Federated Learning: The Pioneering Distributed Machine Learning and Privacy-Preserving Data Technology

Federated learning (pioneered by Google) is a new class of machine learning models trained on distributed data sets, and equally important, a key privacy-preserving data technology. The contribution of this article is to place it in perspective to other data science technologies

Reactivity of Metal-Free and Metal-Associated Amyloid-?? with Glycosylated Polyphenols and Their Esterified Derivatives

Both amyloid-?? (A??) and transition metal ions are shown to be involved in the pathogenesis of Alzheimer???s disease (AD), though the importance of their interactions remains unclear. Multifunctional molecules, which can target metal-free and metal-bound A?? and modulate their reactivity (e.g., A?? aggregation), have been developed as chemical tools to investigate their function in AD pathology; however, these compounds generally lack specificity or have undesirable chemical and biological properties, reducing their functionality. We have evaluated whether multiple polyphenolic glycosides and their esterified derivatives can serve as specific, multifunctional probes to better understand AD. The ability of these compounds to interact with metal ions and metal-free/-associated A??, and further control both metal-free and metal-induced A?? aggregation was investigated through gel electrophoresis with Western blotting, transmission electron microscopy, UV-Vis spectroscopy, fluorescence spectroscopy, and NMR spectroscopy. We also examined the cytotoxicity of the compounds and their ability to mitigate the toxicity induced by both metal-free and metal-bound A??. Of the polyphenols investigated, the natural product (Verbascoside) and its esterified derivative (VPP) regulate the aggregation and cytotoxicity of metal-free and/or metal-associated A?? to different extents. Our studies indicate Verbascoside represents a promising structure for further multifunctional tool development against both metal-free A?? and metal-A??.open0

Chronic Alcohol Exposure Renders Epithelial Cells Vulnerable to Bacterial Infection

<div><p>Despite two centuries of reports linking alcohol consumption with enhanced susceptibility to bacterial infections and in particular gut-derived bacteria, there have been no studies or model systems to assess the impact of long-term alcohol exposure on the ability of the epithelial barrier to withstand bacterial infection. It is well established that acute alcohol exposure leads to reduction in tight and adherens junctions, which in turn leads to increases in epithelial cellular permeability to bacterial products, leading to endotoxemia and a variety of deleterious effects in both rodents and human. We hypothesized that reduced fortification at junctional structures should also reduce the epithelial barrier’s capacity to maintain its integrity in the face of bacterial challenge thus rendering epithelial cells more vulnerable to infection. In this study, we established a cell-culture based model system for long-term alcohol exposure to assess the impact of chronic alcohol exposure on the ability of Caco-2 intestinal epithelial cells to withstand infection when facing pathogenic bacteria under the intact or wounded conditions. We report that daily treatment with 0.2% ethanol for two months rendered Caco-2 cells far more susceptible to wound damage and cytotoxicity caused by most but not all bacterial pathogens tested in our studies. Consistent with acute alcohol exposure, long-term ethanol exposure also adversely impacted tight junction structures, but in contrast, it did not affect the adherens junction. Finally, alcohol-treated cells partially regained their ability to withstand infection when ethanol treatment was ceased for two weeks, indicating that alcohol’s deleterious effects on cells may be reversible.</p> </div

Establishing the long-term alcohol model.

<p>(<b>A</b>) A schematic diagram depicting the long-term alcohol exposure model used in these studies is shown<b>.</b> Caco-2 cells were treated with 0.2% ethanol or 0.2% H₂O (control) daily for 2 months. Confluent monolayers were either kept intact (uninjured) or scrape-wounded as described in materials and methods (Wound model). (<b>B</b>) Control and EtOH Caco-2 confluent monolayers were scrape wounded. The impact of long-term ethanol exposure on the healing dynamics of Caco-2 wounded epithelium was measured by time-lapse videomicroscopy. Representative frames at indicated time points post wounding are shown. (<b>C</b>) Wound areas were measured and the tabulated results relative to the original wound size, indicating that EtOH treated cells heal faster than the control. (<b>D & E</b>) The cytotoxic impact of long-term alcohol exposure on Caco-2 confluent monolayer was evaluated by IF time-lapse videomicroscopy, using PI uptake (red cells are dead) as described in materials and methods. Representative frames at indicated time points are shown in (D) and the results were tabulated from each frame and are shown in (E), indicating that EtOH treatment does not render Caco-2 cells prone to enhanced cytotoxicity. Data were plotted as the Mean ± SEM (* indicates significance with <i>p</i><0.05, n = 3). Arrows point to cluster of cells moving inward.</p

Long-term alcohol exposure renders Caco-2 wounds more vulnerable to bacteria-induced damage.

<p>(<b>A–H</b>) Caco-2 cell monolayers were scrape wounded and infected with indicated bacteria (MOI = 5). Time-lapse videomicroscopy was used to assess healing. (<b>A</b>) Representative frames of the <i>P. aeruginosa</i>-infected wounds are shown. Wound areas were measured relative to the original wound size and the tabulated results are shown in (<b>B</b>). For simplicity, the wound images for other pathogens have been omitted and only the tabulated data are shown in (<b>C–H</b>). As indicated, long-term alcohol exposure renders wounds more susceptible to damage induced by all the pathogens except <i>Listeria monocytogenes</i> (<b>H</b>). (* Indicates significance, <i>p</i><0.05, n = 3 for each bacteria, magnification is 100×).</p

Long-term alcohol exposure adversely affects tight junction but not adherens junction.

<p>Ethanol or H₂O-treated Caco-2 cell monolayers were fixed and the impact of alcohol treatment (EtOH) on tight and adherens juntional proteins (ZO-1 and E-cadherin respectively) was assessed by IF microscopy (<b>A</b> and <b>C</b>) or by Western blot analyses of the cytoplasmic or the membrane fractions (<b>B</b>). The ZO-1 protein levels in different fractions in (B) were determined by densitometry, normalized to GAPDH and plotted with respect to control. The data indicate that long-term alcohol exposure reduces subcellular localization of ZO-1 to tight junction structures at the membrane but it does not effect its overall expression. It also has no appreciable effect on the expression level or the subcellular localization of E-cadherin. (<b>C</b>) Ethanol or H₂O-treated Caco-2 monolayers were infected with PAK (<i>P. aeruginosa</i>) for 5 hrs. Cells were then fixed and the impact of <i>P. aeruginosa</i> on Caco-2 cell-cell monolayer integrity was assessed by ZO-1 staining. Ethanol disruption of tight junctions as shown by IF microscopy of ZO-1 is associated with enhanced damage (white outline) due to infection. (The scale bar  = 25 µm).</p

Stopping alcohol exposure can partially reverse the negative impacts of long-term alcohol exposure.

<p>Alcohol-treated cells were allowed to recover in the absence of ethanol for 2 weeks (Recovery). EtOH, control, and Recovery Caco-2 confluent monolayers were scrape-wounded and their healing capacity in the absence (<b>A–B</b>) or presence of <i>Salmonella typhimurium</i> at MOI = 10 (<b>B–D</b>), was assessed by time-lapse videomicroscopy. Representative movie frames at indicated time points are shown for the uninfected cells in (<b>A</b>) and for the infected cells in (<b>C</b>), and the corresponding tabulated results are shown in (<b>B</b>) and (<b>D</b>) respectively. In the absence of bacteria, ethanol-treated cells heal significantly faster than the mock-treated cells (control) and the recovered cells (Recovery) show intermediate wound closure (<b>A–B</b>). In the presence of <i>Salmonella typhimurium</i>, the recovered cells exhibit similar phenotype to mock-treated cells in that they are significantly more resistant to wound damage induced by <i>S. typhimurium</i> than the EtOH cells (* indicates significance relative to EtOH cells, <i>p</i><0.05, n = 3).</p

Insights into antiamyloidogenic properties of the green tea extract (-)-epigallocatechin-3-gallate toward metal-associated amyloid-beta species

Despite the significance of Alzheimer's disease, the link between metal-associated amyloid-?? (metal-A??) and disease etiology remains unclear. To elucidate this relationship, chemical tools capable of specifically targeting and modulating metal-A?? species are necessary, along with a fundamental understanding of their mechanism at the molecular level. Herein, we investigated and compared the interactions and reactivities of the green tea extract, (-)-epigallocatechin-3-gallate [(2R,3R)-5,7-dihydroxy-2- (3,4,5-trihydroxyphenyl)-3,4-dihydro-2H-1-benzopyran-3-yl 3,4,5- trihydroxybenzoate; EGCG], with metal [Cu(II) and Zn(II)]-A?? and metal-free A?? species. We found that EGCG interacted with metal-A?? species and formed small, unstructured A?? aggregates more noticeably than in metal-free conditions in vitro. In addition, upon incubation with EGCG, the toxicity presented by metalfree A?? and metal-A?? was mitigated in living cells. To understand this reactivity at the molecular level, structural insights were obtained by ion mobility-mass spectrometry (IM-MS), 2D NMR spectroscopy, and computational methods. These studies indicated that (i) EGCG was bound to A?? monomers and dimers, generating more compact peptide conformations than those from EGCGuntreated A?? species; and (ii) ternary EGCG-metal-A?? complexes were produced. Thus, we demonstrate the distinct antiamyloidogenic reactivity of EGCG toward metal-A?? species with a structurebased mechanism.close282