Malignant Primary and Metastatic Cardiac Tumors: A Single-Center 27-Year Case Review.

BACKGROUND: Malignant primary cardiac tumors are exceedingly rare, and despite surgical exeresis or chemotherapy, their prognosis remains poor. Cardiac invasion by metastatic tumors, while more common, also entails an unsatisfactory outcome. This study aimed to review patients diagnosed with malignant primary and secondary cardiac tumors in a tertiary center between 1995 and 2022. METHODS: Clinical data, echocardiographic, computed tomography, and magnetic resonance assessments of tumor location and morphology, histology, treatment, and survival were retrospectively analyzed. RESULTS: Sixty malignant cardiac tumors were diagnosed: 17 primary (A) and 43 metastatic (B) tumors. A: the most common types were angiosarcoma (41%), undifferentiated sarcoma (23%), and fibrosarcoma (18%). Patients with primary tumors were younger than patients with metastatic tumors (41 ± 13 years vs. 57 ± 18 years, p = 0.001), with no significant gender difference. The most frequent presentations were heart failure (59%) and arrhythmia (23%). The most prevalent tumor location was the right heart chambers (71%), mostly in the right atrium (35%). 47% were submitted to tumor resection, and 29% received chemotherapy. The mortality rate was 82% with a median survival of 6.0 (interquartile range: 1.0-11.8) months after diagnosis (minimum of 12 days and maximum of 19 years). One patient with fibrosarcoma underwent heart transplantation and was still alive and well after 19 years. B: regarding metastatic cardiac invasion, the most common primary tumor sites were lung carcinomas (38%), thymomas (17%), and lymphomas (14%). Presentation with pericardial effusion was common (33%). The mortality rate was 72%, with a median survival of 3.6 (1.0-13.4) months (minimum of 7 days, maximum of 5 years). CONCLUSION: Diagnosis of metastatic cardiac tumors was more common than that of malignant primary tumors, both with a dismal prognosis. When radical exeresis is not possible, heart transplantation can be an option with a favorable outcome in carefully selected patients with sarcomas.

Binding of common organic UV-filters to the thyroid hormone transport protein transthyretin using in vitro and in silico studies: Potential implications in health.

Several anthropogenic contaminants have been identified as competing with the thyroid hormone thyroxine (T4) for binding to transport proteins as transthyretin (TTR). This binding can potentially create toxicity mechanisms posing a threat to human health. Many organic UV filters (UVFs) and paraben preservatives (PBs), widely used in personal care products, are chemicals of emerging concern due to their adverse effects as potential thyroid-disrupting compounds. Recently, organic UVFs have been found in paired maternal and fetal samples and PBs have been detected in placenta, which opens the possibility of the involvement of TTR in the transfer of these chemicals across physiological barriers. We aimed to investigate a discrete set of organic UVFs and PBs to identify novel TTR binders. The binding affinities of target UVFs towards TTR were evaluated using in vitro T4 competitive binding assays. The ligand-TTR affinities were determined by isothermal titration calorimetry (ITC) and compared with known TTR ligands. In parallel, computational studies were used to predict the 3-D structures of the binding modes of these chemicals to TTR. Some organic UVFs, compounds 2,2',4,4'-tetrahydroxybenzophenone (BP2, Kd = 0.43 µM); 2,4-dihydroxybenzophenone (BP1, Kd = 0.60 µM); 4,4'-dihydroxybenzophenone (4DHB, Kd = 0.83 µM), and 4-hydroxybenzophenone (4HB, Kd = 0.93 µM), were found to display a high affinity to TTR, being BP2 the strongest TTR binder (ΔH = -14.93 Kcal/mol). Finally, a correlation was found between the experimental ITC data and the TTR-ligand docking scores obtained by computational studies. The approach integrating in vitro assays and in silico methods constituted a useful tool to find TTR binders among common organic UVFs. Further studies on the involvement of the transporter protein TTR in assisting the transplacental transfer of these chemicals across physiological barriers and the long-term consequences of prenatal exposure to them should be pursued.

Infective endocarditis in a cohort of adult CHD patients.

BACKGROUND: CHD increases the risk of infective endocarditis due to the substrate of prosthetic materials and residual lesions. However, lesion-specific and mortality risks data are lacking. We sought to analyse clinical course and mortality of infective endocarditis in a cohort of adult CHD. METHODS: Retrospective analysis of all cases of proven and probable infective endocarditis (Duke's criteria) followed in our adult CHD clinic between 1970 and August, 2021. Epidemiological, clinical and imaging data were analysed. Predictors of surgical treatment and mortality were assessed using regression analysis. RESULTS: During a mean follow-up of 15.8 ± 10.9 years, 96 patients had 105 infective endocarditis episodes, half with previous cardiac surgery (corrective or palliative). The most frequent diagnoses were: ventricular septal defect, bicuspid aortic valve, Tetralogy of Fallot and pulmonary atresia. The site of infection was identified by echocardiography in 82 episodes (91%), most frequently in aortic (n = 27), tricuspid (n = 15), and mitral (n = 13) valves. Blood cultures were positive in 79% of cases, being streptococci (n = 29) and staphylococci (n = 23) the predominant pathogens. Surgery was necessary in 40% and the in-hospital mortality was 10.5%, associated with heart failure (p < 0.001; OR 13.5) and a non-surgical approach (p = 0.003; OR 5.06). CONCLUSIONS: In an adult CHD cohort, infective endocarditis was more frequent in patients with ventricular septal defect and bicuspid aortic valves, which contradicts the current guidelines that excludes them from prophylaxis. Surgical treatment is often required and mortality remains substantial. Prevention of this serious complication should be one of the major tasks in the care of adults with CHD.

Vitamin D concentrations from neonatal dried blood spots and the risk of early-onset type 2 diabetes in the Danish D-tect case-cohort study.

AIMS/HYPOTHESIS: The aim of this study was to examine the influence of neonatal vitamin D concentration on the development of early-onset type 2 diabetes in a large population sample. METHODS: We conducted a case-cohort study utilising data from the Danish biobank and registers. Neonatal vitamin D was assessed measuring 25-hydroxyvitamin D3 [25(OH)D3] concentrations on the dried blood spot samples from the Biological Specimen Bank for Neonatal Screening. Cases of type 2 diabetes (n = 731) were retrieved from the Danish National Patient Register for all individuals born in Denmark between 1 May 1981 and 31 December 1992. The sub-cohort (n = 1765) was randomly selected from all children born in the same period. We used a weighted Cox proportional hazard model assessing the hazard of first type 2 diabetes diagnoses by quintiles of 25(OH)D3 and restricted cubic spline. RESULTS: The median 25(OH)D3 concentration (IQR) among cases was 21.3 nmol/l (13.3-34.1) and 23.9 nmol/l (13.7-35.7) in the sub-cohort. There was no indication of a potential lower risk of early-onset type 2 diabetes among individuals in the higher quintile of vitamin D concentration compared with the lowest (HRcrude 0.97 [95% CI 0.71, 1.33] p = 0.85; HRadjusted 1.29 [95% CI 0.92, 1.83] p = 0.14). CONCLUSIONS/INTERPRETATION: The results of this study do not support the hypothesis that higher neonatal vitamin D concentrations are associated with a lower risk of early-onset type 2 diabetes in adulthood.

Bridging Cyanobacteria to Neurodegenerative Diseases: A New Potential Source of Bioactive Compounds against Alzheimer's Disease.

Neurodegenerative diseases (NDs) represent a drawback in society given the ageing population. Dementias are the most prevalent NDs, with Alzheimer's disease (AD) representing around 70% of all cases. The current pharmaceuticals for AD are symptomatic and with no effects on the progression of the disease. Thus, research on molecules with therapeutic relevance has become a major focus for the scientific community. Cyanobacteria are a group of photosynthetic prokaryotes rich in biomolecules with confirmed activity in pathologies such as cancer, and with feasible potential in NDs such as AD. In this review, we aimed to compile the research works focused in the anti-AD potential of cyanobacteria, namely regarding the inhibition of the enzyme ß-secretase (BACE1) as a fundamental enzyme in the generation of ß-amyloid (Aß), the inhibition of the enzyme acetylcholinesterase (AChE) lead to an increase in the availability of the neurotransmitter acetylcholine in the synaptic cleft and the antioxidant and anti-inflammatory effects, as phenomena associated with neurodegeneration mechanisms.

Exploring the Physiological Role of Transthyretin in Glucose Metabolism in the Liver.

Transthyretin (TTR), a 55 kDa evolutionarily conserved protein, presents altered levels in several conditions, including malnutrition, inflammation, diabetes, and Alzheimer's Disease. It has been shown that TTR is involved in several functions, such as insulin release from pancreatic ß-cells, recovery of blood glucose and glucagon levels of the islets of Langerhans, food intake, and body weight. Here, the role of TTR in hepatic glucose metabolism was explored by studying the levels of glucose in mice with different TTR genetic backgrounds, namely with two copies of the TTR gene, TTR+/+; with only one copy, TTR+/-; and without TTR, TTR-/-. Results showed that TTR haploinsufficiency (TTR+/-) leads to higher glucose in both plasma and in primary hepatocyte culture media and lower expression of the influx glucose transporters, GLUT1, GLUT3, and GLUT4. Further, we showed that TTR haploinsufficiency decreases pyruvate kinase M type (PKM) levels in mice livers, by qRT-PCR, but it does not affect the hepatic production of the studied metabolites, as determined by 1H NMR. Finally, we demonstrated that TTR increases mitochondrial density in HepG2 cells and that TTR insufficiency triggers a higher degree of oxidative phosphorylation in the liver. Altogether, these results indicate that TTR contributes to the homeostasis of glucose by regulating the levels of glucose transporters and PKM enzyme and by protecting against mitochondrial oxidative stress.

An Assay for Screening Potential Drug Candidates for Alzheimer's Disease That Act as Chaperones of the Transthyretin and Amyloid-ß Peptides Interaction.

The protein transthyretin (TTR) modulates amyloid-ß (Aß) peptides deposition and processing and this physiological effect is further enhanced by treatment with iododiflunisal (IDIF), a small-molecule compound (SMC) with TTR tetramer stabilization properties, which behaves as chaperone of the complex. This knowledge has prompted us to design and optimize a rapid and simple high-throughput assay that relies on the ability of test compounds to form ternary soluble complexes TTR/Aß/SMC that prevent Aß aggregation. The method uses the shorter Aß(12-28) sequence which is cheaper and simpler to use while retaining the aggregation properties of their parents Aß(1-40) and Aß(1-42). The test is carried out in 96-plate wells that are UV monitored for turbidity during 6 h. Given its reproducibility, we propose that this test can be a powerful tool for efficient screening of SMCs that act as chaperones of the TTR/Aß interaction that may led to potential AD therapies.

Undiscovered Roles for Transthyretin: From a Transporter Protein to a New Therapeutic Target for Alzheimer's Disease.

Transthyretin (TTR), an homotetrameric protein mainly synthesized by the liver and the choroid plexus, and secreted into the blood and the cerebrospinal fluid, respectively, has been specially acknowledged for its functions as a transporter protein of thyroxine and retinol (the latter through binding to the retinol-binding protein), in these fluids. Still, this protein has managed to stay in the spotlight as it has been assigned new and varied functions. In this review, we cover knowledge on novel TTR functions and the cellular pathways involved, spanning from neuroprotection to vascular events, while emphasizing its involvement in Alzheimer's disease (AD). We describe details of TTR as an amyloid binding protein and discuss its interaction with the amyloid Aß peptides, and the proposed mechanisms underlying TTR neuroprotection in AD. We also present the importance of translating advances in the knowledge of the TTR neuroprotective role into drug discovery strategies focused on TTR as a new target in AD therapeutics.

Repurposing Benzbromarone for Familial Amyloid Polyneuropathy: A New Transthyretin Tetramer Stabilizer.

Transthyretin (TTR) is a homotetrameric protein involved in human amyloidosis, including familial amyloid polyneuropathy (FAP). Discovering small-molecule stabilizers of the TTR tetramer is a therapeutic strategy for these diseases. Tafamidis, the only approved drug for FAP treatment, is not effective for all patients. Herein, we discovered that benzbromarone (BBM), a uricosuric drug, is an effective TTR stabilizer and inhibitor against TTR amyloid fibril formation. BBM rendered TTR more resistant to urea denaturation, similarly to iododiflunisal (IDIF), a very potent TTR stabilizer. BBM competes with thyroxine for binding in the TTR central channel, with an IC50 similar to IDIF and tafamidis. Results obtained by isothermal titration calorimetry (ITC) demonstrated that BBM binds TTR with an affinity similar to IDIF, tolcapone and tafamidis, confirming BBM as a potent binder of TTR. The crystal structure of the BBM-TTR complex shows two molecules binding deeply in the thyroxine binding channel, forming strong intermonomer hydrogen bonds and increasing the stability of the TTR tetramer. Finally, kinetic analysis of the ability of BBM to inhibit TTR fibrillogenesis at acidic pH and comparison with other stabilizers revealed that benzbromarone is a potent inhibitor of TTR amyloidogenesis, adding a new interesting scaffold for drug design of TTR stabilizers.

Sphenoid sinus fungus ball by filaments of actinomycetes and Aspergillus fumigatus.

We present a case of sphenoid sinus fungus ball caused by Aspergillus fumigatus associated with actinomycosis. This case represents the first known reported infection caused by this rare association.

Calcium ions promote superoxide dismutase 1 (SOD1) aggregation into non-fibrillar amyloid: a link to toxic effects of calcium overload in amyotrophic lateral sclerosis (ALS)?

Imbalance in metal ion homeostasis is a hallmark in neurodegenerative conditions involving protein deposition, and amyotrophic lateral sclerosis (ALS) is no exception. In particular, Ca(2+) dysregulation has been shown to correlate with superoxide dismutase-1 (SOD1) aggregation in a cellular model of ALS. Here we present evidence that SOD1 aggregation is enhanced and modulated by Ca(2+). We show that at physiological pH, Ca(2+) induces conformational changes that increase SOD1 ß-sheet content, as probed by far UV CD and attenuated total reflectance-FTIR, and enhances SOD1 hydrophobicity, as probed by ANS fluorescence emission. Moreover, dynamic light scattering analysis showed that Ca(2+) boosts the onset of SOD1 aggregation. In agreement, Ca(2+) decreases SOD1 critical concentration and nucleation time during aggregation kinetics, as evidenced by thioflavin T fluorescence emission. Attenuated total reflectance FTIR analysis showed that Ca(2+) induced aggregates consisting preferentially of antiparallel ß-sheets, thus suggesting a modulation effect on the aggregation pathway. Transmission electron microscopy and analysis with conformational anti-fibril and anti-oligomer antibodies showed that oligomers and amyloidogenic aggregates constitute the prevalent morphology of Ca(2+)-induced aggregates, thus indicating that Ca(2+) diverts SOD1 aggregation from fibrils toward amorphous aggregates. Interestingly, the same heterogeneity of conformations is found in ALS-derived protein inclusions. We thus hypothesize that transient variations and dysregulation of cellular Ca(2+) levels contribute to the formation of SOD1 aggregates in ALS patients. In this scenario, Ca(2+) may be considered as a pathogenic effector in the formation of ALS proteinaceous inclusions.

Trends in dietary intake in Switzerland, 1999 to 2009.

OBJECTIVE: To assess nutrition trends of the Geneva population for the period 1999-2009. DESIGN: Bus Santé Geneva study, which conducts annual health surveys in random samples of the Geneva population. Dietary intake was assessed using a validated FFQ and trends were assessed by linear regression. SETTING: Population-based survey. SUBJECTS: Data from 9283 participants (50% women, mean age 51·5 (sd 10·8) years) were analysed. RESULTS: In both genders total energy intake decreased from 1999 to 2009, by 2·9% in men and by 6·3% in women (both trends P < 0·005). Vegetable protein and total carbohydrate intakes, expressed as a percentage of total energy intake, increased in women. MUFA intake increased while SFA, PUFA and alcohol intakes decreased in both genders. Intakes of Ca, Fe and carotene decreased in both genders. No changes in fibre, vitamin D and vitamin A intakes were found. Similar findings were obtained after excluding participants with extreme dietary intakes, except that the decreases in SFA, vegetable protein and carbohydrate were no longer significant in women. CONCLUSIONS: Between 1999 and 2009, a small decrease in total energy intake was noted in the Geneva population. Although the decrease in alcohol and SFA intakes is of interest, the decrease in Ca and Fe intakes may have adverse health effects in the future.

The trail making test as a screening instrument for driving performance in older drivers; a translational research.

BACKGROUND: In many countries, primary care physicians determine whether or not older drivers are fit to drive. Little, however, is known regarding the effects of cognitive decline on driving performance and the means to detect it. This study explores to what extent the trail making test (TMT) can provide indications to clinicians about their older patients' on-road driving performance in the context of cognitive decline. METHODS: This translational study was nested within a cohort study and an exploratory psychophysics study. The target population of interest was constituted of older drivers in the absence of important cognitive or physical disorders. We therefore recruited and tested 404 home-dwelling drivers, aged 70 years or more and in possession of valid drivers' licenses, who volunteered to participate in a driving refresher course. Forty-five drivers also agreed to undergo further testing at our lab. On-road driving performance was evaluated by instructors during a 45 minute validated open-road circuit. Drivers were classified as either being excellent, good, moderate, or poor depending on their score on a standardized evaluation of on-road driving performance. RESULTS: The area under the receiver operator curve for detecting poorly performing drivers was 0.668 (CI95% 0.558 to 0.778) for the TMT-A, and 0.662 (CI95% 0.542 to 0.783) for the TMT-B. TMT was related to contrast sensitivity, motion direction, orientation discrimination, working memory, verbal fluency, and literacy. Older patients with a TMT-A ≥ 54 seconds or a TMT-B ≥ 150 seconds have a threefold (CI95% 1.3 to 7.0) increased risk of performing poorly during the on-road evaluation. TMT had a sensitivity of 63.6%, a specificity of 64.9%, a positive predictive value of 9.5%, and a negative predictive value of 96.9%. CONCLUSION: In screening settings, the TMT would have clinicians uselessly consider driving cessation in nine drivers out of ten. Given the important negative impact this could have on older drivers, this study confirms the TMT not to be specific enough for clinicians to justify driving cessation without complementary investigations on driving behaviors.

Permanent pacemaker implantation after alcoholic septal ablation induced complete heart block: Long-term impact.

INTRODUCTION AND OBJECTIVES: Patients with hypertrophic obstructive cardiomyopathy (HOCM) that remain symptomatic despite optimized medical therapy often undergo alcohol septal ablation (ASA). One of the most frequent complications is complete heart block (CHB), requiring a permanent pacemaker (PPM) in variable rates of up to 20% of patients. The long-term impact of PPM implantation in these patients remains unclear. This study aimed to evaluate the long-term clinical outcomes in patients who implant PPM after ASA. METHODS: Patients who underwent ASA at a tertiary center were consecutively and prospectively enrolled. Patients with previous PPM or implantable cardio-defibrillator were excluded from this analysis. Patients with and without PPM implantation after ASA were compared based on their baseline characteristics, procedure data and three-year primary endpoint of composite of all-cause mortality and hospitalization and secondary endpoint of composite of all-cause mortality and cardiac cause hospitalization. RESULTS: Between 2009 and 2019, 109 patients underwent ASA, 97 of whom were included in this analysis (68% female, mean age 65.2 years old). 16 patients (16.5%) required PPM implantation for CHB. In these patients, no vascular access, pacemaker pocket or pulmonary parenchyma complications were noted. The baseline characteristics of comorbidities, symptoms, echocardiographic and electrocardiographic findings were identical in the two groups, with higher mean age (70.6±10.0 years vs. 64.1±11.9 years) and lower beta-blocker therapy rate (56% vs. 84%) in the PPM group. Procedure-related data showed higher creatine kinase (CK) peaks in the PPM group (1692 U/L vs. 1243 U/L), with no significant difference in the alcohol dose. At three years after ASA procedure, there were no differences in the primary and secondary endpoints between the two groups. CONCLUSIONS: Permanent pacemaker after ASA induced CHB do not affect long term prognosis in hypertrophic obstructive cardiomyopathy patients.

S100A6 amyloid fibril formation is calcium-modulated and enhances superoxide dismutase-1 (SOD1) aggregation.

S100A6 is a small EF-hand calcium- and zinc-binding protein involved in the regulation of cell proliferation and cytoskeletal dynamics. It is overexpressed in neurodegenerative disorders and a proposed marker for Amyotrophic Lateral Sclerosis (ALS). Following recent reports of amyloid formation by S100 proteins, we investigated the aggregation properties of S100A6. Computational analysis using aggregation predictors Waltz and Zyggregator revealed increased propensity within S100A6 helices H(I) and H(IV). Subsequent analysis of Thioflavin-T binding kinetics under acidic conditions elicited a very fast process with no lag phase and extensive formation of aggregates and stacked fibrils as observed by electron microscopy. Ca(2+) exerted an inhibitory effect on the aggregation kinetics, which could be reverted upon chelation. An FT-IR investigation of the early conformational changes occurring under these conditions showed that Ca(2+) promotes anti-parallel ß-sheet conformations that repress fibrillation. At pH 7, Ca(2+) rendered the fibril formation kinetics slower: time-resolved imaging showed that fibril formation is highly suppressed, with aggregates forming instead. In the absence of metals an extensive network of fibrils is formed. S100A6 oligomers, but not fibrils, were found to be cytotoxic, decreasing cell viability by up to 40%. This effect was not observed when the aggregates were formed in the presence of Ca(2+). Interestingly, native S1006 seeds SOD1 aggregation, shortening its nucleation process. This suggests a cross-talk between these two proteins involved in ALS. Overall, these results put forward novel roles for S100 proteins, whose metal-modulated aggregation propensity may be a key aspect in their physiology and function.

Small molecules present in the cerebrospinal fluid metabolome influence superoxide dismutase 1 aggregation.

Superoxide dismutase 1 (SOD1) aggregation is one of the pathological markers of amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disorder. The underlying molecular grounds of SOD1 pathologic aggregation remains obscure as mutations alone are not exclusively the cause for the formation of protein inclusions. Thus, other components in the cell environment likely play a key role in triggering SOD1 toxic aggregation in ALS. Recently, it was found that ALS patients present a specific altered metabolomic profile in the cerebrospinal fluid (CSF) where SOD1 is also present and potentially interacts with metabolites. Here we have investigated how some of these small molecules affect apoSOD1 structure and aggregation propensity. Our results show that as co-solvents, the tested small molecules do not affect apoSOD1 thermal stability but do influence its tertiary interactions and dynamics, as evidenced by combined biophysical analysis and proteolytic susceptibility. Moreover, these compounds influence apoSOD1 aggregation, decreasing nucleation time and promoting the formation of larger and less soluble aggregates, and in some cases polymeric assemblies apparently composed by spherical species resembling the soluble native protein. We conclude that some components of the ALS metabolome that shape the chemical environment in the CSF may influence apoSOD1 conformers and aggregation.

A Complex Case of Infective Endocarditis With Systemic Embolization: Multidisciplinary Approach to Diagnosis and Management.

A 44-year-old man with no known medical history presented with stroke symptoms and was found to have occlusion of the M1 segment of the right middle cerebral artery. Thrombolysis and aspiration thrombectomy were successfully performed. However, in the following hours, he developed a fever and multiple cerebral hemorrhages. Due to a drop in hemoglobin post-angiography, an abdominopelvic CT was performed, revealing extensive splenic and renal infarctions. The patient was diagnosed with infective endocarditis (IE) with mitral and aortic vegetations and severe aortic regurgitation. Treatment for IE was initiated, and valve surgery was scheduled after six weeks of antibiotic therapy. Transesophageal echocardiogram documented pseudoaneurysm of the anterior mitral valve leaflet with a high risk of rupture, leading to the decision for early surgery. A prior splenectomy was performed due to the risk of splenic bleeding during anticoagulation for cardiac surgery, being complicated by hemorrhagic shock. The patient ultimately died from complications, including ventilator-associated pneumonia, septic shock, and refractory respiratory failure. Stroke can be the initial manifestation of IE, and the optimal medical and surgical approach must consider the risks of systemic embolization and surgical complications.

S100B chaperone multimers suppress the formation of oligomers during Aß42 aggregation.

Extracellular aggregation of the amyloid-ß 1-42 (Aß42) peptide is a major hallmark of Alzheimer's disease (AD), with recent data suggesting that Aß intermediate oligomers (AßO) are more cytotoxic than mature amyloid fibrils. Understanding how chaperones harness such amyloid oligomers is critical toward establishing the mechanisms underlying regulation of proteostasis in the diseased brain. This includes S100B, an extracellular signaling Ca2+-binding protein which is increased in AD as a response to neuronal damage and whose holdase-type chaperone activity was recently unveiled. Driven by this evidence, we here investigate how different S100B chaperone multimers influence the formation of oligomers during Aß42 fibrillation. Resorting to kinetic analysis coupled with simulation of AßO influx distributions, we establish that supra-stoichiometric ratios of dimeric S100B-Ca2+ drastically decrease Aß42 oligomerization rate by 95% and AßO levels by 70% due to preferential inhibition of surface-catalyzed secondary nucleation, with a concomitant redirection of aggregation toward elongation. We also determined that sub-molar ratios of tetrameric apo-S100B decrease Aß42 oligomerization influx down to 10%, while precluding both secondary nucleation and, more discreetly, fibril elongation. Coincidently, the mechanistic predictions comply with the independent screening of AßO using a combination of the thioflavin-T and X-34 fluorophores. Altogether, our findings illustrate that different S100B multimers act as complementary suppressors of Aß42 oligomerization and aggregation, further underpinning their potential neuroprotective role in AD.