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S Ayala

Publications and source records attributed to S Ayala.

At least 19 recordsLinked to original sources
PubMed2001

Effect of dexamethasone on the fatty acid composition of total liver microsomal lipids and phosphatidylcholine molecular species.

Dexamethasone depresses delta6 and delta5 and increases delta9 desaturase and synthase activities. Therefore, we investigated the effect on the fatty acid composition of microsomal liver lipids and phosphatidylcholine (PtdCho) molecular species. After 15 d of treatment we found a notable decrease in arachidonic acid, a small decrease in stearic acid, and increases of linoleic, oleic, palmitoleic, and palmitic acids in liver microsomal total lipids and PtdCho. The study of the distribution of the PtdCho molecular species indicated that 18:0/20:4n-6, 16:0/20:4n-6, and 16:0/18:2n-6 predominated in the control animals. Dexamethasone, as expected because of its depressing effect on arachidonic acid synthesis and activation of oleic and palmitic acid synthesis, evoked a very significant decrease in 18:0/20:4n-6 PtdCho (P<0.001) and an important increase in 16:0/18:2n-6. The invariability of 16:0/20:4n-6 PtdCho could be related to the antagonistic effect of arachidonic and palmitic acid synthesis. PtdCho species containing oleic acid were not significant. The bulk fluidity and dynamic properties of the microsomal lipid bilayer measured by fluorometry using the probes 1,6-diphenyl-1,3,5-hexatriene and 4-trimethylammonium-phenyl-6-phenyl-1,3,5-hexatriene showed no significant modification, probably owing to a compensatory effect of the different molecular species, but changes of particular domains not detected by this technique are possible. However, the extremely sensitive Laurdan detected increased lipid packing in the less-fluid domains of the polar-nonpolar interphase of the bilayer, possibly evoked by the change of molecular species and cholesterol/phospholipid ratio. The most important effect found is the decrease of arachidonic acid pools in liver phospholipids as one of the corresponding causes of dexamethasone-dependent pharmacological effects.

Animals↗
PubMed2001

In vivo assessment of microvascular nitric oxide production and its relation with blood flow.

To assess the hypothesis that microvascular nitric oxide (NO) is critical to maintain blood flow and solute exchange, we quantified NO production in the hamster cheek pouch in vivo, correlating it with vascular dynamics. Hamsters (100-120 g) were anesthetized and prepared for measurement of microvessel diameters by intravital microscopy, of plasma flow by isotopic sodium clearance, and of NO production by chemiluminescence. Analysis of endothelial NO synthase (eNOS) location by immunocytochemistry and subcellular fractionation revealed that eNOS was present in arterioles and venules and was 67 +/- 7% membrane bound. Basal NO release was 60.1 +/- 5.1 pM/min (n = 35), and plasma flow was 2.95 +/- 0.27 microl/min (n = 29). Local NO synthase inhibition with 30 microM N(omega)-nitro-L-arginine reduced NO production to 8.6 +/- 2.6 pmol/min (-83 +/- 5%, n = 9) and plasma flow to 1.95 +/- 0.15 microl/min (-28 +/- 12%, n = 17) within 30-45 min, in parallel with constriction of arterioles (9-14%) and venules (19-25%). The effects of N(omega)-nitro-L-arginine (10-30 microM) were proportional to basal microvascular conductance (r = 0.7, P < 0.05) and fully prevented by 1 mM L-arginine. We conclude that in this tissue, NO production contributes to 35-50% of resting microvascular conductance and plasma-tissue exchange.

Acetylcholine↗
PubMed1998

alpha-Thalassaemia due to a single codon deletion in the alpha1-globin gene. Computational structural analysis of the new alpha-chain variant. Mutations in brief no. 132. Online.

A new unstable alpha-globin chain associated with alpha-thalassemia phenotype has been found in a Spanish patient. Molecular analysis of the alpha-globin gene complex using PCR and non-radioactive single-strand conformation analysis, allowed to identify a new mutation in the second exon of the alpha-globin gene. Direct sequencing of the abnormal fragment revealed a 3 bp deletion, which led to the loss of a single codon corresponding to a Lys (K) residue at position 60 or 61 DK60 or DK61. Theoretical structural analysis, performed by computational methods, indicated that the loss of an amino acid residue at this position disturbed the contact region between the B and E-helices, affecting the overall stability of the molecule. Therefore, the DK60 and DK61 results in a structurally abnormal alpha-globin chain, not previously described, named Hb Clinic, which leads to the alpha-thalassemia phenotype in the heterozygote patient. No abnormal hemoglobin was detected by standard electrophoretic procedures, suggesting that this alpha-globin chain variant is so unstable that it may be catabolized immediately after its synthesis. This mutation was confirmed by PCR using an allele specific primer.

Codon↗
PubMed1997

First description of a frameshift mutation in the alpha1-globin gene associated with alpha-thalassaemia.

A frameshift mutation in the alpha1-globin gene, responsible for a clinically mild alpha-thalassaemia phenotype, has been characterized in a Spanish woman. After excluding the most common forms of alpha-thalassaemia found in the Mediterranean area, both alpha-globin genes (alpha1 and alpha2) were amplified and analysed selectively by non-radioactive single-strand conformation polymorphism (SSCP). An abnormal SSCP mobility was present in the second exon of the alpha1-globin gene and direct sequence analysis revealed a 13 bp deletion (between codons 51 and 55) affecting a single allele. The consequence of this mutation is a reading frameshift leading to a novel amino acid coding sequence from codons 51-61 and a premature stop signal at new position 62, which results in a net reduction of the affected alpha-globin chain output. The presence of this new mutation was confirmed by restriction enzyme analysis of the specific PCR product.

Aged↗
PubMed1996

Nondeletional alpha-thalassemia: first description of alpha Hph alpha and alpha Nco alpha mutations in a Spanish population.

Several different deletions underlie the molecular basis of alpha-thalassemia. The most common alpha-thalassemia determinant in Spain is the rightward deletion (-alpha 3.7). To our knowledge, however, no cases of alpha-thalassemia due to nondeletional mutations have so far been described in this particular Mediterranean area. Here, we report the existence of nondeletional forms of alpha-thalassemia in ten Spanish families. The alpha 2-globin gene was characterized in ten unrelated patients and their relatives only when the presence of deletional alpha-thalassemia was ruled out. The alpha 2-globin gene analysis was performed using the polymerase chain reaction (PCR) followed by restriction enzyme analysis or by allelespecific priming. This allowed the identification of a 5-base pair (bp) deletion at the donor site of IVS I (alpha Hph alpha) in 9 cases and the alpha 2 initiation codon mutation (alpha Nco alpha) in one case. Although these alpha 2-globin gene mutations are found in other mediterranean areas, our results demonstrate their presence in the Spanish population and suggest that the alpha Hph alpha/alpha alpha genotype is probably the most common nondeletional form of alpha-thalassemia in Spain.

Adolescent↗
PubMed1996

Haemoglobin Lleida: a new alpha 2-globin variant (12 bp deletion) with mild thalassaemic phenotype.

Molecular studies of alpha-thalassaemias have revealed defects at different steps in the process of alpha-gene expression. It is not surprising, therefore, that in some cases a single mutation or small deletion can result in a structurally abnormal haemoglobin that produces the alpha-thalassaemia phenotype. In this report we describe a new unstable alpha-globin variant, Hb Lleida, in a Spanish patient with alpha-thalassaemia trait. The mutation was detected by single-strand conformation polymorphism in the third exon of the alpha 2-globin gene. Direct sequence analysis of the alpha-globin gene showed a 12 bp deletion as the only defect of the alpha 2- and alpha 1-globin genes. The propositus was revealed to be a heterozygous carrier, and two alleles were separated by electrophoresis. This deletion causes the loss of four aminoacid residues (from codon 113 to 116) and would be expected to produce an unstable haemoglobin, as a shorter alpha-globin chain variant is created with 137 amino acids instead of 141 amino acids present in a normal alpha-globin chain. However, no abnormal haemoglobin was found by either isoelectric focusing or haemoglobin electrophoresis. Since the deletion affects an aminoacid residue (114 Pro) involved in alpha 1-beta 1-globin chain contacts, the interaction required for efficient Hb assembly is also compromised. The resulting unstable alpha-globin chain is rapidly catabolized and unsuitable for haemoglobin tetramer formation, causing an alpha-thalassaemia trait phenotype in the heterozygous patient.

Adult↗
PubMed1995

[Abnormal changes in erythrocyte membrane proteins in hereditary spherocytosis and their relation to clinical and biological aspects of the disease].

BACKGROUND: In the present paper we report a study of 20 patients with hereditary spherocytosis (HS) performed with the aim of provide further information on the electrophoretic abnormalities of red blood cell (RBC) membrane proteins and their putative relationship with the clinical, biological and genetic aspects of the disease. METHODS: General hematological parameters, reticulocyte count, osmotic fragility test and erythrocyte morphology analysis, were performed by routine procedures. Membrane proteins of erythrocyte were analyzed by SDS-polyacrylamide gradient gel electrophoresis (SDS-PAGE) using the Laemmli and Fairbanks methods. RESULTS: In 8 out of 20 cases (40%) a defect of band 3, alone or associated with a slight deficiency of protein 4.2, was observed. In addition to the presence of spherocytes, in all these 8 patients, a peculiar morphologic RBC alteration called pincered RBCs was also observed. Moreover, 2 cases showed a deficiency of protein 4.2, 2 cases a deficiency of ankyrin and 2 cases a deficiency of spectrin. In 6 cases (30%) the electrophoretical pattern of the erythrocyte membrane proteins was normal. A significant (r = -0.6; p < 0.01) correlation between the protein 4.2 (pallidin) and the mean corpuscular haemoglobin concentration (MCHC) was found. Also, the multiple regression analysis showed a correlation (r2 = 0.6; p < 0.0001) between the amount of protein 2.1 (ankyrin) and two hematological parameters: the mean corpuscular volume (MCV) and the red cell distribution width (RDW). CONCLUSIONS: The defect of band 3 is the most frequent membrane protein abnormality associated with HS.

Adolescent↗
PubMed1995

Hereditary xerocytosis: a report of six unrelated Spanish families with leaky red cell syndrome and increased heat stability of the erythrocyte membrane.

Hereditary xerocytosis (HX) is a rare haemolytic disease due to dehydrated red blood cells (RBCs). A unique feature of this syndrome is that affected members often show normal or near normal haemoglobin levels despite clinical and laboratory evidence of mild to moderate haemolysis. The diagnostic clue is the association of markedly increased RBC Na+ + K+ fluxes with low total cation (Na+ + K+) content. 11 patients of six unrelated families of Spanish origin with HX have been studied from clinical, genetical and biological points of view. In addition, we have investigated the sensitivity of RBC membrane to heat at three different incubation times (15, 30 and 60 min) and two different temperature values (46 degrees C and 49 degrees C). Under these conditions control RBCs (50 normal subjects) exhibited at 49 degrees C and 30 min a maximum of 30% fragmented RBCs. This value increased to 80% after 60 min of incubation. In contrast, patients with HX showed significantly lower percentages of fragmented RBCs at both 30 and 60 min of incubation (maximum 10% and 30%, respectively). In an attempt to determine if increased heat stability was unique to HX RBCs, several other congenital membranopathies with haemolytic anaemia were also studied. The degree of fragmentation, except in one case of HPP (which was strongly increased), did not differ from the control group. Electrophoretic studies of membrane proteins performed in RBCs of all the patients with HX did not explain any qualitative nor quantitative abnormality. In addition to its physiopathological interest, study of RBC heat stability, together with other haematological parameters (increased MCHC and decreased RBC osmotic fragility), may be useful for HX diagnosis, especially in laboratories which are not equipped to evaluate RBC membrane permeability.

Anemia, Hemolytic↗
PubMed1993

Fatty acid composition and dynamics of phospholipids from fresh water fish Prochilodus lineatus brain and spinal cord.

The phospholipid and fatty acid composition of the brain and spinal cord lipids of fresh water fish Prochilodus lineatus ("sábalo") were studied. The fluorescence anisotropy of phospholipids labelled with 1.6-diphenyl 1.3.5-hexatriene, was also investigated. Phosphatidyl-choline was the most abundant phospholipid followed by phosphatidyl-ethanolamine, phosphatidyl-serine, phosphatidyl-inositol and sphingomyelin. The fatty acid composition of all phospholipids except sphingomyelin showed the presence of n-9, n-6 and n-3 series of unsaturated acids. The presence of n-6 polyunsaturated fatty acid was represented by arachidonic acid that was found preferentially in phosphatidyl-inositol. N-3 fatty acids were represented by 20:5n-3, 22:5n-3 and 22:6n-3. Docosa 4,7,10,13,16,19 hexaenoic acid was the most abundant of n-3 fatty acids and was preferentially found in phosphatidyl ethanolamine and phosphatidyl-serine. The percentage of 22:6n-3 acid decreased with age. The simultaneous presence of n-6 fatty acids (arachidonic acid) and n-3 fatty acids in fresh water fishes contrast with the absence of n-6 fatty acids in nervous tissue of marine fishes. Phosphatidyl choline was the most fluid of all phospholipids from brain and spinal cord.

Animals↗
PubMed1991

Fatty acid composition and dynamics of phospholipids from hake (Merluccius hubbsi) spinal cord and brain and sea bass (Acanthustius brasilianus) brain.

This work studies the phospholipid and fatty acid composition in hake brain and spinal cord and in sea bass brain. Fluorescence anisotropy of phospholipid vesicles labeled with 1,6-diphenyl hexatriene was measured to investigate the associated dynamic properties. In all tissues studied, phosphatidylcholine and phosphatidylethanolamine were the major constituents with minor contributions of phosphatidylserine, phosphatidylinositol and sphingomyelin. Fatty acids belong to the n-9 and n-3 series exclusively. Phosphatidylinositol from hake spinal cord and phosphatidylethanolamine and phosphatidylserine from hake brain contain the greatest percentages of eicosa-5,8,11,14,17-pentaenoic (20:5) and docosa-4,7,10,13,16,19-hexaenoic (22:6), respectively. For all fractions studied the total content of saturated fatty acids increases in the order of hake spinal cord, hake brain, sea bass brain together with a decrease in the sum of monounsaturated fatty acids. The comparison between fluorescence anisotropy values and fatty acid composition clearly demonstrates that saturated acids and 20:5 and 22:6 exert a rigidizing effect.

Animals↗
PubMed1990

Malignant cell autolysis caused by intracytoplasmic liberation of lysosomal enzymes.

An ultrastructural study of the action of peptidoglycans on malignant lymphocytes was made. Glycans acted upon lysosomes labilizing and rupturing the lysosomal membrane. Lysosomal enzymes were discharged directly into the cell cytoplasm. Nucleus, mitochondria and all organelles were digested in situ, resulting in a completely structureless cell. Finally, cancerous cells disintegrated by the detachment of cytoplasmic fragments.

Animals↗
PubMed1988

Molecular and cellular events during the germination of conidia of Sporothrix schenckii.

Hyaline, non pigmented microconidia of Sporothrix schenckii were harvested and allowed to form germ tubes in a basal medium with glucose at pH 4.0 and 25 degrees C. These conditions supported only the development of the mycelial form of Sporothrix schenckii in a reproducible, synchronized manner which allowed further analysis of the early cellular events occurring during the germination of the conidia. The relationship between macro-molecular synthesis (DNA, RNA and protein synthesis) and nuclear division, hyphal growth and septum formation were established. Following inoculation, protein synthesis was observed after 10 minutes followed by RNA synthesis, after 1 h and DNA synthesis after 2 h. The first nuclear division was observed during the 9 to 12 h interval after inoculation. Germ tube formation slightly preceeded nuclear division and was first evidenced 9 h after the induction of germination but was not completed until 12 h after inoculation. Septation was first observed in the germ tubes 0.25 micron from the mother cell-germ tube function 9 h after induction of germination.

Cell Division↗
PubMed1987

[Effect of zinc deficiency on the in vivo biosynthesis of fatty acids of the linoleic series in the rat].

The effect of Zn deficiency on the in vivo synthesis of fatty acids of linoleic acid (n6) series was studied in rat liver. 1-14C Linoleic acid (18:2 n 6), 1-14C acetate plus delta-linolenic acid (18:3 n 6), and 1-14C eicosatrienoic acid (20:3 n 6) were administered to control rats and to animals which had been maintained for 32 days on a Zn-deficient diet. The distribution of label among microsomal fatty acids was measured one hour after the injections. 14C 18:2 n 6 was converted to 14C labeled (n 6) linolenate, eicosatrienoate, arachidonate, and docosapentaenoate. Label from 14C acetate was found in saturated fatty acids and in the above polyenes. The label from 14C 20:3 n 6 was transferred to (n 6) eicosatetraenoate and docosapentaenoate. These results are consistent with the occurrence of active delta 6, delta 5 and delta 4 desaturases, as well as fatty acid elongases in vivo. Zn deficiency modified the fatty acid composition of rat liver microsomes and decreased the rate of conversion of 14C 18:2 to higher homologs. The 20:4 n 6/18:2 n 6 ratio was decreased, which correlated with a decreased production of 14C 20:4 n 6 from 14C 18:2 n 6. The ratio (14C-labeled) phosphatidylcholine/triacylglycerols was significantly decreased in Zn-deprived rats. Zn deficiency thus decreases the activity of fatty acid desaturases and elongases and modifies the activity of the enzymes involved in the incorporation of fatty acids into lipids.

Animals↗
PubMed1983

Essential fatty acid status in zinc deficiency. Effect on lipid and fatty acid composition, desaturation activity and structure of microsomal membranes of rat liver and testes.

The effect of zinc deficiency on the lipid composition, fluorescence anisotropy of the membrane labeled with diphenyl hexatriene and delta 9, delta 6, and delta 5 fatty acid desaturation activity of liver and testes microsomal membranes was studied. Sixty days of zinc deficiency in weanling rats evoked a loss of hair and scaled and ridged tail. The activities of delta 6 and delta 5 desaturases, that are relevant enzymes involved in linoleic acid conversion into arachidonic acid, were decreased in both liver and testes. However, the delta 9 desaturase of liver was increased by the zinc deficiency. The arachidonic acid concentration of liver and testes microsomes was decreased. The microsomal phospholipid/cholesterol ratio was markedly decreased, and this change was correlative to an increase of the fluorescence anisotropy of membranes labeled with diphenyl hexatriene, that indicated an increase of the order parameter for diphenyl hexatriene and considering the criterium of Van Blitterswijk et al., an increase of the molecular packing of the bilayer. Zinc deficiency evoked an essential fatty acid deficiency status with low eicosa-5,8,11-trienoic acid, and decrease of delta 6 and, specially, delta 5 desaturase activity, that aggravates the symptoms and avoids compensatory biosynthesis of the polyunsaturated acids of oleic family.

Animals↗
PubMed1980

Effect of polyunsaturated fatty acids of the alpha-linolenic series in the lipid composition of rat testicles during development.

The effect of 22:6 omega 3 acid provided by dietary fish oil on the lipids composition of rat testes and liver during the development of the germinal tissue, was investigated. Results were compared to those obtained in animals fed on sunflower seed oil (linoleate) and methyl palmitate. At 7 and 9 weeks of age, both fish oil and methyl palmitate evoked a decrease of phosphatidyl-choline and ethanolamine and an increase of triacylglycerols. However, only in the group of rats administered with omega 6 or omega 3 acids and not in the palmitate group, the maturation of germinal epithelium was normal. It is suggested, as in a previous work, that 22:6 omega 3 may functionally replace 22:5 omega 6 in rat germinal tissue.

Age Factors↗
PubMed1977

Effect of polyunsaturated fatty acids of the alpha-linolenic series on the development of rat testicles.

The effect of 22:6 omega 3 acid provided by dietary fish oil on the development of germinal tissue of rat testes, fatty acid composition of lipids, and linoleic or alpha-linolenic acid delta 6 desaturation capacity was investigated. Results were compared to those obtained in animals fed methyl palmitate and sunflower seed oil (linoleate). At 7 and 9 weeks of age, development of germinal tissue of animals fed fish oil was normal. The fatty acid composition showed a decrease in 22:5 omega 6 acid content and an increase in 22:6 omega 3 acid in triacylglycerol, phosphatidylcholine, and phosphatidylethanolamine. The fatty acid delta 6 desaturation capacity of testicules microsomes was increased. It is suggested that 22:6 omega 3 acid may functionally replace 22:5 omega 6 acid in germinal tissue.

Aging↗