RÉSUMÉ
BACKGROUND: Standard neuropathologic analysis of Alzheimer's brain relies on traditional fluorescence microscopy, which suffers from limited spatial resolution due to light diffraction. As a result, it fails to reveal intricate details of amyloid plaques. While electron microscopy (EM) offers higher resolution, its extensive sample preparation, involving fixation, dehydration, embedding, and sectioning, can introduce artifacts and distortions in the complex brain tissue. Moreover, EM lacks molecular specificity and has limited field of view and imaging depth. RESULTS: In our study, we employed super-resolution Stimulated Emission Depletion (STED) microscopy in conjunction with the anti-human APP recombinant antibody 1C3 fluorescently labelled with DyLightTM633 (1C3-DyLight633). This combination allowed us to visualize amyloidogenic aggregates in vitro and in brain sections from a 17-month-old 3×Tg-AD mouse with sub-diffraction limited spatial resolution. Remarkably, we achieved a spatial resolution of 29 nm in vitro and 62 nm in brain tissue sections, surpassing the capabilities of conventional confocal microscopy by 5-10 times. Consequently, we could discern individual fibrils within plaques, an achievement previously only possible with EM. CONCLUSIONS: The utilization of STED microscopy represents a groundbreaking advancement in the field, enabling researchers to delve into the characterization of local mechanisms that underlie Amyloid (Aß) deposition into plaques and their subsequent clearance. This unprecedented level of detail is especially crucial for comprehending the etiology of Alzheimer's disease and developing the next generation of anti-amyloid treatments. By facilitating the evaluation of drug candidates and non-pharmacological interventions aiming to reduce amyloid burden, STED microscopy emerges as an indispensable tool for driving scientific progress in Alzheimer's research.
RÉSUMÉ
The risk of suffering pain increases significantly throughout life, reaching the highest levels in its latest years. Prevalence of pain in nursing homes is estimated to range from 40 to 80% of residents, most of them old adults affected with dementia. It is already known that pain is under-diagnosed and under-treated in patients with severe cognitive impairment and poor/absent verbal communication, resulting in a serious impact on their quality of life, psychosocial, and physical functioning. Under-treated pain is commonly the cause of behavioral symptoms, which can lead to misuse of antipsychotic treatments. Here, we present two Regional and National Surveys in Spain (2015-2017) on the current practices, use of observational tools for pain assessment, guidelines, and policies. Results, discussed as compared to the survey across central/north Europe, confirm the professional concerns on pain in severe dementia, due to poor standardization and lack of guidelines/recommendations. In Spain, observational tools are scarcely used because of their difficulty and low reliability in severe dementia, since the poor/absent verbal communication and comprehension are considered limiting factors. Behavioral observation tools should be used while attending the patients, in a situation including rest and movement, should be short (3-5 min) and scored using a numeric scale. Among the pain items to score, "Facial expression" and "Verbalization" were considered essential and very useful, respectively. This was in contrast to "Body movements" and "Vocalizations," respectively, according to the survey in central/north Europe. Scarce time availability for pain assessment and monitoring, together with low feasible and time-consuming tools, can make pain assessment a challenge. The presence of confounding factors, the low awareness and poor knowledge/education of specific tools for this population are worrisome. These complaints draw future directions to improve pain assessment. More time available, awareness, and involvement of the teams would also benefit pain assessment and management in cognitive impairment. The experiences and opinions recorded in these surveys in Spain and other E.U. countries were considered sources of knowledge for designing the "PAIC-15 scale," a new internationally agreed-on meta-tool for Pain Assessment in Impaired Cognition and the "Observational pain assessment" in older persons with dementia.
