Dysphagia in patients undergoing esophageal atresia surgery: Assessment using a functional scale. / Disfagia en pacientes intervenidos de atresia de esófago: valoración con una escala funcional.

INTRODUCTION: Dysphagia is defined as difficulty swallowing. Up to 84% of patients undergoing esophageal atresia surgery have dysphagia beyond the neonatal period. MATERIALS AND METHODS: A retrospective study of patients undergoing esophageal atresia surgery from 2005 to 2021 was carried out. The Functional Oral Intake Scale (FOIS) was used to assess dysphagia in 4 age groups (< 1 year old, 1-4 years old, 5-11 years old, and > 11 years old). FOIS scores < 7 or symptoms of choking, impaction, or food aversion were regarded as dysphagia. RESULTS: 63 patients were analyzed. 74% (47/63) had dysphagia during follow-up. Prevalence was 50% in patients < 1 year old (FOIS mean 4.32), 77% in patients aged 1-4 (FOIS mean 5.61), 45% in patients aged 5-11 (FOIS mean 5.87), and 38% in patients > 11 years old (FOIS mean 6.8). The most frequent causes of dysphagia were stenosis, which occurred in 38% of the patients (n=24), and gastroesophageal reflux (n=18), which was present in 28% of the patients. Both conditions were associated with significantly lower mean FOIS scores (p< 0.05) in the patients under 11 years of age. Differences (p< 0.05) were found in the dysphagia-associated perinatal factors in the various age groups, with longer ventilation assistance times, parenteral nutrition, and hospital stays. CONCLUSIONS: Dysphagia is an extremely frequent symptom at any given age in patients undergoing esophageal atresia surgery. A standardized, cross-disciplinary follow-up is key to improve quality of life.

INTRODUCCION: La disfagia se define como dificultad en el proceso de alimentación. Hasta un 84% de pacientes intervenidos de atresia de esófago tienen disfagia más allá del periodo neonatal. MATERIAL Y METODOS: Estudio retrospectivo de serie de casos intervenidos por atresia de esófago 2005-2021. Se utilizó la escala FOIS (Functional Oral Intake Scale) para cuantificar la disfagia en 4 grupos de edad (menores de 1 año, 1-4 años, 5-11 años y mayores de 11 años). Se consideró disfagia cualquier valor de FOIS < 7 o síntomas de atragantamiento, impactación o aversión alimentaria. RESULTADOS: Se obtuvieron datos de 63 pacientes. El 74% (47/63) presentó disfagia durante el seguimiento. La prevalencia fue del 50% < 1 año (media FOIS 4.32), 77% 1-4 años (media FOIS 5.61), 45% 5-11 años (media FOIS 5.87) y 38% > 11 años (media FOIS 6.8). Las causas más frecuentes de disfagia fueron la estenosis, que presentó un 38% de los pacientes (n= 24) y el reflujo gastroesofágico (n= 18), que presentó a su vez un 28% de los pacientes. Ambas condiciones se asociaron con unos valores medios de FOIS significativamente menores (p< 0,05) en los pacientes menores de 11 años. Se encontraron diferencias (p< 0,05) en factores perinatales asociados a disfagia en los distintos periodos de edad, a destacar mayor tiempo medio de: asistencia ventilatoria, nutrición parenteral e ingreso hospitalario. CONCLUSIONES: La disfagia es un síntoma extremadamente frecuente a cualquier edad en los pacientes intervenidos de atresia de esófago. Un seguimiento estandarizado y multidisciplinar es esencial para mejorar la calidad de vida de estos pacientes.

Disfagia en pacientes intervenidos de atresia de esófago: valoración con una escala funcional / Dysphagia in patients undergoing esophageal atresia surgery: Assessment using a functional scale

Introducción: La disfagia se define como dificultad en el procesode alimentación. Hasta un 84% de pacientes intervenidos de atresia deesófago tienen disfagia más allá del periodo neonatal.Material y métodos: Estudio retrospectivo de serie de casos intervenidos por atresia de esófago 2005-2021. Se utilizó la escala FOIS(Functional Oral Intake Scale) para cuantificar la disfagia en 4 gruposde edad (menores de 1 año, 1-4 años, 5-11 años y mayores de 11 años).Se consideró disfagia cualquier valor de FOIS < 7 o síntomas de atragantamiento, impactación o aversión alimentaria.Resultados: Se obtuvieron datos de 63 pacientes. El 74% (47/63)presentó disfagia durante el seguimiento. La prevalencia fue del 50%< 1 año (media FOIS 4.32), 77% 1-4 años (media FOIS 5.61), 45% 5-11años (media FOIS 5.87) y 38% > 11 años (media FOIS 6.8). Las causasmás frecuentes de disfagia fueron la estenosis, que presentó un 38% delos pacientes (n= 24) y el reflujo gastroesofágico (n= 18), que presentóa su vez un 28% de los pacientes. Ambas condiciones se asociaron conunos valores medios de FOIS significativamente menores (p< 0,05) enlos pacientes menores de 11 años. Se encontraron diferencias (p< 0,05)en factores perinatales asociados a disfagia en los distintos periodosde edad, a destacar mayor tiempo medio de: asistencia ventilatoria,nutrición parenteral e ingreso hospitalario. Conclusiones: La disfagia es un síntoma extremadamente frecuentea cualquier edad en los pacientes intervenidos de atresia de esófago. Unseguimiento estandarizado y multidisciplinar es esencial para mejorarla calidad de vida de estos pacientes(AU)

Introduction: Dysphagia is defined as difficulty swallowing. Up to84% of patients undergoing esophageal atresia surgery have dysphagiabeyond the neonatal period. Materials and methods: A retrospective study of patients undergoing esophageal atresia surgery from 2005 to 2021 was carried out. TheFunctional Oral Intake Scale (FOIS) was used to assess dysphagia in 4age groups (< 1 year old, 1-4 years old, 5-11 years old, and 11 years old). FOIS scores < 7 or symptoms of choking, impaction, or food aversionwere regarded as dysphagia. Results: 63 patients were analyzed. 74% (47/63) had dysphagiaduring follow-up. Prevalence was 50% in patients < 1 year old (FOISmean 4.32), 77% in patients aged 1-4 (FOIS mean 5.61), 45% in patientsaged 5-11 (FOIS mean 5.87), and 38% in patients > 11 years old (FOISmean 6.8). The most frequent causes of dysphagia were stenosis, whichoccurred in 38% of the patients (n=24), and gastroesophageal reflux(n=18), which was present in 28% of the patients. Both conditions wereassociated with significantly lower mean FOIS scores (p< 0.05) in thepatients under 11 years of age. Differences (p< 0.05) were found in thedysphagia-associated perinatal factors in the various age groups, withlonger ventilation assistance times, parenteral nutrition, and hospital stays. Conclusions: Dysphagia is an extremely frequent symptom at anygiven age in patients undergoing esophageal atresia surgery. A standardized, cross-disciplinary follow-up is key to improve quality of life.(AU)

[Psychomotor development in late preterms at two years of age: a comparison with full-term newborn infants using two different instruments]. / Desarrollo psicomotor en prematuros tardios a los dos años de edad: comparacion con recien nacidos a termino mediante dos herramientas diferentes.

INTRODUCTION: Late preterm infants currently constitute 70% of preterm infant births. They present greater comorbidity, including neurodevelopment disorders, which may not manifest until the school age. AIM: To identify the existence of difficulties in the neurodevelopment at the age of two years. SUBJECTS AND METHODS: The psychomotor development was performed at two years of age in late preterm infants and term control group born at our center between January and September 2014, with Brunet-Lezine Revised test and Ages and Stages Questionnaires (ASQ-3) questionnaire. RESULTS: 88 children were included. Late preterm infants had lower scores in the language area and postural developmental. Girls achieved better results than males at global developmental age, oculo-motor coordination, language area and sociability. The ASQ-3 questionnaire detected differences in communication and socio-individual. Prematurity and male sex were identified as an independent risk factor to present a developmental disorder, prematurity for language impairment and male sex for younger developmental age and language impairment. The correlation between language assessment with the Brunet-Lezine Revised test and the ASQ-3 questionnaire was good, with a Pearson correlation coefficient of 0.7 (p < 0.001), showing the usefulness of the questionnaire. CONCLUSIONS: Late preterm infants have a lower developmental age in the language area at two years. Prematurity and male sex are risk factors for developmental disorder. Language assessment with the ASQ-3 questionnaire may be a useful tool to detect disorders and intervene early.

TITLE: Desarrollo psicomotor en prematuros tardios a los dos años de edad: comparacion con recien nacidos a termino mediante dos herramientas diferentes.Introduccion. Los prematuros tardios constituyen actualmente el 70% de los nacimientos prematuros. Presentan mayor comorbilidad, incluyendo las alteraciones del neurodesarrollo, que pueden no manifestarse hasta la escolarizacion. Objetivo. Identificar dificultades en el desarrollo neurologico a los dos años de edad. Sujetos y metodos. Se valoro el desarrollo psicomotor a los dos años de los prematuros tardios y del grupo control a termino nacidos en nuestro centro entre enero y septiembre del año 2014 mediante la escala de Brunet-Lezine revisada y el cuestionario de edades y etapas para la deteccion de trastornos del neurodesarrollo Ages and Stages Questionnaires (ASQ-3). Resultados. Se incluyo a 88 niños. Los prematuros tardios presentaron puntuaciones inferiores en el lenguaje y el desarrollo postural. Las niñas obtuvieron resultados superiores en la edad de desarrollo global, la coordinacion oculomotriz, el lenguaje y la sociabilidad. El cuestionario ASQ-3 detecto las diferencias en comunicacion y socioindividuales. Se identificaron como factores de riesgo para presentar alteracion del desarrollo la prematuridad, para alteracion del lenguaje, y el sexo masculino, para menor edad de desarrollo y alteracion del lenguaje. La correlacion entre la valoracion del lenguaje con la escala de Brunet-Lezine revisada y el cuestionario ASQ-3 fue buena, con un coeficiente de correlacion de Pearson de 0,7 (p < 0,001), lo que muestra la utilidad del cuestionario. Conclusiones. Los prematuros tardios presentan menor desarrollo del lenguaje a los dos años. La prematuridad y el sexo masculino son factores de riesgo para presentar alteracion. La valoracion del lenguaje con el cuestionario ASQ-3 puede ser util para detectar alteraciones.

Protocolo de actuación en atención primaria en la enfermedad inflamatoria intestinal en la edad pediátrica / Protocol of action in primary care in the pediatric inflammatory bowel disease

Dadas las características de la enfermedad inflamatoria intestinal de los pacientes pediátricos y las diferencias clínicas, es muy importante realizar un diagnóstico y tratamiento lo más precoz posible. El retraso en el inicio del tratamiento implica una menor respuesta al mismo y una evolución hacia una mayor gravedad. El trabajo conjunto desde los centros de salud y los niveles hospitalarios siempre resulta beneficioso para el paciente, a la vez que ayuda y acerca a los profesionales. En la literatura médica no se han documentado muchos protocolos dirigidos al diagnóstico precoz y el manejo de esta patología en pacientes pediátricos en atención primaria en coordinación con la atención hospitalaria

An early diagnosis and treatment in the pediatric inflammatory bowel disease is essential. Pediatric patients have special age-related features that make them different to de adults. Delayed beginning treatment implies a lower response and evolution towards a higher severity. A delayed treatment implies lower response and a worse illness outcome. Coordination between primary health care and tertiary care centers is mandatory to benefit the patients and to get better outcomes. This approach in the pediatric patients is not described in scientific papers

Nutrición parenteral en el paciente oncológico pediátrico y trasplante de médula ósea / Parenteral nutrition in pediatric oncological patient and hematopoietic stem cell transplantation

El enfermo oncológico es un paciente con alto riesgo de desnutrición. En este tipo de pacientes es prioritario el diseño de un soporte nutricional personalizado y precoz para conseguir una mejor tolerancia al tratamiento, una buena evolución en su enfermedad de base y una mejora de su calidad de vida. La nutrición parenteral queda reservada para cortos periodos en los que surgen complicaciones importantes durante la quimioterapia y la radioterapia (mucositis, enteritis...), pero es esencial en el trasplante de progenitores hematopoyéticos, así como en su complicación más importante, la enfermedad de injerto contra huésped, en que puede prolongarse durante largos periodos de tiempo. Es fundamental el conocimiento de las alteraciones metabólicas que tienen lugar, así como las variaciones en el gasto energético en reposo y la composición corporal para ajustar los aportes de forma segura y eficaz, minimizando las complicaciones (AU)

The oncological patient is at high risk of malnutrition. Early and personalized nutritional support is essential to improve tolerance to chemotherapy and achieve a better outcome and quality of life. Parenteral nutrition is usually reserved for short periods with major complications during chemotherapy and radiotherapy (mucositis, enteritis...) but it becomes essential in hematopoietic stem cell transplantation as well as in graftversushost disease. The knowledge of the metabolic alterations is essential, as well as the variations in resting energy expenditure and body composition to adjust the requierements in a safe and effective way, minimizing complications (AU)

Impacto de la instauración de un protocolo de actuación clínica ante el dolor abdominal en urgencias pediátricas / Impact of establishment of a clinical protocol for abdominal pain in pediatric emergencies

Objetivos: En enero de 2013 se implantó un protocolo de actuación para el manejo del dolor abdominal en el servicio de urgencias de pediatría, que pretendía reducir la realización de radiografías de abdomen no indicadas, disminuir la administración de enemas no indicados y aplicar una pauta de analgesia mayor. Se ha revisado el impacto del protocolo sobre la modificación de la práctica clínica y si estas variaciones se mantienen. Material y métodos: Estudio observacional, descriptivo, analítico y retrospectivo, realizado en 684 pacientes que acudieron al servicio de urgencias por presentar dolor abdominal de causa aparentemente no orgánica, distribuidos en cuatro periodos: diciembre de 2012 (P1), febrero de 2013 (P2), noviembre de 2013 (P3) y mayo de 2015 (P4). Se han recogido los datos sobre las pruebas diagnósticas realizadas y los tratamientos empleados en estos pacientes. Resultados: Radiografía abdominal: P1= 14,7%, P2= 6,9%, P3= 1,8%, P4= 0% (p <0,01); pacientes con estreñimiento: P1= 23,4%, P2= 13,5%, P3= 0%, P4= 0% (p= 0,001). Ecografía abdominal: P1= 11%, P2= 12,5%, P3= 9,4%, P4= 10,1% (p >0,05). Administración de enema en el servicio de urgencias: P1= 21,5%, P2= 8,3%, P3= 17,1%, P4= 11,7% (p= 0,005); pacientes con estreñimiento: P1= 51,1%, P2= 21,6%, P3= 31,3%, P4= 32,5% (p= 0,036). Tratamiento con polietilenglicol: P1= 4,3%, P2= 6,3%, P3= 9,8%, P4= 4,7% (p >0,05); pacientes con estreñimiento: P1= 12,8%, P2= 21,6%, P3= 40,6%, P4= 20,5% (p= 0,034). Pauta de analgesia: P1= 42,9%, P2= 53,5%, P3= 53,7%, P4= 62,7% (p= 0,02). Reconsultas al servicio de urgencias: P1= 10,4%, P2= 2,1%, P3= 1,8%, P4= 13% (p <0,01). Conclusiones: El protocolo ha logrado reducir de forma significativa la realización de radiografías abdominales y el empleo de enemas rectales. Ha aumentado la prescripción de analgesia en pacientes con dolor abdominal. El protocolo ha logrado homogeneizar la actuación de los profesionales, disminuyendo el riesgo de yatrogenia y aumentando el confort de los pacientes y sus familias (AU)

Objectives: In January 2013 a protocol for the management of abdominal pain at pediatric emergency was implanted, with the following objectives: reducing abdominal radiographs not indicated, reduce treatment with enemas not indicated and more prescription of analgesia. It has been reviewed the impact of the protocol on changing clinical practice and whether these variations are maintained. Material and methods: Retrospective, descriptive and analytical observational study with 684 patients attending emergency department for abdominal pain apparently no organic cause, divided into four periods: December 2012 (P1), February 2013 (P2), November 2013 (P3) and May 2015 (P4). We collected data about diagnostic tests performed and treatments used in these patients. Results: Abdominal radiography: P1= 14.7%, P2= 6.9%, P3= 1.8%, P4= 0% (p <0.01); constipated patients: P1= 23.4%, P2= 13.5%, P3= 0%, P4= 0% (p= 0.001). Abdominal ultrasound: P1= 11%, P2= 12.5%, P3= 9.4%, P4= 10.1% (p >0.05). Patients treated with rectal enema: P1= 21.5%, P2= 8.3%, P3= 17.1%, P4= 11.7% (p= 0.005); constipated patients: P1= 51.1%, P2= 21.6%, P3= 31.3%, P4= 32.5% (p= 0.036). Patients treated with polyethylenglycol: P1= 4.3%, P2= 6.3%, P3= 9.8%, P4= 4.7% (p >0.05); constipated patients: P1= 12.8%, P2= 21.6%, P3= 40.6%, P4= 20.5% (p= 0.034). Patients treated with analgesia: P1= 42.9%, P2= 53.5%, P3= 53.7%, P4= 62.7% (p= 0.02). Reconsultations the emergency department: P1= 10.4%, P2= 2.1%, P3= 1.8%, P4= 13% (p <0.01). Conclusions: The protocol has reduced significantly the performance of abdominal radiographs and use of rectal enemas. It has increased the prescription of analgesia in patients with abdominal pain. Protocol has managed to standardize the medical intervention, reducing the risk of iatrogenic and increasing comfort for patients and their families (AU)

Síndrome de realimentación en pediatría: clínica, diagnóstico, prevención y tratamiento / Refeeding syndrome in children: symptoms, diagnosis, prevention and management

El síndrome de realimentación es un proceso fisiopatológico asociado a trastornos de la glucosa y desequilibrio hidroelectrolítico que involucran principalmente a los iones intracelulares (fosfato, potasio y magnesio). Este síndrome se asocia con el soporte nutricional (oral, enteral o parenteral) en pacientes con riesgo de desnutrición o con desnutrición severa. Es muy importante valorar la presencia de factores de riesgo, estudiar los iones séricos e iniciar la alimentación de manera progresiva. El apoyo nutricional correcto es fundamental, con la supervisión diaria de los electrólitos séricos, los signos vitales y el equilibrio de líquidos, así como un correcto diseño del soporte nutricional (AU)

Refeeding syndrome (RFS) is a term that describes the metabolic and clinical changes that occur on aggressive nutritional rehabilitation of a malnourished patient. A shift from carbohydrate metabolism to fat and protein catabolism occurs. Hypophosphatemia is the hallmark of RFS. Other electrolyte abnormalities are associated with RFS, however, such as hypokalemia and hypomagnesemia. RFS is associated to any nutritional support (more frequently to parenteral nutrition) in malnourished patients'. A proper nutritional support is required to avoid RFS, checking daily liquid balance, electrolytes and vital signs (AU)

La Unidad de Gastroenterología, Hepatología y Nutrición Pediátrica del Hospital Infantil Universitario Miguel Servet / Pediatric Gastroenterology, Hepatology and Nutrition Unit of the Hospital Infantil Universitario Miguel Servet

La gastroenterologia pediátrica es una especialidad amplia que incluye las patologías del tubo digestivo, pancreas e hígado, ademas de la nutrición infantil. En los ultimos años, ha adquirido relevancia la realización de técnicas complementarias como la endoscopia digestiva, la videofluoroscopia y el analisis corporal por impedanciometría. La Unidad de Gastroenterologia, Hepatologia y Nutrición Pediátrica del Hospital Infantil Miguel Servet es Unidad de referencia de la Comunidad de Aragón. En este artículo se refleja la estructura, pruebas complementarias y la actividad asistencial, docente e investigadora (AU)

Pediatric Gastroenterology and Nutrition is an intricate speciality that involves the gastrointestinal tract, liver and pancreas pathologies, but also, the children’s nutrition. In our speciality, every year it’s becoming more important to perform examination procedures, as endoscopy, videofluoroscopy or bioelectrical impedance analysis. The Miguel Servet Children’s Hospital Pediatric Gastroenterology, Hepatology and Nutrition Unit is a reference unit in the Aragon Community. This paper shows the Unit structure, the examination procedures and our teaching and research activity (AU)

Lactancia artificial y leches especiales: usos y controversias / No disponible

No disponible

MAP65/Ase1 promote microtubule flexibility.

Microtubules (MTs) are dynamic cytoskeletal elements involved in numerous cellular processes. Although they are highly rigid polymers with a persistence length of 1-8 mm, they may exhibit a curved shape at a scale of few micrometers within cells, depending on their biological functions. However, how MT flexural rigidity in cells is regulated remains poorly understood. Here we ask whether MT-associated proteins (MAPs) could locally control the mechanical properties of MTs. We show that two major cross-linkers of the conserved MAP65/PRC1/Ase1 family drastically decrease MT rigidity. Their MT-binding domain mediates this effect. Remarkably, the softening effect of MAP65 observed on single MTs is maintained when MTs are cross-linked. By reconstituting physical collisions between growing MTs/MT bundles, we further show that the decrease in MT stiffness induced by MAP65 proteins is responsible for the sharp bending deformations observed in cells when they coalign at a steep angle to create bundles. Taken together, these data provide new insights into how MAP65, by modifying MT mechanical properties, may regulate the formation of complex MT arrays.

Soporte nutricional en la enfermedad renal crónica / Nutritional support in chronic kidney disease

Los niños con una enfermedad renal crónica tienen un alto riesgo de desnutrición y requieren un soporte nutricional especializado, sobre todo en un estadio de la enfermedad mayor o igual a 2. La pérdida de función de un órgano metabólicamente tan activo entraña alteraciones en el metabolismo intermediario de los nutrientes, así como en la biodisponibilidad y la pérdida de éstos. El riñón enfermo tiene una pérdida de función progresiva en la que están implicados muchos factores, entre los que el factor nutricional es importante. El retraso de crecimiento es la afectación más importante durante la infancia. La alteración depende del grado de afectación y de la edad del paciente. El riesgo es mayor cuando la enfermedad es congénita, porque durante el primer año la velocidad de crecimiento es muy alta y los requerimientos nutricionales muy elevados y de difícil cobertura. Las alteraciones motoras del tracto gastrointestinal producen anorexia y vómitos que dificultan la ingesta; por ello, estos pacientes frecuentemente requieren suplementación nutricional y una nutrición enteral prolongada mediante gastrostomía, que en general es endoscópica percutánea (AU)

Children with chronic kidney disease are vulnerable to malnutrition, needing specific nutritional support to prevent it, especially when the disease is in a phase greater than 2 the loss of the function of such an active organ metabolically causes alteration in the intermediary metabolism of the nutrients, as well as in the nutrient bioavailability and losses. Several factors are involved in the progressive loss of renal function, and nutritional factors are very important. Growth retardation is the most important affectation during childhood; the alteration depends in the degree of affectation and the patient’s age. The risk is greater when the disease is congenital because during the first year the speed of the growth is very high and the nutritional requirements are very high and of very difficult coverage. The changes in motor skills of the gastrointestinal tract cause anorexia and vomits that cause difficulty in the consumption, due to this reason they frequently need nutritional supplementation and prolonged enteral nutrition through gastrostomy, which is generally percutaneous endoscopic (AU)

Cálculo de los requerimientos energético-proteicos para el soporte nutricional en la práctica clínica / Estimation of energy and protein requirements to design nutritional support in clinical practice

La estimación precisa de los requerimientos de energía es muy importante cuando se programa un soporte nutricional; un adecuado aporte nutritivo contribuirá a un mejor manejo clínico. Además, los pacientes pediátricos necesitan tener un adecuado aporte de proteínas, que cubra los requerimientos necesarios para el crecimiento. La última meta del soporte nutricional en los lactantes y niños es lograr una retención nitrogenada y un balance de energía neutro. El gasto energético basal (GEB) es el parámetro más representativo del metabolismo y el principal componente del gasto energético total diario. Cuando las técnicas de calorimetría no están disponibles, existen ecuaciones predictivas que pueden aplicarse para determinar su valor. Para estimar el gasto de energía diario, el GEB debe multiplicarse por el factor de nivel de actividad física, que incluye el gasto de energía debido a la actividad física, crecimiento y respuesta metabólica a los alimentos. En caso de enfermedad, existen posibles cambios en el GEB y el nivel de actividad física, así como una inusual pérdida de energía, que deben tenerse en cuenta cuando se tratad e encontrar los requerimientos de energía. Entre las necesidades adicionales en el caso de pacientes malnutridos se incluye la energía necesaria para la recuperación nutricional. En este trabajo se comentan distintos aspectos relacionados con los requerimientos de energía y proteínas estimados en la lactancia y la niñez (AU)

Accurate estimation of energy requirements is important when programming nutritional support, as adequate nutrient intake will contribute to a better clinical course. In addition, pediatric patients need to maintain a proper protein intake, necessary to meet their growth requirements. The ultimate aim of nutritional support in infants and children is to achieve nitrogen retention and neutral energy balance. Basal metabolic rate (BMR) is the most representative parameter of metabolism and represents the major component of energy expenditure. When calorimetry techniques are not available, predictive equations can be applied to determine its value. To estimate daily total energy expenditure, BMR can be multiplied by the physical activity level factor, which includes the energy expenditure derived from physical activity, growth and metabolic response to food. In case of illness, possible changes in BMR and physical activity level, as well as unusual energy losses, must be taken into account when estimating energy requirements. Additional needs of malnourished patients include the necessary energy for nutritional recovering. Different aspects concerning the estimation of energy and protein requirements in infants and children are discussed in this issue (AU)

Valoración sistematizada del estado nutricional / Systematized assessment of nutritional status

La valoración del estado nutricional consiste en la cuantificación de los depósitos energéticos y su contenido proteico, con el objetivo de determinar la presencia o el riesgo de malnutrición por defecto (desnutrición) o por exceso (obesidad) y aportar herramientas preventivas y terapéuticas en los casos en que sea necesario. Para su evaluación existen diversos niveles de complejidad, con aspectos básicos que deben ser incluidos en la historia clínica y en la exploración física, haciendo hincapié en los estigmas de malnutrición. La determinación de la composición corporal puede realizarse mediante pruebas antropométricas muy sencillas, como el peso, la talla, el perímetro braquial o los pliegues grasos, o con herramientas más complejas, entre las que destaca la bioimpedancia eléctrica. Cuando existe posibilidad de malnutrición en un paciente, es fundamental la valoración de su ingesta dietética, sobre todo mediante el registro dietético de 24 horas, así como del gasto energético y de las pérdidas de macro/micronutrientes. Las pruebas bioquímicas pueden aportar información útil tanto de la situación nutricional global como de los déficit concretos. La detección del riesgo nutricional mediante métodos subjetivos de cribado sencillos no ha sido aún suficientemente validada en pediatría. Pese a ello, existen ya métodos propuestos para su realización que podrían permitir el cribado sistemático nutricional en la práctica clínica (AU)

Nutritional assessment involves the measurement of the energy store and protein content of the organism, which goal is to determine the risk or presence of malnutrition by defect or obesity by excess, and to provide the necessary tools to prevent and treat it. For the evaluation there exist different levels of complexity, with basic aspects that shall be included in the medical history and in the physical examination, with special emphasis on malnutrition signs. The study of the body composition can be carried out using simple anthropometric measurements such as weight, height, brachial perimeter or the thick skin fold; more complex devices are also available, like the bioelectrical impedance analysis. When there exists a malnutrition risk, an evaluation of energy intake is very important, e.g. with the 24-hourdiet recall, and of energy expenditure and macro and micronutrients losses should be performed. The biochemical tests can provide useful information concerning both global nutritional status and the essential elements status. Nutritional screening, performed through subjective butstraight forward methods, have not been applied in pediatrics yet. Anyway, several tools have been currently proposed, which could allow the desirable goal of the systematic nutritional screening in the future for clinical practice (AU)

Effects of confinement on the self-organization of microtubules and motors.

The regulation of the cytoskeleton is essential for the proper organization and function of eukaryotic cells. For instance, radial arrays of microtubules (MTs), called asters, determine the intracellular localization of organelles. Asters can be generated through either MT organizing center (MTOC)-dependent regulation or self-organization processes. In vivo, this occurs within the cell boundaries. How the properties of these boundaries affect MT organization is unknown. To approach this question, we studied the organization of microtubules inside droplets of eukaryotic cellular extracts with varying sizes and elastic properties. Our results show that the size of the droplet determined the final steady-state MT organization, which changed from symmetric asters to asymmetric semi-asters and, finally, to cortical bundles. A simple physical model recapitulated these results, identifying the main physical parameters of the transitions. The use of vesicles with more elastic boundaries resulted in very different morphologies of microtubule structures, such as asymmetrical semi-asters, "Y-branching" organizations, cortical-like bundles, "rackets," and bundled organizations. Our results highlight the importance of taking into account the physical characteristics of the cellular confinement to understand the formation of cytoskeleton structures in vivo.

Water-soluble pegylated quantum dots: from a composite hexagonal phase to isolated micelles.

We present a simple method based on the dispersion of fluorescent quantum dots (QD) into a liquid crystal phase that provides either nanostructured material or isolated QD micelles depending on water concentration. The liquid-crystal phase was obtained by using a gallate amphiphile with a poly(ethylene glycol) chain as the polar headgroup, named I. The hydration of QD/I mixtures resulted in the formation of a composite hexagonal phase identified by small-angle X-ray scattering and by polarized light and fluorescence optical microscopy, showing a homogeneous distribution of fluorescence within hexagonal phase. This composite mesophase can be converted into isolated QD-I micelles by dilution in water. The fluorescent QD-I micelles, purified by size exclusion chromatography, are well monodisperse with a hydrodynamic diameter of 20-30 nm. Moreover, these QD do not show any nonspecific adsorption on lipid or cell membranes. By simply adjusting the water content, the PEG gallate amphiphile I provides a simple method to prepare a self-organized composite phase or pegylated water soluble QD micelles for biological applications.

Reconstitution of physiological microtubule dynamics using purified components.

Microtubules are dynamically unstable polymers that interconvert stochastically between polymerization and depolymerization. Compared with microtubules assembled from purified tubulin, microtubules in a physiological environment polymerize faster and transit more frequently between polymerization and depolymerization. These dynamic properties are essential for the functions of the microtubule cytoskeleton during diverse cellular processes. Here, we have reconstituted the essential features of physiological microtubule dynamics by mixing three purified components: tubulin; a microtubule-stabilizing protein, XMAP215; and a microtubule-destabilizing kinesin, XKCM1. This represents an essential first step in the reconstitution of complex microtubule dynamics-dependent processes, such as chromosome segregation, from purified components.

XMAP215 regulates microtubule dynamics through two distinct domains.

XMAP215 belongs to a family of proteins involved in the regulation of microtubule dynamics. In this study we analyze the function of different parts of XMAP215 in vivo and in Xenopus egg extracts. XMAP215 has been divided into three fragments, FrN, FrM and FrC (for N-terminal, middle and C-terminal, respectively). FrN co-localizes with microtubules in egg extracts but not in cells, FrC co- localizes with microtubules and centrosomes both in egg extracts and in cells, while FrM does not co- localize with either centrosomes or microtubules. In Xenopus egg extracts, FrN stimulates microtubule growth at plus-ends by inhibiting catastrophes, while FrM has no effect, and FrC suppresses microtubule growth by promoting catastrophes. Our results suggest that XMAP215 is targeted to centrosomes and microtubules mainly through its C-terminal domain, while the evolutionarily conserved N-terminal domain contains its microtubule-stabilizing activity.

Structural transitions at microtubule ends correlate with their dynamic properties in Xenopus egg extracts.

Microtubules are dynamically unstable polymers that interconvert stochastically between growing and shrinking states by the addition and loss of subunits from their ends. However, there is little experimental data on the relationship between microtubule end structure and the regulation of dynamic instability. To investigate this relationship, we have modulated dynamic instability in Xenopus egg extracts by adding a catastrophe-promoting factor, Op18/stathmin. Using electron cryomicroscopy, we find that microtubules in cytoplasmic extracts grow by the extension of a two- dimensional sheet of protofilaments, which later closes into a tube. Increasing the catastrophe frequency by the addition of Op18/stathmin decreases both the length and frequency of the occurrence of sheets and increases the number of frayed ends. Interestingly, we also find that more dynamic populations contain more blunt ends, suggesting that these are a metastable intermediate between shrinking and growing microtubules. Our results demonstrate for the first time that microtubule assembly in physiological conditions is a two-dimensional process, and they suggest that the two-dimensional sheets stabilize microtubules against catastrophes. We present a model in which the frequency of catastrophes is directly correlated with the structural state of microtubule ends.

Organisation and structure of microtubules and microtubule-motor protein complexes.

We present a short overview of the current status of work on the organisation and structure of microtubules and of microtubule-motor protein complexes. At present there is great interest in obtaining structural information that can help us to understand the movement of the kinesin family of microtubule associated molecular motors. Using electron cryomicroscopy and image reconstruction methods three dimensional maps of microtubule-motor complexes have been obtained in the presence of different nucleotides. We address a number of principles involved in different aspects of this work.

Nucleotide-dependent conformations of the kinesin dimer interacting with microtubules.

BACKGROUND: Kinesins are crucial to eukaryotic cells. They are a superfamily of motor proteins that use ATP hydrolysis to move along microtubules. Many of these motors are heterotetramers with two heavy and two light chains. The heavy chain has a globular motor domain that interacts with microtubules and shows a similar sequence throughout the family. Compared with myosin and dynein, kinesin provides a 'simple' model for understanding molecular motors. RESULTS: Electron cryomicroscopy and three-dimensional reconstruction methods have been used to investigate microtubule-kinesin dimer complexes in different nucleotide states. Three-dimensional maps were obtained in the presence of 5'-adenylylimidodiphosphate (AMP-PNP), ADP-AIF4, ADP and apyrase. In all cases, kinesin has one attached and one free head per tubulin heterodimer. The attached heads appear very similar whereas the free heads show distinct conformations and orientations depending on their nucleotide states. CONCLUSIONS: The kinesin dimer is likely to undergo considerable conformational changes during its ATP hydrolysis cycle. In all nucleotide states, the kinesin dimer attaches to a microtubule using one motor domain with the other motor domain hanging free. Only the free domain changes conformation in the presence of different nucleotides, suggesting that it, or the region linking both motor domains to the coiled coil, is the determinant of directionality. These results give some structural clues as to how kinesin moves along microtubules and we describe possible models of kinesin movement based on currently available data.