Contemporary review of the management of left ventricular thrombus

Funding Acknowledgements

Type of funding sources: None.

Introduction

Left ventricular thrombus (LVT) is a known complication of acute myocardial infarction (AMI) and other cardiomyopathies. LVT increases the risk of stroke and systemic embolism, hence treatment with oral anticoagulation is indicated. While the initial treatment options for LVT is clear, the management of patients after the initial duration of anticoagulation is more complex and varied.

Purpose

We aimed to undertake a comprehensive literature review to study the currently available evidence regarding not only the initial type and duration of anticoagulation for LVT, but also potential treatment options after the initial period of anticoagulation in the setting of both LVT persistence and resolution.

Methods

MEDLINE, EMBASE, Scopus, and Google Scholar were searched from inception to August 2022. Data from randomized controlled trials (RCTs), observational studies and case series discussing management of LVT were included in this summarized synthesis.

Results

Of 2050 studies screened, 30 studies (24 observational studies, 3 case series, 2 RCTs, 1 non-randomized, open-label trial) were included. A total of 17 studies compared warfarin with direct oral anticoagulants (DOACs) for the initial anticoagulation strategy, with the vast majority showing similar outcomes (Table 1). Half (n = 9/18) of the studies repeated imaging between 3-6 months. All studies (n=30) used transthoracic echo with or without contrast as the imaging modality of choice, with selected patients undergoing computed tomography (CT) or cardiac magnetic resonance (CMR). If the LVT persisted, most studies recommended continuing anticoagulation (n = 11/16, 69%) or switching to a different class of anticoagulants (n = 6/16, 38%). In the event of LVT non-resolution, high-risk features of embolization (protruding, mobile vs layered clot) may aid in the discussion of risk and benefit of long-term anticoagulation. Even upon resolution of the LVT, some studies (n=5) recommend continuing anticoagulation in the presence of high-risk features of recurrence (eg. persistently depressed left ventricle ejection fraction (LVEF) and/or apical wall dyskinesis). Regardless, medical management should be optimized together with the appropriate revascularization strategy as clinically indicated.

Conclusions

Current evidence on the management of LVT is limited. This updated review summarizes the available evidence for the management for LVT. Evidence-based recommendations on the management of these patients is warranted to appropriately guide clinicians.

Catheter ablation vs medical therapy for treatment of atrial fibrillation patients with heart failure with preserved ejection fraction: a systematic review and meta-analysis

Funding Acknowledgements

Type of funding sources: None.

Introduction

Catheter ablation (CA) is used as a treatment option in selected patients with atrial fibrillation (AF) and heart failure with reduced ejection fraction (HFrEF) as studies have shown that it reduces heart failure (HF) hospitalization, improves survival, and reduces rates of AF recurrence when compared to medical therapy. However, it is not known whether this benefit persists in patients with heart failure with preserved ejection fraction (HFpEF).

Purpose

The aim of this meta-analysis is to compare CA versus medical therapy in patients with AF and HFpEF

Methods

MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials were searched from August 2012 to August 2022. All randomized controlled trials (RCTs), propensity score matched (PSM) studies, and observational studies including conference abstracts providing outcomes in patients with HFpEF and AF after CA were included. Outcomes examined include all-cause mortality, HF hospitalizations, and AF recurrence. A random-effects model using R statistical software was used to calculate odds ratios (OR) and 95% confidence intervals (CI).

Results

Of 3151 studies screened, 8 studies (1 RCT, 4 PSM, 3 observational) were included with a pooled population of 2171 and 24087 patients with AF and HFpEF who underwent CA and medical therapy respectively. There were no significant differences in baseline age (70.6 vs 70.7, p = 0.16), proportion of hypertension (85.0% vs 86.4%, p = 0.58), diabetes (33.8% vs 35.8%, p = 0.39), coronary artery disease (40.2% vs 41.8%, p = 0.06), or men (42.3 vs 36.6%, p = 0.42). After a mean weighted follow-up of 9.45 months, there was no significant difference in all-cause mortality (OR 0.77 [0.47-1.26], p = 0.07), HF hospitalizations (OR 0.44 [0.18-1.08], p = 0.22), but a significantly lower rate of AF recurrence (OR 0.22 [0.09-0.54], p = 0.001) associated with CA.

Conclusion

In patient with HFpEF, CA significantly reduced AF recurrence compared with medical therapy but with no difference in mortality or HF hospitalization. CA continues to have an important role to play in treatment of AF even in HFpEF patients.

Molecular crosstalk between articular cartilage, meniscus, synovium, and subchondral bone in osteoarthritis

AIMS

Osteoarthritis (OA) is a common degenerative joint disease worldwide, which is characterized by articular cartilage lesions. With more understanding of the disease, OA is considered to be a disorder of the whole joint. However, molecular communication within and between tissues during the disease process is still unclear. In this study, we used transcriptome data to reveal crosstalk between different tissues in OA.

METHODS

We used four groups of transcription profiles acquired from the Gene Expression Omnibus database, including articular cartilage, meniscus, synovium, and subchondral bone, to screen differentially expressed genes during OA. Potential crosstalk between tissues was depicted by ligand-receptor pairs.

RESULTS

During OA, there were 626, 97, 1,060, and 2,330 differentially expressed genes in articular cartilage, meniscus, synovium, and subchondral bone, respectively. Gene Ontology enrichment revealed that these genes were enriched in extracellular matrix and structure organization, ossification, neutrophil degranulation, and activation at different degrees. Through ligand-receptor pairing and proteome of OA synovial fluid, we predicted ligand-receptor interactions and constructed a crosstalk atlas of the whole joint. Several interactions were reproduced by transwell experiment in chondrocytes and synovial cells, including TNC-NT5E, TNC-SDC4, FN1-ITGA5, and FN1-NT5E. After lipopolysaccharide (LPS) or interleukin (IL)-1β stimulation, the ligand expression of chondrocytes and synovial cells was upregulated, and corresponding receptors of co-culture cells were also upregulated.

CONCLUSION

Each tissue displayed a different expression pattern in transcriptome, demonstrating their specific roles in OA. We highlighted tissue molecular crosstalk through ligand-receptor pairs in OA pathophysiology, and generated a crosstalk atlas. Strategies to interfere with these candidate ligands and receptors may help to discover molecular targets for future OA therapy.Cite this article: Bone Joint Res 2022;11(12):862-872.

An Improved Modeling and Numerical Analysis Method for Tooth Surface Wear of Double-Arc Harmonic Gears

Tooth surface wear is one of the most common failure modes of harmonic gears, especially in space drive mechanisms. Due to difficulty accurately modeling its wear failure model and the complex mechanism, its dynamic behavior and wear mechanism have not been deeply investigated, and study of the double-arc tooth profile wear model is relative lacking. Therefore, an improved wear modelling and analysis method that is more in line with actual conditions for double-arc harmonic gears is here proposed. Firstly, a tooth surface wear model under mixed elastohydrodynamic lubrication (EHL) was established based on the Archard formula, which combines the Reynolds equation and double-arc tooth profile equation, and considering the meshing offset caused by elastic deformation. Then, the wear analysis method combined with mixed EHL was derived, and numerical simulation analysis of the wear characteristics in lubrication state was carried out, including wear depth calculation and wear output comparison of different tooth profiles. Furthermore, the influence of main working parameters and design parameters on the wear quantity was analyzed. The results show that wear depth for mixed EHL is significantly less than at dry contact. The double-arc tooth profile can withstand more wear cycles than the involute tooth profile, and the input torque and the number of cycles significantly affect the amount of tooth wear. This study further reveals the tooth wear mechanism for harmonic gears, and provides a theoretical basis for the structural optimization design, wear reduction, and life prolonging of harmonic gears.

Articular fibrocartilage-targeted therapy by microtubule stabilization

The fibrocartilage presented on the joint surface was caused by cartilage injury or degeneration. There is still a lack of effective strategies for fibrocartilage. Here, we hypothesized that the fibrocartilage could be viewed as a raw material for the renewal of hyaline cartilage and proposed a previously unidentified strategy of cartilage regeneration, namely, "fibrocartilage hyalinization." Cytoskeleton remodeling plays a vital role in modifying the cellular phenotype. We identified that microtubule stabilization by docetaxel repressed cartilage fibrosis and increased the hyaline cartilage extracellular matrix. We further designed a fibrocartilage-targeted negatively charged thermosensitive hydrogel for the sustained delivery of docetaxel, which promoted fibrocartilage hyalinization in the cartilage defect model. Moreover, the mechanism of fibrocartilage hyalinization by microtubule stabilization was verified as the inhibition of Sparc (secreted protein acidic and rich in cysteine). Together, our study suggested that articular fibrocartilage-targeted therapy in situ was a promising strategy for hyaline cartilage repair.

Hysteresis analysis reveals dissolved carbon concentration - discharge relationships during and between storm events

The dissolved carbon concentration, which is responsible for aquatic ecosystem productivity and water quality, is tightly coupled with hydrological processes. Excess dissolved carbon may exacerbate eutrophication and hypoxia in aquatic ecosystems and lead to deterioration of water quality. Storm events dominate the dynamics of dissolved carbon concentrations, and this nonlinear behavior exhibits significant time scale dependence. Here, we identified inter- and intra-event variability in the dissolved carbon concentration-discharge (C-Q) relationship in an agriculture-intensive catchment. The driving factors of C-Q hysteresis patterns for dissolved inorganic carbon (DIC) and organic carbon (DOC) were quantified by redundancy analysis combined with hierarchical partitioning. At the inter-event scale, DIC exhibited mainly clockwise hysteresis, indicating an exhaustible, proximal source (e.g., groundwater). However, DOC hysteresis was generally counter-clockwise, indicating distal and plentiful sources (e.g., soil water) in the agricultural catchment. Hierarchical partitioning showed that total rainfall, peak discharge and flood intensity explained 28.38% of the total variation in C-Q hysteresis for DIC and 39.87% for DOC at the inter-event scale. At the intra-event scale, time series analysis of dissolved carbon concentration and discharge indicated the interconversion of supply limitation to transport limitation, which depends on the activation of the specific DIC or DOC source zones. These findings provide significant insights into understanding the dynamics of dissolved carbon during storm periods and are important for targeted watershed management practices aimed at reducing carbon loading to surface waters.

Downregulation of Crystallin Lambda 1 is a New Independent Prognostic Marker in Clear Cell Renal Cell Carcinoma

Background

Clear cell renal cell carcinoma (ccRCC), the most prevalent kidney cancer subtype, has a high mortality rate. Crystallin lambda 1 (CRYL1) encodes an enzyme that catalyzes the dehydrogenation of L-gulonate into dehydro-L-gulonate in uronate cycle. CRYL1 dysregulation has been linked to the progression of several cancers. This research aimed to evaluate the prognostic significance of CRYL1 expression in ccRCC prognosis.

Methods

Clinical data and gene expression profiles on ccRCC were retrieved from the University of California Santa Cruz Xena platform. Differences (variations) in the expression profiles of CRYL1 in ccRCC and healthy tissues were found using RNA-sequencing data, and these findings were validated using qPCR with real-world samples. CRYL1 expression levels were also linked to clinicopathological characteristics, survival, and immune microenvironments. The potential pathway via which CRYL1 expression levels impact the prognosis of patients with ccRCC was investigated using gene set enrichment analysis (GSEA).

Results

In ccRCC tissues, CRYL1 expression levels were lower compared to healthy renal tissues in TCGA cohort (n = 535, P < 0.001), which was validated in another real-world cohort (n = 14, P < 0.001). Lower CRYL1 expression levels were linked to unfavorable clinicopathological characteristics and prognoses (P < 0.001). According to multivariate Cox regression analysis (P < 0.001), CRYL1 expression levels in patients with ccRCC could serve as an independent prognostic indicator. Furthermore, a strong link between CRYL1 expression levels and immune microenvironment was observed (P < 0.001). Finally, GSEA revealed that CRYL1 expression levels (P < 0.001) were associated with fatty acid metabolism, G2M checkpoint delays, and epithelial-mesenchymal transitions in ccRCC.

Conclusion

Our study found that lower levels of CRYL1 expression were linked to unfavorable clinicopathological characteristics and worse prognoses, and CRYL1 could serve as a new target for the treatment of ccRCC, which is useful for personalized medicine.

High-fidelity noise-reconstructed empirical mode decomposition for mechanical multiple and weak fault extractions

The premise to ensure the safe operation of rotating machinery is to accurately and timely capture all kinds of damages and fault signatures, whose challenging issues are the multiple and weak faults. Ensemble noise-reconstructed empirical mode decomposition (ENEMD) is a smart method of adaptively decomposing and denoising for mechanical fault diagnosis. However, the original ENEMD and its derivative methods suffer from the drawbacks of critical noise estimation on the high accuracy, leading to the powerless capability for accurate multiple and weak fault signature extraction. Thus, high-fidelity noise-reconstructed empirical mode decomposition (HNEMD) is proposed to overcome the drawbacks, whose compositions include: (1) The cepstral neighboring coefficient editing is proposed to obtain the pre-whitening signal with the actual white noise, from which the major noise can be well purified by the minimax thresholding. (2) The high order singular value decomposition (HOSVD) local reconstruction is developed to estimate the minor noise from the pre-characterizing signal, where the tensor with the reasonable singular order is constructed by the sliding window and Hankel matrix. (3) The high-fidelity noise recovered by the major noise and the minor noise is reconstructed and combined with the basic ENEMD algorithm for accurate signature extraction, especially for the multiple or/and weak fault ones. Three repeatable simulations are analyzed to illustrate the signature extraction capability and noise estimation process of this method. Moreover, the effective detections of weak and multiple faults from a hot strip finishing mill gearbox and an aerospace bearing further validate the feasibility of the proposed method.

[Analysis of HIV transmission hotspots and characteristics of cross-regional transmission in Guangxi Zhuang Autonomous Region based on molecular network]

Objective: To analyze HIV transmission hotspots and characteristics of cross-regional transmission in Guangxi Zhuang autonomous region (Guangxi) based on the molecular network analysis, and provide evidence for optimization of precise AIDS prevention and control strategies. Methods: A total of 5 996 HIV pol sequences sampled from Guangxi between 1997 and 2020 were analyzed together with 165 534 published HIV pol sequences sampled from other regions. HIV-TRACE was used to construct molecular network in a pairwise genetic distance threshold of 0.5%. Results: The proportion of HIV sequences entering the molecular network of HIV transmission hotspots in Guangxi was 31.5% (1 886/5 996). In the molecular network of HIV cross-regional transmission, the links within Guangxi accounted for 51.6% (2 613/5 062), the links between Guangxi and other provinces in China accounted for 48.0% (2 430/5 062), and the links between Guangxi and other countries accounted for 0.4% (19/5 062). The main regions which had cross-regional linked with Guangxi were Guangdong (49.5%, 1 212/2 449), Beijing (17.5%, 430/2 449), Shanghai (6.9%, 168/2 449), Sichuan (5.7%, 140/2 449), Yunnan (4.2%, 102/2 449), Shaanxi (3.8%, 93/2 449), Zhejiang (2.8%, 69/2 449), Hainan (2.0%, 49/2 449), Anhui (1.5%, 37/2 449), Jiangsu (1.3%, 33/2 449), and other regions (each one <1.0%), respectively. The risk factors of entering the molecular network of HIV transmission hotspots in Guangxi included being aged ≥50 years (compared with being aged 25-49 years, aOR=1.68,95%CI:1.46-1.95), males (compared with females, aOR=1.21,95%CI:1.05-1.40), being single (compared with being married, aOR=1.18,95%CI:1.00-1.39), having education level of high school or above (compared with having education level of junior high school or below, aOR=1.21,95%CI:1.04-1.42), acquired HIV through homosexual intercourse (compared with acquired with HIV through heterosexual intercourse, aOR=1.77, 95%CI:1.48-2.12). The risk factors of cross-regional transmission included males (compared with females, aOR=1.74,95%CI:1.13-2.75), having education level of high school or above (compared with having education level of junior high school or below, aOR=1.96,95%CI:1.43-2.69), being freelancer/unemployed/retired (compared with being farmers, aOR=1.50,95%CI:1.07-2.11), acquired HIV through homosexual intercourse (compared with acquired with HIV through heterosexual intercourse, aOR=3.28,95%CI:2.30-4.72). Conclusion: There are HIV transmission hotspots in Guangxi. Guangxi and other provinces in China form a complex cross-regional transmission network. Future studies should carry out social network surveys in high-risk populations inferred from the molecular network analysis for the timely identification of hidden transmission chains and reduction of the second-generation transmission of HIV.

Genomic testing for copy number and single nucleotide variants in spermatogenic failure

PURPOSE

To identify clinically significant genomic copy number (CNV) and single nucleotide variants (SNV) in males with unexplained spermatogenic failure (SPGF).

MATERIALS AND METHODS

Peripheral blood DNA from 97/102 study participants diagnosed with oligozoospermia, severe oligozoospermia, or non-obstructive azoospermia (NOA) was analyzed for CNVs via array comparative genomic hybridization (aCGH) and SNVs using whole-exome sequencing (WES).

RESULTS

Of the 2544 CNVs identified in individuals with SPGF, > 90% were small, ranging from 0.6 to 75 kb. Thirty, clinically relevant genomic aberrations, were detected in 28 patients (~ 29%). These included likely diagnostic CNVs in 3/41 NOA patients (~ 7%): 1 hemizygous, intragenic TEX11 deletion, 1 hemizygous DDX53 full gene deletion, and 1 homozygous, intragenic STK11 deletion. High-level mosaicism for X chromosome disomy (~ 10% 46,XY and ~ 90% 47,XXY) was also identified in 3 of 41 NOA patients who previously tested normal with conventional karyotyping. The remaining 24 CNVs detected were heterozygous, autosomal recessive carrier variants. Follow-up WES analysis confirmed 8 of 27 (30%) CNVs (X chromosome disomy excluded). WES analysis additionally identified 13 significant SNVs and/or indels in 9 patients (~ 9%) including X-linked AR, KAL1, and NR0B1 variants.

CONCLUSION

Using a combined genome-wide aCGH/WES approach, we identified pathogenic and likely pathogenic SNVs and CNVs in 15 patients (15%) with unexplained SPGF. This value equals the detection rate of conventional testing for aneuploidies and is considerably higher than the prevalence of Y chromosome microdeletions. Our results underscore the importance of comprehensive genomic analysis in emerging diagnostic testing of complex conditions like male infertility.

[Variables associated with hematological remission and survival in patients with acute myeloid leukemia after induction failure and relapse]

Objective: This study aimed to explore variables associated with remission rate and survival in patients with acute myeloid leukemia (AML) after induction failure and relapse. Methods: Data of 373 consecutive patients with AML were analyzed after induction failure and relapse. Binary logistics and the Cox model regression were used to identify variables associated with remission rate and outcomes. Results: In patients with AML after induction failure and relapse, the total CR+CRi rates were 50.6% and 40.3%, respectively; among those who achieved CR/CRi, the 3-year RFS rates were 34.4% and 30.4%, respectively, and the 3-year overall survival rates were 40.1% and 31.6%, respectively. In the multivariate analyses, using CLAG or FLAG regimen as a re-induction chemotherapy regimen, age <39 years and SWOG low-risk were significantly associated with higher remission rates in patients with induction failure. Male, secondary AML, SWOG high-risk, the interval from the first remission to relapse within 12 months, and bone marrow blasts ≥20% at the time of relapse were significantly associated with lower remission rates in relapsed patients. Transplantation was significantly associated with prolonged relapse-free survival and overall survival in patients achieving hematologic remission; the SWOG low-risk group was significantly associated with longer overall survival in those with induction failure; and achieving CR (not CRi) or having female gender was associated with longer RFS or overall survival in relapsed patients. Conclusion: Reinduction chemotherapy regimen, age, gender, SWOG risk, secondary AML, the interval from the first remission to relapse, and bone marrow blast percentage at the time of relapse were significantly associated with remission rates in the patients with AML after induction failure and relapse. Transplantation, SWOG low-risk, achieving CR, or female gender were associated with longer survivals in those achieving remission.

[Effectiveness investigation on left bundle branch area pacing in 10 infants and toddlers]

Objective: To explore the feasibility, safety and effectiveness of left bundle branch area pacing (LBBAP) in children aged ≤3 years. Methods: A total of 10 children aged ≤3 years who were diagnosed with brady arrhythmia in the First Hospital of Tsinghua University from September 2020 to September 2021 were retrospectively analyzed. All the children met the indication of permanent pacemaker implantation and underwent LBBAP successfully. The intraoperative data (pacing parameters, electrocardiogram and radiographic imaging), cardiac ultrasound data and clinical data during regular postoperative follow-up were recorded. The preoperative and postoperative data were compared using matched samples t test. Results: Ten children (aged (1.6±0.7) years with weight of (10.3±2.5) kg) underwent LBBAP successfully. The QRS wave duration on the postoperative electrocardiogram was (100±9) ms, and the percentage of ventricular pacing was (97±7)%. The postoperative follow-up period was 6 (6, 12) months. At 1 week after operation, the left ventricular end-diastolic diameter Z scores in these children reduced significantly compared with those before operation (1.3±0.6 vs. 3.6±1.1, t=9.37, P<0.001). During the follow-up period, cardiac function was normal and the last left ventricular ejection fraction was (66±4)% in all children. At the last follow-up, the pacing threshold of the 10 children was smaller than 1.0 V and was acceptable. Compared with the intraoperative baseline values, the pacing threshold was slightly higher ((0.8±0.1) vs. (0.5±0.1) V, t=-5.27, P=0.001). However, no significant difference was found regarding sensing threshold ((16±5) vs. (14±4) mV, t=-0.83, P=0.426) and impedance ((584±88) vs. (652±86) Ω, t=2.26, P=0.050). During follow-up, no electrode related complications were recorded. Conclusions: LBBAP is safe and effective for infants and toddlers. Narrow QRS pacing with stable pacing parameters and normal cardiac function could be achieved postoperatively.

[Effectiveness, safety and cost of urinary follicle stimulating hormone in controlled ovarian stimulation in China: multi-center retrospective cohort study of 102 061 in vitro fertilization cycles]

Objective: To explore the effectiveness, safety and cost between urinary follicle stimulating hormone (uFSH) and recombinant follicle stimulating hormone (rFSH) in controlled ovarian stimulation (COS) in China. Methods: Data were collected from 16 reproductive centers in China covering oocytes collection time from May 1, 2015 to June 30, 2018. Eligible patients were over 18 years old, adopting COS with uFSH (uFSH group) or rFSH (rFSH group) as start gonadotropins (Gn), and using in vitro fertilization (IVF) and (or) intracytoplasmic sperm injection for fertilisation, excluding frozen embryo recovery cycle. Generalised estimating equation was used to address the violation of independency assumption between cycles due to multiple IVF cycles for one person and clustering nature of cycles carried out within one center. Controlling variables included age, body mass index, anti-Müllerian hormone level, cause of infertility, ovulation protocol, type of fertilisation, number of embryos transferred, number of days of Gn use. Results: Totally 102 061 cycles met eligibility criteria and were included in the analyses. In terms of effectiveness, after controlling relevant unbalanced baseline characteristics, compared with rFSH group, the high oocyte retrieval (>15 oocytes was considered high retrieval) rate of uFSH group significantly decreased in gonadotropin-releasing hormone agonist protocol (OR=0.642, P<0.01) and in gonadotropin-releasing hormone antagonist protocol (OR=0.556, P=0.001), but the clinical pregnancy rate per transfer cycle and the live birth rate per transfer cycle significantly increased (OR=1.179, OR=1.169, both P<0.01) in both agonist and antagonist protocols. For safety, multiple analysis result demonstrated that in the agonist protocol, compared with rFSH group, the incidence of moderate to severe ovarian hyperstimulation syndrome of uFSH group significantly decreased (OR=0.644, P=0.002). The differences in ectopic pregnancy rate and multiple pregnancy rate between the uFSH and rFSH groups were not significant (P=0.890, P=0.470) in all patients. In terms of cost, compared with rFSH group, the uFSH group had lower total Gn costs for each patient (P<0.01). Conclusion: For patients who underwent COS, uFSH has better safety, and economic profiles over rFSH in China.

The Establishment of a Mouse Model for Degenerative Kyphoscoliosis Based on Senescence-Accelerated Mouse Prone 8

Objective

Degenerative kyphoscoliosis (DKS) is a complex spinal deformity associated with degeneration of bones, muscles, discs, and facet joints. The aim of this study was to establish an animal model of degenerative scoliosis that recapitulates key pathological features of DKS and to validate the degenerative changes in senescence-accelerated mouse prone 8 (SAMP8) mice.

Methods

Thirty male mice were divided into 2 groups: 10 bipedal C57BL/6J mice were used as the control group, and 20 bipedal SAMP8 mice were used as the experimental group. Mice were bipedalized under general anesthesia. The incidence of scoliosis and bone quality was determined using radiographs and in vivo micro-CT images 4, 8, and 12 weeks after surgery, respectively. Histomorphological studies of muscle samples were performed after sacrifice at 12 weeks after surgery.

Results

On the 12th week, the incidence rates of kyphosis in C57BL/6J and SAMP8 groups were 50% and 100%, respectively. Overall, the incidence and angle of kyphosis were significantly higher in the bipedal SAMP8 group compared to the C57BL/6J group (44.7°± 6.2° vs. 84.3°± 10.3°, P<0.001). Based on 3D reconstruction of the entire spine, degeneration of the intervertebral disc was observed in bipedal SAMP8 mice, including the reduction of disc height and the formation of vertebral osteophytes. The bone volume ratio (BV/TV) was significantly suppressed in the bipedal SAMP8 group compared with the bipedal C57BL/6J group. In addition, HE staining and Mason staining of the paraspinal muscle tissue showed chronic inflammation and fibrosis in the muscles of the bipedal SAMP8 group.

Conclusions

The SAMP8 mouse model can be taken as a clinically relevant model of DKS, and accelerated aging of the musculoskeletal system promotes the development of kyphosis.