Arginina, óxido nítrico y función endotelial

Arginine is a semi-essential amino acid with major physiological functions. One of the most outstanding of such is itsrole as an amino acid precursor of nitric oxide, a molecule produced, in many tissues, from arginine by the nitric oxidesynthase enzyme. Within the vascular endothelium, nitric oxide behaves as a vasodilator, antiatherogenic, and anti-plaqueaggregation agent. The detailed study of this enzymatic reaction indicates that nitric oxide synthase presents high affinity,for its substrate, arginine, which is found in high concentrations in the endothelium. Consequently, it is surprising thatthe functionality of this enzyme is conditioned by variations in concentrations of arginine, produced by nutritional intake.This is known as «the arginine paradox». However, the existence of an endogenous nitric oxide synthase inhibitor,known as asymmetric dimethylarginine, has been recently demonstrated. This compound would decrease the formationof nitric oxide through competitive inhibition with the natural substrate, arginine. It is for this reason that dietarysupplementation with arginine would be important as a means to counteracting such an effect. In addition to arginine,there are other dietary components which may also influence the synthesis of nitric oxide by the vascular endothelium.La arginina es un aminoácido semiesencial con importantes funciones fisiológicas. Entre ellas destaca su papel comoprecursora del óxido nítrico, una molécula producida a partir de la arginina por la enzima óxido nítrico sintasa enmuchos tejidos y que en el endotelio vascular se comporta como vasodilatadora, antiaterogénica y antiagreganteplaquetaria. El estudio detallado de esta reacción enzimática indica que la óxido nítrico sintasa tiene una granafinidad por su sustrato, la arginina, que se encuentra en concentraciones altas en el endotelio. Por tanto, resultabasorprendente que el funcionamiento de esta enzima estuviera condicionado por las variaciones en las concentracionesde arginina debidas al aporte nutricional. A esto se le llamó «paradoja de la arginina». Sin embargo, se hademostrado recientemente la existencia de un inhibidor endógeno de la óxido nítrico sintasa denominado dimetilargininaasimétrica. Este compuesto disminuiría la formación del óxido nítrico por inhibición competitiva con el sustratonatural, la arginina. De ahí la importancia de la suplementación con arginina para contrarrestar este efecto. Ademásde la arginina, existen otros componentes de la dieta que pueden influir también en la síntesis de óxido nítrico porel endotelio vascular

Medical treatment of benign prostatic hyperplasia

La hiperplasia benigna de próstata es un aumento del tamaño de la glándula de carácter no maligno, muy corriente entre los hombres de más de sesenta años, que produce problemas en la micción. También existen problemas irritativos por aumento del tono del músculo prostático liso y del cuello vesical a través de receptores alfa-l . Para combatir el aumento del tamaño de la glándula se utiliza la supresión androgénica mientras que los fenómenos irritativos se tratan con bloqueantes alfa-I-adrenérgicos. Dentro del primer grupo, en la actualidad se utiliza una inhibidor de la 5-alfa reductasa, la finasterida, que impide la fonnación de dihidrotestosterona, que es la fonna honnonal activa en la próstata. Dentro del segundo grupo, se utiliza modernamente la alfuzosina, que es un inhibidor bastante específico de los receptores del tracto genitourinario.Benign prostatic hyperplasia is a nonmalignant enlargement of the pros tate. This condition is very common in men over sixty years of age and causes bladder outflow osbstrucion. There are also irritative symptomes produced by urethral hypertonia of neurologycal origin through alpha-l-adrenergic receptors. Androgenic suppressión is used to treat the enlargement of the prostate whereas irritative symptomes are treated with alpha-I-adrenoreceptor antagonists. Finasteride blocks the conversión of testosterone to dihydrotestosterone, which is the active fonn of the honnone in the pros tate. Alfuzosin is an alpha-l-adrenoreceptor antagonist in the genitourinary tract

Patología molecular de las HDL

Aunque existe una considerable evidencia epidemiológica sobre el carácter ateroprotector de las HDL, se conocenmuy pocas alteraciones genéticas que expliquen los bajos niveles plasmáticos de las HDL que suponen riesgo aterosclerótico.Se sabe, no obstante, que algunas de estas alteraciones afectan a la estructura de las HDL: deficiencia de apoA-I,producción de apoA-I anormales y deficiencia de apoA-II. Otras alteraciones genéticas afectan al metabolismo de lasHDL. Las deficiencias de la lipasa hepática o de la CETP originan aumentos de las HDL mientras que las deficienciasde la lipoproteín lipasa o la LCAT se traducen en un descenso. También disminuyen los niveles de HDL en laenfermedad de Tangier ya que estas lipoproteínas se captan y se degradan de forma excesiva por los macrófagos

Adaptación metabólica de la corteza renal al ejercicio

AGRADECIMIENTOS Quiero expresar mi más profundo agradecimiento al Profesor Federico Mayor Zaragoza, Director del Departamento de Bioquímica de la Universidad de Granada cuando se iniciaron estos trabajos, que orientó y alentó desde el principio. Esta investigación ha sido financiada en parte por una Ayuda de la Comisión Asesora de Investigación Científica y Técnica y por varias Becas de Formación del Personal Investigador del Ministerio de Educación y Ciencia.Se ha encontrado un aumento en la actividad de la fosfoenolpiruvato carboxicinasa y las actividades amoniogénica y gluconeogénica renales en ratas durante el ejercicio (natación en agua a 22°C) que parece estar vinculado a la acidosis láctiea eoncom!tante a la actividad metabólica muscular. En estas condiciones, el funcionamiento coordinado de amoniogénesis y gluconeogénesis resulta crucial desde un punto de vista fisiológico ya que contribuye a la restauración del equilibrio ácido-básico alterado por la acumulación de lactato en sangre, mientras que el propio lactato puede ser reconvertido en glucosa y utilizado ulteriormente por el músculo.We have found an lnerease in the activities of rat kidney phosphoenolpyruvate carboxykinase, ammoniag,ammoniagnesis and gluconeogenesis during exer,cise (swimming in water at 22°C whi<ch seems to be related to the con(\')mmitant metaboUc acid· osis. In these conditions, the coordinate operation of ammoniagenesis and gluconeogenesis is important from a Physiologycal standpoint. First, it contributes to the l'estoration of thc acid-base balance altel'ed by accumulation of blood lactate. Also, the carbon skeleton of lactate can be re,eonverted to glucose and used again by the muscle as a metabolic fuel

Confirmation of symmetrical distributions of clinical attachment loss and tooth loss in a homogeneous Mexican adult male population

Background/purpose To ascertain whether or not clinical attachment loss and tooth loss are present with similar severity and prevalence across the two sides of the mouth in a homogeneous sample of urban male adults. Materials and methods A cross-sectional study was carried out on 161 policemen (a largely homogeneous group in terms of ethnic background, socioeconomic status, sex, occupation, and medical/dental insurance) in Campeche, Mexico. Periodontal examinations were undertaken using the Florida Probe System in a dental chair by one trained and standardized examiner (kappa ≥ 0.60) to determine clinical attachment loss and tooth loss. We examined six sites in all teeth present in the mouth (a maximum of 168 sites, no third molars). Because of correlated data between observations, McNemar (for tooth loss) and Wilcoxon (for attachment loss) signed-rank tests were used to compare right and left sites within the same patient. Results The mean age was 38.4 ± 11.0 years. The mean number of teeth present was 24.4 ± 4.6; the mean number of periodontal sites/person was 146.7 ± 27.8. All P values were ≥ 0.05 (except for attachment loss in the upper first premolars), suggesting that there were no statistically significant differences between the right and left sides for the frequency of presentation of these two conditions. Conclusion Tooth loss and attachment loss measurements largely resemble each other on both sides of the mouth

Algunos efectos metabólicos de la sustitución de proteínas por grasa en la dieta para truchas

Se han estudiado en truchas arco aris (Salmo gairdneri), los efectos que sobre la gluconeogénesis hepática, tiene el cambio de los porcentajes proteico y lipídico de la dieta y la inserción de cortos periodos de ayuno. La reducción del nivel proteico conlleva una disminución de la gluconeogénesis a partir de aminoácidos como lo n:!l.!estran las actividades de PEPCK y FDP-asa determinadas. La actividad transaminásica hepática durante los periodos de alimentación refleja la intensidad del anabolismo proteico, mientras que durante el ayuno dicha actividad está condicionada por el grado de catabolismo de los aminoácidos. La gluconeogénesis a partir de lactato no parece ser importante en condiciones de reposo muscular, al menos.The effects of diets with differents protein and fat levels on gluconeogenesis in rainbow trout (Salmo gairdneri) were studied. The insertion of short fasting periods was also considered. Reduction of protein level of the diet was accomplished to a reduced rate of gluconeogenesis as the lower activíties of PEPCK and FDP-ase have pointed out. During feeding periods the activity of liver transaminases studied reflects the intensity of protein anabolism, whereas during fasting periods, these activities are determined by the aminoacids catabolism rateo Gluconeogenesis from lactate seems to be a process of less importance, at least in muscular resting conditions

Stain-free detection as loading control alternative to Ponceau and housekeeping protein immunodetection in Western blotting

The authors want to thank the input of Arnaud Remy and Enrique Orozco of Bio-Rad Laboratories. This study was supported by the Ministry of Science and Innovation (SAF2011-22922 and SAF2011-22812), and by funds from Junta de Andalucia (CTS6736 and CTS164). B. Rivero and A. Anzola were supported by fellowships of the Ministry of Education and Science of Spain and Junta de Andalucia, respectively. CIBERehd is funded by the Instituto de Salud Carlos III.It is currently a routine practice to require a measurement of a housekeeping reference, including actin, glyceraldehyde-3-phosphate dehydrogenase, β-tubulin, among others, in Western blots, as it is the rule in RNA blots. Reversible Ponceau staining has been applied successfully to check equal loading of gels. Here we test a new technique, with the Stain-Free gels from Bio-Rad, against both Ponceau staining and housekeeping protein immunodetection under different conditions. Our results show that Stain-Free gels outperform Ponceau staining and that both are more consistent than housekeeping proteins as a loading control.Spanish Government SAF2011-22922 SAF2011-22812Junta de Andalucia CTS6736 CTS164Instituto de Salud Carlos II

Copper(I) complexes as alternatives to iridium(III) complexes for highly efficient oxygen sensing

Cu(i) complexes outperforming Ir(iii) complexes for optical oxygen sensing are demonstrated, which creates new opportunities for low cost sensors.</p

Renormalization Group Analysis of a Quivering String Model of Posture Control

Scaling concepts and renormalization group (RG) methods are applied to a simple linear model of human posture control consisting of a trembling or quivering string subject to damping and restoring forces. The string is driven by uncorrelated white Gaussian noise intended to model the corrections of the physiological control system. We find that adding a weak quadratic nonlinearity to the posture control model opens up a rich and complicated phase space (representing the dynamics) with various non-trivial fixed points and basins of attraction. The transition from diffusive to saturated regimes of the linear model is understood as a crossover phenomenon, and the robustness of the linear model with respect to weak non-linearities is confirmed. Correlations in posture fluctuations are obtained in both the time and space domain. There is an attractive fixed point identified with falling. The scaling of the correlations in the front-back displacement, which can be measured in the laboratory, is predicted for both the large-separation (along the string) and long-time regimes of posture control.Comment: 20 pages, 13 figures, RevTeX, accepted for publication in PR

Maximum in the Middle: Nonlinear Response of Microbial Plankton to Ultraviolet Radiation and Phosphorus

The responses of heterotrophic microbial food webs (HMFW) to the joint action of abiotic stressors related to global change have been studied in an oligotrophic high-mountain lake. A 2×5 factorial design field experiment performed with large mesocosms for >2 months was used to quantify the dynamics of the entire HMFW (bacteria, heterotrophic nanoflagellates, ciliates, and viruses) after an experimental P-enrichment gradient which approximated or surpassed current atmospheric P pulses in the presence vs. absence of ultraviolet radiation. HMFW underwent a mid-term (<20 days) acute development following a noticeable unimodal response to P enrichment, which peaked at intermediate P-enrichment levels and, unexpectedly, was more accentuated under ultraviolet radiation. However, after depletion of dissolved inorganic P, the HMFW collapsed and was outcompeted by a low-diversity autotrophic compartment, which constrained the development of HMFW and caused a significant loss of functional biodiversity. The dynamics and relationships among variables, and the response patterns found, suggest the importance of biotic interactions (predation/parasitism and competition) in restricting HMFW development, in contrast to the role of abiotic factors as main drivers of autotrophic compartment. The response of HMFW may contribute to ecosystem resilience by favoring the maintenance of the peculiar paths of energy and nutrient-mobilization in these pristine ecosystems, which are vulnerable to threats by the joint action of abiotic stressors related to global change.This research was supported by Junta de Andalucía (Excelencia P07-CVI-02598 to PC, and P09-RNM-5376 to JMMS), the Spanish Ministries of Medio Ambiente, Rural y Marino (PN2009/067 to PC) and Ciencia e Innovación (GLC2008-01127/BOS and CGL2011-23681 to PC), the ERC Advanced Grant project number 250254 “MINOS” (to GB), and two Spanish government grants (to JADM and FJB)