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Biomedical subjects

F Moreno

Publications and source records attributed to F Moreno.

At least 55 records · Page 3Linked to original sources
PubMed2003

[Extracranial and intracranial vascular abnormalities and nevus of Ota in the same family].

We present a 17 year old patient suffering from hemangioma on the left side of his face and neck. The evolution of his disease has been followed-up since he was 8 1/2 months old. His mother has nevus of Ota in the sclera and adjacent zones in both sides. At the age of 8 1/2 months, the patient had an ischemic stroke in the territory of the left middle cerebral artery during the surgical correction of the aortic arch coarctation. The conventional arteriogram performed at 10 months of life showed several malformations of the intracranial and extracranial arteries. At the age of 16 years the cutaneous hemangioma was atrophic and a new angiographic study by magnetic resonance arteriography (MRA) showed all the vascular anomalies with higher objectivity than the conventional arteriography, especially the absence of some arteries and the abnormal position of some others. Moreover it could detect the decrease of the caliber of the intracranial arteries and the disappearance of hemangiomatous malformations even though the patient had not received any treatment for the cutaneous hemangioma. We think that this syndrome, which still has no definite name, has a parallel spontaneous biological process with progressing vascular size during the first months or years of life and, later, the vessels regress slowly but progressively, leading to a small caliber or even the occlusion of the vessels of the cutaneous hemangioma and of the abnormal extracranial and intracranial arteries. At the same time, there is a slow but progressive presence of transdural collateral vascularization of the brain. We do not find any relationship between the hemangiomatous syndrome of the patient and the nevus of Ota of his mother.

Adolescent↗
PubMed2003

[Optimization of an individualized LASIK surgery. Geometric ray tracing model].

PURPOSE: To develop an objective calculation method that is able to provide a customized surgical correction that allows the patient to reach the emmetropia and the maximum visual acuity after the surgery. METHODS: The study included 187 eyes with myopia or myopic astigmatism that underwent LASIK. The optical characterization of each eye was developed by a complete theoretical model based in Le Grand eye, in which the measured values of radii and thicknesses of the different surfaces have been substituted. By means of a geometric ray tracing, the surgery has been simulated by changing the anterior corneal radius and the corneal thickness within the optical zone to obtain its influence in the ocular image and the visual acuity. We considered the surgery to be < > when the residual equivalent refraction was between 0 and +0.5 D. RESULTS: An interval for the final corneal radius is proposed for each eye in order to reach the best visual acuity (optimal interval). The position of the post-surgical radius in this interval has been related with the success of the surgical process. CONCLUSIONS: An objective method for LASIK has been proposed: i) it calculates a personalized surgical plan that allows the patient to reach the best visual quality, and ii) it can be used as a reference by the surgeon to design his nomogram and to decrease his learning curve.

Adult↗
PubMed2002

Transversal inhomogeneities in dilute vibrofluidized granular fluids.

The spontaneous symmetry breaking taking place in the direction perpendicular to the energy flux in a dilute vibrofluidized granular system is investigated, using both a hydrodynamic description and simulation methods. The latter include molecular dynamics and direct Monte Carlo simulation of the Boltzmann equation. A marginal stability analysis of the hydrodynamic equations, carried out in the WKB approximation, is shown to be in good agreement with the simulation results. The shape of the hydrodynamic profiles beyond the bifurcation is discussed.

Journal Article↗
PubMed2002

Mediator factor Med8p interacts with the hexokinase 2: implication in the glucose signalling pathway of Saccharomyces cerevisiae.

In the presence of glucose the protein hexokinase 2 (Hxk2p), normally resident in the cytosol, is translocated to the nucleus where it impairs the activation of transcription of the glucose-repressed genes HXK1, GLK1 and SUC2, and promotes the activation of transcription of the glucose-induced genes HXK2 and HXT1. Here, we demonstrate the involvement of an heptameric motif, named the MED8 site, in the direct binding of the mediator protein Med8p, either as a monomer or as a homodimer. Because this site was previously involved in the Hxk2p-dependent glucose-induced regulation of gene transcription, we tested whether Hxk2p interacts with Med8p. Our results show that Hxk2 and Med8 proteins are physically associated and that this Hxk2p-Med8p interaction is of physiological significance because both proteins have been found interacting together in a cluster with DNA fragments containing the MED8 site. We conclude that Hxk2p operates through the MED8 site, by interacting with Med8p, in the glucose signal transduction pathway of Saccharomyces cerevisiae.

DNA-Binding Proteins↗
PubMed2002

[Incidence of A1555G mutations in the mitochondrial DNA and 35delG in the GJB2 gene (connexin-26) in families with late onset non-syndromic sensorineural hearing loss from Cantabria].

INTRODUCTION: Sensorineural deafness is a very common disorder in humans, which affects approximately 10% of the population. Genetic causes are suggested to be responsible for more than half of the cases. The A1555G mutation in the mitochondrial 12S rRNA gene and the 35delG mutation in the GJB2 gene are the most common mutations for sensorineural deafness in the Spanish population. METHODS: A genetic study was carried out in order to determine the frequency of the mutations A1555G in the mitochondrial DNA and 35delG in the connexin-26 gene in 21 patients from 21 non-consanguineous unrelated families affected by late-onset bilateral non-syndromic sensorineural hearing loss from Cantabria. RESULTS: The A1555G mutation was found in 6 patients. Five of these 6 patients had been treated with aminoglycosides. In all of them the auditory impairment affected mainly the high frequencies. The 35delG mutation was not found in any of the patients. CONCLUSIONS: The A1555G mutation in the mitochondrial DNA has been found to be the most common amongst the Cantabrian population. The A1555G mutation should be suspected in those members of families affected by sensorineural hearing impairment with a maternal inheritance pattern and ototoxicity from treatment with aminoglycoside antibiotics. The 35delG mutation in the GJB2 gene does not seem to be a major cause of deafness in families with late-onset non-syndromic sensorineural hearing loss in our area.

Adolescent↗
PubMed2002

Monoclonal antibodies to amoxicillin express different idiotypes determined by anti-idiotype antibodies production.

Penicillins are beta-lactam antibiotics able to generate several antigenic determinants that are recognized by the immune system. To study the differences in the antigen binding site of two monoclonal antibodies (Mab) specific to amoxicillin, polyclonal rabbit anti-idiotypic antibodies were produced. One Mab, AO3.2 (IgG2a), specific to a structure formed by the acyl-side chain structure and a part of the nuclear region of amoxicillin. The second one, AO6.2 (IgE), is specific to the side chain of amoxicillin, although it also recognizes the side chain of other penicillins (penicillin G and ampicillin). These antibodies were used to immunize rabbits in order to produce polyclonal anti-idiotypic antibodies, which were purified in several steps by affinity chromatography. The specificity and cross-reactivity studies were made by ELISA and ELISA inhibition. The results suggest that the anti-Id antibodies produced are the internal image of the antigen, since the binding to their specific idiotype is blocked mainly by the original hapten (amoxicillin): in 98% of the cases with anti-id-1 (induced against AO3.2) and in 59% with anti-id-2 (induced against AO6.2). The absence of cross-reactivity of each anti-idiotypic antibody with the different Mabs specific to amoxicillin shows that the idiotypes induced by the same hapten have differences that are reflected by the nonrecognition of these anti-idiotypes. We conclude that such a small molecule as amoxicillin can present several antigenic determinants that induce a panel of antibody specificities especially directed against the side chain.

Amoxicillin↗
PubMed2002

Early detection of nonresponse to interferon plus ribavirin combination treatment of chronic hepatitis C.

We have investigated the value of early hepatitis C virus (HCV) RNA decline (DeltaHCV RNA) to predict response to combination therapy in 66 chronic hepatitis C patients treated with IFN-alpha2b (3 MU thrice weekly) and ribavirin (800 mg daily) for 12 months [25 sustained responders (SR) and 41 nonresponders or relapsers (NR)]. Serum HCV RNA was retrospectively measured in samples obtained at baseline and 4, 8 and 12 weeks after treatment onset, using a commercially available quantitative RT-PCR assay. At 4 weeks, serum HCV RNA had decreased a mean of 2.6 +/- 0.8 logs among SR as compared with only 0.5 +/- 0.8 logs in NR (P < 0.001), and was already undetectable (< 600 IU/mL) in 12 (48%) of the SR but in none of the NR. At 8 weeks, HCV RNA was undetectable in 21 SR and in 2 NR and mean DeltaHCV RNA were 4.2 +/- 1.3 and 0.8 +/- 1.0 logs, respectively (P < 0.001). At week 12 all SR had undetectable HCV RNA as compared with only five NR (P < 0.001). Stepwise logistic regression analysis identified DeltaHCV RNA at 12 weeks as the strongest predictor of sustained response. Receiver operating characteristic (ROC) curves of DeltaHCV RNA for sustained response prediction identified sensitivity peaks with 100% negative predictive value corresponding to DeltaHCV RNA > 1 log at 4 weeks, > 2 logs at 8 weeks and > 3 logs at 12 weeks. Our results show that early changes in the HCV RNA level may reliably identify patients having no chance of a sustained virological response during the first 3 months of combination therapy, thus providing an excellent tool for optimizing antiviral treatment of chronic hepatitis C.

Adult↗
PubMed2002

Field trial of the brucellosis fluorescence polarization assay.

Fluorescence polarization assay (FPA) is a homogeneous technique which was applied to the serological diagnosis of bovine brucellosis. Because of its simplicity and because it may be performed very rapidly, it was an ideal test to adapt to field use. The FPA was used to test cattle on six dairy farms in Baja California, Mexico. Anticoagulated blood, serum, and milk were collected from each animal. The anticoagulated blood was tested immediately on the farm while serum and milk were tested subsequently in the laboratory. Cattle on one farm (n = 140) were thought not to be infected with Brucella abortus and the other farms were thought to have high prevalence of the infection. The whole blood FPA (FPA(bld)) did not detect antibody in any of the cattle on the first premise. This finding was confirmed using a number of other serological tests, including the buffered antigen plate agglutination test, the complement fixation test, the indirect and competitive enzyme immunoassays, and the FPA using serum and milk. Cattle on the other premises (n = 1122) were tested in a similar fashion. The sensitivity of the FPA(bld), relative to the serum FPA (considered the definitive test), was 99.1% and the relative specificity of the FPA(bld) was 99.6%. These results compared favourably with those obtained using the other serological tests.

Animals↗
PubMed2002

Fluorescence polarization assay for detection of Brucella abortus antibodies in bulk tank bovine milk samples.

A simple, rapid, inexpensive fluorescence polarization assay for the detection of antibodies to Brucella abortus in bulk tank milk samples at the farm level or at dairies with a sensitivity and specificity of 100 and 95.9%, respectively, is described. The assay detects antibodies to B. abortus in 15 min by testing undiluted whey produced by chemical and physical manipulation of milk from bulk tanks. This sampling is noninvasive and therefore costs less and is less stressful than blood-based tests. The assay is specific and can detect antibodies at levels below that of the indirect enzyme immunoassay for milk and the fluorescence polarization assay for individual milk samples. Use of this test would make programs for surveillance of dairy animals and eradication of B. abortus more cost-effective.

Animals↗
PubMed2001

Hydrodynamic Maxwell demon in granular systems.

Spontaneous symmetry breaking in a vibrated system confined into two connected compartments in the absence of external fields is reported. For a small number of particles, the grains are equipartitioned, but if it is increased beyond a critical value, the number of particles in each of the compartments becomes different in the steady state, and the number of particles in one of the compartments decreases monotonically tending to a given value. This phase transition is accurately described by the hydrodynamic equations for a granular gas. The relationship with previous phenomena of phase separation in vibrofluidized granular materials is discussed.

Journal Article↗
PubMed2001

Secretion of the Escherichia coli K-12 SheA hemolysin is independent of its cytolytic activity.

The Escherichia coli K-12 sheA gene encodes a pore-forming hemolysin that is secreted to the medium by a hitherto unidentified mechanism. To study SheA secretion, we constructed fusions between SheA and the mature form of the periplasmic enzyme beta-lactamase, and performed site-directed mutagenesis on these constructs. The SheA-Bla and Bla-SheA hybrid proteins displayed hemolytic activity and were efficiently exported to the extracellular medium. Our results with mutant hybrid proteins show that secretion of SheA is independent of its cytolytic activity, that secretion is paralleled by a transient leakage of periplasmic contents to the extracellular medium, and that deletion of the 11 C-terminal residues of SheA has no effect on its secretion and cytolytic activity.

Cytotoxins↗
PubMed2001

Hydrodynamics of an open vibrated granular system.

Using the hydrodynamic description and molecular dynamics simulations, the steady state of a fluidized granular system in the presence of gravity is studied. For an open system, the density profile exhibits a maximum, while the temperature profile goes through a minimum at high altitude, beyond that the temperature increases with the height. The existence of the minimum is explained by the hydrodynamic equations if the presence of a collisionless boundary layer is taken into account. The energy dissipated by interparticle collisions is also computed. A good agreement is found between theory and simulation. The relationship with previous works is discussed.

Journal Article↗
PubMed2001

The hexokinase 2 protein regulates the expression of the GLK1, HXK1 and HXK2 genes of Saccharomyces cerevisiae.

The key glycolytic HXK2 gene, coding for the enzyme hexokinase 2 (Hxk2p), is expressed when cells of the yeast Saccharomyces cerevisiae are grown on a fermentable medium using glucose, fructose or mannose as a carbon source. After shifting the cells to a non-fermentable carbon source, the HXK2 gene is repressed and the HXK1 and GLK1 genes are rapidly de-repressed, producing the enzymes hexokinase 1 (Hxk1p) and glucokinase (Glk1p) respectively. Because the in vivo functions of the Hxk1p and Glk1p enzymes have remained a mystery so far, we have investigated this glucose-induced regulatory process. Here we demonstrate the involvement of Hxk2p in the glucose-induced repression of the HXK1 and GLK1 genes and the glucose-induced expression of the HXK2 gene. We have also demonstrated the involvement of Hxk1p as a negative factor in the expression of the GLK1 and HXK2 genes. Further experimental evidence, using mutant cells expressing a truncated version of Hxk2p unable to enter the nucleus, shows that nuclear localization of Hxk2p is necessary for glucose-induced repression signalling of the HXK1 and GLK1 genes and for glucose-induced expression of the HXK2 gene. Gel mobility-shift analysis shows that Hxk2p-mediated regulation is exerted through ERA (ethanol repression autoregulation)-like regulatory sequences present in the HXK1 and GLK1 promoters and in two downstream repressing sequences of the HXK2 gene. These findings reveal a novel mechanism of gene regulation whereby the product of a glycolytic gene, normally resident in the cytosol, interacts directly with nuclear proteins to regulate the transcription of the HXK1 and GLK1 genes and to autoregulate its own transcription.

DNA↗