross-resistance to azadCyd, cytosine arabinoside or the fluorinated pyrimidine analogues FUrd, FCyd, FdUrd and FdCyd. Mutant strains that were selected for resistance to azadCyd showed no cross-resistance to azaCyd or fluorinated pyrimidine analogs, but only to cytosine arabinoside. The combined data suggest that azaCyd and azadCyd follow different routes of intracellular metabolic activation and exert their cytotoxic activity via different intracellular targets

How fast is a snail’s pace? The influences of size and substrate on gastropod speed of locomotion

Terrestrial gastropods display monotaxic direct crawling. During locomotion, smooth muscle contraction stimulates a series of pedal waves that move along the ventral surface of the foot. These waves interact with a thin layer of mucus produced by the foot, propelling the animal forward. Although the mechanism by which this process occurs has been well studied, less is known about how morphological or environmental factors affect this process, and ultimately how they may alter the speed of propulsion. In this study, we tested the influences of body size, substrate type, and substrate orientation on crawling speed in the terrestrial snail Cornu aspersum. We found that substrate texture and orientation had a strong effect on speed, whereas snail body size and the presence of a conspecific trail did not. Crawling speed across rough sandpaper was the most striking, showing a clear inversely proportional relationship between the size of abrasive particle and speed. We suggest that this may be the result of substrate attributes interfering with mucus adhesion or mucus production, subsequently affecting locomotion, although gait choice or the frequency and length of each pedal wave may also play a role.PostprintPeer reviewe

Tuning gastropod locomotion: Modeling the influence of mucus rheology on the cost of crawling

Common gastropods such as snails crawl on a solid substrate by propagating muscular waves of shear stress on a viscoelastic mucus. Producing the mucus accounts for the largest component in the gastropod's energy budget, more than twenty times the amount of mechanical work used in crawling. Using a simple mechanical model, we show that the shear-thinning properties of the mucus favor a decrease in the amount of mucus necessary for crawling, thereby decreasing the overall energetic cost of locomotion.Comment: Corrected typo

Long-term culture of cholangiocytes from liver fibro-granulomatous lesions

BACKGROUND: Extensive bile duct proliferation is a key feature of the tissue reaction to clinical and experimental forms of liver injury. Experimental infection of mice by Schistosoma mansoni is a well-studied model of liver fibrosis with bile duct hyperplasia. However, the regulatory mechanisms of bile duct changes are not well understood. In this study we report the reproducible isolation of long-term cultures of cholangiocytes from mice livers with schistosomal fibrosis. METHODS: We have isolated a cholangiocyte cell line from Schistosoma-induced liver granulomas using a combination of methods including selective adhesion and isopyknic centrifugation in Percoll. RESULTS: The cell line was characterized by morphological criteria in optical and transmission electron microscopy, ability to form well differentiated ductular structures in collagen gels and by a positive staining for cytokeratin 18 and cytokeratin 19. To our knowledge, this is the first murine cholangiocyte cell line isolated from schistosomal fibrosis reported in the literature. CONCLUSION: After 9 months and 16 passages this diploid cell line maintained differentiated characteristics and a high proliferative capacity. We believe the method described here may be a valuable tool to study bile duct changes during hepatic injury