A subscription to JoVE is required to view this content. Sign in or start your free trial.

Research Article

The Causal Effects of Plasma Metabolites on Achilles Tendon Injury: A Mendelian Randomization Study

253 views

⸱

DOI:

10.3791/69807

⸱

March 27th, 2026

 ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  , 
1Department of Orthopaedic Centre Hand-Foot Surgery, People's Hospital of Ningxia Hui Autonomous Region, Ningxia Medical University, 2Ningxia Yinchuan Energy College, Nursing College, 3General Surgery Department, People's Hospital of Ningxia Hui Autonomous Region, Ningxia Medical University

In This Article

Summary

Here, we present a combined Mendelian randomization and experimental validation protocol to identify causal metabolites in Achilles tendon injury, identifying 19 plasma metabolites with causal links to Achilles tendon injury, and demonstrating the therapeutic application of 5,6-dihydrothymine and hydroxyasparagine in promoting tissue repair and reducing inflammation.

Abstract

To investigate the causal effects of plasma metabolites on the progression and recovery of Achilles tendon injury (ATI), Mendelian randomization (MR) was applied using a two-sample approach with genetic data from two large datasets. ATI data were sourced from the IEU-OpenGWAS project (ebi-a-GCST90018895), while plasma metabolite data included 1,400 metabolites. Significant instrumental variables (IVs) for metabolites were identified, and five MR methods-IVW, MR-Egger, weighted median, simple mode, and weighted mode-were applied to assess causal relationships. Reverse MR analysis was conducted to explore the impact of ATI on metabolite levels. Tissue repair and the expression of IL-6, TNF-α, VEGFA, and TGF-β1 in mouse Achilles tendon tissue were assessed on day 7 post-treatment with 5,6-dihydrothymine (Dih) and hydroxyasparagine (Hyd) using H&E staining and Western blot. MR analysis identified 19 metabolites with significant causal associations to ATI. Of these, 12 metabolites, including Dih (IVW: OR = 1.197, 95% CI: 1.074-1.334; P = 0.001) and Pregnanediol-3-glucuronide (IVW: OR = 1.098, 95% CI: 1.023-1.177; P = 0.001), were positively associated with ATI progression. In contrast, 7 metabolites, such as Hyd (IVW: OR = 0.789, 95% CI: 0.707-0.880; P < 0.001), were linked to ATI recovery. Reverse MR analysis did not indicate significant causal effects of ATI on metabolite levels, suggesting a unidirectional relationship. X-ray and H&E analyses revealed that Dih and Hyd treatment significantly enhanced Achilles tendon healing in a dose-dependent manner. Further, Dih and Hyd treatment notably reduced IL-6 and TNF-α expression (P < 0.05) while increasing VEGFA and TGF-β levels (P < 0.05), indicating a reduction in inflammation and promotion of tissue repair. This study identified potential causal relationships between specific plasma metabolites and ATI outcomes. These findings may inform future therapeutic strategies and highlight the utility of MR in exploring metabolite-disease associations.

Introduction

Achilles tendon injury (ATI) is a prevalent and debilitating musculoskeletal condition, particularly among athletes and physically active individuals1,2. The Achilles tendon, the largest and strongest tendon in the human body, plays a pivotal role in locomotion, transmitting forces from the calf muscles to the heel during activities such as walking, running, and jumping3,4,5,6. Its limited blood supply and the high mechanical stress it endures make it especially vulnerable to overuse and injury2,7. ATI manifests in various forms, ranging from mild tendinopathy to complete rupture, causing significant pain, impaired mobility, and prolonged rehabilitation8,9. Despite advances in treatment, ATI often results in persistent pain, decreased mobility, and extended recovery times, with an increased risk of chronic complications and re-injury5,10,11,12.

Recent studies have highlighted the critical role of plasma metabolites in the healing process of ATI13,14. These metabolites, involved in various biochemical pathways, are believed to influence key factors such as inflammation, tissue repair, and tendon health15. For example, specific amino acids and lipids are essential for collagen synthesis and managing oxidative stress, both of which are crucial in tendon pathology16,17. Platelet-rich plasma (PRP), rich in growth factors such as PDGF, TGF-β, VEGF, and IGF, has shown potential in promoting tendon healing, though its efficacy in treating chronic Achilles tendinopathy remains debated14. In recent years, high-throughput omics technologies, such as metabolomics and proteomics, have provided unprecedented opportunities to explore the molecular landscape of complex conditions like ATI18,19. Advanced metabolomic technologies have facilitated the identification of biomarkers linked to ATI outcomes, providing insights into how specific metabolites influence injury progression and recovery.

Metabolite profiling and the analysis of metabolic pathways have become powerful approaches for identifying biomarkers and pathways associated with injury20,21. Mendelian randomization (MR) is a robust causal inference method that utilizes genetic variants as instrumental variables (IVs) to address confounding biases common in traditional epidemiological studies22,23,24,25,26,27. MR is particularly useful for studying causal relationships between exposures, such as plasma metabolites, and outcomes like ATI. Unlike conventional observational studies, which are susceptible to confounding and reverse causation, MR uses genetic variants as IVs to provide stronger causal inferences. A deeper understanding of how plasma metabolites influence tendon health is essential for advancing therapeutic strategies and improving recovery outcomes.

Building on these advances, the present study investigates the causal role of plasma metabolites in ATI using MR. Genetic variations associated with metabolite levels were analyzed to identify specific metabolites linked to ATI progression and recovery. Additionally, candidate metabolites, such as 5,6-dihydrothymine (Dih) and hydroxyasparagine (Hyd), were experimentally validated in animal models to elucidate their effects on the course and healing of ATI.

Access restricted. Please log in or start a trial to view this content.

Protocol

Ethics approval and consent to participate

All animal experimental designs were strictly conducted in accordance with the Ningxia Province Laboratory Animal Management Measures and were approved by the Ethics Committee of People's Hospital of Ningxia Hui Autonomous Region, Ningxia Medical University.

Study Design

This study investigated the causal relationships between 1,400 plasma metabolites and ATI employing a two-sample MR methodology. To ensure the validity of IVs in causal inference, three critical assumptions must be satisfied: (1) the genetic variation is directly associated with the exposure of interest; (2) the genetic variation is not confounded by potential confounders between the exposure and the outcome; and (3) the genetic variation influences the outcome exclusively through the exposure and not via alternative pathways.

Sources of GWAS data for ATI

Data for the Genome-Wide Association Study (GWAS) on ATI were sourced from the IEU-OpenGWAS project (https://gwas.mrcieu.ac.uk/), specifically utilizing the dataset ebi-a-GCST90018895. The GWAS analysis encompassed 357,658 individuals of European ancestry, comprising 7,746 cases and 349,912 controls. Following quality control procedures, a total of 19,072,056 single-nucleotide polymorphisms (SNPs) were identified. Quality control procedures included removal of SNPs with minor allele frequency<0.01, Hardy-Weinberg equilibrium P<1×10-⁶, and genotype call rate <0.95. Population stratification was assessed using principal component analysis, and the genomic inflation factor (λ) was calculated to evaluate systematic bias.

GWAS data sources for plasma metabolites

The Exposure Factors dataset includes GWAS data for 1,400 plasma metabolites, consisting of 1,091 metabolite levels and 309 metabolite ratios, as cataloged in the GWAS database (https://www.ebi.ac.uk/gwas/studies/GCST90199621-90201020). MR analyses were restricted to individuals of European ancestry. Detailed information on the dataset is provided in Supplementary Materials, Table S1.

Selection of IVs

In the identification of IVs, the threshold for statistical significance of plasma metabolite-associated19,072,056 SNPs was set at P < 1 × 10-5. To ensure the independence of the analyses, SNPs were aggregated using thresholds of r2 = 0.001 and kilobase (kb) = 10,000, excluding 19,037,213 SNPs with r2 > 0.001 and kb < 10,000 to eliminate potential Linkage Disequilibrium (LD) effects. SNPs with F-statistic values < 10 were excluded from further analyses due to their high heterogeneity, while 34843 SNPs meeting the criteria were retained as valid IVs.

Animals and experimental design

All animal experiments were conducted in strict accordance with the Ningxia Province Laboratory Animal Management Measures and approved by the Ethics Committee of the People's Hospital of Ningxia Hui Autonomous Region, Ningxia Medical University. Male BALB/c mice (8 weeks old, SPF grade) were purchased from Beijing Vital River Laboratory Animal Technology Co., Ltd. (Beijing, China). The mice were acclimated for one week in a controlled environment (temperature 23 ± 1°C, humidity 60 ± 10%), with free access to standard food and water, and a 12 h light/12 h dark cycle. Following acclimation, a murine tendon injury model was established. After a longitudinal skin incision, the left Achilles tendon was exposed and a standardized full-thickness transverse transection was performed at the midpoint of the tendon using microsurgical scissors. The tendon was immediately repaired with 6-0 non-absorbable sutures under a stereomicroscope. Immediately following surgery, X-ray imaging was performed to verify the successful establishment of the ATI mouse model. Simultaneously, X-ray images were acquired for the control group under identical anesthetic conditions to serve as a blank control28. All procedures were performed under general anesthesia induced by intraperitoneal injection of pentobarbital sodium (50 mg·kg-1), and postoperative analgesia was provided with buprenorphine (0.05 mg·kg-1, subcutaneously) every 12 h for 48 h29. Upon successful induction of the model, mice were randomly assigned to the following groups: control, model, and treatment groups receiving Dih at low (10 mg·kg-1, LD-Hyd), medium (30 mg·kg-1, MD-Hyd), and high (50 mg·kg-1, HD-Hyd) doses. Sample size calculation: Based on preliminary data showing a 40% improvement in healing scores with metabolite treatment (SD = 15%), it was determined that n = 6 mice per group would provide 80% power to detect this difference at α = 0.05 (two-tailed). Randomization was performed using computer-generated random numbers by an investigator blinded to group allocation. Experimental procedures and outcome assessments were conducted by investigators blinded to the group assignments30.

Hematoxylin and Eosin (HE) staining

On day 7 post-treatment, mice were euthanized under deep anesthesia induced by intraperitoneal injection of pentobarbital sodium (100 mg·kg-1), ensuring complete loss of reflexes prior to tissue collection in accordance. The injured Achilles tendon tissue, including a small portion of surrounding soft tissue, was carefully harvested and processed. A 15 mm2 piece of skin centered on the Achilles tendon was excised. The skin samples were fixed in 4% paraformaldehyde solution at room temperature for 48 h, followed by dehydration, paraffin embedding, and sectioning of 5 µm. Structural characteristics of the wound skin, granulation tissue formation, and inflammatory cell infiltration were evaluated using H&E staining. For histological evaluation, sections were deparaffinized in xylene (2 × 10 min), rehydrated through graded ethanol (100%, 95%, 85%, and 75%, 5 min each), and rinsed in distilled water. Slides were stained with Harris hematoxylin for 5 minutes, rinsed in running tap water for 5 minutes, differentiated in 1% acid alcohol for 10 seconds, and blued in 0.2% ammonia water for 30 seconds. After washing, sections were counterstained with 0.5% eosin for 2 minutes, followed by dehydration, clearing, and mounting. Histological assessment reliability: To ensure measurement accuracy, 20% of randomly selected samples were independently scored by two blinded observers. Inter-rater reliability was assessed using the intraclass correlation coefficient (ICC). The ICC for collagen organization was 0.89 (95% CI: 0.81-0.94), for tissue degeneration 0.92 (95% CI: 0.86-0.96), and for inflammatory cell infiltration 0.87 (95% CI: 0.78-0.93), indicating excellent reliability. Intra-rater reliability was assessed by having one observer re-score 15% of samples after a two-week interval, yielding ICC values > 0.85 for all parameters31.

Western blot analysis

Protein expression was analyzed by Western blot. Protein quantification was performed using the BCA protein concentration assay kit. Equal amounts of protein were separated by 10% sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and transferred to a nitrocellulose membrane. The membrane was blocked for 1 h with 5% skimmed milk in Tris-buffered saline containing 0.1% Tween-20 at room temperature. Membranes were incubated overnight at 4°C with primary antibodies for VEGFA (1:1000, ab46154), TGF-β1 (1:1000, 21898-1-AP), IL-6 (1:1000, 26404-1-AP), and TNF-α (1:1000, 17590-1-AP). After three washes with PBS, the membranes were incubated with secondary antibodies (1:5000) for 90 minutes at room temperature. Protein bands were visualized using the ECL chemiluminescence substrate kit (See Table of Materials for details) following the manufacturer's protocol and analyzed using ImageJ software (version 1.8; National Institutes of Health). GAPDH (10494-1-AP) was used as the loading control.

Statistical analysis

Statistical analyses were performed using R Studio software. The TwoSampleMR and ieugwasr R packages were employed to extract exposure data and screen valid IVs, including clumping (r² < 0.001, window size = 10,000 kb), allele harmonization, and F-statistic calculation (F = β²_exposure/SE²_exposure). For MR and reverse MR analyses, we utilized the VariantAnnotation, gwasglue, and TwoSampleMR packages, which facilitated robust causal inference and sensitivity testing. A two-sample MR study was conducted to investigate plasma metabolite-related traits. Five distinct analytical approaches were employed: Inverse-Variance Weighting (IVW), MR-Egger, Weighted Median (WM), Simple Mode, and Weighted Mode. The primary results were determined using the IVW method, with statistical significance set at P < 0.01. The IVW method assigns weights to minimize the impact of variation, providing more precise effect estimates. MR-Egger regression was used to evaluate pleiotropy (the phenomenon where genes affect multiple traits), with horizontal pleiotropy assessed by the P-value of the intercept (P > 0.05), and heterogeneity tested using the IVW method combined with MR-Egger's Q statistic. No significant heterogeneity was observed when P > 0.05. Multiple testing correction was applied using the Benjamini-Hochberg false discovery rate (FDR) method, with FDR < 0.05 considered significant. Heterogeneity was quantified using Cochran's Q statistic and the I2 statistic, where I2 > 50% indicated substantial heterogeneity. For I2 values, 95% confidence intervals were calculated following the method described by Ioannidis et al. Sensitivity analyses were performed by sequentially removing each SNP to evaluate the influence of individual variants on the overall results.

To assess measurement reliability, test-retest analyses were performed on key outcome measures (WB quantification and histological scoring) using the intraclass correlation coefficients (ICCs). The ICC was employed to assess the inter-rater and intra-rater reliability of Western Blot (WB) quantification and histological scoring. The criteria were interpreted as follows: below 0.50 (poor), between 0.50 and 0.75 (moderate), between 0.75 and 0.90 (good), and above 0.90 (excellent)32. Three independent researchers blindly evaluated the same set of samples at two time points separated by one week. ICCs for Western blot quantification of IL-6, TNF-α, VEGFA, and TGF-β ranged from 0.87 to 0.93, indicating excellent reliability. ICCs for histological scoring were 0.85 for collagen organization and 0.82 for neovascularization assessment.

Access restricted. Please log in or start a trial to view this content.

Results

Causal relationship between 1,400 plasma metabolites and ATIs

A comprehensive MR analysis of 1,400 plasma metabolites was performed to assess their causal effects on ATI. The primary analysis utilized the IVW approach, with strict controls for LD and potential confounders, to identify metabolites that significantly impact ATI progression and recovery. Figure 1 displays the causal associations between 144 plasma metabolites and ATI, where an associ...

Access restricted. Please log in or start a trial to view this content.

Discussion

This study conducted a comprehensive MR analysis to explore the causal relationships between 1,400 plasma metabolites and ATI. Nineteen plasma metabolites were identified as significantly associated with ATI progression and healing, with Dih and Hyd emerging as key factors influencing ATI outcomes. Subsequent in vivo experiments confirmed the beneficial roles of these metabolites in promoting tendon healing. Treatment with Dih and Hyd resulted in significant, dose-dependent downregulation of the pro-inflammatory...

Access restricted. Please log in or start a trial to view this content.

Disclosures

The authors declare no competing interests.

Acknowledgements

Clinical Application Research on Intestinal Flora Assessment and Step-based Treatment of Chronic Ulcers in Diabetic Foot, Yinchuan Science and Technology Innovation Project (2024SF005). Application Research on the Effects of Different Surgical Methods on Peritendal Tissue Blood Supply and Biomechanical Repair of Acute Closed Achilles Tendon Rupture under the Ningxia Key Research and Development Program (2019BEG3036).

Access restricted. Please log in or start a trial to view this content.

Materials

List of materials used in this article
NameCompanyCatalog NumberComments
5,6-DihydrothymineReagent696-04-8Reagent
BCA Protein Assay KitReagentP0012Reagent
ECL Chemiluminescence Substrate KitReagentP0018SReagent
GAPDH AntibodyAntibody10494-1-APAntibody
Hematoxylin and Eosin Staining KitReagentG1120Reagent
HydroxyasparagineReagentH1126Reagent
IL-6 AntibodyAntibody26404-1-APAntibody
ImageJsoftwareversion 1.8software
Nitrocellulose MembraneConsumableHATF08130Consumable
ParaformaldehydeReagentP0099-3LReagent
RStudiosoftwareversion 4.5.2software
SDS-PAGE Gel Preparation KitReagentP0012ACReagent
Sodium PentobarbitalAnesthetic200-323-9Anesthetic
TGF-β1 AntibodyAntibody21898-1-APAntibody
TNF-α AntibodyAntibody17590-1-APAntibody
VEGFA AntibodyAntibodyab46154Antibody
X-ray systemInstrumentMX-20Instrument

References

  1. Kvist, M. Achilles tendon injuries in athletes. Sports Med. 18 (3), 173-201 (1994).
  2. Järvinen, T. A., et al. Achilles tendon injuries. Curr Opin Rheumatol. 13 (2), 150-155 (2001).
  3. Barfod, K. W. Achilles tendon rupture; assessment of nonoperative treatment. Dan Med J. 61 (4), B4837(2014).
  4. Buddecke, D. Jr Acute Achilles Tendon Ruptures. Clin Podiatr Med Surg. 38 (2), 201-226 (2021).
  5. Bullock, M., Pierson, Z. Achilles Tendon Rupture. Clin Podiatr Med Surg. 41 (3), 535-549 (2024).
  6. Oliva, F., et al. Influence of Exercise on Musculoskeletal Disorders Associated with Gut Microbiota: A Narrative Review. MLTJ. 13 (1), (2023).
  7. Caldwell, J. E., Vosseller, J. T. Maximizing Return to Sports After Achilles Tendon Rupture in Athletes. Foot Ankle Clin. 24 (3), (2019).
  8. King, C. M., Vartivarian, M. Achilles Tendon Rupture Repair: Simple to Complex. Clin Podiatr Med Surg. 40 (1), 75-96 (2023).
  9. Kraeutler, M. J., Purcell, J. M., Hunt, K. J. Chronic Achilles Tendon Ruptures. Foot Ankle Int. 38 (8), 921-929 (2017).
  10. Vascellari, A., et al. Orthobiologics Injection Therapies in the Treatment of Muscle and Tendon Disorders in Athletes: Fact or Fake. MLTJ. 14 (2), (2024).
  11. Winnicki, K., Ochała-Kłos, A., Rutowicz, B., Pękala, P. A., Tomaszewski, K. A. Functional anatomy, histology and biomechanics of the human Achilles tendon - A comprehensive review. Ann Anat. 229, 151461(2020).
  12. Strom, A. C., Casillas, M. M. Achilles tendon rehabilitation. Foot Ankle Clin. 14 (4), 773-782 (2009).
  13. Sun, J. Y., Li, C., Du, F. Y. Adenylate cyclase activates the cAMP signalling pathway to enhance platelet-rich plasma-treated Achilles tendon disease,a theoretical bioinformatics-based study. World Journal of Orthopedics. 15 (2), 192-200 (2024).
  14. Restuccia, G., Varchetta, G. E. Platelet rich plasma (PRP) in the surgical treatment of Haglund's syndrome: the use of PRP membranes as an intra-operative local adjuvant. medicinski glasnik. 21 (1), 196-202 (2024).
  15. Wang, K., Cheng, L., He, B. Therapeutic effects of asperosaponin VI in rabbit tendon disease. Regen Ther. 20, 1-8 (2022).
  16. Shen, H., Lane, R. A. Extracellular Vesicles From Primed Adipose-Derived Stem Cells Enhance Achilles Tendon Repair by Reducing Inflammation and Promoting Intrinsic Healing. Stem Cells. 41 (6), 617-627 (2023).
  17. Bisciotti, G. N., et al. Achilles Tendon Repair after Tenorraphy Imaging and the Doughnut Metaphor. Int J Environ Res Public Health. 20 (11), (2023).
  18. Roh, C. Metabolomics in Radiation-Induced Biological Dosimetry: A Mini-Review and a Polyamine Study. Biomolecules. 8 (2), (2018).
  19. Malinowska, J. M., et al. Derivation of metabolic point of departure using high-throughput in vitro metabolomics: investigating the importance of sampling time points on benchmark concentration values in the HepaRG cell line. Arch Toxicol. 97 (3), 721-735 (2023).
  20. He, L., et al. Causal Associations of Obesity With Achilles Tendinopathy: A Two-Sample Mendelian Randomization Study. Front Endocrinol (Lausanne). 13, 902142(2022).
  21. Koike, Y., et al. Genetic insights into ossification of the posterior longitudinal ligament of the spine. Elife. 12, (2023).
  22. Birney, E. Mendelian Randomization. Cold Spring Harb Perspect Med. 12 (4), (2022).
  23. Burgess, S., Thompson, S. G. Interpreting findings from Mendelian randomization using the MR-Egger method. Eur J Epidemiol. 32 (5), 377-389 (2017).
  24. Georgakis, M. K., Gill, D. Mendelian Randomization Studies in Stroke: Exploration of Risk Factors and Drug Targets With Human Genetic Data. Stroke. 52 (9), 2992-3003 (2021).
  25. Ho, J., Mak, C. C. H., Sharma, V., To, K., Khan, W. Mendelian Randomization Studies of Lifestyle-Related Risk Factors for Osteoarthritis: A PRISMA Review and Meta-Analysis. Int J Mol Sci. 23 (19), (2022).
  26. Larsson, S. C., Butterworth, A. S., Burgess, S. Mendelian randomization for cardiovascular diseases: principles and applications. Eur Heart J. 44 (47), 4913-4924 (2023).
  27. Sekula, P., Del Greco, M. F., Pattaro, C., Köttgen, A. Mendelian Randomization as an Approach to Assess Causality Using Observational Data. J Am Soc Nephrol. 27 (11), 3253-3265 (2016).
  28. Zhao, X., Wang, Q., Wang, W., Lu, S. Increased neutrophil extracellular traps caused by diet-induced obesity delay fracture healing. Faseb j. 38 (20), e70126(2024).
  29. Lin, K., et al. Exosomal miR-212-5p promotes tendon repair via targeting FOXO1 to activate PP1A/YAP1 signaling. Commun Biol. 8 (1), 1798(2025).
  30. Migliorini, F., et al. Management of transient bone osteoporosis: a systematic review. Br Med Bull. 147 (1), 79-89 (2023).
  31. Napoli, R., et al. Cross Cultural Adaptation and Multi Centric Validation of The Italian Version of The Tegner Activity Scale. Muscle Ligaments Tendons J. , (2023).
  32. Koo, T. K., Li, M. Y. A Guideline of Selecting and Reporting Intraclass Correlation Coefficients for Reliability Research. J Chiropr Med. 15 (2), 155-163 (2016).
  33. Hafez, A. E., Ismail, F. M., Abdelhakeem, M. A., Ragaee, S., Soliman, S. A. Musculoskeletal Ultrasound Changes in Chronic Plantar Fascia after Treatment with Platelet Rich Plasma Compared to Steroid. Muscle Ligaments Tendons J. 13 (01), 126(2023).
  34. Xiangyang, Y., et al. Sirtuin1 mitigation of calcium oxalate nephropathy via enhancing itaconate abundance through reduction of histone trimethylation. Clin Transl Med. 15 (8), (2025).
  35. Roland, K., et al. Ceramides in cardiovascular disease: emerging role as independent risk predictors and novel therapeutic targets. Cardiovasc Res. 121 (9), (2025).
  36. Kathryn, A. M., Bernard, D. K., Anna, N. Circulating ceramides as biomarkers of cardiovascular disease: Evidence from phenotypic and genomic studies. Atherosclerosis. 327 (0), (2021).
  37. Kuliś, S., Pietraszewski, P., Callegari, B. Characteristics of Post-Exercise Lower Limb Muscle Tremor Among Speed Skaters. Sensors (Basel). 25 (14), (2025).
  38. Tuniyazi, M., et al. Changes of microbial and metabolome of the equine hindgut during oligofructose-induced laminitis. BMC Vet Res. 17 (1), 11(2021).
  39. Dobritzsch, D., et al. β-Ureidopropionase deficiency due to novel and rare UPB1 mutations affecting pre-mRNA splicing and protein structural integrity and catalytic activity. Mol Genet Metab. 136 (3), 177-185 (2022).
  40. Nakajima, Y., et al. Dihydropyrimidinase deficiency in four East Asian patients due to novel and rare DPYS mutations affecting protein structural integrity and catalytic activity. Mol Genet Metab. 122 (4), 216-222 (2017).
  41. Hirano, M., et al. Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE): Position paper on diagnosis, prognosis, and treatment by the MNGIE International Network. J Inherit Metab Dis. 44 (2), 376-387 (2021).
  42. Mukherjee, A., et al. Adipocytes reprogram cancer cell metabolism by diverting glucose towards glycerol-3-phosphate thereby promoting metastasis. Nat Metab. 5 (9), 1563-1577 (2023).
  43. Tighanimine, K., et al. A homoeostatic switch causing glycerol-3-phosphate and phosphoethanolamine accumulation triggers senescence by rewiring lipid metabolism. Nat Metab. 6 (2), 323-342 (2024).
  44. Blackwell, L. F., Cooke, D. G., Brown, S. The Use of Estrone-3-Glucuronide and Pregnanediol-3-Glucuronide Excretion Rates to Navigate the Continuum of Ovarian Activity. Front Public Health. 6, 153(2018).
  45. Chen, J., et al. Quantitation of serum pregnanediol-3-glucuronide level in different endocrine statuses by LC-MS/MS. J Pharm Biomed Anal. 184, 113171(2020).
  46. Usala, S. J., Alliende, M. E., Trindade, A. A. Algorithms with Area under the Curve for Daily Urinary Estrone-3-Glucuronide and Pregnanediol-3-Glucuronide to Signal the Transition to the Luteal Phase. Medicina (Kaunas). 58 (1), (2022).
  47. Feng, J., Huang, Z., Cui, C., Zhao, M., Feng, Y. Synthesis, taste characteristics and taste mechanism of N-lactoyl leucine from soy sauce using sensory analysis and UPLC-MS/MS. Food Chem. 454, 139670(2024).
  48. Fernandes Silva, L., Hokkanen, J., Vangipurapu, J., Oravilahti, A., Laakso, M. Metabolites as Risk Factors for Diabetic Retinopathy in Patients With Type 2 Diabetes: A 12-Year Follow-up Study. J Clin Endocrinol Metab. 109 (1), 100-106 (2023).
  49. Ito, T., Tono, M., Kitaura, Y., Hemmi, H., Yoshimura, T. Urinary l-erythro-β-hydroxyasparagine-a novel serine racemase inhibitor and substrate of the Zn2+-dependent d-serine dehydratase. Biosci Rep. 41 (4), (2021).
  50. Xia, Y., et al. N(γ) -Hydroxyasparagine: A Multifunctional Unnatural Amino Acid That is a Good P1 Substrate of Asparaginyl Peptide Ligases. Angew Chem Int Ed Engl. 60 (41), 22207-22211 (2021).
  51. Schmidt, C., et al. Lactoyl leucine and isoleucine are bioavailable alternatives for canonical amino acids in cell culture media. Biotechnol Bioeng. 118 (9), 3395-3408 (2021).
  52. Castro, B. M., Prieto, M., Silva, L. C. Ceramide: a simple sphingolipid with unique biophysical properties. Prog Lipid Res. 54, 53-67 (2014).
  53. Cogolludo, A., Villamor, E., Perez-Vizcaino, F., Moreno, L. Ceramide and Regulation of Vascular Tone. Int J Mol Sci. 20 (2), (2019).
  54. Zhang, J., Wei, L., Tan, H., Pang, W. Gut microbiota and postpartum depression: a Mendelian randomization study. Front Psychiatry. 15, 1282742(2024).
  55. Liu, Y., et al. The risk of Alzheimer's disease and cognitive impairment characteristics in eight mental disorders: A UK Biobank observational study and Mendelian randomization analysis. Alzheimers Dement. 20 (7), 4841-4853 (2024).
  56. Chi, J., et al. Causal effects for neurodegenerative diseases on the risk of myocardial infarction: a two-sample Mendelian randomization study. Aging (Albany NY). 16 (11), 9944-9958 (2024).
  57. Tan, Z., Hong, J., Sun, A., Ding, M., Shen, J. Causal effects of circulating lipids and lipid-lowering drugs on the risk of urinary stones: a Mendelian randomization study. Front Endocrinol (Lausanne). 14, 1301163(2023).
  58. Kitsios, G. D., Thaler, D. E., Kent, D. M. Potentially large yet uncertain benefits: a meta-analysis of patent foramen ovale closure trials. Stroke. 44 (9), 2640-2643 (2013).
  59. Sung, C. W., et al. Prediction of high-risk emergency department revisits from a machine-learning algorithm: a proof-of-concept study. BMJ Health Care Inform. 31 (1), (2024).
  60. Lidi, L., Jennifer, H., Daniel, J. L., Hui, B. S. Advances of stem cell based-therapeutic approaches for tendon repair. J Orthop Translat. 9 (0), (2018).
  61. Daibang, N., Yiqin, Z., Wang, W., Jianying, Z., James, H. -C. W. Mechanical Overloading Induced-Activation of mTOR Signaling in Tendon Stem/Progenitor Cells Contributes to Tendinopathy Development. Front Cell Dev Biol. 9 (0), (2021).
  62. Mathieu, M., et al. Trigonelline is an NAD(+) precursor that improves muscle function during ageing and is reduced in human sarcopenia. Nat Metab. 6 (3), (2024).
  63. Yoshida, M., Funasaki, H. Optimal Platelet Concentration for The Therapeutic Effect of Autologous Neutrophil-Reduced Platelet Rich Plasma in A Rat Model of Achilles Tendinopathy. Muscles, Ligaments & Tendons Journal (MLTJ). 10 (4), (2020).
  64. Kuan-Ju, C., Li-Cheng, C., Yi-No, K., Chiehfeng, C. Autologous Stem Cell Therapy for Chronic Lower Extremity Wounds: A Meta-Analysis of Randomized Controlled Trials. Cells. 10 (12), (2021).
  65. Gupta, S., Paliczak, A., Delgado, D. Evidence-based indications of platelet-rich plasma therapy. Expert Rev Hematol. 14 (1), 97-108 (2021).
  66. Impellizzeri, F. M., Bizzini, M. Systematic review and meta-analysis: A primer. International Journal of Sports Physical Therapy. 7 (5), 493-503 (2012).

Access restricted. Please log in or start a trial to view this content.

Reprints and Permissions

Tags

Tissue RepairGenetic DataInstrumental VariablesWestern BlotInflammation MarkersMouse Tendon TissueCausal Associations
Contact Us
Recommend to Library

Privacy

Terms of Use

Policies

Copyright © 2026 MyJoVE Corporation. All rights reserved.