A druggable conformational switch in the c-MYC transactivation domain

The c-MYC oncogene is activated in over 70% of all human cancers. The intrinsic disorder of the c-MYC transcription factor facilitates molecular interactions that regulate numerous biological pathways, but severely limits efforts to target its function for cancer therapy. Here, we use a reductionist strategy to characterize the dynamic and structural heterogeneity of the c-MYC protein. Using probe-based Molecular Dynamics (MD) simulations and machine learning, we identify a conformational switch in the c-MYC amino-terminal transactivation domain (termed coreMYC) that cycles between a closed, inactive, and an open, active conformation. Using the polyphenol epigallocatechin gallate (EGCG) to modulate the conformational landscape of coreMYC, we show through biophysical and cellular assays that the induction of a closed conformation impedes its interactions with the transformation/transcription domain-associated protein (TRRAP) and the TATA-box binding protein (TBP) which are essential for the transcriptional and oncogenic activities of c-MYC. Together, these findings provide insights into structure-activity relationships of c-MYC, which open avenues towards the development of shape-shifting compounds to target c-MYC as well as other disordered transcription factors for cancer treatment.

Advances in mass spectrometry to unravel the structure and function of protein condensates

Membrane-less organelles assemble through liquid-liquid phase separation (LLPS) of partially disordered proteins into highly specialized microenvironments. Currently, it is challenging to obtain a clear understanding of the relationship between the structure and function of phase-separated protein assemblies, owing to their size, dynamics and heterogeneity. In this Perspective, we discuss recent advances in mass spectrometry (MS) that offer several promising approaches for the study of protein LLPS. We survey MS tools that have provided valuable insights into other insoluble protein systems, such as amyloids, and describe how they can also be applied to study proteins that undergo LLPS. On the basis of these recent advances, we propose to integrate MS into the experimental workflow for LLPS studies. We identify specific challenges and future opportunities for the analysis of protein condensate structure and function by MS.

Making stereotactic radiosurgery decisions by calculating the probability of perilesional edema in cavernomas

OBJECTIVE

Stereotactic radiosurgery is a therapeutic modality for cavernomas that is associated with certain adverse effects, such as perilesional edema. In this study, we aimed to estimate the presentation of perilesional edema using imaging techniques, considering its location, proximity to major venous and arterial structures, size, depth, and eloquent location.

PATIENTS AND METHODS

The radiographic evaluation included their sizes, localization of the lobes, whether they were in the deep or superficial regions, eloquent areas, and their proximity to the major arteries and venous sinuses.

RESULTS

As the size increased, the time to edema increased at the same rate (r=0.972, p=0.001). We determined that the duration of edema increases as it attaches to the great venous structures, and edema occurs over a longer time (r=-0.761, p=0.001). Cavernomas >13 mm had a high probability of causing edema (p=0.0014). Edema occurred with a high probability in patients with an arterial distance <5.69 mm and a venous/arterial distance ratio >8.93 (specificity 100%, selectivity 98.2%).

CONCLUSIONS

When recommending stereostatic radiosurgery treatment, the possibility of edema formation should be calculated based on the location, size, and proximity of the cavernoma to the vascular structures, and the choice of treatment should be made accordingly.

Mass Spectrometry of RNA-Binding Proteins during Liquid-Liquid Phase Separation Reveals Distinct Assembly Mechanisms and Droplet Architectures

Liquid-liquid phase separation (LLPS) of heterogeneous ribonucleoproteins (hnRNPs) drives the formation of membraneless organelles, but structural information about their assembled states is still lacking. Here, we address this challenge through a combination of protein engineering, native ion mobility mass spectrometry, and molecular dynamics simulations. We used an LLPS-compatible spider silk domain and pH changes to control the self-assembly of the hnRNPs FUS, TDP-43, and hCPEB3, which are implicated in neurodegeneration, cancer, and memory storage. By releasing the proteins inside the mass spectrometer from their native assemblies, we could monitor conformational changes associated with liquid-liquid phase separation. We find that FUS monomers undergo an unfolded-to-globular transition, whereas TDP-43 oligomerizes into partially disordered dimers and trimers. hCPEB3, on the other hand, remains fully disordered with a preference for fibrillar aggregation over LLPS. The divergent assembly mechanisms revealed by ion mobility mass spectrometry of soluble protein species that exist under LLPS conditions suggest structurally distinct complexes inside liquid droplets that may impact RNA processing and translation depending on biological context.

Liquid-Liquid Phase Separation Primes Spider Silk Proteins for Fiber Formation via a Conditional Sticker Domain

Many protein condensates can convert to fibrillar aggregates, but the underlying mechanisms are unclear. Liquid-liquid phase separation (LLPS) of spider silk proteins, spidroins, suggests a regulatory switch between both states. Here, we combine microscopy and native mass spectrometry to investigate the influence of protein sequence, ions, and regulatory domains on spidroin LLPS. We find that salting out-effects drive LLPS via low-affinity stickers in the repeat domains. Interestingly, conditions that enable LLPS simultaneously cause dissociation of the dimeric C-terminal domain (CTD), priming it for aggregation. Since the CTD enhances LLPS of spidroins but is also required for their conversion into amyloid-like fibers, we expand the stickers and spacers-model of phase separation with the concept of folded domains as conditional stickers that represent regulatory units.

The factors that cause penile shortening after plication surgery in patients with congenital penile curvature: [[es]]Los factores causantes del acortamiento de pene después de la cirugía con plicatura en pacientes con incurvación peneana congénita

OBJECTIVE

Congenital penile curvature is defined as the non-straightness of the penis without any urethral or penile pathology. We aimed to evaluate the factors that cause penile shortening after plication surgery in patients with congenital penile curvature.

METHODS

Between November 2010 and December 2020, we retrospectively reviewed patients with CPC undergoing tunica albuginea plication surgery. Before the procedure, patients' age, curvature location and degrees, as well as penile length were recorded. After the treatment, penile lengths were measured and recorded again. Early and late period results were recorded.

RESULTS

Plication surgery was performed in 130 patients. The median age was 24 years. Seventy-six patients had ventral curvature, 22 had dorsal curvature, 32 had lateral curvature. Average shortening of penile length in patients with curvature below 30° was: ventral 8-16 mm, dorsal 6-13 mm, lateral 5-12 mm. Patients with curvatures above 30° were: ventral 12-22 mm, dorsal 8-20 mm, lateral 2-12 mm.

CONCLUSION

Penile length shortening after plication is inevitable. Curvature degree and direction are factors affecting penile length after surgery. Therefore, patients and relatives should be informed in more detail about this complication.

A "grappling hook" interaction connects self-assembly and chaperone activity of Nucleophosmin 1

How the self-assembly of partially disordered proteins generates functional compartments in the cytoplasm and particularly in the nucleus is poorly understood. Nucleophosmin 1 (NPM1) is an abundant nucleolar protein that forms large oligomers and undergoes liquid-liquid phase separation by binding RNA or ribosomal proteins. It provides the scaffold for ribosome assembly but also prevents protein aggregation as part of the cellular stress response. Here, we use aggregation assays and native mass spectrometry (MS) to examine the relationship between the self-assembly and chaperone activity of NPM1. We find that oligomerization of full-length NPM1 modulates its ability to retard amyloid formation in vitro. Machine learning-based structure prediction and cryo-electron microscopy reveal fuzzy interactions between the acidic disordered region and the C-terminal nucleotide-binding domain, which cross-link NPM1 pentamers into partially disordered oligomers. The addition of basic peptides results in a tighter association within the oligomers, reducing their capacity to prevent amyloid formation. Together, our findings show that NPM1 uses a "grappling hook" mechanism to form a network-like structure that traps aggregation-prone proteins. Nucleolar proteins and RNAs simultaneously modulate the association strength and chaperone activity, suggesting a mechanism by which nucleolar composition regulates the chaperone activity of NPM1.

Mass Spectrometry and Machine Learning Reveal Determinants of Client Recognition by Antiamyloid Chaperones

The assembly of proteins and peptides into amyloid fibrils is causally linked to serious disorders such as Alzheimer's disease. Multiple proteins have been shown to prevent amyloid formation in vitro and in vivo, ranging from highly specific chaperone-client pairs to completely nonspecific binding of aggregation-prone peptides. The underlying interactions remain elusive. Here, we turn to the machine learning-based structure prediction algorithm AlphaFold2 to obtain models for the nonspecific interactions of β-lactoglobulin, transthyretin, or thioredoxin 80 with the model amyloid peptide amyloid β and the highly specific complex between the BRICHOS chaperone domain of C-terminal region of lung surfactant protein C and its polyvaline target. Using a combination of native mass spectrometry (MS) and ion mobility MS, we show that nonspecific chaperoning is driven predominantly by hydrophobic interactions of amyloid β with hydrophobic surfaces in β-lactoglobulin, transthyretin, and thioredoxin 80, and in part regulated by oligomer stability. For C-terminal region of lung surfactant protein C, native MS and hydrogen-deuterium exchange MS reveal that a disordered region recognizes the polyvaline target by forming a complementary β-strand. Hence, we show that AlphaFold2 and MS can yield atomistic models of hard-to-capture protein interactions that reveal different chaperoning mechanisms based on separate ligand properties and may provide possible clues for specific therapeutic intervention.

Spidroin N-terminal domain forms amyloid-like fibril based hydrogels and provides a protein immobilization platform

Recombinant spider silk proteins (spidroins) have multiple potential applications in development of novel biomaterials, but their multimodal and aggregation-prone nature have complicated production and straightforward applications. Here, we report that recombinant miniature spidroins, and importantly also the N-terminal domain (NT) on its own, rapidly form self-supporting and transparent hydrogels at 37 °C. The gelation is caused by NT α-helix to β-sheet conversion and formation of amyloid-like fibrils, and fusion proteins composed of NT and green fluorescent protein or purine nucleoside phosphorylase form hydrogels with intact functions of the fusion moieties. Our findings demonstrate that recombinant NT and fusion proteins give high expression yields and bestow attractive properties to hydrogels, e.g., transparency, cross-linker free gelation and straightforward immobilization of active proteins at high density.

Recombinant spider silks are of interest but the multimodal and aggregation-prone nature of them is a limitation. Here, the authors report on a miniature spidroin based on the N-terminal domain which forms a hydrogel at 37 °C which allows for ease of production and fusion protein modification to generate functional biomaterials.

Structural Basis for Dityrosine-Mediated Inhibition of α-Synuclein Fibrillization

α-Synuclein (α-Syn) is an intrinsically disordered protein which self-assembles into highly organized β-sheet structures that accumulate in plaques in brains of Parkinson’s disease patients. Oxidative stress influences α-Syn structure and self-assembly; however, the basis for this remains unclear. Here we characterize the chemical and physical effects of mild oxidation on monomeric α-Syn and its aggregation. Using a combination of biophysical methods, small-angle X-ray scattering, and native ion mobility mass spectrometry, we find that oxidation leads to formation of intramolecular dityrosine cross-linkages and a compaction of the α-Syn monomer by a factor of √2. Oxidation-induced compaction is shown to inhibit ordered self-assembly and amyloid formation by steric hindrance, suggesting an important role of mild oxidation in preventing amyloid formation.

Association of frontal and maxillary bone fractures and concomitant craniocerebral injuries in patients presenting with head trauma

Background

Maxillofacial fractures and craniocerebral injuries are common in patients with head trauma. These are injuries with high mortality and morbidity. Therefore, patients with head trauma should be evaluated early with a multidisciplinary approach.

Aim

The association between frontal and maxillary bone fractures and concurrent craniocerebral injuries were investigated in patients presenting with head trauma in this study. The data of the patients were analyzed retrospectively.

Methods and Material

Age and gender distributions were evaluated in frontal and maxillary fractures. Concomitant craniocerebral injuries were investigated. Craniocerebral injuries were grouped as pneumocephalus, extra-axial, intra-axial injuries and brain edema. Craniocerebral injuries in frontal and maxillary fractures were compared statistically.

Results

Frontal bone and maxillary bone fractures were detected in 24% and 95% of the patients. Coexistence of pneumocephalus and intra-axial injuries in frontal bone fracture was statistically significant. The association of frontal posterior wall fractures with pneumocephalus and parenchymal contusion was found to be statistically significant. In addition, the association of craniocerebral injuries were evaluated and statistically significant ones were determined.

Conclusion

The presence of maxillofacial fractures in patients presenting with head trauma increases mortality and morbidity. Craniocerebral injuries can be life-threatening and delay the treatment of facial fractures. Upper facial bone fractures are significantly more common in craniocerebral injuries.

Charge Engineering Reveals the Roles of Ionizable Side Chains in Electrospray Ionization Mass Spectrometry

In solution, the charge of a protein is intricately linked to its stability, but electrospray ionization distorts this connection, potentially limiting the ability of native mass spectrometry to inform about protein structure and dynamics. How the behavior of intact proteins in the gas phase depends on the presence and distribution of ionizable surface residues has been difficult to answer because multiple chargeable sites are present in virtually all proteins. Turning to protein engineering, we show that ionizable side chains are completely dispensable for charging under native conditions, but if present, they are preferential protonation sites. The absence of ionizable side chains results in identical charge state distributions under native-like and denaturing conditions, while coexisting conformers can be distinguished using ion mobility separation. An excess of ionizable side chains, on the other hand, effectively modulates protein ion stability. In fact, moving a single ionizable group can dramatically alter the gas-phase conformation of a protein ion. We conclude that although the sum of the charges is governed solely by Coulombic terms, their locations affect the stability of the protein in the gas phase.

Order and disorder-An integrative structure of the full-length human growth hormone receptor

Because of its small size (70 kilodalton) and large content of structural disorder (>50%), the human growth hormone receptor (hGHR) falls between the cracks of conventional high-resolution structural biology methods. Here, we study the structure of the full-length hGHR in nanodiscs with small-angle x-ray scattering (SAXS) as the foundation. We develop an approach that combines SAXS, x-ray diffraction, and NMR spectroscopy data obtained on individual domains and integrate these through molecular dynamics simulations to interpret SAXS data on the full-length hGHR in nanodiscs. The hGHR domains reorient freely, resulting in a broad structural ensemble, emphasizing the need to take an ensemble view on signaling of relevance to disease states. The structure provides the first experimental model of any full-length cytokine receptor in a lipid membrane and exemplifies how integrating experimental data from several techniques computationally may access structures of membrane proteins with long, disordered regions, a widespread phenomenon in biology.

Ion mobility-mass spectrometry shows stepwise protein unfolding under alkaline conditions

Although native mass spectrometry is widely applied to monitor chemical or thermal protein denaturation, it is not clear to what extent it can inform about alkali-induced unfolding. Here, we probe the relationship between solution- and gas-phase structures of proteins under alkaline conditions. Native ion mobility-mass spectrometry reveals that globular proteins are destabilized rather than globally unfolded, which is supported by solution studies, providing detailed insights into alkali-induced unfolding events. Our results pave the way for new applications of MS to monitor structures and interactions of proteins at high pH.

Molecular characteristics of porcine alpha-synuclein splicing variants

Alpha-synuclein (α-syn) is a 140 amino acid, intrinsically disordered protein with a potential role in neurotransmitter vesicle release. The protein is natively unfolded under physiological conditions, and is expressed predominantly in neural tissue. α-syn is associated with neuropathological conditions in Parkinson's disease, where the protein misfolds into oligomers and fibrils resulting in aggregates in Lewy bodies. Here we report the molecular cloning of SNCA cDNA encoding porcine α-syn and transcript variants hereof. Six transcripts coding for porcine α-syn are presented in the report, of which three result from exon skipping, generating in-frame splicing of coding exons 3 and 5. The splicing pattern of these alternative spliced variants is conserved between human and pig. All the observed in-frame deletions yield significantly shorter α-syn proteins compared with the 140 amino acid full-length protein. Expression analysis performed by real-time quantitative RT-PCR revealed a differential expression of the six transcript splicing variants in different pig organs and tissues. Common for all splicing variants, a very high transcript expression was detected in brain tissues and in spinal cord and very low or no expression outside the central nervous system. The porcine α-syn protein demonstrated markedly different biophysical characteristics compared with its human counterpart. No fibrillation of porcine α-syn was observed with the pig wild-type α-syn and A30P α-syn, and both variants show significantly reduced ability to bind to lipid vesicles. Overexpression of mutated porcine α-syn might recapitulate the human PD pathogenesis and lead to the identification of genetic modifiers of the disease.

Predicting the Shapes of Protein Complexes through Collision Cross Section Measurements and Database Searches

In structural biology, collision cross sections (CCSs) from ion mobility mass spectrometry (IM-MS) measurements are routinely compared to computationally or experimentally derived protein structures. Here, we investigate whether CCS data can inform about the shape of a protein in the absence of specific reference structures. Analysis of the proteins in the CCS database shows that protein complexes with low apparent densities are structurally more diverse than those with a high apparent density. Although assigning protein shapes purely on CCS data is not possible, we find that we can distinguish oblate- and prolate-shaped protein complexes by using the CCS, molecular weight, and oligomeric states to mine the Protein Data Bank (PDB) for potentially similar protein structures. Furthermore, comparing the CCS of a ferritin cage to the solution structures in the PDB reveals significant deviations caused by structural collapse in the gas phase. We then apply the strategy to an integral membrane protein by comparing the shapes of a prokaryotic and a eukaryotic sodium/proton antiporter homologue. We conclude that mining the PDB with IM-MS data is a time-effective way to derive low-resolution structural models.

Predicting the Shapes of Protein Complexes through Collision Cross Section Measurements and Database Searches

In structural biology, collision cross sections (CCSs) from ion mobility mass spectrometry (IM-MS) measurements are routinely compared to computationally or experimentally derived protein structures. Here, we investigate whether CCS data can inform about the shape of a protein in the absence of specific reference structures. Analysis of the proteins in the CCS database shows that protein complexes with low apparent densities are structurally more diverse than those with a high apparent density. Although assigning protein shapes purely on CCS data is not possible, we find that we can distinguish oblate- and prolate-shaped protein complexes by using the CCS, molecular weight, and oligomeric states to mine the Protein Data Bank (PDB) for potentially similar protein structures. Furthermore, comparing the CCS of a ferritin cage to the solution structures in the PDB reveals significant deviations caused by structural collapse in the gas phase. We then apply the strategy to an integral membrane protein by comparing the shapes of a prokaryotic and a eukaryotic sodium/proton antiporter homologue. We conclude that mining the PDB with IM-MS data is a time-effective way to derive low-resolution structural models.

A Mass-Spectrometry-Based Approach to Distinguish Annular and Specific Lipid Binding to Membrane Proteins

Membrane proteins engage in a variety of contacts with their surrounding lipids, but distinguishing between specifically bound lipids, and non‐specific, annular interactions is a challenging problem. Applying native mass spectrometry to three membrane protein complexes with different lipid‐binding properties, we explore the ability of detergents to compete with lipids bound in different environments. We show that lipids in annular positions on the presenilin homologue protease are subject to constant exchange with detergent. By contrast, detergent‐resistant lipids bound at the dimer interface in the leucine transporter show decreased k_off rates in molecular dynamics simulations. Turning to the lipid flippase MurJ, we find that addition of the natural substrate lipid‐II results in the formation of a 1:1 protein–lipid complex, where the lipid cannot be displaced by detergent from the highly protected active site. In summary, we distinguish annular from non‐annular lipids based on their exchange rates in solution.

High intracellular stability of the spidroin N-terminal domain in spite of abundant amyloidogenic segments revealed by in-cell hydrogen/deuterium exchange mass spectrometry

Proteins require an optimal balance of conformational flexibility and stability in their native environment to ensure their biological functions. A striking example is spidroins, spider silk proteins, which are stored at extremely high concentrations in soluble form, yet undergo amyloid-like aggregation during spinning. Here, we elucidate the stability of the highly soluble N-terminal domain (NT) of major ampullate spidroin 1 in the Escherichia coli cytosol as well as in inclusion bodies containing fibrillar aggregates. Surprisingly, we find that NT, despite being largely composed of amyloidogenic sequences, showed no signs of concentration-dependent aggregation. Using a novel intracellular hydrogen/deuterium exchange mass spectrometry (HDX-MS) approach, we reveal that NT adopts a tight fold in the E. coli cytosol and in this manner conceals its aggregation-prone regions by maintaining a tight fold under crowded conditions. Fusion of NT to the unstructured amyloid-forming Aβ₄₀ peptide, on the other hand, results in the formation of fibrillar aggregates. However, HDX-MS indicates that the NT domain is only partially incorporated into these aggregates in vivo. We conclude that NT is able to control its aggregation to remain functional under the extreme conditions in the spider silk gland.

Gas-Phase Collisions with Trimethylamine-N-Oxide Enable Activation-Controlled Protein Ion Charge Reduction

Modulating protein ion charge is a useful tool for the study of protein folding and interactions by electrospray ionization mass spectrometry. Here, we investigate activation-dependent charge reduction of protein ions with the chemical chaperone trimethylamine-N-oxide (TMAO). Based on experiments carried out on proteins ranging from 4.5 to 35 kDa, we find that when combined with collisional activation, TMAO removes approximately 60% of the charges acquired under native conditions. Ion mobility measurements furthermore show that TMAO-mediated charge reduction produces the same end charge state and arrival time distributions for native-like and denatured protein ions. Our results suggest that gas-phase collisions between the protein ions and TMAO result in proton transfer, in line with previous findings for dimethyl- and trimethylamine. By adjusting the energy of the collisions experienced by the ions, it is possible to control the degree of charge reduction, making TMAO a highly dynamic charge reducer that opens new avenues for manipulating protein charge states in ESI-MS and for investigating the relationship between protein charge and conformation. ᅟ.

A strategy for the identification of protein architectures directly from ion mobility mass spectrometry data reveals stabilizing subunit interactions in light harvesting complexes

Biotechnological applications of protein complexes require detailed information about their structure and composition, which can be challenging to obtain for proteins from natural sources. Prominent examples are the ring-shaped phycoerythrin (PE) and phycocyanin (PC) complexes isolated from the light-harvesting antennae of red algae and cyanobacteria. Despite their widespread use as fluorescent probes in biotechnology and medicine, the structures and interactions of their noncrystallizable central subunits are largely unknown. Here, we employ ion mobility mass spectrometry to reveal varying stabilities of the PC and PE complexes and identify their closest architectural homologues among all protein assemblies in the Protein Data Bank (PDB). Our results suggest that the central subunits of PC and PE complexes, although absent from the crystal structures, may be crucial for their stability, and thus of unexpected importance for their biotechnological applications.

Mechanistic Understanding of the Interactions between Nano-Objects with Different Surface Properties and α-Synuclein

Aggregation of the natively unfolded protein α-synuclein (α-syn) is key to the development of Parkinson's disease (PD). Some nanoparticles (NPs) can inhibit this process and in turn be used for treatment of PD. Using simulation strategies, we show here that α-syn self-assembly is electrostatically driven. Dimerization by head-to-head monomer contact is triggered by dipole-dipole interactions and subsequently stabilized by van der Waals interactions and hydrogen bonds. Therefore, we hypothesized that charged nano-objects could interfere with this process and thus prevent α-syn fibrillation. In our simulations, positively and negatively charged graphene sheets or superparamagnetic iron oxide NPs first interacted with α-syn's N/C terminally charged residues and then with hydrophobic residues in the non-amyloid-β component (61-95) region. In the experimental setup, we demonstrated that the charged nano-objects have the capacity not only to strongly inhibit α-syn fibrillation (both nucleation and elongation) but also to disaggregate the mature fibrils. Through the α-syn fibrillation process, the charged nano-objects induced the formation of off-pathway oligomers.

Oleuropein derivatives from olive fruit extracts reduce α-synuclein fibrillation and oligomer toxicity

Aggregation of α-synuclein (αSN) is implicated in neuronal degeneration in Parkinson's disease and has prompted searches for natural compounds inhibiting αSN aggregation and reducing its tendency to form toxic oligomers. Oil from the olive tree (Olea europaea L.) represents the main source of fat in the Mediterranean diet and contains variable levels of phenolic compounds, many structurally related to the compound oleuropein. Here, using αSN aggregation, fibrillation, size-exclusion chromatography-multiangle light scattering (SEC-MALS)-based assays, and toxicity assays, we systematically screened the fruit extracts of 15 different olive varieties to identify compounds that can inhibit αSN aggregation and oligomer toxicity and also have antioxidant activity. Polyphenol composition differed markedly among varieties. The variety with the most effective antioxidant and aggregation activities, Koroneiki, combined strong inhibition of αSN fibril nucleation and elongation with strong disaggregation activity on preformed fibrils and prevented the formation of toxic αSN oligomers. Fractionation of the Koroneiki extract identified oleuropein aglycone, hydroxyl oleuropein aglycone, and oleuropein as key compounds responsible for the differences in inhibition across the extracts. These phenolic compounds inhibited αSN amyloidogenesis by directing αSN monomers into small αSN oligomers with lower toxicity, thereby suppressing the subsequent fibril growth phase. Our results highlight the molecular consequences of differences in the level of effective phenolic compounds in different olive varieties, insights that have implications for long-term human health.

Potent α-Synuclein Aggregation Inhibitors, Identified by High-Throughput Screening, Mainly Target the Monomeric State

α-Synuclein (αSN) aggregation is central to the etiology of Parkinson's disease (PD). Large-scale screening of compounds to identify aggregation inhibitors is challenged by stochastic αSN aggregation and difficulties in detecting early-stage oligomers (αSOs). We developed a high-throughput screening assay combining SDS-stimulated αSN aggregation with FRET to reproducibly detect initial stages in αSN aggregation. We screened 746,000 compounds, leading to 58 hits that markedly inhibit αSN aggregation and reduce αSOs' membrane permeabilization activity. The most effective aggregation inhibitors were derivatives of (4-hydroxynaphthalen-1-yl)sulfonamide. They interacted strongly with the N-terminal part of monomeric αSN and reduced αSO-membrane interactions, possibly by affecting electrostatic interactions. Several compounds reduced αSO toxicity toward neuronal cell lines. The inhibitors introduced chemical modifications of αSN that were, however, not a prerequisite for inhibitory activity. We also identified several phenyl-benzoxazol compounds that promoted αSN aggregation (proaggregators). These compounds may be useful tools to modulate αSN aggregation in cellula.

Early events in copper-ion catalyzed oxidation of α-synuclein

Previous studies on metal-ion catalyzed oxidation of α-synuclein oxidation have mostly used conditions that result in extensive modification precluding an understanding of the early events in this process. In this study, we have examined time-dependent oxidative events related to α-synuclein modification using six different molar ratios of Cu²⁺/H₂O₂/protein and Cu²⁺/H₂O₂/ascorbate/protein resulting in mild to moderate extents of oxidation. For a Cu²⁺/H₂O₂/protein molar ratio of 2.3:7.8:1 only low levels of carbonyls were detected (0.078 carbonyls per protein), whereas a molar ratio of 4.7:15.6:1 gave 0.22 carbonyls per α-synuclein within 15 min. With the latter conditions, rapid conversion of 3 out of 4 methionines (Met) to methionine sulfoxide, and 2 out of 4 tyrosines (Tyr) were converted to products including inter- and intra-molecular dityrosine cross-links and protein oligomers, as determined by SDS-PAGE and Western blot analysis. Limited histidine (His) modification was observed. The rapid formation of dityrosine cross-links was confirmed by fluorescence and mass-spectrometry. These data indicate that Met and Tyr oxidation are early events in Cu²⁺/H₂O₂-mediated damage, with carbonyl formation being a minor process. With the Cu²⁺/H₂O₂/ascorbate system, rapid protein carbonyl formation was detected with the first 5 min, but after this time point, little additional carbonyl formation was detected. With this system, lower levels of Met and Tyr oxidation were detected (2 Met and 1 Tyr modified with a Cu²⁺/H₂O₂/ascorbate/protein ratio of 2.3:7.8:7.8:1), but greater His oxidation. Only low levels of intra- dityrosine cross-links and no inter- dityrosine oligomers were detected under these conditions, suggesting that ascorbate limits Cu²⁺/H₂O₂-induced α-synuclein modification.

The Changing Face of Aging: Highly Sulfated Glycosaminoglycans Induce Amyloid Formation in a Lattice Corneal Dystrophy Model Protein

Glycosaminoglycans (GAGs) are related to multiple biological functions and diseases. There is growing evidence that GAG concentration and sulfate content increase with age. The destabilizing mutation A546T in the corneal protein TGFBIp leads to lattice-type corneal dystrophy, but symptoms only appear in the fourth decade of life. We hypothesize that this delayed phenotype can be explained by increased GAG sulfation over time. Using in vitro assays with the C-terminal TGFIBIp domain Fas1-4, previously shown to recapitulate many properties of full-length TGFBIp, we find that only long GAGs with multiple sulfate groups on each repeating unit increase the amount of worm-like aggregates and induce long, straight fibrils in A546T. In contrast, GAGs did not induce aggregation of wildtype Fas1-4, suggesting that the finding might be specific for lattice corneal dystrophy mutants. Our results highlight a possible role of changing GAG sulfation in the accumulation of amyloid, which also may have implications for the development of neurodegenerative diseases.

USE OF NEUTROPHILS TO LYMPHOCYTES RATIO AS AN INFLAMMATION MARKER IN PATIENTS WITH CHRONIC TONSILLITIS

The aim of this study was to assess the neutrophil to lymphocyte ratio (NLR) as an inflammation marker in patients with chronic tonsillitis and to compare the NLR values to other inflammation markers, such as antistreptolysin-O (ASO), C-Reactive Protein (CRP) and erythrocyte sedimentation rate (ESR). Thirty patients aged between 4 and 15 y.o. who had undergone surgery for chronic tonsillitis were included in this retrospective study. Blood samples including haemogram, ASO, CRP and ESR were taken from the patients the day before and one month after the surgery and were analysed retrospectively. Preoperative ASO values were 170±75.5 U, CRP values were 7.6±5 mg/L, ESR values were 15.7±10 mm/H and NLR values were 0.9±0.2. Postoperative ASO values were 140.9±58.5 U, CRP values were 6.8±3.4 mg/L, ESR values were 12.5±5.4 mm/H and NLR values were 1.2±0.4. Statistically significant decreases were observed in the white blood cell count (WBC), lymphocytes, ASO and ESR results, with increase in NLR values after the surgery (p<0.05). The neutrophil and CRP values after the surgery have shown statistically insignificant decrease (p>0.05). The NLR values were compared with the ASO, CRP and ESR values, which were used as inflammation markers. Negative correlation was found between decrease in ASO and ESR and increase in the NLR values after the surgery.

THE USEFULNESS OF MONITORING THE NEUTROPHIL TO LYMPHOCYTE RATIO IN PATIENTS WITH PERIPHERAL VERTIGO

The purpose of this study was to evaluate the usefulness of the neutrophil to lymphocyte ratio (NLR) in a differential diagnosis and follow-up of patients with peripheral vertigo. Twenty patients with benign positional paroxysmal vertigo (BPPV) and 20 patients diagnosed with vestibular neuritis (VN) were included in the study. Serum samples were analysed at the initial presentation and on the seventh day of admission retrospectively. The WBC (white blood cell) count was 10500±2100 /mm3, the neutrophil count was 4700±1100/mm3, the lymphocyte count was 5000±1200/mm3 and the NLR was 0.9±0.2 in the VN group. In patients with BPPV, the WBC count was 9200±1300/mm3, the neutrophil count was 5200±1200/mm3, the lymphocyte count was 3100±1200/mm3 and the NLR was 1.9±0.9. The NLR was lower in patients with VN than in patients diagnosed with BPPV. The WBC and lymphocyte count was significantly higher in the patients with VN than in the patients diagnosed with BPPV. Within the first week of admission, the WBC and lymphocyte counts in patients with VN decreased, and the NLR was more elevated than at the admission. It is highly recommended that NLR is used in the diagnosis and follow-up of the most commonly observed aetiological factors of peripheral vertigo, BPPV and VN.

Altered Stem Cell Receptor Activity in the Ovarian Surface Epithelium by Exogenous Zinc and/or Progesterone

BACKGROUND

Ovarian surface epithelium (OSE) has the characteristics of a stem cell and the potential for differentiation. Previous studies on this subject have succeeded in deriving oocytes from OSE stem cells, leading to the belief that OSE could be used for infertility treatment.

METHODS

Each rat (n = 10) was subjected to zinc and/or progesterone injection for 5 days after conception. After a 6-day implantation period, ovarian tissues were removed and comprehensive immunohistochemical analysis of stem cell markers was conducted: Sox2, Klf4, Oct3/4, c-Myc, CD117, CD90, SSEA-1 and Notch pathway analysis; Notch1, Jagged1, and Delta1 in the OSE and ovarian stromal cells were evaluated after treatment with zinc, progesterone, or both.

RESULTS

Progesterone moderately affected Sox2 expression (p < 0.001), while zinc application strongly affected Klf4 and Oct3/4 and immunoreactivity (p < 0.001). CD90 immunoreactivity was decreased in the OSE and stroma of the progesterone group (p = 0.006) compared with the zinc (p = 0.244) and zinc/progesterone groups (p = 0.910). On the other hand, SSEA-1 showed moderate staining in the OSE and weak staining in stromal cells in animals treated with zinc (p = 0.727), progesterone (p = 0.626), and zinc/progesterone (p = 0.371), with no differences compared with control. Zinc application affected Notch pathway immunoreactivity, with a significant increase in Notch1 (p = 0.0015) and Jagged1 (p < 0.001).

CONCLUSIONS

The expression of putative stem cell markers in the OSE was verified and stem cell receptor activity was raised in the OSE and ovarian stromal cells by zinc and progesterone. Thus, this increased expression allows the therapeutic use of zinc and progesterone in ovary-related infertility and brings a different perspective to reproductive medicine.

Does high maternal first trimester iron status have an effect on the 50 g oral glucose test?

We aimed to test the hypothesis that 1st trimester high body iron status is associated with a high positive 50 g oral glucose tolerance test. In this study, 29 pregnant women with positive 50 g oral glucose tolerance test were compared with 94 negative 50 g OGTT patients as the control group in terms of 1st trimester iron status. Both groups had similar age, weight, height, body mass index and also median gravidity and parity values. Our results showed that there were no differences between groups in mean haemoglobin, haematocrit, serum iron, serum ferritin, total iron binding capacity and transferrin. Since it seems that free radicals have much influence on oxidative stress and glucose metabolism, prospective, randomised clinical trials should be designed to demonstrate the possible relation between maternal iron status and glucose intolerance.

Contact radiator burn subsequent to spinal anaesthesia

An unusual case is reported in which a patient sustained a third-degree burn of the plantar surface of the right foot as the result of contact with a heating radiator. This occurred when the patient fell asleep in his hospital bed after knee surgery. Spinal anaesthesia is easy to perform, and the risk factors, though present, are not serious. Such accidents are not infrequent and care should be taken to prevent them.

[Major urologic surgical procedures in locally advanced colorectal cancers]

OBJECTIVE

To evaluate the outcomes of major urological procedures performed in patients with locally advanced colorectal cancer.

MATERIAL AND METHODS

Data of 37 patients with locally advanced colorectal cancer who underwent major urological surgical procedures along with simultaneous cancer surgery between the years of 2005 and 2010 were retrospectively evaluated.

RESULTS

The mean age was 58.3 years. Male/Female ratio was 2.7. 59% of the patients were primary, and 41% were recurrent cases of colorectal cancer. Bladder, ureters, urethra, kidneys and prostate were found as invaded in 19, 9, 5, 2 and 2 cases, respectively. The following single or combined procedures were performed; partial (n=11) or total (n=8; 2 combined with urethrocutaneostomy, 6 with ileal-conduit) cystectomy, urethroplasty (n=5), nephroureterectomy (n=2), radical nephrectomy (n=1), partial nephrectomy (n=1), ureteroneocystostomy (n=7), Boari's flap (n=4), transureteroureterostomy (n=3). Prolonged drainage was the most common surgical complication (27%). Urethrocutaneous fistula and total urinary incontinence were encountered in 1 and 1 patient, respectively. The incidence of hydronephrosis and elevated creatinine were 38% (preoperative 27%; postoperative 11%) and 24% (11% preoperative; 13% postoperative), respectively. Two deaths occurred in the first month of operations. Mean duration of follow up was 18(6-28) months for surviving 13 patients. Overall survival in 24 cases resulting in death was 21(1-42) months.

CONCLUSIONS

Since the most important eventual effects of locally advanced colorectal cancer are on the kidneys from the urological point of view; the aim of an urologist, as a member of surgical team, should be preserving renal function in addition to helping complete removal of the tumor.

Data filtering with support vector machines in geometric camera calibration

The use of non-metric digital cameras in close-range photogrammetric applications and machine vision has become a popular research agenda. Being an essential component of photogrammetric evaluation, camera calibration is a crucial stage for non-metric cameras. Therefore, accurate camera calibration and orientation procedures have become prerequisites for the extraction of precise and reliable 3D metric information from images. The lack of accurate inner orientation parameters can lead to unreliable results in the photogrammetric process. A camera can be well defined with its principal distance, principal point offset and lens distortion parameters. Different camera models have been formulated and used in close-range photogrammetry, but generally sensor orientation and calibration is performed with a perspective geometrical model by means of the bundle adjustment. In this study, support vector machines (SVMs) using radial basis function kernel is employed to model the distortions measured for Olympus Aspherical Zoom lens Olympus E10 camera system that are later used in the geometric calibration process. It is intended to introduce an alternative approach for the on-the-job photogrammetric calibration stage. Experimental results for DSLR camera with three focal length settings (9, 18 and 36 mm) were estimated using bundle adjustment with additional parameters, and analyses were conducted based on object point discrepancies and standard errors. Results show the robustness of the SVMs approach on the correction of image coordinates by modelling total distortions on-the-job calibration process using limited number of images.

Retrospective analysis of hysteroscopic findings in breast cancer patients having adjuvant tamoxifen treatment

PURPOSE OF INVESTIGATION

To evaluate the effects of tamoxifen on the endometrium of breast cancer patients by hysteroscopy and endometrial sampling.

METHODS

Thirty-seven breast cancer patients using tamoxifen underwent hysteroscopy because of postmenopausal endometrial thickening or abnormal uterine bleeding. Hysteroscopic findings were compared with histopathology and ultrasonographic measurement of the endometrium.

RESULTS

Nineteen women showed endometrial abnormalities (51%) out of 37 patients. Negative and positive predictive values for hysteroscopy in detecting endometrial abnormalities were 100% and 94%, respectively.

CONCLUSION

Endometrial surveillance is an important part of gynecological follow-up in breast cancer patients using tamoxifen and the liberal use of hysteroscopy aids in the diagnosis of abnormal endometrium.

Clinical evaluation of vulvar lichen sclerosus: case series

INTRODUCTION

Vulvar lichen sclerosus is a chronic dermatitis which is located in labial, perineal and perianal areas. The etiology of lichen sclerosus is multifactorial including genetic, autoimmune, hormonal and infectious aspects.

MATERIALS AND METHODS

A retrospective analysis was carried out of the medical records of 82 patients who were suffering from pruritus vulva. All patients had vulvar biopsy-proven diagnosis of lichen sclerosus.

RESULTS

Sixty-six of patients (80.4%) were in the postmenopausal period and 16 patients (19.5%) were in the premenopausal phase. Fifteen patients (18.2%) had thyroid disease, six had (7.3%) diabetes mellitus, five had (6.09%) asthma and five patients had (6.09%) other autoimmune diseases. Lichen sclerosus was most commonly located on the labia majora--58 cases (70.7%). Sixty-four patients (78.04%) had used only potent corticosteroid therapy as the sole treatment.

CONCLUSION

The first-line treatment is topical-potent or ultra-potent corticosteroids in the treatment of lichen sclerosis. Vulvar lichen sclerosis may be associated with autoimmune and thyroid diseases.

Analysis of pediatric burns in a tertiary burns center in istanbul, Turkey

INTRODUCTION

The factors and demographic features of pediatric patients with burns in eastern and western cultures differ from each other. In this retrospective study, our aim was to identify the demographic features of pediatric burns presenting to our tertiary burn center catering to a large population from Istanbul.

METHODS

The demographic data and information of 358 children with burns admitted to the GMM HTH burn center in Istanbul over a 7-year period (2001-2008) were retrospectively reviewed.

RESULTS

48 children with burn injuries were hospitalized in our burn center during the study period. Out of the total of 358 patients, 33.79% (121) were infants and toddlers, 39.66% (142) were in early childhood and 26.53% (95) belonged to the late childhood age group. Males were predominantly affected, the total male to female ratio being 1.3:1. 297 (82.9%) of the 358 subjects resided in urban environments and 61 (17.1%) lived in rural areas. Scalds accounted for more than half (88.16%) of all burns, followed by contact (4.96%), flame (3.43%), electrical (1.52%), chemical (1.52%) and sunburn (0.38). Boiling water was the commonest agent, followed by hot tea. The three most frequent areas of burns were the upper limb (126 cases, 31.18%), followed by the lower limb (105 cases, 25.9%), and the trunk (94 cases, 23.26%). The majority (74%) of the patients had burns covering up to 10% of TBSA, and in 98.8% of the patients' the burn size was less than 30% of TBSA.

CONCLUSION

This study demonstrates that the epidemiological features of pediatric burn patients, based on a review of such patients admitted to our burn center, differ in many aspects between eastern and western populations. Scalds occurring in a domestic setting, with mild to moderate burns, caused the vast majority of hospital admissions. It is necessary to improve the preventive programs and strategies in order to reduce the incidence of pediatric burn trauma.

Polyorchidism: sonographic and magnetic resonance image findings

Polyorchidism is a rare congenital anomaly frequently associated with maldescent testis, hernia, and torsion. Reports in the literature show an increased risk of testicular malignancy in the presence of polyorchidism. This entity has characteristic sonographic features and the diagnosis is often made on the basis of sonography. Magnetic resonance imaging might also be used for the diagnosis, but is more helpful in cases associated with cryptorchism or neoplasia. A conservative approach is the treatment of choice in uncomplicated cases.