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ObjectiveTo investigate the natural history of central osteophytes (COs) by analyzing the structure and matrix composition of CO-associated cartilage using 3-T MRI at and 1-3 years before the onset of COs.Materials and methodsBaseline, 4- and 6-year knee MRIs of 400 participants in the Osteoarthritis Initiative were screened for the appearance of new COs. Twenty-eight subjects developed 31 COs. Using MRIs at CO onset and 1-3 years before CO onset, cartilage T2 values were calculated for the local cartilage preceding COs and the surrounding cartilage. Cartilage lesions local to the site of COs and bone marrow edema like lesions (BMELs) subjacent to COs were graded using whole organ MRI scores (WORMS). Wilcoxon tests were used to compare T2 values from the local and the surrounding cartilage at each time point and to compare T2 and WORMS between time points. Knee symptoms were recorded during this period.ResultsAll subjects showed local cartilage lesions before the development of COs. Mean cartilage WORMS increased from 1.56 ± 0.66 a period of 3 years before to 2.39 ± 0.75 with onset of COs (p = 0.008). Local T2 values in the area of the later-appearing COs were significantly higher compared with T2 values of the surrounding cartilage 3 (p = 0.044) and 2 years earlier (p = 0.031) and with the onset of COs (p = 0.025). No significant increase in symptoms was found with the onset of COs.ConclusionThis study provides evidence that focal cartilage structural and compositional degeneration precedes COs. No significant aggravation of knee symptoms was reported during the evolution of COs.

This article explores the use of hypervalent iodanes as catalysts in organic synthesis, specifically focusing on the chlorination of substrates. The authors investigate the use of iodoresorcinol lactate as a catalyst for enantioselective chlorinations, but encounter challenges with aromatic chlorination. They also discuss the need for further analysis of catalyst integrity in chlorination reactions. The authors are currently working on developing stereoselective chlorination-mediated reactions based on their findings. [Extracted from the article]

BackgroundOsteoarthritis (OA), a multifactorial disease causing joint degeneration, often leads to severe disability. The rising rates of disability highlight the need for implementing preventative measures at early stages of the disease, which would especially benefit subjects at high risk for OA development.PurposeTo develop a risk prediction tool for moderate-severe OA (TOARP) over 8 years based on subject characteristics, knee radiographs, and MRI data at baseline using data from the Osteoarthritis Initiative (OAI).Study typeRetrospective.Subjects641 subjects with no/mild radiographic OA (Kellgren-Lawrence [KL] 0-2) and no clinically significant symptoms (Western Ontario and McMaster Universities Arthritis Index [WOMAC] 0-1) were selected from the OAI.Field strength/sequenceMR images were obtained using 3.0T.AssessmentCompartment-specific cartilage and meniscus morphology and cartilage T2 were assessed. Baseline subject demographics, risk factors, KL score, cartilage WORMS score, presence of meniscus tear, and cartilage T2 were used to predict the development of moderate/severe OA (KL = 3-4 or WOMAC pain ≥5 or total knee replacement [TKR]) over 8 years.Statistical testsBest subsets variable selection followed by cross-validation were used to assess which combinations of variables best predict moderate/severe OA.ResultsModel 1 included KL score, previous knee injury in the last 12 months, age, gender, and BMI. Model 2 included all variables in Model 1 plus presence of cartilage defects in the lateral femur and patella, and presence of a meniscal tear. Model 3 included all variables in Models 1 and 2, plus cartilage T2 in the medial tibia and medial femur. Compared to Model 1 (cross-validated AUC = 0.67), Model 3 performed significantly better (AUC = 0.72, P = 0.04), while Model 2 showed a statistical trend (AUC = 0.71, P = 0.08).Data conclusionWe established a risk calculator for the development of moderate/severe knee OA over 8 years that includes radiographic and MRI data. The inclusion of MRI-based morphological abnormalities and cartilage T2 significantly improved model performance.Level of evidence2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:1517-1526.

ObjectiveThe purpose of this study was to determine the probability of structural worsening of knee cartilage and whole joint degeneration over 4-8 years based on cartilage T2 Z-scores at baseline.DesignRight knees with Kellgren-Lawrence (KL) grades of 0-2 in 587 participants from the Osteoarthritis Initiative were studied. 3T MR images were used to perform baseline cartilage T2 quantification and assess 4-year changes in cartilage morphology (WORMS scoring) in 5 regions. Changes in joint space narrowing (JSN) and KL were assessed over 8 years. T2 Z-scores were based on a reference database of knees without morphologic cartilage degeneration at baseline. Odds ratios for, and predicted probabilities of any worsening in WORMS cartilage, JSN and KL grade were obtained from logistic regression models.ResultsA one-unit increase in the baseline medial femur T2 Z-score was associated with cartilage worsening in the same region (OR = 1.59; P

ObjectivesTo evaluate the ability of different MRI sequences to detect chondrocalcinosis within knee cartilage and menisci, and to analyze the association with joint degeneration.MethodsSubjects with radiographic knee chondrocalcinosis (n = 90, age 67.7 ± 7.3 years, 50 women) were selected from the Osteoarthritis Initiative and matched to controls without radiographic chondrocalcinosis (n = 90). Visualization of calcium-containing crystals (CaC) was compared between 3D T1-weighted gradient-echo (T1GE), 3D dual echo steady-state (DESS), 2D intermediate-weighted (IW), and proton density (PD)-weighted fast spin-echo (FSE) sequences obtained with 3T MRI and correlated with a semiquantitative CaC score obtained from radiographs. Structural abnormalities were assessed using Whole-Organ MRI Score (WORMS) and logistic regression models were used to compare cartilage compartments with and without CaC.ResultsCorrelations between CaC counts of MRI sequences and degree of radiographic calcifications were highest for GE (rT1GE = 0.73, P  0.05). Meniscus WORMS was significantly higher in subjects with chondrocalcinosis compared to controls (P = 0.005). Cartilage defects were significantly more frequent in compartments with CaC than without (patella: P = 0.006; lateral tibia: P

PurposeThis work aimed to compare the diagnostic performance of a metal artifact suppression sequence (MAVRIC-SL) for imaging of hip arthroplasties (HA) at 1.5 and 3 Tesla (T) field strength.MethodsEighteen patients (10 females; aged 27-74) with HA were examined at 3.0 and 1.5 T within 3 weeks. The sequence protocol included 3D-MAVRIC-SL PD (coronal), 3D-MAVRIC-SL STIR (axial), FSE T1, FSE PD and STIR sequences. Anatomical structures and pathological findings were assessed independently by two radiologists. Artifact extent and technical quality (image quality, fat saturation and geometric distortion) were also evaluated. Findings at 1.5 and 3.0 T were compared using a Wilcoxon signed rank test.ResultsWhile image quality was better at 1.5 T, visualization of anatomic structures and clinical abnormalities was not significantly different using the two field strengths (p > 0.05). Fat suppression and amount of artifacts were significantly better at 1.5 T (p

In this account, we describe our journey leading to the discovery of a generally applicable umpolung method for the α-functionalization of ketones. Central to this reaction is the cyclic hypervalent fluoro-iodane, which is mostly known for various alkene functionalizations enabling, for example, the synthesis of fluoro-benzoxazepines, indoles, and ketones. During this work, we encountered α-functionalized ketones as minor side products. This observation prompted us to further investigate this reactivity, thus revealing a directed umpolung of pyridyl ketones by the fluoro-iodane. The key to the success was the unexpected non-covalent interaction between the nucleophile, substrate, and iodane. 1 Introduction 2 Cyclizations Triggered by the Fluorination of Styrenes 3 Umpolung Reactions Facilitated by Hypervalent Iodanes 4 Discovering and Evolving a Fluoro-Iodane-Triggered Regioselective α-Functionalization of Carbonyl Compounds 5 First Investigations on the Nitrogen-Directed Umpolung 6 Conclusion [ABSTRACT FROM AUTHOR]

Aza-Diels–Alder reactions are straightforward processes for the construction of N -heterocycles, featuring inherent atom-economy and stereospecificity. Intramolecular strategies allow the formation of bicyclic core structures with up to three stereocenters within a single step. Herein, this concept is combined with the chemistry of chiral Brønsted acid bound ortho -quinone methide imines to generate a range of interesting fused tetrahydroquinolines in a diastereo- and enantioselective- manner. [ABSTRACT FROM AUTHOR]

Abstract: Aza‐Diels–Alder reactions (ADARs) are powerful processes that furnish N‐heterocycles in a straightforward fashion. Intramolecular variants offer the additional possibility of generating bi‐ and polycyclic systems with high stereoselectivity. We report herein a novel Brønsted acid catalyzed process in which ortho‐quinone methide imines tethered to the dienophile via the N substituent react in an intramolecular ADAR to form complex quinolizidines and oxazinoquinolines in a one‐step process. The reactions proceed under very mild conditions, with very good yields and good to very good diastereo‐ and enantioselectivities. Furthermore, the process was extended to a domino reaction that efficiently combines substrate synthesis, ortho‐quinone methide imine formation, and ADAR. [ABSTRACT FROM AUTHOR]

Abstract: Aza‐Diels‐Alder‐Reaktionen (ADARs) sind leistungsfähige Prozesse zum schnellen und stereoselektiven Aufbau von Stickstoffheterocyclen. Intramolekulare Varianten bieten darüber hinaus die Möglichkeit, bi‐ und polycyclische Ringsysteme in einem Schritt mit hoher Stereoselektivität zu generieren. In dem hier entwickelten Brønsted‐Säure‐katalysierten Verfahren können nun erstmals ortho‐Chinonmethidimine, die über den Iminsubstituenten an ein Dienophil gebunden sind, in einer enantioselektiven ADAR mit inversem Elektronenbedarf zu komplexen Chinolizidin‐ und Oxazinochinolin‐Ringsystemen umgesetzt werden. Die Reaktionen laufen unter milden Bedingungen in sehr guten Ausbeuten und mit guten bis sehr guten Diastereo‐ und Enantioselektivitäten ab. Das Verfahren kann darüber hinaus zu einem Domino‐Prozess erweitert werden, der Substratsynthese, ortho‐Chinonmethid‐Bildung und ADAR effizient vereinigt. [ABSTRACT FROM AUTHOR]

Objective: The purpose of this study was to determine the probability of structural worsening of knee cartilage and whole joint degeneration over 4-8 years based on cartilage T2 Z-scores at baseline.Design: Right knees with Kellgren-Lawrence (KL) grades of 0-2 in 587 participants from the Osteoarthritis Initiative were studied. 3T MR images were used to perform baseline cartilage T2 quantification and assess 4-year changes in cartilage morphology (WORMS scoring) in 5 regions. Changes in joint space narrowing (JSN) and KL were assessed over 8 years. T2 Z-scores were based on a reference database of knees without morphologic cartilage degeneration at baseline. Odds ratios for, and predicted probabilities of any worsening in WORMS cartilage, JSN and KL grade were obtained from logistic regression models.Results: A one-unit increase in the baseline medial femur T2 Z-score was associated with cartilage worsening in the same region (OR = 1.59; P < 0.0001) and in any region (OR = 1.37; P < 0.0001), and with worsening JSN (OR = 1.82; P < 0.0001) and KL grades (OR = 1.69; P < 0.0001). Predicted probabilities of worsening in knees with a medial femur T2 Z-score from 2-4 were 38% for medial femur cartilage WORMS, 70% for any cartilage region, 28% for increasing JSN and 31% for increasing KL grade.Conclusion: Knees with elevated cartilage T2 (especially in the medial femur and those that are 2 to 4 SDs above the mean reference values) are significantly more likely to have structural worsening over 4 to 8 years. Knowing cartilage T2 Z-scores may aid in targeting prevention efforts at early stages of osteoarthritis.Level Of Evidence: 2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2017;46:1128-1136. [ABSTRACT FROM AUTHOR]