•123 fatigue tests performed at four loading frequencies from 1/16Hz to 4Hz.•Loading frequency effect on fatigue behavior of plain concrete is pronounced.•For fiber-reinforced concrete, frequency ...effect on fatigue life is minor.•Fibers can improve fatigue life significantly under low loading frequencies.
This paper presents the recent experimental results aimed at disclosing the loading frequency effect on the fatigue behavior of a plain concrete and two types of fiber-reinforced concrete, using polypropylene and steel fibers. Compressive fatigue tests were conducted on 123 cubic specimens (100mm in edge length). Four different loading frequencies, 4Hz, 1Hz, 1/4Hz and 1/16Hz, were employed. Themaximum stress applied on the specimen was 85% of its compressive strength and the stress ratio was kept constant as 0.3. The results show that the loading frequency effect on the fatigue behavior of the plain concrete is pronounced. The fatigue life (the number of cycles to failure) at lower frequencies is less than that at higher frequencies. However, the fibers do improve the fatigue behavior significantly under low loading frequencies. Such trend can be attributed to the effectiveness of the fibers in bridging cracks, and thus inhibiting the crack extension under cyclic loads.
El presente artículo estudia el entorno social de la infanta Juana de Aragón a través del libro de cuentas elaborado por su tesorero, Luis de Santángel, entre 1469 y 1472. Mediante la consulta de ...esta fuente particular y de documentación auxiliar, se pretende poner de relieve la relevancia histórica de esta figura, que ha pasado desapercibida por la historiografía reciente, y analizar la estructura y composición de la Casa de la Infanta en el momento de su creación, así como la naturaleza de las relaciones trazadas en su interior. También se aborda la dimensión de la Casa de la Infanta como espacio femenino de carácter oficial, y se analizan las posibilidades de autonomía y acción política que esta institución confería a su titular, así como las oportunidades de empleabilidad y promoción social ofrecidas a las mujeres que se integraban en su seno.
Objective: To describe corneal confocal microscopy findings in patients with long COVID-19 with persistent symptoms over 20 months after SARS-CoV-2 infection. Design: A descriptive cross-sectional ...study that included a total of 88 patients; 60 patients with Long COVID-19 and 28 controls. Long COVID-19 diagnosis was established according to the World Health Organization criteria. Corneal confocal microscopy using a Heidelberg Retina Tomograph II (Heidelberg Engineering, Heidelberg, Germany) was performed to evaluate sub-basal nerve plexus morphology (corneal nerve fiber density, nerve fiber length, nerve branch density, nerve fiber total branch density, nerve fiber area, and nerve fiber width). Dendritic cell density and area, along with microneuromas and other morphological changes of the nerve fibers were recorded. Results: Long COVID-19 patients presented with reduced corneal nerve density and branch density as well as shorter corneal nerves compared to the control group. Additionally, Long COVID-19 patients showed an increased density of dendritic cells also with a greater area than that found in the control group of patients without systemic diseases. Microneuromas were detected in 15% of Long COVID-19 patients. Conclusions: Long COVID-19 patients exhibited altered corneal nerve parameters and increased DC density over 20 months after acute SARS-CoV-2 infection. These findings are consistent with a neuroinflammatory condition hypothesized to be present in patients with Long COVID-19, highlighting the potential role of corneal confocal microscopy as a promising noninvasive technique for the study of patients with Long COVID-19.
Abstract
Background/Objectives
The paediatric reference range of fecal calprotectin (FC) has not been decisively established and previous studies show a wide within-age variability, suggesting that ...other factors like anthropometric data or type of feeding can influence FC. Our aims were to establish the normal levels of FC in healthy children grouped by age and analyze whether sex, gestational age, birth weight, type of delivery, type of feeding, or anthropometric data influence FC values.
Methods
This multicentre, cross-sectional, and observational study enrolled healthy donors under 18 years of age who attended their Primary Health Care Centre for their routine Healthy Child Program visits. The exclusion criteria were: (i) immunodeficiency, (ii) autoimmune or (iii) gastrointestinal disease; (iv) medication usage; (v) gastrointestinal symptoms; or (vi) positive finding in the microbiological study.
Results
We enrolled 395 subjects, mean age was 4.2 years (range 3 days to 16.9 years), and 204 were male. The median FC was 77.0 mcg/g (interquartile range 246). A negative correlation between age and FC was observed (Spearman’s rho = −0.603, P<0.01), and none of the other factors analyzed were found to influence FC levels.
Conclusions
Normal FC values in healthy children (particularly in infants) are higher than those considered to be altered in adults and show a negative correlation with age. It is necessary to reconsider the upper limits of FC levels for paediatric patients according to age, with further studies required to determine other factors that influence FC during infancy.
Update on Corneal Confocal Microscopy Imaging Cañadas, Pilar; Alberquilla García-Velasco, Marta; Hernández Verdejo, José Luis ...
Diagnostics (Basel),
12/2022, Volume:
13, Issue:
1
Journal Article
Peer reviewed
Open access
In vivo corneal confocal microscopy (IVCM) is a non-invasive ophthalmic imaging technique that provides images of the cornea at the cellular level. Despite the uses in ocular surface pathologies, in ...the last decades IVCM has been used to provide more knowledge in refractive surgery wound healing, in neuropathies diagnosis, etc. The observation of the corneal cells, both normal and inflammatory, and the possibility of quantification of the corneal nerve density with manual or automated tools, makes IVCM have a significant potential to improve the diagnosis and prognosis in several systemic and corneal conditions.
The purpose of the study was to determine the role of fecal calprotectin and lactoferrin in the prediction of inflammatory bowel disease relapses, both in patients with ulcerative colitis (UC) and ...Crohn's disease (CD), in a large, long-term, follow-up study.
The prospective multicenter study included CD and UC patients who had been in clinical remission for 6 months. At baseline, patients provided a single stool sample for calprotectin and lactoferrin determination. Follow-up was 12 months in patients showing no relapse and until activity flare in relapsing patients.
In all, 163 patients (89 CD, 74 UC) were included. Twenty-six patients (16%) relapsed during follow-up. Calprotectin concentrations in patients who suffered a relapse were higher than in nonrelapsing patients (239 +/- 150 versus 136 +/- 158 microg/g; P < 0.001). Relapse risk was higher in patients having high (>150 microg/g) calprotectin concentrations (30% versus 7.8%; P < 0.001) or positive lactoferrin (25% versus 10%; P < 0.05). Fecal calprotectin (>150 microg/g) sensitivity and specificity to predict relapse were 69% and 69%, respectively. Corresponding values for lactoferrin were 62% and 65%, respectively. The area under the receiver operating characteristic curve to predict relapse using calprotectin determination was 0.73 (0.69 for UC and 0.77 for CD). Better results were obtained when only colonic CD disease or only relapses during the first 3 months were considered (100% sensitivity). High fecal calprotectin levels or lactoferrin positivity was associated with clinical relapse in Kaplan-Meier survival analysis, and both fecal tests were associated with relapse in the multivariate analysis.
Fecal calprotectin and lactoferrin determination may be useful in predicting impending clinical relapse-especially during the following 3 months-in both CD and UC patients.
The coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread rapidly worldwide, seriously endangering human health. Although SARS‐CoV‐2 ...had a lower impact on paediatric population, children with COVID-19 have been reported as suffering from gastrointestinal (GI) symptoms at a higher rate than adults. The aim of this work was to evaluate faeces as a source of potential biomarkers of severity in the paediatric population, with an emphasis on intestinal microbiota and faecal immune mediators, trying to identify possible dysbiosis and immune intestinal dysfunction associated with the risk of hospitalization. This study involved 19 patients with COVID-19 under 24 months of age hospitalized during the pandemic at 6 different hospitals in Spain, and it included a comparable age-matched healthy control group (
n
= 18). Patients and controls were stratified according to their age in two groups: newborns or young infants (from 0 to 3 months old) and toddlers (infants from 6 to 24 months old). To characterize microbial intestinal communities, sequencing with Illumina technology of total 16S rDNA amplicons and internal transcribed spacer (ITS) amplicons of bifidobacteria were used. Faecal calprotectin (FC) and a range of human cytokines, chemokines, and growth factors were measured in faecal samples using ELISA and a multiplex system. Significant reduction in the abundance of sequences belonging to the phylum Actinobacteria was found in those infants with COVID-19, as well as in the
Bifidobacteriaceae
family. A different pattern of bifidobacteria was observed in patients, mainly represented by lower percentages of
Bifidobacterium breve
, as compared with controls. In the group of hospitalized young infants, FC was almost absent compared to age-matched healthy controls. A lower prevalence in faecal excretion of immune factors in these infected patients was also observed.
Conclusion
: Hospitalized infants with COVID-19 were depleted in some gut bacteria, such as bifidobacteria, in particular
Bifidobacterium breve
, which is crucial for the proper establishment of a functional intestinal microbiota, and important for the development of a competent immune system. Our results point to a possible immature immune system at intestine level in young infants infected by SARS-CoV2 requiring hospitalization.
What is Known:
• Although SARS‐CoV‐2 had a lower impact on paediatric population, children with COVID-19 have been reported as suffering from gastrointestinal symptoms at a higher rate than adults.
• Changes in microbial composition have been described in COVID-19 adult patients, although studies in children are limited.
What is New:
• The first evidence that hospitalized infants with COVID-19 during the pandemic had a depletion in bifidobacteria, particularly in Bifidobacterium breve, beneficial gut bacteria in infancy that are crucial for the proper establishment of a competent immune system.
• In young infants (under 3 months of age) hospitalized with SARS-CoV2 infection, the aberrant bifidobacterial profile appears to overlap with a poor intestinal immune development as seen by calprotectin and the trend of immunological factors excreted in faeces.
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