MiR-7a ameliorates spinal cord injury by inhibiting neuronal apoptosis and oxidative stress

OBJECTIVE

The aim of this study was to investigate the therapeutic effect of microRNA-7a (miR-7a) on spinal cord injured rats and to explore its underlying mechanism in vivo.

MATERIALS AND METHODS

The spinal cord injury (SCI) model was first established in adult rats. The epicenter of the lesion was treated with miR-7a mimics via intrathecal injection. The Basso-Beattie-Bresnahan (BBB) locomotor rating scale was used to evaluate the functional recovery of hindlimbs in rats within 4 weeks following SCI. Western blotting and qPCR were utilized to detect the apoptosis and oxidative stress in rats treated with or without miR-7a. In addition, the neuron survival and neuro-filament amount were determined using immunofluorescence.

RESULTS

After SCI and miR-7a treatment, the locomotor recovery of treated rats was significantly improved when compared with rats without treatment. The mitochondrial disorder and cell death were significantly reduced in miR-7a treated rats. Meanwhile, the nuclear transcription factor-κB (NF-κB) pathway was significantly reduced as well. Contrarily, the expression of anti-apoptotic protein Bcl-2 and NF-κB inhibitor I-κB was remarkably elevated in miR-7a treated rats. In addition, up-regulation of miR-7a rescued neurons and maintained the neural structure.

CONCLUSIONS

The up-regulation of miR-7a alleviated the injury-induced oxidative stress and inhibited apoptosis by down-regulating NF-κB pathway in SCI rats.

Effects of alirocumab on carotid plaque lipid content and inflammation: a time course study using serial vessel wall imaging

Background

PCSK9 inhibition has emerged as a potent pharmaceutical approach to lowering LDL cholesterol (LDL-C). Monoclonal anti-PCSK9 antibodies have been shown in recent clinical trials to reduce cardiovascular events in patients with atherosclerotic cardiovascular disease, but the underlying mechanisms are not fully understood. Meanwhile, circulatory inflammation markers were not reduced with PCSK9 inhibitors, thus their effects on plaque inflammation remain elusive. Vessel wall imaging with magnetic resonance (VW-MRI) has enabled serial monitoring of changes in carotid plaque lipid content and inflammation noninvasively that correlates with coronary and carotid vascular events.

Purpose

Using serial VW-MRI, we studied the effects and time course of PCSK9 inhibition with alirocumab on carotid plaque lipid content and inflammation.

Methods

Patients with LDL-C ≥70 mg/dl on ≤70 mg per week atorvastatin or an equivalent (due to statin intolerance or treating-physician discretion) and soft carotid plaque(s) identified on ultrasound underwent carotid VW-MRI. Those with confirmed lipid-rich plaque(s) on VW-MRI received alirocumab (150 mg subcutaneously every other week) and were re-scanned at 3, 6, and 12 months after treatment. Carotid VW-MRI included pre- and post-contrast images for measuring percent lipid-rich necrotic core volume (%LRNC) and dynamic contrast-enhanced images for measuring the extravasation rate of gadolinium contrast (Ktrans, reflecting tissue blood flow, endothelial surface area, and microvessel permeability), a marker of plaque inflammation. The co-primary endpoints were changes in %LRNC and Ktrans at 12 months from baseline.

Results

Of 31 patients enrolled, 27 completed the study (mean age: 69±9; male: 67%; on statins and/or ezetimibe: 41%; median LDL-C: 120 mg/dl [interquartile range: 99, 158]). Alirocumab induced a 59% reduction in LDL-C (p<0.001) on average at 3 months to a median of 54 mg/dl (interquartile range: 29, 69), which was maintained at later time points. From 9.8% at baseline, %LRNC was progressively reduced to 8.4% at 3 months, 7.5% at 6 months, and 7.2% at 12 months, representing a rapid 14% reduction (p=0.032) at 3 months and a total reduction of 20% (p=0.019) at 12 months. From 0.07±0.02 min-1 at baseline, Ktrans was not reduced at 3 or 6 months but was significantly reduced by 17% (p=0.029) at 12 months to 0.06±0.02 min-1. No significant changes in lumen or wall area were observed during the study period.

Conclusions

Serial VW-MRI documented plaque-stabilizing effects of PCSK9 inhibition with alirocumab, including plaque delipidation and attenuation of plaque inflammation. The reduction in plaque lipid content was apparent as early as 3 months. The reduction in Ktrans was not seen until 12 months of treatment and may indicate a later effect on microvascular structure and/or function. This observation represents the earliest time course of plaque morphology modification by non-statin therapy reported to date.

Funding Acknowledgement

Type of funding source: Private grant(s) and/or Sponsorship. Main funding source(s): The study was funded by an investigator-initiated grant from Regeneron and Sanofi.

Time-dependent Microhardness Gradients of Self-adhesive Resin Cements Under Dual- and Self-curing Modes

CLINICAL RELEVANCE

Acid-functional monomers in self-adhesive resin cements may decrease their self-curing polymerization ability. Light irradiation optimizes polymerization performance.

SUMMARY

Purpose: The aim of this study was to investigate Knoop microhardness of self-adhesive resin cements under dual- and self-curing modes in simulated canals for describing the polymerization behavior.Methods and Materials: Slots in lightproof silicone cylinders with one open end were filled with the following eight materials: a traditional resin cement (Duolink), a core build-up resin material (MultiCore Flow), and six self-adhesive resin cements (RelyX Unicem 2, G-Cem Automix, Maxcem, Biscem, Multilink Speed, and PermaCem 2.0). The resins were exposed to light through the open end and then stored in a lightproof box. The Knoop hardness gradient for each resin was measured after 1 hour and 120 hours. Surface readings were obtained at 1-mm intervals from 1 mm to 10 mm away from the open ends. The data were analyzed by two-way analysis of variance and the Student-Newman-Keuls test (α=0.05).Results: All the resin materials had stable Knoop hardness numbers (KHNs) at a certain depth; their KHNs in the self-curing mode did not change (p>0.05). The region above this certain depth was regarded as having undergone the dual-curing mode, and the KHN decreased gradually with depth (p<0.05). Between 1 and 120 hours postexposure, the ratio of the KHN at a 5-mm depth (self-cured) to that at a 1-mm depth (dual-cured) increased in Duolink and MultiCore Flow. However, the ratios of the six adhesive resin cements varied.Conclusion: Without light, most self-adhesive resin cements differed from traditional dual-cured resin materials in terms of Knoop micro-hardness, and they had a lesser capacity for chemical-induced curing.

Literature mapping: association of microscopic skin microflora and biomarkers with macroscopic skin health

Associations between skin microbes or biomarkers and pathological conditions have been reported in the literature. However, there is a lack of clarity on the interaction between the coexistence of common skin microbes with skin physiology and subsequent development of clinical symptoms, and the role of biomarkers in mediating these changes before the development of skin disease. In this review, we aim to identify areas in which extensive research for the studied factors has already been conducted, and which research areas are under-represented. The SciFinder database was searched for articles containing key words including specific skin microbes, biomarkers, skin physiology and diseases from the beginning of the SciFinder data record to 26 April 2016, and we included an additional relevant recent publication from our group. Among the 8000 + articles selected, the frequency of keyword pairs between two roles [microscopic markers (microflora or biomarkers) and reactions (skin physiology or clinical symptoms, or skin disease)] was investigated. Associated research between the individual factors such as skin microflora or biomarkers (chosen based on our earlier publication) and specific biophysical parameters, symptoms or skin disease was identified. The present research heatmap emphasizes the significance of a structured review of research on concerned factor associations to identify early/subclinical clues that can be used to prevent progression to overt skin disease with the help of precise skin care or early intervention, as indicated by skin microflora, biomarkers and an interactive skin biophysics profile. The findings provide a novel approach to explore such associations and may guide future research directed towards predicting disease from early/subclinical symptoms.

Arabidopsis CK2 family gene CKB3 involved in abscisic acid signaling

CKB3 is a regulatory (beta) subunit of CK2. In this study Arabidopsis thaliana homozygous T-DNA mutant ckb3 was studied to understand the role of CKB3 in abscisic acid (ABA) signaling. The results shown: CKB3 was expressed in all organs and the highest expression in the seeds, followed by the root. During seed germination and root growth the ckb3 mutant showed reduced sensitivity to ABA. The ckb3 mutant had more stomatal opening and increased proline accumulation and leaf water loss. The expression levels of number of genes in the ABA regulatory network had changed. This study demonstrates that CKB3 is an ABA signaling-related gene and may play a positive role in ABA signaling.

Intraindividual Variation and Personal Specificity of Salivary Microbiota

Salivary microbiota is a typical habitat of the human microbiome. This study intended to use salivary microbiota as a model aiming to systematically address the influence of collection methods and temporal dynamics on the human microbiota compared to personal specificity. We carried out a supervised short-term longitudinal study to evaluate the influence of the change of collection methods and sampling time point on salivary microbiota in 10 systemically and orally healthy individuals with certain confounding factors (sex, oral and general health state, medication history, physical exercise, diet, and oral hygiene behavior) controlled before and during the sampling period. The microbial profiles were analyzed by 16S rDNA V3 to V4 hypervariable region amplicon sequencing. The taxonomic structure represented by the dominant species and the weighted UniFrac distance algorithm were used to demonstrate the individual specificity and the intraindividual variation introduced by the change of collection method and sampling time point. The findings suggested individual specificity existed in salivary microbiota from individuals with similar oral and general health status. The intraindividual variation brought by the change of collection method or sampling time point might introduce remarkable perturbation with the personal specificity. Insights into the intraindividual variation and personal specificity of salivary microbiota will enhance our understanding in salivary microbiota-related research. We recommend keeping collection conditions consistent within a study to avoid interference brought by the sampling. The strategy of repeated sampling at multiple time points as representative samples, as well as thorough interpretation of the complex relationships and causality between microbiome composition and disease without the interference of temporal dynamics, is optimal for research exploring the relationship between the salivary microbiome and disease.

Signal of Carotid Intraplaque Hemorrhage on MR T1-Weighted Imaging: Association with Acute Cerebral Infarct

BACKGROUND AND PURPOSE

Identifying the mere presence of carotid intraplaque hemorrhage would be insufficient to accurately discriminate the presence of acute cerebral infarct. We aimed to investigate the association between signal intensity ratios of carotid intraplaque hemorrhage on T1-weighted MR imaging and acute cerebral infarct in patients with hemorrhagic carotid plaques using MR vessel wall imaging.

MATERIALS AND METHODS

Symptomatic patients with carotid intraplaque hemorrhage were included. The signal intensity ratios of carotid intraplaque hemorrhage against muscle on T1-weighted, TOF, and MPRAGE images were measured. The acute cerebral infarct was determined on the hemisphere ipsilateral to the carotid intraplaque hemorrhage. The association between signal intensity ratios of carotid intraplaque hemorrhage and acute cerebral infarct was analyzed.

RESULTS

Of 109 included patients (mean, 66.8 ± 9.9 years of age; 96 men), 40 (36.7%) had acute cerebral infarct. Patients with acute cerebral infarct had significantly higher signal intensity ratios of carotid intraplaque hemorrhage on T1-weighted images than those without (Median, 1.44; 25-75 Percentiles, 1.14-1.82 versus Median, 1.27; 25-75 Percentiles, 1.06-1.55, P = .022). Logistic regression analysis revealed that the signal intensity ratio of carotid intraplaque hemorrhage on T1-weighted images was significantly associated with acute cerebral infarct before (OR, 4.08; 95% CI, 1.34-12.40; P = .013) and after (OR, 3.34; 95% CI, 1.08-10.31; P = .036) adjustment for clinical confounding factors. However, this association was not significant when further adjusted for occlusion of the carotid artery (P = .058) and volumes of intraplaque hemorrhage and lipid-rich necrotic core (P = .458).

CONCLUSIONS

The signal intensity ratio of carotid intraplaque hemorrhage on T1-weighted images is associated with acute cerebral infarct in symptomatic patients with carotid hemorrhagic plaques. This association is independent of traditional risk factors but not of the size of plaque composition. The possibility of applying T1 signals of carotid intraplaque hemorrhage to predict subsequent cerebrovascular ischemic events needs to be prospectively verified.

Generation of nonlinear internal waves by flow over topography: Rotational effects

We use the forced Ostrovsky equation to investigate the generation of internal waves excited by a constant background current flowing over localized topography in the presence of background rotation. As is now well known in the absence of background rotation, the evolution scenarios fall into three cases, namely subcritical, transcritical, and supercritical. Here an analysis of the linearized response divides the waves into steady and unsteady waves. In all three cases, steady waves occur downstream but no steady waves can occur upstream, while unsteady waves can arise upstream only when there is a negative minimum of the group velocity. The regions occupied by the steady and unsteady waves are determined by their respective group velocities. When the background current is increased, the wave number of the steady waves decreases. In addition, the concavity (canyon or sill), the topographic width, and the relative strength of the rotation play an important role in the generation mechanism. Nonlinear effects modulate the wave amplitude and lead to the emergence of coherent wave packets. All these findings are confirmed by numerical simulations.

CKB1 regulates expression of ribosomal protein L10 family gene and plays a role in UV-B response

Plastid casein kinase 2 (CK2), which is a major Ser/Thr-specific enzyme in higher organisms, plays an essential role in plant development and diverse abiotic stresses. CKB1 is a regulatory subunit beta of CK2. To expand our understand of functions of the CKB1 gene in Arabidopsis thaliana, protein changes among wild-type (WT) and CKB1 gain- and loss-of-function mutants were compared. Proteins extracted from the CKB1 knockout mutant and overexpressing mutant were compared with Col-0 plants using 2D-PAGE. Proteins regulated by CKB1 were identified with matrix-assisted laser desorption ionisation time-of-flight/time-of-flight mass spectrometry (MALDI-TOF/TOF), and its transcript was verified by qRT-PCR. Bioinformatics analysis, including gene ontology and protein-protein interaction analysis, were employed. The results of mass spectra and bioinformatics analysis suggest that CKB1 may have functions in regulation of the ribosomal protein L10 (RPL10) family and is involved in ultraviolet-B (UV-B) response. Furthermore, qRT-PCR verification showed CKB1 expression was up-regulated by UV-B stress. The expression levels of five genes in the RPL10 family were reduced in the ckb1 T-DNA insertion mutants, whereas they increased in the CKB1 overexpressing mutants under both normal conditions and UV-B treatment. In conclusion, CKB1 has important functions in UV-B radiation stress. Our study implies that CKB1 positively regulates UV-B radiation stress signalling, possibly through modulating expression of the RPL10 family.

[Pre- and post-treatment changes of gingvitis-associated peptidomic profiles in the saliva and gingival crevicular fluid by mass spectrometry]

Objective: To explore peptidomic changes of peptides in saliva and gingival crevicular fluid (GCF) before and after treatment of gingivitis. Methods: From January 2017 to September 2017, seventeen participants at the age of 24-62 (6 males and 11 females) at Department of Preventive Dentistry, Peking University School and Hospital of Stomatology with gingivitis were recruited in the present study. Their clinical parameters were measured and recorded. Saliva and GCF samples were collected from each of the participants at the baseline and 7 days after ultrasonic supragingival scaling, respectively. Matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS) was employed to detect the changes of peptidomic profiles, while ano-liquid chromatography-electrospray ionization-tandem mass spectrometry (nano-LC/ESI-MS/MS) was performed to identify the possible proteins from which the peptides might derive. Results: Initially, four peptide peaks [mass-to-charge ratio (m/z) values: 1 030.6, 1 043.4, 1 053.4 and 1 064.6] were screened out exhibiting a decreasing trend after treatment (P<0.05). Besides, five peptide peaks from gingival crevicular fluid (P<0.05) exhibited differential expression, among which 1 055.5 and 1 168.3 demonstrating a decrease after treatment, while 3 363.7, 3 480.9 and 3 489.5 increased overtime. Certain positive correlations were detected between some peptides and clinical parameters. Principle component analysis using the above mentioned peptide peaks showed a distinct distribution before and after treatment and peptides from GCF showed a slightly better capacity to discriminate patients before and after treatment. The peptides with m/z values of 1 055.5 in GCF and 1 064.6 in saliva were identified to be segments of serum albumin and complement C3, respectively. Conclusions: Several differentially expressed peptides were detected in saliva and GCF by MALDI-TOF MS, exhibiting the potentiality to act as biomarkers in gingivitis patients.

Two linked TBXT (brachyury) gene polymorphisms are associated with the tailless phenotype in fat-rumped sheep

T‐box transcription factor T (TBXT), encoding the brachyury protein, is an embryonic nuclear transcription factor involved in mesoderm formation and differentiation. Previous studies indicate that TBXT mutations are responsible for the tailless or short‐tailed phenotype of many vertebrates. To verify whether the tailless phenotype in fat‐rumped sheep is associated with TBXT mutations, exon 2 of the TBXT gene for 301 individuals belonging to 13 Chinese and Iranian sheep breeds was directly sequenced. Meanwhile, 380 samples were used to detect the genotypes of the candidate variations by mapping to their reads databases in the Sequence Read Archive repository of GenBank. The results showed that one missense mutation, c.334G>T (GGG>TGG) with a completely linked synonymous variant c.333G>C (CCG>CCC) was found to be associated with the ‘tailless’ characteristic in typical fat‐rumped sheep breeds. The c.334G>T transversion led to the conversion of glycine to tryptophan at the 112th amino acid in the T‐box domain of the brachyury protein. In addition, crossbreeding experiments for long‐tailed and tailless sheep showed that CT/CT allele of nucleotides (nt) 333 and 334, a recessive mutation, would cause sheep tails to be shorter, suggesting that these two linked variants at nucleotides 333 and 334 in TBXT are probably causative mutations responsible for the tailless phenotype in sheep.

Carotid Plaque CTA Analysis in Symptomatic Subjects with Bilateral Intraparenchymal Hemorrhage: A Preliminary Analysis

BACKGROUND AND PURPOSE

The presence of IPH is considered the most dangerous feature because it is significantly associated with clinical ipsilateral cerebrovascular events. Our aim was to explore the characterization of plaque with CT in symptomatic subjects with bilateral intraplaque hemorrhage.

MATERIALS AND METHODS

Three-hundred-forty-three consecutive patients with recent anterior circulation ischemic events (<2 weeks) and CT of the carotid arteries (performed within 14 days of the cerebrovascular event) evaluated between June 2012 and September 2017 were analyzed for plaque volume composition to identify all subjects with bilateral intraplaque hemorrhage. Plaque volume was semiautomatically measured, and tissue components were classified according to the attenuation values such as the following: calcified (for values of ≥130 HU), mixed (for values of ≥60 and <130 HU), lipid (for values of ≥25 and <60 HU), and intraplaque hemorrhage (for values of <25 HU). Twenty-one subjects (15 men; mean age, 70 ± 11 years; range, 44-87 years) had bilateral intraplaque hemorrhage and were included in the analysis.

RESULTS

Volume measurement revealed significantly larger plaques on the symptomatic side compared with the asymptomatic one (mean, 28 ± 9 versus 22 ± 8 mm, P = .007). Intraplaque hemorrhage volume and percentage were also significantly higher in the plaque ipsilateral to the cerebrovascular event (P < .001 and < .001, respectively). The volume of other plaque components did not show a statically significant association except for lipid and lipid + intraplaque hemorrhage percentages (23% versus 18% and 11% versus 15%), which were significantly different between the symptomatic and the asymptomatic sides (.016 and .011, respectively). The intraplaque hemorrhage/lipid ratio was higher on the symptomatic side (0.596 versus 0.171, P = .001).

CONCLUSIONS

In patients with bilateral intraplaque hemorrhage and recent ischemic symptoms, the plaque ipsilateral to the symptomatic side has significantly larger volume and a higher percentage of intraplaque hemorrhage compared with the contralateral, asymptomatic side.

Expression of duck hepatitis A virus type 1 VP3 protein mediated by avian adeno-associated virus and its immunogenicity in ducklings

The avian adeno-associated virus (AAAV) is a replication-defective nonpathogenic virus that has been proved to be useful as a viral vector in gene delivery. In this study, the feasibility of AAAV for transgenic expression of duck hepatitis A virus (DHAV) VP3 structural protein and its ability to induce protective immunity in ducklings was assessed. The recombinant AAAV (rAAAV-VP3) expressing the VP3 protein was prepared by co-infection of Sf9 cells with recombinant baculovirus (rBac-VP3) containing VP3 gene flanked by inverted terminal repeats (ITRs) of AAAV and the other two recombinant baculovirus expressing AAAV functional and structural genes, respectively. The generation of rAAAV-VP3 was demonstrated by electron microscopy, immunofluorescence assay, and western blot analysis. One day old ducklings were inoculated with rAAAV-VP3 or commercial attenuated vaccine and then challenged with DHAV-1 strain SH two weeks post vaccination. Anti-DHAV-1 antibodies were detected in all vaccinated groups by ELISA, and the titers between the rAAAV-VP3 group and the attenuated vaccine group were not statistically significant. Real time RT-PCR analysis showed that the virus copy numbers in the livers of the PBS control group were significantly higher than that of the rAAAV-VP3 and attenuated vaccine groups. In conclusion, we demonstrated that the VP3 expression mediated by rAAAV in ducklings could induce protective immunity against DHAV challenge, and this could be a candidate vaccine for the control of duck viral hepatitis. Keywords: avian adeno-associated virus; duck hepatitis A virus; VP3 gene; immunogenicity.

[Comparison of different scoring systems in prognosis evaluation of acute poisoning]

Objective: To compare the predictive value of PSS, APACHEII, SAPSII and SOFA in the prognosis evaluation of acute poisoning. Methods: Clinical data (including PSS score, APACHEII score, SAPSII score and SOFA score, within 24 hours after admission) of 231 acute poisoning patients admitted to the emergency intensive care unit EICU of our hospital from January 2015 to October 2016 was retrospectively analyzed. The patients were divided into the survival group and the dead group according to the 28-day clinical outcomes, comparing the differences of clinical data in each group. To analyze the correlation between PSS score, APACHEII score, SAPSII score and SOFA score in each group, comparing the value and the area under the ROC curve of four scoring systems and evaluate the predictive value of the four scoring systems. Results: Comparing with the survival group and the dead group, PSS score, APACHEII score, SAPSII score and SOFA score were significantly different (P<0.01) . PSS score, APACHEII score, SAPSII score and SOFA score were significantly positive correlation (P<0.01) , the area under the ROC curve (AUC) of the four scoring systems were 0.833, 0.887, 0.843 and 0.843 respectively. The area under the ROC curve (AUC) of APACHEII score was higher than PSS score, SAPSII score and SOFA score, the difference was statistically significant (z=2.351, 2.317, 2.217; P=0.019, 0.021, 0.027) , there was no significant difference in the area (AUC) between the three scoring curves (P>0.05) . The cutoff value (cut-off) , sensitivity, specificity and accuracy rates of PSS score, APACHEII score, SAPSII score and SOFA score were (2.5, 93.1%, 50.9%, 61.5%) , (14.5, 82.8%, 75.7%, 77.48%) , (31.5, 77.6%, 76.90%, 77.08%) , (5.5, 77.60%, 74.60%, 75.35%) . Conclusion: PSS score, APACHEII score, SAPSII score and SOFA score can evaluate the prognosis of patients with acute poisoning, but the APACHEII score is better than the other three scoring systems in evaluating the prognosis for its evaluation ability and accuracy rate.

Proteomic analysis of hypothalamus and liver proteins affected by dietary l-arginine supplementation in laying hens

The goal of this study was to investigate the influence of l-arginine (l-Arg) supplementation on diet-induced changes in hypothalamus and liver proteome of laying hens. Layers were fed either an isonitrogenous control diet or a l-Arg diet. The test included a 2-week acclimation period and a 12-week experimental period. Eight layers per group were sacrificed at terminal of the experiment underwent 12 fasting. Blood and tissue samples of hypothalamus and liver were collected for further analysis. The levels of serum nitric oxide and hypothalamus neuropeptide Y of layers in l-Arg group were increased in comparison with those in control group. Quantitative proteomic analyses showed that a total of 3,715 hypothalamus proteins (235 differentially expressed) and 3797 liver proteins (373 differentially expressed) were detected between control and l-Arg-fed groups. A further enriched Gene Ontology term analysis of proteins found that 17 hypothalamus proteins (11 upregulated and six downregulated) and 29 liver proteins (14 upregulated and 15 downregulated) were altered differentially between the two groups. Our findings revealed the changes in metabolic and hormonal signals in central nervous system and peripheral tissues by responding to l-Arg feeding, which provides a possible way to gain a better understanding of l-Arg function in laying hens.

Effects of dietary L-arginine levels on small intestine protein turnover and the expression of genes related to protein synthesis and proteolysis of layers

The aim of this study was to test the effects of dietary L-arginine (Arg) levels on protein turnover in the small intestine and the expression of genes related to protein synthesis and proteolysis of laying hens. Xinyang Black commercial laying hens (n = 864, aged 217 d) were randomly distributed to 6 treatments with 4 replicates of 36 birds. The dietary treatments were corn-corn gluten meal based diets containing 0.64, 0.86, 1.03, 1.27, 1.42 and 1.66% L-Arg, respectively. Fractional protein synthesis rate (FSR) and fractional protein gain rate (FGR) in the jejunum were the highest in the 1.27% L-Arg group. The mRNA expression of target of rapamycin (TOR), ribosomal protein S6 kinase 1 (S6K1), and eukaryotic initiation factor 4E-binding protein 1 (4E-BP1) in the duodenum reached the highest in the 1.27% L-Arg group, while the mRNA expression of 20S proteasome (20S) was the lowest in the 1.27% L-Arg group. The mRNA abundances of TOR and S6K1 in the jejunum were the highest in the 1.27% L-Arg group, while the mRNA expression of 20S was the lowest in the 1.27% L-Arg group, and the protein expression and phosphorylation levels of TOR in the 1.27% L-Arg group were higher than those in the 0.64% L-Arg group. These results indicate that the action of an appropriate level of dietary L-Arg to improve the protein synthesis of the small intestine involves up-regulating the protein expression and phosphorylation level of TOR in the jejunum accompanied by inhibiting the mRNA expression of 20S of laying hens.