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P Vidal

Publications and source records attributed to P Vidal.

At least 37 records · Page 2Linked to original sources
PubMed1997

A new peptide vector for efficient delivery of oligonucleotides into mammalian cells.

The development of antisense and gene therapy has focused mainly on improving methods for oligonucleotide and gene delivery into cells. In the present work, we describe a potent new strategy for oligonucleotide delivery based on the use of a short peptide vector, termed MPG (27 residues), which contains a hydrophobic domain derived from the fusion sequence of HIV gp41 and a hydrophilic domain derived from the nuclear localization sequence of SV40 T-antigen. The formation of peptide vector/oligonucleotide complexes was investigated by measuring changes in intrinsic tryptophan fluorescence of peptide and of mansyl-labelled oligonucleotides. MPG exhibits relatively high affinity for both single- and double-stranded DNA in a nanomolar range. Based on both intrinsic and extrinsic fluorescence titrations, it appears that the main binding between MPG and oligonucleotides occurs through electrostatic interactions, which involve the basic-residues of the peptide vector. Further peptide/peptide interactions also occur, leading to a higher MPG/oligonucleotide ratio (in the region of 20/1), which suggests that oligonucleotides are most likely coated with several molecules of MPG. Premixed complexes of peptide vector with single or double stranded oligonucleotides are delivered into cultured mammalian cells in less than 1 h with relatively high efficiency (90%). This new strategy of oligonucleotide delivery into cultured cells based on a peptide vector offers several advantages compared to other commonly used approaches of delivery including efficiency, stability and absence of cytotoxicity. The interaction with MPG strongly increases both the stability of the oligonucleotide to nuclease and crossing of the plasma membrane. The mechanism of cell delivery of oligonucleotides by MPG does not follow the endosomal pathway, which explains the rapid and efficient delivery of oligonucleotides in the nucleus. As such, we propose this peptide vector as a powerful tool for potential development in gene and antisense therapy.

3T3 Cells↗
PubMed1997

Argentinian collaborative study on prevalence of erythromycin and penicillin susceptibility in Streptococcus pyogenes. The Argentinian Streptococcus Study Group.

Two monthly studies on the prevalence of penicillin and erythromycin susceptibility of Streptococcus pyogenes were performed in May and October of 1994 in Argentina. A total of 58 centers from 27 cities participated in these studies. A total of 1072 isolates were tested by a diffusion method, although 595 isolates were tested both by the diffusion and an agar dilution method (n = 1767 isolates). No penicillin-resistant streptococci were found in our study (MIC100 = 0.03 microgram/ml). Only four isolates were confirmed as erythromycin resistant S. pyogenes (prevalence 0.14 and 0.28% in May and October 1994, respectively). Resistance in three isolates was due to an inducible mechanism, although in one strain a different phenotype was observed.

Anti-Bacterial Agents↗
PubMed1997

[New strategy for RNA vectorization in mammalian cells. Use of a peptide vector].

A major barrier for gene delivery is the low permeability of nucleic acids to cellular membranes. The development of antisenses and gene therapy has focused mainly on improving methods of oligonucleotide or gene delivery to the cell. In this report we described a new strategy for RNA cell delivery, based on a short single peptide. This peptide vector is derived from both the fusion domain of the gp41 protein of HIV and the nuclear localization sequence of the SV40 large T antigen. This peptide vector localizes rapidly to the cytoplasm then to the nucleus of human fibroblasts (HS-68) within a few minutes and exhibits a high affinity for a single-stranded mRNA encoding the p66 subunit of the HIV-1 reverse transcriptase (in a 100 nM range). The peptide/RNA complex formation involves mainly electrostatic interactions between the basic residues of the peptide and the charges on the phosphate group of the RNA. In the presence of the peptide-vector fluorescently-labelled mRNA is delivered into the cytoplasm of mammalian cells (HS68 human fibroblasts) in less than 1 h with a relatively high efficiency (80%). This new concept based on a peptide-derived vector offers several advantages compared to other compounds commonly used in gene delivery. This vector is highly soluble and exhibits no cytotoxicity at the concentrations used for optimal gene delivery. This result clearly supports the fact that this peptide vector is a powerful tool and that it can be used widely, as much for laboratory research as for new applications and development in gene and/or antisense therapy.

Cells, Cultured↗
PubMed1997

Studies on keratinophilic fungi. IX: Neoarachnotheca gen. nov. and a new species of Nannizziopsis.

Neoarachnotheca is proposed as a new genus of Onygenales. The outstanding generic characteristics are white, spherical ascomata with a wall formed by a network of hyphae and spherical, subhyaline ascospores with an irregular sheath. Nt. keratinophila, the type species, characterized by wavy peridial hyphae has been isolated from marine and river sediments and Myriodontium keratinophilum is its anamorph. Nannizziopsis tropicalis is proposed as a new species based on a strain isolated from soil in Burundi. RFLPs analysis of ITS and 5.8S rDNA support these proposals. The differences with related genera are discussed.

Ascomycota↗
PubMed1997

[Lower extremity salvage in diabetics: microsurgical muscle transplantation with and without previous vascular reconstruction].

Soft tissues wounds with or without bony involvement are a common problem and a cause of limb loss in diabetics. Usually local care, antibiotics, minor debridement and skin grafting are enough for successful handling of these lesions. When there is associated limb ischemia, revascularization is indicated. In patients with large ulcers, proximal bony involvement and tendon exposure, the incidence of primary amputation rises, frequently being considered the only alternative. Two cases of diabetic patients with indication of primary amputation of a lower limb for large infected ulcers are reported. A microvascularized muscle transplant was used to cover large defects of soft tissue, tendons and infected bone. One patient presented also critical ischaemia of the limb, requiring iliac angioplasty and a femoro-distal by-pass with in situ greater saphenous vein previous to the muscle graft. Both patients had no postoperative complications, being able to walk two months after the operation with their useful limb. Microvascularized muscle transplant with or without revascularization is a very useful alternative to amputation in the management of complex wounds of selected diabetic patients.

Adult↗
PubMed1996

The utility of mitochondrial DNA restriction analysis in the classification of strains of Chrysosporium (hyphomycetes).

The taxonomy of the fungal genus Chrysosporium is mainly based on morphological features. In our current studies we have found several Chrysosporium species which showed intermediate morphological characteristics between several species. For this reason, we have carried out an analysis of the mitochondrial DNA restriction fragments of these strains that have permit us to classify each isolate strain in a species.

Chrysosporium↗
PubMed1996

The problem of bilateral foot reconstruction after severe burns.

Reconstruction of bilateral, distal lower limb defects presents a major reconstructive challenge. In the patient with a major burn injury, however, the problem of bilateral foot reconstruction is compounded by both the limited availability of normal unscarred donor sites and by the limited availability of recipient vessels. A case is presented where bilateral dorsum of foot defects in a patient with a 50% surface area burn were successfully reconstructed using a single parascapular free flap. The problems presented by this case are discussed.

Adult↗
PubMed1996

An unreported cause of rupture of the extensor pollicis longus tendon.

Avulsion fractures of the index metacarpal at the insertion of extensor carpi radialis longus are rare. We report such a fracture and the resulting complication of division of the extensor pollicus longus tendon, by the avulsed bony fragment. Careful clinical assessment and appropriate radiological examination is needed to diagnose this rare fracture and internal fixation is recommended.

Adult↗
PubMed1993

Size- and charge selectivity of glomerular filtration in Type 1 (insulin-dependent) diabetic patients with and without albuminuria.

Albuminuria is the first clinical event in the development of diabetic nephropathy. We assessed glomerular charge- and size selectivity in 51 patients with Type 1 (insulin-dependent) diabetes mellitus of juvenile onset and 11 healthy individuals. Patients were allocated to five groups. The urinary albumin excretion rate was normal in group D1; 30-100 mg/24 h in group D2; 101-300 mg/24 h in group D3 and greater than 300 mg/24 h in groups D4 and D5. Group D5 had elevated serum creatinine (above 110 mumol/l). Glomerular filtration rate and renal plasma flow were determined by constant infusion techniques and tubular protein reabsorption by excretion of beta 2-microglobulin. Charge selectivity was estimated from the IgG/IgG4 selectivity index. Size selectivity was measured by dextran clearance. Dextran was measured by refractive index detection after fractionation (2 A fractions in the range 26-64 A) by size exclusion chromatography. IgG/IgG4 selectivity index was significantly decreased in patients with albuminuria (p < 0.001). The drop in IgG/IgG4 selectivity index was found in patients with minimal albuminuria (D2) and was not accompanied by any changes in tubular function or glomerular haemodynamics. Size selectivity was significantly altered only in patients with the most advanced nephropathy (D5) as reflected by an increase in the clearance of 62 A dextran (p < 0.04). We conclude that loss of glomerular charge selectivity precedes or accompanies the formation of new glomerular macromolecular pathways in the development of diabetic nephropathy.

Adult↗
PubMed1993

Aminoguanidine inhibits protein browning without extensive Amadori carbonyl blocking.

It has been proposed that aminoguanidine reacts extensively with Amadori carbonyl groups of glycated proteins thus blocking them and inhibiting the further reactions which lead to browning and fluorescence development. We have glycated bovine serum albumin in the presence of 1, 5, 10 and 25 mM aminoguanidine and measured fluorescence development at 440 nm upon excitation at 370 nm, free (unblocked) Amadori groups as fructosamine with a colorimetric assay and furosine by HPLC, as an index of total Amadori products. Aminoguandine significantly inhibited fluorescence development at all the tested concentrations (31%, 65%, 69% and 82% inhibitions, respectively) (P < 0.001). Blocking of Amadori groups was demonstrated by decreased fructosamine and unchanged furosine yields but only at the higher concentrations and to a very limited extent (13% and 27% blocking, respectively) (P < 0.01). Incubation of Aminoguanidine with albumin produced the appearance of 320 nm absorbing yellow chromophores, quite increased in the presence of glucose. These results suggest that Aminoguanidine is able to block Amadori groups, as previously hypothesized, but question the importance of this mechanism as an explanation of its capacity to inhibit browning. Scavenging of glucose seems to have no impact on glycation as seen by unchanged furosine yields.

Animals↗
PubMed1993

Regeneration of the distal phalanx. A case report.

A patient who suffered a traumatic avulsion of the distal phalanx of the right index finger is described. Following simple wound toilet and closure, the distal phalanx generated to give an excellent functional result.

Bone Regeneration↗
PubMed1992

Effect of glycation on the heterogeneity of human serum albumin analysed by reversed-phase high-performance liquid chromatography in a solvent containing formic acid.

Non-enzymic glycation of human serum albumin (HSA) induces a change in its charge heterogeneity that may account for its particular renal clearance in patients with early diabetic nephropathy. A new high-performance liquid chromatographic analysis for the study of HSA heterogeneity is described based on a high content of formic acid in the mobile phase combined with a concave gradient of isopropanol. Under these conditions, native HSA was separated into three individual components (I, II and III). When glycated HSA was analysed, it was found that although the present method is not suitable for the separation of glycated from non-glycated HSA, it shows the effect of glycation in producing changes in HSA heterogeneity that are different from those reported on surface change. This finding suggests an additional factor (probably conformational changes) that is contributing to the heterogeneity of glycated HSA.

Chromatography, Affinity↗