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This work investigates the effect of vanadium carbide (VC) content and bulk hardness on the low angle impingement/scouring erosion of tool steels. Five grades of CPM xV (x = 1, 3, 9, 10, and 15) tool steels have been studied using a Coriolis erosion tester with a slurry of 10 wt% AFS 50–70 silica sand in water. The results showed that the scouring erosion resistance of the steels increases with increase in VC volume fraction and the increase is much more rapid when the volume fractions of VC are greater than ∼12%. On the other hand, the erosion resistance is mostly independent of material hardness. Wear scars were examined using scanning electron microscopy and laser profilometry. It was found that the standout wear protection effect of the fine VC carbides became more pronounced in steels with VC volume fractions higher than ∼12%. In these steels, the contribution of the microcutting mechanism decreased drastically with increase in VC volume fraction, with the grooving depth being reduced by about 4 times in CPM 15V as compared with the steel containing the lowest VC volume fraction (CPM 1V).

The low-stress ASTM-G65 abrasive wear behaviour was studied in a system of high manganese steels Fe-18Mn-xAl-0.7C with aluminium contents of 0%, 3%, 6% and 9.5% by weight and the results were compared with those of AISI D2 and AISI 9260 steels. By a completely randomized design (CRD), it was determined that the highest wear resistance corresponds to AISI D2 steel, followed by Fe18Mn0Al, Fe18Mn3Al, Fe18Mn9Al, Fe18Mn6Al and AISI 9260 steel. Using micro hardness tests, surface analysis and staking fault energy calculations it was possible to establish a relationship between wear resistance and the strain hardening mechanisms such as transformation induced plasticity (TRIP), twinning induced plasticity (TWIP) and microband induced plasticity (MBIP) for the Fe-Mn-Al-C steels under study.

La infección urinaria (ITU) es una de las patologías infecciosas más frecuentes en pediatría. Tradicionalmente se ha considerado como marcador de probables anormalidades anatómicas y funcionales de la vía urinaria, por lo cual, en las últimas décadas todos los niños que presentaban una ITU eran sometidos a estudio por imágenes en busca de cicatrices renales o anormalidades de la vía urinaria. El objetivo de este artículo es actualizar los conceptos sobre el estudio y tratamiento de pacientes pediátricos que presentan una ITU febril. El estudio por imágenes es incómodo para los pacientes, estresante para los padres y las evidencias actuales para continuar realizándolo son limitadas por lo cual debe ser selectivo en orden de focalizar en los pacientes que puedan beneficiarse con cirugías urológicas correctoras o tratamientos médicos adecuados. Estas pautas están basadas en las guías NICE de ITU e intentan demostrar que uno de los pilares más importantes para evitar secuelas renales es el diagnóstico y tratamiento oportuno de las ITU febriles.

The aim of this study was to determine the frequency of renal abnormalities in HIV positive children hospitalized in one pediatric hospital in Chile.a cross sectional study was performed during April 2007.A total of 18 patients were evaluated, ten male and eight female ranging in age from 4 to 19 years. The average age at the time of HIV diagnosis and nephrologic evaluations were 2,69 and 10,7 years respectively. All patients had acquired HIV infection by vertical transmission. Uriñe samples of two children had microalbuminuria; two had monosymptomatic hematuria, and ten had ¿squamous? cells. Hypercalciuria was detected in one patient, renal lithiasis in another and two patients had abnormal renal ultrasonography. All 19 patients had normal blood pressures. Overall 7 patients (39%) had a renal abnormality.The relatively high incidence of renal abnormalities in our series support the need for a nation-wide screening program to assess the incidence of renal impairment in pediatric HIV positive patients.

El objetivo de este estudio fue evaluar la función renal de pacientes infectados con virus de inmuno-deficiencia humana (VIH) que se controlan en un hospital pediátrico chileno. Método: estudio de corte transversal. Resultados: Se evaluaron 18 pacientes, 10 varones y 8 mujeres; edad: entre 4 y 19 años, la edad promedio al diagnóstico de la infección por VIH y al momento de la evaluación fue 2,69 y 10,7 años, respectivamente. Todos nuestros pacientes adquirieron la infección vía vertical. Dos presentaron microalbuminuria y dos hematuria monosintomática. En 10 (55%) se encontraron células descamativas, en uno hiper-calciuria y en otro litiasis renal. Todos tuvieron presión arterial normal. La ecotomograña renal fue anormal en dos. Se han descrito varias anormalidades renales en pacientes con infección por VIH; en nuestro estudio, 7 pacientes (39%) tuvieron alteraciones en los exámenes de laboratorio. Conclusión: La alta frecuencia de afectación renal encontrada en pacientes pediátricos con infección por VIH hace necesario plantear un tamizaje nacional para determinar la incidencia de nefropatía asociada en nuestros pacientes. The aim of this study was to determine the frequency of renal abnormalities in HIV positive children hospitalized in one pediatric hospital in Chile. Method: a cross sectional study was performed during April 2007. Results: A total of 18 patients were evaluated, ten male and eight female ranging in age from 4 to 19 years. The average age at the time of HIV diagnosis and nephrologic evaluations were 2,69 and 10,7 years respectively. All patients had acquired HIV infection by vertical transmission. Uriñe samples of two children had microalbuminuria; two had monosymptomatic hematuria, and ten had ¿squamous? cells. Hypercalciuria was detected in one patient, renal lithiasis in another and two patients had abnormal renal ultrasonography. All 19 patients had normal blood pressures. Overall 7 patients (39%) had a renal abnormality. Conclusions: The relatively high incidence of renal abnormalities in our series support the need for a nation-wide screening program to assess the incidence of renal impairment in pediatric HIV positive patients.

El objetivo de este estudio fue evaluar la función renal de pacientes infectados con virus de inmuno-deficiencia humana (VIH) que se controlan en un hospital pediátrico chileno. Método: estudio de corte transversal. Resultados: Se evaluaron 18 pacientes, 10 varones y 8 mujeres; edad: entre 4 y 19 años, la edad promedio al diagnóstico de la infección por VIH y al momento de la evaluación fue 2,69 y 10,7 años, respectivamente. Todos nuestros pacientes adquirieron la infección vía vertical. Dos presentaron microalbuminuria y dos hematuria monosintomática. En 10 (55%) se encontraron células descamativas, en uno hiper-calciuria y en otro litiasis renal. Todos tuvieron presión arterial normal. La ecotomograña renal fue anormal en dos. Se han descrito varias anormalidades renales en pacientes con infección por VIH; en nuestro estudio, 7 pacientes (39%) tuvieron alteraciones en los exámenes de laboratorio. Conclusión: La alta frecuencia de afectación renal encontrada en pacientes pediátricos con infección por VIH hace necesario plantear un tamizaje nacional para determinar la incidencia de nefropatía asociada en nuestros pacientes.

Background: Hemolytic-uremic syndrome (HUS) is characterized by acute renal failure, microangiopathic hemolytic anemia and thrombocytopenia. Aim: To describe the characteñstics ofpatients with the diagnosis ofHUS in Chile, and to identify the most reliable early predictors oímorbidity and moñality. Material and methods: The clinical records ofpatients with HUS aged less than 15 years, attended between January 1990 and December 2003 in 15 hospitals, were reviewed. Demographic, clinical, biochemical, hematological parameters, morbidity and mortality were analyzed. Results: A cohort of 587 patients aged 2 to 8 years, 48% males, was analyzed. Ninety two percent had diarrhea. At the moment of diagnosis, anuria was observed in 39% of the patients, hypertension in 45% and seizures in 17%. Forty two percent required renal replacement therapy (RRT) and perítoneal dialysis was used in the majoríty of cases (78%). The most frequently isolated etiological agentwas Escherichia coli. Mortality rate was 2.9% in the acute phase of the disease and there was a positive correlation between mortality and anuria, seizures, white blood cell count (WCC) >20.000/mm³ and requirements of renal replacement therapy (p 20.000/mm³, seizures and hypertension. Conclusions: The present study emphasizes important clinical and epidemiological aspeets ofHUSin a Chilean pediatricpopulation.

Background: Hemolytic-uremic syndrome (HUS) is characterized by acute renal failure, microangiopathic hemolytic anemia and thrombocytopenia. Aim: To describe the characteñstics ofpatients with the diagnosis ofHUS in Chile, and to identify the most reliable early predictors oímorbidity and moñality. Material and methods: The clinical records ofpatients with HUS aged less than 15 years, attended between January 1990 and December 2003 in 15 hospitals, were reviewed. Demographic, clinical, biochemical, hematological parameters, morbidity and mortality were analyzed. Results: A cohort of 587 patients aged 2 to 8 years, 48% males, was analyzed. Ninety two percent had diarrhea. At the moment of diagnosis, anuria was observed in 39% of the patients, hypertension in 45% and seizures in 17%. Forty two percent required renal replacement therapy (RRT) and perítoneal dialysis was used in the majoríty of cases (78%). The most frequently isolated etiological agentwas Escherichia coli. Mortality rate was 2.9% in the acute phase of the disease and there was a positive correlation between mortality and anuria, seizures, white blood cell count (WCC) >20.000/mm³ and requirements of renal replacement therapy (p 20.000/mm³, seizures and hypertension. Conclusions: The present study emphasizes important clinical and epidemiological aspeets ofHUSin a Chilean pediatricpopulation.

Tuberculosis (TB) is an occupational risk hazard that explains 5 to 5.361 additional cases of TB per 100.000 individuals among healthcare workers (HCW) in relation to general population in developing countries. For each clinical case a number of additional infections are occurring, that can be detected by tuberculin skin test conversion among non-BCG vaccinated HCW or by interferon-gamma testing. Risk factors for HCW infection include number of TB patients examined, job characteristics and place of work, delay in diagnostic suspicion, patients with multidrug resistant strains, limited access to appropriate ventilation systems, non-compliance with aerosol dissemination precautions, immune suppressed and/or malnourished HCW. Molecular studies suggest that only 32 to 42% of TB cases among HCW are related to occupational exposure. Useful measures to prevent occupational TB acquisition include a number of administrative-, infrastructure- and personal-related measures that have proven to be successful in reducing occurrence of new infections including clinical TB cases among HCW. In Chile, two official government sponsored guidelines are currently available for preventing TB infection among HCW, issued by the national TBC Control Program and by the National Nosocomial infection Control Program. Major differences in recommendations between these guidelines indicate that an update is urgently needed.

La tuberculosis (TBC) es un riesgo ocupacional que explica entre 5 y 5.361 casos por 100.000 personas en el personal de salud (PS) por sobre la población general en países en vías de desarrollo. Cada caso clínico implica que han ocurrido muchos casos de infección. Esta infección puede ser detectada por la prueba de conversión de tuberculina entre personas no vacunadas o por prueba de liberación de gama interferón. Los factores de riesgo incluyen la frecuencia de pacientes con TBC atendidos, la función y lugar de trabajo del PS, retraso en la sospecha diagnóstica, atención de pacientes con cepas multi-resistentes, sistemas de ventilación limitados, falta de aplicación de precauciones por aerosoles y PS con inmunosupresión o desnutrición. Los estudios moleculares han permitido aclarar que sólo 32 a 42% de los casos en el PS responde a adquisición ocupacional. Las medidas útiles para prevenir este riesgo incluyen un conjunto de disposiciones administrativas, de infraestructura y precauciones en el personal que han permitido reducir el riesgo de infección, y en ocasiones el de TBC clínica, en el PS. En Chile existen actualmente dos normas reguladoras sobre la materia, una del Programa Nacional de la TBC y el otro del Programa de Infecciones Intrahospitalarias, las que difieren en algunos aspectos sustantivos y que ameritan una revisión Tuberculosis (TB) is an occupational risk hazard that explains 5 to 5.361 additional cases of TB per 100.000 individuals among healthcare workers (HCW) in relation to general population in developing countries. For each clinical case a number of additional infections are occurring, that can be detected by tuberculin skin test conversion among non-BCG vaccinated HCW or by interferon-gamma testing. Risk factors for HCW infection include number of TB patients examined, job characteristics and place of work, delay in diagnostic suspicion, patients with multidrug resistant strains, limited access to appropriate ventilation systems, non-compliance with aerosol dissemination precautions, immune suppressed and/or malnourished HCW. Molecular studies suggest that only 32 to 42% of TB cases among HCW are related to occupational exposure. Useful measures to prevent occupational TB acquisition include a number of administrative-, infrastructure- and personal-related measures that have proven to be successful in reducing occurrence of new infections including clinical TB cases among HCW. In Chile, two official government sponsored guidelines are currently available for preventing TB infection among HCW, issued by the national TBC Control Program and by the National Nosocomial infection Control Program. Major differences in recommendations between these guidelines indicate that an update is urgently needed

Tuberculosis (TB) is an occupational risk hazard that explains 5 to 5.361 additional cases of TB per 100.000 individuals among healthcare workers (HCW) in relation to general population in developing countries. For each clinical case a number of additional infections are occurring, that can be detected by tuberculin skin test conversion among non-BCG vaccinated HCW or by interferon-gamma testing. Risk factors for HCW infection include number of TB patients examined, job characteristics and place of work, delay in diagnostic suspicion, patients with multidrug resistant strains, limited access to appropriate ventilation systems, non-compliance with aerosol dissemination precautions, immune suppressed and/or malnourished HCW. Molecular studies suggest that only 32 to 42% of TB cases among HCW are related to occupational exposure. Useful measures to prevent occupational TB acquisition include a number of administrative-, infrastructure- and personal-related measures that have proven to be successful in reducing occurrence of new infections including clinical TB cases among HCW. In Chile, two official government sponsored guidelines are currently available for preventing TB infection among HCW, issued by the national TBC Control Program and by the National Nosocomial infection Control Program. Major differences in recommendations between these guidelines indicate that an update is urgently needed.

Objetivo: Caracterizar la función tiroidea y la respuesta a test de TRH (thyroid releasing hormone), en niños con enfermedad renal crónica (ERC) leve (L), moderada (M), peritoneodiálisis (PD), hemodiálisis (HD) y trasplantados renales (TX). Pacientes y Método: Se estudiaron 46 pacientes con ERC (10 L, 10 M, 10PD,6HDy 10TX),9,3±3,7 años. Se midió t4t,t41,t3t, t31,TBGbasalytest de TRH(TSHa 0,30y60min). Se evaluó función renal, antropometría y se consignó tratamiento inmunosupresor (IS) en el grupo TX. Se utilizó anova para comparar los resultados entre los grupos y coeficiente de correlación para las variables estudiadas. Resultados: Los valores básales de hormonas tiroideas fueron normales en todos los grupos, sólo TSH fue significativamente mayor en L aunque dentro del rango normal (p < 0,01). La respuesta al test de TRH fue predominantemente prolongada en L, M, PD y HD y deficiente en TX; los 3 pacientes TX con tacrolimus, micofenolato y prednisona en días alternos tuvieron respuesta normal a diferencia del resto TX que recibían prednisona continua, ciclosporina y micofenolato. La prolongación de respuesta a TRH se correlacionó con creatininemia, BUN y clearance de creatinina (p < 0,01). Conclusiones: Los niveles de hormonas tiroideas básales se encuentran normales en todos los grupos de ERC. La respuesta a TRH fue predominantemente prolongada en L, M, PD y HD, demostrando un fenómeno adaptativo a nivel terciario del eje hipotálamo-hipofisis-tiroides. Los TX presentan una respuesta mayoritoriamente deficiente a TRH, sugerente de disfunción hipofisiaria, la que podría estar relacionada con el tipo de tratamiento inmunosupresor y al uso de corticoides en días continuos

Objetivo: Caracterizar la función tiroidea y la respuesta a test de TRH (thyroid releasing hormone), en niños con enfermedad renal crónica (ERC) leve (L), moderada (M), peritoneodiálisis (PD), hemodiálisis (HD) y trasplantados renales (TX). Pacientes y Método: Se estudiaron 46 pacientes con ERC (10 L, 10 M, 10PD,6HDy 10TX),9,3±3,7 años. Se midió t4t,t41,t3t, t31,TBGbasalytest de TRH(TSHa 0,30y60min). Se evaluó función renal, antropometría y se consignó tratamiento inmunosupresor (IS) en el grupo TX. Se utilizó anova para comparar los resultados entre los grupos y coeficiente de correlación para las variables estudiadas. Resultados: Los valores básales de hormonas tiroideas fueron normales en todos los grupos, sólo TSH fue significativamente mayor en L aunque dentro del rango normal (p < 0,01). La respuesta al test de TRH fue predominantemente prolongada en L, M, PD y HD y deficiente en TX; los 3 pacientes TX con tacrolimus, micofenolato y prednisona en días alternos tuvieron respuesta normal a diferencia del resto TX que recibían prednisona continua, ciclosporina y micofenolato. La prolongación de respuesta a TRH se correlacionó con creatininemia, BUN y clearance de creatinina (p < 0,01). Conclusiones: Los niveles de hormonas tiroideas básales se encuentran normales en todos los grupos de ERC. La respuesta a TRH fue predominantemente prolongada en L, M, PD y HD, demostrando un fenómeno adaptativo a nivel terciario del eje hipotálamo-hipofisis-tiroides. Los TX presentan una respuesta mayoritoriamente deficiente a TRH, sugerente de disfunción hipofisiaria, la que podría estar relacionada con el tipo de tratamiento inmunosupresor y al uso de corticoides en días continuos Objective: To characterize the thyroid function in mild (L), modérate (M), hemodialysis (HD), peritoneal dialysis (PD), chronic renal failure (CRE) and post kidney transplant (TX). Method: 46 children between 9.3 ±3.7 years-old with CRF (10 mild (L), 10 modérate (M), 10 peritoneodialysis (PD), 6 hemodialysis (HD), 10 transplants (TX)) were evaluated. Basal total T4 and free T3, TRH test (TSH at 0-30-60 min), creatinine, BUN, creatinine clearance and anthropometric parameters were measured. The statistics analysis included Anova Test to compare group results and correlation coefficients for studied variables. Results: Basal thyroid hormone levéis were normal in all groups and no differences between groups (except higher TSH in L (p < 0.01)) were found. TRH test response was prolonged on L, M, PD and HD and deficient in TX, except 3 TX patients who had normal TRH response, all using Tacrolimus, Micofenolate and Prednisone on altérnate day treatment versus the remaining TX who where on Cyclosporine or Azathioprine, Micofenolate and continuous corticoid régimen. Prolonged TRH response correlates with creatinine (p < 0.001) and creatinine clearance (p < 0,01). Conclusions: Basal thyroid hormones were normal in all groups. TRH test response was predominantly prolonged in L, M, PD and HD, suggesting adaptative phenomena at tertiary level, and correlates with renal function. TX patients had deficient TRH response, suggesting hypofisial dysfunction