Base-resolution m5C profiling across the mammalian transcriptome by bisulfite-free enzyme-assisted chemical labeling approach.

5-methylcytosine (m5C) is a prevalent RNA modification crucial for gene expression regulation. However, accurate and sensitive m5C sites identification remains challenging due to severe RNA degradation and reduced sequence complexity during bisulfite sequencing (BS-seq). Here, we report m5C-TAC-seq, a bisulfite-free approach combining TET-assisted m5C-to-f5C oxidation with selective chemical labeling, therefore enabling direct base-resolution m5C detection through pre-enrichment and C-to-T transitions at m5C sites. With m5C-TAC-seq, we comprehensively profiled the m5C methylomes in human and mouse cells, identifying a substantially larger number of confident m5C sites. Through perturbing potential m5C methyltransferases, we deciphered the responsible enzymes for most m5C sites, including the characterization of NSUN5's involvement in mRNA m5C deposition. Additionally, we characterized m5C dynamics during mESC differentiation. Notably, the mild reaction conditions and preservation of nucleotide composition in m5C-TAC-seq allow m5C detection in chromatin-associated RNAs. The accurate and robust m5C-TAC-seq will advance research into m5C methylation functional investigation.

De novo induction of intratumoral lymphoid structures and vessel normalization enhances immunotherapy in resistant tumors.

The tumor microenvironment confers profound resistance to anti-cancer immunotherapy. By targeting LIGHT, a member of the TNF superfamily of cytokines, to tumor vessels via a vascular targeting peptide (VTP), we developed a reagent with the dual ability to modulate the angiogenic vasculature and to induce tertiary lymphoid structures (TLSs). LIGHT-VTP triggered the influx of endogenous T cells into autochthonous or syngeneic tumors, which are resistant to immunotherapy. LIGHT-VTP in combination with checkpoint inhibition generated a large number of intratumoral effector and memory T cells with ensuing survival benefits, while the addition of anti-tumor vaccination achieved maximal therapeutic efficacy. Thus, the combination treatments stimulated the trafficking of pre-existing endogenous effector T cells as well as their intratumoral activation and were more successful than current immunotherapies, which fail due to tumor-intrinsic resistance mechanisms.

Design of robust superhydrophobic surfaces.

The ability of superhydrophobic surfaces to stay dry, self-clean and avoid biofouling is attractive for applications in biotechnology, medicine and heat transfer1-10. Water droplets that contact these surfaces must have large apparent contact angles (greater than 150 degrees) and small roll-off angles (less than 10 degrees). This can be realized for surfaces that have low-surface-energy chemistry and micro- or nanoscale surface roughness, minimizing contact between the liquid and the solid surface11-17. However, rough surfaces-for which only a small fraction of the overall area is in contact with the liquid-experience high local pressures under mechanical load, making them fragile and highly susceptible to abrasion18. Additionally, abrasion exposes underlying materials and may change the local nature of the surface from hydrophobic to hydrophilic19, resulting in the pinning of water droplets to the surface. It has therefore been assumed that mechanical robustness and water repellency are mutually exclusive surface properties. Here we show that robust superhydrophobicity can be realized by structuring surfaces at two different length scales, with a nanostructure design to provide water repellency and a microstructure design to provide durability. The microstructure is an interconnected surface frame containing 'pockets' that house highly water-repellent and mechanically fragile nanostructures. This surface frame acts as 'armour', preventing the removal of the nanostructures by abradants that are larger than the frame size. We apply this strategy to various substrates-including silicon, ceramic, metal and transparent glass-and show that the water repellency of the resulting superhydrophobic surfaces is preserved even after abrasion by sandpaper and by a sharp steel blade. We suggest that this transparent, mechanically robust, self-cleaning glass could help to negate the dust-contamination issue that leads to a loss of efficiency in solar cells. Our design strategy could also guide the development of other materials that need to retain effective self-cleaning, anti-fouling or heat-transfer abilities in harsh operating environments.

Serine starvation silences estrogen receptor signaling through histone hypoacetylation.

Loss of estrogen receptor (ER) pathway activity promotes breast cancer progression, yet how this occurs remains poorly understood. Here, we show that serine starvation, a metabolic stress often found in breast cancer, represses estrogen receptor alpha (ERα) signaling by reprogramming glucose metabolism and epigenetics. Using isotope tracing and time-resolved metabolomic analyses, we demonstrate that serine is required to maintain glucose flux through glycolysis and the TCA cycle to support acetyl-CoA generation for histone acetylation. Consequently, limiting serine depletes histone H3 lysine 27 acetylation (H3K27ac), particularly at the promoter region of ER pathway genes including the gene encoding ERα, ESR1. Mechanistically, serine starvation impairs acetyl-CoA-dependent gene expression by inhibiting the entry of glycolytic carbon into the TCA cycle and down-regulating the mitochondrial citrate exporter SLC25A1, a critical enzyme in the production of nucleocytosolic acetyl-CoA from glucose. Consistent with this model, total H3K27ac and ERα expression are suppressed by SLC25A1 inhibition and restored by acetate, an alternate source of acetyl-CoA, in serine-free conditions. We thus uncover an unexpected role for serine in sustaining ER signaling through the regulation of acetyl-CoA metabolism.

Enhanced SLC35B2/SAV1 sulfation axis promotes tumor growth by inhibiting Hippo signaling in HCC.

BACKGROUND AND AIMS: Protein tyrosine sulfation (PTS) is a common posttranslational modification that regulates a variety of physiological and pathological processes. However, the role of PTS in cancer remains poorly understood. The goal of this study was to determine whether and how PTS plays a role in HCC progression. APPROACH AND RESULTS: By mass spectrometry and bioinformatics analysis, we identified SAV1 as a novel substrate of PTS in HCC. Oxidative stress upregulates the transcription of SLC35B2, a Golgi-resident transporter of sulfate donor 3'-phosphoadenosine 5'-phosphosulfate, leading to increased sulfation of SAV1. Sulfation of SAV1 disrupts the formation of the SAV1-MST1 complex, resulting in a decrease of MST1 phosphorylation and subsequent inactivation of Hippo signaling. These molecular events ultimately foster the growth of HCC cells both in vivo and in vitro. Moreover, SLC35B2 is a novel transcription target gene of the Hippo pathway, constituting a positive feedback loop that facilitates HCC progression under oxidative stress. CONCLUSIONS: Our findings reveal a regulatory mechanism of the SLC35B2/SAV1 sulfation axis in response to oxidative stress, highlighting its potential as a promising therapeutic target for HCC.

METTL3 protects METTL14 from STUB1-mediated degradation to maintain m6 A homeostasis.

N6 -Methyladenosine (m6 A) is an important RNA modification catalyzed by methyltransferase-like 3 (METTL3) and METTL14. m6 A homeostasis mediated by the methyltransferase (MTase) complex plays key roles in various biological processes. However, the mechanism underlying METTL14 protein stability and its role in m6 A homeostasis remain elusive. Here, we show that METTL14 stability is regulated by the competitive interaction of METTL3 with the E3 ligase STUB1. STUB1 directly interacts with METTL14 to mediate its ubiquitination at lysine residues K148, K156, and K162 for subsequent degradation, resulting in a significant decrease in total m6 A levels. The amino acid regions 450-454 and 464-480 of METTL3 are essential to promote METTL14 stabilization. Changes in STUB1 expression affect METTL14 protein levels, m6 A modification and tumorigenesis. Collectively, our findings uncover an ubiquitination mechanism controlling METTL14 protein levels to fine-tune m6 A homeostasis. Finally, we present evidence that modulating STUB1 expression to degrade METTL14 could represent a promising therapeutic strategy against cancer.

YLC-assembly: large DNA assembly via yeast life cycle.

As an enabling technique of synthetic biology, the scale of DNA assembly largely determines the scale of genetic manipulation. However, large DNA assembly technologies are generally cumbersome and inefficient. Here, we developed a YLC (yeast life cycle)-assembly method that enables in vivo iterative assembly of large DNA by nesting cell-cell transfer of assembled DNA in the cycle of yeast mating and sporulation. Using this method, we successfully assembled a hundred-kilobase (kb)-sized endogenous yeast DNA and a megabase (Mb)-sized exogenous DNA. For each round, over 104 positive colonies per 107 cells could be obtained, with an accuracy ranging from 67% to 100%. Compared with other Mb-sized DNA assembly methods, this method exhibits a higher success rate with an easy-to-operate workflow that avoid in vitro operations of large DNA. YLC-assembly lowers the technical difficulty of Mb-sized DNA assembly and could be a valuable tool for large-scale genome engineering and synthetic genomics.

Quantitative, in situ visualization of intracellular insulin vesicles in pancreatic beta cells.

Characterizing relationships between Zn2+, insulin, and insulin vesicles is of vital importance to the study of pancreatic beta cells. However, the precise content of Zn2+ and the specific location of insulin inside insulin vesicles are not clear, which hinders a thorough understanding of the insulin secretion process and diseases caused by blood sugar dysregulation. Here, we demonstrated the colocalization of Zn2+ and insulin in both single extracellular insulin vesicles and pancreatic beta cells by using an X-ray scanning coherent diffraction imaging (ptychography) technique. We also analyzed the elemental Zn2+ and Ca2+ contents of insulin vesicles using electron microscopy and energy dispersive spectroscopy (EDS) mapping. We found that the presence of Zn2+ is an important characteristic that can be used to distinguish insulin vesicles from other types of vesicles in pancreatic beta cells and that the content of Zn2+ is proportional to the size of insulin vesicles. By using dual-energy contrast X-ray microscopy and scanning transmission X-ray microscopy (STXM) image stacks, we observed that insulin accumulates in the off-center position of extracellular insulin vesicles. Furthermore, the spatial distribution of insulin vesicles and their colocalization with other organelles inside pancreatic beta cells were demonstrated using three-dimensional (3D) imaging by combining X-ray ptychography and an equally sloped tomography (EST) algorithm. This study describes a powerful method to univocally describe the location and quantitative analysis of intracellular insulin, which will be of great significance to the study of diabetes and other blood sugar diseases.

RNA 2'-O-methylation promotes persistent R-loop formation and AID-mediated IgH class switch recombination.

BACKGROUND: RNA-DNA hybrids or R-loops are associated with deleterious genomic instability and protective immunoglobulin class switch recombination (CSR). However, the underlying phenomenon regulating the two contrasting functions of R-loops is unknown. Notably, the underlying mechanism that protects R-loops from classic RNase H-mediated digestion thereby promoting persistence of CSR-associated R-loops during CSR remains elusive. RESULTS: Here, we report that during CSR, R-loops formed at the immunoglobulin heavy (IgH) chain are modified by ribose 2'-O-methylation (2'-OMe). Moreover, we find that 2'-O-methyltransferase fibrillarin (FBL) interacts with activation-induced cytidine deaminase (AID) associated snoRNA aSNORD1C to facilitate the 2'-OMe. Moreover, deleting AID C-terminal tail impairs its association with aSNORD1C and FBL. Disrupting FBL, AID or aSNORD1C expression severely impairs 2'-OMe, R-loop stability and CSR. Surprisingly, FBL, AID's interaction partner and aSNORD1C promoted AID targeting to the IgH locus. CONCLUSION: Taken together, our results suggest that 2'-OMe stabilizes IgH-associated R-loops to enable productive CSR. These results would shed light on AID-mediated CSR and explain the mechanism of R-loop-associated genomic instability.

Targeted ablation of the left middle cervical ganglion prevents ventricular arrhythmias and cardiac injury induced by AMI.

Cardiac sympathetic overactivation is a critical driver in the progression of acute myocardial infarction (AMI). The left middle cervical ganglion (LMCG) is an important extracardiac sympathetic ganglion. However, the regulatory effects of LMCG on AMI have not yet been fully documented. In the present study, we detected that the LMCG was innervated by abundant sympathetic components and exerted an excitatory effect on the cardiac sympathetic nervous system in response to stimulation. In canine models of AMI, targeted ablation of LMCG reduced the sympathetic indexes of heart rate variability and serum norepinephrine, resulting in suppressed cardiac sympathetic activity. Moreover, LMCG ablation could improve ventricular electrophysiological stability, evidenced by the prolonged ventricular effective refractory period, elevated action potential duration, increased ventricular fibrillation threshold, and enhanced connexin43 expression, consequently showing antiarrhythmic effects. Additionally, compared with the control group, myocardial infarction size, circulating cardiac troponin I, and myocardial apoptosis were significantly reduced, accompanied by preserved cardiac function in canines subjected to LMCG ablation. Finally, we performed the left stellate ganglion (LSG) ablation and compared its effects with LMCG destruction. The results indicated that LMCG ablation prevented ventricular electrophysiological instability, cardiac sympathetic activation, and AMI-induced ventricular arrhythmias with similar efficiency as LSG denervation. In conclusion, this study demonstrated that LMCG ablation suppressed cardiac sympathetic activity, stabilized ventricular electrophysiological properties and mitigated cardiomyocyte death, resultantly preventing ischemia-induced ventricular arrhythmias, myocardial injury, and cardiac dysfunction. Neuromodulation therapy targeting LMCG represented a promising strategy for the treatment of AMI.

Dexamethasone exposure during pregnancy triggers metabolic syndrome in offspring via epigenetic alteration of IGF1.

BACKGROUND: Previous research has reported that prenatal exposure to dexamethasone (PDE) results in organ dysplasia and increased disease susceptibility in offspring. This study aimed to investigate the epigenetic mechanism of metabolic syndrome induced by PDE in offspring. METHODS: Pregnant Wistar rats were administered dexamethasone, and their offspring's serum and liver tissues were analyzed. The hepatocyte differentiation model was established to unveil the molecular mechanism. Neonatal cord blood samples were collected to validate the phenomenon and mechanism. RESULTS: The findings demonstrated that PDE leads to insulin resistance and typical metabolic syndrome traits in adult offspring rats, which originated from fetal liver dysplasia. Additionally, PDE reduced serum corticosterone level and inhibited hepatic insulin-like growth factor 1 (IGF1) signaling in fetal rats. It further revealed that liver dysplasia and functional impairment induced by PDE persist after birth, driven by the continuous downregulation of serum corticosterone and hepatic IGF1 signaling. Both in vitro and in vivo experiments confirmed that low endogenous corticosterone reduces the histone 3 lysine 9 acetylation (H3K27ac) level of IGF1 and its expression by blocking glucocorticoid receptor α, special protein 1, and P300 into the nucleus, resulting in hepatocyte differentiation inhibition and liver dysplasia. Intriguingly, neonatal cord blood samples validated the link between reduced liver function in neonates induced by PDE and decreased serum cortisol and IGF1 levels. CONCLUSIONS: This study demonstrated that low endogenous glucocorticoid level under PDE lead to liver dysplasia by downregulating the H3K27ac level of IGF1 and its expression, ultimately contributing to metabolic syndrome in adult offspring.

Importance of habitat heterogeneity in tidal flats to the conservation of migratory shorebirds.

Understanding species distribution patterns and what determines them is critical for effective conservation planning and management. In the case of shorebirds migrating along the East Asian-Australasian Flyway (EAAF), the loss of stopover habitat in the Yellow Sea region is thought to be the primary reason for the precipitous population declines. However, the rates of decline vary considerably among species, and it remains unclear how such differences could arise within a group of closely related species using apparently similar habitats at the same locales. We mapped the spatial distributions of foraging shorebirds, as well as biotic (benthic invertebrates consumed by migrating shorebirds) and abiotic (sediment characteristics) environmental factors, at a key stopover site in eastern China. Five of the six sediment characteristics showed significant spatial variation with respect to distance along the shoreline or distance from the seawall in the same tidal flat. The biomasses of four of the six most abundant benthic invertebrates were concentrated in the upper or middle zones of the tidal flat. The distribution patterns of all three focal shorebird species on the tidal flat were best explained jointly by this heterogeneity of sediment characteristics and invertebrate prey. These results suggest that the loss of tidal flats along the Yellow Sea, which is typically concentrated at the upper and middle zones, may not only reduce the overall amount of staging habitat, but also disproportionately affect the most resource-rich portions for the birds. Effective conservation of shorebird staging areas along the EAAF and likely elsewhere must consider the subtle habitat heterogeneity that characterizes these tidal flats, prioritizing the protection of those portions richest in food resources, most frequently used by focal bird species, and most vulnerable to anthropogenic threats. Article impact statement: Heterogeneity of tidal flats with respect to biotic and abiotic factors must be considered in shorebird conservation planning.

Importancia de la heterogeneidad de hábitat en las llanuras intermareales para la conservación de aves playeras migratorias Resumen Entender las pautas de distribución de las especies y los factores que las determinan es fundamental para planificar y gestionar eficazmente su conservación. En el caso de las aves playeras que migran a lo largo de la ruta migratoria Asia Oriental-Australasia (EAAF, en inglés), se cree que la pérdida de puntos de parada en la región del Mar Amarillo es la razón principal de la declinación poblacional precipitada. Sin embargo, las tasas de declinación varían considerablemente entre especies, y sigue sin estar claro cómo pueden surgir tales diferencias dentro de un grupo de especies emparentadas que utilizan hábitats aparentemente similares en los mismos lugares. Mapeamos las distribuciones espaciales de las aves playeras forrajeras, así como los factores ambientales bióticos (invertebrados bénticos consumidos por las aves playeras migratorias) y abióticos (características de los sedimentos), en un punto de parada clave en el este de China. Cinco de las seis características de los sedimentos mostraron una variación espacial significativa con respecto a los cambios lineales en la distancia a lo largo de la costa o la distancia desde el malecón en la misma llanura mareal. La biomasa de cuatro de los seis invertebrados bénticos más abundantes se concentró en las zonas superior o media de la llanura mareal. Esta heterogeneidad de las características de los sedimentos y de las presas invertebradas es la que mejor explica los patrones de distribución de las tres especies de aves playeras en la llanura mareal. Estos resultados sugieren que la pérdida de llanuras mareales a lo largo del Mar Amarillo, que suele concentrarse en las zonas superior y media, puede no sólo reducir la cantidad total de hábitat de parada, sino también afectar de manera desproporcionada a las partes más ricas en recursos para las aves. La conservación eficaz de los puntos de parada de las aves playeras a lo largo del EAAF, y probablemente en otros lugares, debe tener en cuenta la sutil heterogeneidad del hábitat que caracteriza a estas llanuras mareales, priorizando la protección de las partes más ricas en recursos alimenticios, más frecuentemente utilizadas por las especies de aves focales y más vulnerables a las amenazas antropogénicas.

Left ventricular strain changes at high altitude in rats: a cardiac magnetic resonance tissue tracking imaging study.

BACKGROUND: Long-term exposure to a high altitude environment with low pressure and low oxygen could cause abnormalities in the structure and function of the heart. Myocardial strain is a sensitive indicator for assessing myocardial dysfunction, monitoring myocardial strain is of great significance for the early diagnosis and treatment of high altitude heart-related diseases. This study applies cardiac magnetic resonance tissue tracking technology (CMR-TT) to evaluate the changes in left ventricular myocardial function and structure in rats in high altitude environment. METHODS: 6-week-old male rats were randomized into plateau hypoxia rats (plateau group, n = 21) as the experimental group and plain rats (plain group, n = 10) as the control group. plateau group rats were transported from Chengdu (altitude: 360 m), a city in a plateau located in southwestern China, to the Qinghai-Tibet Plateau (altitude: 3850 m), Yushu, China, and then fed for 12 weeks there, while plain group rats were fed in Chengdu(altitude: 360 m), China. Using 7.0 T cardiac magnetic resonance (CMR) to evaluate the left ventricular ejection fraction (EF), end-diastolic volume (EDV), end-systolic volume (ESV) and stroke volume (SV), as well as myocardial strain parameters including the peak global longitudinal (GLS), radial (GRS), and circumferential strain (GCS). The rats were euthanized and a myocardial biopsy was obtained after the magnetic resonance imaging scan. RESULTS: The plateau rats showed more lower left ventricular GLS and GRS (P < 0.05) than the plain rats. However, there was no statistically significant difference in left ventricular EDV, ESV, SV, EF and GCS compared to the plain rats (P > 0.05). CONCLUSIONS: After 12 weeks of exposure to high altitude low-pressure hypoxia environment, the left ventricular global strain was partially decreased and myocardium is damaged, while the whole heart ejection fraction was still preserved, the myocardial strain was more sensitive than the ejection fraction in monitoring cardiac function.

Numerical methods for hemolysis and thrombus evaluation in the percutaneous ventricular assist device.

BACKGROUND: A percutaneous ventricular assist device (pVAD) is an effective method to treat heart failure, but its complications, mainly hemolysis and thrombus formation, cannot be ignored. Accurate evaluation of hemolysis and thrombus formation in pVAD is essential to guide the development of pVAD and reduce the incidence of complications. METHODS: This study optimized the numerical model to predict hemolysis and thrombus formation in pVAD. The hemolysis model is based on the power law function, and the multi-component thrombus prediction model is improved by introducing the von Willebrand factor. RESULTS: The error between the numerical simulation and the hydraulic performance experiment is within 5%. The numerical results of hemolysis are in good agreement with those of in vitro experiments. Meanwhile, the thrombus location predicted by the numerical model is the same as that found in the in vivo experiment. CONCLUSION: The numerical model suggested in this study may therefore accurately assess the possible hemolytic and thrombotic dangers in pVAD, making it an effective tool to support the development of pVAD.

Bone metastases among newly diagnosed cancer patients: a population-based study.

PURPOSE: (i) To analyze age-adjusted incidence rates of synchronous bone metastases diagnosed alongside primary malignancy from 2010 to 2018 in the US population, (ii) determine the incidence proportions (IPs) and characteristics of synchronous bone metastases among newly diagnosed cancer patients in the USA especially pediatric cases, and (iii) assess the implications of synchronous bone metastases on cancer patient's survival, and identify the survival risk factors for these cancer patients. METHODS: Utilizing data from the Surveillance, Epidemiology, and End Results (SEER) program (2010-2018), we calculated age-adjusted IPs and annual percentage change (APC), and employed logistic regression and Cox regression models for our analysis. RESULTS: 3 300 736 cancer patients were identified. The age-adjusted incidence rates of synchronous bone metastases increased from 2010 (18.04/100 000) to 2018 (20.89/100 000; APC: 2.3, 95% confidence interval [CI], 1.4-3.1), but decreased in lung cancer (average APC: -1.0, 95% CI, -1.8 to -0.3). The highest IPs were observed in pediatric neuroblastoma (43.2%; 95% CI, 39.8%-46.7%) and adult small cell carcinoma (23.1%; 95% CI, 22.7%-23.4%). Multivariate logistic analyses revealed that primary tumor characteristics were correlated with higher bone metastases risk. Survival analyses also showed varied prognostic outcomes based on metastasis sites and demographics among cancer patients. Landmark analyses further indicated among long-term cancer survivors (≥3 and ≥5 years), patients with de novo bone metastases had the poorest survival rates compared with those with other synchronous metastases (P < 0.001). CONCLUSION: This study provides a population-based estimation of the incidence and prognosis for synchronous bone metastases. Our findings highlight the need for early identification of high-risk groups and multidisciplinary approaches to improve prognosis of cancer patients with de novo bone metastases.

Vertebral bone quality score was associated with paraspinal muscles fat infiltration, but not modic classification in patients with chronic low back pain: a prospective cross-sectional study.

BACKGROUND: The lumbar vertebra and paraspinal muscles play an important role in maintaining the stability of the lumbar spine. Therefore, the aim of this study was to investigate the relationship between paraspinal muscles fat infiltration and vertebral body related changes [vertebral bone quality (VBQ) score and Modic changes (MCs)] in patients with chronic low back pain (CLBP). METHODS: Patients with CLBP were prospectively collected in four hospitals and all patients underwent 3.0T magnetic resonance scanning. Basic clinical information was collected, including age, sex, course of disease (COD), and body mass index (BMI). MCs were divided into 3 types based on their signal intensity on T1 and T2-weighted imaging. VBQ was obtained by midsagittal T1-weighted imaging (T1WI) and calculated using the formula: SIL1-4/SICSF. The Proton density fat fraction (PDFF) values and cross-sectional area (CSA) of paraspinal muscles were measured on the fat fraction map from the iterative decomposition of water and fat with the echo asymmetry and least-squares estimation quantitation (IDEAL-IQ) sequences and in/out phase images at the central level of the L4/5 and L5/S1 discs. RESULTS: This study included 476 patients with CLBP, including 189 males and 287 females. 69% had no Modic changes and 31% had Modic changes. There was no difference in CSA and PDFF for multifidus(MF) and erector spinae (ES) at both levels between Modic type I and type II, all P values>0.05. Spearman correlation analysis showed that VBQ was weakly negatively correlated with paraspinal muscles CSA (all r values < 0.3 and all p values < 0.05), moderately positive correlation with PDFF of MF at L4/5 level (r values = 0.304, p values<0.001) and weakly positively correlated with PDFF of other muscles (all r values<0.3 and all p values<0.001). Multivariate linear regression analysis showed that age (ß = 0.141, p < 0.001), gender (ß = 4.285, p < 0.001) and VBQ (ß = 1.310, p = 0.001) were related to the total PDFF of muscles. For MCs, binary logistic regression showed that the odds ratio values of age, BMI and COD were 1.092, 1.082 and 1.004, respectively (all p values ＜ 0.05). CONCLUSIONS: PDFF of paraspinal muscles was not associated with Modic classification. In addition to age and gender, PDFF of paraspinal muscles is also affected by VBQ. Age and BMI are considered risk factors for the MCs in CLBP patients.

Diffusion-tensor magnetic resonance imaging as a non-invasive assessment of extracellular matrix remodeling in lumbar paravertebral muscles of rats with sarcopenia.

BACKGROUND: Extracellular matrix (ECM) remodeling in skeletal muscle is a significant factor in the development of sarcopenia. This study aims to evaluate changes in ECM remodeling in the lumbar paravertebral muscles of sarcopenic rats using diffusion-tensor magnetic resonance imaging (DT-MRI) and compare them with histology. METHODS: Twenty 6-month-old female Sprague Dawley rats were randomly divided into the dexamethasone (DEX) group and the control (CON) group. Both groups underwent 3.0T MRI scanning, including Mensa, T2WI, and DT-MRI sequences. The changes in muscle fibers and extracellular matrix (ECM) of the erector spinal muscle were observed using hematoxylineosin and sirius red staining. The expressions of collagen I, III, and fibronectin in the erector spinae were detected by western blot. Pearson correlation analysis was employed to assess the correlation between MRI quantitative parameters and corresponding histopathology markers. RESULTS: The cross-sectional area and fractional anisotropy values of the erector spinae in the DEX group rats were significantly lower than those in the CON group (p < 0.05). Hematoxylin eosin staining revealed muscle fiber atrophy and disordered arrangement in the DEX group, while sirius red staining showed a significant increase in collagen volume fraction in the DEX group. The western blot results indicate a significant increase in the expression of collagen I, collagen III, and fibronectin in the DEX group (p < 0.001 for all). Correlation coefficients between fractional anisotropy values and collagen volume fraction, collagen I, collagen III, and fibronectin were - 0.71, -0.94, -0.85, and - 0.88, respectively (p < 0.05 for all). CONCLUSIONS: The fractional anisotropy value is strongly correlated with the pathological collagen volume fraction, collagen I, collagen III, and fibronectin. This indicates that DT-MRI can non-invasively evaluate the changes in extracellular matrix remodeling in the erector spinal muscle of sarcopenia. It provides a potential imaging biomarker for the diagnosis of sarcopenia.

Association of MRI findings with paraspinal muscles fat infiltration at lower lumbar levels in patients with chronic low back pain: a multicenter prospective study.

OBJECTIVE: In chronic low back pain (CLBP), the relationship between spinal pathologies and paraspinal muscles fat infiltration remains unclear. This study aims to evaluate the relationship between MRI findings and paraspinal muscles morphology and fat infiltration in CLBP patients by quantitative MRI. METHODS: All the CLBP patients were enrolled from July 2021 to December 2022 in four medical institutions. The cross-sectional area (CSA) and proton density fat fraction (PDFF) of the multifidus (MF) and erector spinae (ES) muscles at the central level of the L4/5 and L5/S1 intervertebral discs were measured. MRI findings included degenerative lumbar spondylolisthesis (DLS), intervertebral disc degeneration (IVDD), facet arthrosis, disc bulge or herniation, and disease duration. The relationship between MRI findings and the paraspinal muscles PDFF and CSA in CLBP patients was analyzed. RESULTS: A total of 493 CLBP patients were included in the study (198 females, 295 males), with an average age of 45.68 ± 12.91 years. Our research indicates that the number of MRI findings are correlated with the paraspinal muscles PDFF at the L4/5 level, but is not significant. Moreover, the grading of IVDD is the primary factor influencing the paraspinal muscles PDFF at the L4-S1 level (BES at L4/5=1.845, P < 0.05); DLS was a significant factor affecting the PDFF of MF at the L4/5 level (B = 4.774, P < 0.05). After including age, gender, and Body Mass Index (BMI) as control variables in the multivariable regression analysis, age has a significant positive impact on the paraspinal muscles PDFF at the L4-S1 level, with the largest AUC for ES PDFF at the L4/5 level (AUC = 0.646, cut-off value = 47.5), while males have lower PDFF compared to females. BMI has a positive impact on the ES PDFF only at the L4/5 level (AUC = 0.559, cut-off value = 24.535). CONCLUSION: The degree of paraspinal muscles fat infiltration in CLBP patients is related to the cumulative or synergistic effects of multiple factors, especially at the L4/L5 level. Although age and BMI are important factors affecting the degree of paraspinal muscles PDFF in CLBP patients, their diagnostic efficacy is moderate.

20(R)-ginsenoside Rg3 attenuates cerebral ischemia-reperfusion injury by mitigating mitochondrial oxidative stress via the Nrf2/HO-1 signaling pathway.

Reducing mitochondrial oxidative stress has become an important strategy to prevent neuronal death in ischemic stroke. Previous studies have shown that 20(R)-ginsenoside Rg3 can significantly improve behavioral abnormalities, reduce infarct size, and decrease the number of apoptotic neurons in cerebral ischemia/reperfusion injury rats. However, it remains unclear whether 20(R)-ginsenoside Rg3 can inhibit mitochondrial oxidative stress in ischemic stroke and the potential molecular mechanism. In this study, we found that 20(R)-ginsenoside Rg3 notably inhibited mitochondrial oxidative stress in middle cerebral artery occlusion/reperfusion (MCAO/R) rats and maintained the stability of mitochondrial structure and function. Treatment with 20(R)-ginsenoside Rg3 also decreased the levels of mitochondrial fission proteins (Drp1 and Fis1) and increased the levels of fusion proteins (Opa1, Mfn1, and Mfn2) in MCAO/R rats. Furthermore, we found that 20(R)-ginsenoside Rg3 promoted nuclear aggregation of nuclear factor erythroid2-related factor 2 (Nrf2) but did not affect Kelch-like ECH-associated protein-1 (Keap1), resulting in the downstream expression of antioxidants. In in vitro oxygen-glucose deprivation/reperfusion stroke models, the results of PC12 cells treated with 20(R)-ginsenoside Rg3 were consistent with animal experiments. After transfection with Nrf2 short interfering RNA (siRNA), the protective effect of 20(R)-ginsenoside Rg3 on PC12 cells was reversed. In conclusion, the inhibition of mitochondrial oxidative stress plays a vital position in the anti-cerebral ischemia-reperfusion injury of 20(R)-ginsenoside Rg3, and its neuroprotective mechanism is related to the activation of the nuclear factor erythroid2-related factor 2/heme oxygenase 1 signaling pathway.

The Duration of Hardware Retention After Radiologic Union of Surgically Treated Femoral Neck Fractures in Children May Predict the Aggravation or Occurrence of Avascular Necrosis of the Femoral Head or Neck After Hardware Removal.

BACKGROUND: The incidence of aggravation or occurrence of avascular necrosis (AVN) following hardware removal in surgically treated pediatric femoral neck fractures who achieved radiologic consolidation is unknown. This study aimed to investigate the risk factors for this complication. METHODS: Seventy-one pediatric (mean age: 9.8±3.9 y) were retrospectively analyzed. Risk factors (age, sex, laterality, severity of initial displacement, type of fracture, time from trauma to reduction, reduction and fixation method, quality of reduction, time required to achieve radiologic union, duration of hardware retention, presence of AVN before hardware removal and follow-up time) were recorded. The severity of AVN was assessed based on radiographs with Ratliff's classification. RESULTS: Following hardware removal, the aggravation/occurrence of AVN was detected in 11 hips (15.5%). Among the 5 hips (7%) with aggravation of AVN, 1 (1.4%) with type II AVN and 3 (4.2%) with type III AVN exhibited aggravation of type I AVN, while the remaining hip (1.4%; type I) showed enlargement of the involved AVN area. Six hips (8.5%) developed AVN following hardware removal: 2 (2.8%) were classified as type I and 4 (5.6%) as type III. Receiver operating characteristic curve analysis indicated that hardware retention >7 months after union is associated with a decreased rate of aggravation or occurrence of AVN of the femoral neck or head following hardware removal. CONCLUSIONS: The incidence of aggravation or occurrence of AVN following hardware removal in surgically treated pediatric femoral neck fractures is 15.5%; hardware retention >7 months after radiologic union may reduce the risk of aggravation or occurrence of AVN of the femoral neck or head postimplant removal. LEVEL OF EVIDENCE: Level III.