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Biomedical subjects

S Rodríguez

Publications and source records attributed to S Rodríguez.

At least 19 recordsLinked to original sources
PubMed2006

EEG-like signals generated by a simple chaotic model based on the logistic equation.

We introduce a simple model to produce EEG-like signals. The model is based on the assumption that the number of active nerve cells that generate an electric field, at a given time, is essentially chaotic. In accordance, we use the logistic equation together with a spike-like function to simulate the neuronal activity processes. With this model, we are able to generate EEG-like patterns, with quite a short time of calculation. Real pre-recorded neuronal and simulated signals, as well as their power spectra, are compared in terms of the main conventional EEG frequency peaks.

Action Potentials↗
PubMed2006

[Learning and its difficulties].

AIMS: To review some aspects of learning and its difficulties, learning understood as meaning a process that allows the nervous system to develop, and also as acquisition and consolidation, and as a synaptic and neocortical process. Likewise, we also intend to analyse the role played by the environment as well as the relations between learning and maturing, and between learning and plasticity. It is also our aim to define learning difficulties and to discuss how they can be classified. Finally, this study also seeks to consider diagnosis and the different possibilities it may offer. DEVELOPMENT: The main issue analysed here is the diagnosis of learning disorders, which is classified as being either positive (syndromatic, topographic, aetiological) or differential; the paper also describes the ways such diagnoses can be carried out and the role played by an interdisciplinary team is underlined. CONCLUSIONS: Attention is drawn to the importance of this subject owing to the large numbers of children who visit a specialist because of a possible learning disorder. At the same time we also highlight the fact that the members of the team that study these children will need to have a sound and comprehensive training because of the many pathologies that may be at play. Lastly, we discuss the need to conduct this research to resolve certain aspects that are not well understood.

Child↗
PubMed2006

First Spanish series of intestinal transplantation in adult recipients.

BACKGROUND: short-bowel transplantation has experienced a substantial growth worldwide following improved results from the late 1990's on, and its coverage by Medicare. According to the International Registry (1985-2005), a total of 1,292 intestinal transplants for 1,210 patients in 65 hospitals across 20 countries have been carried out thus far. OBJECTIVE: to know short-term (6 months) results regarding patient and graft survival from the first Spanish series of intestinal transplants in adult recipients. MATERIAL AND METHODS: we present our experience in the assessment of 20 potential candidates to short-bowel transplantation between June 2004 and October 2005. Of these, 10 patients were rejected and 4 were transplanted, which makes up the sample of our study. RESULTS: to this date 5 transplants have been carried out in 4 patients (2 retransplants, 2 desmoid tumors, 1 short bowel syndrome after excision as a result of mesenteric ischemia). Upon study completion and after a mean follow-up of 180 days (range 90-190 days) all recipients are alive, and all grafts but one (75%) are fully operational, with complete digestive autonomy. All patients received induction with alemtuzumab except one, who received thymoglobulin; in all induction was initiated with no steroids. CONCLUSIONS: intestinal transplantation represents a therapeutic option that is applicable in our setting and valid for recipients with an indication who have no other feasible alternative to keep their intestinal failure under control.

Adult↗
PubMed2005

Further studies on a mixture of fatty acids from sugar cane (Saccharum officinarum) wax oil in animal models of hypersensitivity.

A mixture of fatty acids obtained from sugar cane wax oil, the main components of which are palmitic, oleic, linoleic and linolenic acids, was evaluated topically in two experimental models of hypersensitivity: the ear swelling response to ovalbumin in sensitized mice (ED50 edema: 0.63 +/- 0.06 mg/ear, ED50 myeloperoxidase: 0.56 +/- 0.04 mg/ear, ED50 degranulated cells: 0.70 +/- 0,08 mg/ear) and oxazolone-induced contact hypersensitivity in mice (ED50 edema: 1.63 +/- 0.26 mg/ear, ED50 myeloperoxidase: 1.50 +/- 0.28 mg/ear, ED50 degranulated cells: 1.69 +/- 0.08 mg/ear). Also, the effect of this mixture was studied on the chemotaxis induced by fmlp (ED50: 25 +/- 3 microg/mL). The mixture showed anti-inflammatory activity in both in vivo models of allergy and in the chemotaxis test. Therefore, these results provide evidence about the potential usefulness of the mixture of fatty acids from sugar cane wax oil in cutaneous inflammatory and allergic disorders.

Animals↗
PubMed2005

Molecular typing of Mycobacterium avium subspecies paratuberculosis strains from different hosts and regions.

The IS1311 polymerase chain reaction-restriction endonuclease analysis was used to detect genetic differences among 38 Mycobacterium avium subsp. paratuberculosis (Map) isolates from cattle, sheep, goats and bison from distinct regions of Spain, India and the United States of America (USA). In Spain, all eight bovine isolates, three out of six caprine isolates and one of ten ovine isolates were of the C type, while the other nine ovine isolates and three caprine isolates were of the S type. In India, all five ovine isolates and six caprine isolates were of the B type, and so were all three isolates from bison (Bison bison) from the USA. These results show that there are genetic differences between Map isolates related to geographic and host factors that have a potential use in the epidemiological tracing of new paratuberculosis isolates.

Animals↗
PubMed2004

Levels of particulate matter in rural, urban and industrial sites in Spain.

This paper summarises the results of a series of studies on the interpretation of time series of levels of total suspended particles (TSP) and particulate matter (PM, <10 microm) in six regions of Spain in the period 1996-2000. In addition to the local pollution events, high PM10 episodes are recorded during African dust outbreaks, regional atmospheric recirculation events (mainly in spring to autumn), and to a lesser extent, under the influence of European and Mediterranean long range transported air masses. The lowest PM10 levels are usually recorded under Atlantic air mass advective conditions. All these regional and large-scale processes account for the relatively high PM10 levels recorded in regional background stations in Spain. Thus, the PM10 levels recorded at EMEP (Cooperative Program for Monitoring and Evaluation of the Long Range Transmission of Air Pollutants in Europe) regional background stations between March 2001 and March 2002 are very close to the annual limit value proposed for 2010 by the EU Air Quality Directive 1999/30/CE. Chemical data obtained for the different monitoring stations during 2001 show a high mineral load in PM10 for most of the study sites in Spain. Furthermore, a high marine aerosol load is evidenced in the Canary Islands. These mineral and marine loads are lower when considering PM2.5, but a relatively high proportion (8-21%) of mineral dust is still present.

Journal Article↗
PubMed2004

Application of the Max-Lloyd quantizer for ECG compression in diving mammals.

This article presents a practical implementation of an ECG compression algorithm using a Max-Lloyd quantizer, to optimize the low resources of an ECG acquisition and transmission system (telemetry system) for dolphins and human divers. The algorithm scheme is based on a first-order differential pulse code modulation (DPCM) and uses a Max-Lloyd quantizer to code the difference between the current and predicted samples. The use of the non-uniform quantizer instead of a uniform quantizer improves the percent root mean-square difference (PRD), thereby producing a low distortion in the reconstructed signals. Due to its low computational complexity, the compression process can be accomplished on-line during the ECG acquisition process.

Algorithms↗
PubMed2004

Therapeutic efficacy and safety of multiple intravenous infusions of infliximab in refractory ankylosing spondylitis patients with axial involvement.

OBJECTIVE: To evaluate the clinical response and safety profile of infliximab in refractory ankylosing spondylitis patients. METHODS: Patients with active ankylosing spondylitis, despite methotrexate therapy, were included in an open-label, single-centre study. Patients were given 3-5 mg/kg infliximab infusions at Weeks 0, 2, 6, and q8 etc up to Week 30, together with methotrexate at the dosage taken prior to study inclusion, and were followed-up for a 34-week period. RESULTS: Nine patients with mean age 43 years and mean disease duration 7 years, diagnosed with pure axial ankylosing spondylitis were included. Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), duration of morning stiffness, physician's global assessment of disease activity (PhGADA), visual analogue scale (VAS) pain, enthesis index, occiput-to-wall test, Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), and Bath Ankylosing Spondylitis Functional Index (BASFI) significantly improved by Week 6. No adverse events related with the drug were recorded during the 34-week follow-up period. CONCLUSION: Efficacy results are similar to those previously published. No adverse events were seen during therapy, and antinuclear antibody profiles were negative. The association of methotrexate with infliximab can improve the safety profile.

Adult↗
PubMed2003

Comparative sex pherome biosynthesis in Thaumetopoea pityocampa and T. processionea: a rationale for the phenotypic variation in the sex pherome within the genus Thaumetopoea.

The female sex pheromones of the Mediterranean processionary moths (Thaumetopoea sp.) are conjugated dienes or enynes of 16 carbon atoms with the unsaturations located at C11 and C13. To investigate the biochemical basis of this phenotypic variation, the biosynthetic pathway of T. processionea sex pheromone, a diene acetate, has been elucidated and compared to that reported for the enyne-producing species T. pityocampa. Mass labeling experiments showed that T. processionea sex pheromone is biosynthesized from palmitic acid, by subsequent (Z)-11 and (Z)-13 desaturations and final reduction and acetylation. The Pheromone Biosynthesis Activating Neuropeptide (PBAN) activates this biosynthetic pathway downstream of the dienoate intermediate. When either 11-hexadecynoic acid or (Z)-13-hexadecen-11-ynoic acid were administered to T. processionea, this species was able to produce the enyne sex pheromone of T. pityocampa upon PBAN stimulation. In contrast, T. pityocampa does not produce either 11-hexadecynyl acetate or (Z,Z)-11,13-hexadecadienyl acetate, despite having the corresponding precursors in the pheromone gland. However, both acetates are detected after administration of the corresponding alcohols. These overall results suggest that the absence of delta(11) acetylenase and the existence of an enynoate specific reductase in the diene and enyne-producing Thaumetopeae, respectively, account for the different sex pheromones produced by the two groups.

Animals↗
PubMed2003

Cellular mechanisms involved in the stenosis and obliteration of the cerebral aqueduct of hyh mutant mice developing congenital hydrocephalus.

Two phases may be recognized in the development of congenital hydrocephalus in the hyh mutant mouse. During embryonic life the detachment of the ventral ependyma is followed by a moderate hydrocephalus. During the first postnatal week the cerebral aqueduct becomes obliterated and a severe hydrocephalus develops. The aim of the present investigation was to elucidate the cellular phenomena occurring at the site of aqueduct obliteration and the probable participation of the subcommissural organ in this process. Electron microscopy, immunocytochemistry, and lectin histochemistry were used to investigate the aqueduct of normal and hydrocephalic hyh mice from embryonic day 14 (E-14) to postnatal day 7 (PN-7). In the normal hyh mouse, the aqueduct is an irregularly shaped cavity with 3 distinct regions (rostral, middle, and caudal) lined by various types of ependyma. In the hydrocephalic mouse, these 3 regions behave differently; the rostral end becomes stenosed, the middle third dilates, and the caudal end obliterates. The findings indicate that the following sequence of events lead to hydrocephalus: 1) denudation of the ventral ependyma (embryonic life); 2) denudation of dorsal ependyma and failure of the subcommissural organ to form Reissner fiber (first postnatal week); 3) obliteration of distal end of aqueduct; and 4) severe hydrocephalus. No evidence was obtained that NCAM is involved in the detachment of ependymal cells. The process of ependymal denudation would involve alterations of the surface sialoglycoproteins of the ependymal cells and the interaction of the latter with macrophages.

Aging↗
PubMed2003

[Nutritional anemia in nursing women in Costa Rica].

It is reported the prevalence, magnitude and determinant factors of nutritional anaemia in a sample of nursing women (NW), collected during the National Nutrition Survey, of Costa Rica done in 1996. Nutritional anaemia was determinate through measurements of haemoglobin, and plasma ferritin, folates, cianocobalamin and retinol. Methodologies used were cianometahaemoglobin, solid phase immunoradiometric assay, solid phase radioimmunoassay and high-pressure liquid chromatography. WHO cut-off points were used. Anaemia was present in 22.1% of the women. Iron and folate deficiency were found in 48.7 and 84.2% NW, respectively. The magnitude of anaemia was mild and iron and folate deficiencies were severe. Vitamin B12 and A deficiencies were 5.3 and 4.9%, respectively and did not represent a public health problem in this group. Prevalent deficiency was mixed (iron and folates, 46.6%) followed by exclusive folates deficiency (32%). Anaemia was caused by a combined deficiency of iron and folates (61.1%) and most iron deficiencies were accompanied by folates (92%). The logistic regression analysis demonstrated that low socio-economic level of NW and their families was the principal factor determining the appearance of nutritional anaemia, and educative interventions to the mother are possibly recommended. In conclusion anaemia in NW is a moderate health problem of nutritional type, that is more important when severe folates and iron deficiencies are present in Costa Rica. These problems have remained constant throughout the last three decades; although recently, possibly an improvement has occurred because the prevalence of neural tube defects in the infant population has reduced, maybe due to food iron and folates fortification public health policies implementation.

Adult↗
PubMed2002

Evidence for direct protein-protein interaction between members of the enterobacterial Hha/YmoA and H-NS families of proteins.

Escherichia coli nucleoid-associated H-NS protein interacts with the Hha protein, a member of a new family of global modulators that also includes the YmoA protein from Yersinia enterocolitica. This interaction has been found to be involved in the regulation of the expression of the toxin alpha-hemolysin. In this study, we further characterize the interaction between H-NS and Hha. We show that the presence of DNA in preparations of copurified His-Hha and H-NS is not directly implicated in the interaction between the proteins. The precise molecular mass of the H-NS protein retained by Hha, obtained by mass spectrometry analysis, does not show any posttranslational modification other than removal of the N-terminal Met residue. We constructed an H-NS-His recombinant protein and found that, as expected, it interacts with Hha. We used a Ni(2+)-nitrilotriacetic acid agarose method for affinity chromatography copurification of proteins to identify the H-NS protein of Y. enterocolitica. We constructed a six-His-YmoA recombinant protein derived from YmoA, the homologue of Hha in Y. enterocolitica, and found that it interacts with Y. enterocolitica H-NS. We also cloned and sequenced the hns gene of this microorganism. In the course of these experiments we found that His-YmoA can also retain H-NS from E. coli. We also found that the hns gene of Y. enterocolitica can complement an hns mutation of E. coli. Finally, we describe for the first time systematic characterization of missense mutant alleles of hha and truncated Hha' proteins, and we report a striking and previously unnoticed similarity of the Hha family of proteins to the oligomerization domain of the H-NS proteins.

Amino Acid Sequence↗
PubMed2001

Synthesis of gem-dideuterated tetradecanoic acids and their use in investigating the enzymatic transformation of (Z)-11-tetradecenoic acid into (E,E)-10,12-tetradecadienoic acid.

We report the preparation of the deuterated tetradecanoic acids [2,2,3,3-(2)H(4)]-, [2,2,3,3,10,10-(2)H(6)]-, and [2,2,3,3,13,13-(2)H(6)]-tetradecanoic acids (1, 2, and 3, respectively) and their use to investigate the mechanism of the enzymatic transformation of (Z)-11-tetradecenoic acid into (E,E)-10,12-tetradecadienoic acid. Probes 2 and 3 were prepared from intermediate ketones 7 and 10, which were transformed into the labeled bromides 17 and 18 by reduction with NaBD(4), tosylation of the resulting alcohol, replacement of the tosyloxy group by deuteride with LiAlD(4), hydrolysis, and reaction with N-bromosuccinimide. The resulting bromides were converted into the alpha-acetylenic esters 21 and 22, respectively, and the additional deuterium labels were introduced by reduction of the conjugated triple bond with Mg in deuterated methanol. The same sequence of reactions starting with 11-bromoundecane afforded 27. Saponification of the labeled esters 23, 24, and 27 gave the deuterated acids 2, 3, and 1, respectively. The results of the biochemical experiments showed that C10-H removal, but not elimination of C13-H, was sensitive to deuterium substitution in the transformation of (Z)-11-tetradecenoic acid into (E,E)-10,12-tetradecadienoic acid, which is consistent with the hypothesis that this desaturase reaction involves a first slow, C10-H bond cleavage, with probable formation of an unstable allylic intermediate, followed by a second fast C13-H bond removal and concomitant rearrangement.

Animals↗
PubMed2001

Intracellular oxidation of dipeptides. Base-promoted elimination from N-halodipeptides to 2-[N-alkyl-N-(2-N-alkylimino-2-alkyl-ethanoyl)amino]-2,2-dialkylethanoic acids.

One of the possible ways of intracellular oxidation of peptides is via the formation of the corresponding (N-X)-dipeptides, that then undergo base-promoted elimination to yield intermediate 2-[N-alkyl-N-(2-N-alkylimino-2-alkylethanoyl)amino]-2,2-dialkylethanoic acids, which subsequently hydrolyze. Such an elimination process is general-base catalyzed, with Brønsted beta values ranging from 0.26 to 0.31, which suggests an essentially constant degree of proton transfer at the TS. For (N-X)-dipeptides, the ratio k(N-Br)/k(N-Cl) ranges from 2.5 to 15, suggesting a structural dependence of the degree of N-X bond breaking at the TS. The values of beta and k(N-Br)/k(N-Cl) support a concerted asynchronous A(xh)D(H)D(N) mechanism, its TS changing from reactant-like to slightly nitrenium-like depending on the structure of the starting dipeptide. As a consequence of the antiperiplanarity requirements of the reaction, the steric interaction between the leaving group and the substituent on the C bearing the H to be eliminated controls the reaction rate. Such steric interaction is rather important, as indicated by the steric crossed-interaction coefficient (p(ssy') = 0.33). Semiempirical calculations show that bulky substituents in the vicinity of the reaction center imply additional energy requirements for the system to achieve the antiperiplanarity needed at the TS for the reaction to proceed. From the observations reported it follows that (N-X)-dipeptides lose their oxidizing power more readily than analogous (N-X)-amino acids or (N-X)-amines, opening a possible pathway to lessen intracellular halogen-based oxidative stress.

Acetates↗
PubMed2001

Functional aspects of the subcommissural organ-Reissner's fiber complex with emphasis in the clearance of brain monoamines.

Reissner's fiber (RF) extends along the cerebral aqueduct, fourth ventricle, and the entire length of the central canal of the spinal cord. It grows continuously in the caudal direction by addition of newly released glycoproteins by the subcommissural organ (SCO) to its proximal end. Several hypotheses about RF function have been advanced. One of them postulates that RF binds biogenic amines present in the CSF and clears them away. In recent years, this hypothesis has been tested in our laboratory by using several experimental protocols. Firstly, the CSF concentration of monoamines was investigated in RF-deprived rats subjected to immunological neutralization of the SCO-RF complex. Secondly, the capacity of RF to bind monoamines in vivo was studied by injecting radiolabeled serotonin or noradrenaline into the rat CSF, and by perfusing them into the CSF, during one week, using an Alzet's osmotic pump. In vitro binding studies were performed using isolated bovine RF. All the findings obtained indicate that RF binds monoamines present in the ventricular CSF and then transports them along the central canal. In the absence of RF, the CSF concentration of monoamines increases sharply.

Amino Acid Sequence↗