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Biomedical subjects

F Moreno

Publications and source records attributed to F Moreno.

At least 19 recordsLinked to original sources
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↗
PubMed2001

Imaging and mapping protein-binding sites on DNA regulatory regions with atomic force microscopy.

Regulation of gene expression is fundamental in biological systems. A systematic search for protein binding sites in gene promoters has been done in recent years. Biochemical techniques are easy and reliable when analysing protein interactions with short pieces of DNA, but are difficult and tedious when long pieces of DNA have to be analysed. Here we propose AFM as a reliable and easy technique for identifying protein interaction sites in long DNA molecules like gene promoters. We support this idea using a well-known model: the interaction of the Pho4 protein with the PHO5 gene promoter. We have also applied the technique to demonstrate that Mig1 protein binds to two motifs in the promoter of HXK2 gene. Our results allow us to define Mig1p as a new factor probably contributing to the carbon source-dependent transcription regulation of HXK2 gene.

Amino Acid Sequence↗
PubMed2001

Mutations in a new gene encoding a protein of the hair bundle cause non-syndromic deafness at the DFNB16 locus.

Hearing impairment affects about 1 in 1,000 children at birth. Approximately 70 loci implicated in non-syndromic forms of deafness have been reported in humans and 24 causative genes have been identified (see also http://www.uia.ac.be/dnalab/hhh). We report a mouse transcript, isolated by a candidate deafness gene approach, that is expressed almost exclusively in the inner ear. Genomic analysis shows that the human ortholog STRC (so called owing to the name we have given its protein-stereocilin), which is located on chromosome 15q15, contains 29 exons encompassing approximately 19 kb. STRC is tandemly duplicated, with the coding sequence of the second copy interrupted by a stop codon in exon 20. We have identified two frameshift mutations and a large deletion in the copy containing 29 coding exons in two families affected by autosomal recessive non-syndromal sensorineural deafness linked to the DFNB16 locus. Stereocilin is made up of 1,809 amino acids, and contains a putative signal petide and several hydrophobic segments. Using immunohistolabeling, we demonstrate that, in the mouse inner ear, stereocilin is expressed only in the sensory hair cells and is associated with the stereocilia, the stiff microvilli forming the structure for mechanoreception of sound stimulation.

Amino Acid Sequence↗
PubMed2001

Solution structure of microcin J25, the single macrocyclic antimicrobial peptide from Escherichia coli.

The three-dimensional solution structure of microcin J25, the single cyclic representative of the microcin antimicrobial peptide class produced by enteric bacteria, was determined using two-dimensional 1H NMR spectroscopy and molecular modeling. This hydrophobic 21-residue peptide exhibits potent activity directed to Gram-negative bacteria. Its primary structure, cyclo(-V1GIGTPISFY10GGGAGHVPEY20F-), has been determined previously [Blond, A., Péduzzi, J., Goulard, C., Chiuchiolo, M. J., Barthélémy, M., Prigent, Y., Salomón, R.A., Farías, R.N., Moreno, F. & Rebuffat, S. (1999) Eur. J. Biochem., 259, 747-755]. Conformational parameters (3JNHCalphaH coupling constants, quantitative nuclear Overhauser enhancement data, chemical shift deviations, temperature coefficients of amide protons, NH-ND exchange rates) were obtained in methanol solution. Structural restraints consisting of 190 interproton distances inferred from NOE data, 11 phi backbone dihedral angle and 9 chi1 angle restraints derived from the coupling constants and three hydrogen bonds in agreement with the amide exchange rates were used as input for simulated annealing calculations and energy minimization in the program XPLOR. Microcin J25 adopts a well-defined compact structure consisting of a distorted antiparallel beta sheet, which is twisted and folded back on itself, thus resulting in three loops. Residues 7-10 and 17-20 form the more regular part of the beta sheet. The region encompassing residues Gly11-His16 consists of a distorted beta hairpin, which divides into two small loops and is stabilized by an inverse gamma turn and a type I' beta turn. The reversal of the chain leading to the Phe21-Pro6 loop results from a mixed beta/gamma turn. A cavity, in which the hydrophilic Ser8 side-chain is confined, is delimited by two crab pincer-like regions that comprise residues 6-8 and 18-1.

Amino Acid Sequence↗
PubMed2001

Construction and characterization of mutations at codon 751 of the Escherichia coli gyrB gene that confer resistance to the antimicrobial peptide microcin B17 and alter the activity of DNA gyrase.

Microcin B17 is a peptide antibiotic that inhibits DNA replication in Escherichia coli by targeting DNA gyrase. Previously, two independently isolated microcin B17-resistant mutants were shown to harbor the same gyrB point mutation that results in the replacement of tryptophan 751 by arginine in the GyrB polypeptide. We used site-directed mutagenesis to construct mutants in which tryptophan 751 was deleted or replaced by other amino acids. These mutants exhibit altered DNA gyrase activity and different levels of resistance to microcin B17.

Amino Acid Sequence↗
PubMed2001

The histochemical profiles of fibre types in porcine skeletal muscle.

Using a variety of histochemical methods -mATPase staining after alkaline and acid preincubations, NADH-TR and alpha-MGPDH- we have investigated the fibre types in porcine skeletal muscle. The results reveal that four major fibre types -I, IIA, IIB and II*- can be separated histochemically in Longissimus lumborum muscle of Landrace pigs. The histochemical properties of the muscle fibre type II* are very similar to that of type IIX described in other mammals. The existence of IIX fibres in pig muscle has been recently demonstrated by molecular biology techniques and our results validate the use of histochemistry (mATPase) as an easy methodology to differentiate the three fast myosins (type II fibres) in pig muscle.

Adenosine Triphosphatases↗
PubMed2001

[Study of 3 hypervariable loci in a mixed Chilean population].

BACKGROUND: Genetic markers are useful to study evolution parameters in populations and to determine kinship. AIM: To characterize three short tandem repeat loci in a sample of Chilean subjects and compare them with Caucasian and Hispanic populations. MATERIAL AND METHODS: Three hundred ninety three unrelated subjects that were sent for genetic studies from courts of justice, were studied. The loci FESFPS, F13A01 and vWA in blood samples, were typified amplifying DNA by polymerase chain reactions. RESULTS: The three studied loci were highly polymorphic. F13A01 and FESFPS were in Hardy-Weinberg genetic equilibrium. A significant excess of heterozygotes was detected for vWA locus. There were no differences in allele frequencies, according to ethnic origins of last names. Allele frequencies for F13A01 and vWA loci were similar to those of Hispanic populations of Unites States and FESFPS loci was different. CONCLUSIONS: All three loci had a high efficiency for genetic identification tests according to the estimated a priory exclusion probability.

Chi-Square Distribution↗
PubMed2000

External beam irradiation plus (192)Ir implant after breast-preserving surgery in women with early breast cancer.

PURPOSE: To provide more information for the clinician and to analyze the impact of the boost with brachytherapy on the local disease-free survival (LDFS), disease-free survival (DFS), specific overall survival (OS), and cosmesis, a retrospective study of external radiation therapy and (192)Ir implantation in early breast cancer at Institut Català d'Oncologia has been undertaken. PATIENTS AND METHODS: From 1986 to 1996, 530 patients were selected for this study with a median follow-up period of 39.5 months (range, 10-115 months). External radiation therapy (combined with brachytherapy) was administered postoperatively to the breast in all patients. Mean given dose was 48.7 Gy (range, 42-52 Gy) with external radiation therapy to the breast, and 16.8 Gy (range, 10-27 Gy) was the mean dose with brachytherapy. Variables have been tested for cosmesis. Univariate and multivariate analysis have also been carried out. RESULTS: Mean age of the patients was 54 years (range, 28-81 years). Stages were distributed as follows: 350 patients (66%) in Stage I, 173 in Stage II (32.8%), and 7 in Stage III (1.1%). Pathologic distribution was 445 patients with infiltrating ductal carcinoma (84%), 20 patients with infiltrating lobular carcinoma (4%), and 65 patients (12%) of a miscellaneous group. OS for the entire group was 89.4% and 85.9% at 5 and 7 years respectively. Probability of DFS was 81.7% and 70.1% at 5 and 7 years. The LDFS was 94.9% and 91.7% at 5 and 7 years. The MFS probability was 85.5% and 76.9% at 5 and 7 years, respectively. Univariate analysis demonstrated that age (older than 52 years), premenopausal status, moderate and high histologic grades (Grades II-III), and presence of intraductal comedocarcinoma were prognostic factors for local relapse. Multivariate analysis for local disease-free survival demonstrated that only perineural or muscular infiltration remain as prognostic factors. Tumor dose bed of 70 Gy or higher had a negative impact in breast subcutaneous fibrosis, whereas dose rate lower than 65 cGy/h was better for skin color at 2 years. CONCLUSION: We conclude that patients with early-stage breast cancer undergoing external radiotherapy and LDR brachytherapy can be effectively managed. Overall survival, long-term local control, and cosmetic control are excellent.

Adult↗
PubMed2000

Sensorineural hearing loss and Mondini dysplasia caused by a deletion at locus DFN3.

OBJECTIVE: To study a family with inner ear malformations and sensorineural hearing loss. DESIGN: Clinical, radiological, and genetic study of the members of a family with different degrees of sensorineural hearing loss. RESULTS: The males in the family manifested profound congenital hearing loss with severe inner ear malformations, while the only affected female had progressive hearing loss that had begun during puberty. Computed tomography showed inner ear malformations in both males, with enlarged internal auditory meatus and Mondini dysplasia. Genetic analysis disclosed a microdeletion at the locus DFN3 on chromosome X. CONCLUSION: A familial Mondini dysplasia is associated to a microdeletion at the deafness locus DFN3.

Adolescent↗
PubMed2000

Identification of phosphorylation sites in proteins by nanospray quadrupole ion trap mass spectrometry.

A method is described for identifying serine phosphorylation sites in proteins, based on conventional (32)P labeling followed by electrophoretic separation, 'in-gel' digestion with a protease, peptide extraction, reversed-phase high-performance liquid chromatographic separation and collection and off-line analysis of the radioactive fractions by nanospray ion trap mass spectrometry. The method was successfully applied to the identification of three phosphorylation sites in two proteins which were subjected to in vitro phosphorylation under physiological conditions. Different combinations of the various scanning modes of the ion trap, including high-resolution, multiple subfragmentation (or MS(n)) and fast scan analysis, were employed to identify the phosphopeptides, determine their sequence and localize the exact site of phosphorylation. 'Blind' fragmentation using fast scans was used to analyze a phosphopeptide which was undetectable in other scanning modes. The sequence, phosphorylation site and double cysteine modification of the potassium adduct of a peptide containing 35 residues were also determined by multiple fragmentation. The results not only support the validity of the proposed method for routine identification of phosphorylation sites, but also demonstrate the exceptional capability of off-line ion trap mass spectrometry in combination with nanospray ionization for performing very detailed studies on the structure of peptides.

Chromatography, High Pressure Liquid↗
PubMed2000

Varying incorporation of fatty acids into phospholipids from muscle, adipose and pancreatic exocrine tissues and thymocytes in adult rats fed with diets rich in different fatty acids.

Despite numerous studies, the importance which the tissue or the composition of the diet may have in the biological distribution of each fatty acid is not well known. To determine the importance of tissue origin and dietary fatty acids in the fatty acid composition of cell phospholipids, 54 male adult rats were fed isocaloric diets for one month varying only in their fatty acid compositions. The fat component of the six experimental groups was derived from olive oil, sunflower oil, fish oil, soybean oil, palmitic acid, or 82% palmitic acid plus 18% soybean oil, supplying the essential fatty acid. The fatty acid composition of phospholipids from thymocytes, pancreatic exocrine, muscle and adipose tissues was studied by gas-chromatography. The tissue of origin was a more important source of variation than diet in the fatty acid content of the cell phospholipids except for palmitic acid (16:0), eicosapentaenoic acid (20:5 n-3), and docosahexaenoic acid (22:6 n-3). This study points out the complexity of the interrelations between different families of fatty acids and of the specificity of each tissue to changes in the composition of dietary fatty acids, as well as the inconvenience of speaking from the dietary point of view of groups of fatty acid families based on the position of the double bond, since their individual behaviour, including saturated fatty acids, is very different in the face of dietary manipulation. The study also highlights the different behaviour of each of the fatty acids in relation to the others in the diet in each of the tissues, a circumstance which should be taken into account when evaluating the biological effects in both epidemiological and experimental studies.

Adipose Tissue↗
PubMed2000

A 17-kDa allergen detected in pine nuts.

BACKGROUND: Few cases of allergy to pine nuts have been described. We report a case of anaphylactic reaction to pine nuts. The patient needed to be treated in the emergency room due to a systemic reaction immediately after eating pine nuts. METHODS: The patient was studied by prick tests and prick by prick tests. Specific IgE was measured by CAP and by SDS-PAGE/immunoblotting by a diffusion method. RESULTS: The patient showed positive prick by prick tests to pine nuts (12 mm of maximum wheal diameter). Specific IgE was positive (0.79 kU/l). The patient's serum recognized several proteins by immunoblot. However, a 17-kDa allergen band was detected with high intensity. This protein was found to be sensitive to reducing agents, losing its IgE-binding properties after reduction. CONCLUSIONS: The patient presented an IgE-mediated reaction and detected a 17-kDa protein from pine nuts not previously described.

Adult↗
PubMed2000

Temperature effect on muscle growth of the axial musculature of the sea bass (Dicentrarchus labrax L.).

In order to determine the temperature effect on the axial muscle growth of sea bass, a stock of larvae was subjected to the following incubation and cultivation temperatures, respectively: 15 degrees C/ambient, 15/17 degrees C, 17 degrees C/ambient and 17/17 degrees C. In all groups the cross-sectional area of white and red muscles and the number and average area of the white and red muscle fibres were quantified. Results showed that the embryonic period, pre-larval phase and the end of metamorphosis were accelerated at higher temperatures. During the endogenous feeding period, muscle growth took place by fibrillar hypertrophy, and was not influenced by the temperature. Thereafter (external feeding) muscular hyperplasia began, and growth of all the muscular parameters was favoured by the effect of high incubation and cultivation temperatures, with the latter having higher influence. High incubation temperature had an slight effect on muscle growth and body length, which was only observed from 15 days. Metamorphosis finished at 3 +/- 0.4 cm in all the larvae, but this length was earlier reached at higher temperatures. At 120 days, the largest growth was obtained in the larvae maintained at a higher temperature.

Aging↗
PubMed2000

Boundary conditions and normal state for a vibrated granular fluid

The steady state of a fluidized granular system confined between a vibrating wall and a reflecting one is analyzed in detail. The relationship between the velocity of the wall and the hydrodynamic profiles is established. In the limit of a large system, a peculiar normal state, independent of the details of the boundaries, is reached in the bulk. This state has a uniform pressure and a constant temperature gradient. Both quantities are not independent, but verify a closed constitutive relationship. The generality of this state and the relevant role it is expected to play in the description of vibrated granular systems is discussed.

Journal Article↗