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Biomedical subjects

A Barceló

Publications and source records attributed to A Barceló.

30 records · Page 2Linked to original sources
PubMed1998

Mild or absent clinical signs in twin sisters with short-chain acyl-CoA dehydrogenase deficiency.

UNLABELLED: Two HLA-identical twin sisters are reported, of whom one has remained essentially asymptomatic, and an episode of hypotonia and decreased level of conciousness being the only relevant clinical finding in the other. Organic acid-analysis revealed that ethylmalonate was constantly, although sometimes only slightly, increased. No abnormal acylglycines or acylcarnitines could be detected. Enzyme assay in cultured skin fibroblasts confirmed short-chain acyl-CoA dehydrogenase deficiency. CONCLUSION: The lack of appropriate biochemical markers for this deficiency makes the diagnosis difficult and consequently, the low number of patients described may be the result of underdiagnosis.

Acyl-CoA Dehydrogenase↗
PubMed1998

Metallic fragment deposits during phacoemulsification.

PURPOSE: To describe the nature and origin of foreign metallic intraocular bodies appearing after phacoemulsification. SETTING: Department of Ophthalmology, University Hospital of San Juan, Alicante, Spain. METHODS: Two metallic particles, 1 extracted during surgery and the other from a patient in whom surgery had been performed, were studied by scanning electronic microscopy and X-ray dispersive energy spectroscopy. Also evaluated were all metallic elements used in phacoemulsification including phaco tips, Sinskey hooks, and handpieces. A morphologic analysis at various magnifications was performed and the composition of the elements studied. RESULTS: Scanning electronic microscopy showed irregularities of the phaco tip and Sinskey hook after their use. Spectrographic analysis found that the phaco tip was mainly aluminum and titanium; the Sinskey hook, iron, chromium, cobalt, and nickel; the handpiece, iron, chromium, and nickel; and the 2 metallic particles, iron, chromium, and nickel, the same as the handpiece. CONCLUSION: The metallic particles extracted corresponded to those of the phaco handpiece. Vibration during prolonged use of the phacoemulsifier probably caused these particles to chip off the handpiece.

Alloys↗
PubMed1997

A nonsense mutation in the 3-hydroxy-3-methylglutaryl-CoA lyase gene produces exon skipping in two patients of different origin with 3-hydroxy-3-methylglutaryl-CoA lyase deficiency.

A novel nonsense mutation associated with the skipping of constitutive exon 2 of the 3-hydroxy-3-methylglutaryl-CoA lyase gene was found in two patients, from Portugal and Morocco, with 3-hydroxy-3-methylglutaric acidemia. By reverse transcriptase PCR and single-strand conformational polymorphism a G-T transversion was located, at nucleotide 109, of the 3-hydroxy-3-methylglutaryl-CoA lyase cDNA, within exon 2. Two mRNAs were produced as a result of this nonsense mutation: one of the expected size that contains the premature stop codon UAA, and the other with a deletion of 84 bp corresponding to the whole of exon 2. This deletion produced the loss of the last seven amino acids of the leader peptide and the first 21 amino acids of the mature protein. The nonsense mutation was found in a purine-rich GGAAG sequence, which is equal to, or similar to, others reported to be exonic splicing enhancers (ESE). We suggest that the nonsense mutation may affect a possible ESE on exon 2, which would hinder the splice site selection and facilitate an aberrant splice with the skipping of this exon. Determination by quantitative PCR shows that the ratio of mRNA with the nonsense mutation to the mRNA with the deletion is approx. 3:1.

Amino Acid Sequence↗
PubMed1997

Platelet integrin alpha IIb beta 3 (GPIIb-IIIa) is not implicated in the binding of LDL to intact resting platelets.

It has been suggested that the fibrinogen receptor (glycoprotein [GP] IIb-IIIa or platelet integrin alpha IIb beta 3) could be the binding site for low-density lipoprotein (LDL); however, recent data do not support this. Furthermore, GPIIb and not the GPIIb-IIIa complex is the main binding protein for lipoprotein(a) [Lp(a)]. In the present study, we have investigated the interaction between Lp(a) particles and platelet LDL binding sites and whether platelet integrin alpha IIb beta 3 is implicated. Displacement experiments showed that 125I-LDL binding to intact resting platelets was inhibited with the same apparent affinity by both unlabeled LDL and apolipoprotein(a)-free lipoprotein particles [Lp(a)-, an LDL-like particle prepared from Lp(a)]. Hill coefficients for displacement curves suggested that a single set of binding sites was involved. In contrast, both native and oxidized Lp(a) particles were unable to inhibit platelet LDL binding. Furthermore, platelets bound 125I-Lp(a)- particles to a class of saturable binding sites numbering approximately 1958 +/- 235 binding sites per platelet with a dissociation constant (Kd) of 48.3 +/- 12 x 10(-9) mol/L. These values were similar to those obtained for LDL. In contrast to Lp(a), evidence indicates that platelet integrin alpha IIb beta 3 was not involved in the interaction of LDL and intact resting platelets. First, specific ligands for platelet integrin alpha IIb beta 3, such as fibrinogen, vitronectin, and fibronectin, were unable to inhibit the binding of LDL to intact resting platelets. Second, similar LDL binding characteristics (Kd and Bmax values) were found in platelets from control subjects and patients with type I and type II Glanzmann's thrombasthenia, characterized by total and partial lack of GPIIb-IIIa and fibrinogen, respectively. Third, polyclonal antibodies against the GPIIb-IIIa complex (edu-3 and 5B12), human antiserums against platelet alloantigens (anti-Baka/B and anti-PLA1/2), anti-integrin subunits (anti-alpha v and anti-beta 3), and a wide panel of monoclonal antibodies (mAbs) against well-known epitopes of GPIIb (M3, M4, M5, M6, and M95-2b) and GPIIIa (P23-7, P33, P37, P40, and P97) did not affect platelet LDL binding. Finally, in contrast to the proaggregatory effect of native and oxidized LDL, both native and oxidized Lp(a) particles caused a significant dose-dependent decrease of collagen-induced platelet aggregation. In conclusion, we demonstrate that neither the GPIIb-IIIa complex nor GPIIb and GPIIIa individually are membrane binding proteins for LDL on intact resting platelets. Lp(a) particles do not interact with platelet LDL binding sites, and their biological response is clearly different from that of LDL.

Binding Sites↗
PubMed1996

Aberrantly spliced mRNAs of the 3-hydroxy-3-methylglutaryl coenzyme A lyase (HL) gene with a donor splice-site point mutation produce hereditary HL deficiency.

A novel point mutation in the 3-hydroxy-3methyl-glutaryl coenzyme A lyase gene was found in a Turkish patient with homozygous 3-hydroxy-3-methylglutaric acidemia. Amplification by RT-PCR of the mRNA using a six different pairs of oligonucleotides produced no differences in four of the fragments amplified with respect to the control, but generated two fragments of different size. One was representative of a deletion of 126 bp and the other of an insertion of 78 bp. These abnormal mRNAs resulted from a G-->C transversion at the nucleotide +1 of an intron, which changed the invariant GT dinucleotide of the 5' donor splice site. This was associated with the occurrence of an alternative splicing, which led to the skipping of the whole exon of 126 bp, and also with the activation of one cryptic donor splice site in the same intron. These aberrant spliced mRNAs are predicted to encode two abnormal HMG-CoA lyase proteins: the first results in a protein with an internal deletion of 42 amino acids, whose enzyme activity is largely abolished, as the catalytic site was completely removed; the second contains 17 missense amino acids that precede a stop codon. Northern blot analysis showed that the overall content of these aberrantly spliced mRNAs in proband fibroblasts was the same as that found in control fibroblasts. However, hardly any transcript was observed corresponding to the inserted mutated mRNA when it was examined by a specific probe. To quantify the relative proportion of the two mRNAs, a quantitative RT-PCR (the DNA-mimic PCR reaction) was carried out. Results show that the proportion of the inserted mRNAs with respect to the deleted mRNA is only 1.2%. The father, mother, and two brothers of the proband were heterozygous in the G-->C mutation in the +1 nucleotide of the intron considered, while the two alleles of another brother were free of the mutation.

Base Sequence↗
PubMed1995

De novo missense mutation Y174S in exon 1 of the adrenoleukodystrophy (ALD) gene.

Adrenoleukodystrophy (ALD) is an X-linked disease, characterised by an alteration of the peroxisomal beta-oxidation of the very long chain fatty acids. The ALD gene has been identified and mutations have been detected in ALD patients. We report here a new missense mutation in the ALD gene of a male patient, predicting a tyrosine to serine substitution at codon 174 (mutation Y174S). The mother of the ALD patient does not have the Y174S mutation in her leukocyte DNA, indicating that Y174S arose de novo in the patient. Y174S is the first reported de novo mutation in the ALD gene.

Adrenoleukodystrophy↗