Cancer of the breast

Senescence and genomic integrity are thought to be important barriers in the development of malignant lesions. Human fibroblasts undergo a limited number of cell divisions before entering an irreversible arrest, called senescence. Here we show that human mammary epithelial cells (HMECs) do not conform to this paradigm of senescence. In contrast to fibroblasts, HMECs exhibit an initial growth phase that is followed by a transient growth plateau (termed selection or M0; refs 3-5), from which proliferative cells emerge to undergo further population doublings (approximately 20-70), before entering a second growth plateau (previously termed senescence or M1; refs 4-6). We find that the first growth plateau exhibits characteristics of senescence but is not an insurmountable barrier to further growth. HMECs emerge from senescence, exhibit eroding telomeric sequences and ultimately enter telomere-based crisis to generate the types of chromosomal abnormalities seen in the earliest lesions of breast cancer. Growth past senescent barriers may be a pivotal event in the earliest steps of carcinogenesis, providing many genetic changes that predicate oncogenic evolution. The differences between epithelial cells and fibroblasts provide new insights into the mechanistic basis of neoplastic transformation.

Normal human mammary epithelial cells spontaneously escape senescence and acquire genomic changes.

The transfer of DNA across membranes and between cells is a central biological process; however, its molecular mechanism remains unknown. In prokaryotes, trans-membrane passage by bacterial conjugation, is the main route for horizontal gene transfer. It is the means for rapid acquisition of new genetic information, including antibiotic resistance by pathogens. Trans-kingdom gene transfer from bacteria to plants or fungi and even bacterial sporulation are special cases of conjugation. An integral membrane DNA-binding protein, called TrwB in the Escherichia coli R388 conjugative system, is essential for the conjugation process. This large multimeric protein is responsible for recruiting the relaxosome DNA-protein complex, and participates in the transfer of a single DNA strand during cell mating. Here we report the three-dimensional structure of a soluble variant of TrwB. The molecule consists of two domains: a nucleotide-binding domain of alpha/beta topology, reminiscent of RecA and DNA ring helicases, and an all-alpha domain. Six equivalent protein monomers associate to form an almost spherical quaternary structure that is strikingly similar to F1-ATPase. A central channel, 20 A in width, traverses the hexamer.

The bacterial conjugation protein TrwB resembles ring helicases and F1-ATPase

Cancer research has previously focused on the identification of specific genes and pathways responsible for cancer initiation and progression based on the prevailing viewpoint that cancer is caused by a stepwise accumulation of genetic aberrations This viewpoint, however, is not consistent with the clinical finding that tumors display high levels of genetic heterogeneity and distinctive karyotypes We show that chromosomal instability primarily generates stochastic karyotypic changes leading to the random progression of cancer This was accomplished by tracing karyotypic patterns of individual cells that contained either defective genes responsible for genome integrity or were challenged by onco-proteins or carcinogens that destabilized the genome Analysis included the tracing of patterns of karyotypic evolution during different stages of cellular immortalization This study revealed that non-clonal chromosomal aberrations (NCCAs) (both aneuploidy and structural aberrations) and not recurrent clonal chromosomal aberrations (CCAs) are directly linked to genomic instability and karyotypic evolution Discovery of "transitional CCAs" during in vitro immortalization clearly demonstrates that karyotypic evolution in solid tumors is not a continuous process NCCAs and their dynamic interplay with CCAs create infinite genomic combinations leading to clonal diversity necessary for cancer cell evolution The karyotypic chaos observed within the cell crisis stage prior to establishment of the immortalization further supports the ultimate importance of genetic aberrations at the karyotypic or genome level Therefore, genomic instability generated NCCAs are a key driving force in cancer progression The dynamic relationship between NCCAs and CCAs provides a mechanism underlying chromosomal based cancer evolution and could have broad clinical applications

Stochastic cancer progression driven by non-clonal chromosome aberrations.

Cytogenetic and molecular aspects of gastric cancer: Clinical implications

BACKGROUND: There are numerous advantages in closing the pericardial cavity after heart surgery and intrapericardial pneumonectomies. OBJECTIVE: To study the behavior of a natural latex membrane as a partial pericardium substitute. MATERIAL AND METHODS: Sixteen dogs divided into 3 groups were submitted to resection of an elliptical flap of the left anterolateral portion of the pericardium (7 x 5 cm): Group A (n=4) - the removed flap was immediately reimplanted; Group B (n=8) - the flap was replaced with a 0.3 mm thick natural latex membrane of equivalent area; Group C (n=4) - the latex flap was 0.7 mm thick. In all animals the flap was fixed with continuous 5-0 or 6-0 polypropylene sutures. In group C, 4 additional U-shaped stitches anchored with dacron pledgets were applied. All animals were submitted to ECG and to white cell counts during the preoperative period as well as to macro- and microscopic post mortem study. RESULTS: Group A - the self-graft was macro and microscopically intact, strongly adhering to the lung and loosely adhering to the epicardium; Group B - total suture dehiscence occurred in 1 animal and partial dehiscence in 2. The latex membrane did not adhere to the lung or to the epicardium. In 3 animals (37.5%) there was full regeneration of the pericardium underlying the natural latex, microscopically identical to the native pericardium. Group C - the sutures were intact and total pericardium regeneration was observed in 3 animals (75%). In the remaining animals of Groups B and C, the epicardium underlying the latex was slightly thickened, permitting easy visualization of the coronary vessels. Some areas with dense lymphocytes and plasma cells infiltrates, fibroblast and vascular proliferation were microscopically identified in its thickness; in some other areas the fibroblasts surrounded slits with mesothelial lining indicating irregular pericardium regeneration. No local infection or changes in white cell counts were observed and the ECG only showed T wave inversion in all groups. CONCLUSION: The natural latex membrane proved to be adequate for partial pericardium replacement in dogs kept under observation for up to 345 days, favoring regeneration of the native pericardium.

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Substituição parcial do pericárdio de cães por membrana de látex natural

Objectives: Solid caustic soda (CS) ingestion levels continue high in Brazil. The aggressiveness of a caustic agent depends, among other factors, on its concentration and time of contact with mucosa. However, the interdependence of these factors in the production of caustic lesion in the esophageal mucosa is not known, especially regarding CS as the strongest corrosive agent. We analyze the effects of concentration and time of contact on the aggressiveness of CS to the esophagus of live animals.



Study Design/Methods: One milliliter of CS at concentrations between 1.83% and 73.33% was applied to rats. The solution was kept in contact with the mucosa for 10 to 120 minutes. Internal and external organ aspects were analyzed and the epithelium, submucosa, muscle layer, and adventitia were analyzed microscopically



Results: Epithelial necrosis was observed at all concentrations. Among the necrotic layers, the submucosa was observed starting at the 7.33% concentration, and the muscular layer and adventitia were observed at 14.66% concentration. Damage to the pulmonary parenchyma and trachea occurred at 33.66% after 10 minutes, and perforation of the esophagus was observed only after 120 minutes. After 10 minutes, important corrosive lesions installed in the esophageal layers, expanding in depth and superficial extension. The use of heparin had no effect on the production of lesions.



Conclusions: Ten minutes were sufficient to provoke necrosis, and longer contact increased the area of necrosis. Solution concentration levels were more important in damage production: 1.83% was sufficient for epithelial necrosis, 7.33% caused submucosal necrosis, and 14.66% muscle and adventitia necrosis; 33.66% solutions caused lung and trachea damage after 10 minutes and esophageal perforation after 120 minutes.

Effects of time of contact and concentration of caustic agent on generation of injuries.

OBJECTIVE: to assess the regeneration of osteochondral defects in the joint cartilage of the knee induced by autologous platelet-rich plasma (pRp). METHODS: osteochondral defects produced in the trochlear groove of both knees of ten sheep; defects of the right knees were filled with autologous pRp and the left knees were left unfilled. macroscopic and microscopic evaluation was carried out 12 week later. the results were evaluated by the total score of both macroscopic and microscopic evaluations comparing the two sides through the wilcoxon paired test. RESULTS: macroscopic appearance was not uniform among animals, nor was it different between the right and left knees (p=0.3125), and in no case the regenerated tissue was equal to the normal surrounding cartilage. at histological examination, apparently normal cartilage was not detected in any knee, but a poorly differentiated cartilage was present in 7 right knees, compared to 3 left knees. fibrocartilaginous tissue was present in most of the remaining knees, with a significant difference in the overall score between right and left knees (p=0.0313). CONCLUSION: the pRp as used in this study has reparative properties of the joint cartilage of sheep knees, mostly by stimulating the formation of a fibrocartilaginous tissue. Laboratory Investigation.

/pdf/platelet-rich-plasma-gel-promotes-regeneration-of-articular-vtbob0q2th.pdf

José Barbieri Neto

Papers

Substituição parcial do pericárdio de cães por membrana de látex natural

Effects of time of contact and concentration of caustic agent on generation of injuries.

Platelet-rich plasma gel promotes regeneration of articular cartilage in knees of sheeps

Cytogenetics of epithelial hyperplasias of the human breast.

Enhanced TGFα-EGFR expression and P53 gene alterations contributes to gastric tumors aggressiveness