Brain structure and episodic learning rate in cognitively healthy ageing.

Memory normally declines with ageing and these age-related cognitive changes are associated with changes in brain structure. Episodic memory retrieval has been widely studied during ageing, whereas learning has received less attention. Here we examined the neural correlates of episodic learning rate in ageing. Our study sample consisted of 982 cognitively healthy female and male older participants from the Vallecas Project cohort, without a clinical diagnosis of mild cognitive impairment or dementia. The learning rate across the three consecutive recall trials of the verbal memory task (Free and Cued Selective Reminding Test) recall trials was used as a predictor of grey matter (GM) using voxel-based morphometry, and WM microstructure using tract-based spatial statistics on fractional anisotropy (FA) and mean diffusivity (MD) measures. Immediate Recall improved by 1.4 items per trial on average, and this episodic learning rate was faster in women and negatively associated with age. Structurally, hippocampal and anterior thalamic GM volume correlated positively with learning rate. Learning also correlated with the integrity of WM microstructure (high FA and low MD) in an extensive network of tracts including bilateral anterior thalamic radiation, fornix, and long-range tracts. These results suggest that episodic learning rate is associated with key anatomical structures for memory functioning, motivating further exploration of the differential diagnostic properties between episodic learning rate and retrieval in ageing.

Launching of the Anaemia Research Peruvian Cohort (ARPEC): a multicentre birth cohort project to explore the iron adaptive homeostasis, infant growth and development in three Peruvian regions.

BACKGROUND: Preventing infantile anaemia and ensuring optimal growth and development during early childhood, particularly in resource-constrained settings, represent an ongoing public health challenge. Current responses are aligned to treatment-based solutions, instead of determining the roles of its inter-related causes. This project aims to assess and understand the complex interplay of eco-bio-social-political factors that determine infantile anaemia to inform policy, research design and prevention practices. METHODS: This is a longitudinal birth cohort study including four components: (1) biological, will assess known blood markers of iron homeostasis and anaemia and stool microbiota to identify and genetically analyse the participants' flora; (2) ecological, will assess and map pollutants in air, water and soil and evaluate features of nutrition and perceived food security; (3) social, which will use different qualitative research methodologies to explore key stakeholders and informants' perceptions related to nutritional, environmental and anaemia topics, participant observations and a participatory approach and (4) a political analysis, to identify and assess the impact of policies, guidelines and programmes at all levels for infantile anaemia in the three regions. Finally, we will also explore the role of social determinants and demographic variables longitudinally for all study participants. This project aims to contribute to the evidence of the inter-related causal factors of infantile anaemia, addressing the complexity of influencing factors from diverse methodological angles. We will assess infantile anaemia in three regions of Peru, including newborns and their mothers as participants, from childbirth until their first year of age. ETHICS AND DISSEMINATION: Ethical approval was obtained from the Institutional Research Ethics Committee of the Instituto Nacional de Salud del Niño (Lima, Peru), CIEI-043-2019. An additional opinion has been granted by the Ethical Committee of Queen Mary University of London (London, UK). Dissemination across stakeholders is taking part as a continues part of the research process.

[A septal rupture of atypical location after myocardial infarction. A clinical case]. / Ruptura septal de localización atípica posterior a infarto del miocardio. Caso clínico

Paciente masculino de 46 años de edad con antecedentes personales de hipertensión arterial sistémica, tabaquismo y etilismo y heredofamiliares de hipertensión arterial sistémica. El padecimiento inició con cuadro de astenia, adinamia, disnea progresiva, edema de miembros inferiores y aumento del volumen abdominal, por lo que acudió con el médico, quien decidió hospitalizarlo. El paciente recibió tratamiento médico con captopril, furosemida y espironolactona, sin mejoría de los síntomas, motivo por el cual se lo refirió a la institución de los autores. Al llegar al servicio de urgencias, el sujeto se encontraba estable.

Double Burden of Excess Weight and Anemia in Latin American Children up to 2019.

The double burden of malnutrition is the coexistence of two different conditions, mainly reflected as excess or deficit in weight. Anemia is a specific nutritional deficit not always included in the double burden assessment. We reviewed overweight and/or obesity (OW/OB) and anemia studies from Latin-American Children over the last ten years up to 2019. Two authors evaluated the MEDLINE, SCOPUS, and LILACS databases. A scale of ten questions was used to assess the risk of bias in prevalence studies. Fourteen studies were selected. The population studies' size ranged from 147 to 20,342 children with different socio-economic backgrounds, such as urban, peri-urban and rural settings, socio-economic status, schooling, population (ethnic minorities and indigenous), and environmental differences (sea level or high altitude). The prevalence of OW/OB ranged from 4.9% to 42%. The prevalence of anemia was from 3.4% to 67%. The double burden, including OW/OB and anemia, ranged from 0.7% to 67%. A higher prevalence of excess weight and anemia was found in rural and high altitude above sea level environments, extreme poverty, low education level, and indigenous communities. These heterogeneous data, before the 2020 (COVID-19 pandemic), reflect the vast inequities between countries and within each country. Food insecurity linked to poverty and the induced change in eating habits and lifestyles threaten optimal child nutrition in ongoing and future scenarios. The existence of OW/OB and anemia and their simultaneous coexistence in the community, home, and individual levels, indicates that interventions should be comprehensive to face the double burden of malnutrition.

Evaluation of mixing ratio and frequency of turning in the co-composting of biowaste with sugarcane filter cake and star grass.

This work studied the effect of mixing ratio (MR) and turning frequency (TF) in biowaste composting (BW) with sugarcane filter cake (SFC) and star grass (SG), both on process performance (temperature, static respiration index, total organic carbon, total nitrogen and total phosphorus) and on product quality (pH, cation exchange capacity, electrical conductivity, organic matter, nutrients, stability, maturity, total coliforms and faecal coliforms), through the Principal Components Analysis (PCA). The Pearson correlation coefficients were calculated for all the quality parameters. A joint effect of mixing ratio and turning frequency was demonstrated, highlighting the importance of studying the operational parameters simultaneously. The results of the PCA showed that the best operating conditions and therefore higher product quality is achieved with a TF of twice a week and MR between 20 and 30% of SFC or SG. Additionally, it was found that a frequency of one turn per week generates the lowest product quality, regardless the co-substrate and the MR. The best treatment corresponded to BW composting with MR of 20% SFC and TF of two turnings per week. The obtained results allow to optimize the operation in composting facilities.

Non-clinical performance and acceptability of a small portable respiratory stimulator device for basic neonatal resuscitation, tested by health personnel / Desempeño no clínico y aceptabilidad de un estimulador respiratorio portátil para reanimación neonatal básica, evaluado en personal de salud

Introducción: La reanimación neonatal demanda dispositivos para apoyo respiratorio que no siempre se encuentran en áreas rurales. Se requieren dispositivos innovadores y el prototipado rápido permite generarlos usando diseños e impresoras tridimensionales (3D). Objetivo: Evaluar el desempeño no clínico y la aceptabilidad por el personal de salud de un dispositivo respiratorio neonatal producido mediante prototipado rápido. Métodos: Estudio observacional, descriptivo, de prueba de concepto desarrollado en dos etapas. Etapa 1: Fabricación del dispositivo con prototipado rápido en impresoras y escáneres tridimensionales (3D). Etapa 2: Demostración del dispositivo durante programas de capacitación en reanimación neonatal para personal de salud en tres regiones del Perú (Tarapoto, Huánuco y Ayacucho). En ambas etapas se evaluó el desempeño del dispositivo conectado a un analizador de flujo de gases. Se administró una encuesta a los trabajadores de salud de Tarapoto y Ayacucho para conocer su aceptabilidad. Resultados: El prototipo desarrollado tiene forma de T con dos fuelles laterales que al presionarse con una sola mano, proyectan aire por el centro hacia un adaptador facial. El uso del prototipo en laboratorio generó un flujo de aire promedio de 4,8 Lt/min (DE ± 1,7) y una presión promedio de 5,9 cm H2O (DE ± 1,4). Este dispositivo fue considerado como "de uso muy simple" en una encuesta de aceptabilidad donde participaron 39 enfermeras y 11 médicos en zonas alejadas de la capital del Perú. Conclusiones: El prototipo evaluado fue aceptado por el personal y tuvo un desempeño capaz de generar un estímulo de la respiración espontánea al nacer.

Introduction: Neonatal resuscitation demands equipment for respiratory support not always available in rural areas. Innovative devices are required, and rapid prototyping allows to generate them using three-dimensional (3D) designs and printers. Objective: To evaluate the non-clinical performance and the acceptability by health personnel of a neonatal respiratory device produced by rapid prototyping. Methods: Observational study, descriptive, of proof of concept developed in two steps. Step 1: Manufacture of the device with rapid prototyping in three-dimensional (3D) scanners and printers. Step 2: Demonstration of the invention during training programs in neonatal resuscitation for health personnel in three regions of Peru (Tarapoto, Huánuco and Ayacucho). In both steps, we evaluated the performance of the device connected to a gas flow analyser. A survey was administered to the health workers of Tarapoto and Ayacucho to know their acceptability. Results: The developed prototype is T-shaped with two side bellows that, when pressed with one hand, project air through the centre towards a facial adapter. The use of the prototype in the laboratory generated an average air flow of 4.8 Lt /min (SD ± 1.7) and an average pressure of 5.9 cm H2O (SD ± 1.4). This device was considered to be "very simple to use" in an acceptability survey involving 39 nurses and 11 doctors in remote areas of the capital of Peru. Conclusions: The evaluated prototype is acceptable by the staff and has a performance capable of generating spontaneous breathing at birth.

Study of Two Bovine Bone Blocks (Sintered and Non-Sintered) Used for Bone Grafts: Physico-Chemical Characterization and In Vitro Bioactivity and Cellular Analysis.

In this work, the physicochemical properties and in vitro bioactivity and cellular viability of two commercially available bovine bone blocks (allografts materials) with different fabrication processes (sintered and not) used for bone reconstruction were evaluated in order to study the effect of the microstructure in the in vitro behavior. Scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectrometry, mechanical resistance of blocks, mercury porosimetry analysis, in vitro bioactivity, and cell viability and proliferation were performed to compare the characteristics of both allograft materials against a synthetic calcium phosphate block used as a negative control. The herein presented results revealed a very dense structure of the low-porosity bovine bone blocks, which conferred the materials' high resistance. Moreover, relatively low gas, fluid intrusion, and cell adhesion were observed in both the tested materials. The structural characteristics and physicochemical properties of both ceramic blocks (sintered and not) were similar. Finally, the bioactivity, biodegradability, and also the viability and proliferation of the cells was directly related to the physicochemical properties of the scaffolds.

Continuous training and certification in neonatal resuscitation in remote areas using a multi-platform information and communication technology intervention, compared to standard training: A randomized cluster trial study protocol.

Background: About 10% of all newborns may have difficulty breathing and require support by trained personnel. In Peru, 90% of deliveries occur in health facilities. However, there is not a national neonatal resuscitation and certification program for the public health sector. In addition, the Andes and the Amazon regions concentrate large rural remote areas, which further limit the implementation of training programs and the accomplishment of continuous certification. Neonatal resuscitation training through the use of Information, Communication and Technology (ICT) tools, running on computers, tablets or mobile phones, may overcome such limitations. This strategy allows online and offline access to educational resources, paving the way to more frequent and efficient training, and certification processes. Objective: To evaluate the effects of a neonatal resuscitation training and certification program that uses a Multi-Platform ICT (MP-ICT) strategy on neonatal health care in remote areas. Methods: We propose to conduct the study through a cluster-randomized trial, where the study and analysis unit is the health care facility. Eligible facilities will include primary and secondary health care level facilities that are located in provinces with neonatal mortality rates higher than 15 per 1,000 live births. We will compare the proportion of newborns with a heart rate ≥100 beats per minute at two minutes after birth in health care facilities that receive MP-ICT training and certification implementation, with those that receive standard training and certification. Discussion: We expect that the intervention will be shown as more effective than the current standard of care. We are prepared to include it within a national neonatal resuscitation training and certification program to be implemented at national scale together with policymakers and other key stakeholders.  Trial registration: ClinicalTrials.gov Nº NCT03210194 Status of the study: This study is ongoing. Study protocol version 1.1 - March 31st, 2017.

Simulation-optimization model to determine the installed capacity of an educational services system

Introduction. The problem of determining the capacity in service companies is the lack of clear methodologies. As for academic institutions, the research advances on the subject are even more reduced. The literature available has widely covered other problems affecting capacity, and also the programming and the planning of staff, facilities and schedules without directly measuring capacity. Objective. To create a generic methodology to determine the capacity of an educative services system (schools, universities, etc) in terms of the quantity of students to serve with the institution´s infrastructure. Materials and methods. Firstly, a methodology to simulate the capacity used by the students throughout time is created. Then, with this information, an optimization model to calculate the maximum number of students that can be admitted is executed. Results. The model developed is applied in the Engineering School of Universidad del Valle, Colombia, where it was found that 25% more of students could have been admitted, using about 20 % of the capacity that can be potentially used. Conclusion. This methodological model is useful to know the capacity in terms of the number of students an institution can receive. It also facilitates midterm decisions, especially the measurement of the impact of the policies that can be formulated to favor the maximization of the service standards of the institution, and also, for instance, the impact of building new infrastructures.

Introducción. El problema de la determinación de la capacidad en empresas de servicios, es la no existencia de metodologías claras. En cuanto a las instituciones académicas, los avances de investigación sobre el asunto son aún más reducidos. La literatura ha abarcado ampliamente otros problemas que afectan a la capacidad, así como la programación y planificación del personal, instalaciones y horarios sin llegar directamente a medir capacidad. Objetivo. Crear una metodología genérica para determinar la capacidad de un sistema de servicios educativos (escuelas, colegios, universidades, etc), en términos de la cantidad de estudiantes a atender con la infraestructura de la institución. Materiales y métodos. Primero, se desarrolla una metodología para simular la capacidad utilizada por los alumnos matriculados históricamente, posteriormente, con esta información, es ejecutado un modelo de optimización que calculará el número máximo de estudiantes a admitir. Resultados. El modelo desarrollado se aplica en la Facultad de Ingeniería de la Universidad del Valle - Colombia, donde se encontró que podría ser inscrito un 25 % más de estudiantes nuevos empleando alrededor del 20 % de la capacidad que potencialmente se puede utilizar. Conclusión. Este modelo metodológico es útil para conocer la capacidad en términos del número de estudiantes a atender por una institución, asimismo permite tomar decisiones en el mediano plazo, en especial medir el impacto de políticas a formular en pro de la maximización del nivel de servicio de la institución, como por ejemplo el impacto de la construcción de nuevos espacios físicos.

Introdução. O problema de determinar a capacidade das empresas de serviços, é a ausência de metodologias claras. Quanto a instituições acadêmicas, o progresso da pesquisa nesta matéria é ainda menor. A literatura tem uma ampla cobertura de outras questões que afetam a capacidade, tais como programação e planejamento pessoal, instalações e horários, entre outros, sem chegar a medi-la diretamente a capacidade. Objectivo. Criar uma metodologia genérica para determinar a capacidade de um sistema de serviços de ensino (escolas, faculdades, universidades, etc.) em termos do número de alunos que podem ser servido pela infra-estrutura da instituição. Materiais e métodos. Em primeiro lugar, é desenvolvido um método para simular a capacidade utilizada pelos alunos matriculados historicamente. Com esta informação, é executado um modelo de otimização que calcula o número máximo de alunos a admitir. Resultados. O modelo desenvolvido é aplicado na Faculdade de Engenharia da Universidade do Vale - Colômbia, onde foi descoberto que podiam ser registados 25% mais estudantes utilizando cerca de 20% da capacidade que potencialmente podem ser utilizados. Conclusão. Este modelo metodológico é útil para conhecer a capacidade em termos de número de alunos que podem ser servidos por uma instituição, também permite tomada decisões ao médio prazo, especialmente medir o impacto das políticas formuladas no sentido de maximizando do nível de serviço da instituição, tais como o impacto da construção de novos espaços físicos.

Morphological and Structural Study of a Novel Porous Nurse's A Ceramic with Osteoconductive Properties for Tissue Engineering.

The characterization process of a new porous Nurse's A ceramic and the physico chemical nature of the remodeled interface between the implant and the surrounding bone were studied after in vivo implantation. Scaffolds were prepared by a solid-state reaction and implanted in New Zealand rabbits. Animals were sacrificed on days 15, 30, and 60. The porous biomaterial displayed biocompatible, bioresorbable, and osteoconductive capacity. The degradation processes of implants also encouraged osseous tissue ingrowths into the material's pores, and drastically changed the macro- and microstructure of the implants. After 60 healing days, the resorption rates were 52.62% ± 1.12% for the ceramic and 47.38% ± 1.24% for the residual biomaterial. The elemental analysis showed a gradual diffusion of the Ca and Si ions from the materials into the newly forming bone during the biomaterial's resorption process. The energy dispersive spectroscopy (EDS) analysis of the residual ceramic revealed some particle categories with different mean Ca/P ratios according to size, and indicated various resorption process stages. Since osteoconductive capacity was indicated for this material and bone ingrowth was possible, it could be applied to progressively substitute an implant.

Enhanced bone regeneration with a novel synthetic bone substitute in combination with a new natural cross-linked collagen membrane: radiographic and histomorphometric study.

OBJECTIVES: 4Bone is a fully synthetic bioactive bone substitute composed of 60% hydroxyapatite (HA) and 40% beta-tricalcium phosphate (ß-TCP). This study aimed to investigate the effect of resorbable collagen membranes (RCM) on critical size defects in rabbit tibiae filled with this novel biphasic calcium phosphate at 15, 30, 45, and 60 days by radiological and histomorphometric analysis. MATERIAL AND METHODS: Three critical size defects of 6 mm diameter were created in both tibiae of 20 New Zealand rabbits and divided into three groups according to the filling material: Group A (4Bone), Group B (4Bone plus RCM), and Group C (unfilled control group). At each of the four study periods, five rabbits were sacrificed. Anteroposterior and lateral radiographs were taken. Samples were processed for observation under light microscopy. RESULTS: At the end of treatment, radiological analysis found that cortical defect closure was greater in Group B than Group A, and radiopacity was clearly lower and more heterogeneous in Group A cortical defects than in Group B. There was no cortical defect closure in Group C. Histomorphometric evaluation showed significant differences in newly formed bone and cortical closure in Group B compared with Groups A and C, with the presence of higher density newly formed bone in cortical and medullar zones. CONCLUSIONS: Biphasic calcium phosphate functioned well as a scaffolding material allowing bone ingrowth and mineralization. The addition of absorbable collagen membranes enhanced bone gain compared with non-membrane-treated sites. This rabbit study provides radiological and histological evidence confirming the suitability of this new material for guided tissue regeneration of critical defects.

Influence of biphasic ß-TCP with and without the use of collagen membranes on bone healing of surgically critical size defects. A radiological, histological, and histomorphometric study.

OBJECTIVES: The aim of this study was to investigate, by means of radiological and histomorphometric analysis, the effect of resorbable collagen membranes on critical size defects (CSD) in rabbit tibiae filled with biphasic calcium phosphate. MATERIALS AND METHODS: Three CSD of 6 mm diameter were created in both tibiae of 20 New Zealand rabbits and divided into three groups according to the filling material: Group A (Ossceram), Group B (Ossceram plus Alveoprotect membrane), and Group C (unfilled control group). Five animals from each group were sacrificed after 15, 30, 45, and 60 days. Anteroposterior and lateral radiographs were taken. Samples were processed for observation under light microscopy. RESULTS: At the end of treatment, radiological analysis found that cortical defect closure was greater in Group B than Group A, and radiopacity was clearly lower and more heterogeneous in the Group A cortical defects than in Group B. There was no cortical defect closure in Group C. Histomorphometric evaluation showed significant differences in newly formed bone and cortical closure in Group B compared with Groups A and C, with the presence of higher density newly formed bone in cortical and medullar zones. There was no cortical defect closure or medullar bone formation in Group C. CONCLUSIONS: Biphasic calcium phosphate functioned well as a scaffolding material allowing mineralized tissue formation. Furthermore, the addiction of absorbable collagen membranes enhanced bone gain compared with non-membrane-treated sites.

(α'(H))-Dicalcium silicate bone cement doped with tricalcium phosphate: characterization, bioactivity and biocompatibility.

The influence of phosphorus doping on the properties of (α'(H))-dicalcium silicate (C(2)S) bone cement was analyzed, in addition to bioactivity and biocompatibility. All the cements were composed of a solid solution of TCP in C(2)S ([Formula: see text]-C(2)S(ss)) as the only phase present. The compressive strength ranged from 3.8-16.3 MPa. Final setting times ranged from 10 to 50 min and were lower for cements with lower L/P content. Calcium silicate hydrate was the principal phase formed during the hydration process of the cements. The cement exhibited a moderate degradation and could induce carbonated hydroxyapatite formation on its surface and into the pores. The cell attachment test showed that the (α'(H))-C(2)SiO(4) solid solution supported human adipose stem cells adhesion and spreading, and the cells established close contacts with the cement after 24 h of culture. The novel (α'(H))-C(2)S(ss) cements might be suitable for potential applications in the biomedical field, preferentially as materials for bone/dental repair.

Hiperoxia por dos horas produce daño morfológico cerebral luego de asfixia neonatal experimental / Two-hour hyperoxia following experimental neonatal asphyxia produces morphological brain damage

Objetivos: Determinar el efecto de una exposición de dos horas de hiperoxia al 21%, 40% y 100% sobre la morfología cerebral, en un modelo experimental de asfixia neonatal. Diseño: Estudio experimental. Institución: Instituto Nacional de Salud del Niño, Lima, Perú. Material biológico: Ratas albinas Holtzmann. Intervenciones: Ciento veinte ratas albinas Holtzmann de una semana de nacidas (a excepción del grupo control) fueron sometidas a asfixia experimental por ligadura de la arteria carótida izquierda y luego expuestas a hipoxia (oxígeno al 8%). Después fueron asignadas aleatoriamente a uno de los siguientes grupos: exposición por dos horas a O2 al 100%, a O2 al 40%, a O2 al 21% y un grupo control (no expuesto a asfixia experimental). El daño cerebral fue evaluado mediante la medición del peso cerebral y el porcentaje del área cerebral con daño microscópico. Principales medidas de resultados: Daño cerebral. Resultados: El peso cerebral promedio fue menor en los animales de los grupos sometidos a hiperoxia experimental (ANOVA; p<0,001). Se presentó daño cerebral microscópico con mayor frecuencia en el grupo sometido a hipoxia experimental que recibió O2 100% por dos horas y con menor frecuencia en el que recibió O2 al 40% (60% versus 43,3%), diferencia que fue estadísticamente significativa (prueba χ²; p<0,001). El grupo sometido a hipoxia experimental que recibió O2 100% tuvo un mayor porcentaje promedio de área cerebral con daño microscópico (18,3%), en comparación con los otros grupos de hipoxia experimental, aunque la diferencia no fue estadísticamente significativa (ANOVA; p=0,123). Conclusiones: La hiperoxia al 100% por dos horas se asoció con menor peso cerebral y mayor daño cerebral en animales de experimentación sometidos a asfixia neonatal experimental.

Objectives: To determine the effect of 2-hour exposure to 21% O2, 40% O2 and 100% O2 on cerebral morphology in an experimental model of neonatal asphyxia. Design: Experimental study. Setting: Instituto Nacional de Salud del Niño, Lima, Peru. Biologic material: Holtzman albino rats. Interventions: A sample of 120 one week-old Holtzman albino rats (with the exception of the control group) underwent experimental asphyxia by left carotid artery ligation and then exposition to hypoxia (8% O2); thereafter rats were randomly assigned to one of the following groups: exposition for two hours to 100% O2, to 40% O2, to 21% O2, and a control group (not exposed to experimental asphyxia). Brain damage was determined by brain weight and percentage of microscopic brain area damage. Main outcome measures: Brain damage. Results: Brain weight was lower in animals with experimental hyperoxia (ANOVA, p<0.001). Microscopic damage was more frequent in the group receiving 100% O2 for two hours and with less frequency in the group receiving 40% O2 (60% versus 43.3%). The difference was statistically significant (χ2 test: p<0.001). The group receiving 100% O2 had more microscopic brain damage (18.3 %) in comparison with the other groups of experimental hypoxia, but the difference was not statistically significant (ANOVA, p=0.123). Conclusions: Following neonatal asphyxia 100% two-hour hyperoxia was associated with less brain weight and more damage in experimental animals.

The effects of Ca2SiO4-Ca3(PO4)2 ceramics on adult human mesenchymal stem cell viability, adhesion, proliferation, differentiation and function.

Bioceramic samples with osteogenic properties, suitable for use in the regeneration of hard tissue, were synthesized. The materials consisting of α-tricalcium phosphate (αTCP) and also αTCP doped with either 1.5 wt.% or 3.0 wt.% of dicalcium silicate (C2S) in the system Dicalcium Silicate-Tricalcium Phosphate (C2S-TCP) were obtained by solid state reaction. All materials were composed of a single phase, αTCP in the case of a pure material, or solid solution of C2S in αTCP (αTCPss) for the doped αTCP. Viability, proliferation and in vitro osteoinductive capacity were investigated by seeding, adult mesenchymal stem cells of human origin (ahMSCs) which were CD73(+), CD90(+), CD105(+), CD34(-) and CD45(-) onto the 3 substrates for 30 days. Results show a non-cytotoxic effect after applying an indirect apoptosis test (Annexin V/7-AAD staining), so ahMSCs adhered, spread, proliferated and produced extracellular matrix (Heparan-sulfate proteoglycan (HS) and osteopontin (OP)) on all the ceramics studied. Finally, the cells lost the cluster differentiation marker expression CD73, CD90 y CD105 characteristic of ahMSCs and they showed an osteoblastic phenotype (Alkaline phosphatase activity (ALP), Osteocalcin production (OC), Collagen type I expression (Col-I), and production of mineralization nodules on the extracellular matrix). These observations were more evident in the αTCP ceramic doped with 1.5 wt.% C2S, indicating osteoblastic differentiation as a result of the increased concentration of solid solution of C2S in αTCP (αTCPss). Overall, these results suggest that the ceramics studied are cytocompatible and they are able to induce osteoblastic differentiation of undifferentiated ahMSCs.

αTCP ceramic doped with dicalcium silicate for bone regeneration applications prepared by powder metallurgy method: in vitro and in vivo studies.

This study reports on the in vitro and in vivo behavior of α-tricalcium phosphate (αTCP) and also αTCP doped with either 1.5 or 3.0 wt % of dicalcium silicate (C2 S). The ceramics were successfully prepared by powder metallurgy method combined with homogenization and heat treatment procedures. All materials were composed of a single-phase, αTCP in the case of a pure material, or solid solution of C2 S in αTCP for the doped αTCP, which were stable at room temperature. The ceramics were tested for bioactivity in simulated body fluid, cell culture medium containing adult mesenchymal stem cells of human origin, and in animals. Analytical scanning electron microscopy combined with chemical elemental analysis was used and Fourier transform infrared and conventional histology methods. The in vivo behavior of the ceramics matched the in vitro results, independently of the C2 S content in αTCP. Carbonated hydroxyapatite (CHA) layer was formed on the surface and within the inner parts of the specimens in all cases. A fully mineralized new bone growing in direct contact with the implants was found under the in vivo conditions. The bioactivity and biocompatibility of the implants increased with the C2 S content in αTCP. The C2 S doped ceramics also favoured a phase transformation of αTCP into CHA, important for full implant integration during the natural bone healing processes. αTCP ceramic doped with 3.0 wt % C2 S showed the best bioactive in vitro and in vivo properties of all the compositions and hence could be of interest in specific applications for bone restorative purposes.

Influence of thermal treatment on the "in vitro" bioactivity of wollastonite materials.

The aim of this work was to study the influence of the composition and thermal treatment of the in vitro bioactivity of wollastonite materials obtained by sol-gel method. For this purpose, gels in the system SiO(2)-CaO were obtained applying calcium nitrate and tetraethoxysilicate as precursors. The gels were heated to 700 °C and then sintered up to 1400 °C. The bioactivity of the gel-derived materials in simulated body fluid (SBF) was investigated and characterized. Additional changes in ionic concentration, using inductively couple plasma atomic emission spectroscopy (ICP-AES), were determined. The results showed that all materials obtained were bioactive and indicate that the absence of phosphorous in the material composition is not an essential requirement for the development of a Hydroxyapatite layer. The bioactivity was influenced by the thermal treatment, the different phases (glass-phase, wollastonite and pseudowollastonite) as well as the porous size. On the gel-derived materials the bioactivity decreased with the sintering temperature.

A chemical, morphological, and electrochemical (XPS, SEM/EDX, CV, and EIS) analysis of electrochemically modified electrode surfaces of natural chalcopyrite (CuFeS2) and pyrite (FeS2) in alkaline solutions.

Electrodic surfaces of natural chalcopyrite and natural pyrite minerals (El Teniente mine, Chile) have been studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy including microanalysis (SEM/EDX). For comparison, fractured and polished mineral surfaces were also studied by XPS. In both electrodes, the formation of Fe(III) species containing oxygen were detected and Cu(II) species containing oxygen were additionally detected for chalcopyrite at advanced oxidation states. The presence of Cu(II) species containing oxygen was not detected by XPS for the initial oxidation states of the chalcopyrite. For pyrite, the present results do not allow confirmation of the presence of polysulfurs such as have been previously proposed. In both minerals, the measurements of SEM and EDX show relevant alterations in the respective surfaces when different potential values were applied. The chalcopyrite surface shows the formation of protrusions with a high concentration of oxygen. The pyrite surface shows a layer of modified material with high oxygen content. The modifications detected by XPS, SEM, and EDX allowed the explanation of the complexity of the equivalent circuit used to simulate the experimental EIS data. At high oxidation states, both minerals showed a pseudoinductive loop in the equivalent circuit, which was due to the active electrodissolution of the minerals which takes place through a surface film previously formed.

Etiología y susceptibilidad antimicrobiana de las infecciones neonatales / Neonatal infections etiology antimicrobial sensitivity

Objetivo: Determinar los gérmenes más frecuentes causantes de infecciones en recién nacidos hospitalizados y la susceptibilidad antimicrobiana. Material y métodos: Revisión de historias clínicas del Servicio de Neonatología del Instituto de Salud del Niño (Lima, Perú) y resultados de cultivos positivos y antibiogramas, desde junio de 1999 hasta mayo de 2002. Resultados: Durante el periodo de estudio hubo 94 pacientes con sepsis confirmada; de ellos se obtuvo 161 muestras (sangre, orina, catéteres EV, entre otras). Los gérmenes más frecuentes fueron: Staphylococcus epidermidis (38,3 por ciento), Staphylococcus aureus (12 por ciento), Klebsiella sp (10 por ciento), Alcaligenes fecalis (4,6 por ciento), Acinetobacter sp (4 por ciento) y Pseudomonas aeruginosa (4 por ciento). S. epidermidis mostró sensibilidad de 100 por ciento a vancomicina, 90 por ciento a cefotaxima, 50 por ciento a amikacina y ampicilina y 37 por ciento a oxacilina. Klebsiella mostró sensibilidad de 100 por ciento a ciprofloxacina e imipenen, 44 por ciento a ceftriaxona, 20 por ciento a ceftazidima y 14 por ciento a ampicilina; la resistencia a amikacina fue del 100 por ciento. S. aureus mostró sensibilidad de 100 por ciento a vancomicina, 57 por ciento a cefotaxima y 33 por ciento a oxacilina. Conclusiones: Las bacterias gram positivas son las más frecuentes como causa de sepsis neonatal. In vitro, los gérmenes más frecuentes muestran resistencia mayor de 50 por ciento a ampicilina y amikacina; y vancomicina es el antibiótico al cual muestran mayor susceptibilidad las especies de Staphylococcus.

Objective: To determine the most frequent bacteria causing infection in hospitalized newborns, and their antimicrobial sensitivity. Material and methods: Review of the clinical files of Neonatology Division, Children's Health Institute (Lima, Peru) and identification of the positive cultures and antibiograms from June 1999 until May 2002. Results: During this three year period there were 94 patients with confirmed sepsis from whom 161 samples were obtained (blood, urine, IV catheters, and others). The most frequently isolated bacteria were: Staphylococcus epidermidis (38,3 per cent), Staphylococcus aureus (12 per cent), Klebsiella sp (10 per cent), Alcaligenes fecalis (4,6 per cent), Acinetobacter sp (4 per cent) and Pseudomonas aeruginosa (4 per cent). S. epidermidis showed 100 per cent sensitivity to vancomycin, 90 per cent to cefotaxime, 50 per cent to amikacin and ampicillin and 37 per cent to oxacillin. Klebsiella showed 100 per cent sensitivity to ciprofloxacin and imipenem, 44 per cent to ceftriaxone, 20 per cent to ceftazidime and 14 per cent to ampicillin; bacterial resistance to amikacin was 100 per cent. S. aureus showed 100 per cent sensitivity to vancomycin, 57 per cent to cefotaxime and 33 per cent to oxacillin. Conclusions: Gram positive bacteria are the most frequent cause of neonatal sepsis. In vitro, 50 per cent of the most frequent bacteria showed resistance to ampicillin and amikacin. The Staphylococcus species showed greater in vitro sensitivity to vancomycin.