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1.
Sci Rep ; 14(1): 12533, 2024 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-38822066

RESUMO

In flaviviruses such as Dengue or Zika, non-structural (NS) NS4A protein forms homo-oligomers, participates in membrane remodelling and is critical for virulence. In both viruses, mature NS4A has the same length and three predicted hydrophobic domains. The oligomers formed by Dengue NS4A are reported to be small (n = 2, 3), based on denaturing SDS gels, but no high-resolution structure of a flavivirus NS4A protein is available, and the size of the oligomer in lipid membranes is not known. Herein we show that crosslinking Zika NS4A protein in lipid membranes results in oligomers at least up to hexamers. Further, sedimentation velocity shows that NS4A in mild detergent C14-betaine appears to be in fast equilibrium between at least two species, where one is smaller, and the other larger, than a trimer or a tetramer. Consistently, sedimentation equilibrium data was best fitted to a model involving an equilibrium between dimers (n = 2) and hexamers (n = 6). Overall, the large, at least hexameric, oligomers obtained herein in liposomes and in mild detergent are more likely to represent the forms of NS4A present in cell membranes.


Assuntos
Detergentes , Lipossomos , Multimerização Proteica , Proteínas não Estruturais Virais , Zika virus , Lipossomos/química , Lipossomos/metabolismo , Proteínas não Estruturais Virais/química , Proteínas não Estruturais Virais/metabolismo , Detergentes/química , Zika virus/química
2.
Lancet Rheumatol ; 6(6): e374-e383, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38734017

RESUMO

BACKGROUND: Giant cell arteritis is an age-related vasculitis that mainly affects the aorta and its branches in individuals aged 50 years and older. Current options for diagnosis and treatment are scarce, highlighting the need to better understand its underlying pathogenesis. Genome-wide association studies (GWAS) have emerged as a powerful tool for unravelling the pathogenic mechanisms involved in complex diseases. We aimed to characterise the genetic basis of giant cell arteritis by performing the largest GWAS of this vasculitis to date and to assess the functional consequences and clinical implications of identified risk loci. METHODS: We collected and meta-analysed genomic data from patients with giant cell arteritis and healthy controls of European ancestry from ten cohorts across Europe and North America. Eligible patients required confirmation of giant cell arteritis diagnosis by positive temporal artery biopsy, positive temporal artery doppler ultrasonography, or imaging techniques confirming large-vessel vasculitis. We assessed the functional consequences of loci associated with giant cell arteritis using cell enrichment analysis, fine-mapping, and causal gene prioritisation. We also performed a drug repurposing analysis and developed a polygenic risk score to explore the clinical implications of our findings. FINDINGS: We included a total of 3498 patients with giant cell arteritis and 15 550 controls. We identified three novel loci associated with risk of giant cell arteritis. Two loci, MFGE8 (rs8029053; p=4·96 × 10-8; OR 1·19 [95% CI 1·12-1·26]) and VTN (rs704; p=2·75 × 10-9; OR 0·84 [0·79-0·89]), were related to angiogenesis pathways and the third locus, CCDC25 (rs11782624; p=1·28 × 10-8; OR 1·18 [1·12-1·25]), was related to neutrophil extracellular traps (NETs). We also found an association between this vasculitis and HLA region and PLG. Variants associated with giant cell arteritis seemed to fulfil a specific regulatory role in crucial immune cell types. Furthermore, we identified several drugs that could represent promising candidates for treatment of this disease. The polygenic risk score model was able to identify individuals at increased risk of developing giant cell arteritis (90th percentile OR 2·87 [95% CI 2·15-3·82]; p=1·73 × 10-13). INTERPRETATION: We have found several additional loci associated with giant cell arteritis, highlighting the crucial role of angiogenesis in disease susceptibility. Our study represents a step forward in the translation of genomic findings to clinical practice in giant cell arteritis, proposing new treatments and a method to measure genetic predisposition to this vasculitis. FUNDING: Institute of Health Carlos III, Spanish Ministry of Science and Innovation, UK Medical Research Council, and National Institute for Health and Care Research.


Assuntos
Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Arterite de Células Gigantes , Arterite de Células Gigantes/genética , Arterite de Células Gigantes/patologia , Humanos , Loci Gênicos/genética , Feminino , Masculino , Idoso , Polimorfismo de Nucleotídeo Único , Pessoa de Meia-Idade , Estudos de Casos e Controles
3.
Nat Commun ; 15(1): 4491, 2024 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-38802374

RESUMO

Actin nucleotide-dependent actin remodeling is essential to orchestrate signal transduction and cell adaptation. Rapid energy starvation requires accurate and timely reorganization of the actin network. Despite distinct treadmilling mechanisms of ADP- and ATP-actin filaments, their filament structures are nearly identical. How other actin-binding proteins regulate ADP-actin filament assembly is unclear. Here, we show that Spa2 which is the polarisome scaffold protein specifically remodels ADP-actin upon energy starvation in budding yeast. Spa2 triggers ADP-actin monomer nucleation rapidly through a dimeric core of Spa2 (aa 281-535). Concurrently, the intrinsically disordered region (IDR, aa 1-281) guides Spa2 undergoing phase separation and wetting on the surface of ADP-G-actin-derived F-actin and bundles the filaments. Both ADP-actin-specific nucleation and bundling activities of Spa2 are actin D-loop dependent. The IDR and nucleation core of Spa2 are evolutionarily conserved by coexistence in the fungus kingdom, suggesting a universal adaptation mechanism in the fungal kingdom in response to glucose starvation, regulating ADP-G-actin and ADP-F-actin with high nucleotide homogeneity.


Assuntos
Actinas , Difosfato de Adenosina , Glucose , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Citoesqueleto de Actina/metabolismo , Actinas/metabolismo , Difosfato de Adenosina/metabolismo , Difosfato de Adenosina/análogos & derivados , Glucose/metabolismo , Proteínas dos Microfilamentos/metabolismo , Proteínas dos Microfilamentos/genética , Proteínas dos Microfilamentos/química , Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/química
4.
Langmuir ; 40(5): 2646-2655, 2024 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-38258382

RESUMO

The envelope (E) protein of SARS-CoV-2 participates in virion encapsulation and budding at the membrane of the endoplasmic reticulum Golgi intermediate compartment (ERGIC). The positively curved membrane topology required to fit an 80 nm viral particle is energetically unfavorable; therefore, viral proteins must facilitate ERGIC membrane curvature alteration. To study the possible role of the E protein in this mechanism, we examined the structural modification of the host lipid membrane by the SARS-CoV-2 E protein using synchrotron-based X-ray methods. Our reflectometry results on solid-supported planar bilayers show that E protein markedly condenses the surrounding lipid bilayer. For vesicles, this condensation effect differs between the two leaflets such that the membrane becomes asymmetric and increases its curvature. The formation of such a curved and condensed membrane is consistent with the requirements to stably encapsulate a viral core and supports a role for E protein in budding during SARS-CoV-2 virion assembly.


Assuntos
COVID-19 , SARS-CoV-2 , Humanos , SARS-CoV-2/metabolismo , Montagem de Vírus , Proteínas Virais , Proteínas do Envelope Viral/química
5.
Int J Mol Sci ; 24(23)2023 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-38069132

RESUMO

Bacillus thuringiensis (Bt) strains produce pore-forming toxins (PFTs) that attack insect pests. Information for pre-pore and pore structures of some of these Bt toxins is available. However, for the three-domain (I-III) crystal (Cry) toxins, the most used Bt toxins in pest control, this crucial information is still missing. In these Cry toxins, biochemical data have shown that 7-helix domain I is involved in insertion in membranes, oligomerization and formation of a channel lined mainly by helix α4, whereas helices α1 to α3 seem to have a dynamic role during insertion. In the case of Cry1Aa, toxic against Manduca sexta larvae, a tetrameric oligomer seems to precede membrane insertion. Given the experimental difficulty in the elucidation of the membrane insertion steps, we used Alphafold-2 (AF2) to shed light on possible oligomeric structural intermediates in the membrane insertion of this toxin. AF2 very accurately (<1 Å RMSD) predicted the crystal monomeric and trimeric structures of Cry1Aa and Cry4Ba. The prediction of a tetramer of Cry1Aa, but not Cry4Ba, produced an 'extended model' where domain I helices α3 and α2b form a continuous helix and where hydrophobic helices α1 and α2 cluster at the tip of the bundle. We hypothesize that this represents an intermediate that binds the membrane and precedes α4/α5 hairpin insertion, together with helices α6 and α7. Another Cry1Aa tetrameric model was predicted after deleting helices α1 to α3, where domain I produced a central cavity consistent with an ion channel, lined by polar and charged residues in helix α4. We propose that this second model corresponds to the 'membrane-inserted' structure. AF2 also predicted larger α4/α5 hairpin n-mers (14 ≤n ≤ 17) with high confidence, which formed even larger (~5 nm) pores. The plausibility of these models is discussed in the context of available experimental data and current paradigms.


Assuntos
Toxinas de Bacillus thuringiensis , Bacillus thuringiensis , Animais , Furilfuramida/metabolismo , Endotoxinas/toxicidade , Proteínas Hemolisinas/metabolismo , Bacillus thuringiensis/química , Proteínas de Bactérias/metabolismo , Larva
6.
Int J Mol Sci ; 24(15)2023 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-37569828

RESUMO

The envelope (E) protein is a small polypeptide that can form ion channels in coronaviruses. In SARS coronavirus 2 (SARS-CoV-2), the agent that caused the recent COVID-19 pandemic, and its predecessor SARS-CoV-1, E protein is found in the endoplasmic reticulum-Golgi intermediate compartment (ERGIC), where virion budding takes place. Several reports claim that E protein promotes the formation of "cation-selective channels". However, whether this term represents specificity to certain ions (e.g., potassium or calcium) or the partial or total exclusion of anions is debatable. Herein, we discuss this claim based on the available data for SARS-CoV-1 and -2 E and on new experiments performed using the untagged full-length E protein from SARS-CoV-2 in planar lipid membranes of different types, including those that closely mimic the ERGIC membrane composition. We provide evidence that the selectivity of the E-induced channels is very mild and depends strongly on lipid environment. Thus, despite past and recent claims, we found no indication that the E protein forms cation-selective channels that prevent anion transport, and even less that E protein forms bona fide specific calcium channels. In fact, the E channel maintains its multi-ionic non-specific neutral character even in concentrated solutions of Ca2+ ions. Also, in contrast to previous studies, we found no evidence that SARS-CoV-2 E channel activation requires a particular voltage, high calcium concentrations or low pH, in agreement with available data from SARS-CoV-1 E. In addition, sedimentation velocity experiments suggest that the E channel population is mostly pentameric, but very dynamic and probably heterogeneous, consistent with the broad distribution of conductance values typically found in electrophysiological experiments. The latter has been explained by the presence of proteolipidic channel structures.


Assuntos
COVID-19 , SARS-CoV-2 , Humanos , SARS-CoV-2/metabolismo , Proteínas do Envelope Viral/química , Cálcio , Pandemias , Íons , Lipídeos
7.
Cell Rep ; 42(6): 112594, 2023 06 27.
Artigo em Inglês | MEDLINE | ID: mdl-37269287

RESUMO

Coronins play critical roles in actin network formation. The diverse functions of coronins are regulated by the structured N-terminal ß propeller and the C-terminal coiled coil (CC). However, less is known about a middle "unique region" (UR), which is an intrinsically disordered region (IDR). The UR/IDR is an evolutionarily conserved signature in the coronin family. By integrating biochemical and cell biology experiments, coarse-grained simulations, and protein engineering, we find that the IDR optimizes the biochemical activities of coronins in vivo and in vitro. The budding yeast coronin IDR plays essential roles in regulating Crn1 activity by fine-tuning CC oligomerization and maintaining Crn1 as a tetramer. The IDR-guided optimization of Crn1 oligomerization is critical for F-actin cross-linking and regulation of Arp2/3-mediated actin polymerization. The final oligomerization status and homogeneity of Crn1 are contributed by three examined factors: helix packing, the energy landscape of the CC, and the length and molecular grammar of the IDR.


Assuntos
Citoesqueleto de Actina , Actinas , Proteínas Intrinsicamente Desordenadas , Citoesqueleto de Actina/metabolismo , Actinas/metabolismo , Polimerização , Proteínas Intrinsicamente Desordenadas/metabolismo , Proteínas Intrinsicamente Desordenadas/fisiologia , Proteínas dos Microfilamentos/metabolismo , Proteínas dos Microfilamentos/fisiologia , Saccharomyces cerevisiae/genética , Humanos , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/fisiologia
8.
Sci Rep ; 13(1): 7360, 2023 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-37147499

RESUMO

The non-structural (NS) NS4A protein in flaviviruses has three predicted transmembrane domains, is critical for virulence and participates in membrane morphogenesis. In Dengue virus (DENV), both hydrophylic N-terminal tail and its first transmembrane domain participate in the formation of oligomers which are important for pathogenicity. However, the relative importance of the N-terminal domain in oligomerization has been under debate. In particular, since in the absence of detergent or lipids, this domain (residues 1-48) in both DENV and Zika virus (ZIKV) NS4A, was found to be disordered. Recently, however, we reported preliminary data that showed that peptide ZIKV NS4A 4-58 adopts a defined secondary structure in aqueous solution and forms oligomers, signaling its importance for full length NS4A oligomerization. Herein we have performed detailed analytical ultracentrifugation experiments to further characterize the oligomerization of this peptide and also a shorter variant (residues 4-44). In both cases, sedimentation velocity produced a single species with concentration-dependent sedimentation coefficient, consistent with a fast equilibrium between at least two species. Combining sedimentation velocity and equilibrium experiments, data is best fitted to a monomer-dimer-trimer equilibrium. Possible models of NS4A oligomers obtained with AlphaFold-2 predict the stabilizing role for residues in this N-terminal domain, such as Arg20, Asn27, Ala44 and Glu50, all at highly conserved positions in flavivirus NS4A proteins. Our results are thus consistent with N-terminal domain interactions acting as one of the driving forces for NS4A homo-oligomerization.


Assuntos
Vírus da Dengue , Infecção por Zika virus , Zika virus , Humanos , Zika virus/metabolismo , Detergentes/metabolismo , Vírus da Dengue/metabolismo , Proteínas não Estruturais Virais/metabolismo , Lipídeos
9.
Int J Mol Sci ; 24(9)2023 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-37175807

RESUMO

Aquaporins are tetrameric integral membrane proteins that act as water channels, and can also permeabilize membranes to other solutes. The monomer appears to be the functional form despite all aquaporins being organized as tetramers, which therefore must provide a clear functional advantage. In addition to this quaternary organization, some aquaporins can act as adhesion molecules in membrane junctions, when tetramers located in opposing membranes interact via their extracellular domains. These stacked forms have been observed in a range of aquaporins, whether using lipidic membrane environments, in electron crystallography, or using detergent micelles, in single-particle cryo-electron microscopy (cryo-EM). In the latter technique, structural studies can be performed when the aquaporin is reconstituted into nanodiscs of lipids that are surrounded by a protein scaffold. During attempts to study E. coli Aquaporin Z (AqpZ), we have found that in some conditions these nanodiscs tend to form filaments that appear to be either thicker head-to-tail or thinner side-to-side stacks of nanodiscs. Nanodisc oligomerization was observed using orthogonal analytical techniques analytical ultra-centrifugation and mass photometry, although the nature of the oligomers (head-to-tail or side-to-side) could not be determined. Using the latter technique, the AqpZ tetramer itself formed oligomers of increasing size when solubilized only in detergent, which is consistent with multiple stacking of AqpZ tetramers. We observed images consistent with both of these filaments in negative staining EM conditions, but only thicker filaments in cryo-EM conditions. We hypothesize that the apparent nanodisc side-to-side arrangement that can only be visualized in negative staining conditions is related to artifacts due to the sample preparation. Filaments of any kind were not observed in EM when nanodiscs did not contain AqpZ, or after addition of detergent into the nanodisc cryo-EM preparation, at concentrations that did not disrupt nanodisc formation. To our knowledge, these filaments have not been observed in nanodiscs preparations of other membrane proteins. AqpZ, like other aquaporins has a charge asymmetry between the cytoplasmic (more positive) and the extracellular sides, which may explain the likely head-to-tail stacking observed, both in nanodisc preparations and also in detergent micelles.


Assuntos
Aquaporinas , Proteínas de Escherichia coli , Nanoestruturas , Escherichia coli/metabolismo , Detergentes/química , Microscopia Crioeletrônica , Micelas , Proteínas de Escherichia coli/metabolismo , Aquaporinas/metabolismo , Proteínas de Membrana/metabolismo , Nanoestruturas/química
10.
J Mol Biol ; 435(5): 167966, 2023 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-36682677

RESUMO

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) envelope (E) protein forms a pentameric ion channel in the lipid membrane of the endoplasmic reticulum Golgi intermediate compartment (ERGIC) of the infected cell. The cytoplasmic domain of E interacts with host proteins to cause virus pathogenicity and may also mediate virus assembly and budding. To understand the structural basis of these functions, here we investigate the conformation and dynamics of an E protein construct (residues 8-65) that encompasses the transmembrane domain and the majority of the cytoplasmic domain using solid-state NMR. 13C and 15N chemical shifts indicate that the cytoplasmic domain adopts a ß-sheet-rich conformation that contains three ß-strands separated by turns. The five subunits associate into an umbrella-shaped bundle that is attached to the transmembrane helices by a disordered loop. Water-edited NMR spectra indicate that the third ß-strand at the C terminus of the protein is well hydrated, indicating that it is at the surface of the ß-bundle. The structure of the cytoplasmic domain cannot be uniquely determined from the inter-residue correlations obtained here due to ambiguities in distinguishing intermolecular and intramolecular contacts for a compact pentameric assembly of this small domain. Instead, we present four structural topologies that are consistent with the measured inter-residue contacts. These data indicate that the cytoplasmic domain of the SARS-CoV-2 E protein has a strong propensity to adopt ß-sheet conformations when the protein is present at high concentrations in lipid bilayers. The equilibrium between the ß-strand conformation and the previously reported α-helical conformation may underlie the multiple functions of E in the host cell and in the virion.


Assuntos
SARS-CoV-2 , Humanos , Bicamadas Lipídicas/química , Modelos Moleculares , Conformação Proteica em Folha beta , SARS-CoV-2/química
11.
Virol J ; 19(1): 193, 2022 11 21.
Artigo em Inglês | MEDLINE | ID: mdl-36414943

RESUMO

A global pandemic is underway caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The SARS-CoV-2 genome, like its predecessor SARS-CoV, contains open reading frames that encode accessory proteins involved in virus-host interactions active during infection and which likely contribute to pathogenesis. One of these accessory proteins is 7b, with only 44 (SARS-CoV) and 43 (SARS-CoV-2) residues. It has one predicted transmembrane domain fully conserved, which suggests a functional role, whereas most variability is contained in the predicted cytoplasmic C-terminus. In SARS-CoV, 7b protein is expressed in infected cells, and the transmembrane domain was necessary and sufficient for Golgi localization. Also, anti-p7b antibodies have been found in the sera of SARS-CoV convalescent patients. In the present study, we have investigated the hypothesis that SARS-2 7b protein forms oligomers with ion channel activity. We show that in both SARS viruses 7b is almost completely α-helical and has a single transmembrane domain. In SDS, 7b forms various oligomers, from monomers to tetramers, but only monomers when exposed to reductants. Combination of SDS gel electrophoresis and analytical ultracentrifugation (AUC) in both equilibrium and velocity modes suggests a dimer-tetramer equilibrium, but a monomer-dimer-tetramer equilibrium in the presence of reductant. This data suggests that although disulfide-linked dimers may be present, they are not essential to form tetramers. Inclusion of pentamers or higher oligomers in the SARS-2 7b model were detrimental to fit quality. Preliminary models of this association was generated with AlphaFold2, and two alternative models were exposed to a molecular dynamics simulation in presence of a model lipid membrane. However, neither of the two models provided any evident pathway for ions. To confirm this, SARS-2 p7b was studied using Planar Bilayer Electrophysiology. Addition of p7b to model membranes produced occasional membrane permeabilization, but this was not consistent with bona fide ion channels made of a tetrameric assembly of α-helices.


Assuntos
COVID-19 , SARS-CoV-2 , Humanos , Detergentes , Fases de Leitura Aberta , Citoplasma
12.
Int J Mol Sci ; 23(21)2022 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-36362071

RESUMO

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the current COVID-19 pandemic. In SARS-CoV-2, the channel-forming envelope (E) protein is almost identical to the E protein in SARS-CoV, and both share an identical α-helical channel-forming domain. Structures for the latter are available in both detergent and lipid membranes. However, models of the extramembrane domains have only been obtained from solution NMR in detergents, and show no ß-strands, in contrast to secondary-structure predictions. Herein, we have studied the conformation of purified SARS-CoV-2 E protein in lipid bilayers that mimic the composition of ER-Golgi intermediate compartment (ERGIC) membranes. The full-length E protein at high protein-to-lipid ratios produced a clear shoulder at 1635 cm-1, consistent with the ß-structure, but this was absent when the E protein was diluted, which instead showed a band at around 1688 cm-1, usually assigned to ß-turns. The results were similar with a mixture of POPC:POPG (2-oleoyl-1-palmitoyl-sn-glycero-3-phosphocholine/3-glycerol) and also when using an E-truncated form (residues 8-65). However, the latter only showed ß-structure formation at the highest concentration tested, while having a weaker oligomerization tendency in detergents than in full-length E protein. Therefore, we conclude that E monomer-monomer interaction triggers formation of the ß-structure from an undefined structure (possibly ß-turns) in at least about 15 residues located at the C-terminal extramembrane domain. Due to its proximity to the channel, this ß-structure domain could modulate channel activity or modify membrane structure at the time of virion formation inside the cell.


Assuntos
COVID-19 , SARS-CoV-2 , Humanos , Detergentes , Pandemias , Bicamadas Lipídicas/química
13.
Diagnostics (Basel) ; 12(7)2022 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-35885517

RESUMO

The emergency of the coronavirus disease 2019 (COVID-19) pandemic led to the off-label use of drugs without data on their toxicity profiles in patients with COVID-19, or on their concomitant use. Patients included in the COVID-19 Patient Registry of a tertiary hospital during the first wave were analyzed to evaluate the adverse drug reactions (ADRs) with the selected treatments. Twenty-one percent of patients (197 out of 933) had at least one ADR, with a total of 240 ADRs. Patients with ADRs were more commonly treated with multiple drugs for COVID-19 infection than patients without ADRs (p < 0.001). They were younger (median 62 years vs. 70.1 years; p < 0.001) and took less medication regularly (69.5% vs. 75.7%; p = 0.031). The most frequent ADRs were gastrointestinal (67.1%), hepatobiliary (10.8%), and cardiac disorders (3.3%). Drugs more frequently involved included lopinavir/ritonavir (82.2%), hydroxychloroquine (72.1%), and azithromycin (66.5%). Although most ADRs recovered without sequelae, fatal cases were described, even though the role of the disease could not be completely ruled out. In similar situations, efforts should be made to use the drugs in the context of clinical trials, and to limit off-label use to those drugs with a better benefit/risk profile in specific situations and for patients at high risk of poor disease prognosis.

14.
Environ Sci Technol ; 56(8): 5179-5188, 2022 04 19.
Artigo em Inglês | MEDLINE | ID: mdl-35349264

RESUMO

The water channel feature of the aquaporin (AQP) is considered to be the key in improving the permselectivity of AQP-based thin-film composite (TFC) polyamide (PA) membranes, yet much less attention has been paid to the physicochemical property changes of the PA layer induced by AQP-reconstituted proteoliposomes. This study systematically investigated the roles of proteoliposome constituents (liposome/detergent/AQP) in affecting the physicochemical properties and performance of the membranes. For the first time, we demonstrated that the constituents in the proteoliposome could facilitate the formation of a PA layer with enlarged protuberances and thinner crumples, resulting in a 79% increase in effective surface area and lowering of hydraulic resistance for filtration. These PA structural changes of the AQP-based membrane were found to contribute over 70% to the water permeability increase via comparing the separation performance of the membranes prepared with liposome, detergent, and proteoliposome, respectively, and one proteoliposome-ruptured membrane. The contribution from the AQP water channel feature was about 27% of water permeability increase in the current study, attributed to only ∼20% vesicle coverage in the PA matrix, and this contribution may be easily lost as a result of vesicle rupture during the real seawater reverse osmosis process. This study reveals that the changed morphology dominates the performance improvement of the AQP-based PA membrane and well explains why the actual AQP-based PA membranes cannot acquire the theoretical water/salt selectivity of a biomimetic AQP membrane, deepening our understanding of the AQP-based membranes.


Assuntos
Aquaporinas , Nylons , Aquaporinas/química , Detergentes , Lipossomos/química , Membranas Artificiais , Nylons/química , Osmose , Proteolipídeos , Água do Mar/química , Água/química
15.
Clin Nucl Med ; 47(5): 387-393, 2022 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-35234202

RESUMO

BACKGROUND: Two clinical subsets of giant cell arteritis have been identified with different histological and CT findings. However, PET/CT findings have not been compared with temporal artery biopsy (TAB). OBJECTIVE: The aims of this study were to describe clinical and histological findings in patients with giant cell arteritis according to the presence or absence of aortitis in PET/CT at the disease diagnosis, and to identify independent factors related to aortic involvement. METHODS: Patients were included and followed prospectively. Clinical symptoms and TAB findings were recorded. PET/CT was performed in the first 10 days of steroid therapy. Aortitis was defined if a grade 3 uptake on visual analysis was present on arterial wall. Clinical and histological variables were compared according to the presence or absence of aortitis on PET/CT. Multivariate analysis was performed to identify independent factors related to the presence of aortitis. RESULTS: Twenty-seven patients (median age, 77.6 years) were included. PET/CT was performed with a median delay of 5.0 days. Aortitis was observed in 8 patients. Patients with aortitis were younger (69.9 vs 83.7 years, P = 0.04) and had less frequently ischemic manifestations (25.0% vs 84.2%, P = 0.006) than patients without aortitis. Giant multinucleated cells were more frequent on TAB from patients with aortitis (71.4% vs 16.7%), and its presence was an independent risk factor for the occurrence of aortic involvement on PET/CT (odds ratio, 12.2; P = 0.046). CONCLUSIONS: Our study shows that giant cells on TAB are associated with the presence of aortitis on PET/CT. Patients with aortic involvement are younger and show less frequently ischemic manifestations.


Assuntos
Aortite , Arterite de Células Gigantes , Idoso , Biópsia/efeitos adversos , Arterite de Células Gigantes/complicações , Arterite de Células Gigantes/diagnóstico por imagem , Humanos , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/efeitos adversos , Artérias Temporais/diagnóstico por imagem , Artérias Temporais/patologia
16.
Med. clín (Ed. impr.) ; 158(4): 181-185, febrero 2022.
Artigo em Espanhol | IBECS | ID: ibc-204345

RESUMO

El síndrome de Sjögren es una enfermedad autoinmune que afecta a las glándulas exocrinas. Su sintomatología característica es el síndrome seco en forma de xeroftalmia y xerostomía, pero puede afectar a diversos órganos o sistemas y la afectación extraglandular es la que condiciona el pronóstico de la enfermedad. Típicamente se asocia con la presencia de anticuerpos antinucleares, que incluyen anti-Ro-60. La afectación pulmonar aparece en forma de bronquiectasias y/o neumopatía intersticial. Dada la alta prevalencia de esta complicación, su presencia debe descartarse en todos los pacientes con síntomas respiratorios mediante pruebas de función respiratoria y tomografía computarizada de alta resolución torácica. Se puede completar la valoración mediante biopsia transbronquial en aquellos casos en que existan dudas diagnósticas. El tratamiento incluye glucocorticoterapia, terapia inmunosupresora o antifibrótica, y terapia biológica. En caso de mala evolución se debe valorar el trasplante pulmonar.


Sjögren's syndrome is an autoimmune disease that involves exocrine glands. The most characteristic symptoms consist of the sicca syndrome (including xerostomia and dry eye – xerophtalmia), but can involve multiple organs. The extraglandular involvement determines the prognosis. It is typically associated with the presence of antinuclear antibodies, including Ro-60 antibodies. Pulmonary involvement appears as bronchiectasis and/or interstitial pneumonia. Considering its high prevalence, it must be ruled out in all patients with respiratory symptoms by performing pulmonary function tests and high-resolution computed tomography of the chest. Evaluation can be completed with a transbronchial biopsy if diagnostic doubts persist. Treatment includes steroid therapy, inmunosupressive or antifibrotic drugs, or biological therapy. In selected cases pulmonary transplantation must be considered. (AU)


Assuntos
Humanos , Síndrome de Sjogren , Doenças Pulmonares Intersticiais/diagnóstico , Doenças Pulmonares Intersticiais/etiologia , Xerostomia , Pulmão/diagnóstico por imagem
17.
Med Clin (Barc) ; 158(4): 181-185, 2022 02 25.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-34392987

RESUMO

Sjögren's syndrome is an autoimmune disease that involves exocrine glands. The most characteristic symptoms consist of the sicca syndrome (including xerostomia and dry eye - xerophtalmia), but can involve multiple organs. The extraglandular involvement determines the prognosis. It is typically associated with the presence of antinuclear antibodies, including Ro-60 antibodies. Pulmonary involvement appears as bronchiectasis and/or interstitial pneumonia. Considering its high prevalence, it must be ruled out in all patients with respiratory symptoms by performing pulmonary function tests and high-resolution computed tomography of the chest. Evaluation can be completed with a transbronchial biopsy if diagnostic doubts persist. Treatment includes steroid therapy, inmunosupressive or antifibrotic drugs, or biological therapy. In selected cases pulmonary transplantation must be considered.


Assuntos
Doenças Pulmonares Intersticiais , Síndrome de Sjogren , Xerostomia , Humanos , Pulmão/diagnóstico por imagem , Doenças Pulmonares Intersticiais/diagnóstico , Doenças Pulmonares Intersticiais/etiologia , Testes de Função Respiratória , Síndrome de Sjogren/complicações , Síndrome de Sjogren/diagnóstico
18.
Membranes (Basel) ; 11(5)2021 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-33946585

RESUMO

The nonstructural (NS) protein NS4A in flaviviruses is a membrane protein that is critical for virulence, and, among other roles, it participates in membrane morphogenesis. In dengue virus (DENV), the NS4A hydrophilic N-terminal tail, together with the first transmembrane domain, is involved in both homo-oligomerization and hetero-oligomerization with NS4B. In both DENV and Zika virus (ZIKV), this N-terminal tail (residues 1-48) forms a random coil in solution but becomes mostly α-helical upon interaction with detergents or lipid membranes. Herein, we show that a peptide from ZIKV NS4A that spans residues 4-58, which includes most of the N-terminal tail and a third of its first transmembrane domain, forms homotrimers in the absence of detergents or liposomes. After interaction with the latter, α-helical content increases, consistent with binding. The oligomeric size of NS4A is not known, as it has only been reported in SDS gels. Therefore, we propose that full-length NS4A forms homotrimers mediated by this region, and that disruption of the oligomerization of peptide ZIKV NS4A 4-58 in solution can potentially constitute the basis for an in vitro assay to discover antivirals.

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