Comparing sewage-based epidemiology with survey research on drug use in the general population

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Removal of biofilms by impinging water droplets

The process of impinging water droplets on Streptococcus mutans biofilms was studied experimentally and numerically. Droplets were experimentally produced by natural breakup of a cylindrical liquid jet. Droplet diameter and velocity were varied between 20 and 200¿µm and between 20 and 100 m/s, respectively. The resulting erosion process of the biofilm was determined experimentally with high-speed recording techniques and a quantitative relationship between the removal rate, droplet size, and velocity was determined. The shear stress and the pressure on the surface during droplet impact were determined by numerical simulations, and a qualitative agreement between the experiment and the simulation was obtained. Furthermore, it was shown that the stresses on the surface are strongly reduced when a water film is present

The Role of Astrocytes in Synapse Loss in Alzheimer's Disease: A Systematic Review

Alzheimer's disease (AD) is the most common cause of dementia, affecting 35 million people worldwide. One pathological feature of progressing AD is the loss of synapses. This is the strongest correlate of cognitive decline. Astrocytes, as an essential part of the tripartite synapse, play a role in synapse formation, maintenance, and elimination. During AD, astrocytes get a reactive phenotype with an altered gene expression profile and changed function compared to healthy astrocytes. This process likely affects their interaction with synapses. This systematic review aims to provide an overview of the scientific literature including information on how astrocytes affect synapse formation and elimination in the brain of AD patients and in animal models of the disease. We review molecular and cellular changes in AD astrocytes and conclude that these predominantly result in lower synapse numbers, indicative of decreased synapse support or even synaptotoxicity, or increased elimination, resulting in synapse loss, and consequential cognitive decline, as associated with AD. Preventing AD induced changes in astrocytes might therefore be a potential therapeutic target for dementia. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=148278, identifier [CRD148278]

Both male and female APPswe/PSEN1dE9 mice are impaired in spatial memory and cognitive flexibility at 9 months of age

Alzheimer's disease (AD) is the most common cause of dementia. Despite many years of research, very limited treatment options are available. Here we aim to establish a well-defined learning and memory performance test for an AD mouse model, which can be used in future studies to evaluate the effect of novel drugs, treatments, and interventions. We exposed 9-month-old APPswe/PSEN1dE9 mice to a battery of memory tests to determine which test is best suited to study memory deficits in this specific AD mouse model. Since in more recent years it has become clear that there are sex-dependent differences in AD pathology, we also assessed differences in performance between male and female mice. From our test battery, we conclude that the Barnes maze task, which spans multiple days, is better suited to study subtle learning and memory deficits in 9-month-old APPswe/PS1dE9 mice, than the 2 trial T-maze and Fear conditioning task. This test revealed deficits in both spatial memory and cognitive flexibility in the APPswe/PS1dE9 mice compared to wildtype littermates. Furthermore, we conclude that there are no sex dependent memory deficit differences in this AD mouse model at this age