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Biomedical subjects

E Lorenzo

Publications and source records attributed to E Lorenzo.

At least 19 recordsLinked to original sources
PubMed2002

Electrocatalytic oxidation of nitric oxide at indium hexacyanoferrate film-modified electrodes.

The electrocatalytic oxidation of nitric oxide (NO) by indium (III) hexacyanoferrate (III) films has been studied. These films are electrodeposited onto glassy carbon electrodes through potential cycling in acidic solutions containing a potassium electrolyte, indium (III), and potassium hexacyanoferrate. The resulting modified electrodes exhibit a reversible redox response ascribed to the oxidation/reduction of iron atoms presents in the electrodeposited film. The films have a potent and persistent electrocatalytic activity towards NO oxidation at neutral pH. The electrocatalytic oxidation of NO takes place at potentials around +0.75 V which represents a moderate diminution in the overpotential. In addition, interferences due to the presence of nitrate and nitrite have been significantly reduced. According to these results, the described modified electrodes have been used as sensors for the determination of NO generated by decomposition of a typical NO-donor, such as S-nitroso- N -acetyl- d, l -penicillamine (SNAP).

Journal Article↗
PubMed2001

Selective inhibition of vascular endothelial growth factor-mediated angiogenesis by cyclosporin A: roles of the nuclear factor of activated T cells and cyclooxygenase 2.

Cyclosporin A (CsA) is an immunosuppressive drug that inhibits the activity of transcription factors of the nuclear factor of activated T cells (NFAT) family, interfering with the induction of cytokines and other inducible genes required for the immune response. Here we show that CsA inhibits migration of primary endothelial cells and angiogenesis induced by vascular endothelial growth factor (VEGF); this effect appears to be mediated through the inhibition of cyclooxygenase (Cox)-2, the transcription of which is activated by VEGF in primary endothelial cells. Consistent with this, we show that the induction of Cox-2 gene expression by VEGF requires NFAT activation. Most important, the CsA-mediated inhibition of angiogenesis both in vitro and in vivo was comparable to the Cox-2 inhibitor NS-398, and reversed by prostaglandin E(2). Furthermore, the in vivo corneal angiogenesis induced by VEGF, but not by basic fibroblast growth factor, was selectively inhibited in mice treated with CsA systemically. These findings involve NFAT in the regulation of Cox-2 in endothelial cells, point to a role for this transcription factor in angiogenesis, and may provide a novel mechanism underlying the beneficial effects of CsA in angiogenesis-related diseases such as rheumatoid arthritis and psoriasis.

Angiogenesis Inhibitors↗
PubMed2001

The use of tat and env sequences from human immunodeficiency virus 1 in phylogenetic epidemiological studies.

Using nucleotide sequences from the first exon of the tat gene of the human immunodeficiency virus 1 (HIV-1), we tested the hypothesis that a Florida dentist (a common source) infected five of his patients in the course of dental procedures against the null hypothesis that the dentist and each individual of the dental group independently acquired the virus within the local community. This novel approach of analyzing the tat gene region was used because it may, in some circumstances, be more informative for phylogenetic epidemiology than the more commonly used C2-V3 envelope gene region. The first exon of the tat gene was polymerase chain reaction (PCR)-amplified and directly sequenced from uncultured peripheral blood mononuclear cells. Patient's sequences were compared with sequences from six HIV-1 infected heterosexual couples unrelated to the dentist or the five patients, but from the same general geographic area. In addition, a sixth infected dental patient, previously inferred to have acquired HIV-1 from a source other than the dentist, was included. Multiple phylogenetic analyses demonstrated that the sequences of the five patients were significantly more closely related to each other than to sequences of the controls. Our results using tat sequences, combined with envelope sequence data, strongly support a common phylogenetic epidemiological relationship among these five patients, and the HIV-1 infected dentist who treated them. Correct recovery of known epidemiological relationships among couples included in the analysis further strengthens this conclusion.

Base Sequence↗
PubMed2001

Psychological consequences of the 1998 landslide in Sarno, Italy: a community study.

OBJECTIVE: This community study assessed the prevalence of post-traumatic stress disorder (PTSD) and the psychosocial consequences of the landslide which occurred in Sarno, Southern Italy, in May 1998. METHOD: A random sample (n=272) of the population living in the highest risk area of Sarno, and a control group recruited in a small town situated near the disaster area, but not affected by the event, were assessed 1 year after the disaster by standardized instruments. RESULTS: Of the subjects recruited in Sarno, 27.6% met DSM-IV criteria for PTSD; 59% subjects recruited in Sarno and 35% of the control group were identified as "probable cases" by the GHQ-30 (P<0.0001). Subjects recruited in Sarno had significantly higher scores on the four GHQ-30 subscales identified by factor analysis. CONCLUSION: This study emphasizes the negative impact of a natural catastrophic event on mental health, and the need for preventive interventions.

Adolescent↗
PubMed2000

Biosensors based on membrane-bound enzymes immobilized in a 5-(octyldithio)-2-nitrobenzoic acid layer on gold electrodes.

Gold electrodes were modified through chemisorption of 5-(octyldithio)-2-nitrobenzoic acid (ODTNB). ODTNB includes a long chain in a short-length thio acid, providing a heterogeneous-like alkanethiol layer after adsorption on gold electrodes. Membrane-bound enzymes, in particular D-fructose dehydrogenase (FDH), D-gluconate dehydrogenase (GADH), and L-lactic dehydrogenase (cytochrome b2) (Cyb2), were immobilized onto ODTNB-modified gold electrodes simply by adsorption. The short-length thio acid may provide electrostatic interactions with enzyme surface charges, while the alkanethiolate enables hydrophobic interaction with the largely lipophilic, membrane-bound enzymes. The immobilization of FDH, GADH, and Cyb2 onto ODTNB-modified gold surfaces has been studied with the quartz crystal microbalance (QCM). Spectrophotometric and electrochemical assays indicate that the immobilized enzyme retains its enzymatic activity after immobilization onto the ODTNB-modified gold surface. The amount of immobilized (and active) enzyme was estimated from QCM to be of the order of 2.5 x 10(-12)-5.3 x 10(-12) mol x cm(-2). A fructose biosensor was developed, making use of a gold surface modified with ODTNB and fructose dehydrogenase, employing hydroxymethylferrocene as a mediator in solution. Calibration curves exhibited a linear relation between the biosensor response and the substrate concentration up to 0.7 mM. Statistical analysis gave an excellent linear correlation (r = 0.9993) and a sensitivity of 6.1 mM(-1) fructose. The biosensor shows a significant stable catalytic current for at least 25 days.

Biosensing Techniques↗
PubMed1999

Dithiobissuccinimidyl propionate as an anchor for assembling peroxidases at electrodes surfaces and its application in a H2O2 biosensor.

Exposure of gold surfaces to solutions of dithiobis N-succinimidyl propionate (DTSP) gives rise to the modification of the surface with N-succinimidyl-3-thiopropionate (NSTP) which can, in turn, react with amino groups allowing for the covalent immobilization of enzymes such as horseradish peroxidase (HRP). The coverage of NSTP has been estimated to be of the order of 1.3 x 10(-10) from the charge consumed during its reductive desorption. The binding reaction of HRP with NSTP modified gold surfaces has been studied with the quartz crystal microbalance, and the results suggest that the immobilization process involves two steps in which the first (faster) appears to correspond to the rapid incorporation of the enzyme whereas the second is likely due to the slow incorporation of additional enzyme and/or reorganization of the immobilized layer. Spectrophotometric and electrochemical assays indicate that the immobilized HRP retains its enzymatic activity after immobilization onto the DTSP modified gold surface. The amount of immobilized (and active) HRP was estimated from QCM and spectrophotometric measurements to be of the order of 1.5 x 10(-11) mol/cm2. A peroxide biosensor was developed making use of a gold surface modified with DTSP and HRP employing Os and Ru complexes of 1,10-phenanthroline 5,6-dione (phen-dione) of the type [M(phendione)x(L)3-x]+2 (where L = 1,10-phenanthroline or 2,2'-bipyridine, x = 1-3) as mediators with the quinone moieties being the active component. The efficiency of the mediators increased with increasing number of phendione ligands.

Adsorption↗
PubMed1999

Vascular endothelial growth factor activates nuclear factor of activated T cells in human endothelial cells: a role for tissue factor gene expression.

Vascular endothelial growth factor (VEGF) is a potent angiogenic inducer that stimulates the expression of tissue factor (TF), the major cellular initiator of blood coagulation. Here we show that signaling triggered by VEGF induced DNA-binding and transcriptional activities of nuclear factor of activated T cells (NFAT) and AP-1 in human umbilical vein endothelial cells (HUVECs). VEGF also induced TF mRNA expression and gene promoter activation by a cyclosporin A (CsA)-sensitive mechanism. As in lymphoid cells, NFAT was dephosphorylated and translocated to the nucleus upon activation of HUVECs, and these processes were blocked by CsA. NFAT was involved in the VEGF-mediated TF promoter activation as evidenced by cotransfection experiments with a dominant negative version of NFAT and site-directed mutagenesis of a newly identified NFAT site within the TF promoter that overlaps with a previously identified kappaB-like site. Strikingly, this site bound exclusively NFAT not only from nuclear extracts of HUVECs activated by VEGF, a stimulus that failed to induce NF-kappaB-binding activity, but also from extracts of cells activated with phorbol esters and calcium ionophore, a combination of stimuli that triggered the simultaneous activation of NFAT and NF-kappaB. These results implicate NFAT in the regulation of endothelial genes by physiological means and shed light on the mechanisms that switch on the gene expression program induced by VEGF and those regulating TF gene expression.

Binding Sites↗
PubMed1998

Analytical strategies for amperometric biosensors based on chemically modified electrodes.

Various strategies based on the use of chemically modified electrodes for the development of amperometric biosensors are described. Particular emphasis is placed on materials capable of catalyzing the oxidation of NADH and coupling these with enzymatic activities for biosensor construction. In terms of electrocatalysts, the discussion will centre on electrodeposited films of 3,4-dihydroxy benzaldehyde (3,4-DHB) and related analogs as well as on electrodeposited films of transition metal complexes of 1,10-phenanthroline-5,6-dione (phen-dione). Electrodeposited films of these materials have been coupled to the enzymatic activity of aldehyde dehydrogenase and alcohol dehydrogenase for the development of biosensors for aldehydes and ethanol, respectively.

Alcohol Dehydrogenase↗
PubMed1998

Interlaboratory concordance of DNA sequence analysis to detect reverse transcriptase mutations in HIV-1 proviral DNA. ACTG Sequencing Working Group. AIDS Clinical Trials Group.

Thirteen laboratories evaluated the reproducibility of sequencing methods to detect drug resistance mutations in HIV-1 reverse transcriptase (RT). Blinded, cultured peripheral blood mononuclear cell pellets were distributed to each laboratory. Each laboratory used its preferred method for sequencing proviral DNA. Differences in protocols included: DNA purification; number of PCR amplifications; PCR product purification; sequence/location of PCR/sequencing primers; sequencing template; sequencing reaction label; sequencing polymerase; and use of manual versus automated methods to resolve sequencing reaction products. Five unknowns were evaluated. Thirteen laboratories submitted 39043 nucleotide assignments spanning codons 10-256 of HIV-1 RT. A consensus nucleotide assignment (defined as agreement among > or = 75% of laboratories) could be made in over 99% of nucleotide positions, and was more frequent in the three laboratory isolates. The overall rate of discrepant nucleotide assignments was 0.29%. A consensus nucleotide assignment could not be made at RT codon 41 in the clinical isolate tested. Clonal analysis revealed that this was due to the presence of a mixture of wild-type and mutant genotypes. These observations suggest that sequencing methodologies currently in use in ACTG laboratories to sequence HIV-1 RT yield highly concordant results for laboratory strains; however, more discrepancies among laboratories may occur when clinical isolates are tested.

Codon↗
PubMed1998

[Epidemiological study of blood lead levels in young subjects in the Campania region: preliminary data].

Blood lead levels were assayed in 261 children (133 males and 128 females) living in Campania, 137 (63 females and 74 males) in urban areas and 124 (65 females and 59 males) in rural zones, aged between 0.197 and 16.863 years. Blood lead determination was carried out by electrothermal atomic absorption spectroscopy. All children were interviewed about common risk factors for lead exposure. PbB (median +/- SD) were significantly higher in the urban than in the rural population (6.0 +/- 0.31 vs 3.75 +/- 0.25 micrograms/100 ml; p < 0.001). The frequency of blood lead level above 10 micrograms/100 ml was 4.21% in our tested group, i.e., significantly lower than in previous studies. A significant direct correlation between blood lead levels and age was found (r = 0.47; p < 0.001). In agreement with the literature on this subject, our findings show a significant reduction with time, of blood lead levels of children and adolescents in our region. Time of exposure more than total dose seems to be important for the increase of blood lead level.

Adolescent↗
PubMed1996

Reverse transcriptase mutations in HIV-1-infected children treated with zidovudine.

Human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) mutations were detected in DNA from peripheral blood mononuclear cells from 11 of 12 HIV-1-infected children after 11-20 months of zidovudine monotherapy. The number of children with mutations detected at each codon were as follows: codon 41, 4; codon 67, 2; codon 70, 7; codon 215, 7; codon 219, 0. Codon 41 mutations were found only in the presence of a codon 215 mutation and in the absence of a codon 70 mutation. The codon 41/215 mutant combination was associated with decline in weight-for-age z score during therapy, weight < 10th percentile, CD4+ cell counts < 3rd percentile, and immune-complex dissociated HIV-1 p24 antigen (ICD p24 Ag) levels > 100 pg/ml. Patients developing the codon 70 mutation tended to have body weight > 30th percentile, CD4+ cell counts > 25th percentile, and ICD p24 Ag < 100 pg/ml. The codon 41 mutation was associated with clinical deterioration during a 6-month followup period.

Anti-HIV Agents↗
PubMed1996

The Tat and C2-V3 envelope genes in the molecular epidemiology of human immunodeficiency virus-1.

In this study HIV-1 proviral DNA sequences derived from 201 clones of the C2-V3 env region and the first exon of tat were obtained from six HIV-1-infected heterosexual couples. These molecular data were used to confirm the epidemiological relationships. The ability of the molecular data to draw such conclusions was also tested. A bootstrap parsimony analysis of the C2-V3 sequences showed one couple failed to cluster and only two couples clustered in more than 70% of the replicates. The rapid diversification of the C2-V3 region and the length of time that elapsed since the infection event may have limited the certainty of the conclusions that can be reached to infer epidemiological relatedness from this region. Using data from the tat region, all couples clustered, four of them in more than 80% of bootstrap replicates. A single clone from the tat region did not cluster with others from that patient or with those from that patient's partner, indicating that multiple clones are necessary to firmly establish phylogenetic linkage. Nevertheless, the tat region was much more useful in establishing epidemiological relationships among this group than the commonly used C2-V3.

Amino Acid Sequence↗
PubMed1996

UV detection of triazine herbicides and their hydroxylated and dealkylated degradation products in well water.

The aim of this work was to develop a simple method to confirm the presence of hydroxytriazine products (hydroxyatrazine, hydroxysimazine, hydroxyethylterbutyltriazine and hydroxydiaminotriazine) in water and to apply it to well water samples. The hydroxytriazines were concentrated on a Sep-Pak C18 cartridge. Analysis was performed by HPLC using an RP8-DB column with phosphate buffer (pH 4.7)-acetonitrile (72:28, v/v) as the mobile phase and photodiode-array detection at 233 nm. Hydroxyatrazine, hydroxysimazine and hydroxyethylterbutyltriazine were detected at ppb levels in samples from two shallow wells under a very sandy soil citrus orchard taken at three different times in a 1-year period.

Chromatography, High Pressure Liquid↗
PubMed1996

Enzyme support systems for biosensor applications based on gold-coated nylon meshes.

A novel experimental protocol for enzyme immobilization based on the use of a very permeable support is described and applied to the development of an acetylcholinesterase (AChE) based biosensor. In this system, the enzyme was immobilized onto a gold-coated nylon mesh via a self-assembled monolayer of a bifunctional reagent, cystamine, preadsorbed onto the gold surface. This support has been characterized by optical microscopy and electrochemical measurements of permeability. In the assembled biosensor, the AChE modified mesh was placed over a glassy carbon electrode and the response to 4-aminophenylacetate, used as substrate, was monitored via the enzymatic reaction product, 4-aminophenol, by oxidation at +0.25 V vs. SSCE. This approach to biosensor design has been extended to the determination of organophosphorus and carbamate pesticides by their inhibition of AChE enzymatic activity.

Acetylcholinesterase↗
PubMed1995

[Health education in school].

OBJECTIVES: To discover the contents of health education taught at present in the EGB (basic) schools of Castelldefels, the opinions of teachers on health education in schools, and to stimulate reflection among teachers and health-workers on health education at school. DESIGN: A crossover study using a self-administered questionnaire. SETTING: EGB schools in the town of Castelldefels. PARTICIPANTS: All the EGB teachers in Castelldefels (n = 261). MEASUREMENTS AND MAIN RESULTS: 148 teachers (57%) replied to the survey. Health education was considered necessary by 56.8% and essential by 33.1%. They needed technical support and adequate material to carry it through. Integration of health education into the teaching programmes of the school syllabus's different subjects was the best way of carrying it out, in the view of the majority. The advantage of different subjects coincided with those described in the "Health Plan for Catalonia". CONCLUSIONS: Given that we consider teachers to be the professionals best-placed to carry out health education at school, it is useful to confirm their awareness of its importance. As health education is also an objective of the primary care teams, these should be the reference and support point for teachers' demands for technical help.

Adult↗