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Polylactic acid/Mg composites have been recently proposed for biodegradable osteosynthesis devices because, with regards to the neat polymer, they combine an enhanced biocompatibility and bioactivity with better mechanical properties, particularly creep strength. A question still arises about their bacterial behavior. For this purpose, composites of poly-L-D-lactic acid (PLDA) loaded with 1 and 10 wt.% of Mg microparticles were evaluated using Staphylococcus epidermidis, with special emphasis on the study of bacterial adhesion and biofilm formation. During biofilm formation the bacteria viability of the composites decreased up to 65.3% with respect to PLDA. These antibacterial properties do not compromise the cytocompatibility of the material as the composites enhanced the viability of mesenchymal stem cells and their osteogenic commitment. These findings provide an important added value to the biodegradable and biocompatible PLDA/Mg composites for the manufacture of osteosynthesis devices.

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This work deals with the mechanical characterization by depth-sensing indentation (DSI) of PLLA and PLDA composites reinforced with micro-particles of Mg (up to 15wt%), which is a challenging task since the indented volume must provide information of the bulk composite, i.e. contain enough reinforcement particles. The composites were fabricated by combining hot extrusion and compression moulding. Physico-chemical characterization by TGA and DSC indicates that Mg anticipates the thermal degradation of the polymers but does not compromise their stability during processing. Especial emphasis is devoted to determine the effect of strain rate and Mg content on mechanical behavior, thus important information about the visco-elastic behavior and time-dependent response of the composites is obtained. Relevant for the intended application is that Mg addition increases the elastic modulus and hardness of the polymeric matrices and induces a higher resistance to flow. The elastic modulus obtained by DSI experiments shows good agreement with that obtained by uniaxial compression tests. The results indicate that DSI experiments are a reliable method to calculate the modulus of polymeric composites reinforced with micro-particles. Taking into consideration the mechanical properties results, PLA/Mg composite could be used as substitute for biodegradable monolithic polymeric implants already in the market for orthopedics (freeform meshes, mini plates, screws, pins, …), craniomaxillofacial, or spine.

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In the field of bioabsorbable composites for biomedical applications, extrusion has been employed as a method to prepare homogeneous blends of polymeric matrices with bioactive ceramic fillers. In this work, the suitability of processing poly-l-lactic acid/Magnesium (PLLA/Mg) composites by hot extrusion has been assessed by a systematic characterization of PLLA/Mg composites containing different amounts of Mg particles up to 7wt%. The results show that extrusion causes a reduction of almost 20% in the viscosity average molecular weight of PLLA, which further decreases with increasing Mg content. Extrusion gave always rise to a homogeneous distribution of Mg particles within the PLLA matrix. This composite processing was not compromised by the degradation of the polymeric matrix because the processing temperature was always below the onset degradation temperature. In the processing conditions employed in the present work, degradation of the composite slightly increases as more Mg is added up to 5wt%, but is very high at 7wt%. This was also evident from the mechanical behaviour, so that Mg particles improved the stiffness and compression strength of neat PLLA until 5wt% of Mg content, which dropped drastically when the material had 7wt% of Mg. The filler strengthening factor decreases with the increment in Mg content. In order to obtain an optimised contribution of Mg particles, a balance between thermal degradation and mechanical resistance of PLLA must be achieved.

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Absorbable medical devices must be developed in order to have an appropriate degradation rate in agreement with the healing rate of bone in the implantation site. In this work, biodegradable composites formed by a polylactic acid matrix reinforced with 10%wt. magnesium microparticles were processed and their in vitro degradation investigated during 28 days. A joint analysis of the amount of H2 released, the changes in pH in buffered (PBS) and non-buffered media (distilled water), the variations in mass, microstructure and the mechanical performance of the specimens was developed. The main aim was to elucidate the relevance of Mg particles shape on tailoring the degradation kinetics of these novel composites. The results show that the shape of the Mg reinforcing particles plays a crucial role in the degradation rate of PLA/Mg composites, with spherical particles promoting a lower degradation rate than irregular particles. This fact is only partially due to the smaller surface area to volume ratio of the spherical particles. Irregular particles promote a faster formation of cracks and, therefore, an increasingly faster degradation of the polymeric matrix. In every case, the amount of H2 released by the composites was well below that released by monolithic Mg. The pH of PBS during degradation remained always within 7.2 and 7.4. PLA/Mg reinforced with spherical particles retains more than 90% of its mechanical properties after 7 days of immersion and more than 60% after 28 days. STATEMENT OF SIGNIFICANCE: The increasing demand for temporary orthopaedic implants is the driving force to seek new strategies to decrease costs and simultaneously improve patients comfort as well as simplify surgical procedures. Resorbable medical devices must be developed in order to have an appropriate degradation rate in agreement with the healing rate of bone. We are presenting for the first time results of the degradation kinetics of a new material based on polylactic acid reinforced with 10%wt. Mg microparticles. This work analyzes the relevance of Mg particle shape (irregular and spherical) on tailoring the degradation behaviour of these composites. Conclusions withdrawn from this study help to customize bioabsorbable materials in order to meet the requirements for a specific application and patient.

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Introducción: El objetivo principal de este trabajo es conocerlas características neuropsicológicas de un grupo de niños prematuros y con bajo peso al nacimiento, teniendo en cuenta su heterogeneidad y sus rasgos comunes, la gravedad de los síntomas y la necesidad de recibir cuidados específicos. Pacientes y métodos: El grupo estaba formado por 73 sujetos en total, 33 niños y 40 niñas. El número de sujetos en el grupo de bajo peso (GBP) fue de 23 y el del grupo control (GC) de 50. La media de edad en el momento de la recogida de datos fue de 32,65 meses en el GBP y de 31,9 meses para el GC. El estatus socioeconómico de ambos grupos era de tipo medio. Los estadísticos descriptivos de ambos grupos son: «semanas de gestación» con grupo pretérmino (<32 semanas) y grupo control (>37 semanas) y, «peso al nacimiento» con grupo de bajo peso (<1.500 g) y grupo control (>2.500 g). Se evaluó a los participantes mediante una batería de pruebas neuropsicológicas creada específicamente para este estudio. Resultados: El GC obtuvo mejores resultados en casi todas las funciones, pero no todas resultaron estadísticamente significativas, sólo «articulación, lenguaje expresivo y reconocimiento de figuras». Por el contrario, el GBP obtuvo resultados estadísticamente significativos en «reconocimiento de colores». Conclusiones: Se postula la necesidad de realizar un diagnóstico neuropsicológico precoz en los niños de bajo peso al nacer por pertenecer a una población de alto riesgo(AU)

Introduction: The primary target of this work is to know the neuropsychological characteristics of one premature children and with low weight in the birth group, considering it's heterogeneity, common characteristics, the gravity of the symptoms and the necessity to receive specific cares. Patients and methods: The total group is formed by 73 subjects, 33 males and 40 females. The number of subjects of low weight group (LWG) are 23 and the subjects of control group (CG) 50. The average ages at the time of the sample were of 32.65 months, GBP and of 31.9 months GC. The socioeconomic status of both groups were average type. Statistical descriptive of both groups are "weeks of gestation" with the group preterm (<32 weeks) and the control group (>37 weeks) and "weight in the birth", the group of very low weight (<1,500 g) and the control group (>2,500 g). The subjects are evaluated through a neuropsychological battery of tests created for this study. Results: The LWG obtains better results in almost functions but not all are statistically significant, only "articulation, expressive language and recognition of figures". In the other way, the CG obtains statistically significant results in "recognition of colors". Conclusions: We postulate the necessity to realise a precocious neuropsychologycal diagnostic in the children with low weight birth because they belong to a high-risk group(AU)

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UNLABELLED: Intravenous fluids administration is the usual practice in the postoperative period. Nonetheless, consensus about the more appropriate fluid reposition recipe is still insufficient. OBJECTIVE: To study the type of intravenous reposition used in Surgical Units and its impact on the internal milieu. DESIGN: prospective study of 112 patients with scheduled surgery, receiving only intravenous fluids. METHODS: biochemical study on postoperative fluids management in uncomplicated surgery. Principal variables: 1. Water and electrolytes administrated. 2. Differences in sodium/water balances before surgery vs first day after surgery. 3. Symptoms related to hyponatremia. RESULTS: Median P[Na] before and after surgery was 139.9+/-2.9 and 137.7+/-3.7, respectively (p<0.01). Fourteen patients (12.5%) had P[Na]<135, and 12 of them had a reduction of more than 6 mmol/L; accordingly, twenty-six patients (23.2%) had an increased free-water retention (p<0.05). Relevantly, they did not receive a higher amount of free-water and the proportion of isotonic saline/free water varied from <1 to >3. As possible mechanism of free-water accumulation: the postoperative P[Na] was lower in the patients who had a negative free-water clearance >or= -1 L (136.7+/-4.1 vs 138.5+/-3.2 mmol/L, p 0.015). CONCLUSION: The present study provides new information about the intravenous fluids prescribed in postoperative patients, ie, different proportions saline/water are basically equivalent with respect to inducing symptomatic hyponatremia. The mean value of the relation saline/water is 2:1. Hypotonic fluids input is not clearly related to more intense hyponatremia; the latter appears to depend more on a reduced capacity of the kidney to generate sufficient free water output.

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La prescripción de sueros en el postoperatorio es una práctica rutinaria, pero sobre la que no existe un consenso basado en la evidencia. Objetivo: Examinar sistemáticamente el tipo de reposición hidroelectrolítica empleado por los Servicios Quirúrgicos y sus consecuencias sobre el medio interno. Pacientes y métodos: Diseño: estudio prospectivo en 112 pacientes con cirugías programadas. Método: estudio bioquímico del manejo hidroelectrolítico en postoperatorios no complicados tratados solo con sueros intravenosos. Variables principales: 1. agua y electrolitos administrados; 2. Diferencias de equilibrio hidrosalino entre pre- y post-operatorio;3. alteraciones clínicas atribuíbles a hiponatremia. Resultados: La [Na]P media pre y postoperatoria fue 139,9± 2,9 y 137,7 ± 3,7, respectivamente (p < 0,01) Catorce pacientes(12,5%) alcanzaron [Na]P < 135 mmol/L, y 12 presentaron un descenso de [Na]P ≥ 6 mmol/L, vg, 26 sujetos(23,2%) tuvieron un incremento significativo de agua libre(p < 0,05) Estos pacientes no habían recibido mayor cantidad de agua libre que el resto, siendo la proporción sueros isotónicos/agua libre desde < 1 a > 3. Como posible mecanismo de la retención hídrica, la [Na]P postoperatoria en los pacientes con aclaramiento de agua libre negativo ≥ -1litro/24 h fue más baja (136,7 ± 4,1 vs 138,5 ± 3,2 mmol/L,p 0,015). Conclusiones: Se aporta información previamente no disponible: a) diversas proporciones de suero isotónico: agua libre resultaron equivalentes frente al desarrollo de hiponatremia sintomática; b) la relación media suero isotónico: agua libre es 2:1, y c) las soluciones de reposición más hipotónicas no aparecen relacionadas con más hiponatremias. Éstas en cambio dependen de la respuesta renal de retención de agua (AU)

Intravenous fluids administration is the usual practice in the post operative period. Nonetheless, consensus about the more appropriate fluid reposition recipe is still insufficient. Objective: To study the type of intravenous reposition used in Surgical Units and its impacton the internal milieu. Patients and methods: Design: prospective study of 112 patients with scheduled surgery, receiving only intravenous fluids. Methods: biochemical study on postoperative fluids management in uncomplicated surgery. Principal variables: 1. Water and electrolytes administrated. 2. Differences in sodium/water balances before surgery vs first day after surgery. 3. Symptoms related to hyponatremia. Results: Median P[Na] before and after surgery was 139.9 ± 2.9 and 137.7 ± 3.7, respectively (p< 0.01). Fourteen patients (12.5%) had P[Na] < 135, and 12 ofthem had a reduction of more than 6 mmol/L; accordingly, twentysix patients (23.2%) had an increased free-water retention (p <0.05). Relevantly, they did not receive a higher amount of freewater and the proportion of isotonic saline/free water varied from< 1 to > 3. As possible mechanism of free-water accumulation: the postoperative P[Na] was lower in the patients who had a negative free-water clearance ≥ -1 L (136,7 ± 4,1 vs 138,5 ± 3,2 mmol/L, p0,015). Conclusion: The present study provides new information about the intravenous fluids prescribed in postoperative patients, ie, different proportions saline/water are basically equivalent with respect to inducing symptomatic hyponatremia. The mean value of the relation saline/water is 2:1. Hypotonic fluids input is not clearly related to more intense hyponatremia; the latter appears to depend more on a reduced capacity of the kidney to generate sufficient free water output (AU)

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Se presenta el caso de una paciente con embarazo cervical, la dificultad diagnóstica ultrasonográfica, lo difícil de tomar una decisión terapéutica adecuada, su evolución y resultado final.

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Spirometry, the most used test to evaluate pulmonary function, is only occasionally measured in field epidemiological studies. Our aim was to determine which of the following factors in the Platino study can be associated low quality spirometries in the first session: sex, age, socioeconomic level, educational level, body mass index, cold chill, smoking, operating technician, date and subject's previous spirometric experience. 1.168 individuals were evaluated with spirometry. Fifteen nurses and 1 midwife were trained according to NIOSCH standards. Easy One NDD spirometers were used. 1.037 subjects (88.8 percent) performed a satisfactory spirometry in the first session, and 131 (11.2 percent) failed to do so. Only two significant predictors of this failure were identified: age and educational level. Causes for test repetition were 1) Non satisfactory acceptability (77.1 percent); 2) lack of reproducibility (67.9 percent); 3) decline of post bronchodilator CVF without concomitant change in VEF1 (36.6 percent). Eighty nine of the 131 subjects accepted to repeat the test. A satisfactory spirometry was obtained in 79 subjects. Hence, at the end of the study 95.5 percent of the subjects attained a satisfactory test. We conclude that personnel without experience, with appropriate training, can perform high quality field spirometries. Acceptability and repoducibility were the most sensitive factors associated with a bad performance of spirometry. Age and schooling were the main factors related with a low quality spirometry. No association was detected regarding technician as a predictor of low quality spirometries carried out in a population setting.

La espirometría es el examen más utilizado para evaluar la función pulmonar y ocasionalmente se usa en estudios epidemiológicos. Evaluamos si las variables: sexo, edad, nivel socioeconómico, escolaridad, IMC, cursar concomitantemente con resfrío, tabaquismo, fecha del examen, haberse efectuado espirometría anteriormente y técnico responsable, se asociaban con la probabilidad de espirometrías insatisfactorias en una primera sesión. Quince enfermeras y una matrona que recibieron capacitación realizaron las espirometrías en 1.168 sujetos empleando un espirómetro Easy One NDD. En la primera sesión 1.037 individuos (88,8 por ciento) efectuaron una espirometría satisfactoria fracasando 131 (11,2 por ciento). Se identificaron dos variables predictoras del fracaso: edad y años de instrucción. Las causas más frecuentes de espirometrías insatisfactorias fueron: 1) No cumplir con criterios de aceptabilidad (77,1 por ciento); 2) Falta de reproducibilidad (67,9 por ciento); 3) Caída de CVF post broncodilatador sin cambio en el VEF1 (36,6 por ciento). De los 131 sujetos cuya espirometría fue insatisfactoria en la primera sesión, ochenta y nueve aceptaron repetirla, lográndose al final del estudio una espirometría satisfactoria en el 95,5 por ciento de la muestra. Personal técnico sin experiencia previa y adecuadamente entrenado, es capaz de lograr espirometrías de buena calidad en un estudio epidemiológico de campo. Las causas más frecuentes de repetición de examen guardan relación con dificultad de alcanzar criterios de aceptabilidad y reproducibilidad de la prueba. Factores gravitantes en la repetición son la edad y el nivel de instrucción de los sujetos examinados. El desempeño de los técnicos no constituyó un factor limitante para obtener una adecuada calidad de la espirometría en terreno.

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Introducción: No existe abundante literatura sobre morbilidad del cierre de la ileostomía en asa. En Chile, hay sólo 2 comunicaciones. Objetivo: Medir las complicaciones del cierre de la ileostomía en asa, compararlas con las de la literatura, y con la morbilidad del cierre de colostomía en asa publicado por nosotros el año 2000. Material y Método: 57 pacientes: 35 mujeres (61,4 por ciento) y 22 hombres (38,6 por ciento), fueron operados entre 1992 y 2002, empleando técnica manual. Morbilidad fue registrada hasta los 30 días. Resultados: 7 pacientes presentaron complicaciones (12,3 por ciento): 3 íleos (5,3 por ciento) resueltos médicamente; 3 obstrucciones intestinales (5,3 por ciento) y 1 perforación del asa eferente (1,7 por ciento) que fueron reoperadas (7,1 por ciento). No hubo infección de herida operatoria, ni mortalidad. Conclusiones: Nuestra morbilidad en cierre de ileostomía en asa, es semejante a la de la literatura. Sin embargo ella es mayor que la del cierre de la colostomía en asa de nuestra serie histórica de 75 casos (morbilidad 6 por ciento y reoperación 1,3 por ciento).

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Se presenta la experiencia de 1046 cirugías laparoscópicas ginecológica del Servicio de Obstetricia y Ginecología del Hospital El Pino, desde julio de 1995 a diciembre de 2003. El 40,5 por ciento correspondieron a esterilizaciones tubarias, nivel de complejidad tipo 1 y las restantes a niveles de complejidad tipo 2 y 3. Se reportan los resultados y las complicaciones mayores.

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Se presenta la experiencia clínica en el abordaje quirúrgica por vía laparoscópica de 40 mujeres portadoras de miomas intramurales y subserosos. Se describe la preparación preoperatoria, técnica quirúrgica, sutura intracorpóreas, extracción del mioma por morcelación, evolución postoperatoria y complicaciones

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La incorporación de fluoruros a las amalgamas de uso dental pretenden prevenir la aparición de caries marginales, que es una de las mayores causas de fallas de estas restauraciones. El propósito de este trabajo fue evaluar clínica y radiográficamente el comportamiento de una amalgama convencional fluorada con SnF2, respecto a ella misma sin fluoruros. A 25 niños entre 9 y 15 años se les realizaron, con sistema doble ciego, 38 restauraciones de amalgama experimental y 38 con el control, evaluando a los dos años, según esquema de Duperon modificado, la presencia de: caries marginal, corrosión, fracturas marginales y de cuerpo. Se utilizó el análisis de varianza de dos clasificaciones por rango de Friedman, para determinar diferencias entre ellas. El análisis estadístico indicó una diferencia significativa (p < 0.001) entre ambas amalgamas, presentando un ligero mejor comportamiento ante las caries marginales la amalagama fluorada, pero siendo tambión mayor su corrosión

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We report a child affected with the Romano-Ward syndrome (long QT, normal hearing), born from a mother affected with the Jervell and Lange-Nielsen syndrome (long QT plus deafmutism). We discuss the possible pathogenetic reasons for this uncommon association.

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