Muscle plasticity is influenced by renal function and caloric intake through the FGF23-vitamin D axis.

Skeletal muscle, the main metabolic engine in the body of vertebrates, is endowed with great plasticity. The association between skeletal muscle plasticity and two highly prevalent health problems: renal dysfunction and obesity, which share etiologic links as well as many comorbidities, is a subject of great relevance. It is important to know how these alterations impact on the structure and function of skeletal muscle because the changes in muscle phenotype have a major influence on the quality of life of the patients. This literature review aims to discuss the influence of a nontraditional axis involving kidney, bone, and muscle on skeletal muscle plasticity. In this axis, the kidneys play a role as the main site for vitamin D activation. Renal disease leads to a direct decrease in 1,25(OH)2-vitamin D, secondary to reduction in renal functional mass, and has an indirect effect, through phosphate retention, that contributes to stimulate fibroblast growth factor 23 (FGF23) secretion by bone cells. FGF23 downregulates the renal synthesis of 1,25(OH)2-vitamin D and upregulates its metabolism. Skeletal production of FGF23 is also regulated by caloric intake: it is increased in obesity and decreased by caloric restriction, and these changes impact on 1,25(OH)2-vitamin D concentrations, which are decreased in obesity and increased after caloric restriction. Thus, both phosphate retention, that develops secondary to renal failure, and caloric intake influence 1,25(OH)2-vitamin D that in turn plays a key role in muscle anabolism.

Increased 1,25(OH)2-Vitamin D Concentrations after Energy Restriction Are Associated with Changes in Skeletal Muscle Phenotype.

The influence of energy restriction (ER) on muscle is controversial, and the mechanisms are not well understood. To study the effect of ER on skeletal muscle phenotype and the influence of vitamin D, rats (n = 34) were fed a control diet or an ER diet. Muscle mass, muscle somatic index (MSI), fiber-type composition, fiber size, and metabolic activity were studied in tibialis cranialis (TC) and soleus (SOL) muscles. Plasma vitamin D metabolites and renal expression of enzymes involved in vitamin D metabolism were measured. In the ER group, muscle weight was unchanged in TC and decreased by 12% in SOL, but MSI increased in both muscles (p < 0.0001) by 55% and 36%, respectively. Histomorphometric studies showed 14% increase in the percentage of type IIA fibers and 13% reduction in type IIX fibers in TC of ER rats. Decreased size of type I fibers and reduced oxidative activity was identified in SOL of ER rats. An increase in plasma 1,25(OH)2-vitamin D (169.7 ± 6.8 vs. 85.4 ± 11.5 pg/mL, p < 0.0001) with kidney up-regulation of CYP27b1 and down-regulation of CYP24a1 was observed in ER rats. Plasma vitamin D correlated with MSI in both muscles (p < 0.001), with the percentages of type IIA and type IIX fibers in TC and with the oxidative profile in SOL. In conclusion, ER preserves skeletal muscle mass, improves contractile phenotype in phasic muscles (TC), and reduces energy expenditure in antigravity muscles (SOL). These beneficial effects are closely related to the increases in vitamin D secondary to ER.

Locomotor muscle fibre heterogeneity and metabolism in the fastest large-bodied rorqual: the fin whale (Balaenoptera physalus).

From a terrestrial ancestry, the fin whale (Balaenoptera physalus) is one of the largest animals on Earth with a sprinter anti-predator strategy, and a characteristic feeding mode, lunge feeding, which involves bouts of high-intensity muscle activity demanding high metabolic output. We investigated the locomotor muscle morphology and metabolism of this cetacean to determine whether its muscle profile (1) explains this unique swimming performance and feeding behaviour, (2) is or is not homogeneous within the muscle, and (3) predicts allometric variations inherent to an extreme body size. A predominantly fast-glycolytic phenotype characterized the fin whale locomotor muscle, composed of abundant fast-twitch (type IIA) fibres with high glycolytic potential, low oxidative capacity, relatively small size, and reduced number of capillaries. Compared with superficial areas, deep regions of this muscle exhibited a slower and more oxidative profile, suggesting a division of labour between muscle strata. As expected, the fin whale locomotor muscle only expressed the two slowest myosin heavy chain isoforms (I and IIA). However, it displayed anaerobic (glycolytic) and aerobic (lipid-based metabolism) capabilities higher than would be predicted from the allometric perspective of its extreme body size. Relationships between muscle metabolism and body mass were fibre-type specific. The 'sprinter' profile of the fin whale swimming muscle, particularly of its superficial compartment, supports physiological demands during both high-speed swimming and the lunge, when energy expenditure reaches maximal or supramaximal levels. Comparatively, the slower and more oxidative profile of the deep compartment of this muscle seems to be well designed for sustained, low-intensity muscle activity during routine swimming.

Metodología para evaluar la calidad de la formación del estudiante en la Escuela Latinoamericana de Medicina / A methodology for evaluating the quality of student training in the Latin American School of Medicine

Introducción: las demandas crecientes del entorno generan cada día nuevos retos para las Instituciones de Educación Médica Superior, comprometen a las Instituciones de Educación Médicas Superior (IEMS) al cumplimiento de los parámetros mínimos de calidad en el proceso formativo de los estudiantes en aras de asegurar el ejercicio apropiado de la Medicina. De ahí la necesidad de implementar la evaluación del proceso de formación del estudiante como una vía que contribuya a elevar su calidad. Objetivos: diseñar una metodología para evaluar la calidad de la formación del estudiante en la Escuela Latinoamericana de Medicina (ELAM). Métodos: se utilizaron como métodos teóricos el análisis-síntesis, la inducción-deducción, el histórico-lógico, el enfoque sistémico y la modelación. Como métodos empíricos, el análisis documental y de contenido, la encuesta y la consulta a expertos. Resultados: se diseñó una metodología sustentada en un conjunto de relaciones esenciales y principios, estructurada en un conjunto de fases interrelacionadas entre sí, formando una unidad orgánica, cuyos objetivos, contenido, acciones y resultados responden a las exigencias de la evaluación de la calidad de la formación del estudiante. Conclusiones: el incremento de la calidad de la formación es vista como un desafío, una necesidad y un compromiso con el que se responsabilizan los estudiantes, los profesores, directivos de la ELAM. Se valoró como viable la propuesta metodológica diseñada, al ponerse de relieve la importancia de las diferentes fases que la integran, así como la relación entre el objetivo, el contenido, las acciones y los resultados contenidos en cada una de ellas(AU)

Introduction: The growing environmental demands generate new challenges for the institutions of higher medical education. They commit institutions of higher medical education to the fulfillment of the minimum parameters of quality in the training process of the students, in order to ensure the proper medical practice. Hence the need to implement the evaluation of the student training process as a way to help raise its quality. Objective: To design a methodology for evaluating the quality of student training in the Latin American School of Medicine (ELAM). Methods: Analysis-synthesis, induction-deduction, historical-logical, systemic approach and modeling were used as theoretical methods. As empirical methods, the documentary and content analysis, the survey and the consultation of experts were used. Results: A methodology was designed based on a set of essential relationships and principles, structured in a set of interrelated phases, forming an organic unit, whose objectives, content, actions and results respond to the requirements of the evaluation of quality of the students' training. Conclusions: The increased quality of training is perceived as a challenge, a necessity and a commitment with which the students, professors, and the ELAM directors are responsible. The methodological proposal designed was evaluated as viable, highlighting the importance of the different phases that comprise it, as well as the relationship between the objective, content, actions and results contained in each one of them.(AU)

Metodología para evaluar la calidad de la formación del estudiante en la Escuela Latinoamericana de Medicina / A methodology for evaluating the quality of student training in the Latin American School of Medicine

Introducción: las demandas crecientes del entorno generan cada día nuevos retos para las Instituciones de Educación Médica Superior, comprometen a las Instituciones de Educación Médicas Superior (IEMS) al cumplimiento de los parámetros mínimos de calidad en el proceso formativo de los estudiantes en aras de asegurar el ejercicio apropiado de la Medicina. De ahí la necesidad de implementar la evaluación del proceso de formación del estudiante como una vía que contribuya a elevar su calidad. Objetivos: diseñar una metodología para evaluar la calidad de la formación del estudiante en la Escuela Latinoamericana de Medicina (ELAM). Métodos: se utilizaron como métodos teóricos el análisis-síntesis, la inducción-deducción, el histórico-lógico, el enfoque sistémico y la modelación. Como métodos empíricos, el análisis documental y de contenido, la encuesta y la consulta a expertos. Resultados: se diseñó una metodología sustentada en un conjunto de relaciones esenciales y principios, estructurada en un conjunto de fases interrelacionadas entre sí, formando una unidad orgánica, cuyos objetivos, contenido, acciones y resultados responden a las exigencias de la evaluación de la calidad de la formación del estudiante. Conclusiones: el incremento de la calidad de la formación es vista como un desafío, una necesidad y un compromiso con el que se responsabilizan los estudiantes, los profesores, directivos de la ELAM. Se valoró como viable la propuesta metodológica diseñada, al ponerse de relieve la importancia de las diferentes fases que la integran, así como la relación entre el objetivo, el contenido, las acciones y los resultados contenidos en cada una de ellas(AU)

Introduction: The growing environmental demands generate new challenges for the institutions of higher medical education. They commit institutions of higher medical education to the fulfillment of the minimum parameters of quality in the training process of the students, in order to ensure the proper medical practice. Hence the need to implement the evaluation of the student training process as a way to help raise its quality. Objective: To design a methodology for evaluating the quality of student training in the Latin American School of Medicine (ELAM). Methods: Analysis-synthesis, induction-deduction, historical-logical, systemic approach and modeling were used as theoretical methods. As empirical methods, the documentary and content analysis, the survey and the consultation of experts were used. Results: A methodology was designed based on a set of essential relationships and principles, structured in a set of interrelated phases, forming an organic unit, whose objectives, content, actions and results respond to the requirements of the evaluation of quality of the students' training. Conclusions: The increased quality of training is perceived as a challenge, a necessity and a commitment with which the students, professors, and the ELAM directors are responsible. The methodological proposal designed was evaluated as viable, highlighting the importance of the different phases that comprise it, as well as the relationship between the objective, content, actions and results contained in each one of them.(AU)

Obesity-induced discrepancy between contractile and metabolic phenotypes in slow- and fast-twitch skeletal muscles of female obese Zucker rats.

A clear picture of skeletal muscle adaptations to obesity and related comorbidities remains elusive. This study describes fiber-type characteristics (size, proportions, and oxidative enzyme activity) in two typical hindlimb muscles with opposite structure and function in an animal model of genetic obesity. Lesser fiber diameter, fiber-type composition, and histochemical succinic dehydrogenase activity (an oxidative marker) of muscle fiber types were assessed in slow (soleus)- and fast (tibialis cranialis)-twitch muscles of obese Zucker rats and compared with age (16 wk)- and sex (females)-matched lean Zucker rats (n = 16/group). Muscle mass and lesser fiber diameter were lower in both muscle types of obese compared with lean animals even though body weights were increased in the obese cohort. A faster fiber-type phenotype also occurred in slow- and fast-twitch muscles of obese rats compared with lean rats. These adaptations were accompanied by a significant increment in histochemical succinic dehydrogenase activity of slow-twitch fibers in the soleus muscle and fast-twitch fiber types in the tibialis cranialis muscle. Obesity significantly increased plasma levels of proinflammatory cytokines but did not significantly affect protein levels of peroxisome proliferator-activated receptors PPARγ or PGC1α in either muscle. These data demonstrate that, in female Zucker rats, obesity induces a reduction of muscle mass in which skeletal muscles show a diminished fiber size and a faster and more oxidative phenotype. It was noteworthy that this discrepancy in muscle's contractile and metabolic features was of comparable nature and extent in muscles with different fiber-type composition and antagonist functions.NEW & NOTEWORTHY This study demonstrates a discrepancy between morphological (reduced muscle mass), contractile (shift toward a faster phenotype), and metabolic (increased mitochondrial oxidative enzyme activity) characteristics in skeletal muscles of female Zucker fatty rats. It is noteworthy that this inconsistency was comparable (in nature and extent) in muscles with different structure and function.

Mangiferin protects against adverse skeletal muscle changes and enhances muscle oxidative capacity in obese rats.

Obesity-related skeletal muscle changes include muscle atrophy, slow-to-fast fiber-type transformation, and impaired mitochondrial oxidative capacity. These changes relate with increased risk of insulin resistance. Mangiferin, the major component of the plant Mangifera indica, is a well-known anti-inflammatory, anti-diabetic, and antihyperlipidemic agent. This study tested the hypothesis that mangiferin treatment counteracts obesity-induced fiber atrophy and slow-to-fast fiber transition, and favors an oxidative phenotype in skeletal muscle of obese rats. Obese Zucker rats were fed gelatin pellets with (15 mg/kg BW/day) or without (placebo group) mangiferin for 8 weeks. Lean Zucker rats received the same gelatin pellets without mangiferin and served as non-obese and non-diabetic controls. Lesser diameter, fiber composition, and histochemical succinic dehydrogenase activity (an oxidative marker) of myosin-based fiber-types were assessed in soleus and tibialis cranialis muscles. A multivariate discriminant analysis encompassing all fiber-type features indicated that obese rats treated with mangiferin displayed skeletal muscle phenotypes significantly different compared with both lean and obese control rats. Mangiferin significantly decreased inflammatory cytokines, preserved skeletal muscle mass, fiber cross-sectional size, and fiber-type composition, and enhanced muscle fiber oxidative capacity. These data demonstrate that mangiferin attenuated adverse skeletal muscle changes in obese rats.

Fixed-dose versus separate drug combinations for antihypertensive treatment: literature review. / Medicamentos antihipertensivos en combinación a dosis fijas versus dosis separadas: revisión de la literatura.

INTRODUCTION: Hypertension requires effective interventions to reduce cardiovascular morbidity and mortality. Drug therapies have achieved optimal blood pressure levels in affected patients. Recent clinical guidelines suggest drug combinations a fact that has led to the development of various fixed-dose combinations. OBJECTIVE: To find the best available evidence about the effectiveness of antihypertensive drugs in fixed-dose combinations compared with separate dose combinations for blood pressure control, treatment adherence and reducing cardiovascular morbidity and mortality. METHODS: Systematic literature search of the best evidence available in the following databases was performed: MEDLINE/PubMed, LILACS, Cochrane and institutional publications of WHO and PAHO. RESULTS: Two meta-analyses comparing the two combinations were found, in both studies medication compliance was evaluated, no control of blood pressure or effects on cardiovascular events was assessed. Both studies are of very low quality of evidence due to limitations in search methodology, suboptimal quality of the included studies and heterogeneity of the analyzed variables. WHO drug use policies for antihypertensive drugs do not suggest fixed-drug combinations. These combinations are not included in Chile´s national drug formulary. CONCLUSION: Well-designed studies are required to demonstrate the effectiveness of antihypertensive drugs in fixed-dose combination compared with separate dose combinations for controlling blood pressure, treatment adherence and reducing cardiovascular morbidity and mortality.

INTRODUCCIÓN: La hipertensión arterial requiere de intervenciones efectivas para reducir la morbimortalidad cardiovascular. Las terapias farmacológicas han logrado alcanzar cifras óptimas de presión arterial en los afectados. En las guías clínicas recientes se sugiere la utilización de las combinaciones de medicamentos, esto ha llevado a elaborar una diversidad de combinaciones a dosis fija. OBJETIVO: Buscar la mejor evidencia bibliográfica disponible sobre la efectividad de los medicamentos antihipertensivos en combinaciones a dosis fija, en comparación con combinaciones a dosis separadas para controlar la presión arterial, la adherencia al tratamiento y disminución de la morbimortalidad cardiovascular. MÉTODOS: Se realizó una búsqueda sistemática de literatura de las mejores evidencias disponibles en las bases de datos: MEDLINE/PubMed, LILACS, Cochrane y publicaciones institucionales de la Organización Mundial de la Salud y Organización Panamericana de la Salud. RESULTADOS: Del total de estudios encontrados, se seleccionaron dos metanálisis que compararon las dos combinaciones. En ambas se evaluó el cumplimiento de la medicación, no se evaluó el control de presión arterial o efectos en los eventos cardiovasculares. Ambos estudios son de muy baja calidad de evidencia por sus limitaciones en la búsqueda, calidad subóptima de los estudios incluidos y lo heterogéneo de las variables analizadas. En las políticas de medicamentos de la Organización Mundial de la Salud no se sugiere el uso de antihipertensivos con combinaciones a dosis fijas. En Chile no están incluidos en el formulario nacional de medicamentos. CONCLUSIÓN: Se requieren estudios bien diseñados para demostrar la efectividad de los medicamentos antihipertensivos en combinación a dosis fijas en comparación con combinaciones a dosis separadas para control de la presión arterial, la adherencia al tratamiento y disminución de la morbimortalidad cardiovascular.

High-phosphorus diet maximizes and low-dose calcitriol attenuates skeletal muscle changes in long-term uremic rats.

Although disorders of mineral metabolism and skeletal muscle are common in chronic kidney disease (CKD), their potential relationship remains unexplored. Elevations in plasma phosphate, parathyroid hormone, and fibroblastic growth factor 23 together with decreased calcitriol levels are common features of CKD. High-phosphate intake is a major contributor to progression of CKD. This study was primarily aimed to determine the influence of high-phosphate intake on muscle and to investigate whether calcitriol supplementation counteracts negative skeletal muscle changes associated with long-term uremia. Proportions and metabolic and morphological features of myosin-based muscle fiber types were assessed in the slow-twitch soleus and the fast-twitch tibialis cranialis muscles of uremic rats (5/6 nephrectomy, Nx) and compared with sham-operated (So) controls. Three groups of Nx rats received either a standard diet (0.6% phosphorus, Nx-Sd), or a high-phosphorus diet (0.9% phosphorus, Nx-Pho), or a high-phosphorus diet plus calcitriol (10 ng/kg 3 day/wk ip, Nx-Pho + Cal) for 12 wk. Two groups of So rats received either a standard diet or a high-phosphorus diet (So-Pho) over the same period. A multivariate analysis encompassing all fiber-type characteristics indicated that Nx-Pho + Cal rats displayed skeletal muscle phenotypes intermediate between Nx-Pho and So-Pho rats and that uremia-induced skeletal muscle changes were of greater magnitude in Nx-Pho than in Nx-Sd rats. In uremic rats, treatment with calcitriol preserved fiber-type composition, cross-sectional size, myonuclear domain size, oxidative capacity, and capillarity of muscle fibers. These data demonstrate that a high-phosphorus diet potentiates and low-dose calcitriol attenuates adverse skeletal muscle changes in long-term uremic rats.

Skeletal muscle adaptations and muscle genomics of performance horses.

Skeletal muscles in horses are characterised by specific adaptations, which are the result of the natural evolution of the horse as a grazing animal, centuries of selective breeding and the adaptability of this tissue in response to training. These adaptations include an increased muscle mass relative to body weight, a great locomotor efficiency based upon an admirable muscle-tendon architectural design and an adaptable fibre-type composition with intrinsic shortening velocities greater than would be predicted from an animal of comparable body size. Furthermore, equine skeletal muscles have a high mitochondrial volume that permits a higher whole animal aerobic capacity, as well as large intramuscular stores of energy substrates (glycogen in particular). Finally, high buffer and lactate transport capacities preserve muscles against fatigue during anaerobic exercise. Many of these adaptations can improve with training. The publication of the equine genome sequence in 2009 has provided a major advance towards an improved understanding of equine muscle physiology. Equine muscle genomics studies have revealed a number of genes associated with elite physical performance and have also identified changes in structural and metabolic genes following exercise and training. Genes involved in muscle growth, muscle contraction and specific metabolic pathways have been found to be functionally relevant for the early performance evaluation of elite athletic horses. The candidate genes discussed in this review are important for a healthy individual to improve performance. However, muscle performance limiting conditions are widespread in horses and many of these conditions are also genetically influenced.

Slow- and fast-twitch hindlimb skeletal muscle phenotypes 12 wk after ⠚ nephrectomy in Wistar rats of both sexes.

This study describes fiber-type adaptations in hindlimb muscles, the interaction of sex, and the role of hypoxia on this response in 12-wk ⅚ nephrectomized rats (Nx). Contractile, metabolic, and morphological features of muscle fiber types were assessed in the slow-twitch soleus and the fast-twitch tibialis cranialis muscles of Nx rats, and compared with sham-operated controls. Rats of both sexes were considered in both groups. A slow-to-fast fiber-type transformation occurred in the tibialis cranialis of Nx rats, particularly in males. This adaptation was accomplished by impaired oxidative capacity and capillarity, increased glycolytic capacity, and no changes in size and nuclear density of muscle fiber types. An oxidative-to-glycolytic metabolic transformation was also found in the soleus muscle of Nx rats. However, a modest fast-to-slow fiber-type transformation, fiber hypertrophy, and nuclear proliferation were observed in soleus muscle fibers of male, but not of female, Nx rats. Serum testosterone levels decreased by 50% in male but not in female Nx rats. Hypoxia-inducible factor-1α protein level decreased by 42% in the tibialis cranialis muscle of male Nx rats. These data demonstrate that 12 wk of Nx induces a muscle-specific adaptive response in which myofibers do not change (or enlarge minimally) in size and nuclear density, but acquire markedly different contractile and metabolic characteristics, which are accompanied by capillary rarefaction. Muscle function and sex play relevant roles in these adaptations.

Adaptive functional specialisation of architectural design and fibre type characteristics in agonist shoulder flexor muscles of the llama, Lama glama.

Like other camelids, llamas (Lama glama) have the natural ability to pace (moving ipsilateral limbs in near synchronicity). But unlike the Old World camelids (bactrian and dromedary camels), they are well adapted for pacing at slower or moderate speeds in high-altitude habitats, having been described as good climbers and used as pack animals for centuries. In order to gain insight into skeletal muscle design and to ascertain its relationship with the llama's characteristic locomotor behaviour, this study examined the correspondence between architecture and fibre types in two agonist muscles involved in shoulder flexion (M. teres major - TM and M. deltoideus, pars scapularis - DS and pars acromialis - DA). Architectural properties were found to be correlated with fibre-type characteristics both in DS (long fibres, low pinnation angle, fast-glycolytic fibre phenotype with abundant IIB fibres, small fibre size, reduced number of capillaries per fibre and low oxidative capacity) and in DA (short fibres, high pinnation angle, slow-oxidative fibre phenotype with numerous type I fibres, very sparse IIB fibres, and larger fibre size, abundant capillaries and high oxidative capacity). This correlation suggests a clear division of labour within the M. deltoideus of the llama, DS being involved in rapid flexion of the shoulder joint during the swing phase of the gait, and DA in joint stabilisation during the stance phase. However, the architectural design of the TM muscle (longer fibres and lower fibre pinnation angle) was not strictly matched with its fibre-type characteristics (very similar to those of the postural DA muscle). This unusual design suggests a dual function of the TM muscle both in active flexion of the shoulder and in passive support of the limb during the stance phase, pulling the forelimb to the trunk. This functional specialisation seems to be well suited to a quadruped species that needs to increase ipsilateral stability of the limb during the support phase of the pacing gait. Compared with other species, llama skeletal muscles are well suited for greater force generation combined with higher fatigue resistance during exercise. These characteristics are interpreted as being of high adaptive value, given the llama's habitat and its use as a pack animal.

Alterations in oxidative gene expression in equine skeletal muscle following exercise and training.

Intense selection for elite racing performance in the Thoroughbred horse (Equus caballus) has resulted in a number of adaptive physiological phenotypes relevant to exercise; however, the underlying molecular mechanisms responsible for these characteristics are not well understood. Adaptive changes in mRNA expression in equine skeletal muscle were investigated by real-time qRT-PCR for a panel of candidate exercise-response genes following a standardized incremental-step treadmill exercise test in eight untrained Thoroughbred horses. Biopsy samples were obtained from the gluteus medius before, immediately after, and 4 h after exercise. Significant (P < 0.05) differences in gene expression were detected for six genes (CKM, COX4I1, COX4I2, PDK4, PPARGC1A, and SLC2A4) 4 h after exercise. Investigation of relationships between mRNA and velocity at maximum heart rate (VHR(max)) and peak postexercise plasma lactate concentration ([La]T(1)) revealed significant (P < 0.05) associations with postexercise COX4I1 and PPARCG1A expression and between [La]T(1) and basal COX4I1 expression. Gene expression changes were investigated in a second cohort of horses after a 10 mo period of training. In resting samples, COX4I1 gene expression had significantly increased following training, and, after exercise, significant differences were identified for COX4I2, PDK4, and PPARGC1A. Significant relationships with VHR(max) and [La]T(1) were detected for PPARGC1A and COX4I1. These data highlight the roles of genes responsible for the regulation of oxygen-dependent metabolism, glucose metabolism, and fatty acid utilization in equine skeletal muscle adaptation to exercise.

A comprehensive characterisation of the fibre composition and properties of a limb (flexor digitorum superficialis, membri thoraci) and a trunk (psoas major) muscle in cattle.

BACKGROUND: The fibre type attributes and the relationships among their properties play an important role in the differences in muscle capabilities and features. Comprehensive characterisation of the skeletal muscles should study the degree of association between them and their involvement in muscle functionality. The purposes of the present study were to characterise the fibre type composition of a trunk (Psoas major, PM) and a limb (Flexor digitorum, membri thoraci, FD) muscle in the bovine species and to study the degree of coordination among contractile, metabolic and histological properties of fibre types. Immunohistochemical, histochemical and histological techniques were used. RESULTS: The fibre type composition was delineated immunohistochemically in calf muscle samples, identifying three pure (I, IIA, and IIX) and two hybrid type fibres (I+IIA, and IIAX). Most of the fibres in FD were types I and IIA, while pure IIX were absent. All fibre types were found in PM, the IIX type being the most frequent. Compared to other species, small populations of hybrid fibres were detected. The five fibre types, previously identified, were ascribed to three different acid and alkaline mATPase activity patterns. Type I fibres had the highest oxidative capacity and the lowest glycolytic capacity. The reverse was true for the IIX fibres, whereas the type IIA fibres showed intermediate properties. Regarding the histological properties, type I fibres tended to be more capillarised than the II types. Correlations among contractile, metabolic and histological features on individual fibres were significantly different from zero (r values varied between -0.31 and 0.78). Hybrid fibre values were positioned between their corresponding pure types, and their positions were different regarding their metabolic and contractile properties. CONCLUSION: Coordination among the contractile, metabolic and histological properties of fibres has been observed. However, the magnitude of the correlation among them is always below 0.8, suggesting that the properties of muscles are not fully explained by the fibre composition. These results support the concept that, to some extent, muscle plasticity can be explained by the fibre type composition, and by the properties derived from their metabolic and histological profiles.

Sistema de Información Estratégica para la toma de decisiones en el Departamento de Servicios Informáticos / Strategic Information System for decision making in the Department of Computing Services

Diseñar un Sistema de Información Estratégica para apoyar la toma de decisiones en el Departamento deServicios Informáticos. Para el logro del objetivo propuesto se recopiló información sobre la disponibilidad y necesidades del departamento,así como del nivel de satisfacción de los usuarios con los servicios informáticos ofertados. Para ello se aplicó un cuestionario a trabajadores del área, vicerrectores y jefes de los departamentos docentes, considerándose cuatro perspectivasrelacionadas con la estrategia de trabajo del departamento de Servicios Informáticos: financiera, de los beneficiarios, de los procesos internos y de aprendizaje y desarrollo. En cada una de ellas se definió un conjunto de indicadores. El Sistema confeccionado estuvo integrado por tres subsistemas que se corresponden con las diferentes áreas de trabajo del Departamento. Se relacionan entre sí y cada uno posee funciones y objetivos propios, son estos: hard y seguridad informática, red y transmisión de datos, análisis y diseño de sistemas y web. Se formuló, además, un conjunto de estrategias de apoyo al proceso de implementación del procedimiento. Se diseñó un Sistema de Información Estratégica estructurado en varios subsistemas e indicadores quemejorará los procesos de planificación, control, evaluación y toma de decisiones. Permitirá, además, una eficiente recopilación, procesamiento, difusión y actualización sistemática de la información(AU)

To design a Strategic Information System to support decision making in the Department of Computing Services.To achieve the proposed objective information was compiled about the availability and necessities of the department such as the user satisfaction levels of the computing services offered. To do so a questionnaire was given to area employees, assistant deans and chairs of academic departments, taking into account four work strategy related perspectives of the Department of Computing Services: finances of beneficiaries, internal processes and of learning and development. In each of these a group of indicators was defined. The system that was created was integrated with three subsystems that correspond with the department's different work areas. They are interrelated and each one contains their own functions and objectives, which are: Hard and computing security, networking and data transmission, system design and analysis and web. Additionally, group of proceduralimplementation support strategies were formulated. A Strategic Information System was designed structured in various subsystems and indicators that will improve the processes of planning, control, evaluation and decision making. It will also permit a systematic and efficient summarization, processing, diffusion and upgrading of information(AU)

Slow- and fast-twitch rat hind limb skeletal muscle phenotypes 8 months after spinal cord transection and olfactory ensheathing glia transplantation.

Paralysed skeletal muscle of rats with spinal cord injury (SCI) undergoes atrophy and a switch in gene expression pattern which leads to faster, more fatigable phenotypes. Olfactory ensheathing glia (OEG) transplants have been reported to promote axonal regeneration and to restore sensory-motor function in animals with SCI. We hypothesized that OEG transplants could attenuate skeletal muscle phenotypic deterioration and that this effect could underlie the functional recovery observed in behavioural tests. A variety of morphological, metabolic and molecular markers were assessed in soleus (SOL) and extensor digitorum longus (EDL) muscles of spinal cord transected (SCT), OEG-transplanted rats 8 months after the intervention and compared with non-transplanted SCT rats and sham-operated (without SCT) controls (C). A multivariate analysis encompassing all the parameters indicated that OEG-transplanted rats displayed skeletal muscle phenotypes intermediate between non-transplanted and sham-operated controls, but different from both. A high correlation was observed between behaviourally tested sensory-motor functional capacity and expression level of slow- and fast-twitch hind limb skeletal muscle phenotypic markers, particularly the histochemical glycerol-3-phosphate dehydrogenase activity (-0.843, P < 0.0001) and the fraction of variant 2s of the slow regulatory myosin light chain isoform (0.848, P < 0.0001) in SOL. Despite the mean overall effect of OEG transplants in patterning skeletal muscle protein expression towards normal, in 6 out of 9 animals they appeared insufficient to overcome fibre type switching and to support a consistent and generalized long-term maintenance of normal skeletal muscle characteristics. The interplay of OEG and exercise-mediated neurotrophic actions is a plausible mechanism underlying OEG transplantation effects on paralysed skeletal muscle.

Concordancia de los patrones de sensibilidad a drogas de primera línea en aislamientos de Mycobacterium tuberculosis entre contactos intradomiciliarios que desarrollaron tuberculosis activa y sus casos índice con tuberculosis pulmonar multidrogorresistente en una población urbana del Callao / Concordance of first-line drug-susceptibility patterns of Mycobacterium tuberculosis isolates between domiciliary contacs who develop active disease and their index cases with multidrug-resistant pulmonary tuberculosis in an urban population of Callao

La tuberculosis (TB) pulmonar multidrogorresistente (MDR) constituye un problema de salud pública debido a lo complicado del tratamiento y sus tasas de cura menores que la TB Sensible. Un aspecto adicional estß constituido por el manejo de los contactos que desarrollan enfermedad (casos secundarios) y en quienes no se puede precisar el tipo de tratamiento requerido al desconocerse su perfil de sensibilidad en ese momento. Para determinar el grado de concordancia entre las pruebas de sensibilidad de los casos índice y los casos secundarios, se llevó a cabo un estudio retrospectivo, descriptivo, revisßndose registros clínicos y pruebas de sensibilidad a drogas de primera línea de casos secundarios y sus casos índice diagnosticados de TB MDR entre el 2000 y 2005 en la jurisdicción de la DISA Callao. Cumplieron criterios de inclusión 27 pacientes. La frecuencia de concordancia (pruebas idénticas) fue de 40.7 por ciento y la frecuencia de cepas MDR entre los casos secundarios fue 66.7 por ciento, siendo el restante 18.5 por ciento de los casos secundarios pansensibles a drogas de primera línea, y otro 14.8 por ciento pacientes drogoresistentes (DR) no MDR. Con respecto al anßlisis multivariado, el antecedente del caso índice de haber recibido mßs de 2 tratamientos antituberculosos se asoció con la concordancia entre las pruebas de sensibilidad estudiadas y con la presencia de cepas MDR en el caso secundario. Se concluye que es necesario de manera rutinaria asegurar una prueba de sensibilidad para identificación de drogo resistencia y que nuestros hallazgos justifican el empleo de un tratamiento estandarizado para los casos secundarios que debe ser ajustado de acuerdo a la prueba de sensibilidad solicitada antes de iniciar el tratamiento.

Multidrug-resistant (MDR) pulmonary tuberculosis represents a public health problem due to the complexity of its therapy and minor recovery rates comparing with drug susceptible tuberculosis. An additional aspect is related to the management of the contacts that develop the disease (secondary cases) in which cases it can not be defined the type of therapy they need because the drug-susceptibility pattem are unknown in this moment. To determinate the concordance degree of drug-susceptibility assays between index and secondary cases, it was performed a retrospective descriptive survey. Clinical records and first-line drug susceptibility tests of secondary cases and its index cases diagnosed with multidrug-resistant tuberculosis were reviewed between 2000 and 2005 in the jurisdiction of DISA Callao. Twenty-four patients fulfilled inclusion criteria. The rate of concordance (identical patterns) was 40.7 per cent and the rate of MDR strains in secondary cases was 66.7 per cent, there mainder 18.5 per cent were susceptible to all first-line drugs and 14.8 per cent patients were drug resistant (DR) not MDR. With regard to multivariate analysis, the index case record of having more than 2 anti-tuberculous regimens was associated with total concordance between drug-susceptibility assays and it was associated with the presence of MDR strains among secondary cases. We conclude that it is routinely necessary to make sure a susceptibility assay for identifying drug-resistance and conclude that our findings justify the use of a standardized retreatment regimen for secondary cases which must be adjusted in agreement with the susceptibility assay requested before the therapy.

Effects of intensity and duration of exercise on muscular responses to training of thoroughbred racehorses.

This study examined the effects of the intensity and duration of exercise on the nature and magnitude of training adaptations in muscle of adolescent (2-3 yr old) racehorses. Six thoroughbreds that had been pretrained for 2 mo performed six consecutive conditioning programs of varying lactate-guided intensities [velocities eliciting blood lactate concentrations of 2.5 mmol/l (v2.5) and 4 mmol/l (v4), respectively] and durations (5, 15, 25 min). Pre- and posttraining gluteus muscle biopsies were analyzed for myosin heavy chain content, fiber-type composition, fiber size, capillarization, and fiber histochemical oxidative and glycolytic capabilities. Although training adaptations were similar in nature, they varied greatly in magnitude among the different training protocols. Overall, the use of v4 as the exercise intensity for 25 min elicited the most consistent training adaptations in muscle, whereas the minimal training stimulus that evoked any significant change was identified with exercises of 15 min at v2.5. Within this range, muscular adaptations showed significant trends to be proportional to the exercise load of specific training programs. Taken together, these data suggest that muscular adaptations to training in horses occur on a continuum that is based on the exercise intensity and duration of training. The practical implications of this study are that exercises for 15 to 25 min/day at velocities between v2.5 and v4 can improve in the short term (3 wk) the muscular stamina in thoroughbreds. However, exercises of 5-15 min at v4 are necessary to enhance muscular features related to strength (hypertrophy).

Myosin heavy chain fibre types and fibre sizes in nuliparous and primiparous ovariectomized Iberian sows: Interaction with two alternative rearing systems during the fattening period.

To investigate the effects of the reproductive background (nuliparous/primiparous) on skeletal muscle phenotype and their interaction with two alternative finishing systems (indoors/outdoors) in Iberian sows, 32 contemporary piglets were assigned to four different groups: indoors-nuliparous, indoors-primiparous, outdoors-nuliparous and outdoors-primiparous. Nuliparous sows were ovariectomized at 4 months of age, whereas primiparous were castrated at 14 months of age, after their first lactation. Indoors sows were fattened (2 months prior to slaughter) intensively, whereas outdoors sows were finished in an extensive land with natural resources. Muscle samples (semimembranosus, gluteobiceps) were analyzed for myosin fibre types and fibre sizes. Sows finished out-of-doors had more type I and IIA fibres and smaller fibres than indoor-fattened pigs. Primiparous reared indoors had a significantly lower IIX:IIB fibre ratio and showed a clear tendency for having larger fibres than nuliparous reared indoors. Reproductive background effect interacted with rearing condition effect inducing relevant muscular adaptations. Thus, the influence of reproductive background on muscle characteristics was not significant in sows reared out-of-doors but highly significant in sows finished intensively. This interaction resulted in muscular traits less favourable for meat quality in primiparous vs. nuliparous reared indoors.

New insights into skeletal muscle fibre types in the dog with particular focus towards hybrid myosin phenotypes.

Electrophoresis, immunoblots, immunohistochemistry and image analysis methods were applied to characterise canine trunk and appendicular muscle fibres according to their myosin heavy chain (MyHC) composition and to determine, on a fibre-to-fibre basis, the correlation between contractile [MyHC (s), myofibrillar ATPase (mATPase) and sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) isoforms], metabolic [succinate dehydrogenase (SDH) and glycerol-3-phosphate dehydrogenase (GPDH) activities and glycogen and phospholamban (PLB) content] and morphological (cross-sectional area and capillary and nuclear densities) features of individual myofibres. An accurate delineation of MyHC-based fibre types was obtained with the developed immunohistochemical method, which showed high sensitivity and objectivity to delineate hybrid fibres with overwhelming dominance of one MyHC isoform. Phenotypic differences in contractile, metabolic and morphological properties seen between fibre types were related to MyHC content. All canine skeletal muscle fibre types had a relatively high histochemical SDH activity but significant differences existed in the order IIA>I>IIX. Mean GPDH was ranked according to fibre type such that II>IIX. Hybrid fibres, which represented nearly one third of the whole pool of skeletal muscle fibres analysed, had mean values intermediate between their respective pure phenotypes. Slow fibres expressed the slow SERCA isoform and PLB, whereas type II fibres expressed the fast SERCA isoform. Discrimination of myofibres according to their MyHC content was possible on the basis of their contractile, metabolic and morphological features. These intrafibre interrelationships suggest that myofibres of control dogs exhibit a high degree of co-ordination in their physiological, biochemical and morphological characteristics. This study demonstrates that canine skeletal muscle fibres have been misclassified in numerous previous studies and offers useful baseline data and new prospects for future work on muscle-fibre-typing in canine experimental studies.