Relationship between CT-Derived Bone Mineral Density and UTE-MR-Derived Porosity Index in Equine Third Metacarpal and Metatarsal Bones.

Fatigue-related subchondral bone injuries of the third metacarpal/metatarsal (McIII/MtIII) bones are common causes of wastage, and they are welfare concerns in racehorses. A better understanding of bone health and strength would improve animal welfare and be of benefit for the racing industry. The porosity index (PI) is an indirect measure of osseous pore size and number in bones, and it is therefore an interesting indicator of bone strength. MRI of compact bone using traditional methods, even with short echo times, fail to generate enough signal to assess bone architecture as water protons are tightly bound. Ultra-short echo time (UTE) sequences aim to increase the amount of signal detected in equine McIII/MtIII condyles. Cadaver specimens were imaged using a novel dual-echo UTE MRI technique, and PI was calculated and validated against quantitative CT-derived bone mineral density (BMD) measures. BMD and PI are inversely correlated in equine distal Mc/MtIII bone, with a weak mean r value of -0.29. There is a statistically significant difference in r values between the forelimbs and hindlimbs. Further work is needed to assess how correlation patterns behave in different areas of bone and to evaluate PI in horses with and without clinically relevant stress injuries.

T2 mapping of cartilage in the equine distal interphalangeal joint with corresponding histology using 0.27 T and 3.0 T magnetic resonance imaging.

BACKGROUND: Low-field magnetic resonance imaging (MRI) is widely available to equine veterinarians yet is insensitive at detecting cartilage damage in the distal interphalangeal joint (DIPJ). T2 mapping is a quantitative imaging technique that can detect cartilage damage before morphological change is apparent. OBJECTIVES: Validation of a T2 mapping sequence on a low-field MR system. Correlation of the mean T2 relaxation time in sections of cartilage with varying levels of pathology using low- and high-field MRI. STUDY DESIGN: Cross-sectional study. METHODS: Eight phantoms with known (nominal) T2 values underwent low-field (0.27 T) MRI and 38 ex vivo DIPJs were imaged. A further 9 ex vivo DIPJs were imaged on both the low- and high-field MR systems. Immediately after imaging, the DIPJs were disarticulated and samples collected for histology. Histological sections were graded using the Osteoarthritis Research Society International (OARSI) scoring system. Fiji ImageJ software with the MRIAnalysisPak plugin was used to calculate T2 maps and draw the regions of interest (ROIs). RESULTS: There was close agreement between the nominal and the measured T2 values in the phantom study. Spearman's rank correlation demonstrated significant positive correlation between low- and high-field T2 measurements, rho 0.644 (p < 0.001). The intrarater agreement for T2 measurements was excellent, intraclass correlation coefficient (ICC) = 0.99 (95% confidence interval [CI] = 0.99-1.00), the inter-rater agreement was excellent, ICC = 0.88 (95% CI = 0.82-0.92) and there was good intrarater agreement for OARSI scores (к = 0.76). MAIN LIMITATIONS: Only a small number of histological samples were analysed. Both articular cartilage surfaces were measured within the ROI. There were no OARSI grade 0 control samples. CONCLUSIONS: A T2 mapping sequence on a low-field 0.27 T MR system was validated. There was a positive correlation between low- and high-field T2 measurements. The findings suggest a higher mean T2 relaxation time in pathological cartilage tissue examined in this study compared to normal equine cartilage tissue.

TET1 Directs Chondrogenic Differentiation by Regulating SOX9 Dependent Activation of Col2a1 and Acan In Vitro.

Skeletal development is a tightly orchestrated process in which cartilage and bone differentiation are intricately intertwined. Recent studies have highlighted the contribution of epigenetic modifications and their writers to skeletal development. Methylated cytosine (5mC) can be oxidized to 5-hydroxymethylcytosine (5hmC) by the Ten-eleven-translocation (TET) enzymes leading to demethylation. We have previously demonstrated that 5hmC is stably accumulated on lineage-specific genes that are activated during in vitro chondrogenesis in the ATDC5 chondroprogenitors. Knockdown (KD) of Tet1 via short-hairpin RNAs blocked ATDC5 chondrogenic differentiation. Here, we aimed to provide the mechanistic basis for TET1 function during ATDC5 differentiation. Transcriptomic analysis of Tet1 KD cells demonstrated that 54% of downregulated genes were SOX9 targets, suggesting a role for TET1 in mediating activation of a subset of the SOX9 target genes. Using genome-wide mapping of 5hmC during ATDC5 differentiation, we found that 5hmC is preferentially accumulated at chondrocyte-specific class II binding sites for SOX9, as compared with the tissue-agnostic class I sites. Specifically, we find that SOX9 is unable to bind to Col2a1 and Acan after Tet1 KD, despite no changes in SOX9 levels. Finally, we compared this KD scenario with the genetic loss of TET1 in the growth plate using Tet1 -/- embryos, which are approximately 10% smaller than their WT counterparts. In E17.5 Tet1 -/- embryos, loss of SOX9 target gene expression is more modest than upon Tet1 KD in vitro. Overall, our data suggest a role for TET1-mediated 5hmC deposition in partly shaping an epigenome conducive for SOX9 function. © 2020 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Cancer antigen 125 is associated with disease status in uterine carcinosarcoma.

Uterine carcinosarcoma is a rare and aggressive tumor with poor outcomes. Cancer antigen 125 is routinely used to track the disease course of ovarian cancer and has been suggested as a biomarker in other aggressive forms of uterine cancer. We sought to characterize cancer antigen 125 as a potential biomarker of disease status in uterine carcinosarcoma. Clinical and pathological data were abstracted for patients who had surgical staging for a pathologically confirmed uterine carcinosarcoma at our institution from January 2000 to March 2014. Non-parametric tests were used to compare changes in cancer antigen 125. Elevated cancer antigen 125 (>35 U/mL) as a predictor of survival was assessed via Kaplan-Meier curves. Among the 153 patients identified, 66 patients had at least one paired measure of cancer antigen 125 drawn preoperatively, post-treatment, or at the time of disease recurrence, and 19 patients had cancer antigen-125 levels at all three time points. Analysis of the 51 patients with both preoperative and post-treatment values found a significant drop in cancer antigen 125 (p < 0.001). Among the 30 patients who had end-of-treatment and recurrence levels, a significant increase was noted (p = 0.001). There was no significant difference in cancer antigen-125 levels preoperatively compared to at recurrence among the 23 patients with levels at both time-points (p = 0.99). Elevated preoperative cancer antigen 125 was not associated with overall survival (p = 0.12); elevated post-treatment cancer antigen 125 was associated with a worse overall survival (p < 0.001). Based on this dataset, there seems to be utility in trending a cancer antigen-125 level in patients with uterine carcinosarcoma. A cancer antigen-125 level could predict recurrence and provide prognostic information regarding survival.

Prognostic Significance of omental Disease and the Role of Omental Sampling in Patients With Uterine Carcinosarcoma.

OBJECTIVES: Uterine carcinosarcomas are an aggressive and rare form of endometrial cancer. Omentectomy is not part of routine staging, but biopsy is often done because omental disease is a known poor prognostic indicator. We sought to define the role of routine omental sampling during surgical staging. METHODS/MATERIALS: Patients who underwent staging for uterine carcinosarcoma at our institution from January 2000 to December 2013 were identified. Clinical and pathological data were abstracted. Univariate and multivariable Cox proportional hazard regression analysis was used to identify significant predictors of progression-free (PFS) and overall survival (OS). Logistic regression was used to identify predictors of omental disease. RESULTS: We identified 153 patients. The median age was 65 years (range, 40-87 years), and 88.9% were Caucasian. Omental sampling was performed in 106 (69.3%) patients. Of these, 17(16%) had pathologically confirmed omental disease, and 6 (35.3%) with microscopic disease. On multivariable analysis, tumor size (P = 0.024) and postoperative radiation (P = 0.041) were significant predictors of progression-free survival, and omental disease (P = 0.002), residual disease (P = 0.03), and tumor size (P = 0.025) were significant predictors of OS. Median OS was 11.4 versus 128.7 months for those who did and did not have omental disease, respectively (P <0.001). The median OS for those who had omental sampling (127.7 months) versus those who did not (71.3 months) was not significantly different (P = 0.7432). CONCLUSIONS: Although survival was not significantly different between those who did and did not have omental sampling, omental disease had a significant impact on survival. Of those with omental disease, 35% had microscopic disease that could be missed if routine biopsy is not performed, suggesting a role for routine omental sampling.

Frequency of Penetration of the Digital Flexor Tendon Sheath and Distal Interphalangeal Joint Using a Direct Endoscopic Approach to the Navicular Bursa in Horses.

OBJECTIVE: To evaluate the frequency of inadvertent penetration of the digital flexor tendon sheath (DFTS) and/or distal interphalangeal joint (DIPJ) when using a direct endoscopic approach to the navicular bursa, and to evaluate an alternate direct approach to the navicular bursa. STUDY DESIGN: Cadaveric study. SAMPLE POPULATION: Equine cadaver limbs (n = 40 for direct; n = 12 for alternate approach). METHODS: Four surgeons performed the direct endoscopic approach to the navicular bursa on 10 limbs each. Frequencies of inadvertent synovial penetration and iatrogenic damage were compared between surgeons. Use of an alternate direct approach, adopting a straight parasagittal trajectory, was evaluated by 2 surgeons. RESULTS: Inadvertent synovial penetration occurred in 45% of limbs (DFTS 37.5%; DIPJ 17.5%; and both structures 10%). Successful bursa entry was achieved on the first attempt in 45% of limbs. Significant variation in frequency of inadvertent synovial penetration was observed between surgeons (range 10-80%). Inadvertent synovial penetration did not occur when using the alternate direct technique. Iatrogenic damage to navicular bone fibrocartilage and/or deep digital flexor tendon occurred in 55% of limbs using the direct endoscopic approach and in 0% of limbs using the alternate direct approach. CONCLUSION: Because of the considerable risk of inadvertent penetration of the DFTS and/or the DIPJ when making a direct endoscopic approach to the navicular bursa, it is advisable to investigate for inadvertent penetration when treating navicular bursa sepsis using a direct approach. The alternate direct technique may reduce the risk of inadvertent penetration; however, the view within the bursa may be restricted.