Impacts caused by the use of screens during the COVID-19 pandemic in children and adolescents: an integrative review / Impactos causados pelo uso de telas durante a pandemia da COVID-19 em crianças e adolescentes: uma revisão integrativa

ABSTRACT Objective: To identify the scientific evidence on the impacts caused by the use of screens during the COVID-19 pandemic in children and adolescents, raising reflections for future interventions with this public. Data source: This is an integrative literature review, conducted in the databases Medical Literature Analysis and Retrieval System Online (MEDLINE), Literatura Latino-Americana e do Caribe em Ciências da Saúde (LILACS), Cumulative Index to Nursing and Allied Health Literature (CINAHL), United States National Library of Medicine (PubMed), Scopus, Web of Science, and Embase, published from March 2020 to January 2022, in Portuguese, English and Spanish. Data synthesis: The search strategies allowed retrieving 418 articles, of which 218 were duplicates. The analysis of titles and abstracts resulted in the maintenance of 62 studies. Of these, 31 were excluded from the reading of the full text, since they did not clearly present the phenomenon investigated. Thirty-one were eligible, resulting in five categories: eye consequences; increased sedentary behavior and weight; change in eating habits; implications for sleep quality and impacts on mental health. Conclusions: The excessive use of screens during the pandemic led to numerous consequences for children and adolescents, with a higher incidence of visual damage, sedentary lifestyle, inadequate eating habit and increased weight gain, in addition to impaired sleep quality and mental health. This study provides subsidy for health professionals to carry out continuing education focused on this theme, and elaborate effective interventions for this public in this transition to the post-pandemic period.

RESUMO Objetivo: Identificar as evidências científicas sobre os impactos causados pelo uso de telas durante a pandemia da COVID-19 em crianças e adolescentes, almejando reflexões para futuras intervenções com esse público. Fontes de dados: Trata-se de uma revisão integrativa da literatura, realizada nas bases de dados Medical Literature Analysis and Retrieval System Online (MEDLINE), Literatura Latino-Americana e do Caribe em Ciências da Saúde (LILACS), Cumulative Index to Nursing and Allied Health Literature (CINAHL), United States National Library of Medicine (PubMed), Scopus, Web of Science e Embase, publicados de março de 2020 a janeiro de 2022, em português, inglês e espanhol. Síntese dos dados: As estratégias de busca possibilitaram recuperar 418 artigos, sendo 218 duplicados. A análise de títulos e resumos resultou na manutenção de 62 estudos. Destes, após a leitura do texto integral foram excluídos 31, uma vez que não apresentavam com clareza o fenômeno investigado. Foram elegíveis 31 estudos, emergindo cinco categorias: consequências oculares; aumento do comportamento sedentário e do peso; alteração dos hábitos alimentares; implicações na qualidade do sono e impactos na saúde mental. Conclusões: Percebe-se que o uso telas em excesso durante a pandemia trouxe inúmeras consequências para o público infantojuvenil, com maior incidência de acometimentos visuais, sedentarismo, alimentação inadequada e, por consequência, maior ganho de peso, além de prejuízos à qualidade do sono e à saúde mental. Este estudo fornece subsídios para que os profissionais da saúde realizem educação continuada voltada para essa temática e elaborem intervenções efetivas para esse público nesta transição para o período pós-pandêmico.

Microfluidics-based study on the damage pattern of red blood cells and VWF / 国际生物医学工程杂志

Objective:To investigate the effects of shear stress magnitude and exposure time on the damage of blood component erythrocytes and von willebrand factor (VWF) based on microfluidic technology.Methods:A blood shear platform was built based on a microfluidic chip, samples were prepared under different shear stress magnitudes and exposure time lengths, free hemoglobin assay experiments were performed on blood samples, the hemolysis indices of different samples were measured, and the relative molecular masses of different samples of VWF were analyzed by immunoblotting and chemiluminescence imaging.Results:The quantitative relationships between the hemolysis index and the degradation rate of high relative molecular mass VWF with shear stress and exposure time followed the power function model well.Conclusions:The microfluidic experimental platform has the advantages of a precise and controllable internal microenvironment and easy and rapid detection, which can be used for the quantitative study of blood damage patterns.

VWF Damage Based on Novel Maglev Taylor-Couette Blood-Shearing Circulation Platform / 医用生物力学

Objective To study von Willebrand factor(VWF) damage based on a novel Maglev Taylor-Couette blood-shearing device. Methods The magnetic levitation (maglev) Taylor-Couette blood-shearing device was designed, and the blood-shearing platform was built. Fresh porcine blood was tested in circulation loop for 1 hour at laminar flow state. VWF damage was assessed by analyzing sample through Western blot and enzyme-linked immunosorbent assay. Results With the increase of exposure time and shear stress, a large number of high molecular weight VWF multimers were degraded into low molecular weight VWF. The maximum rate of degradation was 569%. When the shear stress increased from 18 Pa to 55 Pa, the ratio of VWF-Rco to VWF-Ag decreased from 45.7% to 32.8%. ConclusionsCompared with initial sample, the VWF damage was mainly manifested by the decrease of high molecular weight VWF and the decrease of VWF activity, and VWF-Ag did not change significantly. The novel maglev Taylor-Couette blood-shearing device can quantitatively control the flow parameters (exposure time and shear stress), and be used for blood damage research in vitro, thus providing references for the design and optimization of extracorporeal membrane oxygenation and blood pump.

Metodología para evaluar el nivel de protección respiratoria de mascarillas y respiradores ante partículas similares a las que transmiten el SARS-CoV-2 / Methodology for evaluating the level of respiratory protection of masks and respirators against particles similar to those that transmit SARS-CoV-2

RESUMEN Objetivo: Desarrollar una metodología para evaluar el nivel de protección respiratoria de respiradores, mascarillas quirúrgicas y mascarillas comunitarias que usa la población peruana, usando partículas de un tamaño similar a las que contienen al virus activo del SARS-CoV-2. Materiales y métodos: Se ha determinado una relación lineal directa entre el logaritmo de la concentración de partículas suspendidas en aire y el tiempo transcurrido; por lo cual es posible comparar la cantidad de partículas internas y externas a la mascarilla o respirador en un mismo periodo y conocer el porcentaje de protección respiratoria de cada muestra evaluada. Resultados: Se ha logrado implementar una metodología para evaluar el nivel de protección respiratoria ante aerosoles menores a 5,0 µm. Asimismo, el empleo de accesorios como ligas o ajustadores detrás de cabeza y nuca, y el uso de clips nasales robustos, incrementan significativamente el nivel de protección respiratoria ante partículas con alta probabilidad de contener al SARS-CoV-2. Conclusiones: Se observa una concordancia entre los valores de protección respiratoria obtenidos y los esperados, considerando el nivel de filtración del material empleado de cada mascarilla quirúrgica o respirador, y su nivel de ajuste. Se observó un incremento significativo en los niveles de protección respiratoria.

ABSTRACT Objective: To develop a methodology for evaluating the level of respiratory protection provided by respirators, surgical masks and community face masks used by the Peruvian population; protection was evaluated against particles of a size similar to those containing active SARS-CoV-2 virus. Materials and methods: A direct linear relationship has been determined between the logarithm of the concentration of airborne particles and the elapsed time; thus, it is possible to compare the quantity of particles inside and outside of the mask or respirator in the same time period, as well as to obtain the percentage of respiratory protection for each evaluated sample. Results: A methodology was established to evaluate the level of respiratory protection against aerosols smaller than 5.0 μm. Also, the use of accessories such as rubber bands or adjusters behind the head and neck, and the use of robust nasal clips, significantly increased the level of respiratory protection against particles with a high probability of containing SARS-CoV-2. Conclusions: We found concordance between the obtained respiratory protection values and those expected, considering the filtration level of the material used for each surgical mask or respirator, as well as the tightness. A significant increase in the levels of respiratory protection was observed.

Fatores determinantes no tempo de tela de crianças na primeira infância / Determining factors in children's screen time in early childhood

Resumo O uso de mídias por crianças na primeira infância está cada vez mais habitual, o que torna necessário investigar os fatores determinantes para o tempo de tela, entendido como o tempo total pelo qual a criança permanece exposta a todas as telas, incluindo televisão e mídias interativas. Trata-se de um estudo transversal, descritivo e exploratório, realizado com 180 crianças, entre 24 a 42 meses de idade, alocadas em: Grupo 1, exposição à tela inferior a duas horas/dia; Grupo 2, exposição à tela igual/superior a duas horas/dia. Realizou-se análise bivariada e de regressão logística binária. Os fatores determinantes no tempo de tela estudados foram os recursos do ambiente familiar, investigado por meio do Inventário de Recursos do Ambiente Familiar; fatores socioeconômicos; estado nutricional e status do desenvolvimento infantil, mensurado pelo teste Bayley III. Como resultado verificou-se que 63% das crianças apresentaram tempo de tela superior a 2 horas/dia e que a televisão ainda é a principal responsável pela exposição das crianças às telas. Observou-se que o tempo de exposição à tela esteve positivamente associado aos recursos familiares, nível econômico e desenvolvimento da linguagem. Entretanto, apenas os dois últimos fatores explicaram o maior tempo de tela.

Abstract The use of media by children in early childhood is increasingly common, and it is necessary to investigate the determinants of screen time, which is understood as the total child screen exposure time, including television and interactive media. This is a descriptive, exploratory, and cross-sectional study conducted with 180 children between 24 and 42 months of age, allocated in Group 1, less than two hours daily screen exposure time; Group 2, daily screen exposure time equal to or more than two hours. Bivariate and binary logistic regression analyses were performed. Screen time determining factors studied were family environment, evaluated with the Family Environment Resource Inventory; socioeconomic factors; nutritional status and child development status, evaluated with the Bayley III test. As a result, 63% of children had daily screen time exceeding two hours, and television still is the main culprit for children screen exposure. We observed that screen time exposure was positively associated with family resources, economic level, and language development. However, only the last two factors explained the longer screen time.

Diagnosis of new occupational lung tumor in Guangdong Province / 中国职业医学

OBJECTIVE: To summarize and analyze the diagnostic ideas of new occupational lung tumors in Guangdong Province.METHODS: According to the Law of the People′s Republic of China on the Prevention and Control of Occupational Disease and the GBZ 94-2002 Diagnostic Criteria of Occupational Cancer, the key diagnostic points of 6 new occupational lung tumors diagnosed in Guangdong Province from 2010 to 2011 were analyzed. RESULTS: There were 9 cases of 6 new kinds of new occupational tumors were diagnosed in Guangdong Province in 2010-2011. The cases included 3 occupational lung cancer of coke oven workers, 2 occupational lung cancer caused by asbestos, 1 occupational mesothelioma caused by asbestos, 1 occupational lung cancer caused by arsenate, 1 occupational lung cancer caused by chromate salt, and 1 occupational lung cancer caused by asphalt. During the process, the diagnosis was based on the principles of the comprehensive analysis and the attribution diagnosis, combined with occupational history, occupational disease hazard exposure history, clinical data and auxiliary examination results. If the patients were diagnosed with a primary tumor, the patients′ exposure history to occupational carcinogens should be tracked, traced and confirmed, and the diagnosis should be confirmed by referring to the list of occupational carcinogens and literature reports of the International Labor Organization, and not limited to only the personnel in a particular industry. CONCLUSION: During the diagnostic process of occupational tumors, attention should be paid to confirm the exposure history of occupational carcinogen. The key is to determine the exposure of corresponding occupational carcinogen, the route and the time of exposure and the incubation period.

Gender and the capacity to identify facial emotional expressions / Gênero e a capacidade de identificação de emoções expressas pela face / El género y la capacidad de identificación de emociones expresadas por el rostro

Recognizing emotional expressions is enabled by a fundamental sociocognitive mechanism of human nature. This study compared 114 women and 104 men on the identification of basic emotions on a recognition task that used culturally adapted and validated faces to the Brazilian context. It was also investigated whether gender differences on emotion recognition would vary according to different exposure times. Women were generally better at detecting facial expressions, but an interaction suggested that the female superiority was particularly observed for anger, disgust, and surprise; results did not change according to age or time exposure. However, regardless of sex, total accuracy improved as presentation times increased, but only fear and anger significantly differed between the presentation times. Hence, in addition to the support of the evolutionary hypothesis of the female superiority in detecting facial expressions of emotions, recognition of facial expressions also depend on the time available to correctly identify an expression.

A habilidade de reconhecer emoções é um mecanismo sociocognitivo fundamental à vida humana. Este estudo comparou 114 mulheres e 104 homens na identificação de emoções básicas no teste de reconhecimento facial, adaptado e validado para o contexto brasileiro. Investigou-se, também, se a diferença de gênero no reconhecimento das emoções poderia variar conforme o tempo de exposição. As mulheres foram melhores na detecção das expressões faciais, mas uma interação sugeriu que a superioridade foi particularmente observada nas emoções de raiva, nojo e surpresa; esses resultados não alteraram conforme idade e tempo de exposição. Entretanto, independentemente do sexo, a acurácia total melhorou conforme aumentou o tempo de apresentação, sendo que apenas o reconhecimento de medo e raiva diferiu entre os tempos de apresentação. Assim, além de apoiar a hipótese da superioridade do sexo feminino em reconhecer expressões faciais emocionais, o reconhecimento das emoções faciais também depende do tempo disponível para conseguir identificá-las.

Reconocer emociones es fruto de un mecanismo sociocognitivo fundamental para los humanos. Se comparó el desempeño de 114 mujeres y 104 hombres en la identificación de emociones básicas en la prueba de reconocimiento facial adaptado para el contexto brasileño. Se investigó también la diferencia de género en el reconocimiento de las emociones según diferentes tiempos de exposición. Las mujeres obtuvieron mejores resultados en la detección de las expresiones, pero una interacción sugirió que la superioridad fue especialmente observada para rabia, repugnancia y sorpresa. Los resultados no han cambiado según la edad o tiempo de exposición. Sin embargo, independientemente del sexo, la precisión total mejoró a medida que aumentaron los tiempos de presentación, pero sólo la detección de miedo y repugnancia se diferenció entre los tres tiempos. Luego, además de la confirmación de la hipótesis evolutiva de la superioridad femenina, el reconocimiento de las expresiones faciales también depende del tiempo disponible.

Study on maternal serum total bile acids in intrahepatic cholestasis of pregnancy on neonatal lung injury / 重庆医学

Objective To explore the correlation between maternal serum total bile acid (TBA) of pregnant women with intrahepatic cholestasis of pregnancy (ICP) and varying degrees of neonatal lung injury.Methods A total of 52 cases of pregnant women with ICP and their corresponding newborns were enrolled into the ICP group from March 2014 to December 2015 in the People's Hospital of Shapingba District.Other 52 cases of pregnant women received cesarean delivery whose gestational age and birth weight of newborns were close to the ICP group and their corresponding newborns were selected as the control group.The conditions of neonatal lung injury were recorded,and the correlations of maternal serum level of TBA and exposure time of high serum level of TBA to degrees of lung injury were analyzed as well.Results The incidence rate of neonatal lung injury in the ICP group (67.3 ％) was higher than that in the control group (17.3 ％),there was statistically significant difference (P＜0.05).The degree of lung injury was positively correlated with maternal serum level of TBA and exposure time of high serum level of TBA (r=0.687,P=0.000;r=0.523,P=0.001).Conclusion The probability of neonatal lung injury of corresponding pregnant women with ICP is significantly increased,and the extent of lung injury is positively correlated with concentration of maternal serum TBA and exposure time of high serum level of TBA.

Relationship Between Salivary Pepsin Concentration and Esophageal Mucosal Integrity in Patients With Gastroesophageal Reflux Disease

BACKGROUND/AIMS: Increased salivary pepsin could indicate an increase in gastro-esophageal reflux, however, previous studies failed to demonstrate a correlation between salivary pepsin concentrations and 24-hour esophageal acid exposure. This study aims to detect the salivary pepsin and to evaluate the relationship between salivary pepsin concentrations and intercellular spaces (IS) in different gastroesophageal reflux disease phenotypes in patients. METHODS: A total of 45 patients and 11 healthy volunteers were included in this study. All subjects underwent upper gastrointestinal endoscopy, 24-hour ambulatory multichannel impedance-pH (MII-pH) monitoring, and salivary sampling at 3-time points during the 24-hour MII-pH monitoring. IS were measured by transmission electron microscopy, and salivary pepsin concentrations were determined by enzyme-linked immunosorbent assay. RESULTS: The IS measurements were greater in the esophagitis (EE), non-erosive reflux disease (NERD), and hypersensitive esophagus (HO) groups than in the functional heartburn (FH) and healthy volunteer groups, and significant differences were indicated. Patients with NERD and HO had higher average pepsin concentrations compared with FH patients. A weak correlation was determined between IS and salivary pepsin among patients with NERD (r = 0.669, P = 0.035). CONCLUSIONS: We confirmed the presence of a higher level of salivary pepsin in patients with NERD than in patients with FH. Salivary pepsin concentrations correlated with severity of mucosal integrity impairment in the NERD group. We suggest that in patients with NERD, low levels of salivary pepsin can help identify patients with FH, in addition the higher the pepsin concentration, the more likely the severity of dilated IS.

Clinical Outcomes of Indocyanine Green-Assisted Peeling of the Internal Limiting Membrane in Epiretinal Membrane Surgery

PURPOSE: In this study we compared the clinical outcomes of idiopathic epiretinal membrane (ERM) surgery according to the use of indocyanine green (ICG) and ICG exposure time. METHODS: The medical records of 76 patients with an idiopathic ERM that underwent vitrectomy and ERM and internal limiting membrane (ILM) removal were reviewed. We compared the results (best corrected visual acuity [BCVA, log MAR] and central macular thickness [CMT, µm]) of idiopathic ERM surgeries using ILM peeling with (group I, 39 eyes) and without ICG (group II, 37 eyes). Additionally, the correlation of ICG exposure time and clinical outcomes in group I was analyzed. RESULTS: Gender, age, lens state, preoperative BCVA, and preoperative CMT were not significantly different between the two groups. The postoperative BCVA was significantly improved in both groups but the difference was not statistically significant. The postoperative CMT was significantly improved in both groups and the change amount of group I was more larger than group II. Additionally, ICG exposure time was not significantly correlated with changes of BCVA and CMT. CONCLUSIONS: Intravitreal ICG-assisted ILM peeling did not significantly affect the recovery of BCVA, however that impaired the recovery of CMT. ICG exposure time did not affect the postoperative visual outcome.

Establishment and validation of classifiers to predict genotoxic and non-genotoxic carcinogens / 中国药学杂志

OBJECTIVE: To establish classifiers to predict genotoxic and non-genotoxic carcinogens using toxicogenomics methods, explore the effect of exposure time and validated the prediction performance of the classifiers. METHODS: The primary mouse hepatocyte model was treated for 24 and 48 h with two genotoxic carcinogens, aflatoxin Bl (AFB1), benzo(a) pyrene (BAP) and two non-genotoxic carcinogens, thioacetamide (TAA), wyeth-14643 (WY). The differentially expressed genes were input to prediction analysis for microarray (PAM) software to screen out classifiers. The functions and interrelations of genes in classifiers were studied by gene set enrichment analysis (GSEA) and the protein-protein interactions were predicted using STRING database. Two additional carcinogens to validate the prediction performance of the classifiers were used. Finally, the experiment of QuantiGene Multiplex assay (Q-GP) to validate the microarray data was used. RESULTS: Forty-eight h classifiers had a better predicted capability than that of 24 h classifiers. p53 pathway, TNF-α signaling pathway, fatty acid metabolism, PPAR signaling pathway involved in the classifires were enriched by GSEA. Carcinogenic protein-protein interaction network and metabolism-related protein-protein interaction network are obtained using STRING database. The predicted probability of the two additional carcinogens using 48 h classifiers was nearly 100% and data between QuantiGene Multiplex assay and microarray assay had a high conformity. CONCLUSION: The classifiers which could be used to discriminate the potential genotoxic carcinogens and non-genotoxic carcinogens and to predict modes of action for unknown compounds, are successfully established and validated. This might be a promising candidate in vitro method for carcinogenicity study in the field of nonclinical safety evaluation of drugs.

Epidemiology of athletic injuries in classic ballet practitioners / Epidemiologia de lesiones musculoesqueleticas en practicantes de balé clásico / Epidemiologia de lesões musculoesqueléticas em praticantes de ballet clássico

Specific overloads of ballet practice may represent risk factors for injuries. The objective of this study was to analyze the epidemiology of typical injuries of ballet, including factors associated with history of injury in ballet practitioners. Studied subjects integrated 124 dancers, of both genders, from nine ballet schools from Campo Grande, Mato Grosso do Sul State, Brazil. To obtain information about injuries, we used a morbidity survey. Participants were divided into two groups: G1 (with injuries) and G2 (without injuries). In relation to prevalence of injuries, 89 cases were registered, and 61 dancers (49%) reported damages incidence, with record of 1.48 cases per practitioner. Moreover, the G2 presented higher body weight (G1: 51±8 versus G2: 55±10 kg) and training time (G1: 4.0±2.0 versus G2: 5.0±4.1 years). With respect to injury type, joints (32%) and muscle affections (25%) were the main occurrences in the lower limbs (85%) due to specific exercises (30%). Weekly exposure time was the most important mechanism to injury installation. The more important causal circumstance to injury occurrence was constituted by specific training (49%) and choreographic performance (41%). In conclusion, evidences have showed that joint injuries in lower limbs are the main classical ballet injuries in ballet practitioners, and weekly exposure time is the most important factor associated with injuries in classical ballet.

Demandas específicas de la práctica de balé pueden representar factores de riesgo para lesiones musculoesqueleticas. Eso estudio tuvo como objetivo analizar la epidemiologia de lesiones típicas del balé, con factores asociados a la historia de lesión en bailarines. Hubo la integración de 124 participantes de los dos géneros, procedentes de nueve escuelas de balé de Campo Grande, Mato Grosso do Sul, Brasil. Se utilizó una averiguación de morbidad referida para registrar las lesiones. Los participantes fueron distribuidos en dos grupos: G1, sin lesión, y G2, con lesión. Con relación a la presencia de lesión, se registraron 89 casos, y 61 bailarines (un 49%) reportaron lesiones con registro de 1,48 casos por practicante. El G2 presentó mayor masa corporal (G1: 51±8 versus G2: 55±10 kg) y tiempo de entrenamiento (G1: 4,0±2,0 versus G2: 5,0±4,1 años). Hubo predominancia de lesiones articulares (32%) y musculares (25%) en las extremidades inferiores (85%) originarias de ejercicios específicos (30%). El mayor tiempo semanal de práctica se configuró como el principal factor de riesgo para lesión. La circunstancia que más causó lesiones fue el entrenamiento específico (49%), seguido por el ensayo de coreografía (41%). Se concluso que las lesiones articulares en extremidades inferiores son las principales lesiones del balé clásico, y el tiempo semanal de exposición se constituye el principal factor asociado a las lesiones en el balé clásico.

Demandas específicas da prática de ballet podem representar fatores de risco para lesões musculoesqueléticas. Este estudo teve por objetivo analisar a epidemiologia das lesões típicas do ballet, com fatores associados ao histórico de lesão em bailarinos. A casuística integrou 124 participantes de ambos os sexos, procedentes de nove escolas e companhias de ballet de Campo Grande, no Mato Grosso do Sul. Para registro de lesões, utilizou-se um inquérito de morbidade referida. Os participantes foram distribuídos em dois grupos: G1, sem lesão, e G2, com lesão. Em relação à presença de lesão, foram registrados 89 casos, sendo que 61 bailarinos (49%) relataram terem se lesionado, com registro de 1,48 casos por praticante. O G2 apresentou maior massa corporal (G1: 51±8 versus G2: 55±10 kg) e tempo de treinamento (G1: 4,0±2,0 versus G2: 5,0±4,1 anos). Houve predomínio de lesões articulares (32%) e musculares (25%) nos membros inferiores (85%), decorrentes de exercícios específicos (30%). O maior tempo semanal de prática configurou o principal fator de risco para lesão. A circunstância que mais provocou lesões foi o treino específico (49%), seguido pelo ensaio de coreografia (41%). Conclui-se que as lesões articulares em membros inferiores são as principais lesões do ballet clássico, e o tempo semanal de exposição constitui o principal fator associado a lesões no ballet clássico.

Influence of light-exposure methods and depths of cavity on the microhardness of dual-cured core build-up resin composites

Objective: The purpose of this study was to evaluate the Knoop hardness number (KHN) of dual-cured core build-up resin composites (DCBRCs) at 6 depths of cavity after 3 post-irradiation times by 4 light-exposure methods. Material and Methods: Five specimens each of DCBRCs (Clearfil DC Core Plus [DCP] and Unifil Core EM [UCE]) were filled in acrylic resin blocks with a semi-cylindrical cavity and light-cured using an LED light unit (power density: 1,000 mW/cm2)at the top surface by irradiation for 20 seconds (20 s), 40 seconds (40 s), bonding agent plus 20 seconds (B+20 s), or 40 seconds plus light irradiation of both sides of each acrylic resin block for 40 seconds each (120 s). KHN was measured at depths of 0.5, 2.0, 4.0, 6.0, 8.0, and 10.0 mm at 0.5 hours, 24 hours, and 7 days post-irradiation. Statistical analysis was performed using repeated measures ANOVA and Tukey's compromise post-hoc test with a significance level of p<0.05. Results: For both DCBRCs, at 0.5 hours post-irradiation, the 20 s and 40 s methods showed the highest KHN at depth of 0.5 mm. The 40 s method showed significantly higher KHN than the 20 s method at all depths of cavity and post-irradiation times, except UCE at depth of 0.5 mm (p<0.05). The 120 s method did not result in significantly different KHN at all depths of cavity and post-irradiation times (p>0.05). In DCP, and not UCE, at 24 hours and 7 days post-irradiation, the B+20 s method showed significantly higher KHN at all depths of cavity, except the depth of 0.5 mm (p<0.05). Conclusion: KHN depends on the light-exposure method, use of bonding agent, depth of cavity, post-irradiation time, and material brand. Based on the microhardness behavior, DCBRCs are preferably prepared by the effective exposure method, when used for a greater depth of cavity. .

The case-case-time-control study design / 中华流行病学杂志

Although the ‘self-matched case-only studies' (such as the case-cross-over or self-controlled case-series method) can control the time-invariant confounders (measured or unmeasured) through design of the study,however,they can not control those confounders that vary with time.A bidirectional case-crossover design can be used to adjust the exposure-time trends.In the areas of pharmaco-epidemiology,illness often influence the future use of medications,making a bidirectional study design problematic.Suissa' s case-time-control design combines the case-crossover and the case-control design which could adjust for exposure-trend bias,but the control group may reintroduce selection bias,if the matching does not go well.We propose a "case-case-time-control" design which is an extension of the case-time-control design.However,rather than using a sample of external controls,we choose those future cases as controls for current cases to counter the bias that arising from temporal trends caused by exposure to the target of interest.In the end of this article we will discuss the strength and limitations of this design based on an applied example.

Avaliação da efetividade de sanitizantes alcalino-clorados contra Listeria monocytogenes / Evaluation of the effectiveness of alkaline-chlorinated sanitizers against Listeria monocytogenes

Listeria monocytogenes é uma crescente preocupação para a indústria devido à sua capacidade de crescer em temperatura de refrigeração durante o armazenamento de alimentos. Falhas na erradicação dessa bactéria podem resultar em grandes perdas econômicas e sérios problemas de saúde pública. Este trabalho teve por objetivo analisar 32 cepas de L. monocytogenes isoladas de diferentes alimentos frente a dois sanitizantes alcalino clorados em diferentes concentrações e tempos de exposição. Os resultados mostraram que o produto A, na concentração recomendada pelo fabricante, eliminou 46,8% das cepas no tempo mediano de 30 minutos. Já o produto B, eliminou 50% das cepas no tempo mediano de 15 minutos. Concluímos que apesar de estar em suspensão a bactéria mostrou certa resistência ao produto alcalino clorado e o tempo de exposição representa um fator determinante para eficácia do produto.

Listeria monocytogenes is a growing concern for the industry due to its ability to grow at refrigeration temperature for food storage. Failures in the eradication of this bacterium can result in large economic losses and serious problems in public health. This study aimed to analyze 32 strains of L. monocytogenes isolated from different foods in front of two chlorinated alkaline sanitizers at different concentrations and exposure times. The results showed that the product A at the concentration recommended by the manufacturer, removed 46.8% of the strains in the median time of 30 '. Have the product B, eliminated 50% of the strains at the median of 15 '. We conclude that despite being in the suspended bacteria showed some resistance to the chlorinated alkaline product and exposure time is the determining factor for product effectiveness.

Radiation Exposure of the Hand and Chest during C-arm Fluoroscopy-Guided Procedures

BACKGROUND: The C-arm fluoroscope is an essential tool for the intervention of pain. The aim of this study was to investigate the radiation exposure experienced by the hand and chest of pain physicians during C-arm fluoroscopy-guided procedures. METHODS: This is a prospective study about radiation exposure to physicians during transforaminal epidural steroid injection (TFESI) and medial branch block (MBB). Four pain physicians were involved in this study. Data about effective dose (ED) at each physician's right hand and left side of the chest, exposure time, radiation absorbed dose (RAD), and the distance from the center of the X-ray field to the physician during X-ray scanning were collected. RESULTS: Three hundred and fifteen cases were included for this study. Demographic data showed no significant differences among the physicians in the TFESIs and MBBs. In the TFESI group, there was a significant difference between the ED at the hand and chest in all the physicians. In physician A, B and C, the ED at the chest was more than the ED at the hand. The distance from the center of the X-ray field to physician A was more than that of the other physicians, and for the exposure time, the ED and RAD in physician A was less than that of the other physicians. In the MBB group, there was no difference in the ED at the hand and chest, except for physician D. The distance from the center of the X-ray field to physician A was more than that of the other physicians and the exposure time in physician A was less than that of the other physicians. CONCLUSIONS: In conclusion, the distance from the radiation source, position of the hand, experience and technique can correlate with the radiation dose.

Influência de diferentes protocolos de fotoativação no grau de conversão e dureza de resinas ortodônticas / Influence of different curing protocols in degree of conversion and hardness the resins orthodontics

A presente Dissertação foi composta de dois estudos. O primeiro estudo avaliou in vitro a influência de diferentes tempos de exposição e potências, mantendo-se a mesma energia total, no grau de conversão (GC) e dureza superficial Knoop de três resinas ortodônticas (Transbond XT, Opal Bond MV e Transbond Plus Color Change) fotoativadas por um LED de 3a geração. A análise do GC foi realizada pelo método de Espectroscopia de infravermelho por transformada de Fourier (FT-IR) em nove grupos (n=5) e a dureza superficial Knoop também foi avaliada em nove grupos (n=15), sendo todos os grupos divididos de acordo com as resinas, potências e tempos utilizados. O segundo estudo comparou o GC de duas resinas ortodônticas (Transbond XT e Opal Bond MV) fotoativadas por um LED de 2a geração e um de 3a geração dada uma mesma densidade de energia. A análise do GC foi realizada pelo método de Espectroscopia infravermelho por transformada de Fourier (FT-IR) em quatro grupos (n=5) divididos de acordo com as resinas e gerações de LED utilizados. Os valores obtidos nos dois estudos foram analisados pelo teste ANOVA de dois níveis. No primeiro estudo, as resinas apresentaram iguais graus de conversão quando fotoativadas pelos tempos T1(8,5s) e T2(6s) e menor grau de conversão em T3 (3s). A resina Transbond Plus Color Change apresentou maior grau de conversão, seguido pela Opal Bond MV cujo grau de conversão foi maior que o da Transbond XT. As resinas apresentaram menor dureza quando fotoativadas pelo tempo T1 (8,5s), mas não houve diferença entre os tempos T2 (6s) e T3 (3s). A resina Transbond Plus Color Change apresentou maior dureza superficial do que a Opal Bond MV, sendo ambos os grupos mais duros do que Transbond XT. Foi detectada interação entre as resinas e os tempos utilizados na dureza das resinas. No segundo estudo, não houve diferença entre os graus de conversão das resinas testadas quando fotoativadas pelo LED de 2ª geração e 3ª geração, porém houve diferença entre os graus de conversão entre as duas resinas, a Opal Bond MV apresentou maior grau de conversão do que a Transbond XT. No primeiro estudo, pode-se concluir que, a polimerização com variação da potência e do tempo, mantendo a energia total constante, interfere no grau de conversão e dureza das três resinas ortodônticas estudadas. O tempo pode ser diminuído e a potência aumentada sem efeito negativo entre os tempos T1 e T2, porém, causando pequena diminuição no grau de conversão no tempo T3. Em relação à dureza superficial, há um efeito positivo quando o tempo é diminuído. No segundo estudo pode-se concluir que dada uma mesma densidade de energia, não houve influência do LED de 2ª e 3ª geração no grau de conversão das resinas ortodônticas testadas, porém, estas apresentaram diferentes graus de conversão entre si, sendo que a resina Opal Bond MV apresentou maior grau de conversão em relação à resina Transbond XT

The present dissertation consisted of two studies. The first study was aimed at assessing in vitro the influence of different exposure times and potencies, keeping the same total energy, on the degree of conversion and Knoop surface micro-hardness of three orthodontic resins (Transbond XT, Opal Bond MV, and Transbond Plus Colour Change) lightcured with a third-generation LED unit. The second study was aimed at comparing the degree of conversion of two orthodontic resins (Transbond XT and Opal Bond MV) light-cured by using 2nd and 3rd generation LED units operating at the same power density. In the first study, the degree of conversion was assessed by using the Fourier transform infrared spectroscopy (FT-IR) in nine groups (n = 15), whereas the Koop surface micro-hardness was assessed in nine groups, with groups being divided according to the resins, potency and exposure time. In the second study, the degree of conversion was also assessed by using FT-IF in four groups (n = 5) divided according to resins and LEDs used. The values obtained were analysed with two-tailed ANOVA. Resins light-cured at T1 (8.5s) and T2 (6s) showed the same values for degree of conversion, but a lower value at T3 (3s). The Transbond Plus Colour Change resin showed the highest degree of conversion, followed in the order by Opal Bond MV and Transbond XT ones. Resins showed a decreased micro-hardness when light-cured at T1 (8.5s), but no difference was found between T2 (6s) and T3 (3s). The Transbond Plus Colour Change resin showed a greater surface micro-hardness than the Opal Bond MV resin, with both groups being harder than the Transbond XT resin. A relationship between resins and exposure time was found regarding the micro-hardness of these materials. No difference was found between the degrees of conversion of the resins light-cured with 2nd and 3rd generation LEDs, although Opal Bond MV resin had a higher degree of conversion compared to the Transbond XT one. In the first study, one can conclude that variation in potency and exposure time interferes with the degree of conversion and micro-hardness of the three orthodontic resins during their polymerization, even keeping the total energy constant. Exposure time can be reduced and potency increased without having a negative effect between T1 and T2, despite causing a small decrease in the degree of conversion at T3. Also, there is a positive effect on the surface micro-hardness when exposure time is reduced. In the second study, one can conclude that 2nd and 3rd generation LEDs had no influence on the degree of conversion of orthodontic resins when operating at the same power potency, although the resins have different degrees of conversion compared to each other

Effect of reduced exposure times on the cytotoxicity of resin luting cements cured by high-power led

OBJECTIVE: Applications of resin luting agents and high-power light-emitting diodes (LED) light-curing units (LCUs) have increased considerably over the last few years. However, it is not clear whether the effect of reduced exposure time on cytotoxicity of such products have adequate biocompatibility to meet clinical success. This study aimed at assessing the effect of reduced curing time of five resin luting cements (RLCs) polymerized by high-power LED curing unit on the viability of a cell of L-929 fibroblast cells. MATERIAL AND METHODS: Disc-shaped samples were prepared in polytetrafluoroethylene moulds with cylindrical cavities. The samples were irradiated from the top through the ceramic discs and acetate strips using LED LCU for 20 s (50 percent of the manufacturer's recommended exposure time) and 40 s (100 percent exposure time). After curing, the samples were transferred into a culture medium for 24 h. The eluates were obtained and pipetted onto L-929 fibroblast cultures (3x10(4) per well) and incubated for evaluating after 24 h. Measurements were performed by dimethylthiazol diphenyltetrazolium assay. Statistical significance was determined by two-way ANOVA and two independent samples were compared by t-test. RESULTS: Results showed that eluates of most of the materials polymerized for 20 s (except Rely X Unicem and Illusion) reduced to a higher extent cell viability compared to samples of the same materials polymerized for 40 s. Illusion exhibited the least cytotoxicity for 20 s exposure time compared to the control (culture without samples) followed by Rely X Unicem and Rely X ARC (90.81 percent, 88.90 percent, and 83.11 percent, respectively). For Rely X ARC, Duolink and Lute-It 40 s exposure time was better (t=-1.262 p=0,276; t=-9.399 p=0.001; and t=-20.418 p<0.001, respectively). CONCLUSION: The results of this study suggest that reduction of curing time significantly enhances the cytotoxicity of the studied resin cement materials, therefore compromising their clinical performance.

Infiltração coronária em dentes tratados endodonticamente e com perda da restauração provisória / Coronal leakage in endodontically treated teeth and loss of temporary restoration

Objetivo: analisar a infiltração coronária após a perda da restauração provisória em dentes tratados endodonticamente. Metodologia: Trinta dentes unirradiculares foram divididos em três grupos experimentais, de acordo com o tempo de exposição ao agente marcador: Grupo A = 3 dias, Grupo B = 10 dias e Grupo C = 15 dias. Depois de obturados a restauração provisória foi feita com Cimpat e os dentes permaneceram 15 dias em estufa a 37°C e 100% de umidade. Após esse período, foi removido o material restaurador e foram colocadas em um recipiente contendo Nanquim e levados para estufa. Decorrido o tempo de permanência de cada um dos grupos, foi realizado o processo de diafanização dos dentes. Os dentes diafanizados foram avaliados por quanto o grau de infiltração do corante. Os dados obtidos foram submetidos ao teste exato de Fisher, com nível de significância de 5%. Resultados: O grupo C apresentou uma maior área de infiltração em relação aos grupos A e B, embora não tenha ocorrido diferença estatística significativa ao nível de 5%. Conclusão: Houve infiltração coronária nos três períodos testados, não havendo diferença estatística significativa entre os grupos, entretanto o tempo de 15 dias de exposição apresentou maior grau de infiltração coronária.

This study aimed to examine the coronal leakage after the loss of the temporary restoration of endodontically treated teeth. Thirty single-rooted teeth were divided into three groups according to exposure time to the official scorer: Group A = 3 days, Group B = 10 days and Group C = 15 days. Once filled the provisional restoration was made with Cimpat and teeth remained 15 days at 37 ° C and 100% humidity. After this period, was removed from the restorative material and the teeth had their roots sealed with nail varnish and placed in a container containing the dye marker nanjing and taken to the greenhouse. After the dwell time of each group, was removed from sealing teeth and made the diaphanization process. Diaphanized teeth were evaluated by two examiners regarding the degree of dye penetration. The data were subjected to Ficher´s exact test with significance of 5% which showed no statistical difference between groups. Results: Group C showed a greater infiltration area in relation to groups A and B, while there was no statistically significant difference at 5%. Conclusion: There coronal leakage in all three periods. No statistically significant differences between groups, but the time of 15 days of exposure had a greater degree of coronal leakage.

Comparison of the Effects of Patterned and Conventional Laser Photocoagulation in Branch Retinal Vein Occlusion

PURPOSE: To compare the clinical effect and complications between patterned laser photocoagulation with short exposure time and conventional laser photocoagulation for neovascularization in branch retinal vein occlusion (BRVO). METHODS: A prospective study was conducted on 36 patients (39 eyes) who required laser photocoagulation for neovascularization due to BRVO. The patients were divided into 2 groups, the patterned laser photocoagulation group (laser exposure time 0.02 sec, 3 x 3 array patterned photocoagulation) and conventional laser photocoagulation group (laser exposure time 0.2 sec). Other laser parameters (burn intensity and spot size) were the same. Pain score at the time of treatment was monitored after the laser photocoagulation. In addition, best-corrected visual acuity as well as central macular thickness measurements were performed before the treatment and after 2, 4, 8, and 12 weeks. The regression of neovascularization in fluorescein angiography was monitored during follow-up periods. RESULTS: The patterned laser photocoagulation group had a greater reduction in pain during laser photocoagulation, and a decreased change in central macular thickness after laser photocoagulation than the conventional laser photocoagulation group. In particular, the patterned laser photocoagulation group had a statistically significant difference between the 2 groups at postoperative 8 and 12 weeks. The regression rate of neovascularization between the 2 groups had no statistically significant difference. CONCLUSIONS: Patterned laser photocoagulation with a short exposure time decreases pain and postoperative macular edema with no difference in regression of neovascularization. Patterned laser photocoagulation with a short exposure time can be considered as a useful and efficient method for neovascularization in BRVO.