Probing Neuroserpin Polymerization and Interaction with Amyloid-β Peptides Using Single Molecule Fluorescence

Neuroserpin is a member of the serine proteinase inhibitor superfamily. It can undergo a conformational transition to form polymers that are associated with the dementia familial encephalopathy with neuroserpin inclusion bodies and the wild-type protein can inhibit the toxicity of amyloid-β peptides in Alzheimer's disease. We have used a single molecule fluorescence method, two color coincidence detection, to determine the rate-limiting steps of the early stages of the polymerization of fluorophore-labeled neuroserpin and have assessed how this process is altered in the presence of Aβ_1-40. Our data show that neuroserpin polymerization proceeds first by the unimolecular formation of an active monomer, followed by competing processes of both polymerization and formation of a latent monomer from the activated species. These data are not in keeping with the recently proposed domain swap model of polymer formation in which the latent species and activated monomer are likely to be formed by competing pathways directly from the unactivated monomeric serpin. Moreover, the Aβ_1-40 peptide forms a weak complex with neuroserpin (dissociation constant of 10 ± 5 nM) that increases the amount of active monomer thereby increasing the rate of polymerization. The Aβ_1-40 is displaced from the complex so that it acts as a catalyst and is not incorporated into neuroserpin polymers.     

Towards a framework for the study of the neural correlates of aesthetic preference

Aiming to provide a tentative framework for the study of the neural correlates of aesthetic preference, we review three recent neuroimaging studies carried out with the purpose of locating brain activity associated with decisions about the beauty of visual stimuli (Cela-Conde et al., 2004; Kawabata and Zeki, 2004; Vartanian and Goel, 2004). We find that the results of the three studies are not in line with previous neuropsychological data. Moreover, there are no coincidences among their results. However, when they are mapped on to Chatterjee's (2003) neuropsychological model of aesthetic preference it becomes clear that neuroimaging data are not contradictory, but complementary, and their interpretation is enriched. The results of these studies suggest that affective processes have an important role in aesthetic preference, and that they are integrated with cognitive processes to reach a decision regarding the beauty of visual stimuli. Future studies must aim to clarify whether certain methodological procedures are better suited to study any of the particular cognitive operations involved in aesthetic preference, and ascertain the extent to which the proposed framework is compatible with the aesthetic appreciation of musical stimuli.     

Concentration of Zinc,Copper, Iron,Calcium, and Magnesium in the Serum,Tissues, and Urine of Streptozotocin-Induced Mild Diabetic Rat Model

A survey carried out in Lake Tana in 2015 found that Hg levels in some fish species exceeded internationally accepted safe levels for fish consumption. The current study assesses human exposure to Hg through fish consumption around the Lake Tana. Of particular interest was that a dietary intake of fishes is currently a health risk for Bihar Dar residents and anglers. Hair samples were collected from three different groups: anglers, college students and teachers, and daily laborers. A questionary includes gender, age, weight, activity. Frequency of fish consumption and origin of the eaten fish were completed by each participant. Mercury concentrations in hair were significantly higher (P value <0.05) for anglers (mean?±?standard deviation 0.120?±?0.199 μg/g) than college students (mean?±?standard deviation 0.018?±?0.039 μg/g) or daily workers (mean?±?standard deviation 16?±?9.5 ng/g). Anglers consumed fish more often than daily workers and college group. Moreover, there was also a strong correlation (P value <0.05) between the logarithms of total mercury and age associated with mercury concentration in scalp hair. Mercury concentrations in the hair of men were on average twice the value of the women. Also, users of skin lightening soap on a daily basis had 2.5 times greater mercury in scalp hair than non-users. Despite the different sources of mercury exposure mentioned above, the mercury concentrations of the scalp hair of participants of this study were below levels deemed to pose a threat to health.     

Canine Hepacivirus NS3 Serine Protease Can Cleave the Human Adaptor Proteins MAVS and TRIF

Canine hepacivirus (CHV) was recently identified in domestic dogs and horses. The finding that CHV is genetically the virus most closely related to hepatitis C virus (HCV) has raised the question of whether HCV might have evolved as the result of close contact between dogs and/or horses and humans. The aim of this study was to investigate whether the NS3/4A serine protease of CHV specifically cleaves human mitochondrial antiviral signaling protein (MAVS) and Toll-IL-1 receptor domain-containing adaptor inducing interferon-beta (TRIF). The proteolytic activity of CHV NS3/4A was evaluated using a bacteriophage lambda genetic screen. Human MAVS- and TRIF-specific cleavage sites were engineered into the lambda cI repressor. Upon infection of Escherichia coli cells coexpressing these repressors and a CHV NS3/4A construct, lambda phage replicated up to 2000-fold more efficiently than in cells expressing a CHV protease variant carrying the inactivating substitution S139A. Comparable results were obtained when several HCV NS3/4A constructs of genotype 1b were assayed. This indicates that CHV can disrupt the human innate antiviral defense signaling pathway and suggests a possible evolutionary relationship between CHV and HCV.     

Neuroprotective role of quercetin in locomotor activities and cholinergic neurotransmission in rats experimentally demyelinated with ethidium bromide

Aim

The purpose of this study was to investigate whether the flavonoid quercetin can prevent alterations in the behavioral tests and of cholinergic neurotransmission in rats submitted to the ethidium bromide (EB) experimental demyelination model during events of demyelination and remyelination.

Main methods

Wistar rats were randomly distributed into four groups (20 animals per group): Control (pontine saline injection and treatment with ethanol), Querc (pontine saline injection and treatment with quercetin), EB (pontine 0.1% EB injection and treatment with ethanol), and EB + Querc (pontine 0.1% EB injection and treatment with quercetin). The groups Querc and Querc + EB were treated once daily with quercetin (50 mg/kg) diluted in 25% ethanol solution (1 ml/kg) and the animals of the control and EB groups were treated once daily with 25% ethanol solution (1 ml/kg). Two stages were observed: phase of demyelination (peak on day 7) and phase of remyelination (peak on day 21 post-injection). Behavioral tests (beam walking, foot fault and inclined plane test), acetylcholinesterase (AChE) activity and lipid peroxidation in pons, cerebellum, hippocampus, hypothalamus, striatum and cerebral cortex were measured.

Key findings

The quercetin promoted earlier locomotor recovery, suggesting that there was demyelination prevention or further remyelination velocity as well as it was able to prevent the inhibition of AChE activity and the increase of lipidic peroxidation, suggesting that this compound can protect cholinergic neurotransmission.

Significance

These results may contribute to a better understanding of the neuroprotective role of quercetin and the importance of an antioxidant diet in humans to provide benefits in neurodegenerative diseases such as MS.     

Metabolomics-Based Discovery of Small Molecule Biomarkers in Serum Associated with Dengue Virus Infections and Disease Outcomes

Background

Epidemic dengue fever (DF) and dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) are overwhelming public health capacity for diagnosis and clinical care of dengue patients throughout the tropical and subtropical world. The ability to predict severe dengue disease outcomes (DHF/DSS) using acute phase clinical specimens would be of enormous value to physicians and health care workers for appropriate triaging of patients for clinical management. Advances in the field of metabolomics and analytic software provide new opportunities to identify host small molecule biomarkers (SMBs) in acute phase clinical specimens that differentiate dengue disease outcomes.

Methodology/Principal Findings

Exploratory metabolomic studies were conducted to characterize the serum metabolome of patients who experienced different dengue disease outcomes. Serum samples from dengue patients from Nicaragua and Mexico were retrospectively obtained, and hydrophilic interaction liquid chromatography (HILIC)-mass spectrometry (MS) identified small molecule metabolites that were associated with and statistically differentiated DHF/DSS, DF, and non-dengue (ND) diagnosis groups. In the Nicaraguan samples, 191 metabolites differentiated DF from ND outcomes and 83 differentiated DHF/DSS and DF outcomes. In the Mexican samples, 306 metabolites differentiated DF from ND and 37 differentiated DHF/DSS and DF outcomes. The structural identities of 13 metabolites were confirmed using tandem mass spectrometry (MS/MS). Metabolomic analysis of serum samples from patients diagnosed as DF who progressed to DHF/DSS identified 65 metabolites that predicted dengue disease outcomes. Differential perturbation of the serum metabolome was demonstrated following infection with different DENV serotypes and following primary and secondary DENV infections.

Conclusions/Significance

These results provide proof-of-concept that a metabolomics approach can be used to identify metabolites or SMBs in serum specimens that are associated with distinct DENV infections and disease outcomes. The differentiating metabolites also provide insights into metabolic pathways and pathogenic and immunologic mechanisms associated with dengue disease severity.