Ultrashort Echo Time Imaging of the Osteochondral Junction in Subjects with Knee Osteoarthritis and Age-matched Healthy Volunteers

SYNOPSIS We describe in vivo translation of ultrashort TE (UTE) imaging of the osteochondral junction (OCJ) at the knee in 9 subjects with osteoarthritis (OA) and 4 age-matched healthy volunteers. The OCJ plays an important role in onset and progression of OA. Our study demonstrates that UTE imaging of the OCJ is repeatable and demonstrates OCJ defects in OA subjects but not in healthy volunteers. Areas of OCJ damage commonly co-locate to other osteochondral pathology (bone marrow lesions and cartilage defects). UTE imaging of the OCJ may be a helpful tool for assessing OCJ damage in clinical studies of OA. INTRODUCTION Disruption of the osteochondral junction (OCJ) is thought to play an important role in the onset and progression of osteoarthritis (OA). Using conventional MR imaging, direct visualisation of the OCJ is not possible due to inherent short T1 and T2 relaxation times of the OCJ tissues. However, by achieving echo times (TEs) of < 1 ms, ultrashort echo time (UTE) MR imaging allows direct visualisation of the OCJ. The normal OCJ appears as an area of linear high signal intensity (SI) on UTE images at the bone-cartilage interface. In OA it has been shown that this area of linear high SI can become thinned or absent, compatible with histological findings of OCJ defects(1, 2). These findings have been described in a number of cadaveric MR studies, but there are limited in vivo data available(3-5). The aims of this study were to compare the in vivo appearance of the OCJ on UTE MR imaging between subjects with knee OA and age-matched healthy volunteers, to determine the relationship between OCJ defects and other osteochondral pathology, and to assess test-retest repeatability. METHODS We imaged 9 participants with mild-moderate knee osteoarthritis, characterised by radiographs with medial tibiofemoral compartment predominant disease and Kellgren-Lawrence grades 2-3, and 4 age-matched healthy volunteers. Participants were imaged at baseline and 1 month. MR studies were performed on a 3T system (GE 750, GE Healthcare). The MR protocol consisted of standard clinical sequences (coronal and sagittal intermediate-weighted fat-saturated fast spin echo (FSE) sequences plus a coronal T1-weighted FSE sequence) and a sagittal dual-echo UTE gradient echo sequence acquired using a 3D cones trajectory (research prototype; repetition time 15 ms, TE 0.03/4.5 ms, flip angle 13o, field-of-view 18 x 18 cm, matrix 430 x 430, slice thickness 2 mm, number of averages 1, acquisition time ~ 7.5 minutes). To increase conspicuity of short T2 tissues, we performed weighted digital image subtraction of the longer TE (4.5 ms) from the shorter TE images (0.03 ms)(6). The presence or absence of characteristic linear high SI at the OCJ was scored in 12 regions for each knee, corresponding to tibiofemoral subdivisions commonly used for semi-quantitative scoring. The presence of bone marrow lesions (BML) or cartilage defects in the same regions was also recorded. Assessment was performed by a single musculoskeletal radiologist with 5 years' experience in OA research, blinded to group assignment. We used descriptive statistics to compare the number of regions with OCJ defects in subjects with OA and healthy volunteers, and to assess the frequency with which OCJ defects co-located with BMLs or cartilage defects. Test-retest repeatability was evaluated using kappa statistics. RESULTS Participant characteristics are displayed in table 1. Six out of 9 OA participants (67%) had an OCJ defect in at least one region compared to 0 out of 4 controls (0%). The most commonly involved region was the central medial tibia (4 participants). OCJ defects commonly co-located to BMLs (7 out of 10 OCJ defects, 70%) and cartilage defects (6 out of 10 OCJ defects, 60%). Results are displayed in table 2. Sample images are displayed in figures 1 - 3. The kappa value for test-retest repeatability of OCJ assessment using UTE was 0.83 (95% confidence interval 0.64 to 1). DISCUSSION The appearances of OCJ defects in subjects with OA in vivo are in keeping with abnormalities predicted by cadaveric MR and histology studies(1, 3). The biological plausibility of the findings is enhanced by the frequency of co-location of OCJ damage to other osteochondral pathology (BMLs and cartilage defects). Our findings demonstrate in vivo translation of UTE imaging of the OCJ, and suggest that this is a useful tool for future studies of OA onset and progression. This may include predicting response to intervention, as equine studies have demonstrated that the presence or absence of OCJ damage is an important predictor of response to treatment of cartilage defects(7). Our results demonstrate that UTE imaging of the OCJ is repeatable with kappa values in keeping with 'near-perfect' test-retest repeatability for qualitative assessment(8). Previous in vivo studies have not used age-matched control subjects, therefore it has been unclear whether areas of OCJ damage are related to OA or normal ageing(4). The normal appearance of the OCJ in age-matched control subjects in this study suggests that the OCJ defects are not part of normal ageing, although at present the number of healthy volunteers imaged is small. CONCLUSION In vivo UTE MR imaging of the OCJ is repeatable and demonstrates OCJ defects in subjects with OA. OCJ defects commonly co-locate with other osteochondral pathology

Effectively Measuring Exercise-Related Variations in T1ρ and T2 Relaxation Times of Healthy Articular Cartilage.

BACKGROUND: Determining the compositional response of articular cartilage to dynamic joint-loading using MRI may be a more sensitive assessment of cartilage status than conventional static imaging. However, distinguishing the effects of joint-loading vs. inherent measurement variability remains difficult, as the repeatability of these quantitative methods is often not assessed or reported. PURPOSE: To assess exercise-induced changes in femoral, tibial, and patellar articular cartilage composition and compare these against measurement repeatability. STUDY TYPE: Prospective observational study. POPULATION: Phantom and 19 healthy participants. FIELD STRENGTH/SEQUENCE: 3T; 3D fat-saturated spoiled gradient recalled-echo; T1ρ - and T2 -prepared pseudosteady-state 3D fast spin echo. ASSESSMENT: The intrasessional repeatability of T1ρ and T2 relaxation mapping, with and without knee repositioning between two successive measurements, was determined in 10 knees. T1ρ and T2 relaxation mapping of nine knees was performed before and at multiple timepoints after a 5-minute repeated, joint-loading stepping activity. 3D surface models were created from patellar, femoral, and tibial articular cartilage. STATISTICAL TESTS: Repeatability was assessed using root-mean-squared-CV (RMS-CV). Using Bland-Altman analysis, thresholds defined as the smallest detectable difference (SDD) were determined from the repeatability data with knee repositioning. RESULTS: Without knee repositioning, both surface-averaged T1ρ and T2 were very repeatable on all cartilage surfaces, with RMS-CV SDD) average exercise-induced in T1ρ and T2 of femoral (-8.0% and -5.3%), lateral tibial (-6.9% and -5.9%), medial tibial (+5.8% and +2.9%), and patellar (-7.9% and +2.8%) cartilage were observed. DATA CONCLUSION: Joint-loading with a stepping activity resulted in T1ρ and T2 changes above background measurement error. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY STAGE: 1 J. MAGN. RESON. IMAGING 2020;52:1753-1764.GlaxoSmithKline National Institute of Health Research (NIHR) Cambridge Biomedical Research Centr

Malaria surveillance from both ends: concurrent detection of Plasmodium falciparum in saliva and excreta harvested from Anopheles mosquitoes

Background: Malaria is the most important vector-borne disease in the world. Epidemiological and ecological studies of malaria traditionally utilize detection of Plasmodium sporozoites in whole mosquitoes or salivary glands by microscopy or serological or molecular assays. However, these methods are labor-intensive, and can over- or underestimate mosquito transmission potential. To overcome these limitations, alternative sample types have been evaluated for the study of malaria. It was recently shown that Plasmodium could be detected in saliva expectorated on honey-soaked cards by Anopheles stephensi, providing a better estimate of transmission risk. We evaluated whether excretion of Plasmodium falciparum nucleic acid by An. stephensi correlates with expectoration of parasites in saliva, thus providing an additional sample type for estimating transmission potential. Mosquitoes were exposed to infectious blood meals containing cultured gametocytes, and excreta collected at different time points post-exposure. Saliva was collected on honey-soaked filter paper cards, and salivary glands were dissected and examined microscopically for sporozoites. Excreta and saliva samples were tested by real time polymerase chain reaction (RT-rtPCR). Results: Plasmodium falciparum RNA was detected in mosquito excreta as early as four days after ingesting a bloodmeal containing gametocytes. Once sporogony (the development of sporozoites) occurred, P. falciparum RNA was detected concurrently in both excreta and saliva samples. In the majority of cases, no difference was observed between the Ct values obtained from matched excreta and saliva samples, suggesting that both samples provide equally sensitive results. A positive association was observed between the molecular detection of the parasites in both samples and the proportion of mosquitoes with sporozoites in their salivary glands from each container. No distinguishable parasites were observed when excreta samples were stained and microscopically analyzed. Conclusions: Mosquito saliva and excreta are easily collected and are promising for surveillance of malaria-causing parasites, especially in low transmission settings or in places where arboviruses co-circulate

Satellite derived offshore migratory movements of southern right whales (Eubalaena australis) from Australian and New Zealand wintering grounds

Funding: Australian Marine Mammal Center Grant 13/48 AIM, SDG, DH, AL http://www.marinemammals.gov.au/ The Australian Marine Mammal Center was involved in study design and anlaysis through the involvement in the project by AMMC staff, Dr Mike Double and Dr Virgina Andrews-Goff Princess Melikoff Trust Marine Mammal Conservation Program KC New Zealand Department of Conservation SC.Southern right whales (Eubalaena australis) migrate between Austral-winter calving and socialising grounds to offshore mid- to high latitude Austral-summer feeding grounds. In Australasia, winter calving grounds used by southern right whales extend from Western Australia across southern Australia to the New Zealand sub-Antarctic Islands. During the Austral-summer these whales are thought to migrate away from coastal waters to feed, but the location of these feeding grounds is only inferred from historical whaling data. We present new information on the satellite derived offshore migratory movements of six southern right whales from Australasian wintering grounds. Two whales were tagged at the Auckland Islands, New Zealand, and the remaining four at Australian wintering grounds, one at Pirates Bay, Tasmania, and three at Head of Bight, South Australia. The six whales were tracked for an average of 78.5 days (range: 29 to 150) with average individual distance of 38 km per day (range: 20 to 61 km). The length of individually derived tracks ranged from 645–6,381 km. Three likely foraging grounds were identified: south-west Western Australia, the Subtropical Front, and Antarctic waters, with the Subtropical Front appearing to be a feeding ground for both New Zealand and Australian southern right whales. In contrast, the individual tagged in Tasmania, from a sub-population that is not showing evidence of post-whaling recovery, displayed a distinct movement pattern to much higher latitude waters, potentially reflecting a different foraging strategy. Variable population growth rates between wintering grounds in Australasia could reflect fidelity to different quality feeding grounds. Unlike some species of baleen whale populations that show movement along migratory corridors, the new satellite tracking data presented here indicate variability in the migratory pathways taken by southern right whales from Australia and New Zealand, as well as differences in potential Austral summer foraging grounds.Publisher PDFPeer reviewe

Diffusional Channeling in the Sulfate-Activating Complex: Combined Continuum Modeling and Coarse-Grained Brownian Dynamics Studies

Enzymes required for sulfur metabolism have been suggested to gain efficiency by restricted diffusion (i.e., channeling) of an intermediate APS2– between active sites. This article describes modeling of the whole channeling process by numerical solution of the Smoluchowski diffusion equation, as well as by coarse-grained Brownian dynamics. The results suggest that electrostatics plays an essential role in the APS2– channeling. Furthermore, with coarse-grained Brownian dynamics, the substrate channeling process has been studied with reactions in multiple active sites. Our simulations provide a bridge for numerical modeling with Brownian dynamics to simulate the complicated reaction and diffusion and raise important questions relating to the electrostatically mediated substrate channeling in vitro, in situ, and in vivo

Male × Female Interaction for a Pre-Copulatory Trait, but Not a Post-Copulatory Trait, among Cosmopolitan Populations of Drosophila melanogaster

Sexual coevolution occurs when changes in the phenotype of one sex select for changes in the other sex. We can identify the “footprint” of this coevolution by mating males and females from different populations and testing for a male-female genotype interaction for a trait associated with male (or female) performance. Here we mated male Drosophila melanogaster from five different continents with females from their own and different continents to test for a male-female interaction for mating speed, a pre-copulatory trait, and female reproductive investment, a post-copulatory trait. We found a strong male-female interaction for mating speed, consistent with previous studies using different populations, suggesting that the potential for sexual coevolution for this trait is present in this species. In contrast, we did not detect a male-female interaction for female reproductive investment. Although a male-female interaction for mating speed is compatible with the hypothesis of ongoing sexual coevolution, the nature of our experimental design is unable to exclude alternate explanations. Thus, the evolutionary mechanisms promoting male-female genotype interactions for pre-copulatory mating traits in D. melanogaster warrant further investigation

Objective sequence-based subfamily classifications of mouse homeodomains reflect their in vitro DNA-binding preferences

Classifying proteins into subgroups with similar molecular function on the basis of sequence is an important step in deriving reliable functional annotations computationally. So far, however, available classification procedures have been evaluated against protein subgroups that are defined by experts using mainly qualitative descriptions of molecular function. Recently, in vitro DNA-binding preferences to all possible 8-nt DNA sequences have been measured for 178 mouse homeodomains using protein-binding microarrays, offering the unprecedented opportunity of evaluating the classification methods against quantitative measures of molecular function. To this end, we automatically derive homeodomain subtypes from the DNA-binding data and independently group the same domains using sequence information alone. We test five sequence-based methods, which use different sequence-similarity measures and algorithms to group sequences. Results show that methods that optimize the classification robustness reflect well the detailed functional specificity revealed by the experimental data. In some of these classifications, 73–83% of the subfamilies exactly correspond to, or are completely contained in, the function-based subtypes. Our findings demonstrate that certain sequence-based classifications are capable of yielding very specific molecular function annotations. The availability of quantitative descriptions of molecular function, such as DNA-binding data, will be a key factor in exploiting this potential in the future.Canadian Institutes of Health Research (MOP#82940)Sickkids FoundationOntario Research FundNational Science Foundation (U.S.)National Human Genome Research Institute (U.S.) (R01 HG003985

Population Dynamics of Aedes aegypti and Dengue as Influenced by Weather and Human Behavior in San Juan, Puerto Rico

Previous studies on the influence of weather on Aedes aegypti dynamics in Puerto Rico suggested that rainfall was a significant driver of immature mosquito populations and dengue incidence, but mostly in the drier areas of the island. We conducted a longitudinal study of Ae. aegypti in two neighborhoods of the metropolitan area of San Juan city, Puerto Rico where rainfall is more uniformly distributed throughout the year. We assessed the impacts of rainfall, temperature, and human activities on the temporal dynamics of adult Ae. aegypti and oviposition. Changes in adult mosquitoes were monitored with BG-Sentinel traps and oviposition activity with CDC enhanced ovitraps. Pupal surveys were conducted during the drier and wetter parts of the year in both neighborhoods to determine the contribution of humans and rains to mosquito production. Mosquito dynamics in each neighborhood was compared with dengue incidence in their respective municipalities during the study. Our results showed that: 1. Most pupae were produced in containers managed by people, which explains the prevalence of adult mosquitoes at times when rainfall was scant; 2. Water meters were documented for the first time as productive habitats for Ae. aegypti; 3. Even though Puerto Rico has a reliable supply of tap water and an active tire recycling program, water storage containers and discarded tires were important mosquito producers; 4. Peaks in mosquito density preceded maximum dengue incidence; and 5. Ae. aegypti dynamics were driven by weather and human activity and oviposition was significantly correlated with dengue incidence

Common Gene Variants in the Tumor Necrosis Factor (TNF) and TNF Receptor Superfamilies and NF-kB Transcription Factors and Non-Hodgkin Lymphoma Risk

BACKGROUND:A promoter polymorphism in the pro-inflammatory cytokine tumor necrosis factor (TNF) (TNF G-308A) is associated with increased non-Hodgkin lymphoma (NHL) risk. The protein product, TNF-alpha, activates the nuclear factor kappa beta (NF-kappaB) transcription factor, and is critical for inflammatory and apoptotic responses in cancer progression. We hypothesized that the TNF and NF-kappaB pathways are important for NHL and that gene variations across the pathways may alter NHL risk. METHODOLOGY/PRINCIPAL FINDINGS:We genotyped 500 tag single nucleotide polymorphisms (SNPs) from 48 candidate gene regions (defined as 20 kb 5', 10 kb 3') in the TNF and TNF receptor superfamilies and the NF-kappaB and related transcription factors, in 1946 NHL cases and 1808 controls pooled from three independent population-based case-control studies. We obtained a gene region-level summary of association by computing the minimum p-value ("minP test"). We used logistic regression to compute odds ratios and 95% confidence intervals for NHL and four major NHL subtypes in relation to SNP genotypes and haplotypes. For NHL, the tail strength statistic supported an overall relationship between the TNF/NF-kappaB pathway and NHL (p = 0.02). We confirmed the association between TNF/LTA on chromosome 6p21.3 with NHL and found the LTA rs2844484 SNP most significantly and specifically associated with the major subtype, diffuse large B-cell lymphoma (DLBCL) (p-trend = 0.001). We also implicated for the first time, variants in NFKBIL1 on chromosome 6p21.3, associated with NHL. Other gene regions identified as statistically significantly associated with NHL included FAS, IRF4, TNFSF13B, TANK, TNFSF7 and TNFRSF13C. Accordingly, the single most significant SNPs associated with NHL were FAS rs4934436 (p-trend = 0.0024), IRF4 rs12211228 (p-trend = 0.0026), TNFSF13B rs2582869 (p-trend = 0.0055), TANK rs1921310 (p-trend = 0.0025), TNFSF7 rs16994592 (p-trend = 0.0024), and TNFRSF13C rs6002551 (p-trend = 0.0074). All associations were consistent in each study with no apparent specificity for NHL subtype. CONCLUSIONS/SIGNIFICANCE:Our results provide consistent evidence that variation in the TNF superfamily of genes and specifically within chromosome 6p21.3 impacts lymphomagenesis. Further characterization of these susceptibility loci and identification of functional variants are warranted