Equisetum praealtum and E. hyemale have abundant Rubisco with a high catalytic turnover rate and low CO2 affinity.

The kinetic properties of Rubisco, a key enzyme for photosynthesis, have been examined in numerous plant species. However, this information on some plant groups, such as ferns, is scarce. This study examined Rubisco carboxylase activity and leaf Rubisco levels in seven ferns, including four Equisetum plants (E. arvense, E. hyemale, E. praealtum, and E. variegatum), considered living fossils. The turnover rates of Rubisco carboxylation (kcatc) in E. praealtum and E. hyemale were comparable to those in the C4 plants maize (Zea mays) and sorghum (Sorghum bicolor), whose kcatc values are high. Rubisco CO2 affinity, estimated from the percentage of Rubisco carboxylase activity under CO2 unsaturated conditions in kcatc in these Equisetum plants, was low and also comparable to that in maize and sorghum. In contrast, kcatc and CO2 affinities of Rubisco in other ferns, including E. arvense and E. variegatum were comparable with those in C3 plants. The N allocation to Rubisco in the ferns examined was comparable to that in the C3 plants. These results indicate that E. praealtum and E. hyemale have abundant Rubisco with high kcatc and low CO2 affinity, whereas the carboxylase activity and abundance of Rubisco in other ferns were similar to those in C3 plants. Herein, the Rubisco properties of E. praealtum and E. hyemale were discussed regarding their evolution and physiological implications.

Epidemiological features of acute medial meniscus posterior root tears.

PURPOSE: Untreated or overlooked medial meniscus posterior root tears (MMPRTs) induce sequential knee joint degradation. We evaluated epidemiological features of acute MMPRT for its early detection and accurate diagnosis. METHODS: Among 330 MMPRT patients from 2018 to 2020, those who underwent arthroscopic pullout repairs were enrolled. Patients who underwent non-operative treatment or knee arthroplasty, those with a cruciate ligament-deficient knee or advanced osteoarthritis of the knee, and those with insufficient data were excluded. Finally, we retrospectively evaluated data from 234 MMPRTs (female: 79.9%, complete tears: 92.7%, mean age: 65 years). Welch's t-test and Chi-squared test were used for pairwise comparisons. Spearman's rank correlation analysis was performed between age at surgery and body mass index (BMI). Multivariable logistic regression analysis with stepwise backward elimination was applied to the values as risk factors for painful popping events. RESULTS: In both sexes, there were significant differences in height, weight, and BMI. In all patients, there was a significant negative correlation between BMI and age (ρ = - 0.36, p < 0.001). The BMI cutoff value of 27.7 kg/m2 had a 79.2% sensitivity and a 76.9% specificity for detecting MMPRT patients aged < 50 years. A painful popping event was confirmed in 187 knees (79.9%), and the frequency was significantly reduced in partial tears as compared to complete tears (odds ratio: 0.080, p < 0.001). CONCLUSION: Higher BMI was associated with a significantly younger age of MMPRT onset. Partial MMPRTs had a low frequency of painful popping events (43.8%).

Different photorespiratory mechanisms in conifer leaves, where peroxisomes have intrinsically low catalase activity.

Photorespiration is an essential metabolic mechanism associated with photosynthesis; however, little is known about the photorespiratory pathway of conifer gymnosperms. Metabolite analyses of the leaves of 27 tree species showed that the mean glycerate content in conifer leaves was lower than that in angiosperm leaves. We performed experiments where [13 C]-serine was fed to detached shoots of a conifer (Cryptomeria japonica), via the transpiration stream, and compared the labeling patterns of photorespiratory metabolites with those of an angiosperm tree (Populus nigra), because glycerate is produced from serine via hydroxypyruvate in peroxisomes. In P. nigra, hydroxypyruvate, glycerate and glycine were labeled with 13 C, whereas in C. japonica, glycolate and a non-canonical photorespiratory metabolite, formate, were also labeled, suggesting that an H2 O2 -mediated non-enzymatic decarboxylation (NED) reaction occurs in C. japonica. We analyzed changes in the metabolite contents of leaves kept in the dark and leaves exposed to illuminated photorespiration-promoting conditions: a positive relationship between formate and serine levels in C. japonica implied that the active C1 -metabolism pathway synthesizes serine from formate. Leaf gas exchange analyses revealed that CO2 produced through NED was recaptured by chloroplasts. Database analysis of the peroxisomal targeting signal motifs of an H2 O2 -scavenging enzyme, catalase, derived from various species, including nine coniferous species, as well as analyses of peroxisomal fractions isolated from C. japonica and P. nigra leaves indicated that conifer peroxisomes had less catalase activity. These results suggest that NED and the subsequent C1 metabolism are involved in the photorespiratory pathway of conifer leaves, where peroxisomes have intrinsically low catalase activity.

Ipsilateral Periprosthetic Fractures above and below the Knee Associated with Navigation Tracker Pin and Bone Fragility.

We report a case of ipsilateral periprosthetic fractures above and below the knee that occurred at different times due to navigation tracker pin and bone fragility. A 66-year-old Japanese woman with rheumatoid arthritis (RA) underwent a total knee arthroplasty. Four months post-surgery, a periprosthetic fracture above the knee at the navigation pin hole was detected. She underwent osteosynthesis and could walk independently, but she developed an ipsilateral tibial component fracture. Conservative treatment with a splint was followed by bone union. Patients with RA treated with oral steroids tend to develop ipsilateral periprosthetic fractures around the knee due to bone fragility.

The stability of repaired meniscal root can affect postoperative cartilage status following medial meniscus posterior root repair.

BACKGROUND: Transtibial pullout repair yields beneficial clinical outcomes in patients with medial meniscus (MM) posterior root tear. However, the relationship between repaired meniscal root healing status and postoperative clinical outcomes remains unclear. We aimed to evaluate changes in articular cartilage damage and clinical scores after pullout repair using two simple stitches (TSS). METHODS: Thirty-three patients who underwent pullout repair using TSS were assessed. Healing status was assessed by a semi-quantitative second-look arthroscopic scoring system comprising three evaluation criteria (width of bridging tissues, stability of the repaired root, and synovial coverage), 1 year postoperatively. MM medial extrusion (MMME) and cartilage damage were assessed preoperatively and 1 year postoperatively. The medial compartment was divided into 8 zones (A-H) for comparison of preoperative and 1-year postoperative cartilage damage. Clinical outcomes were evaluated using the Knee Injury and Osteoarthritis Outcome score, Lysholm score, International Knee Documentation Committee scores, and visual analogue scale pain score. RESULTS: Although cartilage damage did not aggravate significantly in most medial compartment areas, MMME progressed at 1 year postoperatively. No statistical differences were observed in cartilage damage between the central-to-medial area of the medial femoral condyle and the medial tibial plateau area at 1 year postoperatively. Regarding semi-quantitative healing scores, the stability score was significantly correlated with the International Cartilage Repair Society grade at 1 year postoperatively. All 1-year and 2-year clinical scores significantly improved compared with the preoperative scores. CONCLUSION: Regarding TSS repair, stability of repaired meniscal root negatively correlated with cartilage damage in the medial compartment loading area. All 1-year and 2-year clinical scores significantly improved than those of the preoperative scores. Achieving MM stability is crucial for suppressing cartilage degeneration. LEVEL OF EVIDENCE: IV case series study.

Effect of symbiotic N2 fixation on leaf protein contents, protein degradation and nitrogen resorption during leaf senescence in temperate deciduous woody species.

Nitrogen (N) resorption from senescing leaves enables plants to reuse N, making them less dependent on current N uptake from the environment, leading to higher fitness, particularly under low N supply. Species that form a symbiotic association with N2-fixing bacteria have not evolved proficient N resorption, i.e., they retain more N in the senesced leaves than non-N2-fixing species. However, the physiological mechanism underlying the difference is still unknown. Metabolic and structural protein contents in green and senesced leaves, as well as protein degradation during leaf senescence-a critical initial process for subsequent N resorption-were determined in four N2-fixing legumes and in four non-N2-fixers. The metabolic proteins were highly degraded in legumes and to a lesser extent in nonlegumes. Nonetheless, legumes retained more metabolic proteins in their senesced leaves than nonlegumes, because symbiotic N2 fixation improved the metabolic protein content in green leaves. Symbiotic N2 fixation did not change the structural protein content in green leaves. The structural proteins were moderately degraded in nonlegumes, and almost undegraded in legumes, and more structural proteins remained in the senesced leaves of legumes than in those of nonlegumes. The higher metabolic and structural protein contents in the senesced leaves of N2-fixing legumes properly explained the less proficient N resorption. This is an important step in unraveling molecular mechanisms of different N conservation strategies among plant functional types.

Clinical outcomes of medial meniscus posterior root repair: A midterm follow-up study.

BACKGROUND: Transtibial pullout repair of medial meniscus posterior root tears (MMPRTs) cannot prevent the progression of knee osteoarthritis. Conversions of knee arthroplasties are occasionally required following MMPRT repair. However, other knee-related surgical treatments following MMPRT repair are unclear. This study was aimed at investigating the midterm clinical outcomes and knee-related surgical events following MMPRT repair. METHODS: Patients with MMPRT underwent pullout repair using FasT-Fix modified Mason-Allen (F-MMA) suturing with an all-inside meniscal repair device. Thirty-two patients with follow-up duration >2 years were enrolled. We assessed the clinical outcomes and postoperative surgical treatment of both knees. RESULTS: F-MMA pullout repair improved all clinical evaluation scores in patients with MMPRT at a mean follow-up of 36.1 months. Postoperative arthroscopic debridement was required for one patient. An additional MMPRT repair was performed in one patient on second-look arthroscopy. None of the patients required ipsilateral knee arthroplasty. In the contralateral knees, one pullout repair of a newly developed MMPRT and two knee arthroplasties were performed. CONCLUSIONS: This study demonstrated that F-MMA pullout repair yielded satisfactory clinical outcomes. However, subsequent knee-related surgeries were observed in 6.3% of the pullout-repaired knees and 9.4% of the contralateral knees. Our results suggest that surgeons should be aware of the worsening and/or occurrence of contralateral knee joint disease, even when the postoperative clinical outcomes are satisfactory following MMPRT repair. LEVEL OF EVIDENCE: IV.

Video Evidence of Tissue Sliding Improvement by Ultrasound-Guided Hydrorelease on Scars After Arthroscopic Knee Surgery: A Case Report.

Postoperative scarring is a complication of arthroscopic knee surgery that causes a lack of terminal extension and tissue sliding defects. We present video evidence of tissue sliding before and after ultrasound-guided hydrorelease in a 53-year-old man. The patient presented with pain in the scarred area following arthroscopic knee surgery. His active and passive extension was -5° with restricted patellar mobility. Dynamic ultrasonography revealed scar tissue sliding defects. For ultrasound-guided hydrorelease, a needle (22G, 60 mm) was aimed at a site within 10 mm depth of the hypoechoic change in the scar area below the patella, and saline solution (10 mL) mixed with 1% lidocaine (10 mL) and 10 mg prednisolone was injected. Immediately after injection, the patient's extension was 0° with no pain or limitation of patellar mobility, and dynamic ultrasonography showed tissue sliding improved. Video evidence from dynamic ultrasonography clarifies the direction of the inadequate slide and the indication for and efficacy of ultrasound-guided hydrorelease. This case highlights the benefits of video evidence from dynamic ultrasonography before and after ultrasound-guided hydrorelease.

Increased cleft width during knee flexion is useful for the diagnosis of medial meniscus posterior root tears.

PURPOSE: This study aimed to evaluate changes in the cleft width, defined as the distance between the lateral edge of the medial tibial plateau and that of the medial meniscus (MM) posterior root, using open magnetic resonance imaging (MRI) in patients with MM posterior root tear (MMPRT). METHODS: This study included 25 patients (20 women and 5 men; mean age: 65.2 years) who were diagnosed with MMPRT and underwent pullout repair. Upon coronal imaging, the cleft width was evaluated at the 10° and 90° flexed knee positions. The difference in the cleft width (defined as the cleft width at 90° minus the cleft width at 10°) was also calculated. Upon sagittal imaging, the MM posterior extrusion (MMPE) at 90° was also evaluated. Separate univariate linear regression models were used to determine the association between the time from injury to MRI and radiographic measurements. RESULTS: The mean cleft width at 10° and 90° was 4.9 ± 2.6 mm and 7.4 ± 3.7 mm, respectively; the mean difference in cleft width was 2.5 ± 1.5 mm, and the mean MMPE at 90° was 3.7 ± 1.3 mm. There was a significant difference in cleft width at 10° and 90° (p < 0.001). The time from injury to MRI was significantly associated with the cleft width at 10° (R = 0.42; p = 0.023), cleft width at 90° (R = 0.59; p = 0.002), the difference in the cleft width (R = 0.62; p = 0.008), and MMPE at 90° (R = 0.53; p = 0.008). CONCLUSION: This study demonstrates that the cleft width is significantly larger during knee flexion than during knee extension. Increased cleft width during knee flexion ("graben" sign) may help diagnose MMPRT, especially in cases where the cleft sign is unclear during knee extension. LEVEL OF EVIDENCE: III.

Large flexion contracture angle predicts tight extension gap during navigational posterior stabilized-type total knee arthroplasty with the pre-cut technique: a retrospective study.

BACKGROUND: This study aimed to determine the predictors of tight extension gap (EG) compared with the flexion gap (FG) during navigational posterior stabilized-type total knee arthroplasty using the pre-cut technique. METHODS: Nineteen patients with tight EG (defined as FG-EG ≥2 mm after pre-cut; group T) and 84 patients with an approximately equal gap (defined as FG-EG = 0-1 mm after pre-cut; group E) were enrolled. Medial tibial slope angle, hip knee ankle angle, flexion contracture angle, and active maximum flexion angle were compared between the two groups. RESULTS: The multivariate logistic regression model indicated that the probability of tight EG increased with flexion contracture angle (odds ratio, 1.13; 95% confidence interval 1.05-1.20; P ≤ 0.001). According to the receiver operating characteristic analysis, the flexion contracture angle cut-off value associated with tight EG was 15.0° (sensitivity, 85%; specificity, 78%). CONCLUSION: This study demonstrated that a large flexion contracture angle (cut-off 15.0°) was associated with tight EG after pre-cut osteotomy during posterior stabilized-type total knee arthroplasty. Awareness of this risk factor may help improve preoperative predictability of tight EGs and preparedness for additional procedures, such as soft tissue release or capsulotomy, to correct them. LEVEL OF EVIDENCE: Level III.

Semi-quantitative arthroscopic scoring system is related to clinical outcomes in patients after medial meniscus posterior root repair.

BACKGROUND: Different methods are available to assess the healing status of repaired root for medial meniscus posterior root tears (MMPRT) using second-look arthroscopy. However, few studies are comparing them or validating their usefulness. Therefore, it was hypothesized that the semi-quantitative arthroscopic score might correlate more with 1-year clinical outcomes in patients with MMPRT than the qualitative evaluation. METHODS: Data of 61 patients who underwent MMPRT pullout repair and second-look arthroscopy were retrospectively evaluated. The semi-quantitative arthroscopic scoring system was divided into three evaluation criteria: scores from 0 to 10 points include the width of the bridging tissue, stability of the repaired root, and synovial coverage. The qualitative evaluation was classified into 4 status; complete healing, lax healing, scar tissue healing, and failed healing according to the stability and mobility of the repaired root. Multivariate linear regression analyses were used to identify predictors of 1-year postoperative clinical outcomes, including Knee Injury and Osteoarthritis Outcome, Lysholm, or International Knee Documentation Committee scores. Spearman's correlation analysis was used to analyze the correlation between second-look arthroscopic score/qualitative evaluation and 1-year postoperative clinical outcomes. In addition, the optimal cutoff point of semi-quantitative arthroscopic score was determined by receiver operating characteristic (ROC) curve. The Mann-Whitney U test was used to compare clinical outcomes between patients with semi-quantitative arthroscopic scores ≥8 and scores <8. RESULTS: All clinical scores significantly improved at 1 year postoperatively. A good correlation was observed between the semi-quantitative score and clinical scores, but none between qualitative evaluation and clinical scores. The optimal cutoff point of semi-quantitative second-look arthroscopic score was 8 points. Significantly, better clinical outcomes were observed in patients with semi-quantitative scores ≥8 points. CONCLUSIONS: All 1-year postoperative clinical scores were significantly improved. The semi-quantitative arthroscopic scores correlate more with 1-year clinical outcomes in patients with MMPRT than the qualitative evaluation. LEVEL OF EVIDENCE: IV case series study.

Transtibial pullout repair techniques using two simple stitches for medial meniscus posterior root tear can prevent the progression of medial meniscus extrusion and obtain successful outcomes.

PURPOSE: Transtibial pullout repairs using two simple stitches (TSS) and a combination of TSS with posteromedial pullout repair (TSS + PMP) using an all-inside meniscal repair device have been reported previously for the treatment of medial meniscus (MM) posterior root tears. This study aimed to investigate the postoperative clinical outcomes of these techniques including MM extrusion (MME). METHODS: Fifty-two patients who underwent transtibial pullout repair were investigated and divided into TSS (n = 27) and TSS + PMP (n = 25) groups. The clinical outcomes were assessed using the Lysholm knee score and Knee Injury and Osteoarthritis Outcome Score 1 year postoperatively and compared between two groups. MME was measured using magnetic resonance imaging at 1 year postoperatively and compared between two groups. RESULTS: A significant improvement in each clinical score was observed in both groups, and no significant difference was seen in clinical outcomes. Moreover, no significant difference in postoperative MME was observed in both groups (TSS and TSS + PMP: 3.5 mm and 3.8 mm, respectively). Though no significant progression of MME was observed in TSS group, a significant progression of it was observed in TSS + PMP group postoperatively. CONCLUSIONS: This study demonstrated that both techniques improved clinical outcomes in the short-term postoperative period. However, MME was progressed significantly in TSS + PMP group 1 year postoperatively, which indicated that PMP might not be a useful additional procedure for reducing the postoperative MME.

Comparison of posterior root remnant cells and horn cells of the medial meniscus.

PURPOSE/AIM OF THE STUDY: Previous studies have noted distinctions between medial meniscus posterior root and horn cells. However, the characteristics of root remnant cells have not been explored in detail. The purpose of this study was to evaluate the gene expression levels, proliferation, and resistance to mechanical stress of remnant and horn cells. MATERIALS AND METHODS: Medial meniscus tissue samples were obtained from patients who underwent total or uni-compartmental knee arthroplasty. Cellular morphology, sry-type HMG box 9, type II collagen, and chondromodulin-I gene expression levels were analyzed. Collagen synthesis was assessed by immunofluorescence staining. Proliferation analysis after 4 h-cyclic tensile strain was performed. RESULTS: Horn cells displayed triangular morphology, whereas root remnant cells appeared fibroblast-like. sry-type HMG box 9 mRNA expression levels were similar in both cells, but type II collagen and chondromodulin-I mRNA expressions were observed only in horn cells. The ratio of type II collagen-positive cells in horn cells was about 10-fold higher than that in root remnant cells, whereas the ratio of sry-type HMG box 9-positive cells was similar. A significant increase in proliferation was observed in root remnant cells compared to that in horn cells. Further, under cyclic tensile strain, the survival rate was higher in root remnant cells than in horn cells. CONCLUSIONS: Medial meniscus root remnant cells showed higher proliferation and resistant properties to cyclic tensile strain than horn cells and showed no chondromodulin-I expression. Preserving the medial meniscus posterior root remnant during pullout repair surgery might maintain mechanical stress-resistant tissue and support healing.

Medial Meniscus Posterior Root Repair Using a Modified Mason-Allen Suture Can Prevent the Progression of Cartilage Degeneration on the Loading Surface of the Medial Compartment: A Second-Look Arthroscopic Evaluation.

The treatment of medial meniscus posterior root tears (MMPRTs) has evolved to include a variety of repair strategies. This study investigated the location of the articular cartilage degeneration during second-look arthroscopy after transtibial pullout repair with a modified Mason-Allen suture using FasT-Fix (F-MMA) in 22 patients with MMPRTs. Second-look arthroscopy was performed approximately 1 year postoperatively to eval-uate the healing status of the medial meniscus (MM). Articular cartilage degeneration was assessed using the International Cartilage Repair Society grade at primary surgery and again at second-look arthroscopy. Articular surfaces of the medial/lateral femoral condyles, the medial/lateral tibial plateaus, the patella and the trochlea were divided into several subcompartments (MF 1-9, LF 1-9, MT 1-5, LT 1-5, P 1-9, T 1-3). Clinical evaluations used the Japanese Knee Injury and Osteoarthritis Outcome, Lysholm, and International Knee Documentation Committee scores. Second-look arthroscopic findings showed complete healing of the MM posterior root in all patients. Significant differences between pullout repair and second-look arthroscopy were observed for MF 2 and 4, LF 7, and P 7. All clinical outcomes were improved. Our results indicate that this technique improves clinical outcomes postoperatively and may prevent the progression of cartilage degenera-tion on the loading surface of the medial knee compartment.

Histologic Evaluation of Tibial Attachment in 11-Year Double-Bundle ACL Reconstruction with Hamstring Tendons: A Case Report.

CASE: A 49-year-old woman injured her anterior cruciate ligament (ACL) as a high-school student. Double-bundle ACL reconstruction (DBACLR) using hamstring tendon grafts was performed because of recurrent instability. Eleven years after DBACLR, total knee arthroplasty was performed because of osteoarthritis progression. Histologic analysis was completed to observe the osteointegration of the tendon in the obtained proximal tibia. The tibial tunnel showed Sharpey-like fibers anteriorly, connecting the tendon graft and lamellar bone, whereas the intraarticular exit revealed well-aligned chondrocytes posteriorly, indicating chondral metaplasia of the tendon graft. CONCLUSION: Tendon-bone healing can regenerate both fibrous insertion and chondral metaplasia in DBACLR.

Somatic Embryogenesis Initiation in Sugi (Japanese Cedar, Cryptomeria japonica D. Don): Responses from Male-Fertile, Male-Sterile, and Polycross-Pollinated-Derived Seed Explants.

This study aimed to obtain information from several embryogenic cell (EC) genotypes analyzing the factors that affect somatic embryogenesis (SE) initiation in sugi (Cryptomeria japonica, Cupressaceae) to apply them in the improvement of protocols for efficient induction of embryogenic cell lines (ECLs). The results of several years of experiments including studies on the influence of initial explant, seed collection time, and explant genotype as the main factors affecting SE initiation from male-fertile, male-sterile, and polycross-pollinated-derived seeds are described. Initiation frequencies depending on the plant genotype varied from 1.35 to 57.06%. The best induction efficiency was achieved when seeds were collected on mid-July using the entire megagametophyte as initial explants. The extrusion of ECs started approximately after 2 weeks of culture, and the establishment of ECLs was observed mostly 4 weeks after extrusion on media with or without plant growth regulators (PGRs). Subsequently, induced ECLs were maintained and proliferated on media with PGRs by 2-3-week-interval subculture routines. Although, the initial explant, collection time, and culture condition played important roles in ECL induction, the genotype of the plant material of sugi was the most influential factor in SE initiation.

Placement of an anatomic tibial tunnel significantly improves the medial meniscus posterior extrusion at 90° of knee flexion following medial meniscus posterior root pullout repair.

PURPOSE: The purpose of this study was to evaluate the influence of tibial tunnel position in pullout repair for a medial meniscus (MM) posterior root tear (MMPRT) on postoperative MM extrusion. METHODS: Thirty patients (median age 63 years, range 35-72 years) who underwent transtibial pullout repairs for MMPRTs were included. Three-dimensional computed tomography images of the tibial surface were evaluated using a rectangular measurement grid for assessment of tibial tunnel position and MM posterior root attachment. Preoperative and postoperative MM medial extrusion (MMME) and posterior extrusion (MMPE) at 10° and 90° knee flexion were measured using open magnetic resonance imaging. RESULTS: Tibial tunnel centers were located more anteriorly and more medially than the anatomic center (median distance 5.8 mm, range 0-9.3 mm). The postoperative MMPE at 90° knee flexion was significantly reduced after pullout repair, although there was no significant reduction in MMME or MMPE at 10° knee flexion after surgery. In the correlation analysis of the displacement between the anatomic center to the tibial tunnel center and improvements in MMME, and MMPE at 10° and 90° knee flexion, there was a significant positive correlation between percentage distance and improvement of MMPE at 90° knee flexion. CONCLUSION: This study demonstrated that the nearer the tibial tunnel position to the anatomic attachment of the MM posterior root, the more effective the reduction in MMPE at 90° knee flexion. Our results emphasize that an anatomic tibial tunnel should be created in the MM posterior root to improve the postoperative MMPE and protect the articular cartilage in a knee flexion position. Placement of an anatomic tibial tunnel significantly improves the MMPE at 90° of knee flexion after MM posterior root pullout repair. LEVEL OF EVIDENCE: IV.

Transtibial pullout repair of medial meniscus posterior root tears: effects on the meniscus healing score and ICRS grade among patients with mild osteoarthritis of the knee.

PURPOSE: To assess the effects of transtibial pullout repair for medial meniscus posterior root tears (MMPRTs) among patients with early osteoarthritis of the knee as measured by the meniscus healing score and to determine whether the meniscus healing score correlates with the International Cartilage Repair Society (ICRS) grade progression. METHODS: Forty-seven patients with mild osteoarthritic knees (Kellgren-Lawrence grade ≤ 2 and varus alignment < 5°) who underwent transtibial pullout repair less than 3 months after MMPRT onset were assessed. The association between meniscus healing scores at 1 year postoperatively and cartilage damage of the medial compartment (medial femoral condyle [MFC] and medial tibial plateau [MTP]) were evaluated. The MFC was divided into six zones (A to F) and the MTP into two zones (G and H). The mean ICRS grade for each zone was compared between the primary surgery and second-look arthroscopy. The correlation between cartilage damage and meniscus healing status at the time of second-look arthroscopy in each zone was analysed. RESULTS: The mean time interval from injury to surgery was 63 days, and all clinical scores showed significant improvement. There were no significant differences in the extent of cartilage damage in areas B, C, E, or F (n.s.) for MFC or in areas G and H (n.s.) for MTP. The meniscus healing score and cartilage damage were correlated in the loading areas (B, C, E, and H; - 0.53, - 0.45, - 0.33, and - 0.38, respectively; p < 0.05). CONCLUSION: Transtibial pullout repair of MMPRTs among patients with mild osteoarthritic knees improved the clinical outcomes and showed a negative correlation between high meniscus healing scores and ICRS grades in the medial compartment loading area. This study suggests that early surgery should be undertaken for patients with mild osteoarthritic knee who develop MMPRTs. LEVEL OF EVIDENCE: Level IV.

Dehydroquinate dehydratase/shikimate dehydrogenases involved in gallate biosynthesis of the aluminum-tolerant tree species Eucalyptus camaldulensis.

MAIN CONCLUSION: Eucalyptus camaldulensis EcDQD/SDH2 and 3 combine gallate formation, dehydroquinate dehydratase, and shikimate dehydrogenase activities. They are candidates for providing the essential gallate for the biosynthesis of the aluminum-detoxifying metabolite oenothein B. The tree species Eucalyptus camaldulensis shows exceptionally high tolerance against aluminum, a widespread toxic metal in acidic soils. In the roots of E. camaldulensis, aluminum is detoxified via the complexation with oenothein B, a hydrolyzable tannin. In our approach to elucidate the biosynthesis of oenothein B, we here report on the identification of E. camaldulensis enzymes that catalyze the formation of gallate, which is the phenolic constituent of hydrolyzable tannins. By systematical screening of E. camaldulensis dehydroquinate dehydratase/shikimate dehydrogenases (EcDQD/SDHs), we found two enzymes, EcDQD/SDH2 and 3, catalyzing the NADP+-dependent oxidation of 3-dehydroshikimate to produce gallate. Based on extensive in vitro assays using recombinant EcDQD/SDH2 and 3 enzymes, we present for the first time a detailed characterization of the enzymatic gallate formation activity, including the cofactor preferences, pH optima, and kinetic constants. Sequence analyses and structure modeling suggest the gallate formation activity of EcDQD/SDHs is based on the reorientation of 3-dehydroshikimate in the catalytic center, which facilitates the proton abstraction from the C5 position. Additionally, EcDQD/SDH2 and 3 maintain DQD and SDH activities, resulting in a 3-dehydroshikimate supply for gallate formation. In E. camaldulensis, EcDQD/SDH2 and 3 are co-expressed with UGT84A25a/b and UGT84A26a/b involved in hydrolyzable tannin biosynthesis. We further identified EcDQD/SDH1 as a "classical" bifunctional plant shikimate pathway enzyme and EcDQD/SDH4a/b as functional quinate dehydrogenases of the NAD+/NADH-dependent clade. Our data indicate that in E. camaldulensis the enzymes EcDQD/SDH2 and 3 provide the essential gallate for the biosynthesis of the aluminum-detoxifying metabolite oenothein B.

Diagnostic performance of open MRI in the flexed knee position for the detection of medial meniscus ramp lesions.

OBJECTIVES: To identify the diagnostic performance of magnetic resonance imaging (MRI) in the knee-flexed position for the detection of meniscal ramp lesions in patients with anterior cruciate ligament tears. MATERIALS AND METHODS: Forty-three patients (mean age 24.5 ± 9.5 years; 21 males, 22 females) with an arthroscopically proven anterior cruciate ligament tear were included in this retrospective study. The presence of the following two important features on MRI was recorded: irregularity of the medial meniscus at the posterior margin, and complete fluid filling between the posterior horn of the medial meniscus and the capsule margin. Findings obtained in arthroscopy served as the reference standard. The diagnostic sensitivity, specificity, and inter-observer agreement were calculated. RESULTS: Sixteen ramp lesions were noted on arthroscopy (37.2%). With an irregularity of the medial meniscus at the posterior margin on MRI, the sensitivity and specificity were 87.5 and 59.3% at 10° knee flexion and 93.8 and 85.2% at 90° flexion, respectively. The complete fluid filling sign on MRI showed sensitivity and specificity of 31.3 and 100% at 10° knee flexion and 87.5 and 100% at 90° flexion, respectively. The concordance between the two observers for the two MRI features was very good (k = 0.70-0.88). CONCLUSION: MRI with the knee in the flexed position improves the diagnostic performance of the detection of meniscal ramp lesions compared with MRI with the knee in the extended position.