scholarly journals Kinetics of tau aggregation reveals patient specific tau characteristics among Alzheimer's cases

2021 ◽  
Author(s):  
Tarun V Kamath ◽  
Naomi Klickstein ◽  
Caitlin Commins ◽  
Analiese R Fernandes ◽  
Derek H Oakley ◽  
...  
Keyword(s):  
Growth Phase ◽  
Tau Proteins ◽  
Patient Specific ◽  
Lag Phase ◽  
Plateau Phase ◽  
Kinetic Assay ◽  
Cellular Processes ◽  
Morphological Differences ◽  
Tau Aggregation ◽  
Kinetics Of

Abstract The accumulation of tau aggregates throughout the human brain is the hallmark of a number of neurodegenerative conditions classified as tauopathies. Increasing evidence shows that tau aggregation occurs in a “prion-like” manner, in which a small amount of misfolded tau protein can induce other, naïve tau proteins to aggregate. Tau aggregates have been found to differ structurally among different tauopathies. Recently, however, we have suggested that tau oligomeric species may differ biochemically among individual patients with sporadic Alzheimer disease, and have also showed that the bioactivity of the tau species, measured using a cell-based bioassay, also varied among individuals. Here, we adopted a live-cell imaging approach to the standard cell-based bioassay to explore further whether the kinetics of aggregation also differentiated these patients. We found that aggregation can be observed to follow a consistent pattern in all cases, with a lag phase, a growth phase, and a plateau phase, which each provide quantitative parameters by which we characterize aggregation kinetics. The length of the lag phase and magnitude of the plateau phase are both dependent upon the concentration of seeding-competent tau, the relative enrichment of which differs among patients. The slope of the growth phase correlates with morphological differences in the tau aggregates, which may be reflective of underlying structural differences. This kinetic assay confirms and refines the concept of heterogeneity in the characteristics of tau proteopathic seeds among individuals with Alzheimer’s disease and is a method by which future studies may characterize longitudinal changes in tau aggregation and the cellular processes which may influence these changes.

scholarly journals Temporal mechanisms of myogenic specification in human induced pluripotent stem cells

2021 ◽  
Vol 7 (12) ◽  
pp. eabf7412
Author(s):  
P. Nayak ◽  
A. Colas ◽  
M. Mercola ◽  
S. Varghese ◽  
S. Subramaniam
Keyword(s):  
Stem Cells ◽  
Induced Pluripotent Stem Cells ◽  
Pluripotent Stem Cells ◽  
Patient Specific ◽  
Cellular Processes ◽  
Transcriptional Cofactors ◽  
Extracellular Matrix Components ◽  
Cell Subpopulations ◽  
Longitudinal Comparison ◽  
Induced Pluripotent

Understanding the mechanisms of myogenesis in human induced pluripotent stem cells (hiPSCs) is a prerequisite to achieving patient-specific therapy for diseases of skeletal muscle. hiPSCs of different origin show distinctive kinetics and ability to differentiate into myocytes. To address the unique cellular and temporal context of hiPSC differentiation, we perform a longitudinal comparison of the transcriptomic profiles of three hiPSC lines that display differential myogenic specification, one robust and two blunted. We detail temporal differences in mechanisms that lead to robust myogenic specification. We show gene expression signatures of putative cell subpopulations and extracellular matrix components that may support myogenesis. Furthermore, we show that targeted knockdown of ZIC3 at the outset of differentiation leads to improved myogenic specification in blunted hiPSC lines. Our study suggests that β-catenin transcriptional cofactors mediate cross-talk between multiple cellular processes and exogenous cues to facilitate specification of hiPSCs to mesoderm lineage, leading to robust myogenesis.

Deletion of murine tau gene increases tau aggregation in a human mutant tau transgenic mouse model

2010 ◽  
Vol 38 (4) ◽  
pp. 1001-1005 ◽  
Author(s):  
Kunie Ando ◽  
Karelle Leroy ◽  
Céline Heraud ◽  
Anna Kabova ◽  
Zehra Yilmaz ◽  
...  
Keyword(s):  
Mouse Model ◽  
Transgenic Mouse ◽  
Double Mutant ◽  
Transgenic Mouse Model ◽  
Tau Proteins ◽  
Dependent Manner ◽  
Age Dependent ◽  
Ad Alzheimer’S Disease ◽  
Tau Aggregation ◽  
The Brain

We have reported previously a tau transgenic mouse model (Tg30tau) overexpressing human 4R1N double-mutant tau (P301S and G272V) and that develops AD (Alzheimer's disease)-like NFTs (neurofibrillary tangles) in an age-dependent manner. Since murine tau might interfere with the toxic effects of human mutant tau, we set out to analyse the phenotype of our Tg30tau model in the absence of endogenous murine tau with the aim to reproduce more faithfully a model of human tauopathy. By crossing the Tg30tau line with TauKO (tau-knockout) mice, we have obtained a new mouse line called Tg30×TauKO that expresses only exogenous human double-mutant 4R1N tau. Whereas Tg30×TauKO mice express fewer tau proteins compared with Tg30tau, they exhibit augmented sarkosyl-insoluble tau in the brain and an increased number of Gallyas-positive NFTs in the hippocampus. Taken together, exclusion of murine tau causes accelerated tau aggregation during aging of this mutant tau transgenic model.

Synthesis and turnover of proteins and mRNA in germinating wheat embryos

1982 ◽  
Vol 60 (3) ◽  
pp. 389-397 ◽  
Author(s):  
Zbyszko F. Grzelczak ◽  
Mark H. Sattolo ◽  
Linda K. Hanley-Bowdoin ◽  
Theresa D. Kennedy ◽  
Byron G. Lane
Keyword(s):  
Growth Phase ◽  
Time Course ◽  
Phase 1 ◽  
Major Product ◽  
Lag Phase ◽  
Wheat Embryo ◽  
Phase Development ◽  
Wheat Embryos

The most prominent methionine-labeled protein made when cell-free systems are programmed with bulk mRNA from dry wheat embryos has been identified with what may be the most abundant protein in dry wheat embryos. The protein has been brought to purity and has a distinctive amino acid composition, Gly and Glx accounting for almost 40% of the total amino acids. Designated E because of its conspicuous association with early imbibition of dry wheat embryos, the protein and its mRNA are abundant during the "early" phase (0–1 h) of postimbibition development, and easily detected during "lag" phase (1–5 h), but they are almost totally degraded soon after entry into the "growth" phase of development, by about 10 h postimbibition.The most prominent methionine-labeled protein peculiar to the cell-free translational capacity of bulk mRNA from "growth" phase embryos is not detected as a product of in vivo synthesis. Its electrophoretic properties and its time course of emergence, after 5 h postimbibition development, suggest that this major product of cell-free synthesis may be an in vitro counterpart to a prominent methionine-labeled protein made only in vivo, by "growth" phase embryos. Designated G because of its conspicuous association with "growth" phase development, the cell-free product does not comigrate with any prominent dye-stained band in electrophoretic distributions of wheat proteins. The suspected cellular counterpart to G, also, does not comigrate with a prominent dye-stained wheat protein during electrophoresis, and although found in particulate as well as soluble fractions of wheat embryo homogenates it is not concentrated in either nuclei or mitochondria, as isolated.

Effect of Hypertonic Sucrose Upon the Immune Bactericidal Reaction

1970 ◽  
Vol 1 (1) ◽  
pp. 51-55
Author(s):  
Louis H. Muschel ◽  
Linda J. Larsen
Keyword(s):  
Cell Death ◽  
Cell Wall ◽  
Enzymatic Reaction ◽  
Inhibitory Effect ◽  
Lag Phase ◽  
Inner Membrane ◽  
Bactericidal Antibody ◽  
Kinetics Of ◽  
Free Serum ◽  
Supporting Structures

This study was performed to determine the mechanism whereby hypertonic sucrose inhibits the immune bactericidal reaction. Other investigators had postulated that the initial attack of complement (C) on the cell wall was followed with lysozyme-containing whole serum by an enzymatic reaction upon the peptidoglycan substrate resulting in cell death. In the absence of serum lysozyme, secondary lethal changes might occur from damage to the cell's inner membrane as a result of osmotic forces in the presence of a defective cell wall. Hypertonic sucrose giving rise to plasmolysis and protection of the inner membrane was presumed to differentially inhibit the immune response mediated by lysozyme-free serum. The experimental results observed in this investigation have indicated, however, that the inhibitory effect of sucrose upon the bactericidal reaction may be explained simply by its anticomplementary effect and not by any effect on the bacterial cell. This view was supported by the following observations: (i) the comparability of the inhibitory effect of sucrose upon the immune hemolytic and bactericidal reactions, (ii) the comparable percentage loss in bactericidal activity of whole serum and lysozyme-free serum resulting from hypertonic sucrose, (iii) bactericidal antibody titrations were relatively unaffected and C titrations markedly inhibited by sucrose, (iv) the inhibitory effect of sucrose on the bactericidal reaction was unaffected by prior growth of the organism in the presence of sucrose, (v) the kinetics of the bactericidal reactivity of lysozyme-free serum in hypertonic sucrose, compared with whole serum, did not reveal a prolonged lag phase with lysozyme-free serum, but simply diminished reactivity at all times. These observations are compatible with the view that the C attack upon the outer surface of gram-negative bacteria, which plays a part in the cell's permeability control, may account for cell death. In this regard, the immune bactericidal reaction is quite comparable to the lysis of red cells or nucleated cells by C despite the lack of overt lysis in bacteria, probably because of their underlying supporting structures.

scholarly journals Ser/Thr phospho-regulation by PknB and Stp mediates bacterial quiescence and antibiotic persistence in Staphylococcus aureus

2021 ◽  
Author(s):  
Markus Huemer ◽  
Srikanth Mairpady Shambat ◽  
Sandro Pereira ◽  
Lies Van Gestel ◽  
Judith Bergada-Pijuan ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Ribosomal Proteins ◽  
Environmental Changes ◽  
Acid Stress ◽  
Elongation Factor ◽  
Growth Delay ◽  
Lag Phase ◽  
Cellular Processes ◽  
Translational Activity

Staphylococcus aureus colonizes 30 to 50% of healthy adults and can cause a variety of diseases, ranging from superficial to life-threatening invasive infections such as bacteraemia and endocarditis. Often, these infections are chronic and difficult-to-treat despite adequate antibiotic therapy. Most antibiotics act on metabolically active bacteria in order to eradicate them. Thus, bacteria with minimized energy consumption resulting in metabolic quiescence, have increased tolerance to antibiotics. The most energy intensive process in cells - protein synthesis - is attenuated in bacteria entering into quiescence. Eukaryote-like serine/threonine kinases (STKs) and phosphatases (STPs) can fine-tune essential cellular processes, thereby enabling bacteria to quickly respond to environmental changes and to modulate quiescence. Here, we show that deletion of the only annotated functional STP, named Stp, in S. aureus leads to increased bacterial lag-phase and phenotypic heterogeneity under different stress challenges, including acidic pH, intracellular milieu and in vivo abscess environment. This growth delay was associated with reduced intracellular ATP levels and increased antibiotic persistence. Using phosphopeptide enrichment and mass spectrometry-based proteomics, we identified possible targets of Ser/Thr phosphorylation that regulate cellular processes and bacterial growth, such as ribosomal proteins including the essential translation elongation factor EF-G. Finally, we show that acid stress leads to a reduced translational activity in the stp deletion mutant indicating metabolic quiescence correlating with increased antibiotic persistence.

scholarly journals Substantiation of the sell-by date of food products

2020 ◽  
Vol 52 (1) ◽  
pp. 59-63
Author(s):  
S.M. Kuzminskiy ◽  
T.V. Adamchuk ◽  
О.М. Holinko ◽  
N.P. Levytska
Keyword(s):  
Food Products ◽  
Storage Conditions ◽  
Lag Phase ◽  
Contamination Level ◽  
Second Phase ◽  
Phase Duration ◽  
Normative Documents ◽  
Culture Development ◽  
Storage Distribution ◽  
Kinetics Of

Objective of the Work. The overview of current methodical approaches for experimental substantiation of the sell-by date of food products. Methods and Materials. Data analysis of scientific literature and normative documents on methods of substantiation of the sell-by date of food products. Results and Discussion. Sell-by date is a period since product’s manufacture, during which it maintains its safety and quality (including nutritional value) within reasonably foreseeable conditions of storage, distribution and consumption. In the case of new products (recipes) introduction it is necessary to review the sell-by date, and its extending as the need arises. The main aspects of microbiological substantiation of the sell-by date of food products are considered. The identification of microbial hazard for particular product is the first phase of the work. The second phase of the work is to determine the kinetic parameters of precise microorganism’s accumulation to maximum permitted level within regulated and aggravated conditions of product’s storage. Conclusions. In the process of microbiological substantiation of the sell-by date of food products it should be taken into consideration the presence of leading pathogen and causative microorganisms of microbial spoilage, the initial contamination level, the lag phase duration of germ culture development, variations between strains, the kinetics of microorganisms’ accumulation within the product in real and aggravated storage conditions, the indetermination connected with biological nature of microorganisms and their inhomogeneous allocation within the product, the limitation for shortcut research methods (if applicable). The decision rule should be based on the consumer’s risk concept. Key Words: food products, sell-by date, substantiation, microbiological indicators.

Kinetics of the IgG—anti-IgG Reaction, as Evaluated by Conventional and Stopped-Flow Nephelometry

1974 ◽  
Vol 20 (8) ◽  
pp. 1071-1075 ◽  
Author(s):  
John Savory ◽  
Gregory Buffone ◽  
Richard Reich
Keyword(s):  
Polyethylene Glycol ◽  
Data Acquisition System ◽  
Lag Phase ◽  
Stopped Flow ◽  
Kinetic Measurement ◽  
Antigen Concentration ◽  
Specific Proteins ◽  
Rapid Reaction ◽  
Antigen Antibody ◽  
Kinetics Of

Abstract A stopped-flow spectrophotofluorometer equipped with a data-acquisition system was used to study the rate of formation of IgG—anti-IgG complexes by nephelometry. Light-scattering aggregates could be detected within 100 ms. Early rates ( 0-3 s) increased with antigen concentration, while rates during later stages (5-100 s) followed the same trend exhibited by the precipitin curve. Polyethylene glycol (known to exert a profound effect on antigen—antibody reactions) at a concentration of 40 g/liter affected the IgG—anti-IgG reaction as follows: there was an initial lag phase of 5-10 s and a subsequent rapid reaction over the next 20-40 s, characterized by a four-to five-fold enhancement in the amount of light scattered. Our observations demonstrate that centrifugal-analyzer techniques can be used for the kinetic measurement of specific proteins in serum.

scholarly journals AKTIVITAS INULINASE OLEH Pichia manshurica DAN FUSAN F4 PADA FERMENTASI BATCH DENGAN UMBI DAHLIA (Dahlia sp) SEBAGAI SUBSTRAT

REAKTOR ◽  
2015 ◽  
Vol 14 (3) ◽  
pp. 187 ◽  
Author(s):  
Wijanarka Wijanarka ◽  
Endang Sutariningsih Soetarto ◽  
Kumala Dewi ◽  
Ari Indrianto
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Specific Growth ◽  
Lag Phase ◽  
Growth Media ◽  
A Value ◽  
Inulinase Activity ◽  
Pichia Manshurica ◽  
Microbial Strains ◽  
Kinetics Of

ACTIVITY OF INULINASE OF Pichia Manshuria AND FUSAN F4 ON BATCH FERMENTATION UDING DAHLIA TUBER (Dahlia sp) AS A SUBSTRATE. A dahlia tuber is one of the common inulin rich crops. Inulin is formed by units of fructans, which are polymers of D-fructose. Inulinases (EC 3.2.1.7) catalyze the hydrolysis of inulin, producing fructooligosaccharides (FOS), inulooligosaccharides (IOS), pulullan, acetone, butanol and sorbitol, therefore dahlia tubers are used as growth media. The inulin hydrolyzing activity has been reported from various microbial strains Pichia manshurica and Fusan F4 which is the result of fusion protoplast. The objective of this study was to determine the activity of inulinase Pichia manshurica and Fusan F4 on the substrate dahlia tubers. Fusan F4 to increase inulinase activity compared with Pichia manshurica and to investigate the kinetics of specific growth rate (μ) and time double (g) from of Pichia manshurica and Fusan F4. The results showed that the exponential phase occurs at 0-12 hour without a lag phase. P. manshurica has a specific growth rate (μ) of 0.18/hour with time double (g) 3.90 hours and the inulinase enzyme activity of 0.56 IU, while for Fusan F4 consecutive has a value μ of 0.20/hour, g of 3.49 hours and the activity of 0.69 IU. The conclusion of this research is to improve Fusan F4 inulinase activity and the ability has to be better than the Pichia manshurica.Umbi dahlia merupakan salah satu umbi yang mengandung inulin. Inulin merupakan polimer fruktan yang dapat dipecah oleh enzim inulinase (E.C. 3.2.1.7) menjadi fruktosa. Fruktosa merupakan bahan baku dasar untuk pembuatan FOS, IOS, pulullan, aseton dan sorbitol, oleh karena itu umbi dahlia digunakan sebagai media pertumbuhan. Enzim inulinase ini secara indigenous dimiliki oleh Pichia manshurica dan Fusan F4 yang merupakan hasil fusi protoplas.Tujuan  penelitian ini adalah  untuk mengetahui aktivitas inulinase Pichia manshurica dan Fusan F4 pada substrat umbi dahlia, Fusan F4 mampu meningkatkan aktivitas inulinase dibandingkan dengan Pichia manshurica serta untuk mengetahui kinetika kecepatan pertumbuhan specifik (µ) dan waktu generasi (g) Pichia manshurica dan Fusan F4. Hasil penelitian menunjukkan bahwa fase  eksponensial terjadi pada jam ke-0 sampai jam ke-12 tanpa diikuti fase lag, Pichia manshurica mempunyai kecepatan pertumbuhan specific (µ)  sebesar 0,18/jam dengan waktu generasi (g) 3,90 jam dan aktivitas enzim inulinase yang dihasilkan sebesar 0,56 IU, sedangkan untuk fusan F4 secara berturut-turut mempunyai nilai µ sebesar 0,20/jam, g sebesar 3,49 jam dan aktivitas sebesar 0,69 IU. Kesimpulan dari penelitian ini adalah Fusan F4 mampu meningkatkan aktivitas inulinase dan mempunyai kemampuan lebih baik dibanding dengan Pichia manshurica.

scholarly journals Bacterial lipopolysaccharides prime macrophages for enhanced release of arachidonic acid metabolites.

1986 ◽  
Vol 164 (1) ◽  
pp. 165-179 ◽  
Author(s):  
A A Aderem ◽  
D S Cohen ◽  
S D Wright ◽  
Z A Cohn
Keyword(s):  
Arachidonic Acid ◽  
Peritoneal Macrophages ◽  
Lag Phase ◽  
Maximal Concentration ◽  
Latex Beads ◽  
Primed State ◽  
Acid Metabolites ◽  
Bacterial Lipopolysaccharides ◽  
Time Required ◽  
Kinetics Of

Preincubation of resident peritoneal macrophages with 10-100 ng/ml LPS for 60 min resulted in the cells becoming primed for enhanced (three-to eightfold higher) arachidonic acid (20:4) secretion in response to a variety of triggers. The half-maximal concentration of LPS required for priming was 10 ng/ml irrespective of whether the trigger was particulate (examples: zymosan or immune complexes) or soluble (such as PMA or A23187). Similarly, the time required for half-maximal priming of macrophages was 20 min irrespective of which trigger was used. The primed state persisted for at least 30 h. LPS-priming of macrophages also affected the kinetics of 20:4 metabolite secretion. The lag phase characteristically observed when 20:4 secretion is triggered was reduced in LPS-primed cells. Furthermore, LPS-primed cells secreted 20:4 metabolites when challenged with latex beads, while unprimed cells did not. These data suggest that stimuli such as zymosan, which elicit 20:4 secretion in macrophages, promote two signals, a priming signal and a triggering signal. LPS is capable of establishing the priming signal but not the triggering signal, while latex promotes the triggering signal but is unable to prime the cells for 20:4 release. LPS did not effect the profile of 20:4 metabolites secreted in response to any of the triggers, nor did it effect the profile of products synthesized from exogenously added 20:4, suggesting that it did not regulate the 20:4 cascade at the level of either the cyclooxygenase or lipoxygenase pathways. Macrophages respond to LPS without the intervention of T lymphocytes, since the macrophages from nude mice could be primed for enhanced 20:4 secretion.

Key Parameters and Kinetics of Oxidation of Lead (II) Solid Phases by Chlorine in Drinking Water

2006 ◽  
Vol 1 (4) ◽  
Author(s):  
Haizhou Liu ◽  
Gregory V. Korshin ◽  
John F. Ferguson ◽  
Wenju Jiang
Keyword(s):  
Drinking Water ◽  
Transition Phase ◽  
Lag Phase ◽  
X Ray Diffraction ◽  
Water Parameters ◽  
Carbonate Concentration ◽  
Rapid Transition ◽  
Lead Release ◽  
Solid Phases ◽  
Kinetics Of

Equilibria and kinetics of transformations in the Pb(II)/Pb(IV)/chlorine system have a great impact on lead release in drinking water. To explore this system, oxidation of representative Pb(II) solid phases, predominantly hydrocerussite was carried out in chlorinated water with various alkalinities and pH values. It was determined that the oxidation of hydrocerussite by chlorine proceeded via three phases. These included a lag phase, a rapid transition phase and a final quasi steady-state phase. The lag phase corresponded to the transformation of hydrocerussite to cerussite PbCO3, while during the transition phase, the oxidation of PbCO3 and formation of -PbO2 occurred. Key water parameters, such as pH, chlorine concentration and dissolved inorganic carbonate concentration had a pronounced impact on the duration of the lag phase. Data of X-ray diffraction and scanning electron microscopy demonstrated that cerussite PbCO3 was formed as a transient phase during hydrocerussite oxidation, and dispersed microcrystals of scrutinyite -PbO2 were formed when chlorine was consumed.

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