FAP Expression Dynamics and Role in Silicosis: Insights from Epidemiological and Experimental Models.

Prolonged exposure to free silica leads to the development of silicosis, wherein activated fibroblasts play a pivotal role in its pathogenesis and progression. Fibroblast Activation Protein (FAP), as a biomarker for activated fibroblasts, its expression pattern and role in key aspects of silicosis pathogenesis remain unclear. This study elucidated the expression pattern and function of FAP through population-based epidemiological investigations, establishment of mouse models of silicosis, and in vitro cellular models. Results indicated a significant elevation of FAP in plasma from silicosis patients and lung tissues from mouse models of silicosis. In the cellular model, we observed a sharp increase in FAP expression early in the differentiation process, which remained high expression. Inhibition of FAP suppressed fibroblast differentiation, while overexpression of FAP produced the opposite effect. Moreover, fibroblast-derived FAP can alter the phenotype and function of neighboring macrophages. In summary, we revealed a high expression pattern of FAP in silicosis and its potential mechanistic role in fibrosis, suggesting FAP as a potential therapeutic target for silicosis.

The molecular basis of phenotypic evolution: beyond the usual suspects.

It has been well documented that mutations in coding DNA or cis-regulatory elements underlie natural phenotypic variation in many organisms. However, the development of sophisticated functional tools in recent years in a wide range of traditionally non-model systems have revealed many 'unusual suspects' in the molecular bases of phenotypic evolution, including upstream open reading frames (uORFs), cryptic splice sites, and small RNAs. Furthermore, large-scale genome sequencing, especially long-read sequencing, has identified a cornucopia of structural variation underlying phenotypic divergence and elucidated the composition of supergenes that control complex multi-trait polymorphisms. In this review article we highlight recent studies that demonstrate this great diversity of molecular mechanisms producing adaptive genetic variation and the panoply of evolutionary paths leading to the 'grandeur of life'.

Effect of Recycled Fine Aggregates on the Mechanical and Drying Shrinkage Properties of Alkali-Activated Recycled Concrete.

In this paper, the workability, mechanical, ion leaching, and drying shrinkage properties of alkali-activated concrete with recycled coarse and fine aggregates were studied, and the pore structure and micro-morphology of different alkali-activated recycled aggregate concretes (AARACs) were characterized by using the mercury intrusion method and scanning electron microscopy, respectively. The experimental results showed that with the increase in the replacement rate of the recycled fine aggregate (RFA), the flowability showed a decreasing trend. Adding a certain amount of RFA improves the mechanical properties of the AARAC. The compressive strength at a curing age of 28 days was 65.3 MPa with 70 wt% RFA replacement. When the replacement rate of the RFA was 100 wt%, the maximum splitting tensile strength (4.5 MPa) was obtained at a curing age of 7 days. However, the addition of the RFA had little effect on the flexural strength of the AARAC. As an extension of the curing age, the splitting tensile strength, flexural strength, tension-to-compression ratio, and flexure-to-compression ratio all showed an increasing trend at first and then a decreasing trend. At a curing age of 7 days, the tension-to-compression ratio and flexure-to-compression ratio were both high (except for those of R100), indicating that the ductility and toughness of the specimen were improved. The addition of the RFA increased the drying shrinkage of the AARAC. At a curing age of 120 days, compared to the specimen without the RFA, the drying shrinkage rate of the specimen with the addition of 70 wt% RFA increased by 34.15%. As the curing age increased, the microstructure of the reaction products became denser, but the proportion of large-diameter pores increased. This study evaluated the application of RFA in AARAC. The experimental results showed that the RFA-based AARAC had acceptable mechanical and durability properties.

Tri-enzyme fusion of tryptophan halogenase achieves a concise strategy for coenzyme self-sufficiency and the continuous halogenation of L-tryptophan.

The halogenase-based catalysis is one of the most environmentally friendly methods for the synthesis of halogenated products, among which flavin-dependent halogenases (FDHs) have attracted great interest as one of the most promising biocatalysts due to the remarkable site-selectivity and wide substrate range. However, the complexity of constructing the NAD+-NADH-FAD-FADH2 bicoenzyme cycle system has affected the engineering applications of FDHs. In this work, a coenzyme self-sufficient tri-enzyme fusion was constructed and successfully applied to the continuous halogenation of L-tryptophan. SpFDH was firstly identified derived from Streptomyces pratensis, a highly selective halogenase capable of generating 6-chloro-tryptophan from tryptophan. Then, using gene fusion technology, SpFDH was fused with glucose dehydrogenase (GDH) and flavin reductase (FR) to form a tri-enzyme fusion, which increased the yield by 1.46-fold and making the coenzymes self-sufficient. For more efficient halogenation of L-tryptophan, a continuous halogenation bioprocess of L-tryptophan was developed by immobilizing the tri-enzyme fusion and attaching it to a continuous catalytic device, which resulted in a reaction yield of 97.6% after 12 h reaction. An FDH from S. pratensis was successfully applied in the halogenation and our study provides a concise strategy for the preparation of halogenated tryptophan mediated by multienzyme cascade catalysis.

FOXF1 reverses lung fibroblasts transdifferentiation via inhibiting TGF-ß/SMAD2/3 pathway in silica-induced pulmonary fibrosis.

Silicosis is one of the most common and severe types of pneumoconiosis and is characterized by lung dysfunction, persistent lung inflammation, pulmonary nodule formation, and irreversible pulmonary fibrosis. The transdifferentiation of fibroblasts into myofibroblasts is one of the main reasons for the exacerbation of silicosis. However, the underlying mechanism of transcription factors regulating silicosis fibrosis has not been clarified. The aim of this study was to investigate the potential mechanism of transcription factor FOXF1 in fibroblast transdifferentiation in silica-induced pulmonary fibrosis. Therefore, a silicosis mouse model was established, and we found that FOXF1 expression level was significantly down-regulated in the silicosis group, and after overexpression of FOXF1 by adeno-associated virus (AAV), FOXF1 expression level was up-regulated, and silicosis fibrosis was alleviated. In order to further explore the specific regulatory mechanism of FOXF1 in silicosis, we established a fibroblasts transdifferentiation model induced by TGF-ß in vitro. In the model, the expression levels of SMAD2/3 and P-SMAD2/3 were up-regulated, but the expression levels of SMAD2/3 and P-SMAD2/3 were down-regulated, inhibiting transdifferentiation and accumulation of extracellular matrix after the overexpressed FOXF1 plasmid was constructed. However, after silencing FOXF1, the expression levels of SMAD2/3 and P-SMAD2/3 were further up-regulated, aggravating transdifferentiation and accumulation of extracellular matrix. These results indicate that the activation of FOXF1 in fibroblasts can slow down the progression of silicosis fibrosis by inhibiting TGF-ß/SMAD2/3 classical pathway, which provides a new idea for further exploration of silicosis treatment.

Bioinformatics-based dynamics of cuproptosis -related indicators in experimental silicosis.

Pneumoconiosis is one of the most serious occupational diseases worldwide. Silicosis due to prolonged inhalation of free silica dust during occupational activities is one of the main types. Cuproptosis is a newly discovered mode of programmed cell death characterized by the accumulation of free copper in the cell, which ultimately leads to cell death. Increased copper in the serum of silicosis patients, suggests that the development of silicosis is accompanied by changes in copper metabolism, but whether cuproptosis is involved in the progression of silicosis is actually to be determined. To test this hypothesis, we screened the genetic changes in patients with idiopathic fibrosis by bioinformatics methods and predicted and functionally annotated the cuproptosis-related genes among them. Subsequently, we established a mouse silicosis model and detected the concentration of copper ions and the activity of ceruloplasmin (CP) in serum, as well as changes of the concentration of copper and cuproptosis related genes in mouse lung tissues. We identified 9 cuproptosis-related genes among the differential genes in patients with IPF at different times and the tissue-specific expression levels of ferredoxin 1 (FDX1) and Lipoyl synthase (LIAS) proteins. Furthermore, serum CP activity and copper ion levels in silicosis mice were elevated on days 7th and 56th after silica exposure. The expression of CP in mouse lung tissue elevated at all stages after silica exposure. The mRNA level of FDX1 decreased on days 7th and 56th, and the protein level remained in accordance with the mRNA level on day 56th. LIAS and Dihydrolipoamide dehydrogenase (DLD) levels were downregulated at all times after silica exposure. In addition, Heatshockprotein70 (HSP70) expression was increased on day 56. In brief, our results demonstrate that there may be cellular cuproptosis during the development of experimental silicosis in mice and show synchronization with enhanced copper loading in mice.

Exposure to micron-grade silica particles triggers pulmonary fibrosis through cell-to-cell delivery of exosomal miR-107.

Long-term exposure to inhalable silica particles may lead to severe systemic pulmonary disease, such as silicosis. Exosomes have been demonstrated to dominate the pathogenesis of silicosis, but the underlying mechanisms remain unclear. Therefore, this study aimed to explore the roles of exosomes by transmitting miR-107, which has been linked to the toxic pulmonary effects of silica particles. We found that miR-107, miR-122-5p, miR-125a-5p, miR-126-5p, and miR-335-5p were elevated in exosomes extracted from the serum of patients with silicosis. Notably, an increase in miR-107 in serum exosomes and lung tissue was observed in the experimental silicosis mouse model, while the inhibition of miR-107 reduced pulmonary fibrosis. Moreover, exosomes helped the migration of miR-107 from macrophages to lung fibroblasts, triggering the transdifferentiation of cell phenotypes. Further experiments demonstrated that miR-107 targets CDK6 and suppresses the expression of retinoblastoma protein phosphorylation and E2F1, resulting in cell-cycle arrest. Overall, micron-grade silica particles induced lung fibrosis through exosomal miR-107 negatively regulating the cell cycle signaling pathway. These findings may open a new avenue for understanding how silicosis is regulated by exosome-mediated cell-to-cell communication and suggest the prospect of exosomes as therapeutic targets.

Manganese accumulation in red blood cells as a biomarker of manganese exposure and neurotoxicity.

Although overexposure to manganese (Mn) is known to cause neurotoxic damage, effective exposure markers for assessing Mn loading in Mn-exposed workers are lacking. Here, we construct a Mn-exposed rat model to perform correlation analysis between Mn-induced neurological damage and Mn levels in various biological samples. We combine this analysis with epidemiological investigation to assess whether Mn concentrations in red blood cells (MnRBCs) and urine (MnU) can be used as valid exposure markers. The results show that Mn exposure resulted in neurotoxic damage in rats and that MnRBCs correlated well with neurological damage, showing potential as a novel Mn exposure biomarker. These findings provide a basis for health monitoring of Mn-exposed workers and the development of more appropriate biological exposure limits.

Engineered the Active Site of ω-Transaminase for Enhanced Asymmetric Synthesis Towards (S)-1-[4-(Trifluoromethyl)phenyl]ethylamine.

ω-Transaminase (ω-TA) is a promising biocatalyst for the synthesis of chiral amines. In this study, a ω-TA derived from Vitreoscilla stercoraria DSM 513 (VsTA) was heterologous expressed in recombinant E. coli cells and applied to reduce 4'-(trifluoromethyl)acetophenone (TAP) to (S)-1-[4-(trifluoromethyl)phenyl]ethylamine ((S)-TPE), a pharmaceutical intermediate of chiral amine. Aimed to a more efficient synthesis of (S)-TPE, VsTA was further engineered via a semi-rational strategy. Compared to wild-type VsTA, the obtained R411A variant exhibited 2.39 times higher activity towards TAP and enhanced catalytic activities towards other prochiral aromatic ketones. Additionally, better thermal stability for R411A variant was observed with 25.4% and 16.3% increase in half-life at 30 °C and 40 °C, respectively. Structure-guided analysis revealed that the activity improvement of R411A variant was attributed to the introduction of residue A411, which is responsible for the increase in the hydrophobicity of substrate tunnel and the alleviation of steric hindrance, thereby facilitating the accessibility of hydrophobic substrate TAP to the active center of VsTA. This study provides an efficient strategy for the engineering of ω-TA based on semi-rational approach and has the potential for the molecular modification of other biocatalysts.

miRNome targeting NF-κB signaling orchestrates macrophage-triggered cancer metastasis and recurrence.

Whether and how tumor intrinsic signature determines macrophage-elicited metastasis remain elusive. Here, we show, in detailed studies of data regarding 7,477 patients of 20 types of human cancers, that only 13.8% ± 2.6%/27.9% ± 3.03% of patients with high macrophage infiltration index exhibit early recurrence/vascular invasion. In parallel, although macrophages enhance the motility of various hepatoma cells, their enhancement intensity is significantly heterogeneous. We identify that the expression of malignant Dicer, a ribonuclease that cleaves miRNA precursors into mature miRNAs, determines macrophage-elicited metastasis. Mechanistically, the downregulation of Dicer in cancer cells leads to defects in miRNome targeting NF-κB signaling, which in turn enhances the ability of cancer cells to respond to macrophage-related inflammatory signals and ultimately promotes metastasis. Importantly, transporting miR-26b-5p, the most potential miRNA targeting NF-κB signaling in hepatocellular carcinoma, can effectively reverse macrophage-elicited metastasis of hepatoma in vivo. Our results provide insights into the crosstalk between Dicer-elicited miRNome and cancer immune microenvironments and suggest that strategies to remodel malignant cell miRNome may overcome pro-tumorigenic activities of inflammatory cells.

Structural Study of the Thermoelectric Work Units Encapsulated with Cement Paste for Building Energy Harvesting.

Cement-based material encapsulation is a method of encapsulating electronic devices in highly thermally conductive cement-based materials to improve the heat dissipation performance of electronic components. In the field of construction, a thermoelectric generator (TEG) encapsulated with cement-based materials used in the building envelope has significant potential for waste heat energy recovery. The purpose of this study was to investigate the effect of cement-based materials integrated with aluminum heatsinks on the heat dissipation of the TEG composite structure. In this work, three types of thermoelectric work units encapsulated with cement paste were proposed. Moreover, we explored the effect of encapsulated structure, heat dissipation area, the height of thermoelectric single leg, and heat input temperature on maintaining the temperature difference between the two sides of the thermoelectric single leg with COMSOL Multiphysics. The numerical simulation results showed that under the conditions of a heat source temperature of 313.15 K and ambient temperature of 298.15 K, the temperature difference between the two sides of the internal thermoelectric single leg of Type-III can maintain a stable temperature difference of 7.77 K, which is 32.14% higher than that of Type-I and Type-II (5.88 K), and increased by 26.82% in the actual experiment. This work provides a reference for the selection and application of TEG composite structures of cement-based materials combined with aluminum heatsinks.

Expression levels of key immune indicators and immune checkpoints in manganese-exposed rats.

Manganese is essential trace elements, to participate in the body a variety of biochemical reactions, has important physiological functions, such as stimulate the immune cell proliferation, strengthen the cellular immunity, etc. However, excessive manganese exposure can cause damage to multiple systems of the body.The immune system is extremely vulnerable to external toxicants, however manganese research on the immune system are inadequate and biomarkers are lacking. Therefore, here we applied a manganese-exposed rat model to make preliminary observations on the immunotoxic effects of manganese. We found that manganese exposure inhibited humoral immune function in rats by decreasing peripheral blood IgG (ImmunoglobulinG, IgG), IgM (ImmunoglobulinM, IgM) and complement C3 levels; It also regulates rat cellular immune activity by influencing peripheral blood, spleen, and thymus T cell numbers and immune organ ICs (Immune Checkpoints, ICs) and cytokine expression. Furthermore, it was revealed that the impact of manganese exposure on the immune function of rats exhibited a correlation with both the dosage and duration of exposure. Notably, prolonged exposure to high doses of manganese had the most pronounced influence on rat immune function, primarily manifesting as immunosuppression.The above findings suggest that manganese exposure leads to impaired immune function and related changes in immune indicators, or may provide clues for the discovery of its biomarkers.

Genetic basis of nectar guide trichome variation between bumblebee- and self-pollinated monkeyflowers (Mimulus): role of the MIXTA-like gene GUIDELESS.

Nectar guide trichomes play crucial ecological roles in bee-pollinated flowers, as they serve as footholds and guides for foraging bees to access the floral rewards. However, the genetic basis of natural variation in nectar guide trichomes among species remains poorly understood. In this study, we performed genetic analysis of nectar guide trichome variation between two closely related monkeyflower (Mimulus) species, the bumblebee-pollinated Mimulus lewisii and self-pollinated M. parishii. We demonstrate that a MIXTA-like R2R3-MYB gene, GUIDELESS, is a major contributor to the nectar guide trichome length variation between the two species. The short-haired M. parishii carries a recessive allele due to non-synonymous substitutions in a highly conserved motif among MIXTA-like MYB proteins. Furthermore, our results suggest that besides GUIDELESS, additional loci encoding repressors of trichome elongation also contribute to the transition from bumblebee-pollination to selfing. Taken together, these results suggest that during a pollination syndrome switch, changes in seemingly complex traits such as nectar guide trichomes could have a relatively simple genetic basis, involving just a few genes of large effects.

Silica-exposed macrophages-secreted exosomal miR125a-5p induces Th1/Th2 and Treg/Th17 cell imbalance and promotes fibroblast transdifferentiation.

Until now, the specific pathogenesis of silicosis is not clear. Exosomal miRNAs, as a newly discovered intercellular communication medium, play an important role in many diseases. Our previous research found that serum exosomal miR125a-5p was increased in silicosis patients by miRNAs high-throughput sequencing. TRAF6, is a target gene of miR125a-5p, which is involved in T-cell differentiation. Furthermore, results from animal study indicate that knockdown of miR-125a-5p can regulate T lymphocyte subsets and significantly reduce pulmonary fibrosis by targeting TRAF6. However, the level of serum exosomal miR125a-5p in silicosis patients has not been reported, the role of macrophages-secreted exosomal miR-125a-5p in regulating T cell differentiation to promote fibroblast transdifferentiation (FMT) remains unknown. In this study, the levels of serum exosomal miR125a-5p and serum TGF-ß1, IL-17A, IL-4 cytokines in silicosis patients were elevated, with the progression of silicosis, the level of serum exosomal miR125a-5p and serum IL-4 were increased; thus, the serum level of IFN-γ was negatively correlated with the progression of silicosis. In vitro, the levels of miR125a-5p in macrophages, exosomes, and T cells stimulated by silica were significantly increased. When the mimic was transfected into T cells, which directly suppressed TRAF6 and caused the imbalance of T cells differentiation, induced FMT. To sum up, these results indicate that exosomal miR-125a-5p may by targeting TRAF6 of T cells, induces the activation and apoptosis of T cells and the remodeling of Th1/Th2 and Th17/Tregs distribution, ultimately promotes FMT. Suggesting that exosomal miR-125a-5p may be a potential therapeutic target for silicosis.

The role of N6-methyladenosine methylation in PAHs-induced cancers.

Polycyclic aromatic hydrocarbons (PAHs), which are a wide range of environmental toxicants, may act on humans through inhalation, ingestion, and skin contact, resulting in a range of toxic reactions. Epidemiological studies showed that long-term exposure to PAHs in the occupational and living environment results in a substantial rise in the incidence rate of many cancers in the population, so the prevention and treatment of these diseases have become a major worldwide public health problem. N6-methyladenosine (m6A) modification greatly affects the metabolism of RNA and is implicated in the etiopathogenesis of many kinds of diseases. In addition, m6A-binding proteins have an important role in disease development. The abnormal expression of these can cause the malignant proliferation, migration, invasion, and metastasis of cancers. Furthermore, a growing number of studies revealed that environmental toxicants are one of the cancer risk factors and are related to m6A modifications. Exposure to environmental toxicants can alter the methylation level of m6A and the expression of the m6A-binding protein, thus promoting the occurrence and development of cancers through diverse mechanisms. m6A may serve as a biomarker for early environmental exposure. Through the study of m6A, we can find the health injury early, thus providing a new sight for preventing and curing environmental health-related diseases.

Changes in serum TIM-3 and complement C3 expression in workers due to Mn exposure.

Mn (Manganese, Mn) is an essential trace element involved in various biological processes such as the regulation of immune, nervous and digestive system functions. However, excessive Mn exposure can lead to immune damage. Occupational workers in cement and ferroalloy manufacturing and other related industries are exposed to low levels of Mn for a long time. Mn exposure is one of the important occupational hazards, but the research on the effect of Mn on the immune system of the occupational population is not complete, and there is no reliable biomarker. Therefore, this study aimed to evaluate the immunotoxicity of Mn from the soluble immune checkpoint TIM-3 (T-cell immunoglobulin and mucin containing protein 3, TIM-3) and complement C3. A total of 144 Mn-exposed workers were recruited from a bus manufacturing company and a railroad company in Henan Province. An inductively coupled plasma mass spectrometer was used to detect the concentration of RBC Mn (Red blood cell Mn, RBC Mn), and ELISA kits were used to detect serum complement C3 and TIM-3. Finally, the subjects were statistically analyzed by dividing them into low and high Mn groups based on the median RBC Mn concentration. We found that Mn exposure resulted in elevated serum TIM-3 expression and decreased complement C3 expression in workers; that serum TIM-3 and complement C3 expression showed a dose-response relationship with RBC Mn; and that the mediating effect of complement C3 between RBC Mn and TIM-3 was found to be significant. The above findings indicate that this study has a preliminary understanding of the effect of Mn exposure on the immune system of the occupational population exposed to Mn, and complement C3 and TIM-3 may be biomarkers of Mn exposure, which may provide clues for the prevention and control of Mn occupational hazards.

Predictive value of serum ß2-microglobulin in cardiac valve calcification in maintenance hemodialysis patients.

Background: Cardiac valve calcification (CVC) is associated with adverse cardiovascular events. We studied the risk factors of CVC in maintenance hemodialysis (MHD) patients and the value of serum ß2-microglobulin (ß2-MG) levels in predicting the incidence of CVC. ß2-MG is a middle molecular weight toxin. In recent years, researchers found that elevated blood ß2-MG was associated with coronary, thoracic, and abdominal aortic calcifications with significant correlations. ß2-MG has been emerging as a strong biomarker for cardiovascular mortality in uremic patients but its role in CVC is not well studied. This study looked specifically at CVC occurrence in relation to ß2-MG for MHD patients. Methods: Patients who underwent MHD for more than 3 months in the First People's Hospital of Nantong City from November 2012 to November 2019 with complete available data were included in the study. The patients were divided into the CVC group and the non-CVC group. The general information and clinical laboratory indicators of the patients were collected in a retrospective manner. We analyzed the risk factors for developing CVC in MHD patients using binary logistic regression method. Receiver operating characteristic (ROC) curves were used to calculate the cut-off value of ß2-MG for predicting CVC. The decision tree (DT) method was used to classify and explore the probability of CVC in patients with MHD. Results: The ß2-MG in the CVC group was significantly higher than that in the non-CVC group (t=6.750, P<0.001). Multivariate binary logistic regression analysis showed that gender, age, serum ß2-MG, and hemodialysis (HD) adequacy (Kt/V urea) were independent risk factors for CVC in MHD patients. ROC analysis showed that a ß2-MG value of 25 µg/L was the best cut-off point for predicting CVC in MHD patients. According to binary logistic regression analysis, the ß2-MG ≥25 µg/L group was 3.39 times more likely to develop CVC than the ß2-MG <25 µg/L group [odds ratio (OR), 3.39; 95% confidence interval (CI), 1.63-7.06; P=0.001]. The DT model determined that serum ß2-MG ≥25 µg/L and age >69 years were important determinants for predicting CVC in MHD patients. Conclusions: Serum ß2-MG in MHD patients has a positive correlation with the severity and occurrence of CVC.

Recycling waste dolomite powder in cement paste: Early hydration process, microscale characteristics, and life-cycle assessment.

Waste dolomite powder (WDP) is a byproduct obtained from dolomite quarries during the preparation of dolomite products. To study the re-utilisation of WDP, an eco-friendly cement-based material was prepared using WDP as a micro-aggregate. The effects of WDP on the early hydration process, microscale characteristics, and life-cycle assessment of cement paste are discussed in this study. The isothermal calorimetry results showed that the incorporating WDP in cement paste accelerated the early hydration process of cement according to the degree of reaction. In this case, the setting time of the cement pastes with WDP was shortened, and the early compressive strength was significantly improved. The results of X-ray diffraction and scanning electron microscopy analysis at early curing ages (1 and 3 d) showed changes in the peak intensity of ettringite and portlandite and a denser microstructure. Mercury intrusion porosimetry tests showed that the middle and large capillary pores were refined by the nucleation and filling effects of WDP. Based on environmental and economic evaluations, the utilisation of WDP reduced energy consumption, CO2 emissions, and economic costs. Compared to the sample without WDP, the energy consumption, CO2 emissions, and economic cost indices were 42 %, 42.69 %, and 39.4 % lower, respectively. Our results may provide valuable references for the re-utilisation of WDP in low-carbonation cement-based materials.

Peer feedback and Chinese medical students' English academic writing development: a longitudinal intervention study.

BACKGROUND: Studies have documented that utilizing peer feedback can enhance students' English academic writing skills. Little is known, however, about the effects of incorporating peer feedback to enhance English as a second language (L2) medical students' academic writing performance. METHODS: This longitudinal interventional study examines Chinese medical students' English academic writing skills development via peer feedback in four parallel classes over an 18-week semester between the experimental and control groups (n = 124). RESULTS: Significant increases in the experimental group's performance in the post-test were found after 18-week instructions (pre- vs. post-test: overall score, p < .001; task response, p < .001; coherence and cohesion, p < .001; lexical resource, p < .001; grammatical range and accuracy, p < .001), and the effects were retained in the delayed post-test 6 weeks later (post- vs. delayed post-test: overall score, p = .561; task response, p = .585; coherence and cohesion, p = .533; lexical resource, p = .796; grammatical range and accuracy, p = .670). Little improvement was found in the control group in the post-test (pre- vs. post-test: overall score, p = .213; task response, p = .275; coherence and cohesion, p = .383; lexical resource, p = .367; grammatical range and accuracy, p = .180) or the delayed post-test (post- vs. delayed post-test: overall score, p = .835; task response, p = .742; coherence and cohesion, p = .901; lexical resource, p = .897; grammatical range and accuracy, p = .695). Between-group comparisons indicate that the experimental group outperformed the control group in the post- and the delayed post-tests, as shown in their overall score and scores on the four components. CONCLUSIONS: Incorporating peer feedback into process-oriented medical English writing classroom teaching can effectively enhance Chinese medical students' English academic writing skills over time, while the traditional product-oriented writing instructions had little help in improving Chinese medical students' academic writing skills. This longitudinal intervention study develops our understanding of the effectiveness of peer feedback in L2 academic writing pedagogy. It offers instructional implications for L2 writing teachers to teach English academic writing among medical students in China and beyond. Limitations and suggestions for future studies are discussed.