Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 56
Filtrar
Mais filtros








Base de dados
Intervalo de ano de publicação
1.
Mol Clin Oncol ; 19(1): 52, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37303973

RESUMO

Trastuzumab and pertuzumab with taxane-based chemotherapy are considered the first-line standard therapy for human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (mBC). Pertuzumab is also a later-line therapy for mBC in Switzerland, although limited safety and efficacy data are available. The present study assessed the therapeutic regimens, toxicities and clinical outcomes after second- or later-line pertuzumab therapy in patients with mBC who did not receive pertuzumab as a first-line therapy. Physicians from nine major Swiss oncology centers retrospectively completed a questionnaire for each pertuzumab-naive patient who was treated with pertuzumab as a second- or later-line therapy. Of 35 patients with HER2-positive mBC (median age, 49 years; range, 35-87 years), 14 received pertuzumab as a second-line therapy, 6 as a third-line therapy, and 15 as a fourth- or later-line therapy. A total of 20 patients (57%) died during the study period. The median overall survival was 74.2 months (95% confidence interval, 47.6-139.8 months). Grade (G) 3/4 adverse events (AEs) were reported in 14% of patients, with only 1 patient discontinuing therapy due to pertuzumab-related toxicities. The most common AE was fatigue (overall, 46%; G3, 11%). Overall, congestive heart disease occurred in 14% of patients (G3, 6%), nausea in 14% of patients (all G1), and myelosuppression in 12% of patients (G3, 6%). In conclusion, the median overall survival of patients who underwent second- or later-line pertuzumab treatment was similar to that reported for patients who underwent first-line pertuzumab treatment, and the safety profile was acceptable. These data support the use of pertuzumab for second- or later-line therapy when it was not administered as first-line therapy.

2.
FEBS J ; 290(16): 4057-4073, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37042241

RESUMO

Acyl-coenzyme A thioesterase (Acot) enzymes are involved in a broad range of essential intracellular roles including cell signalling, lipid metabolism, inflammation and the opening of ion channels. Dysregulation in lipid metabolism has been linked to neuroinflammatory and neurological disorders such as Alzheimer's and Parkinson's diseases. Structurally, Acot enzymes adopt a circularised trimeric arrangement with each monomer containing an N- and a C-terminal hotdog domain. Acot7 spontaneously forms amyloid fibrils in vitro under physiological conditions. The resultant amyloid fibrillar structures were characterised by dye-binding fluorescence assays, far-UV circular dichroism spectroscopy, transmission electron microscopy and X-ray fibre diffraction. Acot7 has an unusual mechanism of aggregation with no lag phase. The initial phase (~ 18 h) of aggregation involves conformational rearrangement within the oligomers to form species of enhanced ß-sheet character. The subsequent loss of α-helical structure is accompanied by large-scale amyloid fibril formation. The crystal structure of Acot7 revealed an unexpected arrangement of the two domains within the circularised trimeric structure, which is the basis for a proposed mechanism of amyloid fibril formation involving domain swapping during the initial phase of aggregation. Acot7 formed fibrils in the presence of its substrate arachidonoyl-CoA and its inhibitors and maintained its enzyme activity during fibril assembly. It is proposed that the Acot7 fibrillar form acts as functional amyloid.


Assuntos
Amiloide , Doença de Parkinson , Humanos , Amiloide/química , Difração de Raios X , Microscopia Eletrônica de Transmissão , Inflamação , Dicroísmo Circular
3.
Metabolites ; 13(2)2023 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-36837806

RESUMO

Redox homeostasis is a delicate balancing act of maintaining appropriate levels of antioxidant defense mechanisms and reactive oxidizing oxygen and nitrogen species. Any disruption of this balance leads to oxidative stress, which is a key pathogenic factor in several ocular diseases. In this review, we present the current evidence for oxidative stress and mitochondrial dysfunction in conditions affecting both the anterior segment (e.g., dry eye disease, keratoconus, cataract) and posterior segment (age-related macular degeneration, proliferative vitreoretinopathy, diabetic retinopathy, glaucoma) of the human eye. We posit that further development of therapeutic interventions to promote pro-regenerative responses and maintenance of the redox balance may delay or prevent the progression of these major ocular pathologies. Continued efforts in this field will not only yield a better understanding of the molecular mechanisms underlying the pathogenesis of ocular diseases but also enable the identification of novel druggable redox targets and antioxidant therapies.

4.
Biochim Biophys Acta Proteins Proteom ; 1870(11-12): 140854, 2022 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-36087849

RESUMO

Caseins are a diverse family of intrinsically disordered proteins present in the milks of all mammals. A property common to two cow paralogues, αS2- and κ-casein, is their propensity in vitro to form amyloid fibrils, the highly ordered protein aggregates associated with many age-related, including neurological, diseases. In this study, we explored whether amyloid fibril-forming propensity is a general feature of casein proteins by examining the other cow caseins (αS1 and ß) as well as ß-caseins from camel and goat. Small-angle X-ray scattering measurements indicated that cow αS1- and ß-casein formed large spherical aggregates at neutral pH and 20°C. Upon incubation at 65°C, αS1- and ß-casein underwent conversion to amyloid fibrils over the course of ten days, as shown by thioflavin T binding, transmission electron microscopy, and X-ray fibre diffraction. At the lower temperature of 37°C where fibril formation was more limited, camel ß-casein exhibited a greater fibril-forming propensity than its cow or goat orthologues. Limited proteolysis of cow and camel ß-casein fibrils and analysis by mass spectrometry indicated a common amyloidogenic sequence in the proline, glutamine-rich, C-terminal region of ß-casein. These findings highlight the persistence of amyloidogenic sequences within caseins, which likely contribute to their functional, heterotypic self-assembly; in all mammalian milks, at least two caseins coalesce to form casein micelles, implying that caseins diversified partly to avoid dysfunctional amyloid fibril formation.


Assuntos
Caseínas , Proteínas Intrinsicamente Desordenadas , Amiloide/química , Animais , Camelus/metabolismo , Bovinos , Feminino , Glutamina , Cabras/metabolismo , Micelas , Prolina , Agregados Proteicos
5.
Elife ; 112022 06 20.
Artigo em Inglês | MEDLINE | ID: mdl-35723573

RESUMO

Cataract is one of the most prevalent protein aggregation disorders and still the most common cause of vision loss worldwide. The metabolically quiescent core region of the human lens lacks cellular or protein turnover; it has therefore evolved remarkable mechanisms to resist light-scattering protein aggregation for a lifetime. We now report that one such mechanism involves an unusually abundant lens metabolite, myo-inositol, suppressing aggregation of lens crystallins. We quantified aggregation suppression using our previously well-characterized in vitro aggregation assays of oxidation-mimicking human γD-crystallin variants and investigated myo-inositol's molecular mechanism of action using solution NMR, negative-stain TEM, differential scanning fluorometry, thermal scanning Raman spectroscopy, turbidimetry in redox buffers, and free thiol quantitation. Unlike many known chemical chaperones, myo-inositol's primary target was not the native, unfolded, or final aggregated states of the protein; rather, we propose that it was the rate-limiting bimolecular step on the aggregation pathway. Given recent metabolomic evidence that it is severely depleted in human cataractous lenses compared to age-matched controls, we suggest that maintaining or restoring healthy levels of myo-inositol in the lens may be a simple, safe, and globally accessible strategy to prevent or delay lens opacification due to age-onset cataract.


Assuntos
Catarata , Cristalino , Catarata/metabolismo , Humanos , Inositol/análise , Inositol/metabolismo , Cristalino/metabolismo , Chaperonas Moleculares/metabolismo , Agregados Proteicos
6.
Metab Brain Dis ; 37(1): 105-121, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34347208

RESUMO

Neurological disease and disorders remain a large public health threat. Thus, research to improve early detection and/or develop more effective treatment approaches are necessary. Although there are many common techniques and imaging modalities utilized to study these diseases, existing approaches often require a label which can be costly and time consuming. Matrix-assisted laser desorption ionization (MALDI) imaging mass spectrometry (IMS) is a label-free, innovative and emerging technique that produces 2D ion density maps representing the distribution of an analyte(s) across a tissue section in relation to tissue histopathology. One main advantage of MALDI IMS over other imaging modalities is its ability to determine the spatial distribution of hundreds of analytes within a single imaging run, without the need for a label or any a priori knowledge. Within the field of neurology and disease there have been several impactful studies in which MALDI IMS has been utilized to better understand the cellular pathology of the disease and or severity. Furthermore, MALDI IMS has made it possible to map specific classes of analytes to regions of the brain that otherwise may have been lost using more traditional methods. This review will highlight key studies that demonstrate the potential of this technology to elucidate previously unknown phenomenon in neurological disease.


Assuntos
Encéfalo , Neurologia , Encéfalo/diagnóstico por imagem , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos
7.
Molecules ; 26(20)2021 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-34684701

RESUMO

14-3-3 proteins are abundant, intramolecular proteins that play a pivotal role in cellular signal transduction by interacting with phosphorylated ligands. In addition, they are molecular chaperones that prevent protein unfolding and aggregation under cellular stress conditions in a similar manner to the unrelated small heat-shock proteins. In vivo, amyloid ß (Aß) and α-synuclein (α-syn) form amyloid fibrils in Alzheimer's and Parkinson's diseases, respectively, a process that is intimately linked to the diseases' progression. The 14-3-3ζ isoform potently inhibited in vitro fibril formation of the 40-amino acid form of Aß (Aß40) but had little effect on α-syn aggregation. Solution-phase NMR spectroscopy of 15N-labeled Aß40 and A53T α-syn determined that unlabeled 14-3-3ζ interacted preferentially with hydrophobic regions of Aß40 (L11-H21 and G29-V40) and α-syn (V3-K10 and V40-K60). In both proteins, these regions adopt ß-strands within the core of the amyloid fibrils prepared in vitro as well as those isolated from the inclusions of diseased individuals. The interaction with 14-3-3ζ is transient and occurs at the early stages of the fibrillar aggregation pathway to maintain the native, monomeric, and unfolded structure of Aß40 and α-syn. The N-terminal regions of α-syn interacting with 14-3-3ζ correspond with those that interact with other molecular chaperones as monitored by in-cell NMR spectroscopy.


Assuntos
Proteínas 14-3-3/metabolismo , Peptídeos beta-Amiloides/metabolismo , alfa-Sinucleína/metabolismo , Proteínas 14-3-3/fisiologia , Amiloide/metabolismo , Amiloide/fisiologia , Peptídeos beta-Amiloides/fisiologia , Humanos , Chaperonas Moleculares/fisiologia , Agregados Proteicos , Ligação Proteica/fisiologia , Conformação Proteica , Conformação Proteica em Folha beta , Domínios e Motivos de Interação entre Proteínas/fisiologia , Desdobramento de Proteína , alfa-Sinucleína/fisiologia
8.
Exp Eye Res ; 211: 108707, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34332989

RESUMO

The nuclear region of the lens is metabolically quiescent, but it is far from inert chemically. Without cellular renewal and with decades of environmental exposures, the lens proteome, lipidome, and metabolome change. The lens crystallins have evolved exquisite mechanisms for resisting, slowing, adapting to, and perhaps even harnessing the effects of these cumulative chemical modifications to minimize the amount of light-scattering aggregation in the lens over a lifetime. Redox chemistry is a major factor in these damages and mitigating adaptations, and as such, it is likely to be a key component of any successful therapeutic strategy for preserving or rescuing lens transparency, and perhaps flexibility, during aging. Protein redox chemistry is typically mediated by Cys residues. This review will therefore focus primarily on the Cys-rich γ-crystallins of the human lens, taking care to extend these findings to the ß- and α-crystallins where pertinent.


Assuntos
Cisteína/metabolismo , Cristalino/metabolismo , gama-Cristalinas/metabolismo , Envelhecimento/fisiologia , Dissulfetos/metabolismo , Glutationa/metabolismo , Dissulfeto de Glutationa/metabolismo , Humanos , Oxirredução , Compostos de Sulfidrila/metabolismo
10.
Ther Umsch ; 78(3): 136-144, 2021 Apr.
Artigo em Alemão | MEDLINE | ID: mdl-33775135

RESUMO

Outpatient breast cancer treatment after the hospital: what's next? - Adjuvant medical therapies, management of side effects and common fears, planing and coordination of optimal follow-up care in view of current guidelines Abstract. Following successful breast cancer surgery patients will generally be facing a certain prolonged period of medical treatment accompanied by several years of follow-up care, usually in the setting of a private practice or outpatient clinic. These medical treatments, which have proven by evidence to substantially reduce the risk of breast cancer recurrence and thereby significantly added to the boost in overall prognosis of this disease, are discussed in the light of current international treatment guidelines in this article. The standard approach to modern medical therapies is outlined on the basis of clinical pathological risk factors and tumor biology for different breast cancer subtypes (e. g. luminal, HER2-positiv, triple negativ / basal-like) accordingly. We hereby focus particularly upon the management of therapy-induced side effects, typical substance-specific toxicities as well as offering remedy to common fears and myths concerning medical breast cancer treatment. Last but not least we describe our perspective of the "ideal outpatient follow-up care", outlining a time-plan, implementing interdisciplinary expertise and stressing the necessity for good teamwork and interaction among all health care specialists involved, to optimise patient comfort and outcome.


Assuntos
Neoplasias da Mama , Assistência ao Convalescente , Neoplasias da Mama/tratamento farmacológico , Medo , Hospitais , Humanos , Recidiva Local de Neoplasia/terapia , Pacientes Ambulatoriais
11.
Biophys Chem ; 270: 106530, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33545456

RESUMO

Bovine milk αS2-casein, an intrinsically disordered protein, readily forms amyloid fibrils in vitro and is implicated in the formation of amyloid fibril deposits in mammary tissue. Its two cysteine residues participate in the formation of either intra- or intermolecular disulphide bonds, generating monomer and dimer species. X-ray solution scattering measurements indicated that both forms of the protein adopt large, spherical oligomers at 20 °C. Upon incubation at 37 °C, the disulphide-linked dimer showed a significantly greater propensity to form amyloid fibrils than its monomeric counterpart. Thioflavin T fluorescence, circular dichroism and infrared spectra were consistent with one or both of the dimer isomers (in a parallel or antiparallel arrangement) being predisposed toward an ordered, amyloid-like structure. Limited proteolysis experiments indicated that the region from Ala81 to Lys113 is incorporated into the fibril core, implying that this region, which is predicted by several algorithms to be amyloidogenic, initiates fibril formation of αS2-casein. The partial conservation of the cysteine motif and the frequent occurrence of disulphide-linked dimers in mammalian milks despite the associated risk of mammary amyloidosis, suggest that the dimeric conformation of αS2-casein is a functional, yet amyloidogenic, structure.


Assuntos
Amiloide/química , Caseínas/química , Multimerização Proteica , Amiloide/ultraestrutura , Animais , Caseínas/ultraestrutura , Bovinos , Cisteína/análise , Dissulfetos/análise , Leite/química
12.
J Mol Biol ; 432(20): 5593-5613, 2020 09 18.
Artigo em Inglês | MEDLINE | ID: mdl-32827531

RESUMO

One of the most crowded biological environments is the eye lens which contains a high concentration of crystallin proteins. The molecular chaperones αB-crystallin (αBc) with its lens partner αA-crystallin (αAc) prevent deleterious crystallin aggregation and cataract formation. However, some forms of cataract are associated with structural alteration and dysfunction of αBc. While many studies have investigated the structure and function of αBc under dilute in vitro conditions, the effect of crowding on these aspects is not well understood despite its in vivo relevance. The structure and chaperone ability of αBc under conditions that mimic the crowded lens environment were investigated using the polysaccharide Ficoll 400 and bovine γ-crystallin as crowding agents and a variety of biophysical methods, principally contrast variation small-angle neutron scattering. Under crowding conditions, αBc unfolds, increases its size/oligomeric state, decreases its thermal stability and chaperone ability, and forms kinetically distinct amorphous and fibrillar aggregates. However, the presence of αAc stabilizes αBc against aggregation. These observations provide a rationale, at the molecular level, for the aggregation of αBc in the crowded lens, a process that exhibits structural and functional similarities to the aggregation of cataract-associated αBc mutants R120G and D109A under dilute conditions. Strategies that maintain or restore αBc stability, as αAc does, may provide therapeutic avenues for the treatment of cataract.


Assuntos
Cristalino/metabolismo , Agregação Patológica de Proteínas/metabolismo , Cadeia A de alfa-Cristalina/química , Cadeia B de alfa-Cristalina/química , Cadeia B de alfa-Cristalina/metabolismo , alfa-Cristalinas/metabolismo , Animais , Catarata/metabolismo , Bovinos , Chaperonas Moleculares/metabolismo , Conformação Proteica , Cadeia A de alfa-Cristalina/metabolismo , gama-Cristalinas/metabolismo
13.
Protein Sci ; 29(9): 1945-1963, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32697405

RESUMO

Age-related lens cataract is the major cause of blindness worldwide. The mechanisms whereby crystallins, the predominant lens proteins, assemble into large aggregates that scatter light within the lens, and cause cataract, are poorly understood. Due to the lack of protein turnover in the lens, crystallins are long-lived. A major crystallin, γS, is heavily modified by deamidation, in particular at surface-exposed N14, N76, and N143 to introduce negative charges. In this present study, deamidated γS was mimicked by mutation with aspartate at these sites and the effect on biophysical properties of γS was assessed via dynamic light scattering, chemical and thermal denaturation, hydrogen-deuterium exchange, and susceptibility to disulfide cross-linking. Compared with wild type γS, a small population of each deamidated mutant aggregated rapidly into large, light-scattering species that contributed significantly to the total scattering. Under partially denaturing conditions in guanidine hydrochloride or elevated temperature, deamidation led to more rapid unfolding and aggregation and increased susceptibility to oxidation. The triple mutant was further destabilized, suggesting that the effects of deamidation were cumulative. Molecular dynamics simulations predicted that deamidation augments the conformational dynamics of γS. We suggest that these perturbations disrupt the native disulfide arrangement of γS and promote the formation of disulfide-linked aggregates. The lens-specific chaperone αA-crystallin was poor at preventing the aggregation of the triple mutant. It is concluded that surface deamidations cause minimal structural disruption individually, but cumulatively they progressively destabilize γS-crystallin leading to unfolding and aggregation, as occurs in aged and cataractous lenses.


Assuntos
Cristalino/química , Agregados Proteicos , Desdobramento de Proteína , gama-Cristalinas/química , Desaminação , Humanos
14.
J Mol Biol ; 431(3): 483-497, 2019 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-30552875

RESUMO

The reducing environment in the eye lens diminishes with age, leading to significant oxidative stress. Oxidation of lens crystallin proteins is the major contributor to their destabilization and deleterious aggregation that scatters visible light, obscures vision, and ultimately leads to cataract. However, the molecular basis for oxidation-induced aggregation is unknown. Using X-ray crystallography and small-angle X-ray scattering, we describe the structure of a disulfide-linked dimer of human γS-crystallin that was obtained via oxidation of C24. The γS-crystallin dimer is stable at glutathione concentrations comparable to those in aged and cataractous lenses. Moreover, dimerization of γS-crystallin significantly increases the protein's propensity to form large insoluble aggregates owing to non-cooperative domain unfolding, as is observed in crystallin variants associated with early-onset cataract. These findings provide insight into how oxidative modification of crystallins contributes to cataract and imply that early-onset and age-related forms of the disease share comparable development pathways.


Assuntos
Catarata/metabolismo , Dissulfetos/química , Dissulfetos/metabolismo , Cristalino/metabolismo , gama-Cristalinas/química , gama-Cristalinas/metabolismo , Cristalografia por Raios X/métodos , Dimerização , Humanos , Oxirredução , Estresse Oxidativo/fisiologia , Ligação Proteica , Conformação Proteica
15.
Acc Chem Res ; 51(3): 745-752, 2018 03 20.
Artigo em Inglês | MEDLINE | ID: mdl-29442498

RESUMO

Molecular chaperone proteins perform a diversity of roles inside and outside the cell. One of the most important is the stabilization of misfolding proteins to prevent their aggregation, a process that is potentially detrimental to cell viability. Diseases such as Alzheimer's, Parkinson's, and cataract are characterized by the accumulation of protein aggregates. In vivo, many proteins are metastable and therefore under mild destabilizing conditions have an inherent tendency to misfold, aggregate, and hence lose functionality. As a result, protein levels are tightly regulated inside and outside the cell. Protein homeostasis, or proteostasis, describes the network of biological pathways that ensures the proteome remains folded and functional. Proteostasis is a major factor in maintaining cell, tissue, and organismal viability. We have extensively investigated the structure and function of intra- and extracellular molecular chaperones that operate in an ATP-independent manner to stabilize proteins and prevent their misfolding and subsequent aggregation into amorphous particles or highly ordered amyloid fibrils. These types of chaperones are therefore crucial in maintaining proteostasis under normal and stress (e.g., elevated temperature) conditions. Despite their lack of sequence similarity, they exhibit many common features, i.e., extensive structural disorder, dynamism, malleability, heterogeneity, oligomerization, and similar mechanisms of chaperone action. In this Account, we concentrate on the chaperone roles of α-crystallins and caseins, the predominant proteins in the eye lens and milk, respectively. Intracellularly, the principal ATP-independent chaperones are the small heat-shock proteins (sHsps). In vivo, sHsps are the first line of defense in preventing intracellular protein aggregation. The lens proteins αA- and αB-crystallin are sHsps. They play a crucial role in maintaining solubility of the crystallins (including themselves) with age and hence in lens proteostasis and, ultimately, lens transparency. As there is little metabolic activity and no protein turnover in the lens, crystallins are very long lived proteins. Lens proteostasis is therefore very different to that in normal, metabolically active cells. Crystallins undergo extensive post-translational modification (PTM), including deamidation, racemization, phosphorylation, and truncation, which can alter their stability. Despite this, the lens remains transparent for tens of years, implying that lens proteostasis is intimately integrated with crystallin PTMs. Many PTMs do not significantly alter crystallin stability, solubility, and functionality, which thereby facilitates lens transparency. In the long term, however, extensive accumulation of crystallin PTMs leads to large-scale crystallin aggregation, lens opacification, and cataract formation. Extracellularly, various ATP-independent molecular chaperones exist that exhibit sHsp-like structural and functional features. For example, caseins, the major milk proteins, exhibit chaperone ability by inhibiting the amorphous and amyloid fibrillar aggregation of a diversity of destabilized proteins. Caseins maintain proteostasis within milk by preventing deleterious casein amyloid fibril formation via incorporation of thousands of individual caseins into an amorphous structure known as the casein micelle. Hundreds of nanoclusters of calcium phosphate are sequestered within each casein micelle through interactions with short, highly phosphorylated casein sequences. This results in a stable biofluid that contains a high concentration of potentially amyloidogenic caseins and concentrations of calcium and phosphate that can be far in excess of the solubility of calcium phosphate. Casein micelle formation therefore performs vital roles in neonatal nutrition and calcium homeostasis in the mammary gland.


Assuntos
Trifosfato de Adenosina/metabolismo , Caseínas/metabolismo , Chaperonas Moleculares/metabolismo , Proteostase , alfa-Cristalinas/metabolismo , Trifosfato de Adenosina/química , Animais , Caseínas/química , Humanos , Cristalino/química , Leite/química , Chaperonas Moleculares/química , Agregados Proteicos , alfa-Cristalinas/química
16.
Biomol NMR Assign ; 12(1): 69-77, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29030803

RESUMO

Class A ß-lactamases have been widely used as versatile scaffolds to create hybrid (or chimeric) proteins for a series of applications ranging from basic research to medicine. We have, in particular, used the ß-lactamase BlaP from Bacillus licheniformis 749/C (BlaP) as a protein scaffold to create model polyglutamine (polyQ) proteins in order to better understand the mechanism(s) by which an expanded polyQ sequence triggers the formation of amyloid fibrils. The model chimeras were designed by inserting a polyQ sequence of various lengths at two different locations within BlaP (i.e. position 197 or position 216) allowing a detailed comparison of the effects of subtle differences in the environment of the polyQ sequence on its ability to trigger protein aggregation. In order to investigate the effects of the polyQ insertion at both positions on the structure, stability and dynamics of BlaP, a series of NMR experiments including H/D exchange are foreseen. Accordingly, as necessitated by these studies, here we report the NMR assignment of the wild-type BlaP (BlaP-WT) and of the two reference proteins, BlaP197Q0 and BlaP216Q0, wherein a Pro-Gly dipeptide has been introduced at position 197 and 216, respectively; this dipeptide originates from the addition of the Sma1 restriction site at the genetic level to allow further polyQ sequence insertion.


Assuntos
Bacillus licheniformis/enzimologia , Proteínas Mutantes/química , Mutação , beta-Lactamases/química , Proteínas Mutantes/genética , beta-Lactamases/genética
17.
Anal Chem ; 89(17): 9322-9329, 2017 09 05.
Artigo em Inglês | MEDLINE | ID: mdl-28795815

RESUMO

Highly ordered protein aggregates, termed amyloid fibrils, are associated with a broad range of diseases, many of which are neurodegenerative, for example, Alzheimer's and Parkinson's. The transition from soluble, functional protein into insoluble amyloid fibril occurs via a complex process involving the initial generation of highly dynamic early stage aggregates or prefibrillar species. Amyloid probes, for example, thioflavin T and Congo red, have been used for decades as the gold standard for detecting amyloid fibrils in solution and tissue sections. However, these well-established dyes do not detect the presence of prefibrillar species formed during the early stages of protein aggregation. Prefibillar species have been proposed to play a key role in the cytotoxicity of amyloid fibrils and the pathogenesis of neurodegenerative diseases. Herein, we report a novel fluorescent dye (bis(triphenylphosphonium) tetraphenylethene (TPE-TPP)) with aggregation-induced emission characteristics for monitoring the aggregation process of amyloid fibrils. An increase in TPE-TPP fluorescence intensity is observed only with ordered protein aggregation, such as amyloid fibril formation, and not with stable molten globules states or amorphously aggregating species. Importantly, TPE-TPP can detect the presence of prefibrillar species formed early during fibril formation. TPE-TPP exhibits a distinctive spectral shift in the presence of prefibrillar species, indicating a unique structural feature of these intermediates. Using fluorescence polarization, which reflects the mobility of the emitting entity, the specific oligomeric pathways undertaken by various proteins during fibrillation could be discerned. Furthermore, we demonstrate the broad applicability of TPE-TPP to monitor amyloid fibril aggregation, including under diverse conditions such as at acidic pH and elevated temperature, or in the presence of amyloid inhibitors.


Assuntos
Corantes Fluorescentes/química , Fenóis/química , Agregados Proteicos , Fluorescência , Polarização de Fluorescência , Humanos
18.
J Dairy Sci ; 100(7): 5121-5124, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28624068
19.
Psychopharmacology (Berl) ; 234(12): 1871-1880, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28314949

RESUMO

RATIONALE: Emerging evidence suggests the potential utility of combining opioids with imidazoline I2 receptor agonists for chronic pain. However, chronic pain management requires prolonged pharmacotherapy, and the consequence of such combination therapy remains unclear. OBJECTIVE: This study examined the anti-hyperalgesic effect of the opioid oxycodone, the selective I2 receptor agonist phenyzoline, alone and in combination, during prolonged treatment. METHODS: Von Frey filament test was used to examine the anti-hyperalgesic effect of drugs in complete Freund's adjuvant (CFA)-induced inflammatory pain or chronic constriction injury (CCI)-induced neuropathic pain in rats. Twice-daily treatment with oxycodone and phenyzoline, alone or in combination, was continued until the development of significant tolerance (oxycodone) or as long as 19 days passed (phenyzoline). RESULTS: In rats receiving CFA or CCI manipulation, mechanical hyperalgesia was dose-dependently reversed by oxycodone and phenyzoline. Twice-daily treatment with 2 × ED50 dose of oxycodone for 7 days led to significant antinociceptive tolerance to oxycodone but not cross-tolerance to phenyzoline. Similarly, twice-daily treatment with 2 × ED50 dose of phenyzoline for 19 days led to significant antinociceptive tolerance to phenyzoline but not cross-tolerance to oxycodone. Twice-daily treatment with the combined oxycodone and phenyzoline using different ratios (1:3, 1:1 and 3: 1) at the doses that were functionally equivalent to the treatment doses of oxycodone and phenyzoline for 13-19 days generally led to delayed antinociceptive tolerance. CONCLUSIONS: Combination therapy with oxycodone and I2 receptor agonists maintains prolonged antinociceptive effectiveness with reduced propensity to develop tolerance.


Assuntos
Analgésicos Opioides/administração & dosagem , Tolerância a Medicamentos , Receptores de Imidazolinas/agonistas , Imidazolinas/administração & dosagem , Oxicodona/administração & dosagem , Dor/tratamento farmacológico , Analgésicos/administração & dosagem , Animais , Relação Dose-Resposta a Droga , Quimioterapia Combinada , Tolerância a Medicamentos/fisiologia , Receptores de Imidazolinas/fisiologia , Masculino , Dor/patologia , Medição da Dor/efeitos dos fármacos , Medição da Dor/métodos , Ratos , Ratos Sprague-Dawley
20.
Sarcoma ; 2016: 3872768, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27413360

RESUMO

The Ewing sarcoma family of tumors (ESFT) encompasses a group of highly aggressive, morphologically similar, malignant neoplasms sharing a common spontaneous genetic translocation that affect mostly children and young adults. These predominantly characteristic, small round-cell tumors include Ewing's sarcoma of the bone and soft tissue, as well as primitive neuroectodermal tumors (PNETs) involving the bone, soft tissue, and thoracopulmonary region (Askin's tumor). Extraosseous ESFTs are extremely rare, especially in the head and neck region, where literature to date consists of sporadic case reports and very small series. We hereby present a review of the literature published on ESFTs reported in the maxilla and maxillary sinus region from 1968 to 2016.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA