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Biomedical subjects

E Vives

Publications and source records attributed to E Vives.

At least 19 recordsLinked to original sources
PubMed2000

All-L-Leu-Pro-Leu-Pro: a challenging cyclization.

In this paper, we report the difficult synthesis of cyclo(Leu-Pro-Leu-Pro). While the cyclization of Leu-Pro-Leu-D-Pro did not cause problems, the all-L-peptide afforded cyclodimer rather than cyclotetrapeptide (cyclomonomer). A first attempt using our reversible backbone substitution methodology failed. However, we were successful in obtaining the desired cyclo(Leu-Pro-Leu-Pro) by decreasing the concentration. The ratio of cyclomonomer to cyclodimer was raised to 1:1.1 using BOP and 1:0.6 using HATU under our high dilution condition. The structures of the cyclopeptides were confidently assigned by electrospray ionization mass spectrometry and NMR.

Cell Division↗
PubMed2000

Studying avalanches in the ground state of the two-dimensional random-field ising model driven by an external field

We study the exact ground state of the two-dimensional random-field Ising model as a function of both the external applied field B and the standard deviation sigma of the Gaussian random-field distribution. The equilibrium evolution of the magnetization consists in a sequence of discrete jumps. These are very similar to the avalanche behavior found in the out-of-equilibrium version of the same model with local relaxation dynamics. We compare the statistical distributions of magnetization jumps and find that both exhibit power-law behavior for the same value of sigma. The corresponding exponents are compared.

Journal Article↗
PubMed1999

Characterisation of membrane oligonucleotide-binding proteins and oligonucleotide uptake in keratinocytes.

Inadequate cellular compartmentalisation of plasmid DNA and antisense oligodeoxynucleotides (ODNs) is generally considered as a major limitation in their use. In this study, an approach combining in situ visual-isation of rhodamine-labelled ODNs and affinity modification of proteins by radiolabelled-alkylating ODN derivatives has been used to investigate the uptake of ODNs into keratinocytes. We confirm here that unmodified ODNs are efficiently taken up and accumulate in cell nuclei in primary keratinocytes as well as in HaCaT and A431 keratinocyte cell lines. Uptake is fast, irreversible, saturable and not significantly altered by incubation at low temperature. Affinity modification studies in keratinocyte cell lines has revealed two high-affinity, cell-specific interactions between ODNs and proteins of 61-63 kDa and 35 kDa. Trypsin pre-treatment of A431 cells and pre-incubation with polyanions, or with unlabelled nucleic acid competitors, inhibited the accumulation of rhodamine-labelled ODNs in nuclei as well as the affinity labelling of the 61-63 kDa doublet and 35 kDa ODN-binding proteins by reactive ODN derivatives. Finally, cell fractionation studies indicated that these ODN-binding proteins were essentially localised in the plasma membrane. Our results suggest that these ODN-binding proteins might be involved in the recognition and transport of ODNs into keratinocytes.

Cells, Cultured↗
PubMed1998

Infantile idiopathic scoliosis in the newborn.

We have reviewed 7 patients (5 boys and 2 girls) with infantile idiopathic scoliosis which was present at birth and was diagnosed at ages from 1 day to 1 month. The mean follow up was 16 years. The objectives were to discover whether intrauterine forces play a role in the aetiology and to determine whether early treatment of a potentially progressive curve can induce resolution. Two infants were male conjoined twins and were united by skin over the posterior sacrum. Six infants had a rib vertebral angle difference greater than 20 degrees in the first radiograph and 5 had stiff curves. In 2 with flexible curves, the deformity disappeared by the end of the first year. The 5 with stiff curves were treated conservatively for 6 to 24 months. Growth has now been completed in 5; 4 have a straight spine and one developed an adolescent curve of 26 degrees. The 2 who are still growing have no scoliosis. Intrauterine moulding was only demonstrated in the conjoined twins. There was a correlation between the rib vertebral angle difference above 20 degrees and the rigidity of the curve. Early treatment of a potentially progressive curve can lead to resolution.

Female↗
PubMed1997

Pharmacokinetics of oligonucleotides in cell culture.

Synthetic oligonucleotides offer interesting perspectives for the regulation of gene expression in normal and pathological situations. Poor uptake in many cell types, inadequate intracellular compartmentalization, often fragmentary knowledge of intracellular behaviour and mechanism of action, and lack of specificity remain major challenges. These limitations strongly urge the design of new oligonucleotide analogues and more efficient antisense strategies. Present achievements and perspectives for further developments will be discussed with emphasis on cell delivery and intracellular fate.

Animals↗
PubMed1997

Congenital hemangiopericytoma: two cases of familiar presentation.

We report two cases of congenital hemangiopericytoma localized in the abdominal wall in the first patient and scalp in the second. The treatment of both cases consisted in the complete resection of the tumor mass. Four and two years later the patients remain asymptomatic. The special interest in this case report lies in the extremely low incidence of congenital hemangiopericytoma and that this is the first reference to affected siblings.

Diagnosis, Differential↗
PubMed1994

Identification of a novel HIV-1 TAR RNA bulge binding protein.

The Tat protein binds to TAR RNA to stimulate the expression of the human immunodeficiency virus type 1 (HIV-1) genome. Tat is an 86 amino acid protein that contains a short region of basic residues (aa49-aa57) that are required for RNA binding and TAR is a 59 nucleotide stem-loop with a tripyrimidine bulge in the upper stem. TAR is located at the 5' end of all viral RNAs. In vitro, Tat specifically interacts with TAR by recognising the sequence of the bulge and upper stem, with no requirement for the loop. However, in vivo the loop sequence is critical for activation, implying a requirement for accessory cellular TAR RNA binding factors. A number of TAR binding cellular factors have been identified in cell extracts and various models for the function of these factors have been suggested, including roles as coactivators and inhibitors. We have now identified a novel 38 kD cellular factor that has little general, single-stranded or double-stranded RNA binding activity, but that specifically recognises the bulge and upper stem region of TAR. The protein, referred to as BBP (bulge binding protein), is conserved in mammalian and amphibian cells and in Schizosaccharomyces pombe but is not found in Saccharomyces cerevisiae. BBP is an effective competitive inhibitor of Tat binding to TAR in vitro. Our data suggest that the bulge-stem recognition motif in TAR is used to mediate cellular factor/RNA interactions and indicates that Tat action might be inhibited by such competing reactions in vivo.

Animals↗
PubMed1994

Effects of the Tat basic domain on human immunodeficiency virus type 1 transactivation, using chemically synthesized Tat protein and Tat peptides.

To study the structure relationship of different Tat domains, the full-length Tat protein Tat1-86, the gene product of the first exon Tat1-72 which retains full activity of the protein, and a panel of shorter peptides mimicking different regions of the primary structure of the Tat protein were chemically synthesized by the solid-phase method, using an efficient protocol. Synthetic Tat1-86 and Tat1-72 transactivated beta-galactosidase activity in HeLa cells containing the lacZ gene under the control of the human immunodeficiency virus type 1 long terminal repeat. Analyses of the activity of Tat1-86 and Tat1-72 with the sulfhydryl of cysteine residues free or protected by the acetamidomethyl group showed that only the Tat fragments with deprotected cysteine residues retain transactivation ability. In contrast, peptide Tat1-48 was inactive, with cysteine residues either free or protected. Similarly, other shorter synthetic peptides covering the different Tat domains were inactive. Interestingly, when peptides Tat1-48 and Tat38-60 were used simultaneously, a significant transactivation was obtained. This result suggests that both peptide domains are implicated in transactivation, probably by acting at two different sites. This permits us to propose a fundamentally new step in the understanding of the molecular mechanism of Tat transactivation.

Amino Acid Sequence↗