Cecilia Merkis - Academia.edu (original) (raw)

Papers by Cecilia Merkis

The apoptosis or programmed cellular death is an essential, permanent, dynamic and interactive bi... more The apoptosis or programmed cellular death is an essential, permanent, dynamic and interactive biological process by which an organism eliminates the undesirable cells without activation of the immune system or generalized inflammation. Through a genetic programming of the cell a cascade of morphologic and biochemical, dependent changes is promoted of energy, that lead to the death and cellular elimination . The programmed cellular death constitutes a key factor in the development of different physiological processes such as the placentation, an essential reproductive phenomenon in most mammals. It can be induced through intrinsic or mitocondrial route or by extrinsic route that begins by binding ligands to membrane receptors . Early gestation in pigs, is characterized by rapid development and growth of the uterus and the embryos, resulting in the formation of an epiteliochorial, diffuse, noninvasive, folded and adecidua placenta . The placenta plays a fundamental role during the gestation, allowing the maternal-fetal recognition, implantation and maintenance of the pregnancy, and also determining the survival of the piglet. Preliminary reports on remodelling of porcine placental cells have been done in our laboratory through morphologic and immunohistochemical detection of apoptosis, in an attempt to characterize this process during the porcine placentation . The purpose of this study was to investigate cellular apoptosis by TUNEL, TEM and the expression of cellular death receptors FAS B-10, FAS C-20, FAS ZB4, DR4 and mitochondrial proteins Bcl-2 and Bax; to determine the signalling pathways involved in the remodelling porcine placenta. Histological cuts of porcine placenta of ± 30, 55, 70, 80 and 114 days of pregnancy were used. The DNA fragmentation was made by TUNEL ApopTag® (Chemicon). Commercial antibodies and the kits LSAB®+Systems HRP and DAB+Substrate Chromogen System (Dako Cytomation) were used for the immunohistochemical. The results of immunohistochemical were expressed in semiquantitative form, determining: (-): negative, (±): poor, (+): positive, (++): abundant and (+++): considerable label. The presence of apoptotic cells was observed through the pig pregnancy by TEM. DNA fragmentation in situ was observed in placental villi of 30 days of gestation with a staining as patches, whereas in the other gestational periods the labelling was linear. Through electronic microscopy of transmission, signs characteristic of apoptosis in the epithelial cells of the placental villi were observed, in the analyzed placental periods. Throughout the gestation the expression in placental villi of receptor DR4 were negative.

Journal of applied microbiology, 2012

Aims: To examine Saccharomyces cerevisae strains with previously reported beneficial properties ... more Aims: To examine Saccharomyces cerevisae strains with previously reported beneficial properties and aflatoxin B1 binding capacity, for their ability to remove ochratoxin A (OTA) and zearalenone (ZEA) and to study the relation between cell wall thickness and detoxificant ability of yeast strains.Methods and Results: A mycotoxin binding assay at different toxin concentrations and the effect of gastrointestinal conditions on mycotoxin binding were evaluated. Ultrastructural studies of yeast cells were carried out with transmission electronic microscopy. All tested strains were capable of removing OTA and ZEA. Saccharomyces cerevisiae RC012 and RC016 showed the highest OTA removal percentage, whereas RC009 and RC012 strains showed the highest ZEA removal percentages. The cell diameter/cell wall thickness relation showed a correlation between cell wall amount and mycotoxin removal ability. After exposure to gastrointestinal conditions, a significant increase in mycotoxin binding was observed.Conclusions: All tested Saccharomyces cerevisiae strains were able to remove OTA and ZEA, and physical adsorption would be the main mechanism involved in ochratoxin A and ZEA removal. Gastrointestinal conditions would enhance adsorption and not decrease mycotoxin–adsorbent interactions.Significance and Impact of the Study: Live strains with mycotoxin binding ability and beneficial properties are potential probiotics that could be included in animal feed. Previous and present results suggest that the RC008 and RC016 strains are very promising candidates for functional feed product development.

Demineralized bone matrix (DBM) is often used to treat bone defects due to its osteoinductive and... more Demineralized bone matrix (DBM) is often used to treat bone defects due to its osteoinductive and
osteoconductive properties. The aim of this work is to evaluate the characteristics and evolution of the
repair of experimental radial orthopaedic bone defects treated with DBM. DBM was prepared from
rabbit bone obtained from cadavers, which were fragmented, defatted, demineralized and preserved in
alcohol. Ten New Zealand rabbits were used. Critical size defects were created in one of the radiuses.
The defects of 8 rabbits were filled with DBM while the other 2 rabbits did not receive any treatment.
Each rabbit was radiologically followed at 15, 25, 40, 60 and 90 days. The untreated animals did not
show presence of new bone in relation to the defect, whereas the DBM-treated defects were completely
filled at day 90. The presence of new bone was evident from day 15 onward until the entire
defect was repaired. The production of bone at each post operative period was statistically significant
(P<0.0001) between the control examinations on days 15, 25 and 40, while at post operative days 60
and 90 there was no significant difference (P>0.05). The pattern of defects’ repair started with presence
of new bone at the extremes of defects and continued towards their centre.

Journal of applied microbiology, 2012