139 research outputs found
Repeated mild injury causes cumulative damage to hippocampal cells
An interesting hypothesis in the study of neurotrauma is that repeated
traumatic brain injury may result in cumulative damage to cells of the
brain. However, post-injury sequelae are difficult to address at the
cellular level in vivo. Therefore, it is necessary to complement these
studies with experiments conducted in vitro. In this report, the effects
of single and repeated traumatic injury in vitro were investigated in
cultured mouse hippocampal cells using a well characterized model of
stretch-induced injury. Cell damage was assessed by the level of propidium
iodide (PrI) uptake and retention of fluorescein diacetate (FDA).
Uninjured control wells displayed minimal PrI uptake and high levels of
FDA retention. Mild, moderate and severe levels of stretch caused
increasing amounts of PrI uptake, respectively, when measured at 15 min
and 24 h post-injury, indicating increased cellular damage with increasing
amounts of stretch. For repeated injury studies, cultures received a
second injury 1 h after the initial insult. Repeated mild injury caused a
slight increase in PrI uptake compared with single injury at 15 min and 24
h post-injury, which was evident primarily in glial cells. However, the
neurites of neurones in cultures that received repeated insults showed
signs of damage that were not evident after a single mild injury. The
release of neurone-specific enolase (NSE) and S-100beta protein, two
common clinical markers of CNS damage, was also measured following the
repeated injuries paradigm. When measured at 6 h post-injury, both NSE and
S-100beta were found to be elevated after repeated mild injuries when
compared with the single injury group. These results suggest that cells of
the hippocampus may be susceptible to cumulative damage following repeated
mild traumatic insults. Both glial cells and neurones appear to exhibit
increased signs of damage after repetitive injury. To our knowledge, this
study represents the first report on the effects of repeated mechanical
insults on specific cells of the brain using an in vitro model system. The
biochemical pathways of cellular degradation following repeated mild
injuries may differ considerably from those that are activated by a single
mild insult. Therefore, we hope to use this model in order to investigate
secondary pathways of cellular damage after repeated mild traumatic
injury, and as a rapid and economical means of screening possibilities for
treatment strategies, including pharmaceutical intervention
Impact of sexual trajectories of men who have sex with men on the reduction in HIV transmission by pre-exposure prophylaxis
Acknowledgments This project was funded by the Netherlands Organisation for Health Research and Development ZonMw grant 522002004.Peer reviewedPublisher PD
The Rhythm of Risk : Sexual Behaviour, PrEP Use and HIV Risk Perception Between 1999 and 2018 Among Men Who Have Sex with Men in Amsterdam, The Netherlands
Funding Information: This project was funded by the Netherlands Organisation for Health Research and Development ZonMw Grant 522004009. The Amsterdam Cohort Studies on HIV infection, a collaboration between the Public Health Service of Amsterdam, the Amsterdam University Medical Centers location AMC, Sanquin Blood Supply Foundation, MC Jan van Goyen and DC Clinics Lairesse, are part of the Netherlands HIV Monitoring Foundation and financially supported by the Netherlands National Institute for Public Health and the Environment. The ACS gratefully acknowledge all the study participants for their co-operation and participation and research nurses for collecting the data (Samantha de Graaf and Leeann Storey). The authors also thank Dominique Loomans, Ertan Ersan, Maartje Dijkstra, Liza Coyer, and Ward van Bilsen for data management.Peer reviewedPublisher PD
Time for change : Transitions between HIV risk levels and determinants of behavior change in men who have sex with men
Funding Information: This project was funded by the Netherlands Organisation for Health Research and Development ZonMw grant 522004009. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD
Generación automática de reglas de categorización de texto en un método híbrido basado en aprendizaje
En este artículo se evalúan diferentes técnicas para la generación automática de reglas que se emplean en un método híbrido de categorización automática de texto. Este método combina un algoritmo de aprendizaje computacional con diferentes sistemas basados en reglas en cascada empleados para el filtrado y reordenación de los resultados proporcionados por dicho modelo base. Aquí se describe una implementación realizada mediante el algoritmo kNN y un lenguaje básico de reglas basado en listas de términos que aparecen en el texto a clasificar. Para la evaluación se utiliza el corpus de noticias Reuters-21578. Los resultados demuestran que los métodos de generación de reglas propuestos producen resultados muy próximos a los obtenidos con la aplicación de reglas generadas manualmente y que el sistema híbrido propuesto obtiene una precisión y cobertura comparables a la de los mejores métodos del estado del arte
Screening for Hepatitis C Virus Reinfection Using a Behaviour-Based Risk Score among Men Who Have Sex with Men with HIV:Results from a Case–Control Diagnostic Validation Study
We assessed the predictive capacity of the HCV-MOSAIC risk score, originally developed for primary early HCV infection, as a screening tool for HCV reinfection in 103 men who have sex with men (MSM) with HIV using data from the MOSAIC cohort, including MSM with HIV/HCV-coinfection who became reinfected (cases, n = 27) or not (controls, n = 76) during follow-up. The overall predictive capacity of the score was assessed using the area under the receiver operating characteristic (AUROC) curve. The effects of covariates on the receiver operating characteristic (ROC) curve were assessed using parametric ROC regression. The score cut-off validated for primary early infection (≥2.0) was used, from which the sensitivity and specificity were calculated. The AUROC was 0.74 (95% confidence interval (CI) = 0.63–0.84). Group sex significantly increased the predictive capacity. Using the validated cut-off, sensitivity was 70.4% (95%CI = 49.8–86.2%) and specificity was 59.2% (95%CI: 47.3–70.4%). External validation from a cohort of 25 cases and 111 controls, all MSM with HIV, resulted in a sensitivity of 44.0% (95%CI = 24.4–65.1) and specificity of 71.2% (95%CI = 61.8–79.4). The HCV-MOSAIC risk score may be useful for identifying individuals at risk of HCV reinfection. In sexual health or HIV-care settings, this score could help guide HCV-RNA testing in MSM with a prior HCV infection.</p
Growth of transcendental entire solution of some q-difference equation
Technical Reports of Mathematical Sciences, Chiba University, Vol.18(2002
The epidemiological impact of digital and manual contact tracing on the SARS-CoV-2 epidemic in the Netherlands: Empirical evidence
The Dutch government introduced the CoronaMelder smartphone application for digital contact tracing (DCT) to complement manual contact tracing (MCT) by Public Health Services (PHS) during the 2020-2022 SARS-CoV-2 epidemic. Modelling studies showed great potential but empirical evidence of DCT and MCT impact is scarce. We determined reasons for testing, and mean exposure-testing intervals by reason for testing, using routine data from PHS Amsterdam (1 December 2020 to 31 May 2021) and data from two SARS-CoV-2 rapid diagnostic test accuracy studies at other PHS sites in the Netherlands (14 December 2020 to 18 June 2021). Throughout the study periods, notification of DCT-identified contacts was via PHS contact-tracers, and self-testing was not yet widely available. The most commonly reported reason for testing was having symptoms. In asymptomatic individuals, it was having been warned by an index case. Only around 2% and 2-5% of all tests took place after DCT or MCT notification, respectively. About 20-36% of those who had received a DCT or MCT notification had symptoms at the time of test request. Test positivity after a DCT notification was significantly lower, and exposure-test intervals after a DCT or MCT notification were longer, than for the above-mentioned other reasons for testing. Our data suggest that the impact of DCT and MCT on the SARS-CoV-2 epidemic in the Netherlands was limited. However, DCT impact might be enlarged if app use coverage is improved, contact-tracers are eliminated from the digital notification process to minimise delays, and DCT is combined with self-testing
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