Bone Loss at Implant with Titanium Abutments Coated by Soda Lime Glass Containing Silver Nanoparticles: A Histological Study in the Dog

The aim of the present study was to evaluate bone loss at implants connected to abutments coated with a soda-lime glass containing silver nanoparticles, subjected to experimental peri-implantitis. Also the aging and erosion of the coating in mouth was studied. Five beagle dogs were used in the experiments. Three implants were placed in each mandible quadrant: in 2 of them, Glass/n-Ag coated abutments were connected to implant platform, 1 was covered with a Ti-mechanized abutment. Experimental peri-implantitis was induced in all implants after the submarginal placement of cotton ligatures, and three months after animals were euthanatized. Thickness and morphology of coating was studied in abutment cross-sections by SEM. Histology and histo-morphometric studies were carried on in undecalfied ground slides. After the induced peri-implantitis: 1.The abutment coating shown losing of thickness and cracking. 2. The histometry showed a significant less bone loss in the implants with glass/n-Ag coated abutments. A more symmetric cone of bone resorption was observed in the coated group. There were no significant differences in the peri-implantitis histological characteristics between both groups of implants. Within the limits of this in-vivo study, it could be affirmed that abutments coated with biocide soda-lime-glass-silver nanoparticles can reduce bone loss in experimental peri-implantitis. This achievement makes this coating a suggestive material to control peri-implantitis development and progression.     

Differential interactions of the antimicrobial peptide,RQ18, with phospholipids and cholesterol modulate its selectivity for microorganism membranes

BackgroundAntimicrobial peptides (AMPs) are molecules with potential application for the treatment of microorganism infections. We, herein, describe the structure, activity, and mechanism of action of RQ18, an α-helical AMP that displays antimicrobial activity against Gram-positive and Gram-negative bacteria, and yeasts from the Candida genus.MethodsA physicochemical-guided design assisted by computer tools was used to obtain our lead peptide candidate, named RQ18. This peptide was assayed against Gram-positive and Gram-negative bacteria, yeasts, and mammalian cells to determine its selectivity index. The secondary structure and the mechanism of action of RQ18 were investigated using circular dichroism, large unilamellar vesicles, and molecular dynamic simulations.ResultsRQ18 was not cytotoxic to human lung fibroblasts, peripheral blood mononuclear cells, red blood cells, or Vero cells at MIC values, exhibiting a high selectivity index. Circular dichroism analysis and molecular dynamic simulations revealed that RQ18 presents varying structural profiles in aqueous solution, TFE/water mixtures, SDS micelles, and lipid bilayers. The peptide was virtually unable to release carboxyfluorescein from large unilamellar vesicles composed of POPC/cholesterol, model that mimics the eukaryotic membrane, indicating that vesicles' net charges and the presence of cholesterol may be related with RQ18 selectivity for bacterial and fungal cell surfaces.ConclusionsRQ18 was characterized as a membrane-active peptide with dual antibacterial and antifungal activities, without compromising mammalian cells viability, thus reinforcing its therapeutic application.General significanceThese results provide further insight into the complex process of AMPs interaction with biological membranes, in special with systems that mimic prokaryotic and eukaryotic cell surfaces.     

Individual Variations in Serum Melatonin Levels through Time: Implications for Epidemiologic Studies

Melatonin, a marker for the circadian rhythm with serum levels peaking between 2AM and 5AM, is hypothesized to possess anti-cancer properties, making it a mechanistic candidate for the probable carcinogenic effect of circadian rhythm disruption. In order to weigh epidemiologic evidence on the association of melatonin with cancer, we must first understand the laboratory and biological sources of variability in melatonin levels measured in samples. Participants for this methodological study were men enrolled in the Prostate Lung Colorectal and Ovarian Cancer Screening Trial (PLCO). We measured serum melatonin levels over a five year period in 97 individuals to test if melatonin levels are steady over time. The Pearson correlation coefficient between two measures separated by 1 year was 0.87, while the correlation between two measures separated by 5 years was to 0.70. In an additional cross-sectional study of 292 individuals, we used Analysis of Variance to identify differences in melatonin levels between different lifestyle and environmental characteristics. Serum melatonin levels were slightly higher in samples collected from 130 individuals during the winter, (6.36±0.59 pg/ml) than in samples collected from 119 individuals during the summer (4.83±0.62 pg/ml). Serum melatonin levels were lowest in current smokers (3.02±1.25 pg/ml, p = 0.007) compared to never (6.66±0.66 pg/ml) and former (5.59±0.50 pg/ml) smokers whereas BMI did not significantly affect serum melatonin levels in this study. In conclusion, the high 5 year correlation of melatonin levels implies that single measurements may be used to detect population level associations between melatonin and risk of cancer. Furthermore, our results reiterate the need to record season of sample collection, and individual characteristics in order to maximize study power and prevent confounding.     

Maternal Hypermethioninemia Affects Neurons Number,Neurotrophins Levels,Energy Metabolism,and Na<Superscript>+</Superscript>,K<Superscript>+</Superscript>-ATPase Expression/Content in Brain of Rat Offspring

In the current study, we verified the effects of maternal hypermethioninemia on the number of neurons, apoptosis, nerve growth factor, and brain-derived neurotrophic factor levels, energy metabolism parameters (succinate dehydrogenase, complex II, and cytochrome c oxidase), expression and immunocontent of Na⁺,K⁺-ATPase, edema formation, inflammatory markers (tumor necrosis factor-alpha and interleukin-6), and mitochondrial hydrogen peroxide levels in the encephalon from the offspring. Pregnant Wistar rats were divided into two groups: the first one received saline (control) and the second group received 2.68 μmol methionine/g body weight by subcutaneous injections twice a day during gestation (approximately 21 days). After parturition, pups were killed at the 21st day of life for removal of encephalon. Neuronal staining (anti-NeuN) revealed a reduction in number of neurons, which was associated to decreased nerve growth factor and brain-derived neurotrophic factor levels. Maternal hypermethioninemia also reduced succinate dehydrogenase and complex II activities and increased expression and immunocontent of Na⁺,K⁺-ATPase alpha subunits. These results indicate that maternal hypermethioninemia may be a predisposing factor for damage to the brain during the intrauterine life.     

Bidirectional movement of aphid parasitoids (Braconidae: Aphidiinae) between crops and non-crop plants in agroecosystems of central Argentina

The movement of predators and parasitoids between natural and cultivated habitats is a common process in agroecosystems, which may be affected by different biotic and abiotic factors, mostly related to the availability of resources. Here, through a broad approach, we aimed to obtain an overview of factors affecting the bidirectional movement of aphid parasitoids (Braconidae: Aphidiinae) across cultivated habitats and their natural vegetated borders. Using bidirectional flight traps, we measured the number of parasitoids moving from borders to crops and vice versa, in fields of three common crop species (alfalfa, oat and wheat) in the Pampean region, Santa Fe, Argentina. The effects of the abundance of aphid prey, abundance and richness of flowers in both habitats, as well as temperature and wind speed on parasitoid movement, were assessed through generalized mixed models, considering sampling date and field as random factors. The relationship between parasitism percentages and parasitoid movement from the borders to the crops was explored separately for three pest aphid species: Aphis craccivora Koch, Rhopalosiphum padi (L.) and Schizaphis graminum (Rondani). Overall, we found a prevalence of parasitoids moving in the border-crop direction, mainly in wheat and alfalfa crops. Aphid abundance in the arrival habitat affected parasitoid movement in both directions. A link between parasitoid movement and parasitism percentages was observed for the aphid species S. graminum in wheat, suggesting a beneficial role of natural vegetation in pest control.     

Imprints of multiple glacial refugia in the Pyrenees revealed by phylogeography and palaeodistribution modelling of an endemic spider

Mediterranean mountain ranges harbour highly endemic biota in islandlike habitats. Their topographic diversity offered the opportunity for mountain species to persist in refugial areas during episodes of major climatic change. We investigate the role of Quaternary climatic oscillations in shaping the demographic history and distribution ranges in the spider Harpactocrates ravastellus, endemic to the Pyrenees. Gene trees and multispecies coalescent analyses on mitochondrial and nuclear DNA sequences unveiled two distinct lineages with a hybrid zone around the northwestern area of the Catalan Pyrenees. The lineages were further supported by morphological differences. Climatic niche‐based species distribution models (SDMs) identified two lowland refugia at the western and eastern extremes of the mountain range, which would suggest secondary contact following postglacial expansion of populations from both refugia. Neutrality test and approximate Bayesian computation (ABC) analyses indicated that several local populations underwent severe bottlenecks followed by population expansions, which in combination with the deep population differentiation provided evidence for population survival during glacial periods in microrefugia across the mountain range, in addition to the main Atlantic and Mediterranean (western and eastern) refugia. This study sheds light on the complexities of Quaternary climatic oscillations in building up genetic diversity and local endemicity in the southern Europe mountain ranges.     

First volumetric record of fungal spores in the atmosphere of Montevideo City,Uruguay: a 2-year survey

In Uruguay, aeromycological studies are restricted to a gravimetric analysis performed from December 1942 to March 1944 in Montevideo where spores of Pucciniaceae, Alternaria and Helminthosporium were the only specimens identified. Daily monitoring of airborne fungal spores was carried out for the first time in Montevideo, from April 2012 to March 2014, using a Rotorod sampler in order to evaluate the seasonal variation and influence of meteorological parameters. A total of 548,309.68 spores/m³ were recorded which belong to anamorphs of Higher Fungi (69.18 %), Phyla Ascomycota (12.62 %), Basidiomycota (8.01 %), Oomycota (0.37 %) and Myxomycota (0.06 %). Airborne spores occurred in Montevideo throughout the whole year. However, a seasonal pattern was revealed, with the highest concentrations recorded in autumn and summer. The most abundant spore types were Cladosporium (53.22 %), Alternaria (6.62 %), Didymella Group (5.86 %), Leptosphaeria Group (4.37 %) and Coprinus (4.3 %). Temperature appeared to be the most influential meteorological factor correlating significantly and positively with total spore, Cladosporium, Alternaria and Didymella Group abundance. Relative humidity influenced positively total spore, Cladosporium and Didymella Group concentrations while a weak negative association was obtained for Alternaria. Wind speed correlated negatively with total spore, Cladosporium, Alternaria and Didymella Group. Precipitation showed a negative influence on Alternaria, while positive correlations were observed for Didymella Group. For the first time, fungal spores considered allergenic were recorded in Montevideo atmosphere and the risk of exposure would have been high from December to June. However, long-term sampling is needed to define seasonal prevalence patterns and the influence of meteorological conditions on spore abundance.