SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The authors report on their study of the ratio of palmitic acid to stearic acid (P/S) in the pharyngeal secretions of the newborn before the sixth hour of life. Four groups of infants were studied: 78 infants used as controls who hac no respiratory distress, 36 with hyaline membrane disease, 16 with transitory respiratory distress and 5 with perinatal asphyxia. The aetiological diagnosis of the respiratory distress was based on clinical as well as radiological and biological criteria. The P/S ratio is always less than 3 with hyaline membrane disease and above 3 in asphyxias. In the control group and the group with transitory respiratory distress the ratio ranged between 1.3 and 14 which was evidence of false negative results, probably attributable to treatment with cortisone given to the mother in premature labour in a certain number of cases. Study of the P/S ratio in amniotic fluid and in the pharyngeal secretions of 27 children born by Caesarean operation embodies a contradiction in the results the newborns in whom the ratio in the amniotic fluid was greater than 3 never had respiratory distress although the ratio studied at the same time in the pharyngeal secretions was low and sometimes less than 3.
Near-field scanning optical microscopy and atomic force microscopy are used to probe the sub-micrometre phase structure in palmitic acid monolayers containing the 25 peptide amino terminus of lung surfactant protein B (SP-B(1-25)). Monolayers deposited onto mica substrates at a surface pressure of 15 mN m-1 exhibit a two-phase coexistence across a broad range of SP-B(1-25) concentrations. Monolayers containing 5 wt.% SP-B(1-25) or less exhibit an expanse of liquid condensed phase in which elliptical liquid expanded (LE) domains with areas of approximately 25 microm2 coexist. By contrast, monolayers containing 20 wt.% SP-B(1-25) exhibit an expanse of liquid expanded phase in which circular liquid condensed domains coexist. The phase distribution dependence on SP-B(1-25) concentration suggests that the peptide induces disorder in the monolayer.
The present study assesses the effect of high vs. low palmitic acid intakes on plasma lipoprotein cholesterol levels and on rates for endogenous synthesis of cholesterol in healthy and hyperlipidemic subjects. Four diets were formulated to provide combinations of 16:0 at two levels of 18:2n-6. Subjects received each diet treatment for 21 d, followed by washout periods of 21 d. On day 21 of each diet treatment, a fasting blood sample was drawn for lipoprotein determination and to provide a measure of the background level of deuterium. A priming dose of deuterium was consumed and a second blood sample obtained 24 h after the first sample. Isotope ratio mass spectrometry was used to determine the incorporation of deuterium into the newly synthesized cholesterol molecule, and fractional synthetic rates were calculated. Serum total cholesterol and low density lipoprotein-cholesterol was not significantly affected by the high level of 16:0 when diets also contained a high level of 18:2n-6. There was no effect of dietary 16:0 on high density liproprotein-cholesterol at either the high or low levels of intake. The results indicate that 16:0 has no effect on serum lipoprotein profiles in the presence of recommended intakes for 18:2n-6.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
We have performed molecular dynamics simulations of multiple copies of the lung-surfactant peptide SP-B1-25 in a palmitic acid (PA) monolayer. SP-B1-25 is a shorter version of lung-surfactant protein B, an important component of lung surfactant. Up to 30 ns simulations of 20 wt % SP-B1-25 in the PA monolayers were performed with different surface areas of PA, extents of PA ionization, and various initial configurations of the peptides. Starting with initial peptide orientation perpendicular to the monolayer, the predicted final tilt angles average 54 degrees approximately 62 degrees with respect to the monolayer normal, similar to those measured experimentally by Lee et al. (Biophysical Journal. 2001. Synchrotron x-ray study of lung surfactant-specific protein SP-B in lipid monolayers. 81:572-585). In their final conformations, hydrogen-bond analysis and amino acid mutation studies show that the peptides are anchored by hydrogen bond interactions between the cationic residues Arg-12 and Arg-17 and the hydrogen bond acceptors of the ionized PA headgroup, and the tilt angle is affected by the interactions of Tyr-7 and Gln-19 with the PA headgroup. Our work indicates that the factors controlling orientation of small peptides in lipid layers can now be uncovered through molecular dynamics simulations.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The incorporation of free fatty acid into the placental and fetal liver lipids of rabbits was studied after fetal injections of albumin-bound 1-14C-palmitic acid. The fetuses were killed either 5--10 or 10--20 min after the injection. The placentas and livers were extracted for lipids and the specific activities of triglycerides (TG), phospholipids (PL), free fatty acids (FFA), monoglycerides (MG) and diglycerides (DG) measured. The lipids of the liver and placenta took up 17.0 and 3.6% of the dose, respectively, and of that liver TG accounted for 74% and the placental TG 34% of the label in each tissue. Most of the remaining counts were in the PL fraction with the rest more or less evely distributed between the FFA, DG and MG fractions. No activity was recorded in the cholesterol esters. The placental TG, PL, DG and MG specific activities reached the same level as that of the placental FFA, while in the liver these esters had higher specific activities (than the liver FFA). The liver TG, DG and PL had higher specific activities when compared with those of the placenta. The specific activity of the placental FFA was lower at 10--20 min than at 5--10 min; the opposite was seen for the placental TG. No time-related changes were seen in the liver lipids. It is concluded that (i) both placenta and fetal liver incorporate FFA into glycerides and PL; (ii) the liver incorporates FFA more rapidly and to a greater extent than the placenta; (iii) most of the FFA is incorporated into TG and to a lesser extent (PL; (iv) in both organs hydrolysis of PL or TG occurs. These results are discussed with reference to placental transport of FFA and fetal fat metabolism.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Membrane remodeling was imaged in vivo in brains of rats with a 2-week-old right-sided ablation of the nucleus basalis magnocellularis (NBM). To do this, [9,10-3H]palmitic acid ([3H]PAM) was injected intravenously and regional brain incorporation k* of tracer was determined with quantitative autoradiography after 20 min circulation. In NBM-lesioned animals, k* was elevated significantly (by up to 17%) in 11 ipsilateral frontal or parietal cortical regions, more so in layer 1 than in layers IV and V. Unoperated animals showed no right-left difference in k*, whereas sham-operated animals showed some unilateral effects of damage due to the needle track. Circulating [3H]PAM is incorporated into sn-1 positions of brain phospholipids, mainly phosphatidylcholine, and its rate of turnover is thought to reflect turnover of neuronal and glial membranes. These results, when related to published evidence of altered cortical phospholipid metabolism in NBM-lesioned rats, suggest that images of increased [3H]PAM incorporation into ipsilateral cortex reflect increased membrane remodeling involving phospholipids.
Explore the source record for details and available documents.