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Charges' interaction in polyelectrolyte (nano)complexing of His6-OPH with peptides: Unpredictable results due to imperfect or useless concept?
Aslanli, A, Lyagin, I, Efremenko, E
International journal of biological macromolecules. 2019;:368-376
Abstract
Quorum Quenching (QQ) enzymes can be used to prevent bacterial antibiotic resistance by degradation of Quorum Sensing (QS) signaling molecules, for example N-acyl homoserine lactones (AHLs). This paper is aimed at the in silico investigation of the possible combinations of hexahistidine-tagged organophosphorus hydrolase (His6-OPH) with antimicrobial peptides (AMPs) to improve the enzyme activity and, promisingly, stability. This shall help creating a nanosized QQ preparation capable to hydrolyze different AHLs and possessing an antimicrobial activity. To achieve this, binding of AMPs and His6-OPH was simulated by molecular docking, and various interaction parameters (affinity, charge, contact area, etc.) of the generated models were studied. Both anionic and cationic polypeptides were shown to bind to His6-OPH with negligible effect of their charge, that significantly deviates from the charge-to-charge interaction concept. The (nano)complexes of His6-OPH with Indolicidin and Temporin A appear to have the most balanced characteristics which were issued experimentally also.
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Stimuli-Responsive, Pentapeptide, Nanofiber Hydrogel for Tissue Engineering.
Tang, JD, Mura, C, Lampe, KJ
Journal of the American Chemical Society. 2019;(12):4886-4899
Abstract
Short peptides are uniquely versatile building blocks for self-assembly. Supramolecular peptide assemblies can be used to construct functional hydrogel biomaterials-an attractive approach for neural tissue engineering. Here, we report a new class of short, five-residue peptides that form hydrogels with nanofiber structures. Using rheology and spectroscopy, we describe how sequence variations, pH, and peptide concentration alter the mechanical properties of our pentapeptide hydrogels. We find that this class of seven unmodified peptides forms robust hydrogels from 0.2-20 kPa at low weight percent (less than 3 wt %) in cell culture media and undergoes shear-thinning and rapid self-healing. The peptides self-assemble into long fibrils with sequence-dependent fibrillar morphologies. These fibrils exhibit a unique twisted ribbon shape, as visualized by transmission electron microscopy (TEM) and Cryo-EM imaging, with diameters in the low tens of nanometers and periodicities similar to amyloid fibrils. Experimental gelation behavior corroborates our molecular dynamics simulations, which demonstrate peptide assembly behavior, an increase in β-sheet content, and patterns of variation in solvent accessibility. Our rapidly assembling pentapeptides for injectable delivery (RAPID) hydrogels are syringe-injectable and support cytocompatible encapsulation of oligodendrocyte progenitor cells (OPCs), as well as their proliferation and three-dimensional process extension. Furthermore, RAPID gels protect OPCs from mechanical membrane disruption and acute loss of viability when ejected from a syringe needle, highlighting the protective capability of the hydrogel as potential cell carriers for transplantation therapies. The tunable mechanical and structural properties of these supramolecular assemblies are shown to be permissive to cell expansion and remodeling, making this hydrogel system suitable as an injectable material for cell delivery and tissue engineering applications.
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3.
Advances in primary mitochondrial myopathies.
de Barcelos, IP, Emmanuele, V, Hirano, M
Current opinion in neurology. 2019;(5):715-721
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Abstract
PURPOSE OF REVIEW Although mitochondrial diseases impose a significant functional limitation in the lives of patients, treatment of these conditions has been limited to dietary supplements, exercise, and physical therapy. In the past few years, however, translational medicine has identified potential therapies for these patients. RECENT FINDINGS For patients with primary mitochondrial myopathies, preliminary phase I and II multicenter clinical trials of elamipretide indicate safety and suggest improvement in 6-min walk test (6MWT) performance and fatigue scales. In addition, for thymidine kinase 2-deficient (TK2d) myopathy, compassionate-use oral administration of pyrimidine deoxynucleosides have shown preliminary evidence of safety and efficacy in survival of early onset patients and motor functions relative to historical TK2d controls. SUMMARY The prospects of effective therapies that improve the quality of life for patients with mitochondrial myopathy underscore the necessity for definitive diagnoses natural history studies for better understanding of the diseases.
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Chelating Surfaces for Oriented Human Serum Albumin Molecules.
Tuccitto, N, Messina, GML, Li-Destri, G, Wietecka, A, Marletta, G
Langmuir : the ACS journal of surfaces and colloids. 2019;(9):3354-3362
Abstract
Protein immobilization in a specific conformation or orientation at an interface is influenced by specific interactions with the outer layer of the surface. A strategy to build-up a complex construct which is able to orient protein molecules, based on metal-cation chelation processes, is reported. The proposed methodology implies the formation of a mercaptoundecanoic acid monolayer on a gold surface that is activated to attach covalently the tripeptide glycyl-l-histidyl-l-lysine (GHK) on the surface, whose sites are then employed to chelate copper ions, providing a selective platform for the orientation of human serum albumin (HSA) molecules. The protein adsorption process on GHK and GHK-Cu(II)-complex surfaces was monitored by the in situ quartz crystal microbalance with dissipation monitoring (QCM-D) and force spectroscopy technique. The changes in frequency and dissipation factor as well as the D- f plots from QCM-D measurements help to characterize the changes in the protein conformation and are confirmed by force curve spectroscopy results. An improved kinetic model, based on random sequential adsorption with variable protein footprints, has been developed to predict and simulate the experimentally found HSA average surface coverage onto the GHK and GHK-Cu(II)-complex surfaces.
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Control of AtaA-mediated bacterial immobilization by casein hydrolysates.
Ohara, Y, Yoshimoto, S, Hori, K
Journal of bioscience and bioengineering. 2019;(5):544-550
Abstract
Acinetobacter sp. Tol 5 exhibits an autoagglutinating nature and high adhesiveness to various abiotic surfaces through its bacterionanofiber protein AtaA. We have developed new bacterial immobilization methods utilizing the high adhesiveness of AtaA. We previously reported that salt is essential for the adhesiveness of AtaA. In the current study, we unexpectedly found that Tol 5 cells were not immobilized onto polyurethane foam support during growth in LB medium although AtaA was properly expressed and displayed onto the cell surface. The adhesion of Tol 5 resting cells was not affected by sugars but drastically inhibited by yeast extract and casein hydrolysates such as tryptone and casamino acids technical grade (CA-T). Some amino acids, which are major components of CA-T, partially inhibited the adhesion of Tol 5 cells. Experimental results suggested that oligopeptides might effectively inhibit the cell adhesion. Immobilized cells onto the support through AtaA were detached in CA-T solution. Also, the detached cells could be re-immobilized onto the support without impairing of their adhesiveness by replacing CA-T solution to a basal salt medium. Microscopic observation revealed that breaking of AtaA-mediated cell-cell interaction is important for the detachment of Tol 5 cells from the support. CA-T also inhibited AtaA-mediated autoagglutination and dispersed cell clumps through AtaA. This is the first report on adhesion inhibitors against AtaA and suggests that casein hydrolysates like CA-T would be a powerful tool for controlling AtaA-mediated bacterial immobilization.
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Arginine Biosynthesis Modulates Pyoverdine Production and Release in Pseudomonas putida as Part of the Mechanism of Adaptation to Oxidative Stress.
Barrientos-Moreno, L, Molina-Henares, MA, Pastor-García, M, Ramos-González, MI, Espinosa-Urgel, M
Journal of bacteriology. 2019;(22)
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Abstract
Iron is essential for most life forms. Under iron-limiting conditions, many bacteria produce and release siderophores-molecules with high affinity for iron-which are then transported into the cell in their iron-bound form, allowing incorporation of the metal into a wide range of cellular processes. However, free iron can also be a source of reactive oxygen species that cause DNA, protein, and lipid damage. Not surprisingly, iron capture is finely regulated and linked to oxidative-stress responses. Here, we provide evidence indicating that in the plant-beneficial bacterium Pseudomonas putida KT2440, the amino acid l-arginine is a metabolic connector between iron capture and oxidative stress. Mutants defective in arginine biosynthesis show reduced production and release of the siderophore pyoverdine and altered expression of certain pyoverdine-related genes, resulting in higher sensitivity to iron limitation. Although the amino acid is not part of the siderophore side chain, addition of exogenous l-arginine restores pyoverdine release in the mutants, and increased pyoverdine production is observed in the presence of polyamines (agmatine and spermidine), of which arginine is a precursor. Spermidine also has a protective role against hydrogen peroxide in P. putida, whereas defects in arginine and pyoverdine synthesis result in increased production of reactive oxygen species.IMPORTANCE The results of this study show a previously unidentified connection between arginine metabolism, siderophore turnover, and oxidative stress in Pseudomonas putida Although the precise molecular mechanisms involved have yet to be characterized in full detail, our data are consistent with a model in which arginine biosynthesis and the derived pathway leading to polyamine production function as a homeostasis mechanism that helps maintain the balance between iron uptake and oxidative-stress response systems.
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Pretreatment PET/CT imaging of angiogenesis based on 18F-RGD tracer uptake may predict antiangiogenic response.
Li, L, Ma, L, Shang, D, Liu, Z, Yu, Q, Wang, S, Teng, X, Zhang, Q, Hu, X, Zhao, W, et al
European journal of nuclear medicine and molecular imaging. 2019;(4):940-947
Abstract
PURPOSE To explore the relationship between metabolic uptake of the 18F-ALF-NOTA-PRGD2 (18F-RGD) tracer on positron emission tomography/computerized tomography (PET/CT) and the antiangiogenic effect of apatinib in patients with solid malignancies. MATERIALS AND PATIENTS Patients with measurable lesions scheduled for second- or third-line single-agent therapy with apatinib were eligible for this prospective clinical trial. All patients underwent 18F-RGD PET/CT examination before the start of treatment. Standardized uptake values (SUVs) of contoured tumor lesions were computed and compared using independent sample t-tests or the Mann-Whitney U test. Receiver-operating characteristic (ROC) curve analysis was used to determine accuracy in predicting response. Survival curves were compared using the Kaplan-Meier method. RESULTS Of 38 patients who consented to study participation, 25 patients with 42 measurable lesions met the criteria for inclusion in this response assessment analysis. The median follow-up time was 3 months (range, 1-10 months), and the median progression-free survival (PFS) was 3 months (95% confidence interval, 1.04-4.96). The SUVpeak and SUVmean were significantly higher in responding tumors than in non-responding tumors (4.98 ± 2.34 vs 3.59 ± 1.44, p = 0.048; 3.71 ± 1.15 vs 2.95 ± 0.49, P = 0.036). SUVmax did not differ between responding tumors and non-responding tumors (6.58 ± 3.33 vs 4.74 ± 1.83, P = 0.078). An exploratory ROC curve analysis indicated that SUVmean [area under the ROC curve (AUC) = 0.700] was a better parameter than SUVpeak (AUC = 0.689) for predicting response. Using a threshold value of 3.82, high SUVmean at baseline was associated with improved PFS (5.0 vs. 3.4 months, log-rank P = 0.036). CONCLUSION 18F-RGD uptake on PET/CT imaging pretreatment may predict the response to antiangiogenic therapy, with higher 18F-RGD uptake in tumors predicting a better response to apatinib therapy.
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Sex steroids mediate discrete effects on HDL cholesterol efflux capacity and particle concentration in healthy men.
Rubinow, KB, Vaisar, T, Chao, JH, Heinecke, JW, Page, ST
Journal of clinical lipidology. 2018;(4):1072-1082
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Abstract
BACKGROUND Exogenous testosterone decreases serum concentrations of high-density lipoprotein cholesterol (HDL-C) in men, but whether this alters cardiovascular risk is uncertain. OBJECTIVE To investigate the effects of testosterone and estradiol on HDL particle concentration (HDL-Pima) and metrics of HDL function. METHODS We enrolled 53 healthy men, 19 to 55 years of age, in a double-blinded, placebo-controlled, randomized trial. Subjects were rendered medically castrate using the GnRH receptor antagonist acyline and administered either (1) placebo gel, (2) low-dose transdermal testosterone gel (1.62%, 1.25 g), (3) full replacement dose testosterone gel (1.62%, 5 g) or (4) full replacement dose testosterone gel together with an aromatase inhibitor for 4 weeks. At baseline and end of treatment, serum HDL total macrophage and ABCA1-specific cholesterol efflux capacity (CEC), HDL-Pima and size, and HDL protein composition were determined. RESULTS Significant differences in serum HDL-C were observed with treatment across groups (P = .01 in overall repeated measures ANOVA), with increases in HDL-C seen after both complete and partial testosterone deprivation. Medical castration increased total HDL-Pima (median [interquartile range] 19.1 [1.8] nmol/L at baseline vs 21.3 [3.1] nmol/L at week 4, P = .006). However, corresponding changes in total macrophage CEC and ABCA1-specific CEC were not observed. Change in serum 17β-estradiol concentration correlated with change in total macrophage CEC (β = 0.33 per 10 pg/mL change in serum 17β-estradiol, P = .03). CONCLUSIONS Testosterone deprivation in healthy men leads to a dissociation between changes in serum HDL-C and HDL CEC. Changes in serum HDL-C specifically due to testosterone exposure may not reflect changes in HDL function.
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Will 68Ga PSMA-radioligands be the only choice for nuclear medicine in prostate cancer in the near future? A clinical update.
Cuccurullo, V, di Stasio, GD, Evangelista, L, Ciarmiello, A, Mansi, L
Revista espanola de medicina nuclear e imagen molecular. 2018;(2):103-109
Abstract
Prostate Cancer (PCa) represents the most common malignant tumor in men but according to the European Association of Urology (EAU) guidelines, a mass screening for PCa diagnosis should not be performed due to over-diagnosis and over-treatment related problems. An early clinical diagnosis is possible, mainly based on digital rectal examination and Prostatic Specific Agent (PSA) testing. However, the only mandatory test to define the presence of PCa is ultrasound guided-biopsy, obtained on multiple samples, which has also a high prognostic value. In this context, diagnostic imaging plays an important role as confirmed by EAU that in a 2016 update of their guidelines on PCa stated the importance of Positron Emission Tomography (PET) with 11C- or 18F-choline combined with computed tomography (CT) to identify local relapse, lymph node involvement and metastatic spread at all stages. Consequently, in 2017, the European Association of Nuclear Medicine (EANM) together with the Society of Nuclear Medicine and Molecular Imaging (SNMMI) published new guidelines for 68Ga-Prostate Specific Membrane Antigen (PSMA) PET/CT to help physicians in the recommendation, execution and interpretation of PET/CT scans in patients with PCa. Thus, the aim of this 'evidence paper' is to define the current diagnostic algorithm in PCa in order to increase the general level of confidence in approaching such a crucial topic.
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Elucidating the Structures of Amyloid Oligomers with Macrocyclic β-Hairpin Peptides: Insights into Alzheimer's Disease and Other Amyloid Diseases.
Kreutzer, AG, Nowick, JS
Accounts of chemical research. 2018;(3):706-718
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In the more than a century since its identification, Alzheimer's disease has become the archetype of amyloid diseases. The first glimpses of the chemical basis of Alzheimer's disease began with the identification of "amyloid" plaques in the brain in 1892 and extended to the identification of proteinaceous fibrils with "cross-β" structure in 1968. Further efforts led to the discovery of the β-amyloid peptide, Aβ, as a 40- or 42-amino acid peptide that is responsible for the plaques and fibrils. At this point, a three-decade-long marathon began to elucidate the structure of the fibrils and identify the molecular basis of Alzheimer's disease. Along the way, an alternative model began to emerge in which small aggregates of Aβ, called "oligomers", rather than fibrils, are the culprits that lead to neurodegeneration in Alzheimer's disease. This Account describes what is known about the structures of the fibrils and details our research group's efforts to understand the structural, biophysical, and biological properties of the oligomers in amyloid diseases. β-Sheets are the building blocks of amyloid fibrils and oligomers. Amyloid fibrils generally consist of extended networks of parallel β-sheets. Amyloid oligomers appear to be more compact enclosed structures, some of which are thought to be composed of antiparallel β-sheets comprising β-hairpins. β-Hairpins are special because their twisted shape, hydrophobic surfaces, and exposed hydrogen-bonding edges impart a unique propensity to form compact assemblies. Our laboratory has developed macrocyclic β-sheets that are designed to mimic β-hairpins formed by amyloidogenic peptides and proteins. The β-hairpin mimics contain two β-strand peptide fragments linked together at their N- and C-termini by two δ-linked ornithine turn mimics to create a macrocycle. An N-methyl group is installed on one of the β-strands to prevent uncontrolled aggregation. These design features facilitate crystallization of the β-hairpin mimics and determination of the X-ray crystallographic structures of the oligomers that they form. During the past few years, our laboratory has elucidated the X-ray crystallographic structures of oligomers formed by β-hairpin mimics derived from Aβ, α-synuclein, and β2-microglobulin. Out of these three amyloidogenic peptides and proteins, the Aβ β-hairpin mimics have provided the most insight into amyloid oligomers. Our studies have revealed a previously undiscovered mode of self-assembly, whereby three Aβ β-hairpin mimics assemble to form a triangular trimer. The triangular trimers are remarkable, because they contain two largely hydrophobic surfaces that pack together with other triangular trimers to form higher-order oligomers, such as hexamers and dodecamers. Some of the dodecamers pack in the crystal lattice to form annular porelike assemblies. Some of the β-hairpin mimics and triangular trimers assemble in solution to form oligomers that recapitulate the crystallographically observed oligomers. These oligomers exhibit toxicity toward neuronally derived cells, recapitulating the toxicity of the oligomers formed by full-length amyloidogenic peptides and proteins. These findings are significant, because they address a gap in understanding the molecular basis of amyloid diseases. We anticipate that these studies will pave the way for developing diagnostics and therapeutics to combat Alzheimer's disease, Parkinson's disease, and other amyloid diseases.