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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Polymer–Peptide Conjugates Disassemble Amyloid β Fibrils in a Molecular-Weight Dependent Manner

Amyloid aggregation and deposition are associated with many intractable human diseases. Although the inhibition of amyloid protein aggregation has been well-studied, the disaggregation and dissolution of existing amyloid fibrils is less known. Taking a fibrillar assembly of amyloid β (Aβ) peptide as the model system, in this paper we report multivalent polymer–peptide conjugates (mPPCs) that disassemble preformed Aβ fibrils into dispersible sub-100 nm structures. Atomic force microscopy and dynamic light scattering studies show that the disassembly rate of preformed Aβ fibrils is controlled by the molecular weight of mPPCs. Rate equations on fibril disappearance are deduced from a simple model, which indicate that the disassembly reaction is first-order in the concentration of Aβ fibrils and a pseudo-first-order reaction in the concentration of peptide moieties on mPPCs, respectively. We eliminate the possibility that the disassembly occurs by the association between mPPCs and Aβ monomer/oligomers based on circular dichroism and Thioflavin T fluorescence assays. It is mostly likely that the mPPCs disassemble Aβ fibrils through a direct interaction. Finally, the mPPCs may thus offer a general macromolecular design concept that breaks down existing amyloid fibrils in a predictable fashion.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

PIP4Kγ as a potential target for Huntington's disease

Phosphoinositide lipids provide spatial and temporal regulation of cell signaling and membrane traffic. The PI5P‐4‐kinase family is one of the less studied phosphoinositide lipid kinases. These enzymes catalyze the conversion of phosphatidylinositol 5‐phosphate to phosphatidylinositol 4,5‐bis phosphate. A recent study by Vicinanza et al., a suggested that depletion of the PI5P‐4‐kinase, PIP4Kγ promotes a non‐canonical autophagy pathway. Moreover, this depletion reduced the presence of huntingtin‐exon1‐polyglutamine aggregates. Expression of exon1 of huntingtin with an extended polyglutamine tract is a model for huntingtin protein aggregates. To further test the hypothesis that PIP4Kγ is a potential target to reduce huntingtin aggregates, we tested the depletion of PIP4Kγ in cell culture models that express full length mutant huntingtin (mHtt). We determined that depletion of PIP4Kγ, but not PIP4Kα or PIP4Kβ, lowers the levels of mHtt in patient fibroblasts and in immortalized Hdh Q111 mouse striatal neurons. We show that PIP4Kγ‐dependent depletion of mHtt requires lysosomal function because the depletion is blocked by the lysosomal inhibitor, bafilomycin A1. Moreover, we show that depletion of PIP4Kγ increases autophagic flux, as measured by an increase in LC3‐II levels by western blot analysis and an increase in LC3‐II puncta by microscopy. Our studies suggest that PIP4kγ should be further pursued as a target for Huntington's disease. Support or Funding Information This work was supported by AHA postdoctoral fellowship 14POST20480137 (Sai Srinivas Panapakkam Giridharan), NIH grants R01GM050403 and NS064015 (Lois S Weisman) and by HSS funding 1R03MH084839 (Juan Marugan)

Giridharan, Sai Srinivas Panapakkam↗
NASA NTRS2001

TGF-beta1 release from biodegradable polymer microparticles: its effects on marrow stromal osteoblast function

BACKGROUND: Controlled release of transforming growth factor-beta1 (TGF-beta1) to a bone defect may be beneficial for the induction of a bone regeneration cascade. The objectives of this work were to assess the feasibility of using biodegradable polymer microparticles as carriers for controlled TGF-beta1 delivery and the effects of released TGF-beta1 on the proliferation and differentiation of marrow stromal cells in vitro. METHODS: Recombinant human TGF-beta1 was incorporated into microparticles of blends of poly(DL-lactic-co-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG). Fluorescein isothiocynate-labeled bovine serum albumin (FITC-BSA) was co-encapsulated as a porogen. The effects of PEG content (0, 1, or 5% by weight [wt%]) and buffer pH (3, 5, or 7.4) on the protein release kinetics and the degradation of PLGA were determined in vitro for as long as 28 days. Rat marrow stromal cells were seeded on a biodegradable poly(propylene fumarate) (PPF) substrate. The dose response and biological activity of released TGF-beta1 was determined after 3 days in culture. The effects of TGF-beta1 released from PLGA/PEG microparticles on marrow stromal cell proliferation and osteoblastic differentiation were assessed during a 21-day period. RESULTS: TGF-beta1 was encapsulated along with FITC-BSA into PLGA/PEG blend microparticles and released in a multiphasic fashion including an initial burst for as long as 28 days in vitro. Increasing the initial PEG content resulted in a decreased cumulative mass of released proteins. Aggregation of FITC-BSA occurred at lower buffer pH, which led to decreased release rates of both proteins. The degradation of PLGA was increased at higher PEG content and significantly accelerated at acidic pH conditions. Rat marrow stromal cells cultured on PPF substrates showed a dose response to TGF-beta1 released from the microparticles similar to that of added TGF-beta1, indicating that the activity of TGF-beta1 was retained during microparticle fabrication and after growth factor release. At an optimal TGF-beta1 dosage of 1.0 ng/ml after 3 days, the released TGF-beta1 enhanced the proliferation and osteoblastic differentiation of marrow stromal cells over 21 days of culture, with increased total cell number, alkaline phosphatase activity, and osteocalcin production. CONCLUSIONS: PLGA/PEG blend microparticles can serve as delivery vehicles for controlled release of TGF-beta1, and the released growth factor enhances marrow stromal cell proliferation and osteoblastic differentiation in vitro. CLINICAL RELEVANCE: Controlled release of TGF-beta1 from PLGA/PEG microparticles is representative of emerging tissue engineering technologies that may modulate cellular responses to encourage bone regeneration at a skeletal defect site.

Non-NASA Center↗
DOE OSTI2024

Lipid membrane remodeling and metabolic response during isobutanol and ethanol exposure in Zymomonas mobilis

Abstract Background Recent engineering efforts have targeted the ethanologenic bacterium Zymomonas mobilis for isobutanol production. However, significant hurdles remain due this organism’s vulnerability to isobutanol toxicity, adversely affecting its growth and productivity. The limited understanding of the physiological impacts of isobutanol on Z. mobilis constrains our ability to overcome these production barriers. Results We utilized a systems-level approach comprising LC–MS/MS-based lipidomics, metabolomics, and shotgun proteomics, to investigate how exposure to ethanol and isobutanol impact the lipid membrane composition and overall physiology of Z. mobilis . Our analysis revealed significant and distinct alterations in membrane phospholipid and fatty acid composition resulting from ethanol and isobutanol exposure. Notably, ethanol exposure increased membrane cyclopropane fatty acid content and expression of cyclopropane fatty acid (CFA) synthase. Surprisingly, isobutanol decreased cyclopropane fatty acid content despite robust upregulation of CFA synthase. Overexpression of the native Z. mobilis’ CFA synthase increased cyclopropane fatty acid content in all phospholipid classes and was associated with a significant improvement in growth rates in the presence of added ethanol and isobutanol. Heterologous expression of CFA synthase from Clostridium acetobutylicum resulted in a near complete replacement of unsaturated fatty acids with cyclopropane fatty acids, affecting all lipid classes. However, this did not translate to improved growth rates under isobutanol exposure. Correlating with its greater susceptibility to isobutanol, Z. mobilis exhibited more pronounced alterations in its proteome, metabolome, and overall cell morphology—including cell swelling and formation of intracellular protein aggregates —when exposed to isobutanol compared to ethanol. Isobutanol triggered a broad stress response marked by the upregulation of heat shock proteins, efflux transporters, DNA repair systems, and the downregulation of cell motility proteins. Isobutanol also elicited widespread dysregulation of Z. mobilis ’ primary metabolism evidenced by increased levels of nucleotide degradation intermediates and the depletion of biosynthetic and glycolytic intermediates. Conclusions This study provides a comprehensive, systems-level evaluation of the impact of ethanol and isobutanol exposure on the lipid membrane composition and overall physiology of Z. mobilis . These findings will guide engineering of Z. mobilis towards the creation of isobutanol-tolerant strains that can serve as robust platforms for the industrial production of isobutanol from lignocellulosic sugars.

09 BIOMASS FUELS↗
DOE OSTI2018

Functional characterization of natural variants found on the major stress inducible 70-kDa heat shock gene, HSPA1A, in humans

Highlights: • Mutations, R36C, I74T, and F592S, lower the rate of ATP hydrolysis of HSPA1A. • S16P, R36C, I480N, and F592S alter the interaction of HSPA1A and protein substrates. • R36C increases while the I480N decreases the refolding of heat-denatured luciferase. • R36C, I480N, and F592S failed to protect cells from aggregated protein stress. In this report, we investigated the effects of natural single nucleotide polymorphisms on the function of HSPA1A, the major stress-inducible Hsp70 gene in humans. We first established that all mutant proteins retain their ability to hydrolyze ATP, but three of them had a significantly lower rate of ATP hydrolysis as compared to the wild-type (WT) protein. We also used Isothermal Titration Calorimetry and found that although all mutants bind to protein substrate with dissociation constants similar to the WT protein, four of them had increased reaction entropies. We also tested whether these mutations affect the ability of HSPA1A to refold heat-denatured luciferase. These assays revealed that one mutation resulted in significantly lower levels while a second one resulted in higher levels of the refolded enzyme. We then determined whether the mutations affected the ability of HSPA1A to prevent apoptosis caused by poly-glutamine carrying huntingtin proteins. This assay determined that three of the mutations caused increased cell apoptosis as compared to the WT. Our results reveal that although none of these naturally occurring mutations exists on positions of known function, some alter the molecular chaperone activities of HSPA1A most probably by affecting the allosteric communication between its two major domains.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

AgHalo: A Facile Fluorogenic Sensor to Detect Drug-Induced Proteome Stress

Drug-induced proteome stress that involves protein aggregation may cause adverse effects and undermine the safety profile of a drug. Safety of drugs is regularly evaluated using cytotoxicity assays that measure cell death. However, these assays provide limited insights into the presence of proteome stress in live cells. A fluorogenic protein sensor is reported to detect drug-induced proteome stress prior to cell death. An aggregation prone Halo-tag mutant (AgHalo) was evolved to sense proteome stress through its aggregation. Detection of such conformational changes was enabled by a fluorogenic ligand that fluoresces upon AgHalo forming soluble aggregates. Using 5 common anticancer drugs, we exemplified detection of differential proteome stress before any cell death was observed. Thus, this sensor can be used to evaluate drug safety in a regime that the current cytotoxicity assays cannot cover and be generally applied to detect proteome stress induced by other toxins.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Subventricular Accumulation of Cu in the Aging Mouse Brain Does Not Associate with Anticipated Increases in Markers of Oxidative Stress

Natural aging is associated with mild memory loss and cognitive decline, and age is the greatest risk factor for neurodegenerative diseases, such as Alzheimer’s disease. There is substantial evidence that oxidative stress is a major contributor to both natural aging and neurodegenerative disease, and coincidently, levels of redox active metals such as Fe and Cu are known to be elevated later in life. Recently, a pronounced age-related increase in Cu content has been reported to occur in mice and rats around a vital regulatory brain region, the subventricular zone of lateral ventricles. In our study herein, we have characterized lateral ventricle Cu content in a unique murine model of accelerated aging, senescence accelerated mouse-prone 8 (SAMP8) mice. Our results confirm an age-related increase in ventricle Cu content, consistent with the studies by others in wild-type mice and rats. Specifically, we observed Cu content to increase over the time frame 1 to 5 months and 5 to 9 months, but interestingly, no significant increase occurred between 9 and 12 months (although brain Cu content at 12 months was significantly elevated relative to 1 and 5 month-old animals). Despite the magnitude of Cu increase observed within the cells that comprise the subventricular zone of lateral ventricles (average 3 mM Cu, with isolated subcellular concentrations of 17 mM), we did not detect spectroscopic markers of thiol oxidation, protein aggregation, or lipid oxidation. The lack of evidence for oxidative stress in ex vivo animal tissue is in contrast to in vitro studies demonstrating that thiol, protein, and lipid oxidation is pronounced at these Cu concentrations. We suggest that our findings most likely indicate that the Cu ions in this brain region are sequestered in an unreactive form, possibly extended chains of Cu-thiolate complexes, which do not readily redox cycle in the aqueous cytosol. In conclusion, these results also appear to partially challenge the long-held view that age-related increases in brain metal content drive oxidative stress as we did not observe a concomitant association between age-related Cu increase and markers of oxidative stress, nor did we observe a net increase in Cu content between mice aged 9 and 12 months.

X-ray fluorescence↗
DOE OSTI2024

A Unified Description of Salt Effects on the Liquid–Liquid Phase Separation of Proteins

Protein aggregation via liquid-liquid phase separation (LLPS) is ubiquitous in nature and is intimately connected to many human diseases. Although it is widely known that the addition of salt has crucial impacts on the LLPS of proteins, full understanding of the salt effects remains an outstanding challenge. Here, we develop a molecular theory that systematically incorporates the self-consistent field theory for charged macromolecules into the solution thermodynamics. The electrostatic interaction, hydrophobicity, ion solvation, and translational entropy are included in a unified framework. Our theory fully captures the long-standing puzzles of the nonmonotonic salt concentration dependence and the specific ion effect. We find that proteins show salting-out at low salt concentrations due to ionic screening. The solubility follows the inverse Hofmeister series. In the high salt concentration regime, protein continues salting-out for small ions but turns to salting-in for larger ions, accompanied by the reversal of the Hofmeister series. We reveal that the solubility at high salt concentrations is determined by the competition between the solvation energy and translational entropy of the ion. Furthermore, we derive an analytical criterion for determining the boundary between the salting-in and salting-out regimes, which is in good agreement with experimental results for various proteins and salt ions.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Aneuploidy induces premature aging in yeast due to defects in Ribosome Quality Control [RNASeqData]

Premature aging is a hallmark of Down syndrome, caused by trisomy of human chromosome 21; but the reason is unclear and difficult to study in humans. We used an aneuploid model in wild yeast to show that chromosome amplification disrupts nutrient-induced cell-cycle arrest, quiescence entry, and healthy aging, across genetic backgrounds and amplified chromosomes. We discovered that these defects are due in part to aneuploidy-induced dysfunction in Ribosome Quality Control (RQC). Aneuploids entering quiescence display aberrant ribosome profiles, accumulate RQC intermediates, and harbor an increased load of protein aggregates. Although they have normal proteasome capacity, aneuploids show signs of ubiquitin dysregulation, which impacts cyclin abundance to disrupt arrest. Remarkably, inducing ribosome stalling in euploids produces similar aberrations, while up-regulating limiting RQC subunits or proteins in ubiquitin metabolism alleviates many of the aneuploid defects. Our results raise major implications for other aneuploidy disorders including Down syndrome.

aneuploidy↗
DOE OSTI2024

Aneuploidy induces premature aging in yeast due to defects in Ribosome Quality Control [MoBYSeqData]

Premature aging is a hallmark of Down syndrome, caused by trisomy of human chromosome 21; but the reason is unclear and difficult to study in humans. We used an aneuploid model in wild yeast to show that chromosome amplification disrupts nutrient-induced cell-cycle arrest, quiescence entry, and healthy aging, across genetic backgrounds and amplified chromosomes. We discovered that these defects are due in part to aneuploidy-induced dysfunction in Ribosome Quality Control (RQC). Aneuploids entering quiescence display aberrant ribosome profiles, accumulate RQC intermediates, and harbor an increased load of protein aggregates. Although they have normal proteasome capacity, aneuploids show signs of ubiquitin dysregulation, which impacts cyclin abundance to disrupt arrest. Remarkably, inducing ribosome stalling in euploids produces similar aberrations, while up-regulating limiting RQC subunits or proteins in ubiquitin metabolism alleviates many of the aneuploid defects. Our results raise major implications for other aneuploidy disorders including Down syndrome.

aneuploidy↗
DOE OSTI2024

Premature aging in aneuploid yeast is influenced by aneuploidy-induced defects in Ribosome Quality Control [RiboSeq]

Premature aging is a hallmark of Down syndrome, caused by trisomy of human chromosome 21; but the reason is unclear and difficult to study in humans. We used an aneuploid model in wild yeast to show that chromosome amplification disrupts nutrient-induced cell-cycle arrest, quiescence entry, and healthy aging, across genetic backgrounds and amplified chromosomes. We discovered that these defects are due in part to aneuploidy-induced dysfunction in Ribosome Quality Control (RQC). Aneuploids entering quiescence display aberrant ribosome profiles, accumulate RQC intermediates, and harbor an increased load of protein aggregates. Although they have normal proteasome capacity, aneuploids show signs of ubiquitin dysregulation, which impacts cyclin abundance to disrupt arrest. Remarkably, inducing ribosome stalling in euploids produces similar aberrations, while up-regulating limiting RQC subunits or proteins in ubiquitin metabolism alleviates many of the aneuploid defects. Our results raise major implications for other aneuploidy disorders including Down syndrome.

aneuploidy↗
DOE OSTI2022

Failure Mode Identification of Insulin Drug Products – Impact of Relevant Stress Conditions on the Quality of the Drug

Fast-acting insulin drug products (DPs) are carried and administered by diabetic patients to maintain their blood glucose level throughout the day, exposing the DPs to stress conditions. Apidra, Novolog, and Humalog insulin DPs were tested under various stress conditions. Dynamic light scattering (DLS), and size exclusion chromatography (SEC) were used to monitor the stability and aggregation. Thermal stress alone did not influence the stability. However, 24 hr exposure to vigorous mechanical stress shifted the DLS size peaks of Novolog and Humalog from 5 ± 1 nm to > 50.9 ± 25.6 nm, and the SEC native protein peak areas decreased 52% for Novolog and 18.4% for Humalog. Combined stress accelerated protein aggregation more drastically. Novolog and Humalog size shifted (>75 nm) after 3 hr and the peak area decreased > 97.9% after 6 hr exposure, indicating that high temperature accelerated the aggregation triggered by agitation. Soluble aggregates were captured by DLS early on compared to SEC. Apidra was comparably stable indicating DP formulation plays a critical role in stability. Here this study provides a greater understanding of potential failure modes patients and care givers may encounter while handling insulin DPs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Engineered antibody CH2 domains binding to nucleolin: Isolation, characterization and improvement of aggregation

Smaller recombinant antibody fragments are now emerging as alternatives of conventional antibodies. Especially, immunoglobulin (Ig) constant CH2 domain and engineered CH2 with improved stability are promising as scaffolds for selection of specific binders to various antigens. We constructed a yeast display library based on an engineered human IgG1 CH2 scaffold with diversified loop regions. A group of CH2 binders were isolated from this yeast display library by panning against nucleolin, which is a tumor-associated antigen involved in cell proliferation, tumor cell growth and angiogenesis. Out of 20 mutants, we selected 3 clones exhibiting relatively high affinities to nucleolin on yeasts. However, recombinant CH2 mutants aggregated when they were expressed. To find the mechanism of the aggregation, we employed computational prediction approaches through structural homology models of CH2 binders. The analysis of potential aggregation prone regions (APRs) and solvent accessible surface areas (ASAs) indicated two hydrophobic residues, Val{sub 264} and Leu{sub 309}, in the β-sheet, in which replacement of both charged residues led to significant decrease of the protein aggregation. The newly identified CH2 binders could be improved to use as candidate therapeutics or research reagents in the future. - Highlights: • Novel engineered CH2 domains to nucleolin were identified from the yeast display CH2-based library. • Aggregation prone regions (APRs) were predicted through structural homology models CH2 domains. • The replacement of two hydrophobic residues in APRs significantly led to decrease of the CH2 aggregation.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Lanosterol and 25-hydroxycholesterol dissociate crystallin aggregates isolated from cataractous human lens via different mechanisms

Highlights: • We develop a quantitative ex vivo assay for anti-cataract drug validation. • EC50 values of lanosterol and 25-hydroxycholesterol are at ten micromolar level. • Lanosterol is able to release various human crystallins from the aggregates. • 25-Hydroxycholesterol can only release human α-crystallins. • Lanosterol and 25-hydroxycholesterol are mechanistically different lead compounds. Cataract, a crystallin aggregation disease, is the leading cause of human blindness worldwide. Surgery is the only established treatment of cataracts and no anti-cataract drugs are available thus far. Recently lanosterol and 25-hydroxycholesterol have been reported to redissolve crystallin aggregates and partially restore lens transparency in animals. However, the efficacies of these two compounds have not been quantitatively studied ex vivo using patient tissues. In this research, we developed a quantitative assay applicable to efficacy validations and mechanistic studies by a protocol to isolate protein aggregates from the surgically removed cataractous human lens. Our results showed that both compounds were effective for human cataractous samples with EC50 values at ten micromolar level. The efficacies of both compounds strongly depended on cataract severity. Lanosterol and 25-hydroxycholesterol were two mechanistically different lead compounds of anti-cataract drug design.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

Structure-based design of nanobodies that inhibit seeding of Alzheimer’s patient–extracted tau fibrils

Despite much effort, antibody therapies for Alzheimer’s disease (AD) have shown limited efficacy. Challenges to the rational design of effective antibodies include the difficulty of achieving specific affinity to critical targets, poor expression, and antibody aggregation caused by buried charges and unstructured loops. To overcome these challenges, we grafted previously determined sequences of fibril-capping amyloid inhibitors onto a camel heavy chain antibody scaffold. These sequences were designed to cap fibrils of tau, known to form the neurofibrillary tangles of AD, thereby preventing fibril elongation. The nanobodies grafted with capping inhibitors blocked tau aggregation in biosensor cells seeded with postmortem brain extracts from AD and progressive supranuclear palsy (PSP) patients. The tau capping nanobody inhibitors also blocked seeding by recombinant tau oligomers. Another challenge to the design of effective antibodies is their poor blood–brain barrier (BBB) penetration. In this study, we also designed a bispecific nanobody composed of a nanobody that targets a receptor on the BBB and a tau capping nanobody inhibitor, conjoined by a flexible linker. We provide evidence that the bispecific nanobody improved BBB penetration over the tau capping inhibitor alone after intravenous administration in mice. Our results suggest that the design of synthetic antibodies that target sequences that drive protein aggregation may be a promising approach to inhibit the prion-like seeding of tau and other proteins involved in AD and related proteinopathies.

60 APPLIED LIFE SCIENCES↗
NASA NTRS2000

Applications in Bioastronautics and Bioinformatics: Early Radiation Cataracts Detected by Noninvasive, Quantitative, and Remote Means

Human exploration of Mars is a key goal in NASA's exploration planning in the next 20 years. Maintaining crew health and good vision is certainly an important aspect of achieving a successful mission. Continuous radiation exposure is a risk factor for radiation-induced cataracts in astronauts because radiation exposure in space travel has the potential of accelerating the aging process (ref. 1). A patented compact device (ref. 2) based on the technique of dynamic light scattering (DLS) was designed for monitoring an astronaut's ocular health during long-duration space travel. This capability of early diagnosis, unmatched by any other clinical technique in use today, may enable prompt initiation of preventive/curative therapy. An Internet web-based system integrating photon correlation data and controlling the hardware to monitor cataract development in vivo at a remote site in real time (teleophthalmology) is currently being developed. The new technology detects cataracts very early (at the molecular level). Cataract studies onboard the International Space Station will be helpful in quantifying any adverse effect of radiation to ocular health. The normal lens in a human eye, situated behind the cornea, is a transparent tissue. It contains 35 wt % protein and 65 wt % water. Aging, disease (e.g., diabetes), smoking, dehydration, malnutrition, and exposure to ultraviolet light and ionizing radiation can cause agglomeration of the lens proteins. Protein aggregation can take place anywhere in the lens, causing lens opacity. The aggregation and opacification could produce nuclear (central portion of the lens) or cortical (peripheral) cataracts. Nuclear and posterior subcapsular (the membrane's capsule surrounds the whole lens) cataracts, being on the visual optical axis of the eye, cause visual impairment that can finally lead to blindness. The lens proteins, in their native state, are small in size. As a cataract develops, this size grows from a few nanometers (transparent) to several micrometers (cloudy). Ansari and Datiles have shown that DLS can detect cataracts at least two to three orders of magnitude earlier noninvasively and quantitatively than the best imaging (Scheimpflug) techniques in clinical use today (ref. 3).

Ansari, Rafat R.↗
DOE OSTI2021

Effect of docetaxel on mechanical properties of ovarian cancer cells

Docetaxel could inhibit the proliferation of tumor cells by targeting microtubules. The extension of cellular microtubules plays an important role in the invasion and metastasis of tumor cells. This paper aims to study the distribution and mechanical properties of cytoskeletal proteins with low concentration of docetaxel. MTT assay was used to detect the minimum drug activity concentration of docetaxel on SKOV-3 cells, fluorescence staining was used to analyze the distribution of cytoskeleton proteins, scanning electron microscopy(SEM) was used to observe the morphology of single cells, and atomic force microscopy(AFM) was used to determine the microstructure and mechanical properties of cells. The results showed that the IC{sub 10} of docetaxel was 1 ng/ml. Docetaxel can effectively inhibit the formation of cell pseudopodia, hinder the indirectness between cells, reduce the cell extension area, and make the cells malformed. In addition, when AFM analyzes the effects of drugs on cell microstructure and mechanical properties, the average cell surface roughness and cell height are positively correlated with the concentration of docetaxel. Especially when the concentration was 100 ng/ml, the adhesion decreased by 37.04% and Young's modulus increased by 1.57 times compared with the control group. This may be because docetaxel leads to microtubule remodeling and membrane protein aggregation, which affects cell microstructure and increases cell strength, leading to significant changes in the mechanical properties of ovarian cells. This is of great significance to the study of the formation mechanism of tumor cell invasion and migration activities mediated by actin.

60 APPLIED LIFE SCIENCES↗