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Serafimov JM, Gillingham D, Kuster S, Hilvert D. The Putative Diels−Alderase Macrophomate Synthase is an Efficient Aldolase. J Am Chem Soc 2008; 130:7798-9. [DOI: 10.1021/ja8017994] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Bergfreund J, Bertsch P, Kuster S, Fischer P. Effect of Oil Hydrophobicity on the Adsorption and Rheology of β-Lactoglobulin at Oil-Water Interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:4929-4936. [PMID: 29616820 DOI: 10.1021/acs.langmuir.8b00458] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The adsorption of protein layers at oil-water interfaces is critical to the formation and stability of various emulsions in, for example, technical applications as well as in biological lipid storage. Effects of ionic strength, pH, temperature, and pretreatments of the proteins are well-known. However, the oil phase has been regarded as exchangeable and its role in protein adsorption has been widely ignored. Herein, the influence of systematically selected oil interfaces of high purity on the formation and properties of β-lactoglobulin (β-lg) adsorption layers was evaluated. Droplet profile tensiometry and interfacial rheometry were employed to determine the adsorption kinetics and dilatational and interfacial shear moduli. We show that depending on the molecular size, flexibility, hydrophobicity, polarity, and polarizability of the oils, globular proteins adsorb distinctively. Stronger interactions of polar oils with the hydrophilic exterior of the native β-lg lead to decelerated protein unfolding. This results in lower surface pressures and slower formation of viscoelastic networks. In addition, polar oils interact stronger with the protein network by hydrophilic bonding and thereby act as softening agents. The observed effects of hydrophobic subphases on the adsorbed protein layers provide knowledge, which promotes higher reproducibility in rheological studies and precise tailoring of interfacial films for enhanced formation and stability of emulsions.
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Kuster S, Riolfo LA, Zalts A, El Hasi C, Almarcha C, Trevelyan PMJ, De Wit A, D'Onofrio A. Differential diffusion effects on buoyancy-driven instabilities of acid–base fronts: the case of a color indicator. Phys Chem Chem Phys 2011; 13:17295-303. [DOI: 10.1039/c1cp21185d] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Powar S, Bhargava R, Daeneke T, Götz G, Bäuerle P, Geiger T, Kuster S, Nüesch FA, Spiccia L, Bach U. Thiolate/Disulfide Based Electrolytes for p-type and Tandem Dye-Sensitized Solar Cells. Electrochim Acta 2015. [DOI: 10.1016/j.electacta.2015.09.026] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Böni L, Fischer P, Böcker L, Kuster S, Rühs PA. Hagfish slime and mucin flow properties and their implications for defense. Sci Rep 2016; 6:30371. [PMID: 27460842 PMCID: PMC4961968 DOI: 10.1038/srep30371] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 06/30/2016] [Indexed: 01/09/2023] Open
Abstract
When hagfish (Myxinidae) are attacked by predators, they form a dilute, elastic, and cohesive defensive slime made of mucins and protein threads. In this study we propose a link between flow behavior and defense mechanism of hagfish slime. Oscillatory rheological measurements reveal that hagfish slime forms viscoelastic networks at low concentrations. Mucins alone did not contribute viscoelasticity, however in shear flow, viscosity was observed. The unidirectional flow, experienced by hagfish slime during suction feeding by predators, was mimicked with extensional rheology. Elongational stresses were found to increase mucin viscosity. The resulting higher resistance to flow could support clogging of the attacker's gills. Shear flow in contrast decreases the slime viscosity by mucin aggregation and leads to a collapse of the slime network. Hagfish may benefit from this collapse when trapped in their own slime and facing suffocation by tying a sliding knot with their body to shear off the slime. This removal could be facilitated by the apparent shear thinning behavior of the slime. Therefore hagfish slime, thickening in elongation and thinning in shear, presents a sophisticated natural high water content gel with flow properties that may be beneficial for both, defense and escape.
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Sattar S, Haase K, Kuster S, Puts M, Spoelstra S, Bradley C, Wildes TM, Alibhai S. Falls in older adults with cancer: an updated systematic review of prevalence, injurious falls, and impact on cancer treatment. Support Care Cancer 2020; 29:21-33. [PMID: 32671565 DOI: 10.1007/s00520-020-05619-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 07/07/2020] [Indexed: 12/21/2022]
Abstract
PURPOSE This update of our 2016 systematic review answers the following questions: (1) How often do older adults with cancer fall? (2) What are the predictors for falls? (3) What are the rates and predictors of injurious falls? (4) What are the circumstances and outcomes of falls? (5) How do falls in older patients affect subsequent cancer treatment? and a new research question, (6) Which fall reduction interventions are efficacious in this population? METHODS MEDLINE, PubMed, CINAHL, and Embase were searched (September 2015-January 25, 2019). Eligible studies included clinical trials and cohort, case-control, and cross-sectional studies published in English in which the sample (or subgroup) included adults aged ≥ 60, with cancer, in whom falls were examined as an outcome. RESULTS A total of 2521 titles were reviewed, 67 full-text articles were screened for eligibility, and 30 new studies were identified. The majority involved the outpatient setting (n = 19) utilizing cross-sectional method (n = 18). Sample size ranged from 21 to 17,958. Fall rates ranged from 1.52 to 3.41% per 1000 patient days (inpatient setting) and from 39%/24 months to 64%/12 months (outpatient setting). One out of the 6 research questions contributed to a new finding: one study reported that 1 in 20 older patients experienced impact on cancer treatment due to falls. No consistent predictors for falls/fall injuries and no studies on fall reduction interventions in the geriatric oncology setting were identified. CONCLUSION This updated review highlights a new gap in knowledge pertaining to interventions to prevent falls. Additionally, new knowledge also emerged in terms of impact of falls on cancer treatment; however, further research may increase generalizability. Falls and fall-related injuries are common in older adults with cancer and may affect subsequent cancer treatment. Further studies on predictors of falls, subsequent impacts, and fall reduction in the oncology setting are warranted.
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Systematic Review |
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Lutz-Bueno V, Isabettini S, Walker F, Kuster S, Liebi M, Fischer P. Ionic micelles and aromatic additives: a closer look at the molecular packing parameter. Phys Chem Chem Phys 2017; 19:21869-21877. [DOI: 10.1039/c7cp03891g] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Tuning mixture of ionic surfactants with aromatic additives results in micelles with impressive viscoelastic properties.
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Weidelener M, Powar S, Kast H, Yu Z, Boix PP, Li C, Müllen K, Geiger T, Kuster S, Nüesch F, Bach U, Mishra A, Bäuerle P. Synthesis and Characterization of Organic Dyes with Various Electron-Accepting Substituents for p-Type Dye-Sensitized Solar Cells. Chem Asian J 2014; 9:3251-63. [DOI: 10.1002/asia.201402654] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 06/27/2014] [Indexed: 11/07/2022]
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Scheuble N, Geue T, Kuster S, Adamcik J, Mezzenga R, Windhab EJ, Fischer P. Mechanically Enhanced Liquid Interfaces at Human Body Temperature Using Thermosensitive Methylated Nanocrystalline Cellulose. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:1396-404. [PMID: 26779953 DOI: 10.1021/acs.langmuir.5b04231] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The mechanical performance of materials at oil/water interfaces after consumption is a key factor affecting hydrophobic drug release. In this study, we methylated the surface of nanocrystalline cellulose (NCC) by mercerization and dimethyl sulfate exposure to produce thermosensitive biopolymers. These methylated NCC (metNCC) were used to investigate interfacial thermogelation at air/water and medium-chain triglyceride (MCT)/water interfaces at body temperature. In contrast to bulk fluid dynamics, elastic layers were formed at room temperature, and elasticity increased significantly at body temperature, which was measured by interfacial shear and dilatational rheology in situ. This unique phenomenon depends on solvent quality, temperature, and polymer concentration at interfaces. Thus, by adjusting the degree of hydrophobicity of metNCC, the interfacial elasticity and thermogelation of the interfaces could be varied. In general, these new materials (metNCC) formed more brittle interfacial layers compared to commercial methylcellulose (MC A15). Thermogelation of methylcellulose promotes attractive intermolecular forces, which were reflected in a change in self-assembly of metNCC at the interface. As a consequence, layer thickness and density increased as a function of temperature. These effects were measured by atomic force microscopy (AFM) images of the displaced interface and confirmed by neutron reflection. The substantial structural and mechanical change of methylcellulose interfaces at body temperature represents a controllable encapsulation parameter allowing optimization of lipid-based drug formulations.
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Böni LJ, Zurflüh R, Baumgartner ME, Windhab EJ, Fischer P, Kuster S, Rühs PA. Effect of ionic strength and seawater cations on hagfish slime formation. Sci Rep 2018; 8:9867. [PMID: 29959378 PMCID: PMC6026207 DOI: 10.1038/s41598-018-27975-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 06/13/2018] [Indexed: 11/09/2022] Open
Abstract
The defensive slime of hagfish consists of a polyanionic mucin hydrogel that synergistically interacts with a fiber network forming a coherent and elastic hydrogel in high ionic strength seawater. In seawater, the slime deploys in less than a second entrapping large quantities of water by a well-timed thread skein unravelling and mucous gel swelling. This rapid and vast hydrogel formation is intriguing, as high ionic strength conditions generally counteract the swelling speed and ratio of polyelectrolyte hydrogels. In this work we investigate the effect of ionic strength and seawater cations on slime formation dynamics and functionality. In the absence of ionic strength skeins swell radially and unravel uncontrolled, probably causing tangling and creating a confined thread network that entraps limited water. At high ionic strength skeins unravel, but create a collapsed and dense fiber network. High ionic strength conditions therefore seem crucial for controlled skein unraveling, however not sufficient for water retention. Only the presence of naturally occurring Ca2+ or Mg2+-ions allowed for an expanded network and full water retention probably due to Ca2+-mediated vesicle rupture and cross-linking of the mucin. Our study demonstrates that hagfish slime deployment is a well-timed, ionic-strength, and divalent-cation dependent dynamic hydrogel formation process.
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Brütsch L, Stringer FJ, Kuster S, Windhab EJ, Fischer P. Chia seed mucilage – a vegan thickener: isolation, tailoring viscoelasticity and rehydration. Food Funct 2019; 10:4854-4860. [DOI: 10.1039/c8fo00173a] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Chia seeds and their mucilage gels provide a nutritionally and functionally promising ingredient for the food and pharmaceutical industry.
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Sattar S, Haase KR, Bradley C, Papadopoulos E, Kuster S, Santa Mina D, Tippe M, Kaur A, Campbell D, Joshua AM, Rediger C, Souied O, Alibhai S. Barriers and facilitators related to undertaking physical activities among men with prostate cancer: a scoping review. Prostate Cancer Prostatic Dis 2021; 24:1007-1027. [PMID: 34108646 DOI: 10.1038/s41391-021-00399-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 04/30/2021] [Accepted: 05/19/2021] [Indexed: 01/17/2023]
Abstract
BACKGROUND Prostate cancer (PC) and its treatments lead to significant acute, chronic, or latent adverse effects that result in declines in patients' physical functions, quality of life and reduced sense of masculinities. Robust evidence shows that physical activity (PA) can improve many health outcomes in men with PC; however, less is known about the facilitators, preferences, and barriers to PA engagement in this population. The purpose of this scoping review is to document the nature and extent of literature related to these aspects of PA participation among men with PC. METHODS We conducted a scoping review of PA among men with PC. Databases searched included Medline, CINAHL, Embase, Rehabilitation & Sports Medicine Source, and SportDiscus from inception to June 30, 2020. Multiple reviewers were used in all screening and data abstractions. RESULTS The search yielded 2788 individual citations after duplicates were removed. Following title and abstract screening, 129 underwent full-text review, and 46 articles were included. Quantitative data related to our research question showed that structured group exercise was the most commonly reported facilitator/preference among men with PC, whereas treatment-related effects and lack of time are the most common barriers. In terms of qualitative data, the most prominent theme noted related to masculinities and gender-specific needs within the context of having PC. CONCLUSION Men with PC have unique facilitators and barriers concerning PA. More work is needed from the research and clinical practice perspectives to enable this population to engage and remain in regular PA.
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Scoping Review |
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van den Berg MEH, Kuster S, Windhab EJ, Adamcik J, Mezzenga R, Geue T, Sagis LMC, Fischer P. Modifying the Contact Angle of Anisotropic Cellulose Nanocrystals: Effect on Interfacial Rheology and Structure. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:10932-10942. [PMID: 30130966 DOI: 10.1021/acs.langmuir.8b00623] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Cellulose nanocrystals (CNCs) are an emerging natural material with the ability to stabilize fluid/fluid interfaces. Native CNC is hydrophilic and does not change the interfacial tension of the stabilized emulsion or foam system. In this study, rodlike cellulose particles were isolated from hemp and chemically modified to alter their hydrophobicity, i.e., their surface activity, which was demonstrated by surface tension measurements of the particles at the air/water interface. The buildup and mechanical strength of the interfacial structure were investigated using interfacial shear and dilatational rheometry. In contrast to most particle or protein-based interfacial adsorption layers, we observe in shear flow a Maxwellian behavior instead of a glasslike frequency response. The slow and reversible buildup of the layer and its unique frequency dependence indicate a weakly aggregated system, which depends on the hydrophobicity and, thus, on the contact angle of the CNC particles at the air/water interface. Exposed to dilatational flow, the weakly aggregated particles cluster and form compact structures. The interfacial structure generated by the different flow fields is characterized by the contact angle, immersion depth, and layer roughness obtained by neutron reflectometry with contrast variation while the size and local structural arrangement of the CNC particles were investigated by AFM imaging.
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Kuster S, Jordan S, Elhai M, Held U, Steigmiller K, Bruni C, Cacciapaglia F, Vettori S, Siegert E, Rednic S, Codullo V, Airo P, Braun-Moscovici Y, Hunzelmann N, Joao Salvador M, Riccieri V, Gheorghiu AM, Alegre Sancho JJ, Romanowska-Prochnicka K, Castellví I, Kötter I, Truchetet ME, López-Longo FJ, Novikov PI, Giollo A, Shirai Y, Belloli L, Zanatta E, Hachulla E, Smith V, Denton C, Ionescu RM, Schmeiser T, Distler JHW, Gabrielli A, Hoffmann-Vold AM, Kuwana M, Allanore Y, Distler O. Effectiveness and safety of tocilizumab in patients with systemic sclerosis: a propensity score matched controlled observational study of the EUSTAR cohort. RMD Open 2022; 8:e002477. [PMID: 36328401 PMCID: PMC9639158 DOI: 10.1136/rmdopen-2022-002477] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 09/14/2022] [Indexed: 11/06/2022] Open
Abstract
OBJECTIVES Tocilizumab showed trends for improving skin fibrosis and prevented progression of lung fibrosis in systemic sclerosis (SSc) in randomised controlled clinical trials. We aimed to assess safety and effectiveness of tocilizumab in a real-life setting using the European Scleroderma Trial and Research (EUSTAR) database. METHODS Patients with SSc fulfilling the American College of Rheumatology (ACR)/EULAR 2013 classification criteria, with baseline and follow-up visits at 12±3 months, receiving tocilizumab or standard of care as the control group, were selected. Propensity score matching was applied. Primary endpoints were the modified Rodnan skin score (mRSS) and FVC at 12±3 months compared between the groups. Secondary endpoints were the percentage of progressive/regressive patients for skin and lung at 12±3 months. RESULTS Ninety-three patients with SSc treated with tocilizumab and 3180 patients with SSc with standard of care fulfilled the inclusion criteria. Comparison between groups did not show significant differences, but favoured tocilizumab across all predefined primary and secondary endpoints: mRSS was lower in the tocilizumab group (difference -1.0, 95% CI -3.7 to 1.8, p=0.48). Similarly, FVC % predicted was higher in the tocilizumab group (difference 1.5 (-6.1 to 9.1), p=0.70). The percentage of progressive/regressive patients favoured tocilizumab over controls. These results were robust regarding the sensitivity analyses. Safety analysis confirmed previously reported adverse event profiles. CONCLUSION Although this large, observational, controlled, real-life EUSTAR study did not show significant effectiveness of tocilizumab on skin and lung fibrosis, the consistency of direction of all predefined endpoints generates hypothesis for potential effectiveness in a broader SSc population.
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Observational Study |
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Brütsch L, Rugiero S, Serrano SS, Städeli C, Windhab EJ, Fischer P, Kuster S. Targeted Inhibition of Enzymatic Browning in Wheat Pastry Dough. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:12353-12360. [PMID: 30403137 DOI: 10.1021/acs.jafc.8b04477] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Enzymatic browning primarily affects fruits and vegetables but also occurs in wheat-based food. Herein, the browning behavior in wheat pastry dough was investigated aiming toward a targeted inhibitory treatment without influencing the pastry dough properties such as workability or taste. Dough discoloration is attributed to several subsequent enzyme-substrate reactions, which can selectively be inhibited by food additives. In most cases, an effective and lasting inhibition is only guaranteed by compounds acting upon multiple inhibition pathways. Despite their effectiveness, the unlimited use of commercial inhibitors is nondesirable due to necessary labeling, thus sustainable and natural inhibitors usually occurring as conventional food ingredients are of interest. It is shown that white wine combined with lemon juice revealed itself as an ideal combination for prevention of enzymatic browning in pastry dough.
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Evaluation Study |
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Böni L, Rühs PA, Windhab EJ, Fischer P, Kuster S. Gelation of Soy Milk with Hagfish Exudate Creates a Flocculated and Fibrous Emulsion- and Particle Gel. PLoS One 2016; 11:e0147022. [PMID: 26808048 PMCID: PMC4726539 DOI: 10.1371/journal.pone.0147022] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 12/27/2015] [Indexed: 11/19/2022] Open
Abstract
Hagfish slime is an ultra dilute, elastic and cohesive hydrogel that deploys within milliseconds in cold seawater from a glandularly secreted exudate. The slime is made of long keratin-like fibers and mucin-like glycoproteins that span a network which entraps water and acts as a defense mechanism against predators. Unlike other hydrogels, the slime only confines water physically and is very susceptible to mechanical stress, which makes it unsuitable for many processing operations and potential applications. Despite its huge potential, little work has been done to improve and functionalize the properties of this hydrogel. To address this shortcoming, hagfish exudate was mixed with a soy protein isolate suspension (4% w/v) and with a soy emulsion (commercial soy milk) to form a more stable structure and combine the functionalities of a suspension and emulsion with those of the hydrogel. Hagfish exudate interacted strongly with the soy systems, showing a markedly increased viscoelasticity and water retention. Hagfish mucin was found to induce a depletion and bridging mechanism, which caused the emulsion and suspension to flocculate, making "soy slime", a cohesive and cold-set emulsion- and particle gel. The flocculation network increases viscoelasticity and substantially contributes to liquid retention by entrapping liquid in the additional confinements between aggregated particles and protein fibers. Because the mucin-induced flocculation resembles the salt- or acid-induced flocculation in tofu curd production, the soy slime was cooked for comparison. The cooked soy slime was similar to conventional cooked tofu, but possessed a long-range cohesiveness from the fibers. The fibrous, cold-set, and curd-like structure of the soy slime represents a novel way for a cold coagulation and fiber incorporation into a suspension or emulsion. This mechanism could be used to efficiently gel functionalized emulsions or produce novel tofu-like structured food products.
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Radeke HH, Kuster S, Kaever V, Resch K. Effects of cyclosporin and FK-506 on glomerular mesangial cells. Evidence for direct inhibition of thromboxane synthase by low cyclosporin concentrations. Eur J Clin Pharmacol 1993; 44 Suppl 1:S11-6. [PMID: 7683610 DOI: 10.1007/bf01428385] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The cellular sources or molecular mechanisms responsible for the derangement of vasoactive prostanoid levels during immunosuppressive cyclosporin (CSA) therapy have not been defined. Using cultured rat glomerular mesangial cells (MC), the cytostatic, cytotoxic and prostanoid synthesis modulating effects of CSA and FK-506 have been measured and compared with the immunosuppressive action of these drugs. Both, CSA and FK-506 inhibited proliferation of MC at similar doses (IC50 approximately 1 microgram.ml-1). Lymphoproliferation was suppressed with IC50s of 50 ng.ml-1 and < 1 ng.ml-1, respectively. In contrast, and unlike FK-506, CSA caused mesangiolysis (IC50 = 4.5 micrograms.ml-1) and concentration dependently inhibited the interleukin-1 beta (IL-1 beta) stimulated mesangial cell release of TXB2 at nanomolar doses (IC50 = 50 ng.ml-1). In kinetic experiments (6-48 h), CSA 1 ng.ml-1 partially and 1 microgram.ml-1 completely abolished the IL-1 beta augmented mesangial secretion TXB2 at all the time points tested. Both, low and high doses of CSA reduced PGE2 release by only 20-40% and then not until at least 24 h of incubation. Measuring enzymatic capacity of membrane fractions of MC to generate TXB2 or PGE2 from added arachidonic acid (10(-5) M), CSA (0.1-1000 ng.ml-1) caused a dose dependent reduction in cyclooxygenase (COX)/thromboxane synthase activity up to 76%, while PGE2 synthesis (COX/prostaglandin synthase) was decreased by 34%. Immunoblots with a specific COX-1 antiserum revealed that COX-1 protein expression of MC was not affected by CSA.(ABSTRACT TRUNCATED AT 250 WORDS)
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Liebi M, Kuster S, Kohlbrecher J, Ishikawa T, Fischer P, Walde P, Windhab EJ. Magnetically enhanced bicelles delivering switchable anisotropy in optical gels. ACS APPLIED MATERIALS & INTERFACES 2014; 6:1100-1105. [PMID: 24369041 DOI: 10.1021/am4046469] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Mesostructures responding to external triggers such as temperature, pH, or magnetic field have the potential to be used as self-acting sensors, detectors, or switches. Key features are a strong and well-defined response to the external trigger. Here, we present magnetic alignable bicelles embedded into a gelatin matrix generating magnetically switchable structures, which can reversibly be locked and unlocked by adjusting the temperature. We show that the disk-like aggregates can be orientated in magnetic fields, and such orientation can be preserved after embedding into gelatin. The resulting gel cubes show an anisotropic transfer for electromagnetic waves, i.e., a different spatial birefringence. Cycling through the melting point of gelatin sets the structure back to its isotropic state providing a read-out of the thermal history. Stacking of the bicelles induced by the gelatin promotes magnetic aligning, as an increased aggregation number in the stacks increases the magnetic orientation energy.
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Böni LJ, Zurflüh R, Widmer M, Fischer P, Windhab EJ, Rühs PA, Kuster S. Hagfish slime exudate stabilization and its effect on slime formation and functionality. Biol Open 2017; 6:1115-1122. [PMID: 28619721 PMCID: PMC5550916 DOI: 10.1242/bio.025528] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 06/02/2017] [Indexed: 01/16/2023] Open
Abstract
Hagfish produce vast amounts of slime when under attack. The slime is the most dilute hydrogel known to date, and is a highly interesting material for biomaterial research. It forms from a glandular secrete, called exudate, which deploys upon contact with seawater. To study slime formation ex vivo and to characterize its material properties, stabilization of the sensitive slime exudate is crucial. In this study, we compared the two main stabilization methods, dispersion in high osmolarity citrate/PIPES (CP) buffer and immersion in oil, and tested the influence of time, temperature and pH on the stability of the exudate and functionality of the slime. Using water retention measurements to assess slime functionality, we found that CP buffer and oil preserved the exudate within the first 5 hours without loss of functionality. For longer storage times, slime functionality decreased for both stabilization methods, for which the breakdown mechanisms differed. Stabilization in oil likely favored temperature-sensitive osmotic-driven swelling and rupture of the mucin vesicles, causing the exudate to gel and clump. Extended storage in CP buffer resulted in an inhibited unraveling of skeins. We suggest that a water soluble protein glue, which mediates skein unraveling in functional skeins, denatures and gradually becomes insoluble during storage in CP buffer. The breakdown was accentuated when the pH of the CP buffer was raised from pH 6.7 to pH 8.5, probably caused by increased denaturation of the protein glue or by inferior vesicle stabilization. However, when fresh exudate was mixed into seawater or phosphate buffer at pH 6-9, slime functionality was not affected, showing pH insensitivity of the slime formation around a neutral pH. These insights on hagfish exudate stabilization mechanisms will support hagfish slime research at a fundamental level, and contribute to resolve the complex mechanisms of skein unraveling and slime formation.
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Liebi M, Kuster S, Kohlbrecher J, Ishikawa T, Fischer P, Walde P, Windhab EJ. Cholesterol-diethylenetriaminepentaacetate complexed with thulium ions integrated into bicelles to increase their magnetic alignability. J Phys Chem B 2013; 117:14743-8. [PMID: 24205912 DOI: 10.1021/jp406599c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Lanthanides have been used for several decades to increase the magnetic alignability of bicelles. DMPE-DTPA (1,2-dimyristoyl-sn-glycero-3-phospho-ethanolamine-diethylenetriaminepentaacetate) is commonly applied to anchor the lanthanides into the bicelles. However, because DMPE-DTPA has the tendency to accumulate at the highly curved edge region of the bicelles and if located there does not contribute to the magnetic orientation energy, we have tested cholesterol-DTPA complexed with thulium ions (Tm(3+)) as an alternative chelator to increase the magnetic alignability. Differential scanning calorimetric (DSC) measurements indicate the successful integration of cholesterol-DTPA into a DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) bilayer. Cryo transmission electron microscopy and small-angle neutron scattering (SANS) measurements show that the disklike structure, that is, bicelles, is maintained if cholesterol-DTPA·Tm(3+) is integrated into a mixture of DMPC, cholesterol, and DMPE-DTPA·Tm(3+). The size of the bicelles is increased compared to the size of the bicelles obtained from mixtures without cholesterol-DTPA·Tm(3+). Magnetic-field-induced birefringence and SANS measurements in a magnetic field show that with addition of cholesterol-DTPA·Tm(3+) the magnetic alignability of these bicelles is significantly increased compared to bicelles composed of DMPC, cholesterol, and DMPE-DTPA·Tm(3+) only.
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Isabettini S, Liebi M, Kohlbrecher J, Ishikawa T, Windhab EJ, Fischer P, Walde P, Kuster S. Tailoring Bicelle Morphology and Thermal Stability with Lanthanide-Chelating Cholesterol Conjugates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:9005-9014. [PMID: 27529644 DOI: 10.1021/acs.langmuir.6b01968] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Bicelles composed of DMPC and phospholipids capable of chelating lanthanide ions, such as 1,2-dimyristoyl-sn-glycero-3-phospho-ethanolamine-diethylene triaminepentaacetate (DMPE-DTPA), are highly tunable magnetically responsive soft materials. Further doping of these systems with cholesterol-DTPA conjugates complexed to a lanthanide ion considerably enhances the bicelle's size and magnetic alignability. The high value of these cholesterol conjugates for bicelle design remains largely unexplored. Herein, we examine how molecular structural alterations within the cholesterol-DTPA conjugates lead to contrasting self-assembled polymolecular aggregate structures when incorporated into DMPC/DMPE-DTPA/Tm(3+) bilayers. The nature of the linker connecting the DTPA-chelating moiety to the sterol backbone is examined by synthesizing conjugates of various linker lengths and polarities. The incorporation of these compounds within the bilayer results in polymolecular aggregate geometries of higher curvature. The increasing degrees of freedom for conformational changes conveyed to the chelator headgroup with increasing linker atomic length reduce the cholesterol-DTPA conjugate's critical packing parameter. Consequently, an inverse correlation between the number of carbon atoms in the linker and the bicelle radius is established. The introduction of polarity into the carbon chain of the linker did not cause major changes in the polymolecular aggregate architecture. Under specific conditions, the additives permit the formation of remarkably temperature-resistant bicelles. The versatility of design offered by these amphiphiles gives rise to new and viable tools for the growing field of magnetically responsive soft materials.
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Isabettini S, Massabni S, Hodzic A, Durovic D, Kohlbrecher J, Ishikawa T, Fischer P, Windhab EJ, Walde P, Kuster S. Molecular engineering of lanthanide ion chelating phospholipids generating assemblies with a switched magnetic susceptibility. Phys Chem Chem Phys 2018; 19:20991-21002. [PMID: 28745755 DOI: 10.1039/c7cp03994h] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Lanthanide ion (Ln3+) chelating amphiphiles are powerful molecules for tailoring the magnetic response of polymolecular assemblies. Mixtures of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dimyristoyl-sn-glycero-3-phospho-ethanolamine-diethylene triaminepentaacetate (DMPE-DTPA) complexed to Ln3+ deliver highly magnetically responsive bicelles. Their magnetic properties are readily tuned by changing the bicellar size or the magnetic susceptibility Δχ of the bilayer lipids. The former technique is intrinsically bound to the region of the phase diagram guarantying the formation of bicelles. Methods aiming towards manipulating the Δχ of the bilayer are comparatively more robust, flexible and lacking. Herein, we synthesized a new Ln3+ chelating phospholipid using glutamic acid as a backbone: DMPE-Glu-DTPA. The chelate polyhedron was specifically engineered to alter the Δχ, whilst remaining geometrically similar to DMPE-DTPA. Planar asymmetric assemblies hundreds of nanometers in size were achieved presenting unprecedented magnetic alignments. The DMPE-Glu-DTPA/Ln3+ complex switched the Δχ, achieving perpendicular alignment of assemblies containing Dy3+ and parallel alignment of those containing Tm3+. Moreover, samples with chelated Yb3+ were more alignable than the Tm3+ chelating counterparts. Such a possibility has never been demonstrated for planar Ln3+ chelating polymolecular assemblies. The physico-chemical properties of these novel assemblies were further studied by monitoring the alignment behavior at different temperatures and by including 16 mol% of cholesterol (Chol-OH) in the phospholipid bilayer. The DMPE-Glu-DTPA/Ln3+ complex and the resulting assemblies are promising candidates for applications in numerous fields including pharmaceutical technologies, structural characterization of membrane biomolecules by NMR spectroscopy, as contrasting agents for magnetic resonance imaging, and for the development of smart optical gels.
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Isabettini S, Liebi M, Kohlbrecher J, Ishikawa T, Fischer P, Windhab EJ, Walde P, Kuster S. Mastering the magnetic susceptibility of magnetically responsive bicelles with 3β-amino-5-cholestene and complexed lanthanide ions. Phys Chem Chem Phys 2018; 19:10820-10824. [PMID: 28401210 DOI: 10.1039/c7cp01025g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The magnetic susceptibility of lanthanide-chelating bicelles was selectively enhanced by introducing 3β-amino-5-cholestene (aminocholesterol, Chol-NH2) in the bilayer. Unprecedented magnetic alignment of the bicelles was achieved without altering their size. An aminocholesterol conjugate (Chol-C2OC2-NH2), in combination with different lanthanide ions, offers the possibility of fine-tuning the bicelle's magnetic susceptibility.
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Isabettini S, Stucki S, Massabni S, Baumgartner ME, Reckey PQ, Kohlbrecher J, Ishikawa T, Windhab EJ, Fischer P, Kuster S. Development of Smart Optical Gels with Highly Magnetically Responsive Bicelles. ACS APPLIED MATERIALS & INTERFACES 2018; 10:8926-8936. [PMID: 29460620 DOI: 10.1021/acsami.7b17134] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Hydrogels delivering on-demand tailorable optical properties are formidable smart materials with promising perspectives in numerous fields, including the development of modern sensors and switches, the essential quality criterion being a defined and readily measured response to environmental changes. Lanthanide ion (Ln3+)-chelating bicelles are interesting building blocks for such materials because of their magnetic responsive nature. Imbedding these phospholipid-based nanodiscs in a magnetically aligned state in gelatin permits an orientation-dependent retardation of polarized light. The resulting tailorable anisotropy gives the gel a well-defined optical signature observed as a birefringence signal. These phenomena were only reported for a single bicelle-gelatin pair and required high magnetic field strengths of 8 T. Herein, we demonstrate the versatility and enhance the viability of this technology with a new generation of aminocholesterol (Chol-NH2)-doped bicelles imbedded in two different types of gelatin. The highly magnetically responsive nature of the bicelles allowed to gel the anisotropy at commercially viable magnetic field strengths between 1 and 3 T. Thermoreversible gels with a unique optical signature were generated by exposing the system to various temperature conditions and external magnetic field strengths. The resulting optical properties were a signature of the gel's environmental history, effectively acting as a sensor. Solutions containing the bicelles simultaneously aligning parallel and perpendicular to the magnetic field directions were obtained by mixing samples chelating Tm3+ and Dy3+. These systems were successfully gelled, providing a material with two distinct temperature-dependent optical characteristics. The high degree of tunability in the magnetic response of the bicelles enables encryption of the gel's optical properties. The proposed gels are viable candidates for temperature tracking of sensitive goods and provide numerous perspectives for future development of tomorrow's smart materials and technologies.
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Chen Y, Gavaliatsis T, Kuster S, Städeli C, Fischer P, Windhab EJ. Crust treatments to reduce bread staling. Curr Res Food Sci 2021; 4:182-190. [PMID: 33889851 PMCID: PMC8050008 DOI: 10.1016/j.crfs.2021.03.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 03/10/2021] [Accepted: 03/11/2021] [Indexed: 11/25/2022] Open
Abstract
Crust treatments, namely edible bread coatings, enzymatic crust modification and chemical crust modification, were introduced with the intention to minimize bread water loss during ambient storage. It was observed that compared to the treated bread, the untreated bread had significantly higher weight loss and crumb firmness after 14 days of ambient storage. A large array of materials was tested, among which hydrophobic coatings were shown to have the highest moisture barrier efficiency. In particular, the 20% candelilla wax coating (solution of 20% candelilla wax in sunflower oil), 20% beeswax coating (solution of 20% beeswax in sunflower oil) and HPMC oleogel coating (coating containing hydroxypropyl methyl cellulose oleogel) were proved to be most effective, thanks to their low affinity with water and low water vapor permeability. The application of the 20% candelilla wax coating resulted in reductions of the bread weight loss from about 30 to 13% and the crumb firmness from above 500 to 34 N after a storage period of 14 days. In addition, it was noted that the enzymatic and chemical crust modifications yielded moderately good results, but showed a significantly altered appearance of the bread crust.
Wax coating as edible food coating is used to inhibit bread staling. Moisture barrier by the wax coating is applied to the bread crust. Coatings significantly minimize the bread weight loss and crust hardening. Crust morphology is monitored by micro-CT.
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