Uptake and passage of beta-lactoglobulin, palmitic acid and retinol across the Caco-2 monolayer.

Caco-2 cell line grown on collagen coated polycarbonate membranes in bicameral chambers has been used to study the effect of the binding of palmitic acid or retinol on the uptake and passage of iodinated beta-lactoglobulin and albumin across cell monolayers. The percentage of beta-lactoglobulin transported through the monolayer was higher than that of albumin, about 50% and 30% of the total protein after 24 h of incubation, respectively. In all cases, less than 1% of protein was retained intracellularly. No differences were found in the uptake and transport of beta-lactoglobulin or albumin in the presence or absence of ligands. Furthermore, uptake and passage across Caco-2 monolayer of retinol or palmitic acid added either bound to beta-lactoglobulin or to albumin have been compared. The percentage of retinol found in the lower chamber was about 35% of the total retinol after 24 h of incubation for both proteins. However, the amount of retinol associated to cells was higher when it was added bound to beta-lactoglobulin than to albumin, about 26% and 10%, respectively. This fact suggests that the metabolic processing of retinol by Caco-2 cells is the rate-limiting step for retinol transport. The percentage of palmitic acid that crossed the monolayer was about 7%, remaining approx. 90% in the cells for beta-lactoglobulin and albumin. These data support the hypothesis that palmitic acid internalized by Caco-2 cells is mainly destined to serve the structural and energy needs. These results show evidence of retinol and palmitic uptake by Caco-2 cells when beta-lactoglobulin or albumin are the donors, and indicate that the type of binding protein does not affect the transport of both ligands through Caco-2 monolayer.

Bovine beta-lactoglobulin: interaction studies with palmitic acid.

Bovine beta-lactoglobulin (BLG) in vivo has been found complexed with fatty acids, especially palmitic and oleic acid. To elucidate the still unknown structure-function relationship in this protein, the interactions between 13C enriched palmitic acid (PA) and BLG were investigated by means of one-, two-, and three-dimensional NMR spectroscopy in the pH range 8.4-2.1. The NMR spectra revealed that at neutral pH the ligand is bound within the central cavity of BLG, with the methyl end deeply buried within the protein. The analysis of 13C spectra of the holo protein revealed the presence of conformational variability of bound PA carboxyl end in the pH range 8.4-5.9, related to the Tanford transition. The release of PA starts at pH lower than 6.0, and it is nearly complete at acidic pH. This finding is relevant in relation to the widely reported hypothesis that this protein can act as a transporter through the acidic gastric tract. Ligand binding and release is shown to be completely reversible over the entire pH range examined, differently from other fatty acid binding proteins whose behavior is analyzed throughout the paper. The mode of interaction of BLG is compatible with the proposed function of facilitating the digestion of milk fat during the neonatal period of calves.

Specific immunoglobulins in serum of newborn lambs fed with a single dose of colostrum containing anti-peroxidase IgG.

The apparent efficiency of absorption and the decrease of specific colostral IgG after its passage into the blood stream were determined in newborn lambs fed with a single dose of colostrum containing anti-peroxidase IgG at 30 minutes, 12 hours and 24 hours after birth. When colostrum was given at 30 minutes after birth, a value of 16.9+/-4.0 per cent of anti-peroxidase IgG ingested appeared in lamb circulation. This percentage was reduced to 9.8+/-0.8 per cent when the feeding was done at 12 hours after birth and no specific IgG was detected in lambs fed at 24 hours after birth. The concentration of anti-peroxidase IgG in lambs' serum declined quickly within 96 hours of age to about 48 per cent of the initial value, and afterwards the level decreased slowly reaching a value of 10 per cent at 32 days of age. This behaviour probably reflects the protein distribution and use of absorbed antiperoxidase IgG.

[Trypsic inhibitors in serum and hyaline membrane disease (author's transl)]. / Los inhibidores trípsicos del suero y la enfermedad de la membrana hialina

Alpha1 antitrypsin (A1AT), alpha2 macroglobulin, alpha, quimotrypsin, interalpha1 antitrypsin and trypsin inhibitory capacity in serum of newborn with hyaline membrane disease, are compared with values obtained in other dis orders, and with normal newborn at different gestacional age. Significant decreased level of A1AT and trypsin inhibitory capacity were found in hyaline membrane patients, that were in order to symptoms severity and time in which samples were obtained. A1AT immunofluorescent study of hyaline membrane in died newborns was positive allowing to explain the low levels found in serum. Presence of fibrine IgG, C1a and C3 in hyaline membrane is according to it's composition by plasmatic components. Thus a new pathogenic mecanisme (derived of the plasma viscosity in the alveolar layer) could be present in hyaline membrane formation.

Comparison of the ability to bind lipids of beta-lactoglobulin and serum albumin of milk from ruminant and non-ruminant species.

The interaction of sheep, horse, pig, human and guinea-pig whey proteins with fatty acids has been studied. Using gel filtration and autoradiography, it was found that sheep beta-lactoglobulin and serum albumin from all species had the ability to bind fatty acids in vitro. Sheep beta-lactoglobulin, isolated from milk, had approximately 0.5 mol fatty acids bound per mol monomer protein, and albumin from sheep, horse and pig contained approximately 4.5, 2.9 and 4.7 mol fatty acids/mol protein respectively. However, beta-lactoglobulin from horse and pig milk had neither fatty acids physiologically bound nor the ability to bind them in vitro. Albumin was the only whey protein detected with bound fatty acids in these species as well as in human and guinea pig. This suggests that the ability of ruminant beta-lactoglobulin to bind fatty acids was not shared by the same protein of non-ruminants.

beta-lactoglobulin binds palmitate within its central cavity.

Bovine beta-lactoglobulin (beta-Lg) has been studied extensively in both the isolated and the naturally occurring states. It is a commercially important whey protein of obvious nutritional value but, so far, one that has no clearly identified biological function. In common with many of the other members of the lipocalin family to which it belongs, beta-Lg binds hydrophobic ligands, and it appears possible that there are at least two distinct binding sites per monomer for a variety of ligands. By comparison with other members of the family, there is a probable binding site in the central cavity of the molecule that is formed by the eight antiparallel beta-strands that are typical of the lipocalins. We have now cocrystallized beta-Lg with palmitic acid, and the refined structure (R = 0.204, Rfree = 0.240 for 6,888 reflections to 2.5-A resolution) reveals that the ligand binds in the central cavity in a manner similar to the binding of retinol to the related lipocalin, serum retinol-binding protein. The carboxyl group binds to both Lys-60 and Lys-69 at the entrance to the cavity. The hydrophobic tail stretches in an almost fully extended conformation into the center of the protein. This is the first direct observation of a ligand binding to beta-Lg.

[Neonatal transitional care unit (author's transl)]. / Valoración de una unidad neonatal de reanimación-transición.

Statistical analysis between a two year period with a five year interval (1972-1975) in a neonatal transitional care unit is evaluated. Number of resucitations doubled and neonatal mortality in the first seven days of life as well as in the first twenty four hours decreased significantly, being newborns under 1,000 gr. of weight and malformations the first two causes of death in both periods. Factors related to hypoxia which accounted for other 25% of deaths should be prevented. Importance of this type of units in huge maternities is emphasized considering their role in immediate neonatal care.

Lower body temperatures in infants delivered by caesarean section than in vaginally delivered infants.

Clinical experience suggests that infants delivered by caesarean section have difficulties maintaining normal body temperature during the first hours after birth. To test this hypothesis, body and skin temperatures were measured and compared in healthy full-term caesarean section and vaginally delivered newborn infants. The babies were studied during the first 90 min after birth. Axillary and skin temperatures were significantly higher in the vaginally delivered group than in infants delivered by caesarean section. Infants born by non-elective caesarean section were slightly warmer during the first 90 min after birth compared to infants born by elective caesarean section. There were no significant differences in temperatures between infants cared for in a cot as compared to those cared for in an incubator. An incubator creates a physical barrier between babies and parents and incubator care might cause parental anxiety. Thus the routine of putting healthy, full-term caesarean section infants in incubators can be abandoned from a thermoregulatory point of view.

Temperature, metabolic adaptation and crying in healthy full-term newborns cared for skin-to-skin or in a cot.

The aim of the present study was to compare temperatures, metabolic adaptation and crying behavior in 50 healthy, full-term, newborn infants who were randomized to be kept either skin-to-skin with the mother or next to the mother in a cot "separated". The babies were studied during the first 90 min after birth. Axillary and skin temperatures were significantly higher in the skin-to-skin group; at 90 min after birth blood glucose was also significantly higher and the return towards zero of the negative base-excess was more rapid as compared to the "separated" group. Babies kept in cots cried significantly more than those kept skin-to-skin with the mother. Keeping the baby skin-to-skin with the mother preserves energy and accelerates metabolic adaptation and may increase the well-being of the newborn.