Showing papers by "Pan American Health Organization published in 1981"
TL;DR: Immune serum obtained from mice with a chronic infection of Trypanosoma cruzi was fractionated on Sephadex G-200 or on protein ASepharose 4B and demonstrated that the protective antibodies were mostly IgG2 and seem to be preferentially located in IgG 2b subclass.
79 citations
TL;DR: The notion that antibodies found in the breast milk reflect the mother's intestinal antigenic experience is supported by this study, and it has been suggested that anti-food protein antibodies contribute in the prevention of allergies.
32 citations
TL;DR: Using a defined culture medium, it was shown that Trypanosoma cruzi epimastigotes (strains Y, Ma, and F1) do not require exogeneous nucleotides for continuous cultivation and have the capacity for de novo nucleotide synthesis.
5 citations
TL;DR: Cattle, sheep, goats, and horses in most areas of Barbados were examined for ticks, finding that most of the cattle were infested with the southern cattle tick, Boophilus microplus (Canestrini), a vector of bovine babesiosis and anaplasmosis.
3 citations
TL;DR: If endogenous prolactin secretion is important in normal development of fetal lung surfactant, the inhibition of its secretion should be associated with delayed maturation of fetal lungs, and the effect of bromoergocriptine administration to pregnant rabbits upon lecithin content of Fetal lung washes was studied.
Abstract: Summary: If endogenous prolactin secretion is important in normal development of fetal lung surfactant, the inhibition of its secretion should be associated with delayed maturation of fetal lung. We therefore studied the effect of bromoergocriptine administration to pregnant rabbits upon lecithin content of fetal lung washes. The does were treated since the 27th day of gestation with either Mesilate of 2-Bromo-α-ergocriptine (C32H40BrN5O5, CH3SO3H) (Bromocriptine) (Parlodel, Sandoz) (1 mg/kg/day) or solvent twice daily until delivery. The newborns were killed immediately by intraperitoneal administration of sodium penthobarbital and tracheostomized; then lung washes were performed. The extracted lipids were plated and run on heat-activated thin layers of silica gel H. Lecithin was eluted, and phosphorus determination was performed. The level of lecithin phosphorus in the lung washes of the fetuses whose mothers received Bromocriptine was X = 2.24 ± 0.39 μg/g dry lung weight, whereas that of fetuses of control does was X = 6.93 ± 2.64 μg/g dry lung weight (P < 0.001). The mean body weight of the fetuses from treated mothers was 38.22 ± 6.39 g whereas that of fetuses from control rabbits was 47.63 ± 6.94 g (P < 0.001). The mother's body weight gain from days 26 to 30 in Bromo-criptine-treated rabbits was 156.11 ± 99.4 g, whereas that of controls was 374.38 ± 166.21 g (P < 0.01). Speculation: Prolactin could be involved in the normal biochemical development of the lung and also be necessary for a normal weight gain of mother and fetuses during the last stage of gestation.
3 citations
3 citations
TL;DR: It has been demonstrated that glucocorticoids have an important role in accelerating the process of the development of fetal lung maturation and it is speculated that cortisol has a permissive role which allows the action of other hormones.
Abstract: Summary: It is well known that corticoids act to induce fetal lung maturation when administered to the fetus or mother. However, their physiologic role has been recently questioned with regard to stimulation of surfactant production. We investigated the process of fetal lung maturation to determine whether or not it is associated with changes in amniotic fluid cortisol. Sixty-two amniotic fluid samples from 53 patients were obtained by transabdominal amniocentesis strictly due to maternal and/or fetal clinical indication, according to the course of pregnancy and the maternal and/or fetal status. The L/S ratio was measured on thin-layer plates by reflectance densitometry and calculated as previously described by Gluck et al. Cortisol levels in amniotic fluid were measured by radioimmunoassay using commercial reagent kits (Gamma coat I125 cortisol; Clinical Assays, Inc.). The level of amniotic fluid cortisol increased with gestational age from wk 30 to 41; a sharp increment was observed at 39 to 41 wk. No significant differences were found when the mean values of cortisol were compared at wk 30 to 32, 33 to 35, and 36 to 38. When the fourth group was included (39 to 41 wk), a statistically significant difference was found (F = 4.63; P < 0.01). There was a progressive increase in L/S ratio during gestation as has already been described, plus a value greater than 2 was found during the 33 to 35 wk period. The statistical analysis performed on L/S ratios at weekly intervals 30 to 32, 33 to 35, and 36 to 38 showed a significant difference in the mean values in the groups studied (F = 6.84; P < 0.005). Therefore, the increment of L/S ratio over 2 was already observed during the 33 to 35 wk period of gestation, whereas the mean cortisol amniotic fluid values remained unchanged between the 30th and the 38th wk. The cortisol peak was observed only during the 39 to 41 wk period. Speculation: It has been demonstrated that glucocorticoids have an important role in accelerating the process of the development of fetal lung maturation. The physiologic fetal lung surfactant production does not necessarily depend on the increase of fetal cortisol levels. It is speculated that cortisol has a permissive role which allows the action of other hormones.
2 citations