215 research outputs found

    Design, Assembly and Working Modes of Spherical 3-RRR Coaxial Parallel Robot

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    Design, configuration and operation modes of spherical 3-_RRR coaxial parallel robot were performed. A mathematical analysis of the robot was made, which consists of inverse and forward kinematic using geometric and numerical methods respectively, using MATLAB environment. Based on the above, eight possible operation and configuration modes were derived. The proposed approach demonstrates that a unique solution for the specific configuration and operation mode of a coaxial robot can be calculated. Moreover, mechanical design of the robot prototype was performed in the SolidWorks design program presented in detail for experimental verification of the performed numerical and simulation analyses. Results obtained from this work can be implemented in the development of real time orientation control systems for coaxial robots. As future works, an analysis of singularities, performance and dynamic will be carried out. © 2021 IEEE

    The natural history of primary sclerosing cholangitis in 781 children. A multicenter, international collaboration

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    There are limited data on the natural history of primary sclerosing cholangitis (PSC) in children. We aimed to describe the disease characteristics and long-term outcomes of pediatric PSC. We retrospectively collected all pediatric PSC cases from 36 participating institutions and conducted a survival analysis from the date of PSC diagnosis to dates of diagnosis of portal hypertensive or biliary complications, cholangiocarcinoma, liver transplantation, or death. We analyzed patients grouped by disease phenotype and laboratory studies at diagnosis to identify objective predictors of long-term outcome. We identified 781 patients, median age 12 years, with 4,277 person-years of follow-up; 33% with autoimmune hepatitis, 76% with inflammatory bowel disease, and 13% with small duct PSC. Portal hypertensive and biliary complications developed in 38% and 25%, respectively, after 10 years of disease. Once these complications developed, median survival with native liver was 2.8 and 3.5 years, respectively. Cholangiocarcinoma occurred in 1%. Overall event-free survival was 70% at 5 years and 53% at 10 years. Patient groups with the most elevated total bilirubin, gamma-glutamyltransferase, and aspartate aminotransferase-to-platelet ratio index at diagnosis had the worst outcomes. In multivariate analysis PSC-inflammatory bowel disease and small duct phenotypes were associated with favorable prognosis (hazard ratios 0.6, 95% confidence interval 0.5-0.9, and 0.7, 95% confidence interval 0.5-0.96, respectively). Age, gender, and autoimmune hepatitis overlap did not impact long-term outcome. CONCLUSION: PSC has a chronic, progressive course in children, and nearly half of patients develop an adverse liver outcome after 10 years of disease; elevations in bilirubin, gamma-glutamyltransferase, and aspartate aminotransferase-to-platelet ratio index at diagnosis can identify patients at highest risk; small duct PSC and PSC-inflammatory bowel disease are more favorable disease phenotypes

    Worldwide diagnostic reference levels for single-photon emission computed tomography myocardial perfusion imaging: findings from INCAPS.

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    OBJECTIVES: This study sought to establish worldwide and regional diagnostic reference levels (DRLs) and achievable administered activities (AAAs) for single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). BACKGROUND: Reference levels serve as radiation dose benchmarks to compare individual laboratories against aggregated data, helping to identify sites in greatest need of dose reduction interventions. DRLs for SPECT MPI have previously been derived from national or regional registries. To date there have been no multiregional reports of DRLs for SPECT MPI from a single standardized dataset. METHODS: Data were submitted voluntarily to the INCAPS (International Atomic Energy Agency Nuclear Cardiology Protocols Study), a cross-sectional, multinational registry of MPI protocols. A total of 7,103 studies were included. DRLs and AAAs were calculated by protocol for each world region and for aggregated worldwide data. RESULTS: The aggregated worldwide DRLs for rest-stress or stress-rest studies employing technetium Tc 99m-labeled radiopharmaceuticals were 11.2 mCi (first dose) and 32.0 mCi (second dose) for 1-day protocols, and 23.0 mCi (first dose) and 24.0 mCi (second dose) for multiday protocols. Corresponding AAAs were 10.1 mCi (first dose) and 28.0 mCi (second dose) for 1-day protocols, and 17.8 mCi (first dose) and 18.7 mCi (second dose) for multiday protocols. For stress-only technetium Tc 99m studies, the worldwide DRL and AAA were 18.0 mCi and 12.5 mCi, respectively. Stress-first imaging was used in 26% to 92% of regional studies except in North America where it was used in just 7% of cases. Significant differences in DRLs and AAAs were observed between regions. CONCLUSIONS: This study reports reference levels for SPECT MPI for each major world region from one of the largest international registries of clinical MPI studies. Regional DRLs may be useful in establishing or revising guidelines or simply comparing individual laboratory protocols to regional trends. Organizations should continue to focus on establishing standardized reporting methods to improve the validity and comparability of regional DRLs

    Methicillin-resistant staphylococcus aureus in children attending school in cartagena, colombia

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    Objective Determining nasal carriers of methicillin-resistant Staphylococcus aureus (MRSA) and associated risk factors for nasal colonisation in a school-aged population in the seaside city of Cartagena, Colombia. Methods A cross-sectional, analytical study was carried out on 100 healthy schoolchildren to determine MRSA nasal carriage and its association with risk factors. Bacteria were identified using conventional methods. Antibiotic sensitivity was determined by the Kirby Bauer method. Results A total of 36 isolates of S. aureus were identified in the school children. 25 % of the strains were oxacillin-resistant, 66.7 % oxacillin-sensitive and 8.3 % had intermediate susceptibility. 67 % of the MRSA strains isolated were sensitive to all antibiotics tested. One strain (MRSA-Ant4) showed resistance to antibiotics having different mechanisms of action. Conclusions This is the first study in Cartagena which determined the frequency of S. aureus and MRSA strains nasal carriers in a school population (33 % and 9 %, respectively). All S. aureus oxacillin-resistant strains were cephoxitin-resistant, thereby leading to the presence of the mecA gene being suspected. Having used beta-lactam antibiotics during the last three months increased the likelihood of being an MRSA nasal carrier by around five times (OR=4.72; 0.96-23.98 95 %CL; pObjetivo Determinar portadores nasales de Staphylococcus aureus resistente a meticilina (SARM) y factores de riesgo asociados a esta colonización, en una población escolar de Cartagena de Indias.  Métodos Se realizó un estudio analítico  transversal en 100 niños escolares sanos, para la búsqueda de portadores nasales de cepas SARM y su asociación con factores de riesgo. Para la identificación bacteriana se utilizaron métodos convencionales. A todos los aislamientos se les determinó la sensibilidad a antibióticos por el método de Kirby-Bauer. Resultados De la población escolar, se identificaron 36 cepas de S. aureus; 25 %, oxacilino-resistentes; 66,7 %, oxacilino-sensibles y 8,3 %, con sensibilidad intermedia. El 67 % de cepas SARM aisladas fueron sensibles a todos los antibióticos probados. Una cepa (SARM-Ant4) presentó resistencia a tres antibióticos con mecanismos de acción diferentes. Conclusiones Este es el primer estudio realizado en Cartagena, que determinó las frecuencias de portadores nasales de S. aureus y cepas SARM en una población escolar, registrándose un 33 % y 9 %, respectivamente. Todas las cepas de S. aureus oxacilino-resistente, fueron también cefoxitino-resistente, lo que hace sospechar la presencia del gen mecA.  El uso de antibióticos betalactámicos en los últimos tres meses, incrementa aproximadamente cinco veces más el riesgo de ser portador nasal de cepas SARM (aOR=4,72 [IC95%=0,96-23,98] 

    Ursodeoxycholic Acid Therapy in Pediatric Primary Sclerosing Cholangitis : Predictors of Gamma Glutamyltransferase Normalization and Favorable Clinical Course

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    Objective To investigate patient factors predictive of gamma glutamyltransferase (GGT) normalization following ursodeoxycholic acid (UDCA) therapy in children with primary sclerosing cholangitis. Study design We retrospectively reviewed patient records at 46 centers. We included patients with a baseline serum GGT level >= 50 IU/L at diagnosis of primary sclerosing cholangitis who initiated UDCA therapy within 1 month and continued therapy for at least 1 year. We defined "normalization" as a GGT level Results We identified 263 patients, median age 12.1 years at diagnosis, treated with UDCA at a median dose of 15 mg/kg/d. Normalization occurred in 46%. Patients with normalization had a lower prevalence of Crohn's disease, lower total bilirubin level, lower aspartate aminotransferase to platelet ratio index, greater platelet count, and greater serum albumin level at diagnosis. The 5-year survival with native liver was 99% in those patients who achieved normalization vs 77% in those who did not. Conclusions Less than one-half of the patients treated with UDCA have a complete GGT normalization in the first year after diagnosis, but this subset of patients has a favorable 5-year outcome. Normalization is less likely in patients with a Crohn's disease phenotype or a laboratory profile suggestive of more advanced hepatobiliary fibrosis. Patients who do not achieve normalization could reasonably stop UDCA, as they are likely not receiving clinical benefit. Alternative treatments with improved efficacy are needed, particularly for patients with already-advanced disease.Peer reviewe

    Cardiovascular testing recovery in Latin America one year into the COVID-19 pandemic: An analysis of data from an international longitudinal survey.

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    The INCAPS COVID Investigators Group, listed by name in the Appendix, thank cardiology and imaging professional societies worldwide for their assistance in disseminating the survey to their memberships. These include alphabetically, but are not limited to, American Society of Nuclear Cardiology, Arab Society of Nuclear Medicine, Australasian Association of Nuclear Medicine Specialists, Australia-New Zealand Society of Nuclear Medicine, Belgian Society of Nuclear Medicine, Brazilian Nuclear Medicine Society, British Society of Cardiovascular Imaging, Conjoint Committee for the Recognition of Training in CT Coronary Angiography Australia and New Zealand, Consortium of Universities and Institutions in Japan, Danish Society of Cardiology, Gruppo Italiano Cardiologia Nucleare, Indonesian Society of Nuclear Medicine, Japanese Society of Nuclear Cardiology, Moscow Regional Department of Russian Nuclear Medicine Society, Philippine Society of Nuclear Medicine, Russian Society of Radiology, Sociedad Española de Medicina Nuclear e Imagen Molecular, Society of Cardiovascular Computed Tomography, and Thailand Society of Nuclear Medicine.Peer reviewe

    International impact of COVID-19 on the diagnosis of heart disease

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    Background: The coronavirus disease 2019 (COVID-19) pandemic has adversely affected diagnosis and treatment of noncommunicable diseases. Its effects on delivery of diagnostic care for cardiovascular disease, which remains the leading cause of death worldwide, have not been quantified. Objectives: The study sought to assess COVID-19's impact on global cardiovascular diagnostic procedural volumes and safety practices. Methods: The International Atomic Energy Agency conducted a worldwide survey assessing alterations in cardiovascular procedure volumes and safety practices resulting from COVID-19. Noninvasive and invasive cardiac testing volumes were obtained from participating sites for March and April 2020 and compared with those from March 2019. Availability of personal protective equipment and pandemic-related testing practice changes were ascertained. Results: Surveys were submitted from 909 inpatient and outpatient centers performing cardiac diagnostic procedures, in 108 countries. Procedure volumes decreased 42% from March 2019 to March 2020, and 64% from March 2019 to April 2020. Transthoracic echocardiography decreased by 59%, transesophageal echocardiography 76%, and stress tests 78%, which varied between stress modalities. Coronary angiography (invasive or computed tomography) decreased 55% (p < 0.001 for each procedure). In multivariable regression, significantly greater reduction in procedures occurred for centers in countries with lower gross domestic product. Location in a low-income and lower–middle-income country was associated with an additional 22% reduction in cardiac procedures and less availability of personal protective equipment and telehealth. Conclusions: COVID-19 was associated with a significant and abrupt reduction in cardiovascular diagnostic testing across the globe, especially affecting the world's economically challenged. Further study of cardiovascular outcomes and COVID-19–related changes in care delivery is warranted
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