Total Study Time Research Articles

1 Youth Experiencing Homelessness Presenting to an Urban Paediatric Emergency Department: A Descriptive Study

Abstract Background Youth experiencing homelessness (YEH) have high rates of both mental and physical health concerns. This population faces multiple barriers in accessing care, resulting in unaddressed needs and reliance on Emergency Departments (ED). In Canada, the use of the paediatric ED by YEH has not been well described, and there is no data exploring the effects of the COVID-19 pandemic lockdown on ED attendance by this population. Objectives This study aims: 1) To review the frequency/nature of the presentations to the paediatric ED by YEH; 2) To compare pre- and post-COVID-19 data. Design/Methods Medical records were searched for ED encounters where a patient identified a youth shelter as their address and/or had terms documented such as “homeless”, during two time periods: pre-COVID-19 (May 1, 2018–March 15, 2020) and post-COVID-19 lockdown (March 16, 2021–Jan 31, 2022). Pertinent details of the encounters were documented, including chief complaint (CC). Descriptive statistics were used, as well as comparative analysis of the two time periods. Results A total of 1103 encounters were included. Over the total 45-month study time period, CCs were split between mental health-related (n=562, 50.9%) and physical health-related presentations (n=541, 49%). Of the mental health CCs, 396 (70.4%) were documented as “depression/overdose/suicidal/self-harm”. The most common CCs related to physical health were injuries (n=127, 23.4%), and pain (n=126, 23.2%). YEH most commonly attended the paediatric ED between 17:00-00:00 (n=504, 45%), and were triaged as CTAS 3/urgent (n = 676, 61.2%). Of those who completed an Ask Suicide-Screening Questionnaire (ASQ) (n=303), 45.8% (n=139) had an acute positive screen/imminent risk identified. The most common principal diagnoses documented at disposition were related to injuries/assault/pain (n= 224, 20%), and suicide attempt/self-harm (n=196, 17.7%). Of the 166 outpatient referrals made at discharge from ED, 105 (63%) were to mental health/psychiatry. While overall there were fewer ED encounters for this population “post COVID-lockdown” (n=465) as compared to “pre-COVID” (n=638) (p-value <0.05), there was a significant reduction in mental health-related CCs (pre-COVID n=365, post-COVID n=197; p-value <0.05), with no significant reduction in physical-related CCs after the pandemic lockdown (pre-COVID, n=273, n=268). Conclusion YEH utilize the paediatric ED for both their mental and physical healthcare and frequently report suicide risk. The findings that lower attendance to the paediatric ED for mental health-related concerns followed the pandemic lockdown, while physical health encounters remained steady, may reflect increased barriers to care or novel methods of mental health care delivery post-pandemic.

INDEPENDENT WORK OF HIGHER EDUCATION SEEKERS AS THE HIGHEST FORM OF PROFESSIONAL FORMATION AND PERSONAL DEVELOPMENT

The article analyzes the essence of the concepts "independent work", "self-education", "independence" and their relationship and interdependence. The types of independent work in the process of educational and extracurricular activities are characterized. Approaches to their classification according to various criteria are presented. The organization of independent work in institutions of higher education is characterized, including its purpose, content, forms, methods, and conditions of effectiveness, which are determined. The higher school is gradually but steadily moving from the transfer of information to the management of educational and cognitive activities, the formation of the abilities and skills of independent work in the students of higher education. According to the Regulation on the Organization of the Educational Process in Higher Education Institutions, the independent work of students of higher education is the main means of mastering educational material in the time that is free from compulsory educational classes. The study time allocated for the independent work of higher education seekers is regulated by the curriculum and must be no less than 1/3 and no more than 2/3 of the total study time of students devoted to the study of specific disciplines.
 The conditions-factors of the effectiveness of the organization of independent work of higher education seekers have been determined. They include: organizational (time management, educational literature and corresponding facilities); methodical (planning, teaching methods of acquiring information and managing the independent work); psychological and pedagogical (taking into account the individual psychological qualities and properties of the higher education seekers); information-technology (the degree of accessibility of new information systems, the level of computer literacy); organization of control and assessment (observance of systematicity and phasing in the organization and conduct of independent work). The results of a study among higher education applicants regarding the effectiveness of organizing independent work in universities are highlighted.

Asynchronous learning among otolaryngology residents in the United States

ObjectiveOtolaryngology resident learning has historically relied on didactic lectures, textbook reading, and practical hands-on patient care. However, evidence suggests that an increasing proportion of residents in other specialties are deviating from this paradigm. This work aims to characterize otolaryngology residents' current asynchronous learning practices (i.e., personal learning outside of didactics and patient care). MethodsA thirteen-question survey of otolaryngology residents in the United States was performed from 10/1/2020–12/1/2020 assessing demographics, educational resource utilization, and educational resource preference. ResultsNearly all (99 %) respondents reported engaging with educational materials outside of didactics and case prep. Textbook reading comprised 27 % of residents' total study time, with additional time split between board-review book reading (20 %), searching the web (18 %), watching online videos (15 %), and listening to podcasts (10 %). Residents' highest ranked resources were videos, board-review books, textbooks, podcasts, and recorded lectures. Among electronic and multimedia resources, more than half of residents used the following resources: Iowa Head and Neck Protocols (91 %), Board Vitals (75 %), UpToDate (60 %), YouTube (57 %), Google (56 %), and Headmirror (54 %). ConclusionCurrent otolaryngology resident learning involves substantial use of asynchronous learning, including videos, web-based learning, and podcasts, which currently outpace traditional textbook- and didactic-based education. This underscores the need to consider a paradigm shift within academic otolaryngology education away from textbooks and other tradition media to the generation of high-quality multimedia resources for resident learning.

Going beyond the spacing effect: Does it matter how time on a task is distributed?

We assessed the effects of removing some constraints that characterise traditional experiments on the effects of spaced, rather than massed, study opportunities. In five experiments-using lists of to-be-remembered words-we examined the effects of how total study time was distributed across multiple repetitions of a given to-be-remembered word. Overall, within a given list, recall profited from study time being distributed (e.g., four 1-s presentations or two 2-s presentations vs one 4-s presentation). Among the implications of these findings is that if students choose to engage in massed studying (by virtue of constraints on their study time or a failure to appreciate the benefits of spaced study sessions), then studying the information twice but for half the time may produce memory benefits in a single study session.

Effect of Covid-19 Pandemic on Formal Education of Primary School Children (6-11 Years) Studying in Selected Municipal Corporation Primary Schools of East Delhi

The sudden closure of schools in the Covid-19 pandemic has affected formal and informal education of the students especially belonging to socially disadvantaged groups. To explore the impact of this pandemic on the formal education of primary school children an online Google Meet Parent Teacher Meeting Survey was conducted after 16 months of school closure to learning pattern, reading material, reading frequency of Hindi and English, daily study, and its association with socio economic background. This web-based school study used descriptive design. A sample of parents of 400 students age group 6 to 11 years from fi ve selected schools of East Delhi Municipal Corporation available on Google Meet was selected through stratifi ed random sampling. Data was collected through a Structured Interview Schedule with closed ended multiple choice questions designed into Google doc forms and fi lled by researchers simultaneously during survey. Data was analysed using SPSS (26) software descriptive statistics. This study showed an increase in the variety of reading material availability for students as well as increased reading frequency per week of basic languages i.e., 33.8 percent to 90.3 percent for Hindi and 23 percent to 40.3 percent for English along with total study time per day, 39.2 percent to 78.6 percent. Further, guardian education and guardian income have a direct effect on reading frequency of primary school children and total study time during periods of lockdown. Parents' engagement and sensitisation is required for problems faced by the students in adaptation to online education to reduce learning gap and improve outcomes of teaching-learning process due to lockdown and sudden school closure. Reading material can be provided to students to sustain their interest and reading ability during Covid-19 pandemic.

Análise dos materiais didáticos utilizados por radiologistas e residentes de radiologia brasileiros: mudança de paradigma.

Objective:To profile the use of educational materials by radiologists and radiology residents in Brazil.Materials and Methods:This was a cross-sectional, descriptive, observational study in which an electronic questionnaire was sent via email to physicians working in the field of radiology. The questionnaire contained questions regarding the profile, education, and place of work of the physicians, as well as their access to educational resources and the types of educational materials they used most.Results:The questionnaire was completed by 265 physicians. The mean age of the respondents was 38.2 years. Of the 265 respondents, 212 (80.0%) worked with ultrasound, 206 (77.7%) worked with computed tomography, 170 (64.2%) were board-certified, 166 (62.6%) were male, 174 (65.7%) worked at private facilities, and 167 (63.0%) had no academic affiliation. The mean weekly total study time was 9.6 h (median, 6 h), being higher among physicians in training, among those who worked at public facilities, and among those who worked at teaching hospitals. Regarding the device employed in order to access educational materials, there was a trend toward greater use of computers, which were employed by 65.3%. The majority of the respondents (61.9%) chose to access educational materials that were free of charge, the most common sources being websites, eBooks, and online journals.Conclusion:Electronic and digital resources are the main means of access to educational materials used by radiologists in Brazil, the most commonly used resources being web sites, eBooks, and online journals.

Medical students’ pattern of self-directed learning prior to and during the coronavirus disease 2019 pandemic period and its implications for Free Open Access Meducation within the United Kingdom

PurposeSelf-directed learning (SDL) has been increasingly emphasized within medical education. However, little is known about the SDL resources medical students use. This study aimed to identify patterns in medical students’ SDL behaviors, their SDL resource choices, factors motivating these choices, and the potential impact of the coronavirus disease 2019 (COVID-19) pandemic on these variables.MethodsAn online cross-sectional survey comprising multiple-choice, ranked, and free-text response questions were disseminated to medical students across all 41 UK medical schools between April and July 2020. Independent study hours and sources of study materials prior to and during the COVID-19 pandemic were compared. Motivational factors guiding resource choices and awareness of Free Open Access Meducation were also investigated.ResultsThe target sample was 75 students per medical school across a total of 41 medical schools within the United Kingdom (3,075 total students), and 1,564 responses were analyzed. University-provided information comprised the most commonly used component of independent study time, but a minority of total independent study time. Independent study time increased as a result of the COVID-19 pandemic (P<0.001). All sub-cohorts except males reported a significant increase in the use of resources such as free websites and question banks (P<0.05) and paid websites (P<0.05) as a result of the pandemic. Accessibility was the most influential factor guiding resource choice (Friedman’s μrank=3.97, P<0.001).ConclusionThe use of learning resources independent of university provision is increasing. Educators must ensure equitable access to such materials while supporting students in making informed choices regarding their independent study behaviors.

To What Extent Do Study Habits Relate to Performance?

Students’ study sessions outside class are important learning opportunities in college courses. However, we often depend on students to study effectively without explicit instruction. In this study, we described students’ self-reported study habits and related those habits to their performance on exams. Notably, in these analyses, we controlled for potential confounds, such as academic preparation, self-reported class absences, and self-reported total study time. First, we found that, on average, students used approximately four active strategies to study and that they spent about half of their study time using active strategies. In addition, both the number of active strategies and the proportion of their study time using active strategies positively predicted exam performance. Second, on average, students started studying 6 days before an exam, but how early a student started studying was not related to performance on in-term (immediate) or cumulative (delayed) exams. Third, on average, students reported being distracted about 20% of their study time, and distraction while studying negatively predicted exam performance. These results add nuance to lab findings and help instructors prioritize study habits to target for change.

Channel dynamics and geomorphological adjustments of Kaljani River in Himalayan foothills

Channel dynamics is a significant geomorphological process that involves the channel migration, erosion-deposition and meandering of an alluvial river channel within its floodplain region. This geomorphic process is often accelerated by climatic condition and human activities which changes this natural process to a quasi-natural hazard. Current research work tries to evaluate the changing behaviour or dynamic nature of alluvial channel by enlightening average length and shape migration. Finally, state of the art techniques in Arc GIS has been adopted to prepare the mouza (village) wise erosion-deposition map by considering highly fluctuating mouzas of the Kaljani River and its adjacent village at the Himalayan foothill region. The primary data source was a series of time-sequential Landsat data of the years 1972, 1980, 1987, 1993, 1998, 2002, 2008, 2013, and 2019 spanning 47 years. Furthermore, we divided total study time into eight groups i.e. 1972–1980, 1980–1987, 1987–1993, 1993–1998, 1998–2002, 2002–2008, 2008–2013, and 2013–2019 for better understanding. During the study period (1972–2019) the average length of migration of the Kaljani River was 742.05 m and the annual rate was 15.79 m/year. Within this time frame of 1972–2019, the shape area migration of the channel was 66.79 km2 and the annual rate was 1.42 km2/year. The total area of bank erosion from 1972 to 2019 equaled 62.74 km2, out of which, 30.07 km2 were on the right bank and 32.67 km2 were at the left bank. Present analysis helps to enhance the effectiveness of planning and management of land resources and ecological balances in these 45 adjacent Mouzas of the Kaljani River. Among the various important causes, tectonic activity, rainfall, floods, and human intervention especially constriction of the embankment along the Kaljani River are the most significant causes for this dynamic changes of River Kaljani. The results of this study therefore, can be used as an important indicator of the vulnerability of the Kaljani River and also provides information about geomorphological instabilities of the study area.

Productivity in partly mechanized planting operations of willow short rotation coppice

Biomass for energetic use can be procured from various sources including willow short rotation crops (WSRC). The feasibility of willow crops, however, is dependent on the costs incurred by operations such as the plantation, maintenance, harvesting and transport. In small scale applications, cost balancing often results in the use of equipment designed for general agricultural purposes to carry on the operational management of WSRC. This study evaluated the productive performance in planting operations of WSRC for a planting equipment consisting of regular farming tractors used to propel machines designed to support planting on single twin rows. Planting equipment consisting of 4 different types of farming tractors fitted with willow planting equipment was tested in 14 filed plots to be able to compute the main performance indicators such as the net and gross productivity rates. An evident variability in terms of time consumption on categories was observed at plot-level, and the planting time was related to a great extent to the operated area. The size of areas subjected to planting operations was the most important factor that affected productive performance. Variation of net productivity rate was explained largely by the ratio of the length of headland returning maneuvers to total length covered in a given plot. The model developed for the total study time shows that, in the observed conditions, it may take more than 7 h to plant one hectare. The equipment taken into study stands for a flexible option for small-scale farmers which could increase the utilization rates of their farming tractors by using them in other agricultural operations when needed. In addition, the studied equipment fits well to very narrow and small-sized plots, as such situation is typical to Romania and other European countries.

Harbor Porpoise (Phocoena phocoena) Reaction to a 3D Seismic Airgun Survey in the North Sea

The most common cetacean in the North Sea is the harbour porpoise (Phocoena phocoena). Underwater noise is increasingly recognised as a source of impact on the marine environment, and 3D seismic and airguns were are one some of the first man-made high intensity sound sources to receive attention with respect to potential impact on marine mammals. In this study, we investigate the effects of a 3D seismic survey on harbour porpoise echolocation activity in the Danish sector of the North Sea. This was achieved by deploying porpoise click detectors (C-PODs) and sound recorders (SM2M and SM3M) both inside and adjacent to the seismic survey area, before, during and after the survey over a (total study time wasduration of nine months in total). Three echolocation parameters were analysed: number of clicks per minute, minutes with porpoise echolocation click trains and feeding buzz frequency in relation to all minutes with click trains. Decreases in echolocation signals were detected up to 8-12 km from the active airguns, which may indicate temporary displacement of porpoises or a change in porpoise echolocation behaviour. No general displacement of harbour porpoises away from the seismic survey area could be detected when comparing to reference stations 15 km away from any seismic activity. However, nNo general displacement of harbour porpoises away from the seismic survey area could be detected when comparing to reference stations 15 km away from any seismic activity. decreases in recorded echolocation signals were detected up to 8-12 km from the active airguns, which indicate temporary displacement of porpoises and/or a change in porpoise echolocation behaviour. Our results add to the understanding that underwater noise has the potential to affect temporarily foraging efficiency in porpoises. While the effect of seismic surveys on harbour porpoise behaviour was smaller than what has been found for pile-driving, the cumulative effect of the different anthropogenic impacts should could be performed assessed by evaluation of potential population level consequences.

End-tidal capnography provides reliable ventilatory monitoring for non-intubated patients presenting after sedative overdose to the emergency department.

To assess the ability of end-tidal capnography to provide continuous ventilatory monitoring in sedated, non-intubated ED patients following sedative overdose. Observational study undertaken in a tertiary hospital ED. Patient ventilation was assessed using capnography over 60 min. Capnography provided uninterrupted monitoring for 99% of total study time. Capnography detected all episodes of hypoxia detected by SpO2 monitoring. Changes in capnography preceded 70% of hypoxic episodes detected by SpO2 . There were no major adverse events or incidents of device failure. Capnography provided reliable measurement of ventilatory function in sedated non-intubated, poisoned ED patients.

True Grit: Passion and persistence make an innovative course design work.

Our first two experiments on adapting a high-structure course model to an essentially open-enrollment university produced negative or null results. Our third experiment, however, proved more successful: performance improved for all students, and a large achievement gap that impacted underrepresented minority students under traditional lecturing closed. Although the successful design included preclass preparation videos, intensive active learning in class, and weekly practice exams, student self-report data indicated that total study time decreased. Faculty who have the grit to experiment and persevere in making evidence-driven changes to their teaching can reduce the inequalities induced by economic and educational disadvantage.

Do solar study lamps help children study at night? Evidence from rural India

Lack of adequate and consistent lighting has a detrimental impact on the overall well-being of poor households in India. For school-going children in these households, this challenge has contributed to issues such as difficulty in studying after dark, reduced performance in schools, increased dropout from school due to poor educational outcomes, and exposure to pernicious emissions from predominantly kerosene-burning wick lamps. Use of off-grid solar lamps in these poor households has the potential to address these challenges. There is limited research investigating the impact of solar lamps on school going children in rural India. We analyzed the data collected from the Million Solar Urja Lamp Program (MSP) implemented in four states of India. The survey of 873 rural poor households in the states of Madhya Pradesh, Maharashtra, Rajasthan, and Odisha utilized a purposive random sampling method to reveal that the use of solar lamps increased total study time (TST) per day during dark hours from 88 to 118 min in the impact period. Furthermore, enhancement in study time was found more for girls (32 min/day) than boys (27 min/day). Total kerosene expenditures in these households decreased from 0.94 US$ to 0.67 US$ per month while total electricity expenditures dropped from 3.7 US$ to 3.5 US$ per month. The findings shows that number of rooms, household head's education, and the child's class have a positive and significant influence on TST in dark hours at home. A notable observation was that the use of kerosene-burning lighting during the impact period shows a negative correlation with TST in dark hours as compared to baseline period due to the adoption of solar study lamps. The results also show that with increment in studying time, a large number of children moved from lower study time group to moderate and higher study time group.

Comparison of Study Activity Times for “Full” versus “Fast MRI” for Breast Cancer Screening

PurposeTo optimize operations for a newly implemented abbreviated MR (AB-MR) breast cancer screening protocol, activity times were compared with the full-protocol examination. MethodsActivity times from 70 AB-MR and 736 full MR screening studies were analyzed. Total study time was measured from opening to closing examinations and expected scan time by summing the time of acquisition for each imaging series for either protocol. Actual scan time was obtained from DICOM headers. Total technologist activity time was obtained by subtracting expected scan time from total study time. Technologist activity time included both scan-related and non-scan-related activities. ResultsThe actual scan time for the AB protocol was 17.5 ± 0.5 min, compared with 28.8 ± 0.3 min (mean ± SE) for the full protocol (difference, 11.3 min; P < .0001). The total study time was 36.0 ± 3.2 min for AB-MRI and 49.7 ± 0.8 min for the full protocol (difference, 13.7 min; P < .0001), implying that the AB-MR protocol had only a 38% greater patient flow rate than the full protocol. ConclusionsThe realized gains in patient flow rate were lower than expected based on scan times (65%) because of increased technologist activity time for the AB-MR protocol.

Strain-encoded cardiac magnetic resonance imaging: a new approach for fast estimation of left ventricular function

BackgroundRecently introduced fast strain-encoded (SENC) cardiac magnetic resonance (CMR) imaging (fast-SENC) provides real-time acquisition of myocardial performance in a single heartbeat. We aimed to test the ability and accuracy of real-time strain-encoded CMR imaging to estimate left ventricular volumes, ejection fraction and mass.MethodsThirty-five subjects (12 healthy volunteers and 23 patients with known or suspected coronary artery disease) were investigated. All study participants were imaged at 1.5 Tesla MRI scanner (Achieva, Philips) using an advanced CMR study protocol which included conventional cine and fast-SENC imaging. A newly developed real-time free-breathing SENC imaging technique based on the acquisition of two images with different frequency modulation was employed.ResultsAll parameters were successfully derived from fast-SENC images with total study time of 105 s (a 15 s scan time and a 90 s post-processing time). There was no significant difference between fast-SENC and cine imaging in the estimation of LV volumes and EF, whereas fast-SENC underestimated LV end-diastolic mass by 7%.ConclusionThe single heartbeat fast-SENC technique can be used as a good alternative to cine imaging for the precise calculation of LV volumes and ejection fraction while the technique significantly underestimates LV end-diastolic mass.

Does a parsimonious measure of complex body mass index trajectories exist?

Background:A single measure that distills complex body mass index (BMI) trajectories into one value could facilitate otherwise complicated analyses. This study creates and assesses the validity of such a measure: average excess BMI.Methods:We use data from Waves I-IV of the National Longitudinal Study of Adolescent to Adult Health (n=17 669). We calculate average excess BMI by integrating to find the area above a healthy BMI trajectory and below each subject-specific trajectory and divide this value by total study time. To assess validity and utility, we (1) evaluate relationships between average excess BMI from adolescence to adulthood and adult chronic conditions, (2) compare associations and fit to models using subject-specific BMI trajectory parameter estimates as predictors, and (3) compare associations to models using BMI trajectory parameter estimates as outcomes.Results:Average excess BMI from adolescence to adulthood is associated with increased odds of hypertension (OR = 1.56; 95% CI: 1.47, 1.67), hyperlipidemia (OR = 1.36; 95% CI: 1.26, 1.47), and diabetes (OR = 1.57; 95% CI: 1.47, 1.67). The odds associated with average excess BMI are higher than the odds associated with the BMI intercept, linear, or quadratic slope. Correlations between observed and predicted health outcomes are slightly lower for some models using average excess BMI as the focal predictor compared to those using BMI intercept, linear, and quadratic slope. When using trajectory parameters as outcomes, some covariates associate with the intercept, linear, and quadratic slope in contradicting directions.Conclusions:This study supports the utility of average excess BMI as an outcome. The higher an individual’s average excess BMI from adolescence to adulthood, the greater their odds of chronic conditions. Future studies investigating longitudinal BMI as an outcome should consider using average excess BMI, whereas studies that conceptualize longitudinal BMI as the predictor should continue using traditional latent growth methods.

Patient-ventilator interaction with conventional and automated management of pressure support during difficult weaning from mechanical ventilation

PurposeOptimizing pressure support ventilation (PSV) can improve patient-ventilator interaction. We conducted a two-center, randomized cross-over study to determine whether automated PSV lowers asynchrony rate during difficult weaning from mechanical ventilation. MethodsThirty patients failing the first weaning attempt were randomly ventilated for 2 three-hour consecutive periods with: 1)PSV managed by physicians (convPSV); 2)PSV managed by Smartcare® (autoPSV). These 2 periods were applied in the afternoon and overnight, for a 12-h total study time. Two independent clinicians offline analyzed ventilator waveforms to compute asynchrony index(AI). ResultsAI was lower during autoPSV than during convPSV (medians[interquartile ranges] 5.1[2.6–9.5]% vs. 7.3[2.3–13.4]%, p = 0.02), without changes in the proportion of patients with AI>10%(p = 0.31). Pressure support (PS) variability was higher during autoPSV (p < 0.001), but average PS did not vary. In patients with baseline PS > 12 cmH2O (n = 15), PS and tidal volume were lower with autoPSV (12 [10-15]cmH2O vs. 15 [14-18]cmH2O,p = 0.003; 7.2[6.2–8.3]ml/Kg vs. 8.2[7.1–9.1]ml/Kg, p = 0.02) and AI reduction was driven by lower tidal volume (p = 0.03). In patients with baseline PS ≤ 12 cmH2O, AI reduction during autoPSV was mediated by increased PS variability (p = 0.04). ConclusionDuring difficult weaning, autoPSV improves patient-ventilator interaction by lowering tidal volume and enhancing PS variability. In expert centres, however, the size effect of the intervention appears clinically small, likely because physicians themselves adequately limit PS and tidal volume.

The effect of microRNA-21 on myocardial fibrosis in mice with chronic viral myocarditis

Objective: To explore the effect of microRNA-21 (miR-21) on myocardial fibrosis in mice with chronic viral myocarditis (CVMC) and related mechanisms. Methods: Forty 4-week-old Balb/c male mice were randomly divided into 4 groups (n=10 each): phosphate buffer saline (PBS) group, CVMC group, CVMC+miR-21 inhibitor group, CVMC+isotype control group. The first injection of Coxsackie virus B3 (CVB3) or PBS was performed on day 0, and the total study time was 42 days. Each mouse in CVMC group, CVMC+miR-21 inhibitor group and CVMC+isotype control group was intraperitoneally (i.p) injected with 100TCID50 CVB3 0.1, 0.15, and 0.2 ml on day 0, 14, and 28, respectively. The mice in PBS group were i.p injected with the same dose of PBS at the same time point. After the initial infection, each mouse in CVMC+miR-21 inhibitor group and CVMC+isotype control group was intravenously injected with 0.1 ml miR-21 inhibitor or 0.1 ml isotype control, on day 14 and 28. Cardiac function was measured on surviving mice of 4 groups by echocardiography on day 42. Then, the hearts were removed aseptically to observe the expressions of green fluorescence protein (GFP). The myocardial pathological changes were examined with HE, Masson staining and the myocardial pathological scores (PS), the collagen volume fraction (CVF) were calculated respectively. The levels of miR-21, collagen typeⅠ-A1 (COL1-A1) and collagen type Ⅲ-A1 (COL3-A1) mRNA in heart were detected by quantitative real-time polymerase chain reaction (RT-qPCR). Furthermore, the expressions of transforming growth factor-β1 (TGF-β1) and mothers against decapentaplegic homolog 7(Smad7) in heart were determined with Western blot assay. Results: (1) Cardiac function in 4 groups: Compared with PBS group, left ventricular end systolic diameter (LVESD) and left ventricular end diastolic diameter (LVEDD) were markedly increased in CVMC group and CVMC+isotype control group (all P<0.05), whereas the left ventricular ejection fraction (LVEF) was decreased (P<0.05). LVESD and LVEDD were significantly decreased, and LVEF was increased in CVMC+miR-21 inhibitor group compared with those in CVMC group and CVMC+isotype control group (all P<0.05). (2) Myocardial pathological changes: The expressions of GFP in CVMC+miR-21 inhibitor group and CVMC+isotype control group were visible in heart tissues frozen sections. The hearts in CVMC group and CVMC+isotype control group were enlarged and stiff, inflammatory cells were visible and significantly increased myocardial fibrosis was evidenced in mice of these two groups. Higher PS and CVF were evidenced in CVMC group (PS: 1.14±0.69 vs. 0, CVF: (17.86±2.61)% vs. (5.70±1.42)%, all P<0.05) and CVMC+isotype control group(PS: 1.00±0.63 vs. 0, CVF: (16.78±2.58)% vs. (5.70±1.42)%, all P<0.05) compared to PBS group. Compared with CVMC group and CVMC+isotype control group, degree of cardiac fibrosis was reduced in mice of CVMC+miR-21 inhibitor group (CVF: (11.01±2.55)% vs. (17.86±2.61)%, (11.01±2.55)% vs. (16.78±2.58)%, all P<0.05), whereas PS were similar between them (PS: 0.89±0.60 vs. 1.14±0.69, 0.89±0.60 vs. 1.00±0.63, all P>0.05). (3) Cardiac expressions of miR-21, COL1-A1 and COL3-A1 mRNA: The cardiac expressions of miR-21, COL1-A1 mRNA, COL3-A1mRNA in CVMC group and CVMC+isotype control group were markedly higher than those in PBS group (all P<0.05), which were significantly downregulated in CVMC+miR-21 inhibitor group (all P<0.05 vs. CVMC group and CVMC+isotype control group). (4) The cardiac expressions of TGF-β1 and Smad7 protein: The cardiac expressions of TGF-β1 protein in CVMC group and CVMC+isotype control group were markedly higher, whereas the cardiac Smad7 protein expressions were significantly lower (all P<0.05) than those in PBS group (all P<0.05), these changes could be reversed in CVMC+miR-21 inhibitor group (P<0.05 vs. CVMC group and CVMC+isotype control group). Conclusions: Our results suggest that miR-21 contributes to the myocardial fibrosis in CVMC mice through modulating TGF-β1/Smad7 signaling pathway.

Detection of gastro-oesophageal reflux in the neonatal unit.

To determine whether a pH probe or multichannel intraluminal impedance (MII) more frequently detected gastro-oesophageal reflux and test the hypothesis that acid reflux was associated with lower baseline impedance. A prospective study of infants in whom reflux was suspected and evaluated using combined pH and multichannel impedance. Studies were considered abnormal if the acid index was >10% or there were >79MII reflux events in 24hours. The acid index was the percentage of total study time with a pH<four and the acid clearance time (ACT) the time from the pH falling below four to rising above four. Forty-two infants [median gestational age 31 (range 23-42) weeks] were assessed. Only nine infants (21%) had abnormal studies, seven detected by pH monitoring, one by MII monitoring and one by both techniques (p=0.04). After correcting for gestational age and post-natal age, baseline impedance remained negatively correlated with the acid index (r=-0.34, p=0.038) and the maximum ACT (r=-0.44, p=0.006). Clinical suspicion of reflux was frequently incorrect, and reflux was more frequently detected by a pH probe. The inverse relationship of acid reflux to baseline impedance suggests that mucosal disruption may result from acid reflux in this population.