Investigation of Quantitative Magnetization Transfer Magnetic Resonance Imaging as a Non-Invasive Technique to Assess the Biochemical, Mechanical, and Histologic Properties of Healthy and Osteoarthritic Meniscus and Cartilage

Osteoarthritis is a degenerative disease affecting entire joints and leading to pain, stiffness, and loss of mobility. It affects around 13% of the Canadian population and commonly presents in the knee. Traditionally, osteoarthritis has been visualized using radiography because it is the most accessible imaging method and can detect bone alterations, but this method is unable to show changes to the articular cartilage and meniscus, which have been shown to play an important role in the disease process. Quantitative magnetic resonance imaging (qMRI) is able to provide images of the soft tissue within the knee joint as well as numerical values representative of the state of the tissue health. One particular qMRI technique is quantitative magnetization transfer (qMT), and it allows for the determination of the properties of the bound pool within tissues (macromolecules such as proteoglycan and collagen) that has resonance too short to be captured with conventional MRI. Because qMT probes the properties of the hydrogen bound to macromolecules, it is expected to be more sensitive to the changes in composition of a tissue associated with osteoarthritis. The primary objective of this research is to establish a relationship between qMT parameters (f, k, T2b relaxation time, T2f relaxation time, and T1f relaxation time) and the biochemical, histological, and mechanical properties of human articular cartilage and meniscus, and a secondary objective is to compare in vivo to ex situ qMT parameters. Two separate studies were conducted using differing populations in order to accomplish these objectives. The first study assessed six human cadaver knees with no history of injury or illness in order to validate the methods and gain a baseline of values to be expected in a healthy population. Intact cadaver knees were imaged using qMT MRI techniques and qMT parameters extracted. Subsequent to imaging, core samples were taken from each meniscus and digested and assayed to determine the liquid, collagen, and proteoglycan contents. Menisci were dissected into pieces for histology and scored using an established histological scoring system customized to the meniscus. Pearson product moment and Spearman’s rho correlation coefficients were calculated for the biochemistry and histology results respectively compared to the qMT parameters to determine if any of the imaging metrics were predictive of the biochemical content or histological score. Results of this study showed several significant correlations between the qMT parameters and tissue properties. Some of these key findings included correlations in the collective samples where increasing liquid content was associated with decreasing bound pool fraction (r=-0.248, p<0.5); increasing collagen per dry mass showed increasing T1f (r=0.413, p<0.01) and T2f (r=0.510, p<0.01); and an increase in total histology score was related to a decrease in T1f (ρ=-0.232, p<0.05), T2f (ρ=-0.277, p<0.01), and T2b (ρ=-0.207, p<0.05). In the medial side samples, key correlations were observed between increasing collagen per dry mass and increasing T1f (r=0.477, p<0.01), T2f (r=0.585, p<0.01), and T2b (r=0.415, p<0.05); and increasing histology score and decreasing T1f (ρ=-0.232, p<0.05), T2f (ρ=-0.277, p<0.01), and T2b (ρ=-0.207, p<0.05). In the lateral side samples, key correlations were between increasing liquid content and decreasing f (r=-0.380, p<0.05) and increasing sulfated glycosaminoglycan (sGAG) per wet mass was associated with increases in f (r=0.391, p<0.05) and kf (r=0.404, p<0.05). The second study focused on an end-stage osteoarthritis population by assessing total knee arthroplasty patients. The aim of this study was to explore the relationships between qMT parameters and tissue properties in damaged tissue. Two patients were scanned using the qMT MRI protocol prior to their surgery, and the excised tissues were scanned post-operatively using the same sequence. From these samples, seven separate articular cartilage and meniscus surfaces (both medial and lateral) were assessed. After imaging, the surfaces underwent mechanical indentation testing and the instantaneous modulus, elastic fit mean squared error, and tissue thicknesses were determined. Core samples were then removed from the surfaces for biochemical and histological analysis. Biochemistry protocols were the same as utilized in the cadaver study, and histology preparation was the same as well with different scoring methods used depending on the tissue type (articular cartilage versus meniscus). Pearson and Spearman correlation coefficients were once again determined in order to assess correlations between the qMT parameters and the tissue properties. A Wilcoxon signed rank test was performed to assess differences between in vivo and ex situ qMT results. The key results of this study showed significant correlations in the in vivo cartilage between increasing instantaneous modulus and decreasing T1f (r=-0.221, p<0.05) and T2f (r=-0.233, p<0.05) in the lateral side samples; increasing liquid content and T1f (r=0.836, p<0.05) in the lateral samples; and histology score and f in the combined samples (ρ=0.670, p<0.05) and medial samples (ρ=1.000, p<0.01). In the ex situ cartilage, significant correlations were found between increasing histology score and decreasing T2b (ρ=-0.896, p<0.01) in the lateral samples. In the lateral menisci samples in vivo, key correlations were found between increasing liquid content and decreasing kf (r=-0.890, p<0.05); increasing sGAG/dry mass and increasing T2b (r=0.869, p<0.05); and increasing collagen/wet mass and increasing kf (r=0.820, p<0.05). In the lateral ex situ menisci, a negative correlation was observed between instantaneous modulus and T2f (r=-0.563, p<0.05). In the global surface analysis (combining all cartilage and meniscus surfaces), key correlations were between increasing liquid content and increasing T1f (r=0.926, p<0.01) and T2f (r=0.864, p<0.05); increasing sGAG/dry mass and increasing T1f (r=826 p<0.05) and T2f (r=0.964, p<0.01); increasing collagen/dry mass and decreasing T1f (r=-0.780, p<0.05); and increasing histology score and increasing T2f (ρ=0.893, p<0.01). Significant decreases in T1obs, T1f, T2f and T2b were also found from in vivo to ex situ scanning environments. The findings in the correlation analysis of this project show the potential of qMT MRI imaging as a valuable modality for determining the structure, function, and composition of osteoarthritic articular cartilage and meniscus. It has been shown that ex situ qMT parameters are not the same as in vivo but steps have been made in a direction towards quantifying the relationships between the differing environments. Possible uses of this technique lie in early diagnosis of OA, monitoring of disease progression, and evaluation of potential treatments

Experimental long-distance haplotyping of OCA2-HERC2 variants

The regulatory HERC2 SNP, rs12913832, is strongly associated with blue and brown eye colour. However, eye colour in heterozygous rs12913832 individuals is observed to vary greatly. Missense mutations in OCA2, such as rs1800407 and rs74653330, are associated with lighter eye colour in some but not all heterozygous rs12913832 individuals. Determining the physical linkage of these variants might help to further explain eye colour variation. So far, experimental haplotyping of these variants has been challenging because the genomic distance between them (~ 135 kb) exceeds the fragment lengths produced by commonly used DNA isolation kits. The aim for this study was to explore novel methods for long distance haplotyping to assess associations between OCA2-HERC2 haplotypes and eye colour. DNA was isolated from frozen blood samples collected from Norwegians that are known to be heterozygous for both HERC2 rs12913832 and OCA2 SNPs, either rs1800407 (n = 23) or rs74653330 (n = 17), using the newly commercially available Monarch® HMW (heigh molecular weight) DNA Extraction Kit (New England BioLabsinc). We successfully isolated DNA fragments up to 210 kb, which were long enough to haplotype OCA2-HERC2 loci by droplet digital PCR (ddPCR). Three haplotypes were observed in the study population: rs12913832:A-rs1800407:T in 22/23 individuals, rs12913832:A-rs1800407:C in 1/23 individuals and rs12913832:A-rs74653330:T in 16/16 individuals. As expected, all individuals with the rs12913832:A-rs74653330:T haplotype had intermediate to blue eye colour. However, the rs12913832:Ars1800407:T haplotype was observed in both blue and brown-eyed individuals, suggesting more research is needed

Association between copy number variations in the OCA2-HERC2 locus and human eye colour

Human eye colour variation is strongly associated with single nucleotide polymorphisms (SNPs) in the OCA2- HERC2 locus, especially rs12913832 that is found in an enhancer element of OCA2. In a previous study we found that 43 out of 166 individuals in a Norwegian population with the brown eye colour genotype HERC2 rs12913832:AA or AG, did not have the expected brown eye colour. To investigate if duplications or deletions in the OCA2-HERC2 locus could explain the blue eye colour in these individuals, we analysed massively parallel sequencing (MPS) data for copy number variations (CNVs) in the OCA2-HERC2 region. The ~500 kb long OCA2- HERC2 locus was sequenced in 94 individuals with the rs12913832:AG and AA genotypes. Of these, 43 were observed to have blue eye colour and 51 were observed to have brown eye colour. CNVs were analysed using R and the R-package panelcn.MOPS - CNV detection tool for targeted NGS panel data. In rs12913832:AG individuals, CNVs in 32 regions were significantly associated with blue eye colour (Benjamini-Hochberg adjusted pvalue ≤ 0.05). In rs12913832:AA individuals, CNVs in 14 regions were associated with blue eye colour using raw p-values (p ≤ 0.05). The functional effects of these CNVs on OCA2 expression are yet to be investigated. However, this study suggests that CNVs in the OCA2-HERC2 locus might explain why some of the rs12913832:AG and AA individuals have unexpectedly blue eyes

Association between Variants in the OCA2-HERC2 Region and Blue Eye Colour in HERC2 rs12913832 AA and AG Individuals

The OCA2-HERC2 region is strongly associated with human pigmentation, especially eye colour. The HERC2 SNP rs12913832 is currently the best-known predictor for blue and brown eye colour. However, in a previous study we found that 43 of 166 Norwegians with the brown eye colour genotype rs12913832:AA or AG, did not have the expected brown eye colour. In this study, we carried out massively parallel sequencing of a ~500 kbp HERC2-OCA2 region in 94 rs12913832:AA and AG Norwegians (43 blue-eyed and 51 brown-eyed) to search for novel blue eye colour variants. The new candidate variants were subsequently typed in a Norwegian biobank population (total n = 519) for population specific association analysis. We identified five new variants, rs74409036:A, rs78544415:T, rs72714116:T, rs191109490:C and rs551217952:C, to be the most promising candidates for explaining blue eye colour in individuals with the rs12913832:AA and AG genotype. Additionally, we confirmed the association of the missense variants rs74653330:T and rs121918166:T with blue eye colour, and observed lighter skin colour in rs74653330:T individuals. In total, 37 (86%) of the 43 blue-eyed rs12913832:AA and AG Norwegians could potentially be explained by these seven variants, and we suggest including them in future prediction models

Prediction of Eye Colour in Scandinavians Using the EyeColour 11 (EC11) SNP Set

Description of a perpetrator’s eye colour can be an important investigative lead in a forensic case with no apparent suspects. Herein, we present 11 SNPs (Eye Colour 11-EC11) that are important for eye colour prediction and eye colour prediction models for a two-category reporting system (blue and brown) and a three-category system (blue, intermediate, and brown). The EC11 SNPs were carefully selected from 44 pigmentary variants in seven genes previously found to be associated with eye colours in 757 Europeans (Danes, Swedes, and Italians). Mathematical models using three different reporting systems: a quantitative system (PIE-score), a two-category system (blue and brown), and a three-category system (blue, intermediate, brown) were used to rank the variants. SNPs with a sufficient mean variable importance (above 0.3%) were selected for EC11. Eye colour prediction models using the EC11 SNPs were developed using leave-one-out cross-validation (LOOCV) in an independent data set of 523 Norwegian individuals. Performance of the EC11 models for the two- and three-category system was compared with models based on the IrisPlex SNPs and the most important eye colour locus, rs12913832. We also compared model performances with the IrisPlex online tool (IrisPlex Web). The EC11 eye colour prediction models performed slightly better than the IrisPlex and rs12913832 models in all reporting systems and better than the IrisPlex Web in the three-category system. Three important points to consider prior to the implementation of eye colour prediction in a forensic genetic setting are discussed: (1) the reference population, (2) the SNP set, and (3) the reporting strategy

Determination of growth, mass, and body mass index of harbour porpoises (Phocoena phocoena): Implications for conservational status assessment of populations

Longitudinal data on individual growth and seasonal changes in body mass, girth, and blubber thickness are rarely available for cetaceans, making it difficult to assess their population composition and individual nutritional condition. During different time intervals from 1997 to 2020, we collected longitudinal data on length, body mass, girth,and blubber thickness from seventeen harbour porpoises (Phocoena phocoena) in human care. We compared Gompertz and von Bertalanffy growth curves to collected length data at age 0–4 years for five individuals with known dates of birth. Von Bertalanffy had the lowest AICc value and was used to predict the birth year of twelve animals which age had previously been estimated based on tooth ring analysis and ossification of flipper bones. The growth curve was accurate within 1 yr. of age estimates. Within the first year, the calves grew 66%, attaining 84% of their adult length, and reached asymptotic length at age 3–4. For adults, there were large seasonal variations in body mass, body mass index, girth, and blubber thickness, with up to 28% of variation in body mass between seasons. We predicted individual body mass within ± 2 kg using measurements of length and girth, allowing estimation of body mass index of individuals with unknown mass. Our findings enable monitoring and assessments of population composition as well as nutritional condition of individual harbour porpoises, which is crucial for assessing conservational status and guiding management

Genetic relationships of European, Mediterranean, and SW Asian populations using a panel of 55 AISNPs

The set of 55 ancestry informative SNPs (AISNPs) originally developed by the Kidd Lab has been studied on a large number of populations and continues to be applied to new population samples. The existing reference database of population samples allows the relationships of new population samples to be inferred on a global level. Analyses show that these autosomal markers constitute one of the better panels of AISNPs. Continuing to build this reference database enhances its value. Because more than half of the 25 ethnic groups recently studied with these AISNPs are from Southwest Asia and the Mediterranean region, we present here various analyses focused on populations from these regions along with selected reference populations from nearby regions where genotype data are available. Many of these ethnic groups have not been previously studied for forensic markers. Data on populations from other world regions have also been added to the database but are not included in these focused analyses. The new population samples added to ALFRED and FROG-kb increase the total to 164 population samples that have been studied for all 55 AISNPs

European code against cancer 4th edition: 12 ways to reduce your cancer risk

This overview describes the principles of the 4th edition of the European Code against Cancer and provides an introduction to the 12 recommendations to reduce cancer risk. Among the 504.6 million inhabitants of the member states of the European Union (EU28), there are annually 2.64 million new cancer cases and 1.28 million deaths from cancer. It is estimated that this cancer burden could be reduced by up to one half if scientific knowledge on causes of cancer could be translated into successful prevention. The Code is a preventive tool aimed to reduce the cancer burden by informing people how to avoid or reduce carcinogenic exposures, adopt behaviours to reduce the cancer risk, or to participate in organised intervention programmes. The Code should also form a base to guide national health policies in cancer prevention. The 12 recommendations are: not smoking or using other tobacco products; avoiding second-hand smoke; being a healthy body weight; encouraging physical activity; having a healthy diet; limiting alcohol consumption, with not drinking alcohol being better for cancer prevention; avoiding too much exposure to ultraviolet radiation; avoiding cancer-causing agents at the workplace; reducing exposure to high levels of radon; encouraging breastfeeding; limiting the use of hormone replacement therapy; participating in organised vaccination programmes against hepatitis B for newborns and human papillomavirus for girls; and participating in organised screening programmes for bowel cancer, breast cancer, and cervical cancer

Dissecting the Shared Genetic Architecture of Suicide Attempt, Psychiatric Disorders, and Known Risk Factors

Background Suicide is a leading cause of death worldwide, and nonfatal suicide attempts, which occur far more frequently, are a major source of disability and social and economic burden. Both have substantial genetic etiology, which is partially shared and partially distinct from that of related psychiatric disorders. Methods We conducted a genome-wide association study (GWAS) of 29,782 suicide attempt (SA) cases and 519,961 controls in the International Suicide Genetics Consortium (ISGC). The GWAS of SA was conditioned on psychiatric disorders using GWAS summary statistics via multitrait-based conditional and joint analysis, to remove genetic effects on SA mediated by psychiatric disorders. We investigated the shared and divergent genetic architectures of SA, psychiatric disorders, and other known risk factors. Results Two loci reached genome-wide significance for SA: the major histocompatibility complex and an intergenic locus on chromosome 7, the latter of which remained associated with SA after conditioning on psychiatric disorders and replicated in an independent cohort from the Million Veteran Program. This locus has been implicated in risk-taking behavior, smoking, and insomnia. SA showed strong genetic correlation with psychiatric disorders, particularly major depression, and also with smoking, pain, risk-taking behavior, sleep disturbances, lower educational attainment, reproductive traits, lower socioeconomic status, and poorer general health. After conditioning on psychiatric disorders, the genetic correlations between SA and psychiatric disorders decreased, whereas those with nonpsychiatric traits remained largely unchanged. Conclusions Our results identify a risk locus that contributes more strongly to SA than other phenotypes and suggest a shared underlying biology between SA and known risk factors that is not mediated by psychiatric disorders.Peer reviewe

Meeting Paris agreement objectives will temper seabird winter distribution shifts in the North Atlantic Ocean

We explored the implications of reaching the Paris Agreement Objective of limiting global warming to <2°C for the future winter distribution of the North Atlantic seabird community. We predicted and quantified current and future winter habitats of five North Atlantic Ocean seabird species (Alle alle, Fratercula arctica, Uria aalge, Uria lomvia and Rissa tridactyla) using tracking data for ~1500 individuals through resource selection functions based on mechanistic modeling of seabird energy requirements, and a dynamic bioclimate envelope model of seabird prey. Future winter distributions were predicted to shift with climate change, especially when global warming exceed 2°C under a “no mitigation” scenario, modifying seabird wintering hotspots in the North Atlantic Ocean. Our findings suggest that meeting Paris agreement objectives will limit changes in seabird selected habitat location and size in the North Atlantic Ocean during the 21st century. We thereby provide key information for the design of adaptive marine‐protected areas in a changing ocean