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A customized digital image correlation (DIC) system was implemented to monitor the strain produced in a cold-rolled AL-6XN stainless steel plate, 3.0 mm thick, subjected to quasi-static and cyclic loading tests. A comparison of the DIC strain measurements was made against those provided by conventional extensometers. Furthermore, the DIC system was used to monitor the fatigue crack initiation in low-cycle fatigue tests. The true stress-strain behavior for the AL-6XN material was properly captured by the DIC measurements. For low-cycle fatigue tests (strain control), the strain mapping generated by DIC allowed for identifying zones with higher strain than the nominal strain amplitude applied (εa) since the first stages of the fatigue life (FL). These zones become potential fatigue crack initiation sites.

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Respiratory diseases, including influenza and coronaviruses, pose recurrent global threats. This study delves into the respiratory surveillance systems, focusing on the effectiveness of SARI sentinel surveillance for total and severe cases incidence estimation. Leveraging data from the COVID-19 pandemic in Chile, we examined 2020-2023 data (a 159-week period) comparing census surveillance results of confirmed cases and hospitalizations, with sentinel surveillance. Our analyses revealed a consistent underestimation of total cases and an overestimation of severe cases of sentinel surveillance. To address these limitations, we introduce a nowcasting model, improving the precision and accuracy of incidence estimates. Furthermore, the integration of genomic surveillance data significantly enhances model predictions. While our findings are primarily focused on COVID-19, they have implications for respiratory virus surveillance and early detection of respiratory epidemics. The nowcasting model offers real-time insights into an outbreak for public health decision-making, using the same surveillance data that is routinely collected. This approach enhances preparedness for emerging respiratory diseases by the development of practical solutions with applications in public health.

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Various complications occur after a biliary-digestive reconstruction. Volvulus of a segment of the biliodigestive loop has not been described. Two patients who underwent biliodigestive bypass, years later, began with sudden and intense abdominal pain, associated with a volvulus with necrosis of a segment of this biliodigestive loop. This complication occurred many years after the initial correction, and manifested with sudden abdominal pain without impaired liver function, as occurred in these patients.

Diversas complicaciones pueden ocurrir después de una reconstrucción biliodigestiva. El vólvulo de un segmento del asa biliodigestiva no ha sido descrito. Dos pacientes operados de derivación biliodigestiva, años después iniciaron con dolor abdominal súbito e intenso, asociado a un vólvulo con necrosis de un segmento de la asa interpuesta. Se ha descrito el vólvulo de toda el asa interpuesta, pero no el de solo una pequeña porción de esta. La complicación ocurrió muchos años después de la corrección inicial y se manifiesto con dolor abdominal súbito sin deterioro de la función hepática, como sucedió en estos pacientes.

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In light of the ongoing COVID-19 pandemic and the emergence of new SARS-CoV-2 variants, understanding the effectiveness of various booster vaccination regimens is pivotal. In Chile, using a prospective national cohort of 3.75 million individuals aged 20 or older, we evaluate the effectiveness against COVID-19-related intensive care unit (ICU) admissions and death of mRNA-based second vaccine boosters for four different three-dose background regimes: BNT162b2 primary series followed by a homologous booster, and CoronaVac primary series followed by an mRNA booster, a homologous booster, and a ChAdOx-1 booster. We estimate the vaccine effectiveness weekly from February 14 to August 15, 2022, by determining hazard ratios of immunization over non-vaccination, accounting for relevant confounders. The overall adjusted effectiveness of a second mRNA booster shot is 88.2% (95%CI, 86.2-89.9) against ICU admissions and 90.5% (95%CI 89.4-91.4) against death. Vaccine effectiveness shows a mild decrease for all regimens and outcomes, probably linked to the introduction of BA.4 and BA.5 Omicron sub-lineages and the waning of immunity. Based on our findings, individuals might not need additional boosters for at least 6 months after receiving a second mRNA booster shot in this setting.

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AIM: The aim of this case-control study was to evaluate the association between the TNFSF13B rs9514828 (-871 C > T) polymorphism and soluble BAFF (sBAFF) in apical periodontitis (AP) patients. METHODOLOGY: Two hundred and sixty one healthy subjects (HS) and 158 patients with AP classified as: 46 acute apical abscess (AAA), 81 primary AP (pAP) and 31 secondary AP (sAP) patients were included. Genomic DNA (gDNA) was extracted from peripheral blood cells according to the salting out method. The TNFSF13B rs9514828 (NC_000013.11:g.108269025C > T) were identified using polymerase chain reaction (PCR) followed by restriction fragment length polymorphisms (RFLP). Serum sBAFF levels were measured by ELISA test. The chi-squared or Fisher's exact test was performed. Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated to evaluate the risk of AP associated with the rs9514828. The Mann-Whitney U test and Kruskal-Wallis analysis were used for non-normally distributed data. Differences were considered significant with a p-value <.05. RESULTS: No differences in the genotype/allele frequencies were shown between HS and patients with AAA. However, the TT genotype (OR = 2.68, 95% CI: 1.10-6.53; p = .025) and T allele (OR = 1.46, 95% CI: 1.00-2.12; p = .045) were associated with increased risk of pAP. In contrast, the minor allele T significantly decreased the risk of sAP (OR = 0.49, 95% CI: 0.024-0.99; p = .043). sBAFF serum levels were increased in AAA and pAP compared with HS (p < .01 and p = .021, respectively). The AAA patients had higher sBAFF serum levels than pAP (p = .034) and sAP (p < .01). CONCLUSIONS: These results suggest that the TNFSF13B rs9514828 (-871 C > T) polymorphism is associated with pAP susceptibility and that BAFF is a cytokine that might be involved in acute and chronic AP. The future exploration of the rs9514828 polymorphism in other AP cohorts is recommended.

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BACKGROUND: The criteria for the selection of COVID-19 patients that could benefit most from ECMO organ support are yet to be defined. In this study, we evaluated the predictive performance of ECMO mortality predictive models in patients with COVID-19. We also performed a cost-benefit analysis depending on the mortality predicted probability. We conducted a retrospective cohort study in COVID-19 patients who received ECMO at two tertiary care hospitals between March 2020 to July 2021. MATERIALS AND METHODS: We evaluated the discrimination (C-statistic), calibration (Cox calibration), and accuracy of the prediction of death due to severe ARDS in V-V ECMO score (PRESERVE), the Respiratory Extracorporeal Membrane Oxygenation Survival Score (RESP) score, and the PREdiction of Survival on ECMO Therapy-Score (PRESET) score. In addition, we compared the RESP score with Plateau pressure instead of Peak pressure. RESULTS: We included a total of 36 patients, 29 (80%) of them male and with a median (IQR) APACHE of 10 (8-15). The PRESET score had the highest discrimination (AUROCs 0.81 [95%CI 0.67-0.94]) and calibration (calibration-in-the-large 0.5 [95%CI -1.4 to 0.3]; calibration slope 2.2 [95%CI 0.7/3.7]). The RESP score with Plateau pressure had higher discrimination than the conventional RESP score. The cost per QALY in the USA, adjusted to life expectancy, was higher than USD 100 000 in patients older than 45 years with a PRESET > 10. CONCLUSION: The PRESET score had the highest predictive performance and could help in the selection of patients that benefit most from this resource-demanding and highly invasive organ support.

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La viruela del mono fue declarada emergencia de salud pública de importancia internacional por la Organización Mundial de la Salud el año 2022. En Chile, hasta septiembre se han confirmado sobre 450 enfermos, mayoritariamente hombres jóvenes. Este poxvirus zoonótico se transmite entre humanos por contacto estrecho; la enfermedad es autolimitada y puede ser fatal en inmunocomprometidos. La prevención mediante inmunización es importante. MVA-BN es una de las tres vacunas disponibles, de 3° generación, contiene el virus vaccinia atenuado, no replicante por lo que se puede administrar a pacientes inmunocomprometidos y mujeres embarazadas y está aprobada para viruela símica en personas > 18 años. La información disponible sobre eficacia y efectividad es limitada. El CAVEI recomienda incorporar esta vacuna para interrumpir la cadena de transmisión y reducir el riesgo de enfermedad grave, en dos dosis separadas por 28 días, por vía subcutánea, priorizando el uso post-exposición para contactos estrechos con riesgo de enfermedad grave, idealmente en los primeros 4 días y hasta 14 días post contacto de riesgo y en ausencia de síntomas. Cuando el suministro de vacunas lo permita, se recomienda prevención pre-exposición para personas con alto riesgo ocupacional o por prácticas sexuales. Esta recomendación podría modificarse según la epidemiología, el suministro de vacunas y nueva información científica.

Monkeypox was declared a public health emergency of international concern by the World Health Organization during 2022. In Chile, over 450 patients have been confirmed until September, mostly young men. This zoonotic poxvirus is transmitted from humans to humans through close contact; it is a self-limiting disease and can be fatal in people with immunodeficiency. Prevention by immunization is important. MVA-BN, one of the three vaccines available, it is a third generation vaccine, based on non-replicating modified vaccinia virus, therefore can be administered to immunocompromised patients and pregnant women and it has been approved for monkeypox in people over 18 years of age. The available information on efficacy and effectiveness is limited. The CAVEI recommends incorporating this vaccine to interrupt the chain of transmission and reduce the risk of severe disease, administered subcutaneously in two doses, 28 days apart, prioritizing post exposure use for close contacts of confirmed cases with risk of severe disease, ideally within 4 days of exposure and it can be used up to 14 days after exposure and in the absence of symptoms. When the vaccine supply allows it, its application is recommended as pre-exposure prevention for people with high-risk sexual practices or with occupational risk. This recommendation could be modified according to epidemiology, vaccines supply and new scientific information.

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BACKGROUND: The use of Appendicitis Inflammatory Response clinical score in patients with suspected acute appendicitis makes the diagnosis more objective and accurate. AIMS: The aim of this study was to prospectively compare two groups with suspected acute appendicitis, analyzing the number of imaging tests requested, waiting time in the emergency department, until definition of conduct, as well as the sensitivity and specificity of this diagnostic method. METHODS: This is a prospective randomized study comparing 55 patients submitted to clinical-radiological diagnosis according to the routine of the service (control group), with another 55 patients submitted to the Appendicitis Inflammatory Response score flowchart (intervention group). RESULTS: Waiting time for defining the intervention group's conduct was 1.5 h shorter than the control group (p=0.02). Computed tomography was performed in 42 patients in the control group, compared with 25 in the intervention group (p=0.001). The impact of the flowchart based on the Appendicitis Inflammatory Response score of the cases compared to the control group was the reduction of appendectomies with a normal-appearing appendix from 5 to 1 and an increase in the exclusion of appendicitis diagnoses. The use of the Appendicitis Inflammatory Response score resulted in a diagnostic specificity of 92%, compared to 29% in the control group. CONCLUSIONS: The use of the Appendicitis Inflammatory Response score reduced the waiting time for the diagnosis of acute appendicitis, decreased the number of imaging tests, and increased diagnostic specificity of the disease.

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The localized compressive deformation (LCD) effect generated by an indentation process at the crack tip on the fatigue crack growth of the 7075-T651 aluminum alloy is reported. Eccentrically loaded single-edge crack tension specimens (ESE(T)) were pre-cracked at a crack length of about 20 mm by applying a constant amplitude fatigue loading. Subsequently, the LCD process was performed by using a semi-spherical indenter with a radius of 16 mm to compress the crack tip zone at different forces (5.0, 7.0, 12.5, 13.5, 15.5 kN), applied on the opposite surfaces of the specimens. The fatigue cracking process was continued on the compressed samples until an overall crack length of about 30 mm was obtained. The compressive load and the number of delayed cycles is discussed in terms of crack length and crack tip opening displacement (CTOD). A direct relationship between the compressive force induced by the LCD process and the delay of the crack propagation due to the crack arrest was observed. This effect became evident at a compressive force of 5.0 kN, where the crack propagation was arrested for about 9000 cycles in comparison with the non-LCD sample. However, when the force increased, the crack arrest also increased. The crack was considered to be completely arrested at a compressive load of 15.5 kN, since the crack did not grow after the application of more than 3 × 106 cycles.

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ABSTRACT - BACKGROUND: The use of Appendicitis Inflammatory Response clinical score in patients with suspected acute appendicitis makes the diagnosis more objective and accurate. AIMS: The aim of this study was to prospectively compare two groups with suspected acute appendicitis, analyzing the number of imaging tests requested, waiting time in the emergency department, until definition of conduct, as well as the sensitivity and specificity of this diagnostic method. METHODS: This is a prospective randomized study comparing 55 patients submitted to clinical-radiological diagnosis according to the routine of the service (control group), with another 55 patients submitted to the Appendicitis Inflammatory Response score flowchart (intervention group). RESULTS: Waiting time for defining the intervention group's conduct was 1.5 h shorter than the control group (p=0.02). Computed tomography was performed in 42 patients in the control group, compared with 25 in the intervention group (p=0.001). The impact of the flowchart based on the Appendicitis Inflammatory Response score of the cases compared to the control group was the reduction of appendectomies with a normal-appearing appendix from 5 to 1 and an increase in the exclusion of appendicitis diagnoses. The use of the Appendicitis Inflammatory Response score resulted in a diagnostic specificity of 92%, compared to 29% in the control group. CONCLUSIONS: The use of the Appendicitis Inflammatory Response score reduced the waiting time for the diagnosis of acute appendicitis, decreased the number of imaging tests, and increased diagnostic specificity of the disease.

RESUMO - RACIONAL: A utilização do escore clínico Appendicitis Inflammatory Response em pacientes com suspeita de apendicite aguda torna o diagnóstico mais objetivo e preciso. OBJETIVOS: Comparar prospectivamente dois grupos com suspeita de apendicite aguda, analisando o número de exames de imagem solicitados, o tempo de espera no Pronto-Socorro, até a definição da conduta, bem como a sensibilidade e especificidade desse método diagnóstico. MÉTODOS: Estudo prospectivo randomizado comparando 55 pacientes submetidos ao diagnóstico clínico-radiológico de acordo com a rotina do Serviço (grupo controle), com outros 55 pacientes submetidos ao fluxograma do escore Appendicitis Inflammatory Response (grupo intervenção). RESULTADOS: O tempo de espera para definir a conduta do grupo intervenção foi 1,5 hora menor do que o grupo controle (p=0,02). A tomografia computadorizada foi realizada em 42 pacientes do grupo controle, em comparação com 25 do grupo intervenção (p=0,001). O impacto do fluxograma baseado no escore Appendicitis Inflammatory Response dos casos em relação ao grupo controle foi a redução de apendicectomias com apêndice de aparência normal de 5 para 1 e um aumento na exclusão de diagnósticos de apendicite. O uso do escore Appendicitis Inflammatory Response resultou em especificidade diagnóstica de 92%, comparado a 29% no grupo controle. CONCLUSÕES: A utilização do escore Appendicitis Inflammatory Response reduziu o tempo de espera para o diagnóstico de apendicite aguda, diminuiu o número de exames de imagem e aumentou a especificidade diagnóstica da doença.

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The SARS-CoV-2 pandemic has generated an important health and economic impact on the world. Vaccines emerge as an intervention that can contribute to the control of the pandemic. Vaccines were approved for emergency use in the United States, Europe, as well as in Chile, however, they will not be immediately available, creating the need to prioritize vaccine distribution. The World Health Organization (WHO) and other international agencies established ethical frameworks to guide the distribution of the COVID-19 vaccine globally. In Chile, the Advisory Council on Vaccines and Immunizations (CAVEI) and the COVID-19 Advisory Council of the Ministry of Health (MINSAL) recommended the groups to prioritize vaccination, based on the available evidence stating that this information could change over time. In this article, we propose a reference framework of ethical principles and values to support the decision-making of prioritization and distribution of vaccines in Chile. We propose three timeless values: maximizing benefits, prioritizing the most vulnerable, reciprocity, and two transversal bioethics principles: justice and transparency. This reference framework contributes to the vaccination plan communication, the decision-making by the authorities and supports the prioritization strategy's valúes framework. With an explicit values framework we can expect better communication or priorities, a greater acceptance of SARS-CoV-2 vaccination plan by the community and an increased vaccination coverage to protect the population.

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Resumen Introducción: Se define como quiste de colédoco gigante aquel con un diámetro ≥ 10 cm. A pesar de que el abordaje laparoscópico ha sido contraindicado, se presenta el caso de un adolescente con un quiste de colédoco gigante resuelto por laparoscopía. Caso clínico: Paciente de sexo masculino de 14 años con un quiste de colédoco gigante tratado con anastomosis hepático-duodenal laparoscópica. Conclusiones: El tamaño promedio de los quistes de colédoco tratados por laparoscopía es de 40 mm. No se recomienda la resección de quistes gigantes por mínima invasión debido a adherencias y restricción del campo visual. En este caso se realizó un tratamiento laparoscópico de manera exitosa.

Abstract Background: The giant choledochal cyst has a diameter ≥ 10 cm. Although laparoscopy has been contraindicated, we present the case of a teenager with a giant choledochal cyst resolved by laparoscopy. Case report: A 14-year-old male patient with a giant choledochal cyst treated with hepatic-duodenum laparoscopic anastomosis. Conclusions: The average size of bile duct cysts treated by laparoscopy is 40 mm. Giant cysts should not be resected through minimal invasion due to adhesions and a restricted visual field. We report a case of a giant cyst successfully treated by laparoscopy.

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Biological electroporation is a process of opening pores in the cell membrane when exposed to intense electric fields. This work provides results for validation of a dynamic model of electroporation on biological tissues. Computational simulations were carried out and results for the electrical current through the tissue and increase of the tissue temperature were compared to experimental results. Two calculation methods were used: Equivalent Circuit Method and Finite Element Method. With Equivalent Circuit Method the dielectric dispersion present in biological tissues was included. Liver, kidney and heart of rabbit were used in the experiments. Voltage pulse protocols and voltage ramps were applied using stainless steel needles electrodes. There is good agreement between the simulated and experimental results with mean errors below 15%, with the simulated results within the experimental standard deviation. Only for the protocol with fundamental frequency of 50 kHz, the simulation performed by the Finite Element Method using a commercial software did not correctly represent the current, with errors reaching 50%. The justification for the error found is due to the dielectric dispersion that was not included in this simulator.

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Introducción: Se define como quiste de colédoco gigante aquel con un diámetro ≥ 10 cm. A pesar de que el abordaje laparoscópico ha sido contraindicado, se presenta el caso de un adolescente con un quiste de colédoco gigante resuelto por laparoscopía. Caso clínico: Paciente de sexo masculino de 14 años con un quiste de colédoco gigante tratado con anastomosis hepático-duodenal laparoscópica. Conclusiones: El tamaño promedio de los quistes de colédoco tratados por laparoscopía es de 40 mm. No se recomienda la resección de quistes gigantes por mínima invasión debido a adherencias y restricción del campo visual. En este caso se realizó un tratamiento laparoscópico de manera exitosa.

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Our objective in this work was to summarize the main results obtained in processing pure chitosan and chitosan/hyaluronan complex in view of biomedical applications, taking advantage of their original properties. In addition, an electrospinning technique was selected to prepare nanofiber mats well adapted for tissue engineering in relation to the large porosity of the materials, allowing an exchange with the environment. The optimum conditions for preparation of purified and stable nanofibers in aqueous solution and phosphate buffer pH = 7.4 are described. Their mechanical properties and degree of swelling are given. Then, the prepared biomaterials are investigated to test their advantage for chondrocyte development after comparison of nanofiber mats and uniform films. For that purpose, the adhesion of cells is studied by atomic force microscopy (AFM) using single-cell force spectroscopy, showing the good adhesion of chondrocytes on chitosan. At the end, adhesion and proliferation of chondrocytes in vitro are examined and clearly show the interest of chitosan nanofiber mats compared to chitosan film for potential application in tissue engineering.

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The SARS-CoV-2 pandemic has generated an important health and economic impact on the world. Vaccines emerge as an intervention that can contribute to the control of the pandemic. Vaccines were approved for emergency use in the United States, Europe, as well as in Chile, however, they will not be immediately available, creating the need to prioritize vaccine distribution. The World Health Organization (WHO) and other international agencies established ethical frameworks to guide the distribution of the COVID-19 vaccine globally. In Chile, the Advisory Council on Vaccines and Immunizations (CAVEI) and the COVID-19 Advisory Council of the Ministry of Health (MINSAL) recommended the groups to prioritize vaccination, based on the available evidence stating that this information could change over time. In this article, we propose a reference framework of ethical principles and values to support the decision-making of prioritization and distribution of vaccines in Chile. We propose three timeless values: maximizing benefits, prioritizing the most vulnerable, reciprocity, and two transversal bioethics principles: justice and transparency. This reference framework contributes to the vaccination plan communication, the decision-making by the authorities and supports the prioritization strategy's valúes framework. With an explicit values framework we can expect better communication or priorities, a greater acceptance of SARS-CoV-2 vaccination plan by the community and an increased vaccination coverage to protect the population.

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In this work, optimized conditions for preparation of chitosan and hyaluronan polyelectrolyte complex are proposed. The objective was to produce new biomaterials being biocompatible and bioresorbable in the body as well as approaching the extracellular matrix (ECM) structure. These materials will be tested for chondrocyte development in tissue engineering and wound healing applications. Nanofibers made of the polyelectrolyte complex (PEC) were successfully manufactured by electrospinning, and casted films were used as a model for properties comparison. To our knowledge, it is the first time that stable chitosan/hyaluronan fibers are produced, which were observed to be long-lasting in buffer at pH~7.4. The role of thermal treatment at 120 °C for 4 h is examined to control the degree of swelling by crosslinking of the two polysaccharides by H-bonds and amide bonds formation. The properties of the materials are tested for different PEC compositions at different pH values, based on swelling and solubility degrees, diameters of nanofibers and mechanical performances. The influence of the solvent (acidic potential and composition) utilized to process biomaterials is also examined. Acid formic/water 50/50 v/v is observed to be the more appropriated solvent for the carried-out procedures.