Mechanosensitive protein polycystin-1 promotes periosteal stem/progenitor cells osteochondral differentiation in fracture healing

Background: Mechanical forces are indispensable for bone healing, disruption of which is recognized as a contributing cause to nonunion or delayed union. However, the underlying mechanism of mechanical regulation of fracture healing is elusive. Methods: We used the lineage-tracing mouse model, conditional knockout depletion mouse model, hindlimb unloading model and single-cell RNA sequencing to analyze the crucial roles of mechanosensitive protein polycystin-1 (PC1, Pkd1) promotes periosteal stem/progenitor cells (PSPCs) osteochondral differentiation in fracture healing. Results: Our results showed that cathepsin (Ctsk)-positive PSPCs are fracture-responsive and mechanosensitive and can differentiate into osteoblasts and chondrocytes during fracture repair. We found that polycystin-1 declines markedly in PSPCs with mechanical unloading while increasing in response to mechanical stimulus. Mice with conditional depletion of Pkd1 in Ctsk+ PSPCs show impaired osteochondrogenesis, reduced cortical bone formation, delayed fracture healing, and diminished responsiveness to mechanical unloading. Mechanistically, PC1 facilitates nuclear translocation of transcriptional coactivator TAZ via PC1 C-terminal tail cleavage, enhancing osteochondral differentiation potential of PSPCs. Pharmacological intervention of the PC1-TAZ axis and promotion of TAZ nuclear translocation using Zinc01442821 enhances fracture healing and alleviates delayed union or nonunion induced by mechanical unloading. Conclusion: Our study reveals that Ctsk+ PSPCs within the callus can sense mechanical forces through the PC1-TAZ axis, targeting which represents great therapeutic potential for delayed fracture union or nonunion.

Age-related secretion of grancalcin by macrophages induces skeletal stem/progenitor cell senescence during fracture healing

Skeletal stem/progenitor cell (SSPC) senescence is a major cause of decreased bone regenerative potential with aging, but the causes of SSPC senescence remain unclear. In this study, we revealed that macrophages in calluses secrete prosenescent factors, including grancalcin (GCA), during aging, which triggers SSPC senescence and impairs fracture healing. Local injection of human rGCA in young mice induced SSPC senescence and delayed fracture repair. Genetic deletion of Gca in monocytes/macrophages was sufficient to rejuvenate fracture repair in aged mice and alleviate SSPC senescence. Mechanistically, GCA binds to the plexin-B2 receptor and activates Arg2-mediated mitochondrial dysfunction, resulting in cellular senescence. Depletion of Plxnb2 in SSPCs impaired fracture healing. Administration of GCA-neutralizing antibody enhanced fracture healing in aged mice. Thus, our study revealed that senescent macrophages within calluses secrete GCA to trigger SSPC secondary senescence, and GCA neutralization represents a promising therapy for nonunion or delayed union in elderly individuals.

miR-188-3p targets skeletal endothelium coupling of angiogenesis and osteogenesis during ageing

A specific bone capillary subtype, namely type H vessels, with high expression of CD31 and endomucin, was shown to couple angiogenesis and osteogenesis recently. The number of type H vessels in bone tissue declines with age, and the underlying mechanism for this reduction is unclear. Here, we report that microRNA-188-3p (miR-188-3p) involves this process. miRNA-188-3p expression is upregulated in skeletal endothelium and negatively regulates the formation of type H vessels during ageing. Mice with depletion of miR-188 showed an alleviated age-related decline in type H vessels. In contrast, endothelial-specific overexpression of miR-188-3p reduced the number of type H vessels, leading to decreased bone mass and delayed bone regeneration. Mechanistically, we found that miR-188 inhibits type H vessel formation by directly targeting integrin β3 in endothelial cells. Our findings indicate that miR-188-3p is a key regulator of type H vessel formation and may be a potential therapeutic target for preventing bone loss and accelerating bone regeneration.

Sodium Valproate Combined With Topiramate vs. Sodium Valproate Alone for Refractory Epilepsy: A Systematic Review and Meta-Analysis

Background: Among antiepileptic drugs (AEDs), sodium valproate alone or in the combination of topiramate (TPM) for treating refractory epilepsy was controversial. This meta-analysis aimed to systematically evaluate the clinical effects of these two regimens in this population. Methods: Relevant studies up to August 2021 were identified through systematic searches of CNKI, Wanfang, PubMed, and Embase databases. We assessed the effectiveness and the frequency of absence seizures, atonic seizures, and tonic-clonic seizures. The included literature's risk of bias was evaluated using the Cochrane Collaboration's Risk of Bias tool. Sensitivity analysis was conducted to confirm the results' stability. STATA 15.0 was utilized for all pooled analyses in the included studies. Results: Totally 10 articles were determined for our meta-analysis, involving 976 patients with epilepsy in total (combined group, n = 488; monotherapy group, n = 488). The results of this meta-analysis indicated that the total effective rate of sodium valproate combined with TPM was higher than that of sodium valproate alone (random-effect model: OR = 3.52; 95% CI 1.47 to 8.47; p < 0.001; I ² = 73.8%). The frequency of absence seizures in the combined group was lower (fixed-effect model: WMD = -6.02; 95% CI -6.50 to -5.54; I ² = 0.0%) than that in the monotherapy group, with a statistical difference (p < 0.05). The combined group had lower frequency of atonic seizures (WMD = -4.56, 95% CI -6.02 to -3.10; I ² = 82.6%) and lower frequency of tonic-clonic seizures (WMD = -3.32; 95% CI -4.75 to -1.89; I ² = 96.4%). In addition, the distinct difference of adverse events was non-existent between two groups. Conclusions: Sodium valproate combined with TPM was more effective than sodium valproate alone for epilepsy therapy. This meta-analysis provides feasibility data for a larger-scale study on AED therapy of refractory epilepsy and may contribute to better therapy strategies for epilepsy clinically.

Combination therapy with beraprost sodium and aspirin for acute ischemic stroke: a single-center retrospective study

OBJECTIVES

To evaluate the effectiveness and safety of the combination of beraprost sodium (BPS) and aspirin in patients with acute ischemic stroke (AIS).

METHODS

There were 384 patients with AIS enrolled in this single-center, retrospective study. The BPS group comprised patients who received combination therapy with BPS and aspirin, and the control group comprised those who received only aspirin. Primary measurements were glomerular filtration rate (GFR), cystatin-c (Cys-C), National Institute of Health Stroke Scale (NIHSS) score, modified activities of daily living index (MBI), modified Rankin scale (mRS), and blood coagulation indexes. Recurrence and adverse events were recorded.

RESULTS

There were no significant differences in patient characteristics at baseline between the two groups. GFR and Cys-C levels increased in the BPS group compared with the control group. After treatment, the NIHSS and mRS score were significantly lower in the BPS group compared with the control group, whereas the MBI scores were significantly higher in the BPS group compared with the control group. There was no significant difference in blood coagulation between the two groups. There were no serious adverse events in either group.

CONCLUSIONS

Combination therapy with BPS and aspirin may be a safe and effective treatment for AIS.

[Genetic Polymorphisms of SNP Located in the 5' Region of VEGF Gene in Han Population in Guangdong]

OBJECTIVES

To investigate the genetic polymorphism of SNP located in the 5' region of the vascular endothelial growth factor （VEGF） gene in Han population in Guangdong and provide basic data for forensic application and population genetics research.

METHODS

The genetic polymorphisms of 4 SNP loci （rs699947, rs1570360, rs833061, rs2010963） within 5' region of VEGF gene of 184 unrelated individuals in Han population in Guangdong were analyzed by DNA micro sequencing technology SNaPshot. The statistical analysis was carried out by PowerMarker v3.25 software.

RESULTS

The genotype distributions of the 4 SNP loci within 5' region of VEGF gene of 184 unrelated individuals in Han population in Guangdong were in accordance with Hardy-Weinberg equilibrium （P>0.05） and 3 kinds of genotypes were detected from each loci. There was high linkage disequilibrium between the rs833061 and rs699947 SNP loci. Six haplotypes were observed, while the frequency of C-G-T-C, C-G-T-G, A-A-C-G and A-G-C-G were more than 10%, which were the main haplotypes. The discrimination probabilities （DP） of rs699947, rs833061, and rs2010963 loci were between 0.583 and 0.634, with the power of exclusion （PE） between 0.133 and 0.144. The DP and PE of haplotypes of 4 SNP were 0.868 and 0.438, respectively.

CONCLUSIONS

There are great polymorphisms in the 5' region of VEGF gene in Han population in Guangdong, which could be used as genetic indexes for individual identification and paternity testing, as well as association analysis of the related diseases.

SNP in Differentially Methylated Region Upstream of H19 Gene in Guangdong Han Population

OBJECTIVES

To investigate the single nucleotide polymorphism （SNP） and haplotypes in differentially methylated region （DMR） upstream of H19 gene in Guangdong Han population.

METHODS

The PIA typing and restriction enzyme McrBC and HpaⅡ were used to digest the genomic DNA and obtain the individual uniparental DNA template strand. The data of uniparental SNP alleles, genotypes and haplotypes in DMR upstream of H19 gene were obtained by sequencing.

RESULTS

A total of 13 SNPs （rs10840167, rs2525883, rs12417375, rs4930101, rs2525882, rs2735970, rs2735971, rs11042170, rs2735972, rs10732516, rs2071094, rs2107425, and rs4930098） and one mutation locus （g7351c） were found. All loci followed the Hardy-Weinberg equilibrium （P>0.05） by statistical analysis. Except for rs12417375 （DP=0.279） locus, the DP of remaining 12 SNPs were 0.446-0.614, and the g7351c mutation locus （DP=0.013） was the particular loci of the Southern Chinese Han population. Eight haplotypes （designated as haplotype 1-8） were detected, in which 3 haplotypes had not yet been reported and the DP, PIC, PE and H were 0.891, 0.714, 0.524 and 0.758, respectively.

CONCLUSIONS

Obtained by PIA typing, the SNP in DMR upstream of H19 gene and its haplotypes genetic marker system have a high determination power and show a good practical value in forensic identification.

An epidemiological survey of low back pain and axial spondyloarthritis in a Chinese Han population

OBJECTIVE

To investigate the prevalence of low back pain (LBP) and axial spondyloarthritis (SpA) in a Chinese Han population.

METHODS

A face-to-face investigation was performed in the Han population of Dalang Town, Yangshan County, Guangdong Province, China, using a questionnaire established in France in 1999. First the clinical features associated with SpA were investigated, then the human leucocyte antigen (HLA)-B27 and sacroiliac joint radiographic examinations were carried out. Finally, the diagnosis of SpA was determined by rheumatologists.

RESULTS

A total of 13 315 subjects participated in the study and 10 921 were aged >16 years; of these, 787 (7.21%) had LBP. There were 92 axial SpA patients (0.782% in subjects >16 years old and 11.96% in subjects with LBP). There were 29 (0.253%) cases of ankylosing spondylitis (AS), 60 (0.507%) undifferentiated axial SpA (USpA), and three (0.022%) psoriatic arthritis (PsA). Patients in the SpA groups had higher percentages in onset <40 years, insidious onset, morning stiffness, and affected for >3 months compared with those in other LBP groups. Simultaneous symptoms associated with spondylitis, such as buttock pain, heel pain, psoriasis, and SpA family history, were more commonly present. Of the axial SpA patients, 82.67% were HLA-B27 positive, clearly a greater percentage than those (11.65%) in other LBP groups.

CONCLUSIONS

The survey questionnaire for SpA in this study is useful for axial SpA screening in China. In southern China, the prevalence of LBP is 7.21%. The prevalence of axial SpA is 0.782%. USpA is the most common subtype of SpA, followed by AS.

Determination of a misfit dislocation complex in SiGe/Si heterostructures by image deconvolution technique in HREM

The core structure of a dislocation complex in SiGe/Si system composed of a perfect 60 degrees dislocation and an extended 60 degrees dislocation has been revealed at atomic level. This is attained by applying the image deconvolution technique in combination with dynamical diffraction effect correction to an image taken with a 200kV field-emission high-resolution electron microscope. The possible configuration of the dislocation complex is analyzed and their Burgers vectors are determined.

Amplitude correction in image deconvolution for determining crystal defects at atomic level

A method is proposed to improve the image deconvolution technique based on the weak-phase object approximation for determining the crystal defects at atomic level. Originally, both the amplitude and phase modulation caused by the contrast transfer function (CTF) was removed for all reflections in the diffractogram of the image and then the deconvoluted image was obtained by carrying out the inverse FT. In this paper after removing the CTF modulation the amplitudes of reflections are further corrected by constraining the integral amplitudes to be equal to the corresponding structure factor amplitudes of perfect crystals. [110] high-resolution electron microscope images were simulated for a structure model of Si crystal containing the 60 degrees dislocation with different thickness. A comparison between deconvoluted images with the amplitudes corrected by the present method and those uncorrected is given to show the effectiveness of the method. The amplitude-crystal thickness dependence for images simulated close to the Scherzer defocus condition has been analysed and the result serves as an empirical basis of the method. The validity and limitation of the method are discussed.

Active photosynthesis in cyanobacterial mutants with directed modifications in the ligands for two iron-sulfur clusters on the PsaC protein of photosystem I

The PsaC protein of the Photosystem I (PSI) complex in thylakoid membranes coordinates two [4Fe-4S] clusters, FA and FB. Although it is known that PsaC participates in electron transfer to ferredoxin, the pathway of electrons through this protein is unknown. To elucidate the roles of FA and FB, we created two site-directed mutant strains of the cyanobacterium Anabaena variabilis ATCC 29413. In one mutant, cysteine 13, a ligand for FB was replaced by an aspartic acid (C13D); in the other mutant, cysteine 50, a ligand for FA was modified similarly (C50D). Low-temperature electron paramagnetic resonance studies demonstrated that the C50D mutant has a normal FB center and a modified FA center. In contrast, the C13D strain has normal FA, but failed to reveal any signal from FB. Room-temperature optical studies showed that C13D has only one functional electron acceptor in PsaC, whereas two such acceptors are functional in the C50D and wild-type strains. Although both mutants grow under photoautotrophic conditions, the rate of PSI-mediated electron transfer in C13D under low light levels is about half that of C50D or wild type. These data show that (i) FB is not essential for the assembly of the PsaC protein in PSI and (ii) FB is not absolutely required for electron transfer from the PSI reaction center to ferredoxin.

Reconstitution of iron-sulfur center B of Photosystem I damaged by mercuric chloride

Incubation of thylakoid membranes from spinach with low concentrations of mercuric chloride induces the loss of one of the iron-sulfur centers, FB, in Photosystem I (PS I) and inhibits the electron transfer from PS I to the soluble electron carrier, ferredoxin. Reconstitution of this damaged iron-sulfur center has been carried out by incubating treated thylakoid membranes with exogenous FeCl3 and Na2S in the presence ofβ-mercaptoethanol under anaerobic conditions. Low temperature EPR measurements indicate that center FB is largely restored. Kinetic experiments show that the restored FB can be photoreduced from P700. However, these reconstituted thylakoid membranes are still incompetent in the photoreduction of ferredoxin and NADP(+), even though ferredoxin binding to the modified membranes was not impaired, indicating additional changes in the structure of the PS I complex must have occurred.

Specific release of a 9-kDa extrinsic polypeptide of photosystem I from spinach chloroplasts by salt washing

The newly reported 9-kDa polypeptide in photosystem I [(1991) FEBS Lett. 280, 332-334] is an extrinsic component located on the lumenal side of the thylakoid membrane. This subunit can be solubilized with high salt buffer and does not bind any cofactors. The photosystem I electron transfer chain remains intact and functional in the absence of this component as characterized by the photoreduction of NADP+.

Potent anti-tumorigenic effect of tubeimoside 1 isolated from the bulb of Bolbostemma paniculatum (Maxim) Franquet

Tubeimoside 1, one of the new triterpenoid saponins from the bulb of Bolbostemma paniculatum (Maxim) Franquet, had an anti-inflammatory effect on mouse ear edema induced by arachidonic acid and 12-O-tetradecanoylphorbol-13-acetate (TPA). Furthermore, a potent anti-tumorigenic effect of tubeimoside 1 was observed in 2-stage carcinogenesis of mouse skin after oral administration as well as topical application. Thus, tubeimoside 1 appears to be a promising agent for cancer chemoprevention.

Protein secondary structure of the isolated photosystem II reaction center and conformational changes studied by Fourier transform infrared spectroscopy

The secondary structure of the photosystem II (PSII) reaction center isolated from pea chloroplasts has been characterized by Fourier transform infrared (FTIR) spectroscopy. Spectra were recorded in aqueous buffers containing H2O or D2O; the detergent present for most measurements was dodecyl maltoside. The broad amide I and amide II bands were analyzed by using second-derivative and deconvolution procedures. Absorption bands were assigned to the presence of alpha-helices, beta-sheets, turns, or random structure. Quantitative analysis revealed that this complex contained a high proportion of alpha-helices (67%) and some antiparallel beta-sheets (9%) and turns (11%). An irreversible decrease in the intensity of the band associated with the alpha-helices occurs upon exposure of the isolated PSII reaction center to bright illumination. This loss of alpha-helical content gave rise to an increase in other secondary structures, particularly beta-sheets. After similar pretreatment with light, sodium dodecyl sulfate polyacrylamide gel electrophoresis reveals lower mobility and solubility of constituent D1 and D2 polypeptides of the PSII reaction center. Some degradation of these polypeptides also occurs. In contrast, there is no change in the mobility of the two subunits of cytochrome b559. In the absence of illumination, the PSII reaction center exchanged into dodecyl maltoside shows good thermal stability as compared with samples in Triton X-100. Only at a temperature of about 60 degrees C do spectral changes take place that are indicative of denaturation.