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J S Andrade

Publications and source records attributed to J S Andrade.

23 records · Page 2Linked to original sources
PubMed1996

Erythrophagocytosis in the caprine trophoblast.

The mechanism of iron transfer by extravasation of maternal blood in the maternal-fetal interface and the subsequent phagocytosis of the erythrocytes by the trophoblast cells was described in ovine, bovine and other species. This research was performed due to the absence of studies on this process in the goat. Fragments of placentomes were obtained from 9 adult goats of an unspecified breed and were separated into Groups A, B and C, based on 90, 120 and 150 d of gestation, respectively. Fragments of 3 placentomes were obtained from each animal of all groups. The first of them was removed from the base, the second from the middle part and the third from the end of the gestational uterine horn. The fragments were fixed in Bouin solution and histologically processed according to the usual paraffin inclusion techniques. The slides were stained by hematoxilin-eosin and potassium ferrocyanide and examined under light microscopy The erythrophagocytosis (EP) process of the trophoblast was identified in all the examined histological sections, throughout the gestation and for each placentome. An accumulation of spots of blood was observed only in the maternal-fetal interface located in the arcade zone of the placentome. The main cells of the trophoblast of these areas presented an intense phagocytic activity and the observation of erythrocytes with hemossiderin pigments in their citoplasm was possible. The trophoblast epithelium of these areas was thicker and with a columnar aspect than the cubic aspect observed in other areas. The trophoblast binucleate cells do not seem to participate in EP. Our findings indicate that the phagocitosis process of the maternal erythrocites by the trophoblast also occurs in caprine species, indicating that this could be a mechanism of transplacentary transfer of iron in this species.

Journal Article↗
PubMedDate not supplied

Mathematical modeling of the first inflation of degassed lungs.

The pressure-volume (P-V) relationship of degassed lungs during the first inflation is different from that in consecutive inflations. We developed a mathematical model of the P-V curve of the first inflation by assuming that (1) central airways are open leading to many subtrees of n generations that are initially closed; (2) an airway opens when inflation pressure reaches the opening threshold pressure of that segment; and (3) the opening threshold pressures do not depend on airway generation. In this model, airway opening occurs in cascades or avalanches. To test the model which contains only two parameters, n and a pressure, P(low), at which at least one subtree completely opens, we measured the first inflation P-V curves of 15 excised and degassed rabbit lungs. By fitting these data, we found that n=17+/-5, P(low)=23+/-4 cmH2O, and that there is a wide distribution of threshold pressures for airways with diameters <2 mm. Analysis of the P-V curve in a lung which was lavaged with a liquid of constant surface tension and in which airways are presumably open demonstrated that the distribution of threshold pressures is narrow, and hence no avalanches occur during inflation. We conclude that in normal lungs the first inflation is dominated by avalanche behavior of airway opening providing information on the global distribution of threshold pressures and the average site of airway closure.

Animals↗