Biomechanical and histological evaluation of aspirin in rotator cuff tear rat model.

Background: Aspirin is a representative non-steroidal anti-inflammatory drug (NSAIDs) and has been commonly used for the treatment of tendinopathy in clinical practice. In this study, we aimed to evaluate the biomechanical and histological healing effects of aspirin on the healing of the tendon-to-bone interface after rotator cuff tear repair. Methods: A total of 20 male Sprague-Dawley rats were randomly divided into two groups of 10 rats each. Group-C performed repaironly, and group-aspirin treated with aspirin after tendon repair. Group-aspirin rat were intraperitoneally injected with aspirin at 10 mg/kg every 24 h for 7 days. Eight weeks after surgery, the left shoulder of each rat was used for histological analysis and the right shoulder for biomechanical analysis. Results: In the biomechanical analysis, there was no significant difference in load-to-failure (group-C: 0.61 ± 0.32 N, group-aspirin: 0.74 ± 0.91 N; p = .697) and ultimate stress (group-C: 0.05 ± 0.01 MPa, group-aspirin: 0.29 ± 0.43 MPa; p = .095). For the elongation (group-C: 222.62 ± 57.98%, group-aspirin: 194.75 ± 75.16%; p = .028), group-aspirin confirmed a lower elongation level than group-C. In the histological evaluation, the Bonar score confirmed significant differences in collagen fiber density (group-C: 1.60 ± 0.52, group-aspirin: 2.60 ± 0.52, p = .001) and vascularity (group-C: 1.00 ± 0.47, group-aspirin: 2.20 ± 0.63, p = .001) between the groups. Conclusions: Aspirin injection after rotator cuff tear repair may enhance the healing effect during the early remodeling phase of tendon healing.

Effect of Gabapentin on Tendon-to-Bone Healing in a Rat Model of Rotator Cuff Repair.

BACKGROUND: Gabapentin is often used as an analgesic after rotator cuff repair surgery and is recommended as an additional analgesic for arthroscopic rotator cuff repairs. However, evidence of its effects on biological healing mechanisms is lacking. The objective of this study was to investigate the potential of gabapentin in improving tendon-to-bone healing after rotator cuff repair using a rat model. MATERIALS AND METHODS: A total of 20 male rats were randomly allocated to one of two groups: group 1 (repair only, n=10) or group 2 (gabapentin injection, n=10). The rats in the experimental group (group 2) were administered 80 mg/kg of gabapentin subcutaneously 30 minutes before surgery, followed by 80 mg/kg subcutaneously every 24 hours for 48 hours. We used the left shoulder of every rat, while for biomechanical analysis, we used the right shoulder. RESULTS: There was no significant difference in the load to failure, ultimate stress, or elongation between the groups. Collagen continuity, orientation, and density were better in group 2 than group 1. CONCLUSION: In a rat model of rotator cuff repair, gabapentin had a positive impact on the quality of collagen organization at the junction between the tendon and bone, while preserving the biomechanical properties. We propose the use of gabapentin as a supplementary analgesic agent for postoperative pain relief after arthroscopic rotator cuff repair; however, further studies of the effect of gabapentin on biological healing mechanisms are required. [Orthopedics. 2024;47(5):e241-e246.].

Tranexamic Acid Can Reduce Early Tendon Adhesions After Rotator Cuff Repair and Is Not Detrimental to Tendon-Bone Healing: A Comparative Animal Model Study.

PURPOSE: To determine the effects of topical tranexamic acid (TXA) administration on tendon adhesions, shoulder range of motion (ROM), and tendon healing in an acute rotator cuff repair rat model. METHODS: A total of 20 Sprague Dawley rats were used. Tendon adhesion, ROM, and biomechanical and histological analysis of tendon-bone healing was conducted at 3 and 6 weeks after surgery. The rats underwent rotator cuff repair surgery on both shoulders and were administered TXA via subacromial injections. The tendon adhesion was evaluated macroscopically and histologically. Biomechanical tendon healing was measured using a universal testing machine, and histological analysis was quantified by H&E, Masson's trichrome, and picrosirius red staining. RESULTS: At 3 weeks after surgery, the adhesion score was significantly lower in the TXA group (2.10 ± 0.32) than in the control group (2.70 ± 0.48) (P = .005), but there was no significant difference between the 2 groups at 6 weeks. Regarding ROM, compared with the control group, the TXA group showed significantly higher external rotation (36.35° ± 4.52° vs 28.42° ± 4.66°, P < .001) and internal rotation (45.35° ± 9.36° vs 38.94° ± 5.23°, P = .013) 3 weeks after surgery. However, at 6 weeks, there were no significant differences in external and internal rotation between the 2 groups. In the biomechanical analysis, no significant differences in gross examination (3 weeks, P = .175, 6 weeks, P = .295), load to failure (3 weeks, P = .117, 6 weeks, P = .295), or ultimate stress (3 weeks, P = .602, 6 weeks, P = .917) were noted between the 2 groups 3 and 6 weeks after surgery. In the histological analysis of tendon healing, no significant differences in the total score (3 weeks, P = .323, 6 weeks, P = .572) were found between the 2 groups 3 and 6 weeks after surgery. CONCLUSIONS: Topical TXA administration showed a beneficial effect in reducing tendon adhesions and improving ROM 3 weeks postoperatively and had no effect at 6 weeks. This suggests that additional intervention with TXA may be useful in achieving long-term improvement in shoulder stiffness. Additionally, TXA may increase tissue ground substance accumulation in the late postoperative period but does not adversely affect tendon-bone interface healing. CLINICAL RELEVANCE: The use of TXA after rotator cuff repair has no effect on tendon-bone interface healing in clinical practice and can improve shoulder stiffness in the early postoperative period. Additional research on the long-term effects is needed.

Mid-term to Long-term Follow-up Results of Reconstruction for Thumb Radial Polydactyly.

BACKGROUND: Preaxial or radial polydactyly is one of the most common hand congenital anomalies in newborns. Contemporary reconstruction methods include ligament reconstruction, excision of the polydactylous thumb, osteotomy, and other surgical techniques according to the type of polydactyly. The purpose of this study was to report mid-term to long-term reconstruction results for thumb (radial) polydactyly. METHODS: We retrospectively reviewed the medical records of patients who underwent reconstruction surgery for preaxial polydactyly. Clinical outcomes, including the range of motion (ROM), pain, and complications, were evaluated. We assessed the final radiographs of the reconstructed thumb to identify the potential development of arthritis or other remaining deformities. After excluding cases without a simple radiograph and cases with a short follow-up period of fewer than 5 years, 26 thumbs were included. The surgical technique followed including excision of polydactylout thumb was tailored to the type of polydactyly. If the nail size of the thumbs was similar, the Bilhaut-Cloquet method was preferred. RESULTS: The mean age of the patients at the surgery and final follow-up was 14.9 months (range: 8 to 30 mo) and 11.9 years (range: 5.8 to 19.3 y), respectively. The mean follow-up was 128.8 months years (range: 60 to 219 mo), and the mean ROM of the thumb was 32.7 and 57.5 degrees in the distal interphalangeal joint (DIP) and metacarpophalangeal (MP) joint, respectively. Ulnar or radial side instability was prominent in 7 patients in the involved joints (26.9%). One patient underwent interphalangeal (IP) fusion for extension lag with pain. The radiologic evaluation revealed that 2 patients developed radiographic evidence of IP joint arthritis (7.7%). Radial deviation of the MP or IP joint existed in 13 cases (range: 5 to 40 degrees) (50.0%), and ulnar deviation of the MP or IP joint existed in 2 cases (range: 19 to 20 degrees) (7.7%). CONCLUSIONS: In mid-term to long-term experience, sequelae such as joint instability, joint stiffness, and remaining deformity cannot be neglected. An unstable MP joint may result if the DIP joint remains stiff or has a lower ROM. LEVEL OF EVIDENCE: Level IV-therapeutic studies.

The importance of reconstruction nailing for diaphyseal atypical femoral fractures: a comparative study with standard nailing.

INTRODUCTION: Subtrochanteric atypical femoral fractures (AFFs) usually require long cephalomedullary or reconstruction nailing to achieve satisfactory healing. Recently, this type of nailing has also been recommended to fix diaphyseal AFFs and prevent fragility fractures around the proximal femur, although standard antegrade nailing seems sufficient from a biomechanical perspective. This study aimed to compare treatment outcomes and complications between reconstruction and standard nailing for diaphyseal AFFs. MATERIALS AND METHODS: A retrospective comparative study of 48 female patients with diaphyseal AFFs who underwent surgical treatment with either reconstruction or standard nailing was conducted. The reconstruction nailing group comprised 23 patients with a mean age of 74.4 years and included 16 complete and 7 incomplete AFFs. The mean follow-up period was 30 months. The standard nailing group comprised 25 patients with a mean age of 71.1 years and included 16 complete and 9 incomplete AFFs. The mean follow-up period was 57.8 months. The healing rate, time to union, and complications were analyzed and compared between the two groups. RESULTS: Bony union was achieved in all 23 cases (100%) of the reconstruction nailing group by a mean of 19.3 weeks postoperative. In the standard nailing group, 23 of 25 cases healed (92%) by a mean of 16 weeks postoperative. The standard nailing group included two delayed fragility fractures of the femoral neck (5 and 10 years after the initial surgery), four cases of newly developed subtrochanteric AFFs at the distal screw of the proximal interlocking screws of the nail (one complete and three incomplete fractures), and two cases of nonunion. Complications only occurred in the standard nailing group (p = 0.01, Fisher's exact test). CONCLUSIONS: In diaphyseal AFFs, reconstruction nailing may achieve a satisfactory outcome and can also decrease delayed peri-implant fragility fractures of the hip, newly developed subtrochanteric AFFs, and nonunion.

Acylsugars protect Nicotiana benthamiana against insect herbivory and desiccation.

KEY MESSAGE: Nicotiana benthamiana acylsugar acyltransferase (ASAT) is required for protection against desiccation and insect herbivory. Knockout mutations provide a new resource for investigation of plant-aphid and plant-whitefly interactions. Nicotiana benthamiana is used extensively as a transient expression platform for functional analysis of genes from other species. Acylsugars, which are produced in the trichomes, are a hypothesized cause of the relatively high insect resistance that is observed in N. benthamiana. We characterized the N. benthamiana acylsugar profile, bioinformatically identified two acylsugar acyltransferase genes, ASAT1 and ASAT2, and used CRISPR/Cas9 mutagenesis to produce acylsugar-deficient plants for investigation of insect resistance and foliar water loss. Whereas asat1 mutations reduced accumulation, asat2 mutations caused almost complete depletion of foliar acylsucroses. Three hemipteran and three lepidopteran herbivores survived, gained weight, and/or reproduced significantly better on asat2 mutants than on wildtype N. benthamiana. Both asat1 and asat2 mutations reduced the water content and increased leaf temperature. Our results demonstrate the specific function of two ASAT proteins in N. benthamiana acylsugar biosynthesis, insect resistance, and desiccation tolerance. The improved growth of aphids and whiteflies on asat2 mutants will facilitate the use of N. benthamiana as a transient expression platform for the functional analysis of insect effectors and resistance genes from other plant species. Similarly, the absence of acylsugars in asat2 mutants will enable analysis of acylsugar biosynthesis genes from other Solanaceae by transient expression.

Herbivore Oral Secreted Bacteria Trigger Distinct Defense Responses in Preferred and Non-Preferred Host Plants.

Insect symbiotic bacteria affect host physiology and mediate plant-insect interactions, yet there are few clear examples of symbiotic bacteria regulating defense responses in different host plants. We hypothesized that plants would induce distinct defense responses to herbivore- associated bacteria. We evaluated whether preferred hosts (horsenettle) or non-preferred hosts (tomato) respond similarly to oral secretions (OS) from the false potato beetle (FPB, Leptinotarsa juncta), and whether the induced defense triggered by OS was due to the presence of symbiotic bacteria in OS. Both horsenettle and tomato damaged by antibiotic (AB) treated larvae showed higher polyphenol oxidase (PPO) activity than those damaged by non-AB treated larvae. In addition, application of OS from AB treated larvae induced higher PPO activity compared with OS from non-AB treated larvae or water treatment. False potato beetles harbor bacteria that may provide abundant cues that can be recognized by plants and thus mediate corresponding defense responses. Among all tested bacterial isolates, the genera Pantoea, Acinetobacter, Enterobacter, and Serratia were found to suppress PPO activity in tomato, while only Pantoea sp. among these four isolates was observed to suppress PPO activity in horsenettle. The distinct PPO suppression caused by symbiotic bacteria in different plants was similar to the pattern of induced defense-related gene expression. Pantoea inoculated FPB suppressed JA-responsive genes and triggered a SA-responsive gene in both tomato and horsenettle. However, Enterobacter inoculated FPB eliminated JA-regulated gene expression and elevated SA-regulated gene expression in tomato, but did not show evident effects on the expression levels of horsenettle defense-related genes. These results indicate that suppression of plant defenses by the bacteria found in the oral secretions of herbivores may be a more widespread phenomenon than previously indicated.

Herbivore exploits orally secreted bacteria to suppress plant defenses.

Induced plant defenses in response to herbivore attack are modulated by cross-talk between jasmonic acid (JA)- and salicylic acid (SA)-signaling pathways. Oral secretions from some insect herbivores contain effectors that overcome these antiherbivore defenses. Herbivores possess diverse microbes in their digestive systems and these microbial symbionts can modify plant-insect interactions; however, the specific role of herbivore-associated microbes in manipulating plant defenses remains unclear. Here, we demonstrate that Colorado potato beetle (Leptinotarsa decemlineata) larvae exploit bacteria in their oral secretions to suppress antiherbivore defenses in tomato (Solanum lycopersicum). We found that antibiotic-untreated larvae decreased production of JA and JA-responsive antiherbivore defenses, but increased SA accumulation and SA-responsive gene expression. Beetles benefit from down-regulating plant defenses by exhibiting enhanced larval growth. In SA-deficient plants, suppression was not observed, indicating that suppression of JA-regulated defenses depends on the SA-signaling pathway. Applying bacteria isolated from larval oral secretions to wounded plants confirmed that three microbial symbionts belonging to the genera Stenotrophomonas, Pseudomonas, and Enterobacter are responsible for defense suppression. Additionally, reinoculation of these bacteria to antibiotic-treated larvae restored their ability to suppress defenses. Flagellin isolated from Pseudomonas sp. was associated with defense suppression. Our findings show that the herbivore exploits symbiotic bacteria as a decoy to deceive plants into incorrectly perceiving the threat as microbial. By interfering with the normal perception of herbivory, beetles can evade antiherbivore defenses of its host.

Role of trichomes in defense against herbivores: comparison of herbivore response to woolly and hairless trichome mutants in tomato (Solanum lycopersicum).

Trichomes contribute to plant resistance against herbivory by physical and chemical deterrents. To better understand their role in plant defense, we systemically studied trichome morphology, chemical composition and the response of the insect herbivores Helicoverpa zea and Leptinotarsa decemlineata (Colorado potato beetle = CPB) on the tomato hairless (hl), hairy (woolly) mutants and wild-type Rutgers (RU) and Alisa Craig (AC) plants. Hairless mutants showed reduced number of twisted glandular trichomes (types I, IV, VI and VII) on leaf and stem compared to wild-type Rutgers (RU), while woolly mutants showed high density of non-glandular trichomes (types II, III and V) but only on the leaf. In both mutants, trichome numbers were increased by methyl jasmonate (MeJA), but the types of trichomes present were not affected by MeJA treatment. Glandular trichomes contained high levels of monoterpenes and sesquiterpenes. A similar pattern of transcript accumulation was observed for monoterpene MTS1 (=TPS5) and sesquiterpene synthase SST1 (=TPS9) genes in trichomes. While high density of non-glandular trichome on leaves negatively influenced CPB feeding behavior and growth, it stimulated H. zea growth. High glandular trichome density impaired H. zea growth, but had no effect on CPB. Quantitative real-time polymerase chain reaction (qRT-PCR) showed that glandular trichomes highly express protein inhibitors (PIN2), polyphenol oxidase (PPOF) and hydroperoxide lyase (HPL) when compared to non-glandular trichomes. The SlCycB2 gene, which participates in woolly trichome formation, was highly expressed in the woolly mutant trichomes. PIN2 in trichomes was highly induced by insect feeding in both mutant and wild-type plants. Thus, both the densities of trichomes and the chemical defenses residing in the trichomes are inducible.

Specificity of induced resistance in tomato against specialist lepidopteran and coleopteran species.

When challenged by herbivorous insects, plants produce a suite of antinutritive proteins that disrupt digestion and absorption of essential nutrients by the insects. We hypothesized that plants would induce distinct defense responses corresponding to the distinct midgut conditions of different herbivores. We investigated whether or not tomato responds specifically to two specialist herbivores: Colorado potato beetle (CPB; Leptinotarsa decemlineata; Coleoptera: Chrysomelidae) and tobacco hornworm (THW; Manduca sexta; Lepidoptera: Sphingidae), and we evaluated whether the induced defenses triggered by either species affect CPB growth. Tomato did not induce different defense genes in response to CPB or THW but accumulated more transcripts for some defense genes after damage by THW feeding compared to damage by CPB feeding. In addition, trypsin protease inhibitor activity and polyphenol oxidase activity were higher in plants damaged by THW than in plants damaged by CPB. Application of oral secretions from THW to wounded tomato plants increased transcripts compared to controls, but oral secretions from CPB decreased defense transcripts. CPB growth was compromised on plants damaged by either species, suggesting a low specificity of effect. Together, these data suggest distinct quantitative responses of tomato to two different specialist herbivores. Herbivore oral secretions might be responsible for these species-specific responses.