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1.
EMBO Rep ; 25(1): 82-101, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-38228789

RESUMEN

The E. coli Paraquat Inducible (Pqi) Pathway is a putative Gram-negative phospholipid transport system. The pathway comprises three components: an integral inner membrane protein (PqiA), a periplasmic spanning MCE family protein (PqiB) and an outer membrane lipoprotein (PqiC). Interactions between all complex components, including stoichiometry, remain uncharacterised; nevertheless, once assembled into their quaternary complex, the trio of Pqi proteins are anticipated to provide a continuous channel between the inner and outer membranes of diderms. Here, we present X-ray structures of both the native and a truncated, soluble construct of the PqiC lipoprotein, providing insight into its biological assembly, and utilise neutron reflectometry to characterise the nature of the PqiB-PqiC-membrane interaction. Finally, we employ phenotypic complementation assays to probe specific PqiC residues, which imply the interaction between PqiB and PqiC is less intimate than previously anticipated.


Asunto(s)
Proteínas de Escherichia coli , Escherichia coli , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas de Escherichia coli/química , Proteínas de la Membrana/metabolismo , Transporte Biológico , Lipoproteínas/metabolismo
2.
Nature ; 573(7772): 122-125, 2019 09.
Artículo en Inglés | MEDLINE | ID: mdl-31413368

RESUMEN

Fossilized eyes permit inferences of the visual capacity of extinct arthropods1-3. However, structural and/or chemical modifications as a result of taphonomic and diagenetic processes can alter the original features, thereby necessitating comparisons with modern species. Here we report the detailed molecular composition and microanatomy of the eyes of 54-million-year-old crane-flies, which together provide a proxy for the interpretation of optical systems in some other ancient arthropods. These well-preserved visual organs comprise calcified corneal lenses that are separated by intervening spaces containing eumelanin pigment. We also show that eumelanin is present in the facet walls of living crane-flies, in which it forms the outermost ommatidial pigment shield in compound eyes incorporating a chitinous cornea. To our knowledge, this is the first record of melanic screening pigments in arthropods, and reveals a fossilization mode in insect eyes that involves a decay-resistant biochrome coupled with early diagenetic mineralization of the ommatidial lenses. The demonstrable secondary calcification of lens cuticle that was initially chitinous has implications for the proposed calcitic corneas of trilobites, which we posit are artefacts of preservation rather than a product of in vivo biomineralization4-7. Although trilobite eyes might have been partly mineralized for mechanical strength, a (more likely) organic composition would have enhanced function via gradient-index optics and increased control of lens shape.


Asunto(s)
Artrópodos/anatomía & histología , Artrópodos/química , Dípteros/anatomía & histología , Dípteros/química , Fósiles , Pigmentos Biológicos/análisis , Pigmentos Biológicos/química , Animales , Biomarcadores/análisis , Biomarcadores/química , Femenino , Pinzones , Masculino , Melaninas/análisis , Melaninas/química , Óptica y Fotónica
3.
Biophys J ; 123(12): 1519-1530, 2024 Jun 18.
Artículo en Inglés | MEDLINE | ID: mdl-38664968

RESUMEN

The type II pneumocytes of the lungs secrete a mixture of lipids and proteins that together acts as a surfactant. The material forms a thin film on the surface of the liquid layer that lines the alveolar air sacks. When compressed by the decreasing alveolar surface area during exhalation, the films reduce surface tension to exceptionally low levels. Pulmonary surfactant is essential for preserving the integrity of the barrier between alveolar air and capillary blood during normal breathing. This review focuses on the major biophysical processes by which endogenous pulmonary surfactant achieves its function and the mechanisms involved in those processes. Vesicles of pulmonary surfactant adsorb rapidly from the alveolar liquid to form the interfacial film. Interfacial insertion, which requires the hydrophobic surfactant protein SP-B, proceeds by a process analogous to the fusion of two vesicles. When compressed, the adsorbed film desorbs slowly. Constituents remain at the surface at high interfacial concentrations that reduce surface tensions well below equilibrium levels. We review the models proposed to explain how pulmonary surfactant achieves both the rapid adsorption and slow desorption characteristic of a functional film.


Asunto(s)
Surfactantes Pulmonares , Surfactantes Pulmonares/metabolismo , Surfactantes Pulmonares/química , Humanos , Animales , Modelos Biológicos , Adsorción , Fenómenos Biofísicos , Tensión Superficial
4.
J Synchrotron Radiat ; 2024 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-39078690

RESUMEN

The advent of diffraction-limited storage rings (DLSRs) has boosted the brilliance or coherent flux by one to two orders of magnitude with respect to the previous generation. One consequence of this brilliance enhancement is an increase in the flux density or number of photons per unit of area and time, which opens new possibilities for the spatiotemporal resolution of X-ray imaging techniques. This paper studies the time-resolved microscopy capabilities of such facilities by benchmarking the ForMAX beamline at the MAX IV storage ring. It is demonstrated that this enhanced flux density using a single harmonic of the source allows micrometre-resolution time-resolved imaging at 2000 tomograms per second and 1.1 MHz 2D acquisition rates using the full dynamic range of the detector system.

5.
Opt Express ; 32(3): 4413-4426, 2024 Jan 29.
Artículo en Inglés | MEDLINE | ID: mdl-38297643

RESUMEN

X-ray multi-projection imaging (XMPI) has the potential to provide rotation-free 3D movies of optically opaque samples. The absence of rotation enables superior imaging speed and preserves fragile sample dynamics by avoiding the centrifugal forces introduced by conventional rotary tomography. Here, we present our XMPI observations at the ID19 beamline (ESRF, France) of 3D dynamics in melted aluminum with 1000 frames per second and 8 µm resolution per projection using the full dynamical range of our detectors. Since XMPI is a method under development, we also provide different tests for the instrumentation of up to 3000 frames per second. As the high-brilliance of 4th generation light-sources becomes more available, XMPI is a promising technique for current and future X-ray imaging instruments.

6.
Soft Matter ; 20(29): 5745-5753, 2024 Jul 24.
Artículo en Inglés | MEDLINE | ID: mdl-38982765

RESUMEN

Pulmonary surfactant forms a thin film on the liquid that lines the alveolar air-sacks. When compressed by the decreasing alveolar surface area during exhalation, the films avoid collapse from the air/water interface and reduce surface tension to exceptionally low levels. To define better the structure of compressed films that determines their susceptibility to collapse, we measured how cholesterol affects the structure and collapse of dipalmitoyl phosphatidylcholine (DPPC) monolayers at physiological temperatures. Grazing incidence X-ray diffraction (GIXD) and grazing incidence X-ray off-specular scattering (GIXOS) established the lateral and transverse structures of films on a Langmuir trough at a surface pressure of 45 mN m-1, just below the equilibrium spreading pressure at which collapse begins. Experiments with captive bubbles at a surface pressure of 51 mN m-1 measured how the steroid affects isobaric collapse. Mol fractions of the steroid (Xchol) at 0.05 removed the tilt by the acyl chains of DPPC, shifted the unit cell from centered rectangular to hexagonal, and dramatically decreased the long-range order. Higher Xchol produced no further change in diffraction, suggesting that cholesterol partitions into a coexisting disordered phase. Cholesterol had minimal effect on rates of collapse until Xchol reached 0.20. Our results demonstrate that the decreased coherence length, indicating conversion of positional order to short-range, is insufficient to make a condensed monolayer susceptible to collapse. Our findings suggest a two-step process by which cholesterol induces disorder. The steroid would first convert the film with crystalline chains to a hexatic phase before generating a fully disordered structure that is susceptible to collapse. These results lead to far-reaching consequences for formulation of animal-derived therapeutic surfactants. Our results suggest that removal of cholesterol from these preparations should be unnecessary below Xchol = 0.20.


Asunto(s)
1,2-Dipalmitoilfosfatidilcolina , Colesterol , Surfactantes Pulmonares , Temperatura , Surfactantes Pulmonares/química , 1,2-Dipalmitoilfosfatidilcolina/química , Colesterol/química
7.
Soft Matter ; 20(20): 4088-4101, 2024 May 22.
Artículo en Inglés | MEDLINE | ID: mdl-38712559

RESUMEN

This research addresses the growing menace of antibiotic resistance by exploring antimicrobial peptides (AMPs) as alternatives to conventional antibiotics. Specifically, we investigate two linear amphipathic AMPs, LE-53 (12-mer) and LE-55 (16-mer), finding that the shorter LE-53 exhibits greater bactericidal activity against both Gram-negative (G(-)) and Gram-positive (G(+)) bacteria. Remarkably, both AMPs are non-toxic to eukaryotic cells. The heightened effectiveness of LE-53 is attributed to its increased hydrophobicity (H) compared to LE-55. Circular dichroism (CD) reveals that LE-53 and LE-55 both adopt ß-sheet and random coil structures in lipid model membranes (LMMs) mimicking G(-) and G(+) bacteria, so secondary structure is not the cause of the potency difference. X-ray diffuse scattering (XDS) reveals increased lipid chain order in LE-53, a potential key distinction. Additionally, XDS study uncovers a significant link between LE-53's upper hydrocarbon location in G(-) and G(+) LMMs and its efficacy. Neutron reflectometry (NR) confirms the AMP locations determined using XDS. Solution small angle X-ray scattering (SAXS) demonstrates LE-53's ability to induce vesicle fusion in bacterial LMMs without affecting eukaryotic LMMs, offering a promising strategy to combat antibiotic-resistant strains while preserving human cell integrity, whereas LE-55 has a smaller ability to induce fusion.


Asunto(s)
Péptidos Antimicrobianos , Humanos , Péptidos Antimicrobianos/química , Péptidos Antimicrobianos/farmacología , Antibacterianos/química , Antibacterianos/farmacología , Pruebas de Sensibilidad Microbiana , Interacciones Hidrofóbicas e Hidrofílicas , Péptidos Catiónicos Antimicrobianos/química , Péptidos Catiónicos Antimicrobianos/farmacología , Bacterias Gramnegativas/efectos de los fármacos
8.
Pharm Res ; 2024 Jul 29.
Artículo en Inglés | MEDLINE | ID: mdl-39078576

RESUMEN

OBJECTIVE: This paper investigates the critical role of material thickness in freeze-dried pellets for enhancing the storage stability of encapsulated bacteria. Freeze dried material of varying thicknesses obtained from different annealing durations is quantified using Scanning Electron Microscopy (SEM) and X-ray microtomography (µCT), the material thickness is then correlated to the storage stability of the encapsulated cells. METHODS: A formulation comprising of sucrose, maltodextrin, and probiotic cells is quenched in liquid nitrogen to form pellets. The pellets undergo different durations of annealing before undergoing freeze-drying. The material thickness is quantified using SEM and µCT. Storage stability in both oxygen-rich and oxygen-poor environments is evaluated by measuring CFU counts and correlated with the pellet structure. RESULTS: The varying annealing protocols produce a range of material thicknesses, with more extensive annealing resulting in thicker materials. Storage stability exhibits a positive correlation with material thickness, indicating improved stability with thicker materials. Non-annealed pellets exhibit structural irregularities and inconsistent storage stability, highlighting the impracticality of avoiding annealing in the freeze-drying process. CONCLUSIONS: Extensive annealing not only enhances the storage stability of probiotic products but also provides greater control over the freeze-drying process, ensuring homogeneous and reproducible products. This study underscores the importance of material thickness in freeze-dried pellets for optimizing storage stability for probiotic formulations, and emphasize the necessity of annealing as a critical step in freeze-drying quenched pellets to achieve desired structural and stability outcomes.

9.
Alzheimers Dement ; 20(4): 3099-3107, 2024 04.
Artículo en Inglés | MEDLINE | ID: mdl-38460119

RESUMEN

Dementia research lacks appropriate representation of diverse groups who often face substantial adversity and greater risk of dementia. Current research participants are primarily well-resourced, non-Hispanic White, cisgender adults who live close to academic medical centers where much of the research is based. Consequently, the field faces a knowledge gap about Alzheimer's-related risk factors in those other groups. The Alzheimer's Association hosted a virtual conference on June 14-16, 2021, supported in part by the National Institute on Aging (R13 AG072859-01), focused on health disparities. The conference was held entirely online and consisted of 2 days of core programming and a day of focused meetings centered on American Indian and Alaska Natives and on LGBTQIA+ populations. Over 1300 registrants attended discussions focused on the structural and systemic inequities experienced across diverse groups, as well as ways to investigate and address these inequities.


Asunto(s)
Nativos Alasqueños , Enfermedad de Alzheimer , Adulto , Humanos , Indio Americano o Nativo de Alaska , Inequidades en Salud , Disparidades en Atención de Salud , Factores de Riesgo , Minorías Sexuales y de Género , Estados Unidos/epidemiología , Blanco
10.
Drug Metab Dispos ; 51(10): 1372-1380, 2023 10.
Artículo en Inglés | MEDLINE | ID: mdl-37524542

RESUMEN

The current study was designed to investigate the influence of allosteric effectors on the metabolism of the prototypical cytochrome P450 (CYP) 3A4 substrate midazolam (MDZ), and on the determination in vitro time-dependent inhibition (TDI) of CYP3A4 using human liver microsomes (HLM). As the concentration of midazolam increased to 250 µM in HLMs, homotropic cooperativity resulted in a decrease in the 1'-hydroxymidazolam to 4-hydroxymidazolam ratio to a maximum of 1.1. The presence of varying concentrations of testosterone, progesterone (PGS), or carbamazepine (CBZ) in HLMs with MDZ could recapitulate the effect of homotropic cooperativity such that the formation rates of the 1'hydroxymidazolam and 4-hydroxymidazolam were equal even at low concentrations of MDZ. The presence of PGS (10 or 100 µM) and CBZ (100 or 1000 µM) in in vitro TDI determination of four known CYP3A4 time-dependent inactivators (clarithromycin, troleandomycin, mibefradil, raloxifene) simultaneously decreased potency and inactivation rate constant, resulting in fold changes in inactivation efficiency on average of 1.6-fold and 13-fold for the low and high concentrations of allosteric modulator tested, respectively. The formation of a metabolic-intermediate complex (MIC) for clarithromycin and troleandomycin decreased in the presence of the allosteric modulators in a concentration-dependent manner, reaching a new steady state formation that could not be overcome with increased incubation time. Maximum reduction of the MIC formed by clarithromycin was up to ∼91%, while troleandomycin MIC decreased up to ∼31%. These findings suggest that the absence of endogenous allosteric modulators may contribute to the poor translation of HLM-based drug-drug interaction predictions. SIGNIFICANCE STATEMENT: The reported overprediction of in vitro human liver microsome time-dependent inhibition of CYP3A4 and observed drug interactions in vivo remains an issue in drug development. We provide characterization of allosteric modulators on the CYP3A4 metabolism of the prototypical substrate midazolam, demonstrating the ability of the modulators to recapitulate the homotropic cooperativity of midazolam. Furthermore, we demonstrate that allosteric heterotropic cooperativity of CYP3A4 can impact the time-dependent inhibition kinetics of known mechanisms-based inhibitors, providing a potential mechanism to explain the overprediction.


Asunto(s)
Citocromo P-450 CYP3A , Midazolam , Humanos , Citocromo P-450 CYP3A/metabolismo , Midazolam/farmacología , Midazolam/metabolismo , Troleandomicina/metabolismo , Troleandomicina/farmacología , Claritromicina , Microsomas Hepáticos/metabolismo , Interacciones Farmacológicas , Carbamazepina/farmacología , Carbamazepina/metabolismo
11.
Pharm Res ; 40(11): 2499-2511, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-36635486

RESUMEN

PURPOSE: The objective of this work was to demonstrate that clinical OAT1-mediated DDIs can be predicted using physiologically based pharmacokinetic (PBPK) modeling. METHODS: LY404039 is a metabotropic glutamate receptor 2/3 agonist and the active moiety of the prodrug pomaglumetad methionil (LY2140023). After oral administration, pomaglumetad methionil is rapidly taken up by enterocytes via PEPT1 and once absorbed, converted to LY404039 via membrane dehydropeptidase 1 (DPEP1). LY404039 is renally excreted by both glomerular filtration and active secretion and in vitro studies showed that the active secretion of LY404039 was mediated by the organic anion transporter 1 (OAT1). Both clinical and in vitro data were used to build a PBPK model to predict OAT1-mediated DDIs. RESULTS: In vitro inhibitory potencies (IC50) of the known OAT inhibitors, probenecid and ibuprofen, were determined to be 4.00 and 2.63 µM, respectively. Subsequently, clinical drug-drug interaction (DDI) study showed probenecid reduced the renal clearance of LY404039 by 30 to 40%. The PBPK bottom-up model, predicted a renal clearance that was approximately 20% lower than the observed one. The middle-out model, using an OAT1 relative activity factor (RAF) of 3, accurately reproduced the renal clearance of LY404039 and pharmacokinetic (PK) changes of LY404039 in the presence of probenecid. CONCLUSIONS: OAT1- mediated DDIs can be predicted using in vitro measured IC50 and PBPK modeling. The effect of ibuprofen was predicted to be minimal (AUC ratio of 1.15) and not clinically relevant.


Asunto(s)
Aminoácidos , Compuestos Bicíclicos Heterocíclicos con Puentes , Óxidos S-Cíclicos , Interacciones Farmacológicas , Aminoácidos/metabolismo , Óxidos S-Cíclicos/sangre , Óxidos S-Cíclicos/farmacocinética , Compuestos Bicíclicos Heterocíclicos con Puentes/sangre , Compuestos Bicíclicos Heterocíclicos con Puentes/farmacocinética , Modelos Biológicos , Profármacos/metabolismo , Profármacos/farmacocinética , Humanos , Masculino , Femenino , Adulto , Persona de Mediana Edad
12.
Chem Rev ; 121(22): 13936-13995, 2021 11 24.
Artículo en Inglés | MEDLINE | ID: mdl-33938738

RESUMEN

This Review focuses on the establishment and development of self-assemblies governed by the supramolecular interactions between cyclic peptides. The Review first describes the type of cyclic peptides able to assemble into tubular structures to form supramolecular cyclic peptide nanotubes. A range of cyclic peptides have been identified to have such properties, including α-peptides, ß-peptides, α,γ-peptides, and peptides based on δ- and ε-amino acids. The Review covers the design and functionalization of these cyclic peptides and expands to a recent advance in the design and application of these materials through their conjugation to polymer chains to generate cyclic peptide-polymer conjugates nanostructures. The Review, then, concentrates on the challenges in characterizing these systems and presents an overview of the various analytical and characterization techniques used to date. This overview concludes with a critical survey of the various applications of the nanomaterials obtained from supramolecular cyclic peptide nanotubes, with a focus on biological and medical applications, ranging from ion channels and membrane insertion to antibacterial materials, anticancer drug delivery, gene delivery, and antiviral applications.


Asunto(s)
Nanoestructuras , Nanotubos , Nanoestructuras/química , Nanotubos/química , Péptidos/química , Péptidos Cíclicos/química , Polímeros/química
13.
Global Health ; 19(1): 17, 2023 03 20.
Artículo en Inglés | MEDLINE | ID: mdl-36935478

RESUMEN

BACKGROUND: The COVID-19 pandemic and the climate emergency threaten progress in reaching many of the Sustainable Development Goal (SDG) targets by 2030. The under-5 mortality and maternal mortality rates are well below the targets, and if we progress at the current pace, there is a high risk of not meeting the 2030 goals. Furthermore, the initial progress in the decline in child and maternal mortality since 1990 is likely to be eroded. Much of this progress has resulted from increased sanitation, drinking water, education, and health service coverage. The adequate provision of public services is possible if there is sufficient government funding. When governments have more income, they spend more on public services, which increases access to fundamental economic and social rights and, thus, contributes to the SDGs. One of the key drivers of government financing, taxation, constitutes 70% of government revenue in low- and lower-middle-income countries. Corporate income tax constitutes 18.8% of tax revenue in African countries compared to 10% of tax revenue in OECD countries. Therefore, it plays a critical role in SDG progress. This paper aims to quantify the contribution of one large taxpayer, that publishes their tax payments, (Vodafone Group Plc) on progress towards SDGs in six African countries. We use econometric modelling to estimate the impact of an increase in government revenue equivalent to Vodafone's average tax paid between 2007-2017. RESULTS: We find that government revenue equivalent to Vodafone's taxes made a significant contribution to progress in attaining selected SDGs. We found that the revenue equivalent to Vodafone's taxes allowed 966,188 people to access clean water and 1,371,972 people to access basic sanitation each year. Over the time period studied, 858,054 children spent an extra year in school and 54,275 children under five years and 3,655 mothers survived. In just one of these countries, Tanzania, the revenue equivalent to Vodafone's tax contribution allowed 174,121 people to access clean water and 223,586 to access sanitation each year. Over the time studied 187,023 children spent an additional year at school, 6,569 additional children under five and 625 additional mothers survived. CONCLUSIONS: These findings demonstrate that the reported contributions from a single multinational corporation drive SDG progress. Furthermore, it highlights the importance of transparent taxes and explores the responsibilities of global institutions, governments, investors, and multinational corporations.


Asunto(s)
COVID-19 , Desarrollo Sostenible , Niño , Humanos , Preescolar , Pandemias , COVID-19/epidemiología , COVID-19/prevención & control , Impuestos , Tanzanía
14.
BMC Public Health ; 23(1): 2255, 2023 11 16.
Artículo en Inglés | MEDLINE | ID: mdl-37974100

RESUMEN

BACKGROUND: Nearly all countries have ratified the United Nations Convention on the Rights of the Child and, therefore, support children having access to their rights. However, only a small minority of children worldwide have access to their environmental, economic, and social rights. The most recent global effort to address these deficits came in 2015, when the United Nations General Assembly agreed to a plan for a fairer and more sustainable future by 2030 and outlined the Sustainable Development Goals (SDGs). One remediable cause is the lack of revenue in many countries, which affects all SDGs. However, illicit financial flows from low-income to high-income countries, including international tax abuse, continue unabated. METHODS: Using the most recent estimates of tax abuse perpetuated by multinational companies and tax evasion through offshore wealth, and precise econometric modelling, we illustrate the potential regarding child rights (or progress towards the SDGs) if there was an increase in revenue equivalent to tax abuse in Malawi, a low-income country particularly vulnerable to climate change. The Government Revenue and Development Estimations model provides realistic estimates of government revenue changes in developmental outcomes. Using panel data on government revenue per capita, it models the impact of increased revenue on governance and SDG progress. RESULTS: If cross-border tax abuse and tax evasion were curtailed, the equivalent increase in government revenue in one country, Malawi, would be associated with 12,000 and 20,000 people having access to basic water and sanitation respectively each year. Each year, an additional 5000 children would attend school, 150 additional children would survive, and 10 mothers would survive childbirth. CONCLUSIONS: More children would access their economic and social rights if actions were taken to close the gap in global governance regarding taxation. We discuss the responsibility of duty bearers, the need for a global body to arbitrate and monitor international tax matters, and how the Government of Malawi could take further domestic action to mitigate the gaps in global governance and protect itself against illicit financial flows, including tax abuse.


Asunto(s)
Renta , Pobreza , Humanos , Niño , Malaui , Naciones Unidas , Gobierno , Impuestos
15.
Alzheimers Dement ; 19 Suppl 9: S126-S131, 2023 11.
Artículo en Inglés | MEDLINE | ID: mdl-37390354

RESUMEN

On September 25 and 26, 2021, the Alzheimer's Association hosted the first meeting focused on people with early-onset Alzheimer's disease (EOAD)-sometimes referred to as younger onset Alzheimer's disease (AD). Though a diagnosis of AD can be devastating at any age, those with a younger onset-defined as symptoms developing prior to 65 years of age-face unique challenges. EOAD occurs when people are in the prime of their lives, often with multiple responsibilities including careers, community activities, and raising children and caring for older family members. These challenges warrant special consideration and study, yet people with EOAD are often excluded from AD research because of their atypical age of onset. To help fill this gap, we designed and launched the Longitudinal Early-Onset Alzheimer's Disease Study (LEADS) to enroll and follow 500 people with EOAD from > 15 sites in the United States, which the National Institute on Aging funded in 2018. The September 2021 meeting was designed to inform people with EOAD and their family members and caregivers about the latest research on the biology of EOAD, treatments in the pipeline, practical considerations about legal and financial arrangements for families, and the support networks available to them. More than 217 registrants attended.


Asunto(s)
Enfermedad de Alzheimer , Niño , Humanos , Edad de Inicio , Estudios Longitudinales
16.
Biophys J ; 121(18): 3533-3541, 2022 09 20.
Artículo en Inglés | MEDLINE | ID: mdl-35841141

RESUMEN

Cholesterol induces faster collapse by compressed films of pulmonary surfactant. Because collapse prevents films from reaching the high surface pressures achieved in the alveolus, most therapeutic surfactants remove or omit cholesterol. The studies here determined the structural changes by which cholesterol causes faster collapse by films of dipalmitoyl phosphatidylcholine, used as a simple model for the functional alveolar film. Measurements of isobaric collapse, with surface pressure held constant at 52 mN/m, showed that cholesterol had little effect until the mol fraction of cholesterol, Xchol, exceeded 0.20. Structural measurements of grazing incidence X-ray diffraction at ambient laboratory temperatures and a surface pressure of 44 mN/m, just below the onset of collapse, showed that the major structural change in an ordered phase occurred at lower Xchol. A centered rectangular unit cell with tilted chains converted to an untilted hexagonal structure over the range of Xchol = 0.0-0.1. For Xchol = 0.1-0.4, the ordered structure was nearly invariant; the hexagonal unit cell persisted, and the spacing of the chains was essentially unchanged. That invariance strongly suggests that above Xchol = 0.1, cholesterol partitions into a disordered phase, which coexists with the ordered domains. The phase rule requires that for a binary film with coexisting phases, the stoichiometries of the ordered and disordered regions must remain constant. Added cholesterol must increase the area of the disordered phase at the expense of the ordered regions. X-ray scattering from dipalmitoyl phosphatidylcholine/cholesterol fit with that prediction. The data also show a progressive decrease in the size of crystalline domains. Our results suggest that cholesterol promotes adsorption not by altering the unit cell of the ordered phase but by decreasing both its total area and the size of individual crystallites.


Asunto(s)
1,2-Dipalmitoilfosfatidilcolina , Surfactantes Pulmonares , 1,2-Dipalmitoilfosfatidilcolina/química , Colesterol/química , Presión , Surfactantes Pulmonares/química , Tensoactivos
17.
Rheumatology (Oxford) ; 61(8): 3246-3256, 2022 08 03.
Artículo en Inglés | MEDLINE | ID: mdl-34897366

RESUMEN

OBJECTIVES: To evaluate the inhibition of progression of structural joint damage through week 48 in patients with moderately to severely active RA receiving upadacitinib as monotherapy or in combination with MTX. METHODS: Radiographic progression was assessed in two phase 3 randomized controlled trials. MTX-naïve patients were randomized to upadacitinib 15 or 30 mg once daily or MTX monotherapy (SELECT-EARLY, n = 945), while MTX inadequate responders (IRs) were randomized to upadacitinib 15 mg once daily or adalimumab 40 mg every other week or placebo added to background MTX (SELECT-COMPARE, n = 1629). The mean changes from baseline in modified total Sharp score (mTSS), joint space narrowing and erosion scores were determined. Data were analysed both by linear extrapolation for missing data imputation and treatment switching and as observed. RESULTS: In patients naïve or with limited exposure to MTX (SELECT-EARLY), mean changes from baseline to week 48 in mTSS were 0.03 for upadacitinib 15 mg, 0.14 for upadacitinib 30 mg and 1.00 for MTX based on linear extrapolation (P < 0.001 for both upadacitinib doses vs MTX). Among patients with an inadequate response to MTX (SELECT-COMPARE), the mean change from baseline in mTSS was significantly reduced in the upadacitinib 15 mg plus MTX group vs placebo plus MTX (0.28 vs 1.73; P < 0.001). The mean change from baseline in the adalimumab plus MTX group was 0.39. CONCLUSION: Upadacitinib monotherapy or in combination with background MTX was effective in inhibiting the progression of structural joint damage through week 48 in MTX-naïve and MTX-IR patients with RA. TRIAL REGISTRATION: ClinicalTrials.gov (https://clinicaltrials.gov), NCT02706873 and NCT02629159.


Asunto(s)
Antirreumáticos , Artritis Reumatoide , Adalimumab/uso terapéutico , Antirreumáticos/efectos adversos , Artritis Reumatoide/inducido químicamente , Artritis Reumatoide/diagnóstico por imagen , Artritis Reumatoide/tratamiento farmacológico , Progresión de la Enfermedad , Método Doble Ciego , Quimioterapia Combinada , Compuestos Heterocíclicos con 3 Anillos , Humanos , Metotrexato/efectos adversos , Ensayos Clínicos Controlados Aleatorios como Asunto , Resultado del Tratamiento
18.
Nature ; 535(7611): 241-5, 2016 07 14.
Artículo en Inglés | MEDLINE | ID: mdl-27362222

RESUMEN

Differences in phenological responses to climate change among species can desynchronise ecological interactions and thereby threaten ecosystem function. To assess these threats, we must quantify the relative impact of climate change on species at different trophic levels. Here, we apply a Climate Sensitivity Profile approach to 10,003 terrestrial and aquatic phenological data sets, spatially matched to temperature and precipitation data, to quantify variation in climate sensitivity. The direction, magnitude and timing of climate sensitivity varied markedly among organisms within taxonomic and trophic groups. Despite this variability, we detected systematic variation in the direction and magnitude of phenological climate sensitivity. Secondary consumers showed consistently lower climate sensitivity than other groups. We used mid-century climate change projections to estimate that the timing of phenological events could change more for primary consumers than for species in other trophic levels (6.2 versus 2.5-2.9 days earlier on average), with substantial taxonomic variation (1.1-14.8 days earlier on average).


Asunto(s)
Cambio Climático/estadística & datos numéricos , Ecosistema , Animales , Organismos Acuáticos , Clima , Conjuntos de Datos como Asunto , Predicción , Lluvia , Estaciones del Año , Especificidad de la Especie , Temperatura , Factores de Tiempo , Reino Unido
19.
Eur J Cancer Care (Engl) ; 31(3): e13581, 2022 May.
Artículo en Inglés | MEDLINE | ID: mdl-35343002

RESUMEN

OBJECTIVE: To evaluate and describe attitudes, quality of life (Qol), needs and preferences of patients with head and neck cancer after 3 years of follow-up care. METHODS: This is an exploratory prospective study of recurrence-free patients. Survey results were compared between 1-, 2- and 3-year post-treatment and by disease characteristics. RESULTS: A total of 116 patients were included with 46% oropharyngeal cancer, 66% early stage disease and 41% having had surgery. After 3 years, most patients reported good to excellent health (88%), however expressed uncertainty regarding recurrence (66%), multiple needs (information on prognosis 91%, long-term sequalae 72%) and wanted to continue with follow-up (96%). Few changes were observed over time, with exceptions. Patients with more advanced disease, oral cancer or who had surgery experienced declining Qol (p < 0.050). Women experienced improvements in Qol domains (pain p = 0.028, speech p = 0.009) over time. Attitudes towards communication with oncologists demonstrated improved patient comfort (p = 0.044) over the 3 years; however, patients' beliefs about their prognosis did not (71% vs. 73% vs. 77% did not believe they were cured, p = 0.581). CONCLUSION: Although patients' needs, preferences and attitudes towards follow-up did not change drastically, important needs persist. This work supports identifying individual patient needs and the challenges in addressing prognostic expectations.


Asunto(s)
Neoplasias de Cabeza y Cuello , Calidad de Vida , Cuidados Posteriores , Femenino , Estudios de Seguimiento , Neoplasias de Cabeza y Cuello/terapia , Humanos , Prioridad del Paciente , Estudios Prospectivos , Autoinforme , Encuestas y Cuestionarios
20.
Molecules ; 27(21)2022 Oct 25.
Artículo en Inglés | MEDLINE | ID: mdl-36364053

RESUMEN

Bio-based and patient-specific three-dimensional (3D) scaffolds can present next generation strategies for bone tissue engineering (BTE) to treat critical bone size defects. In the present study, a composite filament of poly lactic acid (PLA) and 45S5 bioglass (BG) were used to 3D print scaffolds intended for bone tissue regeneration. The thermally induced phase separation (TIPS) technique was used to produce composite spheres that were extruded into a continuous filament to 3D print a variety of composite scaffolds. These scaffolds were analyzed for their macro- and microstructures, mechanical properties, in vitro cytotoxicity and in vivo biocompatibility. The results show that the BG particles were homogeneously distributed within the PLA matrix and contributed to an 80% increase in the mechanical strength of the scaffolds. The in vitro cytotoxicity analysis of PLA-BG scaffolds using L929 mouse fibroblast cells confirmed their biocompatibility. During the in vivo studies, the population of the cells showed an elevated level of macrophages and active fibroblasts that are involved in collagen extracellular matrix synthesis. This study demonstrates successful processing of PLA-BG 3D-printed composite scaffolds and their potential as an implant material with a tunable pore structure and mechanical properties for regenerative bone tissue engineering.


Asunto(s)
Ingeniería de Tejidos , Andamios del Tejido , Ratones , Animales , Ingeniería de Tejidos/métodos , Andamios del Tejido/química , Poliésteres/farmacología , Poliésteres/química , Regeneración Ósea , Impresión Tridimensional
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