Search Results (262)

Alzheimer’s disease (AD) involves the accumulation of amyloid-β (Aβ) plaques, whose quantification plays a central role in understanding disease progression. Automated segmentation of Aβ deposits in histopathological micrographs enables large-scale analyses but is hindered by the high cost of detailed pixel-level annotations. Weakly supervised learning offers a promising alternative by leveraging coarse or indirect labels to reduce the annotation burden. We evaluated a weakly supervised approach to segment and analyze thioflavin-S-positive parenchymal amyloid pathology in AD and age-matched brains. Our pipeline integrates three key components, each designed to operate under weak supervision. First, robust preprocessing (including retrospective multi-image illumination correction and gradient-based background estimation) was applied to enhance image fidelity and support training, as models rely more on image features. Second, class activation maps (CAMs), generated by a compact deep classifier SqueezeNet, were used to identify, and coarsely localize amyloid-rich parenchymal regions from patch-wise image labels, serving as spatial priors for subsequent refinement without requiring dense pixel-level annotations. Third, a patch-based convolutional neural network, U-Net, was trained on synthetic data generated from micrographs based on CAM-derived pseudo-labels via an extensive object-level augmentation strategy, enabling refined whole-image semantic segmentation and generalization across diverse spatial configurations. To ensure robustness and unbiased evaluation, we assessed the segmentation performance of the entire framework using patient-wise group k-fold cross-validation, explicitly modeling generalization across unseen individuals, critical in clinical scenarios. Despite relying on weak labels, the integrated pipeline achieved strong segmentation performance with an average Dice similarity coefficient (≈0.763) and Jaccard index (≈0.639), widely accepted metrics for assessing segmentation quality in medical image analysis. The resulting segmentations were also visually coherent, demonstrating that weakly supervised segmentation is a viable alternative in histopathology, where acquiring dense annotations is prohibitively labor-intensive and time-consuming. Subsequent morphometric analyses on automatically segmented Aβ deposits revealed size-, structural complexity-, and global geometry-related differences across brain regions and cognitive status. These findings confirm that deposit architecture exhibits region-specific patterns and reflects underlying neurodegenerative processes, thereby highlighting the biological relevance and practical applicability of the proposed image-processing pipeline for morphometric analysis. Full article

Candida fungal species are the most common fungal opportunistic pathogens. Their ability to form antifungal resistant biofilms contributes to their increasing clinical frequency. These fungi express surface-anchored adhesins including members of the Als family. These adhesins mediate epithelial adhesion, aggregation, and biofilm formation. Many of the adhesins contain cross-β core sequences that form amyloid-like protein aggregates on the fungal surface. The aggregates mediate high-avidity bonding that contributes to biofilm establishment and persistence. Accordingly, autopsy sections from individuals with candidiasis and other mycoses have amyloids within abscesses. An amyloid-forming peptide containing a sequence from Candida albicans Als5 bound to C. albicans, C. tropicalis, and C. parapsilosis. C. albicans and C. tropicalis aggregated with beads coated with serum albumin, and the aggregates stained with the amyloid-binding dye thioflavin T. Additionally, an Als5-derived amyloid-inhibiting peptide blocked cell aggregation. The amyloid-inhibiting peptide also blocked C. albicans, C. tropicalis, and C. parapsilosis adhesion to monolayers of FaDu epithelial cells. These results show the involvement of amyloid-like interactions in pathogenesis in several Candida species. Full article

Protein association and aggregation are fundamental processes that play critical roles in a variety of biological phenomena from cell signaling to the development of incurable diseases, including amyloidoses. Understanding the basic biophysical principles governing protein aggregation processes is of crucial importance for developing treatment strategies for diseases associated with protein aggregation, including sarcopenia, as well as for the treatment of pathological processes associated with the disruption of functional protein complexes. This work, using a set of methods such as atomic force microscopy (AFM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction, as well as bioinformatics analysis, investigated the structures of complexes formed by titin and myosin-binding protein C (MyBP-C). TEM revealed the formation of morphologically ordered aggregates in the form of beads during co-incubation of titin and MyBP-C under close-to-physiological conditions (175 mM KCl, pH 7.0). AFM showed the formation of a relatively homogeneous film with local areas of relief change. Fluorimetry with thioflavin T, as well as FTIR spectroscopy, revealed signs of an amyloid-like structure, including a signal in the cross-β region. X-ray diffraction showed the presence of a cross-β structure characteristic of amyloid aggregates. Such structural features were not observed in the control samples of the investigated proteins separately. In sarcomeres, these proteins are associated with each other, and this interaction plays a partial role in the formation of a strong sarcomeric cytoskeleton. We found that under physiological ionic-strength conditions titin and MyBP-C form complexes in which an amyloid-like structure is present. The possible functional significance of amyloid-like aggregation of these proteins in muscle cells in vivo is discussed. Full article

The effects of potassium (K⁺) on yeast metabolism were documented as early as 1940. Studies proposing a mechanism for its transport started in 1950, and in 1953, a mechanism for the stimulation of fermentation was suggested. However, it was not until the 1970s that both mechanisms were clarified in Mexico, and the actual internal pH of the cells was measured. The presence of an H⁺-ATPase that generates an electric plasma membrane difference (PMP), which is used by specific transporters to facilitate the influx of K⁺ and other cations into the cells, was discovered. For years, many efforts were made to estimate and measure the value of the PMP; the obtained results were variable and erratic. In the 1980s, a methodology was developed to estimate the plasma membrane potential by following the fluorescence changes in the DiSC₃(3) dye and measuring its accumulation, which provided actual but inaccurate values. Similar values were obtained by measuring the accumulation of tetraphenylphosphonium. The most reliable method of measuring the actual values of the plasma membrane potential was only recently devised using the also fluorescent dye thioflavin T. This review presents the attempts and outcomes of these experiments necessary to clarify the results reported by different research groups. Innovative research with Genetically Encoded Voltage Indicators (GEVIs) is also included. Full article

Objectives: The compound 3-(4-Hydroxy-3-methoxyphenyl) propionic acid (HMPA) is a terminal metabolite derived from polyphenol compounds. It has been studied for its potential to support brain health indirectly through its anti-oxidant effects and ability to enhance the gut environment; however, its role in dementia pathogenesis is unclear. Therefore, the aim of this study was to evaluate how HMPA inhibits Aβ42 aggregation in vitro. Methods: We examined the inhibitory effects of HMPA on amyloid-β protein (Aβ) aggregation using a thioflavin T (ThT) assay and electron microscopy (EM). Results: ThT assays demonstrated that HMPA inhibited both the nucleation and elongation phases of Aβ aggregation. Additionally, EM of low-molecular-weight (LMW) Aβ42 in the presence of HMPA demonstrated shorter fibrils compared to those formed without HMPA. The EC₅₀ of HMPA in LMW Aβ42 was 5–6 mM. Conclusions: These findings indicate that, similar to several polyphenol compounds such as myricetin and rosmarinic acid, HMPA may inhibit Aβ pathogenesis, although it requires a fairly high concentration in vitro. These findings suggest the potential of HMPA as a lead compound for modulating Aβ-related neurodegeneration. Full article

We aimed to simulate tau abnormalities—specifically hyperphosphorylation and aggregation—that are hallmarks of tauopathies, including Alzheimer’s disease, to evaluate tau-targeting therapies. To model pathological p-tau accumulation at early disease stages, we exposed mouse cortical cultures to redox-active iron from hemin (Hm), a breakdown product of hemoglobin, or challenged them with the excitatory neurotransmitter glutamate. Using the AT8 phospho-specific antibody, we demonstrate that a subtoxic concentration of Hm (3 µM) promotes pathological p-tau accumulation in a subpopulation of cultured cortical neurons and their proximal neurites. Uric acid (UA; 0.1–200 µM), the metabolic end-product of purines in humans, prevented p-tau build-up. Neither xanthine, the immediate precursor of UA, nor allantoin, its oxidized product, reproduced this effect. Live cell imaging studies revealed that UA operates by repressing iron-driven lipid peroxidation. DOT (3 µM), a brain-permeant tetracycline (TC) without antibiotic activity, mimicked UA’s anti-tau and antioxidant effects. Interestingly, both UA and DOT remained effective in preventing p-tau accumulation induced by glutamate (10 µM). To simulate tau aggregation at more advanced disease stages, we conducted a Thioflavin-T aggregation assay. Our findings revealed that UA and DOT prevented tau aggregation seeded by heparin. However, only DOT remained effective when heparin-assembled tau fibrils were used as the seeding material. In summary, our results indicate that UA-elevating agents may hold therapeutic utility for tauopathies. The non-purine compound DOT could serve as an effective alternative to UA-related therapies. Full article

Alzheimer′s disease (AD) is a chronic neurodegenerative disorder that leads to memory loss and changes in mental and behavioral functions in elderly individuals. A major pathological feature of AD is the aggregation of amyloid-beta (Aβ) peptides, along with oxidative stress, inducing neurocellular apoptosis in the brain. Gobaishi (Galla chinensis), a traditional herbal medicine, has gained considerable attention for its constituents and potent therapeutic properties, particularly its strong inhibitory activity against Aβ fibril formation. In this study, we investigated the anti-Aβ aggregation effects of Gobaishi and its active constituents. We isolated two compounds by employing Thioflavin T (ThT) assay-guided fractionation, which were identified through various spectroscopic methods as pentagalloyl glucose (PGG) and methyl gallate (MG). Evaluation of their anti-Aβ aggregation effects revealed that PGG and MG contribute 1.5% and 0.7% of the activity of Gobaishi, respectively. In addition, PGG demonstrated significantly stronger DPPH radical scavenging activity (EC₅₀ = 1.16 µM) compared to MG (EC₅₀ = 6.44 µM). At a concentration of 30 µM, PGG significantly reduced the Aβ-induced cytotoxicity in SH-SY5Y cell lines compared to MG. Based on these findings, both Gobaishi and its active compound PGG are proposed as promising candidates for further investigation as potent anti-amyloidogenic agents in AD management. Full article

Alzheimer’s disease (AD) is a chronic and complex neurodegenerative disorder characterized by progressive cognitive decline, memory loss, and irreversible impairment of brain functions. The etiology of AD is multifactorial, involving a complex interplay of genetic, environmental, and physiological factors, including the aggregation of amyloid-β (Aβ) and oxidative stress (OS). The role of OS in AD pathogenesis is of particular significance, given that an imbalance between oxidants and antioxidants promotes cellular damage, exacerbates Aβ deposition, and leads to cognitive deterioration. Despite extensive research, current therapeutic strategies have largely failed, likely due to the use of single-target drugs unable to halt the multifactorial progression of the disease. In this study, we investigated the synergistic therapeutic effect of plant-derived bioactive compounds Withanone, Apigenin, Bacoside A, Baicalin, and Thymoquinone in combination with N,N-Dimethyltryptamine (NN-DMT), a psychedelic molecule. We used a transgenic Caenorhabditis elegans model to assess the behavioral and molecular outcomes following compound exposure. Motility assays, thioflavin S staining, and survival assays under oxidative stress were employed to evaluate the treatment efficacy. The results of the behavioral and molecular analyses indicated that the combination therapy exhibited a higher efficacy than the monotherapies, leading to a significant reduction in age-related motility defects in the AD model. Furthermore, the combination treatment substantially reduced Aβ plaque burden, enhanced survival following OS insult, and demonstrated a synergistic effect in mitigating AD-related hallmarks. Taken together, these findings support the potential of combining NN-DMT with specific bioactive compounds as a promising multi-target therapeutic approach for AD. Full article

Background: Radiolabeled compounds can serve as diagnostic or therapeutic agents depending on the characteristics of the isotopes used. IMPY (6-iodo-2-(4′-dimethylamino)-phenyl-imidazo[1,2-a]pyridine) is a lipophilic derivative of thioflavin-T, designed to function as a tracer when labeled with radioactive iodine. While it has been primarily studied for imaging applications, its potential therapeutic effects when labeled with iodine-125 (¹²⁵I) remain to be explored. Methods: In this study, IMPY was synthesized and labeled with ¹²⁵I for therapeutic purposes. Three different labeling methods were employed: isotope exchange reaction, redox reaction, and the Iodogen technique. The radiochemical yield of each method was determined to identify the most effective approach. Additionally, the effects of ¹²⁵I-IMPY on neuroblastoma cells were evaluated by assessing its toxicity and cellular uptake. Results: The radiochemical yields for the isotope exchange reaction, redox reaction, and Iodogen technique were found to be 0.96%, 10.74%, and 96.52%, respectively. The Iodogen technique exhibited the highest yield, exceeding 90% even after 48 h, making it the most efficient method. Furthermore, the impact of ¹²⁵I-IMPY on neuroblastoma cells was analyzed, revealing significant cellular uptake and potential therapeutic effects. Conclusions: This study demonstrated that the Iodogen technique is the most effective method for labeling IMPY with ¹²⁵I. The high labeling efficiency and observed cellular effects suggest that ¹²⁵I-IMPY could be considered not only as a tracer but also as a potential therapeutic agent for neuroblastoma. Further studies are needed to explore its full therapeutic potential and mechanism of action. Full article

Background/Objectives: Lipoxins, particularly Lipoxin A4 (LXA4), are endogenous lipid mediators with potent anti-inflammatory and pro-resolving properties, making them promising candidates for the treatment of inflammatory and neurodegenerative disorders. However, their therapeutic application is limited by poor stability and bioavailability. This study aimed to develop and characterize nanomicelles encapsulating LXA4 (nano-lipoxin A4) to improve its pharmacological efficacy against Alzheimer’s disease (AD), a neurodegenerative condition marked by chronic inflammation and beta-amyloid (Aβ) accumulation. Methods: Nano-lipoxin A4 was synthesized using Pluronic F-127 as a carrier and characterized in terms of morphology, physicochemical stability, and in vitro activity against Aβ fibrils. Dissociation of Aβ fibrils was assessed via Thioflavin-T fluorescence assays and transmission electron microscopy. In vivo biodistribution and pharmacokinetic profiles were evaluated using technetium-99m-labeled nano-lipoxin A4 in rodent models. Hepatic biochemical parameters were also measured to assess potential systemic effects. Results: In vitro studies demonstrated that nano-lipoxin A4 effectively dissociated Aβ fibrils at concentrations of 50 nM and 112 nM. Electron microscopy confirmed the disruption of fibrillar structures. In vivo imaging revealed predominant accumulation in the liver and spleen, consistent with reticuloendothelial system uptake. Pharmacokinetic analysis showed a prolonged half-life (63.95 h) and low clearance rate (0.001509 L/h), indicating sustained systemic presence. Biochemical assays revealed elevated liver enzyme levels, suggestive of increased hepatic metabolism or potential hepatotoxicity. Conclusions: Nano-lipoxin A4 exhibits significant therapeutic potential for Alzheimer’s disease through effective modulation of Aβ pathology and favorable pharmacokinetic characteristics. However, the elevation in liver enzymes necessitates further investigation into systemic safety to support clinical translation. Full article

Amyloid beta (Aβ42 and Aβ40) aggregation, along with neurofibrillary tangles, is one of the major neurotoxic events responsible for the onset of Alzheimer’s disease. Many potent peptide-based inhibitors mainly focusing on central hydrophobic core Aβ16–20 (KLVFF) have been reported in recent years. Herein, we report pentapeptides 1–4, based on the β-turn-inducing fragment Aβ19–23 (FFAED). The synthesis of peptides 1–4 was carried out using Fmoc/tBu-based solid-phase peptide synthesis technique, and it was found that pentapeptide 3 potently inhibit the aggregation propensity of Aβ42, when incubated with it at 37 °C for 48 h. The aggregation inhibition study was conducted using thioflavin T-based fluorescence assay and circular dichroism spectroscopy, and supported by transmission electron microscope imaging. The conformational change on the aggregation of Aβ42 and aggregation inhibition by peptides 1–4 was further evaluated using ¹H–¹⁵N HSQC NMR spectroscopy. The results demonstrated that the most potent analog, peptide 3, effectively disrupts the aggregation process. This study is the first to demonstrate that an Aβ19–23 fragment mimic can disrupt the aggregation propensity of Aβ42. Full article

Clinical data as well as animal and cell studies indicate that certain antidiabetic drugs, including glucagon-like peptide 1 receptor agonists (GLP-1RAs), exert therapeutic effects in Alzheimer’s disease (AD) by modulating amyloid-β peptide (Aβ) metabolism. Meanwhile, the direct interactions between GLP-1RAs and Aβ and their functional consequences remain unexplored. In this study, the interactions between monomeric Aβ40/Aβ42 of GLP-1(7-37) and its several analogs (semaglutide (Sema), liraglutide (Lira), exenatide (Exen)) were studied using biolayer interferometry and surface plasmon resonance spectroscopy. The quaternary structure of GLP-1RAs was investigated using dynamic light scattering. The effects of GLP-1RAs on Aβ fibrillation were assessed using the thioflavin T assay and electron microscopy. The impact of GLP-1RAs on Aβ cytotoxicity was evaluated via the MTT assay. Monomeric Aβ40 and Aβ42 directly bind to GLP-1(7-37), Sema, Lira, and Exen, with the highest affinity for Lira (the lowest estimates of equilibrium dissociation constants were 42–60 nM). GLP-1RAs are prone to oligomerization, which may affect their binding to Aβ. GLP-1(7-37) and Exen inhibit Aβ40 fibrillation, whereas Sema promotes it. GLP-1 analogs decrease Aβ cytotoxicity toward SH-SY5Y cells, while GLP-1(7-37) enhances Aβ40 cytotoxicity without affecting the cytotoxic effect of Aβ42. Overall, GLP-1RAs interact with Aβ and differentially modulate its fibrillation and cytotoxicity, suggesting the need for further studies of our observed effects in vivo. Full article

Background: The mutation rate of p53 in breast cancer is around 20%. Specific p53 mutations exhibit prion-like abnormal misfolding and aggregation and gain oncogenic function, causing resistance to the chemotherapy drug doxorubicin. In this study, we identified key upstream regulatory molecules that inhibit the aggregation of p53 with the aim of increasing the anticancer effect of doxorubicin. Methods: Thioflavin T was employed as a fluorescent probe to detect prion-like protein aggregates within cells, the response to various inhibitors was evaluated using CCK8 assay, and the coefficient of drug interaction was calculated. The cell apoptosis ratio was evaluated using Caspase-3/7 based flow cytometry assay. Results: MDA-MB-231 cells (with p53 R280K mutation) and T47D cells (with p53 L194F mutation) had a strong Thioflavin T staining signal, but MDA-MB-468 cells (with p53 R273H mutation) had a weak Thioflavin T signal. Compared to MDA-MB-468 cells, which had a good response to doxorubicin, both MDA-MB-231 and T47D showed high doxorubicin drug resistance. Co-treatment with various misfolding p53 aggregation inhibitors and doxorubicin found that only the HSP70 inhibitor and doxorubicin had synergistic anticancer activity in both MDA-MB-231 and T47D cells. Furthermore, this co-treatment induced cell apoptosis in MDA-MB-231, which was reversed by a pan-caspase inhibitor. Conclusions: Doxorubicin resistance caused by specific p53 mutants can be resolved by co-treatment with a HSP70 inhibitor in breast cancer cells. Full article

CRISPR/Cas-based diagnostics offer unparalleled specificity, but their reliance on fluorescently labeled probes and complex nucleic acid extraction limits field applicability. To tackle this problem, we have developed a label-free, equipment-free platform integrating FTA card-based extraction, CRISPR/Cas12a, and pre-folded G-quadruplex (G4)–Thioflavin T (ThT) signal reporter. This system eliminates costly fluorescent labeling by leveraging G4-ThT structural binding for visible fluorescence output, while FTA cards streamline nucleic acid isolation without centrifugation. Achieving a limit of detection (LOD) to 10¹ CFU/mL for Escherichia coli O157:H7 in spiked food samples, the platform demonstrated 100% concordance with qPCR and standard fluorescent probe-based CRISPR/Cas12a system. Its simplicity, minimal equipment (portable heating/imaging), and cost-effectiveness make it a revolutionary tool for detecting foodborne pathogens in resource-limited environments. Full article

Herein, we proposed a versatile G-quadruplex (G4)-tetrahedral DNA framework (G4-TDF) nanostructure functionalized origami microfluidic paper-based device (μPADs) for fluorescence detection of K⁺ by lighting up thioflavin T (ThT). In this work, TDF provided robust structural support for G-rich sequence in well-defined orientation and spacing to ensure high recognition efficiency, enabling sensitive fluorescence sensing on origami μPAD. After introducing ThT, the G-rich sequences extended from TDF vertices formed a parallel G4 structure, showing weak fluorescence signal output. Upon the presence of target K⁺, this parallel G4 structure transitioned to antiparallel G4 structure, leading to a significantly increase in fluorescence signal of ThT. Benefiting from the outstanding fluorescence enhancement characteristic of the G4 structure for ThT and excellent specificity of the G4 structure to K⁺ plus satisfactory recognition efficiency with the aid of TDF, this origami paper-based fluorescence sensing strategy exhibited an impressive detection limit as low as 0.2 mM with a wide range of 0.5–5.5 mM. This innovative G4-TDF fluorescence sensing was applied for the first time on μPAD, providing a simple, effective, and rapid method for K⁺ detection in human serum with significant potential for clinical diagnostics. Full article