Central venous catheter-related right atrial thrombus in oncology patients: a case series of cardiovascular magnetic resonance studies.

Background: Patients with cancer are at an increased risk of thrombus formation, often identified on routine echocardiogram in the right atrium. The 2022 ESC Guidelines on Cardio-oncology emphasize cardiac magnetic resonance (CMR) as the gold standard for thrombus identification. Case summary: We present a case series of seven patients who underwent CMR due to right atrial mass suspected to result from central venous catheter-related right atrial thrombus. In all cases, CMR enabled accurate diagnosis of a thrombus. It also allowed to assess complete or partial resolution of the thrombi following anticoagulation on follow-up studies. Discussion: The presence of a central venous catheter is recognized as a risk factor for thrombus formation, particularly when inappropriately advanced into the right atrium. The integration of CMR into the diagnostic pathway enabled precise thrombus identification and guidance for treatment in this population with a complex balance between cancer-related thrombotic and haemorrhagic risks.

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.

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.

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.

Myocardial Work Brings New Insights into Left Ventricular Remodelling in Cardio-Oncology Patients.

Serial transthoracic echocardiographic (TTE) assessment of 2D left ventricular ejection fraction (LVEF) and global longitudinal strain (GLS) are the gold standard screening methods for cancer therapeutics-related cardiac dysfunction (CTRCD). Non-invasive left ventricular (LV) pressure-strain loop (PSL) provides a novel method of quantifying myocardial work (MW) with potential advantages to evaluate the impact of cardiotoxic treatments on heart function. We prospectively assessed breast cancer female patients undergoing cancer therapy through serial monitoring by 2D and 3D TTE. Patients were evaluated at T0, T1 and T2 (before, 4-6 and 12-14 months after starting therapy, respectively). Through PSL analysis, MW indices were calculated. A total of 122 patients, with a mean age of 54.7 years, who received treatment with anthracyclines (77.0%) and anti-HER2 (75.4%) were included. During a mean follow-up of 14.9 ± 9.3 months, LVEF and GLS were significantly diminished, and 29.5% developed CTRCD. All MW indices were significantly reduced at T1 compared with baseline and tended to return to baseline values at T2. Global work index and global work efficiency showed a more pronounced variation in patients with CTRCD. The presence of more than one cardiovascular risk factor, obesity and baseline left atrium volume were predictors of changes in MW parameters. In conclusion, breast cancer treatment was associated with LV systolic dysfunction as assessed by MW, with its peak at 4-6 months and a partial recovery afterwards. Assessment of myocardial deformation parameters allows a more detailed characterization of cardiac remodelling and could enhance patient screening and selection for cardioprotective therapeutics.

Neuroprotection in early stages of Alzheimer's disease is promoted by transthyretin angiogenic properties.

BACKGROUND: While still controversial, it has been demonstrated that vascular defects can precede the onset of other AD hallmarks features, making it an important therapeutic target. Given that the protein transthyretin (TTR) has been established as neuroprotective in AD, here we investigated the influence of TTR in the vasculature. METHODS: We evaluated the thickness of the basement membrane and the length of brain microvessels, by immunohistochemistry, in AßPPswe/PS1A246E (AD) transgenic mice and non-transgenic mice (NT) bearing one (TTR+/-) or two (TTR+/+) copies of the TTR gene. The angiogenic potential of TTR was evaluated in vitro using the tube formation assay, and in vivo using the chick chorioallantoic membrane (CAM) assay. RESULTS: AD transgenic mice with TTR genetic reduction, AD/TTR+/-, exhibited a thicker BM in brain microvessels and decreased vessel length than animals with normal TTR levels, AD/TTR+/+. Further in vivo investigation, using the CAM assay, revealed that TTR is a pro-angiogenic molecule, and the neovessels formed are functional. Also, TTR increased the expression of key angiogenic molecules such as proteins interleukins 6 and 8, angiopoietin 2, and vascular endothelial growth factor, by endothelial cells, in vitro, under tube formation conditions. We showed that while TTR reduction also leads to a thicker BM in NT mice, this effect is more pronounced in AD mice than in NT animals, strengthening the idea that TTR is a neuroprotective protein. We also studied the effect of TTR tetrameric stabilization on BM thickness, showing that AD mice treated with the TTR tetrameric stabilizer iododiflunisal (IDIF) displayed a significant reduction of BM thickness and increased vessel length, when compared to non-treated littermates. CONCLUSION: Our in vivo results demonstrate the involvement of TTR in angiogenesis, particularly as a modulator of vascular alterations occurring in AD. Since TTR is decreased early in AD, its tetrameric stabilization can represent a therapeutic avenue for the early treatment of AD through the maintenance of the vascular structure.

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.

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.

Processed meat intake and chronic disease morbidity and mortality: An overview of systematic reviews and meta-analyses.

Despite the nutritional value of meat, a large volume of reviews and meta-analyses suggests that processed meat intake is associated with an increased risk of chronic diseases. However, assessments of the quality of these published reviews internal validity are generally lacking. We systematically reviewed and assessed the quality alongside summarizing the results of previously published systematic reviews and meta-analyses that examined the association between processed meat intake and cancers, type II diabetes (T2D), and cardiovascular diseases (CVD). Reviews and meta-analyses published until May 2018 were identified through a systematic literature search in the databases MEDLINE and EMBASE, and reference lists of included reviews. The quality of the systematic reviews and meta-analyses was assessed using A Measurement Tool to Assess Systematic Reviews (AMSTAR). All eligible reviews had to comply with two quality requirements: providing sufficient information on quality assessment of the primary studies and a comprehensive search. The results were summarized for T2D, CVD, and each of the different cancer types. The certainty in the estimates of the individual outcomes was rated using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) method. In total, 22 systematic reviews were eligible and thus included in this review. More than 100 reviews were excluded because quality assessment of the primary studies had not been performed. The AMSTAR score of the included reviews ranged from 5 to 8 indicating moderate quality. Overall, the quality assessments of primary studies of the reviews are generally lacking; the scientific quality of the systematic reviews reporting positive associations between processed meat intake and risk of various cancers, T2D and CVD is moderate, and the results from case-control studies suggest more often a positive association than the results from cohort studies. The overall certainty in the evidence was very low across all individual outcomes, due to serious risk of bias and imprecision.

Transthyretin stability is critical in assisting beta amyloid clearance- Relevance of transthyretin stabilization in Alzheimer's disease.

BACKGROUND: The absence of transthyretin (TTR) in AD mice decreases brain Aß clearance and reduces the low-density lipoprotein receptor-related protein 1 (LRP1). It is possible that neuroprotection by TTR is dependent on its tetramer structural stability, as studies using TTR mutants showed that unstable L55P TTR has low affinity for Aß, and TTR tetrameric stabilizers such as iododiflunisal ameliorate AD features in vivo. METHODS: We firstly investigated TTR folding status in human plasma measuring the resistance to urea denaturation. The importance of TTR stability on Aß internalization was studied in human cerebral microvascular endothelial (hCMEC/D3) and hepatoma cells (HepG2), by flow cytometry. To investigate the fate of Aß at the blood-brain barrier, Aß efflux from hCMEC/D3 cells seeded on transwells was measured using ELISA. Further, to assess Aß colocalization with lysosomes, Lysotracker was used. Moreover, levels of LRP1 were assessed in the liver and plasma of mice with different TTR backgrounds or treated with iododiflunisal. RESULTS: We showed that TTR stability is decreased in AD and that WT TTR and drug-stabilized L55P TTR are able to increase uptake of Aß. Furthermore, measurement of Aß efflux showed that stable or stabilized TTR increased Aß efflux from the basolateral to the apical side. Moreover, HepG2 cells incubated with Aß in the presence of WT TTR, but not L55P TTR, showed an increased number of lysosomes. Further, in the presence of WT TTR, Aß peptide colocalized with lysosomes, indicating that only stable TTR assists Aß internalization, leading to its degradation. Finally, we demonstrated that only stable TTR can increase LRP1 levels. CONCLUSION: TTR stabilization exerts a positive effect on Aß clearance and LRP1 levels, suggesting that TTR protective role in AD is dependent on its stability. These results provide relevant information for the design of TTR-based therapeutic strategies for AD.

Non-Aspergillus fungal rhinosinusitis at a tertiary care hospital and the first report of human infection by Trichoderma asperellum

We describe 27 cases of fungal rhinosinusitis, which were caused by agents other than Aspergillus, diagnosed at our institution during a 24-year period. Particular focus was on defining the causal fungi and the predisposing factors. Fungal cultures were obtained from 20 cases and there was no growth in seven cases. Classification of mycotic disease of the nose and paranasal sinuses as invasive and noninvasive is based on clinical, radiological, and histopathological factors. The most common pathogens were Histoplasma capsulatum (n=4), Scedosporium apiospermum (n=2), Alternaria alternata (n=2), Schizophyllum commune (n=2), Pseudallescheria boydii (n=1), Penicillium sp. (n=1), Lichtheimia (Absidia) corymbifera (n=1), Xylaria enteroleuca (n=1), Trichoderma asperellum (n=1), T. harzianum (n=1), T. viride (n=1), Fusarium solani (n=1), Cladosporium sp. (n=1), and Cryptococcus neoformans (n=1). From the ones that revealed no growth, four were classified as hyalohyphomycosis and three were mucormycosis by the histopathological findings. In addition, we describe the first welldocumented case of rhinosinusitis and human infection by T. asperellum.

Polymer-doxycycline conjugates as fibril disrupters: an approach towards the treatment of a rare amyloidotic disease.

The term amyloidosis describes neurological diseases where an abnormal protein is misfolded and accumulated as deposits in organs and tissues, known as amyloid, disrupting their normal function. In the most common familial amyloid polyneuropathy (FAP), transthyretin (TTR) displays this role primarily affecting the peripheral nervous system (PNS). Advanced stages of this inherited rare amyloidosis, present as fibril deposits that are responsible for disease progression. In order to stop disease progression, herein we designed an efficient family of nanoconjugates as fibril disrupters. These polymer conjugates are based on doxycycline (doxy), already in phase II trials for Alzheimer's disease, covalently linked to poly-l-glutamic acid (PGA). The conjugates were rationally designed, looking at drug loading and drug release rate by adequate linker design, always considering the physiological conditions at the molecular target site. Conjugation of doxycycline exhibited greater potential towards TTR fibril disaggregation in vitro compared to the parent drug. Exhaustive physico-chemical evaluation of these polymer-drug conjugates concluded that drug release was unnecessary for activity, highlighting the importance of an appropriate linker. Furthermore, biodistribution studies through optical imaging (OI) and the use of radiolabelled polymer-drug conjugates demonstrated conjugate safety profile and renal clearance route of the selected PGA-doxy candidate, settling the adequacy of our conjugate for future in vivo evaluation. Furthermore, preliminary studies in an FAP in vivo model at early stages of disease development showed non-organ toxicity evidences. This nanosized-system raises a promising treatment for advanced stages of this rare amyloidotic disease, and also presents a starting point for possible application within other amyloidosis-related diseases, such as Alzheimer's disease.

Aspergillosis of the nose and paranasal sinuses: a review of 54 cases

Aspergillus species are considered opportunistic fungi of increasing clinical importance. Informationregarding extrapulmonary involvement is scarce. The aim of this study was to isolate the differentspecies of Aspergillus from patients with rhinosinusitis. A retrospective study was conducted ina university hospital in Porto Alegre, Brazil (1986–2014). For mycological diagnoses, paranasaltissue obtained at surgery was subjected to histopathology examination and sent for fungal cultures.Of the 54 samples analyzed, 32 were diagnosed positive by culture. The underlying causes ofimmunodeficiency were: six with transplantation (three bone marrow,two lung, one kidney) andtwo with hematological disease (one bone marrow neoplasia and two leukemia). In the presentstudy, the clinical manifestations of rhinosinusitis aspergillosis were: 20 allergic reactions, 20fungus balls, and 14 acute invasive cases. The species isolated from the 54 samples were: Aspergillusfumigatus (n=14); A. flavus (n=6); A. niger (n=2); A. terreus (n=1); A. fischeri (n=1); and Aspergillussp., (n=3). Two concomitant species of Aspergillus were observed in two patients: A. fumigatus andA. flavus; and A. fumigatus and A. niger. In four patients, Aspergillus was associated with other fungi. These were: A. flavus and Fusarium, A. fumigatus and Rhyzopus, A. flavus and Mucorales, and Aspergillus sp. and Mucorales. The most common species of Aspergillus that were responsiblefor paranasal sinus infections were A. fumigatus, A. flavus, and A. niger...

Espécies de Aspergillus são considerados fungos oportunistas de crescente importância clínica.Informações sobre o envolvimento extrapulmonar é escassa. O objetivo deste estudo foi isolaras diferentes espécies de Aspergillus em pacientes com rinossinusite. Um estudo retrospectivofoi realizado em um hospital universitário em Porto Alegre, Brasil (1986-2014). Para diagnósticomicológico, tecido paranasais obtido no momento da cirurgia foi submetido a exame histopatológicoe encaminhados para cultivos de fungos. Das 54 amostras analisadas, 32 foram diagnosticados pelocultivo positivo. As causas subjacentes da imunodeficiência foram: seis com transplante (medulaóssea, três, pulmão, dois; rim, um) e dois com doenças hematológicas (neoplasia osso estreito,um; leucemia, duas). No presente estudo, as manifestações clínicas de rinossinusite aspergilarforam: alérgica, 20; bolas fúngica, 20; e aguda invasiva, 14. As espécies fúngicas isoladas foram:Aspergillus fumigatus, 14; A. flavus, seis; A. niger, dois; A. terreus, um; A. fischeri, um; e Aspergillussp., três. Duas espécies de Aspergillus concomitantes foram observadas em dois pacientes: A.fumigatus e A. flavus; e A. fumigatus e A. niger. Em quatro pacientes, Aspergillus foi associado comoutros fungos: A. flavus e Fusarium, um; A. fumigatus e Rhyzopus, um; A. flavus e Mucorales, um; eAspergillus sp. e Mucorales, um. Os isolados mais comuns de Aspergillus que são responsáveis porinfecções dos seios paranasais são A. fumigatus, A. flavus e A. niger...

Targeting a rare amyloidotic disease through rationally designed polymer conjugates.

Saraiva et al. discovered in 2006 a RAGE-based peptide sequence capable of preventing transthyretin (TTR) aggregate-induced cytotoxicity, hallmark of initial stages of an inherited rare amyloidosis known as Familial Amyloidotic Polyneuropathy (FAP). To allow clinical progression of this peptidic sequence as FAP treatment, a family of polymer conjugates has been designed, synthesised and fully characterised. This approach fulfils the strategies defined in the Polymer Therapeutics area as an exhaustive physico-chemical characterisation fitting activity output towards a novel molecular target that is described here. RAGE peptide acts extracellularly, therefore, no intracellular drug delivery was necessary. PEG was selected as carrier and polymer-drug linker optimisation was then carried out by means of biodegradable (disulphide) and non-biodegradable (amide) covalent bonds. Conjugate size in solution, stability under in vitro and in vivo scenarios and TTR binding affinity through surface plasmon resonance (SPR) was also performed with all synthesised conjugates. In their in vitro evaluation by monitoring the activation of caspase-3 in Schwann cells, peptide derivatives demonstrated retention of peptide activity reducing TTR aggregates (TTRagg) cytotoxicity upon conjugation and a greater plasma stability than the parent free peptide. The results also confirmed that a more stable polymer-peptide linker (amide) is required to secure therapeutic efficiency.

Stability of the transthyretin molecule as a key factor in the interaction with a-beta peptide--relevance in Alzheimer's disease.

Transthyretin (TTR) protects against A-Beta toxicity by binding the peptide thus inhibiting its aggregation. Previous work showed different TTR mutations interact differently with A-Beta, with increasing affinities correlating with decreasing amyloidogenecity of the TTR mutant; this did not impact on the levels of inhibition of A-Beta aggregation, as assessed by transmission electron microscopy. Our work aimed at probing differences in binding to A-Beta by WT, T119M and L55P TTR using quantitative assays, and at identifying factors affecting this interaction. We addressed the impact of such factors in TTR ability to degrade A-Beta. Using a dot blot approach with the anti-oligomeric antibody A11, we showed that A-Beta formed oligomers transiently, indicating aggregation and fibril formation, whereas in the presence of WT and T119M TTR the oligomers persisted longer, indicative that these variants avoided further aggregation into fibrils. In contrast, L55PTTR was not able to inhibit oligomerization or to prevent evolution to aggregates and fibrils. Furthermore, apoptosis assessment showed WT and T119M TTR were able to protect against A-Beta toxicity. Because the amyloidogenic potential of TTR is inversely correlated with its stability, the use of drugs able to stabilize TTR tetrameric fold could result in increased TTR/A-Beta binding. Here we showed that iododiflunisal, 3-dinitrophenol, resveratrol, [2-(3,5-dichlorophenyl)amino] (DCPA) and [4-(3,5-difluorophenyl)] (DFPB) were able to increase TTR binding to A-Beta; however only DCPA and DFPB improved TTR proteolytic activity. Thyroxine, a TTR ligand, did not influence TTR/A-Beta interaction and A-Beta degradation by TTR, whereas RBP, another TTR ligand, not only obstructed the interaction but also inhibited TTR proteolytic activity. Our results showed differences between WT and T119M TTR, and L55PTTR mutant regarding their interaction with A-Beta and prompt the stability of TTR as a key factor in this interaction, which may be relevant in AD pathogenesis and for the design of therapeutic TTR-based therapies.

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.

Optical coherence tomography image in gelatinous drop-like corneal dystrophy: case report / Tomografia de coerência óptica na distrofia corneana gelatinosa em gotas: relato de caso

Gelatinous drop-like corneal dystrophy is a rare disorder with few cases described in the present literature. The following report will show how difficult it is to diagnose this disease in early stages. Modern image exams, such as optical coherence tomography helps to diagnose and can be crucial to establish the best treatment. We will present the histopathological changes and clinical features in this unusual dystrophy.

A distrofia corneana gelatinosa em gotas é uma desordem rara e pouco descrita em nossa literatura. O caso apresentado demonstra a dificuldade de realizar o diagnóstico nas fases mais iniciais da doença. O uso de modernos exames de imagem, como a tomografia de coerência óptica de segmento anterior, auxilia no diagnóstico e pode ser crucial para definir a melhor conduta terapêutica. Apresentaremos as alterações histopatológicas e as características clínicas desta incomum distrofia.