Pith-specific lignification in Nicotiana attenuata as a defense against a stem-boring herbivore.

Plants have developed tissue-specific defense strategies in response to various herbivores with different feeding habits. Although defense responses to leaf-chewing insects have been well studied, little is known about stem-specific responses, particularly in the pith, to stem-boring herbivores. To understand the stem-specific defense, we first conducted a comparative transcriptomic analysis of the wild tobacco Nicotiana attenuata before and after attack by the leaf-chewing herbivore Manduca sexta and the stem borer Trichobaris mucorea. When the stem-boring herbivore attacked, lignin-associated genes were upregulated specifically in the inner parenchymal cells of the stem, the pith; lignin also accumulated highly in the attacked pith. Silencing the lignin biosynthetic gene cinnamyl alcohol dehydrogenase enhanced the performance of the stem-boring herbivore but had no effect on the growth of the leaf-chewing herbivore. Two-dimensional nuclear magnetic resonance results revealed that lignified pith contains feruloyltyramine as an unusual lignin component in the cell wall, as a response against stem-boring herbivore attack. Pith-specific lignification induced by the stem-boring herbivore was modulated by both jasmonate and ethylene signaling. These results suggest that lignin provides a stem-specific inducible barrier, protecting plants against stem-boring insects.

Long-term Survival Analysis of Meniscus Allograft Transplantation With Bone Fixation.

PURPOSE: To investigate the long-term clinical results and clinical survival rate of meniscus allograft transplantation (MAT) with bone fixation. METHODS: The inclusion criteria of this study were previous MAT with bone fixation technique in our institution and minimum follow-up duration of 8 years. Potential subjects were identified using the medical records and database that was prospectively collected from December 1996 to December 2005. The exclusion criteria were diffuse International Cartilage Repair Society grade IV articular cartilage degeneration that was not treated with a concomitant or staged cartilage repair procedure. Surgical indication for MAT was previous total or subtotal meniscectomy followed by persistent swelling and pain in involved compartment. Recommendations to return to contact sports or strenuous activities were not made. Clinical outcomes were evaluated using the modified Lysholm score, and comparison between preoperative and final Lysholm score was done using Student t-test. During the follow-up period, failure was defined as (1) subtotal resection of the allograft, (2) conversion to total knee arthroplasty, or (3) a modified Lysholm score less than 65 or that of the preoperative status. Survival analysis was performed using the Kaplan-Meier method. RESULTS: During the study period, 52 knees underwent MAT in our institution and 49 knees were eligible for this study. Three knees were excluded because they had diffuse grade IV cartilage degeneration in the respective compartment. Among the 49 knees enrolled, 34 underwent lateral and 15 underwent medial MAT. Two patients had bilateral lateral MAT. Of those 47 patients, 37 were male and 10 were female. Mean patient age at the time of the MAT was 30.4 ± 8.6 years. The median follow-up period was 11.5 years (8 to 17 years). The preoperative mean modified Lysholm score was 73.2 ± 10.6, which significantly increased to 89.4 ± 13.2 at the time of the final follow-up (P < .001). There were 2 failures noted at 6 months and 11.3 years, respectively, after MAT. All of the other allografts were surviving at the time of the latest follow-up. The 10-year survival rate was 98.0% (95% confidence interval [CI], 94.1%-100%), and the 15-year survival rate was 93.3% (95% CI, 83.7%-100%) according to the Kaplan-Meier analysis. CONCLUSIONS: MAT using the bone fixation techniques demonstrated a high clinical survival rate according to the long-term observation. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Survivorship After Meniscal Allograft Transplantation According to Articular Cartilage Status.

BACKGROUND: Clinical outcomes after meniscal allograft transplantation (MAT) in arthritic knees are unclear, and objective estimates of graft survival according to the articular cartilage status have not been performed. HYPOTHESIS: MAT should provide clinical benefits in knees with high-grade cartilage damage, but their graft survivorship should be inferior to that in knees with low-grade chondral degeneration after MAT. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: The records of 222 consecutive patients who underwent primary MAT were reviewed to compare clinical outcomes and graft survivorship. The patients were grouped according to the degree and location of articular cartilage degeneration: low-grade chondral lesions (International Cartilage Repair Society [ICRS] grade ≤2) on both the femoral and tibial sides (ideal indication), high-grade lesions (ICRS grade 3 or 4) on either the femoral or tibial side (relative indication), and high-grade lesions on both sides (salvage indication). Kaplan-Meier survival analysis with the log-rank test was performed to compare the clinical survival rates and graft survival rates between the groups. A Lysholm score of <65 was considered a clinical failure, and graft failure was defined as a meniscal tear or meniscectomy of greater than one-third of the allograft, objectively evaluated by magnetic resonance imaging (MRI) and second-look arthroscopic surgery. RESULTS: The mean (±SD) Lysholm score significantly improved from 63.1 ± 15.1 preoperatively to 85.1 ± 14.3 at the latest follow-up of a mean 44.6 ± 19.7 months ( P < .001). However, the postoperative scores were not significantly different between the 3 groups (85.7 ± 14.2 for ideal indication, 84.7 ± 17.0 for relative indication, and 84.7 ± 14.2 for salvage indication; P = .877). On MRI at the latest follow-up of a mean 23.0 ± 19.9 months and second-look arthroscopic surgery of a mean 19.3 ± 20.7 months, there were 25 (11.3%) failed MAT procedures (4 medial, 21 lateral); of these, 5 lateral MAT procedures (2.3%) went on to allograft removal. Clinical survival rates were not significantly different between the groups ( P = .256). However, on objective evaluation, the estimated cumulative graft survival rate at 5 years in the salvage indication group (62.2% [95% CI, 41.6-82.8]) was significantly lower than that in the other 2 groups (ideal indication: 93.8% [95% CI, 88.5-99.1]; relative indication: 90.9% [95% CI, 81.1-100.0]) ( P = .006). CONCLUSION: Our findings showed that MAT was an effective symptomatic treatment in knees with advanced bipolar chondral lesions. However, better graft survival can be expected when articular cartilage is intact or if chondral damage is limited to a unipolar lesion. MAT should be considered before the progression of chondral damage to a bipolar lesion for better graft survivorship and should be performed cautiously in arthritic knees.