The stereoselective pharmacokinetics of the desmethyl-phencynonate hydrochloride in beagle dogs.

The aim of this study was to investigate the chiral inversion and the stereoselective pharmacokinetic profiles of desmethyl-phencynonate hydrochloride after administration of the single isomer and its racemate to beagle dogs. A liquid chromatography with tandem mass spectrometry (LC-MS/MS) method was established for determination of the stereoisomers on chiral columns in beagle dog plasma, which met all the requirements. The chiral inversion in dogs of the desmethyl-phencynonate hydrochloride were studied after administration of the single isomer or the racemic modification. The stereoselective pharmacokinetic profiles of the desmethyl-phencynonate hydrochloride were studied by assays for simultaneous isomers after administration of the racemic modification. The results showed that the absorption of the R-configuration dosed as the single isomer was higher than it dosed as the racemic modification. The AUC(0-t), AUC(0-∞), and Cmax of the S-configuration were much higher than those of R-configuration after oral administration of the racemic desmethyl-phencynonate hydrochloride. The chiral inversion of desmethyl-phencynonate isomers could not occur in dogs after administration of the R-configuration.

Localized tenosynovial giant cell tumor in children.

Background: To investigate the clinical characteristics and surgical efficacy of localized tenosynovial giant cell tumors in children. Methods: The clinical data, surgery, and follow-up results of 17 children with localized tenosynovial giant cell tumors who visited our hospital from 2011 to 2021 were collected for statistical analysis. Results: The median patient age was 7 years and 8 months, and the ratio of males to females was 1.43 (10/7). The predilection of disease was similar in hands and feet, and the common presenting symptom was mass. One patient experienced recurrence after surgery, and one child had postoperative functional limitations. Conclusion: Extremities are common sites of localized tenosynovial giant cell tumors in children. Complete surgical resection helps reduce the recurrence rate. Level of evidence: Level III.

Effects of Florfenicol on nirS-Type Denitrification Community Structure of Sediments in an Aquatic Microcosm Model.

Florfenicol is one of the most widely used antibiotics in aquaculture and veterinary clinics because of its low side effects and strong bactericidal effect. A total of 45~60% of florfenicol is not absorbed by the animal body and accumulates in the aquatic environment through a variety of pathways, which affects denitrification. Indoor aquatic microcosm models were constructed and sediment samples were collected at different florfenicol concentrations (0.1, 1, 10, and 100 mg/L) on days 0, 7, 30, and 60 to extract the microbial genome DNA and determine the water properties. qPCR and amplicon sequencing were used to study the dynamic changes in the nirS gene and nirS-type denitrification community structure, diversity, and abundance, respectively. The results showed that high florfenicol stress influenced the sediment's physicochemical properties, reducing conductivity, alkaline dissolved nitrogen, and organic matter content. In addition, the abundance of nirS, a functional denitrification gene, increased obviously with increased florfenicol concentrations but decreased the diversity of nirS-type denitrification microorganisms. Proteobacteria was the dominant denitrifying phylum in the sediment. Our study provides a scientific basis for the rational use of florfenicol in aquaculture to maintain a healthy and stable microecological environment and also provides a preliminary understanding of the response characteristics of water denitrifying microorganisms to florfenicol exposure.

The lipid peroxidation-derived DNA adduct γ-OHPdG as a diagnostic and prognostic biomarker in hepatocellular carcinoma.

PURPOSE: Chronic inflammation and lipid peroxidation (LPO) are associated with the pathogenesis of hepatocellular carcinoma (HCC), and γ-hydroxy-1, N2-propanodeoxyguanosine (γ-OHPdG) is a promutagenic DNA adduct derived from LPO. This study aimed to examine the relationship between γ-OHPdG and the progression of liver carcinogenesis. METHODS: Primary HCC specimens were obtained from 228 patients and cirrhosis specimens from 46 patients. The patients were followed up with after surgery via outpatient visits and telephone calls. The levels of γ-OHPdG were determined by immunohistochemical analysis in the carcinomatous tissues together with adjacent and cirrhosis tissues. RESULTS: γ-OHPdG levels in the cancerous tissues were significantly higher compared to adjacent tissues (P < 0.001) and also higher than the ones from the tissues of cirrhosis patients. Along with tumor size, histological grade, MVI grade, T stage, the percentage of ki67-positive cells and HCC progression, γ-OHPdG levels in cancerous tissues showed a gradually increasing trend. Moreover, prognostic analysis showed that higher γ-OHPdG levels in cancerous tissues were strongly correlated with lower overall survival (P < 0.001), lower intrahepatic recurrence-free survival (P < 0.001) and lower distant metastasis-free survival (P < 0.05). There was a trend, although not statistically significant, of increased levels of γ-OHPdG in cirrhosis cases that advanced to HCC, whereas γ-OHPdG levels reversely correlated with the period of time observed for cirrhosis advanced to HCC. CONCLUSIONS: These results suggest that γ-OHPdG is a prognostic biomarker for predicting outcomes in HCC, and may serve as a prospective indicator for predicting HCC in cirrhosis patients.

Epidemiology of porcine deltacoronavirus among Chinese pig populations in China: systematic review and meta-analysis.

Porcine deltacoronavirus (PDCoV) is a newly emerging and important porcine enteropathogenic coronavirus that seriously threatens the swine industry in China and worldwide. We conducted a systematic review and meta-analysis to access the prevalence of PDCoV infection in pig population from mainland China. Electronic databases were reviewed for PDCoV infection in pig population, and meta-analysis was performed to calculate the overall estimated prevalence using random-effect models. Thirty-nine studies were included (including data from 31,015 pigs). The overall estimated prevalence of PDCoV infection in pigs in China was 12.2% [95% confidence interval (CI), 10.2-14.2%], and that in Central China was 24.5% (95%CI, 16.1-32.9%), which was higher than those in other regions. During 2014-2021, the estimated prevalence of PDCoV infection was the highest in 2015 at 20.5% (95%CI, 10.1-31.0%) and the lowest in 2021 at 4.8% (95%CI, 2.3-7.3%). The prevalence of PDCoV infection in sows was 23.6% (95%CI, 15.8-31.4%), which was higher than those in suckling piglets, nursery piglets, and finishing pigs. The prevalence of PDCoV infection was significantly associated with sampling region, sampling year, pig stage, and clinical signs (diarrhea). This study systematically evaluated the epidemiology of PDCoV infection in Chinese pig population. The findings provide us with a comprehensive understanding of PDCoV infection and are beneficial for establishing new controlling strategies worldwide.

Quantifying the contribution of local drivers to observed weakening of spring dust storm frequency over northern China (1982-2017).

Recent studies have suggested that spring dust storm (SDS) events in northern China (NC) have exhibited substantial decline over the past 30 years. However, it is unclear which local factors are most responsible for the decline in SDS events, and the contribution of each dominant factor remains to be determined. This study utilized high-density DS records and collocated homogenized surface meteorological observations from 1982 to 2017, in conjunction with land surface products, to examine the local drivers that influence the long-term variation in SDS frequency (SDSF) over the entire NC area and its three dust-source areas: northwestern China (NWC), north-central China (NCC), and northeastern China (NEC). Results indicated that the observed SDSF averaged over NC, NWC, NCC, and NEC has decreased by 144.4 %, 109.3 %, 166.4 %, and 92.2 %, respectively, during 1982-2017. The variation in SDSF is largely explained by variation in wind speed (WS), precipitation, volumetric soil moisture, and surface bareness. A multivariable linear regression model incorporating these local drivers accounted for 81.0 %, 74.0 %, and 46.9 % of the variance in SDSF in NWC, NCC, and NEC, respectively. Statistical analyses on the local drivers suggested that weakening of WS was the dominant factor in the reduction in SDSF over recent decades, contributing 76.9 %, 54.7 %, and 33.6 % of the variation in NWC, NCC, and NEC, respectively. More importantly, we revealed that the interannual variation in regional SDSF was not only controlled by local drivers, but also influenced by cross-regional transport of dust aerosols emitted from upstream source areas.

Source characterization of volatile organic compounds in urban Beijing and its links to secondary organic aerosol formation.

Volatile organic compounds (VOCs) are precursors for ozone and secondary organic aerosol (SOA) formation, thereby playing a vital role in atmospheric chemistry and urban air quality. To characterize the relationship between VOCs and SOA, organics both in gas and particulate phases were concurrently measured in urban Beijing. The VOCs and organic aerosol (OA) were apportioned into factors with different oxidation levels by applying the factorization analysis on their detailed mass spectra. Six factors of VOCs were identified, including four primary VOCs (PVOC) factors and two secondary VOCs (SVOC) factors. The PVOC factors dominated the total VOCs when the air mass originated in the cleaner northern areas, while SVOC factors dominated for polluted southern air masses. The normalized concentrations of PVOC and primary OA factors showed consistent diurnal variations regardless of air mass directions, owing to the relatively stable local emissions during the experimental period. This contrasted with the secondary factors due to more complex transformation processes. The traffic-related VOCs and solid fuel combustion VOCs negatively correlated with SOA, implying that they may have contributed to the SOA formation through photooxidation. The VOCs in lower oxidation levels were found to have poor correlations with the less oxidized SOA, whereas they correlated strongly to the more oxidized SOA. This implied that the less oxidized SOA may be in a transition state, where its production and loss rates were balanced. These served as products of VOCs oxidation and reactants of more oxidized SOA formation, playing important roles on the VOC to SOA transformation. The identified VOC emission sources and their photochemical production of SOA should be considered in air quality policy planning.

Effects of hygroscopicity on aerosol optical properties and direct radiative forcing in Beijing: Based on two-year observations.

The influence of relative humidity on aerosol properties and the direct radiative forcing of PM10 and PM1 were investigated in Beijing from January 2018 to December 2019. The annual mean scattering hygroscopic growth factor at RH = 80 % [f(80 %)] of PM10 and PM1 were 1.60 ± 0.24 and 1.58 ± 0.22, respectively. The variation of aerosol hygroscopic growth factors of PM10 and PM1 aerosols was similar, which is mainly due to the fact that aerosol scattering in Beijing is dominated by fine particles. The seasonal mean f(80 %) of PM10 from spring to winter were 1.66 ± 0.23, 1.71 ± 0.25, 1.51 ± 0.20, 1.49 ± 0.16, respectively, which were higher in spring and summer, and lower in autumn and winter. The diurnal variation of f(80 %) was relatively higher from 12:00 to 18:00, which could be related to the formation of secondary aerosols by photochemical reactions. f(80 %) shows a strong positive relationship with both the scattering Angström exponent (SAE) and the single scattering albedo (ω0) under dry conditions; therefore, the scattering hygroscopic growth factor could be estimated using these two parameters. The upscatter fraction (ß) and single scattering albedo, which are the key aerosol optical properties for the calculation of direct radiative forcing, are also RH-dependent. As RH increases, the upscatter fraction (backscatter fraction) decreases and ω0 increases. The aerosol radiative forcing at RH 80 % was 1.48 times as that in the dry state. The sensitivity experiment showed that the variation in the scattering coefficient with relative humidity had the greatest influence on radiation forcing, followed by ß and ω0. The seasonal variation of ΔF(80 %)/ΔF(dry) coincides with that of the aerosol hygroscopic growth factor. Our study suggests that understanding the influence of relative humidity on aerosol properties and direct radiative forcing is important for accurately estimating the radiative forcing of aerosols.

Atmospheric Particle Hygroscopicity and the Influence by Oxidation State of Organic Aerosols in Urban Beijing.

A hygroscopic tandem differential mobility analyser (H-TDMA) was used to observe the size-resolved hygroscopic characteristics of submicron particles in January and April 2018 in urban Beijing. The probability distribution of the hygroscopic growth factor (HGF-PDF) in winter and spring usually showed a bimodal pattern, with more hygroscopic mode (MH) being more dominant. The seasonal variation in particle hygroscopicity was related to the origin of air mass, which received polluted southerly air masses in spring and clean northwesterly air masses in winter. Particles showed stronger hygroscopic behaviour during heavy pollution episodes (HPEs) with elevated concentrations of secondary aerosols, especially higher mass fraction of nitrate, which were indicated using the PM2.5 (particulate matter with diameter below 2.5 µm) mass concentration normalised by CO mass concentration. The hygroscopic parameter (κ) values were calculated using H-TDMA (κhtdma) and chemical composition (κchem). The closure study showed that κchem was overestimated in winter afternoon when compared with κhtdma, because the organic particle hygroscopic parameter (κorg) was overestimated in the calculations. It was influenced by the presence of a high concentration of hydrocarbon-like organic aerosol (HOA) with a weak water uptake ability. A positive relationship was observed between κorg and the ratio of oxygenated organic aerosol (OOA) and HOA, thereby indicating that the strong oxidation state enhanced the hygroscopicity of the particles. This study revealed the effect of local emission sources and secondary aerosol formation processes on particle hygroscopicity, which is of great significance for understanding the pollution formation mechanism in the North China Plain.

Effectiveness of polyvalent bacterial lysate for pediatric asthma control: a retrospective propensity score-matched cohort study.

Background: Previous studies showed bacterial lysates were effective for pediatric asthma. However, evidence of polyvalent bacterial lysate Qipian is lacking. Methods: In this real-world retrospective cohort study, data of children with asthma, aged six months to 14 years old, attending to Jiangxi Provincial Children's Hospital from January 2021 to April 2022, prescribed routine treatment for asthma plus Qipian (Qipian group) or not (control group) were extracted. To minimize the impact of confounders on the outcomes, baseline characteristics were utilized to perform propensity score matching through a multivariable logistic regression model. After matching, asthma control, exacerbation, etc. were compared. Results: Totally, 795 patients were included (337 in the Qipian group and 458 in the control group), with 278 pairs (556 patients) matched. Most baseline characteristics were well-balanced. The proportion of males were 68.3% and 70.1% in the two groups. The Qipian group favored better asthma control, with more "controlled" [3-month: 257 (92.4%) vs. 240 (86.3%); 6-month: 246 (88.5%) vs. 235 (84.5%)], and fewer "poorly/very poorly controlled" patients, compared with the control group (P=0.004 and 0.025, respectively). Patients in the Qipian group had lower risks of exacerbation. Incidence rate ratios (IRR) for any exacerbation were 0.56 [95% confidence interval (CI): 0.33 to 0.93] in the 3-month period and 0.83 (95% CI: 0.55 to 1.26) in the 6-month period. IRR for severe exacerbations were 0.09 (95% CI: 0.01 to 0.71) in the 3-month period and 0.20 (95% CI: 0.06 to 0.70) in the 6-month period (compared to the control group). Qipian significantly reduced the cumulative dose of short-acting beta-agonist (3-month: 3.22±10.37 vs. 8.08±16.71 mg; P<0.001; 6-month: 6.56±16.23 vs. 11.81±24.41 mg; P=0.002). There was no difference in incidences of respiratory tract infection or fever due to respiratory tract infection between the two groups. Numbers of antibacterial agent prescription were fewer in the Qipian group compared to the control group (3-month: 0.67±1.16 vs. 1.04±1.45; P=0.001; 6-month: 1.14±1.69 vs. 1.51±2.12; P=0.023). Conclusions: According to this retrospective study, Qipian may be effective for improved pediatric asthma control. Safety profile and mechanisms of action of Qipian need further investigation. Further randomized controlled trials are warranted to confirm our results.

A multi-center retrospective comparative study of third generation Ceramic-on- Ceramic total hip arthroplasty in patients younger than 45 years with or without the sandwich liner: A ten-year minimum.

BACKGROUND: Ceramic-on-ceramic couplings are attractive alternative bearing surfaces that have been reported to eliminate or reduce problems related to polyethylene wear debris. However, the material in THA still remains one of the major concerns about the risk of fracture, due to its brittleness. OBJECTIVE: The present study aims at reporting the fracture rate of a series of ceramic-on-ceramic THAs with use of the sandwich liner combined with a ceramic femoral head, and attempt to detect the relative risk factors, possible cause and assesse the medium-term clinical results. METHODS: We retrospectively evaluated 282 patients (300 hips) with use of the sandwich liner ceramic-on-ceramic THA between 2001 and 2009 at three-centers. Patient assessment was based on demographic factors, including age, weight, gender and body-mass index. All patients were evaluated clinically and radio-graphically or computed tomography in consideration of dislocation, osteolysis, periprosthetic fracture, infection, loosening and implant fracture. RESULTS: five ceramic sandwich liners fracture (1.7%) were observed at an average of 7.3 years follow-up. These factors were irrelevant to the ceramic liner fracture, including age (p = 0.205), weight (p = 0.241), gender (p = 0.553), body-mass index (p = 0.736), inclination (p = 0.727), and anteversion (p = 0.606). The overall survival was 91.4% at 12 years with revision as the endpoint. Other complications included dislocation in two, perprosthetic fracture in two and osteolysis in eight hips. No hip had aseptic loosening of the implants was seen. CONCLUSIONS: We found that the sandwich liner may be lead to a high rate of alumina fracture and osteolysis. We have discontinued the use of sandwich liner with THA since 2009.

Nuclear receptor estrogen-related receptor gamma suppresses colorectal cancer aggressiveness by regulating Wnt/ß-catenin signaling.

Colorectal cancer (CRC) is the predominant cause of cancer-related death worldwide, because of the lack of effective therapeutic targets. Estrogen-related receptor gamma (ESRRG), which belongs to the family of nuclear receptors, functions as an important element regulating gene transcription. In our report, we identified ESRRG as a potential tumor suppressor. The decreased level of ESRRG was initially observed in CRC and was highly associated with a poor prognosis. ESRRG overexpression abrogated cell growth and metastasis in vitro and in vivo. Mechanistically, ESRRG repressed the epithelial-to-mesenchymal transition process and antagonized Wnt signaling by regulating ß-catenin degradation. In addition, significant ESRRG hypermethylation was found in CRC and inversely correlated with its expression. Consistently, the expression of ESRRG was induced after treatment with DNA demethylating agent 5-aza-2'-deoxycytidine. Taken together, these findings define a tumor-suppressive role of ESRRG in CRC, providing a potential novel therapeutic approach for this cancer.

Formation and evolution of secondary particulate matter during heavy haze pollution episodes in winter in a severe cold climate region of Northeast China.

The formation and evolution of sulfate (SO42-) and nitrate (NO3-) secondary contaminants under different stages of pollution episodes and different meteorological and emission conditions were compared, based on the simultaneous observation of fine particulate matter (PM2.5) and its chemical components in four heavy haze pollution episodes at 14 sampling sites in a severe cold climate region of Northeast China in winter from 2017 to 2019. The results yielded two main findings. (1) Nitrate formation during the day was mainly due to the combination of high emissions and high relative humidity (RH, 50-90%), high temperature (T, 0 to 5 °C), high atmospheric oxidizability (ozone (O3) and nitrous acid (HONO) concentrations), and high ammonia (NH3) concentrations. Nitrate was formed by a gas-phase homogeneous reaction of the hydroxyl radical (OH·) with nitrogen dioxide (NO2), sulfur dioxide (SO2), and ammonia (NH3). (2) The main differences in SO42- formation between Northeast China and other regions were that the gas-phase oxidation process played an important role. This was mainly a result of the promotion of the gas-phase oxidation of SO42- due to the high oxidizing ability and the suppression of the aqueous reaction due to the low Ts in winter and low-sulfur coal emissions. Sulfate formation mostly occurred through an aqueous phase reaction in winter, but the highest yield and the fastest production capacity were produced by the gas-phase reaction.

Antimicrobial Resistance and Transconjugants Characteristics of sul3 Positive Escherichia coli Isolated from Animals in Nanning, Guangxi Province.

Sulfonamides are the second most popular antibiotic in many countries, which leads to the widespread emergence of sulfonamides resistance. sul3 is a more recent version of the gene associated with sulfonamide resistance, whose research is relatively little. In order to comprehend the prevalence of sul3 positive E. coli from animals in Nanning, a total of 146 strains of E. coli were identified from some farms and pet hospitals from 2015 to 2017. The drug resistance and prevalence of sul3 E. coli were analyzed by polymerase chain reaction (PCR) identification, multi-site sequence typing (MLST), drug sensitivity test, and drug resistance gene detection, and then the plasmid containing sul3 was conjugated with the recipient strain (C600). The effect of sul3 plasmid on the recipient was analyzed by stability, drug resistance, and competitive test. In this study, forty-six sul3 positive E. coli strains were separated. A total of 12 ST types were observed, and 1 of those was a previously unknown type. The ST350 is the most numerous type. All isolates were multidrug-resistant E. coli, with high resistant rates to penicillin, ceftriaxone sodium, streptomycin, tetracycline, ciprofloxacin, gatifloxacin, and chloramphenicol (100%, 73.9%, 82.6%, 100%, 80.4%, 71.7%, and 97.8%, respectively). They had at least three antibiotic resistance genes (ARGs) in addition to sul3. The plasmids transferred from three sul3-positive isolates to C600, most of which brought seven antimicrobial resistance (AMR) and increased ARGs to C600. The transferred sul3 gene and the plasmid carrying sul3 could be stably inherited in the recipient bacteria for at least 20 days. These plasmids had no effect on the growth of the recipient bacteria but greatly reduced the competitiveness of the strain at least 60 times in vitro. In Nanning, these sul3-positive E. coli had such strong AMR, and the plasmid carrying sul3 had the ability to transfer multiple resistance genes that long-term monitoring was necessary. Since the transferred plasmid would greatly reduce the competitiveness of the strain in vitro, we could consider limiting the spread of drug-resistant isolates in this respect.

Intensified wintertime secondary inorganic aerosol formation during heavy haze pollution episodes (HPEs) in Beijing, China.

Air pollution in China is complex, and the formation mechanism of chemical components in particulate matter is still unclear. This study selected three consecutive heavy haze pollution episodes (HPEs) during winter in Beijing for continuous field observation, including an episode with heavy air pollution under red alert. Clean days during the observation period were selected for comparison. The HPE characteristics of Beijing in winter were: under the influence of adverse meteorological conditions such as high relative humidity, temperature inversion and low wind speed; and strengthening of secondary transformation reactions, which further intensified the accumulation of secondary aerosols and other pollutants, promoting the explosive growth of PM2.5. PM2.5/CO values, as indicators of the contribution of secondary transformation in PM2.5, were approximately 2 times higher in the HPEs than the average PM2.5/CO during the clean period. The secondary inorganic aerosols (sulfate nitrate and ammonium salt) were significantly enhanced during the HPEs, and the conversion coefficients were remarkably improved. In addition, it is interesting to observe that the production of sulfate tended to exceed that of nitrate in the late stage of all three HPEs. The existence of aqueous phase reactions led to the explosive growth sulfur oxidation ratio (SOR) and rapid generation of sulfate under high relative humidity (RH>70%).

The Clinical and Radiological Outcomes of Subtrochanteric Osteotomy in Crowe Type IV Hip Dysplasia: A Comparison of Three Different Stem Designs.

AIMS: The purpose of this study was to determine whether there are differences in clinical and radiographic outcomes among three different stem designs for subtrochanteric osteotomy in Crowe type IV developmental dysplasia of the hip (DDH). METHODS: A retrospective analysis of prospectively collected data was undertaken from a consecutive series of 37 Crowe type IV DDHs treatment of noncemented total hip arthroplasty with chevron subtrochanteric osteotomy in 30 patients. Patients are divided into three groups, including Ribbed group (using Link Ribbed stem; n = 14), Synergy group (using Synergy stem; n = 9), and Link Classic Uncemented (LCU) group (using LCU stem; n = 14), according to the design of the stem. The clinical and radiographic outcomes were evaluated. RESULTS: All patients were followed for 36 months. The time of bone union of the LCU stem was significantly longer than that of the Synergy stem (P = 0.02) and the Ribbed stem (P > 0.05); the time of bone union of the Ribbed stem was longer than that of the Synergy stem (P > 0.05). The length of stem in the distal femur of the Ribbed stem (P = 0.000) and the Synergy stem (P = 0.001) is significantly longer than that of the LCU stem. There were three hips with malunion, stem loosening, and varus alignment, which were observed in the LCU stem. None of these were observed in Ribbed and Synergy stems. In total hip arthroplasty with a noncemented stem combined with subtrochanteric femoral osteotomy for Crowe IV DDH, 89.2% hips (33/37) can achieve good and excellent clinical outcomes. There were three hips (1 hip in the Ribbed stem and two in the LCU stem) with fair clinical outcomes and one hip (LCU stem) with poor clinical outcomes. CONCLUSIONS: Although Ribbed, Synergy, and LCU stems have similar clinical outcomes, the LCU stem has a tendency to a varus position, longer union time, malunion, and stem loosening, when compared with the Ribbed and Synergy stems. We recommend against adoption of the LCU stem for Crowe IV DDH with subtrochanteric femoral osteotomy. LEVEL OF EVIDENCE: Level III, therapeutic study.

Platelet-Derived Growth Factor-Functionalized Scaffolds for the Recruitment of Synovial Mesenchymal Stem Cells for Osteochondral Repair.

Cartilage regeneration is still a challenge for clinicians because of avascularity, denervation, load-bearing, synovial movement, and the paucity of endogenous repair cells. We constructed a multilayered osteochondral bionic scaffold and examined its repair capacity using a rabbit osteochondral defect model. The cartilage phase and interface layer of the scaffold were prepared by freeze-drying, whereas the bone phase of the scaffold was prepared by high-temperature sintering. The three-phase osteochondral bionic scaffold was formed by joining the hydroxyapatite (HAp) and silk fibroin (SF) scaffolds using the repeated freeze-thaw method. Different groups of scaffolds were implanted into the rabbit osteochondral defect model, and their repair capacities were assessed using imaging and histological analyses. The cartilage phase and the interface layer of the scaffold had a pore size of 110.13 ± 29.38 and 96.53 ± 33.72 µm, respectively. All generated scaffolds exhibited a honeycomb porous structure. The polydopamine- (PDA-) modified scaffold released platelet-derived growth factor (PDGF) for 4 weeks continuously, reaching a cumulative release of 71.74 ± 5.38%. Synovial mesenchymal stem cells (SMSCs) adhered well to all scaffolds, but demonstrated the strongest proliferation ability in the HSPP (HAp-Silk-PDA-PDGF) group. Following scaffold-induced chondrogenic differentiation, SMSCs produced much chondrocyte extracellular matrix (ECM). In in vivo experiments, the HSPP group exhibited a significantly higher gross tissue morphology score and achieved cartilage regeneration at an earlier stage and a significantly better repair process compared with the other groups (P < 0.05). Histological analysis revealed that the new cartilage tissue in the experimental group had a better shape and almost filled the defect area, whereas the scaffold was nearly completely degraded. The new cartilage was effectively fused with the surrounding normal cartilage, and a substantial amount of chondrocyte ECM was formed. The SF/HAp three-layer osteochondral bionic scaffold exhibited favorable pore size, porosity, and drug sustained-release properties. It demonstrated good biocompatibility in vitro and encouraging repair effect at osteochondral defect site in vivo, thereby expected to enabling the repair and regeneration of osteochondral damage.

On the fossil and non-fossil fuel sources of carbonaceous aerosol with radiocarbon and AMS-PMF methods during winter hazy days in a rural area of North China plain.

Regional transport is a key source of carbonaceous aerosol in many Chinese megacities including Beijing. The sources of carbonaceous aerosol in urban areas have been studied extensively but are poorly known in upwind rural areas. This work aims to quantify the contributions of fossil and non-fossil fuel emissions to carbonaceous aerosols at a rural site in North China Plain in winter 2016. We integrated online high resolution-time of flight-aerosol mass spectrometer (HR-TOF-AMS) observations and radiocarbon (14C) measurements of fine particles with Positive Matrix Factorization (PMF) analysis as well as Extended Gelencsér (EG) method. We found that fine particle concentration is much higher at the rural site than in Beijing during the campaign (Dec 7, 2016 to Jan 8, 2017). PMF analysis of the AMS data showed that coal-combustion related organic aerosol (CCOA + Oxidized CCOA) and more oxidized oxygenated organic aerosol (MO-OOA) contributed 48% and 30% of organic matter to non-refractory PM1 (NR-PM1) mass. About 2/3 of the OC and EC were from fossil-fuel combustion. The EG method, combining AMS-PMF and 14C data, showed that primary and secondary OC from fossil fuel contribute 35% and 22% to total carbon (TC), coal combustion emission dominates the fossil fuel sources, and biomass burning accounted for 21% of carbonaceous aerosol. In summary, our results confirm that fossil fuel combustion was the dominant source of carbonaceous aerosol during heavy pollution events in the rural areas. Significant emissions of solid fuel carbonaceous aerosols at rural areas can affect air quality in downwind cities such as Beijing and Tianjin, highlighting the benefits of energy transition from solid fuels to cleaner energy in rural areas.

Long-term trend of new particle formation events in the Yangtze River Delta, China and its influencing factors: 7-year dataset analysis.

To evaluate the influence of anthropogenic emission reductions since 2013 in China, a long-term trend analysis of the particle number size distribution (PNSD) and new particle formation (NPF) events in the Yangtze River Delta (YRD) region was conducted based on the PNSD measurement (diameter ranging from 3 to 850 nm) at the Lin'an (LAN) regional background station from 2013 to 2019. A modified Mann-Kendall test and a Theil-Sen estimator were used to calculate the overall trend of particle number concentrations in different modes and the relevant influencing factors. We observed a significant decreasing trend in the Aitken and accumulation mode number concentrations, with annual decrease rates of approximately 5.6% and 8.2%, respectively, resulting in an approximately 6.0% decline in total particles annually. However, the nucleation mode particle number concentration showed no significant trend from 2013 to 2016, but an increasing trend from 2016 to 2019, which was related to the NPF events occurrence frequency. The regional NPF events of "banana shape" accounted for an increasing fraction of all NPF events. As a key parameter influencing the NPF event, the condensation sink decreased by approximately 63% from 2013 to 2019. Moreover, the estimated sulfuric acid concentration decreased by approximately 50%, with a higher reduction rate occurring during 2013-2016 as result of the effective SO2 reduction. Surface meteorological factors (including the air temperature, relative humidity, air pressure, and wind) and the air masses origin were found to played minor roles in the long-term trend of NPF events. As PNSD and NPF events are closely related to changes in the particle emissions and regional air pollution levels, studies concerning PNSD and NPF are necessary to provide important information regarding air quality improvements and evaluating the efficacy of climate change mitigation strategies.