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Biomedical subjects

M Ibáñez

Publications and source records attributed to M Ibáñez.

At least 19 recordsLinked to original sources
PubMed2004

Behavioral profile of SB 269970, a selective 5-HT(7) serotonin receptor antagonist, in social encounters between male mice.

The 5-HT(7) receptor is targeted by several antipsychotics, such as pimozide or clozapine, which have demonstrated antiaggressive properties in laboratory animal models. Likewise, 'in situ' hybridization and autoradiography studies have revealed moderate to high densities of 5-HT(7) receptors in limbic areas and hypothalamus, which have long been involved in the control of aggression. However, to date there is no evidence concerning the role of this receptor in the regulation of aggression. This study was designed to examine the effects of SB 269970 (1, 2, 4, 8, 16 and 32 mg/kg, i.p.), a selective 5-HT(7) receptor antagonist, on agonistic behavior elicited by isolation in mice. Individually housed mice were exposed to anosmic standard opponents 15 min after drug administration and encounters were videotaped and evaluated using an ethopharmacologically-based analysis. The results indicated that SB 269970 did not produce any significant behavioral changes, suggesting that 5-HT(7) receptors might not be involved in the modulation of aggression. Further studies with other selective ligands for these receptors are needed to confirm these findings.

Agonistic Behavior↗
PubMed2003

[Neurological follow-up of very low birth weight newborns at the age of two years (1998-1999)].

BACKGROUND: Because of improved obstetric and neonatal care, there is growing interest in the later outcome of very low birth weight newborns. OBJECTIVES: The aim of this study was to evaluate the survival rate of very low birth weight newborns and to identify disabilities at the age of 2 years. MATERIAL AND METHODS: An observational, follow-up study was performed of neonates with a birth weight of under 1,500 grams born between 1998 and 1999. The follow-up program included pediatric, maturative, neurological, psychological, ophthalmological, and audiological evaluation. Neurosensorial disabilities were classified as mild, moderate, or severe. RESULTS: One hundred thirty-six very low birth weight newborns were admitted. The survival rate was 77.9 % and 83.9 % completed the follow-up to the age of 2 years. The neurosensorial disability rate was 20.2 %; disability was severe in 9 %, moderate in 1.1 %, and mild in 10.1 %. In patients lost to follow-up, birth weight was higher, gestational age was older, and sonographic findings were more frequently normal. CONCLUSION: Survival in very low birth weight newborns has increased with improved neonatal care. The presence of sequelae was similar to that found in other follow-up studies. A substantial number of patients were lost to follow up, which influenced the disability rates.

Child, Preschool↗
PubMed1999

Phospholipid membranes form specific nonbilayer molecular arrangements that are antigenic.

Hexagonal phase (H(II))-preferring lipids such as phosphatidate, cardiolipin, and phosphatidylserine form nonbilayer molecular arrangements in lipid bilayers. While their presence in biological membranes has not been established, in vitro studies suggest that alterations in membrane properties modify their function. In this study, antiphospholipid monoclonal antibodies were developed against nonbilayer structures. One of the monoclonal antibodies identifies nonplanar surfaces in liposomes and in membranes of cultured cells. These results are the first evidence that natural membranes maintain a fragile balance between bilayer and nonbilayer lipid arrangements. Therefore, these antibodies can be used to evaluate the role of H(II)-preferring lipids in the modulation of membrane activities. Our studies demonstrated that nonplanar surfaces are highly immunogenic. Although these structures are normally transient, their formation can be stabilized by temperature variations, drugs, antibiotics, apolar peptides, and divalent cations. Our studies demonstrated that abnormal exposure of nonbilayer arrangements may induce autoimmune responses as found in the antiphospholipid syndrome.

Animals↗
PubMed1998

Improving the solid-phase extraction of "quat" pesticides from water samples. Removal of interferences.

A novel strategy, based on the addition of a cationic surfactant, for preventing the interferences associated with a diminution in the efficacy of solid-phase extraction (SPE) with silica cartridges of diquat, paraquat and difenzoquat in water is developed. Conditions for extraction are optimised with respect to pH, cationic surfactant and its concentration. Humic acids, anionic surfactants, inorganic salts and other organic contaminants like pesticides, phenols, polycyclic aromatic hydrocarbons and polychlorinated biphenyls produce the studied interferences. The best performance is shown in the improvement of the "quats" recovery from waters with high levels of humic acids and anionic surfactants (recovery is increased from ca. 30% to more than 80%). Unfortunately, the strong interference from inorganic salts remains. The presence in the water sample of other organic contaminants only affected the extraction efficiency of difenzoquat at high concentrations (more than 1 mg/l). Analytic utility is illustrated by selective measurements of the three herbicides, in real water samples. Overall, the results show that in spite of its drawbacks, SPE is a useful technique that allows the detection and quantification of the "quats" at limits below 100 ng/l as established by the European Union.

Aluminum Chloride↗
PubMed1997

[Preventive treatment of nonrheumatic atrial fibrillation: from the efficacy of clinical trials to the effectiveness of clinical practice].

OBJECTIVES: To know the percentage of patients with nonrheumatic atrial fibrillation treated with anticoagulants as an approach to the effectiveness of the prophylactic treatment of stroke. DESIGN: Multicenter observational study. SETTING: Six primary health centers from Barcelona. PARTICIPANTS: 465 patients with the diagnosed of AF were selected during the second semester of 1996. Patients that had suffered a hemorrhagic stroke, or with mitral stenosis, or with a prosthetic valve, or had hyperthyroidism, or receiving anticoagulant therapy were excluded. MEASUREMENTS AND MAIN RESULTS: 299 patients (64%) were finally included for the analysis. 15.8% of the patients were treated with acenocoumarin, and 35.4% were treated with aspirin. The percentage of patients treated improved for high risk patients (higher than 50%). CONCLUSIONS: The percentage of patients with nonrheumatic AF treated with acenocoumarin or aspirin is low, and physicians might be reluctant to use them because of bleeding complications, compliance with the treatment, or problems of accessibility.

Acenocoumarol↗
PubMed1997

A ColE1-type plasmid from Salmonella enteritidis encodes a DNA cytosine methyltransferase.

The multicopy plasmid pFM366 was isolated from a virulent Salmonella enteritidis strain and was found to code for DNA methylase activity (Ibáñez and Rotger, 1993). The present work was aimed at characterizing the genetic organization and functional features of this 5.6 kb plasmid. We found pFM366 almost identical to the plasmid P4 isolated from Shigella sonnei, that encodes the SsoII restriction-modification system (Karyagina et al., 1993), and related to other ColE1-type plasmids. Examination of these plasmids revealed a common organization which suggests they were the result of similar recombinational events. The cytosine methylase of pFM366 is nearly identical to M. SsoII, whereas the gene encoding the restrictase homologous to R. SsoII is truncated and its product is inactive. The expression of the cytosine methylase encoded by pFM366 is strongly affected by deletion of regions located upstream and downstream of its ORF, and is negatively controlled by the rpoS gene in Escherichia coli. The methylase activity encoded by pFM366 induces the SOS response, which could be responsible for the observed delay in the growth of E. coli.

Amino Acid Sequence↗
PubMed1997

Genetic map of the virulence plasmid of Salmonella enteritidis and nucleotide sequence of its replicons.

Partial sequencing of a genomic library of the virulence plasmid of Salmonella enteritidis has been used to localize in the restriction map of this plasmid the genetic loci already described in other Salmonella plasmids. The comparison of the vestigial tra region with the corresponding genes in the F plasmid allowed us to define the extent of the deletions that the S. enteritidis plasmid should have suffered. The putative replicons of the plasmid, repB and repC, were isolated and both proved to be functional in Escherichia coli, but repC was segregationally unstable. The nucleotide sequence of repB showed the typical organization of RepFIIA replicons, although the similarity was lower than usual in this group of replicons. The highest homology was found with the replicon of the virulence plasmid pYVe439-80 from Yersinia enterocolitica (72.5%). Replicon repC also showed a maximum identity of 72.6% with known replicons, namely the RepFIB of pColV-K30 and P307, both virulence plasmids isolated from E. coli. We conclude that the S. enteritidis plasmid could arise from the S. typhimurium plasmid through deletions, and that they are evolutionary distant from other IncFI and IncFII plasmids.

Amino Acid Sequence↗
PubMed1996

Spermidine-condensed DNA and cone-shaped lipids improve delivery and expression of exogenous DNA transfer by liposomes.

A new liposome system containing spermidine-condensed DNA and negative cone-forming lipids designed to improve gene delivery and expression is described. The compacted nature of condensed DNA forms permitted a higher extent of encapsulation of DNA in liposomes. These vesicles contained fusogenic cone-shaped lipids to increase fusion between liposomes and membranes to enhance the amount of DNA delivery into the cells. In addition, the insensitivity of condensed DNA forms to endonucleases and restriction enzymes, as well as their higher activity in both replication and transcription, improve foreign DNA expression. These improvements in condensed DNA encapsulation in liposomes, transfer into the cells, and DNA expression increase the number of transfected cells and produce a higher level of gene expression in most transfected cells. This is reflected in the 60-fold cell culture transfection increase compared with traditional liposome transfection systems. This liposome system does not cause any apparent damage to the transfected cells; furthermore, the liposomes are small, 400-500 nm, and have negative surface charges that can prolong their circulation half-lives in vivo, permitting their use for in vivo gene therapy applications.

Animals↗
PubMed1996

[Survival in patients with sick sinus syndrome and artificial pacemaker. Determining clinical factors].

INTRODUCTION AND OBJECTIVE: The hypothesis that ventricular pacing is the most important factor in the survival of patients with Sick Sinus Syndrome remains controversial. The aim of this report was to determine independent clinical variables to predict survival in paced SSS patients. METHODS: Retrospective, nonrandomized study of 153 patients with a mean age of 69 +/- 11 years, who received an initial pacemaker for Sick Sinus Syndrome between 1980 and 1994: 65 physiologic pacing (32 dual chamber, 33 atrial) and 88 ventricular pacing mode. After a maximum follow up of 177 months (median 57 months) the end point was total mortality. RESULTS: Total mortality was 21%. Using univariate analysis, single chamber ventricular pacing, age > or = 70 years and NYHA > or = 2, was associated with a higher risk for total mortality (4 times increased risk for ventricular pacing compared to other pacing modalities). Independent predictors using multivariate analysis were: 1) NYHA > or = 2 (p < 0.05). 2) Coronary artery disease (p < 0.01). 3) Chronic obstructive pulmonary disease (p < 0.05) and 4) Gender (p < 0.05). CONCLUSIONS: Mortality in patients with the Sick Sinus Syndrome is strongly predicted by preimplant baseline clinical variables. Our data indicate that the role of ventricular pacing mode remains inconclusive. A large, randomized study is necessary to confirm these results.

Age Factors↗
PubMed1994

Transbilayer diffusion of divalent cations into liposomes mediated by lipidic particles of phosphatidate.

Liposomes formed from egg-yolk phosphatidylcholine:egg-yolk phosphatidate (molar ratio 2:1) containing pBR322 DNA and DNase I were induced to form, with divalent cations, bilayer/nonbilayer phase transitions of phosphatidate which allowed cation diffusion into liposomes; then cation diffusion was measured by the activation of the hydrolysis of DNase I on DNA. The formation of phosphatidate transitions on liposomes was demonstrated by freeze-fracture and 31P NMR, and a direct correlation between the formation of phosphatidate transitions and the transbilayer diffusion of cations was found: only Ca2+ and Mn2+, which induce phase transitions, were able to penetrate liposomes and triggered the DNase I activity; in addition, Ca2+ at higher concentrations (10 mM) caused fusion of liposomes, whereas Mn2+ did not, suggesting that transitions induced by Mn2+ participated only in the diffusion of this ion; furthermore, Mg2+ neither formed phase transitions nor triggered the enzymatic activity. The liposomes studied represent more dynamic structures that can form phosphatidate structures involved in both (1) the interchange of divalent cations with the surroundings, thereby modulating encapsulated enzymes, and (2) the fusion of lipid vesicles probably implicated in the enrichment of liposomal content in the early Precambian Earth.

Cations↗
PubMed1993

Characterization of a small cryptic plasmid from Salmonella enteritidis that affects the growth of Escherichia coli.

We examined the plasmid content of 25 clinical isolates of Salmonella enteritidis, and detected the presence of small plasmids (3-5.3 kb) in 9 of them, alone, or in addition to the large, so-called virulence plasmid. A 5.3-kb plasmid isolated as unique extrachromosomal DNA from a strain responsible for a high-mortality outbreak was characterized by restriction mapping and cloning. The plasmid replicon was localized in a 1.7-kb fragment, that hybridized with three of the small plasmids detected in S. enteritidis, and with another small plasmid from Salmonella typhimurium. A strain of Escherichia coli carrying this plasmid, or a cloned 3.7-kb PvuII restriction fragment, showed a slower growth rate, especially in minimal medium, as well as a noticeable increase in DNA methyltransferase activity.

Blotting, Southern↗
PubMed1993

[Frequency of platelet alloantigens in the Spanish population].

PURPOSE: The aim of this study is to investigate the distribution and incidence of platelet alloantigens in Spain and to compare this frequency with that found in other populations. MATERIAL AND METHODS: Five hundred blood donors were phenotyped for the HPA-1a (Zwa), HPA-3a (Bak(a)), HPA-4a (Yukb/Pen(a)) y HPA-4b (Yuk(a)). One hundred of these donors were also phenotyped for the HPA-5a (Br(a)) antigen. Furthermore, we also phenotyped a group of 50 black individuals from a community of west African immigrants who live in the province of Barcelona. The typing of all the antigens except those of the HPA-5 system was carried out using the technique of Indirect Immunofluorescence. To type the antigens of the HPA-5 system the MAIPA technique was employed. RESULTS AND CONCLUSIONS: The incidence of the different platelet specific antigens in the Spanish population is, in general, the same as that detected in the other European countries and in the white population of the USA. In Europe and North America, the HPA-1a antigen is the most important of all owing to its involvement in alloimmune clinical disorders. In Asia, this role seems to be played by the HPA-4b antigen. Moreover, polymorphism for the HPA-1a allele does not seem to exist. The incidence of the HPA-5b (Br(a)) antigen in Spain, which is higher than that for France and Germany, suggests a high involvement of this antigen in our country in different alloimmune processes. The preliminary data obtained in a group of black west Africans suggest the absence on polymorphism for the HPA-1a allele and that the incidence of the remaining antigens is comparable to that of the Spanish population.

Africa, Western↗
PubMed1993

[Left ventricular outflow obstruction due to accessory mitral tissue].

An asymptomatic 31-year-old woman was studied because she presented a systolic ejection cardiac murmur. The echocardiogram showed a mobile, sac-like mass attached to the ventricular surface of the anterior mitral leaflet and its chordae tendineae and papillary muscle. This structure moved to the left ventricular outflow tract during every systole occupying the subaortic area. Conventional and color-coded Doppler examination revealed left ventricular outflow obstruction caused by the accessory mitral valve tissue that produced a high-velocity turbulent flow pattern in the subaortic area where the sac-like structure approximated to the outflow tract walls.

Adult↗
PubMed1990

Diffusion of Mn2+ ions into liposomes mediated by phosphatidate and monitored by the activation of an encapsulated enzymatic system.

Transbilayer diffusion of Mn2+ ions occurred in liposomes formed from dipalmitoyl-phosphatidylcholine or egg-yolk phosphatidylcholine and egg-yolk phosphatidate (molar ratio 2:1) containing DNA and DNase I within their aqueous compartments. Cation diffusion was demonstrated by the hydrolytic activity of DNase I, activated by the Mn2+ ions that diffused into the vesicles, and this was confirmed by light scattering. Phosphatidate, a cone-shaped lipid which has been synthesized under simulated prebiotic conditions, was necessary for cation diffusion across the liposome membranes. Such liposomes represent a simple precellular system that interchanges cations with the surroundings and provides a microenvironment for enzymatic reactions, as evidenced by the hydrolysis of DNA by DNase I inside these closed lipid compartments.

Cations↗
PubMedDate not supplied

Possible prebiotic significance of polyamines in the condensation, protection, encapsulation, and biological properties of DNA.

Some properties of DNA condensed with spermidine have been compared with the properties of DNA condensed with Co3+(NH3)6 to determine whether condensation of DNA with these trivalent cations protects DNA against the action of DNase I and increases transcription and encapsulation of DNA into liposomes. It was shown that DNA condensed with Co3+(NH3)6 was resistant to the action of the endonuclease DNase I such as DNA condensed with spermidine was. However, DNA condensed with Co3+(NH3)6 was significantly less active in transcription with the E. coli RNA polymerase than DNA-spermidine condensed forms. In addition, it was demonstrated that both compacted forms of DNA were more efficiently encapsulated into neutral liposomes; however, negatively, charged liposomes were scarcely formed in the presence of DNA condensed with Co3+(NH3)6. These experiments and the well documented properties of polyamines increasing the resistance to radiations and hydrolysis of nucleic acids, as well as their biological activities, such as replication, transcription, and translation, together with the low concentration of Co3+ in the environment, lead us to propose spermidine as a plausible prebiotic DNA condensing agent rather than Co3+ and the basic proteins proposed by other authors. Then, we consider the possible role and relevance of the polyamine-nucleic acids complexes in the evolution of life.

Animals↗
PubMedDate not supplied

Baker's asthma in a child.

BACKGROUND: baker's asthma is a well-known occupational lung disease which usually develops in adults. We report the case of a two years old boy who suffered from asthma, urticaria and atopic dermatitis for twelve months, whose symptoms were associated to visits to his grandfather's bakery. METHODS AND RESULTS: skin prick tests (SPT) were made to dust mites, moulds, flours, alfa-amylase and egg. It was also determined total IgE and specific IgE antibodies to alfa-amylase and flours. Subsequently, a challenge test was carried out with wheat flour. The SPTs were positive to flours, alfa-amylase and egg. The determination of specific IgE antibodies showed 2.64 kU/L to wheat, 0.79 kU/L to glyadin and 2.98 kU/L to alfa-amylase. The patient developed asthma and rhinitis after manipulating wheat flour for 10 min. CONCLUSIONS: we demonstrated a type I hypersensitivity to wheat flour and alfa-amylase in a two years old child by SPT, specific IgE antibodies and challenge test. This case in the childhood equivalent of occupational baker's asthma.

Angioedema↗
PubMedDate not supplied

Identification of phosphatidate nonlamellar phases on liposomes by flow cytometry.

This study is the first report that demonstrates nonlamellar arrangements, or lipidic particles, of phosphatidate inserted in the lipid bilayer of liposomes using polyclonal antibodies from mice and flow cytometry. Sera immunoreactivity was analyzed using liposomes that displayed smooth bilayers of phosphatidate particles, as shown by electron microscopy. This cytofluorimetric analysis showed that immune mice sera have a specific immunoreactivity with the phosphatide particles formed by Mn2+, which also cross-reacted with those formed by Ca2+ and with cardiolipin particles formed by Mn2+. In addition, these immune sera hardly reacted with smooth bilayered liposomes, independently of the lipid composition studied. Thus, this new methodology can be applied to demonstrate nonlamellar molecular arrangements in biological membranes.

Animals↗