Quantification of lipoproteins by proton nuclear magnetic resonance spectroscopy (1H-NMRS) improves the prediction of cardiac autonomic dysfunction in patients with type 1 diabetes.

AIMS: To assess if advanced characterization of serum glycoprotein and lipoprotein profile, measured by proton nuclear magnetic resonance spectroscopy (1H-NMRS) improves a predictive clinical model of cardioautonomic neuropathy (CAN) in subjects with type 1 diabetes (T1D). METHODS: Cross-sectional study (ClinicalTrials.gov Identifier: NCT04950634). CAN was diagnosed using Ewing's score. Advanced characterization of macromolecular complexes including glycoprotein and lipoprotein profiles in serum samples were measured by 1H-NMRS. We addressed the relationships between these biomarkers and CAN using correlation and regression analyses. Diagnostic performance was assessed by analyzing their areas under the receiver operating characteristic curves (AUCROC). RESULTS: Three hundred and twenty-three patients were included (46% female, mean age and duration of diabetes of 41 ± 13 years and 19 ± 11 years, respectively). The overall prevalence of CAN was 28% [95% confidence interval (95%CI): 23; 33]. Glycoproteins such as N-acetylglucosamine/galactosamine and sialic acid showed strong correlations with inflammatory markers such as high-sensitive C-reactive protein, fibrinogen, IL-10, IL-6, and TNF-α. On the contrary, we did not find any association between the former and CAN. A stepwise binary logistic regression model (R2 = 0.078; P = 0.003) retained intermediate-density lipoprotein-triglycerides (IDL-TG) [ß:0.082 (95%CI: 0.005; 0.160); P = 0.039], high-density lipoprotein-triglycerides (HDL-TGL)/HDL-Cholesterol [ß:3.633 (95%CI: 0.873; 6.394); P = 0.010], and large-HDL particle number [ß: 3.710 (95%CI: 0.677; 6.744); P = 0.001] as statistically significant determinants of CAN. Adding these lipoprotein particles to a clinical prediction model of CAN that included age, duration of diabetes, and A1c enhanced its diagnostic performance, improving AUCROC from 0.546 (95%CI: 0.404; 0.688) to 0.728 (95%CI: 0.616; 0.840). CONCLUSIONS: When added to clinical variables, 1H-NMRS-lipoprotein particle profiles may be helpful to identify those patients with T1D at risk of CAN.

A molecular dynamics study on the mechanical response of thermal-pressure rejuvenated CuxZr100-x metallic glasses.

A molecular dynamics study was performed on the mechanical response of thermal-pressure rejuvenated CuxZr100-x metallic glasses. The effect of temperature (50, 300, 600 K) and pressure (0-50 GPa) on the rejuvenation process and the mechanical properties of CuxZr100-x including stress-strain response, shear localization formation and elastic modulus were investigated. The thermal-pressure rejuvenation process involves transitioning the system to a higher potential energy state and a lower atomic volume, demonstrating the significant influence of pressure on rejuvenation. Our findings reveal that increasing pressure at specific temperatures and material compositions results in reduced yield stress and stress drop. They also indicate that with increasing pressure, the system undergoes a transition towards homogeneity, resulting in enhanced ductility compared to its initial amorphous state. Additionally, high temperatures contribute to lower values of Young's, shear, and bulk moduli, as well as decreased yield stress and stress drop. Consequently, the system becomes more homogeneous, promoting rejuvenation. Furthermore, we observed that the final yield strength of the system increases with higher Cu content for all structures at specific pressures and temperatures. The level of rejuvenation is additionally impacted by the amount of Cu, and structures containing varying content of Cu demonstrate varying degrees of rejuvenation. To validate our findings, we utilized Voronoi analysis, which revealed a higher fraction of densely-packed clusters in the samples. Finally, a total of 10 materials properties were calculated and explored using statistical analysis which shows there are different correlations between pressure, temperature and atomic composition with mechanical properties.

Perfil lipoproteico por espectroscopia nuclear magnética en pacientes con insuficiencia cardiaca crónica comparado con controles emparejados / 1H-magnetic resonance spectroscopy lipoprotein profile in patients with chronic heart failure versus matched controls

Introducción y objetivos El fenotipado avanzado de lipoproteínas es mejor predictor del riesgo aterosclerótico que el colesterol. El perfil de lipoproteínas en la insuficiencia cardiaca (IC) no está completamente caracterizado. Nuestro objetivo fue describir el perfil de lipoproteínas en IC crónica en comparación con una población de control emparejada. Métodos Estudio transversal entre mayo 2006 y abril 2014, que incluyó pacientes ambulatorios con IC crónica. Las concentraciones de lípidos y el tamaño de las principales fracciones de lipoproteínas (lipoproteínas de alta densidad [HDL], lipoproteínas de baja densidad [LDL] y lipoproteínas de muy alta densidad) y concentración de sus subfracciones (grandes, medianas y pequeñas) se evaluaron mediante espectroscopia de resonancia magnética. Resultados 429 pacientes con IC crónica se compararon con 428 controles. Los pacientes con IC crónica presentaron menor colesterol total y menor concentración de partículas de LDL (1.115 frente a 1.352 nmol/L; p <0,001) y HDL (25,7 frente a 27,9μmol/L; p <0,001), esta última mediada principalmente por la reducción de la subfracción pequeña de HDL (15,2 frente a 18,6μmol/L; p <0,001). El tamaño medio de las partículas lipoproteínas de muy alta densidad, LDL y HDL fue significativamente mayor en los pacientes con IC. Todas las diferencias relacionadas con la partícula HDL persistieron después del ajuste por clase funcional o índice de masa corporal. Encontramos fuertes correlaciones negativas entre biomarcadores cardiacos (fracción aminoterminal del propéptido natriurético cerebral y interleucina-1 tipo de receptor 1) con concentraciones de LDL y HDL, sus subfracciones pequeñas y el tamaño de la partícula HDL. Conclusione Los pacientes con IC crónica difieren significativamente en su perfil de lipoproteínas en comparación con controles emparejados. Se necesitan más investigaciones para comprender mejor la relevancia patogénica de esta diferencia (AU)

Introduction and objectives Advanced lipoprotein phenotyping is a better predictor of atherosclerotic cardiovascular risk than cholesterol concentration alone. Lipoprotein profiling in heart failure (HF) is incompletely characterized. We aimed to describe the lipoprotein profile in patients with chronic HF compared with a matched control population. Methods This cross-sectional study was performed from May 2006 to April 2014 and included ambulatory patients with chronic HF. Lipid concentrations and the size of main lipoprotein fractions (high-density lipoprotein [HDL], low-density lipoprotein [LDL], and very low-density lipoprotein) and the particle concentration of their 3 subfractions (large, medium and small) were assessed using 1H magnetic resonance spectroscopy. Results The 429 included patients with chronic HF were compared with 428 matched controls. Patients with chronic HF had lower total cholesterol and lower mean LDL (1115 vs 1352 nmol/L; P<.001) and HDL (25.7 vs 27.9μmol/L; P <.001) particle concentrations, with this last difference being mediated by a significantly lower concentration of the small subfraction of HDL (15.2 vs 18.6μmol/L; P <.001). Mean very low-density lipoprotein, LDL, and HDL particle size was significantly higher in patients with HF vs controls. All HDL-related differences from controls persisted after adjustment for New York Heart Association functional class or body mass index. We found strong negative correlations of known cardiac biomarkers (N-terminal pro-brain natriuretic peptide and interleukin-1 receptor-like 1) with total and small LDL and HDL fractions and HDL particle size. Conclusions Patients with chronic HF significantly differ in their lipoprotein profile compared with unaffected controls. Further research is needed to better understand the pathogenic relevance of this difference (AU)

Particle size and cholesterol content of circulating HDL correlate with cardiovascular death in chronic heart failure.

Evidence regarding any association of HDL-particle (HDL-P) derangements and HDL-cholesterol content with cardiovascular (CV) death in chronic heart failure (HF) is lacking. To investigate the prognostic value of HDL-P size (HDL-Sz) and the number of cholesterol molecules per HDL-P for CV death in HF patients. Outpatient chronic HF patients were enrolled. Baseline HDL-P number, subfractions and HDL-Sz were measured using 1H-NMR spectroscopy. The HDL-C/P ratio was calculated as HDL-cholesterol over HDL-P. Endpoint was CV death, with non-CV death as the competing event. 422 patients were included and followed-up during a median of 4.1 (0-8) years. CV death occurred in 120 (30.5%) patients. Mean HDL-Sz was higher in CV dead as compared with survivors (8.39 nm vs. 8.31 nm, p < 0.001). This change in size was due to a reduction in the percentage of small HDL-P (54.6% vs. 60% for CV-death vs. alive; p < 0.001). HDL-C/P ratio was higher in the CV-death group (51.0 vs. 48.3, p < 0.001). HDL-Sz and HDL-C/P ratio were significantly associated with CV death after multivariable regression analysis (HR 1.22 [95% CI 1.01-1.47], p = 0.041 and HR 1.04 [95% CI 1.01-1.07], p = 0.008 respectively). HDL-Sz and HDL-C/P ratio are independent predictors of CV death in chronic HF patients.

A one-year longitudinal study of enterohemorrhagic Escherichia coli O157 fecal shedding in a beef cattle herd.

Bovines are the primary reservoir of enterohemorrhagic Escherichia coli (EHEC) O157:H7 and the main source of its transmission to humans. Here, we present a one-year longitudinal study of fecal shedding of E. coli O157. E. coli O157 obtained from recto-anal mucosal samples were characterized by multiplex PCR. The E. coli O157 prevalence ranged from 0.84% in July to 15.25% in November. The confinement within pens resulted in prevalence of 11%. Most animals (61.86%; 75/118) shed E. coli O157 at least in one sampling occasion. Of the positive animals, 82.19%, 16.44%, and 1.37% were stx positive on one, two and three sampling occasions, respectively. All the E. coli O157 isolated strains carried the genes eae and rfbO157, whereas 11%, 33% and 56% contained stx1, stx2 and stx1/stx2, respectively. The stx1/stx2 and stx2 types were significantly higher during the grazing and finishing periods, respectively, in comparison with the rearing and grazing periods. The presence of stx2a subtype was evident in four isolates, whereas stx2c was present in at least seven. However, both subtypes were present simultaneously in two isolates. The stx1/stx2c, stx1/stx2d and stx1/stx2NT genotypes occurred in 24, 2 and 15 isolates, respectively. The simultaneous occurrence of stx1 and stx2c significantly increased during grazing. Some cases of within-pen and between-pen transmission occurred throughout the study. Contagion levels during in-field grazing were higher than during permanent confinement in the pens. Thus, the individual patterns of shedding varied depending on the proportion of animals shedding the bacteria within pens and the time of shedding.

LDL particle size and composition and incident cardiovascular disease in a South-European population: The Hortega-Liposcale Follow-up Study.

BACKGROUND: The association of low-density lipoprotein (LDL) particle composition with cardiovascular risk has not been explored before. The aim was to evaluate the relationship between baseline LDL particle size and composition (proportions of large, medium and small LDL particles over their sum expressed as small-LDL %, medium-LDL % and large-LDL %) and incident cardiovascular disease in a population-based study. METHODS: Direct measurement of LDL particles was performed using a two-dimensional NMR-technique (Liposcale®). LDL cholesterol was assessed using both standard photometrical methods and the Liposcale® technique in a representative sample of 1162 adult men and women from Spain. RESULTS: The geometric mean of total LDL particle concentration in the study sample was 827.2 mg/dL (95% CI 814.7, 839.8). During a mean follow-up of 12.4 ±â€¯3.3 years, a total of 159 events occurred. Medium LDL particles were positively associated with all cardiovascular disease, coronary heart disease (CHD) and stroke after adjustment for traditional risk factors and treatment. Regarding LDL particle composition, the multivariable adjusted hazard ratios for CHD for a 5% increase in medium and small LDL % by a corresponding decrease of large LDL % were 1.93 (1.55, 2.39) and 1.41 (1.14, 1.74), respectively. CONCLUSIONS: Medium LDL particles were associated with incident cardiovascular disease. LDL particles showed the strongest association with cardiovascular events when the particle composition, rather than the total concentration, was investigated. A change in baseline composition of LDL particles from large to medium and small LDL particles was associated with an increased cardiovascular risk, especially for CHD.

Effect of diets rich in either saturated fat or n-6 polyunsaturated fatty acids and supplemented with long-chain n-3 polyunsaturated fatty acids on plasma lipoprotein profiles.

BACKGROUND/OBJECTIVES: Abnormalities in lipoprotein profiles (size, distribution and concentration) play an important role in the pathobiology of atherosclerosis and coronary artery disease. Dietary fat, among other factors, has been demonstrated to modulate lipoprotein profiles. We aimed to investigate if background dietary fat (saturated, SFA versus omega-6 polyunsaturated fatty acids, n-6PUFA) was a determinant of the effects of LCn-3PUFA supplementation on lipoprotein profiles. SUBJECTS/METHODS: A randomized controlled clinical intervention trial in a parallel design was conducted. Healthy subjects (n=26) were supplemented with 400 mg eicosapentaenoic acid plus 2000 mg docosahexaenoic acid daily and randomized to consume diets rich in either SFA or n-6PUFA for a period of 6 weeks. Blood samples, collected at baseline and after 6 weeks of intervention, were assessed for plasma lipoprotein profiles (lipoprotein size, concentration and distribution in subclasses) determined using nuclear magnetic resonance spectroscopy. RESULTS: Study participants receiving the SFA or the n-6PUFA enriched diets consumed similar percentage energy from fat (41 and 42% respectively, P=0.681). However, subjects on the SFA diet consumed 50% more energy as saturated fat and 77% less as linoleic acid than those consuming the n-6PUFA diet (P<0.001). The diets rich in SFA and n-6PUFA reduced the concentration of total very-low-density lipoprotein (VLDL) particles (P<0.001, both), and their subclasses and increased VLDL (P=0.042 and P=0.007, respectively) and LDL (P=0.030 and 0.027, respectively) particle size. In addition, plasma triglyceride concentration was significantly reduced by LCn-3PUFA supplementation irrespective of the dietary fat. CONCLUSIONS: LCn-3PUFA modulated lipoprotein profiles in a similar fashion when supplemented in diets rich in either SFA or n-6PUFA.

Fiabilidad de un test de dinamometría manual en pacientes con dolor de espalda baja mediante test-retest de 12 semanas: estudio piloto / Reliability of handgrip test in low back pain patients using a 12-week test-retest: Pilot study

Objetivo: Calcular la fiabilidad de un protocolo de valoración de la fuerza mediante dinamometría manual mediante test-retest en pacientes con dolor crónico de espalda baja. Material y método: La muestra estuvo compuesta por 6 pacientes derivados por una unidad hospitalaria especializada. Cada uno realizó la evaluación en 2 ocasiones separadas con un intervalo de 12 semanas. Resultados: No se encontraron diferencias significativas entre los valores de fuerza máxima obtenidos en las 2 sesiones de medición y los índices obtenidos de fiabilidad relativa y absoluta son excelentes. Conclusiones: La fuerza de prensión manual evaluada a través de dinamometría es replicable en ambas manos en periodos de intervalo de 12 semanas en pacientes con dolor de espalda baja

Objective: The aim of this study was to calculate the reliability of a handgrip protocol in low back pain patients using a test-retest design. Material and method: The sample consisted of 6 patients referred by a specialised hospital unit. Each participant performed the test twice with an interval of 12 weeks. Results: There were no statistically significant differences between maximal handgrip assessed in both sessions. Absolute and relative reliability index were excellent. Conclusions: Maximal handgrip is highly reliable in both hands after 12 weeks in patients with low back pain

Fiabilidad de la prueba Fall Risk de la plataforma Biodex Balance System® en las personas mayores institucionalizadas con miedo a caerse mediante test-retest de 12 semanas / Reliability of fall risk test of the Biodex Balance System ® platform in institutionalized elderly with fear of falling by 12 weeks test-retest

Introducción. El objetivo del presente estudio es analizar la fiabilidad de la prueba Fall Risk (FR) de la plataforma Biodex Balance System® (BBS) en las personas mayores institucionalizadas con miedo a caerse mediante un test-retest de 12 semanas. Material y métodos. Participaron en el estudio 14 personas mayores institucionalizadas (75,64 ± 7,47 años; 74,29 ± 15,52 kg) con miedo a caerse (puntuación FES- I = 32,57 ± 7,52). Se realizó un test-retest de 12 semanas. Cada sujeto realizó 3 ensayos (20 s cada uno) en cada medición en la plataforma BBS a nivel 8 con un descanso de 10 s entre ensayos. Para cada medición se tomó la media de los 3 ensayos. Resultados. La fiabilidad relativa de la prueba descrita fue excelente (CCI = 0,97). En cuanto a la fiabilidad absoluta se obtuvo un error estándar de medida (EEM) del 9,9% y un mínimo cambio real (MCR) de 27,4%. La fiabilidad de la plataforma BBS usando el método Bland-Altman mostró que el error sistemático (diferencia de medias entre el test-retest) para la prueba FR fue 0,25 (bias). Conclusión. La puntuación obtenida en la prueba FR evaluada con la plataforma BBS es replicable para las mediciones de equilibrio dinámico y riesgo de caída en personas mayores institucionalizadas con miedo a caerse. Este estudio proporciona nuevos datos para la interpretación de los cambios producidos en la puntuación de la prueba FR de BBS tras la aplicación de programas de actividad física en esta población (AU)

Introduction. The aim of the present study was to analyze the reliability of the Fall Risk (FR) test of the Biodex Balance System® (BBS) platform in institutionalized elderly with fear of falling using a 12-weeks test-retest. Material and methods. Fourteen institutionalized elderly (n=14; 75.64±7.47 years; 74.29±15.52 kg) with fear of falling (FES- I score=32.57±7.52) participated in this study. A 12-week test-retest was performed. Each subject performed 3 trials (20 s each) for each measurement in the BBS platform at level 8 with a rest of 10 s between trials. The mean of the three trials was taken for each measurement. Results. The relative reliability of the described test was excellent (ICC=0,97). Regarding absolute reliability, a 9.9% standard error of measurement (SEM) was obtained with a 27.4% small real difference (SRD). The reliability of the BBS platform using Bland-Altman method showed that the systematic error (mean difference between test-retest) for the FR test was 0,25 (bias). Conclusion. The score obtained in the FR test evaluated with BBS platform is replicable for measurements of dynamic balance and fall risk in institutionalized elderly with fear of falling. This study provides new data for interpreting changes in the FR test score on BBS after the application of physical activity programs in this population (AU)

Fiabilidad relativa y absoluta del test de elevación progresiva de carga isoinercial en pacientes afectados por dolor de espalda bajo crónico no específico: un estudio test-retest de 12 semanas / Relative and absolute reliability of the progressive iso-inertial lifting test in patients affected by non-specific, chronic low back pain: a 12-week test-retest study

Introducción. El dolor de espalda bajo crónico inespecífico es una dolencia cada vez más prevalente. Esta dolencia afecta a la funcionalidad y a la calidad de vida del individuo que la padece. El objetivo de este estudio fue determinar los índices relativos y absolutos de fiabilidad test-retest del protocolo de evaluación de la capacidad isoinercial de carga progresivo, como método de evaluación de la capacidad funcional en estos pacientes. Material y métodos. La muestra se compuso de 10 pacientes con dolor de espalda baja crónico inespecífico derivados por una unidad hospitalaria especializada en pacientes con dolor a los que se aplicó el protocolo del test de evaluación de la capacidad isoinercial de carga progresivo en 2 ocasiones separadas por un período de tiempo de 12 semanas siguiendo el protocolo estandarizado de dicho test. El análisis de los datos consistió en el cálculo de los índices de fiabilidad relativos (coeficiente de correlación intraclase) y absolutos (error estándar de medida y mínima diferencia real), así como la representación de los datos mediante los correspondientes gráficos de Bland-Altman. Resultados. Los resultados obtenidos muestran coeficientes de correlación intraclase altos, así como índices de error absolutos elevados para el test usado tanto en varones como en mujeres. Conclusión. El procedimiento empleado para la determinación de la capacidad funcional mediante del test de evaluación de la capacidad isoinercial de carga progresivo muestra una consistencia temporal alta, por lo que puede ser utilizado como medio para evaluar dicha capacidad en pacientes con dolor de espalda baja crónico inespecífico, en intervenciones inferiores a 12 semanas(AU)

Introduction. Chronic non-specific low back pain is an increasingly prevalent ailment. This ailment affects functional capacity and quality of life of individuals who have this condition. The aim of this study was to determine relative and absolute test-retest reliability of the protocol for the evaluation of the progressive isoinertial lifting test as a functional capacity function method. Material and methods. The sample consisted of 10 patients with chronic non-specific low back pain referred from a hospital unit specialized in pain patients who underwent the standardized protocol of the progressive isoinertial lifting test on two occasions separated by a period of 12 weeks. The data analysis consisted of calculating relative reliability (intraclass correlation coefficients) and absolute (standard error of measurement and smallest real difference) indices and the representation of the data using the corresponding Bland-Altman plots. Results. The results obtained show high correlation coefficients and large absolute error rates for the test used both in men and women. Conclusion. The procedure used for determining the functional capacity by means of the progressive isoinertial lifting test shows high temporal consistence. Thus, it can be used as a method to assess functional capacity of patients with chronic non-specific low back pain enrolled in interventions of less than 12 weeks(AU)

Reacción de hipersensibilidad tras inyección de azul patente V sódico para detección de ganglio centinela / No disponible

No disponible

[Lazarus phenomenon: spontaneous resuscitation]. / El fenómeno de lázaro: reanimación espontánea.

A 94-year-old woman undergoing surgery for simple repair of a duodenal perforation experienced a sudden massive hemorrhage (1500 mL) when the duodenum was separated from adjacent structures. Hemodynamic stability was re-established when fluids were replaced. After the abdominal wall was closed, increased amplitude of the QRS wave was observed and heart rate slowed until there was no pulse. Electromechanical dissociation (EMD) was diagnosed and cardiopulmonary resuscitation was started. When EMD persisted after 40 minutes, resuscitative measures were stopped and the ventilator was disconnected, though orotracheal intubation and arterial and electrocardiographic monitoring were maintained. After 2 or 3 minutes, heart rhythm restarted spontaneously and arterial pressure waves reappeared on the monitor. The patient progressed well for 72 hours, after which she developed septic shock and multiorgan failure, dying 18 days later. The Lazarus phenomenon may be more common than the medical literature would indicate, possibly because a large gap in our understanding of the pathophysiology of the phenomenon underlies anecdotes about "miracles". As we wait for adequate international consensus on a protocol for monitoring the withdrawal of resuscitative measures, we should act prudently before definitively certifying death. The case we report occurred during a surgical intervention in which the patient had received general anesthesia. We believe that the causes that might explain the Lazarus phenomenon are quite different in that context than they would be in a nonsurgical setting, such that it would be useful to create a national database to keep a record of such intraoperative events.

Influencia de la analgesia epidural sobre la incidencia de taquiarritmias en el postoperatorio de la cirugía pulmonar / Influence of epidural analgesia on the incidence of tachyarrhythmia during pulmonary surgery postoperative

Objetivos: Valorar la influencia del uso de analgesia epidural torácica (AET) intra y postoperatoria sobre la presentación de taquiarritmias en el postoperatorio de las resecciones pulmonares. Material y métodos: Se han analizado, de forma retrospectiva, los cursos postoperatorios de 200 pacientes consecutivos intervenidos de resecciones pulmonares mayores (lobectomías, bilobectomías y neumonectomías) en nuestro hospital durante el periodo comprendido entre octubre de 1998 y junio de 2002. En este tiempo se ha introducido progresivamente en nuestro Servicio la AET como parte de la técnica anestésica en cirugía pulmonar. Se ha analizado la influencia del empleo de AET en la presentación de episodios de taquiarritmia supraventricular en las primeras 48 horas de postoperatorio. Resultados: Se empleó AET para el manejo anestésico y control del dolor postoperatorio en el 49,5 por ciento de los casos (99/200).No existen diferencias significativas entre los grupos de pacientes con y sin AET en cuanto a edad, sexo, riesgo ASA, duración de la intervención y tipo de resecciones practicadas. Presentaron crisis de taquiarritmia el 9,5 por ciento de los pacientes (19/200), tratándose, en todos los casos, de fibrilación auricular paroxística. Entre los pacientes que no recibieron AET la tasa de arritmias fue del 13,86 por ciento (14/101), mientras que en aquellos en los que se empleó AET como parte de la técnica anestésica y durante el postoperatorio, dicha tasa fue del 5,05 por ciento (5/99), siendo dicha diferencia estadísticamente significativa (p=0,034). Conclusiones: El empleo de AET como parte de la técnica anestésica y para el manejo del dolor postoperatorio en cirugía de resección pulmonar parece ejercer un efecto protector en cuanto al desarrollo de fibrilación auricular en el postoperatorio inmediato. Se discuten las posibles causas de este efecto (AU)

The distribution of rest periods affects performance and adaptations of energy metabolism induced by high-intensity training in human muscle.

The effect of the distribution of rest periods on the efficacy of interval sprint training is analysed. Ten male subjects, divided at random into two groups, performed distinct incremental sprint training protocols, in which the muscle load was the same (14 sessions), but the distribution of rest periods was varied. The 'short programme' group (SP) trained every day for 2 weeks, while the 'long programme' group (LP) trained over a 6-week period with a 2-day rest period following each training session. The volunteers performed a 30-s supramaximal cycling test on a cycle ergometer before and after training. Muscle biopsies were obtained from the vastus lateralis before and after each test to examine metabolites and enzyme activities. Both training programmes led to a marked increase (all significant, P < 0.05) in enzymatic activities related to glycolysis (phosphofructokinase - SP 107%, LP 68% and aldolase - SP 46%, LP 28%) and aerobic metabolism (citrate synthase - SP 38%, LP 28.4% and 3-hydroxyacyl-CoA dehydrogenase - SP 60%, LP 38.7%). However, the activity of creatine kinase (44%), pyruvate kinase (35%) and lactate dehydrogenase (45%) rose significantly (P < 0.05) only in SP. At the end of the training programme, SP had suffered a significant decrease in anaerobic ATP consumption per gram muscle (P < 0.05) and glycogen degradation (P < 0.05) during the post-training test, and failed to improve performance. In contrast, LP showed a marked improvement in performance (P < 0.05) although without a significant increase in anaerobic ATP consumption, glycolysis or glycogenolysis rate. These results indicate that high-intensity cycling training in 14 sessions improves enzyme activities of anaerobic and aerobic metabolism. These changes are affected by the distribution of rest periods, hence shorter rest periods produce larger increase in pyruvate kinase, creatine kinase and lactate dehydrogenase. However, performance did not improve in a short training programme that did not include days for recovery, which suggests that muscle fibres suffer fatigue or injury.

Effect of summer intermission on skeletal muscle of adolescent soccer players.

BACKGROUND: To study the effect of some weeks of rest on three groups of adolescent soccer players, who had undergone systematic training for eleven months. EXPERIMENTAL DESIGN: Retrospective and comparative investigation; duration 4-8 weeks. SETTING: young amateur players from a Spanish football club were examined at the beginning and at the end of the summer rest period. PARTICIPANTS: 37 young soccer players aged 14, 15 and 16 years old. They were members of three football teams. INTERVENTIONS: during the rest period they were free from any training program. MEASURES: biopsies of M. vastus lateralis were taken immediately after training and after the summer holidays. The type, percentage and diameter of the fibers, as well as the enzymes of glycogen metabolism (glycogen synthase and glycogen phosphorylase), glycolysis (phosphofructokinase and lactate dehydrogenase), oxidative metabolism (succinate dehydrogenase and citrate synthase) and creatine kinase and transaminase (aspartate and alanine aminotransferase) were studied. RESULTS: Detraining had an adaptation effect, decreasing the cross-sectional area of type I and type II fibers, and decreasing the activities of creatine kinase, citrate synthase, phosphofructokinase, lactate dehydrogenase and aspartate aminotransferase. CONCLUSIONS: The results can help trainers to plan the length of the rest period between training.

Failure of cesarean section to prevent intracranial hemorrhage in siblings with isoimmune neonatal thrombocytopenia.

Two siblings with isoimmune neonatal thrombocytopenia developed severe neurological sequelae secondary to intracranial hemorrhage despite delivery by cesarean section. These cases demonstrate that cesarean section alone will not prevent intracranial hemorrhage, in utero or postnatally, in isoimmune neonatal thrombocytopenia.