Fibrillary Protein Research Articles

Mechanistic In Vitro Dissection of the Inhibition of Amyloid Fibrillation by n-Acetylneuraminic Acid: Plausible Implication in Therapeutics for Neurodegenerative Disorders.

A variety of neurodegenerative disorders including Parkinson's disease are due to fibrillation in amyloidogenic proteins. The development of therapeutics for these disorders is a topic of extensive research as effective treatments are still unavailable. The present study establishes that n-acetylneuraminic acid (Neu5ac) inhibits the amyloid fibrillation of hen egg-white lysozyme (HEWL) and α-synuclein (SYN), as observed using various biophysical techniques and cellular assays. Neu5ac inhibits the amyloid formation in both proteins, as suggested from the reduction in the ThT fluorescence and remnant structures in transmission electron microscopy micrographs observed in its presence. In HEWL fibrillation, Neu5ac decreases the hydrophobicity and resists the transition of the α-helix to a β-sheet, as observed by an ANS binding assay, circular dichroism (CD) spectra, and Fourier transform infrared measurements, respectively. Neu5ac stabilizes the states that facilitate the amyloid formation in HEWL and SYN, as demonstrated by an enhanced intrinsic fluorescence in its presence, which is further confirmed by an increase in Tm obtained from differential scanning calorimetry thermograms and an increase in the near-UV CD signal for HEWL with Neu5ac. However, the increase in stability is not a manifestation of Neu5ac binding to amyloid facilitating (partially folded or native) states of both proteins, as verified by isothermal titration calorimetry and fluorescence binding measurements. Besides, Neu5ac also attenuates the cytotoxicity of amyloid fibrils, as evaluated by a cell toxicity assay. These findings provide mechanistic insights into the Neu5ac action against amyloid fibrillation and may establish it as a plausible inhibitor molecule against neurodegenerative disorders.

484 Echocardiographic patterns in patients with apolipoprotein AI amyloidosis

Abstract Aims Hereditary amyloidosis are rare diseases characterized by extracellular deposition of insoluble fibril proteins in target organs disrupting their structure and function. The APOA1 gene encodes the precursor of apolipoprotein AI (ApoAI), whose mature form is the major component of high-density lipoproteins. There are some clusters of ApoAI amyloidosis (AApoAI) worldwide, including in the Lombardy and Veneto regions. Patients with AApoAI often present with chronic kidney disease, liver and spleen enlargement, with occasional involvement of the heart, peripheral nervous system, and other organs. Patterns of cardiac disease in AApoAI have never been systematically investigated. Methods and results We examined all patients with an established diagnosis of AApoAI referred to a dedicated outpatient clinic in Brescia from 2010 to 2020. The cardiac screening included a transthoracic echocardiogram with 2D speckle-tracking analysis. One-hundred and eighty-nine patients were evaluated [n = 102 (54%) men, median age 55 years (interquartile range 42–67)]. Renal disease was present in 39% and liver disease in 31%. Almost all patients were in sinus rhythm (96%). Median left ventricular ejection fraction (LVEF) was 60% (55–66), and just 2% of patients had LVEF <50%. Diastolic function was preserved, with E/e′ ratio of 7 (6–10). Overall, patients did not display a prominent LV hypertrophy, with median interventricular septal thickness of 11 mm (9–12), a posterior wall thickness of 9 mm (8–11), and a LV mass index of 92 g/m2 (74–111). Global longitudinal strain [−19% (−21 to − 17)], and the mass to strain ratio (MSR) [10.0 (6.8–12.1)] were within normal limits. Ten percent of patients displayed apical sparing, and 19% had a ‘granular sparkling’ appearance of the interventricular septum, which are both echocardiographic red flags of cardiac amyloidosis. Right ventricular (RV) function was preserved [median tricuspid annular plane systolic excursion of 23 mm (20–26)], with a borderline RV free wall thickness [6 mm (5–8)]. A pericardial effusion was present in 11%. Moderate to severe mitral, aortic or tricuspid regurgitation or aortic stenosis were found in 11%, 4%, 6% and no patients, respectively. We found moderately strong correlations between age and several echocardiographic findings, namely: IVS (P < 0.001, r = 0.484), LVMI (P < 0.001, r = 0.459), E/e′ (P < 0.001, r = 0.501), and RV free wall thickness (P < 0.001, r = 0.459). Absolute GLS tended to decrease with age (P < 0.001, r = 0.380), and MSR to increase (P < 0.001, r = 0.357). Conclusions In the largest series of patients with AApoAI so far, minor signs of cardiac disease emerged from transthoracic echocardiography. Nonetheless, some red flags of cardiac amyloidosis were found in some patients. Furthermore, the correlations between age and echocardiographic findings suggested a progressive increase in wall thickness, a decline in systolic and diastolic function, and a greater uncoupling between LV mass and contractility over time.

325 Dealing with cardiac amyloidosis diagnosis: keep calm and use the magnifying glasses!

Abstract Methods and results Case report— male, 71 years old. Past medical history—arterial hypertension, dyslipidemia, tobacco abuse. COPD on nocturnal CPAP therapy. Rheumatic polymyalgia on steroid therapy. Previous unprovoked deep vein thrombosis on anticoagulation with rivaroxaban. Bilateral carpal tunnel surgeries 8 years ago. Spontaneous left biceps tendon rupture 4 year ago. IgA kappa monoclonal gammopathy of undetermined significance (MGUS). Mild interventricular septum (IVS) hypertrophy on echocardiography since 2018. In 2019 IVS was 18 mm with granular sparkling appearance. In February 2020 he was hospitalized for initial heart failure and COPD exacerbation. In 2021 he developed worsening dyspnoea. He underwent cardiological evaluation in a spoke hospital and a cardiac magnetic resonance (CMR) suggested infiltrative cardiomyopathy. Bone scintigraphy showed moderate cardiac uptake (Perugini Score 2). Following haematological evaluation, fat pad biopsy was performed, and amyloid was detected on Congo red staining. Classification of the amyloid fibril protein was not performed. Bone marrow biopsy, even though of suboptimal quality, was negative for amyloid and for plasma cellular infiltration. Bone marrow aspirate showed 11% of plasma cells and multiple myeloma was therefore hypothesized. Recent medical history—he was evaluated in our Cardiac Amyloid Outpatient Clinic in May 2021. He was symptomatic for dyspnoea (NYHA class III) and exercise intolerance, diffuse osteo-muscolar pain, and extremities paresthesia. His blood pressure was on the low side of normality with necessity of anti-hypertensive therapy downgrading. Signs and symptoms of hematological disease were not present. We required to analyse the fat pad specimen in order to perform amyloid fibril protein typing; with immunoelectron microscopy, transthyretin (TTR) was identified as the amyloid fibrils precursor (no light chains could be identified). We considered performing endomyocardial biopsy to exclude the coexistence of ATTR amyloidosis and light chains (AL) amyloidosis in the heart but, given the history, clinical picture, and fat pad biopsy results, we felt that cardiac ATTR was the most probable diagnosis and we decided to proceed with a close cardiological and haematological follow-up. TTR genetic testing is ongoing. Conclusions ATTR cardiac amyloidosis is an emerging cause of heart failure, especially with preserved ejection fraction, in the older population. However, these patients frequently present with dysproteinemias and bone marrow abnormalities, up to multiple myeloma, raising the issue of differential diagnosis between ATTR and AL amyloidosis. According to the latest European Consensus Document, in the presence of cardiac uptake at bone scintigraphy (Grades 1–3) and positive haematologic tests, histological confirmation (usually cardiac) is necessary to subtype amyloid infiltration. In our case, the patient had positive Congo Red-stained fat pad biopsy, but the typing of the amyloid deposition was not performed. After referral to a Center with a Cardiac Amyloid Outpatient Clinic with a specialized Pathology Unit, we could further proceed with diagnostic workup and identify the amyloid deposition as ATTR; of note, fat pad biopsy is positive in just 15–25% of ATTR amyloidosis. Moreover, close collaboration with Hematology was necessary to assess the risk of AL amyloidosis and to provide a close and targeted follow-up. Endomyocardial biopsy was not performed after consideration of the various elements suggestive for ATTR cardiac amyloidosis, but the patient will be evaluated periodically and closely to potentially reassess this decision.

Dihedral Angle Measurements for Structure Determination by Biomolecular Solid-State NMR Spectroscopy.

In structural studies of immobilized, aggregated and self-assembled biomolecules, solid-state NMR (ssNMR) spectroscopy can provide valuable high-resolution structural information. Among the structural restraints provided by magic angle spinning (MAS) ssNMR the canonical focus is on inter-atomic distance measurements. In the current review, we examine the utility of ssNMR measurements of angular constraints, as a complement to distance-based structure determination. The focus is on direct measurements of angular restraints via the judicious recoupling of multiple anisotropic ssNMR parameters, such as dipolar couplings and chemical shift anisotropies. Recent applications are highlighted, with a focus on studies of nanocrystalline polypeptides, aggregated peptides and proteins, receptor-substrate interactions, and small molecule interactions with amyloid protein fibrils. The review also examines considerations of when and where ssNMR torsion angle experiments are (most) effective, and discusses challenges and opportunities for future applications.

Whey protein (amyloid)-aggregates in oil-water systems: The process-related comminution effect

Whey protein fibrils are excellent emulsifiers. However, the emulsification process significantly alters the size of the aggregates and thus their functionality. It is not yet known how strongly the disperse phase (oil) contributes to the size change. Furthermore, it is unknown whether the aggregate morphologies (semi-flexible amyloid-, and flexible amyloid-like aggregates) differ in their size reduction during emulsification. Therefore, both types of aggregates were processed under different stress levels and in the presence and absence of an oil phase by rotor-stator dispersion, ultrasonication and high-pressure homogenisation. The size reduction exponent for each aggregate type was determined by atomic force microscopy, analytical ultracentrifugation and dynamic light scattering. Semi-flexible fibrils decreased in length by rotor-stator shear from 6200 to a minimum of 190 nm, but sonication resulted in even greater shortening (150 - 84 nm) and is comparable to high pressure homogenisation (283 - 111 nm). Worm-like flexible aggregates are only affected by sonication (98 - 46 nm). The addition of oil resulted in a further reduced aggregate length with lower energy input for all aggregates. Overall, these results provide new insights about the emulsion processing behaviour of different amyloid aggregates, which should be taken into account when preparing emulsions. • Influence of processing on fibrils and wormlike aggregates were investigated. • Different stressing conditions were implemented (ultra-turrax, sonication and HPH). • Addition of oil led to a difference in the comminution rate. • Wormlike aggregates were more stable against ultra-turrax compared to fibrils. • Secondary structure of both aggregates were stable against processing.

Structural basis for transthyretin amyloid formation in vitreous body of the eye

Amyloid transthyretin (ATTR) amyloidosis is characterized by the abnormal accumulation of ATTR fibrils in multiple organs. However, the structure of ATTR fibrils from the eye is poorly understood. Here, we used cryo-EM to structurally characterize vitreous body ATTR fibrils. These structures were distinct from previously characterized heart fibrils, even though both have the same mutation and type A pathology. Differences were observed at several structural levels: in both the number and arrangement of protofilaments, and the conformation of the protein fibril in each layer of protofilaments. Thus, our results show that ATTR protein structure and its assembly into protofilaments in the type A fibrils can vary between patients carrying the same mutation. By analyzing and matching the interfaces between the amino acids in the ATTR fibril with those in the natively folded TTR, we are able to propose a mechanism for the structural conversion of TTR into a fibrillar form.

Superoxide dismutase-1 alters the rate of prion protein aggregation and resulting fibril conformation

The assembly of amyloidogenic proteins into highly-structured fibrillar aggregates is related to the onset and progression of several amyloidoses, including neurodegenerative Alzheimer's or Parkinson's diseases. Despite years of research and a general understanding of the process of such aggregate formation, there are currently still very few drugs and treatment modalities available. One of the factors that is relatively insufficiently understood is the cross-interaction between different amyloid-forming proteins. In recent years, it has been shown that several of these proteins or their aggregates can alter each other's fibrillization properties, however, there are still many unknowns in the amyloid interactome. In this work, we examine the interaction between amyloid disease-related prion protein and superoxide dismutase-1. We show that not only does superoxide dismutase-1 increase the lag time of prion protein fibril formation, but it also changes the conformation of the resulting aggregates.

Neuropathology of murine Sanfilippo D syndrome

Sanfilippo D syndrome (mucopolysaccharidosis type IIID) is a lysosomal storage disorder caused by the deficiency of N-acetylglucosamine-6-sulfatase (GNS). A mouse model was generated by constitutive knockout of the Gns gene. We studied affected mice and controls at 12, 24, 36, and 48 weeks of age for neuropathological markers of disease in the somatosensory cortex, primary motor cortex, ventral posterior nuclei of the thalamus, striatum, hippocampus, and lateral and medial entorhinal cortex. We found significantly increased immunostaining for glial fibrillary associated protein (GFAP), CD68 (a marker of activated microglia), and lysosomal-associated membrane protein-1 (LAMP-1) in Sanfilippo D mice compared to controls at 12 weeks of age in all brain regions. Intergroup differences were marked for GFAP and CD68 staining, with levels in Sanfilippo D mice consistently above controls at all age groups. Intergroup differences in LAMP-1 staining were more pronounced in 12- and 24-week age groups compared to 36- and 48-week groups, as control animals showed some LAMP-1 staining at later timepoints in some brain regions. We also evaluated the somatosensory cortex, medial entorhinal cortex, reticular nucleus of the thalamus, medial amygdala, and hippocampal hilus for subunit c of mitochondrial ATP synthase (SCMAS). We found a progressive accumulation of SCMAS in most brain regions of Sanfilippo D mice compared to controls by 24 weeks of age. Cataloging the regional neuropathology of Sanfilippo D mice may aid in understanding the disease pathogenesis and designing preclinical studies to test brain-directed treatments.

Flavonolignan silibinin abrogates SDS induced fibrillation of human serum albumin

Misfolding, aggregation and fibrillation of amyloidogenic proteins have been established as hallmark events in pathophysiology of various degenerative diseases. Inhibition of protein fibrillation through use of plant derived molecular scaffolds is currently considered as one solution to it. Further, rational design of therapeutic originating with the specific plant molecular scaffolds appeared passable to aid in mitigating amyloidogenic diseases. Silibinin (SB) is a flavonolignan obtained from milk thistle plant. SB is well acclaimed as a potent hepatoprotective, cardioprotective and an attenuator of receptor signaling in case of type 2 diabetes. This work reports the inhibitory capacity of SB against protein fibrillation under experimental conditions. Human serum albumin (HSA), an ubiquitous serum protein was used and various platform studies were carried out for indepth understanding of similar effects. Biophysical studies and electron microscopy confirmed that SB inhibited HSA fibrils formations by 36% at optimal molar ratio. In silico studies further demonstrated that intermolecular hydrogen bonds and hydrophobic interactions hindered progressive aggregation and protein fibrillation.

Interfacial Interactions within Amyloid Protein Corona Based on 2D MoS2 Nanosheets.

The interfacial interaction within the amyloid protein corona based on MoS2 nanomaterial is crucial, both for understanding the biological effects of MoS2 nanomaterial and the evolution of amyloid diseases. The specific nano-bio interface phenomenon of human islet amyloid peptide (hIAPP) and MoS2 nanosheet was investigated by using theoretical and experimental methods. The MoS2 nanosheet enables the attraction of hIAPP monomer, dimer, and oligomer on its surface through van der Waals forces. Especially, the means of interaction between two hIAPP peptides might be changed by MoS2 nanosheet. In addition, it is interesting to find that the hIAPP oligomer can stably interact with the MoS2 nanosheet in one unique "standing" binding mode with an entire exposed β-sheet surface. All the interaction modes on the surface of MoS2 nanosheet can be the essence of amyloid protein corona that may provide the venue to facilitate the fibrillation of hIAPP proteins. Further, it was verified experimentally that MoS2 nanosheets could accelerate the fibrillation of hIAPP at a certain concentration mainly based on the newly formed nano-bio interface. In general, our results provide insight into the molecular interaction mechanism of the nano-bio interface within the amyloid protein corona, and shed light on the pathway of amyloid protein aggregation that is related to the evolution of amyloid diseases.

B2 Microglobulin and Bence Jones Proteinuria Guide the Diagnosis of Idiopathic AA Amyloidosis: A Journal to Diagnosis

Amyloidosis is a disease caused by the extracellular deposition of pathological insoluble fibrillary protein in multiple tissues and may result in severe organ dysfunction. There are two major forms of amyloidosis: AL amyloid and AA amyloidosis, which complicates any chronic inflammatory condition, including rheumatologic, chronic infections, and certain neoplasms. In small but increasing numbers, the chronic inflammatory state underlying AA amyloidosis remains obscure, despite extensive investigations, which are known as idiopathic. In the current case, the first extensive evaluation to determine the inflammatory disease was negative. The patient had B2 microglobulin elevation and Bence jones proteinuria, which are non-specific findings, but are not conclusive, for malignancies. The diagnosis of Idiopathic AA amyloidosis was guided by understanding the pathophysiology of B2 microglobulin and Bence jones proteinuria along with excluding all other etiologies. Unfortunately, the development of restrictive cardiomyopathy and ESRD within 3 months indicates a rapid progression and poor prognosis in this patient. Clinicians may not be familiar that B2 microglobulin and Bence jones proteinuria are also found in amyloidosis, which may delay the diagnosis. Inflammatory process and kidney injury due to AA amyloidosis caused previous markers positivity in our patient. It is plausible that delays in diagnosis may be multi-faceted and heavily influenced by the average age of the patient, the complexity and the rareness of the disease. Also, non-disease-specific symptoms may reduce the likelihood of a prompt diagnosis. Therefore, establishing the diagnosis is difficult, and early diagnosis requires high clinical suspicion.

Role of mutations and post-translational modifications in systemic AL amyloidosis studied by cryo-EM

Systemic AL amyloidosis is a rare disease that is caused by the misfolding of immunoglobulin light chains (LCs). Potential drivers of amyloid formation in this disease are post-translational modifications (PTMs) and the mutational changes that are inserted into the LCs by somatic hypermutation. Here we present the cryo electron microscopy (cryo-EM) structure of an ex vivo λ1-AL amyloid fibril whose deposits disrupt the ordered cardiomyocyte structure in the heart. The fibril protein contains six mutational changes compared to the germ line and three PTMs (disulfide bond, N-glycosylation and pyroglutamylation). Our data imply that the disulfide bond, glycosylation and mutational changes contribute to determining the fibril protein fold and help to generate a fibril morphology that is able to withstand proteolytic degradation inside the body.

Pre-Clinical Characterization of a Novel Fusion Protein (AT-03), with Pan-Amyloid Binding and Removal

Background: Amyloidosis is characterized by extracellular deposition of protein fibrils that can involve any organ or tissue in the body. It is a severe, progressive and often lethal disorder. There are approximately seventeen different systemic amyloid diseases, each associated with the deposition of a specific precursor protein. Toxic amyloid deposits result in significant organ dysfunction and increased morbidity and mortality. Reduction and removal of tissue amyloid deposits could restore organ function, improve quality of life and increase life expectancy for patients. We have developed and characterized a fusion protein consisting of serum amyloid protein (SAP) linked to a single chain human IgG1 Fc domain, designated AT-03. SAP is a pentameric serum protein that is ubiquitously associated with amyloid deposits. The high affinity and specificity for amyloid resulted in the use of radio-iodinated SAP as an imaging agent for the non-invasive detection of systemic amyloid. The SAP domain of the fusion protein targets the amyloid deposits delivering Fc domains to stimulate amyloid removal via macrophage mediated phagocytosis.Methods: Binding of AT-03 to ATTR and AL fibrils and extracts was assessed by ELISA. Ex vivo phagocytosis of amyloid substrates was studied using activated human THP-1 cells. The biodistribution of AT-03 in murine models of AA, AApoA2 and AL amyloidosis was evaluated immunohistochemically or by SPECT imaging and microautoradiography. Clearance of AA amyloidosis in response to AT-03 therapy was accessed in a mouse model using histological scoring of amyloid burden.Results: AT-03 bound amyloid AL and ATTR substrates with sub nanomolar EC50 values. Systemic administration of AT-03 resulted in specific binding to diverse forms of amyloid in the heart, kidney, liver and/or spleen in multiple animal models. Opsonization of amyloid deposits with AT-03 in vitro resulted in a dose dependent phagocytosis by activated THP-1 cells. A single IV dose of AT-03 resulted in significant reduction of splenic AA amyloid within 14 days post-injection.Conclusions: We have developed a novel fusion protein with sub nanomolar pan amyloid reactivity that specifically binds diverse forms of amyloid in multiple organs and tissues in vivo and can effectuate amyloid removal. The data indicates that AT-03 may serve as a novel therapeutic for the removal of systemic amyloid deposits of diverse types. AT-03 is currently being developed for clinical evaluation. DisclosuresSirac: Attralus, Inc: Patents & Royalties, Research Funding. Jaccard: Janssen: Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria; Abbvie: Honoraria. Bridoux: AstraZeneca: Consultancy, Speakers Bureau; Janssen: Consultancy. Bell: Attralus Inc: Current Employment. Guthrie: Attralus Inc: Current Employment. Selvarajah: Attralus Inc: Current Employment. Kennel: Attralus Inc: Current holder of stock options in a privately-held company, Patents & Royalties: Inventor and patent holder. Wall: Attralus Inc: Current holder of stock options in a privately-held company, Patents & Royalties: Inventor and patent holder, Research Funding.

Heat accelerates degradation of β-lactoglobulin fibrils at neutral pH

Fibrous aggregates of β-lactoglobulin display superior mechanical and interfacial properties compared to the native protein. These properties directly link to the protein morphology and structure. When incorporated into food matrices, during processing protein fibrils are exposed to pH shifts and high temperature conditions, which accelerate their degradation. In the present study, neutralized β-lactoglobulin fibrils were heated at 100 °C and 121 °C for various times to assess their degradation. Fibril morphology, structure, and viscosity in solution were examined by microscopy, scattering, spectroscopy, and rheology. Atomic force microscopy showed the contour length of the protein fibrils decreased gradually with heating at 100 °C and 121 °C, with greater decreases at 121 °C. Increased fibril diameters (∼15–25 nm) were observed at 121 °C for 5–15 min heating and were disrupted upon further heating. Small-angle x-ray scattering indicated an increase in fibril radius with heating at pH 7 followed by a decrease at prolonged heating, whereas fibril length decreased continuously with heating. Thioflavin T fluorescence, circular dichroism and Fourier transform infrared spectroscopy confirmed the conversion of β-sheet to random coils as fibrils were degraded during thermal treatment at pH 7. Surface hydrophobicity of fibrils decreased with increase in heating temperature and time, coinciding with an increase in the content of non-aggregated proteins. Viscosity of fibril solutions increased when fibrils were heated at 100 °C, whereas at 121 °C their viscosity first increased and then decreased. These findings imply heating at 100 °C and 121 °C facilitates degradation and depolymerisation of β-lactoglobulin fibrils with aggregation as an intermediate step.

How fullerenes inhibit the amyloid fibril formation of hen lysozyme

The inhibition of protein unfolding and self-assembly into fibrils using nanoparticles is a potential medicinal strategy to impede amyloid-related diseases. Among various nanoparticles, fullerenes have attracted great interest because of their inhibition effect on protein fibrillization, but the mechanism of the inhibition process is not properly understood. To explore the inhibition mechanisms, molecular dynamics simulations of hen egg white lysozyme (HEWL), a model of an amyloid-prone protein, have been performed in the presence of varied C60 concentrations. It is found that the structural fluctuation of HEWL decreases as the concentration of C60 increases. As the concentration of C60 increases, clustered fullerene aggregates are formed via hydrophobic interaction rather than interacting with HEWL, and HEWL was adsorbed on the surface of the fullerene aggregates. The maintenance of the structure and the inhibition of HEWL fibrillization by C60 is also experimentally confirmed by thioflavin T fluorescence assays and atomic force microscopy. Thus, two independent methods confirmed that C60 is able to inhibit the formation of amyloid fibrils in a dose-dependent manner. This study is an initial step in understanding by which mechanism C60 inhibits HEWL fibrillization, allowing to further design strategies for amyloid inhibition based on fullerenes and other nanoparticles.

Conduction abnormalities and role of cardiac pacing in cardiac amyloidosis: A systematic review.

Cardiac amyloidosis (CA) is an increasingly recognized cause of heart failure, characterized by extracellular deposition of insoluble protein fibrils leading to progressive myocardial dysfunction. The most common types of cardiac amyloidosis are immunoglobin light-chain (AL) and transthyretin (ATTR). Conduction abnormalities are commonly encountered among patients with cardiac amyloidosis and are an important cause of morbidity and mortality. Abnormalities range from infra-Hisian intraventricular conduction delay and bundle branch block to complete atrioventricular block. Pacemaker placement in CA patients follows established guidelines, similar to those for patients without CA, with generally good efficacy. The role and appropriate timing of pacemakers for primary prevention of brady-arrhythmias in CA remains uncertain. While biventricular (BiV) pacing has been shown to improve clinical outcomes in patients with systolic heart failure without CA, there are few data examining the utility of BiV pacing in patients with CA. With the advent of effective treatments for AL and ATTR, appropriate application of pacing is important to support patients with CA and conduction disease through therapeutic trials. This systematic review summarizes the current literature examining the utility of pacing in CA.

Potential of tetradecyltrimethylammonium bromide in preventing fibrillation/aggregation of lysozyme: biophysical studies

A key step in the prevention of neurodegenerative disorders is to inhibit protein aggregation or fibrillation process. Functionality recognition is an essential strategy in developing effective therapeutics in addressing the treatment of amyloidosis. Here, we have focused on an approach based on structure–property energetics correlation associated with tetradecyltrimethylammonium bromide (TTAB), a cationic surfactant that acts as an inhibitor targeting different stages of hen egg-white lysozyme fibrillation. Characterization of amyloid fibrils and the inhibitory capability of 16 mM TTAB surfactant on fibrillation were investigated with the calorimetric, spectroscopic and microscopic techniques. ThT binding fluorescence studies inferred that micellar TTAB exerts its maximum inhibitory effect against amyloid fibrillation than monomer TTAB. The TEM measurements also confirmed complete absence of amyloid fibrils at micellar TTAB. At the same time, the transformation of β-sheet to α-helix under the action of TTAB was confirmed by the Far-UV CD spectroscopy. Although there have been some reports suggesting that cationic surfactants can induce aggregation in proteins, this work suggests that polar interactions between head groups of TTAB and amyloid fibrils are the predominant factors that cause retardation in fibrillation by interrupting/disturbing the intermolecular hydrogen bond of β-sheets. The present finding has explored the knowledge-based details in developing efficient potent inhibitors and provides a platform to treat diseases associated with protein misfolding. Communicated by Ramaswamy H. Sarma

Multiple rounds of nuclei induced whey protein concentrate fibril formation at varying ionic species and concentrations

Mature whey protein concentrate (WPC) fibrils can act as secondary nuclei to induce fibrillation. Multiple rounds of nuclei induced aggregation could introduce differences in their ability to form fibrils. The second induction fabricated the highest population of fibrils, while the sixth induction lost the ability of fibrillation. Salt-tolerant fibrils through multiple inductions were produced, but less with each cycle owing to a decreased salt tolerance. The difference in fibrillation between spontaneous formation and multiple rounds of induction was associated with the ability of ions to bind to the protein aggregations. More cations were distributed on the surface of fibrils after the sixth cycle of induction compared with that of the second induction. Divalent salts had much stronger effects than monovalent salts on inhibiting protein fibrillation due to fewer divalent cations distributed on the surface of the fibril. Cation binding appeared to be an important factor in the formation of fibrils.

Tryptophan-cardanol fluorescent nanoparticles inhibit α-synuclein aggregation and disrupt amyloid fibrils.

Protein misfolding and aggregation play a vital role in several human diseases such as Parkinson's, Alzheimer's, and prion diseases. The development of nanoparticles that modulate aggregation could be potential drug candidates for these neurodegenerative disorders. Parkinson's disease pathogenesis is closely associated with the accumulation of α-synuclein oligomers and fibrils in the substantia nigra of the brain. This report discusses the interactions of novel tryptophan-cardanol nanoparticles with α-synuclein protein monomers and fibrils. These nanoparticles could effectively disrupt α-synuclein fibrils and inhibit fibril formation at low concentrations such as 5μM. The tryptophan-cardanol nanoparticles inhibit fibril formation from unstructured protein resulting in spherical nanostructures. These nanoparticles could also disassemble amyloid fibrils; the complete disappearance of fibrils was evident after 48 h of incubation with tryptophan-cardanol. The transmission electron microscopy (TEM) micrographs after the incubation did not show any remnants of the peptide aggregates or oligomers. The thioflavin T fluorescence after the disassembly was diminished compared with that of fibrils also supports the inhibitory effect of the nanoparticles. Also, these nanoparticles did not reduce the viability of the SH-SY5Y cells. These findings suggest that the tryptophan-cardanol nanoparticles showed sufficiently high inhibitory activity and may have therapeutic potential for synucleinopathies.

Engineering of inorganic nanostructures with hierarchy of chiral geometries at multiple scales

Engineering of inorganic nanostructures with hierarchy of chiral geometries at multiple scales