Memantine prevents reference and working memory impairment caused by sleep deprivation in both young and aged Octodon degus.

Memory loss is one of the key features of cognitive impairment in either aging, Mild Cognitive Impairment (MCI) or dementia. Pharmacological treatments for memory loss are today focused on addressing symptomatology. One of these approved compounds is memantine, a partial NMDA receptor antagonist that has proved its beneficial effects in cognition. The Octodon degus (O. degus) has been recently proposed as a potential model relevant for neurodegenerative diseases. However, there are no previous studies investigating the effect of pharmacological treatments for age-related cognitive impairment in this rodent. In this work we aimed to evaluate the effect of memantine on sleep deprivation (SD)-induced memory impairment in young and old O. degus. Young and old animals were trained in different behavioral paradigms validated for memory evaluation, and randomly assigned to a control (CTL, n=14) or an SD (n=14) condition, and treated with vehicle or memantine (10-mg/Kg i.p.) before the SD started. We demonstrate that SD impairs memory in both young and old animals, although the effect in the old group was significantly more severe (P<0.05). Memantine pretreatment was able to prevent the cognitive impairment caused by SD in both age groups, while it had no negative effect on CTL animals. The positive effect of memantine in counteracting the negative effect of SD on the retrieval process even in the aged O. degus further supports the translational potential of both the challenge and the species, and will enable a better understanding of the behavioral features of memantine effects, especially related with reference and working memories.

A new surface plasmon resonance-based immunoassay for rapid, reproducible and sensitive quantification of pentraxin-3 in human plasma.

A new immunoassay based on surface plasmon resonance (SPR) for the rapid, reproducible and sensitive determination of pentraxin-3 (PTX3) levels in human plasma has been developed and characterized. The method involves a 3-min flow of plasma over a sensor chip pre-coated with a monoclonal anti-PTX3 antibody (MNB4), followed by a 3-min flow of a polyclonal anti-PTX3 antibody (pAb), required for specific recognition of captured PTX3. The SPR signal generated with this secondary antibody linearly correlates with the plasma PTX3 concentration, in the range of 5-1500 ng/mL, with a lowest limit of detection of 5 ng/mL. The PTX3 concentrations determined with the SPR-based immunoassay in the plasma of 21 patients with sepsis, ranging 15-1600 ng/mL, were superimposable to those found in a classic ELISA immunoassay. Since the PTX3 concentration in the plasma of healthy subjects is <2 ng/mL, but markedly rises in certain medical conditions, the method is useful to quantify pathological levels of this important biomarker, with important diagnostic applications. In comparison with the classic ELISA, the SPR-based approach is much faster (30 min versus 4-5 h) and could be exploited for the development of new cost-effective SPR devices for point-of-care diagnosis.

Ranolazine ameliorates postresuscitation electrical instability and myocardial dysfunction and improves survival with good neurologic recovery in a rat model of cardiac arrest.

BACKGROUND: During ischemia, enhancement of the "late Na+ current" (I(NaL)) contributes to intracellular Ca2+ overload. Dysregulation of intracellular Ca2+ homeostasis plays a critical role in the pathophysiology of cardiac arrest and cardiopulmonary resuscitation (CPR), leading to ventricular arrhythmias and left ventricle (LV) dysfunction. OBJECTIVE: The purpose of this study was to investigate the effects of the I(NaL) blocker ranolazine on outcome of CPR in a rat model. We hypothesized that ranolazine might reduce postresuscitation arrhythmias and improve survival and recovery. METHODS: Eighteen rats were assigned to receive intravenous ranolazine 10 mg/kg or vehicle. Ventricular fibrillation was induced and untreated for 8 minutes. CPR then was performed for 8 minutes. ECG and arterial and right atrial pressures were monitored up to 3 hours after CPR. After resuscitation, LV function was monitored by echocardiography, and 72-hour survival with neurologic recovery was evaluated. Plasma was obtained for biomarkers of heart and brain injury. RESULTS: All animals in the ranolazine group were resuscitated and survived up to 72 hours, whereas 72% in the vehicle group were resuscitated but 54% survived. The period of postresuscitation arrhythmia with hemodynamic instability was shorter in the ranolazine group compared to vehicle group (P < .02). Seventy-two hours after resuscitation, LV systolic and diastolic functions were better in the ranolazine group compared to vehicle (P < .05). Full neurologic recovery was observed in all ranolazine animals, whereas neurologic impairment persisted in the vehicle group (P < .02). CONCLUSION: In this model, ranolazine pretreatment reduced postresuscitation electrical and hemodynamic instability and improved 72-hour postresuscitation LV function and survival with good neurologic recovery.

Doxycycline in Creutzfeldt-Jakob disease: a phase 2, randomised, double-blind, placebo-controlled trial.

BACKGROUND: Creutzfeldt-Jakob disease (CJD) is a fatal, untreatable prion encephalopathy. Previous studies showed that doxycycline is effective in in-vitro and in-vivo models of disease, and patients with CJD who received compassionate treatment with doxycycline showed increased survival time compared with historical series. We therefore did a randomised, double-blind study of doxycycline versus placebo in CJD. METHODS: We recruited patients older than 18 years old who had a diagnosis of definite or probable sporadic CJD or genetic forms of the disease via Italian reference centres and the French national referral system. Patients were randomly assigned (ratio 1:1) to receive oral doxycycline (100 mg daily) or placebo under double-blind conditions from the day of randomisation to death. Centralised randomisation was done independently of enrolment or evaluation of patients using a minimisation method in Italy and a simple randomisation in France. Participants, caregivers, and clinicians were masked to group assignment. The primary efficacy variable was the survival time from randomisation. Interim analyses were planned to detect a significant effect of treatment as early as possible. This trial is registered with EudraCT, 2006-001858-27 for the Italian study and 2007-005553-34 for the French study. FINDINGS: From April 12, 2007, to Aug 19, 2010, in Italy, and from Jan 30, 2009, to Jan 10, 2012, in France, 121 patients with CJD were enrolled in the study, 62 of whom were randomly assigned to the treatment group and 59 to the placebo group. The first interim analysis showed absence of superiority of doxycycline compared with placebo, and the trial was stopped for futility. Efficacy analyses did not show significant differences between patients treated with doxycycline and placebo with regard to survival times (HR 1.1, 95% CI 0.8-1.7, p=0.50). Serious adverse events were judged not to be related to treatment, whereas a relation was deemed probable or possible for five non-serious adverse events that occurred in each treatment group. INTERPRETATION: Doxycycline at a dose of 100 mg per day was well tolerated but did not significantly affect the course of CJD, at variance with the results of previous observational studies. Our experience could be useful in the design of large multinational controlled trials of potential anti-prion molecules in this rare disease. FUNDING: Agenzia Italiana Farmaco, Italian Ministry of Health, AIEnP, and French Ministry of Health.

Blood protein coating of gold nanoparticles as potential tool for organ targeting.

Nanoparticles (NP) and nanoparticulated drug delivery promise to be the breakthrough for therapy in medicine but raise concerns in terms of nanotoxicity. We present quantitative murine biokinetics assays using polyelectrolyte-multilayer-coated gold NP (AuNP, core diameter 15 and 80 nm; (198)Au radio-labeled). Those were stably conjugated either with human serum albumin (alb-AuNP) or apolipoprotein E (apoE-AuNP), prior to intravenous injection. We compare the biokinetics of protein-AuNP-conjugates with citrate-stabilized AuNP (cit-AuNP). Biokinetics was complemented with histology in organs with high AuNP content using 15 nm double fluorescently-labeled alb-AuNP-conjugates. Protein conjugation massively reduced liver retention (alb-AuNP: 52%, apoE-AuNP: 72%, cit-AuNP: >95%, at 19 h and 48 h) when compared to cit-AuNP. The protein conjugates were retained in lungs (alb-AuNP (18%) and spleen (alb-AuNP (16%), apoE-AuNP (21%) at 19 h. Alb-AuNP show significantly increased fractions in lungs (factors: 60 (30 min); 111 (19 h); 235 (48 h) and brain (factors: 70 (30 min); 90 (19 h); >200 (48 h) compared to cit-AuNP (control) - or even to apoE-AuNP. The influence of protein conjugation on the biodistribution disappears for 80 nm AuNP comparing to control. Histologically, the 15 nm alb-AuNP are mainly located in the endothelium of brain, lungs, liver and kidneys after 30 min, while at 19 h they moved deeper into the parenchyma e.g. in hippocampus. Our study clearly suggests that stable conjugation of AuNP with albumin and apoE prior to intravenous administration increases specificity and efficiency of NP in diseased target-organs thus suggesting a potential role in nanomedicine and nanopharmacology.

Selective nanovector mediated treatment of activated proinflammatory microglia/macrophages in spinal cord injury.

Much evidence shows that acute and chronic inflammation in spinal cord injury (SCI), characterized by immune cell infiltration and release of inflammatory mediators, is implicated in development of the secondary injury phase that occurs after spinal cord trauma and in the worsening of damage. Activation of microglia/macrophages and the associated inflammatory response appears to be a self-propelling mechanism that leads to progressive neurodegeneration and development of persisting pain state. Recent advances in polymer science have provided a huge amount of innovations leading to increased interest for polymeric nanoparticles (NPs) as drug delivery tools to treat SCI. In this study, we tested and evaluated in vitro and in vivo a new drug delivery nanocarrier: minocycline loaded in NPs composed by a polymer based on poly-ε-caprolactone and polyethylene glycol. These NPs are able to selectively target and modulate, specifically, the activated proinflammatory microglia/macrophages in subacute progression of the secondary injury in SCI mouse model. After minocycline-NPs treatment, we demonstrate a reduced activation and proliferation of microglia/macrophages around the lesion site and a reduction of cells with round shape phagocytic-like phenotype in favor of a more arborized resting-like phenotype with low CD68 staining. Treatment here proposed limits, up to 15 days tested, the proinflammatory stimulus associated with microglia/macrophage activation. This was demonstrated by reduced expression of proinflammatory cytokine IL-6 and persistent reduced expression of CD68 in traumatized site. The nanocarrier drug delivery tool developed here shows potential advantages over the conventionally administered anti-inflammatory therapy, maximizing therapeutic efficiency and reducing side effects.

6-methoxy-7-benzofuranoxy and 6-methoxy-7-indolyloxy analogues of 2-[2-(2,6-Dimethoxyphenoxy)ethyl]aminomethyl-1,4-benzodioxane (WB4101):1 discovery of a potent and selective α1D-adrenoceptor antagonist.

Previous results have shown that replacement of one of the two o-methoxy groups at the phenoxy residue of the potent, but not subtype-selective, α1-AR antagonist (S)-WB4101 [(S)-1] by phenyl, or by ortho,meta-fused cyclohexane, or especially by ortho,meta-fused benzene preferentially elicits α1D-AR antagonist affinity. Such observations inspired the design of four new analogues of 1 bearing, in lieu of the 2,6-dimethoxyphenoxy residue, a 6-methoxy-substituted 7-benzofuranoxy or 7-indolyloxy group or, alternatively, their corresponding 2,3-dihydro form. Of these new compounds, which maintain, rigidified, the characteristic ortho heterodisubstituted phenoxy substructure of 1, the S enantiomer of the dihydrobenzofuranoxy derivative exhibited the highest α1D-AR antagonist affinity (pA2 9.58) with significant α1D/α1A and α1D/α1B selectivity. In addition, compared both to α1D-AR antagonists structurally related to 1 and to the well-known α1D-AR antagonist BMY7378, this derivative had modest 5-HT1A affinity and neutral α1-AR antagonist behavior.

A novel spirocyclic tropanyl-Δ²-isoxazoline derivative enhances citalopram and paroxetine binding to serotonin transporters as well as serotonin uptake.

A group of spirocyclic tropanyl-Δ(2)-isoxazolines was synthesized exploiting the 1,3-dipolar cycloaddition of nitrile oxides to olefins. Their interaction with the dopamine and serotonin transporters (DAT and SERT, respectively) was evaluated through binding experiments. The majority of the compounds had no inhibitory effects (IC(50) >> 10 µM), while some had an IC(50) value in the range 5-10 µM (8a-c, 10b and 11c on DAT, 12b on SERT). Unexpectedly, one of the tertiary amines under investigation, that is 3'-methoxy-8-methyl-spiro{8-azabicyclo[3.2.1]octane-3,5'(4'H)-isoxazole 7a, was able to enhance at a concentration of 10 µM both [(3)H]citalopram and [(3)H]paroxetine binding to SERT in rat brain homogenate (up to 25%, due to an increase of B(max)) and [(3)H]serotonin uptake (up to 30%) in cortical synaptosomes. This peculiar pharmacological profile of 7a suggests it binds to an allosteric site on SERT, and positions derivative 7a as a very useful tool to investigate SERT machinery.

Versatile and efficient targeting using a single nanoparticulate platform: application to cancer and Alzheimer's disease.

A versatile and efficient functionalization strategy for polymeric nanoparticles (NPs) has been reported and successfully applied to PEGylated, biodegradable poly(alkyl cyanoacrylate) (PACA) nanocarriers. The relevance of this platform was demonstrated in both the fields of cancer and Alzheimer's disease (AD). Prepared by copper-catalyzed azide-alkyne cycloaddition (CuAAC) and subsequent self-assembly in aqueous solution of amphiphilic copolymers, the resulting functionalized polymeric NPs exhibited requisite characteristics for drug delivery purposes: (i) a biodegradable core made of poly(alkyl cyanoacrylate), (ii) a hydrophilic poly(ethylene glycol) (PEG) outer shell leading to colloidal stabilization, (iii) fluorescent properties provided by the covalent linkage of a rhodamine B-based dye to the polymer backbone, and (iv) surface functionalization with biologically active ligands that enabled specific targeting. The construction method is very versatile and was illustrated by the coupling of a small library of ligands (e.g., biotin, curcumin derivatives, and antibody), resulting in high affinity toward (i) murine lung carcinoma (M109) and human breast cancer (MCF7) cell lines, even in a coculture environment with healthy cells and (ii) the ß-amyloid peptide 1-42 (Aß(1-42)), believed to be the most representative and toxic species in AD, both under its monomeric and fibrillar forms. In the case of AD, the ligand-functionalized NPs exhibited higher affinity toward Aß(1-42) species comparatively to other kinds of colloidal systems and led to significant aggregation inhibition and toxicity rescue of Aß(1-42) at low molar ratios.

PEGylated nanoparticles bind to and alter amyloid-beta peptide conformation: toward engineering of functional nanomedicines for Alzheimer's disease.

We have demonstrated that the polyethylene glycol (PEG) corona of long-circulating polymeric nanoparticles (NPs) favors interaction with the amyloid-beta (Aß(1-42)) peptide both in solution and in serum. The influence of PEGylation of poly(alkyl cyanoacrylate) and poly(lactic acid) NPs on the interaction with monomeric and soluble oligomeric forms of Aß(1-42) peptide was demonstrated by capillary electrophoresis, surface plasmon resonance, thioflavin T assay, and confocal microscopy, where the binding affected peptide aggregation kinetics. The capture of peptide by NPs in serum was also evidenced by fluorescence spectroscopy and ELISA. Moreover, in silico and modeling experiments highlighted the mode of PEG interaction with the Aß(1-42) peptide and its conformational changes at the nanoparticle surface. Finally, Aß(1-42) peptide binding to NPs affected neither complement activation in serum nor apolipoprotein-E (Apo-E) adsorption from the serum. These observations have crucial implications in NP safety and clearance kinetics from the blood. Apo-E deposition is of prime importance since it can also interact with the Aß(1-42) peptide and increase the affinity of NPs for the peptide in the blood. Collectively, our results suggest that these engineered long-circulating NPs may have the ability to capture the toxic forms of the Aß(1-42) peptide from the systemic circulation and potentially improve Alzheimer's disease condition through the proposed "sink effect".

Mutant PrP suppresses glutamatergic neurotransmission in cerebellar granule neurons by impairing membrane delivery of VGCC α(2)δ-1 Subunit.

How mutant prion protein (PrP) leads to neurological dysfunction in genetic prion diseases is unknown. Tg(PG14) mice synthesize a misfolded mutant PrP which is partially retained in the neuronal endoplasmic reticulum (ER). As these mice age, they develop ataxia and massive degeneration of cerebellar granule neurons (CGNs). Here, we report that motor behavioral deficits in Tg(PG14) mice emerge before neurodegeneration and are associated with defective glutamate exocytosis from granule neurons due to impaired calcium dynamics. We found that mutant PrP interacts with the voltage-gated calcium channel α(2)δ-1 subunit, which promotes the anterograde trafficking of the channel. Owing to ER retention of mutant PrP, α(2)δ-1 accumulates intracellularly, impairing delivery of the channel complex to the cell surface. Thus, mutant PrP disrupts cerebellar glutamatergic neurotransmission by reducing the number of functional channels in CGNs. These results link intracellular PrP retention to synaptic dysfunction, indicating new modalities of neurotoxicity and potential therapeutic strategies.

Applications of surface plasmon resonance (SPR) for the characterization of nanoparticles developed for biomedical purposes.

Great interest is currently being devoted to the development of nanoparticles (NPs) for biomedical purposes, designed to improve the pharmacokinetic profile of their cargos (either imaging probes or drugs) and to enhance the specific targeting at the disease site. Recent works suggest that Surface Plasmon Resonance (SPR), widely used for the analysis of biomolecular interactions, represents a technique of choice for rapid and quantitative analyses of the interaction between NPs--functionalized with specific ligands--and their putative biological targets. Moreover, SPR can provide important details on the formation and the role of the protein "corona", i.e., the protein layer which coats NPs once they come into contact with biological fluids. These novel applications of SPR sensors may be very useful to characterize, screen and develop nanodevices for biomedical purposes.

The binding affinity of anti-Aß1-42 MAb-decorated nanoliposomes to Aß1-42 peptides in vitro and to amyloid deposits in post-mortem tissue.

Amyloid ß (Aß) aggregates are considered as possible targets for therapy and/or diagnosis of Alzheimer disease (AD), and nanoparticles functionalized with Aß-specific ligands are considered promising vehicles for imaging probes and therapeutic agents. Herein, we characterized the binding properties of nanoliposomes decorated with an anti-Aß monoclonal antibody (Aß-MAb). The Aß-MAb was obtained in mice by immunization with Aß antigen followed by hybridoma fusion. Surface Plasmon Resonance (SPR) studies confirmed the very high affinity of purified Aß-MAb for both Aß monomers and fibrils (K(D) = 0.08 and 0.13 nm, respectively). The affinity of the biotinylated Aß-MAb, used thereafter for liposome decoration, was lower although still in the low nanomolar range (K(D) = 2.1 and 1.6 nm, respectively). Biotin-streptavidin ligation method was used to decorate nanoliposomes with Aß-MAb, at different densities. IgG-decorated liposomes were generated by the same methodology, as control. Vesicles were monodisperse with mean diameters 124-134 nm and demonstrated good colloidal stability and integrity when incubated with serum proteins. When studied by SPR, Aß-MAb-liposomes, but not IgG-liposomes, markedly bound to Aß monomers and fibrils, immobilized on the chip. K(D) values (calculated on Aß-MAb content) were about 0.5 and 2 nm with liposomes at high and low Aß-MAb density, respectively. Aß-MAb-liposome binding to Aß fibrils was additionally confirmed by ultracentrifugation technique, in which interactions occur in solution under physiological conditions. Moreover, Aß-MAb-liposomes bound amyloid deposits in post-mortem AD brain samples, confirming the potential of these nanoparticles for the diagnosis and therapy of AD.

Curcumin-decorated nanoliposomes with very high affinity for amyloid-ß1-42 peptide.

Amyloid ß (Aß) aggregates are considered as possible targets for therapy and/or diagnosis of Alzheimer disease (AD). It has been previously shown that curcumin targets Aß plaques and interferes with their formation, suggesting a potential role for prevention or treatment of AD. Herein, a click chemistry method was used to generate nanoliposomes decorated with a curcumin derivative, designed to maintain the planar structure required for interaction with Aß, as directly confirmed by Surface Plasmon Resonance experiments. Another type of liposomes was formed starting from curcumin-phospholipid conjugate, in which the planar structure of curcumin is disrupted. Both types of generated curcumin-decorated vesicles had mean diameters in the nano range (131-207 nm) and slightly negative ζ-potential values according to their lipid composition, and were stable for periods up to 20 days. They also demonstrated high integrity during incubation in presence of plasma proteins. Surface Plasmon Resonance experiments, measuring the binding of flowing liposomes to immobilized Aß1-42, indicated that the liposomes exposing the curcumin derivative (maintaining the planarity) have extremely high affinity for Aß1-42 fibrils (1-5 nM), likely because of the occurrence of multivalent interactions, whereas those exposing non-planar curcumin did not bind to Aß1-42. In summary, we describe here the preparation and characterization of new nanoparticles with a very high affinity for Aß1-42 fibrils, to be exploited as vectors for the targeted delivery of new diagnostic and therapeutic molecules for AD.

New method based on capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) to monitor interaction between nanoparticles and the amyloid-ß peptide.

A novel application of capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) was proposed to efficiently detect and monitor the interaction between polymeric nanoparticles and the ß-Amyloid peptide (Aß(1-42)), a biomarker for Alzheimer's Disease (AD), at concentrations close to physiological conditions. The CE-LIF method allowed the interaction between PEGylated poly(alkyl cyanoacrylate) nanoparticles (NPs) and the soluble Aß(1-42) peptide monomers to be highlighted. These results were confirmed by surface plasmon resonance (SPR) and confocal laser scanning microscopy (CLSM). Whereas SPR showed an interaction between the NPs and the Aß(1-42) peptide, CLSM allowed the formation of large aggregates/assemblies at high NP and peptide concentrations to be visualized. All these results suggested that these nanoparticles could bind the Aß(1-42) peptide and influence its aggregation kinetics. Interestingly, the non-PEGylated poly(alkyl cyanoacrylate) NPs did not alter the aggregation kinetics of the Aß(1-42) peptide, thus emphasizing the high level of discrimination of the CE-LIF method with respect to NPs.

Lipid-based nanoparticles with high binding affinity for amyloid-beta1-42 peptide.

The neurotoxic beta-amyloid peptide (Abeta), formed in anomalous amounts in Alzheimer's disease (AD), is released as monomer and then undergoes aggregation forming oligomers, fibrils and plaques in diseased brains. Abeta aggregates are considered as possible targets for therapy and/or diagnosis of AD. Since nanoparticles (NPs) are promising vehicles for imaging probes and therapeutic agents, we realized and characterized two types of NPs (liposomes and solid lipid nanoparticles, 145 and 76 nm average size, respectively) functionalized to target Abeta(1-42) with high affinity. Preliminary immunostaining studies identified anionic phospholipids [phosphatidic acid (PA) and cardiolipin (CL)] as suitable Abeta(1-42) ligands. PA/CL-functionalized, but not plain, NPs interacted with Abeta(1-42) aggregates as indicated by ultracentrifugation experiments, in which binding reaction occurred in solution, and by Surface Plasmon Resonance (SPR) experiments, in which NPs flowed onto immobilized Abeta(1-42). All these experiments were carried out in buffered saline. SPR studies indicated that, when exposed on NPs surface, PA/CL display very high affinity for Abeta(1-42) fibrils (22-60 nm), likely because of the occurrence of multivalent interactions which markedly decrease the dissociation of PA/CL NPs from Abeta. Noteworthy, PA/CL NPs did not bind to bovine serum albumin. The PA/CL NPs described in this work are endowed with the highest affinity for Abeta so far reported. These characteristics make our NPs a very promising vector for the targeted delivery of potential new diagnostic and therapeutic molecules to be tested in appropriate animal models.

Development of a proteolytically stable retro-inverso peptide inhibitor of beta-amyloid oligomerization as a potential novel treatment for Alzheimer's disease.

The formation of beta-amyloid (Abeta) deposits in the brain is likely to be a seminal step in the development of Alzheimer's disease. Recent studies support the hypothesis that Abeta soluble oligomers are toxic to cells and have potent effects on memory and learning. Inhibiting the early stages of Abeta aggregation could, therefore, provide a novel approach to treating the underlying cause of AD. We have designed a retro-inverso peptide (RI-OR2, H(2)N-r<--G<--k<--l<--v<--f<--f<--G<--r-Ac), based on a previously described inhibitor of Abeta oligomer formation (OR2, H(2)N-R-G-K-L-V-F-F-G-R-NH(2)). Unlike OR2, RI-OR2 was highly stable to proteolysis and completely resisted breakdown in human plasma and brain extracts. RI-OR2 blocked the formation of Abeta oligomers and fibrils from extensively deseeded preparations of Abeta(1-40) and Abeta(1-42), as assessed by thioflavin T binding, an immunoassay method for Abeta oligomers, SDS-PAGE separation of stable oligomers, and atomic force microscopy, and was more effective against Abeta(1-42) than Abeta(1-40). In surface plasmon resonance experiments, RI-OR2 was shown to bind to immobilized Abeta(1-42) monomers and fibrils, with an apparent K(d) of 9-12 muM, and also acted as an inhibitor of Abeta(1-42) fibril extension. In two different cell toxicity assays, RI-OR2 significantly reversed the toxicity of Abeta(1-42) toward cultured SH-SY5Y neuroblastoma cells. Thus, RI-OR2 represents a strong candidate for further development as a novel treatment for Alzheimer's disease.