Comparative characterization of ARC-PVD ZrN and PEO hydroxyapatite coatings on pure Ti-6Al-4V substrates for biomedical applications

The nanocrystalline films of zirconium nitride have been synthesized using ion-plasma vacuum-arc deposition technique on pure Ti-6Al-4V, whereas the hydroxyapatite coatings were deposited by the method of plasmaelectrolytic oxidation in alkaline electrolytes (hydroxyapatite + 1 М potassium hydroxide). Structure evaluation by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) with microanalysis (EDS) – were performed to study phase and chemical composition, surface morphology, microstructure of coatings. The formed HA PEO coatings with spheroidal structure contain the phases of CaTiO₃ calcium titanate, CaHPO₄ anhydrous dicalcium phosphate, and Ca₁₀(PO₄)₆(OH)₂ hydroxyapatite. It was revealed that ZrN single-phase coatings of cubic modification with finecrystalline grains of 20 nm in size were formed. This experimental study found that coating Ti-6Al-4V with ZrN and HA positively influences preosteoblast cell adhesion, which results in the almost complete coverage of the surface, along with a less number of cells grown on uncoated titanium surface.Нанокристалічні плівки нітриду цирконію було синтезовано методом іонно-плазмового вакуумно-дугового осадження на підкладки з Ti-6Al-4V, а покриття з гідроксиапатиту наносили методом плазмоелектролітичного оксидування в лужних електролітах (гідроксиапатит + 1 М гідроксид калію). Для вивчення фазового та хімічного складу, морфології поверхні, мікроструктури покриттів проводили структурні дослідження: рентгеноструктурний аналіз (РСА), скануючу електронну мікроскопію (СЕМ) з мікроаналізом (ЕДС). Сформовані покриття HA PEO зі сфероїдальною структурою містять фази титанату кальцію CaTiO₃, безводного дикальційфосфату CaHPO₄ та гідроксиапатиту Ca₁₀(PO₄)₆(OH)₂. Виявлено, що утворюються однофазні покриття ZrN кубічної модифікації з дрібнокристалічними зернами розміром 20 нм. Експериментальне дослідження показало, що покриття ZrN і HA на Ti-6Al-4V позитивно впливають на адгезію клітин преостеобластів, що призводить до майже повного покриття поверхні, порівнянно із меншою кількістю клітин, вирощених на титановій поверхні без покриття

Differences in the pattern and regulation of mineral deposition in human cell lines of osteogenic and non-osteogenic origin

Bone marrow-derived mesenchymal stem cells (MSCs) are widely used as a cellular model of bone formation, and can mineralize in vitro in response to osteogenic medium (OM). It is unclear, however, whether this property is specific to cells of mesenchymal origin. We analysed the OM response in 3 non-osteogenic lines, HEK293, HeLa and NTera, compared to MSCs. Whereas HEK293 cells failed to respond to OM conditions, the 2 carcinoma-derived lines NTera and HeLa deposited a calcium phosphate mineral comparable to that present in MSC cultures. However, unlike MSCs, HeLa and NTera cultures did so in the absence of dexamethasone. This discrepancy was confirmed, as bone morphogenetic protein inhibition obliterated the OM response in MSCs but not in HeLa or NTera, indicating that these 2 models can deposit mineral through a mechanism independent of established dexamethasone or bone morphogenetic protein signalling

Microclimate variability and long-term persistence of fragmented woodland

Favourable microclimates are predicted to buffer fragmented populations against the effects of environmental change, but ecological timeseries are often too short to establish the extent to which such microsites facilitate population persistence through multiple climate shifts. We investigate the effects of microclimatic heterogeneity on woodland resilience through millennial climate and disturbance shifts near northwest European woodland range limits. We use palaeoecological data from northern Scotland to study the effects of fragmentation on community composition and diversity in a potentially favourable microclimate, and compare palynological timeseries of tree abundance from five sites to assess the effects of favourable (low-lying sheltered) versus more marginal (higher altitude) settings on population persistence and stability. The sheltered site shows persistence of tree cover through Holocene climatic and anthropogenic shifts, including climatically-driven regional woodland contraction around 4400calBP (calendar years before present), when surviving woods became compositionally differentiated into upland pine and low-lying deciduous communities. A favourable microclimate can thus buffer woodlands against environmental shifts and increase continuity of canopy cover, but it does not generate stable communities. Compositional reorganisation is an essential stress response mechanism and should be accommodated by conservation managers. The replacement of deciduous taxa byPinus sylvestrisafter 1060calBP represents the decoupling of pine distribution from climate drivers by management intervention. As a result, current microrefugial woodland composition reflects late Holocene human intervention. Alternative models of community composition and behaviour from palaeoecology provide a stronger foundation for managing microsite communities than relict woods in contrasting environmental settings

Meta-analysis of type 2 Diabetes in African Americans Consortium

Type 2 diabetes (T2D) is more prevalent in African Americans than in Europeans. However, little is known about the genetic risk in African Americans despite the recent identification of more than 70 T2D loci primarily by genome-wide association studies (GWAS) in individuals of European ancestry. In order to investigate the genetic architecture of T2D in African Americans, the MEta-analysis of type 2 DIabetes in African Americans (MEDIA) Consortium examined 17 GWAS on T2D comprising 8,284 cases and 15,543 controls in African Americans in stage 1 analysis. Single nucleotide polymorphisms (SNPs) association analysis was conducted in each study under the additive model after adjustment for age, sex, study site, and principal components. Meta-analysis of approximately 2.6 million genotyped and imputed SNPs in all studies was conducted using an inverse variance-weighted fixed effect model. Replications were performed to follow up 21 loci in up to 6,061 cases and 5,483 controls in African Americans, and 8,130 cases and 38,987 controls of European ancestry. We identified three known loci (TCF7L2, HMGA2 and KCNQ1) and two novel loci (HLA-B and INS-IGF2) at genome-wide significance (4.15 × 10(-94)<P<5 × 10(-8), odds ratio (OR)  = 1.09 to 1.36). Fine-mapping revealed that 88 of 158 previously identified T2D or glucose homeostasis loci demonstrated nominal to highly significant association (2.2 × 10(-23) < locus-wide P<0.05). These novel and previously identified loci yielded a sibling relative risk of 1.19, explaining 17.5% of the phenotypic variance of T2D on the liability scale in African Americans. Overall, this study identified two novel susceptibility loci for T2D in African Americans. A substantial number of previously reported loci are transferable to African Americans after accounting for linkage disequilibrium, enabling fine mapping of causal variants in trans-ethnic meta-analysis studies.Peer reviewe

Measuring the CMB primordial B-modes with Bolometric Interferometry

The Q&U Bolometric Interferometer for Cosmology (QL’BIC) is the first bolometric interferometer designed to measure the primordial B-mode polarization of the Cosmic Microwave Background (CMB). Bolometric interferometry is a novel technique that combines the sensitivity of bolometric detectors with the control of systematic effects that is typical of interferometry, both key features in the quest for the faint signal of the primordial B-modes. A unique feature is the so-called “spectral imaging”, i.e., the ability to recover the sky signal in several sub-bands within the physical band during data analysis. This feature provides an in-band spectral resolution of ∆v/v ~ 0.04 that is unattainable by a traditional imager. This is a key tool for controlling the Galactic foregrounds contamination. In this paper, we describe the principles of bolometric interferometry, the current status of the QU BIC experiment and future prospects

Whole-genome sequencing reveals host factors underlying critical COVID-19

Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2,3,4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease

Information generation and processing systems that regulate periodontal structure and function

Article first published online: 11 AUG 2013The periodontium is a very dynamic organ that responds rapidly to mechanical and chemical stimuli. It is very complex in that it is composed of two hard tissues (cementum and bone) and two soft connective tissues (periodontal ligament and gingiva). Together these tissues are defined by the molecules expressed by the resident periodontal cells in each compartment and this determines not only the structure and function of the periodontium but also how it responds to infection and inflammation. The biological activity of these molecules is tightly regulated in time and space to preserve tissue homeostasis, influence inflammatory responses and participate in tissue regeneration. In this issue of Periodontology 2000 we explore new experimental approaches and data sets which help to understand the molecules and cells that regulate tissue form and structure in health, disease and regeneration.P. Mark Bartold and Christopher A. McCulloc