Palliative medicine in the emergency department: symptom control and aggressive care.

OBJECTIVES: Identifying the prevalence of palliative care (PC) needs among patients who die at the emergency department (ED) and to assess symptom control and aggressiveness of care. METHODS: We conducted a decedent cohort study of adults deceased at the ED of a Portuguese teaching hospital in 2016. PC needs were identified using the National Hospice Organization terminality criteria and comorbidities measurement by the Charlson's Index. RESULTS: 384 adults died at the ED (median age 82 (IQR 72-89) years) and 78.4% (95% CI 73.9% to 82.2%) presented PC needs. Only 3.0% (n=9) were referred to the hospital PC team. 64.5%, 38.9% and 57.5% experienced dyspnoea, pain and confusion, respectively. Dyspnoea was commonly medicated (92%), against 56% for pain and 8% for confusion. Only 6.3% of the patients were spared from aggressive interventions, namely blood collection (86.0%) or intravenous fluid therapy (63.5%). The burden of aggressive interventions was similar between those with or without withhold cardiopulmonary resuscitation order (median 3 (2-4) vs 3 (2-5)), p=0.082. CONCLUSIONS: Nearly four out of five adults who died at the ED had PC needs at the time of admission. Most experienced poor symptom control and care aggressiveness in their last hours of life and were mostly unknown to the PC team. The findings urge improvements in the care provided to patients with PC needs at the ED, focusing on patient well-being and increased PC referral.

A Rare and Surprising Case of Spontaneous Type B Carotid-Cavernous Fistula in an Internal Medicine Ward.

Carotid-cavernous fistulas are abnormal communications between the carotid arteries and the cavernous sinus. They can be spontaneous, which is rare, or acquired, most often post-traumatic. We describe the case of a 59-year-old woman with complaints of right-sided red eye and blurred vision that did not improve with antibiotic treatment for bacterial conjunctivitis, progressing to what appeared to be post-septal cellulitis. The patient had exuberant chemosis, diplopia, VI cranial nerve palsy, and elevated intraocular pressure in the right eye. Computed tomography of the orbits showed right-sided thickening of the soft tissues of the upper eyelid and the medial and lateral rectus muscles, and an enlargement of the ipsilateral superior ophthalmic vein. However, antibiotics did not cause any kind of improvement. After a laborious diagnostic march, the diagnosis of a rare case of Barrow type B spontaneous carotid-cavernous fistula was confirmed. The patient underwent confirmatory angiography with endovascular treatment at the same time, showing rapid improvement after the procedure, without any sequelae. It is of great importance that clinicians are alert to this diagnosis, as diagnostic and therapeutic delay can lead to severe ocular compromise. In patients with a presumptive diagnosis of conjunctivitis and/or orbital cellulitis that does not improve with antibiotic treatment, the differential diagnosis with this rare entity should be considered, so that the appropriate treatment can be timely instituted.

Pulmonary Exacerbations in Pediatric Patients: Retrospective Study in a Portuguese Cystic Fibrosis Center.

(1) Background: Cystic fibrosis (CF) is a multisystemic disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Lung disease, the leading cause of morbimortality, is marked by acute worsening of symptoms-such as pulmonary exacerbations (PEx). The objectives of this study were: Identifying the frequency of PEx in pediatric CF patients; Characterizing each PEx; Finding association between the frequency and characteristics of the PEx and patients' features. (2) Methods: Retrospective analysis of all PEx from a period of January 2015 to December 2019 in a group of pediatric patients from a single CF center. Data were collected from medical records. Descriptive statistics and chi-square/Fisher's test were used. (3) Results: Thirty-four pediatric patients contributed to the total sample used in this study and 198 PEx were identified, median of 1.0 PEx/patient/year. Most frequent PEx symptoms were increased cough (93.9%) and change in secretions (88.4%), most common pathogens were Staphylococcus aureus (54.9%) and Pseudomonas aeruginosa (24.9%). The majority were treated as outpatient (85.9%). Most common antibiotics included amoxicillin/clavulanate (35.9%) and ciprofloxacin (22.7%). Outcome was favorable in all PEx. (4) Conclusion: Results were consistent with what has been described in literature. More studies are necessary for a better characterization of CF PEx, in order to develop standardized protocols for their management.

Discovery of amivantamab (JNJ-61186372), a bispecific antibody targeting EGFR and MET.

A bispecific antibody (BsAb) targeting the epidermal growth factor receptor (EGFR) and mesenchymal-epithelial transition factor (MET) pathways represents a novel approach to overcome resistance to targeted therapies in patients with non-small cell lung cancer. In this study, we sequentially screened a panel of BsAbs in a combinatorial approach to select the optimal bispecific molecule. The BsAbs were derived from different EGFR and MET parental monoclonal antibodies. Initially, molecules were screened for EGFR and MET binding on tumor cell lines and lack of agonistic activity toward MET. Hits were identified and further screened based on their potential to induce untoward cell proliferation and cross-phosphorylation of EGFR by MET via receptor colocalization in the absence of ligand. After the final step, we selected the EGFR and MET arms for the lead BsAb and added low fucose Fc engineering to generate amivantamab (JNJ-61186372). The crystal structure of the anti-MET Fab of amivantamab bound to MET was solved, and the interaction between the two molecules in atomic details was elucidated. Amivantamab antagonized the hepatocyte growth factor (HGF)-induced signaling by binding to MET Sema domain and thereby blocking HGF ß-chain-Sema engagement. The amivantamab EGFR epitope was mapped to EGFR domain III and residues K443, K465, I467, and S468. Furthermore, amivantamab showed superior antitumor activity over small molecule EGFR and MET inhibitors in the HCC827-HGF in vivo model. Based on its unique mode of action, amivantamab may provide benefit to patients with malignancies associated with aberrant EGFR and MET signaling.

Perceção dos enfermeiros de cuidados paliativos sobre a intervenção do enfermeiro de reabilitação / Perception of palliative care nurses on the intervention of the rehabilitation nurse

Enquadramento: Os Cuidados Paliativos, sendo cuidados de saúde exigentes e humanizados, intervêm sobretudo no sofrimento das pessoas com doenças graves e/ou avançadas e irreversíveis, maximizando, quanto possível, a sua qualidade de vida e dignidade. Com o mesmo propósito intervém a enfermagem de reabilitação num cuidar especializado, no sentido de otimizar o conforto e bem-estar da pessoa, porém nem sempre reconhecido pelos seus pares. Assim pretendemos conhecer a perceção dos enfermeiros sobre a intervenção do enfermeiro especialista em enfermagem de reabilitação nas pessoas internadas em Unidades de Cuidados Paliativos. Métodos: Estudo qualitativo, com recurso à análise de conteúdo. Os dados foram colhidos junto de uma amostra de 13 enfermeiros, sendo 12 do sexo feminino e 1 do sexo masculino. Eram todos licenciados em enfermagem e exerciam a sua atividade profissional em Unidades de Cuidados Paliativos. Para a recolha de dados recorreu-se a uma entrevista semiestruturada. Resultados: Observámos que os enfermeiros da nossa amostra têm uma perceção muito positiva acerca da intervenção do enfermeiro especialista em reabilitação nas Unidades de Cuidados Paliativos, considerando-o como agente facilitador na satisfação das necessidades do doente, destacando a sua intervenção sobretudo aos níveis da cinesiterapia respiratória, promoção/preservação da autonomia/independência do doente, mobilização, treino da deglutição/disfagia e massagem. Conclusões: A visão dos enfermeiros sobre a intervenção do enfermeiro especialista em reabilitação nas unidades de Cuidados Paliativos é positiva salientando a importância da sua intervenção na manutenção das capacidades funcionais dos doentes, a prevenção de riscos/complicações e a promoção de intervenções terapêuticas que objetivem a melhoria das funções residuais e reduzam o impacto das incapacidades resultantes da doença.

Background: Palliative Care, being a demanding and humanized health care, mainly involves the suffering of people with serious and / or advanced and irreversible diseases, maximizing, as much as possible, their quality of life and dignity. With the same purpose, rehabilitation nursing intervenes in a specialized care, in order to optimize the comfort and well-being of the person, but not always recognized by their peers. Thus we intend to know the nurses' perception about the intervention of the nurse specialist in rehabilitation nursing in the people hospitalized in Palliative Care Units. Methods: Qualitative study using content analysis. Data were collected from a sample of 13 nurses, 12 females and 1 males. They were all licensed in nursing and exercised their professional activity in Palliative Care Units. For the collection of data a semi-structured interview was used. Results: We observed that the nurses in our sample have a very positive perception about the intervention of the specialist nurse in rehabilitation in the Palliative Care Units, considering it as a facilitating agent in the patient's needs, emphasizing their intervention mainly at the levels of kinesitherapy respiratory therapy, promotion / preservation of autonomy / independence of the patient, mobilization, deglutition / dysphagia training and massage. Conclusions: The nurses' view on the intervention of the nurse specialist in rehabilitation in the Palliative Care units is positive, emphasizing the importance of their intervention in the maintenance of the functional capacities of the patients, the prevention of risks / complications and the promotion of therapeutic interventions that aim to improve and reduce the impact of disability resulting from the disease.

Abernethy malformation: beware in cases of unexplained hepatic encephalopathy in adults-case report and review of the relevant literature.

The Abernethy malformation consists of a congenital extrahepatic portosystemic shunt and is believed to be extremely rare in humans. The potential implications of abnormal portovenous shunting and decreased hepatic portal flow are numerous and potentially serious. Although congenital extrahepatic portosystemic shunts are increasingly suspected and diagnosed in specialized centres, much of their clinical presentation and natural history is not fully understood. Symptoms of portosystemic shunt are mainly caused by increased levels of ammonia, which lead to signs of encephalopathy. Therapeutic options depend on the type of shunt and its clinical course, so the classification of the congenital portosystemic shunt is a key finding in these patients.

Engineering a targeted delivery platform using Centyrins.

Targeted delivery of therapeutic payloads to specific tissues and cell types is an important component of modern pharmaceutical development. Antibodies or other scaffold proteins can provide the cellular address for delivering a covalently linked therapeutic via specific binding to cell-surface receptors. Optimization of the conjugation site on the targeting protein, linker chemistry and intracellular trafficking pathways can all influence the efficiency of delivery and potency of the drug candidate. In this study, we describe a comprehensive engineering experiment for an EGFR binding Centyrin, a highly stable fibronectin type III (FN3) domain, wherein all possible single-cysteine replacements were evaluated for expression, purification, conjugation efficiency, retention of target binding, biophysical properties and delivery of a cytotoxic small molecule payload. Overall, 26 of the 94 positions were identified as ideal for cysteine modification, conjugation and drug delivery. Conjugation-tolerant positions were mapped onto a crystal structure of the Centyrin, providing a structural context for interpretation of the mutagenesis experiment and providing a foundation for a Centyrin-targeted delivery platform.

Identification of Cys255 in HIF-1α as a novel site for development of covalent inhibitors of HIF-1α/ARNT PasB domain protein-protein interaction.

The heterodimer HIF-1α (hypoxia inducible factor)/HIF-ß (also known as ARNT-aryl hydrocarbon nuclear translocator) is a key mediator of cellular response to hypoxia. The interaction between these monomer units can be modified by the action of small molecules in the binding interface between their C-terminal heterodimerization (PasB) domains. Taking advantage of the presence of several cysteine residues located in the allosteric cavity of HIF-1α PasB domain, we applied a cysteine-based reactomics "hotspot identification" strategy to locate regions of HIF-1α PasB domain critical for its interaction with ARNT. COMPOUND 5 was identified using a mass spectrometry-based primary screening strategy and was shown to react specifically with Cys255 of the HIF-1α PasB domain. Biophysical characterization of the interaction between PasB domains of HIF-1α and ARNT revealed that covalent binding of COMPOUND 5 to Cys255 reduced binding affinity between HIF-1α and ARNT PasB domains approximately 10-fold. Detailed NMR structural analysis of HIF-1α-PasB-COMPOUND 5 conjugate showed significant local conformation changes in the HIF-1α associated with key residues involved in the HIF-1α/ARNT PasB domain interaction as revealed by the crystal structure of the HIF-1α/ARNT PasB heterodimer. Our screening strategy could be applied to other targets to identify pockets surrounding reactive cysteines suitable for development of small molecule modulators of protein function.

Homodimerization of the PAS-B domains of hypoxia-inducible factors.

The Per-Arnt-Sim (PAS) domains of hypoxia-inducible transcription factors (HIF) mediate heterodimer formation between the HIF-α forms that are induced in the event of cellular hypoxia and the constitutive HIF-ß variants. Previous efforts toward structural characterization of the HIF-1α PAS domains were limited by protein stability. Using homology modeling based on the published crystal structure of the PAS-B domain of the homologous protein HIF-2α in complex with the partner HIF-ß (also known as ARNT), we have identified a variant of HIF-1α with improved solubility, monodispersity, and stability. Purified solutions of the PAS-B domains of HIF-1α and HIF-2α differ in their propensity for homodimer formation. In an attempt to understand the structural basis for this difference, and to document the structural changes that accompany homodimer formation, we have undertaken a comparative NMR study of the PAS-B domains of HIF-1α and HIF-2α and mutants of HIF-1α that mimic the behavior of HIF-2α. The NMR spectra of all of these domains are very similar, consistent with the similarity of their amino acid sequences. However, the greater propensity of the HIF-1α PAS-B domain to form dimers as the concentration was increased allowed us to determine the site of homodimerization and pointed toward possible sequence changes in HIF-1α that might discourage the formation of homodimers.

Production of therapeutic proteins in algae, analysis of expression of seven human proteins in the chloroplast of Chlamydomonas reinhardtii.

Recombinant proteins are widely used today in many industries, including the biopharmaceutical industry, and can be expressed in bacteria, yeasts, mammalian and insect cell cultures, or in transgenic plants and animals. In addition, transgenic algae have also been shown to support recombinant protein expression, both from the nuclear and chloroplast genomes. However, to date, there are only a few reports on recombinant proteins expressed in the algal chloroplast. It is unclear whether this is because of few attempts or of limitations of the system that preclude expression of many proteins. Thus, we sought to assess the versatility of transgenic algae as a recombinant protein production platform. To do this, we tested whether the algal chloroplast could support the expression of a diverse set of current or potential human therapeutic proteins. Of the seven proteins chosen, >50% expressed at levels sufficient for commercial production. Three expressed at 2%-3% of total soluble protein, while a forth protein accumulated to similar levels when translationally fused to a well-expressed serum amyloid protein. All of the algal chloroplast-expressed proteins are soluble and showed biological activity comparable to that of the same proteins expressed using traditional production platforms. Thus, the success rate, expression levels, and bioactivity achieved demonstrate the utility of Chlamydomonas reinhardtii as a robust platform for human therapeutic protein production.

A conformational switch in human immunodeficiency virus gp41 revealed by the structures of overlapping epitopes recognized by neutralizing antibodies.

The membrane-proximal external region (MPER) of the human immunodeficiency virus (HIV) envelope glycoprotein (gp41) is critical for viral fusion and infectivity and is the target of three of the five known broadly neutralizing HIV type 1 (HIV-1) antibodies, 2F5, Z13, and 4E10. Here, we report the crystal structure of the Fab fragment of Z13e1, an affinity-enhanced variant of monoclonal antibody Z13, in complex with a 12-residue peptide corresponding to the core epitope (W(670)NWFDITN(677)) at 1.8-A resolution. The bound peptide adopts an S-shaped conformation composed of two tandem, perpendicular helical turns. This conformation differs strikingly from the alpha-helical structure adopted by an overlapping MPER peptide bound to 4E10. Z13e1 binds to an elbow in the MPER at the membrane interface, making relatively few interactions with conserved aromatics (Trp672 and Phe673) that are critical for 4E10 recognition. The comparison of the Z13e1 and 4E10 epitope structures reveals a conformational switch such that neutralization can occur by the recognition of the different conformations and faces of the largely amphipathic MPER. The Z13e1 structure provides significant new insights into the dynamic nature of the MPER, which likely is critical for membrane fusion, and it has significant implications for mechanisms of HIV-1 neutralization by MPER antibodies and for the design of HIV-1 immunogens.

Antigenic and immunogenic study of membrane-proximal external region-grafted gp120 antigens by a DNA prime-protein boost immunization strategy.

The membrane-proximal external region (MPER) of human immunodeficiency virus type 1 (HIV-1) gp41 is a target of broadly neutralizing monoclonal antibodies (MAbs) 2F5, 4E10, and Z13. Here we engrafted the MPER into the V1/2 region of HIV-1 gp120 to investigate the ability of the engineered antigens to elicit virus-neutralizing antibodies (NAbs). To promote the correct folding and presentation of the helical 4E10 epitope, we flanked the epitope with helical domains and manipulated the helix by sequential deletion of residues preceding the epitope. Binding of the recombinant proteins to MAb 4E10 increased four- to fivefold with the deletion of one or two residues, but it returned to the wild-type level when three residues were deleted, suggesting rotation of the 4E10 epitope along the helix. Immunization of mice and rabbits by electroporation-mediated DNA priming and protein boosting with these constructs elicited high levels of gp120-specific antibodies. A consistent NAb response against the neutralization-resistant, homologous JR-FL virus was detected in rabbits but not in mice. Analysis of the neutralizing activity revealed that the NAbs do not target the MPER or the V1, V2, or V3 region. Through this study, we learned the following. (i) The 4E10 epitope can be manipulated using a "rotate-the-helix" strategy that alters the helix register. However, presentation of this epitope in the immunogenic V1/2 region did not render it immunogenic in mice or rabbits. (ii) DNA vaccination with monomeric gp120-based antigens can elicit a consistent NAb response against the homologous neutralization-resistant virus by targeting epitopes outside the V1, V2, and V3 regions.

An affinity-enhanced neutralizing antibody against the membrane-proximal external region of human immunodeficiency virus type 1 gp41 recognizes an epitope between those of 2F5 and 4E10.

The membrane-proximal external region (MPER) of human immunodeficiency virus type 1 (HIV-1) gp41 bears the epitopes of two broadly neutralizing antibodies (Abs), 2F5 and 4E10, making it a target for vaccine design. A third Ab, Fab Z13, had previously been mapped to an epitope that overlaps those of 2F5 and 4E10 but only weakly neutralizes a limited set of primary isolates. Here, libraries of Fab Z13 variants displayed on phage were engineered and affinity selected against an MPER peptide and recombinant gp41. A high-affinity variant, designated Z13e1, was isolated and found to be approximately 100-fold improved over the parental Fab not only in binding affinity for the MPER antigens but also in neutralization potency against sensitive HIV-1. Alanine scanning of MPER residues 664 to 680 revealed that N671 and D674 are crucial for peptide recognition as well as for the neutralization of HIV-1 by Z13e1. Ab competition studies and truncation of MPER peptides indicate that Z13e1 binds with high affinity to an epitope between and overlapping with those of 2F5 and 4E10, with the minimal peptide epitope WASLWNWFDITN. Still, Z13e1 remained about an order of magnitude less potent than 4E10 against several isolates of pseudotyped HIV-1. The sum of our molecular analyses with Z13e1 suggests that the segment on the MPER of gp41 between the 2F5 and 4E10 epitopes is exposed on the functional envelope trimer but that access to the specific Z13e1 epitope within this segment is limited. Thus, the ability of MPER-bearing immunogens to elicit potent HIV-1-neutralizing Abs may depend in part on recapitulating the particular constraints that the functional envelope trimer imposes on the segment of the MPER to which Z13e1 binds.

Structural basis of enhanced binding of extended and helically constrained peptide epitopes of the broadly neutralizing HIV-1 antibody 4E10.

Potent, broadly HIV-1 neutralizing antibodies (nAbs) may be invaluable for the design of an AIDS vaccine. 4E10 is the broadest HIV-1 nAb known to date and recognizes a contiguous and highly conserved helical epitope in the membrane-proximal region of gp41. The 4E10 epitope is thus an excellent target for vaccine design as it is also highly amenable to peptide engineering to enhance its helical character. To investigate the structural effect of both increasing the peptide length and of introducing helix-promoting constraints in the 4E10 epitope, we have determined crystal structures of Fab 4E10 bound to an optimized peptide epitope (NWFDITNWLWYIKKKK-NH(2)), an Aib-constrained peptide epitope (NWFDITNAibLWRR-NH(2)), and a thioether-linked peptide (NWFCITOWLWKKKK-NH(2)) to resolutions of 1.7 A, 2.1 A, and 2.2 A, respectively. The thioether-linked peptide is the first reported structure of a cyclic tethered helical peptide bound to an antibody. The introduced helix constraints limit the conformational flexibility of the peptides without affecting interactions with 4E10. The substantial increase in affinity (10 nM versus 10(4) nM of the IC(50) of the original KGND peptide template) is largely realized by 4E10 interaction with an additional helical turn at the peptide C terminus that includes Leu679 and Trp680. Thus, the core 4E10 epitope was extended and modified to a WFX(I/L)(T/S)XX(L/I)W motif, where X does not play a major role in 4E10 binding and can be used to introduce helical-promoting constraints in the peptide epitope.

Structure-function analysis of the epitope for 4E10, a broadly neutralizing human immunodeficiency virus type 1 antibody.

The human immunodeficiency virus type 1 (HIV-1) neutralizing antibody 4E10 binds to a linear, highly conserved epitope within the membrane-proximal external region of the HIV-1 envelope glycoprotein gp41. We have delineated the peptide epitope of the broadly neutralizing 4E10 antibody to gp41 residues 671 to 683, using peptides with different lengths encompassing the previously suggested core epitope (NWFDIT). Peptide binding to the 4E10 antibody was assessed by competition enzyme-linked immunosorbent assay, and the K(d) values of selected peptides were determined using surface plasmon resonance. An Ala scan of the epitope indicated that several residues, W672, F673, and T676, are essential (>1,000-fold decrease in binding upon replacement with alanine) for 4E10 recognition. In addition, five other residues, N671, D674, I675, W680, and L679, make significant contributions to 4E10 binding. In general, the Ala scan results agree well with the recently reported crystal structure of 4E10 in complex with a 13-mer peptide and with our circular dichroism analyses. Neutralization competition assays confirmed that the peptide NWFDITNWLWYIKKKK-NH(2) could effectively inhibit 4E10 neutralization. Finally, to limit the conformational flexibility of the peptides, helix-promoting 2-aminoisobutyric acid residues and helix-inducing tethers were incorporated. Several peptides have significantly improved affinity (>1,000-fold) over the starting peptide and, when used as immunogens, may be more likely to elicit 4E10-like neutralizing antibodies. Hence, this study represents the first stage toward iterative development of a vaccine based on the 4E10 epitope.

Broadly neutralizing anti-HIV antibody 4E10 recognizes a helical conformation of a highly conserved fusion-associated motif in gp41.

Broadly neutralizing monoclonal antibodies to HIV-1 are rare but invaluable for vaccine design. 4E10 is the broadest neutralizing antibody known and recognizes a contiguous and highly conserved epitope in the membrane-proximal region of gp41. The crystal structure of Fab 4E10 was determined at 2.2 A resolution in complex with a 13-residue peptide containing the gp41 core epitope (NWFDIT). The bound peptide adopts a helical conformation in which the key contact residues, TrpP672, PheP673, IleP675, and ThrP676, map to one face of the helix. The peptide binds in a hydrophobic pocket that may emulate its potential interaction with the host cell membrane. The long CDR H3 of the antibody extends beyond the bound peptide in an orientation that suggests that its apex could contact the viral membrane when 4E10 is bound to its membrane-proximal epitope. These structural insights should assist in the design of immunogens to elicit 4E10-like neutralizing responses.

Structure of the cytosolic Cu,Zn superoxide dismutase from Schistosoma mansoni.

Cu,Zn superoxide dismutase (Cu,Zn SOD) is an essential enzyme for protecting cells from the toxic effects of reactive oxygen species. In humans, two distinct Cu,Zn SOD genes are located on chromosomes 4 and 21 and mutations in the latter have been associated with familial amyotrophic lateral sclerosis. Similarly, schistosomes (trematode parasites responsible for the chronically debilitating disease schistosomiasis) also produce two distinct Cu,Zn SODs, in this case one cytosolic and one bearing a signal peptide. The crystal structure of the cytosolic form of the enzyme from the human trematode Schistosoma mansoni (SmCtSOD) was solved and refined to a resolution of 2.2 A (space group P2(1)2(1)2(1), R = 17.6% and R(free) = 24.1%) and 1.55 A (space group P2(1), R = 15.7% and R(free) = 17.1%). This is the first report of a crystal structure of a Cu,Zn superoxide dismutase derived from a human parasite. Alternate positions for the catalytic copper and its water ligand were refined for the 1.55 A SmCtSOD model, but the most interesting structural differences between SmCtSOD and the human homologue reside in the loops used for electrostatic guidance of the substrate to the enzyme active site.

ALS mutants of human superoxide dismutase form fibrous aggregates via framework destabilization.

Many point mutations in human Cu,Zn superoxide dismutase (SOD) cause familial amyotrophic lateral sclerosis (FALS), a fatal neurodegenerative disorder in heterozygotes. Here we show that these mutations cluster in protein regions influencing architectural integrity. Furthermore, crystal structures of SOD wild-type and FALS mutant H43R proteins uncover resulting local framework defects. Characterizations of beta-barrel (H43R) and dimer interface (A4V) FALS mutants reveal reduced stability and drastically increased aggregation propensity. Moreover, electron and atomic force microscopy indicate that these defects promote the formation of filamentous aggregates. The filaments resemble those seen in neurons of FALS patients and bind both Congo red and thioflavin T, suggesting the presence of amyloid-like, stacked beta-sheet interactions. These results support free-cysteine-independent aggregation of FALS mutant SOD as an integral part of FALS pathology. They furthermore provide a molecular basis for the single FALS disease phenotype resulting from mutations of diverse side-chains throughout the protein: many FALS mutations reduce structural integrity, lowering the energy barrier for fibrous aggregation.