A Relationship between the Structures and Neurotoxic Effects of Aß Oligomers Stabilized by Different Metal Ions.

Oligomeric assemblies of the amyloid ß peptide (Aß) have been investigated for over two decades as possible neurotoxic agents in Alzheimer's disease. However, due to their heterogeneous and transient nature, it is not yet fully established which of the structural features of these oligomers may generate cellular damage. Here, we study distinct oligomer species formed by Aß40 (the 40-residue form of Aß) in the presence of four different metal ions (Al3+, Cu2+, Fe2+, and Zn2+) and show that they differ in their structure and toxicity in human neuroblastoma cells. We then describe a correlation between the size of the oligomers and their neurotoxic activity, which provides a type of structure-toxicity relationship for these Aß40 oligomer species. These results provide insight into the possible role of metal ions in Alzheimer's disease by the stabilization of Aß oligomers.

Hypochlorite-induced oxidation promotes aggregation and reduces toxicity of amyloid beta 1-42.

Exacerbated hypochlorite (OCl-) production is linked to neurodegenerative processes, but there is growing evidence that lower levels of hypochlorite activity are important to protein homeostasis. In this study we characterise the effects of hypochlorite on the aggregation and toxicity of amyloid beta peptide 1-42 (Aß1-42), a major component of amyloid plaques that form in the brain in Alzheimer's disease. Our results demonstrate that treatment with hypochlorite promotes the formation of Aß1-42 assemblies ≥100 kDa that have reduced surface exposed hydrophobicity compared to the untreated peptide. This effect is the result of the oxidation of Aß1-42 at a single site as determined by mass spectrometry analysis. Although treatment with hypochlorite promotes the aggregation of Aß1-42, the solubility of the peptide is enhanced and amyloid fibril formation is inhibited as assessed by filter trap assay, thioflavin T assay and transmission electron microscopy. The results of in vitro assays using SH-SY5Y neuroblastoma cells show that pre-treatment of Aß1-42 with a sub-stoichiometric amount of hypochlorite substantially reduces its toxicity. The results of flow cytometry analysis and internalisation assays indicate that hypochlorite-induced modification of Aß1-42 reduces its toxicity via at least two-distinct mechanism, reducing the total binding of Aß1-42 to the surface of cells and facilitating the cell surface clearance of Aß1-42 to lysosomes. Our data is consistent with a model in which tightly regulated production of hypochlorite in the brain is protective against Aß-induced toxicity.

The worldwide costs of dementia in 2019.

INTRODUCTION: Dementia is a leading cause of death and disability globally. Estimating total societal costs demonstrates the wide impact of dementia and its main direct and indirect economic components. METHODS: We constructed a global cost model for dementia, presenting costs as cumulated global and regional costs. RESULTS: In 2019, the annual global societal costs of dementia were estimated at US $1313.4 billion for 55.2 million people with dementia, corresponding to US $23,796 per person with dementia. Of the total, US $213.2 billion (16%) were direct medical costs, US $448.7 billion (34%) direct social sector costs (including long-term care), and US $651.4 billion (50%) costs of informal care. DISCUSSION: The huge costs of dementia worldwide place enormous strains on care systems and families alike. Although most people with dementia live in low- and middle-income countries, highest total and per-person costs are seen in high-income countries. HIGHLIGHTS: Global economic costs of dementia were estimated to reach US $1313.4 in 2019. Sixty-one percent of people with dementia live in low-and middle-income countries, whereas 74% of the costs occur in high-income countries. The impact of informal care accounts for about 50% of the global costs. The development of a long-term care infrastructure is a great challenge for low-and middle-income countries. There is a great need for more cost studies, particularly in low- and middle-income countries. Discussions of a framework for global cost comparisons are needed.

Structure-Based Discovery of Small-Molecule Inhibitors of the Autocatalytic Proliferation of α-Synuclein Aggregates.

The presence of amyloid fibrils of α-synuclein is closely associated with Parkinson's disease and related synucleinopathies. It is still very challenging, however, to systematically discover small molecules that prevent the formation of these aberrant aggregates. Here, we describe a structure-based approach to identify small molecules that specifically inhibit the surface-catalyzed secondary nucleation step in the aggregation of α-synuclein by binding to the surface of the amyloid fibrils. The resulting small molecules are screened using a range of kinetic and thermodynamic assays for their ability to bind α-synuclein fibrils and prevent the further generation of α-synuclein oligomers. This study demonstrates that the combination of structure-based and kinetic-based drug discovery methods can lead to the identification of small molecules that selectively inhibit the autocatalytic proliferation of α-synuclein aggregates.

Six Action Steps to Address Global Disparities in Parkinson Disease: A World Health Organization Priority.

Importance: The Global Burden of Disease study conducted between 1990 and 2016, based on a global study of 195 countries and territories, identified Parkinson disease (PD) as the fastest growing neurological disorder when measured using death and disability. Most people affected by PD live in low- and middle-income countries (LMICs) and experience large inequalities in access to neurological care and essential medicines. This Special Communication describes 6 actions steps that are urgently needed to address global disparities in PD. Observations: The adoption by the 73rd World Health Assembly (WHA) of resolution 73.10 to develop an intersectoral global action plan on epilepsy and other neurological disorders in consultation with member states was the stimulus to coordinate efforts and leverage momentum to advance the agenda of neurological conditions, such as PD. In April 2021, the Brain Health Unit at the World Health Organization convened a multidisciplinary, sex-balanced, international consultation workshop, which identified 6 workable avenues for action within the domains of disease burden; advocacy and awareness; prevention and risk reduction; diagnosis, treatment, and care; caregiver support; and research. Conclusions and Relevance: The dramatic increase of PD cases in many world regions and the potential costs of PD-associated treatment will need to be addressed to prevent possible health service strain. Across the board, governments, multilateral agencies, donors, public health organizations, and health care professionals constitute potential stakeholders who are urged to make this a priority.

Proliferation of Tau 304-380 Fragment Aggregates through Autocatalytic Secondary Nucleation.

The self-assembly of the protein tau into neurofibrillary tangles is one of the hallmarks of Alzheimer's disease and related tauopathies. Still, the molecular mechanism of tau aggregation is largely unknown. This problem may be addressed by systematically obtaining reproducible in vitro kinetics measurements under quiescent conditions in the absence of triggering substances. Here, we implement this strategy by developing protocols for obtaining an ultrapure tau fragment (residues 304-380 of tau441) and for performing spontaneous aggregation assays with reproducible kinetics under quiescent conditions. We are thus able to identify the mechanism of fibril formation of the tau 304-380 fragment at physiological pH using fluorescence spectroscopy and mass spectrometry. We find that primary nucleation is slow, and that secondary processes dominate the aggregation process once the initial aggregates are formed. Moreover, our results further show that secondary nucleation of monomers on fibril surfaces dominates over fragmentation of fibrils. Using separate isotopes in monomers and fibrils, through mass spectroscopy measurements, we verify the isotope composition of the intermediate oligomeric species, which reveals that these small aggregates are generated from monomer through secondary nucleation. Our results provide a framework for understanding the processes leading to tau aggregation in disease and for selecting possible tau forms as targets in the development of therapeutic interventions in Alzheimer's disease.

A dopamine metabolite stabilizes neurotoxic amyloid-ß oligomers.

Aberrant soluble oligomers formed by the amyloid-ß peptide (Aß) are major pathogenic agents in the onset and progression of Alzheimer's disease. A variety of biomolecules can influence the formation of these oligomers in the brain, although their mechanisms of action are still largely unknown. Here, we studied the effects on Aß aggregation of DOPAL, a reactive catecholaldehyde intermediate of dopamine metabolism. We found that DOPAL is able to stabilize Aß oligomeric species, including dimers and trimers, that exert toxic effects on human neuroblastoma cells, in particular increasing cytosolic calcium levels and promoting the generation of reactive oxygen species. These results reveal an interplay between Aß aggregation and key biochemical processes regulating cellular homeostasis in the brain.

Rationally Designed Antibodies as Research Tools to Study the Structure-Toxicity Relationship of Amyloid-ß Oligomers.

Alzheimer's disease is associated with the aggregation of the amyloid-ß peptide (Aß), resulting in the deposition of amyloid plaques in brain tissue. Recent scrutiny of the mechanisms by which Aß aggregates induce neuronal dysfunction has highlighted the importance of the Aß oligomers of this protein fragment. Because of the transient and heterogeneous nature of these oligomers, however, it has been challenging to investigate the detailed mechanisms by which these species exert cytotoxicity. To address this problem, we demonstrate here the use of rationally designed single-domain antibodies (DesAbs) to characterize the structure-toxicity relationship of Aß oligomers. For this purpose, we use Zn2+-stabilized oligomers of the 40-residue form of Aß (Aß40) as models of brain Aß oligomers and two single-domain antibodies (DesAb18-24 and DesAb34-40), designed to bind to epitopes at residues 18-24 and 34-40 of Aß40, respectively. We found that the DesAbs induce a change in structure of the Zn2+-stabilized Aß40 oligomers, generating a simultaneous increase in their size and solvent-exposed hydrophobicity. We then observed that these increments in both the size and hydrophobicity of the oligomers neutralize each other in terms of their effects on cytotoxicity, as predicted by a recently proposed general structure-toxicity relationship, and observed experimentally. These results illustrate the use of the DesAbs as research tools to investigate the biophysical and cytotoxicity properties of Aß oligomers.

Effects of Doxorubicin Delivery Systems and Mild Hyperthermia on Tissue Penetration in 3D Cell Culture Models of Ovarian Cancer Residual Disease.

Current chemotherapy strategies for second-line treatment of relapsed ovarian cancer are unable to effectively treat residual disease post-cytoreduction. The findings presented herein suggest that tissue penetration of drug is not only an issue for large, unresectable tumors, but also for invisible, microscopic lesions. The present study sought to investigate the potential of a block copolymer micelle (BCM) formulation, which may reduce toxicities of doxorubicin (DOX) in a similar way to pegylated liposomal doxorubicin (PLD, Doxil/Caelyx), while enhancing penetration into tumor tissue and improving intratumoral availability of drug. To achieve this goal, 50 nm-sized BCMs capable of high DOX encapsulation (BCM-DOX) at drug levels ranging from 2 to 7.6 mg/mL were formulated using an ultrafiltration technique. BCM-DOX was evaluated in 2D and 3D cell culture of the human ovarian cancer cell lines HEYA8, OV-90, and SKOV3. Additionally, the current study examines the impact of mild hyperthermia (MHT) on the cytotoxicity of DOX. The BCM-DOX formulation fulfilled the goal of controlling drug release while providing up to 9-fold greater cell monolayer cytotoxicity in comparison to PLD. In 3D cell culture, using multicellular tumor spheroids (MCTS) as a model of residual disease postsurgery, BCM-DOX achieved the benefits of an extended release formulation of DOX and resulted in improvements in drug accumulation over PLD, while yielding drug levels approaching that achievable by exposure to DOX alone. In comparison to PLD, this translated into superior MCTS growth inhibition in the short term and comparable inhibition in the long term. Overall, although MHT appeared to enhance drug accumulation in HEYA8 MCTS treated with BCM-DOX and DOX alone in the short term, improved growth inhibition of MCTS by MHT was not observed after 48 h of drug treatment. Evaluation of BCM-DOX in comparison to PLD as well as the effects of MHT is warranted in vivo.

Hematological change parameters in patients with pressure ulcer at long-term care hospital.

OBJECTIVE: To assess factors associated with the development of pressure ulcers, and to compare the effectiveness of pharmacological treatments. METHODS: The factors associated with the development of pressure ulcers were compared in lesion-carrying patients (n=14) and non-carriers (n=16). Lesion-carrying patients were treated with 1% silver sulfadiazine or 0.6IU/g collagenase and were observed for 8 weeks. The data collected was analyzed with p<0.05 being statistically relevant. RESULTS: The prevalence of pressure ulcers was about 6%. The comparison of carrier and non-carrier groups of pressure ulcers revealed no statistically significant difference in its occurrence with respect to age, sex, skin color, mobility, or the use of diapers. However, levels of hemoglobin, hematocrit, and red blood cells were found to be statistically different between groups, being lower in lesion-carrying patients. There was no significant difference found in lesion area between patients treated with collagenase or silver sulfadiazine, although both groups showed an overall reduction in lesion area through the treatment course. CONCLUSION: Hematologic parameters showed a statistically significant difference between the two groups. Regarding the treatment of ulcers, there was no difference in the area of the lesion found between the groups treated with collagenase and silver sulfadiazine.

Hematological change parameters in patients with pressure ulcer at long-term care hospital / Alterações dos parâmetros hematológicos em pacientes portadores de úlcera por pressão em um hospital de longa permanência

Objective To assess factors associated with the development of pressure ulcers, and to compare the effectiveness of pharmacological treatments. Methods The factors associated with the development of pressure ulcers were compared in lesion-carrying patients (n=14) and non-carriers (n=16). Lesion-carrying patients were treated with 1% silver sulfadiazine or 0.6IU/g collagenase and were observed for 8 weeks. The data collected was analyzed with p<0.05 being statistically relevant. Results The prevalence of pressure ulcers was about 6%. The comparison of carrier and non-carrier groups of pressure ulcers revealed no statistically significant difference in its occurrence with respect to age, sex, skin color, mobility, or the use of diapers. However, levels of hemoglobin, hematocrit, and red blood cells were found to be statistically different between groups, being lower in lesion-carrying patients. There was no significant difference found in lesion area between patients treated with collagenase or silver sulfadiazine, although both groups showed an overall reduction in lesion area through the treatment course. Conclusion Hematologic parameters showed a statistically significant difference between the two groups. Regarding the treatment of ulcers, there was no difference in the area of the lesion found between the groups treated with collagenase and silver sulfadiazine. .

Objetivo Avaliar os fatores associados ao desenvolvimento da úlcera por pressão e comparar a efetividade de tratamentos farmacológicos. Métodos Os fatores associados ao desenvolvimento de úlcera por pressão foram comparados entre pacientes portadores (n=14) e não portadores (n=16) da lesão. Os pacientes com a ferida foram tratados com sulfadiazina de prata 1% ou colagenase 0,6UI/g, sendo acompanhados durante 8 semanas. Os dados coletados foram analisados considerando-se estatisticamente significativo se p<0,05. Resultados A prevalência de úlcera por pressão foi de cerca de 6%. A comparação entre os grupos de portadores e não portadores de úlcera por pressão não revelou diferença estatística significativa entre ocorrência desta segundo idade, sexo, cor da pele, mobilidade e uso de fralda. Por outro lado, os valores de hemoglobina, hematócrito e hemácias foram estatisticamente diferentes entre os grupos, sendo menor naqueles pacientes portadores da lesão. Não houve diferença significativa na área da lesão entre aqueles pacientes tratados com colagenase ou sulfadiazina de prata, embora ambos os tratamentos tenham evidenciado uma redução média da área da lesão. Conclusão Os parâmetros hematológicos apresentaram diferença estatística entre os dois grupos avaliados, ao contrário das demais variáveis analisadas. Em relação ao tratamento das úlceras, não houve diferença na área da lesão na comparação entre a colagenase e a sulfadiazina. .