PubMed Health⌕ Search

Biomedical subjects

A Ribera

Publications and source records attributed to A Ribera.

At least 91 records · Page 5Linked to original sources
PubMed1983

Autoimmune thrombocytopenia: serological behavior of platelet antibodies.

The study of the specificity of platelet autoantibodies has made it possible to expand our knowledge about the immune characterization of idiopathic thrombocytopenic purpura. We report on a study of eluates obtained from 10 patients' platelets with autoimmune thrombocytopenia. They were tested with platelets obtained from healthy donors (Zw a + and Zw a-) and with type I Glanzmann platelets. Our results, as those reported by van Leeuwen et al. in 1982, suggest that the autoantibodies recognize one or more antigenic markers probably carried by glycoproteins IIb and IIIa.

Antigen-Antibody Reactions↗
PubMed1982

Thermal and 13C-NMR study of the dynamic structure of 1-palmitoyl-2-oleyl-sn-glycero-3-phosphocholine and 1-oleyl-2-palmitoyl-sn-glycero-3-phosphocholine in aqueous dispersions.

Mixed-acid monounsaturated phosphatidylcholines containing palmitate and oleate chains have been synthesized by phospholipase A2 digestion of the appropriate single-acid phosphatidylcholine, followed by reacylation of the lysophosphatidylcholine with the desired fatty acid anhydride. The positional isomers 1-palmitoyl-2-oleyl-sn-glycero-3-phosphocholine and 1-oleyl-2-palmitoyl-sn-phosphocholine have been thus obtained. The thermotropic behavior of these lipids dispersed in excess water has been studied by differential scanning calorimetry. Positional isomers of mixed-acid monounsaturated phosphatidylcholines are found to have different gel to liquid-crystalline transition temperatures and enthalpies. It was found that mixtures of 1-palmitoyl-2-oleyl-sn-glycero-3-phosphocholine with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine or 1,2-distearoyl-sn-glycero-3-phosphocholine exhibited inmiscibility in the phosphatidylcholine gel state. The dynamic structure of 1-palmitoyl-2-oleyl-sn-glycero-3-phosphocholine and 1-oleyl-2-palmitoyl-sn-glycero-3-phosphocholine bilayers has been investigated by measuring the 13C nuclear spin-lattice relaxation times of sonicated aqueous dispersions. No difference was found between the two systems, suggesting that above the thermal transition the presence of the unsaturated acyl group in the 1 or 2 position does not affect significantly the dynamic structure of the bilayer.

Calorimetry, Differential Scanning↗
PubMed1981

Incorporation of fatty acids into phosphatidylcholine species by liver homogenates from chick embryos.

Labeled palmitic, stearic, oleic, linoleic and araquidonic acids were incorporated into phosphatidylcholines by incubation with liver homogenates from 13, 17 and 21 day-old chick embryos. Palmitic acid was incorporated into dienoic and tetraenoic phosphatidylcholines whereas linoleic acid was incorporated into dienoic phosphatidylcholines. Labeled palmitic and linoleic acids were specifically found into positions 1 and 2 of the phosphatidylcholine molecule, respectively. Under in vitro conditions, the incorporation of either palmitic or linoleic acids into phosphatidylcholines was 2-3 fold greater in liver homogenates from 17 day-old chick embryos than in those from 13 or 21 day-old ones.

Age Factors↗
PubMed1981

Deacylation and reacylation of phosphatidylcholines by liver homogenates from chick embryos.

Liver homogenates from 13, 17 and 21 day-old chick embryos were incubated with phosphatidylcholine and lysophosphatidylcholine labeled with fatty acids to study deacylation and reacylation reactions of phosphatidylcholines during development. By using phosphatidylcholines labeled with palmitic or linoleic acids in position 1 or 2, respectively, phospholipase A2 activity was detected. By using lysophosphatidylcholine labeled with palmitic acid in position 1, preferential acylation with araquidonic acid was demonstrated. In agreement with this data, the incubation of dienoic phosphatidylcholines labeled with palmitic acid in position 1, with the liver homogenates, gave rise to labeled tetraenoic phosphatidylcholines. The extent of both deacylation and reacylation of the phosphatidylcholine molecule in position 2 by liver homogenates from chick embryos, decreased during development.

Acylation↗
PubMed1980

[Chronic ulcerative colitis and autoimmune hemolytic anemia (author's transl)].

A 27-year-old male developed an autoimmune hemolytic anemia during the initial episode of chronic ulcerative colitis. Laboratory studies revealed a positive direct Coomb's test (IgG + C), and the presence of specific anti-Hr antibody. Salicylazosulfapyridine was tested by means of immunohematologic techniques, but results discarded this drug as the responsible agent for autoimmune hemolytic anemia. Association of ulcerative colitis and autoimmune hemolytic anemia is an uncommon finding; around 36 cases have been published in the literature. Hemolytic anemia may develop as a consequence of treatment with salicylazosulfapyridine, the antimicrobial of choice in the management of inflammatory diseases of the bowel.

Adult↗
PubMed1980

Molecular species composition of phosphatidylcholines during the development of the avian embryo brain.

A comparative approach has been used to investigate the molecular species composition of phosphatidylcholine (PC) and its age variation throughout several developmental stages of chick and duck embryo brains. The brain PC consist of 15 major molecular species which do not undergo appreciable variation in their relative abundance either during embryonic development or between equivalent stages of maturation in the 2 avian species. In fact, a highly invariable molecular architecture of PC is shown in the developing organ. Molecular species containing saturated or monounsaturated fatty acids were dominant in all stages of development of the avian embryo brain. Among these molecular species, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine accounted for 75-80% of the total PC.

Animals↗